APPARATUS AND METHOD FOR MANUFACTURING A PACKAGING MATERIAL

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for manufacturing a packaging material that incorporates a barrier layer. More specifically, the present invention relates to an apparatus and method for manufacturing a packaging material using liquid phase atmospheric photo chemical deposition to apply a barrier layer on a moving web substrate.

BACKGROUND OF THE INVENTION

Flexible and non-flexible packages having at least one layer

of a polymer material have been used in the packaging industry for a

substantial period of time. Non-flexible packages are generally

manufactured from a laminate material that includes a paperboard

support layer and inner and outer layers of thermoplastic materials that

are heat sealable to one another. Flexible packaging materials often do not include a structural support layer (although they may contain a thin substrate layer of, for example, paper) and are often used to form

pouch-type containers. Packages made from these laminated materials

have the requisite properties for packaging non-aromatic foodstuffs that

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are generally insensitive to oxygen but are not suitable for aromatic,

oxygen-sensitive foodstuffs, such as orange juice or the like.

Packages for aromatic, oxygen sensitive foodstuffs are generally

made from laminated materials incorporating a barrier layer, either as a

product contact layer or as an intermediate layer in a multilayer laminate.

One of the most commonly used barrier layer materials is aluminum.

Another commonly used barrier material is ethylene vinyl alcohol (EVOH) .

Other materials have been found to exhibit excellent barrier properties. One set of materials that has been shown to exhibit

excellent barrier properties is the silicon based materials. These materials include silicon oxides (SiOx) such as silicon dioxide (SiO ₂ ), and silicon

nitride (Si ₃ N ₄ ). Packaging materials incorporating such silicon based materials are set forth in U.S. Patent No. 5, 1 22,410, issued June 16,

1992, to Lfgren, the teachings of which are hereby incorporated by

reference. Generally stated, the '410 patent discloses a laminate

material comprising a carrier layer of thermoplastic material and a barrier layer of inorganic material that is joined to a further carrier/barrier layer

at the faces of the barrier layers by a bonding agent. In one

embodiment, the barrier layers are silicon based layers, each having a

thickness of 50 - 500 C. In the illustrated embodiments, the silicon

based barrier layers are formed on the respective thermoplastic carrier

layers using a vacuum deposition process.

The existing vacuum deposition processes used in the manufacture of the multilayer barrier materials are prohibitively costly due to the equipment, time, and energy needs associated with batch processing the materials in a chamber that has been evacuated to a pressure that is substantially below atmospheric pressure. One such process that has been utilized to deposit SiOx materials onto a web in a batch process is a plasma-enhanced chemical vapor deposition (PECVD) process described in U.S. Patent No. 5,224,441 . Other CVD processes are shown, for example, in U.S. Patent Nos. 4,495,218 to Azuma et al.; 5,364,667, to Rheiu. These processes tend to be prohibitively costly and have generally not been economical for the production of packaging laminate materials.

SUMMARY OF THE INVENTION

An economical apparatus and method for forming a barrier layer

on a substrate material is set forth which eliminates many of the

problems associated with prior processes. In accordance with the

method of the present invention, a continuous web of substrate material is provided on which the barrier layer is to be formed. The web of substrate material is driven, either continuously or in an indexed fashion,

through a deposition system. The deposition system includes a coating

apparatus that coats a surface of the web of substrate material with a

precursor, such as a liquid precursor. The continuous web of substrate material is subsequently driven through a reaction chamber of the deposition system wherein there is provided a flow of oxidizer gas over

the surface of the web on which the precursor has been applied . The reaction chamber has an internal pressure of about one atmosphere.

The continuous web of substrate material and the oxidizer gas are

exposed to ultraviolet radiation in the reaction chamber as the

continuous web of substrate material is driven therethrough to thereby

provide a barrier layer on the web of substrate material. In accordance

with one embodiment of the method, the precursor is a liquid silicon

precursor and the resulting barrier layer is a silicon-based barrier layer.

The method allows a continuous web of substrate material to be

continuously processed at a reaction pressure of about one atmosphere

thereby making the production of the resulting packaging material more

economical than the batch processing at low pressure that is required of the prior processes.

An apparatus for implementing the method of the invention is also

set forth. The apparatus comprises a web dispenser supporting a

continuous web of substrate material and a deposition apparatus. The deposition apparatus comprises a) a coating apparatus for placing a layer

of precursor, for example, a liquid precursor, on the surface of the web,

b) a reaction chamber, c) at least one driving mechanism for driving the

web through the coating apparatus and the reaction chamber, d) an

ultraviolet energy source disposed to radiate ultraviolet energy into the

reaction chamber, e) at least one gas inlet for conducting a flow of an

oxidizing gas into the reaction chamber, pressure within the reaction

chamber being about one atmosphere, the oxidizing gas and precursor

on the continuous web of substrate material being exposed to the

ultraviolet light energy from the ultraviolet lamp to thereby cause

formation of a barrier layer on the web of substrate material.

