JPH04131237A - Multilayer packing body - Google Patents

Abstract

PURPOSE:To enhance gas barrier properties by constituting a packing body of an outer resin layer having specific vapor permeability, a layer consisting of an ethylene/ vinyl alcohol copolymer resin containing an ethylene monomer unit, a polyamide resin and a layer of one or more kind of a water soluble or alcohol-soluble metal compound and an inner resin layer having specific vapor permeability. CONSTITUTION:A packing body consists of an outer resin layer A having vapor permeability of 40g/m<2> day or more, a layer B of a composition consisting of 50-97wt.% of an ethylene/vinyl alcohol copolymer resin containing 20-65mol% of an ethylene monomer unit, 45-3wt.% of a polyamide resin and 0.005-5wt.% of one or more kind of a water-soluble or alcohol-soluble metal compound and an inner resin layer (C) having vapor permeability of 20g/m<2> day or less. The outer layer A is composed of one or more kind resin selected from polyamide, polyester and polycarbonate. The metal compound of the intermediate layer B is an alkali metal compound, alkaline earth metal compound and compounds of boron, silicon, iron, aluminum, phosphorus and zinc. Further, a transparent inorg. film is provided to the inner surface of both surfaces of the intermediate layer B. By this method, the remaining of whitening at the time of the contact with water can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention A. relates to a multilayer structure and a multilayer packaging body that have excellent storage stability for food products due to their high gas barrier properties.
In particular, the present invention relates to a packaging material for retort sterilization that is unprecedented in that it has both high gas barrier properties and excellent transparency.

B,lLL! 1. Transparent plastic packaging materials, especially film packaging materials, are widely used for retort or boil sterilized foods due to their major characteristics such as being lightweight, being able to be heated in microwave ovens, etc., and being able to see the contents. ing.

However, plastic films have poor gas barrier properties.
In particular, it is currently used only for limited purposes due to its lack of oxygen gas barrier properties.

Ethylene-vinyl alcohol copolymer resin (hereinafter referred to as EV
It is sometimes abbreviated as OH. ) is a thermoplastic resin with the highest gas barrier properties at present, but when applied to retort films, EV
Water absorption in the OH layer leaves a whitish tinge after retort treatment, and furthermore, there are problems in that poor appearance such as delamination occurs.

On the other hand, JP-A-1-253442 uses a resin blended with EVOH and polyamide resin as an intermediate layer,
There is a description of a film that uses resin with high moisture permeability for the outer layer material and 11 resin, which has lower moisture permeability than the outer layer material, for the inner layer material and has excellent retortable transparency and gas barrier properties, but it contains metal compounds. There is no description of making the EVOH and PA
Although there is a description of adding a water-soluble metal salt etc. to the system, the purpose is different, and therefore the composition and purpose of use are different from the present invention.

C1 describes practical problems in the multilayer film described in JP-A-1-253442 9 For example, P A + s −
/ Unstretched layer of EV OH and PA Brelleno, s, /
PP. The multilayer film of , whitens immediately after retorting, but becomes completely transparent in a short period of time. This is as described in the above patent.

However, if water droplets adhere to the surface of the transparent multilayer film for a long time after retorting, the film will turn white.
Afterwards, even if the water droplets are removed, the whiteness remains (hereinafter referred to as "residual whitening").
Although rewhitening itself does not have a large r:IN, residual rewhitening is a problem in terms of appearance. In actual use, it was predicted that re-whitening or remaining re-whitening would occur due to water droplets adhering to the product from rain and dew condensation on display shelves at retail stores, and there were restrictions such as the use of double packaging.

However, in the above configuration, if the intermediate layer was stretched on two wheels, re-whitening would occur, but the transparency would be restored by removing the adhering water, and no residual re-whitening could be seen, so this system could be used. . However, there are many uses for films that are not biaxially stretched, such as coextruded films, and there has been a strong demand for a solution to this problem.

D. The present inventors closely observed the re-whitening and residual re-whitening phenomenon and studied methods for improving this phenomenon. As a result, we have found an extremely useful result in that when a metal compound is added to the intermediate layer (B), residual re-whitening is completely eliminated.

Although the state of re-whitening and the residual phenomenon of re-whitening, the mechanism of occurrence, and the mechanism of improvement are not fully clear, a metal compound that has a strong interaction with EVOH5 or PA was added.
In the presence of water, E
It is considered that it may have the effect of a kind of compatibilizer for VOH and PA.

