JPH03168242A - Styrene-based resin composition - Google Patents

Abstract

PURPOSE:To obtain a composition useful as OA(office automation) device parts and sliding materials, having excellent impact strength, luster and sliding properties, comprising a rubber modified styrene based resin composition having occlusion structure and polyorganosiloxane having specific viscosity CONSTITUTION:A styrene-based resin composition comprising (A) 100 pts.wt. resin composition which consists essentially of a rubber modified styrene-based resin composition having occlusion structure in a dispersed rubber state obtained by polymerizing styrene with an arbitrarily copolymerizable monomer in the presence of a rubber-like polymer (preferably styrene-butadiene block polymer) by bulk-suspension two-stage polymerization and <=45wt.%, preferably <=40wt.% based on the total amounts of component having a salami structure and (B) 0.5-5 pts.wt., preferably 1-3.5 pts.wt. polyorganosiloxane having 500-100,000, preferably 800-80,000 centistokes viscosity at 25 deg.C.

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to a novel styrenic resin composition. More specifically, the present invention relates to a novel styrenic resin composition, which has high C) impact strength and excellent gloss, and is suitable as a material for OA equipment parts and a sliding material. The present invention also relates to a styrenic resin composition having excellent physical properties such as sliding properties.

[Conventional technology]

Styrene resin is used as a material for videotape reels and keyboard parts for personal computers, computer phones, etc. When used as such material, it is required to have good sliding properties in addition to impact resistance. It is known that it is effective to add polyorganosiloxane to styrenic resin in order to impart this sliding property to styrenic resin. Method for manufacturing embroidery (Japanese Patent Publication No. 52-43863, Publication No. 63-15
287) and a styrene resin composition containing polyorganosiloxane (Japanese Patent Laid-Open No. 60-217254). However, the rubber-modified styrene resin used in these styrene resins has a salami structure, so styrenic resins made by mixing polyorganosiloxane with this resin have improved sliding properties and impact resistance. Although it has been
The drawback was that the gloss was low. Therefore, there was a problem in that it was not possible to escape from restrictions on usage. [Problems to be Solved by the Invention] The present invention overcomes the drawbacks of conventional styrenic resin compositions, and has a good balance of physical properties such as high impact strength, excellent gloss and sliding properties. This was developed with the aim of providing a styrenic resin composition with excellent properties. [Means for Solving the Problems] In order to develop a styrenic resin composition with an excellent balance of physical properties such as impact resistance, gloss, and sliding properties, the inventor of the present invention has conducted extensive research and found that rubber-modified We have found that the use of a rubber-modified styrene resin composition in which the dispersed rubber form has an occlusion structure is suitable for the above purpose, and based on this knowledge, we have completed the present invention. . That is, (a.) 100 parts by weight of a rubber-modified styrene resin composition whose dispersed rubber form has an occlusion structure and (b) a viscosity at 25°C of 500 to 100.0 parts by weight.
00 centistokes polyorganosiloxane 0.5
The present invention provides a styrenic resin composition characterized in that the composition contains 5 parts by weight. The present invention will be explained in detail below. (a) Rubber-modified styrenic resin in the styrenic resin composition of the present invention! It is necessary that the dispersed rubber form has an occlusion structure. If the dispersed rubber form does not have an occlusion structure, the impact resistance and gloss will be poor. Here, the occlusion structure means that in one rubber particle,
It refers to a structure in which the core is made of a styrene polymer and the shell is made of a rubber-like polymer. It contains 5 or less internal occlusions, and at least 50% of them have 1 ftl of internal occlusions. In the present invention, the occlusion structure as described above is
It is preferable that the content is 0% or more, and if 30% or more of particles such as salami structure are mixed, there is a possibility that good gloss cannot be obtained. (a) Boki's rubber-modified styrenic resin composition consists of a styrene polymer and a rubbery polymer. The styrenic polymer may be a styrene homopolymer or a copolymer of a monomer copolymerizable with styrene. Examples of the copolymerizable monomers include σ-methylstyrene, vinylethynoleene, vinylethynolebenzene, vinylexylene, p-t-butylstyrene, α-methyl-p-methylstyrene, promostyrene, Aromatic monovinyl compounds such as chlorostyrene and vinylnaphthalene, acrylonitrile, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid,
Examples include maleic anhydride and phenylmaleimide. These monomers may be used alone or in combination of two or more, but the amount is usually 50% by weight or less, preferably 40% by weight, based on the total monomers containing styrene.
