JP2683035B2 - Styrene resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a styrene-based resin composition, and more specifically, it is prepared by mixing a styrene-based polymer having a syndiotactic structure with a specific particulate elastic material, and injection molding The present invention relates to a styrene resin composition having excellent impact resistance, rigidity and heat resistance suitable as a material for extrusion molding and the like.

[Problems to be solved by conventional technology and invention]

Styrenic resins generally have the major drawback of lacking impact resistance. Therefore, for the purpose of improving this defect, it is widely practiced to form a copolymer (HIPS resin, ABS resin, etc.) with a rubber-like polymer or to mix the rubber-like polymer.

The styrene resin improved in impact resistance by mixing or copolymerizing a rubber-like polymer is widely used. However, depending on the application, a styrene resin having further excellent impact resistance and heat resistance is desired.

By the way, the styrene resin which has been generally used from the past is obtained by radical polymerization, and its stereoregularity has an atactic structure and is amorphous. Therefore, it cannot be said that impact resistance and mechanical strength are sufficiently high, and there is a limit to improvement of these physical properties.

Therefore, the present inventor has conducted earnest research to develop a polystyrene-based resin composition having more excellent physical properties, beyond the limit of the improvement of the physical properties inherent in the conventional styrene-based resin. In the process, a styrene-based polymer having high syndiotacticity previously developed by the group of the present inventors (JP-A-62-104818) was used, and by combining this with a rubber-like polymer, It was found that a resin composition having excellent physical properties can be obtained (Japanese Patent Application No. 62-
305838).

However, in the resin composition disclosed in the above-mentioned Japanese Patent Application No. 62-305838, in order to obtain an Izod impact strength of 10 kgf · cm / cm or more, 30% by weight or more of a rubber-like polymer is blended. is required. As described above, when a large amount of the rubber-like polymer is blended, the excellent rigidity which is a characteristic of the styrene polymer having a syndiotactic structure is lost, and the tensile elastic modulus is decreased to 30,000 kg f / cm ² or less. There is a problem that it will end up. In addition, the heat resistance and chemical resistance of this styrene-based polymer are also reduced.

Conversely, if the amount of the rubber-like polymer is reduced in order to maintain the rigidity of the styrene-based polymer, the Izod impact strength will be well below 10 kg fcm / cm and sufficient impact resistance will be exhibited. Can not be.

[Means for solving the problem]

The present invention eliminates the inconveniences of the prior art as described above,
An object of the present invention is to provide a styrene-based resin composition having excellent impact resistance and rigidity as well as heat resistance.

That is, the present invention comprises (A) mainly 65 to 99% by weight of a styrene polymer having a syndiotactic structure, and (B) a polyfunctional monomer having an alkyl acrylate, an alkyl methacrylate and a conjugated diene type double bond. A particulate elastic body having an average particle size of 0.35 to 4 μm obtained by polymerizing a vinyl monomer in the presence of a polymer obtained by polymerizing one or more monomers selected from the group 35 A styrene-based resin composition is provided, which is characterized by comprising 1 to 1% by weight.

As described above, the resin composition of the present invention contains the component (A) and the component (B) as main components. here,
The component (A) is mainly a styrene-based polymer having a syndiotactic structure. The predominant syndiotactic structure of the styrene-based polymer is that the stereochemical structure is mainly a syndiotactic structure, that is, a carbon-carbon bond. It has a steric structure in which phenyl groups and substituted phenyl groups, which are side chains, are alternately located in opposite directions with respect to the formed main chain, and its tacticity is determined by nuclear magnetic resonance ( ¹³ C- NMR method). ¹³ C
-The tacticity measured by the NMR method can be indicated by the abundance ratio of a plurality of continuous constitutional units, for example, diad in the case of 2, triad in the case of 3, and pentad in the case of 5. The styrene-based polymer having a predominantly syndiotactic structure as referred to in the present invention is usually 75% or more, preferably 85% or more in dyad, or 30% or more, preferably 50% or more in pentad (racemic ventad). Polystyrene, poly (alkyl styrene), poly (halogenated styrene), poly (alkoxy styrene), poly (vinyl benzoate) and their mixtures, or copolymers containing these as main components . In addition, here, as poly (alkylstyrene), there are poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (tert-butylstyrene), and the like, and as poly (halogenated styrene), Examples include poly (chlorostyrene), poly (bromostyrene), and poly (fluorostyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene). Of these, particularly preferred styrene polymers are polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tert-butylstyrene), poly (p-chlorostyrene), poly ( Examples thereof include m-chlorostyrene), poly (p-fluorostyrene), and a copolymer of styrene and p-methylstyrene.

