JP2801277B2 - Multi-layer package - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Technical Field of the Invention The present invention relates to a package, in particular, a package containing a polyolefin resin as a main material, to a food, wherein there is no transfer of an odor component, and furthermore, a taste component in a food. There is no migration to food packaging, and there is no conventional example that also has hot water resistance.
The present invention relates to a multilayer package capable of sterilizing boil and retort.

B. Prior Art As the resin used for the innermost layer, polyolefin resins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer are generally used. This is the cost,
This is because of the heat sealing suitability. However, these resins easily permeate the aroma component, and conversely, low-molecular substances remaining in the resin migrate to the food, so that a so-called polyolefin odor is easily imparted to the food. These cause changes in the taste, smell and organic components of the contents, and are problematic.

Ethylene-vinyl alcohol copolymer (EVOH)
Is a thermoplastic resin with the highest gas barrier properties in existence, and also has excellent barrier properties for aromatic components and organic substances,
Furthermore, there is no transfer of low molecular weight substances to the contents.

An example in which EVOH is used for the innermost layer is disclosed in JP-B-61-58307, and JP-A-54-78749 discloses that a blend of EVOH and a polyamide and that the blend can be laminated with another thermoplastic resin. However, there is no description that the blend is used as the innermost layer and the thermoplastic resin is used as the outer layer.

Furthermore, Japanese Patent Publication No. 59-38103 describes a structure comprising a blend layer of EVOH and a thermoplastic resin and a moisture-resistant or creep-resistant resin layer, but the blend layer with EVOH is the innermost layer. There is no description to do.

C. Problems to be Solved by the Present Invention However, EVOH has a problem that the retort (120 ° C.) or the boil (98 ° C.) treatment causes wavy wrinkles and delamination, and EVOH layers (or inner layers when used for the inner layer). Sticking occurs and is not practical in appearance.

Such anomalies during retort of the EVOH layer are as follows.
In hot water at a temperature of 120 ° C. or higher, particularly hot water at a temperature of 120 ° C. or higher, the water is absorbed and swells, and at the same time, melts and flows to form an amorphous state. Therefore, it is not possible to use EVOH for the innermost layer in direct contact with hot water to make a retort wrapping material. The present invention has realized a configuration which has never been considered as impossible in the past, that is, a retortable packaging material having an EVOH layer as the innermost layer.

D. Means for Solving the Problems The present inventors have conducted extensive studies on means for preventing EVOH from flowing due to retort treatment.

As a result, when a composition comprising 3 to 97% by weight of EVOH and 97 to 3% by weight of a polyamide resin (hereinafter sometimes abbreviated as PA) is used for the innermost layer and the outer layer is made of another thermoplastic resin, The layer of the composition does not cause flow, does not cause ripples, patterns, etc., and the packaging material with high preservability inherent in EVOH can be obtained. After confirming the surprising facts, the present invention has been completed.

One of the resins forming the composition of the innermost layer of the present invention
EVOH includes arbitrary ones obtained by hydrolyzing a vinyl acetate unit in a copolymer of ethylene and vinyl acetate. ~ 65 mol%, especially 27 ~
50 mol%, a saponification degree of vinyl acetate unit of 96% or more, especially 99% or more, and a melt index (19
(0 ° C., 2160 g) is exemplified by a range of 0.2 to 60 g / 10 minutes. Further, the EVOH referred to in the present invention may be modified with a copolymer monomer in a range of 5 mol% or less. Examples of the modifying monomer include propylene, 1-butene, 1-hexene, and 4-methyl-1-pentene. Acrylates, methacrylates, maleic acid, fumaric acid, itaconic acid, higher fatty acid vinyl esters, alkyl vinyl ethers, N- (2-dimethylaminoethyl) methacrylamides or quaternized products thereof, N-vinylimidazole, or Its quaternary product, N-vinylpyrrolidone,
N-n-butoxymethylacrylamide, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane and the like can be exemplified.

The other resin forming the composition forming the innermost layer is a polyamide resin.

Polyamide resins (PA) include polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon 9), polyundecaneamide (nylon-11), Lauryl lactam (nylon-12), polyethylene diamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), poly Hexamethylene sebacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10 , 6), polydodecamethylene sebacamide (nylon-10,8) or caprolactam / lauryl lactam copolymer (nylon-6 / 12), capro Kutamu / .omega.-aminononanoic acid copolymer (nylon-6 /
9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,6), lauryl lactam / hexamethylenediammonium adipate copolymer (nylon-12 / 6,6), hexamethylenediamonmonium adipate / Hexamethylenediammonium sebacate copolymer (nylon-6,6 / 6,10), ethylenediammonium adipate / hexamethylenediammonium adipate copolymer (nylon-2,6 / 6,6), caprolactam / hexa Methylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon-6 / 6,6 / 6,10), polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, hexamethylene isophthalamide / terephthalamide copolymer And the like.

