JP2688619B2 - Rubber modified styrenic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a novel rubber-modified styrene resin composition. More specifically, the present invention is excellent in slidability, rigidity, impact resistance, and mold corrosion resistance, and is a rubber-modified styrene that is particularly suitable as a sliding material for reels for video tapes and OA equipment parts. The present invention relates to a resin composition.

[Prior art] Conventionally, in order to improve the impact resistance of a styrene resin,
By blending a rubber-like polymer with polystyrene, or by polymerizing styrene in the presence of the rubber-like polymer, styrene is partially graft-polymerized to the rubber-like polymer, and the balance of styrene becomes polystyrene. It is industrially widely used to prepare a so-called rubber-modified polystyrene resin composition in which a substantially rubber-like polymer / styrene graft copolymer and polystyrene are mixed.

On the other hand, styrene resin is used as a material for keyboards such as reels for video tapes, personal computers, and touch-tone phones. In this case, in addition to the above impact resistance,
Good slidability is also required. In order to impart this slidability to the styrene resin, it is known that it is effective to contain the polyorganosiloxane in the styrene resin. For example, a composition containing the polyorganosiloxane having self-lubricating property. (JP-B-52-43863 and JP-B-63-15287) and a styrene resin composition containing a polyorganosiloxane (JP-A-60-21).
No. 7254) is disclosed.

However, in these conventional polyorganosiloxane-containing styrene resin compositions, the slidability is not yet sufficient, they do not withstand long-term use, and they are subject to restrictions on their use, and they are molded. At this time, the influence of low molecular weight components contained in polyorganosiloxane causes problems such as corrosion of molds and molding machines, which is not economically disadvantageous, but in some cases, product contamination and deterioration of quality may occur. It has the drawback that it may lead to an undesirable situation.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of such conventional polyorganosiloxane-containing styrene resin compositions, is excellent in slidability, rigidity, and impact resistance, and is excellent in gold. The purpose of the present invention is to provide a rubber-modified styrene-based resin composition having mold corrosion resistance.

[Means for Solving the Problems] As a result of intensive studies to develop a rubber-modified styrenic resin composition having the above-mentioned excellent properties, the present inventors have found that
It has been found that the object can be achieved by mixing a specific rubber-modified styrene resin with a specific polyorganosiloxane at a predetermined ratio, and based on this finding, the present invention has been completed.

That is, the present invention relates to (A) 85 to 96% by weight of an aromatic vinyl monomer alone or a combination of an aromatic vinyl monomer and a vinyl monomer copolymerizable with the aromatic vinyl monomer, and a rubber dissolved therein. 100 parts by weight of a rubber-modified styrene-based resin obtained by polymerizing a mixture of 15 to 4% by weight of a polymer, (B) a temperature of 25 ° C.
A rubber-modified styrenic resin composition characterized in that the viscosity is 500 to 100,000 centistokes, and the content of the organosiloxane 20-mer or less is 0.5 to 5.0 parts by weight of a polyorganosiloxane having a content of 500 ppm by weight or less. It is provided.

 Hereinafter, the present invention will be described in detail.

In the composition of the present invention, the rubber-modified styrenic resin used as the component (A) is obtained by polymerizing an aromatic vinyl monomer in the presence of a dissolved rubber-like polymer or by combining the aromatic vinyl monomer with the aromatic vinyl monomer. It is obtained by copolymerizing with a copolymerizable vinyl monomer.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, α-ethylstyrene, α-
Α-Alkyl-substituted styrene such as methyl-p-methylstyrene, o-methylstyrene, m-methylstyrene, p
-Methylstyrene, 2,4-dimethylstyrene, ethylstyrene, o-t-butylstyrene, p-t-butylstyrene, and other alkyl-substituted styrenes, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, dichlorostyrene, dibromostyrene,
Trichlorostyrene, tribromostyrene, tetrachlorostyrene, tetrabromostyrene, 2-methyl-4-
Nuclear halogenated styrenes such as chlorostyrene and p-hydroxystyrene, o-methoxystyrene, vinylnaphthalene and the like can be mentioned. Of these, styrene and α-methylstyrene are particularly preferable. These aromatic vinyl monomers may be used alone,
Two or more kinds may be used in combination.