The molecular weight of the styrenic polymer used in the present invention is not limited, but preferably has a weight average molecular weight of 10,000 or more, and most preferably 50,000 or more. Further, the molecular weight distribution is not limited in its width, and various molecular weight distributions can be applied. Such a styrene-based polymer having a predominantly syndiotactic structure is, for example, a styrene-based polymer in an inert hydrocarbon solvent or in the absence of a solvent, using a titanium compound and a condensation product of water and a trialkylaluminum as a catalyst. It can be produced by polymerizing a monomer (a monomer corresponding to the above-mentioned styrene-based polymer) (JP-A-62-187708).

On the other hand, the component (B) of the present invention is one or more monomers selected from the group consisting of a polyfunctional monomer having an alkyl acrylate, an alkyl methacrylate and a conjugated diene type double bond as described above. Is a particle-like elastic body (rubber-like elastic body particle) having an average particle size of 0.35 to 4 μm, preferably 0.4 to 3 μm, obtained by polymerizing a vinyl-based monomer in the presence of a polymer obtained by polymerizing . Here, as alkyl acrylate or alkyl methacrylate,
Those having an alkyl group having 2 to 10 carbon atoms are preferable, and specific examples thereof include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and n-octyl methacrylate.

Examples of the polyfunctional monomer having a conjugated diene double bond include a conjugated diene compound such as butadiene and a compound having a non-conjugated double bond in addition to the conjugated diene double bond in one molecule. To be Examples of such a compound include 1-methyl-2-vinyl-4,6-heptadiene-1.
-Ol; 7-methyl-3-methylene-1,6-octadiene; 1,3,7-octatriene and the like.

The component (B) of the present invention is a vinyl-based monomer in the presence of a polymer (copolymer) obtained by polymerizing one of these monomers alone or copolymerizing two or more of these monomers. A polymer obtained by polymerizing the above-mentioned polymer, that is, a graft copolymer obtained by graft-polymerizing a vinyl-based monomer to the above-mentioned polymer (copolymer). Here, the vinyl monomer is styrene, α
-Aromatic vinyl compounds such as methylstyrene, acrylic acid esters such as methyl acrylate and ethyl acrylate, methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, vinyl acetate , A monomer such as vinyl ester such as vinyl propionate, and one or more of these monomers are polymerized (graft polymerization).

The polymerization reaction at this time can be carried out by various methods such as bulk polymerization, suspension polymerization and emulsion polymerization, and those produced by emulsion polymerization are particularly preferable.

The preferred examples of the component (B) are as follows. That is, first, there is a resin polymer obtained by polymerizing one or more vinyl monomers in the presence of a rubber-like polymer mainly containing alkyl acrylate and / or alkyl methacrylate (alkyl acrylates). . Here, the rubber-like polymer mainly containing alkyl acrylates means 70% by weight or more of the alkyl acrylates and other vinyl-based monomers copolymerizable therewith, such as methyl methacrylate, acrylonitrile, vinyl acetate and styrene. Etc. means a polymer obtained by reacting 30% by weight or less. In this case, a polymer obtained by appropriately adding and reacting a polyfunctional monomer such as divinylbenzene, ethylene dimethacrylate, triallyl cyanurate, and triallyl isocyanurate as a crosslinking agent is also included. Specific examples of the component (B) belonging to the above are those obtained by graft-polymerizing styrene with rubber latex obtained by copolymerizing MAS elastic body (methyl methacrylate and butyl acrylate (commercially available as ROHM & HAS Co., Ltd., trade name EXL-2330, or Kanebuchi Chemical Industry Co., Ltd., trade name M-101)).