Ethylene-vinyl alcohol copolymer (EVOH), which is one of the resins forming the intermediate layer (B), can be any copolymer of ethylene and vinyl acetate as long as it is a hydrolyzed vinyl acetate unit. However, those with an ethylene unit content of 20 are particularly suitable for the purpose of the present invention.
~65 mol%, preferably 20-50 mol%, especially 2
7 to 45 mol%, the degree of saponification of vinyl acetate units is 96% or more, especially 99% or more, and the melt index (190°C, 2160g) value is 02 to 6.
A range of 0 g/10 minutes is exemplified. Further, the EVOH referred to in the present invention may be modified with a copolymerizable monomer in a range of 5 mol% or less, and such modified monomers include propylene, 1-butene, 1-hexene, 4-methyl-1pentene, acrylic acid ester, methacrylate ester,
Maleic acid, fumaric acid, itaconic acid, higher fatty acid vinyl esters, alkyl vinyl ethers, N-(2-dimethylaminoethyl)methacrylamides or their quaternized products, N-vinylpyrrolidone, N,N-butoxymethylacrylamide, vinyl trichloride. Examples include methoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane.

In addition, polyamide-based Its (PA) which is one of the resins forming the intermediate layer (B) includes polycapramide (nylon-6), poly-ω-aminoheptane M (nylon-7), poly-ω-aminononane acid (nylon-9),
Polyundecaneamide (nylon-11), polylauryllactam (nylon-12), polyethylenediamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon 4-6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene dodecamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), Polydecamethylene adipamide (nylon-10,8) or caprolactam/lauryllactam copolymer (nylon-6/
12), caprolactam/ω-aminononanoic acid copolymer (nylon-6/9), caprolactam/hexamethylene diammonium adipate copolymer (nylon-6/9),
6.6), lauryl lactam/hexamethylene diammonium adipate copolymer (nylon-12/6.6)
, hexamethylene diammonium adipate/hexamethylene diammonium sepagate copolymer (nylon-
6,676,10), ethylene diammonium adipate/hexamethylene diammonium adipate copolymer (nylon-2,6/6.6), caprolactam/hexamethylene diammonium adipate/hexamethylene diammonium sebacate copolymer ( Nylon-6/6
．． 6/6.10), polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, hexamethylene isophthalamide/terephthalamide copolymer, and the like. Those PAs modified with aromatic amines such as methylbenzylamine and metaxylylene diamine are also preferred, and metaxylylene diammonium adipate is also preferred.

These PAs can be used alone or in a mixture of two or more.

Among these PAs, the most suitable for the present invention is a caprolactam/lauryllactam copolymer, that is, one containing nylon-6/12 as a main component. The composition of the 6th component and the 12th component in nylon-6/12 is not particularly limited, but it is preferred that the 12th component is 5 to 60% by weight, more preferably 5 to 50% by weight.

Moreover, its relative viscosity is 20 to 40, more preferably 24
~39. is within the range of

Polyether diamines and dicarboxylic acid # (dimer acid, etc.) may be added during condensation polymerization of these PAs, especially nylon-6/12, to form a polyamide having polyether bonds in the polymer chain. Sometimes, NH3
It is also preferred to reduce the amount of carboxyl end groups in the polyamide by adding monoamines such as hexamethylene diamine, aliphatic amines such as lauryl amine, or aromatic amines such as metaxylylene diamine. In this case, it is preferable that the amine group has an equivalent of 5XlO-' equivalent/g or more and the carboxyl terminal group has an equivalent of 3XlO-' equivalent of 7g or less.

Furthermore, the metals that are components of the metal compound added to the intermediate layer (B) include alkali metals, alkaline earth metals,
Examples include boron, silicon, aluminum, iron, zinc, and phosphorus. The form of the compound to be added is not limited, but water-soluble or alcohol-soluble compounds are preferred. For example, salts such as chlorides, carbonates, hydroxides, sulfides, acetates, metal alkoxides, etc. , silane coupling agents.

Among these, preferred are chlorides, nitrates, hydroxides, metal alcoholades, and metal alkoxides.

More specifically, lithium chloride, lithium hydroxide, sodium chloride, sodium hydroxide, potassium chloride, potassium hydroxide, calcium chloride, calcium nitrate, aluminum nitrate, ferric chloride, zinc chloride, sodium borate, tetramethoxy Examples include silane, tetraethoxysilane, triethoxyphenylsilane, triethoxyborane, and titanium tetraiso-10 oxide.

