JP3213913B2 - Polyvinylidene chloride methyl acrylate copolymer compositions, films, and structures that retain high gas barrier properties after retort - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrier polymer material having high gas barrier properties, particularly oxygen barrier properties, and which retains desired properties even when subjected to retorting. In particular, the present invention relates to polyvinylidene chloride copolymer compositions, and more particularly to compositions comprising polyvinylidene chloride-methyl acrylate copolymers which retain essentially high gas barrier properties, especially oxygen barrier properties, even after retorting.

[0002]

2. Description of the Related Art Retorting is a widely used method for preparing food in packages prior to sale and for sterilizing other substances such as food or medical supplies. For example, a process for cooking food in a package and killing microorganisms such as bacteria in the substance. Retorting is a heating process that involves heating the packaged contents with heated or boiling water, typically steam at about 212 ° -275 ° F. (100-135 ° C.). . Heated water above about 212 ° F. (100 ° C.) can be used to retort with a suitable pressure.

A pouch for a package for retorting is disclosed, for example, in US Pat. No. 4,190,477.
No. 11742, No. 4360550, and 44242
No. 56. A common feature of such prior art pouches is that they are layers of metal foil. The foil is a gas barrier that retains such properties even after severe retorting.

[0004] Consumers use microwave ovens to cook or reheat prepackaged foods. The industry also wants to employ the microwave process to cook and sterilize packaged ingredients. As is well known, metal objects should not be used in microwave processes such as cooking, heating or sterilizing food in a microwave oven. Therefore, packages with metal foils do not meet many needs today.

[0005] For example, food cooked, packaged, and sold to be cooked / reheated in a package by a consumer can be prepared / reheated if the package has a metal foil layer. If a microwave oven could not be used to do so, such food would not be able to meet the needs of consumers. Furthermore, if it were not possible for such packaged food to be subjected to cooking / reheating in a microwave, it would not be desirable to a consumer having a microwave oven, and It may not be desirable for consumers who want to enjoy the benefits of using microwaves for cooking / reheating, such as fast cooking, low radiant heat, and other benefits. Similarly, if the packaged item is not microwave sterilizable, the business purchaser will be opposed to packaging such item.

[0006] Therefore, there is a great demand for packages that do not have a metal foil layer. However, the retorting and microwave processes subject the package to harsh conditions, ie, high temperature, pressurized, and / or heated water or steam or other conditions. For the microwave process, the water in the packaged material is converted to steam, thereby subjecting the package to conditions similar to retorting conditions. Therefore, there is a great need for packages that can withstand the rigorous conditions of retorting without having a metal foil layer.

[0007] The polyvinylidene chloride copolymer is supplied as a resin. For example, Dow Chemical sells the resin under the trademark Saran. Such Sara
The n ranges are known as VC Saran and MA Saran. Dow manufactures single-layer VC Saran films under the trademark HB Saran. MA Sar
an is a methyl acrylate-polyvinylidene chloride copolymer. In this regard, WO 89/034
11 (International application PCT / US88 / 03515; Priority application US application No. 107141, filed October 9, 1987) and WO 89/3412 (International application PCT / US8).
8/03516; priority application US application 107137
No., filed Oct. 9, 1987), and such description is incorporated herein by reference. Such international application not only relates to polyvinylidene chloride copolymers and compositions, but also represents the current understanding of such copolymers and compositions.

In such an international application, a film or other article may be formed from a polyvinylidene chloride copolymer, and such an article may have, for example, low gas permeation for oxygen, carbon dioxide, water vapor, odor, odor, hydrocarbons or pesticides. It is recognized that it has the property.

However, to obtain such an article, the polyvinylidene chloride copolymer resin must be extruded, which is problematic. If no modifier is used with the resin, the melt viscosity of the resin is high, the load on the extrusion screw is high, and the copolymer is thermally decomposed. The degraded copolymer produces undesirable amounts of carbon and hydrochloric acid in the extrudate.

Furthermore, as recognized in the above-mentioned international application, relatively large amounts of stabilizers and plasticizers are required for industrial extrusion of polyvinylidene chloride copolymer resins without thermal decomposition and discoloration. Need to be mixed in.

