JPH05156102A - Colored styrene resin composition - Google Patents

Abstract

(57) [Abstract] [Purpose] To solve the appearance defect (black stripe) that appears on the molded product when the styrene resin containing titanium oxide is injection-molded, such as black ink. [Structure] Styrene resin containing titanium oxide, maleic anhydride monomer 0.
05-8.0 parts by weight, or at least 5 parts maleic anhydride.
0.05 to 50 parts by weight of maleic anhydride-styrene copolymer containing 0% by weight or more is added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having an excellent appearance which is useful as a material used in various electric products, housings of office equipment and miscellaneous goods.

[0002]

2. Description of the Related Art Styrenic resins have been conventionally used for molding processability,
Due to its excellent balance of dimensional stability and mechanical strength,
It is used as a molding material for various products. In particular, it is widely used for various electrical products, office equipment housings, and external parts such as sundries. And it is colored and used for design. Titanium oxide is often used for coloring styrenic resins used for these purposes, and in general, in order to uniformly disperse titanium oxide and titanium oxide in the resin, dispersion of fatty acid metal salts etc. It is carried out by kneading into the resin together with the agent. However, when a colored styrene-based resin is injection-molded using titanium oxide, a black streak pattern may occur on a molded product, although a black-based coloring agent is not used. This black striped pattern is called a black strip.

Since the occurrence of the above-mentioned black stripes greatly lowers the commercial value, it has been conventionally studied. For example, 9,
10-dihydro-9-oxa-10-phosphananthrene-10-oxide, distearyl pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylene diphosphite, or , Adding boron trioxide to styrene resin,
The method described in JP-A-63-86743 for preventing the occurrence of black stripes, and the method described in JP-A-2-88659 for preventing the occurrence of black stripes by using alkylene-bis-fatty acid amide or fatty acid zinc as a color dispersant Is known. However, none of them was sufficient to completely prevent the occurrence of black stripes.

[0004]

DISCLOSURE OF THE INVENTION The present invention is directed to a black streak pattern (black stripe) generated on a molded product when injection molding is performed using a styrene resin composition colored with a coloring agent containing titanium oxide. ) Is intended to solve the defective phenomenon.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that the object can be achieved by adding a specific compound, and have reached the present invention.

That is, according to the present invention, in a styrene resin containing titanium oxide, 0.05 to 8.0 parts by weight of a maleic anhydride monomer or at least 5.0% by weight of maleic anhydride is used with respect to 100 parts by weight of a styrene resin. A colored styrene resin composition, characterized by containing 0.05 to 50 parts by weight of a maleic anhydride-styrene copolymer contained therein.

The present invention will be described in detail below.

The styrene resin used in the present invention is, for example, a homopolymer of a styrene monomer (GPPS resin), a copolymer of a styrene monomer and another copolymerizable monomer, such as styrene-acrylonitrile. Copolymer resin (AS resin) or a polymer obtained by grafting these to a rubber component, for example, high impact polystyrene resin (HIPS resin),
Examples thereof include acrylonitrile-styrene-butadiene copolymer resin (ABS resin). In addition, some or all of the styrene of these polymers is α-methylstyrene, p
It may be replaced with a vinyl aromatic compound such as -methylstyrene, vinyltoluene or p-tert-butylstyrene. Further, part or all of acrylonitrile may be replaced with vinyl cyanide compound such as methacrylonitrile. However, it is preferably an acrylonitrile-styrene-butadiene copolymer resin (ABS resin).

The titanium oxide used in the present invention is not particularly limited as long as it is generally used, and the average particle diameter is 0.
Particles of any size from 01 to 0.5 μm can be used. The crystal structure may be rutile type or anatase type. Further, the surface may not be treated, but one which is previously treated with aluminum oxide or the like is preferably used. The amount of titanium oxide added is usually 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the resin. If it is less than 0.1 parts by weight, the coloring property is insufficient, and if it is more than 5.0 parts by weight, the strength of the resin is lowered, which is not preferable. .

The content of the maleic anhydride monomer is 0.05 to 8.0 parts by weight, preferably 0.1 to 3.0 parts by weight, based on 100 parts by weight of the styrene resin composition. If the amount of maleic anhydride monomer is less than 0.05 parts by weight, black stripes are likely to occur on the surface of the injection-molded product, and if it is more than 8.0 parts by weight, maleic anhydride monomers are polymerized with each other during the molding process, resulting in a 2-3 mer. It is not preferable because it produces a large amount of low molecular weight compounds mainly containing ethylene, and significantly reduces the physical properties of the styrene resin, particularly the heat resistance.