In accordance with further enhancements to the apparatus and method of the present invention, the temperature of the moving web

of substrate material is controlled, at least in part, by passing the web over a cooling table as it is processed in the reaction chamber.

Additionally, the precursor, oxidizer, ultraviolet light intensity, substrate

material, and web speed through the reaction chamber may be chosen

so that the deposition of the barrier layer takes place at a temperature

of less than about 200E C within the reaction chamber. Selective

deposition of the barrier material may take place using photo masking techniques.

The foregoing apparatus can be used in any one of a variety of

system configurations. For example, the foregoing apparatus can be

used in a modular fashion to accommodate low deposition rates with

high speed web rates through the system. This provides better regulation of the thickness and quality of the barrier layer formed on the

substrate. Additionally, it provides the opportunity to form multi-layer

laminates having different layer compositions coated thereon. To this

end, a plurality of reaction chamber modules may be arranged so that the continuous web of substrate material is passed through a series of

the devices, each device contributing to a predetermined thickness of

the barrier layer material. Additionally, the apparatus can be utilized in a first web converting system wherein the barrier layer is, for example, the product contact layer of the packaging material or in a second web

converting system wherein a further material layer is joined on or over

the barrier layer of the substrate/barrier material after processing by the

deposition apparatus. In either instance, the resulting laminate material may be taken up onto a rewinder roll for transport and use in

subsequent converting or packaging operations. In accordance with a

still further system utilizing the foregoing apparatus, the apparatus is disposed at the input of a packaging machine wherein the resulting

substrate/barrier material is transported after the deposition of the barrier

layer to the input of the packaging machine for forming the material into a package which is both filled and sealed.

Other objects, features, and advantages of the present method and apparatus will become apparent on review of the following drawings and accompanying description.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of one embodiment of a deposition

system constructed in accordance with one embodiment of the present invention.

Fig. 2A is a cross-section side view of one embodiment of a web

inlet suitable for use in the system of Fig. 1 .

Fig. 2B is a cross-section side view of a further web inlet suitable

for use in the system of Fig. 1 .

Figs. 3A and 3B are system diagrams illustrating the use of a

plurality of serially disposed modules of the general type shown in FIG.

1 .

Fig. 4 is a system diagram illustrating one embodiment of a web

handling system for use with a deposition system such as the one set

forth in Fig. 1 .

Fig. 5 is a system diagram of a packaging system employing a

deposition system and web handling system that feeds a material

web directly from the output of a deposition device to the input of a

packaging machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to Fig. 1 , there is shown a deposition system 20

constructed in accordance with one embodiment of the present invention. The deposition system 20 includes a coating apparatus 25,

for example, a liquid coating apparatus, and a reaction chamber apparatus 30. A continuous web of substrate material 35 extends from

a location exterior to the liquid coating apparatus 25, and through both the coating apparatus 25, illustrated here as a liquid coating module, and

the reaction chamber apparatus 30, shown here as a separate system

module. The liquid coating module 25 and the reaction chamber module

30 may be formed separately, as illustrated, or in an integrated fashion as a single device. As will be set forth below, there is a high degree of

flexibility associated with the use of separate modules.

The web of substrate material 35 is first driven through the

coating apparatus 25 where a precursor, for example, a liquid precursor, is applied to the surface 40 of the web. More particularly,

the liquid coating module 25 may apply the precursor to the upper surface 40 of the web of substrate material 35 using any one of several

coating techniques, such as, gravure printing, spray coating, immersion coating, etc. Such liquid coating techniques are well known.

The coated substrate web then exits the liquid coating module 25 and passes through the reaction chamber apparatus 30. More

particularly, the web enters the web inlet portion 45 of the reaction chamber module 30, passing through a reaction chamber 50, to a

location exterior to a web outlet portion 55 of the module 30. The

continuous web substrate 35 is driven in the direction illustrated by

arrows 60 in a continuous manner or in an indexed fashion through the

deposition system 20. The continuous web of substrate material 35 may

be a single polymer, such as polyethylene (LDPE, VLDPE, LLDPE, etc.),

polyethylene terephthalate (PET), etc., or a multilayer laminate, for

example, a paperboard based material coated with at least one layer of polyethylene. Numerous polymers and polymer layer combinations are

suitable for use as the web substrate 35. A known surface treatment,

such as corona or flame treatment, may be performed on the web substrate 35 prior to processing by the deposition system 20.

