JPH07102659B2 - Gas barrier multi-layer structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has a transparent heat resistance that does not cause deformation even when subjected to hot water treatment or filled with food or beverage at high temperature for the purpose of sterilization. The present invention relates to excellent gas barrier multi-layer containers, films and sheets.

[Conventional technology]

In recent years, multi-layer sheets, films and containers made of various gas barrier resins and thermoplastic resins such as polyester, polyamide and polyolefin have been widely used for packaging of foods and beverages requiring gas barrier properties. .

The resin used for the gas barrier layer is ethylene-
Polyamides such as vinyl alcohol copolymer resins, vinylidene chloride copolymer resins, acrylonitrile copolymer resins, and polymethaxylylene adipamide (hereinafter abbreviated as nylon MXD6) are known.

Of these gas barrier resins, nylon MXD6 has excellent gas barrier properties and, in addition to having better thermal stability when melted than other resins, polyethylene terephthalate (hereinafter abbreviated as PET). ), Nylon 6 and polypropylene, and various thermoplastic resins such as co-extrusion and co-injection molding are possible, and use of the multilayer structure as a gas barrier layer has recently been actively promoted.

The glass transition point of the polyamide obtained from the polycondensation reaction of an aliphatic dicarboxylic acid represented by nylon MXD6 and metaxylylenediamine is around 70 ° C., for example, by stretch blow molding, a layer composed of nylon MXD6 and PET. A transparent wide-mouth container or transparent bottle made from a layer consisting of
When it is immersed in the above hot water, it contracts greatly.

Therefore, the container using nylon MXD6 cannot be used for the container of foods and beverages which require hot water treatment or filling at high temperature for the purpose of sterilization.

Further, Japanese Patent Publication No. 56-23792 proposes a gas barrier multi-layer container having a polyolefin layer such as polyethylene and polypropylene and a layer made of nylon MXD6.

However, when polyolefin is used, the appropriate temperature during processing such as deep drawing and blow molding is higher than that of PET, so nylon MXD6 tends to crystallize, and stretching processing is difficult, and uneven thickness and whitening occur. It is easy to wake up, and it is difficult to obtain a container that is satisfactory in shape and transparency.

Further, in JP-A-60-232952, a gas barrier multilayer comprising a polyamide obtained by a polycondensation reaction of metaxylylenediamine and a dicarboxylic acid containing a certain proportion or more of isophthalic acid and a thermoplastic polyester represented by PET. Molded bodies have been proposed. In this case, the exemplified copolyamide having isophthalic acid as a part of the dicarboxylic acid component unit has a higher glass transition temperature than nylon MXD6 and has a low crystallinity or is a substantially amorphous polymer. Is considered to be.

However, the copolymerized polyamide exemplified in JP-A-60-232952 has a high melt viscosity and becomes rubbery easily as the use ratio of isophthalic acid is increased in order to impart amorphousness. There is a problem that it is difficult to obtain a high molecular weight polymer.

[Problems to be solved by the invention]

At present, in addition to features such as light weight and resistance to breakage, a practical synthetic resin package that can withstand heat treatment for sterilization and hot filling, and has excellent transparency and gas barrier performance is available. Not obtained.

[Means for solving problems]

In order to solve these problems, the inventors of the present invention have made extensive studies as to a package having a gas barrier property. As a result, metaxylilediamine, an aliphatic dicarboxylic acid, and a dicarboxylic acid composed of isophthalic acid and terephthalic acid. A polyamide composition (polyamide C) composed of a copolyamide (polyamide A) obtained by a polycondensation reaction with a polycondensation reaction and a polyamide (polyamide B) obtained by a polycondensation reaction of metaxylylenediamine and an aliphatic dicarboxylic acid. ) And other thermoplastic resins are co-extruded and co-injection molded, and the precursors such as sheets, films and parisons are subjected to secondary processing such as blow molding, deep drawing and stretching for the purpose of sterilization. Heat resistance that does not cause shrinkage, deformation such as expansion, and whitening even in hot water treatment and hot filling of foods and beverages, And completed the present invention found that a multi-layer structure is obtained having even a light having excellent more advanced gas barrier property.

