JP2555078B2 - Heat-resistant polyester container having gas barrier properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention is a multi-layer polyester container, which has a high gall barrier property and thus can be distributed at room temperature and can be stored for a long period of time. In addition to being capable of being stored for a long period of time, the contents (food) are not transferred to another container, and the container is used as it is for boiling heating, microwave heating, and grill oven heating (220
The present invention relates to a heat-resistant multi-layer polyester container having a high gas barrier property, which is capable of (° C. Or lower).

B. Conventional technology Using ethylene terephthalate as the main repeating unit,
Add crystallization accelerators to thermoplastic polyester (PET) and heat-set during thermoforming or in a later step,
A method of imparting heat resistance (220 ° C. or lower) is known (Japanese Patent Laid-Open No. 59
-62660), and many heat resistant containers are commercially available. In the heat-resistant PET container, the contents (food) are not transferred to another container, and the heating of the container is performed by boiling, microwave oven and grill oven heating. In particular, since it can be heated in the grill oven, it is possible to attach kogation to the food surface. Therefore, the use of the container is
It was expected to grow more and more, but there were the following problems,
At present, it is used only for limited purposes.
That is, it is necessary to increase the crystallinity of PET in order to impart heat resistance to the container. As a result, the impact strength is reduced and the container is easily damaged. As a countermeasure against this, a structure in which thin-layer PET with suppressed crystallinity is laminated is also found, but it does not have sufficient strength. To make matters worse, if the container is made thicker and a rigid container is made, the impact resistance will decrease,
There was a big problem that the container was more likely to be damaged. Further, since the gas barrier property of the container is poor, it is necessary to store the food at a low temperature (freezing or refrigerating) when the food is stored in this container for a long period of time. Therefore, worse, the PET container having a higher degree of crystallinity has a lower impact strength at a low temperature and is more likely to be damaged.

Therefore, as a method of improving these drawbacks and further greatly improving the long-term storage stability of food at room temperature, a method of compounding another functional resin such as a gas barrier resin in the PET layer is considered. Therefore, a polyvinylidene chloride (PVDC) or polyacrylonitrile (PAN) was compounded in the PET layer to create a heat-resistant multi-layer PET container with gas barrier properties.
It had a strong coloring and odor and could not be used.

On the other hand, the saponification product of ethylene-vinyl acetate copolymer (EVOH), which has the best gas barrier property, has almost no coloring or odor when heated in a grill oven (220 ° C), and thus solves the above problems. Considered an effective resin.
However, as an adhesive resin for adhering the PET layer and the EVOH layer, an ethylenically unsaturated carboxylic acid, or an acid anhydride thereof (for example, maleic anhydride) added or grafted, polyolefin, ethylene-vinyl acetate copolymer ,
When ethylene-acrylic acid ester copolymer, ethylene-acrylic acid copolymer, or metal salt thereof is used, when the grill oven is heated (220 ° C), not only is the adhesive resin colored and the odor is severe, but it also adheres. Due to insufficient properties, peeling occurred at the interface of the adhesive layer and it could not be used.

C. Problems to be Solved by the Invention An EVOH / PET composite container is mentioned as a container further imparting excellent gas barrier properties without impairing the performance of a PET container having good heat resistance. Since this container has a high gas barrier property, it can be distributed at room temperature and can be stored for a long period of time, and the contents (food) are not transferred to another container. As it is, it is an excellent container that can be used for boil heating, electronic lens heating, and grill oven heating (220 ° C or less). However, there is almost no adhesive resin that effectively adheres the PET layer and EVOH layer, and even if it is heated, when the grill oven is heated (220 ° C), the adhesive resin is colored and the odor is severe. Not only that, because of insufficient adhesion, peeling occurred at the interface of the contact layer, so that it could not be used at all.

Therefore, the inventors of the present invention have made a diligent study on a heat-resistant polyester container having a PET layer and an EVOH layer. As a result, when the grill oven is heated (220 ° C.), there is almost no coloring of the adhesive resin and odor, Moreover, not only peeling is not observed at the interface of the contact layer, but surprisingly the impact strength of the container has increased, damage of the container is unlikely to occur, as a result of increasing the thickness of the container and making a rigid container The possibility was discovered and the present invention was completed.

