MINERALS

BACKGROUND OF THE INVENTION

The present invention relates to the field of the manufacture and use of cellulose filaments from renewable resources as well as products including such filaments.

Energy and resource conservation is an ever growing area of focus. Energy costs continue to rise and many material sources such as those based on petroleum are under constant cost and availability concerns. Many products utilize petroleum-based materials such as polyolefin and other polymer-based filaments which are employed in the manufacture of fibrous nonwoven webs which are used to absorb and or dispense fluids. For example, many of the layers in personal care absorbent articles are made from polymer-based fibrous nonwovens. Particularly, in the area of nonwovens, petroleum-based polymers are a key source for manufacturing. An effort has been ongoing, however, to make such filaments and nonwovens from sustainable resources and to move away from more petroleum-based products. One area has been in connection with the manufacture of such filaments and nonwovens from renewable raw materials which are cellulose-based. Amongst a variety of other uses, cellulose is significantly used in consumer goods such as tissue and towel products.

With the manufacturing of tissue and disposable towel products, a substantial amount of sludge is produced which contains valuable cellulosic fibrous material that may also include additional minerals such as calcium carbonate. The cellulose is found in the waste material from the manufacturing of paper and paper/pulp-based products. Currently, the sludge is mostly disposed in landfills which create an environmental concern. It is believed, however, that the sludge may be useful as a valuable raw material for producing microfibrillar cellulose which, in turn, can be used for nonwoven manufacturing. The microfibrillar cellulose can be used as a precursor to producing filaments for compostable and biodegradable nonwoven substrates. Thus, the sludge waste can be reclaimed and used as a valuable raw material. The following demonstrates how this is possible and beneficial to both the environment and the industry.

SUMMARY OF THE INVENTION

The present invention relates to a cellulosic filament precursor dope comprising, based upon the total weight of said wet precursor dope, from about 7% to about 20% of microfibrillar cellulose fibers, about 1 % to about 5% of calcium carbonate, about 0.2% to about 5% of a thickening agent and about 75% to about 95% of a water-based solvent, said microfibrillar cellulose fibers being dispersed in said solvent and said thickening agent being dissolved in said solvent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an SEM image at 500μηι of a cellulosic textile filament made by the equipment and process described herein.

FIG. 2 is an SEM image at 500μηι of a cellulosic textile filament of the present invention using the equipment and process described herein.

FIG. 3 is an SEM image at 100μηι of a cellulosic textile filament made by the equipment and process described herein.

FIG. 4 is an SEM image at Ι ΟΟμηι of a cellulosic textile filament of the present invention using the equipment and process described herein.

FIG. 5 is an SEM image at 10μηι of a cellulosic textile filament made by the equipment and process described herein.

FIG. 6 is an SEM image at 10μηι of a cellulosic textile filament of the present invention using the equipment and process described herein.

Fig. 7 is an SEM image at Ι ΟΟμηι of the cross-sectional view of a filament made by the equipment and process described herein.

FIG. 8 is an SEM image at l OO^m of the cross-sectional view of a cellulosic textile filament of the present invention using the equipment and process described herein.

FIG. 9 is a schematic diagram of the one-shot filament extruder used to process cellulosic textile filaments described herein.

FIG. 10 is a proposed commercial grade process that may be used to form cellulosic textile filaments and fibrous nonwoven webs according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION The waste sludge produced from the tissue and disposable towel manufacturing can be a useful resource for providing a precursor cellulose textile filament dope (or "dope") that can be used as a base wherein a high percentage of a mineral is present or added such that the mineral content is greater than about 20% of the solid content or more particularly 25% of the solid content. As will be described below, the cellulose textile filament dope can also be manufactured as a raw material for industrial applications. However, it can be very expensive and thus, there is motivation to find alternative resources for this material.

The cellulose textile filament precursor dope has three main components, a solvent, microfibrillar cellulose and a thickening agent. To reduce manufacturing costs, particularly with respect to energy conservation, calcium carbonate mineral can be added to the microfibrillar cellulose. Beside a filler effect, the added mineral can also improve filaments strength due to the charge-charge interactions between the metal ions (Ca ²⁺ ) with cellulose.

SOLVENT

The solvent used to make the dope is water or a majority water-based solvent, thus, a solvent that is essentially water or at least 90%, by volume, of the solvent is composed of water. An important advantage of the present invention is its low cost, low energy approach to form the spinning dope and, particularly, the formation of a stronger filament that is used within fibrous nonwoven webs and end products. If desired, the water source may be purified and/or distilled but this is not necessary for the process and resultant material to work.

