AU474635B2

AU474635B2 - Improved package and method of making same

Info

Publication number: AU474635B2
Application number: AU34242/71A
Authority: AU
Inventors: PAUL EDWARD GRINDROD MAURICE JENNINGS GIFFORD and. GLENN MINOR AUSTIN OSCAR EUGENE WERFERTH
Original assignee: Oscar Mayer Foods Corp
Current assignee: Oscar Mayer Foods Corp
Priority date: 1971-10-06
Filing date: 1971-10-06
Publication date: 1973-04-12
Also published as: AU3424271A

Description

34.242/1L The resent invention generally relates to in)r-vco :aci:aI,'es and nethods of making the same which pac R:R are characterized by hernetic seals that can Ce riia'liy separated ::hen access to the product is desired. More particularly, this invention is concerned with a new and improved package having either

a hermetic breakaway or peelable seal formed between an ethylene-polar monomer copolymer film or coating and a

thermoplastic film. Desirably, controlled amounts of heat, belwc' the melt temperatures of the film materials constituting the package, can be applied to the seal area at the time of seal formation to improve the

tenacity of the seal so formed without destroying its

breakaway property or peelability. In a preferred embodiment of the present invention, the hermetic break- away or peelable seal is formed between an ethylene-

vinyl acetate copolymer (hereinafter referred to as EVA)

film or coating and a polyvinylidene chloride film which

is contacted with the EVA coating or film while the

polyvirylidene chloride film is in an amorphous super- cooled state.

As used herein, the term "Pclyvinylidene Chloride

Pilm" is used to designate thernoplastic films composed

of copolymers of vinylidene chloride and vinyl chloride

having a vinylidene chloride content of from 60 to

percent by vei[ht and a corresponding vinyl chloride

content of from 40 to 5 percent by weight.

4 7 4.6

34,242 n' As used in the specification, the term "breakaway

seal" is used to define a seal wherein, at the time the

seal is broken, either of the film materials which make

up the seal separate either partially or entirely from

the substrates to which they were respectively applied.

The term '"peelable seal" is used to denote a seal where--

in both of the film materials which make up the seal,

on seal separation, remain intact on the substrates to

which they were respectively applied.

In accordance with the present invention there is provided a package comprising a product enclosed

between first and second layers of packaging material,

said first layer of packaging material having a seal-

forming surface formed of a copolymer of ethylene and a

polar monomer film material, said seal-forming surface

of said first layer of packaging material being adhered)

to said second layer of packaging materialto define a hermetic seal, said ethylene-polar monomer copolymer film material having a polar monomer content which

enables said hermetic seal to be separated when access

to said product is desired. The polar monomer content preferably ranges from IfO to 402 .by weight. While ethylene-vinyl acetate copolymer is a preferred film

material for the practice of the present invention,

other ethylene-polar monomer copolymer film materials

such as, for example ethylene-isobutyl acrylate copol-

ymer and ethylene-ethyl acrylate copolymer can also be

adhered to a thermoplastic film to provide the

474.635

34,2 4 2 1.

advantageous breakaway and peelable seals of the

present invention.

Oxygen barrier films can be advantageously combined with the ethylene-polar monomer copolymer films

of the present invention for packaging food and other

perishable products. In this regard, the oxygen barrier films ar' transparent films which have an

oxygen transmission rate of from 0 to 10 cubic cm., per

100 square inches, per 24 hours, per mil thickness, at 770F. and 760 mm. Hg.

A preferable aspect of the present invention

involves the discovery that the tenacity of a seal

formed between an ethylene-polar monomer copolymer film

or coating and a thermoplastic film can be substantially

improved by

474.635

34,2 4 2'T heating the seal interface, at the time of seal formation, to

a temperature which advantageously promotes increased seal

tenacity without adversely affecting the ease with which such

seals can be broken when access is desired. Typical temper-

atures which can be used to obtain the advantageous improved

hermetic seals with these films generally run from approxi-

mately 806F. to 2006F. The'use of such a heating step is

readily distinguishable from conventional heat seal techniques

in that with conventional heat seal techniques it is necessary

to heat at least one of the materials at the seal interface

to a temperature above its melting point in order to induce

fusing thereof to the other material making-up the heat seal.'

In accordance with the low temperature sealing techniques of

the present invention, the maxi1mum temperatures employed are

below the melt temperatures of the film materials which make

up the package and form the seal. It has been found that as

the polar monomer content-of the ethylene-polar. monomer

copolymer coating or film is lowered, a corresponding in-

crease in temperature-is required in order to produce a seal

of equ ivalent tenacity.

The improved packages of the present invention

exhibit significant advantages in that they are generally

characterized by a seal which closely conforms to the shape

of the packaged product. This product-conforming seal has

a number of significant advantages. For example, the

uns ightly appearances produced by the free. movement of water

474,635

34,2 4 2 m and product juices loosely contained in many conventional

packages is avoided. In addition, the present invention also

provides a package with a permanently positioned product

without any loose film thereby substantially minimizing dam-

age to the package during shipment which can result in con-

tamination of the product. Furthermore, these packages pro-

vide a maximum seal area for a given product particularly

where such product is of irregular shape thereby providing

the maximum seal area afforded by a package of a given size

and likewise minimizing the amount of residual oxygen pre-

sent in such package. For these reasons, and others, the

improved packages of the present invention are particularly

suitable for the packaging of food products such as wieners,

bacon, sliced luncheon meats, chops, cheese and the like.

It is, therefore, an important object of the present

invention to provide an improved package characterized by an

improved hermetic peelable or breakaway seal which can be

readily and easily separated when access to the contents of

said package is desired.

An object of the present invention is to provide an

improved package which is particularly suitable for packaging

of food products which package includes an improved hermetic

peelable or breakaway seal formed without the use of a plasti-

cizer or pressure-sensitive adhesive.

Another object of the present invention is to pro-

vide a new and improved package having an improved peelable e 474.635

3 4,24 2 nI

or breakaway seal formed between an ethylene-polar monomer

copolymer film or coating and a thermoplastic film.

