JPH01168709A - Syndiotactic polystyrene film - Google Patents

Abstract

PURPOSE:To obtain excellent heat resistance, chemical resistance and mechanical strength and to attempt to improve transparency, by using a syndiotactic polystyrene having a specified wt.-average MW. CONSTITUTION:The title film having a total optical transmittance of 90% or higher and a density of 1.00-1.15 at 25 deg.C is formed by heat-molding, drawing, quenching and heat-treating a syndiotactic polystyrene having a wt.-average MW of 10<4>-10<6> (measured in 1,2,4-trichlorobenzene at 130 deg.C by means of gel permeation chromatography). This film is suitably used for a variety of wrapping materials and insulating materials. The raw material polystyrene may have a substituent such as Cl, CH3, etc., in its uncleus and is obtd. by polymerizing a raw material styrene in the presence of a catalyst composed of a Ti compd. such as titanium halide and an alkylaluminoxane.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to syndiotactic polystyrene films,
More specifically, it relates to syndiotactic polystyrene films that have excellent characteristics such as transparency, heat resistance, chemical resistance, 1-dimensional stability, mechanical strength, and low equilibrium moisture content. It is.

Conventional technology Traditionally, polystyrene film is glossy and transparent.

It has characteristics such as excellent visible light transmittance and low water absorption rate and moisture absorption rate, and is widely used as a variety of packaging materials.It also has excellent electrical properties such as dielectric constant and dielectric loss tangent. It is also widely used as an electrical insulating material for capacitors, high-frequency cable insulation, polyvariconders, and their cell edges.

This polystyrene film is industrially manufactured by forming a polystyrene film obtained by radical polymerization using methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. Polystyrene obtained by such radical polymerization usually has an atactic structure and does not have stereoregularity.

By the way, polystyrene resins that support stereoregularity include those with an isotactic structure.

It is known that the former isotactic structure is mainly obtained by polymerization using a Ziegler type catalyst, while the latter syndiotactic structure is known to be obtained by polymerization using a Ziegler type catalyst. It is known that it can be obtained by monopolymerization in the presence of a catalyst consisting mainly of a combination of a titanium compound such as titanium halide or alkoxy titanium and an alkylaluminoxane (Japanese Patent Laid-Open No. 104818/1983).

These polystyrene resins with stereoregularity have a higher melting point than polystyrene resins with an atactic structure that do not have stereoregularity.

Since it also has excellent chemical resistance, it is expected to be used as a heat-resistant and chemical-resistant polymer.

One of its uses is film.

Although isotactic polystyrene has a high melting point, it has an extremely slow crystallization rate (1) and only brittle films can be obtained using normal molding methods. A method has been proposed in which a film is formed at a relatively low temperature and then stretched at an appropriate temperature to remove the low molecular weight organic compound to produce an isotactic polystyrene film with excellent heat resistance and chemical resistance. (Unexamined Japanese Patent Publication No. 62-130
Publication No. 826).

On the other hand, syndiotactic polystyrene has a high melting point of about 270°C, and its crystallization rate is also a problem that the invention aims to solve. Since the speed is fast, it can be used as a film with excellent heat resistance and chemical resistance, but the drawback is that the usual molding method can only produce a white, opaque and brittle film. As in the case of isotactic polystyrene, a film produced by forming a film using a film-forming medium and then stretching it has the disadvantage that it inevitably becomes opaque.

The present invention overcomes the drawbacks of conventional syndiotactic polystyrene and syndiotactic polystyrene, and provides excellent heat resistance and chemical resistance.

This was done with the aim of obtaining a polystyrene film that has mechanical strength and good transparency.

Means to Solve the Problems The inventors of the present invention have conducted intensive research to develop a polystyrene film with excellent physical properties.

A film of a specific density obtained by uniaxially or biaxially stretching a film made of substantially amorphous syndiotactic polystyrene having a specific weight average molecular weight has surprisingly excellent transparency. The present invention was made based on this finding.