Among these PAs, the most preferred one for the present invention is a caprolactam / lauryl lactam copolymer, ie, nylon-6 / 12. The composition of 6 and 12 components in nylon-6 / 12 is not particularly limited, but 12 components are 5
Preferably, it is from about 60% by weight, more preferably from 10 to 50% by weight. Further, its relative viscosity is in the range of 2.0 to 3.6, more preferably 2.2 to 3.2.

A polyamide having a polyether bond in the polymer chain may be obtained by adding a polyether diamine and a dicarboxylic acid (such as dimer acid) at the time of polycondensation of these PAs, especially nylon-6 / 12. At the time of condensation, aliphatic amines such as hexamethylenediamine, laurylamine and laurylamine, and aromatic amines such as metaxylylenediamine and methylbenzylamine are added to reduce the amount of carboxyl end groups in the polyamide. Are preferred. In this case, the amine terminal group is preferably at least 8 × 10 ⁻⁵ equivalent / g and the carboxyl terminal group is preferably at most 3 × 10 ⁻⁵ equivalent / g.

By using the resin (B) blended with EVOH (A) in the innermost layer, it does not cause morphological defects, and also has the odor components (outer layer resin odor, for example, polyolefin odor) present in the food package. It is surprising that there is no transfer to the food packaging, and further no transfer of the taste component in the food to the food package.

Although the detailed mechanism that provides such a remarkable effect is not always clear, it is considered that the use of PA resin in a blend with EVOH is effective in preventing the flow of EVOH after boiling at 98 ° C or after retorting at 120 ° C. Then, it is believed that a resin blend having a melting point higher than the heat treatment temperature exhibits such an effect.

The composition ratio of EVOH and PA resin forming the innermost layer composition is 3
% To 97% by weight: 97 to 3% by weight, preferably 55 to 95% by weight: 45 to 5% by weight, more preferably 65 to 85% by weight: 15 to
35% by weight. When the PA resin component is small, the outer layer package having this composition as the innermost layer is rippled when retorted.
There is a tendency for morphological defects such as patterns to appear. Conversely, if the amount of the PA resin is too large, the odor-preventing property decreases, which is not preferable.

Further, to the composition of the innermost layer, other polymers or antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, coloring agents, fillers, etc. may be added within a range not to impair the purpose of the present invention. Can be. Other polymers include polyolefin resins, polyester resins, polycarbonate resins, polystyrene resins, polyvinyl chloride resins, acrylic resins, polyvinylidene chloride resins, polyurethane resins, and the like. Further, specific examples of the additives other than the polymer include the following.

Stabilizers: calcium acetate, calcium stearate, hydrotalcites, metal salts of ethylenediaminetetraacetic acid and the like.

Antioxidant: 2,5-di-t-butylhydroquinone, 2,6
-T-butyl-p-cresol, 4,4'-thiobis-
(6-t-butylphenol), 2,2'-methylene-bis (4-methyl-6-t-butylphenol), oketadecyl-3- (3 ', 5'-di-t-butyl-4'- (Hydroxyphenyl) propionate, 4,4'-thiobis-
(6-t-butylphenol) and the like.

UV absorber: ethyl-2-cyano-3,3-diphenyl acrylate, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'hydroxy-3'-t-butyl-5 ' -Methylphenyl) -5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone and the like.

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

Antistatic agents: pentaerythritol monostearate, sorbitan monopalmitate, sulfated oleic acid, polyethylene oxide, carbowax and the like.

Lubricants: ethylene bis stearamide, butyl stearate and the like.

Colorant: carbon black, phthalocyanine, quinacridone, indoline, azo pigment, titanium oxide, red iron oxide, etc.

Filler: glass fiber, asbestos, mica, sericite, talc, crow flake, ballastonite, calcium silicate, aluminum silicate, calcium carbonate, etc.

When a composition of 5 to 60% by weight of a powder selected from mica, sericite, talc and glass flake and 95 to 40% by weight of the above resin blend composition was used as the innermost layer, Is preferable since the gas barrier property tends to be improved as compared with the case where no is used. This method is mainly applicable to containers such as cups and trays.