That is, the present invention relates to an aromatic dicarboxylic acid comprising 55 to 70 mol% of aliphatic dicarboxylic acid, 20 to 30 mol% of isophthalic acid and 5 to 20 mol% of terephthalic acid, and comprising isophthalic acid and terephthalic acid. Of 30 to 45 mol% of dicarboxylic acid and 40 to 60% by weight of copolyamide (polyamide A) obtained from polycondensation reaction of metaxylylenediamine, and aliphatic dicarboxylic acid and metaxylylenediamine 40-60% by weight of polyamide obtained from polycondensation reaction (polyamide B)
The present invention relates to a gas barrier multi-layer structure excellent in transparency and heat resistance, which is formed by bonding at least one layer of a polyamide composition (polyamide C) composed of the above and at least one layer composed of another thermoplastic resin.

The copolyamide (polyamide A) used in the present invention is a polycondensation of a dicarboxylic acid composed of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid containing isophthalic acid and terephthalic acid, and a diamine containing metaxylylenediamine as a main component. Obtained from the reaction.

The polycondensation reaction for obtaining the copolyamide (polyamide A) may be carried out by a method of passing a nylon salt obtained from a dicarboxylic acid and a diamine, or may be carried out by a method of directly reacting the dicarboxylic acid and the diamine.

Further, as an example of directly reacting, it is also possible to drop the metaxylylenediamine under normal pressure while raising the temperature to 160 to 300 ° C. to the molten dicarboxylic acid obtained by decomposing the powdery aromatic dicarboxylic acid, and react it. is there.

According to this direct reaction method, unlike the method via a nylon salt, the nylon salt from terephthalic acid and metaxylylenediamine, which have a high melting point, is not left in the reaction system, and the copolyamide (polyamide of the present invention) A)
Can be easily obtained.

As the aliphatic dicarboxylic acid used as a raw material for the copolyamide (polyamide A), adipic acid is most preferable in consideration of the gas barrier property of the obtained polyamide, but other dicarboxylic acids include succinic acid and glutaric acid. , Suberic acid, pimelic acid, azelaic acid, sebacic acid and dodecanedioic acid.

Of the total dicarboxylic acid component units of the copolyamide (polyamide A), the aliphatic dicarboxylic acid component units are 55 to
70 mol%, the isophthalic acid component unit must be 20 to 30 mol%, and the terephthalic acid component unit must be 5 to 20 mol%.

The copolyamide (polyamide A) used in the present invention is more than the polyamide (polyamide B) obtained by the polycondensation reaction of metaxylylenediamine represented by metaxylylene adipamide and an aliphatic dicarboxylic acid. ,
It has a melting point higher by about 20 ° C. and effectively acts to improve the heat resistance of a multilayer structure using the copolymerized polyamide.

In the copolyamide (polyamide A), aliphatic dicarboxylic acid component units account for 70% of all dicarboxylic acid component units.
If it exceeds mol%, the glass transition temperature of the obtained copolyamide will be lowered, and as a result, it will be impossible to obtain a package which is resistant to hot water treatment or high temperature filling, which is the object of the present invention.

Further, the aliphatic dicarboxylic acid component unit in the total dicarboxylic acid component unit, the copolymerized polyamide obtained when the content is 55 mol% or less, the melt viscosity becomes high and the thermal stability at the time of melting decreases, and the polycondensation reaction is completed. Also, it is difficult to perform melt molding, so that it is not a suitable material to be used in the present invention.

Furthermore, when the isophthalic acid component unit is 20 mol% or less or the terephthalic acid component unit is 5 mol% or less out of all the dicarboxylic acid component units, the obtained copolyamide shows properties as a crystalline polymer. Therefore, it is easy to whiten by heating during secondary processing, hot water treatment of the product obtained after secondary processing, etc., and therefore a suitable material that can be adopted for the multilayer structure of the present invention characterized by heat resistance and transparency. It does not become.