D. Means for Solving the Problems The present invention provides an ethylene-vinyl acetate copolymer saponification having an ethylene content of 25 to 60 mol% and a saponification degree of a vinyl acetate component of 90 mol% or more, preferably 96 mol% or more. (A) layer having a heat resistant polyester (B) layer containing at least one crystallization accelerator selected from the following D to G groups on at least one side of the material (A) layer. A gas barrier having a thermoplastic polyester adhesive resin (C) layer in between, and having a shrinkage rate of 10% or less in the container body (vertical direction) when heated in an oven at 220 ° C for 30 minutes A heat-resistant multi-layer polyester container having properties.

E. More Detailed Description of the Invention Hereinafter, the present invention will be described in more detail.

PET used in the present invention has ethylene terephthalate as a main constituent unit, and ethylene terephthalate unit as a main constituent unit.
It means a polyester containing 80 mol% or more, preferably 90 mol% or more, and can contain a dicarboxylic acid other than terephthalic acid or a glycol component other than ethylene glycol. Incidentally, as dicarboxylic acids other than terephthalic acid, aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl-4,4 dicarboic acid, oxalic acid, malonic acid, succinic acid, Aliphatic dicarboxylic acids such as glutanoic acid, adipic acid, pimelic acid, cork acid, azelaic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid may be used, and one or more of these may be used. I can. Further, glycol components other than ethylene glycol include 1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, 9-
Aliphatic glycols such as nonanediol, diethylene glycol and triethylene glycol, and alicyclic diols such as cyclohexanediol and cyclohexanedimethanol can be used, and one or more of these can be used. Since the molecular weight of the polyester has a great influence on the sheet molding or the physical properties of the container, it is desirable that the specific year is 0.60 dl / g or more, preferably 0.70 dl / g or more. The intrinsic viscosity referred to here is a value measured at 30 ° C. in a phenol / tetrachloroethane mixed solvent (1: 1 weight ratio). Further, in order to increase the crystallization rate of the polyester, which is practically important in molding a heat resistant container, a method of adding a crystallization accelerator to a polymer is particularly effectively utilized in the present invention. Here, the crystallization accelerator is selected from the following D to G groups. Examples of the group D include inorganic compounds having a fine particle size (2 to 3 μm or less), specifically, talc, silica, calcium carbonate, titanium dioxide, and magnesium oxide. They are,
The PET is generally used in a proportion of 0.01 to 5% by weight. Examples of the E group include polymers of olefins having 2 to 6 carbon atoms, such as low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polyisopropylene, polybutene, poly-4-methyl. Examples include penten. These are used in a proportion of 1 to 15% by weight, more preferably 2 to 8% by weight, based on the PET. Group F includes sodium salts or potassium salts of organic acids having 7 to 30 carbon atoms, and Group G includes sodium salts or potassium salts of polymers having a carboxyl group.
Specific examples of these FG groups include sodium stearate, sodium benzoate, sodium salts of ethylene-acrylic acid or methacrylic acid copolymers (such as ionomers), sodium salts of styrene-maleic anhydride copolymers (completely or Partially neutralized salts). The amount of these added to the PET is generally 0.01 to 5% by weight for the organic acid salt and 0.1 for the polymer salt having a carboxyl group.
~ 10% by weight.

In addition, since the final product is exposed to high temperature for a long time, it is effective to add 0.05 to 5% by weight of a heat stabilizer to PET. Further, one or more heat stabilizers shown below are often added. Examples of heat stabilizers include alkylated substituted phenols, bisphenols, substituted bisphenols, thiobisphenols, polyphenols, thiobisacrylates, aromatic amines, organic phosphites, and polyphosphaides, among which aromatic amines. Examples of include primary polyamines, diallylamine, bisdiallylamine, alkylated diallylamine, ketone-diallylamine condensation products, aldehyde-amine condensation products, and aldehyde-amines. Further, more preferable heat stabilizers include polyphenols having two or more phenol ring structures in the compound, for example, tetrakis [methylene 3- (3,5-di-t-
Butyl-4-hydroxyphenyl) -propionate]
Methane and 1,3,5-trimethyl-2,4,6-tris (3,5
-Di-t-butyl-4-vitroxybenzyl) benzene and the like. Among them, tetrakis [methylene 3- (3,5-di-t-butyl-4-vitroxyphenyl) -propionate] methane is particularly preferably used.
In addition, when these are mixed, other additives (plasticizer, lubricant, antistatic agent, especially colorant, etc.) can be freely used within the range that the effects of the present invention are not impaired. Further, various CO ₂ gas generating agents, cross-linking agents, and auxiliaries can be added depending on the purpose in order to form a foamed structure or a cross-linked structure by heat, ultraviolet rays, electron beams, or the like.