The process may be carried out at room temperature but if desired, the water-based solvent and the resultant cellulosic filament precursor dope may be heated to an elevated temperature. Whether heat is added to the process in some cases will depend on the thickening agent being used. Also, the range of temperatures used will depend on the pressures being used to extrude the filaments. At normal atmospheric pressure, temperatures must be below the boiling point of water so as to not cause bubble formation which could disrupt the filament formation. As a result, temperatures will generally be below about 200 degrees Fahrenheit (93°C). However, as extrusion pressures increase, the temperature of the precursor dope and the water contained therein may be elevated to temperatures above 212 degrees Fahrenheit (100°C) but generally, at normal sea level/STP conditions, the temperatures should remain between 185 and 195 degrees Fahrenheit (85°C - 90.5°C) so the water does not flash off as steam and disrupt the filament formation.

Typically, the water or water-based solvent will be present in the water-based dispersion dope in a weight percent of about 75% to about 95% based upon the total weight of the precursor dope including the dry and wet ingredients.

MICROFIBRILLAR CELLULOSE

The main dry component of the cellulosic textile filaments of the present invention is microfibrillar or microfibrillated cellulose also referred to as "MFC". Microfibrillar cellulose is a form of cellulose generated by applying high shear forces to cellulosic fibers to yield cellulose fibrils with a lateral dimension or diameter in the range of about 10 nm to about 100 nm and lengths which are generally in the micrometer scale.

Other than from the waste sludge from paper and paper/pulp-based manufacturing, there are a variety of sources available to form the microfibrillar cellulose of the present invention. Generally, any cellulosic source which can, with proper processing, yield microfibrillated cellulose fibers of the size mentioned above, become a source of such MFC for the present invention. Some examples of cellulose sources include, but are not limited to, wood pulp, algae, trees, grasses, Kenaf, hemp, jute, bamboo, and microbial cellulose.

Numerous articles and literature are available on microfibrillar cellulose, its sources and production. See, for example, Turbak A, Snyder F, Sandberg K (1983), Microfibrillated cellulose: A new cellulose product: properties, uses, and commercial potential, J Appl Polym Sci Appl Polym Symp 37:815-827. See, also, Chinga-Carrasco, Gary (June 13, 201 1 ), Cellulose fibres, nanofibrils and microfibrils: The morphological sequence of microfibrillar cellulose components from a plant physiology and fibre technology point of view, Nanoscale Res Lett. 201 1 ; 6(1 ): 417, published online 201 1 June 13, doi: 10.1186/1556-276X-6 17PMCID: PMC3211513.

Microfibrillar cellulose can be made, for example, by mechanical disintegration of cellulose fibers. To accomplish this, first, a cellulose source such as softwood pulp is milled and passed through a 0.50 millimeter sieve. Mills such as the Mini model, THOMAS® Wiley Mill, are available from Thomas Scientific in Swedesboro, New Jersey. After the cellulose has been milled, it is next refined using a PFI mill according to the TAPPI test method T 248 sp-08 for 3x1 Ok revolutions and then diluted with water to approximately 0.2 percent solids, based upon the total weight of the cellulose source and the water, and passed through a DeBee bench top homogenizer from BEE International Inc. of South Easton, Massachusetts three times at 22,000 pounds per square inch (1.52x10 ⁸ Paschals). Finally, the homogenized material is centrifuged with a Beckman Avanti J-E centrifuge at 12,000 revolutions per minute (rpm) for thirty minutes to obtain the microfibrillated cellulose.

Typically, the microfibrillar cellulose will be present in the water-based dispersion precursor dope in a weight percent of about 7% to about 20%, based upon the total weight of the precursor dope including the dry and wet ingredients. In the finished, dry filament, the microfibrillar cellulose content will range from about 65%, from about 70% or from about 80% to about 90%, to about 95% or to about 99.5%, by weight based upon the total dry weight of the filament. By "dry", it is noted that the weights are measured at ambient conditions and all water is assumed evaporated. For the examples and testing set forth below, microfibrillar cellulose was obtained from IMERYS Corporation, Roswell, GA and VERSO Corporation, Memphis, TN. The obtained microfibrillar cellulose once formed was centrifuged with a Beckman Avanti J-E centrifuge at 12,000 rpm for 30 minutes to yield a mud-like microfibrillar cellulose product having a weight of 109.1 grams and an average solids content of 15.2%.