Polyamide (polyamide B) obtained from a polycondensation reaction of an aliphatic dicarboxylic acid and metaxylylenediamine is a polymer having crystallinity already known as a gas barrier packaging material, and its representative is metaxylylene adipate. Mido has already been tried to be used as a barrier packaging material.

The production of the polyamide (polyamide B) is carried out in the same manner as the production of the copolyamide (polyamide A), for example, via a nylon salt or by a method in which a dicarboxylic acid and a diamine are directly reacted.

Adipic acid is preferable as the aliphatic dicarboxylic acid used as a raw material for the polyamide (polyamide B), but other examples include suberic acid, pimelic acid, azelaic acid, and sebacic acid.

The metaxylylenediamine constituting the diamine component units of the copolyamide (polyamide A) and the polyamide (polyamide B) may contain a small amount of another diamine.

In this case, other diamines include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and octamethylenediamine, 1,3
Examples thereof include aliphatic diamines having a cyclic structure such as -bis (aminomethyl) cyclohexane and 1,4-bis (aminomethyl) cyclohexane, and aromatic diamines such as paraxylylenediamine and metaphenylenediamine.

The proportion of the copolyamide (polyamide A) in the polyamide composition (polyamide C) of the present invention is 40 to 60% by weight, preferably 45 to 60% by weight.

When the proportion of the copolyamide (polyamide A) is less than 40% by weight, the heat resistance effect of the copolyamide (polyamide A) having a high glass transition temperature cannot be clearly seen. On the other hand, when it exceeds 60% by weight, it is necessary to raise the temperature during heat processing, and when the other thermoplastic resin constituting the multilayer structure together with the polyamide composition is crystalline, whitening due to crystallization occurs. Or cause deterioration during processing,
This is not preferable because it induces thermal decomposition during adhesion.

The polyamide composition (polyamide C) in the present invention is
What is a copolyamide (polyamide D) obtained by a single melt polycondensation reaction using the same components and the same component proportions of dicarboxylic acids and metaxylylenediamine as those used in the production of the polyamide composition (polyamide C)? , Clearly different in heat resistance and transparency.

That is, the copolyamide (polyamide D) is a polyamide obtained by the polycondensation reaction between metaxylylenediamine and a dicarboxylic acid or their nylon salts, which is proposed in Japanese Patent Publication No. 56-23792 together with the polyamide (polyamide B). It is a contained polymer, and although the crystallization rate is low, it is similar to polyamide (polyamide B).
It shows the property as a crystalline polymer, and is whitened by heating and hot water treatment under pressure.

On the other hand, the polyamide composition (polyamide C) used in the present invention is composed of the copolyamide (polyamide A) and the polyamide (polyamide B) constituting the composition.
As long as the mixing ratio of is within the range presented in the present invention, hot water under pressure, there is no whitening by heat treatment such as pressurized hot water treatment, as a result, the multilayer structure of the present invention is good. The transparency can be maintained.

Therefore, the present invention can be achieved by using a copolyamide having a component unit composition outside the range presented in the present invention or a polyamide composition having a ratio outside the range presented in the present invention, and already known polyamides. It is difficult to obtain a multilayer structure having both heat resistance and transparency as is clear, and a copolyamide (polyamide A) and a polyamide (polyamide B) having a mixing ratio within the range proposed by the present invention are used. By using a polyamide composition (polyamide C) consisting of (1) and (2), a multilayer structure having both practical heat resistance and transparency can be obtained.

For melt-mixing the copolyamide (polyamide A) and the polyamide (polyamide B), an extruder equipped with a heating facility,
Equipment such as a kneader that can melt and knead polyamide is used.

Among them, melt extrusion using an extruder, after granulating,
It is preferable to use coextrusion or co-injection molding in consideration of workability during molding.

Also, pellets of copolyamide (polyamide A) and polyamide (polyamide B) are mixed well in the solid state,
The mixed pellets can be directly subjected to coextrusion or coinjection molding.

