JP2676261B2 - Rubber modified styrenic resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel rubber-modified styrene resin composition. More specifically, the present invention has high impact strength, and excellent gloss and rigidity,
It has an excellent balance of physical properties, such as OA equipment, home appliances,
The present invention relates to a rubber-modified styrene-based resin composition that is preferably used as a material for sheets and the like.

BACKGROUND ART Conventionally, in order to improve the impact resistance of styrene resin,
By blending a rubber-like polymer with polystyrene, or by polymerizing styrene in the presence of a rubber-like polymer, styrene is partially graft-polymerized to the rubber-like polymer, and the rest of styrene becomes polystyrene. Industrially, a so-called rubber-modified polystyrene resin composition is substantially mixed with a rubbery polymer / styrene graft copolymer and polystyrene.

In such a rubber-modified polystyrene resin composition, the rubber-like polymer is usually dispersed in the styrene-based polymer in the form of particles, and the size of the particles and the impact resistance, rigidity, and gloss are close to each other. Having a relationship is well known. That is, the resistance and gloss are better as the particles of the rubber-like polymer are smaller, but on the other hand, the impact resistance is decreased in proportion to the size of the particles of the rubber-like polymer,
Below a certain limit, the effect of improving impact resistance is substantially lost.

In a conventional rubber-modified polystyrene resin composition,
In order to obtain the desired impact resistance, the rubbery polymer is dispersed in the polystyrene resin phase as particles having a particle diameter of 1 μm or more, usually in the range of 1 to 10 μm. However, there is a problem that the use of the apparatus cannot be avoided.

By the way, in high impact polystyrene (HIPS), it is known that dispersed particles of a rubber-like polymer have an occlusion structure ["Die Angevandte Makromoleku
lare Chemie) "Volume 58/59, pages 175-198 (1977
However, detailed examination of the microstructure of dispersed particles has not been made. As a styrene resin composition in which dispersed particles of such a rubber-like polymer have an occlusion structure, a styrene-butadiene block copolymer having a particle size of 0.1 to 0.6 is used.
Particles having an occlusion structure in which 80% or more of the particles have a symmetry plane and are dispersed in polystyrene have been proposed (West German Patent Publication No. 3,345,377).
No.), but the impact resistance is not sufficient.

The present invention overcomes the drawbacks of the conventional rubber-modified styrenic resin composition, has a high impact strength, and has excellent gloss and rigidity, and has a good balance of physical properties. It is made for the purpose of providing.

The present inventors have conducted extensive studies to develop a styrene-based resin composition having an excellent balance of physical properties such as impact resistance, gloss, and rigidity, and as a result, have identified a styrene-based polymer and a rubber-like polymer as specific components. Contained in a proportion, and the rubber-like polymer is dispersed in the styrene-based polymer phase as particles having a specific particle size and particle size distribution having an occlusion structure having a plane of symmetry, and the gel content and swelling index are It has been found that compositions within the specified range may be suitable for said purpose. Further, among the above compositions, the present inventors have found that when the thickness of the rubber-like polymer phase, the area average particle diameter (diameter) of the rubber-like polymer and the volume fraction of the rubber-like polymer satisfy a specific relationship. It has been found that it has particularly excellent physical properties. The present invention has been completed based on these findings.

DISCLOSURE OF THE INVENTION That is, the present invention provides a styrene-based monomer,
(A) obtained by polymerizing in the presence of a rubber-like polymer composed of a mixture of butadiene-based block copolymer rubber (SB type) or styrene-butadiene-based block copolymer rubber (SB type) and polybutadiene rubber. Styrene polymer 70〜
A rubber-modified styrene resin composition comprising 92% by weight and (B) 30 to 8% by weight of a rubbery polymer, wherein particles of the rubbery polymer are dispersed in a continuous phase comprising the styrene polymer. 70% or more of the number of particles of the rubber-like polymer has an occlusion structure containing 5 or less inclusion occlusions, and the particles of the rubber-like polymer having one inclusion occlusion have an occlusion structure. 50 out of
% Or more, the outer shape of the particles of the rubber-like polymer having one inclusion occlusion has a symmetric surface, the area average particle diameter is 0.1 to 0.7 μm, and the area average particle with respect to the number average particle diameter. Particles having a diameter ratio of 1.0 to 2.5 are dispersed in the styrene polymer, and the gel amount is 1.1 to 4.0 weight ratio with respect to the rubber-like polymer, and the swelling index is 5 to 20. and, dispersed particles of the rubber-like polymer, relationship _{K = φ R {1 - [} (D S / 2) -λ) / (D S / 2)] 3} -1 (φ R in the formula is The volume fraction of the rubber-like polymer in the composition is shown, D _S is the area average particle diameter (diameter) of the rubber-like polymer, and λ is the thickness of the rubber-like polymer phase and is 0.10 μm or less. ) K is 0.18 or more, the rubber-modified styrene resin composition is provided.