CALCIUM CARBONATE

Minerals, such as calcium carbonate are added to enhance the MFC and arrive at the present invention. Such combination provides stronger filaments used to create the nonwoven web and minimize the use of polypropylene. Additionally, the addition of the mineral helps to improve the filaments strength due to the charge-charge interactions between the metal ions (Ca ²⁺ ) with cellulose. Advantages of filaments formed from microfibrillar cellulose with calcium carbonate are such that the filaments will have enhanced strengths compared to polypropylene fibers of similar size with less elongation. Also, filaments formed from microfibrillar cellulose and calcium carbonate can sustain higher drying and process temperatures than polymer-based fibers such as polyolefins including polypropylene. Unlike polyolefin-based nonwoven webs, filaments made from microfibrillar cellulose and calcium carbonate are inherently wettable and have higher absorbent capabilities. Thus, MFC combined with calcium carbonate minerals as demonstrated by the present invention can be beneficial to the manufacturing of nonwoven webs to create stronger and more sustainable materials.

Typically, the calcium carbonate will be present in the water-based dispersion precursor dope in a weight percent of from about 1 % or from about 2% to about 3% or to about 5%, based upon the total weight of the precursor dope including the dry and wet ingredients. In the finished, dry filament, the calcium carbonate content will range from about 20% or from about 25%, by weight based upon the total dry weight of the filament.

THICKENING AGENTS

To change the dynamic viscosity (also referred to as the complex viscosity) of the microfibrillar cellulose dispersed in the water-based solvent, thickening agents may be employed and dissolved in the water-based dispersion precursor dope to assist in the extrusion and filament forming process. Suitable thickening agents will increase the viscosity of the water-based dispersion of microfibrillar cellulose. Typically, the thickening agent will cause the water-based dispersion of microfibrillar cellulose to have a dynamic viscosity of between about 400 Pascal seconds (Pa s) and about 3000 Pa s at a shear rate of 100 reciprocal seconds (s- ¹ ), more specifically between about 800 Pa s and about 1250 Pa s @ a shear rate of 100 s- ¹ . Complex viscosity follows Newton's law and is written as t(t)=h*dg/dt. The star is used to indicate that the viscosity is measured in an oscillatory test rather than the normal steady state shear rate test, for example, in a capillary rheology measurement. According to the Cox/Merz rule, h(dg/dt)=|h*(w)| if the values of dg/d^s ¹ ) and w(d) are the same so complex viscosity can be used to set the processing conditions.

Complex viscosity is a frequency-dependent viscosity function determined in response to a forced sinusoidal oscillation of shear stress. It is obtained by dividing the complex modulus by the angular frequency (|h*|=|G*|/w) and is used to study the vistetic nature of a fluid. When a visco-elastic fluid is stressed in a sinusoidal manner, the resulting sinusoidal shear rate function is somewhere between, a completely in-phase and out-of-phase response. The in-phase component is the real part of the complex viscosity ( h -G"/w), also known as the dynairisEosity and represents the viscous behavior and the imaginary part of the complex viscosity (h"=G7w) represents the elastic behavior. The complex viscosity function is expressed as the difference between the in-phase viscosity and the out-of-phase viscosity or the imaginary components of the complex viscosity, h*=hH

The dynamic or complex viscosity can be measured using an Anton Paar Model Physica MCR

301 rheometer from Anton Paar GmbH of Graz, Austria at room temperature (70°F/21 °C) conditions. Determination of the complex viscosity of a cellulosic precursor dope can be determined in accordance with the manual for this apparatus.

Specific examples of thickening agents include, but are not limited to, polyethylene oxide (PEO), polyvinylpyrrolidone, polyvinyl alcohol (PVOH) from Sigma Aldrich Co, LLC of Saint Louis, Missouri, nanocrystalline cellulose, hemicellulose and nanostarch. Examples of PEO include those available also from Sigma-Aldrich including grade 372781 PEO with a viscosity average molecular weight (Mv) of 1 ,000,000, grade 182028 with a viscosity average molecular weight (Mv) of 600,000 and grade 181994 with a viscosity average molecular weight (Mv) of 200, 000. An example of a suitable polyvinylpyrrolidone is grade 437190 also from Sigma-Aldrich with a weight average molecular weight (Mw) of 1 ,300,000. As to the molecular weight of the thickening agent it should be noted that some molecular weights are reported by the manufacturers and suppliers as number average molecular weights (Mn), weight average molecular weights (Mw) and viscosity average molecular weights (Mv). Thus, the appropriate version of the molecular weight should be determined by standard methods as used by the industry for the particular material in question.