Examples of the other thermoplastic resin used together with the copolyamide (polyamide C) in the present invention include polyolefin, polystyrene, polyester, polycarbonate and polyamide.

Examples of the polyolefin include polyethylene, polypropylene, two or more kinds of polyolefin copolymers such as ethylene, propylene and butene, and a mixture thereof.

Examples of the diol component that can be used as a raw material for the polyester include ethylene glycol, a diol component unit mainly composed of cyclohexanedimethanol, and neopentyl glycol, propylene glycol, butanediol, diethylene glycol, bis (hydrocyethoxy) benzene, etc. it can.

Examples of the dicarboxylic acid component as the other raw material of the polyester include dicarboxylic acid component units mainly containing terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, as well as adipic acid, sebacic acid and hexahydroterephthalic acid.

As the polyester using the above components as raw materials, specifically,
PET, polycyclohexane dimethylene terephthalate,
Examples thereof include polycyclohexane dimethylene isophthalate, polyethylene naphthalene dicarboxylate, and a copolyester mainly composed of component units of the polyester.

Further, polyesters containing an oxy acid component unit such as paraoxybenzoic acid in a part of the diol and dicarboxylic acid component units can also be used.

These polyesters can be used alone or as a mixture.

Polycarbonate is a polycarbonate mainly composed of a carbonic acid ester component unit of bisphenol A.

Polyamide means nylon 6, nylon 66, nylon 1
1, a copolyamide mainly composed of an aliphatic polyamide such as nylon 12, nylon 46 and nylon 610, and a component unit forming the polyamide.

Further, as the thermoplastic resin that can be used in the present invention,
The polyolefins, polyesters, polycarbonates and polyamides exemplified above can be used by mixing with each other as long as the transparency is not completely lost.

The multilayer structure of the present invention means a sheet, a film, a tube and a bottle composed of a layer made of a polyamide composition (polyamide C) and a layer made of another thermoplastic resin,
It means a container such as a cup or a can, and a bag-like object.

In the multilayer structure, at least one layer composed of the polyamide composition (polyamide C) must be present, and at least one layer composed of another thermoplastic resin must be present.

In the case of containers intended for water-containing foods and beverages that need to be hot-filled, the inner layer is usually made of a thermoplastic resin other than polyamide so that the polyamide layer does not absorb water and deteriorate the gas barrier properties and mechanical properties. It is preferable that

In addition, an adhesive resin layer is provided between the layer of the polyamide composition (polyamide C) and another thermoplastic resin or between two different thermoplastic resin layers in order to improve the adhesive force between the layers. Multilayer structures are also included in the invention.

Further, the present invention also includes a multi-layered structure provided with a layer of a composition in which an adhesive resin is melt-mixed with a thermoplastic resin such as polyester, polyamide, polycarbonate and polyolefin in order to improve the adhesive force between layers.

For example, it is possible to use polyethylene, polypropylene or a copolymer of olefins such as ethylene, propylene and butene modified as an adhesive resin of polyamide composition (polyamide C) and polyolefins. Further, for adhesion between polyamide and polyester or polycarbonate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid copolymer alkali or alkaline earth metal cross-linked product and ethylene- Acrylic ester-based copolymers and the like can be used.

The multilayer structure of the present invention is produced by coextrusion based on the inflation method, T-die method, etc., sandwich molding in which two or more kinds of molten resins are sequentially injected into a mold, and co-injection molding called two-color molding. .

Sheets, films, tubes and containers produced by co-extrusion or co-injection molding can be used as they are, or can be used as container-like or bag-like products by some heating and heat-sealing or other adhering methods. It is used as a container such as a bottle or cup after being subjected to secondary processing including stretching such as blow molding and deep drawing including parison.

In addition, the sheet and the film may be used as a bag-like material after stretching by heat sealing or another adhesion method.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Reference Examples, Examples and Comparative Examples.

The method of measuring the characteristics used is as follows.

(1) Measurement of haze: According to JIS K-6714 or ASTM D883-62T.

