JPH1053680A - 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 while keeping the transparency of the base resin 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 (e.g. barium sulfate or calcium carbonate) composed of (B1 ) a fine inorganic filler component having an average particle diameter of 0.001-0.1μ and (B2 ) a coarse inorganic filler component having an average particle diameter of 1-10μm at a ratio satisfying the formula 2.0<= (W1 /ρ1 ) (W2 /ρ2 )<=1,000 (W1 and W2 are the compounding amounts of B1 and B2 , respectively; ρ1 and ρ2 are the specific gravity values of the components B1 and B2 , respectively) and (C) 0.001-3 pts.wt. of a lubricant consisting of a higher fatty acid (salt) or a higher fatty acid amide (e.g. stearic acid, zinc stearate or stearic acid amide).

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 a good balance of practical strength, moldability and heat resistance, especially a styrene polymer composition having excellent practical strength. Is to do.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by adding a specific inorganic filler and a specific lubricant to a styrene polymer in a specific amount, the transparency of the styrene polymer can be improved. A styrene polymer composition excellent in practical strength without any damage was completed.

That is, the present invention relates to a resin composition containing a styrene polymer, an inorganic filler and a specific lubricant, wherein 1) the amount of the inorganic filler is 100 parts by weight of the styrene polymer. 0.001 to 3 parts by weight, 2) the inorganic filler is a small particle inorganic filler component (average particle size:
R ₁ micron, specific gravity: ρ ₁ , compounding amount: W ₁ ) and large-particle inorganic filler component (average particle size: R ₂ microns, specific gravity:
ρ ₂ , compounding amount: W ₂ ), and the small particle inorganic filler component and the large particle inorganic filler component have the following relationship: a) 2.0 ≦ (W ₁ / ρ ₁ ) / (W ₂ / ρ ₂ ) ≦ 1000 b) 0.001 ≦ R ₁ ≦ 0.1 c) 1 ≦ R ₂ ≦ 10 3) The specific lubricant is at least one of a higher fatty acid, a higher fatty acid salt and a higher fatty acid amide, and The present invention relates to a styrene polymer resin composition, wherein the amount is 0.001 to 3 parts by weight based on 100 parts by weight of the styrene polymer.

According to the present invention, a small amount of a fine inorganic filler and a specific lubricant are added to a styrene polymer, and the use of a filler having a bimodal particle size distribution as the inorganic filler makes it possible to improve the transparency. It is intended to improve the practical strength of the resin without impairing it. For example, by adding a small amount of an inorganic filler having a bimodal particle size distribution and a specific lubricant to a high-strength type styrene polymer, an AS resin having more practical strength than the high-strength type styrene polymer can be obtained. It is possible to produce a styrene polymer resin composition having practical strength close to (styrene-acrylonitrile copolymer).

[0008]

DETAILED DESCRIPTION OF THE INVENTION The styrene polymer of the present invention is a 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 small-particle inorganic filler is 0.001 to 0.1 μm, preferably 0.005 to 0.1 μm.
It is 05 microns. The average particle size of the small particle inorganic filler is
If it is less than 0.001 micron, the dispersibility is very poor and it cannot be uniformly dispersed in the resin. When the average particle size of the small-particle inorganic filler exceeds 0.1 μm, no significant improvement in practical strength is observed. The average particle size of the large particle inorganic filler is 1 to 10 microns, preferably 1 to 5 microns. If the average particle diameter of the large-particle inorganic filler component is less than 1 micron, no significant improvement in practical strength is observed. If the average particle size of the large-particle inorganic filler component exceeds 10 microns, the haze value of the styrene polymer molded article becomes undesirably large even if the amount of the large-particle inorganic filler is extremely small.
Considering the balance between practical strength and transparency, the average particle size of small-particle inorganic fillers is 0.001 to 0.1 micron,
It is preferably 0.005 to 0.05 micron, and the average particle size of the large-particle inorganic filler component is 1 to 10 micron, preferably 1 to 10 micron.
~ 5 microns.

In the present invention, the total amount of the inorganic filler is 0.001 to 3 parts by weight, preferably 0.001 to 1 part by weight, based on 100 parts by weight of the styrene polymer. 0.0
If the amount is less than 01 parts 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. Considering the balance between practical strength and transparency, the amount of the inorganic filler to be added is 0.001 to 3 parts by weight.

Further, in the present invention, the small-particle inorganic filler component (specific gravity: ρ ₁ , blending amount: W ₁ ) and the large-particle inorganic filler component (specific gravity: ρ ₂ , blending amount: W ₂ ) It is necessary to have the relationship Even if the value of 2.0 ≦ (W ₁ / ρ ₁ ) / (W ₂ / ρ ₂ ) ≦ 1000 (W ₁ / ρ ₁ ) / (W ₂ / ρ ₂ ) exceeds 1000 or is less than 2.0 The effect of improving the practical strength is not recognized as compared with the case where the small particle inorganic filler component or the large particle inorganic filler component is added alone.

