JP2002037964A - Aromatic vinylic resin composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact resistant aromatic vinylic resin excellent in impact resistance and gloss, hardly losing the gloss in a high-temperature environment and excellent in flexural modulus. SOLUTION: This aromatic vinylic resin composition is characterized in that (A) rubber particles constituted of (a) an aromatic vinyl-conjugated diene block copolymer rubber having 25-50 wt.% content of an aromatic vinyl monomer unit, >=70% ratio of aromatic vinyl block and <=200 cps viscosity of 5% styrene solution, and (B) rubber particles constituted of (b) a conjugated diene- based rubber having >75 wt.% content of a conjugated diene monomer unit, >=40% content of the vinyl bond unit in the conjugated diene monomer unit, and >=20 cps viscosity of 5% styrene solution, are dispersed in a matrix of an aromatic vinylic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an impact-resistant aromatic vinyl resin composition having excellent gloss and a method for producing the same.

[0002]

2. Description of the Related Art Impact resistant polystyrene resin (HIPS)
Aromatic vinyl resins represented by are generally improved in impact resistance by dispersing rubber-like polymer particles in a resin matrix, and are inexpensive for electrical equipment, office equipment, and packaging. Widely used in fields such as containers and sundries.

However, when rubbery polymer particles are dispersed in a polystyrene resin, the gloss generally tends to be impaired,
It is a difficult task to achieve both impact resistance and gloss. For example, as a method of improving gloss, a method of using a styrene-butadiene block copolymer as a resin modifier has been proposed (JP-B-48-18594, JP-B-60-5).
However, this method has a problem that the improvement of the impact resistance is insufficient and the use thereof is limited.

It is known that, when styrene is polymerized in the presence of a rubber-like polymer, the particle size and structure of rubber particles dispersed in a polystyrene matrix differ depending on the type of rubber. For example, when a styrene-butadiene block copolymer is used, the rubber layer and the resin layer are inverted in the course of polymerization to form core-shell structured particles having a polystyrene core and a rubber shell, and a conjugated diene rubber such as polybutadiene. Is known to form particles having a salami structure in which polystyrene and rubber are mixed (for example, assessment of polymer production process 10, assessment of impact-resistant polystyrene (HIPS) production process, reaction engineering research). Society Research Report, published by the Society of Polymer Science, January 26, 1989).

Further, a method in which a plurality of rubbers are used in combination as a rubber component is also known.
JP-A No. 1 (1999) discloses that a small particle size formed of a styrene-butadiene block copolymer and a large particle size formed of a low cis-polybutadiene and a styrene-butadiene block copolymer coexist. A method for improving the formability without impairing the impact properties is described. However, the gloss obtained by this method is not always sufficient, and there is a problem that the gloss tends to decrease particularly when the molded article is placed in a high-temperature environment, and the bending elastic modulus is not always sufficient.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aromatic vinyl resin composition which has excellent impact resistance and gloss, and does not easily lose gloss even in a high temperature environment. An object of the present invention is to provide an efficient method for producing such a resin composition.

The present inventors have conducted intensive studies to achieve the above object. As a result, when two specific rubber components are used as a modifier, an aromatic compound having excellent properties in both impact resistance and gloss is obtained. The inventors have found that an aromatic vinyl resin composition can be obtained, and have completed the present invention.

[0008]

According to the present invention, there is provided, as a first invention, an aromatic vinyl resin matrix having an aromatic vinyl monomer content of 25 to 50% by weight, A rubber particle (A) composed of an aromatic vinyl-conjugated diene-block copolymer rubber (a) having a block ratio of 70% or more and a 5% styrene solution viscosity of 200 cps or less, and a conjugated diene monomer content of More than 75% by weight, and the vinyl bond amount in the conjugated diene monomer unit is 40%.
An aromatic vinyl resin composition in which rubber particles (B) composed of a conjugated diene rubber (b) having a styrene solution viscosity of 20% or more and a 5% styrene solution of 20% or more is provided.

According to a second aspect of the present invention, there is provided a first aromatic vinyl resin in which rubber particles (A) composed of the block copolymer rubber (a) are dispersed in a matrix of the aromatic vinyl resin. A method for producing an aromatic vinyl resin composition is provided in which the composition is mixed with a second aromatic vinyl resin composition in which rubber particles (B) composed of the conjugated diene rubber (b) are dispersed. Is done.