A barrier material is formed on the continuous web of substrate

material 35 as it passes through the reaction chamber 50. To this end,

an oxidizing gas and carrier gas are supplied at a first gas inlet 65.

These gases are directed through region 70 in the direction indicated by

arrow 60 under the guidance of a baffle wall 75. Baffle wall 75

terminates in a curved section 80 at an open region where the gases are deflected in a direction indicated by arrows 85 and 90 over the upper

surface 40 of the web 35. The gases entering the reaction chamber 30

may be heated, for example, in a manner that will be described below.

Although the oxidizing and carrier gases are illustrated as entering the

reaction chamber 50 through a single inlet 65, it will be recognized that

multiple inlets may be used for communication of these gases to the

reaction chamber 50.

An ultraviolet radiation module, shown generally at 100, is

disposed to irradiate the oxidizing gas and liquid precursor on surface 40

so as to result in the formation of a barrier layer on the upper surface 40

of the web substrate 35. In the illustrated embodiment, the ultraviolet

radiation module 100 includes one or more ultraviolet lamps 102

disposed beneath a reflector hood 103 within a housing 105. Cooling

ports (not illustrated) may be used to conduct a cooled air flow through region 107 to cool the reflector hood 103 and UV lamp 102. An

ultraviolet transparent window 1 10 is disposed at one end of the

housing 105 proximate the upper surface 40 of the web substrate 35.

One type of ultraviolet lamp that may be utilized is a model EPIQ 6000 lamp available from FUSION UV Curing Systems of Rockville, Maryland.

Such a lamp has a generally broad spectrum extending from 200 nm to

450 nm and has a power output of about 600 Watts/inch. Another type

of lamp suitable for use in the present system is an excimer (KrCI) lamp

such as one sold by Hereus Noblelight. Such an excimer lamp is

characterized by a narrow wavelength centered, for example, at 222 nm

and has a power output of about 1 70 Watts/inch. The choice of

ultraviolet lamp type is principally determined by the absorption spectrum of the liquid precursor and oxidizing gas molecules that have

to react with one another and, further, by the absorption spectrum of

the web of substrate material 35.

The liquid precursor and oxidizing gas react with one another

under the influence of the ultraviolet radiation emanating through the

window 1 10. It is also possible that such reactions may also take place at the window surface 1 1 5 as well as at the upper surface 40 of the

web 35. To reduce the deposition of the barrier material on the window

surface 1 1 5, a further flow of carrier gas is introduced through a second

gas inlet 1 20 and an optional third gas inlet 121 . This flow of carrier gas is directed through region 125 and is separated from the

oxidizing/carrier gas stream by the baffle wall 65. In the illustrated

embodiment, the curved portion 70 assists in directing the carrier gas

from region 1 25 in a direction, illustrated here by arrows 1 30, across window surface 1 1 5 to purge any evaporated precursor and oxidizing reactants from the region adjacent the window surface 1 1 5. A further flow of carrier gas is directed through inlet 1 21 and into region 1 31 in

the direction of arrows 1 32 where it is directed to the window surface 1 1 5 by further baffle 133 to further assist in separating the flow 90 of

the oxidizing gas from the flow 132 of the purging gas. The carrier gas,

residual gas, and byproduct gases ultimately flow into region 1 35 where

they are removed through exhaust outlet 135, for example, to be

released into the atmosphere, to be stored in a containment vessel, to

be separated and recycled, etc. The pressure within the reaction chamber 50 will typically be

about one atmosphere and, preferably, slightly greater than one

atmosphere. As such, it is necessary to ensure as tight a seal as

possible at the web inlet and outlet portions 45 and 55 while still

allowing the web of substrate material 35 to readily pass therethrough.

To accomplish this, the inlet and outlet portions 45 and 55 may be

provided with a web sealing device 1 50, such as shown in Fig. 2A.

The web sealing device 1 50, shown here at the inlet portion 45,

includes a channel guide member 1 55 that extends through a sidewall

160 of the reaction chamber module 30. The channel guide member

1 55 is elongated in the direction of web movement and defines a

channel region 1 65 through which the web 35 passes into the interior

of the reaction chamber module 30. Flexible sealing members 1 70 and

1 75 are disposed at opposite ends of the channel region 1 65 and, for example, may be integrally formed with the channel guide member 1 55.