Other and further objects of the present invention

will be apparent from the following detailed description

thereof taken in conjunction with the accompanying drawings

wherein:

Figure 1 is a diagrammatic illustration of a pro-

cedure which can be followed in making a laminated film

474.635

34,24 2 package embodying principles of the present invention;

Figure 2 is a perspective view of a package made in

accordance with the present invention;

Figure 3 is a fragmentary enlarged sectional view of

a portion of the seal area of the package shown in Figure 2;

Figure-4 is a fragmentary enlarged sectional view

of the portion of.the seal area, similar to that shown in

Figure 3, but of a modified package from that shown in Figure

2;

Figure 5 is a schemmatic plan view of a wiener

package embodying principles of the present invention;

Figure 6 is a side elevational view of the package

shown in Figure

Figure 7 is an enlarged fragmentary sectional view

of the package shown in Figure 5 taken along the line 7-7

therein;

Figure 8 is an enlarged fragmentary sectional view

of the package, shown in Figure 5 taken along the line 8-8

therein;

Figure 9 is a diagrammatic illustration of a pro-

cedure which can be followed in making a package embodying

principles of the present invention which procedure includes

one form of low .temperature heating to enhance the seal

formation in accordance with the present invention;

Figure 10 is a diagrammatic illustration of another

procedure which can be followed in making a film package 8 1 474,635

34,242 n, embodying the present invention which procedure includes a

modified heating step for producing improved seals;

Figure 11 is a schematic plan view of a modified

wiener type package embodying principles of the present

invention;

Figure 12 is a side elevational view of the package

shown in Figure 11;

Figure 13 is an enlarged fragmentary sectional view

of the package shown in Figure 11 taken along the line 13-13

therein;

Figure 14 is a schematic plan view of one form of

bacon package embodying principles of the present invention;

Figure 15 is a fragmentary enlarged sectional view

of the package shown in Figure 14 taken along the line 15-15

therein;

Figure 16 is a schematic plan view of a modified

form of bacon package embodying principles of the present

invention;

Figure 17 is an enlarged fragmentary sectional view

of the package shown in Figure 16 taken along the line 17-17

therein;

Figure 18 is a schematic plan view of a further

modified form of bacon package embodying principles of the

present invention; and

Figure 19 is an enlarged fragmentary sectional view

of the package shown in Figure 18 taken along the line 19-19

therein. q 474.635

34. 2 4 2 In the detailed description of certain preferred

embodiments of the present invention set out below, it will

be noted that these packages generally include one or more

laminae of a polyvinylidene chloride film. These polyvinyli-

dene chloride films are not essential to the present invention

in that suitable peelable or breakaway seals can be formed

between ethylene-polar monomer copolymer films or coatings

and other thermoplastic materials. There are, however,

certain unique properties -of polyvinylidene chloride films

which, by reason of their own individual characteristics and

cooperative characteristics exhibited with ethylene-polar

monomer copolymer films and coatings, make these films

particularly suitable for use in the improved packages of the

present invention.

Polyvinylidene chloride films, for example, exhibit

a so-called "supercooled" or amorphous state that can be

advantageously utilized to enable film laminations which

include the same to be readily formed about a product to

be packaged. The properties and the method of inducing this

amorphous condition are fully described in co-owned United

States Letters Patents 3,083,106, 3,189,505 and 3,131,069,

among others. In general, these unique properties can be

induced, following extrusion, by immediately cooling the

films such as by passing them through a water bath maintained

0 at a temperature of from approximately 35 F. to 100 0 F. This

amorphous condition can then be maintained until the combin-

474.635

34, 242/7"- ation of time and temperature causes crystallization.

While in this supercooled state, the polyvinylidene

chloride film can be drawn about a product to be packaged to form a surface conforming package which is not characterized by folds or pleats that can establish potential leakage areas. Controlled stretching or forming of the film while in a supercooled state can be practiced without accompanying crystallization of the film to an extent that the supercooled properties are retained in order to make full utilization of these unique properties.

An important discovery which has been employed in the making of a preferred embodiment of the present invention involves the finding that while in an amorphous condition and without substantial crystallization occurring, a flexible polyvinylidene chloride film will form a particularly effective hermetic peelable or breakaway seal with an ethylene-polar monomer copolymer film or coating having a polar monomer content of from approximately 10% to 40% by weight by merely placing these films in adherent contact with each other. This hermetic seal, however, can be further improved by the application of the low temperature heating techniques pre- viously referred to which will be described in greater detail hereinafter.

The ethylene-polar monomer copolymer films and coatings included within the present invention are those copolymers of ethylene and a polar monomer wherein -the polar 11 474.63-5

3 4,2 4 2 ni monomer content ranges from approximately 10% to 40% by weight. In this regard, the termi polar monomer is used herein to denote those chemical substituents or groups which, when copolymerized with theylene, provide a resultant copolymer that exhibits polar characteristics to a degree such that the copolymer is susceptible to adhesion with other thermoplastic films. The preferred copolymer film material of the present invention is ethylene-vinyl acetate. Other suitable copolymners of ethylene

and polar monomers, however, may be advantageously used to provide the breakaway or peelable seals with thermoplastic films of the present invention. By way of examnple only, these other copolymers include the copolymer of ethylene and isobutyl acrylate and the copolymer of ethylene and ethyl acrylate as well as copolymers of ethylene and polar monomers which exhibit properties and characteristics similar to these specific film materials. For purposes of illustration, the following embodiments of the present invention will be described with reference to the preferred copolymer film material, namely, EVA. it is to be understood, however,

that the present invention is not limited to EVA copolymers but rather encompasses the equivalent ethylene-polar monomer copolymer films mentioned above.

Referring to the drawings, and with particular reference to Figure 1, the numeral 21 generally designates

a continuous film and packaging forming apparatus which can

be employed in the manufacture of packages embodying principles

12 474,635

34,242171, of the present invention. As is shown, apparatus 21 generally

includes a film forming component 22, supercooling bath 23,

package forming component 24, heater 25 and combination

labeling and trimming unit 26. For purposes of illustration,

apparatus 21 will generally be described in connection with

the forming of packages made from two three-ply film lamina-

tions, where each of such laminations includes at least one

lamina of a polyvinylidene chloride film.

As is shown, film forming component 22 includes a

plurality of film extruders, diagraxmtically illustrated

and respectively designated by the reference numerals 27-32.

Film extruders 27-32 extrude films 33-38, respectively, each

of which exhibits properties and characteristics which are

specifically adapted to meet the requirements of the package

to be ultimately formed. For example. in the packaging of

food products which are subject to deterioration by contact

with oxygen, film extruders 27 and 32 could be supplied

with a suitable oxygen barrier film forming resin, such as,

for example, a polyvinylidene chloride film having a compo-

sition of approximately 85% vinylidene chloride and

vinyl chloride or 90% vinylidene chloride and 10% vinyl

chloride. As is shown, films 33, 34 and 35 form the bottom

film lamination 39. In accordance with the present inven-

tion, inner lamina 35 will preferably be formed of a flexible

polyvinylidene chloride film generally having a lower vinyli-

dene chloride content, such as, for example, a film formed

13 474.,635

34,24 2m. from a resin having a 68% vinylidene chloride and 32% vinyl

chloridecontent. Bonding of the flexible polyvinylidene

chloride inner lamina 35 to the outer lamina 33 is accom-

plished through the use of intermediate lamina 34 composed

of an EVA film having a vinyl acetate content of at least

by weight. By employing such an intermediate film

lamina 34 between the two polyvinylidene chloride laminae

33 and 35, improved strength and flexibility are provided

to the film lamination 39 resulting in such film lamination

exhibiting substantially increased impact strength as well

as improved low temperature properties. Other suitable film

materials for the intermediate lamina 34 include chlorinated

polyethylene and compounded polyvinyl chloride and polyvinyl

chloride-vinyl acetate copolymers.

