JP2011021076A - Syndiotactic polystyrene-based resin composition - Google Patents

Abstract

The present invention provides a resin composition having a heat resistance and a practical impact strength, excellent fluidity and retention stability, and having reduced mold contamination during molding, and a molded product thereof.
A total of (a) 22-99.5% by mass of a styrenic polymer having a syndiotactic structure and (b) 0.5-78% by mass of a hydrogenated styrene-butadiene-styrene block copolymer. (C) 0.005 to 6 parts by mass of a crystal nucleating agent, (d) 0.005 to 6 parts by mass of an antioxidant having no phosphorus in the structure, and (e) a fibrous form with respect to 100 parts by mass A silicone oil containing 3 to 155 parts by mass of a reinforcing agent, (f) having a methyl group and / or a phenyl group in the structure, and having a tetramer or less oligomer component of 100 ppm or less (a) to (e ) A syndiotactic polystyrene resin composition containing 0.005 to 6 parts by mass with respect to a total of 100 parts by mass of the components, and a molded product formed by molding the resin composition.
[Selection figure] None

Description

  The present invention relates to a styrenic polymer resin composition having a syndiotactic structure and a molded article thereof. More specifically, the molded product has heat resistance and practical impact strength, which are excellent characteristics of a styrenic polymer having a syndiotactic structure, excellent fluidity and retention stability, and mold contamination during molding. The present invention relates to a resin composition having a reduced content and a molded product thereof.

The styrenic polymer resin composition having a syndiotactic structure is a resin composition having excellent heat resistance, chemical resistance and electrical properties, and is widely used in automobile parts, tableware / food containers, electrical / electronic parts, etc. It is provided. However, there is a problem that moldability such as mold contamination and retention stability at the time of molding is insufficient.
Examples of the styrenic polymer resin composition having a syndiotactic structure include Patent Documents 1 and 2. However, in these patent documents, there is no contrivance such that an antioxidant having phosphorus in the structure causing mold contamination is not added. Moreover, there is no description about using a specific silicone oil.

Japanese Patent Application Laid-Open No. 11-172061 Japanese Patent Application Laid-Open No. 11-172062

  The present invention was made to solve the above-mentioned problems, and the molded article has heat resistance and practical impact strength, which are excellent characteristics of a styrene polymer having a syndiotactic structure, and has fluidity and retention. An object of the present invention is to provide a resin composition having excellent stability and reduced mold contamination during molding, and a molded product thereof.

As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using a composition having the following components and contents, thereby completing the present invention. It came to.
That is, the present invention
(A) 22-99.5% by mass of a styrenic polymer having a syndiotactic structure;
(B) Hydrogenated styrene-butadiene-styrene block copolymer with respect to a total of 100 parts by mass with 0.5 to 78% by mass,
(C) 0.005 to 6 parts by mass of a crystal nucleating agent,
(D) containing 0.005 to 6 parts by mass of an antioxidant not containing phosphorus in the structure, and (e) 3 to 155 parts by mass of a fibrous reinforcing agent, and (f) a methyl group and / or phenyl Shinji containing 0.005 to 6 parts by mass of silicone oil having a group in the structure and having a tetramer or less oligomer component of 100 ppm or less with respect to a total of 100 parts by mass of components (a) to (e) The present invention provides an tactic polystyrene-based resin composition and a molded product obtained by molding the resin composition.

  A molded product obtained from the syndiotactic polystyrene resin composition of the present invention has heat resistance and practical impact strength, which are excellent characteristics of a styrene polymer having a syndiotactic structure, and is called fluidity and residence stability. It is excellent in productivity and can reduce mold contamination during molding.

The syndiotactic polystyrene resin composition of the present invention is
(A) 22-99.5% by mass of a styrene polymer (SPS) having a syndiotactic structure;
(B) Hydrogenated styrene-butadiene-styrene block copolymer with respect to a total of 100 parts by mass with 0.5 to 78% by mass,
(C) 0.005 to 6 parts by mass of a crystal nucleating agent,
(D) containing 0.005 to 6 parts by mass of an antioxidant not containing phosphorus in the structure, and (e) 3 to 155 parts by mass of a fibrous reinforcing agent, and (f) a methyl group and / or phenyl A silicone oil having a group in the structure and having a tetramer or less oligomer component of 100 ppm or less is contained in an amount of 0.005 to 6 parts by mass with respect to 100 parts by mass in total of the components (a) to (e).

