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Title:
MULTI-COMPONENT FIBERS INCLUDING A CRYSTALLINE POLYOLEFIN AND A HYDROCARBON TACKIFIER RESIN, AND PROCESS FOR MAKING SAME
Document Type and Number:
WIPO Patent Application WO/2019/025942
Kind Code:
A1
Abstract:
Nonwoven fibrous webs including a multiplicity of (co)polymeric fibers made of a mixture including from about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin. A process for making the nonwoven fibrous webs includes heating the foregoing mixture to at least a Melting Temperature of the mixture to form a molten mixture, extruding this molten mixture through at least one orifice to form at least one filament, applying a gaseous stream to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers, and cooling the plurality of discrete, discontinuous fibers to a temperature below the Melting Temperature and collecting the discrete discontinuous fibers as a nonwoven fibrous web. The nonwoven fibrous webs exhibit a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

Inventors:
BATRA SAURABH (US)
DOTSETH COLBY W (US)
JOSEPH EUGENE G (US)
REN LIYUN (US)
TALWAR SACHIN (US)
ROMANO MICHAEL D (US)
BERRIGAN MICHAEL R (US)
Application Number:
IB2018/055684
Publication Date:
February 07, 2019
Filing Date:
July 30, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
3M INNOVATIVE PROPERTIES CO (US)
International Classes:
D04H1/4291; D01D5/088; D04H1/56
Foreign References:
US20150143653A12015-05-28
US20090264846A12009-10-22
US20120251771A12012-10-04
US5635290A1997-06-03
US20160002826A12016-01-07
Attorney, Agent or Firm:
BAKER, James A., et al. (Office of Intellectual Property CounselPost Office Box 3342, Saint Paul Minnesota, US)
Download PDF:
Claims:
C-4 PP 650 Y Same as C-2 Same as C-2

PP 650 Y/ OPPERA™ 100 Same as Same as

22

(95%/5% w/w) Example 9 Example 9

Same as Same as

23 PP 650 Y / OPPERA™ 100 (95%/5% w/w)

Example 9 Example 9

Same as Same as

24 PP 650 Y / OPPERA™ 100 (90%/ 10% w/w)

Example 10 Example 10

Same as Same as

25 PP 650 ΎΙ OPPERA™ 100 (85% 15% w/w)

Example 12 Example 12

Reference throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments" or "an embodiment," whether or not including the term "exemplary" preceding the term "embodiment," means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the certain exemplary embodiments of the present disclosure. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the certain exemplary embodiments of the present disclosure.

Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

While the specification has described in detail certain exemplary embodiments, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments.

Accordingly, it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth hereinabove. In addition, all numbers used herein are assumed to be modified by the term "about."

Furthermore, all publications and patents referenced herein are incorporated by reference in their entirety to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. Various exemplary embodiments have been described. These and other embodiments are within the scope of the following claims. What is claimed is:

1. A nonwoven fibrous web, comprising:

a plurality of (co)polymeric fibers comprising from about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1 % w/w to about 40% w/w of at least one hydrocarbon tackifier resin, wherein the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

2. The nonwoven fibrous web of claim 1 , wherein the at least one crystalline polyolefin

(co)polymer is selected from the group consisting of polyethylene, isotactic polypropylene, syndiotactic polypropylene, isotactic polybutylene, syndiotactic polybutylene, poly-4-methyl pentene, and mixtures thereof.

3. The nonwoven fibrous web of claim 2, wherein the at least one crystalline polyolefin (co)polymer exhibits a Heat of Fusion measured greater than 50 Joules/g.

4. The nonwoven fibrous web of claim 1 , wherein the at least one hydrocarbon tackifier resin is a saturated hydrocarbon.

5. The nonwoven fibrous web of claim 1, wherein the at least one hydrocarbon tackifier resin is selected from the group consisting of Cs piperylene derivatives, C9 resin oil derivatives, and mixtures thereof.

6. The nonwoven fibrous web of claim 1, wherein the at least one hydrocarbon tackifier resin makes up from 2% to 40% by weight of the (co)polymeric fibers.

7. The nonwoven fibrous web of claim 6, wherein the at least one hydrocarbon tackifier resin makes up from 5% to 30% by weight of the (co)polymeric fibers.

8. The nonwoven fibrous web of claim 7, wherein the at least one hydrocarbon tackifier resin makes up from 7% to 20% by weight of the (co)polymeric fibers.

9. The nonwoven fibrous web of claim 1, wherein the plurality of (co)polymeric fibers exhibit a mean Actual Fiber Diameter of from about 100 nanometers to about 1 micrometer, inclusive, as determined using Scanning Electron Microscopy.

10. The nonwoven fibrous web of claim 9, wherein the plurality of (co)polymeric fibers exhibits a mean Effective Fiber Diameter of between about 1 micrometer to about 20 micrometers.

11. The nonwoven fibrous web of claim 1 , further comprising between 0 to about 30% of at least one plasticizer.

12. The nonwoven fibrous web of claim 11, wherein the at least one plasticizer is selected from the group consisting of oligomers of Cs to C olefins, and mixtures thereof. 13. The nonwoven fibrous web of claim 1, wherein the nonwoven fibrous web exhibits a

Maximum Load in the Machine Direction of at least 5 Newtons as measured using the Tensile Strength Test.

14. The nonwoven fibrous web of claim 1, wherein the nonwoven fibrous web exhibits a Basis Weight of 1 gsm to 400 gsm.

15. The nonwoven fibrous web of claim 14, wherein the nonwoven fibrous web exhibits a Basis Weight of 1 gsm to 50 gsm. 16. A process for making a nonwoven fibrous web, comprising:

a) heating a mixture of about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1 % w/w to about 40% w/w of at least one hydrocarbon tackifier resin to at least a Melting Temperature of the mixture to form a molten mixture;

b) extruding the molten mixture through at least one orifice to form at least one filament; c) applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers; and

d) cooling the plurality of discrete discontinuous fibers to a temperature below the Melting Temperature of the molten mixture to form a nonwoven fibrous web, wherein at least one of the crystalline polyolefin (co)polymer or the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

17. The process of claim 16, wherein applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers is accomplished using a process selected from the group consisting of melt -blowing, gas jet fibrillation, and combinations thereof.

18. The process of claim 16, further comprising at least one of addition of a plurality of staple fibers to the plurality of melt -blown fibers, or addition of a plurality of particulates to the plurality of melt-blown fibers.

19. The process of claim 16, further comprising collecting the plurality of discrete discontinuous fibers as the nonwoven fibrous web on a collector.

20. The process of claim 19, further comprising processing the collected nonwoven fibrous web using a process selected from the group consisting of autogenous bonding, through-air bonding, electret charging, embossing, needle-punching, needle tacking, hydroentangling, or a combination thereof.

Description:
FIBERS INCLUDING A CRYSTALLINE POLYOLEFIN AND A HYDROCARBON TACKIFIER RESIN, AND PROCESS FOR MAKING SAME

TECHNICAL FIELD

The present disclosure relates to (co)polymeric fibers including a crystalline polyolefin

(co)polymer and a hydrocarbon tackifier resin, and more particularly, to nonwoven fibrous webs including such fibers, and methods for preparing such webs.

BACKGROUND

Melt-blowing is a process for forming nonwoven fibrous webs of thermoplastic

(co)polymeric fibers. In a typical melt-blowing process, one or more thermoplastic (co)polymer streams are extruded through a die containing closely arranged orifices and attenuated by convergent streams of high-velocity hot air to form micro-fibers which are collected to form a melt-blown nonwoven fibrous web.

Thermoplastic (co)polymers commonly used in forming conventional melt -blown nonwoven fibrous webs include polyethylene (PE) and polypropylene (PP). Melt-blown nonwoven fibrous webs are used in a variety of applications, including acoustic and thermal insulation, filtration media, surgical drapes, and wipes, among others.

SUMMARY

Briefly, in one aspect, the present disclosure describes a nonwoven fibrous web including a multiplicity of (co)polymeric fibers including from about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1 % w/w to about 40% w/w of at least one hydrocarbon tackifier resin, wherein the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

In some exemplary embodiments, the at least one crystalline polyolefin (co)polymer is selected from polyethylene, isotactic polypropylene, syndiotactic polypropylene, isotactic polybutylene, syndiotactic polybutylene, poly-4-methyl pentene), and mixtures thereof. In certain presently preferred embodiments, the at least one crystalline polyolefin (co)polymer exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g. In some such presently preferred embodiments, the at least one crystalline polyolefin (co)polymer is selected to be isotactic polypropylene, syndiotactic polypropylene, and mixtures thereof.

In certain exemplary embodiments, the at least one hydrocarbon tackifier resin is a saturated hydrocarbon. In certain presently preferred exemplary embodiments, the at least one hydrocarbon tackifier resin is selected from Cs piperylene derivatives, C9 resin oil derivatives, and mixtures thereof. In additional presently preferred exemplary embodiments, the at least one hydrocarbon tackifier resin makes up from 2% to 40% by weight of the (co)polymeric fibers, more preferably from 5% to 30% by weight of the (co)polymeric fibers, even more preferably from 7% to 20% by weight of the (co)polymeric fibers.

In further presently preferred exemplary embodiments, the multiplicity of (co)polymeric fibers exhibits a mean Actual Fiber Diameter of from about 100 nanometers to about 10 micrometers, more preferably from 100 nanometers to 1 micrometer, inclusive. In other exemplary embodiments, the multiplicity of (co)polymeric fibers exhibits a mean Effective Fiber Diameter of between about 1 micrometer and about 100 micrometers, more preferably greater than 1 micrometer to about 20 micrometers.

In certain exemplary embodiments, the (co)polymeric fibers further include between about

0 to 30% w/w of at least one plasticizer. In some such embodiments, the at least one plasticizer is selected from oligomers of Cs to Cu olefins, and mixtures thereof.

In another aspect, the present disclosure describes a process for making a nonwoven fibrous web, including heating a mixture of about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin to at least a Melting Temperature of the mixture to form a molten mixture, extruding the molten mixture through at least one orifice to form at least one filament, applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers, and cooling the plurality of discrete discontinuous fibers to a temperature below the Melting Temperature of the molten mixture to form a nonwoven fibrous web, wherein at least one of the crystalline polyolefin (co)polymer or the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

In certain such exemplary embodiments, applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers is accomplished using a process selected from melt-blowing, gas jet fibrillation, and combinations thereof. In some such exemplary embodiments, the process further includes at least one of addition of a plurality of staple fibers to the plurality of discrete, discontinuous fibers, or addition of a plurality of particulates to the plurality of discrete, discontinuous fibers.

In further such exemplary embodiments, the process further includes collecting the plurality of discrete, discontinuous fibers as the nonwoven fibrous web on a collector. In some such embodiments, the process further includes processing the collected nonwoven fibrous web using a process selected from autogenous bonding, through-air bonding, electret charging, embossing, needle -punching, needle tacking, hydroentangling, or a combination thereof. Exemplary embodiments according to the present disclosure may have certain surprising and unexpected advantages over the art. One such advantage of exemplary embodiments of the present disclosure relates to increased tensile strength exhibited by the webs, even when prepared at low Basis Weight (i.e., less than or equal to 50 g/m 2 , "gsm"). Increased tensile strength for low Basis Weight webs is important for many insulation applications, for example, thermal or acoustic insulation, more particularly acoustic or thermal insulation mats used in motor vehicles (e.g., aircraft, trains, automobiles, trucks, ships, and submersibles).

