JPH1053679A - Styrene polymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a styrene polymer composition capable of exhibiting excellent strength, moldability and heat-resistance in balanced state without deteriorating the transparency and useful in the field of food container, light electric appliance, etc., by compounding a styrene polymer with a specific lubricant and an inorganic filler having a specific particle diameter. SOLUTION: This composition is produced by compounding (A) 100 pts.wt. of a styrene polymer with (B) 0.001-3 pts.wt. of an inorganic filler having an average particle diameter of 0.001-10μ (e.g. barium sulfate or calcium carbonate) and (C) 0.001-3 pts.wt. of a lubricant consisting of a higher fatty acid (e.g. stearic acid or behenic acid), a higher fatty acid salt (e.g. zinc stearate or sodium stearate) or a higher fatty acid amide (e.g. stearylamide or ethylenebisstearylamide).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Styrene polymers have excellent transparency and moldability and are inexpensive, and are used in a wide range of fields such as food containers and light electric appliances. However, styrene polymers are other transparent resins (especially, styrene-acrylonitrile copolymers,
Styrene-based polymer such as styrene-methyl methacrylate copolymer). 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 a styrene polymer, the molecular weight of the polymer is increased. However, when the molecular weight is increased, the fluidity deteriorates. Therefore, a plasticizer such as mineral oil is generally added for the purpose of improving the fluidity. When a plasticizer is added, the fluidity improves, but the heat resistance decreases. Thus, considering the balance between practical strength, moldability and heat resistance, the current styrene polymer has not been sufficiently satisfactory.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a styrene polymer composition having an excellent balance of strength, moldability and heat resistance, especially a styrene polymer composition having excellent practical strength. It is in.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have impaired the transparency of styrene polymers, in particular, by adding specific amounts of specific inorganic fillers and specific lubricants to styrene polymers. Thus, a styrene polymer composition having excellent practical strength was completed.

That is, the present invention relates to a styrene polymer 100
0.001 to 3 parts by weight of an inorganic filler having an average particle diameter of 0.001 to 10 microns, and at least one lubricant selected from the group consisting of higher fatty acids, higher fatty acid salts and higher fatty acid amides with respect to parts by weight. And a styrene polymer composition characterized by containing

The object of the present invention is to improve the practical strength of a resin by adding a small amount of an inorganic filler having a fine particle size and a specific lubricant to a styrene polymer without significantly impairing transparency. For example, by adding a small amount of a fine inorganic filler and a specific lubricant to a high-strength type styrene polymer, an AS resin (styrene-acrylonitrile copolymer) which is more excellent in practical strength than a high-strength type styrene polymer The styrene polymer resin composition having a practical strength close to that of the above) can be produced.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The styrene polymer used in the present invention is generally molded polystyrene (GPPS) having a weight average molecular weight in the range of 100,000 to 500,000.

Examples of the styrene compound which is a monomer constituting the styrene polymer include styrene, α-substituted alkylstyrene such as α-methylstyrene, and nucleus-substituted alkylstyrene such as p-methylstyrene. As a polymerization method for the styrene polymer, a batch suspension polymerization method or a continuous bulk polymerization method can be used, and any of a radical polymerization method such as thermal polymerization or polymerization using an initiator can be used.

The inorganic filler used in the present invention includes calcium carbonate, talc, magnesium hydroxide, clay, silica, barium sulfate, titanium oxide, zinc oxide, magnesium oxide, mica, potassium iodide, lithium hydroxide, and aluminum sulfate. Sodium, iron sulfate, potassium hexafluorophosphate, sodium tripolyphosphate and the like. Among these, barium sulfate and / or calcium carbonate are preferred.

In the present invention, the average particle size of the inorganic filler is 0.001 to 10 microns, preferably 0.005 to 5 microns. If the average particle size is less than 0.001 micron, the dispersibility is extremely poor and the resin cannot be uniformly dispersed in the resin. If the average particle size of the inorganic filler exceeds 10 microns, no improvement in practical strength is observed. On the other hand, if the average particle size exceeds 10 microns, the haze value of the styrene polymer molded article becomes undesirably large even if the amount of the inorganic filler is extremely small. Considering the balance between practical strength and transparency, the average particle size of the inorganic filler is 0.001 to 10 microns,
Preferably it is 0.005 to 5 microns.

In the present invention, the amount of the inorganic filler is 0.001 to 3 parts by weight, based on 100 parts by weight of the styrene polymer.
Preferably, it is 0.001-1 part by weight. If the amount is less than 0.001 part by weight, the effect of improving the practical strength cannot be obtained. On the other hand, if the amount exceeds 3 parts by weight, the haze value of the styrene polymer molded article is undesirably increased.

Further, the styrene polymer composition of the present invention comprises:
It is essentially GPPS with improved strength and transparency is important. Haze value for 3mm thick plate (ASTM
D1003) is preferably 5.0 or less. The haze value is greatly affected by the amount of the inorganic filler added, the average particle diameter, the type of the inorganic filler, and the like. For example, 2-3
If it is barium sulfate having a particle size of microns, the addition amount is 0.001 to 0.05 with respect to 100 parts by weight of the styrene polymer.
Parts by weight are preferred. If barium sulfate has a particle diameter of 0.02 to 0.03 micron, the addition amount is preferably 0.01 to 1.0 part by weight based on 100 parts by weight of the styrene polymer.
That is, the optimum addition amount is affected by the difference in the addition amount of the inorganic filler, the particle size, and the type of the inorganic filler.

