JP6790763B2 - Co-extruded non-stretched film for retort, laminated film and packaging - Google Patents

Description

The present invention mainly uses a coextruded non-stretched film capable of retort sterilization that can be suitably used for packaging a gas-substituted deep-drawing package (gas pack), a laminated film capable of retort sterilization and freezing packaging, and these films. It is related to the packaging body produced by.

In recent years, reflecting activities to reduce the amount of waste of food and packaging materials, and the social environment where aging and individualization are advancing, food contents are transferred from the packaging used for distribution to cooking utensils such as pots and frying pans and tableware. There is a demand for a packaging that can be cooked by using the packaging as a cooking utensil or tableware. In addition, the food expiration date has been extended by using inert gas replacement packaging (gas pack) and retort sterilization treatment.
Therefore, if consumers purchase food in such a package, they can carry the purchased product as it is, store it for a long period of time, cook it, use it as a container, and dispose of it as it is after use. This makes it possible to save the trouble of using cooking utensils and tableware separately at home.

However, in the case of conventional general packaging materials, the shape of the packaging cannot be maintained if a gas-packed packaging is prepared and heat-sterilized by retort, etc. due to insufficient heat resistance, etc. The resin melts, and when pulled, the unheat-sealed part (opening trigger part) fuses to be used as a handle when opening, making it impossible to open the package, or during heat sterilization. In addition, the seal strength becomes weak and the package is opened (broken bag, the seal is removed), and other problems occur. Therefore, the retort sterilization treatment cannot be performed, and the only method for extending the expiration date is to enclose the inert gas in an aseptic state, and there is a limit to the extension of the expiration date. In addition, consumers cannot cook retort pouches, and the types of foods to be packaged are limited.

On the other hand, as a packaging material that can withstand cooking such as boil, for example, Patent Documents 1 and 2 disclose a technique for disposing a heat-resistant polybutylene terephthalate resin (PBT) or the like in an outer layer. However, Patent Document 1 describes that the flange of the container becomes too hard when the ratio of the outer layer thickness to the total film thickness exceeds 25%, and Patent Document 2 states that the moldability and strength are inferior when the outer layer thickness is 40 μm or more. In the case of these techniques, it is possible to cook by boiling, but because the packaging material is not strong enough, it cannot stand on its own as a container shape and cannot be used as tableware. In addition, retort cooking is not possible. Specifically, the sealing resin of Patent Document 1 is an ionomer resin, polyethylene, or a copolymer of ethylene and other components, and the heat-sealing layer resin of Patent Document 2 has a melting point of 120 to 135 ° C. Therefore, the resin of these seal layers melts, and the opening trigger portion is fused to make it impossible to open the package, the resin adheres to the contents, or the package is partially opened (breaking bag, seal). Problems such as omission) occur.

In contrast to the above-mentioned disclosed technology, polybutylene terephthalate resin (PBT) has a high crystallization rate and crystallization is likely to proceed due to thickening. Therefore, when the PBT layer is thickened in film forming, it becomes opaque. Is well known, and in the inert gas-replaced deep-squeezed package (gas pack) market, a transparent container in which the contents can be seen is required by a universal concept. Therefore, conventionally, packaging materials for gas packs have been used. The idea of thickening the PBT layer has not been conceived, and the use of other hard transparent resins and film-forming techniques such as alternating multi-layering have been studied.

However, hard and heat-resistant resins are expensive, and it is necessary to upgrade the equipment for alternating multi-layering, so gas pack packaging that can be cooked and can be used as tableware that can be economically popularized in the market is available. Not provided.

Japanese Unexamined Patent Publication No. 6-226930 Japanese Unexamined Patent Publication No. 2002-178470

In view of the above-mentioned background technology, it is an object of the present invention to provide a film for a packaging body which can be sterilized and cooked in the form of a retort pouch or the like, and which can be used as an independent tableware while maintaining the form.

In earnest consideration of the above problems, it has a polypropylene terephthalate resin layer, at least one polyamide resin layer and at least one ethylene-vinyl acetate copolymer saponified layer as an intermediate layer, and an easy peeling layer as an inner layer. The coextruded non-stretched film has a thickness of the polybutylene terephthalate resin layer of 40 μm or more, a ratio of 40% or more to the total thickness, and the main component of the resin constituting the easy peeling layer has a melting point of 150. A co-extruded non-stretched film for retort, which is a polypropylene resin having a temperature of ℃ or higher, a laminated film for a frozen package in which a polyethylene resin film is laminated on the polybutylene terephthalate layer side, and a package using these films. Found to be a solution.