The composition ratio of EVOH, PA, and metal forming the intermediate layer (B) is 50 to 97% by weight: 45 to 3% by weight: 0.005
~5% by weight, preferably 65-85% by weight: 15~
35% by weight: 0.01 to 2% by weight. If the PA component is low, defects in appearance such as ripples and patterns tend to appear when a multilayer package is subjected to retort treatment. If the metal content is too low, re-whitening will remain, whereas if it is too high, it will cause gel formation during molding, coloration of the film, and decrease in strength, which is undesirable.

In addition, the intermediate layer CB) may contain other polymers, antioxidants, ultraviolet absorbers,
Plasticizers, antistatic agents, lubricants, colorants, fillers, etc. can also be added. Examples of other polymers include polypropylene resins, polyester resins, polystyrene resins, polyvinylidene chloride resins with a polyvinyl chloride side and an acrylic side, and polyurethane resins.

Furthermore, an ethylenically unsaturated monomer (e.g.,
It is also possible to impart flexibility to the laminated ellipsoid by blending olefins such as ethylene and propylene), copolymers, or saponified products thereof. Further, specific examples of additives other than polymers include the following.

Stabilizers such as calcium nistearate, hydrotalcites, metal salts, etc.

Antioxidant = 2.5-di-t-butylhydroquinone,
2.6-di-t-butyl-p-cresol, 4.4=thiobis-(6-t-butylphenol), 2.2'-methylene-bis-(4-methyl-6-,t-butylphenol), octadecyl -3-(3°, 5°-di-monobutyl-4"-hydroxyphenyl)propionate, 4,
4'-thiobis=(6-t-butylphenol), etc.

Ultraviolet absorber: Ethyl-2-cyano-3,3'-diphenylacrylate, 2-(2'-hydroxy-5methylphenyl)benzotriazole, 2-(2'hydroxy-3'-t-butyl-5-methylphenyl) )-5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, etc.

Plasticizer: dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester, etc.

Antistatic agents: pentaerythritol monostearate, sorbitan monopalmitate)-4iE oxidized oleic acid, polyethylene oxide, carbon wax, etc.

Lubricants: ethylene bisstearamide, butyl stearate, etc.

Colorant dicarbon black - phthalocyanine, quinacridone, indoline, azo pigment, titanium oxide, red iron oxide, etc.

Fillers Nigellas fiber, asbestos, mica, sericite, talc, glass flakes, ballastonite calcium silicate, aluminum silicate, montmorillonite, etc.

In particular, a filler selected from mica, sericite, talc and glass flakes, montmorillonite 5 to 60% by weight and the above composition (composition with EVOH and PA etc.)9
When a composition containing 5 to 40% by weight is used as layer (B), it is preferred because the gas barrier properties are improved, and this is mainly applicable to containers such as cups and trays.

Among the above-mentioned inorganic fillers, water-swellable phyllosilicates such as montmorillonite can be kneaded by the usual melt blending method, but it is more preferable to mix them using the method shown below, as the effect can be achieved with a small amount of filling. .

Colloidal montmorillonite dispersion using water as a dispersion medium, alcohol such as methyl alcohol, n-10 panol or isopropyl alcohol, water and EVOH.
After adding and heating and stirring to dissolve EVOH, the usual method,
That is, a method can be applied in which the solution is cooled and solidified, then crushed, dried, and pelletized. Alternatively, montmorillonite may be added to an EVOH solution heated and dissolved in the above-mentioned alcohol-water mixed solvent, etc., and the above method may be applied, or the EVOH solution and water or the above-mentioned alcohol-water mixed solvent may be used. may be mixed with a colloidal montmorillonite dispersion forming a sol as a dispersion medium, and the above method may be applied, or an EVOHffi composition in which a desired amount of montmorillonite is uniformly dispersed can be obtained. An EVOH film containing a high concentration of montmorillonite may be prepared by the method described above and used to obtain the final desired concentration. Alternatively, a vented kneading extruder may be used. It is also possible to apply a method in which an aqueous sol of montmorillonite is dropped into EVOH which is melted at a temperature higher than its melting point and then kneaded.

The blending method for obtaining the composition forming the intermediate layer (B) includes melt extrusion using a single or twin screw extruder (same direction or different directions), intensive mixer, continuous intensive mixer, etc., followed by cooling. A method of pelletizing is used.