The industry has taught that ethylene vinyl acetate (EVA) has been added to polyvinylidene chloride copolymer resins to improve extrudability without significantly reducing barrier properties. In fact, extrusion aids for EVA-containing polyvinylidene chloride copolymer compositions have been favored in the industry. Furthermore, in the industry, E
EVA was reacted with additives such as epoxidized oils for VA plasticizer and lubricant properties.

However, not only the above-mentioned international application, but also other references relating to the use of polyvinylidene chloride copolymer extrudates, such as US Pat. No. 4,714,638, indicate that retorting adversely affects the barrier properties of polyvinylidene chloride extrudates. Did not realize that.

[0013] It has now been discovered that when many packaging materials, especially polymer films, are subjected to retorting, desirable properties such as barrier properties are damaged. After retorting, the packaging material becomes more permeable to gases, such as oxygen and air, and reduces the shelf life of the contents in the package.

Ethylene vinyl alcohol (EVOH)
Is used as an oxygen barrier when adjusting the packaging material. However, EVOH is sensitive to moisture.
EVOH absorbs water during retorting and similar processes, thereby reducing oxygen barrier properties. With the passage of time and loss of moisture, there is some recovery of barrier properties, however, the packaged material has already undergone oxygen degradation.

It is well known that films formed from Saran resin are of good barrier properties which are unaffected by retorting. Alternatively, those skilled in the art were not aware that retorting would adversely affect films, especially films from Saran resin, as discussed below. However, as a result of retorting, the HB Saran film will have an increase in oxygen transmission of at least about 30-70%.
This increase in transmittance is observed even when HB Saran does not contain EVA.

Similarly, MA containing EVA is used as an extrusion aid.
Films from Saran and films made of polyvinylidene chloride-methyl acrylate copolymer blended with EVA will result in at least about 30-100% increase in transmission as a result of retorting.

[0017]

SUMMARY OF THE INVENTION The main object of the present invention is therefore to provide a gas barrier film which is suitable for forming a film which retains gas barrier properties even under severe conditions such as retort processing. And a novel polyvinylidene chloride-methyl acrylate copolymer composition.

The present inventors have proposed polyvinylidene chloride (PV)
Films made from blends containing dC) -methyl acrylate (MA) copolymer and certain stabilizers, but without the extrusion aid EVA, which has heretofore been considered suitable, may be retorted or similar. It has been surprisingly found that there is no noticeable decrease in oxygen barrier properties upon and after treatment. Polyvinylidene chloride (PVdC) methyl acrylate (M) according to the present invention
A) Blends comprising copolymers and certain stabilizers are suitable for use as gas impermeable films, such as when refilling various substances, such as foods, pharmaceuticals and others after filling.

The present invention provides a novel composition and packaging film containing an EVA-free polyvinylidene chloride-methyl acrylate copolymer.
The present invention provides a method of packaging an article using such a film, and a method of heat treating such an article and a package by, for example, retorting. Such substances are:
For example, foodstuffs and the like are safely heated by microwaves and other heat sources or cooked for consumption or other uses.

The blends of the present invention having improved post retort gas barrier properties include a polyvinylidene chloride-methyl acrylate copolymer and are essentially free of EVA. Polyvinylidene chloride-methyl acrylate copolymer compositions containing even a small amount of EVA are adversely affected by retorting, and the gas barrier properties of polyvinylidene chloride-methyl acrylate copolymer compositions that do not contain EVA are also reduced by retorting. It was surprisingly discovered that only a small amount was adversely affected.

That films made with Saran resin were not expected to be adversely affected by the retort treatment;
Those skilled in the art were not aware that films from Saran resin were not adversely affected by retorting, and that polyvinylidene chloride-vinyl chloride copolymer without EVA was said to have reduced barrier properties after retorting. Assuming that, MA containing EVA
Not only is the barrier properties of films made from Saran (or polyvinylidene chloride-methyl acrylate copolymer) adversely affected by retorting,
It is quite surprising that it has been found that the reduction in barrier properties is critically dependent on the plasticizer.

