JPH0557887B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to coextruded multilayer sheets and structures with excellent heat resistance and gas barrier properties, and further relates to coextruded multilayer sheets with excellent rigidity and suitable for forming deep-drawn containers, and molding therefrom. The present invention relates to multilayer structures such as deep-drawn containers. (Prior art) Linear polyester in general, and polyethylene terephthalate (hereinafter referred to as PET) in particular, has attracted attention as a material for various containers including bottles due to its excellent mechanical and chemical properties. -Represented by the method described in Publication No. 5107
Demand for deep-drawn containers made from PET sheets is also increasing as they have excellent rigidity and gas barrier properties. However, improvements in packaging technology and expansion of packaging applications require the addition of even higher functionality to PET containers.In particular, when considering alternative uses for metal cans and glass containers, it is necessary to use plastics to reduce weight and make them transparent. Although it has many advantages in terms of performance and safety, its lack of performance in terms of gas barrier properties and heat resistance is a hindrance, greatly limiting the development of its applications. As a means of improving the gas barrier properties and heat resistance of such PET containers, we have developed a partially saponified resin of ethylene/vinyl acetate copolymer (hereinafter referred to as EVOH), which is a material with even better gas barrier properties than PET.
That's what it means. ) or a resin composition (hereinafter referred to as modified PAR) consisting of a vinyl resin mainly composed of vinyl resin and aromatic polyester, which is a material with even better heat resistance than PET, and PET (hereinafter referred to as modified PAR) is co-injected with PET and biaxially stretched and blown. The molded multi-layered bottle was published in 1988.
Although it is known from Japanese Patent No. 214047, a multilayer sheet having such a structure with excellent heat resistance and gas barrier properties and a container formed from the same have not yet been put into practical use. (Problems to be solved by the invention) Although it is highly predicted that the composite of PET/EVOH/modified PAR will provide high functionality such as heat resistance and gas barrier, The biggest reason for the delay in its practical application is the problem of adhesion between these materials. PET and denaturation
PAR each has a non-polar molecular structure and exhibits excellent mutual adhesion under coextrusion conditions, whereas EVOH has a polar molecular structure with hydroxyl groups with large molecular cohesive energy, which makes PET
and direct adhesion to modified PAR is not possible at all. Therefore, in order to form a multilayer sheet of PET/EVOH/modified PAR, an adhesive layer is indispensable in the middle, but an adhesive suitable for forming such a sheet has not yet been found. Of course, if the purpose is simply to bond PET and EVOH, adhesives based on acid anhydride group-containing polyolefin, epoxy group-containing polyolefin, or polyurethane have already been put into practical use. In addition, the development of adhesives based on polyamides and polyesters is actively progressing, but adhesives for coextruded multilayer sheets intended for secondary processing such as deep drawing must not only have adhesive strength but also suitability for melt extrusion. It goes without saying that secondary processability, such as aptitude for stretching and stretching, and, if necessary, transparency are also required. However, it is a general tendency that molding processability decreases as the degree of modification progresses through modification techniques such as various copolymers and polymer alloys to improve adhesion. The difficulty of balancing PET/
This can be said to be one of the major reasons for delaying the practical application of highly functional multilayer sheets made of EVOH/modified PAR. (Means for Solving the Problems) The present inventors have solved the above problems, and have developed a product that has excellent rigidity, heat resistance, and gas barrier properties, can maintain transparency if necessary, and is also capable of deep drawing processing. In order to develop a coextruded multilayer sheet that is also provided with stretching and secondary processability, the present invention was arrived at as a result of extensive research, particularly regarding the adhesive layer. That is, the present invention is a multilayer sheet having a structure in which a two-layer adhesive layer is provided between PET and EVOH, and of the adhesive layer, the PET side is made of 10 to 90% by weight of sulfonic group-containing polyester and 90% by weight of aromatic polyester. This is a coextruded multilayer sheet characterized by a resin composition (hereinafter referred to as sulfon group-containing modified PAR) consisting of ~10% by weight, and whose EVOH side is polyamide. Furthermore, the sulfon group-containing polyester used in the sulfon group-containing modified PAR contains 0.5 to 10 moles of zodium sulfoisophthalic acid and/or zodium sulfon terephthalic acid to the total acid component in the sulfon group-containing modified PAR. %
This is a coextruded multilayer sheet characterized in that the polyamide is a copolymerized polyamide containing 5 to 30% by weight of a nylon 66 component. Furthermore, there is a container molded from these coextruded multilayer sheets. The PET used in the present invention is a polyester whose main repeating unit is ethylene terephthalate, and the amount of phthalic acid, isophthalic acid, hexahydrophthalic acid, naphthalene dicarboxylic acid, adipic acid, and zebacin is 10 mol% or less of the total acid component. It is possible to use dicarboxylic acids such as acids, polyhydric carboxylic acids such as trimellitic acid and pyromellitic acid, or oxyacids such as P-oxybenzoic acid as the acid component.