That is, 1 the present invention is based on gel permeation chromatography (1,2,4-)lychlorobenzene containing 130
The weight average molecular weight (measured at °C) is 10.000 to 1,
In the range of 000,000. Consists of syndiotactic polystyrene with or without nuclear substituents, and has a total light transmittance of 90% or more and 1.00 to 1.15
Polystyrene-based resins have a special geotactic structure and have a density in the range of 20 to 30. The phenyl groups or substituted phenyl groups, which are side chains, are mainly located alternately in opposite directions with respect to the main chain formed from carbon-carbon bonds. Its toughness can be determined by nuclear magnetic resonance (NMR). (by this NMR method)
Toughness to be measured can be expressed by the abundance ratio of consecutive constituent units (1), for example, 2 in the case of diats, 3 in the case of triats, and 5 in the case of pentads. The polystyrene resin having a syndiotactic structure as used in the invention usually means one having a syndiotactic structure of 85% or more in terms of diad or 50% or more in pentad.

Examples of the polystyrene resin include polystyrene as well as various nuclear-substituted polystyrenes such as polyalkylstyrene and polyhalogenated styrene. Specific examples of nuclear-substituted polystyrene include poly(o-, m- or p-
methylstyrene), poly(2,4-12,5-13,4
- or 3,5-dimethylstyrene), poly(pt-7
poly(alkylstyrene), poly(o-, m- or p-chlorostyrene), poly(o-,
m- or p-bromostyrene), poly(o-, m-
or p-fluorostyrene), poly(0-methyl-p-
Poly(halogenated styrene) such as fluorostyrene)
, poly(halogen-substituted alkylstyrene), poly(o-, m- or p-methoxystyrene), poly(o-
, m- or p-ethoxystyrene], and poly(carboxyalkylstyrene) such as poly(o-, m- is p-carboxymethylstyrene).

Poly(alkyl silyl styrene) such as poly(p-vinylbenzylprobyl ether), poly(alkyl ether styrene), poly(p-)limethylsilyl styrene), and even poly(vinylbenzyl dimethoxy phosphide). Can be mentioned.

In the present invention, among the above polystyrene resins,
In particular, polystyrene obtained by polymerizing styrene is suitable. Furthermore, the polystyrene resin having a syndiotactic structure used in the present invention does not necessarily have to be a single compound, and as long as the syndiotacticity is within the above range, the polystyrene resin having an isotactic structure or an atactic structure can be used. It may be a mixture with or incorporated into a copolymer chain.

The polystyrene resin having the syndiotactic structure described above uses styrene derivatives such as styrene, alkyl styrene, and halogenated styrene as raw material monomers.
For example, it can be produced by polymerization in the presence of a catalyst consisting of a combination of a titanium compound such as titanium halide or alkoxytitanium and alkylaluminoxane. Polystyrene resins with high syndiotacticity can be obtained by such polymerization methods, but if necessary, by fractionation using a solvent etc., it is possible to obtain a syndiotacticity close to 1100%. It is also possible to obtain a polystyrene resin having the following properties.

To produce the film of the present invention, first, the thus obtained polystyrene resin whose stereoregularity is a syndiotactic structure is molded into a substantially amorphous film. There are no particular restrictions on the method of forming this substantially amorphous film, but 1. Usually, the film is heated and formed using a press or T-die at a temperature higher than the melting point of the polystyrene resin, and then the film is formed using a cooling press or cooling roll. A substantially amorphous syndiotactic polystyrene film can be obtained by rapid cooling using a cooling tank or a cooling tank, preferably at a temperature decreasing rate of 150° C./min or more.

At this time, if the cooling rate is slow, crystallization progresses, causing opacity and embrittlement.

The substantially amorphous film thus obtained is then stretched at a temperature in the range above its glass transition temperature and below its cold crystallization temperature. The above-mentioned glass transition temperature and cold crystallization temperature vary depending on the type of polystyrene resin and the value of syndiotacticity.1 For example, in polystyrene with syndiotacticity of 99% or more, the glass transition temperature is 93%. ℃, cooling crystallization temperature is 1
The stretching temperature was 44° C. and the melting point was 268° C. If the stretching temperature exceeds the above range, a film having desired physical properties cannot be obtained and the object of the present invention cannot be achieved.

Furthermore, there is no particular restriction on the stretching method, and conventionally used methods such as simultaneous or sequential biaxial stretching, or -axial stretching using a rolling device, elongation stretching device, etc. can be used. .

