JPH0339249A - Sheet having multilayer structure - Google Patents

Abstract

PURPOSE:To improve the heat resistance of a multilayer structure sheet by providing a sheath layer composed of polycarbonate having a glass transition point higher than that of thermoplastic polyester having a specific composition to both surfaces of a core layer composed of said polyester. CONSTITUTION:Thermoplastic polyester having 80mol.% or more of an ethylene terephthalate unit becoming a core layer component and polycarbonate having a glass transition point higher than that of the aforementioned thermoplastic polyester becoming a sheath layer component are supplied to a multilayer extrusion molding machine. The aforementioned core component is supplied to one extruder and the sheath component is supplied to other extruder and both components are respectively extruded to mold a multilayer structure sheet wherein both surfaces of the core layer are coated with the sheath layers. The total occupying ratio of polycarbonate used in the heat-resistant reinforcing layers being the sheath layers constituting the obtained multilayer structure sheet is pref. about 3wt.% or more.

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.

(Prior Art) Conventionally, polyvinyl chloride, polymethyl methacrylate, polycarbonate, polyester, polyarylate, etc. are known as transparent sheets.

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,
The heat resistance is low, and migratory titanium, a 61 plastic agent, is considered to be a poor choice. On the other hand, sheets using hard polyvinyl chloride or polymethyl methacrylate have excellent transparency, but
It has low heat resistance, low impact strength, and poor secondary processability.

Furthermore, although sheets using polycarbonate are excellent in heat resistance, transparency, and impact strength, their glass transition temperature is too high, resulting in extremely poor secondary processability and poor gas barrier properties.

Furthermore, although polyester sheets have good transparency, impact strength, secondary processability, chemical resistance, and gas barrier properties, they have a drawback in that 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-priced sheet with excellent heat resistance, transparency, secondary processability, and gas barrier properties. By effectively compounding a resin composition made of polycarbonate into the main component and the t component, we can provide a low-cost sheet with excellent heat resistance, transparency, -addition properties, and gas barrier properties. 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 significantly improved by using polyester, which is inexpensive and has good transparency, secondary processability, and gas barrier properties, in the center of the sheet, and polycarbonate, which has a higher glass transition point, on both sides. However, they discovered that the shape of the container did not change even after being sterilized in water for a long period of time, and arrived at the present invention.

In addition, in the case of food containers containing foods that need to be heated and sterilized in water, polyester has the problem of becoming cloudy during heat sterilization in water, but polyester core layers are replaced with polycarbonate. Since the polyester is not in direct contact with the water guide, the nI
The present invention was achieved by finding that it is not subject to plasticizing action and is less likely to become cloudy.

However, in the present invention, a thermoplastic polyester having 80 mol% or more of ethylene terephthalate units is used in the core layer, and a glass transition point higher than that of the thermoplastic polyester is used in the sheath layers on both sides of the core layer. (This is a multilayer structure sheet characterized by the use of polycarbonate that has a positive polarity.)

In the present invention, the heat i+JQl used as the core layer
A polyester is one obtained by melting and combining a low +lj polymer obtained from terephthalic acid or a lower alkyl ester of terephthalic acid and ethylene glycol by a conventional ester reaction or an ester exchange reaction, or solid phase +li
This is a combined process. And Jukujiff, which contains 80 mol% or more of ethylene terephthalate units,! P
L polyester includes, in addition to the Q'+iJ qj polynisnal described in L, a copolymer consisting of 80 mol% or more of ethylene terephthalate units and other repeating units, that is, other copolymer components. As other copolymerization components in E, various acid components and polyhydric alcohol components can be used.

For example, flI ingredients include phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, hexahydroterephthalic acid, 2,6-naphthalene dicarboxylic acid, 2,5-dibromoterephthalic acid, diphenyl Dicarboxylic acid, trimesic acid, trimesic acid, pyromellitic acid, etc. can be mentioned, and polyhydric alcohol components include propylene glycol, diethylene glycol, tetramethylene glycol, polyethylene glycol, polytetramethylene glycol, 1.6 -Hexanediol, trimethylene glycol, neopentyl glycol, ρ-xylylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, glycerin, pentaerythritol, trimethanolpropane, trimethanolbenzene, trimethanolbenzene, etc. can.

The molecular species of hot mouth I plastic polyester in L is about 10°0
A range of 00 to 100,000 is suitable for obtaining high transparency, especially at high temperatures, which is desirable from the physical properties L and extrusion properties, since the copolymerized polyester is difficult to crystallize.

