PH26886A - Non-foil composite structures for packaging juice - Google Patents

Description

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BACKGROUND OF THE INVENTION

The invention relates to heat-sealable bare rier laminates for the containment of essential oils and the prevention of loss of vitamin C in paperw board cartons, ac well as to a process for making such laminates. More particularly, this invention relates to barrier laminates which are comprised of an improved heat-seal able non-foil composite strucw ture which retains the vitamin C in juice at nutrie tional=claims levels throughout the normal expected shelf life when the carton/package is made as well ’ as improving tho retention of citrus juice flavor ’ oils therein. . .

Hent-senlable low-density polyethylenes are well known to be components of current paperboard citrus juice cartons which provide little barrier to absorption and/or transmission of citrus juice essen- tial flavor/aroma oils. Additionally, it is well known that impermeable materials such as aluminum foil, polar materials such as: polyamides, poly ethylene tcrephthalates, polyvinylidene chloridesy polyvinyl chlorides, etCo, and highly crystalline non-polar materials such as high-density polyethylene and polypropylene provide varying degrees of barrier to the absorption and/or transmission of nonepolar

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J citrus juice flavor oils such at d-Limonene, et.al.

However, these materials require a thick liquid con- tact low density polyethylene layer for heat seal=~ ability as well as an expensive tie lger to provide consistent adhesion between the LDPE and the barrier material. The thick LDPE liquid contact layer (1.5 : mil) generally required in such cartons also absorbs citrus flavor/sroma oils, with resultant deleterious effects on product quality.

The existing commercial structure for a paper- ‘board carton for juice and similar products has utim

To, lized an easily heat-sealable barrier laminate com= posed of paperboard sandwiched between two layers of low density polyethylene (LDPE) + The LDPE is an in= expensive heat-sealable moisture barrier. The cone ventional structure falters in that the thick LDPE ‘ layer absorbs the essential oils of the juice after short periods of time causing intejrity decay of heat seals, stress cracking of the layer and allows trans- mission of the essential oils into the paperboard and to the atmosphere. Additionally, the conventional structure provides virtually no barrier resistance to } oxygen causing the juice to lose vitamin C in large , amounts.

One other conventional structure adds two addi 1 “3. oo i tional layers to thee structure identified above, name- ly a foil layer and an additional LDPE layer. The exe pensive foil layer increases barrier resistance to the flow of oxygen, while the additional LOPE allows for ultimate heat-sealability of the laminate. The improved conventional structure has poor barrier properties re- lating to the absorption of essential oils and aromas, since the interior contacting layer is still a thick layer of LOPE.

The object of the present invention is to pro- duce an improved juice packaging heat-gealable laminate ’ material for a juice carton which does not transmit flavor/odor ingredients of citrug and other juices and pxhibits an improved cost-to-performance ratio relative to fpil-lined cartons.

SUMIMARY OF THE INVENT ION

The preferred embodiment of the present invention reveals an improved non-foil composite structure provid- ing a substantial barrier to the loss of vitamin C and an almost complete barrier to the loss of essential flavor oils over the shelf life period of the carton (six weeks) and for beyond the six week period as well. The pre- ferred embodiment comprises from the puter atmosphere exposed surface to the inner surface contacting the essential pils and/or flavors (linuid juice); a first exterior layer of a low density polyethylene polymer; a paperboard substrate; an interior laminate coating comprising a Plexar tie layer, an ethylene vinyl alcohnl copolymer (EVUH) layer, and another

Plexar tie layer and a second layer of a low density polyethylene polymer coated onto the laminate coating layer of Plexar/tVUH/Plexar in contact with the juice ‘ rendering the laminate heat-sealable.

A sacond embodiment of the present invention revesls a nun-foil composite structure, providing a . substantial barrier to the loss of vitamin C and an almost complete barrier to the loss of esgential flavor pils; which comprises from the outer atmpsphere ex- posed surface to the inner surface cnntacting the essential pils and/or flavors (liquid juice); a thin layer of a low density polyethylene polymer, a paperboard substrate, a tie layer of Plexar or ethylene acrylic acid, an mterior layer of an ethylene vinyl alcohol copolymer (EVOH) and a thin layer of a low density polyethylene polymer coated onto the interior layer of EVOH, in di- rect contact with the juice, rendering the laminate heat-sealable.