1,2-propanediol in an amount of up to mol%;
Dihydric alcohols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, cyclohexanedimethal, trimethylolpropane, triethylolpropane, pentaerythritol It is possible to use polyhydric alcohols such as the following as the alcohol component. Such PET can be obtained by a conventional melt polycondensation reaction, and if necessary, the degree of polymerization can be further increased by a solid phase polymerization reaction. The EVOH used in the present invention has the trade name “EVAL”
It is a crystalline polymer obtained by saponifying a random copolymer of ethylene/vinyl acetate, as represented by the following: It has polar hydroxyl groups and exhibits extremely excellent gas barrier properties due to its large molecular cohesive energy. In the sulfon group-containing polyester in the sulfon group-containing modified PAR, which is one of the constituent components of the adhesive layer of the present invention, some of the acid components in the polyester include sodium sulfoisophthalic acid and sodium sulfonaterephthalate. It can be easily obtained by a conventional melt polycondensation reaction using an acid, and when a polymer with a high degree of polymerization is required, a solid phase polymerization reaction can also be used. If the amount of copolymerization of sodium sulfoisophthalic acid and/or sodium sulfo-terephthalic acid is 0.5 mol% or more based on the total acid component in the sulfon group-containing modified PAR, the amount of copolymerization of sodium sulfoisophthalic acid and/or sodium sulfioterephthalic acid is 0.5 mol % or more based on the total acid component in the sulfon group-containing modified PAR. and can have sufficient adhesion to polyamide. In addition, when the copolymerization amount is 10 mol% or more, the adhesive force reaches saturation, and no further effect can be expected, and at the same time, the hygroscopic effect of the sulfon group occurs, which does not give good results to the gas barrier properties of EVOH. . The basic properties of sulfonate group-containing polyester are:
It is desirable that the polyester be as close to PET as possible in terms of heat resistance, processability, etc., and this can be solved by using PET containing sulfone groups as the polyester.
Similarly, the aromatic polyester in the modified PAR containing sulfonate groups is composed of an aromatic dicarboxylic acid or a derivative thereof and a dihydric phenol or a derivative thereof. Preferred aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, and the like, and mixtures thereof are particularly preferred in terms of melt processability and overall performance. When such a mixture is used, the mixing ratio is not limited, but terephthalic acid/terephthalic acid/
Isophthalic acid is preferably 9/1 to 1/9 (weight ratio), and particularly 7/3 to 3/7 (weight ratio) from the viewpoint of melt processability and performance balance. Divalent phenol has the following general formula where R ₁ , R ₂ , R ₃ , R ₄ , R ₁ ′, R ₂ ′,
R ₃ ′ and R _{4 ′} are selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group, and a halogenated hydrocarbon group; Alternatively, the alkylidene group may be substituted with one or more halogen groups). The dihydric phenols used in the present invention include:
For example, 2,2-bis(4-hydroxyphenyl)
-propane, 2,2-bis(4-hydroxy-
3,5-dibromophenyl)-propane, 2,2
-bis(4-hydroxy-3,5-dichlorophenyl)-propane, 4,4'-dihydroxyphenyl sulfone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenylketone,
4,4'-dihydroxydiphenylmethane, 2,2
-bis(4-hydroxy3,5dimethylphenyl)propane, 1,1-bis(4-hydroxyphenyl)-ethane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxy Diphenyl, benzoquinone, etc. These may be used alone or as a mixture. In addition, these divalent phenols are para-substituted products,
Other isomers may be used, and ethylene glycol, propylene glycol, etc. may be used in combination with these dihydric phenols. The most typical divalent phenols are 2,
2-bis(4-hydroxyphenyl)propane,
It is commonly called bisphenol A. Such aromatic polyesters are produced by various methods such as solution polymerization, melt polymerization, and interfacial polymerization. Sulfuronic group-containing modified PAR can be obtained by extruding this sulfuronic group-containing polyester and an aromatic polyester using a melt extruder, or by stirring and mixing them while melting them in a reaction can with stirring blades.