Thus, exemplary nonwoven fibrous webs as described herein may advantageously exhibit a Maximum Load in the Machine Direction of at least 5 Newtons as measured with the Tensile Strength Test as defined herein.

In certain exemplary embodiments, the nonwoven fibrous webs exhibit a Basis Weight of from 1 g/m 2 (gsm) to 400 gsm, more preferably from 1 gsm to 200 gsm, even more preferably from 1 gsm to 100 gsm, or even 1 gsm to about 50 gsm.

Another advantage of exemplary embodiments may be to limit or eliminate the possibility of newly formed fibers breaking and forming fiber fragments ((i.e., "fly") which can fall onto the collected nonwoven web and damage the web where they land.

An additional advantage of exemplary embodiments relates to an ability to use a higher melt temperature for the melt-blown process, which leads to a lower mean Effective Fiber Diameter (EFD) of about 5 micrometers or less, and may even permit the production of sub- micrometer fibers (i.e., nanofibers) having a mean Actual Fiber Diameter (AFD) of one micrometer or less. Such nonwoven fibrous webs including sub -micrometer fibers achieve better acoustic and/or thermal insulation performance at equal or lower Basis Weight than comparable microfiber webs, thus leading to improved insulation performance at a lower production cost. Embodiments of the present disclosure may also exhibit higher production rates due to the lower melt viscosities achieved during melt-blowing of the fibers.

The following Listing of Exemplary Embodiments summarizes the various exemplary illustrative embodiments of the present disclosure.

Listing of Exemplary Embodiments

A. A nonwoven fibrous web, comprising:

a plurality of (co)polymeric fibers comprising from about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and

from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin, wherein the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g. B. The nonwoven fibrous web of Embodiment A or any following Embodiment, wherein the at least one crystalline polyolefin (co)polymer is selected from the group consisting of polyethylene, isotactic polypropylene, syndiotactic polypropylene, isotactic polybutylene, syndiotactic polybutylene, poly-4-methyl pentene, and mixtures thereof.

C. The nonwoven fibrous web Embodiment B, wherein the at least one crystalline polyolefin (co)polymer exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g,

D. The nonwoven fibrous web of any preceding or following Embodiment, wherein the at least one hydrocarbon tackifier resin is a saturated hydrocarbon.

E. The nonwoven fibrous web of any preceding or following Embodiment, wherein the at least one hydrocarbon tackifier resin is selected from the group consisting of Cs piperylene derivatives, C9 resin oil derivatives, and mixtures thereof.

F. The nonwoven fibrous web of any preceding or following Embodiment, wherein the at least one hydrocarbon tackifier resin makes up from 1% to 40% by weight of the (co)polymeric fibers. G. The nonwoven fibrous web of claim Embodiment F, wherein the at least one hydrocarbon tackifier resin makes up from 5% to 30% by weight of the (co)polymeric fibers.

H. The nonwoven fibrous web of Embodiment G, wherein the at least one hydrocarbon tackifier resin makes up from 7% to 20% by weight of the (co)polymeric fibers.

I. The nonwoven fibrous web of any preceding or following Embodiment, wherein the plurality of (co)polymeric fibers exhibit a mean Actual Fiber Diameter of from about 100 nanometers to about

20 micrometers.

J. The nonwoven fibrous web of Embodiment I, wherein the plurality of (co)polymeric fibers exhibits a mean Actual Fiber Diameter of between about 1 micrometer to about 10 micrometers. K. The nonwoven fibrous web of any preceding or following Embodiment, further comprising between about 0 to 30% of at least one plasticizer.

L. The nonwoven fibrous web of Embodiment K, wherein the at least one plasticizer is selected from the group consisting of oligomers of C5 to Cu olefins, and mixtures thereof.

M. The nonwoven fibrous web of any preceding or following Embodiment, wherein the nonwoven fibrous web exhibits a Maximum Load in the Machine Direction of at least 5 Newtons as measured using the Tensile Strength Test.

M. The nonwoven fibrous web of any preceding or following Embodiment, wherein the nonwoven fibrous web exhibits a Basis Weight of 1 gsm to 400 gsm.

N. The nonwoven fibrous web of Embodiment M, wherein the nonwoven fibrous web exhibits a Basis Weight of 1 gsm to 50 gsm.

O. A process for making a nonwoven fibrous web, comprising: a) heating a mixture of about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1 % w/w to about 40% w/w of at least one hydrocarbon tackifier resin to at least a Melting Temperature of the mixture to form a molten mixture;

b) extruding the molten mixture through at least one orifice to form at least one filament; c) applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers; and

d) cooling the plurality of discrete discontinuous fibers to a temperature below the Melting Temperature of the molten mixture to form a nonwoven fibrous web, wherein at least one of the crystalline polyolefin (co)polymer or the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

P. The process of Embodiment O, Q, R or S, wherein applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers is accomplished using a process selected from the group consisting of melt -blowing, gas jet fibrillation, and combinations thereof.

Q. The process of Embodiment O, P, R or S, further comprising at least one of addition of a plurality of staple fibers to the plurality of melt-blown fibers, or addition of a plurality of particulates to the plurality of melt -blown fibers.

R. The process of Embodiment O, P, Q, or S, further comprising collecting the plurality of discrete discontinuous fibers as the nonwoven fibrous web on a collector.

S. The process of Embodiment O, P, Q, or R, further comprising processing the collected nonwoven fibrous web using a process selected from the group consisting of autogenous bonding, through-air bonding, electret charging, calendering, embossing, needle -punching, needle tacking, hydroentangling, or a combination thereof.

Various aspects and advantages of exemplary embodiments of the disclosure have been summarized. The above Summary is not intended to describe each illustrated embodiment or every implementation of the present certain exemplary embodiments of the present disclosure. The Detailed Description and Examples that follow more particularly exemplify certain presently preferred embodiments using the principles disclosed herein.

DETAILED DESCRIPTION

For the following Glossary of defined terms, these definitions shall be applied for the entire application, unless a different definition is provided in the claims or elsewhere in the specification. Glossary

Certain terms are used throughout the description and the claims that, while for the most part are well known, may require some explanation. It should be understood that:

The terms "(co)polymer" or "(co)polymers" includes homopolymers and copolymers, as well as homopolymers or copolymers that may be formed in a miscible blend, e.g., by coextrusion or by reaction, including, e.g., transesterification. The term "copolymer" includes random, block and star (e.g. dendritic) copolymers.

The term "molecularly same (co)polymer" means one or more (co)polymers that have essentially the same repeating molecular unit, but which may differ in molecular weight, method of manufacture, commercial form, and the like.

The term "nonwoven fibrous web" means a fibrous web characterized by entanglement or point bonding of a plurality of fibers.

The term "self-supporting" means a nonwoven fibrous web having sufficient coherency and strength so as to be drapable and handleable without substantial tearing or rupture.

The terms "melt -blowing" and "melt-blown process" mean a process for forming a nonwoven fibrous web by extruding a fiber-forming material through one or more orifices to form filaments while contacting the filaments with air or other attenuating fluid to attenuate the filaments into discrete discontinuous fibers, and thereafter collecting a layer of the attenuated discrete discontinuous fibers.

The term "die" means a processing assembly including one or more orifices to form filaments for use in (co)polymer melt processing and fiber extrusion processes, including but not limited to melt-blowing processes.

The term "melt-blown fibers" means discrete fibers prepared using a melt-blowing process.

The term "machine direction" means the longitudinal direction in which a nonwoven fibrous web of indeterminate length is moved or wound onto a collector, and is distinguished from the "cross-web" direction, which is the lateral direction extending betwenn the two lateral edges of the nonwoven fibrous web. Gnerally, the crossweb direction is orthogonal to the machine direction for a rectangular nonwoven fibrous web.

The term "composite nonwoven fibrous web" means a nonwoven web having an open- structured entangled mass of melt-blown fibers, for example, sub -micrometer melt-blown fibers and optionally melt-blown microfibers. The terms "particle" and "particulate" are used substantially interchangeably. Generally, a particle or particulate means a small distinct piece or individual part of a material in finely divided form. However, a particulate may also include a collection of individual particles associated or clustered together in finely divided form. Thus, individual particles used in certain exemplary embodiments of the present disclosure may clump, physically intermesh, electro-statically associate, or otherwise associate to form particulates. In certain instances, particulates in the form of agglomerates of individual particles may be intentionally formed such as those described in U.S. Patent No. 5,332,426 (Tang et al.).

The term "particle -loaded nonwoven fibrous web" means a nonwoven fibrous web containing particles bonded to the fibers or enmeshed among the fibers, the particles optionally being absorbent and/or adsorbent.

The term "enmeshed" means that particles are distributed and physically held in the fibers of the web. Generally, there is point and line contact along the fibers and the particles so that nearly the full surface area of the particles is available for interaction with a fluid.

The term "autogenous bonding" means bonding between fibers at an elevated temperature as obtained in an oven or with a through-air bonder without application of solid contact pressure such as in point-bonding or calendering.

The term "calendering" means a process of passing a product, such as a polymeric absorbent loaded web through rollers to obtain a compressed material. The rollers may optionally be heated.

The term "densification" means a process whereby fibers which have been deposited either directly or indirectly onto a filter winding arbor or mandrel are compressed, either before or after the deposition, and made to form an area, generally or locally, of lower porosity, whether by design or as an artifact of some process of handling the forming or formed filter. Densification also includes the process of calendering webs.

The term "Actual Fiber Diameter" or "AFD" means the mean number diameter on a population of melt -blown fibers determined by measuring 500 individual fibers using Scanning Electron Microscopy (SEM).

The term "Effective Fiber Diameter" or "EFD" means the apparent diameter of the fibers in a nonwoven fibrous web based on an air permeation test in which air at 1 atmosphere and room temperature is passed at a face velocity of 5.3 cm/sec through a web sample of known thickness, and the corresponding pressure drop is measured. Based on the measured pressure drop, the Effective Fiber Diameter is calculated as set forth in Davies, C.N., The Separation of Airborne Dust and Particles, Institution of Mechanical Engineers, London Proceedings, IB (1952). The term "microfibers means a population of fibers having a mean diameter of at least one micrometer (μπι) and preferably less than 1,000 μπι.

The term "coarse microfibers" means a population of microfibers having a mean diameter of at least 10 μπι and preferably less than 1,000 μπι.

The term "fine microfibers" means a population of microfibers having a mean diameter of from one μπι to less than 10 μπι.

The term "ultrafine microfibers" means a population of microfibers having a mean diameter of 2 μπι or less.

The term "nanofibers" means a population of fibers having a mean diameter of 1 μπι or less.

The term "sub-micrometer fibers" means a population of fibers having a mean diameter of less than 1 μπι.

The term "separately prepared microfibers" means a stream of microfibers produced from a microfiber-forming apparatus (e.g., a melt-blowing die) positioned such that the microfiber stream is initially spatially separate (e.g., over a distance of about 1 inch (25 mm) or more from, but will merge in flight and disperse into, a stream of larger size microfibers.

The term "homogeneous" means exhibiting only a single phase of matter when observed at a macroscopic scale.