A third embodiment of the present invention re- veals a non-foil composite structure, providing 8 subg-

tantial barrier to the loss of vitamin C and an almost complete barrier to the loss of essential flavor oils; which comprises from the outer atmosphere exposed sur- face to the inner surface contacting the essential oils and/or Flavors (liquid juice); a thin layer of a low density polyethylene polymer; a paperboard subg- trate, an interior layer of an ethylene vinyl alcohol copolymer (EVLH) ad a thin layer of a low density poly- ethylene polymer coated onto the interior layer of EVOH, in direct contact with the liguid, rendering the lamin- ate heat-sealable. ’ ’ The cartons constructed of the laminate of the present invention enable significant flavor oil re- tention of the citrus juice contained, and also sig- nificant prevention of loss of vitamin C, resulting in a substantial extension of the shelf life thereof and permits replacement of the costly aluminum foll bar- rier.

The preferred ethylene vinyl alcohol copolymer is sold under the product name EVAL EP resins and is avallable from EVAL Company of /merica. The preferred tie layer is a Plexar 177 and is available from USI

Corporation.

The present invention has produce a suitable container which has excellent barrier properties vtiliz- - fh - A

> ing a laminate which can ve heat-sealed with its ex- terior and interior layers being a non-polar consti- tuent (LDPE) fram front to back. The liquid juice components are insoluble in the pola r EVOH material, preventing flavor pil absorption and resulting suel- ling, stress cracking, plasticization and heat seal degradation as DCCUCS with a th ck LDPE as the con- tact layer.

The preferred laminates of the present inven- tion not only exhibit significant barrier properties to extend the shelf life of the juice, but the lami- nates can be produce-using conventional extrusion equipment. . ’ The preferred embodiments of the present inven tion are constructed as follows:

Stepwise, th=a paperboard is flame treated on both sides. Second, a layer of molten LDPE 1s then placed onto the paperboard substrate by extrusion coat- ing.

Yhirdly, the web is turned over and a sandwich layer of EVOH surroundeg by Plexar tie layers, or one

Plexar tie layer and EVOH, or EUUH alone is coextruded onto the uncoated exposed side of the paperboard stbe ghtratee. This newly placed layer is corona discharge treated or flame treated to Facilitate adhesion of a subsequent food contact layer.

Lastly, a layer of LOPE is extruded.mto the interior sandwich leyur of 1 lexar—EVUH-l Loxoo, oo [ lexar-.JUH layer op “ULM layer. The completed laminate can now be heat-sealed from front to back (LOPE to

LDPE) at conventicnal temperature (250°F. to 500°F.).

The newly formed laminate can then be scored, cut into blanks, folded and side-seam heat-sealed thera- on for transport.

Once transported, the prepared blanks can be filled onto conventional equipment, such as a PurePak (R) * machine made by Ex-Cell-0. The blanks are formed heat sealed at the bottom,filled andheat-sealed at the top by the PurePak(®) machine to complete the filled car- ton.

The barrier laminates produced by the present invention not only exhibit excellent barrier properties and can be easily constructed but also meet FDA approval for use in food packaging. EVAL Company of America's

EVAL EP is FDA apmroved for direct fond contact and the preferred ethylene vinyl alcohol copolymer of the invention. Other EVOH's which heat seal at low tem perature (250%. to 5000F.) anc which can be cut on conventional machinery could also be used as the bar- rier material.

BAD ORIGINAL

Thus, until the advent of the present inven=- tion, few suitable containers for the containment of citrus juices have heen developed which retain the ad- vantages of usiny paperboard as the bose material as well as have a relatively inexpensive barrier layer (EVOH) which can he fabricated using conventional exe trusion coating pruipmant.

The present invention described herein is parti- cularly useful as a paperboard laminate employed in the manufacture of citrus juice or other liquid product containers. Such containers make use of heat-seals . for seaming and closing, for examuple, cartons, folding sguare Or rectangular cantainers Qr boxes, and/or even fabricating cylindrical tubes.

The packaging material is printed, converted in= tp flat blanks side seamcd, and then formed, filled, and sealed using panventinnal carton filling machines.

Specifically, tho preferred srbodiment of the neu packe- aging material, as used to rroduce ll-ounce, quert, : 20 half-gallon ant {1 rep-quart Furefak ® cartons, COM- prises an exterior coating of 12 lbs LDPE, mperboards of varying thickeness (depending on carton size), a coextruded sanduich layer af /%.571bs of an adhesive tie material (Plexar 177), 4.0 lbs EVOH (EVAL), 4.5 lbs. no. a tie layer material (Plexar 177), and a product contact coating layer of 10 lbs LDPE.