Using Digital Density Meter ND-504AA manufactured by Nippon Denshoku Industries Co., Ltd. (2) Shrinkage measurement: Mark lines are drawn in the vertical and horizontal directions of the film and container,
The length of the marked line before and after the treatment was measured and determined from the following formula.

a ₀ , b ₀ : Length of vertical and horizontal marking lines before treatment a, b: Length of vertical and horizontal marking lines after treatment (3) Measurement of oxygen permeability: OXTRAN 100A manufactured by Modern Control (4) ) Glass transition temperature [T ₉ ]: Glass transition temperature obtained by DSC method SSC / 560S manufactured by Seiko Denshi Co., Ltd. Temperature rising rate: 20 ° C / min (5) Measurement of relative viscosity [ηrel.]: Resin to be measured 1 g Is dissolved in 100 ml of 96% sulfuric acid and measured at a temperature of 25 ° C Reference example Charge 3100 g of adipic acid, 1640 g of isophthalic acid and 910 g of terephthalic acid to a reaction tank with an internal volume of 20 equipped with a stirrer, jacket and dephlegmator, and circulate heat The adipic acid was melted by heating with an apparatus. Next, 4990 g of metaxylylenediamine (hereinafter abbreviated as MXDA) in molten adipic acid in which powdered isophthalic acid and terephthalic acid are dispersed.
Was added dropwise to react. During the dropping of MXDA, the reaction temperature was raised from 170 ° C to 240 ° C in 50 minutes.
The temperature was raised to 260 ° C. The reaction was continued at 260 ° C. for 1.5 hours to complete the melt polycondensation reaction.

In the obtained copolyamide, unreacted solid isophthalic acid and terephthalic acid were not observed, and the relative viscosity was 2.35.

Example 1 Using adipic acid, isophthalic acid and terephthalic acid and MXDA as raw materials (raw material composition molar ratio: adipic acid / isophthalic acid / terephthalic acid / MXDA = 58/27/15/100), the same as shown in Reference Example Copolymerized polyamide [glass transition temperature Tg = 123 ° C.] was obtained by the reaction method.

Pellets of this copolyamide and metaxylylene adipamide (hereinafter abbreviated as nylon MXD6) [Tg = 75
C.] Mixed pellets obtained by mixing the pellets in a solid state in a weight ratio of 40:60, polypropylene (manufactured by Mitsubishi Petrochemical Co., Ltd., FY-6C), and modified polypropylene as an adhesive layer of both resin layers (Mitsui Petrochemical Co., Ltd., QF-30
5), using an extruder (45 × 65 × 45 mmφ) and a feed block, and using a T-die method, two outer layers are polypropylene, an intermediate layer is polyamide C of the present invention, and both layers are modified polypropylene. A 5-layer sheet was created.

Next, using a vacuum forming machine, create a sheet with a depth of 26 mm,
A container having an opening diameter of 64 mm and a bottom diameter of 53 mm was prepared.

Water was put in the obtained container, covered with an aluminum foil having a heat seal layer, and sealed by welding with a heat seal machine.

The container containing this water was subjected to pressurized hot water treatment at 120 ° C. for 30 minutes using an autoclave for retort treatment (manufactured by Tommy Seiko Co., Ltd.).

The evaluation results are shown in Table 1, and it was confirmed that the containers of Examples maintained good transparency and original shape even after the pressurized hot water treatment.

The obtained three-kind five-layer sheet was simultaneously biaxially stretched with a tenter type stretching machine (manufactured by Toyo Seiki Seisakusho) at an area stretching ratio of 4 times.

Then, the biaxially stretched film was heat-set at 150 ° C. for 30 seconds, and then hot-water treated under pressure at 120 ° C. for 30 minutes. Tables 2 and 3 show the results of measuring the stretchability and the haze after heating and hot-pressurized water treatment.

