JPH01200959A - Multilayer structural sheet - Google Patents

Abstract

PURPOSE:To enhance secondary processability, by providing a heat resistant reinforcing layer consisting of polyester and polyallylate and a chemical resistant reinforcing layer composed of polyester to both surfaces of a core layer composed of polyethylene terephthalate. CONSTITUTION:A heat resistant reinforcing layer composed of a resin composition wherein the wt. ratio of thermoplastic polyester and polyallylate is 60:40-0:100 is arranged to both surfaces of the core layer composed of thermoplastic polyester having at least 80mol% of an ethylene terephtalate unit provided at the center of a sheet cross-section and, further a chemical resistant reinforcing layer composed of thermoplastic polyester is further arranged to both surfaces of the heat resistant reinforcing layer to form a multilayer structural sheet. In this case, the wt. ratio of the core layer, the heat resistant layer and the chemical resistant layer as A, B, Cwt.% is set to 40<=A<=94 and 3<=(B and C)<=30.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a transparent multilayer structure sheet having excellent heat resistance, chemical resistance and secondary processability.

(Conventional technology) Conventional transparent sheets are made of polyvinyl chloride.

Polymethyl methacrylate polycarbonate polyester, polyarylate, etc. are known.

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

In other words, soft vinyl chloride sheets have excellent transparency, impact strength,
Although the results are mostly satisfactory in terms of secondary processability, migration of the plasticizer is seen as a problem.

On the other hand, sheets using hard vinyl 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. 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. However, resin compositions obtained from polyester and polyarylate are widely used because their heat resistance is improved by adding polyarylate, as already known in JP-A-49-61247 and JP-A-50-96652. Although it has become possible to expand its uses, on the other hand, there are problems such as a decrease in chemical resistance9 and an increase in price as the blending ratio of polyarylate increases.

(Problem to be solved by the invention) As mentioned above, it has been difficult to obtain a low-cost sheet that has excellent heat resistance, chemical resistance, and secondary processability, but among these properties, only heat resistance It is transparent and heat resistant by effectively compounding a resin composition consisting of polyarylate and polyester into the main component using inferior and low-priced polyester.

The purpose is to provide a low-cost sheet with excellent chemical resistance and secondary processability.

(Means for Solving the Problems) As a result of intensive research for this purpose, the inventors of the present invention found that by using an inexpensive polyester in the center of the sheet cross section, and using polyester and polyester having a higher glass transition point on both sides. By using a resin composition consisting of arylate,
The present invention was achieved by discovering that heat resistance is significantly improved, and by placing polyester layers on both sides, a transparent multilayer structure sheet with chemical resistance and good secondary processability can be obtained.

That is, in the present invention, a core layer made of a thermoplastic polyester having at least 80 mol% or more of ethylene terephthalate units is located at the center of the sheet cross section, and on both sides thereof, the weight ratio of the thermoplastic polyester and polyarylate is 60:40. A heat-resistant reinforcing layer made of a resin composition in the range of ~O:100 is located, and chemical-resistant reinforcing layers made of the thermoplastic polyester are located on both sides of the heat-resistant reinforcing layer, and the core layer, the heat-resistant reinforcing layer, and the chemical-resistant reinforcing layer are The weight ratio is A and B, respectively.
, when expressed as C weight %.

It relates to a multilayer structure characterized by the relationship of 40≦A≦94 and 3≦(B and C)≦30, and the core layer is a material recovered during secondary processing of the multilayer structure sheet. Can be done.

(effect) What is the thermoplastic polyester used in the present invention?

A product obtained by melt polymerizing a low polymer obtained from terephthalic acid or a lower alkyl ester of terephthalic acid and ethylene glycol by a normal esterification reaction or transesterification reaction, or by subjecting it to solid phase polymerization treatment. This is what I did. The thermoplastic polyester having at least 80 mol% or more of ethylene terephthalate units means 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, two types of acid components and glycol 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. , trimellitic acid, trimesic acid, pyromellitic acid, etc., and glycol components include propylene glycol, diethylene glycol, tetramethylene glycol, and polyethylene glycol.

Polytetramethylene glycol, 1,6-hexanediol, trimethylene glycol, neopentyl glycol, P-xylylene glycol, 1,4-cyclohexane dimetatool, bisphenol A, glycerin, pentaerythritol, trimethanolpropane, trimethanolbenzene , triethanolbenzene and the like.