It is important to uniformly disperse the above-mentioned crystallization accelerator, heat stabilizer, and other additives in PET because it has a great influence on the performance of the final product container, but the method of adding and uniformly dispersing them is important. , Not particularly limited, a method of adding an additive such as the crystallization accelerator during the polymerization of PET, PE
T additive is dry blended and melt extruded, a method of blending PET into a pelletized master pellet at a desired ratio, dry additive of PET and melt extrusion,
Examples include a method of directly using a pelletized resin and a method of directly dry blending an additive with PET. Preferably, the method of adding during the polymerization of PET, or P
An example is a method in which an additive is dry-blended with ET, melt-extruded, and a pelletized resin is directly used. Obtained PE
In some cases, the T composition has an intrinsic viscosity of 0.65 to 1.2, preferably 0.70 to 1.0, when measured in a phenol / tetrachloroethane mixed solvent (1: 1 weight ratio) at 30 ° C. The operation of increasing the intrinsic viscosity is performed by, for example, a solid-phase polymerization method which is usually used for the pellet.

The EVOH used in the present invention has an ethylene content of 20 to 60 mol%, preferably 25 to 55 mol%, and a saponification degree of the vinyl acetate component of 90% or more, preferably 96% or more of ethylene-vinyl acetate copolymer. It is a saponified polymer. When the ethylene content is 20 mol% or less, the molding temperature becomes close to the decomposition temperature, and molding becomes difficult. On the other hand, when the ethylene content is 60 mol% or more, the gas barrier property is deteriorated, which is not preferable. Further, EVOH having a vinyl acetate component with a saponification degree of less than 96%, particularly less than 90%, is not preferable because a gelled substance is likely to occur frequently and the gas barrier property is low. Furthermore, EVOH is a silicon compound in the molecule,
It is more desirable to contain 0.0005 to 0.2 mol%. Such, when using EVOH containing a silicon compound, the EVOH layer of the multilayer container under moisture absorption, in the empty state especially without food, when heated for 30 minutes in a 220 ℃ microwave oven, EVOH layer and It is preferable because it improves the interlayer adhesion of the adhesive resin layer. In some cases, it is preferable to use the silicon compound-containing EVOH by mixing the silicon compound-containing EVOH with EVOH not containing a silicon compound. And EVOH
The silicon unit contained in is selected from the following (I), (II) and (III).

[Wherein n is 0 to 1, m is 0 to 2, R ¹ is a lower alkyl group having a lower alkyl group, an allyl group or an aryl group, R ² is an alkoxyl group having 1 to 40 carbon atoms, The alkoxyl group may have a substituent containing oxygen. R ³ is hydrogen or a methyl group, R ⁴ is hydrogen or a lower alkyl group, R ⁵ is an alkylene group or a divalent organic residue in which chain carbon atoms are bonded to each other by oxygen or nitrogen,
R ⁶ is hydrogen, halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, R ⁷ is an alkoxyl group or an acyloxyl group (wherein the alkoxyl group or the acyloxyl group has a substituent having oxygen or nitrogen). R ⁸ is hydrogen, halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, and R ⁹ is a lower alkyl group. ] More specifically, R ¹ is a lower alkyl group having 1 to 5 carbon atoms, or 6 to 18 carbon atoms.
Represents an allyl group having 1 to 5 carbon atoms, or an allyl group having 6 to 18 carbon atoms, R ⁴ represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and R ⁵ represents a carbon number. 1
An alkylene group of ~ 5 or a divalent organic residue in which chain carbon atoms are mutually bonded by oxygen or nitrogen,
R ⁶ is hydrogen, halogen, a lower alkyl group having 1 to 5 carbon atoms,
Shows a 1-5 lower alkyl group having an allyl group or an allyl group having 6 to 18 carbon atoms, 6 to 18 carbon atoms, R ⁷ is an alkoxyl group or the number 1 to 40 alkoxyl group or acyloxy group (wherein the carbon An acyloxyl group may have a substituent having oxygen or nitrogen), and R ⁸
Represents hydrogen, halogen, a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a lower alkyl group having 1 to 5 carbon atoms and having an allyl group having 6 to 18 carbon atoms, and R ⁹ is A lower alkyl group having 1 to 5 carbon atoms is shown. And, vinyltrimethoxysilane, vinyltriethoxysilane and the like are preferably used. The EVOH is according to ASTM-D1238-65T,
Melt viscosity index measured at 190 ℃, 2160g load is 0.1-25g / 1
It is 0 minutes, preferably 0.3 to 20 g / 10 minutes. Further, it is free to use one or more additives (various resins, antioxidants, plasticizers, coloring agents, etc.) within the range where the effects of the present invention are not impaired. In particular, it is preferable to add a hindered phenol-based or hindered amine-based heat stabilizer in an amount of 0.01 to 5% by weight as a measure against EVOH thermal stability and gel generation.