The second embodiment of the present invention comprises an exterior coating of 0.8 mil LDOFE, papers boards of varying thickness (depending on carton sized, 0.5 to 0.8 mil adhesive tie layer, ho tn 0.7 nil

EVOH, and 0.7 mil LOPE (product-contact) .

The tuird esbardiment of the present invention comprises an exterior coating of 0.8 mil LDPE, paper- boards of varying thickness (depending on carton size), 0.2 to 0.7 mil EVOH, and 0.7 mil LDPE (product-contact).

Prior cartons containing aluminum foil are often ’ expensive relative to the performance problems they present when hreing form=fill-sealed hy the juice pack- ager. Also, the usual thick (22 1b) or (1.5 mil)

LOPE product-contact layer generally required in such cartons ahsorbs citrus flavor/aroma nils, with subse- quent deleterious effects on product quality.

The present invention makes use of a relatively inexpensive layer of EVOH, reducing loss of essential pils and vitamin G, while functioning as an excellent barrier. Frovided is a Very thin (0.7 mil) product- contact layer of LDPE thereby reducing juice absorp= tian in the product-contact laynr and resultant de- gradation of the contact layeTe

BRIEF DESGRIPTILK UF THE DRAJINGG

FIG. 1 is a cross-sectional elevation of an existing cnmrercial structure of a laminate;

FIG. 2 is a cross-sectional elevation of an existing commercial structure of a laminate;

FIG. 3 is a cross-sectional elevation of an existing commercial structure of a laminate;

FIG. & is a cross~sectinnal elevation of an existing commercial structure of a laminate;

F1G. 5 is a cross-sectional elevation of the preferred embodiment of the laminate of the present in- . vention;

FIG. 6 is a cross-sectional elevation of an al- ternate embodiment of the laminate of the present ine vention;

FIG. 7 is a cross-sectional elevation of an al- ternate embodiment of the laminate of the present in- vention;

FIG. & is a blpck diagram representing the process ofor making the preferred embodiment of the laminate of the present invention;

FIG. 9 is a block diagram representing the pro- cess for making the alternate embodiment of the lami nate of the present invention; and

FIG. 10 is a block diagram representing the process for making the alternate zrbodiment of the laminate of the present invention.

DETAILED DUSGRLUTICH UF THE IWVENTION

The existing commercial structure for a paper- hoard carton for juice and similar products hos made use of an easily hzat-sealed terrier laminate composed of paperboard 4 (F1G. 1) sandwiched between two thick layers of low desntiy polyethylene (LDPE) 2.6 (1.5 mil). The LDPE is an inexpensive heat-sealable mate- rial which acts to a limited extent as a moisture bar- ’ rier to prevent loss of essential oils (flavor) and aroma. The problem encountered with the conventional laminate structure has been that the essential oils of the juice (namely~-d-Limonene) have, after short periods of time, heen absorbed into the thick 1.5 mil

LDPE layer causing heat seal decay, stress cracking, and swelling while stripping the juice of the essential oils. Additinnally, the conventional structure (FIG. 1) proviuen vicb nlly no barvics rasicl ooo to oxygen which cotices the uice to lose vitinin © in great quantities afler a relatively short period of time. To illustrate, the conventional paperboard 1/2 gallon juice carton will lose 60.5% of its essential oil (d=

Limonene) and B45 of its vitamin C content in a stor- age period of six weeks (SLE TAULE 1). AL opp OREN

One conventional existing paperboard carton (FIG. 2) utilizes two extra layers in addition to the layers disclosed in FIG. 1 to add greater bar- rier resistance to the passage of oxygen and rem

BEultant loss of vitamin C. Expensive aluminum foil 14 has been added to the laminate structure to in- crease the barrier's resistance in the flow of oxygen.

An Additional thick layer of LDPE 16 is needed to allow the laminate to the heat-sealed from front to back with the exterior LDPE 8 layer. The structure of the barrier laminate (FIG. 2) has poor barrier . properties relating to the absorption of essential oils and aromas, since the heat--sealable contacting layer is a thick layer of low density polycthylene,

The shelf storage life of the juice carton made up of the barrier laminate of FIG, 2 still exhibits a percentage loss of essential o0ils~(d~l.imonene) of © 35.5%, while grently improving its barrier properties with respect to the percentage loss of vitamin C, 24% (See Table 1), The addition of the foil layer allows the laminate to exhibit excellent 0, barrier properties. Although the use of a foil layer is ex- tremely beneficial; the enormous increased expense : makes the use of foil economically less desirable.