In particular, polyvinylidene chloride copolymers
Films made from such resins were not expected to be affected by the retort process, or the skilled artisan was not aware of the problem of reduced barrier properties after the retort process. The discovery of the decline is completely unexpected. In addition, for films made from polyvinylidene chloride-methyl acrylate copolymer, reduced barrier properties are due to the plasticizer EV.
It was more unexpected to find that it was critically dependent on the presence of A. Because both PVd
The plasticizer of the c-copolymer was considered equivalent, and E
This is because VA or EVA-containing plasticizers were the preferred extrusion aids, and a decrease in barrier properties after retort is seen in films made of PVdc-vinyl chloride regardless of the presence of EVA.

The polyvinylidene chloride employed in the present invention
In the methyl acrylate copolymer, the methyl acrylate should preferably be present at 3-8 wt%, more preferably 6-8 wt%, based on total weight. However, it is conceivable to use a polyvinylidene chloride-methyl acrylate copolymer which results in an upper limit of the content of methyl acrylate of about 12%, and even in some cases about 15%.

The additives used in the blend according to the invention include epoxidized linseed oil, epoxidized soybean oil,
It is a stabilizer selected from the group consisting of magnesium hydroxide, magnesium oxide and tetrasodium pyrophosphate. Such additives comprise about 0.5 to the total weight of the blend.
To 3 wt%.

At present, epoxidized linseed oil and magnesium hydroxide are preferred stabilizers. Epoxidized linseed oil is available from Vikoflex 7190 (Viking C
Chemical Company).
Although some variations are possible, concentrations of the stabilizer greater than about 3% significantly reduce gas barrier properties.

The blend of the present invention can be extruded into a film,
It is then formed in a conventional manner into a package such as a pouch, lidstock, barrier sheet, or other article to be retorted. Such films and packages are encompassed by the term "film package" as used herein. Although the blends of the present invention can be used as monolayer films, in a preferred embodiment at least one
Used as multilayer extrudates and multilayer laminates using multiple outer film layers. The blend of the present invention is a sheet,
It can also be used to make tubes and containers.

The film of the present invention may be formed as a single layer or a co-extruded product or a laminate by extrusion, co-extrusion, extrusion coating, extrusion lamination, cast / co-extrusion,
It can be made by any of the conventional methods, such as blow coextrusion, adhesive lamination, and the like, and combinations thereof. If desired, for example, for a particular end use, the film or laminate can be oriented by conventional methods such as blow tube orientation, stretch orientation, or molecular orientation. They shrink and otherwise hit set.

The films of the present invention are crosslinked by conventional methods such as irradiation, heat, or the addition of a crosslinking agent. These treatments should be performed with care to avoid adversely affecting the gas barrier properties after retort and / or to avoid PVdC decomposition. For background on films and equipment for making them, see US Pat.
No. 77099, No. 4755402, No. 3558330
No., No. 471438, No. 4842791, No. 43
79117 and 4804510,
A currently pending U.S. application (A)
totorneyDocket No. 14784),
And U.S. Application Nos. 458487 and 458488.
No., 458485, 458490, 4584
86, 458484, which are incorporated herein by reference.

The novel extrudates and other film layers useful in the laminates of the present invention can be any of those commonly used in the art, such as polyethylene (PE), medium density PE (MDPE), High density PE (HDPE), low density PE (LDPE), linear low density PE (LLDPE),
Very low density PE (VLDPE), polypropylene (P
P), linear ultra low density PE (ULDPE), propylene
Ethylene copolymer (PPE), nylon, high impact polystyrene (HIPS), ethylene butene copolymer (EB), polyethylene terephthalate (PE
T), a copolymer of PET or CoPET, or even EV
A (preferably EVA with a high VA content, ie 28-35
EVA containing wt% VA) or a mixture thereof.

However, compositions containing EVA and LLDPE and their copolymers deform at elevated temperatures such as retort conditions. Therefore, PP is preferred for the outer layer.
A presently preferred embodiment is a film comprising a plurality of superimposed layers, a layer comprising a first layer forming a core disposed between a second layer and a third layer;
A poly (vinylidene chloride-methyl acrylate) copolymer blend containing no VA;
P is included. Further, when such additional film layer is a food film package or other controlled article, such as a food retort pouch, such film layer should obtain appropriate government approval, such as FDA approval.