The upper film lamination 40 is a three-ply film

lamination having an inner lamina 36, intermediate lamina

37 and.outer lamina 38. As was previously noted, outer

lamina 38 can be formed of a suitable oxygen barrier film

such as, for example, a polyvinylidene chloride film having

a vinylidene chloride content of approximately 85% and a

vinyl chloride content of approximately 15%. In accordance

with a preferred embodiment of the present invention, inner

lamina 36 is composed of an EVA film having a vinyl acetate

content of from approximately 10% to 40% by weight. EVA

films having a vinyl acetate content of from 15% to

by weight are particularly suitable for forming the improved

14, 474,635

34,2 4 2 breakaway and peelable seals with a polyvinylidene chloride

film having a 68% vinylidene chloride, 32% vinyl chloride

content such as inner film lamina 35. Intermediate lamina

37 can be composed of a suitable EVA film having a vinyl

acetate content of at least 30%. Such intermediate film

lamina imparts additional strength and flexibility to the

film lamination as well as providing opposed surfaces to

which the inner EVA film 36 and outer polyvinylidene chloride

film 38 bond.

Films 33-38, upon being extruded, are immediately

introduced into a controlled temperature water bath 41 in

the supercooling unit 23. Water bath 41 is preferably

maintained at a temperature of from approximately 350F. to

100 0F. When reduced to this temperature, the poMyvinylidene

chloride films exhibit the previously mentioned "supercooled"

or non-crystalline properties which are maintained until a

combination of time and temperature conditions produce

crystallization therein. While in this supercooled state,

the polyvinylidene chloride can be readily formed about a

product to produce a surface conforming package therefor.

In accordance with the present invention, the amorphous

polyvinylidene chloride film 35, when contacted with the

EVA film lamina 36, produces a hermetic peelable seal there-

with. The extrusion of the EVA or equivalent copolymer film

into the supercooling bath while not essential in order to

effect an amorphous or non-crystalline condition therein, is

474,635

3 4 ,2 4 2 n provided in order to enable the EVA or equivalent copolymer

film to be laminated with the supercooled polyvinylidene

chloride without thereby causing premature crystallization

of the supercooled polyvinylidene chloride film.

As is shown, films 33-35 immediately upon being

introduced into the supercooling bath 41 are formed into

the film lamination 39 by contacting such films between a

pair of combining rollers 42. Likewise, films 36-38 are

contacted between combining rollers 43 in forming the film

lamination 40. As such, upper film lamination 40 includes

an outer lamina 38 composed of an oxygen barrier film, an

intermediate lamina 37 composed of an EVA film having a vinyl

acetate content of from approximately 30% to 40% and an inner

lamina 36 composed of an EVA film having a vinyl acetate

content of from approximately 10% to 40% by weight. Similarly, bottom film lamination 39 includes an outer lamina 33 com-

posed of an oxygen barrier film, an intermediate lamina 34

composed of an EVA film having a vinyl acetate content of

from approximately 30% to 40% by weight, or other suitable

film, and an inner lamina 35 composed of a flexible poly-

vinylidene chloride film which forms a peelable seal with

the ethylene vinyl acetate lamina 36 of the upper film

lamination

In the illustrated embodiment, the film lamination

39 is directed around guide rollers 45 and 46 into the

package forming component 24. Similarly, the film lamination 16 474, 635

34,24 2 ni is directed around guide rollers 47 and 48 into the same

package forming component. Such package forming component

is constructed and operated in accordance with known

techniques for handling the polyvinylidene chloride films in

order to provide product conforming packages therewith. A

complete description of such apparatus is set forth in the

co-owned United States Letters Patents 3,083,106 and 3,129,545,

the disclosure of which are incorporated herein by reference

thereto.

Individual product-enclosing packages 49 emerge

from the package forming unit 24 in a chain joined by a

continuous web 50. These packages can then be heated by a

suitable heating element 25 to effect crystallization of the

polyvinylidene chloride film. By way of example, the tem-

perature of the polyvinylidene chloride laminae 33, 35 and

38 in the laminations 39 and 40 can be raised to approximately

150°F. for this purpose. If desired, however, such crystal-

lization can be obtained by permitting the packages to be.

stored at room temperature for a prolong period of time.

The packages upon being thus formed, are received

in the combination labeling and trimming unit 26 wherein

labels are applied thereto and they are separated from the

web 50 which is received upon a suitable collecting roll 51.

The separated packages 49a are then discharged from the unit

26 into a conveyor 52 in condition for further handling,

storage, or direct shipping, if desired. 17 o 474.635

34,242 171 Figures 2 and 3 generally illustrate a package

embodying principles of the present invention which is par-

ticularly suitable for packaging sliced luncheon meats and

similar products. As is shown, package 61 generally includes

an upper film lamination 62 drawn over a plurality of stacked

luncheon meat slices 63 in intimate surface conforming con-

figuration therewith. Upper film lamination 62 is bonded to

a lower film lamination 64 through a seal area 65. In accord-

ance with a preferred embodiment of the present invention,

upper film lamination 62 includes an inner lamina 66 which

is composed of an EVA film having a vinyl acetate content of

from approximately 10% to 40% by weight. Likewise, lower

film lamination 64 includes an inner lamina 67 bonded to said

inner lamina 66 of said upper film lamination 62 throughout

the peripheral seal area 65. Inner film lamina 67 is com-

posed of a suitable thermoplastic film or other material

which will cooperatively form a hermetic peelable seal with

the EVA lamina 66. Preferably, inner lamina 67 is composed

of a polyvinylidene chloride film which is contacted with

said EVA film 66 while said polyvinylidene chloride film

lamina 67 is in an amorphous or supercooled state. In this

manner, a peelable and hermetic seal is formed between these

films without the use of additional sealants or pressure-

sensitive adhesive. Likewise, the use of heat, electronic,

hypersonic, or equivalent sealing techniques can be eliminated

when such supercooled or amorphous polyvinylidene chloride

18 474,635

34,2 42', film is conjointly used with the EVA copolymer for forming

the unique hermetic and peelable seal of the present invention.