One of the representative examples of the thermoplastic resin used in the present invention is a polyester-amide copolymer having an ester group / amide group molar ratio of 90/10 to 10/90. The carboxylic acid component of the copolymer includes terephthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, aromatic dicarboxylic acid such as diphenyl-4,4-dicarboxylic acid, oxalic acid, malonic acid, succinic acid. ,
Aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, cork acid, azelaic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid can be used, and one or more of these can be used. As the glycol component, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentadiol, 1,6-hexanediol, 9
Examples include aliphatic glycols such as nonanediol, diethylene glycol and triethylene glycol, and alicyclic diols such as cyclohexanediol and cyclohexanedimethanol, and one or more of these can be used. If the amount is small, trivalent or higher carboxylic acids or alcohols can also be used. Further, as the amine component, piperazine, or diamines such as pentaethylenediamine, hexaethylenediamine, nonaneethylenediamine, decaethylenediamine, undecaethylenediamine, nodecaethylenediamine, and laurinlactam, undecaneamide, hexamethylosebacamide, hexamethyleneadipamide. Acid amides such as amide, ω-aminoheptanoic acid, ω-aminononanoic acid
Different types or more can be used. A polyester-amide copolymer obtained by co-condensing these, a melt-mixed composition of the copolymer and polyester or polyamide, and a mixed composition of polyamide and polyester are used. Then, when the ester group in these polyesteramides (the composition in the case of a mixed composition) is 90 mol% or more, or when the amide group is 90 mol% or more, the adhesion between the heat-resistant PET and EVOH Not enough power. The ester / amide group molar ratio is 8/15
~ 15/85 is more preferred. And, preferably, one or more of terephthalic acid, adipic acid, azelaic acid and succinic acid as a dicarboxylic acid component, one or more of ethylene glycol and 1,4-cyclohexanedimethanol as a glycol component, and piperazine as an amine component. And a polyester-amide having an ester group / amide group molar ratio of 70/30 to 10/90, or one or more of terephthalic acid, adipic acid, azelaic acid and succinic acid as a dicarboxylic acid component, Ethylene glycol and 1,4 as glycol components
Examples include a composition in which 10 to 80% by weight of 6 nylon, 6-66 nylon, 66 nylon, 6-12 nylon, and 6-9 nylon are melt-mixed with a polyester containing at least one of cyclohexanedimethanol.

