JP2555081B2 - Styrene resin composition with excellent fluidity and coating adhesion - Google Patents

Description

TECHNICAL FIELD The present invention relates to a styrene resin composition having excellent fluidity and coating adhesion after molding.

[Conventional technology]

Styrene-based resins are generally used for many molded products because they are inexpensive and have good dimensional stability, but the drawback is one large molded product, such as how to use electronic musical instruments, how to use televisions, how to use large computer, etc. In the case of molding, the resin is not filled up to the end of the mold due to the lack of fluidity of the resin, which causes a so-called short shot. In addition, if the fluidity is poor even if it can be filled, the pressure is not sufficiently applied to the end, and after the molded product is taken out of the mold, a defective appearance such as a warp or a sink mark often occurs.

In order to solve this problem, it is usually attempted to reduce the molecular weight of the resin or to add liquid paraffin, ethylene bisstearamide, higher fatty acid or the like as a flow improver. Of these, the former improvement in fluidity due to a decrease in molecular weight is not usually used because it greatly reduces the impact strength of the resin, and the latter additive is generally used for improvement.

It is known that these fluidity improvements have a plastic function between resins in a molten state at the time of molding and cause bleeding on the surface of the resin.

Therefore, when coating a molded product, there is a problem that the coating liquid is repelled or the coating film is easily peeled off due to the influence of the fluidity improver that bleeds on the surface. It is being wiped off or washed with a fluorine-based solvent.

[Problems to be solved by the invention]

Therefore, an object of the present invention is to provide a styrene-based resin composition that does not require pretreatment for coating, specifically, a styrene-based resin composition having excellent fluidity and coating adhesion.

[Means for solving problems]

The present inventors have made sufficient improvements in fluidity, do not require pretreatment for coating, are excellent in coating adhesion, and have eagerly searched for an inexpensive additive component, and have found an additive satisfying this object. Finally, the present invention has been reached.

That is, the present invention, with respect to 100 parts by weight of styrene-based resin, ethylene bis stearamide is 2.5 parts by weight or less,
Further, the present invention is a styrene-based resin composition having excellent fluidity and coating adhesion, which contains 0.5-10 parts by weight of castor hardened oil and ethylene bis-stearamide in total.

The styrene-based resin used in the present invention includes impact-resistant polystyrene (HIPS) obtained by graft-polymerizing styrene onto a rubber-like elastomer, a copolymer of acrylonitrile and styrene (AS resin), and AS resin reinforced with a rubber-like elastomer (AB
S resin), copolymer of methyl methacrylate and styrene (MS resin), AS resin reinforced with rubber elastomer (MB
S resin).

The hydrogenated castor oil used in the present invention is obtained by hydrogenating castor oil to raise its melting point to 84 ° C or higher.

In the present invention, hydrogenated castor oil is used in combination with ethylene bis-stearamide, and the effects of the present invention cannot be obtained by blending castor oil or ethylene bis-stearamide alone. That is, when the castor hardened oil is blended alone, the fluidity and the coating adhesion are improved, but the heat resistance is significantly reduced.
Also, when ethylene bis stearamide is blended alone, there is little decrease in heat resistance and the effect of improving fluidity is great, but the compatibility with paint solvents is poor, especially 2.5 parts by weight or more (based on 100 parts by weight of styrene resin). The blending property markedly reduces the coatability. Therefore, it is essential that the blending amount of ethylenebisstearoamide is 2.5 parts by weight or less, preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the styrene resin.

In the present invention, the total amount of hydrogenated castor oil and ethylene bis-stearamide is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the styrene resin. If the total amount is less than 0.5 parts by weight, the effect of improving the fluidity is not sufficient, and if the amount is more than 10 parts by weight, there is a problem that the volatile content at the time of molding increases, and bleeding on the surface of the molded product occurs. As is the case with the conventional method, alcohol wiping or fluorine solvent cleaning is required before painting.