The composition obtained in this way is melt-molded and then formed into a sheet.
It is made into a film and used as the intermediate layer (B).

The molding method is not particularly limited, but a conventional method can be used. It is also preferable to form a film or sheet made of a composition of EVOH and PA and then hold it in a solution containing a metal compound so that the metal compound is included in the film or sheet. Biaxial stretching (uniaxial stretching or two-wheel stretching) is also used as rotation.

In the multilayer packaging of the present invention, the middle layer (B) is a gas barrier layer.
It plays the role of a material, and its thickness in particular directly affects barrier performance. The thickness of the intermediate layer (B) is lO~
Range of 250μ 1 Usually selected from the range of 15 to 100μ.

An inorganic film can also be laminated on the intermediate layer (B), if necessary. Here, the inorganic film is preferably a transparent inorganic film. In particular, a 5illide-free film or a nitride film is preferable because of its cost.
Desirable in terms of film strength, etc. For example, aluminum oxide (^108), silicon oxide (Sin, l II, boron oxide (BO0 or less, approximately 111.11 zirconium oxides, etc.)
Examples include titanium oxides, magnesium oxides, aluminum nitrides, and silicon nitrides. In addition, fluoride,
Examples include alkali or alkaline earth oxides, and multiple compounds thereof.

These inorganic films are typically laminated by a vapor deposition method, and may be laminated on only one side of the intermediate layer (B), or on both sides. If laminated only on one side, it is especially suitable for retorts. In this case, it is preferable to provide it on the inside of the intermediate layer (B) (on the side of the contents to be filled in the package).Also, a thin inorganic film is sufficient, but its thickness is 100λ to 500, preferably 200 to 500. There are 400 people.

The moisture permeability of the outer layer (A) must be carefully selected because it affects the multilayer packaging of the present invention, especially the appearance and gas barrier properties of the multilayer film coloring material after retort treatment. In addition, when the multilayer packaging of the present invention is subjected to so-called boil sterilization treatment at 100°C or lower, a resin with low heat resistance can be used, but when the temperature exceeds 100°C, resins with low heat resistance can be used, especially 105~
When subjected to retort treatment performed at 135° C., consideration must also be given to heat resistance. Furthermore, in the present invention, it has been found that the higher the moisture permeability of the outer layer, the better the appearance and gas barrier properties after retorting, resulting in better results. The method for evaluating moisture permeability is the method shown in J I 5-Z-0208, that is,
A method of determining the weight increase rate by attaching a film of any thickness to a cup containing a moisture absorbent, sealing and fixing the film, and then leaving it in a thermostat controlled at 40°C and 90% relative humidity, and measuring the rate of weight increase. is convenient. When using a material whose moisture permeability (unit: g/♂day) measured by this method is 35 or more, particularly 50 or more, more preferably 100 or more, the gas barrier during storage after retort treatment is Good for sexual recovery.

In the present invention, the resin for the outer layer (A) preferably used is PA, polyester, or polycarbonate, and the most preferably used resin for the outer layer is PA. Examples include the various PAs mentioned above,
Especially nylon-6, nylon-66, nylon-6/
6.6 etc. are mentioned. The thickness of this resin is 900~Kl (10g/♂da7
It is. The moisture permeability is approximately proportional to the thickness of the fat layer (A). Therefore, a thinner material is preferable, but depending on the resin, it is not possible to mold the material thinly, and making it thinner may result in defects in strength, etc., and the preferable range varies depending on each resin.

If it is unstretched nylon, it is 275μ or less, especially 110μ
μ or less, more preferably 15 to 40 μ is used.

For two-wheel stretched nylon, 97μ or less, especially 39μ
It can be used at a thickness of 10 μm or less, more preferably 10 μm to 20 μm.

Examples of other resins include polycarbonate resin (having a moisture permeability of 120 to 150 g/biday at a thickness of 10 μm, and preferably used within a thickness range of 10 to 38 μm).

Polyester resins may also be employed for the purposes of the present invention. In particular, polyethylene terephthalate wood has a water vapor permeability of 6 (Ig/d −
dat, it is preferable to use it with a thickness of 15μ or less.

