JPH0723428B2 - Method for molding styrene-based polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved method for molding a styrenic polymer. More specifically, the present invention provides a styrenic polymer having stereoregularity that is substantially a syndiotactic structure, using a specific solvent, for example, cast products, films, sheets, laminates, coating films, etc. The present invention relates to a method of molding extremely easily.

[Conventional technology]

Conventionally, as a method for producing a styrene-based polymer, methods such as radical polymerization, cationic polymerization, anionic polymerization, polymerization with a transition metal complex catalyst, and radiation polymerization are known.
Ordinary styrenic polymers are produced by radical polymerization.

The styrene polymer produced by this radical polymerization method has an atactic structure in its stereoregularity,
Various molding methods, such as injection molding, extrusion molding, blow molding,
It is molded into various shapes by methods such as vacuum molding and injection molding. For example, household electric appliances, office equipment,
Widely used as household products, packaging containers, toys, furniture, synthetic paper, and other industrial materials.

By the way, the inventors of the present invention polymerize a styrene monomer by using a catalyst composed of a special transition metal compound and an organoaluminum compound, and thereby have a stereoregular styrene-based styrene-based structure. It was found that a polymer was obtained. However, the styrene-based polymer having such a syndiotactic structure is remarkably different in physical properties from the one having the atactic structure described above, and has a very high melting point, and thus it is difficult to perform thermoforming similar to that. In addition, there is a problem in that its chemical properties are different from those having an atactic structure, for example, in its solubility in a solvent, and it cannot be handled in the same manner even in a molding method using a solvent.

[Problems to be solved by the invention]

Under such circumstances, an object of the present invention is to provide a method for easily molding various shapes of a styrene-based polymer having substantially stereoregular syndiotactic structure.

[Means for solving problems]

The present inventors have conducted extensive studies on a method for molding a styrene-based polymer having stereoregularity which is a substantially syndiotactic structure, and as a result, by molding the polymer using a specific solvent, The inventors have found that the above objects can be achieved, and have completed the present invention based on this finding.

That is, the present invention provides a styrene-based polymer having a substantially syndiotactic structure with at least one selected from aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, cyclic amides and cyclic ethers. After dissolving in a seed solvent and then casting, casting or coating the solution,
It is intended to provide a method for molding a styrene-based polymer, which comprises volatilizing the solvent.

Hereinafter, the present invention will be described in detail.

The styrene-based polymer used in the method of the present invention has a substantially syndiotactic structure. here,
A styrene-based polymer having a substantially syndiotactic structure means a styrene-based polymer having 50% or more of a racemic pentad by the magnetic resonance ( ¹³ C-NMR) analysis of isotope carbon having a syndiotactic structure. means. Examples of the styrene polymer include styrene, p-methylstyrene, m-methylstyrene, p-chlorostyrene, p-
Homopolymers such as fluorostyrene and copolymers thereof may be mentioned.

The styrene-based polymer having a syndiotactic structure in the above-mentioned practical example used in the method of the present invention can be produced, for example, by the following method. That is, it can be produced by polymerizing a styrene-based monomer in an inert hydrocarbon solvent or in the absence of a solvent, using a titanium compound and a condensation product of water and a trialkylaluminum as a catalyst.

In the method of the present invention, the solvent of the styrene polymer having a substantially syndiotactic structure is selected from aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, cyclic amides and cyclic ethers. At least one solvent is used.

Examples of the aromatic hydrocarbon include benzene, toluene, xylene, ethylbenzene, methylnaphthalene, and tetralin, and examples of the alicyclic hydrocarbon include cyclohexane, cyclohexene, methylcyclohexane,
Ethylcyclohexane, decahydronaphthalene, etc.
Examples of the halogenated hydrocarbon include dichloromethane,
Chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, trifluoroethane,
Examples of the cyclic amide include trichlene, curlbenzene, dichlorobenzene, trichlorobenzene, and the like.
-Methylpyrrolidone, N-ethylpyrrolidone and the like, and examples of the cyclic ether include tetrahydrofuran and dioxane. These solvents may be used alone or in combination of two or more.