According to the present invention, food can be stored and distributed for a long period of time under low temperature of refrigeration or freezing, and consumers can easily cook and eat food in the purchased form. In particular, since it maintains its shape as a bulky deep-drawn package from low temperature to high temperature and has excellent independence, it can be used for a wide range of foods such as hams and sausages, as well as prepared foods and foods containing juice and soup.
In addition, in vacuum packaging, even baked products, udon noodles, rolled eggs, tofu, etc., whose contents collapse due to shrinkage of the packaging material, are deeply squeezed with an inert gas (gas pack) and retort sterilized at 120 ° C. By doing so, the product life can be extended with a good shape and the amount of waste can be reduced.

It is sectional drawing of the deep drawing package which used the coextruded unstretched film as the bottom material, and combined with the lid material. It is sectional drawing of the deep drawing package which used the laminated film as a bottom material and combined with a lid material. It is an example figure of the load resistance evaluation which put the weight on the deep drawing package. It is an example figure of the upper surface of the packaging body which put together the lid material and the bottom material, heat-sealed the peripheral part, and provided the opening trigger part without heat-sealing one of the four corners.

The coextruded non-stretched film for retort pouch, the laminated film for frozen packaging, and the packaging using these films will be described in detail below. However, the present invention is not limited to the embodiments described below.
The coextruded non-stretched film of the present invention has a polybutylene terephthalate resin layer as an outer layer, at least one polyamide resin layer and at least one ethylene-vinyl acetate copolymer saponified layer as an intermediate layer, and an easy inner layer. It has a peeling layer.

In the present invention, the "outer layer" is a layer located on the outside air side when the coextruded non-stretched film alone is molded into a deep-drawn package, and when a laminated film for a frozen package is produced, a polypropylene resin is used. This is the layer on the side to be laminated with the film. The "inner layer" is a layer that becomes the container side at the time of molding the package, and the "middle layer" is a layer located between the outer layer and the inner layer.
Further, in the present invention, the "main component" means a component constituting 50% by mass or more of the composition, preferably 60% by mass or more, and more preferably 70% by mass or more. The upper limit is not particularly limited, and means that it may be 100% by mass or less.

<Outer layer: Polybutylene terephthalate resin (PBT) layer>
A polybutylene terephthalate homopolymer and / or a polybutylene terephthalate copolymer is used as the outer layer of the coextruded non-stretched film of the present invention. Hereinafter, it may be abbreviated as PBT layer.
The homopolymer is polymerized using terephthalic acid as the dicarboxylic acid component and 1,4-butanediol as the diol component. Examples of the copolymer include those using dodecandioic acid or polytetramethylene glycol as the dicarboxylic acid component and tetramethylene oxide glycol as the diol component.

As the PBT layer resin, a variety having a melting point of about 220 to 230 ° C. and a thermal deformation temperature (0.455 MPa) of about 130 to 150 ° C. is used, which contributes to the heat resistance of the film.
Further, as compared with polyethylene terephthalate resin (PET), which is a typical polyester resin, PBT has a lower melting point, but the thermal deformation temperature is higher than PET, and PBT has excellent heat resistance. For example, when PET is used for the outer layer of the package, the PET layer becomes starch syrup due to the influence of heat and water in a boiled environment, and when the packages come into contact with each other, they are fused to cause a problem. However, a PBT layer is arranged on the outer layer. In the case of a package made of the coextruded non-stretched film of the present invention, the boil treatment can be performed in a good state. Further, the polyester resin has a property that heat resistance, strength and rigidity are increased by stretching, but PBT has a feature that the crystallization rate is faster than PET and excellent heat resistance and rigidity can be obtained without stretching.
The ultimate viscosity (IV) of the PBT layer resin is preferably 1.15 to 1.35 dl / g, more preferably 1.20 to 1.30 dl / g. For the ultimate viscosity (IV), 300 mg of the resin of the sample is dissolved in 30 ml of a solvent (phenol: 1,1,2,2-tetrachloroethane = mass ratio 1: 1), and the sample is dropped using an Ubbelohde type capillary viscometer. Time can be measured and calculated.