The rubber-modified styrenic resin composition of the present invention comprises a rubber-like polymer dispersed in a styrenic polymer as particles having a specific particle size and a particle size distribution having an occlusion structure having a symmetry plane, and Since it has a microstructure, it has characteristics such as high impact strength, excellent gloss and rigidity, and excellent physical property balance.

Furthermore, when the thickness of the rubber-like polymer phase, the diameter of the rubber-like polymer particles, in other words, the area average particle diameter (diameter) of the rubber-like polymer and the volume fraction of the rubber-like polymer satisfy a specific relationship. Further, it has more excellent physical properties and further has a good falling weight strength.

BEST MODE FOR CARRYING OUT THE INVENTION The styrene-based polymer as the component (A) in the composition of the present invention may be a styrene homopolymer, or a copolymer of styrene and a copolymerizable monomer. May be Examples of the copolymerizable monomer include aromatic monovinyl compounds such as α-methylstyrene, vinyltoluene, vinylethylbenzene, vinylxylene, pt-butylstyrene, α-methyl-p-methylstyrene, and vinylnaphthalene. , Acrylonitrile, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, maleic anhydride, phenylmaleimide and the like. These monomers may be used alone or in combination of two or more, but usually 50% by weight or less, preferably 40% by weight or less, based on all monomers containing styrene. Used in proportion.

On the other hand, the rubber-like polymer as the component (B) is composed of a styrene-butadiene block copolymer rubber (SB type) or a mixture of a styrene-butadiene block copolymer rubber (SB type) and a polybutadiene rubber. is there. When the styrene-butadiene block copolymer rubber (SB type) and polybutadiene rubber are used together, the former / the latter = 10
The ratio is / 0 to 6/4 (polymerization ratio).

The styrene-butadiene block copolymer rubber (SB type) has a molecular weight in the range of 50,000 to 500,000, and the content of the polymer block formed by styrenes is in the range of 10 to 60% by weight. Those are particularly preferable.
If the molecular weight is less than 50,000, the impact resistance is not sufficient, and if it exceeds 500,000, the fluidity at the time of molding is deteriorated, which is not preferable. Further, if the content of the polymer block formed of styrenes is less than 10% by weight, the gloss is inferior, and if it exceeds 60% by weight, the impact resistance tends to decrease. The styrene-butadiene block copolymer rubber (SB type) has a molecular weight of 50,000 to 1,000,00
You may mix and use about 0 polybutadiene rubber suitably.

The molecular weight of this rubber-like polymer is the weight average molecular weight in terms of polystyrene by GPC.

In the styrene resin composition of the present invention, the rubber-like polymer as the component (B) has an occlusion structure having a symmetry plane and has an area average particle diameter (diameter) of 0.1 to 0.7 μm.
m, preferably 0.2-0.6 μm, number average particle diameter (diameter)
The ratio of the area average particle diameter to 1.0 to 2.5, preferably
It is necessary that the particles of 1.0 to 1.8 are dispersed in the styrene polymer as the component (A).

If the area average particle diameter is less than 0.1 μm, the impact resistance is not sufficient, and if it exceeds 0.7 μm, the gloss tends to decrease. In addition, the area average particle diameter with respect to the number average particle diameter is
If it exceeds 2.5, the gloss tends to decrease.