In the method of the present invention, first, the above-mentioned styrene-based polymer having a substantially syndiotactic structure is dissolved in these solvents to prepare a molding solution. The concentration of the polymer in this solution is not particularly limited, but is usually selected in the range of 0.1 to 20% by weight. If this concentration is too low, it is difficult to mold a product having a desired thickness by a single step by a casting method or a coating method, and at the same time, it is economically disadvantageous due to the large amount of solvent, while it is too high. It becomes difficult to handle and mold because the viscosity becomes high and a gel-like substance is formed to make it non-uniform.

If desired, various additives that can be dissolved in the solvent used, such as an antioxidant, an ultraviolet absorber, a heat stabilizer, a flame retardant, an antistatic agent, and a colorant, can be added to this solution.

In the present invention, the solution thus prepared may be used as it is, or, if necessary, it may be used after removing insoluble matters existing in the solution by means such as filtration.

This filtering treatment is usually carried out by a pressure method using cotton cloth, flannel, glass wool, kana-kin and combinations thereof as a filter medium. When bubbles are present in the solution, if necessary, the bubbles may be removed by an appropriate method before use.

Then, the solution is poured into a mold having a desired shape, or
After being cast on the surface of a support made of metal or glass, or applied on the surface of a desired molded article, the solvent contained therein is volatilized. The method for volatilizing the solvent is not particularly limited and may be volatilized at room temperature,
It may be volatilized by heating to an appropriate temperature, or any method of volatilizing under normal pressure or under reduced pressure may be used.

When making a film or sheet, a method of casting the solution on a support made of metal or glass having a flat and uniform surface is usually used. At this time, it is industrially preferable to use a metal support, and examples of the metal support include those made of nickel, chromium, copper, or stainless steel, those plated with nickel, and copper on an iron base metal. And a layer having a nickel layer formed thereon, and a layer having an alloy layer of nickel and chromium provided on a base metal made of iron.

As a method for applying the solution to the surface of a molded body or the like, any conventionally used application method, for example, an immersion method, a brush application method, a spray method, or the like can be used.

By such a molding method, styrene-based polymers having a substantially syndiotactic structure can be easily obtained in various shapes, such as cast products, films, sheets, laminates and coating films.

Unlike the melt-molded products, the cast products, films, sheets, laminates, coating films, etc. obtained in this way do not cause a decrease in the molecular weight, so they have high mechanical strength, By performing the crystallization treatment, a molded product having a high melting point which cannot be imagined from conventionally known polystyrene can be obtained. The present invention provides a method for obtaining such a novel and useful molded article.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples.
The invention is in no way limited by these examples.

Production Example 1 Production of Polystyrene with Syndiotactic Structure Toluene 2 as a solvent, 20 mmol of cyclopentadienyl titanium toluchloride as a catalyst component, and 0.8 mol of methylaluminoxane as an aluminum atom were added to a reaction vessel, and styrene 3.6 at 20 ° C. Was added to carry out a polymerization reaction for 1 hour. After the reaction was completed, the product was washed with a hydrochloric acid-methanol mixed solution to decompose and remove the catalyst component. Then, it was dried to obtain 330 g of a polymer. Next, this polymer was subjected to Soxhlet extraction using methyl ethyl ketone as a solvent to obtain an extraction residue of 95% weight.

This polymer has a weight average molecular weight of 280000 and a number average molecular weight of 57.
000 and the melting point was 270 ° C. Further, this polymer was found to have an absorption at 145.35 ppm due to the syndiotactic structure from the analysis of the isotopic carbon by magnetic resonance ( ¹³ C-NMR), and the syndiotacticity of the pentad calculated from the peak area was It was 96%.

Production Example 2 Production of Polystyrene Copolymer with Syndiotactic Structure 60 ml of toluene as a reaction solvent, 0.05 mmol of tetraethoxytitanium and 5 mmol of methylaluminoxane as aluminum atoms were placed in a reaction vessel, and 0.45 mol of styrene and p-methyl at 50 ° C. 0.05 mol of styrene was added and a polymerization reaction was carried out for 2 hours.

