JPH0528662B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to coextruded sheets and structures with excellent heat resistance and gas barrier properties, and more specifically, they are suitable for forming deep-drawn containers with excellent heat resistance, gas barrier properties, and rigidity. The present invention provides a coextruded multilayer sheet and a multilayer container formed therefrom. (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 consisting of PET and polycarbonate (hereinafter referred to as modified PC), which is a material with higher heat resistance than PET, is co-injected with PET to produce biaxial stretch blow molding. A multi-layer bottle with
Multilayer sheets having such a structure with excellent heat resistance and gas barrier properties and containers formed from the same have not yet been put into practical use. (Problem to be solved by the invention) Although it is highly predicted that the composite of PET/EVOH/modified PC will provide high functionality such as heat resistance and gas barrier, The biggest reason for the delay in practical application is the problem of adhesion between these materials. PET and modified PC
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 of high molecular cohesive energy, which makes direct adhesion to PET and modified PC completely impossible. Therefore, in order to mold a multilayer sheet of PET/EVOH/modified PC, an adhesive layer is indispensable in the middle, but an adhesive suitable for molding such a sheet has not yet been found. Of course just
If the purpose is 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 further transparency, if necessary, are also required. However, it is a general tendency that moldability decreases as the degree of modification progresses through various modification techniques such as copolymerization and polymer alloys to improve adhesion. The difficulty of balancing PET/EVOH/
This can be said to be one of the major reasons for delaying the practical application of highly functional multilayer sheets of modified PC. (Means for Solving the Problems) The present inventors have solved these problems, and have developed a product that has excellent rigidity, heat resistance, and gas barrier properties, can maintain transparency if necessary, and can also be deep-drawn. In order to develop a coextruded multilayer sheet that also has secondary processing properties such as stretching, we have arrived at the present invention 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 the PET side of the adhesive layer is made of 10 to 90% by weight of sulfon group-containing polyester and polycarbonate.
It is a coextruded multilayer sheet characterized in that it is a resin composition (hereinafter referred to as sulfone group-containing modified PC) consisting of 90 to 10% by weight, and the EVOH side is polyamide. Furthermore, the sulfon group-containing polyester used in the sulfon group-containing modified PC contains 0.5 to 10 moles of sodium sulfoisophthalic acid and/or sodium sulfophoterephthalic acid to the total acid component in the sulfone group-containing modified PC. %, and the polyamide is a copolymerized polyamide containing 5 to 30% by weight of a nylon 66 component. Furthermore, it is a structure 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 sebacin is 10 mol% or less of the total acid component. It is possible to use dicarboxylic acids such as acids, polycarboxylic 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, cyclohexanedimethanol, trimethylolpropane, triethylolpropane, penta Polyhydric alcohols such as erythritol can be used as the alcohol component. like this
PET is 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. The sulfone group-containing polyester in the sulfone group-containing modified PC, which is one of the constituent components of the adhesive layer of the present invention, contains sodium sulfoisophthalic acid and sodium sulfo terephthalate as part of the acid components in the polyester. 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 PC, the amount of copolymerization of sodium sulfoisophthalic acid and/or sodium sulfioterephthalic acid is determined as follows: 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 co-containing sulfon as the polyester.
Similarly, the polycarbonate in the sulfon group-containing modified PC is a 4,4-dioxydiallylalkane polycarbonate, such as bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ethane, 2,2bis(4-hydroxyphenyl)ethane, etc. -hydroxyphenyl)propane, bis(4-hydroxy-
3,5-diclophenyl)methane, 2,2bis(4-hydroxy-3,5-dimethylphenyl)
It is a polycarbonate obtained from 4,4-dioxydiphenylalkane such as propane, bis(4-hydroxyphenyl)phenylmethane, and phosgene or diphenyl carbonate. Sulfon group-containing modified PC can be obtained by extruding this sulfon group-containing polyester and polycarbonate using a melt extruder, or by stirring and mixing them while melting them in a reaction can with stirring blades.
A suitable randomization-promoting catalyst may be added to promote randomization due to the transesterification reaction that occurs during melt blending, resulting in a homogeneous polymer alloy. Such sulfonate group-containing modified PC has a glass transition temperature that increases as the amount of polycarbonate increases.
Tg and improves heat resistance. 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. These may be used alone, as a copolymer, or as a mixture; nylon 6 containing 5 to 30% by weight of nylon 66;
66 copolyamide is particularly preferred. The structure of the multilayer sheet according to the present invention is obtained by extruding PET/sulfon group-containing modified PC/polyamide/EVOH as basic units from a multilayer die using four extruders dedicated to each resin.
PET/Sulfion group-containing modified PC/Polyamide/
EVOH/Polyamide/Sulfon group-containing modification
It can have a seven-layer PC/PET structure or, if necessary, a multi-layer structure with more layers. 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 PC and then subjected to vacuum forming or pressure forming. It is possible to make 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 made of modified PC containing sulfonate groups, which has excellent adhesion to both PET and polyamide.
By doing so, it is possible to not only create a multilayer sheet that integrates PET and EVOH, but also to utilize the heat resistance of the sulfon group-containing modified PC to create a multilayer sheet that has many of the advantages of PET.
In addition to the gas barrier properties provided by EVOH, it also provides heat resistance. The amount of sulfon group-containing modified PC necessary for imparting such heat resistance to 3% or more of the total sheet weight can sufficiently exhibit the effect. 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, it can be said with certainty that this is an epoch-making container that combines heat resistance and gas barrier properties that have not been possible with PET containers themselves. (Example) Next, the present invention will be specifically described 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, 3.0 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. This sulfon group-containing polyester and polycarbonate were melt-blended at a ratio of 5:5, and 99
A sulfion group-containing modified PC with a Tg of °C was obtained.
At this time, the amount of 5-sodiumsulfonisophthalic acid based on the total acid components was 1.5 mol%. Separately, nylon 6 contains 15% by weight of nylon 66 component and has a relative viscosity of 4.5 when measured at 25°C in 96% concentrated sulfuric acid.
66 copolyamide, PET with an intrinsic viscosity of 1.0, and EVOH (EVAL EP-F manufactured by Kuraray Co., Ltd.) with an MI (melt index) value of 1.40 g measured at 190°C for 10 minutes at a load of 2160 g were prepared. After thoroughly drying the materials, extrude them through a multilayer die using 4 extruders for each, PET (300μ) / modified PC containing sulfon group (40μ) / copolyamide (20μ) / EVOH (80μ) / Copolymerized polyamide (20μ)/Sulfon group-containing modified PC (40μ)/PET
A sheet with a thickness of 800μ and having a seven-layer structure (300μ) was obtained.
There was no thickness unevenness between the layers, and although there was some cloudiness, the sheet was translucent, and the layers were so firmly adhered that they 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.
Example 2 and Comparative Examples 1 to 3 confirmed that the value was 0.6cc・mm/24hr・m ²・atm, which is less than half of the 1.3cc・mm/24hr・m ²・atm of the single unit. 2 The results in Table 1 were obtained according to the method of Example 1, except that the composition of the adhesive layer was changed.