The component (a) is preferably 30 to 99% by mass, more preferably 80 to 99% by mass, of the total amount of the components (a) and (b), and the component (b) is 1 to 70% by mass. %, Preferably 1 to 20% by mass. When the component (b) is 0.5% by mass or less, the impact resistance of the obtained molded product is lowered, and when it is 78% by mass or more, the mold is contaminated during molding.
Moreover, (a) and (b) component total 100 mass parts,
The component (c) is preferably 0.01 to 4 parts by mass, more preferably 0.01 to 5 parts by mass, and 0.005 parts by mass or less expressing the function as a crystal nucleating agent. Therefore, it is difficult to secure the mold release rigidity at the time of molding, and if it is 6 parts by mass or more, the mold is contaminated.
The component (d) is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and if it is 0.005 parts by mass or less, the residence stability deteriorates and 6 parts by mass. If it is more than the part, the mold will be contaminated.
The component (e) is preferably 15 to 100 parts by mass, more preferably 15 to 80 parts by mass, and is added to improve the rigidity of the resin composition. If it is 155 parts by mass or more, the fluidity during molding is insufficient. To do.
Furthermore, with respect to 100 parts by mass of the sum of components (a) to (e), component (f) is preferably 0.01 to 4 parts by mass, more preferably 0.01 to 3 parts by mass, If it is 0.005 parts by mass or less, the releasability is deteriorated, and if it is 6 parts by mass or more, the mold is contaminated.

Hereinafter, specific examples of these components will be described.
(A) Polystyrene resin having a syndiotactic structure The syndiotactic structure in a polystyrene resin having a syndiotactic structure is a syndiotactic structure, that is, a main chain formed from a carbon-carbon bond. On the other hand, it has a three-dimensional structure in which phenyl groups as side chains are alternately positioned in opposite directions, and its tacticity is quantified by a nuclear magnetic resonance method ( ¹³ C-NMR method) using isotope carbon. ^The tacticity measured by the ¹³ C-NMR method can be indicated by the abundance ratio of a plurality of consecutive structural units, for example, a dyad for two, a triad for three, a pentad for five. However, the polystyrene-based resin having a syndiotactic structure is usually 75% or more, preferably 85% or more, or 30% or more, preferably 50% or more, of racemic pentad. Polystyrene, poly (alkyl styrene), poly (halogenated styrene), poly (halogenated alkyl styrene), poly (alkoxy styrene), poly (vinyl benzoate), hydrogenated polymers thereof and mixtures thereof, Or the copolymer which has these as a main component is designated. Here, as poly (alkylstyrene), poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (t-butylstyrene), poly (phenylstyrene), poly (vinylnaphthalene) And poly (vinyl styrene). Examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), and poly (fluorostyrene). Examples of poly (halogenated alkylstyrene) include poly (chloromethylstyrene), and examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).
Among these, particularly preferred polystyrene resins include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (pt-butylstyrene), poly (p-chlorostyrene), poly (M-chlorostyrene), poly (p-fluorostyrene), hydrogenated polystyrene, and copolymers containing these structural units.
The polystyrene resin having such a syndiotactic structure is, for example, a styrene monomer having a titanium compound and a condensation product of water and trialkylaluminum in the presence of an inert hydrocarbon solvent or in the absence of a solvent as a catalyst. The polymer (a monomer corresponding to the above polystyrene resin) can be polymerized (Japanese Patent Laid-Open No. 62-187708). Poly (halogenated alkylstyrene) can be obtained by the method described in JP-A-1-46912, and these hydrogenated polymers can be obtained by the method described in JP-A-1-178505.
These polystyrene resins having a syndiotactic structure can be used alone or in combination of two or more.