In this regard, however, it is important to note that the

application of a controlled amount of heat to the seal area

is preferred as will be more fully discussed in connection

with the package forming apparatus shown in Figures 9 and

As is best shown in Figure 3, the upper film lamni-

nation includes an outer film lamina 68 which is preferably

composed of a suitable oxygen barrier film such'as, for

example, a polyvinylidene chloride film having a vinylidene

chloride content of approximately 85% and vinyl chloride

content of approximately 15%. A suitable intermediate laminia

69 which effectively bonds the inner lamina 66 to the outer

lamina 68 can be composed of an EVA film having a vinyl

acetate content of from approximately 30% to 40% by weight

and, as such, is characterized by improved bonding ability

with inner and outer laminae 66 and 68. Intermediate lamina

69 also imparts improved flexibility and strength to the film

lamination 62. Bottom film lamination 64 is likewise pro-

vided with a suitable intermediate lamina 70 for bonding the

inner film lamina 67 to an outer oxygen barrier film lamina

71. in instances wherein the inner film lamina 67 is composed

of a flexible polyvinylidene chloride film and outer lamina

71 is formed of an oxygen barrier polyvinylidene chloride

film, intermediate lamina 70 can desirably be either an EVA

film comparable in composition to the intermediate film

19 474,635

34242 R1 lamnina 69 cr other suitable film such as chlorinated poly- ethylene, and compounded Polyvinyl chloride and Polyvinyl chloride-vinyl acetate copolymners. Equivalent film laminae which can be substituted in place of the specific intermedi- ate and outer l~aminae in the upper and lower film laminations 62 and 64 will be obvious to those skilled in this art. In the embodiment 81 shown in Figure 4, like refer- ence numerals have been used to designate laminae which are identical to those shown in the Figure 3 embodiment. Accord- ingly, the above description of upper film lamination 62 is incorporated herein by reference and applied to the package 81 of Figure 4. The lower film lamination 72 can have a lamina 73 formed of any suitable relatively rigid material such as, for example, rigid polyvinyl chloride or bleached kraft paperboard having a thickness in the order of from about 0.010 to 0.020 of an inch. The upper surface of the lamina 73 can have a lamina 74 composed of a suitable thermo- plastic film bonded thereto. Preferably, lamina 74 is formed of a polyvinylidene chloride film which is contacted with the inner EVA film lamina 66 of the upper film lamination 62 while in an amorphous or supercooled state so as to provide 'a hermetic peelable seal. While not illustrated, the bottom surface of the lamina 73 may be provided with a suitable water impermeab~le coating such as microcrystalline paraffin wax or the like.

Figures 5~-8 generally illustrate a package 91 formed

1474,6

34,24 2 nl. of a top lamination 92 and a bottom lamination 93 which

cooperatively enclose therebetween a plurality of wieners or

wiener-shaped products 94 in closely spaced side by side

relation to each other. The film laminations 92 and 93 are

combined peripherally about the product 94 to form a contin-

uous edge seal 95. As is illustrated, the film laminations

are also drawn inwardly about the products to conform to the

contour thereof and provide, the package 91 with a surface

conforming configuration without having folds or pleats

which folds or pleats could cause problem areas with respect

to possible leakage and contamination.

As is best shown in Figure 7, top film lamination

92 includes an outer oxygen barrier film 96, intermediate

lamina 97 and an inner lamina 98 which, in accordance with

a preferred embodiment of the present invention, is com-

posed of an EVA film having a vinyl acetate content of from

approximately 10% to 40% by weight. Typically, the outer

film lamina 96'could be composed of a polyvinylidene

chloride film having a vinylidene chloride content of

approximately 85% and a vinyl chloride content of approxi-

mately 15% by weight. Intermediate film lamina 97 is

preferably composed of a film which will effectively bond

with the outer lamina 96 and inner lamina 98. An EVA film

having a vinyl acetate content of at least 30% is particularly

suitable for.this purpose since suct film provides the

resultant film lamination with improved strength, flexibility

and desirable low temperature properties.

21 474.635

34,24 2 L Bottom film lamination 93 is likewise composed of an outer oxygen barrier film 99, an intermediate lamina 100 and inner lamina 101. In accordance with the present invention,

inner lamina 101 is composed of a thermoplastic film which will form a hermetic peelable or breakaway seal with the EVA film lamina 98. Preferably, inner film lamina 101 is composed

of a polyvinylidene chloride film which is contacted with said EVA film lamina 98 while in an amorphous supercooled state. If desired, however, suitable crystalline polyvinyli-

dene chloride films and other films may be used as the inner lamina 101 and a suitable hermetic peelable seal formed therewith by the use of heat seal techniques.

In order to facilitate ready separation of the

film laminations 92 and 93, inserts 102 and 103 are provided adjacent the package end 104. If desired, the inserts 102

and 103 can be formed of a suitable paper or equivalent

material which can be suitably imprinted as desired. In this manner, the breakaway or peelable seal of the package illustrated in these figures is easily openable, without

requiring a cutting implement.

In general, it has been observed that as the polar

monomer content of an ethylene-polar monomer copolymer film is increased, the over all tackiness of the film is likewise increased. Accordingly, where the film lamina 101 in the

lower film lamination 93 is composed of a less tacky thermo- plastic material, it is generally preferred that the ethylene-

22 r 474,6

34,2 42,011, polar monomer copolymer film lamina 98 have a correspondingly higher polar monomer content.

Figure 9 generally illustrates one form of continu- ous film extruding and package forming appdratus 124 which, in accordance with an important aspect of the present inven- tion, is equipped with means for applying controlled amounts of heat to the seal interface at the time of seal formation in order to provide the thus formed packages with a peelable or breakaway seal of improved tenacity. This apparatus generally includes a film forming component 125, supercooling bath 126, ethylene-polar monomer copolymer coating dispenser 127, package forming component 128, low temperature seal heating means 129a and 129b, and combination labeling and trimming unit 131. By way of illustration only, the combi- nation film extruding and package forming apparatus 124 will generally be described in connection with the forming of packages made from a three-ply film lamination and an EVA coated oxygen barrier film.

As is shown, film forming component 125 includes a plurality of extruders, diagrammatically illustrated and respectively designated by the reference numerals 132-135. Film extruder 132 is supplied with a suitable oxygen barrier film forming resin which preferably will form a transparent film 136 having an oxygen transmission rate of from 0 to cubic cm., per 100 square inches, per 24 hours, per mil thickness, at 770F. and 760 num. Hg., such as, for example,