Polyetherketone (143), polysulfone (490), polyether resulfone, which can be used for the purpose of the present invention, shows the moisture permeability (indicated in parentheses) per lOμ of the resin used for the outer layer (A). (50
0), polyetherimide (218>, polyimide (
The multilayer f! Although it is suitable for the construction of packaging, its low heat resistance limits its use to special applications such as low-temperature sterilization.

Further, polypropylene has low moisture permeability (14 to 35 g/m/dB per 10 μm), so its use is usually difficult.

Polyethylene is also not suitable because it has low moisture permeability and low heat resistance.

Commercially available films can be used as the outer layer (A), and non-stretched nylon film (CN), two-wheel stretched nylon film (ON), two-wheel stretched polyethylene terephthalate film (0-PET), polycarbonate film, etc. are suitable, but especially Two-wheel stretched film is best.

The water vapor permeability of the resin used for the outer layer (A) can be measured by the water vapor permeability of a single layer film, and if these are laminated by a dry lamination method, the water vapor permeability value of the single layer film can be measured. The effect on the moisture permeability of the adhesive in dry lamination is small and is not considered.

For multilayer packages that have already been laminated (laminated products or coextruded products), the moisture permeability of the film made from a single layer of resin used in the outer layer is substituted for the value of the moisture permeability of the outer layer of the multilayer package. be able to. When the outer layer is composed of two or more layers, the water vapor permeability of the multilayered outer layer can be determined by a conventional method from the water vapor permeability of a film made of a single layer for each of the constituent resins. This concept of moisture permeability can also be applied to the inner layer described below.

In the multilayer package of the present invention, it is important that the inner layer (C) has low moisture permeability. There are no particular restrictions on the low water absorption thermoplastic used for the inner layer, but depending on the purpose, it is possible to obtain an excellent packaging material by considering moisture permeability, heat resistance, heat sealability, transparency, etc. can.

First, generally speaking, the lower the moisture permeability of the inner layer, the higher the oxygen gas barrier properties of the obtained multilayer structure. This is believed to be because the lower the moisture permeability of the inner layer, the lower the relative humidity of the intermediate layer. The moisture permeability mentioned above is 20
gh1da7 or less, more preferably ha10g/d
- Day or less is preferable, and suitable results can be obtained by using, for example, poly-10-pyrene 60 μm (moisture permeability bgiyt·da7). Polypropylene can provide satisfactory results in terms of heat resistance, heat sealability, and transparency. Polypropylene is suitable as the inner layer resin for many purposes, but other thermoplastic resins can also be used. , polystyrene-based 1L polyvinyl chloride resin,
Examples include acrylic resins, polyvinylidene chloride, polyacetal, and polycarbonate resins.5 These resins may be used alone or in a layered manner.

Suitable films used for the inner layer (C) include nylon film (CN or ON), unstretched polypropylene film (CPP), second-class polypropylene film (OPP), polyethylene film, polyvinylidene chloride film, etc. However, if retortability and heat sealability are important, it is desirable to use an unstretched polypropylene film for the innermost layer.

To lower the moisture permeability of the inner layer (C), select resin or
Alternatively, this can be achieved by adjusting the thickness ratio of the inner layer and the outer layer. Further, when some of the layers of the laminated elliptical body of the present invention are produced by coextrusion, a common technique is employed in which the main resins of the intermediate layer and the inner layer are laminated with adhesive resin sandwiched therebetween. Adhesive resins include polyolefins such as polypropylene, polyethylene, or copolymers of ethylene and monomers that can be copolymerized with it (vinyl acetate, acrylic esters, etc.), modified by adding maleic anhydride, etc. etc. are used.

Additives such as antioxidants, colorants, fillers, and the like described above may be added to the resin used for the outer layer or the inner layer.

The multilayer mn structure of the present invention can be formed by various lamination methods such as those described below. coextrusion method, dry lamination method,
In the sand lamination method, extrusion lamination method, and coextrusion method, when PA is used for the outer layer, an adhesive resin layer may not be required between the outer layer and the intermediate layer, which is advantageous in terms of the process.

When providing an adhesive 11M layer, it is preferable to arrange it so that the combined moisture permeability of the outer layer and the adhesive W resin layer is as high as possible, especially 35/■f da7 or more.For dry laminate, the outer layer A common method is to bond three or more types of films: , intermediate layer, and inner layer. Therefore, an inorganic film is laminated at a desired position by vapor deposition, if necessary, before bonding.