(B) Rubber-like elastic body Examples of rubber-like elastic bodies include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiocol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, styrene- Butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), Styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer Olefin-based rubbers such as ethylene propylene rubber (EPM), ethylene-propylene diene rubber (EPDM), ethylene-octene copolymer-based elastomers; butadiene-acrylonitrile-styrene-core-shell rubber (ABS), methyl methacrylate-butadiene- Styrene-core shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene-core shell rubber (MAS), octyl acrylate-butadiene-styrene-core shell rubber (MABS), alkyl acrylate-butadiene-acrylonitrile-styrene-core shell rubber (ABS), Siloxane-containing cores such as butadiene-styrene-core shell rubber (SBR), methyl methacrylate-butyl acrylate-siloxane Particulate elastic material of the core-shell type, such as Rugomu, these modified rubbers, and the like. Of these, SBR, SEB, SBS, SEBS, SIR, SEP, SIS, SEPS or rubbers modified from these are preferably used. The styrene content is preferably 20 to 80 wt%, and the fluidity is preferably 1 g / 10 min or less, including those that do not flow at 200 ° C. and 10 kg MFR. If the styrene content is 20 wt% or less, sufficient interface strength with syndiotactic polystyrene cannot be obtained, and if it is 80 wt% or more, the effect of improving the elongation due to the addition of a rubber-like elastic body is small. Moreover, when it exceeds 1 g / 10min by 200 degreeC and 10 kg MFR, the effect of a tensile physical property improvement will be small.
In addition, these rubber-like elastic bodies can be used individually by 1 type or in combination of 2 or more types.

(C) Crystal nucleating agent Crystal nucleating agents include high melting point polymers, aromatic sulfonates or metal salts thereof, organophosphate compounds or metal salts thereof, dibenzylidene sorbitol or derivatives thereof, rosin acid partial metal salts, Inorganic fine particles, imidic acid, amic acid, quinacridones, quinones, or a mixture thereof may be mentioned.
Examples of the high melting point polymer include polyolefins such as polyethylene and polypropylene. The polymer used as the high melting point polymer is usually a polymer having a melting point of 100 ° C. or higher, preferably 120 ° C. or higher, and polypropylene is particularly preferable.
Examples of the organophosphate metal salt include ADEKA STAB NA-11 manufactured by ADEKA Corporation.
Examples of the dibenzylidene sorbitol or derivatives thereof include dibenzylidene sorbitol, 1,3: 2,4-bis (o-3,4-dimethylbenzylidene) sorbitol, 1,3: 2,4-bis (o-2,4). -Dimethylbenzylidene) sorbitol, 1,3: 2,4-bis (o-4-ethylbenzylidene) sorbitol, 1,3: 2,4-bis (o-4-chlorobenzylidene) sorbitol and 1,3: 2, Specific examples include 4-dibenzylidene sorbitol, such as Gelall MD and Gelall MD-R manufactured by Shin Nippon Rika Co., Ltd.
Examples of the rosin acid partial metal salt include Pine Crystal KM1600, Pine Crystal KM1500, and Pine Crystal KM1300 manufactured by Arakawa Chemical Industries, Ltd.
Examples of the inorganic fine particles include talc, clay, mica, asbestos, glass fiber, glass flake, glass beads, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, alumina, silica, diatomaceous earth, titanium oxide, magnesium oxide, Pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, molybdenum sulfide and the like can be mentioned.
In addition, these crystal nucleating agents can be used individually by 1 type or in combination of 2 or more types.