The flexible sealing members 1 70 and 175 may be of sufficient length

to contact the upper surface 40 of the web 35 and urge the web 35

against a lower wall 1 76 of the channel region 1 65. In this manner, the web 35 passes through a generally sealed antechamber (or in the case

of a web sealing device at the web exit portion 55, a generally sealed

post-chamber) which assists in isolating the reactant and carrier gases

within the reaction chamber 50 from the atmospheric gases. Such a partial seal also increases the integrity of the barrier layer by reducing

the possibility of the entry of contaminants into the reaction chamber

30.

The precursor material disposed in the surface 40 of the web 35 may become contaminated as it travels between the liquid coating module 25 and the reaction chamber module 30. To prevent such

contamination, end 1 77 of the web sealing device 1 50 may extend to

the web exit end 1 78 of the liquid coating module 25. The particular

manner in which contamination is avoided is dependent on the particular

system configuration that is utilized.

Another web sealing device is shown in Fig. 2B. As illustrated,

the web sealing device 1 80 is disposed through sidewall 1 60 of the reaction chamber module 30 and includes an upper roller 181 and a lower roller 182 that extend along at least the width of the web 35.

The web 35 proceeds between the rollers 1 81 and 1 82 and into the

interior of the reaction chamber module 30. The edge portions of the sidewall 160 may be provided with gaskets to further seal the interior of the module 30 from external contaminants.

With reference again to Fig. 1 , it is possible to select a precursor,

oxidizing gas, web material, and web speed that allows the deposition of the barrier material to take place in the reaction chamber 50 at

temperatures about or below 200E F. Depending on the material(s) used

for the web substrate 35, such temperatures may cause one or more

layers of the web substrate 35 to go to a molten state. To prevent this from occurring, and to facilitate formation of the barrier material on the

upper surface 40 of the web 35, a cooling table 1 85 is provided over

which the web substrate 35 is transported as it passes through the

reaction chamber 50. The cooling table 1 85 functions as a heat sink for the web 35 and, for example, may be cooled by water tubes or the

like extending throughout its interior. Other cooling mechanisms may

likewise be employed to cool the cooling table 1 85 and/or the web

substrate 35.

Figs. 3A and 3B illustrate modular approaches to utilizing the

components of the deposition system 20. In the exemplary modular

system shown in Fig. 3A, a plurality of reaction chamber modules 30 are

arranged in a serial fashion along the direction of travel of the web

substrate 35. The reaction chamber modules 30 are connected to a

common carrier gas source 195 and oxidizing gas source 200. Pressure

regulating valves 210 are disposed between each of the sources 195

and 200 and their respective common lines 21 5 and 220. Flowmeters

235 are disposed in the oxidizing gas line 220 to monitor flow of the oxidizing gas to the first gas inlet 50 of each of the reaction chamber

modules 30. Flowmeters 240 are also disposed in each interconnect

line 245 that connects the line 21 5 supplying carrier gas to the first gas

inlet 50. Similarly, flowmeters 250 are disposed in line with the second

gas inlet 1 20 to monitor the flow of carrier gas that is used for purging

of the window surface 1 1 5 (Fig. 1 ). Flowmeters 252 may also be used to monitor carrier gas flow at inlet 121 . Flowmeter information may be

in a digital format suitable for monitoring by a central controller. The reaction chamber modules 30 of the illustrated embodiment

are all connected directly to one another in series. However, an

alternative modular configuration may also be utilized, such as is shown

in Fig. 3B, wherein one or more liquid coating modules 25 are disposed

at strategic locations along the travel path of the web 35. For example,

a liquid coating module 25 may be disposed between each of the

reaction chamber modules 30 to receive the web from the output of the

respective prior reaction chamber module 30, apply the precursor, and

supply the web 35 to the input of the respective subsequent reaction chamber 30.

Using the deposition modules 25, 30 in a tandem fashion gives

rise to several advantages over the use of a single device. For example,

the tandem deposition devices can provide more accurate control of the

thickness of the barrier layer since a single barrier layer may be formed on the web substrate 35 by depositing a series of thinner layers whose

thicknesses are easier to control. Additionally, the speed of the web substrate 35 through the deposition devices for a given barrier layer

thickness may be increased for large scale production. Also, the modular set-up facilitates quick and economical adaptation of the

production line to accommodate the production of different packaging

materials having different substrate/barrier characteristics.

Various web handling systems are suitable for driving the web

substrate through the deposition system 20. One exemplary system

suitable for initial material production or converting operations is shown

in Fig. 4. As illustrated, the web handling system, shown generally at

260, includes a web dispenser 265 and web recoil roll 270. The web of substrate material 35 extends between the web dispenser 265 and

web recoil roll 270 and through the deposition system 20 in the

illustrated manner over a plurality of idler rollers 275 and dancer rollers

280. Each dancer roller 280 is connected to a tension cylinder 285 that

assists in adjusting the tension of the web substrate 35 as it passes

through the deposition device 20.