FIGS. 3 nud tt disclose structures of barrier laminates described in U.$. Pat. Noo 4,513,036. FIG. 3 discloses a barrier laminate comprising a sande wich of LDPE }R8-paperboard 20-High Density Poly=- ethylene (HDPE) 22-LDPE 24, The laminate disclosed exhibits large losses of essential oils during its shelf life of six weeks, namely 60.5%, while also exhibiting large losses of vitamin C during the Bix week period, namely 87% (see Table 1). The economics and ease of fabrication of the laminates of FIG. 3 are outweighed by the poor barrier properties exhibited,

FIG. " discloses the preferred embodiment of ’ U.S. Pat. No. 1,513,026, namely a barrier laminate comprising LDPE 26~Paperboard 28-Polypropylene 30m

LDPE 32. The additional polyprovylene layer 30 adds to the barrier properties at relatively low additional costs. The barrier properties still are extremely dew ficient in resistance to the passage of oxygen and loss of vitamin C., namely 71% after nix weeks. The polypropylene lominate structure loses 39.5% of its ’ essential oils (d-Limonene) after six weeks (see

Table 1).

Both embodiments disclosed in the patent cited above do not adequately preserve the flavor aroma and vitamin C content of the juice. The structure of the existing commercial constructions have all faced the - 1h ~ same problem due to the necessity for heat sealing the seams and closures while forming the carton blank and while filling the cartons with juice or the like. The necesrity of forming a heat seal from the front to the back of the laminate has resulted in the use of a thick exterior layer» of LDPE and a thick : interior layer of LDPE, both non-polar compounds which exhibit excellent heat-sealing characteristics to one another (see (FIGS. l=lt).

Referring to FIG. 5, the preferred embodiment of the laminate of the precent invention is shown as . comprising a paperboard substrate 36 of varying thick~ ness which is most suitably high--grade paperboard stock, for example, 282 1b Milk Garton Board, to which is applied on one side a coating of low density poly~ ethylene (LDPE) 34, in a coating weight ranging from about 9 to about 15 pounds per ream. Any commercial extrusion coating grade LDPE is suitable for use here in. On the back or interior portion of the laminate, namely onto the paperboard layer 36, is coextruded a sandwich bh of a 4.5 1b. tie material (Plexar 177) 38 ho 1b. EVOH (EVAL) 40/4.5 1b tie material (Plexar 177) 42. The EVOH being a barrier layer composed of © EVAL Company of America's RVAL EP resins. Extruded thereon is a coating of 10 1bs. LDPE 46.

Referring to FIG. 6, the alternate embodiment of the laminate of the present jnvention is shown as comprising a paperboard suhmtrate 5h of varying thick= ness which is suitably high grade paperboard stock, i.e. 282 1b, milk carton hoard, to which is applied on one side a very thin 0.” mil coating of low density polyethylene (1,DPE) 52, in a coating weight range averag- ing 12 lbs. per 3000 square feet. Any commercial ex= } trusion coating grade LDPE ig suitable for use herein.

On the back or interior portion of the laminate, names onto the paperboard layer 5h, a (Plexar 1727) tie layer © 56 and a layer of 0.2 to 0,7 mil of £VOH 56 are applied by coextrusiong The EVOH heing a barrier layer com= posed of EVAL Company of america's EVAL EP resins.

Extrusion coated thercon js a very thin 0,7 mil layer 58 of a non-polar LDPE.

Referring to FlG. 7, a third embodiment of the laminate of the present invention is shown a8 comprie- ing a paperboard substrate 66 of varying thickness which is suitably high grade paperboard stock, i.e. 282 1b milk carton bvonrd, to which is applied on one side a very thin 0,8 mil coating of 1.0P1 6h, a 0.2 to 0.7 mil layer of myo 68 is applied by extrusion coatinge

Extrusion counted thercon js a thin layer 70 of a non-~ polar LDPE. a 16 =

Referring now to FIG. 8, wherein a block diagram discloses the method of forming the heat- sealable barrier laminate of FlG. 5S.

The laminate can be easily fabricated. In

Step A, the paperboard is [lame trented two sides.

Step B, a molten layer of the LDPE 34 is extrusion coated onto the paperboard substrate 36. Step Cy the LDPE layer 3h is corona discharge or flame heated in preparation for subsequent printing. Step Dy the web is turned over to facilitate Step Ey which has a sandwich layer Uli of Plexar 38/KVAL. 40/Plexar U2 ' coextruded onto the paperboard substrate 36. In Step

F, extrusion coating of a layer of LDPE 46 onto the : sandwich layer !ih completes the laminate.

