JPH09208769A - Styrenic resin composition and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a styrenic resin composition having improved practical strength and transparency of a styrenic resin by adding a small amount of a water-soluble inorganic compound to a styrenic polymer. SOLUTION: This styrenic resin composition contains (A) 100 pts.wt. of a styrenic polymer and (B) 0.0005-0.1 pt.wt., preferably 0.0005-0.0002 pt.wt. of a water-soluble inorganic compound. As the component B, potassium dihydrogenphosphite, sodium nitrite or molybdenum oxide, etc., providing slight bright points caused to inorganic fine particles dispersed in a molded product in viewing through the molded product made of the objective composition and having excellent appearance is preferable. The objective composition is obtained by adding an aqueous solution composed of water corresponding to 0.5-1 pt.wt. and the component B corresponding to 0.0005-0.1 pt.wt. into 100 pts.wt. of styrenic monomer at the time of polymerization, or adding the aqueous solution to 100 pts.wt. of the component A and blending, and evaporating moisture in the polymerizing time or the blending time to uniformly disperse the component B.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to transparency, moldability,
The present invention relates to a styrene resin composition excellent in practical strength and cost performance.

[0002]

BACKGROUND OF THE INVENTION Styrene polymers are used in a wide range of fields such as food containers and housings for home appliances because they are excellent in transparency and moldability and inexpensive. However, the styrene resin has a weak point that it is inferior in impact strength. In particular, in the case of a deep-bottom box-shaped molded product, there is often a problem that the molded product is cracked at the time of release from a mold for injection molding.

Generally, in order to increase the practical strength of styrene polymers, the molecular weight of the polymers is increased. However, if the molecular weight is increased, the fluidity deteriorates. Therefore, a plasticizer such as mineral oil is often added for the purpose of improving the fluidity. Addition of a plasticizer improves the fluidity but decreases the heat resistance. Thus, considering the balance of practical strength, moldability, and heat resistance, the current styrene polymers are not sufficiently satisfactory.

In order to solve these problems, Japanese Patent Laid-Open No. 7-
Japanese Patent No. 228737 discloses a styrene resin composition obtained by adding specific fine particles, and realizes improvement in impact strength. However, in the invention, the refractive index, particle size, and glass transition temperature of the fine particles used are limited, and the application thereof is somewhat limited.

[0005]

An object of the present invention is to improve the practical strength and transparency of a styrene resin by adding a small amount of a water-soluble inorganic compound, which could not be achieved by the prior art.

[0006]

The object of the present invention is to provide a styrene resin composition containing 0.0005 to 0.1 part by weight of a water-soluble inorganic compound with respect to 100 parts by weight of a styrene polymer. The water-soluble inorganic compound is one or more compounds selected from potassium dihydrogen phosphite, sodium tripolyphosphate, sodium nitrite, lithium hydroxide, sodium hydroxide, molybdenum oxide, and copper sulfide. This can be easily achieved with a styrenic polymer composition.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The styrenic polymer in the present invention means a homopolymer such as α-substituted alkylstyrene such as styrene and α-methylstyrene, a nucleus-substituted alkylstyrene such as p-substituted alkylstyrene, and the like. A compound copolymerizable with the monomer, for example, acrylonitrile, methacrylic acid, vinyl monomers such as ester derivatives such as methyl methacrylate, and further maleic anhydride,
It may be a copolymer with maleimide or a nucleus-substituted maleimide.

The water-soluble inorganic compound blended in the styrene resin composition of the present invention is not particularly limited as long as it is a solid at room temperature (25 ° C.) and can be dissolved in water at 90 ° C. or higher. , Crystal form, and the presence or absence of crystal water.

For example, potassium iodide, sodium chloride, sodium aluminum sulfate dodecahydrate, cesium aluminum sulfate dodecahydrate, thallium aluminum sulfate dodecahydrate, aluminum tetrahydroborate, barium oxide, cadmium chloride, tetracyanocadmium. Potassium acid, potassium tetracyanomercuric acid (II), potassium chloride, magnesium sulfate, potassium hexafluoroline (V), dodecamolybdophosphoric acid 30 hydrate,
Examples thereof include one or more compounds selected from ammonium chloride, sodium bromate, sodium molybdate, silver hexafluoroantimonate (V), strontium chloride, strontium nitrate, zinc iodide and the like.