In a multilayer film having a film of the composition of the present invention, a tie layer or adhesive layer may be present between the layers of the multilayer film. Suitable materials for such tie or adhesive layers are known to those skilled in the art, including anhydrous modified polyolefins, ethylene acrylic acid copolymers, ethylene methyl acrylate copolymers, PP and EVA
Or other synthetic resins or the like. The adhesive chosen should be stable under the conditions under which the films of the present invention are made and used. Additional information about adhesives is described in commonly-assigned U.S. Patent Application No. 458489, which is incorporated herein by reference.

Commercially available products for the layers in the multilayer product of the present invention include nylon 6; 11; 12; 6.
12; and 6,66; ULTRAMIDKR 4600
(BASF), NOVAMID 2030 (Mitsubishi Kasei), DURATHANE (Farberfabrik)
en Bayer A. G. FIG. ), 1030 (Unitika), ZYTEL SUPERTUFF 811 (Du
Pont), 4018 (Huels, Germany), and ELY
1256 (Elmser, Switzerland), Mylar, Da
lar, Exxon 5610A-2 (P with EVA)
P blend), Admer (Mitsui Petrochemical No. AT4
69C), Bynel (DuPont, E361 or 3)
036) and Plexar 3342. A
dmer, Bynel and Plexar 3342 are considered maleic anhydride-modified polyolefins.

The film (monolayer or multilayer) of the present invention may have the same thickness as a conventional film. That is, about 2.0 mils (0.051 mm) with a typical range of about 1.5 to about 3.0.
(0.038-0.076 mm). Conventionally, films less than about 1.5 mils (0.038 mm) were considered too weak to perform the required function, whereas the monolayer of the present invention is about 3/4 mil or thicker. May be. Films up to about 20 mils (0.51 mm) work, while films thicker than about 3.0 mils (0.076 mm) are economically inefficient. The 20-200 mil sheet structure of the present invention is economical for use in rigid plastic packages. This sheet can be used for trays or other rigid containers.

The single-layer or multi-layer film or sheet of the present invention is formed by heat sealing the periphery of the shape to be formed on the pouch.
The final container, or by a conventional method such as sealing with an adhesive, or
Formed into a film package, for example, a pouch.
For example, if a square pouch, such as a retort pouch, is desired, a rectangular film twice as long as the desired length of the pouch is folded and its surrounding two parallel sides (perpendicular to the fold line). ) Is heat- or adhesive-sealed, filled with the food or other item to be packed, and then the peripheral open end is heat- or adhesive-sealed. Another method of making a retort pouch is to seal the three ends of the facing film, fill the thus formed open pouch with food or other material to be packed, and then replace the fourth end (open end). It is to seal.

For background art on pouches and their manufacture, see US Pat. Nos. 4,190,477 and 4,311,742.
Nos. 4,360,550 and 4,424,256, the disclosures of which are incorporated herein.

Retort pouches are usually used for food, medical supplies,
Filling with blood or other material (the content of the filling does not limit the present invention). The package of the present invention, however, is particularly useful for retort pouches. Sealed retort pouches and pouches, such as trays containing food and microwaved, are typically Title 2
1, C.I. F. R. , Part113 (Definition, Sec11
Heat and retort at a temperature and for a time sufficient to achieve commercial sterilization as defined in 3,3). This article stipulates that: "The commercial degree of sterilization of thermally processed foods means the conditions achieved by the following treatments: (i) the food does not contain the following upon heating: (a) normal storage and sales; Microorganisms that can reproduce in food under non-refrigerated conditions; and (b) microorganisms (including spores) that can grow or are important to public health; or Be free of microorganisms that can reproduce in food under non-refrigerated storage or sale conditions. "

Generally, in order to kill microorganisms such as bacteria in food or other objects, the temperature and time of the heating is such that the food or other object reaches a temperature of at least 140 ° F. (60 ° C.). Must be enough. The preparation of food and the disinfection of microorganisms in food and other objects can be accomplished by removing pouches or trays containing food or other items from 212 ° F. (100 ° C.) to 275 ° F.
° C), for example, heating at 265 ° F (129.4 ° C),
Alternatively, it can be realized by retorting. Typical retort times are half an hour to one hour (typically less than one hour). The time and temperature of the retort depend on the contents and amount in the pouch or tray. This heating is done by heated or boiled water, steam or heated or pressurized steam; the heated water heats to a temperature of 100 ° C. or more without adjusting the pressure be able to. Heating is also achieved with microwave sterilization. The contents and the amount in the pouch or package are factors of the time and temperature of the heating.