(D) Antioxidant Examples of the antioxidant include hindered phenol compounds and thioether compounds.
Examples of the hindered phenol compounds include 2,6-di-t-4-methylphenol (BHT), 2,6-di-t-4-ethylphenol (NOCRACK M-17), 2,6-di- t-4-phenylphenol (Noclaiser NS-260), 2,2′-methylenebis (4-methyl-6-tert-butylphenol) (Sumilizer MDP-S, Nocrack NS-6), 2,2′-methylenebis (4 -Ethyl-6-t-butylphenol) (Nocrack NS-5), 2,2'-methylenebis (4-ethyl-6-n-nonylphenol) (Noclaiser NS-90), 4,4'-butylidenebis (3-methyl) -6-tert-butylphenol) (Sumilizer BBM-S, Nocrack NS-30, Adekastab AO-40), 4,4 '-Thiobis (3-methyl-6-tert-butylphenol) (Sumilizer WX-R, Nocrack 300), 1,1,3-tris (5-tert-butyl-4-hydroxy-2-methylphenyl) butane (Adekastab) AO-30), 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (Sumilizer GM), 2- [1- (2-hydroxy- 3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate (Sumilizer GS), n-octadecyl-3- (3,5-di-t-4-hydroxyphenyl) Propionate (IRGANOX 1076, Adekastab AO-50, Sumilizer BP-76), 3, -Di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester (IRGANOX 1222), triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] ( IRGANOX 245), 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (IRGANOX 249), 2,2-thio-diethylenebis [3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (IRGANOX 1035), N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide) (IRGANOX 1098), 3,9-bis [1,1-dimethyl-2- [β {(3-t-butyl -4-hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane (Sumilizer GA-80, Adekatab AO-80), N, N'- Bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine (IRGANOX MD1024), pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxy Phenyl) propionate] (IRGANOX 1010, Adekastab AO-60, Sumilizer BP-101), 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1 , 3,5-triazine (IRGANOX 565), 1,3,5-tri Chill-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (IRGANOX 1330, Adekatab AO-330), tris (3,5-di-t-butyl-4- Hydroxybenzyl) isocyanurate (IRGANOX 3114, Adekastab AO-20) and tris (4-t-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate (Cyanox 1790) are preferred.
Among these, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (Sumilizer GM), 2- [1- (2-hydroxy-3, 5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate (Sumilizer GS), n-octadecyl-3- (3,5-di-t-4-hydroxyphenyl) propionate ( IRGANOX 1076, Adekastab AO-50, Sumilizer BP-76) and pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (IRGANOX 1010, Adekastab AO-60, Sumilizer BP-101) is more preferred .
“NOCRACK” and “NOCRIZER” are trade names of Ouchi Shinsei Chemical Co., Ltd., “Sumilizer” is the trade name of Sumitomo Chemical Co., Ltd., “Adekastab” is the trade name of Asahi Denka Kogyo Co., Ltd., and “IRGANOX” Is a trade name of a product of Ciba Specialty Chemicals, Inc., and “Cyanox” is a trade name of a product of Cytec Industry Co., Ltd. The same applies to trivalent organic phosphorus compounds and thioether compounds described later.

Examples of the thioether compound include dilauryl 3,3′-thiodipropionate (Sumilizer TPL-R, Nocrack 300), ditridecyl 3,3′-thiodipropionate (Sumilizer TL), dimyristyl 3,3′-thiodipropioate. (Sumilizer TPM), distearyl 3,3'-thiodipropionate (Sumilizer TPS), distearyl 3,3'-methyl-3,3'-thiodipropionate, bis [2-methyl-4- ( 3-n-alkyl (C ₁₂ or C ₁₄ ) thiopropionyloxy) -5-tert-butylphenyl] sulfide ((Adekatab AO-503A), tetrakis [methylene-3- (hexylthio) propionate] methane, tetrakis [methylene- 3- (Dodecylthio) pro Pionate] Methane (Sumilizer TP-D, Adekastab AO-412S), Tetrakis [methylene-3- (octadecylthio) propionate] methane, 2-mercaptobenzimidazole (Sumilizer MB, Nocrack MB) and 2-mercaptomethylbenzimidazole (Nocrack) Among them, tetrakis [methylene-3- (dodecylthio) propionate] methane (Sumilizer TP-D, Adekatab AO-412S) is more preferable.
In the present invention, phosphorus is not contained in the structure because the decomposition product of the antioxidant having phosphorus in the structure is prevented from adhering to the mold during molding and causing mold contamination. Use an antioxidant.
In addition, these antioxidants can be used individually by 1 type or in combination of 2 or more types.

(E) Fibrous reinforcing agent Examples of the fibrous reinforcing material include glass fiber, carbon fiber, whisker, ceramic fiber, and metal fiber. Specifically, the whiskers include boron, alumina, silica, silicon carbide, the ceramic fibers include gypsum, potassium titanate, magnesium sulfate, and magnesium oxide, and the metal fibers include copper, aluminum, and steel. In the present invention, glass fibers are preferred because surface treatment with high interfacial adhesive strength with the syndiotactic polystyrene resin composition is possible. Here, the shape of the fibrous reinforcing material includes a cloth shape, a mat shape, a convergent cut shape, a short fiber, and a filament shape. In the case of a convergent cut, a length of 0.05 to 50 mm and a fiber diameter of 5 to 20 μm are preferable. In the case of a cloth or mat, the length is 1 mm or more, preferably 5 mm or more.
In addition, these fibrous reinforcing agents can be used individually by 1 type or in combination of 2 or more types.

