JPH02300235A - Polyester film or fiber - Google Patents

Abstract

PURPOSE:To obtain a polyester film or fiber of excellent productivity and dimensional stability by orienting a compatible mixture of a crystalline thermoplastic polyester with a specified amorphous thermoplastic polyester. CONSTITUTION:An at least uniaxially oriented film or fiber comprising a compatible mixture of a crystalline thermoplastic polyester (A) with an amorphous thermoplastic polyester (B) having a glass transition temperature higher than the polyester (A). The requirements for the above glass transition temperature (Tg) are necessary because an improvement in the dimensional stability of the polyester (A) can be accomplished by the introduction of the polyester (B) of a higher Tg. The requirements for being amorphous are necessary because if the polyester (B) is crystalline, it inevitably has too high a melting point to be subjected to film formation, melt spinning, orienting, etc.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a polyester film that has excellent productivity, dimensional stability, etc. and is useful as a packaging film, a film for electrical and electronic fields, or a polyester film for clothing and industrial applications. It relates to polyester fibers that can be used as materials.

[Conventional technology]

Polyethylene terephthalate (PET), polybutylene terephthalate (PB'r), polyethylene-2,6-
Films or fibers made of crystalline thermoplastic polyesters such as naphthalate (PEN) have mechanical properties such as strength, elongation, and Young's modulus, as well as moisture and water absorption properties.
It is a material with excellent balance of chemical properties such as chemical resistance.

[Problem to be solved by the invention]

However, there are severe demands for improving the performance of these polyester films or fibers, and in particular, it is desired to further improve their dimensional stability against heat. To improve this dimensional stability, two main methods are used: the use of polyester with a high melting point and high glass transition temperature, and heat treatment to increase oriented crystallization. It is difficult to obtain a polyester that satisfies both a melting point and a high glass transition temperature, and the latter method has its own limitations because the heat treatment temperature is determined by the polyester's melting point, degree of crystallinity, and crystallization speed.

The present invention seeks to address the above-mentioned problems in polyester films or fibers.

[Means to solve the problem]

As a result of intensive studies on this problem, the inventors of the present invention found that the use of amorphous polyester having a high glass transition temperature is suitable for the purpose, and arrived at the present invention.

That is, the present invention provides crystalline thermoplastic polyester (/
l) and an amorphous thermoplastic polyester (B) having a glass transition temperature 11 higher than that of the crystalline thermoplastic polyester (B).
The gist is a film or fiber made of a compatible mixture with B) and characterized in that it is oriented in at least one axis.

Crystalline thermoplastic polyester used in the present invention (
A) is a crystalline, melt-processable polyester with good film or fiber forming properties, and specifically includes PET, PBT, PEN, polycyclohexylene dimenalene terephthalate (PCT), and polyester. Typical examples include p-ethyleneoxybenzoate (PEOB) and polyesters containing these as main components. Here, the glass transition temperature (hereinafter referred to as T g) of the crystalline thermoplastic polyester (B) is the same as that of the amorphous thermoplastic polyester (B).
]゛g, but Tg plays an important role in the relationship with DS
It can be measured by C, etc., and in PET it is 70
°C, 50°C for PBT, 120°C for PEN, P
The optimum value is 95°C for CI'' and 60°C for PE0B.Additionally, a small amount of other components (preferably 15% It goes without saying that the crystalline thermoplastic polyester (If) may be formed from a mixed polyester of PET and P B i', for example.

Next, the amorphous thermoplastic polyester (2) used in the present invention is an amorphous thermoplastic polyester having a higher 'rg than the crystalline thermoplastic polyester (II), but the requirements for the Tg value are not met. Due to the following reasons. In other words, the dimensional stability of the crystalline thermoplastic polyester (B) is improved by the amorphous thermoplastic polyester with a higher Tg.
This is because it can be achieved by introducing . In addition, the requirement of being amorphous is the amorphous thermoplastic polyester (13)
This is because if it is crystalline, it inevitably has an excessively high melting point, which often makes melt film formation, melt spinning, stretching, etc. difficult. Therefore, polyesters that are amorphous but have a low Tg, or polyesters that are crystalline even though they have a high Tg, have problems in their effectiveness. And, crystalline thermoplastic polyester (A) and amorphous thermoplastic polyester (B)
The difference in Tg is preferably 20°C or more, more preferably 30°C or more. Examples of such high g and amorphous polyesters include diphenylsulfone-4,4'-dicarboxylic acid, diphenyl-4,4'-
dicarboxylic acid, diphenyl-2,2'-dicarboxylic acid,
! , 1.3-trimethyl-3-phenylindan-4
', 5-dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, N-(2-hydroxyethyl) trimellitimide, N, N'-ethylene bis trimellitimide, bis(4-hydroxyethylphenyl) sulfone, 2. 2
-bis(4-hydroxyethylphenyl)propane, 3
．． 9-bis(l,1-dimethyl-2-hydroxyethyl)-2,4゜8.10-tetrakisspiro(5,5]undecane, bis(4-hydroxyethyl-3,5-dimethylphenyl)sulfone, 2 .2-bis(4-hydroxyethyl-3,5-dimethylphenyl)propane, bis(4-hydroxyethyl-3,5-dimethylphenyl)
Polyesters containing components such as ethylene glycol, trimethylene glycol, 1,4-butanediol, adipic acid, sebacic acid, terephthalic acid, cyclohexanedicarboxylic acid, hydroxyethylbenzoic acid, etc. are suitable. It is obtained by polycondensation by a commonly known method in combination with a suitable component.