The molecular weight of thermoplastic polyester is approximately 10,000 to 10
A range of 0.000 is preferable from the viewpoint of physical properties and extrusion processability.

The polyarylate used in the present invention is obtained from an aromatic dicarboxylic acid or a functional derivative thereof and a dihydric phenol or a functional derivative thereof. As the aromatic dicarboxylic acid used for preparing the polyarylate, any aromatic dicarboxylic acid may be used as long as it reacts with dihydric phenol to give a satisfactory polymer, and one type or a mixture of two or more types may be used. Preferred aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and mixtures thereof are particularly preferred in terms of melt processability and overall performance.

In the case of such a mixture, the mixing ratio is not limited, but terephthalic acid/isophthalic acid = 971 to 1/9.
(molar ratio) is preferable, and in particular, 773 to 3/7 (molar ratio) and more preferably 1/1 (molar ratio) from the viewpoint of melt processability and balance of performance. Specific examples of preferred dihydric phenols include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, and 2,2-bis(4-hydroxyphenyl)propane. −
3,5-dichlorophenyl)propane, 4.4'-dihydroxydiphenyl sulfone, 4.4'-dihydroxydiphenyl ether, /! , 4'-dihydroxydiphenyl sulfide, 4.4"-dihydroxydiphenylketone, 4,4°-dihydroxydiphenylmethane, 2.2'-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1.1-bis (4-hydroxyphenyl)ethane, 1.1-bis(4-hydroxyphenyl)cyclohexane, 4.4'-dihydroxydiphenyl, benzoquinone, etc. These may be used alone or in combination of two or more. They may be used in combination.Although these dihydric phenols are para-substituted, other isomers may also be used.

Furthermore, ethylene glycol, propylene glycol, etc. may be used in combination with these dihydric phenols.

The most typical dihydric phenol is 2°2-bis(4-hydroxyphenyl)propane.

It is commonly called bisphenol A.

Most preferred from the viewpoint of comprehensive physical properties.

Therefore, the most preferred polyarylate in the present invention is a mixture of terephthalic acid and isophthalic acid or their functional derivatives (however, the molar ratio of terephthalic acid groups to isophthalic acid groups is 9:1 to 1:9, especially 7:3 to 3). dihydric phenol, especially bisphenol A or its functional derivative. The molecular weight of the polyarylate is preferably in the range of about 7,000 to 100,000 from the viewpoint of physical properties and extrusion processability.

In the present invention, the resin composition composed of thermoplastic polyester and polyarylate used as the heat-resistant reinforcing layer in the multilayer structure sheet preferably has a glass transition temperature of 100'C or higher. The blending ratio of 40% by weight or more is required. The reason why it is desirable for the glass transition temperature to be 100°C or higher is because it enables hot filling when used in food containers, etc., and the elastic modulus of the resin composition hardly decreases up to around 100°C. . The core layer sandwiched between the heat-resistant reinforcing layers and the chemical-resistant reinforcing layers located on both sides are made of thermoplastic polyester, so the glass transition temperature is approximately 73°C.
It is. Therefore, when used at temperatures exceeding 73°C, its elastic modulus decreases by about 3 orders of magnitude, that is, 10h to 10'dyne.
/cnl, but since the elastic modulus of the heat-resistant reinforcing layer controls the overall elastic modulus, 1For example, if the heat-resistant reinforcing layer makes up 10% by weight of the whole, the elasticity decreases by about one digit even at temperatures exceeding 73°C. That is, the value of 10' dyne/c4 is maintained.

Furthermore, by positioning the heat-resistant reinforcing layer to sandwich the core layer at the center of the sheet cross section, the bending rigidity of the sheet becomes higher than when the heat-resistant reinforcing layer is used in place of the core layer. Since bending rigidity can be expressed as the product of elastic modulus and moment of inertia of area, the reason for this can be proven from material mechanics as follows. A core layer with a thickness of a and a low elastic modulus is located at the center of the sheet cross section.

The moment of inertia of the cross section when a heat-resistant reinforcing layer with a high elastic modulus of thickness b/2 is located on both sides of the sheet) I,, A heat-resistant reinforcing layer with a high elastic modulus of a thickness b is located at the center of the sheet cross section, and on both sides Let lt be the moment of inertia of area when a layer with a low elastic modulus is located with a thickness of a/2.