The package has been found to be an excellent gas barrier that does not result in the degradation of the desired properties under retort conditions, including microwave conditions. fact,
Of the many advantages of the present invention, the co-extruded films of the present invention (e.g., the core layer is made from a polyvinylidene chloride-methyl acrylate copolymer blend essentially free of EVA) are perishable. A longer shelf life compared to a film of the same thickness as a film of a PVdC-vinyl chloride copolymer blend for packaging. In addition, if a longer shelf life is not required for the benefits of the present invention, the coextruded films of the present invention can be thinner than films of PVdC-vinyl chloride copolymer blends, As a result, costs can be reduced. Thus, the package of the present invention can provide a longer shelf life for perishable fillings, and has particular economic advantages when a long shelf life is not required.

For packaging, the preferred structure of the film or sheet formed into the pouch includes a second layer comprising PET and a sealant, preferably PP, or a blow sealant such as polyethylene, or a blend of these sealants. It comprises a plurality of superimposed layers, including a first layer of a co-extrudate of the invention, disposed between the third layers. A commercially available product suitable for blending as a sealant is Tafmer, eg, Tafmer, an alpha-olefin having elastomeric properties.
A (Mitsui Petrochemical). This film or sheet can be described as PET / first layer / sealant. Preferably, the film or sheet is about 1.5-3 mil thick, more preferably about 2.0 mil thick.

The first layer extrudate includes a core layer disposed between a pair of first intermediate layers, each first intermediate layer disposed between the core layer and each second intermediate layer, each first intermediate layer, and each first intermediate layer. A pair of second intermediate layers disposed between the outer layers and a plurality of layers including an outer layer including a first outer layer and a second outer layer.

The core layer comprises a polyvinylidene chloride methyl acrylate copolymer and a particular stabilizer, preferably about 98.8 wt% polyvinylidene chloride methyl acrylate copolymer (eg, Dow 119) and about 1.8 wt%. The first intermediate layer comprises EVA, preferably high VA content EVA (eg Exxon LD-761: VA content = about 28 wt.
%); The second intermediate layer is a polypropylene-based PP base adhesive or binding resin (Exxon 5610).
A-2 comprises a particularly useful PP base adhesive or binding resin); the first outer layer preferably comprises PP
(Eg Fina 3622), white PP concentrate opacifier (eg Chroma P20192A)
And EVA (especially EVA containing high VA; for example, Exxon
LD-761) blend, more preferably about 80w
comprising a blend of t% PP, about 10 wt% white PP concentrate opacifier and about 10 wt% EVA;
And the second outer layer is preferably PP (eg Fina)
3622) and EVA (especially high VA content EVA), more preferably 90 wt% PP and 10 wt% EVA.

The first layer is preferably [80% PP, 1
0% white PP concentrate opacifier and 10% EV
A / PP base adhesive / EVA / 98.8% polyvinylidene chloride-methyl acrylate copolymer and 1.2%
ELO / EVA / PP base adhesive / 90% PP and 10
% EVA]. Preferred examples of the first layer include a core layer of about 40 wt%, a first intermediate layer of about 3 wt% (particularly, each first intermediate layer is about 1.5 wt%), and a second intermediate layer of about 7 wt%.
An intermediate layer (especially each second intermediate layer is about 3.5 wt%) and an outer layer of about 50 wt% (especially about 30 wt% of the first outer layer and about 20 wt% of the second outer layer).