Further, the dispersed particles of the rubber-like polymer need to have an occlusion structure having a plane of symmetry. In other words, the rubber-modified styrenic resin composition of the present invention is one in which the particles of the rubber-like polymer are dispersed in the continuous phase of the styrene-based polymer, but in one particle of the rubber-like polymer. ,
The core has a styrenic polymer, and the shell has an occlusion structure containing 5 or less inclusion occlusions made of a rubbery polymer, and the inclusion occlusion is 1
The individual rubber-like polymer particles account for 50% or more of the occlusion structure, and the inclusion occlusion is 1
It is necessary that the outer shape of the individual rubber-like polymer particles has a plane of symmetry.

In the present invention, 70% or more of the number of particles of the rubber-like polymer needs to have an occlusion structure containing 5 or less inclusion occlusions as described above, and when particles such as a salami structure are mixed in an amount of 30% or more. , There is a possibility that good gloss may not be obtained.

Therefore, in the present invention, a high impact polystyrene (HIPS) having a normal salami structure containing six or more inclusion occlusions can be blended if the number of rubber particles is less than 30%.

Further, in the composition of the present invention, the rubber-like polymer particles need to have a specific microstructure. That is, the gel amount needs to be in the range of 1.1 to 4.0 weight ratio, preferably 1.4 to 3.6 weight ratio with respect to the rubbery polymer, and its swelling index is 5 to 20, preferably 7 to 18. Must be in range. If the gel amount is less than 1.1 weight ratio, the impact resistance is not sufficient, and if it exceeds 4.0 weight ratio, the gloss may decrease. If the swelling index is outside the above range, the impact strength tends to decrease.

In the composition of the present invention, the styrenic polymer of the component (A) and the rubbery polymer of the component (B) are each 70%.
-92% by weight and 30-8% by weight, preferably 72-90% 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 the impact resistance is not sufficiently exhibited, and if it exceeds 30% by weight, the gloss and the fluidity tend to decrease.

Further, in the composition of the present invention, the thickness (λ) of the rubber-like polymer phase is preferably 0.10 μm or less. In order to make the thickness (λ) of the rubber-like polymer phase 0.10 μm or more,
It is necessary to increase the molecular weight of the rubber-like polymer used (for example, when using styrene-butadiene block copolymer rubber (SB type), it is necessary to make the molecular weight of the butadiene polymer block part about 800,000 or more. is there).

When the rubber-modified styrene resin composition of the present invention is produced using such a high molecular weight rubber-like polymer, the viscosity of the polymerization reaction solution becomes extremely high, which is not preferable. The thickness (λ) of the rubber-like polymer phase is preferably 0.005 to 0.07 μm.

Furthermore, a relational expression K having factors such as the volume fraction (φ _R ) of the rubber-like polymer, the area average particle diameter (diameter) (D _S ) of the rubber-like polymer, and the thickness (λ) of the rubber-like polymer phase = Φ _R {1-[((D _S / 2) −λ) / (D _S / 2)] ³ } ⁻¹ (1) has a K of 0.18 or more, preferably 0.20 or more, more preferably 0.22. It is necessary to be above. If the K value is less than 0.18, the falling weight impact strength is insufficient, and is not necessarily sufficient for a material such as a housing for a large television.

The volume fraction of the rubber-like polymer (phi _R) of the formula _{φ R = {[(1 /} W R) -1] (ρ R ρ PS) +1} can be obtained by ^-1 ... (II).

Here, ρ _R is the specific gravity of the rubbery polymer, and 0.90 is used. Further, ρ _PS is the specific gravity of the styrene-based polymer, and 1.05 is used. Furthermore W _R is the polymerization fraction of the rubber-like polymer contained in the composition, wherein _{W R = W D (1-} S) / [(1-W D) x + W D] ... (III) Can be obtained by

Area average particle diameter of the rubber-like polymer (diameter) (D _S) and (D _n) may be obtained as follows. That is, pellets of a rubber-modified styrenic resin composition having a small orientation were treated with an aqueous 3 wt% osmium tetroxide solution and thinned with an ultramicrotome, and a transmission electron microscope image of this was obtained. The diameter (D) in the major axis direction of the rubber-like polymer particles was measured for 1000 particles, and the area average value was calculated according to the following equation
The area average particle size (diameter) (D _S ) and (D _n ) of the rubbery polymer is obtained.