The styrene-based resin composition of the present invention is a styrene-based resin, castor hydrogenated oil and ethylene bis-stearamide are mixed with a Henschel mixer, a kneading roll, a Banbury mixer, and the like. It can be produced by adding these components to a polymerization system for producing a resin.

The composition of the present invention may further contain various additives such as an antioxidant, a colorant and a surfactant.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

Examples 1 and 2 ABS resin obtained by polymerizing a mixture of 75 parts by weight of styrene and 25 parts by weight of acrylonitrile in the presence of 10 parts by weight of rubber-like elastomer (manufactured by Mitsui Toatsu Chemicals, Inc .: trade name Santak GT-10). ) 100 parts by weight of hydrogenated castor oil and ethylene bisstearamide were mixed in the amounts shown in Table 1 and pelletized by an extruder.

Determine the fluidity (melt flow value) of the obtained resin composition by JI
It was measured according to SK-6871.

Paint adhesion is 50 x 50 x 2.5 mm flat plate molded product by injection molding, and urethane paint (Nagashima Paint Co., Ltd .: trade name X-361) and acrylic paint (Toho Kaika) Kenken Co., Ltd .: trade name Polytac) was applied and measured by a cross-cut test according to JIS K-5400.

The heat resistance was measured by the Vicat softening point according to JIS K-6870.

 The obtained results are shown in Table-1.

Comparative Examples 1 to 5 The same as Examples 1 to 2 except that the amounts of hydrogenated castor oil and ethylene bisstearamide were changed to the amounts shown in Table 1. The results are shown in Table 1.

Examples 3 to 4 Rubber-like elastomer 7.5% by weight and styrene 92.5% by weight
HIPS obtained by graft polymerization of (manufactured by Mitsui Toatsu Chemicals, Inc .:
Trade name Topolex 860-03) 100 parts by weight of castor hydrogenated oil and ethylene bis stearamide shown in Table 1 were blended in the same manner as in other Examples 1 and 2. The results are shown in Table-1
Shown in

Comparative Examples 6 to 7 Comparative Examples 6 to 7 were performed in the same manner as in Examples 3 to 4, except that the compounds shown in Table 1 were used in the amounts shown in Table 1 in place of hydrogenated castor oil and ethylenebisstearoamide. The results are shown in Table 1.

EFFECTS OF THE INVENTION Castor effect oil alone improves fluidity, but coating adhesion is insufficient (Comparative Example 1), and ethylenebisstearoamide alone improves fluidity while maintaining heat resistance. However, the coating adhesion is significantly reduced (Comparative Example 2). Further, if the total amount used is too small, the fluidity is insufficient (Comparative Example 3), and if the total amount is too large, the fluidity is improved but the coating adhesion and heat resistance are reduced (Comparative Example 4).
Further, even if the total amount used is within the range of the present invention, if the blending amount of ethylenebisstearoamide is too large, the coating adhesion will be reduced (Comparative Example 5).

It should be noted that the blending of the higher fatty acid alone improves the fluidity, but the heat resistance and the coating adhesion are lowered (Comparative Example 6), and the blending of the metal soap alone improves the fluidity and has sufficient heat resistance. However, the coating adhesion decreases (Comparative Example 7).

The composition of the present invention, as seen in the examples, has a fluidity,
Both coating adhesion and heat resistance are excellent in a well-balanced manner, and large moldings, such as TV housings,
The housing of an electronic musical instrument, the housing of an air conditioner, etc. can be easily molded and can be painted without pretreatment, which is an extremely excellent property, which greatly contributes to the industry.

Claims (1)

(57) [Claims] 1. A styrene resin containing 0.05 to 2.5 parts by weight of ethylene bis-stearamide and 0.45 to 9.95 parts by weight of castor-hardened oil, and hydrogenated castor oil and ethylene bis-stearamide in total. A styrene-based resin composition excellent in fluidity and coating adhesion, characterized by containing 0.5 to 10 parts by weight.