Further, if desired, as the copolymerizable vinyl-based monomer used together with the aromatic vinyl monomer,
For example, acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, vinyl cyanide such as α-chloroacrylonitrile, maleic anhydride, unsaturated dicarboxylic acid anhydrides such as itaconic anhydride and methyl methacrylate, methyl acrylate, methacrylic acid, Examples thereof include acrylic acid and phenylmaleimide. Among these, unsaturated dicarboxylic acid anhydride, particularly maleic anhydride is preferable. These copolymerizable vinyl monomers may be used alone or in combination of two or more.

Further, as the rubber-like polymer used for the rubber-modified styrene resin, for example, polybutadiene such as cis-type, trans-type, low vinyl-type obtained by emulsion polymerization or solution polymerization, or random obtained by emulsion polymerization or solution polymerization. Type, block type butadiene-styrene copolymer rubber, natural rubber, polyisobutylene rubber, styrene-isoprene copolymer rubber, butyl rubber, ethylene-propylene copolymer rubber, and graft copolymers of these rubbers with styrene. Although polymer rubber etc. are mentioned, polybudiene and butadiene-styrene copolymer rubber are preferable among these. These rubbery polymers may be used alone or in combination of two or more.

The rubber-modified styrenic resin as the component (A) in the composition of the present invention is 85 to 96% by weight of the aromatic vinyl monomer or a combination of the aromatic vinyl monomer and the copolymerizable vinyl monomer.
And a polymer containing 15 to 4% by weight of the rubbery polymer in a dissolved state are polymerized, and a graft polymer obtained by graft-polymerizing a part of monomers to the rubbery polymer is obtained. It is contained. The amount of the rubber-like polymer is 4% by weight.
If less than 15% by weight, sufficient impact resistance cannot be obtained, and if more than 15% by weight, rigidity decreases.

HI-PS, HI-SMA, styrene-butadiene-methylmethacrylate copolymer, ABS and the like are known as typical examples of such rubber-modified styrene-based resin. It is preferable to polymerize a mixture of 15% by weight and a vinyl-based monomer copolymerizable with 56-84% by weight of an aromatic vinyl monomer, particularly 1-40% by weight of an unsaturated dicarboxylic acid anhydride.

This polymerization method is not particularly limited, and a conventionally used method such as emulsion polymerization method, bulk polymerization method, solution polymerization method, suspension polymerization method, or bulk-suspension two-step polymerization method is used. Legal and the like can be used.

At this time, a polymerization initiator or a molecular weight modifier is used, if desired. Examples of the polymerization initiator include 1,1-bis (t
-Butyliperoxy) cyclohexane, 1,1-bis (t
-Butylperoxy-3,3,5-trimethylcyclohexane and other peroxyketals, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5
-Dialkyl peroxides such as di (t-butylperoxy) hexane, benzoyl peroxide, diaryl peroxides such as m-toluoyl peroxide,
Peroxydicarbonates such as dimyristyl peroxydicarbonate, peroxyesters such as t-butylperoxyisopropyl carbonate, ketone peroxides such as cyclohexanone peroxide, p
-Menta hydroperoxide and other organic peroxides such as hydroperoxides, azohisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, azobisisobutyric acid methyl ester, azobiscyanovaleric acid and other azo compounds Is mentioned.

Examples of the molecular weight regulator include mercaptans such as α-methylstyrene dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, 1-phenylbutene-2-fluorene, dipentene and chloroform,
Examples thereof include terpenes and halogen compounds.

In the rubber-modified styrenic resin thus obtained, the rubber-like component is finely dispersed uniformly, but the average particle size thereof is such that the glossiness, impact resistance and slidability of the resulting composition are In order to obtain good results, it is preferably in the range of 0.2 to 2.0 μm. The average particle size of the rubber-like component can be controlled by changing the rotation speed of the reaction tank.