The preferred structure of the film or sheet can be formed into a lidstock that includes a plurality of overlapping layers. The superposed layer contained in the lidstock comprises a first layer of the coextrudate of the present invention disposed between a second layer and a third layer; a second layer and a third layer, preferably comprising PET, and an outer layer. A fourth layer such that one of the second and third layers is located between the first and fourth layers; the fourth layer is preferably PP,
Includes coextruded films containing PP copolymers or blends such as PP / Tafmer. This film or sheet is represented as PET / first layer / PET / sealant. Preferably, the film or sheet has a thickness of about 1.5-3.0 mils, especially about 2-3 mils, and more preferably about 2.75 mils.

In a first embodiment, the first layer coextrudate includes a plurality of superposed layers containing a core layer disposed between a first outer layer and a second outer layer. The core layer comprises a polyvinylidene chloride-methyl acrylate copolymer essentially free of EVA and ELO, more preferably 98.8.
Polyvinylidene chloride-methyl acrylate copolymer essentially free of wt% EVA (e.g. Dow 11
9) and 1.2 wt% ELO. The first and second outer layers are the first of a film or sheet that can be formed into a pouch.
The first and second outer layers of the layer are as described. In this example, the first layer coextrudate is preferably 30-40 w
t% of the first outer layer, 40-50 wt% of the core layer, and
Including 20-30 wt% of the second outer layer.

In a second embodiment, the first layer coextrudate comprises a core layer disposed between a pair of first intermediate layers (each first intermediate layer being disposed between the core and the second intermediate layer). , A second intermediate layer (each second intermediate layer is disposed between the first intermediate layer and the outer layer), and a plurality of layers including an outer layer including the first and second outer layers. Here, the first and second intermediate layers and the outer layer are the same as described for the first layer of the film or sheet suitable for forming a pouch, and the core layer is polyvinylidene chloride substantially free of EVA. A methyl acrylate copolymer, preferably a polyvinylidene chloride-methyl acrylate copolymer essentially free of EVA and ELO, more preferably 98.8 wt% EV
Contains polyvinylidene chloride-methyl acrylate copolymer essentially free of A and 1.2 wt% ELO.
In this example, the first layer is preferably the same wt% of the core, first intermediate, second intermediate, first outer and first outer layers as described for the first layer of film or sheet suitable for forming a pouch. Includes two outer layers.

In another embodiment, the first layer is arranged as described above for the second embodiment of the first layer for a film or sheet suitable for forming lidstock. It has a plurality of overlapping layers including a core layer, first and second intermediate layers, and first and second outer layers. In this embodiment, the material of the core layer, and each weight percent of the core layer, the first and second intermediate layers, and the first and second outer layers, is a film or sheet suitable for forming the above-described lidstock. Is the same as that of the second embodiment of the first layer. However, in this embodiment, the first intermediate layer is made of EVA (especially high VA-content EVA, such as Exxon
LD-761; VA content = 28%) and a PP base adhesive (eg Exxon 5610A-2), preferably 30 wt% EVA and 70 wt% PP base adhesive; the second intermediate layer comprises PP ( Example: Fina 3622),
EVA (especially high VA content EVA) and PP base adhesive, preferably 80 wt% PP base adhesive, 10 w
1% outer layer comprising PP, PP base adhesive and white PP concentrate opacifier (eg Chroma P20192A or A).
and preferably 75% by weight of P
P, including 10 wt% PP base adhesive and 15 wt% white PP concentrate opacifier;
P and PP base adhesives, preferably 80 wt% PP and 20 wt% PP base adhesives.

[0047]

EXAMPLES The following examples are given for illustrative purposes only and should not be construed as limiting the invention, and many obvious modifications may be made without departing from the spirit and scope of the invention. Is possible.

FIG. 1 illustrates the barrier properties after retorting of the film of the present invention. Five films were made with the following composition, and the oxygen transmission rate was measured from before the retort to 8 days after the retort. The measurement results are shown in FIG. In FIG. 1, the PVdC component of the film has been standardized to a thickness of 1 mil.