The term "Web Basis Weight" is calculated from the weight of a 10 cm x 10 cm web sample.

The term "Web Thickness" is measured on a 10 cm x 10 cm web sample using a thickness testing gauge having a tester foot with dimensions of 5 cm x 12.5 cm at an applied pressure of 150 Pa.

The term "Polymer Density" is the mass per unit volume of the (co)polymer or (co)polymer blend that is used to form the nonwoven fibers of a nonwoven fibrous web. The

Polymer Density for a (co)polymer may generally be found in the literature, and the Polymer

Density of a (co)polymer blend may be calculated from the weighted average of the component

(co)polymer Polymer Densities, based upon the weight percentages of the individual (co)polymers used to make up the (co)polymer blend. The Polymer Density of polypropylene resin is 0.91 g/cm 3 and the Polymer Density of the hydrocarbon tackifier resins used herein is about 1.00 g/cm 3 .

For the calculations of Solidity provided herein using the following formula, a Polymer Density of

0.91 g/cm 3 was used.

The term "Solidity" is defined by the equation:

Solidity (%) = Γ3.937 * Web Basis Weight (g/m 2 l

[Web Thickness (mils) * Polymer Density (g/cm 3 )] wherein one mil is equivalent to 25 micrometers.

The term "Melting Temperature" as used herein, is the highest magnitude peak among principal and any secondary endothermic melting peaks in a cooling after first heating heat flow curve plotted as a function of temperature, as obtained using Differential Scanning Calorimetry (DSC).

The term "adjoining" with reference to a particular layer in a multi -layer non woven fibrous web means joined with or attached to another layer, in a position wherein the two layers are either next to (i.e., adjacent to) and directly contacting each other, or contiguous with each other but not in direct contact (i.e., there are one or more additional layers intervening between the layers).

The terms "about" or "approximately" with reference to a numerical value or a shape means +/- five percent of the numerical value or property or characteristic, but expressly includes the exact numerical value. For example, a viscosity of "about" 1 Pa-sec refers to a viscosity from 0.95 to 1.05 Pa-sec, but also expressly includes a viscosity of exactly 1 Pa-sec. Similarly, a perimeter that is "substantially square" is intended to describe a geometric shape having four lateral edges in which each lateral edge has a length which is from 95% to 105% of the length of any other lateral edge, but which also includes a geometric shape in which each lateral edge has exactly the same length.

The term "substantially" used with reference to a property or characteristic means that the property or characteristic is exhibited to a greater extent than the opposite of that property or characteristic is exhibited. For example, a substrate that is "substantially" transparent refers to a substrate that transmits more radiation (e.g. visible light) than it fails to transmit (e.g. absorbs and reflects). Thus, a substrate that transmits more than 50% of the visible light incident upon its surface is substantially transparent, but a substrate that transmits 50% or less of the visible light incident upon its surface is not substantially transparent.

By using terms of orientation such as "atop", "on", "over," "covering", "uppermost", "underlying" and the like for the location of various elements in the disclosed coated articles, we refer to the relative position of an element with respect to a horizontally-disposed, upwardly-facing substrate. However, unless otherwise indicated, it is not intended that the substrate or articles should have any particular orientation in space during or after manufacture.

By using the term "overcoated" to describe the position of a layer with respect to a substrate or other element of an article of the present disclosure, we refer to the layer as being atop the substrate or other element, but not necessarily contiguous to either the substrate or the other element. By using the term "separated by" to describe the position of a layer with respect to other layers, we refer to the layer as being positioned between two other layers but not necessarily contiguous to or adjacent to either layer.

As used in this specification and the appended embodiments, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to fine fibers containing "a compound" includes a mixture of two or more compounds. As used in this specification and the appended embodiments, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

As used in this specification, the recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5).

Unless otherwise indicated, all numbers expressing quantities or ingredients, measurement of properties and so forth used in the specification and embodiments are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached listing of embodiments can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claimed embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Various exemplary embodiments of the disclosure will now be described. Exemplary embodiments of the present disclosure may take on various modifications and alterations without departing from the spirit and scope of the disclosure. Accordingly, it is to be understood that the embodiments of the present disclosure are not to be limited to the following described exemplary embodiments, but are to be controlled by the limitations set forth in the claims and any equivalents thereof.

Nonwoven Fibrous Webs

Thus, in one exemplary embodiment, the disclosure describes a nonwoven fibrous web, comprising a plurality of (co)polymeric fibers comprising from about 50% w/w to about 99% w/w of at least one crystalline poly olefin (co)polymer, and from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin, wherein the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

In some exemplary embodiments, the nonwoven fibrous webs as described herein may advantageously exhibit improved tensile strength, as evidenced by a Maximum Tensile Load in the Machine Direction as measured with the Tensile Strength Test as defined herein, of at least 5 Newtons (N), at least 6 N, at least 7 N, at least 8 N, at least 9 N, or even at least 10 N. Generally, the Maximum Tensile Load in the Machine Direction as measured with the Tensile Strength Test as defined herein is less than 20 N, less than 15 N, less than 14 N, or even less than 12 N. Fibers

Nonwoven fibrous webs of the present disclosure generally include fibers that may be regarded as discrete discontinuous fibers. In some exemplary embodiments, the discrete discontinuous fibers in the non-woven fibrous webs or composite webs comprise microfibers and may advantageously exhibit a mean Effective Fiber Diameter (determined using the test method described below) of between about 1 micrometer and about 100 micrometers, more preferably greater than 1 micrometer to about 20.0 micrometers, inclusive, even more preferably from greater than 1 micrometer to about 10.0 micrometers. In other exemplary embodiments, the discrete discontinuous fibers in the non-woven fibrous webs or composite webs may comprise sub- micrometer fibers or nanofibers and may advantageously exhibit a mean Actual Fiber Diameter (determined using the test method described below) of from about 100 nanometers (nm) to about 5 micrometers (μπι), inclusive, more preferably from 100 nm to 1 μπι, inclusive, even more preferably from about 100 nm to about 900 nm, or even 200 nm to 750 nm, or 250 nm to 500 nm, inclusive.

The nonwoven fibrous web may take a variety of forms, including mats, webs, sheets, scrims, fabrics, and a combination thereof.

Fiber Components

Melt-blown nonwoven fibrous webs or webs of the present disclosure comprise fibers comprising from about 50% w/w to about 99% w/w of at least one crystalline polyolefin

(co)polymer, and from about 1% w/w to about 40% w/w at least one hydrocarbon tackifier resin. In some embodiments, a single crystalline polyolefin (co)polymer) may be mixed with a single hydrocarbon tackifier resin. In other exemplary embodiments, a single crystalline polyolefin (co)polymer may be advantageously mixed with two or more hydrocarbon tackifier resins. In further exemplary embodiments, two or more crystalline polyolefin (co)polymers may be mixed with a single hydrocarbon tackifier resin. In other exemplary embodiments, two or more crystalline polyolefin (co)polymers may be advantageously mixed with two or more hydrocarbon tackifier resins.

Crystalline Polyolefin (Co)polymer

The crystalline polyolefin (co)polymers useful in practicing embodiments of the present disclosure are generally crystalline polyolefin (co)polymers with a moderate level of crystallinity. Generally (co)polymer crystallinity arises from stereoregular sequences in the (co)polymer, for example stereoregular ethylene, propylene, or butylene sequences. For example, the (co)polymer can be: (A) a propylene homopolymer in which the stereoregularity is disrupted in some manner such as by regio-in versions; (B) a random propylene copolymer in which the propylene stereoregularity is disrupted at least in part by co-monomers; or (C) a combination of (A) and (B).

In some exemplary embodiments, the at least one crystalline polyolefin (co)polymer is selected from polyethylene, isotactic polypropylene, syndiotactic polypropylene, isotactic polybutylene, syndiotactic polybutylene, poly-4-methyl pentene, and mixtures thereof. The at least one crystalline polyolefin (co)polymer preferably exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g. In certain presently preferred exemplary embodiments, the at least one crystalline polyolefin (co)polymer is selected to be isotactic polypropylene, syndiotactic polypropylene, and mixtures thereof.

In some exemplary embodiments, the crystalline polyolefin (co)polymer is a (co)polymer that includes a non-conjugated diene monomer to aid in vulcanization and other chemical modification of the blend composition. The amount of diene present in the (co)polymer is preferably less than 10% by weight, and more preferably less than 5% by weight. The diene may be any non-conjugated diene which is commonly used for the vulcanization of ethylene propylene rubbers including, but not limited to, ethylidene norbornene, vinyl norbornene, and

dicyclopentadiene.

In one exemplary embodiment, the crystalline polyolefin (co)polymer is a random copolymer of propylene and at least one co-monomer selected from ethylene, C4-C12 alpha-olefins, and combinations thereof. In one particular embodiment, the copolymer includes ethylene-derived units in an amount ranging from a lower limit of 2%, 5%, 6%, 8%, or 10% by weight to an upper limit of 20%, 25%, or 28% by weight. This embodiment also includes propylene-derived units present in the copolymer in an amount ranging from a lower limit of 72%, 75%, or 80% by weight to an upper limit of 98%, 95%, 94%, 92%, or 90% by weight. These percentages by weight are based on the total weight of the propylene and ethylene-derived units; i.e., based on the sum of weight percent propylene-derived units and weight percent ethylene-derived units being 100%.

In other exemplary embodiments, the crystalline polyolefin (co)polymer is a random propylene copolymer having a narrow compositional distribution. In certain presently preferred embodiments, the crystalline polyolefin (co)polymer is a random propylene copolymer exhibiting a Heat of Fusion determined using DSC of greater than 50 J/g.

The copolymer is described as random because for a copolymer comprising propylene, co- monomer, and optionally diene, the number and distribution of co-monomer residues is consistent with the random statistical polymerization of the monomers. In stereoblock structures, the number of block monomer residues of any one kind adjacent to one another is greater than predicted from a statistical distribution in random copolymers with a similar composition. Historical ethylene- propylene copolymers with stereoblock structure have a distribution of ethylene residues consistent with these blocky structures rather than a random statistical distribution of the monomer residues in the (co)polymer. The intramolecular composition distribution (i.e., randomness) of the copolymer may be determined by 13 C NMR, which locates the co-monomer residues in relation to the neighboring propylene residues.

The crystallinity of the crystalline polyolefin (co)polymers may be expressed in terms of heat of fusion. Embodiments of the present disclosure include crystalline polyolefin (co)polymers exhibiting a heat of fusion as determined using differential scanning calorimetry (DSC) greater than 50 J/g, greater than 51 J/g, greater than 55 J/g, greater than 60 J/g, greater than 70 J/g, greater than 80 J/g, greater than 90 J/g, greater than 100 J/g, or even about 110 J/g. Generally, the crystalline polyolefin (co)polymers exhibit a heat of fusion as determined using DSC less than 210 J/g, less than 200 J/g, less than 190 J/g, less than 180 J/g. less than 170 J/g. less than 160 J/g, less than 150 J/g, less than 140 J/g, less than 130 J/g, less than 120 J/g, less than 110 J/g, or even less than 100 J/g.

The level of crystallinity is also reflected in the Melting Point. In one embodiment of the present disclosure, the (co)polymer has a single Melting Point. Typically, a sample of propylene (co)polymer will show secondary melting peaks adjacent to the principal peak, which are considered together as a single Melting Point. The highest of these peaks is considered to be the Melting Point.