Further, as a third invention, rubber particles composed of rubber (a) by polymerizing a part of an aromatic vinyl monomer in the presence of block copolymer rubber (a) ( Step (I) for forming A), rubber particles (B) composed of rubber (b) by polymerizing a part of an aromatic vinyl monomer in the presence of conjugated diene rubber (b) (II), and a step (II) of mixing the polymerization reaction solutions obtained in the steps (I) and (II).
The present invention provides a method for producing an aromatic vinyl resin composition comprising I), a step (IV) of polymerizing an unreacted aromatic vinyl monomer in a polymerization reaction solution.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION [Aromatic Vinyl Resin Composition] The aromatic vinyl resin composition of the present invention is obtained by dispersing at least two kinds of different rubber particles in a matrix of an aromatic vinyl resin. is there. The aromatic vinyl resin is a polymer having an aromatic vinyl monomer as a main component, and the content of the aromatic vinyl monomer unit is preferably 50% by weight or more, more preferably 60% by weight or more, particularly Preferably 7
0% by weight or more.

Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, 2-methylstyrene,
-Methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-
Examples thereof include t-butylstyrene and 5-t-butyl-2-methylstyrene, and among them, styrene is preferable. These monomers may be used alone or as a mixture of two or more.

[0013] If necessary, other copolymerizable monomers may be used in combination with the aromatic vinyl monomer. Specific examples of other monomers include acrylonitrile, α, β-unsaturated nitriles such as methacrylonitrile, acrylic acid, methacrylic acid, unsaturated carboxylic acids or acid anhydrides such as maleic anhydride, methyl methacrylate, Examples include unsaturated carboxylic esters such as ethyl acrylate and butyl acrylate.

Rubber particles (A) The rubber particles (A) have an aromatic vinyl monomer content of 25 to
50% by weight, preferably 30 to 45% by weight, particularly preferably 35 to 45% by weight, and the aromatic vinyl block ratio is 70% or more, preferably 80% or more, particularly preferably 90% or more, and 5% Styrene solution viscosity 200cp
s or less, preferably 10 to 100 cps, particularly preferably 20 to 50 cps.
It is obtained by graft-polymerizing a graft polymerization monomer mainly composed of an aromatic vinyl monomer onto the block copolymer rubber (a). If the amount of the aromatic vinyl monomer in the block copolymer rubber (a) is too small, the gloss decreases, and if it is too large, the impact resistance decreases. On the other hand, if the aromatic vinyl block ratio is too low or the viscosity of the 5% by weight styrene solution is too high, the gloss is reduced.

The conjugated diene monomer used for producing the block copolymer rubber (a) is not particularly limited.
-Butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene and the like can be mentioned. Among these, 1,3-butadiene and 2-methyl-1,3-butadiene are preferable, and 1,3-butadiene is particularly preferable. The aromatic vinyl monomer is the same as that used in the production of the above-mentioned aromatic vinyl-based resin, but need not necessarily be the same.

The block copolymer rubber (a) may be used in addition to a conjugated diene monomer and an aromatic vinyl monomer, as well as other monomers copolymerizable therewith as long as the effects of the present invention are not impaired. It may be obtained by copolymerizing a body. Examples of the copolymerizable monomer include non-conjugated diene monomers such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene and 5-ethylidene-2-norbornene, and methyl acrylate. And (meth) acrylate monomers such as methyl methacrylate.

The monomers for graft polymerization may be in the same category as the monomers used in the production of the aromatic vinyl resin composition, but usually have the same composition.
For example, when the aromatic vinyl resin is polystyrene, it is styrene, when it is an acrylonitrile-styrene resin, it is acrylonitrile and styrene, and when it is a methyl methacrylate-styrene resin, it is methyl methacrylate and styrene.

As the polymerization of the monomer for graft polymerization proceeds, the rubber (a) dissolved in the monomer forms a core-shell type particle structure. These particles usually have a core-shell structure in which a newly formed resin component is used as a core and rubber (a) is used as a shell. Such a structure is made of rubber (a)
It is formed when the grafting amount of the grafting monomer is about 5 to 50 parts by weight based on 100 parts by weight.