In FIG. 1, the lines plotted by the solid squares represent data for films made from the prior art vinyl chloride-polyvinylidene chloride copolymer (HB Saran). The line plotting the points represented by hollow diamonds is another prior art polyvinylidene chloride methyl acrylate copolymer containing Mg (OH) ₂ and EVA (7.5-7.5).
8 wt% MA; 1.5 wt% Mg (OH) ₂ and 3 wt%
5 shows data for films made from E.g. The line plotting the points represented by the solid black squares is a polyvinylidene chloride methyl acrylate copolymer (7.5 mg) containing Mg (OH) ₂ as a stabilizer.
-8 wt% MA; containing 1.5 wt% Mg (OH) ₂ )
2 shows data for a film of the present invention made from.
The line plotting the points represented by the black diamonds is a polyvinylidene chloride methyl acrylate copolymer (7.5-8 wt% MA; 1 wt% ELO) containing epoxidized linseed oil (ELO) as a stabilizer. )
5 shows data for another film of the present invention made from. The line plotting the points represented by the black squares is
Polyvinylidene chloride methyl acrylate copolymer containing epoxidized linseed oil (ELO) as stabilizer (7.5-8 wt% MA; containing 1.5 wt% ELO)
5 shows data for yet another film of the present invention made from.

FIG. 1 shows that for polyvinylidene chloride-methyl acrylate copolymer films containing EVA and polyvinylidene chloride-vinyl chloride films, there is a significant decrease in gas, especially oxygen barrier properties, after retorting. . In contrast, the film of the present invention retains high gas barrier properties even when subjected to retort conditions.

[0051]

As described above, according to the present invention,
A polymer material having a high gas (particularly oxygen) barrier property and maintaining the barrier property even when subjected to retort treatment is provided.

[0052]

[Brief description of the drawings]

FIG. 1 is a graph showing oxygen permeability as a function of time for various films.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI C08L 27/08 C08L 27:08 // C08L 27:08 C08K 5/15 (72) Inventor John Paul Extine Wisconsin, USA 54956, Nina, Glen Isle Drive 1206 (72) Inventor Mark Edward Nordness 54956, Wisconsin, USA Nina Grob Street 951 (56) References JP 62-267332 (JP, A) JP 6426441 (JP, A) WO 91/3518 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/18 C08L 27/08

Claims (11)