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 particle size, the type of the inorganic filler, and the like. It is preferable that the amount of addition of the inorganic filler and the particle size distribution are within the above ranges and the haze value is 5 or less. The optimum addition amount is influenced by the addition amount of the inorganic filler, the particle size, and the type of the inorganic filler.

Further, in order to disperse the inorganic filler well and to obtain good releasability between the mold and the resin during molding, it 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). Phenyl salicylate compound; a hindered amine-based stabilizer); and a plasticizer such as liquid paraffin, an antistatic agent, and an additive such as a coloring agent. 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.

[0018]

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 4 and Comparative Examples 1 to 6 The components were blended according to the formulation shown in Table 1, melt-kneaded at 220 ° C. with a twin-screw extruder, and the mixture was subjected 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), placed on a table with a concave portion formed thereon, dropped a 50 g steel ball toward the concave portion, and visually observed whether or not the molded product was broken. 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".

[0021]

[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) BF-20; barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.),
Average particle diameter 0.03 μm, specific gravity 4.0 BMH; barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.),
Average particle size 2.5 μm, specific gravity 4.0.

Example 5 A styrene resin and an inorganic filler were melt-kneaded with a twin screw extruder at 220 ° C. 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 (5)

[Claims] 1. A resin composition containing a styrene polymer, an inorganic filler and a specific lubricant, wherein: 1) a blending amount of the inorganic filler of 0.001 to 3 parts by weight with respect to 100 parts by weight of the styrene polymer; 2) the inorganic filler is a small particle inorganic filler component (average particle size:
R ₁ micron, specific gravity: ρ ₁ , compounding amount: W ₁ ) and large-particle inorganic filler component (average particle size: R ₂ microns, specific gravity:
ρ ₂ , compounding amount: W ₂ ), and the small particle inorganic filler component and the large particle inorganic filler component have the following relationship: a) 2.0 ≦ (W ₁ / ρ ₁ ) / (W ₂ / ρ ₂ ) 1000 b) 0.001 ≤ R ₁ ≤ 0.1 c) 1 ≤ R ₂ ≤ 10 3) The specific lubricant is at least one selected from the group consisting of higher fatty acids, higher fatty acid salts and higher fatty acid amides. Yes, the amount is based on 100 parts by weight of styrene polymer
A styrene polymer composition, wherein the amount is 0.001 to 3 parts by weight. 2. The styrene polymer composition according to claim 1, wherein the inorganic filler is barium sulfate and / or calcium carbonate. 3. Haze value (AST) on a 3 mm thick plate
The styrene polymer composition according to claim 1 or 2, wherein MD1003) is 5.0 or less. 4. A styrene polymer pellet obtained by melting and kneading 0.001 to 3 parts by weight of an inorganic filler satisfying the following conditions with respect to 100 parts by weight of a styrene polymer:
A styrene polymer composition in which 0.001 to 3 parts by weight of at least one lubricant selected from the group consisting of higher fatty acid salts and higher fatty acid amides is uniformly adhered. Conditions of the inorganic filler: small particle inorganic filler component (mean particle size: R ₁ micron, density: [rho _1, amount: W ₁₎ and the large particle inorganic filler component (mean particle size: R ₂ microns, a specific gravity:
ρ ₂ , compounding amount: W ₂ ), and the small-particle inorganic filler component and the large-particle inorganic filler component have the following relationship: a) 2.0 ≦ (W ₁ / ρ ₁ ) / (W ₂ ) / Ρ ₂ ) ≦ 1000 b) 0.001 ≦ R ₁ ≦ 0.1 c) 1 ≦ R ₂ ≦ 10 5. A styrene polymer pellet melt-kneaded with 0.001 to 3 parts by weight of an inorganic filler satisfying the following conditions with respect to 100 parts by weight of a styrene polymer:
A styrene polymer composition characterized in that at least one lubricant selected from the group consisting of higher fatty acid salts and higher fatty acid amides is directly applied to a molded article as it is in a state where 0.001 to 3 parts by weight are uniformly adhered. Molding method. Conditions of the inorganic filler: small particle inorganic filler component (mean particle size: R ₁ micron, density: [rho _1, amount: W ₁₎ and the large particle inorganic filler component (mean particle size: R ₂ microns, a specific gravity:
ρ ₂ , compounding amount: W ₂ ), and the small-particle inorganic filler component and the large-particle inorganic filler component have the following relationship: a) 2.0 ≦ (W ₁ / ρ ₁ ) / (W ₂ ) / Ρ ₂ ) ≦ 1000 b) 0.001 ≦ R ₁ ≦ 0.1 c) 1 ≦ R ₂ ≦ 10