(N is the number of rubber-like polymer particles having a diameter D) Further, the thickness (λ) of the rubber-like polymer phase was determined by obtaining a transmission electron microscope image in the same manner as described above. The rubbery polymer phase exists only at the periphery, that is, the thickness λi of the rubbery polymer phase of the rubbery polymer particles cut near the center is measured for 100 particles, and the number average value is calculated. It is obtained by obtaining according to the following equation.

λ = (λ ₁ + λ ₂ + λ ₃ +... + λ ₁₀₀ ) / 100 Similarly, a transmission electron microscope image was obtained, and the ratio of the number of occlusion-structured particles to 1,000 randomly extracted particles was determined. The ratio of occlusion structure particles was evaluated.

The rubber-modified styrene-based resin composition of the present invention comprises a styrene-based monomer (styrene or a monomer copolymerizable with styrene), a styrene-butadiene-based block copolymer rubber (SB type), or styrene. It can be adjusted by polymerizing in the presence of a rubber-like polymer composed of a butadiene block copolymer rubber (SB type) and a polybutadiene rubber. The polymerization method is not particularly limited, and a conventionally used method such as an emulsion polymerization method,
Bulk polymerization method, solution polymerization method, suspension polymerization method, or bulk-
A multi-step polymerization method such as a suspension two-step polymerization method can be used.

Next, an example of a preferred method for producing the resin composition of the present invention by the bulk-suspension two-stage polymerization method will be described. First, styrene or a mixture of a monomer copolymerizable with styrene is mixed with a rubber-like polymer. Add coalescence and heat to dissolve as needed. This dissolution is preferably performed as uniformly as possible.

Next, to this solution, a molecular weight regulator (chain transfer agent) such as an alkyl mercaptan and a polymerization initiator such as an organic peroxide used as needed are added, and while heating to a temperature of about 70 to 150 ° C., Preliminary polymerization by a bulk polymerization method is performed under stirring until the degree of polymerization reaches 10 to 60%. In this prepolymerization step, the rubbery polymer is dispersed into particles by stirring.

Next, the prepolymerized solution is suspended in an aqueous phase using tribasic calcium phosphate, polyvinyl alcohol or the like as a suspending agent, and suspension polymerization (main polymerization) is usually performed until the degree of polymerization approaches 100%. If necessary, after this main polymerization step,
Further heating may be continued.

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

Further, as a polymerization initiator used as desired,
For example, peroxyketals such as 1,1-bis (t-butylperoxy) cyclohexane and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, dicumyl peroxide, di-t-butyl peroxide, 2,
Dialkyl peroxides such as 5-dimethyl-2,5-di (t-butylperoxy) hexane, diallyl peroxides such as benzoyl peroxide and m-toluoyl peroxide
Organic peroxides such as peroxides, peroxydicarbonates such as dimyristyl peroxydicarbonate, peroxyesters such as t-butylperoxyisopropyl carbonate, ketone peroxides such as cyclohexanone peroxide, and hydroperoxides such as p-menthane hydroperoxide. You can list things.

The particle size, particle size distribution, and particle structure of the rubber-like polymer can be controlled by controlling the stirring speed and the amount of the molecular weight regulator used. It can be controlled by the reaction temperature, reaction time and the like.

Further, the thickness λ of the rubber-like polymer phase is controlled by changing the molecular weight of the butadiene polymer block portion when, for example, a styrene-butadiene block copolymer rubber (SB type) is used as the rubber-like polymer. can do. That is, when the molecular weight of the butadiene polymer block is reduced, λ is decreased, and when the molecular weight is increased, λ is increased.

Next, the slurry thus obtained is treated by an ordinary means to take out a bead-like reaction product, dried, and then pelletized according to a conventional method to give the rubber-modified styrene resin composition of the present invention. The thing is obtained. The molecular weight of the matrix portion of the rubber-modified styrene resin composition thus obtained is 100,000 to 300,000, preferably 130,
Advantageously, it is in the range of 000 to 280,000. If the molecular weight is less than 100,000, impact resistance is poor, and if it exceeds 300,000, fluidity during molding becomes insufficient.