Next, the stretched film thus obtained.

Further, it is heat-treated under tension at a temperature in the range above the cold crystallization temperature and below the melting point. A sufficient time for this heat treatment is about 10 minutes to 2 hours. Without such heat treatment, a film with sufficiently satisfactory physical properties cannot be obtained.

The film thus obtained needs to have a density at 25° C. in the range of 1.00 to 1.15. Anything outside this range will not have the desired physical properties.

Effects of the Invention The syndiotactic polystyrene film thus obtained has excellent characteristics such as excellent transparency, heat resistance, chemical resistance, dimensional stability, mechanical strength, and low equilibrium moisture content. have.

In particular, as a film with excellent heat resistance and chemical resistance, it is suitably used as various packaging materials and insulating materials.

Examples Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

The content of methyl ethyl ketone insoluble parts in one example was determined by the formula: content of methyl ethyl ketone insoluble parts (4) - weight of total produced polymer.

Example 1 (1) Production of syndiotactic polystyrene 600 td of toluene was placed in a stainless steel autoclave with an internal volume of 1500 ml and purged with inert gas. : ) Tylaluminoxane (manufactured by Toyo Stouffer) 120 mmo
1 and 6 mmol of tetraethoxy titanium were added, and then 600% of styrene was added and a polymerization reaction was carried out at 50° C. for 2 hours. After the reaction was completed, the reaction was stopped using hydrochloric acid-methanol, and the resulting polymer was filtered off.

Dry. The resulting polystyrene was 922.

The content of the methyl ethyl ketone insoluble part in this polystyrene is 96%, and the stereoregularity of this insoluble part is "C-N
As a result of MR spectrum analysis, it was found to have a syndiotactic structure with 99 or more molecules. Moreover, the weight average molecular weight of this syndiotactic polystyrene measured by gel permeation chromatography (measured in 1,2,4-trichlorobenzene at 130°C) is 48.7 × 1
04, and the melting point measured using a differential scanning calorimeter is 2.
The temperatures were 56°C and 266°C.

(2) Production of syndiotactic polystyrene film The syndiotactic polystyrene described above.

After press molding at 310° C., it was rapidly cooled to room temperature using a cooling press to obtain a transparent, substantially amorphous film having a density of 1.05 f/cI/i.

When this substantially amorphous film was subjected to calorimetric analysis using a differential scanning calorimeter, the glass transition temperature was 93°C, the cold crystallization temperature was 144°C, and the melting point was 268°C.

Place this film on a film stretcher at 110°C.
So 3. OX 3.0 simultaneous biaxial stretching and further stretching at 160℃ for 30 minutes while set on a film stretcher.
Heat treated for minutes.

The obtained film has a density of 1, lot/d, total light transmittance of 92.5%, and a Young's modulus of 700 to 9/cd, at 150°C for 10 minutes. No heat shrinkage was observed.

Comparative Example 1 In Example 1, after press molding at 310° C., the density was not quenched at room temperature without being rapidly cooled using a cooling press, and the density was 1.
A white, opaque, crystalline, brittle film of 0.08 was obtained.

This film was stretched to 110℃ using a film stretcher.
So 3. When OX 3.0 was simultaneously biaxially stretched, the film broke during stretching and could not be stretched.

Comparative Example 2 Stretching was carried out in the same manner as in Example 1, except that the stretching temperature and the heat treatment temperature were each 145°C.

The obtained film was white and opaque with a density of 1.09 f/-, a Young's modulus of 620/9/cd, and a heat shrinkage rate of 9% at 150°C for 10 minutes. Ta.

Example 2 Stretching was performed in the same manner as in Example 1 except that the heat treatment temperature was 210°C.

The obtained film had transparency with a total light transmittance of 92.7% at a density of 1.11 f/'cd, a Young's modulus of 740 y/di, and a temperature of 200°C and 10%.
No heat shrinkage was observed within minutes.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1 Gel permeation chromatography (1,2
, 4-trichlorobenzene at 130° C.) with a weight average molecular weight in the range of 10,000 to 1,000,000, with or without nuclear substituents; % or more and a density in the range of 1.00 to 1.15.