As a more preferred example of the thermoplastic polyester system used in the present invention, Al, Cr, Sn, Ge and Si selected in the group consisting of a dicarboxylic acid component and a glycol component, one or more elements The dicarboxylic acid component
Examples of the modified polyester include 0.1 to 5 mol per 100 mol. Among these, as a metal element,
Al and Cr are preferable because a large adhesive force can be obtained, and Al is particularly preferable. On the other hand, if the content is less than 0.1 mol, the effect is insufficiently expressed, while if it is more than 5 mol, undesirable phenomena such as gelation and coloring of the polymer occur. In the present invention, these elements include a mode in which they are mixed in the polyester as a compound containing these elements, and a mode in which these elements are present in a state of being chemically bonded to the polyester molecule. Is preferable because high adhesion can be obtained. As a method of binding the above-mentioned element to the polyester, a method of adding a compound of the above-mentioned element (particularly preferably a metal ester, a chelate compound, an organic acid salt or the like) at the time of the polymerization of the polyester and performing the polymerization can be used. Examples of the Al compound include aluminum acetylacetonate, aluminum ethoxide, aluminum propoxide, and reaction products of these compounds with monocarboxylic acid. As the Cr compound, chromium acetylacetonate or a monocarboxylic acid salt of chromium, and as the Sn compound, tetraethylstannate, tetrapropylstannate, tetrabutylstannate or a reaction product of these with monocarboxylic acid, a Ge compound. Examples thereof include germanium dioxide, and examples of the Si compound include methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, and diphenyldimethoxysilane. Particularly preferred are aluminum acetylacetonate, aluminum ethoxide, and aluminum propoxide. It is preferable to add these compounds to the polyester polymerization reaction system at 230 ° C. or lower after the polyester polymerization reaction is almost completed. As the form of addition, there is a method of dissolving in a diol or a method of dissolving in a monocarboxylic acid or its ester in order to prevent gelation of the polymer during polymerization. The dicarboxylic acid component constituting the thermoplastic polyester containing these elements, terephthalic acid,
Isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl-4,
4 aromatic dicarboxylic acids such as dicarphonic acid, oxalic acid,
Aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutanoic acid, adipic acid, pimelic acid, corkic acid, azelaic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid are listed, and one or more of them can be used. The above can be used. The glycol component may be ethylene glycol, 1,3-propanediol,
1,4-butanediol, 1,5-pentanediol, 1,6-
Aliphatic glycols such as hexanediol, 1,9-nonanediol, diethyl glycol and triethylene glycol, and cycloaliphatic diols such as cyclohexanediol and cyclohexanedimethanol can be used. Use one or more of these. Can be done. Furthermore, a trivalent or higher carboxylic acid or alcohol can be used in a small amount. Preferably, terephthalic acid, isophthalic acid and adipic acid are used as the dicarboxylic acid, and ethylene glycol and diethylene glycol are used as the diol. The intrinsic viscosity of the obtained thermoplastic polyester is preferably 0.50 dl / g or more, and further 0.
It is preferably 60 dl / g or more. The intrinsic viscosity referred to here is 3 in a phenol / tetrachloroethane mixed solvent (1: 1 weight ratio).
It is a value measured at 0 ° C.

In the present invention, as a method for obtaining a heat-resistant multilayer container having a gas barrier property, the EVOH and PET are extruded through an adhesive resin, a laminating method, a dry laminating method, a coextrusion laminating method,
Multi-layer sheet and parison are obtained by the co-extrusion sheet making method (feed block method or multi-manihole method, etc.), co-extrusion direct blow method, co-extrusion pipe method, co-injection method, various solution coating method, etc. and use these There is a method of obtaining a container or a method of directly obtaining a molded container. In the case of directly obtaining a molded container, the container is treated with a mold heated to a temperature sufficient to achieve a desired crystallinity to impart heat resistance. Mold temperature range is 150 ~ 215
C., preferably 160-220.degree. C. and held in the mold for 2-60 seconds, preferably 2-20 seconds. On the other hand, when a container is obtained from a multi-layer sheet or parison by secondary processing, it is important to immediately give an instruction to the multi-layer sheet or parison immediately after molding in order to minimize the degree of crystallization that occurs after molding. The multi-layer sheet or parison (hereinafter, multi-layer structure) is desired to be heated and thermoformed as rapidly as possible, and the thermoforming temperature range is 110 to 170 ° C.
It is preferably 120 to 160 ° C. In the thermoforming, the water content of the EVOH layer, which is a constituent of the multilayer structure, is not particularly limited, but is preferably 0.01 to 5% or less. Then, the thermoformed container is heat-treated in a mold heated to a temperature sufficient to achieve a desired crystallinity, thereby imparting heat resistance. The mold temperature range is
150 ~ 215 ℃, preferably 160 ~ 220 ℃, 2 ~ 60
Hold in the mold for seconds, preferably 2-20 seconds. Since the molded product has a high temperature and is flexible, it is necessary to be careful when removing it from the mold. The shape of the molded product is adjusted. The molded product has a shrinkage ratio of 10% or less, preferably 6% or less, in the container body (vertical direction) when heated in an open range of 220 ° C. for 30 minutes. Here, the shrinkage rate of the container body (vertical direction) is a value obtained by 100 × (dimension before heating−dimension after heating) / dimension before heating.

The shape of the multilayer structure is also not particularly limited, and may be tray-shaped, cup-shaped, or bolt-shaped. When the multilayer structure is secondarily processed into a molded container, the stretching ratio is 20 times or less, preferably 3 to 15 times in terms of area ratio.