The rubber-modified styrenic resin composition of the present invention may optionally contain various additives that are commonly used, such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylene bis-stearamide. Such as lubricants, organic polysiloxane, mineral oil, or 2,6-di-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, tri (2,4-di-t-butylphenyl) phosphite, 4,4'-butylidene bis (3-methyl-6-t-butylphenyl-) Phosphorus-based antioxidants such as di-tridecyl) phosphite, other ultraviolet absorbers, flame retardants, antistatic agents, release agents, plasticizers, dyes, pigments, and various fillers can be added. Further, other polymers, for example, polyphenylene ether and the like can be blended.

The styrene-based resin composition of the present invention thus obtained has an excellent balance of physical properties such as impact resistance, gloss, and rigidity, and is suitably used as a material for OA equipment, home electric appliances, sheets, and the like.

[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.

The physical properties of the molded product and the properties of the composition were determined by the following methods.

(1) Gel amount and swelling index Sample Wc (g) was dissolved in toluene,
After centrifugation for minutes, the supernatant was decanted to determine the amount of swollen insoluble components Ws (g), and then the swollen insoluble components were vacuum-dried at 60 ° C. for 24 hours to obtain a dry insoluble component Wg.
(G) is obtained.

Gel amount (wt%) = (Wg / Wc) × 100 Swelling index = Ws / Wg (2) Izod impact value It was determined according to JIS K-7110 (with 23 ° C. notch).

(3) Glossiness Measured according to JIS K-7105.

(4) Flexural Modulus Obtained according to ASTM D-790.

(5) Melt index [MI] Obtained according to JSO R-1133.

(6) Drop weight impact strength Load is applied at the center of the board width (70 mm) at a point 125 mm from the gate position (end of the formed board) of an injection-molded board of 270 x 70 x 3 mm.
Rheometrics automatic drop weight impact tester RD under the conditions of 3.76 kg, speed 3.5 m / sec, sample fixing part hole diameter 2 inch, temperature 23 ℃
The weight was measured using T5000, and the energy up to the point at which the force suddenly decreased was first determined from the force-displacement curve, and was taken as the falling weight impact strength.

Reference Example 1 An autoclave having an internal volume of 5 l was charged with a weight average molecular weight of 330,000,
SB block copolymer with styrene content of 30% by weight 36
Add 2 g, styrene 3000 g and n-dodecyl mercaptan 1 g as a chain transfer agent, and stir at 400 rpm with 130
The reaction was carried out at ℃ for 4 hours.

Then, in a 10 l autoclave, the reaction mixture 3000
g, water 3000g, polyvinyl alcohol as suspension stabilizer
10g, 6g of benzoyl peroxide and 3g of dicumyl peroxide as polymerization initiators were added, stirred at 300rpm, heated from 80 ℃ to 140 ℃ at a heating rate of 30 ℃ / hr, and reacted at that temperature for further 4 hours. Then, beads of the rubber-modified polystyrene composition were obtained.

Next, the beads of the obtained composition were pelletized by a single screw extruder at 220 ° C., and then molded.

The measurement results of the physical properties of the obtained molded product and the properties of the composition are shown in Table 1.

Reference Example 2 In Reference Example 1, the amount of SB block copolymer charged was changed to
It was carried out in the same manner as in Reference Example 1 except that the stirring speed in bulk polymerization was 500 rpm and the stirring speed was 448 g. The results are shown in Table 1.

Reference Example 3 In Reference Example 1, 319 g of an SB block copolymer having a molecular weight of 200,000 and a styrene unit content of 30% by weight is used.
It was carried out in the same manner as in Reference Example 1 except that the stirring rotation speed in bulk polymerization was 500 rpm. The results are shown in Table 1.

Example 1 In Reference Example 1, the amount of SB block copolymer charged was changed to
It was carried out in the same manner as in Reference Example 1 except that 377 g was used and the stirring rotation speed in bulk polymerization was 300 rpm. The results are shown in Table 1.

Example 2 In Reference Example 1, the amount of SB block copolymer charged was changed to
It carried out like Example 1 except having set it as 636 g. The results are shown in Table 1.