The thickness of the PBT layer is set to 40 μm or more, preferably 50 μm or more, and more preferably 60 μm or more, from the viewpoint of heat resistance and strength of the film. With a thickness of 40 μm or more, the deep-drawn package can stand on its own without losing its shape even after heating, and can be used as a substitute for tableware.
The lower limit of the thickness ratio of the PBT layer to the total thickness of the coextruded non-stretched film is 40% or more, preferably 60% or more, and more preferably 70% or more. The upper limit is preferably 95% or less, more preferably 90% or less, and 85% or less.
With 40% or more, the waist as a deep-drawn package becomes sufficient, giving consumers a strong impression of the form and a sense of security when it is displayed in stores as a product, and practically, the dish as it is in the package. It can be used as tableware instead of a container. Further, when the ratio is 95% or less, the layer thickness ratio of the polyamide resin layer of the intermediate layer to the ethylene-vinyl acetate copolymer saponified layer and the easy peeling layer of the inner layer can be increased, so that the oxygen barrier property and the opening property are good. Become.
Since PBT has a high crystallization rate and crystallization is likely to proceed due to thickening, generally, when the PBT layer is thickened in film forming, it tends to become opaque. Therefore, it is desirable to reduce the crystallinity of the PBT layer and make it transparent by examining the film forming conditions.

<Intermediate layer: polyamide resin layer, ethylene-vinyl acetate copolymer saponified layer>
The coextruded stretched film of the present invention has a polyamide resin (PA) layer and an ethylene-vinyl acetate copolymer saponified product (EVOH) layer as intermediate layers.
The PA layer and the EVOH layer have an oxygen gas barrier property, and can impart a function of preventing putrefaction of the contents to the film.
At least one PA layer and one EVOH layer are arranged. It is preferable that both layers are adjacent to each other, and it is more preferable that the PA layer is adjacent to the outer layer side and the EVOH layer is adjacent to the inner layer side thereof. Further, if the PA layers are arranged on both sides of the EVOH layer, such as the PA layer / EVOH layer / PA layer, sufficient interlayer strength can be easily obtained for the PBT layer and the PE layer, and the options for the adhesive resin are widened.

The polyamide resin is not particularly limited, but it is preferable to use a nylon resin (Ny) from the viewpoint of gas barrier property and pinhole resistance. For example, a polymer of condensation units such as 6 nylon, 66 nylon, 69 nylon, 6-66 nylon, 12 nylon, 11 nylon, 610 nylon, 612 nylon, 6I-6T nylon, MXD6 nylon, or two or more of them. Examples thereof include copolymers and even mixtures thereof. Of these, it is preferable to use MXD6 nylon having a high gas barrier property, 6 nylon or 6-66 nylon having a high pinhole resistance.
The lower limit of the thickness of the PA layer is 2 μm or more, preferably 3 μm or more, and more preferably 5 μm or more. The upper limit is 25 μm or less, preferably 20 μm or less, and more preferably 15 μm or less. When it is 2 μm or more, good gas barrier property and pinhole resistance can be easily obtained, and when it is 25 μm or less, good cutability in a deep drawing packaging machine can be easily obtained.

EVOH having an ethylene content of 30 to 60 mol% and a saponification degree of 95% or more is preferable from the viewpoint of moldability and gas barrier property.
The lower limit of the thickness of the EVOH layer is preferably 1 μm or more, and more preferably 2 μm or more. The upper limit is preferably 20 μm or less, more preferably 10 μm or less. When it is 1 μm or more, good oxygen gas barrier property can be easily obtained, and when it is 20 μm or less, deterioration of pinhole resistance can be easily suppressed.

<Intermediate layer: Propylene resin layer>
In the coextruded non-stretched film of the present invention, a polypropylene-based resin layer can be arranged as an intermediate layer from the viewpoint of having both heat resistance and sealing properties. For example, it is desirable to dispose of it at a position adjacent to the easy peeling layer. Examples of the polypropylene-based resin used for the intermediate layer include a propylene homopolymer and / or a propylene-α-olefin copolymer. Homopropylene is preferable from the viewpoint of heat resistance against high temperature sterilization and prevention of whitening.
The thickness of the polypropylene-based resin layer is not particularly limited, but the lower limit is preferably 5 μm or more from the viewpoint of film formation stability and heat resistance, and the upper limit is preferably 20 μm or less from the viewpoint of transparency.

<Intermediate layer: Adhesive resin layer>
In the co-extruded non-stretched film of the present invention, an adhesive resin layer can be appropriately arranged between the outer layer and the intermediate layer and between the inner layer and the intermediate layer from the viewpoint of further increasing the interlayer adhesive strength. For example, between the PBT layer and the PA layer, between the PBT layer and the EVOH layer, between the PA layer and the PP layer, between the EVOH layer and the PP layer, between the PA layer and the easy peeling layer, EVOH. It is preferably disposed between the layer and the easy peeling layer.
The thickness of the adhesive resin layer is not particularly limited, but the lower limit is preferably 3 μm or more from the viewpoint of adhesiveness and interlayer strength, and the upper limit is preferably 8 μm or less from the viewpoint of transparency and economy.