As a blending method for obtaining the composition, a single-screw or twin-screw extruder (in the same direction or in a different direction),
After melt extrusion with an intensive mixer, a continuous intensive mixer or the like, a method of pelletizing under cooling is used.

In the multilayer package of the present invention, the above composition plays a role of a gas barrier material, and its thickness directly affects the barrier performance. The thickness of the innermost layer is selected from the range of 10 to 250 µ, usually from 20 to 100 µ.

In the present invention, it is essential that the layer of the composition is the innermost layer.However, providing a protective layer by coating a small amount of latex or a solution of a resin for the purpose of surface protection is included in the scope of the present invention. It is. In this case, the resin includes a polyamide-based, polyester-based, cellulose-based, epoxy-based or rubber-based resin. Coating amount is 1 to 10 g / m ² by solid content, preferably 3 to 7 g / m ^2.

In the outer package of the present invention, it is important that the outer layer is a thermoplastic resin other than the innermost layer resin, preferably a hydrophobic thermoplastic resin layer.
An excellent packaging material can be obtained by considering the transparency and the like.

When the multilayer package of the present invention is subjected to a so-called boil sterilization treatment at 100 ° C or lower, a resin having low heat resistance can be used, but when the temperature exceeds 100 ° C, particularly 105 ° C to 135 ° C.
In the case of being subjected to the retort treatment performed in the above, consideration for heat resistance is also necessary.

As the resin used for the outer layer in the present invention, polyolefin resins represented by polyethylene and polypropylene are the most important for the purpose of the present invention. In addition to polyolefin, polyamide resins, polyester resins, polystyrene resins, polyvinyl chloride resins, acrylic resins, polyvinylidene chloride resins, polyacetal resins, polycarbonate resins, and the like. Alternatively, two or more kinds are mixed and used as a single layer or multiple layers.

The multilayer package of the present invention can be manufactured by the following various laminating methods. That is, a coextrusion method, a dry lamination method, a sand lamination method, an extrusion lamination method, a coextrusion lamination method, and the like. As the film used for the outer layer in the dry lamination, a nylon film (CN or ON), a non-stretched polypropylene film (CCP), a biaxially stretched polypropylene film (OPP), a polyethylene film, a polyvinylidene chloride film, and the like are preferable. is there.

When the multilayer package of the present invention is produced by a co-extrusion method, an ordinary technique of laminating an outer layer and an inner layer with an adhesive resin interposed therebetween is employed. Adhesive resins such as polypropylene, polyethylene, or resins obtained by modifying polyolefins such as copolymers of ethylene with copolymerizable monomers (such as vinyl acetate and acrylic acid ester) with addition of maleic anhydride, etc. Is used.

The resin used for the outer layer is an antioxidant as described above,
Additives such as coloring agents and fillers may be added.

Although the use of the multilayer package of the present invention is not limited, it is most effective when used for boiling and retorting.

Examples of the use of the film packaging material include lid materials, pouches, vacuum packaging, skin packaging, deep drawing packaging, and rocket packaging. The lid material is preferably sealed and sealed by a heat sealing method in a container mainly composed of polypropylene laminated with a gas barrier material. The lid material of the present invention has the advantage that it has a high level of holding properties, is not yellowish or the like, and thus enhances commercial value, and can be opened while checking the contents. Pouches are used in the form of three-sided seals, four-sided seals, pillows, gazettes, standing pouches and the like. It can also be used in the form of a bug in box. The multilayer package of the present invention exhibits excellent performance as a cup or tray type container in addition to the film package. In this case, polypropylene, high-density polyethylene, heat-resistant polyester, or the like is used as the resin of the outer layer, and is 200 to 1200 μ thicker than the film material. As a method of forming the container, other than a method of producing a sheet by a co-extrusion method, a method of extrusion laminating the innermost layer composition on a thicker sheet of the outer layer resin, or a method of dry laminating a film of the composition on a sheet of the outer layer resin or After laminating by a sand laminating method or the like, a method of deep drawing by a vacuum press forming machine is adopted. Further, the multilayer package of the present invention can be formed into a bottle shape or a tube shape by a co-extrusion method.

The multilayer package of the present invention is used in the form of a lid material, a pouch, a tray, cups, a bottle or a tube,
These exhibit an excellent effect particularly as a multilayer package for boil sterilization or retort sterilization.

Here, as the retort sterilization treatment or the boil sterilization treatment, known hot water heating treatment can be performed. Various methods such as a recovery method, a replacement method, a steam method, a shower method, and a spray method are employed for the retort sterilization treatment.