Example 3 In Reference Example 1, as the SB block copolymer, 659 was used as an SB block copolymer manufactured by Nippon Zeon Co., Ltd. (molecular weight 100,000, styrene unit content 22.6% by weight, trade name: ZLS-01).
g was used, and the same procedure as in Reference Example 1 was performed except that the stirring rotation speed in bulk polymerization was 300 rpm. First result
It is shown in the table.

Example 4 In Example 3, the amount of SB block copolymer charged was changed to
The procedure of Example 3 was repeated, except that the amount was 1167 g. The results are shown in Table 1.

Example 5 In Example 3, the amount of the SB block copolymer charged was changed to
Example 3 was carried out in the same manner as in Example 3 except that 333 g was used. The results are shown in Table 1.

Example 6 The amount of dicumyl peroxide in Example 3 was changed to
The same procedure as in Example 3 was carried out except that the amount was 10 g. The results are shown in Table 1.

Example 7 In Example 3, the amount of dicumyl peroxide was changed.
The same procedure as in Example 3 was carried out except that the amount was 2 g.
The results are shown in Table 1.

Example 8 In Example 3, the stirring speed in bulk polymerization was 500 rpm.
The same procedure as in Example 3 was carried out except that The results are shown in Table 1.

Example 10 In Reference Example 3, the amount of the SB block copolymer charged was 52%.
It was carried out in the same manner as in Reference Example 3 except that the amount of stirring was 7 g, and the stirring rotation speed in bulk polymerization was 400 rpm. First result
It is shown in the table.

Example 11 In Example 10, the stirring rotation speed in bulk polymerization is 500 rpm.
The same procedure as in Example 10 was carried out except that The results are shown in Table 1.

Example 12 In Reference Example 1, 752 g of an SB block copolymer having a molecular weight of 100,000 and a styrene unit content of 30% by weight
It was carried out in the same manner as in Reference Example 1 except that the stirring rotation speed in bulk polymerization was 500 rpm. The results are shown in Table 1.

Example 13 In Example 1, 377 g of the SB block copolymer was further added to polybutadiene (manufactured by Ube Industries, Ltd., trade name: BR15HB,
The procedure of Example 1 was repeated except that 94 g of a molecular weight of 550,000) was added. The results are shown in Table 1.

Example 14 Example 14 was carried out in the same manner as Example 13 except that the addition amount of polybutadiene was 162 g. The results are shown in Table 1.

Example 15 In an autoclave having an internal volume of 5 liters, SB block copolymer [manufactured by Nippon Zeon Co., Ltd., trade name: ZLS-01, content of styrene unit 22.6% by weight, molecular weight 100,000] 704 g, styrene 3000 g
Then, 1 g of n-dodecyl mercaptan as a chain transfer agent was added, and the mixture was reacted at 130 ° C. for 4 hours while stirring at 300 rpm to obtain a prepolymer (I).

Similarly, a prepolymer (II) was obtained using 409 g of polybutadiene (trade name: NF35AS manufactured by Asahi Kasei Co., Ltd.) and 0.5 g of n-dodecyl mercaptan. (As for the rubber structure, beads were synthesized under the following suspension polymerization conditions and the occlusion of 0.4 μm and the salami structure of 1.2 μm were confirmed by an electron microscope.) Then, the prepolymer obtained in 10 l of autoclave (I) 2550 g, prepolymer (II) 450 g, water 3000 g,
While adding 10g of polyvinyl alcohol as a suspension stabilizer, 6g of benzoyl peroxide and 3g of dicumyl peroxide as a polymerization initiator, and stirring at 500rpm, the temperature was raised from 80 ° C to 140 ° C at a heating rate of 30 ° C / hour, and further 4 The reaction was carried out for a time to obtain beads of rubber-modified polystyrene. (It was confirmed with an electron microscope that the occlusion was 0.4 μm and the salami was 1.2 μm.) The obtained beads were pelletized with a single screw extruder at 220 ° C. and then molded.

The measurement results of the physical properties of the obtained molded product and the properties of the composition are shown in Table 1.