Particularly preferred water-soluble inorganic compounds are:
When seeing through the molded article obtained from the composition of the present invention,
There are few bright spots due to the inorganic fine particles dispersed in the molded product, and by excellent appearance characteristics, potassium dihydrogen phosphite, sodium tripolyphosphate, sodium nitrite,
Lithium hydroxide, sodium hydroxide, molybdenum oxide,
Examples include one or more compounds selected from copper chloride.

The amount of the water-soluble inorganic compound added is 0.0005 to 0.1 part by weight, preferably 0.0005 to 0.05 part by weight, more preferably 0 to 100 parts by weight of the styrene polymer. 0.0005 to 0.0002 parts by weight.

If it is less than 0.0005 parts by weight, the effect of improving the practical strength is not observed, and if it is more than 0.1 parts by weight, the transparency of the obtained molded product is impaired.

In the method for producing the styrene resin composition of the present invention, an aqueous solution of an inorganic compound is added during the polymerization of the styrene polymer. Alternatively, a method of adding an aqueous solution of an inorganic compound to the styrene-based polymer at the time of melt-kneading with an extruder or the like can be selected.

Moisture in the aqueous solution is volatilized during the polymerization or kneading process, and as a result, the inorganic compound is uniformly dispersed in the styrene polymer matrix.

The amount of water of the inorganic compound aqueous solution to be added must be 0.5 to 1.0 part by weight based on 100 parts by weight of the styrene polymer. When the amount is 1.0 part by weight or more, foaming due to water is observed in the molded product obtained from the styrene resin composition,
If it is 0.5 parts by weight or less, the dissolution of the inorganic compound becomes insufficient, and the inorganic compound cannot be uniformly dispersed in the styrene polymer matrix.

In the styrene resin composition of the present invention, if necessary, known antioxidants such as phenol compounds and phosphorus compounds, UV absorbers such as benzotriazole compounds, benzophenone compounds and phenyl salicylate compounds. A hindered amine stabilizer, a lubricant such as liquid paraffin, ethylenebisstearylamide, metal soap, a release agent, an antistatic agent, and an additive such as a colorant may be used.

[0017]

The present invention will be described in detail below with reference to examples.

Example 1 Table 1 shows that the amount of sodium chloride added is 0.005 parts by weight based on 100 parts by weight of base resin pellets (manufactured by Daicel Chemical Industries Ltd., Daicel Styrol 53). The aqueous solution of the inorganic compound was added, and this was heated at 220 ° C. using a 30 mmΦ twin-screw extruder.
Then, it was melt-kneaded and pelletized.

The composition thus obtained was 3 mm in an injection molding machine with a screw diameter of 25 mmΦ and a mold clamping pressure of 100 t.
A thick flat plate was formed into a test piece, and DuPont impact strength and haze were evaluated.

The DuPont impact strength is measured according to JIS.
K5400 and haze were measured according to ASTM D1003. Table 1 shows the evaluation results.

(Examples 2 to 27, Comparative Examples 1 to 5) Evaluations were made in the same manner as in Example 1 except that the kind and addition amount of the inorganic compound were changed. The results are shown in Table 1.

[0022]

According to the present invention, it is possible to improve the practical strength and transparency of a styrene resin by adding a small amount of a water-soluble inorganic compound, which could not be achieved by the conventional techniques. Further, it can be easily obtained by dissolving it in water and adding it to the base resin, or by adding it at the time of polymerization, and the particle size of the inorganic compound is not limited.

[0023]

[Table 1]

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Claims (3)

[Claims] 1. To 100 parts by weight of a styrene-based polymer,
A styrene resin composition containing 0.0005 to 0.1 part by weight of a water-soluble inorganic compound. 2. The water-soluble inorganic compound is one or more compounds selected from potassium dihydrogen phosphite, sodium tripolyphosphate, sodium nitrite, lithium hydroxide, sodium hydroxide, molybdenum oxide and copper chloride. The styrene polymer composition according to claim 1. 3. 0.5 to 1.0 part by weight of water and 0.00
An aqueous solution containing 05 to 0.1 parts by weight of a water-soluble inorganic compound is added at the time of polymerization of 100 parts by weight of a styrene-based monomer, or 100 parts by weight of a styrene-based polymer is added and kneaded to polymerize water. The method for producing a styrene-based polymer according to claim 1 or 2, wherein the inorganic compound is uniformly dispersed by volatilizing during or during kneading.