The scrap produced by trimming when obtaining a molded product is crushed and directly used or pelletized, and then recovered and used. The recovery method is not particularly limited, but the scrap is crushed, and if it absorbs moisture, it is dried and then dry blended with the raw material PET, the crushed scrap is pelletized and then dried with the raw material PET. There are a method of blending, a method of blending the crushed scrap and the raw material PET into a pellet. The blend ratio of the raw PET composition and the scrap is usually about 2 to 100%. At this time, in order to improve dispersibility and thermal stability and suppress abnormalities during container molding, metal soaps (such as aliphatic or / and aromatic carboxylic acid salts), chelate compounds (such as EDTA), or alkalis or alkalis It may be preferred to add one or more earth metal carboxylates.

In addition, as the constitution of the multilayer structure, PET composition / EVOH / P
ET composition, PET composition / adhesive resin / EVOH / adhesive resin / PE
T composition, PET composition / adhesive resin / EVOH / adhesive resin / PET
Composition / PET, PET composition / Adhesive resin / EVOH / Adhesive resin /
PET, PET / PET composition / Adhesive resin / EVOH / Adhesive resin / PET
Composition / PET, PET composition / Recovered PET composition / Adhesive resin / E
VOH / adhesive resin / PET composition, PET composition / recovered PET composition / adhesive resin / EVOH / adhesive resin / recovered PET composition / PET composition, PET composition / recovered PET composition / adhesive resin Typical examples include / EVOH / adhesive resin / PET composition / PET, PET / PET composition / recovered PET composition / adhesive resin / EVOH / adhesive resin / PET composition. The thickness of each layer is not particularly limited, but generally the total thickness of the container body is 200μ to 2000μ, and the EVOH layer is 2μ.
~ 200μ, the adhesive resin layer is 2μ ~ 200μ.

The thus obtained multilayer container of the present invention has extremely good gas barrier properties, and is a food packaging container having good heat resistance, and not only can the food be stored for a long time at room temperature, but also the food. Without transferring it to another container,
It is a container having excellent properties that can be heated in a boil, a microwave oven, and a grill microwave oven (220 ° C.) as it is. Further, this container is also effective in fields where fragrance is required.

Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited by these examples.

F Example Example 1 EVOH has an ethylene content of 44 mol% and a saponification degree of 9
9.4%, vinyltrimethoxysilane 0.02 mol%, melt index (MI; 190 ° C-2160g) 1.6g / 10min. As a heat resistant PET composition, an unmodified polyethylene terephthalate 100 with an intrinsic viscosity of 0.90dl / g. MI (190 ℃ for parts by weight)
-2160 g) 5.0 g / 10 min 3 parts by weight of low-density polyethylene, 1.2 parts by weight of TiO ₂ as a pigment, and 0.5 parts by weight of Irganox 1010 (made by Ciba-Gaiki) as a heat stabilizer were dry-dried, load axis screw type, vent Pelletization was carried out using a formula 40φ extruder and dried at 150 ° C for 8 hours. As the adhesive resin, polyester obtained by the following method was used. That is, nitrogen gas introduction tube in a 300 ml three-necked flask, stirrer, hexylene glycol 200 ml in a polymerization apparatus equipped with a cooling tube, 0.20 mol of aluminum isopropoxide, 0.10 mol of caprylic acid,
An aluminum compound obtained by adding 0.30 mol of P-oxybenzoic acid and 0.20 mol of acetylacetone and reacting at 100 ° C. was previously mixed with 64 g of bis-β-hydroxyethyl terephthalate, 36.5 g of adipic acid and 1 part of ethylene glycol.
To the solution obtained by adding 5.5 g and 14.9 g of diethyl glycol and reacting at 200 ° C. for 4 hours was added 0.52 mol of tributyl phosphate 25 μ, and 40 ml of antimony trioxide together with the aluminum compound in terms of aluminum atom based on 100 mol of dicarboxylic acid component. After that, while heating up to 260 ℃ and decompressing, 275 ℃ -0.1m
What was polymerized for 90 minutes under mHg decompression was used. This resin has an intrinsic viscosity of 0.61 dl / g and a glass transition temperature of -5 ° C.
It was.