In addition, a copolymer obtained by copolymerizing an alkyl acrylate and / or an alkyl methacrylate with a polyfunctional monomer having a conjugated diene type double bond may contain one or more vinyl monomers. There is a resin polymer obtained by polymerization. When obtaining this copolymer, a vinyl-based monomer and a cross-linking agent can be added as in the above case. As a specific example of the component (B) belonging to the above, octyl acrylate and butadiene are used in a mixture of the former: the latter = 7: 3, and styrene and methyl methacrylate are added to a rubber latex obtained by copolymerization to obtain a graft. MAS elastic body such as graft copolymer obtained by polymerization, or rubber latex obtained by copolymerizing methyl methacrylate and butadiene, MBS such as graft copolymer obtained by adding styrene and graft polymerizing Elastic body (Mitsubishi Rayon Co., Ltd. as a commercial product)
Manufactured by Mebrene C-223).

As other elastic bodies, AABS elastic body (rubber latex obtained by copolymerizing butadiene and alkyl acrylate and graft-polymerized with acrylonitrile and styrene added) or SBR elastic body (polybutadiene with styrene graft-polymerized) What you did) and so on.

The component (B) used in the composition of the present invention is a particulate elastic material as described above, but its average particle size is 0.35 to 4 μm.
m, preferably 0.4 to 3 μm. Average particle size is 0.35μ
If it is less than m, the effect of improving the impact resistance of the resulting composition is insufficient, and if it exceeds 4 μm, the surface gloss of the molded article is lowered.

The particle size of the particulate elastic material as the component (B) can be adjusted by adjusting the polymerization conditions. For example, if the polymerization time is lengthened, the particle size tends to increase.

Further, in the composition of the present invention, the above-mentioned (A) component styrene-based polymer having a syndiotactic structure is 65 to 99% by weight, preferably 70 to 95% by weight, and the particulate elastic body (B) component is used. Is blended in a proportion of 35 to 1% by weight, preferably 30 to 5% by weight. Here, the mixing ratio of the particulate elastic material is 35% by weight.
If it exceeds, the rigidity and heat resistance of the resulting composition decrease,
If it is less than 1% by weight, improvement in impact resistance cannot be expected.

The composition of the present invention basically comprises the above-mentioned components (A) and (B), but various inorganic fillers, additives or other synthetic materials can be used unless the object of the present invention is impaired. Resins, elastomers, etc. can be added as required. Here, as the inorganic filler,
For example, glass fiber, glass beads, glass flakes,
Carbon fiber, carbon black, calcium nitrate, calcium carbonate, calcium silicate, titanium oxide, alumina,
Examples thereof include silica, asbestos, talc, clay, mica, quartz powder, and metal powder. Examples of the additives include phosphite-based and phosphate-based antioxidants, benzotriazole-based and benzophenone-based ultraviolet absorbers, aliphatic carboxylate-based and paraffin-based external lubricants, and common additives. Examples include flame retardants, nucleating agents, release agents, antistatic agents, coloring agents, and the like. Other synthetic resins include polyethylene, polypropylene, polystyrene,
Examples thereof include styrene-maleic anhydride copolymer, polycarbonate, polyphenylene sulfide AS resin, ABS resin, polymethyl methacrylate, and polyphenylene ether. As the elastomer, in addition to those having an average particle size of less than 0.35 μm among the elastic bodies, a part or all of natural rubber, polybutadiene, polyisoprene, polyisobutylene, isobutylene-isoprene rubber, and styrene-butadiene rubber are hydrogenated. Examples of the rubber include ethylene rubber, ethylene-propylene rubber, acrylic rubber, urethane rubber, and silicone rubber.