In the composition of the present invention, the polyorganosiloxane used as the component (B) has the general formula (In the formula, R is an alkyl group, a haloalkyl group, an aryl group or a haloaryl group, and R ′ and R ″ are a phenyl group or an alkyl group having 1 to 6 carbon atoms, and they may be the same, Each may be different, n
Is a natural number such that this polyorganosiloxane is liquid at room temperature)
500-100,000 centistokes, preferably 800-30,00
It is in the range of 0 centistokes. If the viscosity is less than 500 centistokes, the object of the present invention cannot be sufficiently achieved, and if it exceeds 100,000, it becomes extremely difficult to uniformly disperse it in the composition.

Typical examples of such polyorganosiloxanes include homopolymers and copolymers of polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, polytrichloropropylmethylsiloxane, polytrichlorophenylmethylsiloxane, polymethylphenyldimethylsiloxane, and the like. Coalesced and listed. These polyorganosiloxanes may be used alone or in combination of two or more.

In the polyorganosiloxane of the component (B), it is necessary that the content of the organosiloxane 20-mer or less is 500 ppm by weight or less, preferably 400 ppm by weight or less. If the content of this component exceeds 500 ppm by weight, the bleeding of the component causes remarkable deterioration of the sliding property with time and causes corrosion of a mold, a molding machine, or the like, which may cause product contamination.

In the composition of the present invention, the polyorganosiloxane of the component (B) is 0.5 to 5.0 parts by weight, preferably 1.0 to 5.0 parts by weight based on 100 parts by weight of the rubber-modified styrenic resin of the component (A).
It is necessary to mix it in a ratio of 3.0 parts by weight. If the amount is less than 0.5 parts by weight, the effect of the present invention is not sufficiently exerted, and if it exceeds 5.0 parts by weight, self-coloring of the molded product is remarkable,
The appearance is likely to be impaired, which may cause troubles during coloring.

The rubber-modified styrene-based resin composition of the present invention is, for example, when the rubber-modified styrene-based resin as the component (A) is polymerized,
It can be prepared by adding the polyorganosiloxane of the component (B), and the component (A) and the component (B)
It can also be prepared by dry-blending the components and then melt-kneading them using a kneader such as an extruder. It is also possible to prepare by preparing a master pellet having a high polyorganosiloxane concentration from a rubber-modified styrene resin and a polyorganosiloxane, and mixing the master pellet with the rubber-modified styrene resin.

The rubber-modified styrenic resin composition of the present invention may optionally contain various additives conventionally used in styrenic resin compositions, such as lubricants, antioxidants, plasticizers, flame retardants, light stabilizers, and coloring agents. Agent, antistatic agent, etc. may be added, and further, a fiber reinforcing agent such as glass fiber or a filler such as an inorganic filler may be filled. As the lubricant,
For example, stearic acid, behenic acid, stearamide, methylene bis stearamide, ethylene bis stearamide, and the like, as the antioxidant, for example, 2,6-t-butyl-4-methylphenol, stearyl-β- (3, 5-
Di-t-butyl-4-hydroxyphenyl) propionate, triethylene glycol-bis-3- (3-t-
Butyl-4-hydroxy-5-methylphenyl) propionate and other hindered phenols and tri (2,4-
Phosphorus compounds such as di-t-butylphenyl) phosphite and 4,4′-butylidenebis (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite are used as plasticizers, for example, mineral oil and Polyethylene glycol or the like is used. Further, as the flame retardant, for example, a combination of an organic halogen-based flame retardant such as tetrabromobisphenol A, decabromodiphenyl oxide, brominated polycarbonate and antimony oxide can be preferably mentioned.

Furthermore, the rubber-modified styrene resin composition of the present invention,
For example, use as a molding material by blending with resins such as ABS resin, polystyrene, polyvinyl chloride, styrene-acrylonitrile resin, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, nylon 6, nylon 11, nylon 12, polyphenylene oxide, polyphenylene sulfide. You can also

[Examples] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

 Each physical property was evaluated according to the following methods.

(1) Sliding property A cylindrical test piece with an outer diameter of 26 mm, an inner diameter of 20 mm, and a height of 15 mm is molded, and a polydimethylsiloxane additive-free product is separately 50 mm ^φ ×
Mold into a 3mm ^t disk.

