JPH0567660B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to various types of light electrical equipment housings, rotating bodies,
The present invention relates to a sliding article made of an impact-resistant rubber-modified styrenic resin composition that has excellent surface smoothness and sliding properties suitable for gears and bearings. More specifically, the present invention relates to a slidable article made of a rubber-modified styrenic resin composition that does not produce black streaks during molding and has excellent thermal stability. [Conventional technology and its issues] Styrenic resins have been used in a wide variety of fields due to their excellent moldability, but in particular, so-called high impact polystyrene (HIPS) modified with rubbery polymers. Rubber-modified styrenic resins such as ABS resins and ABS resins have good moldability and
Because it has excellent impact resistance, it is used in a wide range of fields such as daily necessities, toys, and housings for light electrical equipment. Furthermore, in recent years, it has become possible to obtain impact-resistant resin compositions with excellent surface smoothness and abrasion resistance by incorporating organopolysiloxane into such rubber-modified styrenic resins. For example, in JP-A No. 60-217254, polyorganosiloxane with a specific viscosity is added to a rubber-modified styrene resin with a specific structure as a silicon content of 0.25 to 1.25.
A rubber-modified styrenic resin composition with excellent abrasion resistance and surface smoothness is disclosed. In addition to having excellent sliding properties, such resin compositions are inexpensive compared to engineering resins such as polyacetal.
It has come to be used for applications such as VTR cassette reels, personal computers, pushbutton key tops, and CRT turntables. However, although such resin compositions found in the prior art have excellent sliding properties and abrasion resistance, they have the drawback of easily generating black streaks during molding. The occurrence of black streaks depends on the type of molding machine used, but generally it is more likely to occur when a molding machine with strong shearing force is used. The reason why black streaks tend to occur during molding of rubber-modified styrenic resins containing such organopolysiloxanes is not clear. Since black streaks on a slidable article impair its commercial value, there has been a strong desire for a slidable article without black streaks. [Means for Solving the Problems] Therefore, as a result of intensive studies to solve the problems, the present inventors found that during the molding process of a composition comprising a rubber-modified styrenic resin and a specific amount of organopolysiloxane, The inventors have discovered that a phenolic antioxidant with a specific chemical structure is highly effective in suppressing black streaks, leading to the completion of the present invention. That is, the present invention provides a rubber-modified styrenic resin.
100 parts by weight of (a), 0.5 to 1.5 parts by weight of organopolysiloxane (b) as silicon content, and triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate. ],
4,4'-Butylidene-bis-(3-methyl-6-
t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,1-bis(2-methyl-
4-Hydroxy-5-t-butylphenyl)butane, 3,9-bis[2-[3-(3-t-butyl-
4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,
From a rubber-modified styrenic resin composition containing 0.05 to 1.0 parts by weight of at least one or two or more phenolic antioxidants (c) selected from 8,10-tetraoxaspiro[5,5]undecane The object of the present invention is to provide a slidable article. The rubber-modified styrenic resin referred to in (a) here is:
It is obtained by graft polymerizing a vinyl monomer whose main component is a styrene monomer onto a rubbery polymer. As the styrene monomer, styrene is preferred, but α-methylstyrene and P-methylstyrene can also be used. Acrylonitrile, with an upper limit of about 40% by weight, preferably about 30% by weight, of these styrenic monomers;
Nitrile monomers such as methacrylonitrile: Can be replaced with vinyl monomers such as methyl methacrylate and used in combination. Rubbery polymers include butadiene polymer (PBR), styrene-butadiene copolymer (SBR), acrylonitrile-butadiene copolymer (NBR), as well as ethylene-propylene-diene terpolymer (EPDM), An acrylic ester polymer (acrylic rubber) or the like can be used. The method for grafting the above-mentioned monomers onto these rubbery polymers may be any of the conventional bulk, bulk/suspension, and emulsion polymerization methods. The content of the rubbery polymer in the rubber-modified styrenic polymer obtained according to the above method can be adjusted depending on the use of the molded article, and is usually 3 to 20% by weight. If the content of the rubbery polymer is less than 3% by weight, the impact strength will not be sufficient, while if it exceeds 20% by weight, the rigidity will decrease, which is not preferable. Next, examples of the organopolysiloxane (b) include polymers such as polydimethylsiloxane, polymethylphenylsiloxane, and polymethylphenyldimethylsiloxane. Most preferred are siloxanes. The viscosity of the organopolysiloxane is:
Preferably, the kinematic viscosity at 25° C. is 5,000 to 50,000 centistokes. If the kinematic viscosity is less than 5,000 centistokes, the effect of imparting sliding properties will be small; on the other hand, if the kinematic viscosity exceeds 50,000 centistokes,
Dispersion into the rubber-modified styrenic resin (a) becomes difficult. The amount of the organopolysiloxane used is 100% of the rubber-modified styrene resin in (a) above.
The silicon content is 0.5 to 1.5 parts by weight, preferably 0.75 to 1.0 parts by weight. usage is 0.5
If it is less than 1.5 parts by weight, the effect of imparting sliding properties will not be sufficient, and if it exceeds 1.5 parts by weight,
The effect of imparting sliding properties reaches saturation, which is not only uneconomical, but also causes black streaks to easily occur during molding, which is undesirable. Next, the styrenic resin composition used for the injection molded article of the present invention needs to contain the above-mentioned phenolic antioxidant. The phenolic antioxidant (c) above is

〔Effect of the invention〕

The slidable article made of the improved rubber-modified styrenic resin composition of the present invention does not have the black streaks during molding that were found in the molded products of the slidable rubber-modified styrenic resin composition according to the prior art. Therefore, the yield rate of molded products is good, and its industrial value is great. [Example] The content of the present invention will be specifically explained below using Examples and Comparative Examples, but these do not limit the scope of the present invention. Evaluation of black streak suppression effect: The cylinder temperature of the injection molding machine was set to 240°C, and the resin composition pellets were left in the cylinder for 10 minutes while being supplied.
The test specimens (50 mm
x90mm x 2.5mm). Among the sampled test pieces, count the number of test pieces with black streaks. In addition, when molding the above test piece, please prepare it in advance.
After adding GP polystyrene, etc., and thoroughly cleaning the inside of the cylinder, molding is performed. [Reference example]: Production of rubber styrene resin. Polybutadiene is dissolved in a mixture of styrene monomer and ethylbenzene, and after radical graft polymerization with stirring, unreacted monomers and solvent are removed under reduced pressure to obtain rubber-modified polystyrene with a rubber content of 5% and a rubber particle size of 10 μm. . Example 1 100 parts by weight of rubber-modified polystyrene obtained in Reference Example, polydimethylsiloxane (Toray Silicone)
Co., Ltd., SH-200 oil, 12500 centistokes)
1.0 parts by weight calculated as silicon content and triethylene glycol-bis[3-
0.3 parts by weight of (3-t-butyl-5-methyl-4-hydroxyphenyl)propionate was granulated using a 30 mm twin-screw extruder. Test pieces are prepared from the resulting resin pellets according to the method described above, and the number of test pieces having black streaks is counted. The results are shown in Table 1. Example 2 In Example 1, 4,4'-butylidene-bis(3-methyl-
The test is conducted in the same manner except that 6-t-butyl-phenol) is used. The results are shown in Table 1. Example 3 A test is conducted in the same manner as in Example 1, except that 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane is used as the phenolic antioxidant. The result is the first
Shown in the table. Example 4 A test is conducted in the same manner as in Example 1, except that 1,1-bis(2-methyl-4-hydroxy-5-t-butyl-phenyl)butane is used as the phenolic antioxidant. The results are shown in Table 1. Comparative Example 1 In Example 1, 2,6-
The test is carried out in the same manner, except that di-t-butyl-4-methyl-phenol is used. The result is the first
Shown in the table. Comparative Example 2 In Example 1, n-octadecyl-3-(3',5'-di-t-
The test is carried out in the same manner, except that butyl-4'-hydroxyphenyl) propionate is used. The results are shown in Table 1. Comparative Example 3 In Example 1, 1,6-hexanediol-bis[3-(3,
5-di-t-butyl-4-hydroxyphenyl)
The test is conducted in the same manner, except that propionate] is used. The results are shown in Table 1. Comparative Example 4 In Example 1, 2,4-bis-(n-octylthio)6-(4
The test is conducted in the same manner, except that -hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine is used. The results are shown in Table 1. Comparative Example 5 In Example 1, pentaerythrityl-tetrakis [3-(3,
5-di-t-butyl-4-hydroxyphenyl)
The test is conducted in the same manner, except that propionate] is used. The results are shown in Table 1. Comparative Example 6 In Example 1, 2,2'-methylene-bis(4-methyl-6-
The test is conducted in the same manner except that t-butylphenol) is used. The results are shown in Table 1. Example 5 A test is conducted in the same manner as in Example 1, except that the amount of the phenolic antioxidant added is 0.1 part by weight. The results are shown in Table 1. Example 6 A test is conducted in the same manner as in Example 2, except that the amount of phenolic antioxidant added is 0.1 part by weight. The results are shown in Table 1. Example 7 A test is conducted in the same manner as in Example 3, except that the amount of phenolic antioxidant added is 0.1 part by weight. The results are shown in Table 1. Example 8 A test is conducted in the same manner as in Example 4, except that the amount of phenolic antioxidant added is 0.1 part by weight. The results are shown in Table 1. The phenolic antioxidants with specific structures listed in Table 1 below are listed below for reference; [] Triethylene glycol-bis[3-
(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate]

[Chemical] [] 4,4'-Butylidene-bis-(3-methyl-6-t-butylphenol)

[Formula] [] 1,1,3-tris(2-methyl-4-
Hydroxy-5-t-butylphenyl)butane

[Formula] [] 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane

[Formula] [] 2,6-di-t-butyl-4-methylphenol

[Formula] [] Octadecyl-3-(3,5-di-t-
Butyl-4-hydroxyphenyl)propionate

[Formula] [] 1,6-hexanediol-bis[3-
(3,5-di-t-butyl-4-hydroxyphenyl)propionate]

[C] [] Pentaerythrityl-tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)propionate]

[Formula] [] 2,4-bis(n-octylthio)-6
-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-todoroxy-3,5
-di-t-butylanilino-1,3,5-triazine

[Formula] [] 2,2'-methylene-bis-(4-methyl-6-t-butylphenol)

【formula】

[Table] As is clear from Table 1, only in the case of slidable articles made of rubber-modified styrene resin, organopolysiloxane, and rubber-modified polystyrene containing a phenolic antioxidant with a specific structure, black streaks appear. There is no.

Claims (1)

[Scope of Claims] 1. 100 parts by weight of rubber-modified styrenic resin (a), 0.5 to 1.5 parts by weight of organopolysiloxane (b) as silicon content, and triethylene glycol bis[3-
(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 4,4'-butylidene-bis-(3-methyl-6-t-butylphenol), 1,1,3-tris( 2-methyl-4-
hydroxy-5-t-butylphenyl)butane,
1,1-bis(2-methyl-4-hydroxy-5
-t-butylphenyl)butane, 3,9-bis[2-[3-(3-t-butyl-4-hydroxy-
5-methylphenyl)propionyloxy]-1,
0.05 to 1.0 parts by weight of at least one or two or more phenolic antioxidants (c) selected from 1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane A slidable article comprising a rubber-modified styrenic resin composition.