Comparative Example 1 Nylon MXD6 (Tg = 75 ° C), polypropylene (manufactured by Mitsubishi Petrochemical Co., Ltd., FY-6C), and modified polypropylene (manufactured by Mitsui Petrochemical Co., Ltd., QF-30) as an adhesive layer for both resin layers.
Using 5), in the same manner as in Example 1, a three-kind five-layer sheet was prepared in which the two outer layers were polypropylene, the intermediate layer was nylon MXD6, and both layers were modified polypropylene.

Next, a container was prepared by the same vacuum forming method as in Example 1 and subjected to pressurized hot water treatment. Table 1 shows the transparency and shrinkability after the pressurized hot water treatment.

Further, as in Example 1, the obtained three-kind five-layer sheet was simultaneously biaxially stretched by using a tenter type stretching machine (manufactured by Toyo Seiki Seisakusho) at an area stretching ratio of 4 times.

Table 2 shows the measurement results of the stretchability and the haze after stretching.

Comparative Example 2 Using adipic acid, isophthalic acid and terephthalic acid and MXDA as raw materials (raw material composition molar ratio: adipic acid / isophthalic acid / terephthalic acid / MXDA = 83/11/6/100), the same as in Reference Example A copolyamide (glass transition temperature Tg = 89 ° C.) was obtained by the reaction method.

This copolyamide, polypropylene (manufactured by Mitsubishi Yuka Co., Ltd., FY-6C), and modified polypropylene (manufactured by Mitsui Petrochemical Co., Ltd., QF-30) as an adhesive layer for both resin layers.
Using 5) and a device similar to that of Example 1, a three-kind five-layer sheet having two outer layers of polypropylene, an intermediate layer of copolyamide and both layers of modified polypropylene was prepared.

Subsequently, a container was created by a vacuum forming method as in Example 1, and then hot water treatment under pressure was performed.

The evaluation results are shown in Table 1.

Further, the obtained three-kind five-layer sheet was subjected to simultaneous biaxial stretching by using a tenter type stretching machine (manufactured by Toyo Seiki Seisakusho) in the same manner as in Example 1 with an area stretching ratio of 4 times. Further, the biaxially stretched film was heat-set at 150 ° C. for 30 seconds and then hot-water treated at 120 ° C. for 30 minutes under pressure.

Tables 2 and 3 show the results of the measurement and evaluation of the stretchability, the haze after heating and hot-pressurized water treatment.

Example 2 Using adipic acid, isophthalic acid and terephthalic acid and MXDA as raw materials (raw material composition molar ratio: adipic acid / isophthalic acid / terephthalic acid / MXDA = 67/27/6/100), the same as shown in Reference Example A copolyamide (glass transition temperature Tg = 107 ° C.) was obtained by the reaction method.

Mixed pellets obtained by mixing the copolyamide pellets and nylon MXD6 pellets at a weight ratio of 55:45, and PET (manufactured by Nippon Unipet Co., Ltd., RT-543).
Parison having a five-layer structure in which the inner and outer layers and the intermediate layer are PET, and the layer between the inner and outer layers and the intermediate layer is the above-mentioned copolyamide. Was molded.

This parison has a blow pressure of 20 kg / cm ² and a blow molding temperature of about 110 ° C.
Blow molding was performed to obtain a 5-layer bottle having an internal volume of 1.5. Table 4 shows the thickness of each layer of the 5-layer bottle and the evaluation results.

Comparative Example 3 In the same manner as in Example 2 except that nylon MXD6 was used alone instead of the mixed pellets of copolyamide and nylon MX6, the inner and outer layers were the PET, and the layer between the inner and outer layers was the middle layer. Formed a parison having a five-layer structure of Nylon MXD6.

The parison obtained was blown at a pressure of 20 Kg / cm ² , at a blow molding temperature of 85-
Blow molding was performed at 95 ° C to obtain a 5-layer bottle having an internal volume of 1.5.

The thickness of each layer of the obtained 5-layer bottle and the evaluation results are shown in
Shown in the table.

In this comparative example, it was attempted to carry out blow molding at the same blow molding temperature as in Example 2, but deformation due to the weight of the parison, or whitening / crystallization of the nylon MXD6 layer occurred.
It was difficult to blow mold. Further, even when molding was possible, the obtained bottle had uneven thickness or whitening.