When one end of the cylindrical molded product of the test piece is brought into contact with the disc surface and a pressure load of 0.5 kg · f is applied and the cylindrical molded product is rotated at a constant rotation speed using a friction wear tester, From the melting limit rotational speed at which the test piece and the disc were fused and the time until the fusion was reached, the rotational speed at which no fusion was performed for 30 minutes was used as an index of slidability.

(2) Rigidity (flexural modulus) Obtained according to ASTM D-790.

(3) Impact resistance (Izod impact strength) It was determined according to JIS K-7110 (notched).

(4) Mold corrosion prevention After molding a 80 mm × 40 mm × 2 mm ^t molded product for 4 hours continuously, observe the generation state of oily substance adhering to the mold, and visually check 5
At the stage (5 points: good, 1 point: bad), a score was given.

Here, as a result of GC analysis of the oily substance in the defective product, a component of 20 parts or less of polyorganosiloxane or carboxylic acid (formic acid, etc.) was detected, and it was estimated that this was a causative substance of mold corrosion. .

(5) Average particle size of rubber-like component A transmission electron micrograph (magnification of 10,000) of a rubber-modified styrenic resin by an ultrathin section method was taken and the number of dispersed particles in the photo was estimated to be 800 to 2000. I asked for it as follows.

That is, since the dispersed particles seen in the electron microscope are not perfectly circular, the diameter a in the longitudinal direction and the diameter b in the short width direction are measured and The average particle diameter was determined by the average particle diameter Ds (μm) = ΣniDi ³ / ΣniDi ² (where ni is the number of dispersed particles having the particle diameter Di).

The content of the n-mer component in the polyorganosiloxane was determined by GLC analysis (FID detection, internal standard method) of the upper layer after mixing 1 g of the sample with 10 g of acetone and shaking for 24 hours.

Example 1 In a first polymerization vessel having a capacity of 13 and maintained at 93 ° C., 1,1 parts of 100 parts by weight of a mixture of 5.3% by weight of polybutadiene rubber, 89.7% by weight of styrene monomer and 5.0% by weight of ethylenebenzene was added.
Bis (t-butylperoxy) -3,3,5-trimethylcyclohexane 0.035 parts by weight, n-dedosyl mercaptan
A raw material mixture containing 0.020 parts by weight and 0.070 parts by weight of an antioxidant (Irganox 1076, manufactured by Chippa-Geigy),
Polymerization was carried out by continuously feeding at a feed rate of 10 per hour, and then the partial polymer was heated at a volume of 13 ° C maintained at 112 ° C.
Was sent to the second polymerization tank of No. 2 to continue the polymerization. This polymer is
Further, it is sent to a third polymerization tank having a capacity of 19 and then to a fourth polymerization tank having a capacity of 20, and the polymerization is continued at a temperature of 120 to 180 ° C., and then the volatile components are removed by a devolatilization device to obtain pelletized rubber-like components. A rubber-modified polystyrene resin containing 6.2% by weight was obtained.

Next, to 100 parts by weight of this rubber-modified polystyrene resin,
Add 2.5 parts by weight of polydimethylsiloxane (viscosity 10,000 cSt./25°C, content of organosiloxane 20-mer or less 350 wtppm, Toray Silicone Co., SH-200 oil low molecular weight component cut product), and extruder Was kneaded to prepare a resin composition.

This resin composition was injection molded and the physical properties of the molded product were measured. Table 1 shows the results.