The adhesive resin is not particularly limited as long as the various resin layers constituting each layer can be bonded with the required strength. Preferably, it is a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, and citraconic acid.
In addition, an ester of unsaturated carboxylic acid or an anhydride can be used as the adhesive resin, and methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butyl methacrylate, vinyl acetate, etc. can be used as derivatives. Glysidyl acrylate, glycidyl methacrylate, acrylamide, methacrylic acid, sodium acrylate and the like can be used.

<Inner layer: Easy peeling layer>
The coextruded non-stretched film of the present invention has an easy peeling layer in the inner layer.
The main component of the resin constituting the easy peeling layer is a polypropylene resin having a melting point of 150 ° C. or higher. As a result, heat resistance can be imparted to the film, the shape stability and independence of the bulky deep-drawn package can be maintained even during heat treatment such as retort pouching, and food safety is improved because resin melting does not occur. I can keep it. Furthermore, when the coextruded non-stretched film of the present invention is used as a deep-drawn bottom material, the molding temperature can be set to a high temperature, so that ribs having sharp angles, fineness, and a high aspect ratio can be formed on the bottom surface and side surfaces, and thus the package. It is effective in improving the strength and food preservation of food.
Examples of the polypropylene-based resin having a melting point of 150 ° C. or higher include propylene homopolymers and / or propylene-based block copolymers, and propylene homopolymers are preferable from the viewpoint of film-forming property and transparency.

Although a polypropylene resin having a melting point of less than 150 ° C. can be blended in the easy peeling layer, 50% by mass or more of the main component of the resin constituting the easy peeling layer, that is, a polypropylene resin having a melting point of 150 ° C. or higher is contained. It is necessary.
In order to impart the easy peeling function, it is preferable to mix one or more kinds of polypropylene-based resin having a melting point of 150 ° C. or higher and an incompatible resin.

As the resin to be mixed in the easy peeling layer, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ionomer (IO), ethylene-acrylic acid copolymer (for example, from the viewpoint of easy peeling function, Polyethylene-based resins such as EAA) and ethylene-methyl methacrylate copolymer (EMMA) are preferred. Among them, LDPE and LLDPE are preferable, and heat-resistant LLDPE is preferable from the viewpoint of heat treatment resistance.
The heat-resistant LLDPE is produced by a polymerization method using a single-site catalyst, and has a density of 920 kg / m ³ or more, more preferably 930 kg / m ³ or more. Further, the melting point is preferably 120 ° C. or higher.

Further, when a thermoplastic elastomer (TPO) is mixed with the easy peeling layer, the adhesiveness (tackiness) to the adherend is likely to increase, and the polypropylene resin having a melting point of 150 ° C. or higher, which is relatively hard, is used as the main component. The heat sealability of the easy peeling layer can be improved.
Examples of the thermoplastic elastomer mixed in the easy peeling layer include olefin-based elastomers, styrene-based elastomers, and urethane-based elastomers. Of these, a styrene-based elastomer is preferable because it increases the adhesiveness (tackiness) of the easy-peel layer to the adherend to improve the heat-sealing property and also easily obtains the effect of preventing fusion of the opening opening portion.

Examples of the thermoplastic styrene-based elastomer include styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene-ethylene-butylene copolymer / styrene (SEBS), and styrene / ethylene-propylene copolymer. -AB-A type block polymer such as styrene (SEPS); styrene-butadiene (SB), styrene-isoprene (SI), styrene-ethylene-butylene copolymer (SEB), styrene-ethylene-propylene copolymer AB type block polymer such as (SEP); Styrene-based random copolymer such as styrene / butadiene rubber (SBR); ABC type such as styrene / ethylene-butylene copolymer / olefin crystal (SEBC) Styrene / olefin crystal block polymer; CBC type olefin crystal block polymer such as olefin crystal (CEBC); olefin elastomer such as ethylene / α olefin, ethylene / propylene / α olefin, propylene / α olefin , Furthermore, these hydrogenated products and the like can be mentioned. Of these, SBS, SEPS, SEBS, and SBBS are preferable from the viewpoint of elastic modulus and heat resistance at room temperature (23 ° C.). In particular, SBS is preferable in terms of heat-sealing property and fusion prevention property of the opening trigger portion.