【table】

[Table] In the table, NaSIPA-PET is PET copolymerized with 3.6 mol% of 5-sodium sulfoisophthalic acid.
Also, PC indicates polycarbonate. 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 was determined to be a temperature at which no deformation occurs when 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
The coextruded multilayer sheet with a structure consisting of PC/polyamide/EVOH as basic units has excellent extrusion moldability, uniformity,
It has excellent interlayer adhesion, and containers formed from this sheet are also provided with excellent gas barrier properties and excellent heat resistance corresponding to the heat resistance of sulfon group-containing modified PC. On the other hand, when the modified PC does not have a sulfonate group as in Comparative Example 1, there is no adhesive force between it and the polyamide, and therefore peeling occurs during sheet extrusion or deep drawing, resulting in a significant decrease in productivity and at the same time, welding. The expected effect on heat resistance cannot be obtained. In addition, as in Comparative Example 2, sulfon group-containing PET
Although workability and productivity are excellent when using only one, heat resistance cannot be imparted. As is clear from the Examples and Comparative Examples described above, the present invention makes it possible to easily obtain coextruded multilayer sheets and containers with excellent heat resistance and gas barrier properties.

Claims (1)

[Claims] 1. Adhesion consisting of 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 this. A multilayer sheet having an adhesive layer, the polyester resin layer side of the adhesive layer being a resin composition consisting of 10 to 90% by weight of sulfonic group-containing polyester and 90 to 10% by weight of polycarbonate,
A coextruded multilayer sheet characterized in that 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 polycarbonate contains sodium sulfoisophthalic acid and/or sodium sulfophoterephthalic acid relative to the total acid components in the resin composition. It is polyethylene terephthalate copolymerized to have a content of 0.5 to 10% by mole, and the polyamide is a copolymerized polyamide containing 5 to 30% by weight of a nylon 66 component. Coextruded multilayer sheet. 3 An adhesive layer consisting of two layers is provided between a 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 this. A multilayer sheet having the above structure, in which the polyester resin layer side of the adhesive layer is a resin composition consisting of 10 to 90% by weight of sulfion group-containing polyester and 90 to 10% by weight of polycarbonate, and the vinyl resin layer side is made of polyamide. A structure molded from a coextruded multilayer sheet.