In addition to the layer structure of the multilayer structure and multilayer package of the present invention, the following can also be used. (A)/(B)/(A
)/(C), (A)/(B)/(A)/(B)(C),
There is - between each of these layers! - It is free to provide an adhesive layer as required, and it is also free to provide other layers, such as an IIN layer, between each layer.

The characteristics of the multilayer packaging body of the present invention are best exhibited when it is used as a film packaging material, particularly as a film packaging material for retorts. Applications of film packaging include lids, pouches, vacuum packaging, skin bags, deep-draw packaging, and rocket packaging. ! The material is poly 1 layered with gas barrier material.
It is preferable to seal the container mainly containing 0 pyrene using a heat sealing method.6 The lid material of the present invention has a high retention property, is transparent, and does not have a yellowish tinge. Increase the product value and also improve the contents [! !
The L size has the advantage of being able to open the lid. Pouches are used in shapes such as three-sided seals, four-sided seals, pillows, gussets, and standing pouches. Furthermore, the multilayer packaging body of the present invention, which can be used in the form of a bag-in-box, exhibits excellent performance not only as a film packaging but also as a cup- or tray-shaped container. In this case, the resin for the inner layer is polypropylene, high-density polyethylene, heat-resistant polyester, etc., and the thickness is <200 to 12 mm thicker than the film material.
It is preferable to set it to 00μ.

The acid form of this container can be made by coextrusion laminating the nylon outer layer and the composition of the intermediate layer onto a thick sheet of inner resin, or by laminating a nylon film and a film of the composition (by dry lamination or coextrusion). ) is laminated onto an inner resin sheet by dry lamination or sand lamination, and then deep drawing is performed using a vacuum-pressure molding machine.

Containers using the outer package of the present invention in the form of 1L pouches, trays, cups, etc. are subjected to retort treatment or boil sterilization treatment - known hot water heating treatment methods and conditions are adopted as these treatment methods. be able to. Various methods are used for retort processing, such as recovery method, displacement method, steam method, Java method, and spray method. Immediately after retorting, the packaging material of the present invention tends to become white and opaque.

For example, among the multilayer packaging bodies of the present invention, an example suitable as a film packaging material is an unstretched nylon-6 film for the outer layer.
3 Qu, moisture permeability 3 (10 g/d day), EVOH and nylon 6/12 were inorganic vapor deposited on the inside of a film (50 μ) of 8020 parts by weight of nylon 6/12. This film is made by laminating films (60μ, moisture permeability 6g/d・da7) using a dry lamination method, and this film is used as a lid material or a pouch in a retort (1
(20°C, 30 minutes), it becomes white and opaque after retort treatment III. However, after air drying, it becomes completely transparent. The oxygen gas permeability (hereinafter 0TR) also reaches its equilibrium value within 12 hours. In order to more reliably achieve transparency and OTR recovery, drying may be performed more intensively than usual.

Although the multilayer film thus obtained re-whitens when exposed to water during storage, it regains full transparency once the surface water is removed.

The above-described multilayer packaging of the present invention can be filled with food and then, if necessary, can be made into an aerated layer by known means, or can be replaced with an inert gas such as nitrogen gas or carbon dioxide, and then can be heat-sealed or the like. Seal and then boil or retort sterilization.

Examples of foods that are suitable include cooked or semi-cooked foods that can be eaten as they are or heated prior to consumption.

Cooked curry, cooked hash, beef stew borscht, meat sauce, sweet and sour pork, sukiyaki, and Chinese bean paste.

Vegetables, meat and potatoes, oden, boiled asparagus, sweet corn, mashi roum, cream-stewed tuna, consommé, potage, etc., miso soup, pork soup.

Kenchinjiru, rice, sekihan, kamameshi, fried rice, pilaf, art book,
Spaghetti, soba, udon, ramen, noodles.

Food supplements such as kamameshi mix, Chinese soba mix, boiled red beans, zenzai, anmitsu, meatballs, hamburgers, beef steaks, roast balk, pork tsuchi, corned beef, ham, sausage, grilled fish, yakiniku, yakitori, roast Chicken, pork stew, fish meat, bacon, kamaboko, pudding, jelly, yokan, various types of veterinary foods, and the multilayer packaging of the present invention can be used for confectionery products such as mandarin oranges, beech, pineapple, cherries, olives, etc., as well as sauces. , vinegar, mirin, dressing, mayonnaise, kefchap, cooking oil, miso, lard and other seasonings, tofu, jam, butter, margarine, confectionery juice, vegetable juice, beer, cola, lemonade, sake, shochu, confectionery wine ,
Also excellent as a container for wine, whiskey brandy, etc. In addition, pharmaceuticals such as Ringer's solution, agricultural chemicals, cosmetics, detergents, organic liquid chemicals such as benzene, toluene, xylene, acetone, methyl ethyl ketone, n-hexane, cyclohexane, carbon tetrachloride, gasoline, kerosene, petroleum benzene, thinner, and grease, and vitamins. It can also be used as a container for medical liquids such as drugs and glucose.