Examples of the styrene-based elastomer (hydrogenated derivative of vinyl aromatic hydrocarbon-conjugated diene block copolymer) as described above include "KratonG" (registered trademark) manufactured by Clayton Polymers and "Septon" (registered) manufactured by Claret. Trademark), "Hybler" (registered trademark), Asahi Kasei "Tough Tech" (registered trademark), JSR "Dynaron" (registered trademark), and styrene block and isobutylene block obtained by cationic polymerization of Kaneka. Examples include "SIBSTAR" (registered trademark) composed of.
Further, examples of the resin composition of the propylene-based resin and the styrene-based elastomer include "Zeras" (registered trademark) manufactured by Mitsubishi Chemical Corporation.

The composition of the resin constituting the easy peeling layer is 150 ° C. or higher, and the mass composition ratio of polypropylene resin: polyethylene resin: thermoplastic elastomer (total resin 100% by mass) is (50 to 100) :( 0 to 50). ): (0 to 20) is preferable, (60 to 90) :( 10 to 40): (1 to 10) is more preferable, and (60 to 80) :( 20 to 40) :( 1 to 5) is further preferable. preferable.
When the polyethylene resin is in the above composition ratio range, the easy peeling property and the heat seal property are good, and when the thermoplastic elastomer is in the above composition ratio range, the heat seal property can be improved and the fusion of the opening opening portion can be prevented.

The lower limit of the thickness of the easy peeling layer is preferably 2 μm or more, more preferably 3 μm or more, still more preferably 4 μm or more, from the viewpoint of film forming property and peeling appearance. The upper limit is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less.
When it is 2 μm or more, stable film-forming property can be obtained, and when it is 15 μm or less, fluffing and film residue can be less likely to occur at the time of peeling, and a good peeled appearance can be obtained.

<Whole co-extruded non-stretched film>
The total thickness of the coextruded non-stretched film of the present invention is preferably 100 μm or more and less than 500 μm. The lower limit is more preferably 150 μm or more, still more preferably 200 μm or more, from the viewpoint of the waist as a deep-drawn package. The upper limit is more preferably 450 μm or less, still more preferably 400 μm or less, from the viewpoint of reducing the amount of packaging material.

The layer structure of the coextruded non-stretched film of the present invention is particularly high as long as it has a PBT layer as an outer layer, at least one PA layer and one EVOH layer as an intermediate layer, and an easy peeling layer as an inner layer. Not limited.
For example, the abbreviations are used to indicate the PBT layer (A), PA layer (B), EVOH layer (C), PP layer (D), easy peeling layer (E), and adhesive resin layer (F). In the case, the following layer structure can be formed.
(1) A / F / B / C / F / E
(2) A / F / B / C / F / D / E
(3) A / F / C / B / F / E
(4) A / F / C / B / F / D / E
(5) A / F / B / C / B / F / E
(6) A / F / B / C / B / F / D / E
(7) A / F / B / F / C / F / D / E

Of the above, the layer structure of (2), (4) or (6) is preferable from the viewpoint of combining deep drawing workability, heat resistance, rigidity, pinhole resistance, transparency, and gloss.

The coextruded non-stretched film of the present invention can be produced by using a known method. For example, a co-extrusion inflation method, a co-extrusion T-die method, or the like can be used, and it is particularly preferable to use the co-extrusion T-die method.

The peel strength (easy peel strength, 180-degree peel) when the coextruded non-stretched film of the present invention is heat-sealed with an adherend is such that cohesive failure occurs during peeling and the peeled surface does not fluff. Good.
For example, an adherend (film) made of a propylene resin is superposed on the easy-peel layer surface of the film of the present invention, heat-sealed under the setting conditions of 180 ° C. for 2 seconds, and the peel strength at 23 ° C. after allowing to cool. However, the lower limit is preferably 2.0 N / 15 mm width or more, more preferably 3.0 N / 15 mm width or more, and further preferably 4.0 N / 15 mm width. The upper limit is preferably 12.0 N / 15 mm width or less, more preferably 10.0 N / 15 mm width or less, and further preferably 8.0 N / 15 mm width or less.
When the peeling strength is within the above range, it is easy to have both easy peeling property that can be easily opened by hand and sufficient sealing property by heat sealing. In particular, regarding the sealing property, it is useful in that even if steam derived from the contents is generated by the retort heat treatment and the pressure inside the package increases, it is difficult for a part of the package to be opened (bag rupture, seal removal). is there.