The resin composition of the present invention can be obtained by mixing the above-mentioned components (A) and (B) and, if necessary, various desired components, and kneading at an appropriate temperature, for example, a temperature equal to or higher than the melting point of the component (A). it can. The compounding and kneading at this time may be performed by a usual method. Specifically, kneader, mixing roll,
A melt-kneading method using a extruder, a Banbury mixer, a Henschel mixer, a kneading roll, or a solution blending method may be used. The molding can be performed by various methods such as extrusion molding, injection molding, blow molding and press molding.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Reference Example 1 (Production of polystyrene having mainly syndiotactic structure) Toluene 2 as a reaction solvent, 5 mmol of tetraethoxy titanium as a catalyst component and 500 mmol of methylaluminoxane as an aluminum atom were put in a reaction vessel, and styrene 15 was added at 55 ° C. In addition, a polymerization reaction was carried out for 4 hours.

After the reaction, the product was washed with a mixed solution of hydrochloric acid and methanol to decompose and remove the catalyst component. Then, by drying, 2.5 kg of a styrene-based polymer (polystyrene) was obtained. Next, this polymer was subjected to Soxhlet extraction using methyl ethyl ketone as a solvent to obtain an extraction residue of 97% by weight.
The weight average molecular weight of this extraction residue was 400,000. In addition, ¹³ C-NMR analysis (solvent: 1,2-dichlorobenzene) of this polymer showed absorption at 145.35 ppm due to the syndiotactic structure. Syndiotacticity was 98%.

Reference Example 2 A commercially available particulate elastic material was dispersed in acetone or methanol, sprayed and dropped on a micromesh for electron microscope observation, and then observed with an electron microscope to determine the average particle diameter. The results are shown below.

(1) MAS elastic body (brand name KM-330, manufactured by Rohm & Haas) …… 0.3 μm (2) MAS elastic body (brand name EXL-2330, manufactured by Rohm & Haas) …… 0.5 μm (3) MAS Elastic body (Brand name M-101, manufactured by Kanegafuchi Chemical Industry Co., Ltd.) …… 0.5 μm (4) MBS elastic body (Brand name C-223, Mitsubishi Rayon Co., Ltd.)
Made) …… 0.4 μm (5) MABS elastic body (brand name HIA-15, Mitsubishi Rayon Co., Ltd.)
Made) …… 0.1 μm (6) MAS elastic body (trade name W-529, made by Kureha Chemical Co., Ltd.)
0.2 μm Example 1 90% of the styrene polymer having a syndiotactic structure obtained in Reference Example 1 and a particulate MAS elastic body (trade name EXL-233)
0, manufactured by Rohm & Haas Co., Ltd.), and PTBBA-Al (p-tert.
-Butyl aluminum benzoate) 1 part by weight, (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (trade name PEP) as an antioxidant
-36, Adeka Argus Co., Ltd.) 0.7 part by weight and 2,6-di-tert-butyl-4-methylphenol (trade name Sumilizer BHT, Sumitomo Chemical Co., Ltd.) 0.1 part by weight are added, and the twin-screw kneading extrusion is performed. The mixture was kneaded and tableted by a machine.

Test pieces were prepared from the obtained pellets by injection molding, and Izod impact strength (with notch) (according to JIS K 7110), tensile elastic modulus (according to JIS K 7113), heat distortion temperature (Vicat softening point) (JIS (According to K 7206) was measured.
The results are shown in Table 1.

Further, an ultrathin section for electron microscope observation was cut out from the Izod test piece and observed by a phase contrast method, and the elastic body (rubber) particle size was determined to be 0.5 μm. The particle size of the elastic body was determined by the following average particle size formula.