It is used in a proportion of less than % by weight. On the other hand, there are no particular restrictions on the type of rubbery polymer, and those conventionally used in rubber-modified styrenic resin compositions, such as natural rubber, polybutadiene rubber, polyisoprene rubber, and styrene-butadiene copolymers, can be used. rubber,
Synthetic rubbers such as styrene-isobrene copolymer rubber, butyl rubber, and ethylene-propylene copolymer rubber, or graft copolymer rubbers of these rubbers and styrene can be used. Among these, styrene-butadiene block copolymer rubber or a combination of styrene-butadiene block copolymer rubber and polybutadiene rubber is preferred. When styrene-butadiene copolymer rubber and polyptadiene rubber are used together, the amount of polyptadiene rubber is preferably 40% by weight or less, preferably 35% by weight or less. This styrene-butadiene block copolymer rubber has a molecular weight in the range of so,ooo to soo,ooo, and a content of polymer blocks composed of styrenes in the range of 10 to 60% by weight. Some are particularly preferred. An ungrooved material with a molecular weight of so or ooo will not have sufficient impact resistance, and if it exceeds soo or ooo, the fluidity during cutting will decrease, which is not preferable. Also, if the content of the polymer block formed by styrene is less than 10% by weight, the gloss will be poor;
If it exceeds 20%, there is a tendency for impact resistance to decrease. Also,
This styrene-butadiene block copolymer rubber has
Polybutadiene rubber having a molecular weight of about 50,000 to 1,000,000 may be appropriately blended and used. The molecular weight of this rubbery polymer is the weight average molecular weight in terms of polystyrene determined by GPC. The rubbery polymer has an occluded structure and has an area average particle size (diameter) of 0.1 to 0.7 μm, preferably 0.2 to 0.6 μm, and a ratio of The area average particle diameter ratio is 1.0 to 2.5, preferably 1.
．． It is preferable that particles having a particle diameter of 0 to 1.8 are dispersed in the styrene polymer of the above (a). When the area average particle diameter is less than 0.1 μm, impact resistance is insufficient, and when it exceeds 0.7 μm, gloss tends to decrease. Furthermore, when the area average particle diameter relative to the number average particle diameter exceeds 2.5, gloss tends to decrease. Further, the styrenic polymer and the rubbery polymer are respectively 70 to 92% by weight and 30 to 8% by weight, preferably 7% by weight.
The content is preferably 2 to 90% by weight and 28 to 10% by weight. If the content of the rubbery polymer is less than 8% by weight, the effect of improving impact resistance tends to be insufficient, and if it exceeds 30% by weight, gloss and fluidity tend to decrease. (a) Boki's rubber-modified styrenic resin composition can be produced by blending a styrene polymer and a rubbery polymer. Preferably, it is prepared by polymerizing a polymerizable monomer. Next, an example of a preferred method for producing the resin composition of the present invention using a bulk one-suspension two-stage polymerization method will be described. First, styrene or a mixture of a monomer copolymerizable with styrene is
Add the rubbery polymer and heat as necessary to dissolve. It is preferable to perform this dissolution as uniformly as possible. Next, a molecular weight regulator (chain transfer agent) such as alkylmercabutane and a polymerization initiator such as an organic peroxide to be used as necessary are added to this solution, and while heating to a temperature of about 70-150°C, , the degree of polymerization is 10-60% under stirring.