When the coextruded non-stretched film of the present invention is heat-sealed with an adherend, if a part (end) thereof is not heat-sealed, the co-extruded non-stretched film is heat-sealed even after retort treatment at 121 ° C. for 30 minutes. It is preferable that the non-extruded portion does not heat-fuse to the adherend. As a result, a package having an opening trigger that does not heat-seal a part is produced, and even if the retort treatment is performed, the user grabs the opening trigger with his / her fingers and pulls the film to peel off the heat-sealed package. It becomes easier to open the package.

<Laminated film>
The laminated film in which a polyethylene resin (PE) film is laminated on the PBT layer side of the coextruded non-stretched film of the present invention can be suitably used for frozen packaging applications.
Examples of the PE film include known non-stretched films made of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).
The thickness of the PE film is preferably 10 μm or more and 200 μm or less, and more preferably 20 μm or more and 100 μm or less. Further, it is desirable that the thickness of the PE film is appropriately selected in consideration of the thickness of the co-extruded non-stretched film. For example, the thickness ratio of the co-extruded non-stretched film: PE film is preferably (10 to 1): 1. , (5-3): 1 is more preferable.
By laminating such a PE film, it is possible to effectively impart impact resistance and pinhole resistance under ice temperature or freezing.

<Deep drawing package>
The coextruded non-stretched film and the laminated film of the present invention can be suitably used as the bottom material of the deep-drawn package. In particular, when used in a gas-replacement deep-throttle package (gas pack) in which an inert gas is injected, which can prolong the expiration date of food, the coextruded non-stretched film and laminated film of the present invention can be used from low temperature to high temperature and have a shape. It is possible to effectively utilize the characteristics such as excellent retention and independence, and it is possible to carry out from the manufacture and distribution of food to the use as cooking utensils and tableware simply and efficiently.
A deeply drawn package made of only a coextruded non-stretched film can be applied from refrigeration (chilled) to retort, and a deeply drawn package made of a laminated film can be applied from frozen to retort.

Deep drawing of the coextruded non-stretched film and laminated film of the present invention can be carried out by known methods and conditions.
Further, when the coextruded non-stretched film of the present invention is used as a deep-drawn bottom material, the molding temperature can be set to a high temperature, so that ribs having an acute angle, fineness, and a high aspect ratio can be formed on the bottom surface and side surfaces. The formation of ribs is effective in improving the strength of the package and the food preservation.

Further, as the heat sealing condition between the lid material and the bottom material, general conditions such as a temperature of 170 to 190 ° C. and a time of 1 second to 4 seconds can be adopted. Since the outer layer of the coextruded non-stretched film of the present invention is composed of a PBT layer having high heat resistance, in the heat sealing step, when the film is separated from the rubber packing of the sealing portion, the film surface is not roughened and the package body. There is no deterioration in appearance such as gloss.

The lid material is not particularly limited as long as it has an easy peeling property. For example, a lid material obtained by dry-laminating a stretched polypropylene resin film (OPP), a transparent vapor-deposited polyethylene terephthalate film, and a linear low-density polyethylene (LLDPE) film, a stretched polyethylene terephthalate (OPET) film, and a seal containing EVOH and Ny. A laminate obtained by dry-laminating a coextruded film as a layer can be mentioned.
I.

Hereinafter, examples of the present invention will be shown, but the present invention is not limited thereto.
<Preparation of coextruded non-stretched film>
The film having the layer structure shown in each example was produced by a coextrusion method. The layer structure is described in the order from the outer layer to the inner layer. The components of each layer are shown using the following abbreviations.

The thermal deformation temperature of the resin is a measured value at ASTM D648 (0.455 MPa).
The ultimate viscosity (IV) of the resin is a value measured according to JIS K 7367-1.
The resin density is a value measured according to JIS K 6922-1.
The melting point of the resin is a value measured according to JIS K 7121-1987.