Other examples of thickening agents include, but are not limited to, maltodextrin, soy protein isolate, carboxymethylcellulose, alginic acid, gelatin, textured soy protein, guar gum, xanthan gum, modified corn starch, carrageenan, sugars, esters, calcium alginate, pectic, konjac, liquid glucose and sodium triphosphate. Further, it should be appreciated that this list is not exhaustive and other thickening agents are also contemplated to be within the scope of the present invention provided they are compatible with the other components of the water-based dispersion precursor dope and the process and equipment parameters chosen to form the filaments according to the present invention.

Generally, thickening agents which are suitable within the present invention will have viscosity average molecular weights (Mv) up to about 2,000,000. Generally, the viscosity average molecular weight of the thickening agent will range between about 200,000 and about 2,000,000 and more specifically between about 500,000 and about 1 ,000,000 though other molecular weights may be used depending on the particular end-use application. The amount of thickening agent that will be used will typically range, from about 0.2%, from about 0.5% or from about 1 % to about 3.0%, to about 4.0% or to about 5.0%, by weight based upon the total weight of the water-based dispersion precursor dope including the weights of the solvent, the microfibrillar cellulose, the calcium carbonate, the thickening agent and any other additives or components. The end result of the type and quantity of such thickening agents used in the precursor dope is the desire to yield a precursor dope that falls within the above- stated viscosity ranges so that suitable filaments may be extruded by the particular equipment being used.

In the finished, dry filament, the thickening agent content will range from about from about 0.5%, from about 8% or from about 10% to about 12%, to about 15%, or to about 20%, by weight based upon the total dry weight of the filament.

ADDITIONAL COMPONENTS

While a solvent, thickening agent, microfibrillar cellulose and calcium carbonate are the core components of both the precursor dope and the end-use filaments and fibrous nonwoven webs, other components may be included depending upon the particular end-use application. Other components include, but are not limited to, water-based binding agents. Di-aldehydes are on example of binding agents that may be used with the present invention. Typically the binding agent being used should be designed to not prematurely crosslink at a point where it interferes with the formation of the dope or filament forming process. As a result, it is desirable to use binding agents that can be activated or facilitated in their binding through the use of additional heat such as can be applied during a drying process after the filaments have been formed. One example in this regard is an acrylic latex binder which can be accelerated with heated air at temperatures of about 300°F/149°C. When other components are added to the dope, it is generally desirable to add them in an amount such that the finished, dry filament will have, based upon the total dry weight of the filament, from about 75% to about 99% microfibrillar cellulose fibers, from about 1 % to about 3% calcium carbonate, from about 20% to about 0.5% of a thickening agent and from about 0.5% to about 5% of other additional components.

EQUIPMENT AND PROCESS

The cellulosic textile precursor dope materials and filaments set forth in the examples below were made using bench scale equipment. The microfibrillar cellulose, calcium carbonate (when applicable), thickening agent and water were mixed in the prescribed proportions on a weight percent basis based upon the total weight of all wet and dry components in a 150 milliliter container and stirred by hand using a glass stirring rod to the highest level of uniformity and dispersion possible to form the precursor dope. Typically, this took approximately 60 minutes to 120 minutes of repeated intervals of stirring for one to two minutes and letting the sample rest for five to ten minutes until an acceptably uniform dispersion was obtained (visually no lumps). The precursor dope was then poured into the open end of a 30 milliliter capacity one shot filament extruder as shown in FIG. 9. The plunger (110) was replaced and the air removed. The exit orifice (not shown) on the extrusion barrel (120) which the dope was extruded has an approximate diameter of 0.3 millimeter. The extrusion barrel (120) was positioned at a 90 degree angle to a horizontal laboratory bench surface upon which there was placed on a nonstick conveyor belt (130), such as a polyurethane belt, which formed the horizontal forming surface upon which the dope was deposited. The space between the spinneret (140) and the conveyor belt (130) is approximately 3-5 inches above the forming surface.