(57) [Claims] 1. Contains an ethylene vinyl acetate plasticizer
A polyvinylidene chloride methyl acrylate copolymer and a stabilizer selected from the group consisting of epoxidized linseed oil, epoxidized soybean oil, magnesium hydroxide, magnesium oxide and tetrasodium pyrophosphate as essential components, A film having a high gas barrier property, and the high barrier property is substantially maintained even after retorting at a high temperature. 2. A method of packaging a food product, comprising packaging the food product in a film package formed from the film of claim 1. 3. A method according to claim 1, further comprising a plurality of superposed layers; the superposed layers including a first layer constituting a core layer disposed between the second layer and the third layer; Item 1. A film comprising the film of Item 1; and wherein the second and third layers include polypropylene. 4. A method comprising: a plurality of superposed layers; the superposed layers including a first layer constituting a core layer disposed between a second layer and a third layer; the first layer comprising: A film, characterized in that the second layer comprises polypropylene, a white polypropylene concentrate opacifier and ethylene vinyl acetate; and the third layer comprises polypropylene and ethylene vinyl acetate. 5. A method comprising: a plurality of superimposed layers; the superposed layers including a core layer disposed between a pair of first intermediate layers; each of the first intermediate layers being a core layer and a second intermediate layer. Each of the second intermediate layers is disposed between one first intermediate layer and one outer layer; the outer layers are a first outer layer and a second outer layer. The first intermediate layer comprises ethylene vinyl acetate; the second intermediate layer comprises a polypropylene base adhesive; the first outer layer is polypropylene, white. A film comprising a polypropylene concentrate opacifier and ethylene vinyl acetate; and a second outer layer thereof comprising polypropylene and ethylene vinyl acetate. 6. A method according to claim 1, further comprising the steps of: providing a plurality of superposed layers; the superposed layers including a core layer disposed between a pair of first intermediate layers; Each of the second intermediate layers is disposed between one first intermediate layer and one outer layer; the outer layers are a first outer layer and a second outer layer. The first intermediate layer comprises ethylene vinyl acetate and a polypropylene base adhesive; and the second intermediate layer comprises a polypropylene base adhesive, polypropylene and ethylene vinyl acetate. The first outer layer comprises polypropylene, a polypropylene base adhesive and a white polypropylene concentrate opacifier; and the second outer layer comprises polypropylene and polypropylene Film which comprises a base resin adhesive. 7. A method comprising: a first layer disposed between a second layer comprising polyethylene terephthalate; and a third layer comprising a polypropylene sealant; The layers include a core layer disposed between a pair of first intermediate layers; each of the first intermediate layers is disposed between the core layer and a second intermediate layer; each of the second intermediate layers is Disposed between one first intermediate layer and one outer layer; the outer layers comprising a first outer layer and a second outer layer; the core layer comprising the film of claim 1; A first intermediate layer comprising ethylene vinyl acetate; a second intermediate layer comprising a polypropylene base adhesive; a first outer layer comprising polypropylene, a white polypropylene concentrate opacifier and ethylene vinyl acetate; Films its second outer layer is characterized by containing a polypropylene and ethylene vinyl acetate. 8. The method according to claim 1, further comprising a plurality of superposed layers; the superposed layers including a first film layer, a second film layer, a third film layer, and a fourth film layer as an outer layer.
The film layer is disposed between the second film layer and the third film layer, each of the second film layer and the third film layer containing polyethylene terephthalate, and the fourth film layer serving as an outer layer.
The film layer includes a polypropylene sealant, and one of the second and third film layers is disposed between the first and fourth film layers; the first film layer includes a second film layer and a fourth film layer. A core layer disposed between the three film layers; the core layer including the film of claim 1; the second layer including polypropylene, a white polypropylene concentrate opacifier and ethylene vinyl acetate; A film characterized in that the three layers contain polypropylene and ethylene vinyl acetate. 9. A method comprising: a plurality of superposed layers; the superposed layers including a first layer, a second layer, a third layer, and a fourth layer as an outer layer, wherein the first layer comprises a second layer; A fourth layer as an outer layer comprising a polypropylene sealant, wherein one of the second and third layers comprises polyethylene terephthalate, wherein the second layer and the third layer each comprise polyethylene terephthalate; A first layer disposed between the first layer and the fourth layer; the first layer being disposed between the core layer and the second intermediate layer, and a core layer disposed between the pair of first intermediate layers. A plurality of layers including a first intermediate layer, a second intermediate layer disposed between the first intermediate layer and the outer layer, and a pair of outer layers forming the first outer layer and the second outer layer. A cored layer comprising the film of claim 1; said first intermediate layer comprising ethylene vinyl acetate; And a second intermediate layer comprising a polypropylene base adhesive; a first outer layer comprising polypropylene, a white polypropylene concentrate opacifier and ethylene vinyl acetate; and a second outer layer comprising polypropylene and ethylene vinyl acetate. Film. 10. A method comprising: a plurality of superposed layers; the superposed layers including a first layer, a second layer, a third layer, and a fourth layer as an outer layer, wherein the first layer comprises a second layer; A fourth layer as an outer layer comprising a polypropylene sealant, wherein one of the second and third layers comprises polyethylene terephthalate, wherein the second layer and the third layer each comprise polyethylene terephthalate; A first layer disposed between the first layer and the fourth layer; the first layer being disposed between the core layer and the second intermediate layer, and a core layer disposed between the pair of first intermediate layers. A plurality of layers including a first intermediate layer, a second intermediate layer disposed between the first intermediate layer and the outer layer, and a pair of outer layers forming the first outer layer and the second outer layer. A core layer comprising the film of claim 1; wherein said first intermediate layer comprises ethylene vinyl acetate and polyp. The second intermediate layer comprises a polypropylene base adhesive, polypropylene, and ethylene vinyl acetate; the first outer layer comprises polypropylene, a polypropylene base adhesive and a white polypropylene concentrate opaque agent; A film, wherein the second outer layer comprises polypropylene and a polypropylene base adhesive. 11. A retort pouch cast from the film of claim 1, wherein the content is filled, and the filled content is cooked and / or sterilized by injecting the filled content into a retort treatment. how to.