Using these resins, feed block type-3 type 5
A sheet was prepared with a layer coextrusion device. The thickness composition of the sheet is such that both outermost layers have a PET composition of 800μ, an adhesive resin layer has an inner layer of 50μ, and an intermediate layer has an EVOH layer of 50μ.
The obtained sheet is put in a vacuum pressure air forming machine and the sheet temperature is 130
℃, drawing ratio 1, thermoforming with a round cup-shaped mold, mold temperature
Heat setting was performed at 180 ° C. for 10 seconds. The appearance of the obtained container was good, and the shrinkage rate of the container when heated in a microwave oven at 220 ° C. for 30 minutes was 3%. However, the shrinkage rate of the container is a value calculated by 100 × (dimension before heating−dimension after heating) / dimension before heating in the container body (vertical direction).
The appearance of the container after heating was also good. on the other hand,
When the gas barrier property of the EVOH layer of this container at 20 ° C.-65% RH was measured using a model 10/50 manufactured by Mocon Co., 1.8 cc.20 μ / m ² .24 hr. 1.7c in later container
c.20μ / m ² .24hr.atm and both showed very good gas barrier properties.

By the way, a container before heating was filled with salad oil, and a commercially available 100 μ biaxially stretched PET film laminated with a sealant was used to cover the container with an upper lid (heat seal). Then, the container was dropped on a concrete floor surface at 20 ° C., and the drop impact strength (fall height) was measured. As a result, the drop height at which 5 of 10 containers were damaged was 1.5 m or more, indicating good drop impact resistance. It was 1 m at -20 ° C.

Example 2 In Example 1, EVOH was added with an ethylene content of 44 mol%,
Saponification degree 99.4%, MI (190 ℃ -2160g) 1.6g / 10min EVOH
The same procedure as in Example 1 was carried out. 22 containers obtained
When heated in a 0 ° C. microwave oven for 30 minutes, the shrinkage rate of the container showed almost the same value as in Example 1. Although slight delamination was observed in the flange portion of the container, there was no problem in practical use.

Example 3 In Example 1, EVOH was mixed with ethylene content 32 mol%, saponification degree 99.4%, and vinylitol trimethoxysilane 0.03.
Mol%, MI (190 ° C-2160g) 1.6g / 10min Change to EVOH,
Further, the thickness constitution of the sheet and the EVHO layer of the intermediate layer were changed to 20 μ, and the same procedure as in Example 1 was carried out. The obtained container was good, the shrinkage ratio of the container when heated in a 220 ° C microwave oven was 4%, and the appearance of the container after heating was also good. Then, when the gas barrier property of the EVOH layer of the container after heating was measured at 20 ° C.-65% RH, it was 0.6 cc.20 μ / m ² .24 hr.a.
It showed a very good gas barrier property with tm. Further, the container filled with salad oil was dropped on a concrete floor surface at 20 ° C., and a drop impact degree (fall height) was measured. As a result, the drop height at which 5 of 10 containers were damaged was 1.5 m or more.

Example 4 The procedure of Example 1 was repeated except that the low density polyethylene, which is a crystallization accelerator, was replaced with polypropylene. The obtained container was good, the shrinkage ratio of the container when heated in a 220 ° C microwave oven was 4%, and the appearance of the container after heating was also good. And of the container after heating
When the gas barrier property of the EVOH layer at 20 ° C.-65% RH was measured, it showed a very good gas barrier property of 1.6 cc.20 μ / m ² .24 hr.atm.

Example 5 In Example 1, the addition rate of the crystallization accelerator was 3% by weight.
Was carried out in the same manner as in Example 1. The obtained container was good, the shrinkage ratio of the container when heated in the microwave oven at 220 ° C. was 4%, and the appearance of the container after heating was also good. Then, the EVOH layer of the container after heating is at 20 ° C-65
When the gas barrier property at% RH was measured, it was 1.7 cc.20 μ / m ² .
It showed a very good gas barrier property of 24 hr.atm.

Example 6 In Example 1, the adhesive resin was azelaic acid / cyclohexanedimethanol / piperazine (molar ratio 0.50 / 0.05).
9 / 0.41) was carried out in the same manner as in Example 1 except that the polyester-amide having an intrinsic viscosity of 0.75 dl / g (molar ratio of ester group / amide group 18/82) was used. The obtained container was good, and the shrinkage rate of the container when heated in the microwave oven at 220 ° C. was as good as 4%. The appearance of the container after heating was also slightly colored, but it was not a problem in use. When the same drop impact strength as that in Example 1 was measured, the drop height at which 5 of 10 containers were damaged was 1.5 m or more.