23 474635

3 4,2 42 ni. a polyVinylidene chloride film having a composition of approximately 85% vinylidene chloride and 15% vinyl chloride. Likewise, film extruders 133, 134 and 135 are supplied with film forming resins which when extruded form films 137, 138 and 139, respectively. Bottom lamina or film 137 is composed

of a film material which forms a peelable or breakaway seal with an EVA coating or film which has a vinyl acetate content of from approximately 10% to 40% by weight. In accordance with a preferred embodiment of the present invention, bottom lamina 137 is a flexible polyvinylidene chloride film, for example, a polyvinylidene chloride film having a 68% vinyli-*

dene chloride and 32% vinyl chloride content. outer lamina 139 is a suitable oxygen barrier film, for example, a poly- vinylidene chloride film having a composition of approximately

vinylidene chloride and 15% vinyl chloride and inter-

mediate lamina 138 is composed of a film which will effectively

bond with laminae 137 and 138 and also provide the thus

formed film lamination 140 with improved strength and flex- ibility. For example, intermediate film lamina 138 could

be composed of an EVA film having a vinyl acetate content

of at least 30% by weight. in this connection, it should

be noted that films 136-139 can be composed of different

thermoplastic materials and that the specific compositions

herein designated are given for illustrative purposes only. Films 136-139 upon being extruded, are immediately

introduced into a controlled temperature water bath 141 in

24 474,635

34.2 4 2 ni supercooling unit 126. Water bath 141 is preferably maintained

at a temperature of from approximately 359F. to 100 0 F. When

reduced to this temperature, the polyvinylidene chloride

laminae 136, 137 and 139 exhibit the previously mentioned

"supercooled" or non-crystalline properties. As is shown,

films 137-139 upon being introduced into the water bath 141

are combined into the film lamination 140 by contacting such

films between a pair of combining rollers 142. Film lamina-

tion 140 is then di4rected around guide rollers 143 and 144

into the package forming component 128. As is apparent from

the drawing, film lamination 140 includes an outer lamina

which is composed of the oxygen barrier film 139, a~ suitable

intermediate lamina 138 and a bottom lamina 137 which when

contacted with an EVA film or coating having a vinyl acetate

content of from approximately 10% to 40% by weight will form

a peelable or breakaway seal therewith.

The oxygen barrier film 136 is likewise directed

around guide rollers 145, 146 and 147 to a location located

just adjacent to package forming component 128 at which an

ethylene-polar monomer copolymer coating 148 from dispenser

127 is deposited thereon to form a coated film 149. For

purposes of illustration, this embodiment of the present

invention will be described with reference to an EVA coating

148. The EVA coating 148 is applied at a location in advance

of package forming unit 128 so that it will be substantially

dried on the film 136 prior to package forming. If-necessary, 474.635

3 4,2 4 2 171 suitable drying means (not shown) can be used to facilitate

drying of the coated film 149. This coating can vary in

thickness, however, it will generally be in the order of 0.1

to 0.2 of a mil in thickness and has a vinyl acetate content

of from 10% to 40% by weight. As is shown, the EVA coating

is applied to the upper surface of the oxygen barrier film

136 so that it will be in position to be contacted with the

bottom surface of film lamination 140 in order to provide

therewith a peelable or breakaway seal.

Products to be packaged are introduced into the

package forming component 128 between film lamination 140

and coated film 139 as is diagrammatically illustrated in

Figure 9. The package forming component 128 is constructed

and operated in accordance with known techniques for handling

the specific films employed. For example, where polyvinyli-

dene chloride films are used, the film forming component

128 is preferably constructed and operated in the manner

described in co-owned United States Letters Patents 3,083,106

and 3,129,545, the disclosures of which are incorporated

herein by reference.

Individual product-enclosing packages 150 emerge

from the package forming unit 128 in a chain joined by a

continuous web 151. These packages are then introduced into

the controlled seal heating means 129a and 129b. As is

shown in the illustrative enmbodiment, controlled seal heating

means 129a is in the form of a continuous die belt 152 which 26 474,635

34,24 2 [71L moves about horizontally spaced rollers or drive means 153

and 154 in a counterclockwise direction. Attached to die

belt 152 are a series of spaced upper die members 155 each

of which is heated by suitable means for providing controlled

heating of the seal interface area. For example, in the

illustrated embodiment, each of the dies 155 is connected to

a flexible supply hose 156 and flexible return hoses 157.

Hot water from a heated central well 158 is circulated through

each of the supply hoses 156 into each of the respective die

members 155 and then sent back to well 158 via return hoses

157 wherein the water is reheated prior to recirculation.

If desired, electric or other suitable means can be employed

for heating the die members 155 so that they will supply the

seal interface area of the package with the desired amount

of heat. Die members 155 are generally shaped to conform to

the upper surface of each of the packages 150 and are respectively

spaced so that they overlie each of the packages 150 is a

closing relationship therewith as the packages 150 exit

from package forming apparatus 124. The individual dies

155 are shaped in accordance with the upper contour of the

packages and the interior construction thereof will depend

upon the precise heat supply employed as well as on the

shape of product being packaged. For example, if a plurality

of wieners or wiener-like sausages were to be packaged in

the apparatus 124, the respective die members 155 can be

shaped as is shown in co-owned United States Letters Patents

.21 474,635

3 4,2 42/'71- 3,083,106 and 3,129,545, the disclosures of which are incor-

porated herein by reference.

The lower radiant seal heating means 129b in the

illustrative embodiment can be used to provide an additional source of heat for heatIng the seal interface in accordance with the present invention. In some installations, however,

it will be observed that sufficient heating of the seal inter- face area can be accomplished from either of controlled seal heating means 129a or 129b operating alone. If desired, seal heating moans 129b could be constructed in the form of a plurality of hezated die members comparable to seal heating' means 129a or other suitable design.

In accordance with this aspect of the present inven-

tion, the heating of the seal area is controlled in order to raise the temperature at the seal interface to a level where- in the seal tenacity is substantially improved but which does not adversely affect the breakaway property or peel- ability of the EVA-thermoplastic film seal. The maximum temperatures employed are below the melt temperatures of the film materials which make up the package and form the seal. Typically these temperatures will range from approx-

imately 80 0 F. to approximately 200 0 F. and, as such, this heating step is readily distinguishable from conventional heat seal techniques wherein at least one of tho film materials at the seal interface is heated to a temperature above its melting point in order to induce fusing thereof 28 474,635

34, 22 42 to the other film material making up the seal. As such, con-

ventional heat seals are difficult to open and are not of

the peelable or breakaway type which is characteristic of the

present invention. Other disadvantages of conventional heat

sealing are that with such techniques there is a tendency

toward some extrusion or thinning of the film and distortion

accompanied by a change in crystal arrangement throughout

the seal area.

The individual packages 150 upon receiving this

controlled heating to the seal area from seal heating means

129a and 129b are then further heated by one or more heating

elements 130a and 130b in order to effect crystallization of

the polyvinylidene chloride films. This heating step can,

of course, be eliminated where the packaging films do not

undergo the previously noted supercooling or amorphous

condition. In some installations it is possible to accom-

plish heating of the polyvinylidene chloride film to effect

crystallization and heating of the seal area to improve

seal tenacity in a single step. By way of example, the

temperature of the polyvinylidene chloride film 136 and

polyvinylidene chloride laminae 137 and 139 in the film

lamination 140 can be raised to approximately 150 0 F. for

purpose of inducing crystallization thereof. If desired,

however, such crystallization can be obtained by permitting

the packages to be stored at.room temperature for a pro-

longed period of time. 29 47 4,6

34, 24 2 /7nL The packages upon being formed and treated in accord- ance with the manner described above, are then received in

the combination package trimmer and labeling unit 131 wherein

labels are applied thereto and they are separated from the

web 151 which is received upon a suitable collecting roll 165.