The crystalline polyolefin (co)polymer preferably has a melting point determined using DSC ranging from an upper limit of 300 °C, 275 °C, 250 °C, 200 °C, 175 °C, 150 °C, 125 °C, 110 °C, or even about 105 °C, to a lower limit of about 105 °C, 110 °C, 120 °C , 125 °C, 130 °C, 140 °C, 150 °C, 160 °C, 175, 180 °C , 190 °C, 200 °C, 225 °C, or even about 250 °C.

The crystalline polyolefin (co)polymers used in the disclosure generally have a weight average molecular weight (Mw) within the range having an upper limit of 5,000,000 Daltons (Da or g/mol), 1,000,000 Da, or 500,000 Da, and a lower limit of 10,000 Da, 20,000 Da, or 80,000 Da, and a molecular weight distribution M„/M n (MWD), sometimes referred to as a "polydispersity index" (PDI), ranging from a lower limit of 1.5, 1.8, or 2.0 to an upper limit of 40, 20, 10, 5, or 4.5. The M„ and MWD, as used herein, can be determined by a variety of methods, including those in U.S. Pat. No. 4,540,753 to Cozewith, et al., and references cited therein, or those methods found in Verstrate et al., Macromolecules, v. 21, p. 3360 (1988), the descriptions of which are incorporated by reference herein for purposes of U.S. practices.

At least one crystalline polyolefin (co)polymer is generally present in an amount from about 50% w/w (50.0% w/w, 55% w/w, 60% w/w, 65% w/w, 70% w/w, 75% w/w, 80% w/w, 85% w/w, or even about 90% w/w) to about 99% w/w (99.0% w/w, 98% w/w 97% w/w, 96% w/w, 95% w/w, 90% w/w, 85% w/w, 80% w/w, 75% w/w, 70% w/w, 65% w/w, or even about 60% w/w) based on the total weight of the composition.

Hydrocarbon Tackifier Resins

Various types of natural and synthetic hydrocarbon tackifier resins, alone or in admixture with each other, can be used in preparing the fiber compositions described herein, provided they meet the miscibility criteria described herein. Preferably, the hydrocarbon tackifier resin is selected to be miscible (i.e., forms a homogenous melt) with the crystalline polyolefin

(co)polymer(s) when the mixture is in a molten state, that is, when the mixture of the at least one crystalline polyolefin (co)polymer and the at least one hydrocarbon tackifier resin is heated to a temperature at or above the Melting Temperature (as determined using DSC) of the mixture.

Suitable resins include, but are not limited to, natural rosins and rosin esters, hydrogenated rosins and hydrogenated rosin esters, coumarone-indene resins, petroleum resins, polyterpene resins, and terpene -phenolic resins. Specific examples of suitable petroleum resins include, but are not limited to aliphatic hydrocarbon tackifier resins, hydrogenated aliphatic hydrocarbon tackifier resins, mixed aliphatic and aromatic hydrocarbon tackifier resins, hydrogenated mixed aliphatic and aromatic hydrocarbon tackifier resins, cycloaliphatic hydrocarbon tackifier resins, hydrogenated cycloaliphatic resins, mixed cycloaliphatic and aromatic hydrocarbon tackifier resins, hydrogenated mixed cycloaliphatic and aromatic hydrocarbon tackifier resins, aromatic hydrocarbon tackifier resins, substituted aromatic hydrocarbons, and hydrogenated aromatic hydrocarbon tackifier resins.

As used herein, "hydrogenated" includes fully, substantially and at least partially hydrogenated resins. Suitable aromatic resins include aromatic modified aliphatic resins, aromatic modified cycloaliphatic resin, and hydrogenated aromatic hydrocarbon tackifier resins. Any of the above resins may be grafted with an unsaturated ester or anhydride to provide enhanced properties to the resin. Examples of grafted resins and their manufacture are described in the chapter titled Hydrocarbon Resins, Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed. v. 13, pp. 717- 743 (J. Wiley & Sons, 1995).

Hydrocarbon tackifier resins suitable for use as described herein include EMPR 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 116, 117, and 118 resins, OPPERA™ resins, and EMFR resins available from Exxon-Mobil Chemical Company (Spring, TX); ARKON™ PI 40, PI 25, PI 15, Ml 15, and Ml 35 and SUPER ESTER™ rosin esters available from Arakawa Chemical Company (Osaka, Japan); SYLVARES™ polyterpene resins, styrenated terpene resins and terpene phenolic resins, SYLVATAC™ and SYLVALITE™ rosin esters available from Arizona Chemical Company LLC (Jacksonville, FL); NORSOLENE™ aliphatic aromatic resins and WINGTACK™ Cs resins available from TOTAL Cray Valley (Paris, France);

DERTOPHENE™ terpene phenolic resins and DERCOLYTE™ polyterpene resins available from DRT Chemical Company (Dax Cedex, France); EASTOTAC™ resins, PICCOTAC™ resins, REGALITE™ and REGALREZ™ hydrogenated cycloaliphatic/aromatic resins available from Eastman Chemical Company (Kingsport, TN); PICCOLYTE™ and PERMALYN™ polyterpene resins, rosins and rosin esters available from Pinova, Inc. (Brunswick, GA); coumerone/indene resins available from Neville Chemical Company (Pittsburg, PA); QUINTONE™ acid modified Cs resins, C5-C 9 resins, and acid modified C5-C 9 resins available from Nippon Zeon (Tokyo, Japan); and CLEARON™ hydrogenated terpene resins available from Yasuhara Chemical Company, Ltd. (Tokyo, Japan). The preceding examples are illustrative only and by no means limiting.

In some exemplary embodiments, the hydrocarbon tackifier resin has a number average molecular weight (M n ) within the range having an upper limit of 5,000 Da, or 2,000 Da, or 1,000 Da, and a lower limit of 200 Da, or 400 Da, or 500 Da; a weight average molecular weight (M„) ranging from 500 Da to 10,000 Da or 600 to 5,000 Da or 700 to 4,000 Da; a Z average molecular weight (Mz) ranging from 500 Da to 10,000 Da, and a polydispersity index (PDI) as measured by Mw/Mn, of from 1.5 to 3.5, where M n , M„, and M z are determined using size exclusion chromatography (SEC), or as provided by the supplier.

In other exemplary embodiments, the hydrocarbon tackifier resin has a lower molecular weight than the crystalline polyolefin (co)polymer.

The hydrocarbon tackifier resins of the present disclosure are generally selected to be miscible with the crystalline polyolefin (co)polymer in a molten state.

Hydrocarbon tackifier resins useful in embodiments of the present disclosure may have a softening point within the range having an upper limit of 180 °C, 150 °C, or 140 °C, and a lower limit of 80 °C, 120 °C, or 125 °C. Softening point (°C) is measured using a ring and ball softening point device according to ASTM E-28 (Revision 1996).

Preferably, the hydrocarbon tackifier resin is a saturated hydrocarbon. In certain presently preferred exemplary embodiments, the hydrocarbon tackifier resin is selected from C5 piperylene derivatives, C 9 resin oil derivatives, and mixtures thereof.

The hydrocarbon tackifier resin makes up from about 2% w/w (2.0% w/w, 3% w/w, 4% w/w, 5% w/w, 10% w/w, 15% w/w, 20% w/w) to about 40% (40.0% w/w, 35% w/w, 30% w/w, or even 25% w/w) based on the weight of the (co)polymeric fibers in the nonwoven fibrous web, more preferably from 5% to 30% by weight of the (co)polymeric fibers, even more preferably from 7% to 20% by weight of the (co)polymeric fibers. Optional Nonwoven Fibrous Web Components

In further exemplary embodiments, the nonwoven melt-blown fibrous webs of the present disclosure may further comprise one or more optional components. The optional components may be used alone or in any combination suitable for the end-use application of the nonwoven melt- blown fibrous webs. Three non-limiting, currently preferred optional components include optional electret fiber components, optional non-melt-blown fiber components, and optional particulate components as described further below.

Optional Plasticizer

In certain exemplary embodiments, the (co)polymeric fibers further include a plasticizer in an amount between about 0 % to about 30% w/w of the fiber composition, more preferably from 1 % to 20% w/w, 1% to 10% w/w, 1% to 5%, or even 1% to 2.5%. In some such embodiments, the plasticizer is selected from oligomers of Cs to Cu olefins, and mixtures thereof. A non-limiting list of suitable commercially available plasticizers includes SHF and SUPEERSYN™ available from Exxon-Mobil Chemical Company (Houston, TX); STNFLUID™ available from Chevron- Phillips Chemical Co. (Pasadena, TX); DURASYN™ available from BP-Amoco Chemicals (London, England); NEXBASE™ available from Fortum Oil and Gas Co. (Espoo, Finland); SYNTON™ available from Crompton Corporation (Middlebury, CT); EMERY™ available from BASF GmbH (Ludwigshafen, Germany), formerly Cognis Corporation (Dayton, Ohio).

Optional Electret Fiber Component

The nonwoven melt-blown fibrous webs of the present disclosure may optionally comprise electret fibers. Suitable electret fibers are described in U.S. Patent Nos. 4,215,682; 5,641,555; 5,643,507; 5,658,640; 5,658,641 ; 6,420,024; 6,645,618, 6,849,329; and 7,691,168, the entire disclosures of which are incorporated herein by reference.

Suitable electret fibers may be produced by meltblowing fibers in an electric field, e.g. by melting a suitable dielectric material such as a (co)polymer or wax that contains polar molecules, passing the molten material through a melt -blowing die to form discrete fibers, and then allowing the molten (co)polymer to re-solidify while the discrete fibers are exposed to a powerful electrostatic field. Electret fibers may also be made by embedding excess charges into a highly insulating dielectric material such as a (co)polymer or wax, e.g. by means of an electron beam, a corona discharge, injection from an electron, electric breakdown across a gap or a dielectric barrier, and the like. Particularly suitable electret fibers are hydro-charged fibers.

Optional Non-melt-blown Fiber Component

In additional exemplary embodiments, the nonwoven fibrous web optionally further comprises a plurality of non-melt -blown fibers. Thus, in exemplary embodiments, the nonwoven fibrous web may additionally comprise discrete non-melt-blown fibers. Optionally, the discrete non-melt -blown fibers are staple fibers. Generally, the discrete non-melt-blown fibers act as filling fibers, e.g. to reduce the cost or improve the properties of the melt -blown nonwoven fibrous web.

Non-limiting examples of suitable non-melt-blown filling fibers include single component synthetic fibers, semi-synthetic fibers, polymeric fibers, metal fibers, carbon fibers, ceramic fibers, and natural fibers. Synthetic and/or semi-synthetic polymeric fibers include those made of polyester (e.g., polyethylene terephthalate), nylon (e.g., hexamethylene adipamide,

polycaprolactam), polypropylene, acrylic (formed from a (co)polymer of acrylonitrile), rayon, cellulose acetate, polyvinylidene chloride -vinyl chloride copolymers, vinyl chloride-acrylonitrile copolymers, and the like.

Non-limiting examples of suitable metal fibers include fibers made from any metal or metal alloy, for example, iron, titanium, tungsten, platinum, copper, nickel, cobalt, and the like.

Non-limiting examples of suitable carbon fibers include graphite fibers, activated carbon fibers, poly(acrylonitrile)-derived carbon fibers, and the like.