Example 16 Example 16 was carried out in the same manner as Example 15 except that the amount of n-dodecyl mercaptan used when preparing the prepolymer (II) was changed to 1 g. The results are shown in Table 1.

Comparative Example 1 In Reference Example 3, the amount of SB block copolymer charged was changed to
It was carried out in the same manner as in Reference Example 3 except that the amount of stirring was 205 g and the stirring rotation speed in bulk polymerization was 400 rpm. The results are shown in Table 2.

Comparative Example 2 In Example 12, the amount of SB block copolymer charged was changed to
Example 12 was carried out in the same manner as in Example 12 except that 242 g was used. The results are shown in Table 2.

Comparative Example 3 In Example 3, the amount of the SB block copolymer charged was changed to
The same procedure as in Example 3 was carried out except that the amount was 191 g. The results are shown in Table 2.

Comparative Example 4 In Example 3, the amount of the SB block copolymer charged was changed to
The same procedure as in Example 3 was carried out except that 1477 g was used. The results are shown in Table 2.

Comparative Example 5 The procedure of Example 3 was repeated, except that the amount of dicumyl peroxide used as a polymerization initiator was changed to 0.5 g. The results are shown in Table 2.

Comparative Example 6 In Example 3, as a polymerization initiator, 6 g of di-t-butyl peroxide was used instead of 6 g of benzoyl peroxide.
Was used and the amount of dicumyl peroxide was 10 g, and the same procedure as in Example 3 was carried out. The results are shown in Table 2.

Comparative Example 7 In Example 3, the stirring speed in bulk polymerization was 800 rpm.
The same procedure as in Example 3 was carried out except that The results are shown in Table 2.

Comparative Example 8 In Example 3, the stirring rotation speed in bulk polymerization was 100 rpm.
The same procedure as in Example 3 was carried out except that The results are shown in Table 2.

Comparative Example 9 The procedure of Example 14 was repeated, except that the amount of polybutadiene added was 262 g. The results are shown in Table 2.

INDUSTRIAL APPLICABILITY The rubber-modified styrene resin composition of the present invention has an excellent physical property balance, and can be effectively used as a material for, for example, OA equipment, home electric appliances, sheets and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Nakamura 1 Anesaki Kaigan, Ichihara City, Chiba Prefecture Idemitsu Petrochemical Co., Ltd. (56) References JP 63-102769 (JP, A) JP 63-185268 (JP, A) JP 62-65462 (JP, A) JP 63-112646 (JP, A) JP-A-60-245614 (JP, A) JP-A-60-130614 (JP, A) JP-B-62-34773 (JP, B2)

Claims (1)

(57) [Claims] 1. A rubber-like polymer comprising a styrene-based monomer and a mixture of styrene-butadiene-based block copolymer rubber (SB type) or styrene-butadiene-based block copolymer rubber (SB type) and polybutadiene rubber. 70 to 92% by weight of (A) styrenic polymer obtained by polymerizing in the presence of coalescence
And (B) a rubber-like polymer in an amount of 30 to 8% by weight, wherein particles of the rubber-like polymer are dispersed in a continuous phase of the styrene-based polymer, 70% or more of the number of particles of the rubbery polymer has an occlusion structure containing 5 or less inclusion occlusions, and the particles of the rubbery polymer having one inclusion occlusion are among the occlusion structures. The outer shape of the particles of the rubber-like polymer, which occupies 50% or more and has one inclusion occlusion, has a symmetrical surface, the area average particle diameter is 0.1 to 0.7 μm, and the area average with respect to the number average particle diameter. Particles having a particle size ratio of 1.0 to 2.5 are dispersed in the styrene polymer, and the gel amount is 1.1 to 4.0 weight ratio with respect to the rubbery polymer, and the swelling index is 5 to 20. And the rubber-like polymer Dispersed particles of the following equation: K = φ _R {1-[(D _S / 2) -λ) / (D _S / 2)] ³ } ^-1 (where φ _R is the rubber-like weight in the composition) The volume fraction of coalescence is shown, D _S is the area average particle diameter (diameter) of the rubber-like polymer, and λ is the thickness of the rubber-like polymer phase, which is 0.10 μm or less. The above is the rubber-modified styrenic resin composition characterized by the above.