Moreover, the polycarbonate used in the present invention is a homopolycarbonate, a copolycarbonate, or a mixture thereof. Polycarbonates are generally prepared by condensation of 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, bis( Included are hydroxyphenyl)-sulfoxides, biα,α-(hydroxyphenyl)-diisopropylene sulfoxides, and nuclear-alkylated compounds thereof. Examples of these suitable suphenols include 2,2-bis-(4-hydroxyphenyl)
Propane (bisphenol A), 2,4-bis-(4-
hydroxyphenyl) methylbutane, 1,1-bis-(
4-hydroxyphenyl)-cyclohexane, α, α-
Bis(4-hydroxyphenyl)-ρ-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.
2r bis-(3,5-dimethyl-4-hydroxyphenyl)furopane, 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-
Examples include 4-hydroxyphenyl)-p-diisopropylbenzene and 414-sulfonyldiphenyl.

The polycarbonates of the present invention have fIi derived from one or more suitable bisphenols in their structural units.
can contain positions.

In the present invention, the polycarbonate used as the P8-resistant reinforcing waste in the multilayer structure sheet is desirably 391% or more of the total amount of polycarbonate, and the heat-resistant reinforcing effect is significantly reduced at 3% of the total amount of polycarbonate.

The total thickness of the heat-resistant reinforcing layer is preferably 3% by weight to 60% by weight.

As the core layer, it is also possible to use recovered materials generated during secondary processing of the multilayer structure sheet. In addition, in the center of the core layer, there is an additional layer of ethylene/
By providing a gas barrier material layer such as vinyl alcohol copolymer (14VOH), polymethaxylylenediamine adipamide (MXD-6), and non-grade Boria Sl-'' resin, it has heat resistance and gas barrier properties. It is also possible to manufacture excellent containers.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 It is preferable to use low-density polyethylene and polypropylene, or compositions based thereon.

In addition, the heat-resistant reinforcing layer also plays the role of improving water resistance, that is, the polycarbonate prevents water from entering the core layer, so the multilayer sheet of the present invention can be used even after sterilization treatment in spring water. A transparent food container was obtained without becoming cloudy.

Furthermore, since the food container is mainly made of polyester, it is extremely advantageous in terms of cost.

Further, by inserting polyarylate citrus between the polyester layer and the polycarbonate layer, ultraviolet ray resistance can be brought about.

(Example] Next, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 4 Polyethylene terephthalate alone with an intrinsic viscosity of 1.0 was used as the core layer, and Kneepilon E2000 (
Example 1. Polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used at various thickness ratios (expressed in weight %) shown in Table 1.
2.3 multilayer sheets were molded.

As for the sheet forming method, a multilayer extrusion molding machine was used, and polyethylene terephthalate (extrusion temperature 2
75° C.) and polycarbonate (extrusion temperature 295° C.) using the other extruder to create a multilayer sheet with a thickness of 1.0 mm.

In addition, as Example 4, polyethylene terephthalate (intrinsic viscosity 1.0
) under the same conditions as Example 2.

Table 1 shows the results of measuring the physical properties of these sheets according to JIS K-7126.

As an evaluation of heat resistance, each piece was placed in hot water at 100°C for 30 minutes. 0 indicates optical physical properties (haze) 3, G engineering Ishin L6 wood StQ physical properties (haze) 3-6, × indicates optical physical properties (haze) 6 or more.

In addition, for secondary processability, a molded product was created using a thermoforming machine and a molding company was checked. O is good, Δ is slightly poor, ×
indicates good quality.

In addition, 02 gas barrier property is 20°C1Ii' l-1
Measured at 0%. O is 2cc・■/d・day Eastman,
× indicates 2 (-c・■/po・day−hi).

As is clear from Table 1, the examples according to the present invention have heat resistance of -E of 95°C or higher, and also have good secondary f properties.

Comparative Examples 1 to 3 Table 1 shows the results of molding multilayer sheets in the same manner as in the example except for using various softening thickness ratios (expressed in % of car weight) and measuring their physical properties. , Comparative Examples 1 to 3 all have at least one of heat resistance, secondary processability, and gas barrier properties.
One was defective.

〔Effect of the invention〕

As is clear from the following description, the multilayer structure sheet according to the present invention uses polycarbonate in addition to thermoplastic polyester to compensate for the drawbacks of polyester having a thermal lJ of 41.1. q
While effectively utilizing the advantages of polyester,
By effectively using polycarbonate,
It has excellent heat resistance, secondary processability, and gas barrier properties, and has excellent practical effects such as being widely usable as industrial and industrial sheets. be.

Claims (1)

[Claims] A multilayer structure sheet characterized in that a thermoplastic polyester having 80 mol% or more of ethylene terephthalate units is used in the core layer, and a polycarbonate having a glass transition point higher than that of the thermoplastic polyester is used in the sheath layers on both sides.