The separated packages 150a are then dropped from the package

trimmer and labeler 131 onto a conveyor belt 166 which is driven by a suitable drive means 167 and such packages are

in condition for further handling, storage or direct shipping.

Figure 10 generally illustrates another embodiment

of continuous film extruding and package forming apparatus

wherein means is provided for applying controlled amounts of

heat to the seal interface area of the packages 150 at the

time of seal formation in order to provide the thus formed

package with a peelable or breakaway seal of improved ten-

acity. This apparatus is generally designated by the ref-

erence numeral 175 and includes certain components which are identical to those previously described in conjunction

with the apparatus 124 of Figure 9. Accordingly, like

reference numerals have been used to designate like com-

ponents in apparatus 175.

The apparatus embodiment 175 shown in Figure 10 however, includes a modified seal heating means 176 which

can be substituted for the seal heating dies 155 of seal

heating means 129a shown and described in Figure 9. In

particular, seal heating means 176 is in the form of a

474,635 plurality of infra-red heating lamps which are arranged to produce heating of the seal interface area which will result in a seal of improved tenacity without adversely effecting the peelability or breakaway property thereof. The seal heating means 176 shown in this embodiment is particularly suitable for heating the seal interface area in products of irregular shape since it affords a convenient means by which a large and irregularly shaped seal area can be uniformly heated, such as one wherein the seal closely conforms to the contour of the irregularly shaped product a pork chop, etc.). In this regard, it will be noted that the package forming apparatus 128 when constructed and operated as des- cribed above, will result in a vacuum having been drawn within the package so that the upper and lower films and/or film laminations will themselves be drawn about the product in a product shape conforming relationship therewith. Upon heating of the seal interface area by the infra-red lamps

176 and heating element 129b to a temperature below the melt

temperature of either of the film materials at the seal

interface, an improved peelable or breakaway seal of the

present invention will be provided. As previously noted,

this seal in conforming closely to the shape of the product,

affords the packaged product with a number of significant

advantages. For example, the product itself will be per-

manently positioned within the package with little or no

loose film on the package thereby substantially minimizing

31 474.635

34,24-2/1 damage to the package during shipment which could result in product contamination. Likewise, with the packaging of food

products the product shape conforming seal offers an important advantage insofar as it essentially eliminated the unsightly

appearance produced by the fre movement of water and product

juices which would be loosely contained in the package and also minimizes the amount of residual oxygen present therein. The use of infra-red lamps 176 alone rather than in

conjunction with the heating element 129b is generally the most efficient seal heating technique employed where the product is placed upon a product board or film having a low coefficient of thermal conductivity. In this regard, however,

it is possible where the lower film lamination consists

of a two or three-ply film lamination or an EVA coated film such as film 149) to supply heat to the seal area from the heating element 129b or an equivalent heat source. When paper is used as one of the constituents in the package, it is generally preferred to use a heat lamp such as the infra- red lamps 176. In some instances, a hot air stream or

equivalent means can be used where it is desired to heat the seal interface area without directly contacting the packaging

films with a die 155 or equivalent heated platen.

.Referring to Figures 11-13, -a modified package 185

is shown which in the illustrated embodiment encloses a plurality of wieners or wiener shaped products in closely

spaced side by side relation to each other. As is best shown

132 47 4,635

34,24 2 in Figure 13, the package 185 is formed of a top three-ply

film lamination 186 and a botttmi film 187 which, in accord-

ance with a preferred embodiment of the present invention,

is partially coated with an EVA coating 188 selectively

applied to the portion of film 187 adjacent one end of the

package; this portion of film 187 is illustrated in the

drawings by the bracket 184. The seal area within the

brackets 184 can be easily peeled back when access to the

product is desired so as to provide a technique by which

controlled access to the product is afforded and by which

further seal destruction by the consumer is effectively

avoided. This selective partial EVA coating 188 of film

187 facilitates resealing of the package when less than the

entire contents thereof are removed.

While the specific films which form the film lami-

nation 186 will depend upon the particular requirements of

the package and the characteristics of the product being

packaged, in the packaging of food products subject to

oxygen deterioration, the top film lamination will generally

include an outer oxygen barrier film 189, a suitable inter-

mediate film 190, and a bottom lamina 191 composed of a

thermoplastic film material which will farm a breakaway or

peelable seal with the EVA or equivalent copolymer coating

188 on the bottom film 187. Typically, outer film lamina

189 could be composed of a polyvinylidene chloride film

having a vinylidene chloride content of approximately 33 47 4.635

34,242/'. to 80% by weight and a vinyl chloride content of from approx-

imately to 10% by weight. Likewise, film lamina 190 can

be composed of any material which readily adheres to laminae

189 and 191 such as, for example, an EVA film having a vinyl

acetate content of at least 30% by weight or other suitable

film material such as chlorinated polyethylene and compounded

polyvinyl chloride and polyvinyl chloride-vinyl acetate

copolymer films. If desired, the inner film or lamina 191

may be composed of a flexible polyvinylidene chloride film

such as one having a vinylidene chloride content of 68% by

weight and a vinyl chloride content of 32% by weight.

Film 187 is preferably composed of any suitable

transparent oxygen barrier film material. Typically, this film should have an oxygen transmission rate of not more

than 10 cubic cm., per 100 square inches, per 24 hours, per

mil thickness, at 770 F. and 760 mm. Hg. Polyvinylidene

chloride films comparable in composition to upper film

lamina 189 can be desirably used for this purpose.

As is shown, the top film lamination 186 and bottom

film 187 are drawn about the wiener shaped product in a sur-

face conforming configuration therewith and are joined

peripherally around the edge of the products to form a con-

tinuous edge seal 192. In order to facilitate access to the

product and ready separation of the film lamination 186 from

the EVA coated film 187, paper or equivalent inserts 193 and

194 can be provided adjacent the end of the package which is

,a 1 474,635

3 4,242/7). to be opened.

Figures 14 and 15 illustrate a package embodying principles of the present invention which is particularly adapted for use with a bacon product. The package 200 com- prises a baseboard or member 201 which is formed of any suitably relatively rigid material such as bleached kraft paperboard which may have a thickness of from 0.01 to 0.02 of an inch. M~ounted centrally on the product board 201 is a bacon product 202 which bacon product can be in the form of a plurality of stacked bacon slices that extend along the product board 201 in an inclined position. The package includes a top film lamination 203 which completely covers the product 202 and extends downwardly along the edges thereof in intimate contact therewith and then extends over the pro- duct board 201 and into sealing engagement with the exposed peripheral top surface 2 01a of the product board 201 and the upper surface 204a of a bottom film lamination 205 com- posed of an inner film lamina 204 and outer film lamina 206. Top film lamination 203 is composed of an outer film lamina 207 and inner film lamnina 208. in accordance with a pre- ferred embodiment of the present invention, a peelable or breakaway hermetic seal is provided by having either film lamina 204 or film lamina 208 composed of an EVA film or coating which has a vinyl acetate content of from 10% to by weight with the remaining film lamnina being composed of a suitable thermoplastic film material which provides a

474,6

34,24 2 n,_ breakaway or peelable seal therewith. For example, top film

lamination 203 can be composed of an outer oxygen barrier

film 207 such as a polyvinylidene chloride film having

vinylidene chloride content of from approximately 85% to

by weight and a vinyl chloride content of from approximately

to 10% by weight. Film lamina 208 can be composed of

an EVA film having a vinyl acetate content of from approximately

to approximately 40% by weight with the vinyl acetate

content of from approximately 15% to 20% being preferred.