Prepolymerization is carried out by bulk polymerization until . In this prepolymerization step, the rubbery polymer is dispersed into particles by stirring. Next, the prepolymerization solution is suspended in an aqueous phase using tricalcium phosphate, polyvinyl alcohol, or the like as a suspending agent,
Usually, suspension polymerization (main polymerization) is carried out until the degree of polymerization approaches 100%. Note that, if necessary, heating may be continued after this main polymerization step. Examples of the molecular weight regulator include α-methylstyrene dimer, n-dodecylmercabutane, t-dodecylmercabutane, 1-7enylbutene-2-7norolelene,
Examples include mercabutanes such as dibentene and chlorophonolem, terbenes, and halogen compounds. In addition, examples of the polymerization initiator used as desired include 1,1-bis(t-butylberoxy)cyclohexane, 1,1-bis(1-butynolepenoleoxy)3,
3. Beroxyketals such as 5-1-limethylcyclohexane, dialkyl such as dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(di-butylberoxy)hexane, etc. Peroxides, diaryberoxides such as penzoyl peroxide and m-toluoyl peroxide, peroxyesters such as peroxydicarbonates such as dimyristyl peroxydicarbonates and t-butylberoxyisopropyl carbonate, cyclohexanone Examples include organic peroxides such as ketone peroxides such as peroxide, and hydroperoxides such as p-menthane hydroperoxide. The particle size, particle size distribution, and particle structure of the rubber-like polymer can be controlled by changing the stirring rotation speed and the amount of molecular weight regulator used, and the gel amount and swelling index can be controlled by the type and amount of catalyst, It can be controlled by reaction temperature, reaction time, etc. Next, the slurry obtained in this way is treated with a conventional method to remove bead-shaped reactants, dried, and then pelletized according to a conventional method to obtain a rubber-modified styrene whose dispersed rubber form has an occlusion structure. A system polymer is obtained. The molecular weight of the matrix portion of the rubber-modified styrenic resin composition thus obtained is Zoo, 000 to 300,
000, preferably in the range from 130,000 to 280,000. This molecular weight is 100,00
If it is less than 0, the impact resistance will be poor, and if it exceeds 3oo or ooo, the fluidity during molding will be insufficient. Note that the above (a) rubber-modified styrene-based l#tFl71 composition in which the dispersion rubber form of the bokmin has an occlusion structure may contain a rubber-modified styrene-based resin composition having a salami structure. A rubber-modified styrenic resin composition having a salami structure is
Consists of styrene polymer and rubbery polymer. These styrenic polymers and rubber-like polymers are similar to the styrenic polymers and rubber-like polymers of the rubber-modified styrenic resin composition in which the dispersed rubber form has an occludidine structure, but the rubber-like polymer Preferred is polyptadiene rubber. A rubber-modified styrenic resin having a salami structure is one in which 50% or more of rubber particles have six or more occlusions in which the core is a styrene polymer and the shell is a rubbery polymer. be. The content ratio of the rubber-modified styrenic resin composition having a salami structure is 45% by weight of the total amount of the rubber-modified styrenic resin composition whose dispersed rubber form has an occlusion structure and the rubber-modified styrenic resin composition which has a salami structure. % or less, particularly preferably 40% by weight or less. When the content of the rubber-modified styrenic resin composition having a salami structure exceeds 45% by weight, gloss tends to decrease. In the present invention, (b) a polyorganosiloxane having a viscosity of 500 to 100,000 centistokes at 25° C. is used as the 5E component. This polyorganosiloxane has the following general formula (1) ... (1) (R in the formula is an alkyl group, a haloalkyl group, an aryl group, or a haloaryl group, and R 1 and R'' are each a phenyl group or a carbon 1 to 6 alkyl groups, which may be the same or different, and n is such that the polyorganosiloxane has a viscosity of 500 to 100,000 centistokes at 25°C. ) is a natural number. Typical examples of such polyorganosiloxanes are:
Examples include homopolymers and copolymers such as polydimethylsiloxane, polymethyl7enylsiloxane, polydiphenylsiloxane, polytrichloropropylmethylsiloxane, polytrichlorophenylmethylsiloxane, and polymethyl7enyldimethylsiloxane. One type of these polyorganosiloxanes may be used, or two or more types may be used in combination. The polyorganosiloxane used in the present invention needs to have a viscosity at 25°C of SOO to 100,000 centistokes, preferably SOO to go,o
It is in the range of oo centistokes. This viscosity is 500
If it is less than 100,000 centistokes, the purpose of the present invention cannot be fully achieved, and if it exceeds 100,000 centistokes, It becomes extremely difficult to uniformly disperse the product in the product. The content ratio of component (a) and component (b) in the styrenic resin composition of the present invention is (a)! ! ! ．． It is necessary that the amount of the component (b) be in the range of 0.5 to 5 parts by weight, preferably in the range of 1 to 3.5 parts by weight, per 100 parts by weight. (b) If the content is less than 0.5 parts by weight, sliding properties will be insufficient, and if it exceeds 5 parts by weight, the product will become noticeably white, the appearance will be easily impaired, and the gloss will decrease. There is a risk that it may cause problems during coloring. The styrenic resin composition of the present invention can be obtained by blending predetermined amounts of each of these components, and its production may be carried out in accordance with conventional methods. For example, after premixing each portion with a mixer such as a Henschel mixer, tumbler blender kneader, etc., kneading with an extruder, or heating rolls,
Manufactured by melt-kneading in a Banbury mixer. Also, from (a) component and (b) IR component, (b) tI.