(F) Silicone oil The silicone oil used in the present invention has a siloxane skeleton and a structure containing a methyl group and / or a phenyl group. For example, KF-54 and KF- manufactured by Shin-Etsu Chemical Co., Ltd. 96, SH200 manufactured by Toray Dow Corning Co., Ltd., etc. In the present invention, a silicone oil having a viscosity at 25 ° C. of 10,000 to 15000 cst and an oligomer component of tetramer or less of 100 ppm or less is used.
(F) If the viscosity at 25 ° C. of the component is less than 10000 cst, the generated gas at the time of molding increases and contaminates the mold. If it exceeds 15000 cst, the pellet surface is uniformly covered during pre-mixing before kneading. Is difficult.
If the oligomer component of tetramer or less in the component (f) exceeds 100 ppm, the mold is contaminated.

  In addition, the resin composition of the present invention includes a filler other than the fibrous reinforcing material (e), an ultraviolet absorber, a heat stabilizer, a light resistant (weather resistant) agent, and a lubricant as long as the effects of the present invention are not impaired. , Mold release agents, crystal nucleating agents other than the component (d), colorants including dyes and pigments, and the like can be blended.

  There is no restriction | limiting in particular about the preparation method of the resin composition of this invention, It can prepare by a well-known method. For example, the above components may be blended by various methods such as mixing at room temperature or melt kneading, and the method is not particularly limited. Among these mixing and kneading methods, melt kneading using a twin screw extruder is preferably used. In melt kneading using a twin screw extruder, kneading at a temperature higher than the melting point of the SPS used and lower than 350 ° C. is preferred. By setting the kneading temperature to be equal to or higher than the melting point of the SPS, the viscosity of the SPS does not become too high, so that productivity does not decrease. Moreover, there is no possibility that SPS will thermally decompose by setting it as less than 350 degreeC.

  There is no restriction | limiting in particular also about the shaping | molding method using the resin composition of this invention, It can shape | mold by well-known methods, such as injection molding and extrusion molding. The molding temperature at the time of injection molding is preferably higher than the melting point of the SPS used and lower than 350 ° C. By setting the molding temperature to be equal to or higher than the melting point of SPS, there is no possibility that fluidity is lowered, and when it is lower than 350 ° C., there is no possibility that SPS is thermally decomposed. Moreover, as mold temperature, 140-200 degreeC is preferable and 150-180 degreeC is still more preferable. By setting the mold temperature to 140 ° C. or higher, SPS is sufficiently crystallized and the characteristics of SPS are fully exhibited. Moreover, since the rigidity at the time of mold release does not fall by setting it as 200 degrees C or less, there is no possibility that an ejector crack and a deformation | transformation generate | occur | produce.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.
Examples 1-10 and Comparative Examples 1-10
The following components were used as blending components.
Component (a) SPS: 1,2,4-trichlorobenzene as a solvent, polystyrene having a weight average molecular weight Mw in terms of polystyrene measured by GPC method at 150 ° C. of 200,000 and a molecular weight distribution Mw / Mn of 2.20 Syndiotactic polystyrene (b) component Septon 8006: SEBS type elastomer (manufactured by Kuraray) Styrene content 33 wt%
(C) Component NA-11 (trade name, manufactured by ADEKA CORPORATION)
(D) Component (d) -1. IRGANOX1010 (trade name, manufactured by Ciba Specialty Chemicals Co., Ltd.)
Phenolic antioxidants that do not contain phosphorus in the structure (d) -2. PEP36 (trade name, manufactured by ADEKA CORPORATION)
Antioxidant (e) component containing phosphorus in structure 03 JA FT 164G: Glass fiber (trade name, manufactured by Owens Corning, chopped strand type, average fiber diameter 10.5 μm, average fiber length 3 mm)
(F) Component (f) -1. SH200CV (trade name, manufactured by Toray Dow Corning Co., Ltd.)
Silicone oil (f) having a viscosity at 25 ° C. of 13000 sct and an oligomer component up to tetramer of 100 ppm or less-2. SH200 (trade name, manufactured by Toray Dow Corning Co., Ltd.)
Silicone oil having a viscosity of 12500 sct at 25 ° C. and an oligomer component up to a tetramer of 500 ppm