E,XJL! ! L implementation f! 41 EVOH has an ethylene monomer unit content of 28 mol%, a saponification degree of 998%, and a melt index (190°C
2160g > 1.2g/101II+ resin beret 79% and PA as PA A-6/+2 copolymer [weight ratio of caprolactam units and lauryllactam units 80/20, melting point 196°C, relative viscosity is 2゜5]2
0% and lithium chloride 1% (0.0% as lithium element)
After tri-blending 0233 of/l1jff+100g), co-directional twin-screw extrusion II with a diameter of 30mm- (Gui temperature 2
Melt extrusion was carried out at 30° C.) to obtain blended pellets. After drying this blend pellet, film formation was carried out using an extruder equipped with a full-flight screw with a diameter of 40 μm and a coat hanger die with a diameter of 500 μm (temperature 230°C). A transparent unstretched film was obtained.

Next, this film was used as an intermediate layer, and a commercially available two-wheel stretched nylon-6 film (Unitika Emblem ON,
Thickness 15μ, moisture permeability 260g/m'day),
Using a commercially available unstretched polypropylene film (Tocero CP, thickness 60μ, moisture permeability 7g/♂・day) for the inner layer,
Dry lamination was performed to obtain a three-layer transparent film. Takerapuku A- is an adhesive for dry lamination.
31115 (manufactured by Takeda Pharmaceutical Co., Ltd.) was used as the main ingredient, and Takenate A-10 (manufactured by Ota Pharmaceutical Co., Ltd.) was used as a curing agent. The amount of adhesive applied was 4.0 g/♂. After lamination, raw processing was performed at 40°C for 3 days.

This film was made into a four-sided sealed pouch with inner dimensions of 1σ×1oCn. The contents were water. This is a retort device! (-Manufactured by Nichiita Seisakusho, high temperature and high pressure cooking sterilization tester, RC
3-40 RTGN) was used to perform retort treatment at 120° C. for 30 minutes.

After retort processing, the film was whitish.

Approximately 2 hours after the retort treatment, the film became transparent and had a good appearance with no delamination or the like.

One day after retorting, the transparent pouch surface was wet with water.
I put down the paper, and there was one more device still wet. The surface of the pouch was whitened in spots. However, when the surface water was wiped off, the transparency was completely restored in about 30 minutes.

In addition, a film was cut out from a similarly retorted pouch and the amount of oxygen permeation was measured using OXTRAM-10150A (MOCON) under conditions of 65% RH on the outside and 100% RH on the inside. 1.2ee/about 12 hours after retort
d-dt7-iLw+ (the film was transparent at this time), and the oxygen permeation amount of the film that became transparent again after re-whitening was also 1.2 cc/+jdate·aL-.

Comparative Example 1 A multilayer film was obtained in the same manner as in Example 1 except that no metal salt was added, and a pouch was made. The following retorts were performed in the same manner. This pouch also became transparent about 2 hours after retorting. After one day of storage, a wet R paper was placed on the surface and after one day of storage, it turned white in spots. Some whitening remained even after air drying.

Examples 2 to 6 In Example 1, instead of lithium chloride, 4.0 g of calcium nitrate (Ca(NO5)2) (Ca atom 0.
124mol/11&f100g) (Example 2),
Aluminum nitrate (At(NO4) > 3)
5.0g (A IJ [Chiro 023■o l
/ Ill Ii l00g) (Example 3), Sodium acetate (CH) COON a) 2.0g (Na atom [1,024mol/Thu!f100g> (Example 4), Boric acid (Hs B O4) 1.4g (B atom 0.1123 so l/III it 100g) (
Example 5) was added, and the other evaluations were made in the same manner. In either case, a film with good transparency and no residual re-whitening could be obtained.