A randomization promoting catalyst such as sodium acetate may be added to promote randomization due to the transesterification reaction that occurs during melt blending, resulting in a uniform polymer alloy. Such a modified PAR containing a sulfonate group exhibits a higher glass transition temperature Tg and improves heat resistance as the amount of aromatic polyester increases. The polyamide, which is another component of the adhesive layer of the present invention, is selected from polycapramide, polylaurinlactam, polyhexamethylene adipamide, poly-11-aminoundecanoic acid, and the like. Although these may be used alone, as a copolymer, or as a mixture, a nylon 6,66 copolyamide containing 5 to 30% by weight of a nylon 66 component is particularly preferred. The structure of the multilayer sheet according to the present invention is obtained by extruding PET/sulfon group-containing modified PAR/polyamide/EVOH as basic units from a multilayer die using four extruders dedicated to each resin.
A seven-layer structure of PET/modified PAR containing a sulfon group/polyamide/EVOH/polyamide/modified PAR containing a sulfon group/PET, or a multilayer structure of more than that can be used if necessary. The multilayer sheet obtained by the present invention can be easily improved in rigidity, gas barrier properties, and heat resistance by being heated in a temperature range 20 to 50°C higher than the Tg of the sulfonic group-containing modified PAR, and then subjected to vacuum forming or pressure forming. It can be made into a multilayered structure such as a container with excellent properties. (Function) In the present invention, PET which has no mutual adhesive force at all
A two-layer adhesive layer is provided between EVOH and EVOH.
One layer is made of polyamide, which has excellent adhesion to EVOH, and the other layer is a modified material containing sulfonate groups, which has excellent adhesion to both PET and polyamide.
By using PAR, it is possible to not only create a multilayer sheet that integrates PET and EVOH, but also to make use of the heat resistance of modified PAR containing sulfon groups to create a multilayer sheet that combines the many advantages of PET with EVOH. In addition to gas barrier properties,
Furthermore, it also imparts heat resistance. Sulfonic group-containing modification necessary to impart such heat resistance
The effect can be sufficiently exhibited if the amount of PAR is 3% or more of the total sheet weight. In addition, each of the constituent components of such a multilayer sheet is selected from materials that are excellent in secondary drawing processability such as deep drawing processing, so it can be formed extremely easily. When considering alternative uses for glass containers, we look to multi-layer structures such as innovative containers that have both heat resistance and gas barrier properties, which PET containers themselves have not been able to achieve until now. (Example) Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Example 1 A melt polycondensation reaction was carried out by a conventional method using 97.5 mol% of terephthalic acid, 2.5 mol% of 5-sodiumsulfoisophthalic acid, and 100 mol% of ethylene glycol in a mixed solvent of equal weight of phenol/tetrachloroethane. A sulfonic group-containing polyester with an ultimate clay of 0.70 measured at 20°C was obtained. On the other hand, it consists of terephthalic acid/isophthalic acid (mixed molar ratio 1) and bisphenol A;
An aromatic polyester having a logarithmic viscosity of 0.60 measured at 25° C. in a 6/4 mixed solvent of tetrachloroethane was prepared. This sulfon group-containing polyester and aromatic polyester are melt-blended in a ratio of 6:4, and the sulfon group-containing modified polyester has a Tg of 99°C.
Got PAR. At this time, the amount of 5-sodyursulfonisophthalic acid based on the total acid components was 1.5 mol%. Contains 15% by weight of nylon 66 component,
A nylon 6/66 copolyamide with a relative viscosity of 4.5 and an intrinsic viscosity of 1.0 measured at 25°C in 96% concentrated sulfuric acid.