In order to disperse the inorganic filler satisfactorily and to obtain good releasability between the mold and the resin at the time of molding, the filler is selected from the group consisting of higher fatty acids, higher fatty acid salts and higher fatty acid amides. At least one lubricant is added. The addition amount is based on 100 parts by weight of the styrene polymer.
It is 0.001 to 3 parts by weight, preferably 0.01 to 1 part by weight. If the amount is less than 0.001 part by weight, a substantial effect cannot be obtained. If the amount exceeds 3 parts by weight, the heat resistance becomes too low, the transparency becomes poor, and the mold stain becomes unfavorable. Fatty acids constituting these lubricants are selected in the range of 10 to 25 carbon atoms per molecule, and preferably 12 to 22 carbon atoms. If the number of carbon atoms is less than 10, mold staining is severe, and if it is more than 25, transparency is deteriorated, which is not preferable. Representative examples of higher fatty acids and higher fatty acid salts include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid,
Behenic acid and the like, and their Periodic Table Groups I and II
And salts of metals belonging to Group III, III and IV.
Among these, stearic acid, behenic acid, zinc stearate, calcium stearate, and sodium stearate are preferred. Representative examples of the higher fatty acid amide include stearic acid amide, oleic acid amide, ethylenebisstearylamide and the like.

In the method for producing a styrene polymer composition of the present invention, an inorganic filler and / or a lubricant may be added at the time of polymerization of the styrene polymer, or a styrene polymer pellet or powder and an inorganic filler and / or It can also be manufactured by melt-kneading a lubricant with a molding machine such as an extruder. In addition, it is directly molded with the inorganic filler and the lubricant uniformly attached to the surface of the styrene polymer pellet, or the lubricant is uniformly attached to the surface of the styrene polymer pellet into which the inorganic filler is kneaded. It can also be used for molding products.

The styrene polymer composition of the present invention may contain, if necessary, a stabilizer against heat, light and oxygen (for example, an antioxidant such as a phenol compound or a phosphorus compound; a benzotriazole compound or a benzophenone compound). , A phenyl salicylate compound or the like; an ultraviolet absorber; a hindered amine stabilizer); a plasticizer such as liquid paraffin; an antistatic agent; and an additive such as a colorant. In addition to these additives, a small amount of HIPS or SBS elastomer may be added as needed. However, it is preferable that the haze value (ASTM D1003) of the final styrene polymer resin composition on a 3 mm thick plate be within a range of 5.0 or less.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.

Examples 1 to 5 and Comparative Examples 1 to 4 By blending according to the blending recipe shown in Table 1, melt-kneading at 220 ° C. with a twin screw extruder, and subjecting the mixture to injection molding at 220 ° C. Test pieces were prepared and physical properties were measured. Table 1 shows the results. In addition, the measuring method of each physical property is as follows.

(1) Haze value: Measured according to ASTM D1003. The test piece thickness was 3 mm. (2) Izod impact strength: Measured according to JIS K6871. (3) Falling ball impact test: Color plate molded product (width 100mm)
× length 350 mm × thickness 3 mm), and was placed on a table having a concave portion formed thereon. A steel ball of 50 g was dropped toward the concave portion, and the presence or absence of breakage of the molded product was visually observed. From the height of the drop at which the probability of breakage of the molded article was 50%, it was converted into an energy standard and expressed as 50% break energy. (4) Appearance: The molded article was visually observed, and the ones with little or no glitter were marked as "good", and those with glitters markedly marked as "bad".

[0020]

[Table 1]

The abbreviations in Table 1 are as follows. GPPS-1; high-strength type GPPS (weight average molecular weight
350,000) GPPS-2: High strength type GPPS (weight average molecular weight)
320,000) AS resin; SEvian N050 (manufactured by Daicel Chemical Industries, Ltd.) BF-20; barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.),
Average particle size 0.03 μm BMH; barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.),
Average particle size 2.5 μm.

Example 6 A styrene resin and an inorganic filler were melt-kneaded at 220 ° C. in a twin-screw extruder in the same formulation as in Example 1 to obtain pellets containing the inorganic filler. The same amount of lubricant as in Example 1 was added to the pellets, mixed well with a tumbler, and the lubricant was attached to the pellet surface. The resulting pellets had better fluidity than the pellets obtained in Example 1. The pellets were subjected to injection molding at 220 ° C. to prepare test pieces, and the physical properties were measured. The same values as in Example 1 were obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C08K 5/20 KFZ C08K 5/20 KFZ

Claims (6)

[Claims] 1. An inorganic filler having an average particle diameter of 0.001 to 10 microns per 100 parts by weight of a styrene polymer.
To 3 parts by weight and at least one lubricant selected from the group consisting of higher fatty acids, higher fatty acid salts and higher fatty acid amides
A styrene polymer composition comprising 0.001 to 3 parts by weight. 2. The styrene polymer composition according to claim 1, wherein the inorganic filler has an average particle size of 0.005 to 5 microns. 3. The styrene polymer composition according to claim 1, wherein the inorganic filler is barium sulfate and / or calcium carbonate. 4. A haze value (AST) for a 3 mm thick plate.
The styrene polymer composition according to any one of claims 1 to 3, wherein MD 1003) is 5.0 or less. 5. An inorganic filler having an average particle size of 0.001 to 10 microns per 100 parts by weight of a styrene polymer.
At least one lubricant selected from the group consisting of higher fatty acids, higher fatty acid salts and higher fatty acid amides, on the surface of a styrene polymer pellet melt-kneaded at 〜3 parts by weight;
A styrene polymer composition in which parts by weight are uniformly attached. 6. An inorganic filler having an average particle size of 0.001 to 10 microns per 100 parts by weight of a styrene polymer.
At least one lubricant selected from the group consisting of higher fatty acids, higher fatty acid salts and higher fatty acid amides, on the surface of a styrene polymer pellet melt-kneaded at 〜3 parts by weight;
A method for molding a styrene polymer composition, which is directly applied to a molded article as it is in a state where parts by weight are uniformly attached.