Example 6 A coextruded multilayer film consisting of four layers was produced using a feedblock type coextrusion IT having four extruders and a T-die. The composition consists of, from the outside, polyamide (Novamid 1020 manufactured by Mitsubishi Chemical Industries, thickness 15μ), the composition used in Example 1 (thickness 15μ), and adhesive W sushi (Atmer〇F-500 manufactured by Mitsui Petrochemical Corporation, thickness 10μ). ), polypropylene (PY-22 (1, thickness 50μ) manufactured by Mitsubishi Yuka W). The following procedure was carried out in the same manner as in Example 1. The transparency recovery property after retorting was good, and there was no residual re-whitening after water adhesion. There was none.

Example 7 A multilayer sheet was obtained in the same manner as in Example 6, and thermoformed using a vacuum-pressure forming machine (manufactured by Asano Seisakusho Co., Ltd.) to a diameter of 7c.
A round cup with a height of 3.5 cm and a bottom diameter of 60 cm was obtained.

The average thickness of the container is made of polyamide (Mitsubishi Chemical Corporation) starting from the outer layer.
Tsubamitsudo 1020 (manufactured by Mitsui Petrochemical Co., Ltd., thickness 12μ), the composition used in Example 1 (thickness 16μ), adhesive tree 1m (Mitsui Petrochemical @ 4I! Atomer QF-500, thickness 8μ), polypropylene (Mitsubishi Yuka ■ PY- 220, thickness 3111μ)
The container was filled with water, and the lid was sealed using a commercially available aluminum packaging material. The following was retorted in the same manner as in Example 1. Good transparency recovery after retorting,
There was no residual rewhitening.

Example 8, Comparative Example 2 In Example 1, a film of the EVOH composition was obtained.

Next, using an electron beam evaporation device, the degree of vacuum is 1. OXI
.

-'Torr, 200 on one side (inner surface) of the above film.
An angstrom silicon oxide film was deposited. Using this film, the film was then retorted in the same manner as in Example 1.

The appearance of the film after retorting was good, with no residual re-whitening due to contact with water. A film was obtained from the EVOH composition of Example 1 without adding any metal. Thereafter, silicon oxide was similarly deposited and retorted. The appearance after retorting was good, but after re-whitening due to contact with water, whiteness remained even after air drying.

Examples 9-12. Comparative Examples 3 to 6 In Example 1, almost the same transparency was obtained even when nylons having different EVOH1 copolymer compositions with different ethylene contents were used, which shows the case where the composition of EvOHffi was changed. However, systems containing less ethylene have a lower oxygen permeation rate and better storage stability. On the other hand, those with too little PA content and those with too much PA content caused poor appearance. Those with low metal content had some residual re-whitening.

On the other hand, those with a high metal content generated gel during thermoforming, making them unusable. The results are shown in Table 1.

The following margins F, 11th and 11 The multilayer elliptical body and multilayer packaging of the present invention are different from conventional EV
This solves the problem of residual whitening when it comes into contact with water during storage, which was a major practical defect in the appearance of OH-based rettle packaging materials.

Claims (7)

[Claims] (1) Moisture permeability (measured at 40°C and 90% RH) is 40g
/m^2・day or more resin outer layer (A), ethylene containing 20 to 65 mol% of ethylene monomer units
50 to 97% by weight of vinyl alcohol copolymer resin, 45 to 3% by weight of polyamide resin, and 0.005% of at least one water-soluble or alcohol-soluble metal compound.
Layer (B) of the composition consisting of ~5% by weight, and moisture permeability (
Measured at 40℃ and 90%RH) is 20g/m^2・da
A gas barrier multilayer packaging body comprising a resin inner layer (C) having a value of y or less. (2) The multilayer package according to claim 1, wherein the outer layer (A) is a layer of at least one resin selected from polyamide, polyester, and polycarbonate. (3) A multilayer package, wherein the metal compound of the intermediate layer (B) according to claim 1 is an alkali metal or alkaline earth metal compound. (4) A multilayer packaging body, wherein the metal compound of the intermediate layer (B) according to claim 1 is a compound of boron, silicon, iron, aluminum, phosphorus, and zinc. (5) A multilayer package having a transparent inorganic film on the inside or both sides of the intermediate layer (B) according to claim 1. (6) A multilayer package for boil sterilization or retort sterilization, comprising the multilayer package according to any one of claims 1 to 5. (7) A food package obtained by filling the multilayer package according to any one of claims 1 to 5 with a food or pharmaceutical and boiling or retort sterilization.