(Components of each layer)
PBT; polybutylene terephthalate homopolymer (thermal deformation temperature 136 ° C.) (IV1.26 dl / g unit)
-PET; Polyethylene terephthalate homopolymer (thermal deformation temperature 68 ° C.) (IV0.80dl / g)

-PA; 6-66 copolymerized nylon (nylon 66 ratio 15%)
-EVOH; Ethylene-vinyl acetate copolymer saponified product (32 mol% ethylene)
-Adhesion: Unsaturated carboxylic acid-modified polypropylene-based adhesive resin

EP1; Composition of propylene homopolymer (melting point 165 ° C.), SBS-based elastomer, and linear low-density polyethylene (melting point 130 ° C.), composition mass ratio 66: 4:30
EP2; composition of propylene homopolymer (melting point 165 ° C.) and high-density polyethylene (melting point 130 ° C.), composition mass ratio 70:30
EP3; a mixture of linear low-density polyethylene (melting point 125 ° C) and polybutene (melting point 125 ° C), composition weight ratio 60:40
EP4; composition of propylene-ethylene random copolymer (melting point 125 ° C.) and low-density polyethylene (melting point 112 ° C.), composition mass ratio 60:40

<Manufacturing of laminated film>
The following polyethylene resin non-stretched film was laminated on the surface side of the PBT layer or PET layer of the coextruded non-stretched film by a dry laminating method. For the dry laminate, a two-component mixed polyurethane adhesive resin of a polyester-based polyol and an isocyanate compound was used.
・ LL1: Linear low density polyethylene resin unstretched film 25 μm thickness ・ LL2: Linear low density polyethylene resin unstretched film 50 μm thickness ・ LL3: Linear low density polyethylene resin unstretched film 80 μm thickness

<Making a deep-drawn package>
Using a deep-drawing packaging machine (FV6300 manufactured by Omori Kikai Kogyo Co., Ltd.), a co-extruded non-stretched film or laminated film produced in each example as a bottom material film under the conditions of a molding heating temperature of 140 ° C. and a molding time of 1.5 seconds Using it, it is deeply drawn into a substantially rectangular shape with a length of 130 cm, a width of 70 cm, a drawing depth of 30 cm, and a flange width of about 6 mm, and a sliced ham (weight 300 g) is accommodated and combined with a lid film at 180 ° C. for 2 seconds. A deeply drawn package was prepared by heat sealing under the conditions.

The following films are used as the lid film.
-OPP: Biaxially stretched polypropylene film (30 μm thickness)
-Transparent vapor deposition PET: VM-PET manufactured by Toyo Melalizing (12 μm thickness)
-CPP: Unstretched polypropylene film (40 μm thickness)
A laminated film having the following structure was prepared and used by the dry laminating method. "//" represents the lamination by the dry laminating method.
OPP // Transparent vapor deposition PET // CPP

<Evaluation method>
The following evaluations were made and the results are shown in Table 1.
(Peeling strength)
A lid film is placed on the easy-peel layer surface of the film prepared in each example, heat-sealed under the setting conditions of 180 ° C. for 2 seconds, and the peel strength (N / 15 mm width) at 23 ° C. after cooling is determined by JIS Z 0239. : Measured according to 1995, and the easy peelability was evaluated.

(Retort non-fusing property)
A lid film is placed on the easy-peel layer surface of the film created in each example, heat-sealed under the setting conditions of 180 ° C for 2 seconds, and a strip piece is placed, including a 10 mm long non-heat-sealed part (non-heat-sealed part). Prepare and retort at 121 ° C for 30 minutes to observe the non-heat-sealed part. The case of heat-sealing is marked with "x", the case of no heat-sealing is marked with "○", and the opening trigger part (non-heat-sealed part) is designated. The provided package was evaluated as an index of non-fusing property when it was prepared and retorted.

(Load resistance)
The deeply squeezed package using the film produced in each example was placed on a horizontal and flat table with the bottom surface grounded, and as shown in FIG. 3, the entire top surface of the package was covered with 10 Pa, 20 Pa, 30 Pa, 40 Pa, 50 Pa. Each pressure of 60 Pa was applied, and the deformation of the bottom surface of the package was observed.
When the bottom surface is deformed and the central part floats away from the ground surface, it is marked with "x", and when the bottom center part does not float and the deep drawing shape is maintained, it is marked with "○", and it is self-supporting for use as a gas pack and tableware substitute. , Evaluated as an index of robustness.

(Retort resistance)
The deep-drawn package using the film produced in each example was treated with boiling water for 30 minutes under the conditions of 90 ° C. and 100 ° C. under atmospheric pressure and 110 ° C. and 120 ° C. under pressure.
“○” indicates that the shape of the package can be maintained, “△” indicates that the shape of the package does not show any significant deformation, but the surface of the bottom material film has an uneven resin flow appearance, and the package is large. "× 1" when deformed, "x2" when partial peeling of the heat seal part (breaking bag, missing seal) occurs, when both large deformation and partial peeling of the heat seal part occur Was set to "x", and the availability of retort was evaluated.