Example 2 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (Example 1
3.5 parts by weight (the same kind as used in 1.) were added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

Example 3 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (Example 1
1.0 part by weight of the same kind as used in 1) was added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

Example 4 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was added with polydimethylsiloxane (viscosity 60,00).
0 cSt./25° C., the content of components of organosiloxane 20-mer or less 400 ppm by weight, and 2.5 parts by weight of KF-96ST manufactured by Shin-Etsu Chemical Co., Ltd.) were added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

Example 5 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was added with polymethylphenylsiloxane (viscosity 5,000 cSt./25° C., content of components of organosiloxane 20-mer or less 320 ppm by weight, Toray 2.5 parts by weight of SH-710 oil low molecular weight component cut product manufactured by Silicone Co., Ltd.) was added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

Example 6 A mixture of 5.6% by weight of ethylene / propylene rubber (EP02P, manufactured by Japan Synthetic Rubber Co., Ltd.) and 94.4% by weight of styrene monomer was added to the first polymerization tank having a capacity of 1.8 g maintained at 113 ° C. at an hour.
Polymerization was carried out while continuously feeding maleic anhydride at a feed rate of 6.1 g / h at the same time as feeding continuously at a feed rate of.

The partially polymerized product was then added to a volume of 2.8 maintained at 132 ° C.
At the same time as sending to the second polymerization tank of
After further polymerizing while feeding at a feeding rate of 5.4 g, the volatile components of this polymer were removed by a devolatilizer, and the rubber-modified styrene-based rubber containing 14.1% by weight of a rubber component in pellet form. A resin was obtained.

Next, to 100 parts by weight of this rubber-modified styrenic resin, 2.5 parts by weight of polydimethylsiloxane (the same kind as used in Example 1) was added and kneaded with an extruder to prepare a resin composition. Then, this was injection-molded and the physical properties of the molded product were measured. Table 1 shows the results.

Comparative Example 1 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was added with polydimethylsiloxane (viscosity 100 cS
t./25° C., 2.5 parts by weight of Shin-Etsu Chemical Co., Ltd. KF-96ST) were added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

Comparative Example 2 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity of 10,00).
A resin composition was prepared by adding 2.5 parts by weight of 0 cSt./25° C., content of components of organosiloxane 20 mer or less 4,000 ppm by weight, Toray Silicone Co., Ltd., SH-200 oil) and kneading with an extruder. Table 1 shows the results.

Comparative Example 3 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polymethylphenylsiloxane (viscosity 45,000 cSt./25° C., content of components of organosiloxane 20 mer or less 4,800 ppm by weight, Toray Silicone, SH-71
0 oil) (2.5 parts by weight) was added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

Comparative Example 4 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (Example 1
0.3 parts by weight of the same type as used in 1) was added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

Comparative Example 5 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (Example 1
5.5 parts by weight (the same kind as used in 1.) were added and kneaded with an extruder to prepare a resin composition. Table 1 shows the results.

[Advantages of the Invention] According to the present invention, by incorporating a specific polyorganosiloxane into a rubber-modified styrene-based resin, it is possible to obtain excellent sliding property, rigidity, and impact resistance, as well as a good mold corrosion prevention property. A rubber-modified styrene resin composition can be easily obtained.

The rubber-modified styrene-based resin composition of the present invention is particularly suitable for use as a sliding material in reels for video tapes, OA equipment parts, and the like.

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Claims (3)

(57) [Claims] 1. (A) 85 to 96% by weight of an aromatic vinyl monomer alone or a combination of an aromatic vinyl monomer and a vinyl monomer copolymerizable with the aromatic vinyl monomer, and a rubber dissolved therein. Polymer 15
To 100 parts by weight of rubber-modified styrenic resin obtained by polymerizing a mixture of 4 to 4% by weight, (B) the viscosity at a temperature of 25 ° C. is 500 to 100,000 centistokes, and the content of organosiloxane 20-mer or less is 500. A rubber-modified styrene resin composition comprising 0.5 to 5.0 parts by weight of a polyorganosiloxane in an amount of ppm by weight or less. 2. A vinyl-based monomer 1 to 40 in which the rubber-modified styrene resin as the component (A) is copolymerizable with 4 to 15% by weight of a rubber-like polymer and 56 to 84% by weight of an aromatic vinyl monomer. The rubber-modified styrenic resin composition according to claim 1, wherein the rubber-modified styrene-based resin composition is obtained by polymerizing a mixture with a weight% thereof. 3. The rubber-modified styrene resin composition according to claim 2, wherein the copolymerizable vinyl monomer is an unsaturated dicarboxylic acid anhydride.