Non-limiting examples of suitable ceramic fibers include any metal oxide, metal carbide, or metal nitride, including but not limited to silicon oxide, aluminum oxide, zirconium oxide, silicon carbide, tungsten carbide, silicon nitride, and the like.

Non-limiting examples of suitable natural fibers include those of bamboo, cotton, wool, jute, agave, sisal, coconut, soybean, hemp, and the like.

The fiber component used may be virgin fibers or recycled waste fibers, for example, recycled fibers reclaimed from garment cuttings, carpet manufacturing, fiber manufacturing, textile processing, or the like.

The size and amount of discrete non-melt-blown filling fibers, if included, used to form the nonwoven fibrous web, will generally depend on the desired properties (i.e., loftiness, openness, softness, drapability) of the nonwoven fibrous web 100 and the desired loading of the chemically active particulate. Generally, the larger the fiber diameter, the larger the fiber length, and the presence of a crimp in the fibers will result in a more open and lofty nonwoven article. Generally, small and shorter fibers will result in a more compact nonwoven article.

Optional Particulate Component

In certain exemplary embodiments, the nonwoven fibrous web further comprises a plurality of particulates. Exemplary nonwoven fibrous webs according to the present disclosure may advantageously include a plurality of chemically active particulates. The chemically active particulates can be any discrete particulate, which is a solid at room temperature, and which is capable of undergoing a chemical interaction with an external fluid phase. Exemplary chemical interactions include adsorption, absorption, chemical reaction, catalysis of a chemical reaction, dissolution, and the like.

Additionally, in any of the foregoing exemplary embodiments, the chemically active particulates may advantageously be selected from sorbent particulates (e.g. adsorbent particulates, absorbent particulates, and the like), desiccant particulates (e.g. particulates comprising a hygroscopic substance such as, for example, calcium chloride, calcium sulfate, and the like, that induces or sustains a state of dryness in its local vicinity), biocide particulates, microcapsules, and combinations thereof. In any of the foregoing embodiments, the chemically active particulates may be selected from activated carbon particulates, activated alumina particulates, silica gel particulates anion exchange resin particulates, cation exchange resin particulates, molecular sieve particulates, diatomaceous earth particulates, anti-microbial compound particulates, metal particulates, and combinations thereof.

In one exemplary embodiment of a nonwoven fibrous web particularly useful as a fluid filtration article, the chemically active particulates are sorbent particulates. A variety of sorbent particulates can be employed. Sorbent particulates include mineral particulates, synthetic particulates, natural sorbent particulates or a combination thereof. Desirably the sorbent particulates will be capable of absorbing or adsorbing gases, aerosols, or liquids expected to be present under the intended use conditions.

The sorbent particulates can be in any usable form including beads, flakes, granules or agglomerates. Preferred sorbent particulates include activated carbon; silica gel; activated alumina and other metal oxides; metal particulates (e.g., silver particulates) that can remove a component from a fluid by adsorption or chemical reaction; particulate catalytic agents such as hopcalite (which can catalyze the oxidation of carbon monoxide); clay and other minerals treated with acidic solutions such as acetic acid or alkaline solutions such as aqueous sodium hydroxide; ion exchange resins; molecular sieves and other zeolites; biocides; fungicides and virucides. Activated carbon and activated alumina are presently particularly preferred sorbent particulates. Mixtures of sorbent particulates can also be employed, e.g., to absorb mixtures of gases, although in practice to deal with mixtures of gases it may be better to fabricate a multilayer sheet article employing separate sorbent particulates in the individual layers.

In one exemplary embodiment of a nonwoven fibrous web particularly useful as a gas filtration article, the chemically active sorbent particulates are selected to be gas adsorbent or absorbent particulates. For example, gas adsorbent particulates may include activated carbon, charcoal, zeolites, molecular sieves, an acid gas adsorbent, an arsenic reduction material, an iodinated resin, and the like. For example, absorbent particulates may also include naturally porous particulate materials such as diatomaceous earth, clays, or synthetic particulate foams such as melamine, rubber, urethane, polyester, polyethylene, silicones, and cellulose. The absorbent particulates may also include superabsorbent particulates such as sodium polyacrylates, carboxymethyl cellulose, or granular polyvinyl alcohol.

In certain exemplary embodiments of a nonwoven fibrous web particularly useful as a liquid filtration article, the sorbent particulates comprise liquid an activated carbon, diatomaceous earth, an ion exchange resin (e.g. an anion exchange resin, a cation exchange resin, or

combinations thereof), a molecular sieve, a metal ion exchange sorbent, an activated alumina, an antimicrobial compound, or combinations thereof. Certain exemplary embodiments provide that the web has a sorbent particulate density in the range of about 0.20 to about 0.5 g/cc.

Various sizes and amounts of sorbent chemically active particulates may be used to create a nonwoven fibrous web. In one exemplary embodiment, the sorbent particulates have a mean size greater than 1 mm in diameter. In another exemplary embodiment, the sorbent particulates have a mean size less than 1 cm in diameter. In further embodiments, a combination of particulate sizes can be used. In one exemplary additional embodiment, the sorbent particulates include a mixture of large particulates and small particulates.

The desired sorbent particulate size can vary a great deal and usually will be chosen based in part on the intended service conditions. As a general guide, sorbent particulates particularly useful for fluid filtration applications may vary in size from about 0.001 to about 3000 μπι mean diameter. Generally, the sorbent particulates are from about 0.01 to about 1500 μπι mean diameter, more generally from about 0.02 to about 750 μπι mean diameter, and most generally from about 0.05 to about 300 μπι mean diameter.

In certain exemplary embodiments, the sorbent particulates may comprise nano- particulates having a population mean diameter less than 1 μιη. Porous nano-particulates may have the advantage of providing high surface area for sorption of contaminants from a fluid medium (e.g., absorption and/or adsorption). In such exemplary embodiments using ultrafine or nano-particulates, it may be preferred that the particulates are adhesively bonded to the fibers using an adhesive, for example a hot melt adhesive, and/or the application of heat to the melt- blown nonwoven fibrous web (i.e., thermal bonding).

Mixtures (e.g., bimodal mixtures) of sorbent particulates having different size ranges can also be employed, although in practice it may be better to fabricate a multilayer sheet article employing larger sorbent particulates in an upstream layer and smaller sorbent particulates in a downstream layer. At least 80 weight percent sorbent particulates, more generally at least 84 weight percent and most generally at least 90 weight percent sorbent particulates are enmeshed in the web. Expressed in terms of the web Basis Weight, the sorbent particulate loading level may for example be at least about 500 gsm for relatively fine (e.g. sub-micrometer-sized) sorbent particulates, and at least about 2,000 gsm for relatively coarse (e.g., micron-sized) sorbent particulates.

In some exemplary embodiments, the chemically active particulates are metal particulates. The metal particulates may be used to create a polishing nonwoven fibrous web. The metal particulates may be in the form of short fiber or ribbon-like sections or may be in the form of grain-like particulates. The metal particulates can include any type of metal such as but not limited to silver (which has antibacterial/antimicrobial properties), copper (which has properties of an algaecide), or blends of one or more of chemically active metals.

In other exemplary embodiments, the chemically active particulates are solid biocides or antimicrobial agents. Examples of solid biocide and antimicrobial agents include halogen containing compounds such as sodium dichloroisocyanurate dihydrate, benzalkonium chloride, halogenated dialkylhydantoins, and triclosan.

In further exemplary embodiments, the chemically active particulates are microcapsules. Microcapsules are described in U.S. Pat. No. 3,516,941 (Matson), and include examples of the microcapsules that can be used as the chemically active particulates. The microcapsules may be loaded with solid or liquid biocides or antimicrobial agents. One of the main qualities of a microcapsule is that by means of mechanical stress the particulates can be broken in order to release the material contained within them. Therefore, during use of the nonwoven fibrous web, the microcapsules will be broken due to the pressure exerted on the nonwoven fibrous web, which will release the material contained within the microcapsule.

In certain such exemplary embodiments, it may be advantageous to use at least one particulate that has a surface that can be made adhesive or "sticky" so as to bond together the particulates to form a mesh or support nonwoven fibrous web for the fiber component. In this regard, useful particulates may comprise a (co)polymer, for example, a thermoplastic (co)polymer, which may be in the form of discontinuous fibers. Suitable polymers include polyolefins, particularly thermoplastic elastomers (TPE's) (e.g., VISTAMAXX™, available from Exxon-Mobil Chemical Company, Houston, Texas). In further exemplary embodiments, particulates comprising a TPE, particularly as a surface layer or surface coating, may be preferred, as TPE's are generally somewhat tacky, which may assist bonding together of the particulates to form a three-dimensional network before addition of the fibers to form the nonwoven fibrous web. In certain exemplary embodiments, particulates comprising a VISTAMAXX™ TPE may offer improved resistance to harsh chemical environments, particularly at low pH (e.g., pH no greater than about 3) and high pH (e.g., pH of at least about 9) and in organic solvents.

Any suitable size or shape of particulate material may be selected. Suitable particulates may have a variety of physical forms (e.g., solid particulates, porous particulates, hollow bubbles, agglomerates, discontinuous fibers, staple fibers, flakes, and the like); shapes (e.g., spherical, elliptical, polygonal, needle -like, and the like); shape uniformities (e.g., monodisperse, substantially uniform, non-uniform or irregular, and the like); composition (e.g. inorganic particulates, organic particulates, or combination thereof); and size (e.g., sub -micrometer-sized, micro-sized, and the like).

With particular reference to particulate size, in some exemplary embodiments, it may be desirable to control the size of a population of the particulates. In certain exemplary embodiments, particulates are physically entrained or trapped in the fiber nonwoven fibrous web. In such embodiments, the population of particulates is generally selected to have a mean diameter of at least 50 μπι, more generally at least 75 μπι, still more generally at least 100 μιη.

In other exemplary embodiments, it may be preferred to use finer particulates that are adhesively bonded to the fibers using an adhesive, for example a hot melt adhesive, and/or the application of heat to one or both of thermoplastic particulates or thermoplastic fibers (i.e., thermal bonding). In such embodiments, it is generally preferred that the particulates have a mean diameter of at least 25 μπι, more generally at least 30 μπι, most generally at least 40 μιη. In some exemplary embodiments, the chemically active particulates have a mean size less than 1 cm in diameter. In other embodiments, the chemically active particulates have a mean size of less than 1 mm, more generally less than 25 micrometers, even more generally less than 10 micrometers.

However, in other exemplary embodiments in which both an adhesive and thermal bonding are used to adhere the particulates to the fibers, the particulates may comprise a population of sub-micrometer-sized particulates having a population mean diameter of less than one micrometer (μπι), more generally less than about 0.9 μπι, even more generally less than about 0.5 μπι, most generally less than about 0.25 μιη. Such sub-micrometer-sized particulates may be particularly useful in applications where high surface area and/or high absorbency and/or adsorbent capacity is desired. In further exemplary embodiments, the population of sub- micrometer-sized particulates has a population mean diameter of at least 0.001 μπι, more generally at least about 0.01 μπι, most generally at least about 0.1 μπι, most generally at least about 0.2 μπι.