Referring now to FIG. 9, wherein a block dia~ gram discloses the method of forming the heat sealahle parrier laminate of F1G. bo

In Step i, the paperboard is flame treated on two sides, Step By a molten layer of LDPE 52 is exw trusion coated onto the paperboard substrate 5h, Step

Cc, the LDPE layer 52 is corona discharge or flame treated to provide subsequent inner layer adhesion.

Step Dy the web is turned over to facilitate Step E, which has a layer of molten tie layer 56 and EVOH 56 coextruded onto the paperboard substrate Sho Step Fy the tie/F~VCH layer 60 has its surface coronn dis=- charge treated or flame treated to facilitate the adhesion of a subsequent interior product-contact thin LDPE coating 62 to complete the laminateo .

Referring now to FIG. 10, wherein a block diagram discloses the method of forming the heat- sealable barrier laminate of FIG. 7.

In Step i, the paperboard 66 is flame treated on two sides. Step B, a molten layer of LDPE 64 is extrusion coated onto the paperboard substrate 664

Step C, the LDPE layer 6h is corona discharge or , flame treated to provide subsaquent inner layer ade hesion. Step D, the web is turned over to facilitate

Step E, which hns a layer of molten EVOH 68 extrusion coated onto the paperboard suhstrate 66. Step Fy EVOH layer 68 is corona discharge trented or flame treated to facilitate the adhesion of a subsequent interior product-contact thin LDPE coating to complete the laminate.

Although specif coating techniques have been described, any osppropriate technique for applying the layers onto the paperboard substrate can be suite ably employed, such as extrusion, coextrusion, or adhesive lamination or single and/or multilayer films to paperboard to achieve the stated inventions of this patent.

The unique harrier effect provided by the laminate of the present invention to the % loss of essential oils nnd to the % loss of vitamin C is clearly demonstrated by the following example outlined in Table 1l.

Standard 1/2 gallen juice containers were pre- pared and filled with juices. A typieal essential oil in the juice was d-Limonene., The filled cartons were stored for a test period of six weeks after which the juice was analyzed to determine the percentage loss . by weight of the essential oil d-Limonene and the per=- centage loss by weight of vitamin Co

All weights in lbs are given in lbs per 3000 square feet.

TABLIL 1

Test Sample % Loss 1/2 Gallon Juice of

Container Essential % Loss of 0il Vitamin C

Ce ———————————————————————

LDPE/BOARD/LPTE (¥1aG. 1) 0.5 84

LDPE/BOARD/1LNFPE/FOIL/ 35,5 2h

LDPE (FIG. 2)

LDPE/BOARD/HDPR/1L.DER 60.5 87 (FIG. 3)

LDPE/BOARD/POLY PROPYLENE/ 39.5 71

LDPE (FIG. 4)

LDPE/BOARD/PLiEAN 1~EVOH~ 16.5 INS

PLEXAR/LDPE (FIG. 5) ————————————

It cau he clearly seen that the container pre- pared from » laminate of the present invention pro- vides an almost complete barrier to the loss of essential oils far greater than has been present in existing structures. Additionally, the oxygen passe age or nercentnge loss of vitamin C hns been greatly reduced over all prior laminates not containing alu= minum foil,

The affectiveness of the laminate of the pre- sent invention as a barrier Lo migration of essential . oils and flavors, as well as «= harrier to a loss of vitamin C permits a significant extension of shelf life of containers constructed therefrome :

BAD ORIGINAL v

Claims (1)

1. WHAT IS CLAIMED IS:

   1. A process for improving the resistance of paperboard to the migration of esrential oils and/or flavorings, said process comprising the steps of: (a) flame treating a paperboard substrate on two sides; (b) extrusion coating a 12 1b. outer layer of » low density polyethylene polymer onto said outer surface of said paperboard} (¢) corona discharge treating said outer layer ‘ of low density polyethylene polymers; (d) flipping the coated paperboard web over; (2) coextruding an inner sandwich comprising a h.5 1b. tie layery a 4.0 1b, ethylene vinyl alcohol copolymers layer and a Ba5 1b tid layer onto said uncoated surface of said paperboard; and (f) extruding o 10 1b heat-sealable low density polyethylene polymer layer onto said sure face of said inner wandwich of tie layere ethylene vinyl Aleohol copolymer layer= tin layer.