After completion of the reaction, the product was washed with a mixed solution of hydrochloric acid and methanol to decompose and remove the catalyst component. Then, by drying, 6.4 g of a copolymer was obtained. Next, this copolymer is
Soxhlet extraction using methyl ethyl ketone as a solvent,
An extraction residue of 80% by weight was obtained. This extraction copolymer has a weight average molecular weight of 440,000 and a number average molecular weight of 240,000 and a melting point of
It was 227 ° C. The content ratio of the p-methylstyrene unit in this copolymer was 18 mol%. Further, this copolymer was found to have an absorption at 145.35 ppm by analysis by ¹³ C-NMR, and the syndiotacticity of the styrene unit in the pentad was 72%, which was calculated from the peak area.

Example 1 2.5 g of the polystyrene powder obtained in Production Example 1 and 47.5 g of chloroform were placed in a flask having an inner volume of 300 ml and dissolved by heating to obtain a transparent solution having a concentration of 5% by weight. The solution was poured into a petri dish and dried in hot air at 100 ° C to obtain a film.

Example 2 An aluminum piece having a thickness of 1 mm and a vertical length of 10 mm was immersed in a chloroform solution of polystyrene obtained in the same manner as in Example 1 for 5 seconds at room temperature, and then the aluminum piece was dried with hot air to give polystyrene. An aluminum piece was obtained which was covered with a thin film.

Example 3 2.5 g of the polystyrene powder obtained in Production Example 1 was mixed with paraxylene 4
By dissolving in 7.5 g, a paraxylene solution having a concentration of 5% by weight was obtained. This solution was poured into a petri dish and dried under reduced pressure at room temperature to obtain a film.

Example 4 2.5 g of the polystyrene powder obtained in Production Example 1 was dissolved in 47.5 g of N-methylpyrrolidone to obtain a 5% by weight methylpyrrolidone solution. This solution was poured into a petri dish and dried under reduced pressure at 70 ° C to obtain a film.

Example 5 2.5 g of the polystyrene powder obtained in Production Example 1 was mixed with ethylbenzene.
By dissolving in 47.5 g, a 5 wt% ethylbenzene solution was obtained. An aluminum piece similar to that of Example 2 was immersed in this solution at 100 ° C. for 5 seconds and taken out,
By drying under reduced pressure at room temperature, an aluminum piece coated with a polystyrene thin film was obtained.

Example 6 An aluminum piece coated with a polystyrene thin film was obtained by applying the ethylbenzene solution obtained in Example 5 to an aluminum piece similar to the above with a brush and then drying it under reduced pressure at room temperature.

Example 7 0.25 g of the polystyrene powder obtained in Production Example 1 was dissolved in 249.75 g of dichloromethane to obtain a solution having a concentration of 0.1% by weight. This solution was poured into a petri dish and dried at 60 ° C to obtain a film.

Example 8 1 g of the polystyrene powder obtained in Production Example 1 was dissolved in 99 g of tetrahydrofuran to obtain a solution having a concentration of 1% by weight. This solution was poured into a petri dish and dried at 60 ° C to obtain a film.

Example 9 A paraxylene solution was obtained by dissolving 2.5 g of the styrene copolymer powder obtained in Production Example 2 in 47.5 g of paraxylene. This solution was poured into a petri dish and dried under reduced pressure at room temperature to obtain a film.

Example 10 A decahydronaphthalene solution was obtained by dissolving 2.5 g of the styrene copolymer powder obtained in Production Example 2 in 47.5 g of decahydronaphthalene. This solution was poured into a petri dish and dried under reduced pressure at room temperature to obtain a film.

〔The invention's effect〕

The molding method of the styrene-based polymer of the present invention is a method of molding a styrene-based polymer having stereoregularity substantially a syndiotactic structure using a specific solvent, and by using this molding method, A cast product of a styrene-based polymer having a substantially syndiotactic structure and a thin film-shaped molded product such as a film, a sheet, a laminate, and a coating film can be manufactured very easily.

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Claims (1)

[Claims] 1. A styrene-based polymer having a substantially syndiotactic structure is selected from at least one selected from aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, cyclic amides and cyclic ethers. A method for molding a styrene-based polymer, which comprises dissolving in a solvent of a seed, casting, casting or coating the solution, and then volatilizing the solvent.