Example 3 Using adipic acid, isophthalic acid, terephthalic acid and MXDA as raw materials (raw material composition molar ratio: adipic acid / isophthalic acid / terephthalic acid / MXDA = 60/25/15/100), same as described in Reference Example A copolyamide (glass transition temperature Tg = 120 ° C.) was obtained by the method of 1.

Pellets of this copolyamide and nylon MXD6 (Tg
= 75 ° C) pellets mixed in a solid state at a weight ratio of 60:40, low density polyethylene (Nippon Petrochemical Co., Ltd., Nisseki Lexlon M201), nylon 6-nylon 66 Polymerized polyamide (Novamid 2030 manufactured by Mitsubishi Kasei Co., Ltd.) and modified polyethylene (Nippon Petrochemical Co., Ltd. manufactured by Nippon Petrochemical Co., Ltd., Nisseki N Polymer R1100) as an adhesive layer between the polyamide resin and polyethylene are provided in four extruders (45 mmφ, 65 mmφ, 45 mmφ, 40 mmφ) and a feed block, and by T-die method, low density polyethylene in one outer layer, the copolymerized polyamide of the present invention in the intermediate layer, nylon 6-nylon 66 type copolymerized polyamide in the other outer layer and the outer layer A four-kind four-layer sheet having an adhesive layer between the intermediate layer and the intermediate layer was prepared.

Then, the obtained multilayer sheet was simultaneously biaxially stretched to a fourfold area magnification using a stretching machine (manufactured by Toyo Seiki Seisakusho Co., Ltd.).

Next, two obtained biaxially stretched films were stacked and heat-sealed with the polyethylene layer as a welding layer to prepare a bag-shaped product.

Table 5 shows the results of evaluation of the workability and appearance during stretching, and the shrinkage during heat sealing and hot water filling.

Comparative Example 4 One outer layer was prepared using the same equipment and materials as in Example 3 except that nylon MXD6 (Tg = 75 ° C.) was used alone instead of the mixed pellets of copolyamide and nylon MXD6. Low density polyethylene, nylon MXD6 in the middle layer,
Nylon 6-nylon 66 type copolyamide in the other outer layer and an adhesive layer between the outer layer and the intermediate layer 4
A seed 4-layer sheet was prepared.

Then, the obtained multilayer sheet was simultaneously biaxially stretched to a fourfold area magnification using a stretching machine (manufactured by Toyo Seiki Seisakusho Co., Ltd.).

Furthermore, by stacking two obtained biaxially stretched films and heat-sealing the polyethylene layer as a fusion layer,
A bag was created.

Table 5 shows the evaluation results of the workability and appearance during stretching, and the shrinkage during heat sealing and hot water filling.

Example 4 Using adipic acid, isophthalic acid, terephthalic acid and MXDA as raw materials (raw material composition molar ratio: adipic acid / isophthalic acid / terephthalic acid / MXDA = 60/25/15/100), the same as described in Reference Example Copolymerized polyamide (glass transition temperature Tg = 120 ° C.) was obtained by the reaction method of 1.

This copolyamide pellet and nylon MXD6 pellet were mixed in a solid state at a weight ratio of 50:50, respectively, and mixed pellets and polycarbonate (Mitsubishi Gas Chemical Co., Ltd., Iupilon S2000) were separately injection molded. Machine is used to sequentially inject into the same mold, the inner and outer layers are made of polycarbonate, and the middle layer is made of the above copolyamide and nylon.
A parison having a three-layer structure, which is a mixture of MXD6, was molded.

The parison obtained was blown at a pressure of 20 Kg / cm ² , at a blow molding temperature of 160.
Blow molding was performed at ˜180 ° C. to obtain a three-layer bottle having an inner volume of 1.

The three-layer bottle obtained here has excellent transparency, and as shown in Table 6, it is hardly deformed even when it is filled with hot water at 95 ° C, and has a high oxygen barrier performance. Had.