Considering that low elastic modulus/high elastic modulus = 1/103, it is only necessary to compare the heat-resistant reinforcing layer with high elastic modulus as a layer that affects bending rigidity. 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 core layer made of thermoplastic polyester in the whole is preferably 40% by weight or more and 94% by weight or less from the viewpoint of cost. The reason why 94% by weight or less is desirable is that the proportion of the other constituent layers in the whole needs to be at least 6% by weight. The proportion of the heat-resistant reinforcing layer in the entire heat-resistant reinforcing layer is desirably 3% by weight or more, and if it is less than 3% by weight, the heat-resistant reinforcing effect is not significant. Furthermore, if the thickness of the heat-resistant reinforcing layer exceeds 30% by weight, the heat-resistant reinforcing effect will be reduced compared to an increase in the thickness. Therefore, the total thickness of the heat-resistant reinforcing layer is preferably 3% by weight or more and 30,000% by weight or less.

Polyarylate can be used in cooking oil, machine oil or acetone,
If it comes into contact with a solvent such as toluene, cloudy deterioration or crank formation is observed, so it is preferable not to use it on the sheet surface. On the other hand, since the resistance of thermoplastic polyester to the above-mentioned oils and solvents decreases due to crystallization due to orientation during secondary processing of the sheet, it is desirable to place it on the surface of the sheet as a second chemical-resistant reinforcing layer. The proportion of this chemical-resistant reinforcing layer in the entirety is preferably 3% by weight or more.

If it is less than 3% by weight, the chemical resistance reinforcing effect will not be exhibited.

Further, if the thickness of the chemical-resistant reinforcing layer exceeds 30% by weight, the chemical-resistant reinforcing effect will be reduced compared to the increase in thickness, so the thickness of the chemical-resistant reinforcing layer is preferably 3% by weight or more and 30% by weight or less.

Further, as the core layer of the multilayer structure sheet of the present invention, recovered materials such as trimming waste generated during secondary processing of the multilayer structure sheet may be used. Since the composition of the recovered material is thermoplastic polyester and polyarylate, this recovered material itself is a composition having a higher glass transition temperature than the thermoplastic polyester.

Therefore, the core layer itself has heat resistance, so 1
Even if the blending ratio of polyarylate in the resin composition consisting of thermoplastic polyester and polyarylate used as the original heat-resistant reinforcing layer is lowered, the multilayer has the same heat resistance as the multilayer structure sheet when recycled material is not used. A structural sheet can be obtained, which is an effective means for cost reduction.

(Example) Examples 1 to 4. Comparative Examples 1 to 4 Next, the present invention will be explained in more detail with reference to Comparative Examples and Examples. Using polyethylene terephthalate alone as the core layer and chemical-resistant reinforcing layer, and using polyethylene terephthalate alone or a composition consisting of polyethylene terephthalate and polyarylate (Polyarylate resin U polymer manufactured by Unitika) as the heat-resistant reinforcing layer, Comparative Examples 1 to 4 (indicated by weight %) Example 1~
A sheet with a thickness of 1 mm was prepared using Step 4. Among the physical property evaluations of these sheets, in terms of heat resistance, the bending elastic modulus was 5
The temperature at which O'dyne/c+a was measured. As for chemical resistance, clouding of the sheet surface due to acetone application was checked. The results are shown in Table 1.

As can be seen from the results in Table 1, the examples according to the present invention had 9
It has heat resistance of 5°C or higher and good chemical resistance.

(Effects of the Invention) The multilayer structure sheet according to the present invention can greatly reduce the amount of expensive polyarylate, and has excellent heat resistance, chemical resistance, and secondary processability, and can be used for food containers, medicine containers, etc. It can be widely used.

Patent applicant: Unitika Co., Ltd.

Claims (2)

[Claims] (1) A core layer made of thermoplastic polyester having at least 80 mol% or more of ethylene terephthalate units is located at the center of the sheet cross section, and on both sides the weight ratio of the thermoplastic polyester and polyarylate is 60:40.
A heat-resistant reinforcing layer made of a resin composition with a ratio of 0:100 to 0:100 is disposed, and a chemical-resistant reinforcing layer made of the thermoplastic polyester is disposed on both sides of the heat-resistant reinforcing layer. When the weight ratios are respectively A, B, and C weight%, 40≦A≦94 and 3≦(B and C)≦30
A multilayer structure sheet characterized by the following relationship. (2) The multilayer structure sheet according to claim 1, wherein a material recovered during secondary processing of the multilayer structure sheet is used as the core layer.