In the case of boil sterilization or retort sterilization treatment, after filling the food, the interior is degassed by known means as necessary, or after the interior is replaced with an inert gas such as nitrogen gas or carbon dioxide, heat is applied. It is preferable to seal by means such as a seal, and then to perform sterilization by boiling or retort. Further, the multilayer package of the present invention can be used as it is, without being subjected to a boil sterilization or a retort sterilization treatment, to be filled with food as it is. As food to be filled,
Cooked or semi-cooked foods that are eaten as they are or heated prior to eating are suitable. Next, examples of foods are shown.

Processed meat products such as bonito, seaweed, tea, ham, sausage, rice confectionery, castella, bread, beans, cakes, rice,
Instant noodles, snack foods, pickles, kamaboko, fish products such as chikuwa, tsukudani, miso, liquid soup, cheese products, sprinkles.

Next, you need to sterilize cooked curry, cooked bean sprouts, beef shichiyu, borscht, meat sauce, sweet and sour pork, sukiyaki, Chinese bean, happo greens, meatballs, oden, asparagus boiled, sweet corn, Various soups such as matsushiyu room, boiled tuna cream, consommé, potage, miso soup, pork juice, kenchin soup, cooked rice, red rice, pot rice, fried rice, pilaf, porridge, spaghetti, soba, udon,
Additive foods such as ramen, noodles, kamame-no-miso, and Chinese noodles, boiled azuki, zenzai, anmitsu, meat dumplings,
Hamburger, beef steak, roast pork, pork saute, corned beef, ham, sausage, grilled fish, grilled meat,
Yakitori, roast chicken, pork kechijap, fish meat, bacon, kamaboko, pudding, jelly, yokan,
Various pet foods. In addition, the multilayer package of the present invention is a fruit product such as tangerine, peach, pineapple, cherry, olive, soy sauce, sauce, vinegar, mirin, dressing, mayonnaise, ketchup, cooking oil, miso, lard and other cooking ingredients, tofu It is also excellent as a container for jars, jams, butters, margarines, fruit jyous, vegetable jyous, beer, cola, lemonade, sake, shochu, fruit sake, wine, whiskey, brandy, etc. Also, medicines such as Ringer's solution, pesticides, cosmetics, detergents, benzene, toluene, xylene, acetone, methyl ethyl ketone, normal hexane, cyclohexane, carbon tetrachloride, gasoline,
It can also be used as a container for organic liquid chemicals such as kerosene, petroleum benzine, thinner, and grease.

Hereinafter, the present invention will be described more specifically with reference to examples. The parts are parts by weight.

E. Examples Example 1 As EVOH, the content of ethylene monomer units was 44 mol%, the saponification degree was 99.8 mol%, and the melt index (190
80 ° C., 2160 g) of a resin pellet having 5.5 g / 10 min, and PA as a PA-6 / 12 copolymer [caprolactam structural unit and lauryl lactam structural unit in a weight ratio of 80/20 and a melting point of 196.
℃, relative viscosity 2.5] 20 parts after dry blending, diameter 30mm
Was extruded with a co-rotating twin-screw extruder (die temperature 230 ° C.) to obtain a blend pellet. The blended pellet was dried to obtain a composition (1). Using this, a film was formed using an extruder having a 40 mm diameter full flight type screw and a 550 mm width coat hanger die (temperature 230 ° C.)
A 50 μm thick transparent film was obtained. A biaxially stretched polypropylene film (area stretch ratio 50 times, 20 times
μ) was dry-laminated. As an adhesive for dry lamination, a urethane-based adhesive (Takeluck A-385)
(Manufactured by Takeda Pharmaceutical Co., Ltd.) and Takenate A-
After lamination, curing was carried out at 40 ° C. for 3 days using 50 (made by Takeda Pharmaceutical Co., Ltd.) as a curing agent. The laminated film was heat-sealed with a heat sealer at a pressure of 0.5 kg / cm ² , a heater surface temperature of 135 ° C. and a time of 2 seconds.
As a content, curry was filled and finally one side was sealed to obtain a pouch test sample (1).

A 100 cc glass bottle was filled with curry and sealed with an aluminum cap to prepare a control sample (0).

The above sample was retorted by Hisaka Manufacturing Co., Ltd.
120 ℃ using high-temperature and high-pressure cooking sterilization tester (RCS-40RTGN)
A 30 minute retort treatment was performed. After the retort, there was no breakage of the sticking seal portion inside the bag, and no morphological defects such as wrinkles of the innermost layer were observed.