In further exemplary embodiments, the particulates comprise a population of micro-sized particulates having a population mean diameter of at most about 2,000 μπι, more generally at most about 1,000 μπι, most generally at most about 500 μπι. In other exemplary embodiments, the particulates comprise a population of micro-sized particulates having a population mean diameter of at most about 10 μπι, more generally at most about 5 μπι, even more generally at most about 2 μπι (e.g., ultrafine micro-fibers).

Multiple types of particulates may also be used within a single finished web. Using multiple types of particulates, it may be possible to generate continuous particulate webs even if one of the particulate types does not bond with other particulates of the same type. An example of this type of system would be one where two types are particulates are used, one that bonds the particulates together (e.g., a discontinuous polymeric fiber particulate) and another that acts as an active particulate for the desired purpose of the web (e.g., a sorbent particulate such as activated carbon). Such exemplary embodiments may be particularly useful for fluid filtration applications.

Depending, for example, on the density of the chemically active particulate, size of the chemically active particulate, and/or desired attributes of the final nonwoven fibrous web article, a variety of different loadings of the chemically active particulates may be used relative to the total weight of the fibrous web. In one embodiment, the chemically active particulates comprise less than 90% wt. of the total nonwoven article weight. In one embodiment, the chemically active particulates comprise at least 10% wt. of the total nonwoven article weight.

In any of the foregoing embodiments, the chemically active particulates may be advantageously distributed throughout the entire thickness of the nonwoven fibrous web.

However, in some of the foregoing embodiments, the chemically active particulates are preferentially distributed substantially on a major surface of the nonwoven fibrous web.

Furthermore, it is to be understood that any combination of one or more of the above described chemically active particulates may be used to form nonwoven fibrous webs according to the present disclosure. Processes for Forming Fibers

In another aspect, the present disclosure describes a process for making a nonwoven fibrous web, comprising heating a mixture of about 50% w/w to about 99% w/w of a crystalline polyolefin (co)polymer, and from about 1 % w/w to about 40% w/w of a hydrocarbon tackifier resin to at least a Melting Temperature of the mixture to form a molten mixture, extruding the molten mixture through at least one orifice to form at least one filament, applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers, and cooling the plurality of discrete discontinuous fibers to a temperature below the Melting Temperature of the molten mixture to form a nonwoven fibrous web, wherein at least one of the crystalline polyolefin (co)polymer or the nonwoven fibrous web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.

A number of processes may be used to produce a microfiber stream, including, but not limited to, melt -blowing, gas jet fibrillation, or a combination thereof. Suitable processes for forming microfibers are described in U.S. Patent Nos. 6,315,806 (Torobin), 6,114,017

(Fabbricante et al.), 6,382,526 Bl (Reneker et al.), and 6,861,025 B2 (Erickson et al.). Alternatively, a population of microfibers may be formed or converted to staple fibers and combined with a population of sub-micrometer fibers using, for example, using a process as described in U.S. Patent No. 4,118,531 (Hauser).

A number of processes may be used advantageously to produce a sub-micrometer fiber stream from the molten (co)polymer mixture, including, but not limited to melt -blowing, gas jet fibrillation, or a combination thereof. Particularly suitable processes include, but are not limited to, processes disclosed in U.S. Patent Nos. 3,874,886 (Levecque et al.), 4,363,646 (Torobin), 4,536,361 (Torobin), 5,227,107 (Dickenson et al.), 6,183,670 (Torobin), 6,269,513 (Torobin), 6,315,806 (Torobin), 6,743,273 (Chung et al.), 6,800,226 (Gerking) and 9,382,643 (Moore et al.); German Patent DE 19929709 C2 (Gerking); Pub. PCT App. No. WO 2007/001990 A2 (Krause et al.).

Sub-micrometer fibers separately formed using processes other than melt-blowing and/or gas jet fibrillation may also be combined with a population of microfibers and/or sub-micrometer fibers formed by melt-blowing and/or gas jet fibrillation. Suitable processes for separately forming sub-micrometer include electrospinning processes, for example, those processes described in U.S. Patent No. 1,975,504 (Formhals).

Other suitable processes for forming sub-micrometer fibers are described in U.S. Patent Nos. 6,114,017 (Fabbricante et al.), 6,382,526 B l (Reneker et al.); and 6,861,025 B2 (Erickson et al.).

Melt-Blowing Processes

In the melt-blowing process, the crystalline polyolefin (co)polymer/hydrocarbon resin tackifier mixture is melted to form a molten mixture, which is then extruded through one or more orifices of a melt-blowing die. applying a gaseous stream to the at least one filament to attenuate the at least one filament to form a plurality of discrete, discontinuous fibers

In any of the foregoing processes, the melt-blowing should be performed within a range of temperatures hot enough to enable the crystalline polyolefin (co)polymer/hydrocarbon resin tackifier mixture to be melt-blown but not so hot as to cause unacceptable deterioration of the crystalline polyolefin (co)polymer/hydrocarbon resin tackifier mixture. For example, the melt- blowing can be performed at a temperature that causes the molten mixture of the crystalline polyolefin (co)polymer and hydrocarbon resin tackifier to reach a processing temperature at least 40-50°C above the melting temperature.

Preferably, the processing temperature of the molten mixture is selected to be 200°C, 225°C, 250°C, 260°C, 270°C, 280°C, or even at least 290°C; to less than or equal to about 360°C, 350°C, 340°C, 330°C, 320°C, 310°C, or even 300°C. Processes for Forming Composite Nonwoven Fibrous Webs

In some such exemplary embodiments, the process further includes at least one of addition of a plurality of staple fibers to the plurality of discrete, discontinuous fibers, or addition of a plurality of particulates to the plurality of discrete, discontinuous fibers, to form a composite nonwoven fibrous web.

In some exemplary embodiments, the method of making a composite nonwoven fibrous web comprises combining the microfiber or coarse microfiber population with the fine microfiber population, the ultrafine microfiber population, or the sub-micrometer fiber population by mixing fiber streams, hydroentangling, wet forming, plexifilament formation, or a combination thereof.

In combining the microfiber or coarse microfiber population with the fine, ultrafine or sub- micrometer fiber populations, multiple streams of one or both types of fibers may be used, and the streams may be combined in any order. In this manner, nonwoven composite fibrous webs may be formed exhibiting various desired concentration gradients and/or layered structures.

For example, in certain exemplary embodiments, the population of fine, ultrafine or sub- micrometer fibers may be combined with the population of microfibers or coarse microfibers to form an inhomogenous mixture of fibers. In certain exemplary embodiments, at least a portion of the population of fine, ultrafine or sub -micrometer fibers is intermixed with at least a portion of the population of microfibers. In other exemplary embodiments, the population of fine, ultrafine or sub-micrometer fibers may be formed as an overlayer on an underlayer comprising the population of microfibers. In certain other exemplary embodiments, the population of microfibers may be formed as an overlayer on an underlayer comprising the population of fine, ultrafine or sub- micrometer fibers.

Optional Particulate Loading Processes

In many applications, substantially uniform distribution of particles throughout the web is desired. There may also be instances where non-uniform distributions may be advantageous. In certain exemplary embodiments, a particulate density gradient may advantageously be created within the composite nonwoven fibrous web. For example, gradients through the depth of the web may create changes to the pore size distribution that could be used for depth filtration. Webs with a surface loading of particles could be formed into a filter where the fluid is exposed to the particles early in the flow path and the balance of the web provides a support structure and means to prevent sloughing of the particles. The flow path could also be reversed so the web can act as a pre -filter to remove some contaminants prior to the fluid reaching the active surface of the particles.

Various methods are known for adding a stream of particulates to a nonwoven fiber stream. Suitable methods are described in U.S. Patent Nos. 4,118,531 (Hauser), 6,872,311 (Koslow), and 6,494,974 (Riddell); and in U.S. Patent Application Publication Nos. 2005/0266760 (Chhabra and Isele), 2005/0287891 (Park) and 2006/0096911 (Brey et al.).

In other exemplary embodiments, the optional particulates could be added to a nonwoven fiber stream by air laying a fiber web, adding particulates to the fiber web (e.g., by passing the web through a fluidized bed of particulates), optionally with post heating of the particulate -loaded web to bond the particulates to the fibers. Alternatively, a pre -formed web could be sprayed with a preformed dispersion of particulates in a volatile fluid (e.g. an organic solvent, or even water), optionally with post heating of the particulate -loaded web to remove the volatile fluid and bond the particulates to the fibers.

In further exemplary embodiments, the process further includes collecting the plurality of discrete, discontinuous fibers as the nonwoven fibrous web on a collector. In certain such exemplary embodiments, the composite nonwoven fibrous web may be formed by depositing the population of fine, ultrafine or sub-micrometer fibers directly onto a collector surface, or onto an optional support layer on the collector surface, the support layer optionally comprising microfibers, so as to form a population of fine, ultrafine or sub -micrometer fibers on the porous support layer.

The process may include a step wherein the optional support layer, which optionally may comprise polymeric microfibers, is passed through a fiber stream of fine, ultrafine or sub- micrometer fibers. While passing through the fiber stream, fine, ultrafine or sub -micrometer fibers may be deposited onto the support layer so as to be temporarily or permanently bonded to the support layer. When the fibers are deposited onto the support layer, the fibers may optionally bond to one another, and may further harden while on the support layer.

In certain exemplary embodiments, the fine, ultrafine or sub-micrometer fiber population is combined with an optional porous support layer that comprises at least a portion of the coarse microfiber population. In some exemplary embodiments, the microfibers forming the porous support layer are compositionally the same as the population of microfibers that forms the first layer. In other presently preferred embodiments, the fine, ultrafine or sub -micrometer fiber population is combined with an optional porous support layer and subsequently combined with at least a portion of the coarse microfiber population. In certain other presently preferred embodiments, the porous support layer adjoins the second layer opposite the first layer.

In other exemplary embodiments, the porous support layer comprises a nonwoven fabric, a woven fabric, a knitted fabric, a foam layer, a screen, a porous film, a perforated film, an array of filaments, or a combination thereof. In some exemplary embodiments, the porous support layer comprises a thermoplastic mesh. Optional Processing Steps

In some embodiments, the process further includes processing the collected nonwoven fibrous web using a process selected from autogenous bonding (e.g., through-air bonding, calendering, and the like), electret charging, embossing, needle -punching, needle tacking, hydroentangling, or a combination thereof.

Optional Bonding Processes

Depending on the condition of the fibers and the relative proportion of microfibers and sub-micrometer fibers, some bonding may occur between the fibers themselves (e.g., autogenous bonding) and between the fibers and any optional particulates, before or during collection.

However, further bonding between the fibers themselves and between the fibers and any optional particulates in the collected web may be desirable to provide a matrix of desired coherency, making the web more handle-able and better able to hold any sub-micrometer fibers within the matrix ("bonding" fibers themselves means adhering the fibers together firmly, so they generally do not separate when the web is subjected to normal handling).

In certain exemplary embodiments, a blend of microfibers and sub -micrometer fibers may be bonded together. Bonding may be achieved, for example, using thermal bonding, adhesive bonding, powdered binder, hydroentangling, needle-punching, calendering, or a combination thereof. Conventional bonding techniques using heat and pressure applied in a point -bonding process or by smooth calender rolls can be used, though such processes may cause undesired deformation of fibers or excessive compaction of the web.

A presently preferred technique for bonding fibers, particularly microfibers, is the autogenous bonding method disclosed in U.S. Patent Application Publication No.