(Freezing resistance)
Twenty deep-drawn packages using the films produced in each example were stored frozen at -20 ° C for 24 hours, and dropped onto the concrete floor from a height of 0.5 m in a horizontal position with the bottom facing downward. I let you.
The number of packages with cracks and cracks in the bottom material (per 20 deep-drawn packages) was measured and evaluated as an index of whether or not they can withstand freezing storage and transportation. The number is preferably 5 or less.

Tables 1 and 2 show the layer structures of Examples and Comparative Examples, and the evaluation results.
The lower numerical values of each layer in Tables 1 and 2 are the thickness (μm), the “total thickness” is the total thickness (μm) of the coextruded non-stretched film, and the “outer layer thickness ratio” is the ratio (%) of the outer layer thickness to the total thickness. .. In addition, "-" indicates that the layer does not exist.

According to the present invention, food can be stored and distributed for a long period of time under low temperature of refrigeration or freezing by performing retort sterilization after replacing the food with an inert gas, and consumers can heat boil, retort, etc. You will be able to cook and eat. In particular, since it maintains its shape as a bulky deep-squeezed package from low temperature to high temperature and has excellent independence, it can be used for a wide range of foods such as ham and sausage, as well as prepared foods and foods containing juice and soup.
In addition, in vacuum packaging, even baked products, udon noodles, rolled eggs, tofu, etc., whose contents collapse due to shrinkage of the packaging material, are aesthetically pleasing in shape by the inert gas replacement deep squeezing packaging (gas pack) and retort sterilization treatment. The life can be extended and the amount of waste can be reduced.

1; Co-extruded non-stretched film 2; Polyethylene resin film 3; Laminated film 4; Lid material 5; Heat-sealed part 6; Non-heat-sealed part, opening trigger part 10; Deep-drawing package 20; Weight

Claims (10)

It has a polybutylene terephthalate resin layer on the outer layer,
The intermediate layer has at least one polyamide resin layer and at least one ethylene-vinyl acetate copolymer saponified layer.
A coextruded non-stretched film having an easy peeling layer on the inner layer.
The thickness of the polybutylene terephthalate resin layer is 40μm or more, the ratio of the total thickness is 40% or more, and the main component of the resin constituting the easy-peel layer is a melting point of 0.99 ° C. or more polypropylene-based resin, wherein Heat seal the adherend composed of the easy peeling layer and polypropylene resin, and part of it is used as the opening trigger without heat sealing, and the opening trigger does not fuse even after retorting at 121 ° C for 30 minutes. A co-extruded non-stretched film for retort characterized by. The coextruded non-stretched film for retort pouch according to claim 1, wherein the easy peeling layer contains an ethylene resin and a thermoplastic elastomer. The coextruded non-stretched film for retort pouch according to claim 1 or 2, wherein the ratio of the thickness of the polybutylene terephthalate resin layer to the total thickness is 60% or more and 95% or less. Claimed that the peel strength at 23 ° C. after cooling by heat-sealing with an adherend composed of polypropylene resin under the condition of 180 ° C. for 2 seconds is 2.0 N / 15 mm width or more and 12.0 N / 15 mm width or less. Item 2. The coextruded non-stretched film for retort according to any one of Items 1 to 3. A laminated film for a frozen package in which a polyethylene resin film is laminated on the polybutylene terephthalate resin layer side of the coextruded non-stretched film for retort according to any one of claims 1 to 4 . It has a polybutylene terephthalate resin layer on the outer layer,
The intermediate layer has at least one polyamide resin layer and at least one ethylene-vinyl acetate copolymer saponified layer.
It has an easy peeling layer on the inner layer,
The thickness of the polybutylene terephthalate resin layer is 40 μm or more, the ratio to the total thickness is 40% or more, and
The main component of the resin constituting the easy peeling layer is a retort coextruded non-stretched film which is a polypropylene resin having a melting point of 150 ° C. or higher.
A laminated film for a frozen package in which a polyethylene resin film is laminated on the polybutylene terephthalate resin layer side. A lid material or a deeply drawn bottom material using the coextruded non-stretched film for retort pouch according to any one of claims 1 to 4 or the laminated film for a frozen package according to claim 5 or 6. A packaging body comprising the lid material or deep-drawn bottom material according to claim 7 and a polypropylene-based resin adherend. A gas-replaced deep-drawn package using the lid material or the deep-drawn bottom material according to claim 7. A freezing package using the laminated film for a freezing package according to claim 5 or 6.

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