This sample (1) was stored at 20 ° C. and 65% RH, and the control sample (0) was stored in a refrigerator (5 ° C.). Three months later, both were opened and the age and gender were evaluated by 10 randomly selected panelists. As a result, 9 out of 10 panelists did not notice any change in taste, smell or color.

Comparative Example 1 A multilayer film was obtained in the same manner as in Example 1 except that an unstretched polypropylene film (thickness: 50 μm) was used in place of the inner film, and then curry was filled and retorted. After the retort, no morphological defects such as wrinkles on the innermost layer were observed, and the condition was good. However, after 3 months, the contents were smelled and the taste was changed (10 out of 10 persons recognized it). In particular, there were many indications that the smell peculiar to plastic was felt and the flavor was reduced.

Comparative Example 2 In Example 1, a film was formed by using EVOH (ethylene monomer content: 44 mol%) instead of the inner layer film.
Using a μ film, a multilayer film was obtained, filled with curry and retorted. After the retort, the inner layers were stuck together and the seal part was broken. In addition, let the thing which the seal part does not produce tears leave for three months,
The contents were examined. As a result, the flavor of the contents was changed, and a polyolefin odor was observed.

Example 2 and Comparative Example 3 The multilayer structure of Example 1 was the same as that of Example 1 except that the outer layer was unstretched polypropylene film (hereinafter referred to as CPP) (50 μ) (inner layer) (Example 2). Example 1
(Comparative Example 3) in which the inner layer of the film was CPP was prepared, filled, and then retorted. In the bag of Example 2, no defective shape was recognized even after retorting. Also, the bag of Example 2
After storage for a few months and similar evaluation, no change in taste, smell or color was observed. On the other hand, the taste and flavor of the contents of the bag of Comparative Example 3 were changed (10 out of 10 persons).

Example 3 A co-extruded multilayer sheet composed of three layers was produced using a feed block type co-extrusion apparatus having three extruders and a T-shaped die. The composition was polypropylene (Mitsubishi Noka PY220 manufactured by Mitsubishi Yuka Co., Ltd., thickness 500μ) and an adhesive resin composed of maleic anhydride-modified PP (Modik P-300F manufactured by Mitsubishi Yuka Co., thickness 50μ) from the outside. This is a blend composition (1) (thickness: 100 μ) used in 1.
This multilayer sheet was molded into a cup-shaped container having a circular shape with a radius of 33 mm, a circular shape with an upper surface of 37 mm, and a height of 37 mm by using a vacuum pressure molding machine (manufactured by Asano Manufacturing Co., Ltd.). Average thickness after molding is polypropylene 250μ from outside, adhesive resin 25
μ, composition (1) was 50 μm.

The cup was filled with curry, heat-sealed using the multilayer film of Example 1 as a lid, and then subjected to a retort treatment at 120 ° C. for 30 minutes. Delamination of the seal part has been eliminated. There was no change in the taste, smell, or color of the contents after storage for three months. At that time, the inside of the container was inspected, but no defective configuration was found.

Examples 4 to 7 As shown in Table 1, a test was carried out by changing the composition of the inner layer material of Example 1, and there was no morphological defect and no change in taste, smell and color after 3 months was observed.

Examples 8 and 9 As shown in Table 1, the test was carried out by changing the outer layer of Example 1, but there was no morphological defect, and the taste, smell and color after 3 months did not change.

Example 10 In Example 1, the boil was performed at 98 ° C. for 30 minutes instead of the retort treatment at 120 ° C. for 30 minutes. However, there was no change in morphological defects, taste, and odor.

Comparative Examples 4 to 6 As shown in Table 1, in Comparative Examples 1, 2, and 3, when the boil was performed at 98 ° C. for 30 minutes instead of the retort treatment at 120 ° C. for 30 minutes, similar problems occurred.

F. Effects of the Invention The multilayer package of the present invention does not cause morphological defects, yet has gas barrier properties, and further does not transfer odor components depending on the food package to the food, and furthermore, in the food. The transfer of the taste component to the food package is small, and it is particularly suitable for sterilizing boil and retort.

Claims (2)

(57) [Claims] 1. A layer of a composition comprising 3 to 97% by weight of an ethylene-vinyl alcohol copolymer (A) containing 20 to 65% by mole of ethylene monomer units and 97 to 3% by weight of a polyamide resin (B). A multilayer package comprising at least two layers, in which an inner layer is a layer of a thermoplastic resin other than the above-mentioned composition, which is an outer layer. 2. A multilayer package for boil sterilization or retort sterilization, comprising the multilayer package of claim 1.