While the extrusion barrel (120) was drawn backwards, the precursor dope was extruded from the orifice of the extrusion barrel (120) by depressing the plunger (110) into the extrusion barrel (120). Filaments were then extruded with lengths that were in the range of approximately 1 -2 meters (as shown in FIG. 1 -8). Initial wet diameters of the filaments were approximately less than 0.5 millimeter. The filaments were allowed to air dry at room temperature overnight. Once dried, the filaments exhibited shrinkage in their diameters. Dry diameters were approximately less than 100 microns (as shown in FIGS. 1-8). All portions of the above-described process were performed at room temperature (75°F/21 °C). Visual observation of the filaments showed them to be well formed and the filaments exhibited good tensile strength when pulled by hand.

Due to the low solids content of the water-based dispersion textile filament precursor dope, shrinkage of the newly formed filament and thus reduction in filament diameter must be factored into the process parameters. For example, if a 30 micron diameter filament is desired once the filament has dried from a precursor dope having a solids content of approximately 10%, the initial filament diameter will have to be approximately 95 microns to compensate for the shrinkage. This relationship is linear and so, for example, at the same 10% solids content, a 10 micron dry filament will require an approximate 32 micron wet filament diameter. In addition, draw down of the filament as it is extruded must also be taken into consideration. Typically, it should be assumed that the draw down in filament diameter in a commercial process will be in the range of 50% to 80%. Thus, if a dry filament diameter of 5 microns to 50 microns is desired, utilizing an approximate 15% solids precursor dope, it is anticipated that the wet filament diameter will have to be in the range of 70 microns to 100 microns. As a result, it is also anticipated that the extrusion equipment will have to utilize extrusion openings or orifices with diameters in the range of 70 microns to 100 microns to yield dry, finished filaments with filament diameters in the 5 microns to 50 microns range though this can be adjusted accordingly depending on the viscosity of the water-based dispersion precursor dope, the amount of draw of the filaments as they are extruded, the forming height of the extrusion orifices from the forming surface, the flow rate of the precursor dope from the orifices, the draw of the filaments and the speed of the forming surface.

The microfibrillar cellulose filaments were made using bench scale equipment but it is anticipated that conventional fiber extrusion equipment can be used. See, for example, U.S. Patent Nos. 6,306,334 and 6,235,392 both to Luo et al.; U.S. Patent Application Publication No. 201 1/0124258 to White et al. and WO 01/81664 to Luo et al. This type of equipment can be utilized to mix and spin the microfibrillar cellulose filaments according to the present invention with the difference being that 1 ) no chemicals need be added to the solvent used to dissolve the cellulose, 2) minimal gas or mechanical stretching need necessarily be used due to the tenacity of the filaments being formed, 3) no insolubilizing step need be used and lastly, 4) no washing or other chemical extraction step need be implemented to yield the resultant filaments. Figure 5 illustrates a schematic diagram of a prophetic process which could be used to form the filaments and fibrous nonwoven webs according to the present invention.

FIG. 10 shows a process and equipment 200 according to the present invention including a precursor dope tank (212), a spin pump (214) and an extrusion die (216). The precursor dope is placed in the dope tank (212) and pumped to the extrusion die (216) by way of the spin pump (214). The precursor dope exits the extrusion die (216) in the form of filaments (220) which are deposited onto a forming surface (224). If desired, an optional drawing unit (222) can be used between the extrusion die (216) and the forming surface (224) to further draw and attenuate the filaments as they exit the extrusion die (216) and before they are deposited onto the forming surface (224). A vacuum assist (226) may be used to facilitate the deposition of the filaments down onto the forming surface (224) to form a fibrous nonwoven web (228). After the web (228) is formed, it may be subjected to a drying step via a dryer (230) and, if desired, further processing steps as mentioned above including, but not limited to, such steps as calendering and/or embossing by passing the nonwoven web (228) through the nip (232) of a pair of calender/embossing rolls (234) and (236) either or both before and after the dryer (230). It is also known that a two stage drying process may be employed (not shown). Typically water add-on would be no more than about 5%, by weight based upon the weight of the fibrous nonwoven web and the water.

Filaments have a diameter of from about 5 microns to about 50 microns and were tested for peak load, peak stress and strain-at-break utilizing a MTS® Synergie 200. Gauge length was approximately 1.0 inch and the pressure for the grips of the machine was set to about 60 psi. It is desirable that the filament properties also have a peak load (gf) from about 25 gf or from about 30 gf to about 60 gf or to about 75gf; a peak stress (MPa) from about 45 Mpa or from about 50 MPa to about 70 MPa or to about 80 MPa; and a strain-at-break of from about 3.5% or from about 4.0% to about 5.0% or to about 5.5%. Other property values can be found herein under Table 1.