U.S. 2008/0038976 Al .

Optional Electret Charging Processes

In some particular embodiments, the melt -blown fibers may be advantageously electrostatically charged. Thus, in certain exemplary embodiments, the melt-blown fibers may be subjected to an electret charging process. An exemplary electret charging process is hydro- charging. Hydro-charging of fibers may be carried out using a variety of techniques including impinging, soaking or condensing a polar fluid onto the fiber, followed by drying, so that the fiber becomes charged. Representative patents describing hydro-charging include U.S. Patent Nos. 5,496,507; 5,908,598; 6,375,886 Bl ; 6,406,657 Bl ; 6,454,986 and 6,743,464 B l. Preferably water is employed as the polar hydro-charging liquid, and the media preferably is exposed to the polar hydro-charging liquid using jets of the liquid or a stream of liquid droplets provided by any suitable spray means.

Devices useful for hydraulically entangling fibers are generally useful for carrying out hydro-charging, although the operation is carried out at lower pressures in hydro-charging than generally used in hydro-entangling. U.S. Patent No. 5,496,507 describes an exemplary apparatus in which jets of water or a stream of water droplets are impinged upon the fibers in web form at a pressure sufficient to provide the subsequently-dried media with a filtration-enhancing electret charge.

The pressure necessary to achieve optimum results may vary depending on the type of sprayer used, the type of (co)polymer from which the fiber is formed, the thickness and density of the web, and whether pretreatment such as corona charging was carried out before hydro-charging. Generally, pressures in the range of about 69 kPa to about 3450 kPa are suitable. Preferably, the water used to provide the water droplets is relatively pure. Distilled or deionized water is preferable to tap water.

The electret fibers may be subjected to other charging techniques in addition to or alternatively to hydro-charging, including electrostatic charging (e.g., as described in U.S. Patent Nos. 4,215,682, 5,401,446 and 6,119,691), tribo-charging (e.g., as described in U.S. Patent No. 4,798,850) or plasma fluorination (e.g., as described in U.S. Patent No. 6,397,458 B l). Corona charging followed by hydro-charging and plasma fluorination followed by hydro-charging are particularly suitable charging techniques used in combination.

Optional Post-collection Processing Steps

Various processes conventionally used as adjuncts to fiber-forming processes may be used in connection with fibers as they exit from one or more orifices of the belt blowing die. Such processes include spraying of finishes, adhesives or other materials onto the fibers, application of an electrostatic charge to the fibers, application of water mists to the fibers, and the like. In addition, various materials may be added to a collected web, including bonding agents, adhesives, finishes, and other webs or films. For example, prior to collection, extruded fibers or fibers may be subjected to a number of additional processing steps, e.g., further drawing, spraying, and the like. Various fluids may also be advantageously applied to the fibers before or during collection, including water sprayed onto the fibers, e.g., heated water or steam to heat the fibers, or cold water to quench the fibers.

After collection, the collected mass may additionally or alternatively be wound into a storage roll for later processing if desired. Generally, once the collected melt -blown nonwoven fibrous web has been collected, it may be conveyed to other apparatus such as a calender, embossing stations, laminators, cutters and the like; or it may be passed through drive rolls and wound into a storage roll.

Thus, in addition to the foregoing methods of making and optionally bonding or electret charging a nonwoven fibrous web, one or more of the following process steps may optionally be carried out on the web once formed:

(1) advancing the composite nonwoven fibrous web along a process pathway toward further processing operations;

(2) bringing one or more additional layers into contact with an outer surface of the sub- micrometer fiber component, the microfiber component, and/or the optional support layer;

(3) calendering the composite nonwoven fibrous web;

(4) coating the composite nonwoven fibrous web with a surface treatment or other composition (e.g., a fire-retardant composition, an adhesive composition, or a print layer);

(5) attaching the composite nonwoven fibrous web to a cardboard or plastic tube;

(6) winding-up the composite nonwoven fibrous web in the form of a roll;

(7) slitting the composite nonwoven fibrous web to form two or more slit rolls and/or a plurality of slit sheets;

(8) placing the composite nonwoven fibrous web in a mold and molding the composite nonwoven fibrous web into a new shape; and

(9) applying a release liner over an exposed optional pressure-sensitive adhesive layer, when present.

Articles Incorporating Nonwoven Fibrous Webs

Nonwoven fibrous webs can be made using the foregoing processes. In some exemplary embodiments, the nonwoven fibrous web or composite web takes the form of a mat, web, sheet, a scrim, or a combination thereof.

In some particular exemplary embodiments, the nonwoven fibrous web or composite web may advantageously include charged melt-blown fibers, e.g., electret fibers. In certain exemplary embodiments, the melt-blown nonwoven fibrous web or web is porous. In some additional exemplary embodiments, the nonwoven fibrous web or composite web may advantageously be self-supporting. In further exemplary embodiments, the melt -blown nonwoven fibrous web or composite web advantageously may be pleated, e.g., to form a filtration medium, such as a liquid (e.g., water) or gas (e.g., air) filter, a heating, ventilation or air conditioning (HVAC) filter, or a respirator for personal protection. For example, U.S. Patent No. 6,740,137 discloses nonwoven webs used in a collapsible pleated filter element. Webs of the present disclosure may be used by themselves, e.g., for filtration media, decorative fabric, or a protective or cover stock. Or they may be used in combination with other webs or structures, e.g., as a support for other fibrous layers deposited or laminated onto the web, as in a multilayer filtration media, or a substrate onto which a membrane may be cast. They may be processed after preparation as by passing them through smooth calendering rolls to form a smooth-surfaced web, or through shaping apparatus to form them into three-dimensional shapes.

A nonwoven fibrous web or composite web of the present disclosure can further comprise at least one or a plurality of other types of fibers (not shown) such as, for example, staple or otherwise discontinuous fibers, melt spun continuous fibers or a combination thereof. The present exemplary fibrous webs can be formed, for example, into a non -woven web that can be wound about a tube or other core to form a roll, and either stored for subsequent processing or transferred directly to a further processing step. The web may also be cut into individual sheets or mats directly after the web is manufactured or sometime thereafter.

The melt-blown nonwoven fibrous webs or composite webs can be used to make any suitable article such as, for example, a thermal insulation article, an acoustic insulation article, a fluid filtration article, a wipe, a surgical drape, a wound dressing, a garment, a respirator, or a combination thereof. The thermal or acoustic insulation articles may be used as an insulation component for vehicles (e.g., trains, airplanes, automobiles and boats). Other articles such as, for example, bedding, shelters, tents, insulation, insulating articles, liquid and gas filters, wipes, garments, garment components, personal protective equipment, respirators, and the like, can also be made using melt-blown nonwoven fibrous webs of the present disclosure.

Flexible, drape-able and compact nonwoven fibrous webs may be preferred for certain applications, for examples as furnace filters or gas filtration respirators. Such nonwoven fibrous webs typically have a density greater than 75 kg/m 3 and typically greater than 100 kg/m 3 or even 120 kg/m 3 . However, open, lofty nonwoven fibrous webs suitable for use in certain fluid filtration applications generally have a maximum density of 60 kg/m 3 .

Thus, in certain exemplary embodiments, the nonwoven fibrous webs exhibit a Basis Weight of from 1 gsm to 400 gsm, more preferably from 1 gsm to 200 gsm, even more preferably from 1 gsm to 100 gsm, or even 1 gsm to about 50 gsm.

Certain presently-preferred nonwoven fibrous webs according to the present disclosure may have a Solidity less than 50%, 340%, 30%, 20%, or more preferably less than 15%, even more preferably less than 10%.

The operation of the processes of the present disclosure to produce nonwoven fibrous webs as described herein, will be further described with regard to the following detailed examples. These examples are offered to further illustrate the various specific and preferred embodiments and techniques. It should be understood, however, that many variations and modifications may be made while remaining within the scope of the present disclosure.

EXAMPLES

These Examples are merely for illustrative purposes and are not meant to be overly limiting on the scope of the appended claims. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Summary of Materials

Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Solvents and other reagents used may be obtained from Sigma- Aldrich Chemical Company (Milwaukee, WI).

Test Methods

The following test methods have been used in evaluating some of the Examples of the present disclosure.

Tensile Strength Test

The tensile properties of webs in the Examples were measured by pulling to failure a 1 inch by 6 inch sample (2.5 cm by 15.2 cm). The thickness of the nonwoven fibrous web samples was about 0.15 cm. The Tensile Strength Test was carried out using commercially available tensile test apparatus designated as Instron Model 5544, available from Instron Company (Canton,

MA). The gauge length was 4 inches (10.2 cm), and the cross-head speed was 308 millimeters/per minute. The Maximum Tensile Load (in Newtons) was determined in the machine direction of the nonwoven fibrous web.

Actual Fiber Diameter

The Actual Fiber Diameter (AFD) was determined using a Scanning Electron Microscope

(SEM). The samples were sputter coated with gold in a vacuum chamber (Denton Vacuum,

Moorestown, New Jersey). The specimens were then analyzed using a Phenom Pure SEM

(Phenom- World, Eindhoven, Netherlands). The AFD is the average (mean) number diameter determined from measurements taken on 500 individual fibers in the nonwoven fibrous web sample using SEM Effective Fiber Diameter

The Effective Fiber Diameter (EFD) was determined using an air flow rate of 32 L/min (corresponding to a face velocity of 5.3 cm/sec), using the method set forth in Davies, C. N., "The Separation of Airborne Dust and Particles," Institution of Mechanical Engineers, London, Proceedings IB, 1952.

Actual Fiber Diameter

The Actual Fiber Diameter (AFD) was determined using a Scanning Electron Microscope (SEM). The samples were sputter coated in a vacuum chamber (Denton Vacuum, Moorestown, New Jersey). The specimens were then analyzed using a Phenom Pure SEM (Phenom-World, Eindhoven, Netherlands). The AFD is the average (mean) fiber diameter determined from measurement of 500 individual fibers.

Differential Scanning Calorimetrv (Melting Temperature and Heat of Fusion)

Differential Scanning Calorimetry (DSC) was used to determine the Melting Temperature and Heat of Fusion of the crystalline polyolefin, the mixture of the crystalline polyolefin with the hydrocarbon tackifier resin, and the nonwoven fibrous webs produced from the mixture.

The DSC analysis was carried out using a Model DSC Q2000 available from Ta

Instruments Co. (New Castle, DE). Approximately 1.5 mg to 10 mg of the crystalline polyolefin, the mixture of the crystalline polyolefin with the hydrocarbon tackifier resin, or the nonwoven fibrous web produced from the mixture, was loaded and sealed in an aluminum pan and placed in the DSC Q2000 apparatus.

DSC measurements on each sample was carried out using the following sequential Heating-Cooling-Heating cycle. Each sample was initially heated from -20 °C to 250 °C (or at least 30°C above the Melting Temperature of the sample) at a rate of 10 °C/minute. Each sample was then held for 1 minute at 250°C, and then subsequently cooled down to -20°C (or at least 50°C below the crystallization temperature of the sample) at a rate of 20 °C/min. Each sample was then held for 1 minute at -20°C and then subsequently heated from -20°C to 200°C at 10 °C/min.

The temperature corresponding to the highest-temperature endothermic peak was reported as the Melting Temperature (° C), and the area under the same highest-temperature endothermic peak was reported as the Heat of Fusion.