Film lamination 205 can include an inner film lamina 204

composed of a flexible polyvinylidene chloride film having

a vinylidene chloride content of approximately 32% by weight

while outer film lamina 206 can be composed of a suitable

oxygen barrier film such as upper film lamina 207 of film

lamination 203. Either of the two-ply film laminations 203

or 205 can be substituted by a single ply film having an

EVA coating or a modified two or three-ply film lamination.

The present invention is not limited to any specific film

materials other than that one of the films at the seal

interface provides a hermetic and peelable seal. A corner

portion of the package 200 can be provided with a triangular

insert 209 which is preferably formed from a material which

will not adhere to the covering film lamination 203. A

small corner portion of the upper film lamination 203 ex-

tends over the triangular insert 209 but is not adhered

thereto, thereby enabling the upper film lamination to be 36 474,635

34,242 readily lifted and grasped for subsequent peeling of the film from the surface of the seal interface and product when access to the package is desired.

Figures 16 and 17 illustrate a modified bacon

package 225 which is also made in accordance with the present invention. In particular, the package 225 provides a method by which the bacon product can be packaged without the use of a rigid tray like member as shown and described in con- junction with the embodiment of Figures 14 and 15. In particular, the package 225 includes an upper film lamination 226 composed of an outer oxygen barrier film lamina 227 and inner lamina 228 which is composed of an EVA or equivalent copolymer film or coating having a vinyl acetate content of from approximately 10% to 40% by weight. As is shown, film lamination 226 extends over a bacon product 229 in conforming relationship therewith, extending along the edges of the product and outwardly therefrom in adherent contact with a bottom film lamination 230 formed of an inner lamina 231 composed of a suitable thermoplastic film which will form a peelable or breakaway seal with the EVA coating or film 228. Bottom lamina 232 of film lamination 230 is com- posed of a suitable oxygen barrier film of the type previously described. In accordance with a preferred embodiment of the present invention, inner lamina 228 is composed of an EVA film or coating having a vinyl acetate content of from approximately 15% to 20% by weight while the film lamina 231

37 474,635

34,24 217' of bottom film lamination 230 can be composed of a polyvinyl-

idene chloride film having a vinylidene chloride content of

approximately 68% by weight and vinyl chloride content of

approximately 32% by weight. A suitable paper or other

equaivalent non-adhering insert 33 can be provided in the

corner of the package to facilitate the peeling of the upper

film lamination 226 when access to the product is desired.

Figures 18 and 19 illustrate a further modified

bacon package 241 embodying principles of the present invention

wherein a lower film lamination such as film lamination 205

of the embodiment shown in Figures 14 and 15 and film lami-

nation 230 of the embodiment shown in Figures 16 and 17 can

be eliminated. As is best shown in Figure 19, the package

241 generally includes an upper film lamination 242 which

can be composed of a suitable oxygen barrier film 243 and

an inner lamina 224 composed of a suitable thermoplastic film

which when contacted with an EVA coating or film will form

a hermetic peelable or breakaway seal therewith. For

example, outer film lamina 243 could be composed of a

plasticized polyvinyl chloride film and inner film lamina

224 could be composed of a polyvinylidene chloride film

having a vinylidene chloride content of from approximately

68% to 90% by weight and a vinyl chloride content of from

approximately 32% to 10% by weight. Upper film lamination

242 covers the product 245 which in the illustrated embodi-

ment consists of a plurality of stacked bacon slices which

38 474,635

34,2 4 2 n extend along the package as generally shown in Figure 18.

The bacon product 245 can be placed on the lower board

member 246 which is generally composed of a suitable rigid

member such as a foamed polystyrene board or equivalent

material having a thickness sufficient to provide the package

with the desired degree of rigidity. In the illustrated

embodiment, polystyrene board 247 is coated on its top and

bottom surfaces with polyvinylidene chloride coatings 248

and 249, respectively, with upper coating 248 being further

coated with the preferred EVA coating 251 having a vinyl

acetate content of from approximately 10% to 40% by weight.

Typically, this EVA coating will be from 0.1 to 0.2 of a

mil in thickness, however, this invention is not limited

to any specific EVA coating thickness. Upper film lamina-

tion 242 is placed over the bacon product 245 in conforming

relationship therewith by the evacuation of air from the

interior of the package during package formation with a

hermetic peelable or breakaway seal being formed between

the EVA coating on the board and the polyvinylidene chloride

or other equivalent thermoplastic material of the film 244.

A portion of the bottom board member 246 can be provided

with a suitable triangular insert 250 formed of a material

which will not adhere to the top film lamination 242 and

which enables the consumer to grasp a corner of the top

film lamination 242 for gaining access to the contents of

the package by easily lifting such top film lamination which

39 474,635

34,24 2 /1" will readily separate from the EVA coated board member 246.

.Each of the bacon packages shown in Figures 14-19 can be modified in manners which will be obvious to those skilled in the art. For example, the hermetic peelable or

breakaway seals thereof can be improved by heating the seal interface at the time of seal formation to a temperature

below the melt temperatures of the respective film materials which make up such seals. Likewise, if desired, such packages

can be formed without heating the seal interface particularly

where the film which is contacted with the EVA or equivalent copolymer film or coating at the seal interface is a poly- vinylidene chloride film which when contacted with such EVA film or coating is in an amorphous or supercooled condition. However, as previously noted, the concept of using a supercooled polyvinylidene chloride film and EVA or equiva- lent copolymer film or coating to form the seal and simultan- eously providing controlled amounts of heat to such seal interface which controlled amounts of heat do not raise either of the film materials at the seal interface to a temperature above their melting points provides a preferred hermetic peelable or breakaway seal.

While certain embodiments of the present invention

have been described in detail, it will be apparent that

various modifications and v;1riations thereof may be made

without departing from the spirit and scope of this invention. Accordingly, only such limitations are to be imposed on this invention as are indicated in the appended claims. 474 47,3

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A package comprising a product enclosed between first and second layer of packaging material, said first layer

of packaging material having a seal-forming surface formed of a copolymer of ethylene and a polar monomer film material,

said seal-forming surface of said first layer of packaging material being adhered without use of adhesives to said second

layer of packaging materiil formed of thermoplastic film

material to define a hermetic seal, said ethylene-polar monomer copolymer film material having a polar monomer content

which enables said hermetic seal to be separated when access to

said product is desired. 2. The package of claim 1 wherein said polar monomer is selected from the group consisting of vinyl acetate, isobutyl acrylate and ethyl acrylate.