It can also be produced by preparing a master pellet with a high concentration and mixing this master pellet with the (a) It component. Furthermore, it can also be produced by adding component (b) during the polymerization of component (a). If desired, the styrenic resin composition may contain various commonly used additives, such as stearic acid, behendicic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylene bisstearamide. Lubricants, mineral oil, or 2,6-gee-t-
Butyl-4-methylphenol, stearin-β~(3
．． 5-di-t-butyl-4-hydroxy-7enyl)probionate, triethylene glycol-bis-3-(3
-t-butyl-4-hydroxy-5-methyl7enyl)
Hindered phenols such as probionate and tri(
2,+-di-1-butylphenyl) phosphite, 4.
4'-Butylidenebis(3-methyl-6-t-butyl7
Add phosphorus-based antioxidants such as enylugetridecyl) phosphite, other ultraviolet absorbers, antistatic agents, mold release agents, laminate agents, flame retardants, stabilizers, dyes, pigments, and various fillers. be able to. Further, other polymers such as polystyrene, poly7-enylene ether, etc. can also be blended. [Example J Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Production example 1 Contents: 5I! A styrene-butadiene block copolymer (manufactured by Bayer) with a molecular weight of 230,000 and a styrene content of 40 wt% was placed in an autoclave equipped with an Ikari-type stirring blade.
BL6533) 527y, polyptadiene (manufactured by Ube Industries, Ltd. BR15HB. molecular weight 550,000) 1329, 3000 g of styrene, and 1 g of n-dodecyl mer-butane as a chain transfer agent were added, and the mixture was stirred at 4Q Orprn.
Bulk polymerization reaction was carried out at 0°C for 4 hours. Next, the reaction mixture 30Q09 and water 300% were placed in an autoclave with an internal capacity tOii equipped with an Ikari-type stirring blade.
09. Polyvinyl alcohol as suspension stabilizer 1 0
n. 6g of penzoyl peroxide as polymerization initiator
and 3 g of dicumyl peroxide, and while stirring at 300 rpm, the temperature was raised from 80 °C to 140 °C at a rate of 30 °O/hr, and the reaction was continued at that temperature for an additional 4 hours to form a rubber-modified polystyrene composite. Got some beads. The beads were pelletized using a single screw extruder at 220°C. The obtained pellets were analyzed using an electron microscope; however, an occlusal structure with an area average particle size of 0.50 μm and a ratio of area average particle size to number average particle size of 2.2 was found to be 8.
It had 5%. The physical properties of a shaped article were a gloss of 96% and an Izod impact strength of 14.8 kg·clI/cM. This copolymer had a rubbery polymer content of 18% and a molecular weight of 210,000. Production Example 2 Production Example 1 was carried out in the same manner as Production Example 1 except that the rotation speed of the stirring blade in bulk polymerization was 50 Orpm. The obtained rubber-modified polystyrene composite had a 90% occlusion structure with an area average particle size of 0.41 μm and a ratio of area average particle size to number average particle size of 2.1, and a gloss of 99%. Izod impact strength is i0.6 & 9.
Cm/cm. This copolymer had a rubbery polymer content of 18% and a molecular weight of 21,500. Example 1 Rubber modified polystyrene composite obtained in Production Example 1 100
Polydimethylsiloxane (Toray Silicone Co., Ltd. IR) having a viscosity of 10,000 centistokes by weight at 25°C
Pre-blended 2.5 parts by weight of SH-200 oil,
The blended material was heated to a cylinder temperature of 220°C using a single screw extruder.