  After dry blending the above ingredients, the mixture is melt kneaded while side-feeding glass fibers at a cylinder temperature of 290 ° C. using a twin-screw extruder, and the resulting strand is cooled through a water bath and then pelletized to form a resin composition Was prepared. The following evaluation was performed using the obtained resin composition. Table 1 shows the resin composition of the components (a) and (b), and Table 2 shows the components (c), (d), and (e) for 100 parts by mass of the sum of the components (a) and (b). The resin composition, Table 3 shows the amount of component (f) relative to 100 parts by mass of the sum of components (a) to (e), and Table 4 shows the composition and evaluation results of the resin composition obtained.

<Evaluation items>
(1) Melting point (Tm) / crystallization temperature (Tc)
Measures the melting point, which is an index of heat resistance of crystalline resins, and the crystallization temperature, which is an index of nucleating agent performance. Evaluation is performed by measuring the peak temperature of melting and the peak temperature of crystallization by differential scanning calorimetry (DSC) method (heating rate: 20 ° C./min). Unit: ° C.
(2) Mold fouling Using a 100-ton molding machine manufactured by Sumitomo Heavy Industries, the deposits were visually confirmed when molded at 290 ° C. for 200 shots. The ease of wiping with ethanol was also confirmed.
○: No deposit / good wiping property △: Cloudy / bad wiping property, but wiping possible ×: Liquid, solid deposit and cloudy / No wiping (3) Residence stability After melting at 290 ° C. for 3 minutes, The viscosity after melting for 10 minutes was measured, and the viscosity retention rate of the viscosity after melting for 10 minutes relative to the viscosity after melting for 3 minutes was evaluated. unit:%.
(4) MFR
MFR, which is an index of fluidity, was measured according to JIS-K7210. Unit: g / 10 min.
(5) Izod impact strength (notched)
Based on JIS-K7110, it was measured in the shape of a specified molded product. Unit: kJ / m ² .

  As is apparent from Table 4, the resin composition of the present invention has a melting point that is an index of heat resistance, a crystallization temperature that is important for mold release rigidity, MFR that is an index of residence stability and fluidity, Izod impact strength, It can be seen that it has releasability and can reduce mold contamination during molding.

As described above in detail, the molded product obtained from the syndiotactic polystyrene resin composition of the present invention has heat resistance and practical impact strength, which are excellent characteristics of a styrene polymer having a syndiotactic structure. In addition, it has excellent productivity such as fluidity and retention stability, and can reduce mold contamination during molding.
For this reason, the molded article formed by molding the syndiotactic polystyrene resin composition of the present invention is useful as, for example, automobile parts having a large number of moldings and materials for daily necessities requiring good appearance, such as chopsticks.

Claims (4)

(A) 22-99.5% by mass of a styrenic polymer having a syndiotactic structure;
(B) Hydrogenated styrene-butadiene-styrene block copolymer with respect to a total of 100 parts by mass with 0.5 to 78% by mass,
(C) 0.005 to 6 parts by mass of a crystal nucleating agent,
(D) 0.005 to 6 parts by mass of an antioxidant having no phosphorus in the structure;
(E) A silicone oil containing 3 to 155 parts by mass of a fibrous reinforcing agent, (f) having a methyl group and / or a phenyl group in the structure, and having a tetramer or less oligomer component of 100 ppm or less ( A syndiotactic polystyrene-based resin composition containing 0.005 to 6 parts by mass with respect to a total of 100 parts by mass of components a) to (e).   The syndiotactic polystyrene resin composition according to claim 1, wherein (e) is a glass fiber.   A molded product formed by molding the resin composition according to claim 1.   A chopstick made of the molded product according to claim 3.