Example 7 In Example 1, 80 parts by weight of 6-66 nylon was mixed with 100 parts by weight of modified polyethylene terephthalate containing 35 mol% of isophthalic acid having an intrinsic viscosity of 0.75 dl / g, and a biaxial screw type was used. Pelletization was performed using a vent type 40φ extruder, and the resin was dried in the same manner as in Example 1 except that the resin was dried at 150 ° C. for 8 hours. The ester / amide group molar ratio of this mixed pellet is 60/40. The obtained container was good, and the shrinkage rate of the container when heated in the microwave oven at 220 ° C. was 3.5%, which was good. The appearance of the container after heating was also slightly colored, but it was not a problem in use.

Comparative Example The same procedure as in Example 1 was performed except that EVOH was not used. Although the obtained container was good, the drop impact strength (drop height) when the container was dropped on the concrete floor surface at 20 ° C. was 0.5 m or less. Moreover, when the gas barrier property of the PET layer of the container at 20 ° C.-65% RH was measured,
It has a poor gas barrier property of 97cc.20μ / m ² .24hr and is unusable as a container for long-term food storage at room temperature.

Comparative Example 2 The same procedure as in Example 1 was carried out by changing the heat-resistant PET in Example 1 to a normal PET. The obtained container was good, but when the container was heated in the microwave oven at 220 ° C. for 30 minutes, the shrinkage rate of the container was 65% and it was unusable.

Comparative Example 3 The procedure of Example 1 was repeated except that the adhesive resin was changed to a maleic anhydride-modified ethylene-vinyl acetate copolymer. 30 in a 220 ° C microwave oven
After heating for a minute, the flange portion of the container delaminated,
To make matters worse, the odor was so strong that it could not be used.

G. Effect of the Invention The multi-layer polyester container of the present invention is a heat-resistant multi-layer polyester container having significantly improved gas barrier properties and impact resistance, and the contents (food) can be stored at room temperature for a long period of time. Without, the contents (food) are left as they are for boiling, microwave heating, grill oven heating (22
0 ° C) is possible.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-253541 (JP, A) JP-A-59-143638 (JP, A) JP-A-62-113526 (JP, A) JP-A-60- 135473 (JP, A) JP 59-115327 (JP, A) JP 61-254342 (JP, A) JP 60-97851 (JP, A)

Claims (6)

(57) [Claims] 1. An ethylene-vinyl acetate copolymer saponification product (A) layer having an ethylene content of 25 to 60 mol% and a saponification degree of a vinyl acetate component of 90 mol% or more.
A heat-resistant polyester resin composition (B) layer containing at least one crystallization accelerator selected from the group, and a thermoplastic polyester-based adhesive resin (C) between the layer (A) and the layer (B). ), And the shrinkage rate of the container body (longitudinal direction) is 10 when heated in an oven at 220 ° C for 30 minutes.
% Or less, a heat-resistant multilayer polyester container having gas barrier properties. Group D: Talc, silica, calcium carbonate, titanium dioxide or magnesium oxide Group E: Polymer of olefin having 2 to 6 carbon atoms Group F: Sodium salt or potassium of organic acid having 7 to 30 carbon atoms Salt Group G: Sodium salt or potassium salt of a polymer having a carboxyl group 2. The multilayer polyester container according to claim 1, which has (B) layers on both sides of (A) layer. 3. The multilayer polyester container according to claim 1 or 2, wherein the crystallization accelerator is a polymer of an olefin having 2 to 6 carbon atoms. 4. The multilayer polyester container according to claim 1, wherein the saponified ethylene-vinyl acetate copolymer (A) has a silicon content of 0.0005 to 0.2 mol%. 5. The adhesive resin layer (C) is a polyester-amide adhesive resin having an ester group / amide group ratio (molar ratio) of 90/10 to 10/90. Four
The multilayer polyester container according to any one of items. 6. The adhesive resin layer (C) comprises Al, Cr, Sn, Ge and S.
a thermoplastic polyester containing 0.1 to 5 mol of one or more elements selected from the group consisting of i per 100 mol of the dicarboxylic acid component, or a thermoplastic polyester containing the element in a state of being bound to polyester molecules. The multilayer polyester container according to any one of claims 1 to 4.