3. The package of claim 1 wherein said polar monomer is present in said copolymer film material in a concentration

of from 10% to 40% by weight.

4. The package of claim 1 wherein said hermetic seal was heated to a temperature of from 80 0 F. to 200 0 F. at

the time said ethylene-polar monomer copolymer film material was adhered without use of adhesives to said thermoplastic

film material.

The package of claim I wherein said surface of said first layer of packaging material is formed of an ethylene-

vinyl acetate copolymer film material having a vinyl acetate

content of from 10% to 40% by weight.

47 4,6

3 4,24 2 n:

6. The package of claim 5 wherein the vinyl acetate

content of said ethylene-vinyl acetate copolymer film material is from approximately 15% to 20% by weight.

7. The package of claim 5 wherein said second layer of packaging material has a surface formed of a polyvinylidene

chloride film which has been adhered without use of adhesives

to said ethylene-vinyl acetate copolymer film material while

said polyvinylidene chloride copolymer film is an an amorphous

supercooled state.

8. A package comprising a product enclosed between first and second film laminations, said first film lamination

comprising a lamina formed of an ethylene-polar monomer co-

polymer film material, said polar monomer being present in

said film lamina in a content of from 10% to 40% by weight,

portions of said ethylene-polar monomer film material being

adhered without use of adhesives to said second film lamination

formed of a thermoplastic film material to define a hermetic

seal which can be separated when access to said product is

desired.

9. The package of claim 8 wherein said polar monomer is selected from the group consisting of vinyl acetate, isobutyl

acrylate and ethyl acrylate.

The package of claim 8 wherein said hermetic seal was heated to a temperature of from 80 0 F. to 200 0 F. at the

time said ethylene-polar monomer copolymer film material was

adhered without use of adhesives to said thermoplastic film

material.

42 474,635

34,242n/.

11. The package of claim 8 wherein said lamina is

formed of an ethylene-vinyl acetate copolymer film material.

A3 474635

34,24 2/71 12. The package of claim 11 wherein said ethylene-

vinyl acetate copolymer film material has a vinyl acetate

content of from approximately 15% to 20% by weight.

13. Tbe package of claim 11 wherein said second

film lamination includesla polyvinylidene chloride film which

is in adherent contact with said portions of said ethylene-

vinyl acetate copolymer film material, said polyvinylidene

chloride film having been adhered to said ethylene-vinyl

acetate film material while said polyvinylidene chloride

film is in an amorphous supercooled condition.

14. A package comprising a meat product enclosed

between first and second film laminations formed about said

product in t-ight surface conforming contact therewith, said

first film lamination having at least one lamina formed of

an oxygen barrier film and an inner lamina formed of an

ethylene-polar monomer copolymer film having a polar monomer

content of from approximat-ely 10% to 40% by weight, a second

film lamination having at least one lamina formed of an

oxygen barrier film and an inner lamina formed of a

thermop,-I&stit film, portions of said ethylene-polar monomer

copolymer film and said thermoplastic film being in adherent

contact with each other to define a hermetic seal which can

be x-eed+I'y separated when access to said meat product is

desired.

The package of claim 14 wherein said polar

monomer is selected from the group consisting of vinyl 44 474.635

34,242nL acetate, isobutyl acrylate and ethyl acrylate. 16. The package of claim 14 wherein said hermetic seal was heated to a temperature of from 80 0 F. to 200 0F. at the time said ethylene-polar monomer copolymer film was adhered to said ther'oplastic)film.

17. The package of claim 14 wherein said product comprises a plurality of wiener-shaped sausages arranged in side-by-side relation.

18. The package of claim 14 wherein said inner lamina of said first film lamination is formed of an ethylene- vinyl acetate copolymer film. 19. The package of claim 18 wherein said ethylene- vinyl acetate copolymer film has a vinyl acetate content from to 20% by weight.

The package of claim 18 wherein said thorme- plastfl44%,-e polyvinylidene chloride film e -h 9 been brought into adherent contact with said ethylene-vinyl acetate copolymer film while said polyvinylidene chloride film is in an amorphous supercooled state. 21. A method of enclosing a product between a pair of film laminations which can be readily separated when access to said product is desired, said method comprising the steps of inserting a product between first and second film laminations, said first film lamination having a lamina adjacent said product which is formed of an ethylene- polar monomer copolymer film material having a polar monomer

474,635

24,242

content of from 10% to 40% by weight, said second film

lamination having a lamina adjacent said product which is

formed of a polyvinylidene chloride film, contacting said

ethylene-polar 'monomer copolymer film lamina with said

polyvinylidene chloride film lamint~ about said product to form a hermetic seal which completely encloses said product

between said first and second film laminations. 22. The method of claim 21 wherein said polar monomer is selected from the group consisting of vinyl acetate,

isobutyl acrylate and ethyl acrylate.

23. The method of claim 21 wherein said ethylene- polar monomer copo lyiner film lamina and polyvinylidene chloride

film lamnina are heated to a temperature of from 80 0 F. to 200 0F

at the time of forming said hermetic seal, whereby the adhesion

of said seal is improved without destroying the breakaway

property of peelability thereof.

24. The method of claim 21 wherein said lamina of said first film lamination which is adjacent said product is formed of an ethylene-vinyl acetate copolymer film.

The method of claim 24 wherein said ethylene- vinyl acetate copolymer film material has a vinyl acetate

content of from 15% to 20% by weight. 26. The method of claim 24 wherein said polyvinylidene

chloride film which when initially contacted with said ethylene- vinyl acetate copolymer film lamina is in an amorphous super- cooled state.

46 4 74.635

34,24 2 m7

27. A method of enclosing a product between a pair

of film laminations substantially as herein described with

reference to Fig. 1 or Fig. 9 or Fig. 10 of the accompanying drawings.

28. A package substantially as herein described and with reference to Figs. 2 and 3, or Fig. 4, or Figs. 5, 6, 7 and 8, or Figs. 11, 12 and 13, or Figs. 14 and 15, or Figs.

16 and 17, of:the accompanying drawings.

D A T E D this 5th day of October, 1971.

OSCAR MAYER CO., INC. By its Patent Attorneys: CALLINAN AND NEWTON

1

474.635

34,2 4 2 n-

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49'6 474.6

34,2 4 2 iL,

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474.635

3 4,2 4 2 nL

53 5~4 74.63

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185

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192

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189 S L3

474,835

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200 207 208

201

t19-15-~0~206

225

227 2262 ~14n 22

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230

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241 224 243

245 242

248 4 24T 249

57 1 474,635