Examples of Blown Microfiber (BMF) and Composite BMF Webs

The following illustrate Examples of the preparation of various nonwoven fibrous webs prepared according to the processes described in the present disclosure, as well as Comparative Examples. Comparative Example C-l

A melt-blown (blown microfiber, BMF) nonwoven fibrous web was made using a crystalline polypropylene (crystalline polyolefin (co)polymer) resin having a 1200 melt flow rate (MFR), commercially available as METOCENE MF650X from Lyondell-Basell (Houston, TX). A conventional melt-blowing process was employed, similar to that described, for example, in Wente, Van A., "Superfine Thermoplastic Fibers" in Industrial Engineering Chemistry, Vol.48, pages 1342 et seq. (1956) or in Report No.4364 of the Naval Research Laboratories, published May 25, 1954, entitled "Manufacture of Superfine Organic Fibers" by Wente, Van A.; Boone, CD.; and Fluharty, E.L.

More particularly, the melt-blowing die had circular smooth surfaced orifices, spaced 10 to the centimeter, with a 5: 1 length to diameter ratio. Molten (co)polymer was delivered to the die by a 20 mm twin screw extruder commercially available from Steer of Uniontown, OH. This extruder was equipped with two weight loss feeders to control the feeding of the (co)polymer resins to the extruder barrel, and a gear pump to control the (co)polymer melt flow to a die. The extruder temperature was at about 250 °C and it delivered the melt stream to the BMF die, which itself maintained at 250 °C. The gear pump was adjusted so that a 0.268 kg/hr/cm die (1.5 lb/hr/inch die width) (co)polymer throughput rate was maintained at the die. The primary air temperature of the air knives adjacent to the die orifices was maintained at approximately 325 °C.

This produced a web on a rotating collector spaced 43 cm from the die. The web had a Basis Weight of approximately 55 g/m 2 . Significant fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 1

A BMF web was prepared generally as described in Comparative Example C-l, except that the polymer was a blend at a (95/5) ratio of METOCENE™ MF650X and a hydrocarbon tackifier resin commercially available as OPPERA™ PR100A from Exxon Mobil Corp. of Irving, TX. The web thus produced had a Basis Weight of approximately 55 g/m 2 , and a Solidity of approximately 4.37%. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 2

A BMF web was made as described in Example 1, except that the extruder temperature was about 275°C, the BMF die was maintained at approximately 275°C and the primary air temperature was at approximately 375°C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm. Example 3

A BMF web was made as described in Example 1, except that the extruder temperature was about 285°C, the BMF die was maintained at approximately 285°C and the primary air temperature was at approximately 375°C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 4

A BMF web was made as described in Example 3, except that the web was made using a blend of METOCENE™ MF650X and OPPERA™ PR100A at a (90/10) ratio. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 5

A BMF web was made as described in Example 4, except that the web was collected at a BMF die to collector distance of 35.6 cm. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 6

A BMF web was made as described in Example 5, except that the web was made using a blend of METOCENE™ MF650X and OPPERA™ PR100A at a (85/15) ratio. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 7

A BMF web was made as described in Example 5, except that the extruder temperature was about 295°C, the BMF die was maintained at approximately 295°C and the primary air temperature was at approximately 400°C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 8

A BMF web was made as described in Example 6, except that the extruder temperature was about 295°C, the BMF die was maintained at approximately 295°C and the primary air temperature was at approximately 400°C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Exemplary results for Comparative Example C-l and Examples 1- 8 are summarized in

Table 1. Table 1

Comparative Example C-2

A BMF web was made as described in Comparative Example C-l, except for the following details. The polymer used was a polypropylene resin commercially available as METOCENE™ MF650Y from Lyondell-Basell (Houston, TX). The extruder temperature was approximately 255 °C and it delivered the METOCENE™ MF650X melt stream to the BMF die maintained at 255 °C. The primary air temperature was maintained at approximately 335 °C. The die to collector distance was about 17 inches (43.18 cm).

Significant fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 9

A BMF web was generally as described in Comparative Example C-2, except for the following details. The polymer was a blend at a (95/5) ratio of METOCENE™ MF650Y and a hydrocarbon tackifier resin commercially available as OPPERA™ PR100A from Exxon Mobil Corp. of Irving, TX. The extruder temperature was approximately 260°C and it delivered the blend melt stream to the BMF die maintained at 260°C. The primary air temperature was maintained at approximately 335 °C. The resulting web had a Basis Weight of approximately 55 g/m 2 . No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 10

A BMF web was made as described in Example 9, except that the blend ratio of

METOCENE™ MF650Y to OPPERA™ PR100A was (90/10). No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 11

A BMF web was made as described in Example 10, except the extruder temperature was at about 270 °C and it delivered the blend melt stream to the BMF die maintained at 270 °C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 12

A BMF web was made as described in Example 11, except that the blend ratio of

METOCENE™ MF650Y to OPPERA™ PR100A was (85/15). No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 13

A BMF web was made generally as described in Example 9, except for the following details. The blend ratio of METOCENE™ MF650Y to OPPERA™ PR100A was (90/10). The extruder temperature was at approximately 270°C and it delivered the blend melt stream to the BMF die maintained at 270°C. The gear pump was adjusted so that a 0.536 kg/hr/cm die width (3.0 lb/hr/inch die width) polymer throughput rate was maintained at the BMF die. The primary air temperature was maintained at approximately 335 °C. The resulting web had a Basis Weight of approximately 55 g/m 2 . No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 14

A BMF web was made as described in Example 13, except that the blend ratio of METOCENE™ MF650Y to OPPERA™ PR100A was (85/15). No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 15

A BMF web was made generally as described in Example 10, except for the following details. Instead of the OPPERA™ PR100A resin, the METOCENE™ MF650Y resin was blended with a cycloaliphatic hydrocarbon tackifier resin commercially available as ESCOREZ™ 5400 from Exxon Mobil Corp., at blend ratio of (90/10). The extruder temperature was at

approximately 250 °C and it delivered the blend melt stream to the BMF die maintained at 250 °C. The gear pump was adjusted so that a 0.268 kg/hr/cm die (1.5 lb/hr/inch die width) polymer throughput rate was maintained at the BMF die. The primary air temperature was maintained at approximately 335 °C. This produced a web on a rotating collector spaced 30.5 cm from the die. This web and had a Basis Weight of approximately 64 g/m 2 . No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 16

A BMF web was made generally as described in Example 15, except for the following details. The ESCOREZ™ 5400 was replaced by ESCOREZ™ 5415, commercially available from Exxon Mobil Corp. (Houston, TX). The resulting web had a Basis Weight of approximately 60 g/m 2 . No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 17

A BMF web was made generally as described in Example 15, except for the following details. The ESCOREZ™ 5400 was replaced by a hydrocarbon tackifier resin commercially available as ARKON™ P-100 from Arakawa Chemical of Osaka, JP. The resulting web had a Basis Weight of approximately 61 g/m 2 . No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm. Exemplary results for Comparative Examples C-2 and Examples 9-17 are summarized in

Table 2.

Table 2

Example 18

A composite web was made using an apparatus generally as disclosed in Figure 2 of U.S.

Patent 7,989,371. Blown microfibers were included in the composite web using a blend of PP 650Y and OPPERA™ PR 100A at a (90/10) ratio. These fibers had an EFD of approximately 4.7. Crimped 6 denier polyethylene terephthalate staple fibers, commercially available from In vista of Wichita, Kansas, were also included in the composite web, with the ratio of blown microfibers to staple fibers being approximately 65 to 35. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm. Comparative Example C-3

A BMF web was made generally according to Comparative Example C-l, except for the following details. The polymer used was a polypropylene resin commercially available as TOTAL Polypropylene 3860X from TOTAL, Houston, Texas. The extruder temperature was set at about 310°C and it delivered the melt stream to the BMF die maintained at 310°C. The gear pump was adjusted so that a 0.268 kg/hr/cm die (1.5 lb/hr/inch die width) polymer throughput rate was maintained at the BMF die. The primary air temperature was maintained at approximately 400°C. The resulting web was collected at a BMF die to collector distance of 19 inches (48.3 cm) and had a Basis Weight of approximately 54 g/m 2 . The web had a Solidity of approximately 6.97%. Significant fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 19

A BMF web was made generally according to Comparative Example C-3, except for the following details. The extruder was charged with using a blend of polypropylene and polymethyl pentene polymer where the polymethyl pentene used had a melt flow rate of 180, commercially available as TPX DX820 from Mitsui Chemicals of Tokyo, JP. PP3860 and TPX DX820 were blended at a (95/5) ratio. The resulting web had a Basis Weight of approximately 53 g/m 2 . The web had a Solidity of approximately 6.90%. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 20

A BMF web was made as described in Example 19, except that the PP3860/TPX DX820 blend ratio was (90/10) and the extruder and die temperatures were maintained at 315 °C. The resulting web had a Basis Weight of approximately 56 g/m 2 . The web had a Solidity of approximately 7.21%. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 21

A BMF web was made as described in Example 20, except that Oppera PR100A was added to the polymer blend at the ratio PP3860/ TPX DX820 / OPPERA™ PR100A (90/5/5). The resulting web had a Basis Weight of approximately 54 g/m 2 . The web had a Solidity of approximately 9.93%. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Exemplary results for Comparative Example C-3 and Examples 19-21 are summarized in

Table 3. Table 3

Comparative Example C-4

A BMF web was made as described in Example 9, except for the following details. The BMF die used in the example consists of small orifice size ranging from 150 um and high orifice density of 10 hole/cm (25 hole/inch). In addition, the molten polymer was delivered to the die by a 12.7 mm single screw. The extrusion rate was maintained at 0.09 kg/hr/cm (0.5 lb/hr/inch die width). The extruder temperature was approximately 260 °C and it delivered the METOCENE™ MF650Y melt stream to the BMF die maintained at 270 °C. The primary air temperature was maintained at approximately 240 °C. Significant fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 22

A BMF web was made as described in Comparative Example C-4, except that

METOCENE™ MF 650Y was blended with OPPERA™ PR100A. The blend ratio of

METOCENE™ MF650Y to OPPERA™ PR100A was (95%/5% w/w). No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 23

A BMF web was made as described in Example 22, except that the extrusion temperature was about 280 °C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm. Example 24

A BMF web was made as described in Example 22, except that the blend ratio of METOCENE™ MF650Y to OPPERA™ PR100A was (90/10 w/w) and the extrusion temperature was 295 °C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Example 25

A BMF web was made as described in Example 22, except that the blend ratio of METOCENE™ MF650Y to OPPERA™ PR100A was (85/15 w/w) and the extrusion temperature was 315 °C. No fly was visually observed with the un-aided human eye under illumination with fluorescent lighting at a distance of about 30 cm.

Exemplary results for Comparative Example C-4 and Example 22-25 are summarized in

Table 4.

Table 4

Differential Scanning Calorimetry (DSC) measurements according to the foregoing test method were carried out to determine the Melting Temperature and Heat of Fusion of the crystalline polyolefin, the mixture of the crystalline polyolefin with the hydrocarbon tackifier resin, and the nonwoven fibrous webs produced from the mixture, for Comparative Example Cl- C4 and Examples 1-25. These results are summarized in Table 5. Table 5