   2. 0 process for improving the resistance of paperboard to the migration of essential oils and/or er 21 = flavorings, oaid process comprising the steps of: (a) flame treating a paperboard substrate on two sides; (b) extrusion coating » 12 1b outer layer of a low density polyrthylene polymer onto said onter surface of said paperboard; (¢) flame treating snid outer layer of low density polyethylene polymers; (d) flipping the conted paperboard substrate cvers; (e) coextrusion of an inner sandwich corpris~ ' ing a 4.5 1b. tie layer, a 4.0 1bs ethylene vinyl alcohol copolymer layer and a lo5 1b tie layer onto raid inner surface of said paperboard; and }

   (1) extruding a 10 1b heat-sealable low dene sity polyethylene polymer layer onto said aur face of said inner sandwich of tie layer-

   ethylene vinyl alcohol copolymer layer=-tie layers

   3, A process for improving the resistance of paperboard to the migration of essential oils and/or flavorings, said process comprising the steps of: (a) flame treating = paperboard substrate on a © 25 two sideeas ve DD es

   (b) extrusion coating a thin 0,8 mil thick couter layer of a low density polyethylene polymer onto said outer surface of said paperboard; (c) corona discharge treating said outer layer of low density polyethylene polymer; (d) flipping the coated paperboard substrate over; (e) coextruding a tie layer and a 0.2 to 007 mil thick inner layer of ethylene vinyl alcohol copolymer onto said uncoated inner ’ surface of said paperboard; (f) corona discharge treating said inner layer of the material-ethylene vinyl alcohol co- polymer; and : (g) extrusion coating a thin 0.7 mil thick layer of a hent-sealable low density polyethylene polymer onto said surface of said inner layer of tie midterial-cthylene vinyl alcohol co= polymer layers Lh, A process for improving the resistance of pnperboard to the migration of essential oils and/or flavorings, said process comprising the steps of: (a) flame treating a paperboard substrate on 2S two sides;

   (b) extrusion coating n thin 0,8 mil thick layer of a low density polyethylene polymer onto naid outer surface of said paprrhoard; (¢) flame treating said outer layer of low density polyethylene polymer; (d) flipping the coated paperboard substrate bver; (e) coextruding a tie layer and a 0.2 to 0.7 mil thiek inner layer of an ethylene vinyl alcohol copolymer onto said uncoated inner ’ surface of said paperboard. (£f) flame treating srid inner layer of ethylene vinyl alcohol copolymer; and (g) extrusion coating a 0.7 mil thick layer of a heat-sealable low density polyethylene polymer onto said surface of said inner layer of tie material~ethylene vinyl alco= hol copolymer layer, i

   5. A process for improving the resistance of paperboard to the migration of essential oils and/or flavorings, said process comprising the steps of: (a) flame treating a paperboard substrate on two sides - 2h

   (h) evtruasicn conting a thin 0,8 mil thick outer layer of a low density polyethylenn polymer outo said outer surface of said paperboard; (¢) corcna discharge treating said outer layer of low density polyethylene rolymer; (d) flipping the goated peperboard substrate over; } (e) extrusion coating a 0.2 to 0.7 mil thick inner layer of ethylene vinyl alcohol cow polymer onto gaid uncoated inner gurface of ’ said paperboard; (f) corcna discharge treating snid inner layer of ethylene vinyl alcohol copolymers; ond (g) extrusion coating » thin 0,7 mil thick lnyer of a heat—scplable low density poly- ethylene polymer onto said surface of sald inner layer of ethylene vinyl alcohol co- polymere 6, Ah process for improving the resistance of paperboard to the migration of essential oils and/or flavorings, coid process comprising the steps of: (a) flame treating a paperboard substrate on two sides;

   (b) extrusion coating 2 thin 0.8 mil thick outer layer of a lou density polyethylene polymer onto said nuter surface of said paperboard; (c) flame treating said outer layer of low density polyethylere polymers; (d) flipping the conted yaperhoard substrate TI pay overs (e) extrusion coating 2 0.2? to 0,7 mil thick inner layer of ethylene vinyl alcohol co- polymer onto said unconted inner surface * of said poperboard; (f) flame treating said inner layer of cthylene ; L y vinyl alcohol copelymer; and (gz) extrusion coating © thin 0.7 mil thick layer nl a heat-sealable low density polyethylene polymer onto anid surface of said inner layer of ethylene vinyl alcohol copolymera CHARLES ®. GIBBONS CYNTHIA I,. TANNER ALLAN A.

   WHILLOCK : Inventors ; r BAD ORIGINAL