For comparison, the evaluation results of the above-mentioned polycarbonate single layer are also shown in Table 6.

Comparative Example 5 The same apparatus and materials as in Example 4 were used except that nylon MXD6 was used alone instead of the mixture of copolyamide and nylon MXD6. The inner and outer layers were polycarbonate and the middle layer was nylon MXD6. 3 A parison having a layered structure was molded.

Next, the parison obtained was blow-molded at a blow pressure of 20 Kg / cm ² and a blow-molding temperature of 160 to 180 ° C, but the nylon MXD6 layer crystallized and was difficult to process, or the bottle obtained barely had a nylon layer. Was white and had poor transparency, and the nylon MXD6 layer and the polycarbonate layer were easily peeled off, resulting in lack of practicality.

Example 5 Sebacic acid, isophthalic acid and terephthalic acid and MXDA were used as raw materials (raw material composition molar ratio: sebacic acid / isophthalic acid / terephthalic acid / MXDA = 65/25/15/100), same as described in Reference Example Copolymerized polyamide (glass transition temperature Tg = 93 ° C.) was obtained by the reaction method of 1.

This copolyamide pellet, sebacic acid and MXDA
Polymethaxylylene sebacamide (hereinafter referred to as Nylon MXD10) pellets obtained by polycondensation reaction with and mixed with each other in a solid state at a weight ratio of 60:40, and PET (Nippon Unipet Co., Ltd.) Made, Unipet R
T543) are sequentially injected into the same mold using different injection molding machines, the inner and outer layers are PET, and the middle layer is a composition layer composed of a mixture of the above-mentioned copolymerized polyamide and nylon MXD3.
A parison having a layered structure was molded.

Next, the obtained parison was blow molded at a blow pressure of 20 Kg / cm ² and a blow molding temperature of 95 to 105 ° C. to obtain a three-layer bottle having an inner volume of 1.

The obtained three-layer bottle has excellent transparency, and, as shown in Table 7, assuming pasteurization, it is hardly deformed even when immersed in hot water at 75 ° C, and is excellent. It had an oxygen barrier performance.

Comparative Example 6 The same apparatus, materials and method as in Example 6 were used except that nylon MXD10 was used alone instead of the mixed pellets of copolyamide and nylon MXD10.
A parison having a three-layer structure of PET and nylon MXD10 as an intermediate layer was molded.

Next, the obtained parison was blow molded at a blow pressure of 20 kg / cm ² and a blow molding temperature of 85 to 95 ° C. to obtain a three-layer bottle having an inner volume of 1.

When the obtained bottle was immersed in a temperature of 75 ° C. as in Example 5, as shown in Table 7, a larger shrinkage was recognized as compared with the bottle of the present invention shown in Example 5.

[Effect] By using the present gas barrier multi-layer structure for a multi-layer structure such as a container or a bag, it is easily deformed by external force or internal pressure during hot water treatment or pressurized steam treatment for sterilization and disinfection. It becomes possible to overcome the drawback of the resin packaging material.

Further, the multilayer structure obtained by the present invention maintains good transparency and gas barrier property even when subjected to hot water treatment or retort treatment and further high temperature filling of foods and beverages.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Momose 5 Examiner, 1028 Kitaya, Hadano City, Kanagawa Prefecture Hitomi Morita

Claims (1)

[Claims] 1. A 55 to 70 mol% aliphatic dicarboxylic acid,
20 to 30 mol% isophthalic acid and 5 to 20 mol% terephthalic acid, and 30 to 45 mol% aromatic dicarboxylic acid consisting of isophthalic acid and terephthalic acid
40 to 60% by weight of a copolyamide (polyamide A) obtained from a polycondensation reaction of dicarboxylic acid with meta-xylylenediamine and a polycondensation reaction of aliphatic dicarboxylic acid with meta-xylylenediamine. To 60% by weight of polyamide (polyamide B) at least one layer of a polyamide composition (polyamide C) and at least one layer of another thermoplastic resin are joined together and are excellent in transparency and heat resistance Barrier multi-layer structure