JPH0382530A - Heat-resistant, transparent and multilayer plastic sheet - Google Patents

Abstract

PURPOSE:To obtain a transparent and multilayer structural sheet which is superior in heat resistance, gas barrier properties and secondary processability, by a method wherein the central layer, heat-resistant and transparent layers on both sides of the central layer and outer layers on both side of the central layer and outer layers on both sides of the heat-resistant and transparent layers further which are comprised respectively of polyester where mol% of an ethylene terephthalate unit is specified, polycarbonate resin and thermoplastic polyester are provided. CONSTITUTION:Thermoplastic polyester which is inexpensive and possesses favorable secondary processability and gas barrier properties is used for the center of a section of a sheet. A resin componsition comprised of polycarbonate resin having the higher glass transition point than that of the thermoplastic polyester is used on both sides of the same. With this construction, heat resistance is improved drastically and a multi-layer structural sheet which is transparent and has favorable secondary processability is obtained by making use of thermoplastic polyester layer on both sides of the resin compositions. The thermoplastic polyester to be used possesses an ethylane terephthalate unit of at least 80 mol %.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transparent multilayer structure sheet with excellent heat resistance, gas barrier properties, and secondary processability.

[Conventional technology]

Conventionally, known transparent sheets include polyvinyl chloride, polymethyl methacrylate, polycarbonate, polyester, and polyarylate.

However, these sheets have advantages and disadvantages in their properties, and their fields of application are also limited.

In other words, although the soft polyvinyl chloride sheet is almost satisfactory in terms of transparency, impact strength, and secondary processability,
Migration of plasticizer is considered to be a problem.

On the other hand, sheets using hard polyvinyl chloride or polymethyl methacrylate have excellent transparency, but have low impact strength and poor secondary processability.

Further, although sheets using polycarbonate have excellent heat resistance, transparency, and impact strength, their glass transition temperature is too high and their secondary processability is extremely poor.

Furthermore, although polyester sheets have good transparency, impact strength, secondary processability, and chemical resistance, their heat resistance is limited and their fields of use are limited.

[Problem to be solved by the invention]

As mentioned above, it has been difficult to obtain a low-cost sheet with excellent heat resistance, transparency, gas barrier properties, and secondary processability. To provide a low-cost sheet with excellent heat resistance, transparency, secondary processability, and gas barrier properties by effectively combining a resin composition made of polycarbonate into the main component. The purpose is to

[Means to solve the problem]

As a result of intensive research for this purpose, the present inventors found that
Heat resistance is achieved by using an inexpensive thermoplastic polyester with good secondary processability and gas barrier properties in the center of the sheet cross section, and a resin composition made of polycarbonate resin with a higher glass transition point on both sides. The inventors have discovered that by using thermoplastic polyester layers on both sides, a transparent multilayer structure sheet with good secondary processability can be obtained, and the present invention has been achieved based on this finding. In addition, there is a gas barrier in the center of the center layer.
It is also possible to provide a layer of barrier material such as a highly resistant ethylene/vinyl alcohol copolymer. In this case, it is preferable to provide an adhesive layer outside the gas barrier material layer.

[Effect]

The thermoplastic polyester used in the present invention is obtained by melt polymerizing a low polymer obtained by a conventional esterification reaction or transesterification reaction from terephthalic acid or a lower alkyl ester of terephthalic acid and ethylene glycol. or solid-phase polymerized products thereof. A thermoplastic polyester having 80 mol% or more of ethylene terephthalate units means, in addition to the above-mentioned thermoplastic polyester, 80 mol% or more of ethylene terephthalate units and other repeating units, that is, other copolymer components. As the above-mentioned other copolymer components, various acid components and polyhydric alcohol components can be used.

For example, acid components include phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, hexahydroterephthalic acid, 2,6-naphthalenedicarboxylic acid, 2,5-dibromoterephthalic acid, diphenyldicarboxylic acid, Examples of polyhydric alcohol components include propylene glycol, diethylene glycol, tetramethylene glycol, polyethylene glycol, polytetramethylene glycol, l,6-hexanediol, trimethylene glycol, neopentyl glycol, p-xylylene glycol, 1,4-cyclohexane dimetatool, bisphenol A, glycerin,
Examples include pentaerythritol, trimethanolpropane, trimethanolbenzene, and triethanolbenzene.