EVOH (manufactured by Kuraray Co., Ltd.) with an MI value of 1.40g measured at 190℃ for 10 minutes with PET and a load of 2160g.
Prepare EP-FB), thoroughly dry these materials, and extrude them from a multilayer die using four dedicated extrusion machines to form PET (300μ)/modified PAR containing sulfonate groups (40μ)/copolymerized polyamide. (20μ)/
A sheet having a thickness of 800μ and having a seven-layer structure of EVOH (80μ)/copolymerized polyamide (20μ)/modified PAR containing sulfonate groups (40μ)/PET (300μ) was obtained. The thickness between each layer was uniform with no unevenness, and although there was some cloudiness due to EVOH, it was a transparent sheet, and each layer was firmly adhered to the extent that it could not be separated. This sheet was heated at 140° C. for 5 seconds and then formed into a cup with a diameter of 100 mm and a depth of 40 mm by vacuum forming, resulting in a uniformly stretched transparent product. When this cup was filled with hot water and the degree of deformation was observed, no deformation occurred at all up to 85°C. In addition, the oxygen gas permeability of the film cut out from this container was measured using a measuring device manufactured by Moran Control.
1/2 compared to standalone 1.3cc・mm/24hr・m ²・atm
It was confirmed that the following value was 0.5cc・mm/24hr・m ²・atm. Example 2, Comparative Examples 1 and 2 According to the method of Example 1, only the composition of the adhesive layer was changed to obtain the results shown in Table 1.

[Table] In the table, NaSIPA-PET is PET copolymerized with 2.5 mol% of 5-zodium sulfoisophthalic acid.
Also, PAR indicates aromatic polyester.
Further, the structure of the multilayer sheet is seven layers as in Example 1, and therefore, the thickness of each layer in the table indicates the thickness of the layers on both sides centering on the EVOH layer. The heat-resistant temperature of the container is the temperature at which deformation does not occur when it is filled with hot water. (Effect of the invention) As is clear from Examples 1 and 2, PET/sulfonate group-containing modified PET that satisfies the requirements of the present invention
A coextruded multilayer sheet with a structure consisting of PAR/polyamide/EVOH as basic units has excellent extrusion moldability, uniformity, and interlayer adhesion, and multilayer structures such as containers formed from this sheet are excellent gas barriers. It also has excellent heat resistance that corresponds to the properties and heat resistance of modified PAR containing sulfone groups.

Claims (1)

[Scope of Claims] 1. At least two layers between polyethylene terephthalate or a polyester resin layer mainly composed of polyethylene terephthalate and a partially saponified resin of ethylene/vinyl acetate copolymer or a vinyl resin layer mainly composed of polyethylene terephthalate.
A multilayer sheet having an adhesive layer consisting of layers, in which the polyester resin layer side of the adhesive layer is made of 10 to 90% by weight of sulfonate group-containing polyester,
A coextruded multilayer sheet characterized in that it is a resin composition consisting of 90 to 10% by weight of aromatic polyester, and the vinyl resin layer side is polyamide. 2. The sulfon group-containing polyester used in the resin composition consisting of the sulfon group-containing polyester and the aromatic polyester contains sodium sulfo-isophthalic acid and/or sodium sulfo-terephthalate relative to the total acid components in the resin composition. The coextruded multilayer sheet according to claim 1, which is polyethylene terephthalate copolymerized with an acid content of 0.5 to 10 mol%. 3 Polyamide contains 5-30% by weight of nylon 66 component
The coextruded multilayer sheet according to claim 1, characterized in that it is a copolymerized polyamide containing. 4 Between polyethylene terephthalate or a polyester resin layer mainly composed of polyethylene terephthalate and a partially saponified resin of ethylene vinyl acetate copolymer or a vinyl resin layer mainly composed of polyethylene terephthalate, 10 to 90% by weight of a sulfon group-containing polyester, A multilayer structure formed from a coextruded multilayer sheet provided with an adhesive layer consisting of at least two layers of a resin composition consisting of 90 to 10% by weight of aromatic polyester and polyamide resin.