It is desirable that the cellulosic filaments of the present invention, as described herein, may be used at least in a portion of an absorbent article such as a diaper, a diaper pant, a training pant, an incontinence article, a feminine hygiene article, a bandage or a wipe.

EXAMPLES

The MFC concentrate before it is let down is a very thick paste. As a result, water must be added in increasing amounts to the MFC to generate a precursor of suitable viscosity. Once this is done, specified amounts of PEO thickening agent can be added. If need be, additional water can be added during the hand mixing process to yield a precursor dope with suitable viscosity after which the dope can be extruded by hand with the above described syringe. Satisfactory dopes were made with and without calcium carbonate to compare the resulting filaments produced. Dopes made without calcium carbonate consisted of a solid content wherein the solid comprises: 8% microfibrillar cellulose, 1.0% PEO and 0.5% PVOH based on the total weight of all wet and dry ingredients in the dope. Dopes made with calcium carbonate consisted of a solid content wherein the solid comprises: 8% microfibrillar cellulose, 1.0% PEO, 2% calcium carbonate and 0.5% PVOH based on the total weight of all wet and dry ingredients in the dope.

A total of three samples of microfibrillar cellulose precursor dope were made and formed into filaments. MFC dope was loaded into the barrel of a mini-extruder (FIG. 13) with care to minimize air pocket. After the air bubbles was manually pushed through the mini-extruder, a single filament was extruded onto a non-sticky sheet through a single die tip (0.4 mm for Dope A and B; 0.3 mm for dope C). The single filaments were left to air dry. As shown by the images in FIG. 1 -8, filaments made with the calcium carbonate comparatively resulted in thicker and stronger filaments. In some instances, MFC dope was load into the barrel of an extruder with care to minimize air pocket. Using the extrusion set up, single filaments were extruded onto the conveyor belt (125 ft/min) through a single die tip (0.5 mm). The single filaments were left to air dry.

The resulting filaments were tested for peak load, peak stress and strain-at-break utilizing a MTS® Synergie 200. Gauge length was approximately 1.0 inch and the pressure for the grips of the machine was set to about 60 psi.

EXAMPLE A

2 g of polyvinyl alcohol (PVOH from Sigma Aldrich, 99% hydrolysis, MW 89,000-98,000) was added into 225.6 ml of distilled H20 with continuous stir on a hot plate until complete dissolved. Slowly, 4 g of polyethylene oxide (PEO from sigma Aldrich, MW 1 ,000,000) was added into the H20/PVOH solution with stir until dissolved. H20/PVOH/PEO solution was poured into the container of a Netzsch PMH 1 / PML 1 Laboratory Planetary Mixer (NETZSCH Lohnmahltechnik GmbH Max-Fischer-Str. 20b 86399 Bobingen Germany). 168.4 g of Microfibrillated cellulose MFC (Verso, derived from soft wood kraft pulp, 19% solid) was added to the above solution and mixed until a uniform MFC dope formed.

EXAMPLE B

2 g of polyvinyl alcohol (PVOH from Sigma Aldrich, 99% hydrolysis, MW 89,000-98,000) was added to 205.8 ml of distilled H20 with continuous stir on a hot plate until complete dissolved. Slowly, 4 g of polyethylene oxide (PEO from sigma Aldrich, MW 1 ,000,000) was added into the H20/PVOH solution with stir until dissolved. H20/PVOH/PEO solution was poured into the container of a Netzsch PMH 1 / PML 1 Laboratory Planetary Mixer. 188.2 g of Microfibrillated cellulose MFC (IMERYS, derived from soft wood kraft pulp, 17% solid with 75% fiber and 25% CaC03) was added to the above solution and mixed until a uniform MFC dope was formed.

EXAMPLE C

4 g of polyethylene oxide (PEO from sigma Aldrich, MW 1 ,000,000) was added into 185.5 g of distilled water with continuous stir until complete dissolved. H20/PEO solution was added into the container of a Netzsch PMH 1 / PML 1 Laboratory Planetary Mixer. 211.5g of Microfibrillated cellulose MFFC (IMERYS, derived from soft wood kraft pulp, 23% solid with 75% fiber and 25% CaC03) was added to the above solution and mixed until a uniform MFC dope was formed.

Table 1

Weight percentages are given based on the total weight of the microfibrillar cellulose, calcium carbonate (when applicable) thickening agent and water.

*Assuming water completely evaporated

These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood the aspects of the various embodiments may be interchanged either in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in the appended claims.