It should be noted that it goes without saying that the higher the '1゛g of the amorphous thermoplastic polyester (■), the better the dimensional stability of the final film or fiber will be. 200° considering workability such as stretching
It is preferably L7 or lower.

The film or fiber of the present invention is composed of a compatible mixture of a crystalline thermoplastic polyester (A) and an amorphous thermoplastic polyester (B). The combination is selected taking into account its compatibility with the polyester (B), but this mixture simply means that it is a simple blend of the crystalline thermoplastic polyester (If) and the amorphous thermoplastic polyester (B). The state of a medium line blend or the state of a block copolyester, including the case where the crystalline thermoplastic polyester (A) and the amorphous thermoplastic polyester form a so-called block copolyester, are crystalline thermoplastic. It is produced by appropriately adjusting the temperature, time, etc. when mixing the plastic polyester (B) and the amorphous thermoplastic polyester (2). The amount of the amorphous thermoplastic polyester in the mixture is preferably 10 to 50% by weight, more preferably 15 to 40% by weight.

The film or fiber of the present invention can be obtained by a generally known method.

First, for the film, crystalline thermoplastic polyester (A) and amorphous thermoplastic polyester (■) are melt-mixed in a tn-axis or twin-screw extruder, and the resulting mixture is passed through a T-die or circular die into a film. For example, an unstretched film is obtained by melt extrusion and cooling with a casting roller or gas or liquid, and then stretched. In the case of uniaxial stretching, the stretching ratio is preferably 1.5 times or more.

In addition, an even better film can be obtained by (2) transverse biaxial stretching. In this case as well, it is preferable to stretch the film by 1.5 times or more in each direction.As the stretching method for the film, uniaxial stretching, sequential two-wheel stretching, simultaneous biaxial stretching, etc. can be adopted, and two stretching devices are used for this [I - A single type axial stretching machine, a transverse stretching machine with a set of tenters, a simultaneous biaxial stretching machine with a set of tenters or a single bra set, etc. are applicable.

In the case of fibers, it is almost the same, and a method is adopted in which the molten mixture described in i) is extruded from a spinneret, the discharged yarn is cooled in gas to obtain an undrawn yarn, and this is stretched. Ru.

In order to improve dimensional stability, which is the objective of the present invention, it is preferable to heat set the film or fiber after stretching, and usually the melting point of the crystalline thermoplastic polyester (A) is -50°C to crystalline. The thermoplastic polyester (B) may be heat-treated in a relaxed, fixed length or stretched state within the melting point range of the thermoplastic polyester (B).

〔Example〕

Hereinafter, the present invention will be further explained in detail with reference to Examples.

(Reference example) Synthesis of high Tg amorphous polyester 50 mol parts of dimethyl terephthalate, 10 mol parts of dimenal isophthalate, dimethyl ester of 1,1.3-trimethyl-3-phenylindyne-4',5-dicarboxylic acid 40 mol parts of ethylene glycol, 150 mol parts of ethylene glycol, and 0.02 mol part of manganese acetate were transesterified at normal pressure while raising the temperature from 150°C to 200°C. 0.02 mol part of antimony oxide was added and polycondensation was carried out at 270° C. for 3 hours under reduced pressure of 0.1 torr. '1゛g of the obtained polyester is 125℃
in a heavy mixed solvent such as phenol/tetrachloroethane.
．． The relative viscosity measured at 20°C at a concentration of 5 g/a is 1.
It was 75. Further, no melting point was observed in DSC measurement. When this polyester and polybutylene terephthalate were melt-mixed in a glass test tube at 240° C. at a weight ratio of 1:1, a uniform and transparent state was obtained.

(Examples 1 to 3, Comparative Example 1) Polybutylene terephthalate (symbol A) and the polyester of the above-mentioned reference example (symbol 13) were melt-mixed at 240°C in various proportions shown in Table 1. Extrude from die 5
Rapidly cooled with a casting roller at 11°C to about 100°C.
An unstretched film of μ was obtained.

This unstretched film was stretched at a temperature of 100°C at a magnification of 3.0 times and 3°0 times in the width using a tenter-type simultaneous biaxial stretching device, and then subjected to constant length heat treatment at 200°C. A stretched film with a medium size of 400 mm was obtained. The stretching speed was 20 m/inch, and no problems such as cutting of the film occurred.

The strength, elongation, and dry heat shrinkage rate at 160° C. of the obtained film were measured. As shown in Table 1, it was confirmed that the addition of high Tg amorphous polyester had a good effect on dimensional stability.

Table 1 (Note) Physical properties are measured in the length direction of the film.

(Effects of the Invention) The polyester film or fiber of the present invention has excellent dimensional stability and good IL productivity, and is useful as a packaging film, an industrial film, a fiber for clothing, a fiber for industrial materials, and the like.

Claims (1)

[Claims] A polyester system consisting of a compatible mixture of a crystalline thermoplastic polyester (B) and an amorphous thermoplastic polyester (B) having a higher glass transition temperature than the crystalline thermoplastic polyester (A) and oriented in at least one axis. film or fiber.