The maleic anhydride-styrene copolymer is a copolymer of a maleic anhydride monomer and a styrene-based monomer, and the styrene-based monomer is the styrene-based monomer used in the styrene-based resin. Although it is composed of a body, styrene and α-methylstyrene are particularly preferable, and at least one of such styrene-based monomers is used. If desired, an acrylonitrile-based monomer, a maleimide-based monomer, an acrylic acid ester-based monomer or the like can be used in combination with the styrene-based monomer.

The ratio of maleic anhydride contained in the maleic anhydride-styrene copolymer (the ratio of maleic anhydride contained in the copolymer segment) is at least 5.
It should be 0% by weight or more, preferably 10.0
It is more than weight%. The ratio of maleic anhydride is 5.0% by weight
If the amount is smaller, black streaks are likely to occur in the injection molded product, which is not preferable.

The maleic anhydride-styrene copolymer may be modified with a rubbery polymer such as butadiene or styrene-butadiene block copolymer.

The content of the maleic anhydride-styrene copolymer is 0.05 to 50 parts by weight, particularly preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the styrene resin. If the content is less than 0.05 parts by weight, black streaks are likely to occur on the surface of the injection-molded product, and if it exceeds 50 parts by weight, the physical properties of the styrene resin, particularly impact resistance, are deteriorated, which is not preferable.

Even if an unsaturated dicarboxylic acid monomer such as maleic acid, fumaric acid, citraconic acid, metaconic acid, glutaconic acid, methylenesuccinic acid or allylmalonic acid is used in place of the maleic anhydride monomer, the desired result is obtained. No improvement effect can be obtained. On the other hand, although an improving effect is observed in unsaturated dicarboxylic acid anhydrides such as citraconic anhydride obtained by modifying maleic anhydride, the effect is inferior to that of maleic anhydride.

The maleic anhydride monomer and the maleic anhydride-styrene copolymer may be used in combination.

The maleic anhydride-styrene copolymer used in the present invention can be obtained by a known method such as a bulk polymerization method, a suspension polymerization method or an emulsion polymerization method.

The method for producing the resin composition of the present invention is not particularly limited, and for example, titanium oxide, maleic anhydride monomer or maleic anhydride-styrene copolymer and styrene resin are preliminarily used in a Henschel mixer, tumbler or the like. Mixing, a method of pelletizing the mixture using an extruder, a kneader, or the like, maleic anhydride at the time of polymerization of the styrene resin-styrene copolymer is mixed, pellets of the resulting resin composition and titanium oxide. The method of mixing and pelletizing by the above method is performed.

In the present invention, if necessary, additives other than titanium oxide, for example, colorants, antistatic agents, antioxidants, plasticizers, ultraviolet absorbers and the like can be added.

[0020]

The present invention will be described in more detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to these examples.

Examples 1 to 10 Premixing was carried out according to the formulation shown in Table 1, and pelletization was performed using an extruder at a cylinder temperature of 220 ° C. Using the IS-80EPN injection molding machine manufactured by Toshiba Kikai Co., Ltd., the pellets thus obtained were subjected to 100 × 50 × 150 mm flat plate at a cylinder temperature of 240 ° C., a screw back pressure of 20 kg / cm ² , a screw rotation speed of 100 rpm, and a mold temperature of 50 ° C. One sheet was molded and the number of black stripes was examined. The results are shown in Table 1. No black stripes occurred in either case.

[0022]

[Table 1]

Comparative Examples 1 to 9 The number of black stripes was examined in the same manner as in Examples except for the composition shown in Table 2. The results are shown in Table 2. Outside the scope of the present invention, a large number of black stripes were generated.

[0024]

[Table 2]

[0025]

INDUSTRIAL APPLICABILITY A molded article produced by injection molding using the resin composition of the present invention has no black stripes and is extremely useful in industry.

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Claims (2)

[Claims] 1. A styrene-based resin containing titanium oxide, which contains 0.05 to 8.0 parts by weight of a maleic anhydride monomer or at least 5.0% by weight of maleic anhydride per 100 parts by weight of a styrene-based resin. A colored styrenic resin composition comprising 0.05 to 50 parts by weight of a maleic acid-styrene copolymer. 2. The colored styrene resin composition according to claim 1, wherein the styrene resin is an acrylonitrile-styrene-butadiene copolymer.