The molecular weight of thermoplastic polyester is approximately 10,000 to 1
A range of 00.000 is preferable from the viewpoint of physical properties and extrusion processability.

Moreover, the polycarbonate resins used in the present invention are homocarbonates, copolycarbonates, or mixtures thereof. Polycarbonate m is generally produced by polycondensation from phosgene and bisphenols.

Among the bisphenols useful in the practice of this invention are hydroquinone, resorcinol, bis-(hydroxyphenyl)-cycloalkanes, bis-(hydroxyphenyl)-cycloethers, bis-(hydroxyphenyl)-ketones, Included are (hydroxyphenyl)-sulfoxides, bis-(hydroxyphenyl)-sulfones and α,α-(hydroxyphenyl)-diisopropylbenzenes, as well as their nucleus-alkylated compounds. Other examples of these suitable bisphenols include 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A), 2,4-
bis-(4-hydroxyphenyl)-methyl-butane,
1.1-bis-(4-hydroxyphenyl)-cyclohexane, α,α-bis-(4-hydroxyphenyl)-
p-diisopropylbenzene, 2.2-bis-(3-methyl-4-hydroxyphenyl)propane, 2.2-bis-(3-chloro-4-hydroxyphenyl)propane, bis-(3,5-dimethyl- 4-hydroxyphenyl)-methane, 2,2-bis-(3,5-dimethyl-4-
hydroxyphenyl)propane, bis-(3゜5-dimethyl-4-hydroxyphenyl)sulfoxide, bis(
3,5-dimethyl-4-hydroxyphenyl)sulfone, hydroxybenzophenone, 2,4-bis-(3,5
-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,1-bis-(3゜5-dimethyl-4-hydroxyphenyl)-cyclohexane, α,α-bis-(3
, 5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene, and 4,4-sulfonyldiphenyl.

The polycarbonates of the present invention can contain units derived from one or more suitable bisphenols among their structural units.

In the present invention, the resin composition made of polycarbonate resin used as the heat-resistant reinforcing layer in the multilayer structure sheet is as follows:
It is desirable that the glass transition temperature is 100°C or higher,
Polycarbonate resins used for this purpose are effective.

The reason why it is desirable for the glass transition temperature to be 100°C or higher is to enable hot filling when used in food containers, etc., and the elastic modulus of the resin composition hardly decreases up to around 100°C. . The center layer sandwiched between the heat-resistant reinforcing layers and the outer layers on both sides (chemical-resistant reinforcing layers)
Since it is a thermoplastic polyester, its glass transition temperature is about 73°C.

Therefore, when used at temperatures exceeding 73°C, its elastic modulus decreases by about three orders of magnitude, i.e., 10' to 10'dyne/ai.
However, since the elastic modulus of the heat-resistant reinforcing layer controls the overall elastic modulus, for example, if 10% by weight of the whole is made up of the heat-resistant reinforcing layer, the elastic modulus decreases by about an order of magnitude even at temperatures exceeding 73°C, that is, 10 ' Maintain the value of dyne/cj.

Furthermore, by positioning the heat-resistant reinforcing layer sandwiching the center layer at the center of the sheet cross section, the bending stiffness of the sheet is higher than when the heat-resistant reinforcing layer is used in place of the center layer. Since it can be expressed as the product of the coefficient and the moment of inertia of area, the reason for this can be proven by material mechanics as follows. Moment of inertia II when a low elastic modulus central layer with thickness a is located at the center of the sheet cross section, and heat resistant reinforcing layers with high elastic modulus of thickness b/2 are located on both sides of the central layer, and the thickness at the center of the sheet cross section The moment of inertia of area when a heat-resistant reinforcing layer with a high elastic modulus b is located and layers with a low elastic modulus of thickness a / 2 are located on both sides of it is I2, and low elastic modulus / high elastic modulus =
Considering 1/103, only the heat-resistant reinforcing layer with a high elastic modulus needs to be compared as a layer that contributes to bending rigidity, so the following equation is obtained. This indicates that the closer the heat-resistant reinforcing layer is to the sheet surface, the higher the overall bending rigidity will be. However, it is desirable that the sheet surface be made of thermoplastic polyester, which has excellent chemical resistance.