The mixture was melt-kneaded and injection molded to prepare test pieces. The physical properties of this test piece are shown in the WCL table. Example 2 The same procedure as in Example 2 was carried out except that the amount of polydimethylsiloxane in Example 1 was changed to 1.0 parts by weight. Table 1 shows the physical properties of the obtained test piece. Example 3 In Example 1, the rubber-modified polystyrene assembly obtained in Production Example 2 was used instead of the rubber-modified polystyrene assembly obtained in Production Example 1, and the viscosity at 25°C was 10,
Except that 3.5 parts by weight of polymethylphenylsiloxane (SH-700 oil manufactured by Toray Silicone Co., Ltd.) with a viscosity of 5,000 centistokes at 25°C was used instead of polydimethylsiloxane with a viscosity of 5,000 centistokes. The same procedure as in Example 1 was carried out. Table 1 shows the physical properties of the obtained test piece. Example 4 In Example 3, the amount of the rubber-modified polystyrene composite obtained in Production Example 2 was changed to 95 parts by weight, and polymethyl 7-enylsiloxane having a viscosity of 5,000 centistokes at 25°C was used. , viscosity at 25°C is 60,000
2.0 parts by weight of centistokes polydimethylsiloxane (KF-965T manufactured by Shin-Etsu Chemical Co., Ltd.) and 51 parts by weight of a rubber-modified polystyrene composite having a salami structure (Idemitsu Styrene IT50 manufactured by Idemitsu Petrochemical Co., Ltd.) were added. The same procedure as in Example 3 was carried out except for the addition. Table 1 shows the physical properties of the obtained test piece. Example 5 60 parts by weight of the rubber-modified polystyrene composite obtained in Production Example 1, 40 parts by weight of the rubber-modified polystyrene composite having a salami structure (Idemitsu Styrene manufactured by Idemitsu Petrochemical Co., Ltd. 1T54)
Parts by weight, polydimethylsiloxane with a viscosity of io, ooo centistokes at 25°C (S
}1200) 3.0 parts by weight were pre-blended in the same manner as in Example 1 and injection molded to prepare test pieces. The physical properties of this test piece are shown in Table 1. Comparative Example 1 In Example 1, instead of polydimethylsiloxane having a viscosity of 10,000 centistokes at 25°C, 2
Polydimethylsiloxane (KF-96ST, manufactured by Shin-Etsu Chemical Co., Ltd.) with a viscosity of 100 centistokes at 5°C was
．． The same procedure as in Example 1 was conducted except that 5 parts by weight was used. Comparative Example 2 The same procedure as in Example 1 was carried out except that the amount of polydimethylsiloxane was changed to 0.3 parts by weight. Comparative Example 3 In Example 4, instead of polydimethylsiloxane having a viscosity of so, ooo centistokes at 25°C, polydimethylsiloxane (manufactured by Toray Silicone Co., Ltd. SH-200) having a viscosity of 1o, ooo centistokes at 25°C was used. The same procedure as in Example 4 was conducted except that the amount of oil was 5.5 parts by weight. Comparative Example 4 In Example 1, the amount of the rubber-modified polystyrene composition obtained in Production Example 1 was 50 parts by weight, and 50 parts by weight of the rubber-modified polystyrene composition having a salami structure (HT50 manufactured by Idemitsu Petrochemical Co., Ltd.) was added. The same procedure as in Example 1 was carried out except that 1 part was added. The physical properties of Comparative Examples 1 to 4 are shown in Table 1. In addition, the physical properties of the above test piece were measured by the following method. Gloss: Compliant with JISK-7105. Izod impact strength: Compliant with JISK-7110 (23°C notched). Sliding property: A cylindrical test piece with an outer diameter of 26 mra, an inner diameter of 20 mm, and a height of 15 mm is formed, and a polyorganosiloxane-free product is separately formed into a disk of 50 m+m" x 3 mm. Cylindrical shape of the test piece When one end of the product was brought into contact with the disk surface and the cylindrical shaped product was rotated at a constant rotational speed using a friction and wear tester with a pressure load of 0.5k9·f, the test piece and From the melting limit rotational speed at which the cylinder and the cylinder fuse and the time required to reach that point, the rotational speed at which no fusion occurred for 30 minutes was used as an index of slidability. The resin composition has high impact strength because the dispersed rubber has an occlusion structure, and has excellent balance of physical properties such as excellent gloss and sliding properties.

Claims (1)

[Claims] 1 (a) 100 parts by weight of a rubber-modified styrenic resin composition whose dispersed rubber form has an occlusion structure; and (b) 2
A styrenic resin composition comprising 0.5 to 5 parts by weight of a polyorganosiloxane having a viscosity of 500 to 100,000 centistokes at 5°C. 2. The rubber-modified styrenic resin composition is composed of a rubber-modified styrenic-based resin composition in which the dispersed rubber form has an occlusion structure and a rubber-modified styrenic-based resin composition that has a salami structure, and the rubber-modified styrenic resin composition has a salami structure. The styrenic resin composition according to claim 1, wherein the content of the styrenic resin composition is 45% by weight or less.