(D: average particle size, di: diameter of each particle, n: number of particles) The average particle size was calculated with n = 200.

Example 2 80% by weight of the syndiotactic styrene polymer obtained in Reference Example 1 was used, and MA was used as a particulate elastic body.
2 S elastic body (trade name: M-101, manufactured by Kanegafuchi Chemical Co., Ltd.)
The same operation as in Example 1 was performed except that 0% by weight was used. The results are shown in Table 1.

The rubber particle size obtained from the ultrathin section in the same manner as in Example 1 was 0.5 μm.

Example 3 70% by weight of the styrene polymer having a syndiotactic structure obtained in Reference Example 1 was used, and MB was used as a particulate elastic body.
30 S elastic body (trade name C-223, manufactured by Mitsubishi Rayon Co., Ltd.)
The same operation as in Example 1 was carried out except that the use was made by weight. The results are shown in Table 1.

After the ultrathin section was dyed and fixed with osmic acid, the obtained rubber particle size was 0.4 μm.

Example 4 80% by weight of the styrene polymer having a syndiotactic structure obtained in Reference Example 1 was used, and MB was used as a particulate elastic body.
5% by weight of S elastic body (trade name C-223, Mitsubishi Rayon Co., Ltd.) and MABS (trade name HIA-15, Mitsubishi Rayon Co., Ltd.) 15
The same operation as in Example 1 was performed except that the content was changed to wt%. The results are shown in Table 1.

The obtained Izod test piece was made to be a solvent in hot xylene, and then the gel portion was filtered and dried, dispersed with acetone, and observed with an electron microscope. As a result, particles having a particle size of 0.4 μm and particles having a particle size of 0.1 μm were observed, and the area fraction in the observation visual field was about 1: 3.

Example 5 68% by weight of the syndiotactic styrene polymer obtained in Reference Example 1 was used, and MA was used as a particulate elastic body.
S elastic body (product name M-101, manufactured by Kanegafuchi Chemical Industry Co., Ltd.) 2
% By weight and MAS elastic (trade name: W-529, Kureha Chemical Co., Ltd.)
The same operation as in Example 1 was performed except that the amount was 30% by weight. The results are shown in Table 1.

Electron microscope observation after gel extraction revealed a particle size of 0.5μ
m particles and 0.2 μm particles were observed, and the area fraction in the observation visual field was about 1:15.

Example 6 The styrene-based polymer having the syndiotactic structure obtained in Reference Example 1 was used in an amount of 85% by weight, and MB was used as a particulate elastic body.
Same as Example 1 except that S elastic body (trade name C-223, manufactured by Mitsubishi Rayon Co., Ltd.) 10% by weight and SBS elastic body (trade name TR-1102, manufactured by Shell Chemical Co., Ltd.) 5% by weight. The operation was performed. The results are shown in Table 1.

When the gel was observed with an electron microscope, particles having a particle size of 0.4 μm were observed.

Comparative Example 1 70% by weight of the styrene-based polymer having the syndiotactic structure obtained in Reference Example 1 was used, and MA was used as a particulate elastic body.
30% by weight of BS (product name HIA-15, manufactured by Mitsubishi Rayon Co., Ltd.)
The same operation as in Example 1 was performed, except that The results are shown in Table 1.

Comparative Example 2 50% by weight of the styrene polymer having the syndiotactic structure obtained in Reference Example 1 was used, and MA was used as a particulate elastic body.
50 S elastic body (trade name EXL-2330, manufactured by Rohm & Haas)
The same operation as in Example 1 was carried out except that the content was changed to% by weight, but it was too soft to be deformed during molding and could not be released.

Comparative Example 3 The styrene-based polymer having the syndiotactic structure obtained in Reference Example 1 was 80% by weight, and the elastic body was amorphous.
The same operation as in Example 1 was performed except that EPR (trade name EP-02P, manufactured by JSR) was set to 20 parts by weight. The results are shown in Table 1.

Comparative Example 4 80% by weight of the syndiotactic styrene-based polymer obtained in Reference Example 1 was used, and MA was used as a particulate elastic body.
The same operation as in Example 1 was performed except that the S elastic body (trade name: KM-330, manufactured by Rohm & Haas Co.) was set to 20% by weight. The results are shown in Table 1.

Example 7 50 parts by weight of polybutadiene latex having an average particle size of 1.0 μm, 20 parts by weight of styrene, 0.1 part by weight of potassium rosinate,
0.1 parts by weight of potassium hydroxide, 0.2 parts by weight of sodium pyrophosphate, 0.3 parts by weight of dextrose, 0.01 parts by weight of ferrous sulfate, and 150 parts by weight of water were charged into a reactor equipped with a stirrer, and after nitrogen replacement, the temperature was raised to 70 ° C. Then, 0.2 part by weight of cumene hydroperoxide was added as a radical polymerization catalyst, and a polymerization reaction was carried out for 1 hour.

Thereafter, a separately prepared emulsion consisting of 30 parts by weight of styrene, 1.5 parts by weight of potassium rosinate, 0.1 part by weight of potassium hydroxide, 0.2 part by weight of cumene hydroperoxide, and 50 parts by weight of water was added to the polymerization system over 3 hours. .

Then, the reaction was continued for an additional 1 hour while maintaining the jacket temperature at 70 ° C. to complete the polymerization.

The produced latex contains 2,6-di-t as an antioxidant.
1.0 part by weight of ert-butyl-p-cresol and 2.0 parts by weight of sulfuric acid were added, and the mixture was heated and coagulated, filtered, washed with water, and dried to obtain a particulate elastic body (SBR). The particle size was 1.2 μm.

10% by weight of this particulate elastic body and 90% by weight of the styrene-based polymer having a syndiotactic structure obtained in Reference Example 1, and thereafter the same operation as in Example 1 was performed. The results are shown in Table 1.

Example 8 70 parts by weight of a polybutadiene latex having an average particle diameter of 2.4 μm, 200 parts by weight of water and 0.3 parts by weight of potassium persulfate were charged, and the mixture was kept at 70 ° C. and 15 parts by weight of methyl methacrylate was added dropwise over 30 minutes for polymerization. After the completion of dropping,
The temperature was kept for 1 hour to complete the polymerization.

Next, 15 parts by weight of styrene was added dropwise over 30 minutes to advance the polymerization, and the polymerization was held for 60 minutes to complete the polymerization.

When the obtained graft copolymer latex was observed with an electron microscope, the average particle diameter was 2.5 μm.

Subsequently, this graft copolymer latex was added to an aqueous solution of aluminum chloride, salted out and coagulated, filtered, washed with water and dried to obtain a particulate elastic body.

10% by weight of this particulate elastic body and 90% by weight of the styrene-based polymer having a syndiotactic structure obtained in Reference Example 1, and thereafter the same operation as in Example 1 was performed. The results are shown in Table 1.

EFFECT OF THE INVENTION The styrene resin composition of the present invention has excellent heat resistance and mechanical properties such as impact resistance and rigidity.

Therefore, the styrene resin composition of the present invention is expected to be widely and effectively used as an industrial material required to have heat resistance and various mechanical properties, particularly a material for injection molding or extrusion molding.

Claims (1)

(57) [Claims] 1. A styrene-based polymer having 65 to 99% by weight of (A) a syndiotactic structure, and (B) an alkyl acrylate, an alkyl methacrylate, and a polyfunctional monomer having a conjugated diene type double bond. A particulate elastic body having an average particle size of 0.35 to 4 μm obtained by polymerizing a vinyl monomer in the presence of a polymer obtained by polymerizing one or more monomers selected from the group 35 A styrene-based resin composition characterized by comprising 1 to 1% by weight.