The proportion of the center layer made of thermoplastic polyester in the whole is preferably 40% by weight or more and 94% by weight or less from a cost perspective. This is because at least 6% by weight is required. The proportion of the heat-resistant reinforcing layer in the whole is preferably 3% by weight or more; if it is less than 3% by weight, the heat-resistant reinforcing effect is not significant, and if the thickness of the heat-resistant reinforcing layer exceeds 30% by weight, the thickness The heat resistance reinforcing effect will be less than the increase. Therefore, the total thickness of the heat-resistant reinforcing layer is preferably 3% by weight or more and 30% by weight or less.

In addition, another layer in the center of the center layer is made of ethylene/vinyl alcohol copolymer (EV) with high gas barrier properties.
OH), polymethaxylylenediamine adipamide (M
XD-6) By providing a layer of gas barrier material such as non-grade polyamide resin, it is also possible to manufacture a container having heat resistance and gas barrier properties.

In this case, an adhesive layer on the outside of the gas barrier material layer is made of maleic anhydride graft-modified ethylene-vinyl acetate copolymer, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, or the like. It is preferable to use a composition having the following composition. Further, by inserting a polyarylate resin between the polyester layer and the polycarbonate resin layer, an ultraviolet ray blocking effect can be provided.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Polyethylene terephthalate resin (hereinafter referred to as PET) manufactured by Unitika Corporation with an intrinsic viscosity of 1.0 was used as the center layer and outer layer, and polycarbonate resin (Kneepilon E-2000 manufactured by Mitsubishi Gas Chemical Corporation) was used as the heat-resistant reinforcing layer. A sheet with a thickness of 1 mm was prepared using each of the mixing ratios shown in 1.

Table 1 shows the results of measuring the physical properties of these sheets.

As an evaluation of heat resistance, the molded product was treated in hot water at 100° C. for 30 minutes and then checked for thermal deformation. ○
indicates that there is no deformation of the molded product, and × indicates that there is deformation of the molded product.

In addition, for secondary processability, a molded product was created using a thermoforming machine and the moldability was checked. ○ is good, Δ is slightly poor, ×
indicates defective.

As is clear from Table 1, the examples according to the present invention have heat resistance, good secondary processability, and are economical.

Comparative Example 1.2 Multilayer sheets were molded in the same manner as in the example except that the various thickness ratios (indicated by weight %) shown in Table 1 were used, and the physical properties of the sheets were measured. Table 1 shows the results of Comparative Example 1. .2 was poor in at least one of heat resistance, secondary workability, and economical efficiency.

Table 1 [Effects of the Invention] As is clear from the above description, the multilayer structure sheet according to the present invention uses thermoplastic polyester, which is inexpensive and has good secondary processability and gas barrier properties, in the center layer, and By using polycarbonate that has a higher glass transition point than that, and using thermoplastic polyester layers that are transparent and have good secondary processability on both sides, the disadvantages of thermoplastic polyester can be compensated for, and the advantages of thermoplastic polyester can be compensated for. By effectively using small amounts of expensive polycarbonate while effectively utilizing polycarbonate, it has excellent heat resistance, transparency, secondary processability, and gas barrier properties, and is widely used as industrial and industrial sheets. It has excellent practical effects, such as the ability to

Claims (1)

[Claims] Consisting of a center layer made of thermoplastic polyester having 80 mol% or more of ethylene terephthalate units, heat-resistant transparent layers made of polycarbonate resin placed on both sides of the center layer, and outer layers made of thermoplastic polyester placed on both sides of the center layer. A multilayer structure sheet characterized by: