JPH02145637A - Rubber-modified styrenic resin composition having improved slidability - Google Patents

Abstract

PURPOSE:To provide a resin composition having excellent thermal stability and slidability and free of the generation of black streaks when molded by comprising a rubber-modified styrenic resin, an organopolysiloxane and a phenolic antioxidant having a specific chemical structure. CONSTITUTION:A composition comprises (A) 100 pts.wt. of a rubber-modified styrenic resin containing 3-20wt.% of a rubbery polymer, (B) an organopolysiloxane, preferably polydimethylsiloxane, having a kinematic viscosity of preferably 5000-50000 centistokes at 25 deg.C in an amount of 0.5-1.5 pts.wt., preferably 0.75-1 pt.wt., as a silicon content and (C) 0.01-2 pts.wt., preferably 0.1-1 pt.wt., of a phenolic antioxidant, preferably triethylene glycol bis[3-(3-t- butyl-5-methyl-4-hydroxyphenyl)propionate] having one or more groups of the formula (R1-R3 are H or methyl).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides impact-resistant T8 properties with excellent surface smoothness and sliding properties suitable for molding various types of light electrical equipment housings, rotating bodies, gears, bearings, etc. The present invention relates to a rubber-modified styrenic resin composition.

More specifically, the present invention relates to a slidable rubber-modified styrenic resin composition that does not produce horse marks 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, and among them, rubber-modified styrenes such as so-called high impact polystyrene (HIPS) and ABS resins are modified with rubbery polymers. In addition to moldability, the resin has excellent impact resistance, so
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, Japanese Patent Application Laid-Open No. 60-217254 discloses a wear-resistant material in which a rubber-modified styrene resin with a specific structure contains polyorganosiloxane of a specific viscosity from 0.25 to 1.25 parts by weight as silicon content. Additionally, a rubber-modified styrenic resin composition with excellent surface smoothness is disclosed. In addition to having good sliding properties, such resin compositions also have
Since it is cheaper than engineering resins such as polyacetal, it has come to be used for applications such as VTR cassette reels, personal computers, Punshuong keypads, and CRT turntables.

However, although such resin compositions found in the prior art have excellent sliding properties and abrasion resistance, they have the disadvantage of easily generating black streaks during molding. ing. 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 molded product reduce its commercial value, there has been a strong desire for a slidable styrene resin that does not generate black streaks.

[Means to solve the problem]

Therefore, as a result of intensive studies to solve this problem, the present inventors have identified a method for suppressing black streaks that occur during molding of a composition consisting of a rubber-modified styrene resin and a specific amount of organopolysiloxane. The inventors discovered that a phenolic antioxidant with a chemical structure exhibits anti-oxidant properties, leading to the completion of the present invention.

That is, the present invention provides rubber-modified styrenic resin (a) 1
00 parts by weight, organopolysiloxane (b) as a silicon content of 0.5 to 1.5 parts by weight, and in the molecule (however, R3
, R2, R3: H or a methyl group. ) A phenolic antioxidant having at least one atomic group represented by (
To provide a slidable rubber-modified styrenic resin composition which is blended with c) in an amount of 0.05 to 1.0 parts by weight and has excellent thermal stability and does not generate black streaks during molding. .

The rubber-modified styrenic resin (a) referred to herein is one obtained by graft polymerizing a vinyl monomer whose main component is a styrene monomer onto a rubbery polymer.

Styrene is preferred as the styrenic monomer, but
In addition, α-methylstyrene and P-methylstyrene can also be used. Nitrile monomers such as acrylonitrile, methacrylaterile, and vinyl monomers such as methyl methacrylate can be used in combination to replace these styrene monomers by up to 40% by weight, preferably about 30% by weight. You can.

As the rubbery polymer, book diene polymer (PHR),
In addition to styrene-butadiene copolymer (SBR), acrylonitrile-cyclodiene copolymer (NRR), ethylene-propylene-diene terpolymer (EPDM),
Acrylic acid 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, and 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, but from the viewpoint of sliding properties, polydimethylsiloxane is most preferred.

The viscosity of the organopolysiloxane is 25°C.
Preferably, the kinematic viscosity is 5,000 to 50,000 centistokes. When the kinematic viscosity is less than s, ooo centistokes, the effect of imparting sliding properties is small, and on the other hand, when the kinematic viscosity exceeds so, ooo centistokes, dispersion in the rubber-modified styrenic resin described in (a) is difficult. Become. The amount of the organopolysiloxane used is 0.5 to 1.5 parts by weight as silicon content, preferably 0.75 to 1.0 parts by weight, based on 100 parts by weight of the rubber-modified styrene resin (a). Parts by weight.

If the amount used is less than 0.5 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 will reach saturation. This is not preferable because it is not only uneconomical but also tends to cause black streaks during molding.

Next, the phenolic antioxidant (c) has at least one atomic group having the structure described above (R1, R2, R3:H or methyl group). It is not clear why only phenolic antioxidants that meet this requirement are highly effective in suppressing the generation of black streaks during molding of resin compositions.

Examples of the phenolic antioxidant (c) include triethylene glycol-bis[3-(3-t-butyl 5-
Methyl-4-hydroxyphenyl)propionate L4
．． 4°-butylidene-bis-(3-methyl-6-t-butylphenol), LL, 3-tris(2-methyl4-hydroxy-5-t-butylphenyl)butane,
11-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] -
Examples include 2,4,8,10-tetraoxaspiro(5,5)undecane. Among these, triethylene glycol-bis(3-(3-t-butyl-5-
methyl-4-hydroxyphenyl)propionate] exhibits the most favorable effect.

The amount of the above phenolic antioxidant (c) used is 0 per 100 parts by weight of the rubber modified styrenic resin (a).
．． 01 to 2.0 parts by weight, preferably 0.1 to 1.0 parts by weight. If the amount used is less than 0.01 part by weight, the effect of suppressing the generation of black streaks during molding will be poor, and on the other hand, if the amount used exceeds 2.0 parts by weight, the black streaks will occur during molding. The effect of suppressing scar generation reaches saturation and is undesirable.

There are no particular restrictions on the method of blending the organopolysiloxane (b) and phenolic antioxidant (c) into the rubber-modified styrenic resin (a), and any method suitable for the polymerization method of the rubber-modified styrenic resin can be used. All you have to do is choose.

Specifically, a method of blending (b) and (c) into pellets of rubber-modified styrenic resin (a) using an extruder etc.
Polymerization in the bulk polymerization stage of bulk polymerization or bulk/suspension polymerization/
There is a method of adding components (b) and (c) to liquid 8.

Furthermore, additives such as dyes and pigments, lubricants, fillers, mold release agents, waxing agents, and antistatic agents may be added to the slidable rubber-modified styrenic resin composition of the present invention as necessary. can.

〔Effect of the invention〕

The slidable rubber-modified styrenic resin composition of the present invention does not generate black streaks during molding that was observed in the slidable rubber-modified styrenic resin compositions of the prior art, so the yield rate of molded products is improved. It also has great industrial utility value.

〔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.

Black 10 Good Tomo 11 Effects] 5λ Reviews'' Complaint: The cylinder temperature of the injection molding machine was set to 240°C, and the resin composition pellet was kept in the cylinder for 10 minutes, and then according to the normal molding cycle, Test piece (50++u++X
90mm x 2.5mm).

Among the sampled test pieces, count the number of test pieces with black streaks.

In addition, when molding the above-mentioned test piece, CP polystyrene or the like is charged in advance and the inside of the cylinder is thoroughly cleaned, and then molding is performed.

[Reference example]: Production of rubber styrene resin.

Polybutadiene was dissolved in a mixture of styrene monomer and ethylhenzene, and after radical graft polymerization with stirring,
By removing unreacted monomers and solvent under reduced pressure, rubber-modified polystyrene having a rubber content of 5% and a rubber particle size of 10 μm is obtained.

Example 1 100 parts by weight of rubber-modified polystyrene obtained in Reference Example,
Polydimethylsiloxane (manufactured by Toray Silicone, Sl+
-200 oil, 12,500 centistokes) in terms of silicon content and triethylene glycol-bis(3-(3-t-butyl-5-methyl-4-hydroxyphenyl) as a phenolic antioxidant. ) Propionate) 0.3 parts by weight is 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,
The test is carried out in the same manner except that 4'-butylidene-bis-(3-methyl-6-1-phthylphenol) is used. The results are shown in Table 1.

Example 3 In Example 1, 1,
1.3-Tris(2-methyl-4-hydroxy-5-
The test is carried out in the same manner except that t-butylphenyl)butane is used. The results are shown in Table 1.

Example 4 In Example 1, 1,
The test is carried out in the same manner, except that 1-bis(2-methyl-4-hydroxy-5-t-butyl-phenyl)butane is used. The results are shown in Table 1.

Comparative Example 1 In Example 1, 2,6-di-t-
The test is carried out in the same manner, except that butyl-4-methyl-phenol is used. The results are shown in Table 1.

Comparative Example 2 In Example 1, n-
octadecyl-3-(3',5'-di-butyl-4
Lh (Lh) using (hydroxyphenyl)propionate
shall be tested in the same manner. The results are shown in Table 1.

Comparative Example 3 In Example 1, 1.
The test is conducted in the same manner except that 6-hexanethiol bis[3-(3,5-di-L-butyl-4-hydroxyphenyl)propionate] is used. The results are shown in Table 1.

Comparative Example 4 In Example 1, 2,
4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-L-butylanilino)-1,3,5-
) The test is conducted in the same manner except that riazine is used. The results are shown in Table 1.

Comparative Example 5 The test is conducted in the same manner as in Example 1, except that pentaerythrityl-tetrakis (3-(3,5 di-t-butyl-4-hydroxyphenyl) propionate) is used as the phenolic antioxidant. .

The results are shown in Table 1.

Comparative Example 6 In Example 1, 2,
The test is carried out in the same manner except that 2'-methylene-bis(4-methyl-6-t-butylphenol) is used. The results are shown in Table 1.

Example 5 In Example 1, the amount of phenolic antioxidant added was 0.
．． The test is conducted in the same manner except that the amount is 1 part by weight. The results are shown in Table 1.

Example 6 In Example 2, the amount of phenolic antioxidant added was 0.
．． The test is conducted in the same manner except that the amount is 1 part by weight. The results are shown in Table 1.

Example 7 In Example 3, the amount of phenolic antioxidant added was 0.
．． The test is conducted in the same manner except that the amount is 1 part by weight. The results are shown in Table 1.

Example 8 In Example 4, the amount of phenolic antioxidant added was 0.
．． The test is conducted in the same manner except that the amount is 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 [IV] 1,1 bis(2 methyl-4 hydroxybutyl-5) Methylhydroxyphenyl) Butylphenyl) Butanelobionate] (II) 4.4' Butylidene-bis(3-methyl-6 methylphenol) (V)2.6 Dit-butyl-4 methylphenol H C5H7 CI) 1. 1.3 Tris(2 methyl-4 hydroxy[Vl] octadecyl-3 (35-di-t-butyl-4 hydroxyphenyl) propionate (cHo)3C (■) 1,6-hexanediol bis[3 citroxy-3,5- dibutylanilino)-1,35 dobutyl-4 hydroxyphenyl) propiofuriazine] (■) penquerythrityltetrakis[3 (X)2.2 methylenebismethyl-6-t bunbutyl-4 hydroxyphenyl) propityl phenol) onate] shi+13 shiJ-13 (IX) 2゜4-bis(n octylthio) hydroxy-3,5-di-L-butylanilino)-1,3
As is clear from Table 1, only when the rubber-modified styrenic resin and organopolysiloxane are blended with the phenolic antioxidant of the specific composition specified in the present invention, black color is removed during molding. A good molded product without any marks can be obtained.

(1 other person)

Claims (1)

[Scope of Claims] 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 at least atomic groups having the following structure in the molecule. 0.05 to 1 phenolic antioxidant (c)
A slidable rubber-modified styrenic resin composition with excellent thermal stability containing 1.0 parts by weight. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1, R_2, R_3: H or methyl group.)