The web handling system 260 may be controlled by a central

controller 300 which, for example, includes one or both a programmable

logic controller, a programmable axis manager, or other type of

controller capable of controlling an electric motor, such as a servomotor.

The controller 300 receives position information along one or more lines 305 and 310 indicative of the position of dancer rollers 280. This

information is used by the controller 300 to control the speed of motors

31 5 and 320 (i.e., servomotors) which are connected to drive the web

dispenser 265 and web recoil roll 270, respectively, and motor 320 which is connected to output drive roller 325. The controller 300

effects control by sending signals along lines 330, 335, and 340, to

maintain the speed of the web 35 through system 20 at the desired rate

while further maintaining the tension of web 35 at the requisite tension. Tension of the web 35 may also be monitored using a tension sensor

345 that supplies a signal indicative of tension on the web 35 along one

or more lines 350. Web tension should be chosen to ensure that the barrier material does not crack or otherwise create flaws in the barrier

material.

The central controller 300 may also be used to monitor and

control the flow of gases through the deposition system 20, the

temperature within the reaction chamber, and the coating of the

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precursor by the liquid coating module. To this end, signals indicative

of the flow of the respective gases through the deposition system 20 are provided to the controller along one or more lines 350. In response

to these received signals, the controller 300 provides output signals

along one or more lines 355 to, for example, mass flow controllers

and/or other flow control valves to automatically regulate the supply of

gases. Gas flows may be set to and maintained at a predetermined constant level or dynamically changed in response to barrier layer

thickness as monitored, for example, by a barrier thickness sensor 360

that supplies a signal indicative of barrier thickness along one or more lines 365. As will be readily recognized, web speed and tension, and gas flows will vary depending on the barrier material, substrate material,

desired barrier material thickness, etc.

The use of one or more deposition devices in a single integrated

packaging system is illustrated in Fig. 5. The packaging system, shown

generally at 500, includes a deposition system 20 and a packaging

machine 51 5. The deposition subsystem 510 deposits a barrier material layer on the web substrate 35 and provides the substrate/barrier

material 520 to the input of the packaging machine 51 5. The packaging machine 51 5 may, for example, be a TBA-9J aseptic packaging machine

available from Tetra Pak, Inc. The packaging machine 51 5 receives the web of substrate/barrier material 520 and forms the material into a

container, for example, a brik-type container, that is filled and sealed.

Other packaging machine types may also be utilized, the TBA-97

machine being merely exemplary.

The barrier layer of the web substrate/barrier material need not be the product contact layer of any resulting package found from the

material. Rather, the substrate/barrier material may have a further material joined to it at the face of the barrier layer. Exemplary systems

for placing one or more further layers of material over the barrier layer are illustrated in copending application U.S. S.N. 08/527,414, filed

9/1 3/95, entitled, "APPARATUS AND METHOD FOR MANUFACTURING

A PACKAGING MATERIAL USING GASEOUS PHASE ATMOSPHERIC

PHOTO CHEMICAL VAPOR DEPOSITION TO APPLY A BARRIER LAYER TO A MOVING WEB SUBSTRATE ", (Attorney Docket No. 1091 7US01 -

Corporate Docket No. TRX-0208), filed 9/1 3/95, which is hereby

incorporated by reference. Similarly, further exemplary embodiments of

the reaction chamber module are disclosed in that application.

If a barrier layer of SiOx material is desired to be formed on the

web of substrate material 35, the precursor may be an organic silane

such as tetraethoxysilane (TEOS), tetramethyldisoloxane (TMDSO),

triethoxysilane (TROS), silicon (IV) acetate, tetraacetoxysilane, or a

siioxane such as hexamethyldisiloxane (HMDSO) that are pure, dissolved

in a solvent, or mixed together for application by the liquid coating

apparatus. Other silicon precursors may also be utilized, although

organic silanes are preferable since they tend to be safer for use in large

scale processing. The oxidizing gas may, for example, be an oxidizer

such as N ₂ O or O ₂ . The carrier gas may be an inert gas such as N ₂ , Ar, or He. Photoinitiators and photsensitizers in the reactive gas or liquid

phase may be used to promote the photoreaction between the

precursor(s) and oxidizer(s).

While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood,

of course, that the invention is not limited thereto since modifications

may be made by those skilled in the art, particularly in light of the

foregoing teachings. It is therefore contemplated by the appended claims to cover such modifications as incorporate those features which

come within the spirit and scope of the invention.