The particle size of the rubber particles (A) is preferably 0.1.
01 μm to 0.5 μm, more preferably 0.1 μm to
When the particle size is too small, the impact resistance may be poor, and when it is too large, the gloss may be poor.
Since the particle size depends on the type of the block copolymer rubber (a) and the type of the grafting monomer, it is necessary to appropriately select the particle size within the above range.

Rubber particles (B) The rubber particles (B) have a conjugated diene monomer unit content of 75%.
% By weight and the amount of vinyl bonds in the conjugated diene monomer unit is 40% to 90% by weight, preferably 50 to 85%.
%, Particularly preferably 60% to 80% by weight, and a 5% by weight styrene solution viscosity of 20 cps or more, preferably 30%
~ 1000 cps, more preferably 40 ~ 200 cps
Is obtained by graft-polymerizing a graft polymerization monomer having an aromatic vinyl monomer as a main component to the conjugated diene rubber (b).

The conjugated diene monomer unit amount contained in the conjugated diene rubber (b) is more than 75% by weight, preferably 8%.
0% by weight or more, particularly preferably 90% by weight or more,
If the amount is too small, the impact resistance becomes insufficient. The conjugated diene monomer used is the same as that used in the production of the block copolymer rubber (a),
It need not be the same. Further, other monomers copolymerizable with the conjugated diene monomer may be used in combination as long as the effects of the present invention are not impaired. Examples of such a monomer include those exemplified as the aromatic vinyl monomer and the copolymerizable monomer in the description of the block copolymer rubber (a).

If the vinyl bond content of the conjugated diene rubber (b) is too small, the gloss in a high temperature environment becomes insufficient,
Further, the gloss may vary depending on the part of the molded product. In the present invention, the molecular weight of the rubber (B) is also an important requirement. If the viscosity of the 5% by weight styrene solution is too large, the gloss is reduced, and if it is too small, the impact resistance is reduced.

The rubber particles (B) can be obtained in the same manner as in the case of the rubber particles (A) except that a conjugated diene rubber (b) is used instead of the block copolymer rubber (a) as the rubber component. it can. The conjugated diene rubber (b) dissolved in the monomer becomes particles and precipitates as the graft polymerization monomer proceeds, and is dispersed in the monomer. The shape of the particles at this time usually has a salami structure in which the newly formed resin component and rubber (b) are intertwined with each other. The grafting amount of the grafting monomer to 100 parts by weight of the rubber (b) is usually 5 to 50 parts by weight.

The rubber particles (B) preferably have a particle size of 0.1.
It is 7-5 μm, more preferably 1-2.5 μm. If the particle size is too small, the impact resistance may be poor, and if too large, the gloss may be poor. The particle size depends on the type of the block copolymer rubber (a) and the type of the grafting monomer, and can be appropriately selected so as to fall within the above range.

The aromatic vinyl resin composition of the present invention comprises at least the two kinds of particles (A) and (B) dispersed in a matrix of the aromatic vinyl resin. The method for producing such a resin composition is not particularly limited, and examples thereof include the following methods.

In the first method, a first aromatic vinyl resin composition containing rubber particles (A) obtained by previously polymerizing a grafting monomer in the presence of a block copolymer rubber (a) is used. And a second aromatic vinyl resin composition (2) containing rubber particles (B) obtained by polymerizing a graft monomer in the presence of a conjugated diene rubber (b). And then mixing both resin compositions.

The first resin composition used in this method is obtained by polymerizing a graft monomer mainly composed of an aromatic vinyl monomer in the presence of the block copolymer rubber (a). be able to. The amount of the block copolymer rubber (a) to be used is from 2 to 2 of the obtained first resin composition.
The content is 5% by weight, preferably 3 to 20% by weight, and particularly preferably 5 to 15% by weight. If the amount is too small, the impact resistance is not sufficiently improved, and if it is too large, the gloss tends to decrease.

The polymerization may be carried out according to a conventional method. After dissolving the block copolymer rubber (a) in the grafting monomer,
It can be produced by a general polymerization method, for example, a bulk polymerization method, a solution polymerization method, a bulk-polymerization suspension method in which suspension polymerization is performed after the bulk polymerization, or the like. Examples of the polymerization solvent used in the solution polymerization include benzene, toluene, xylene, cyclohexane, and the like. In the bulk-polymerization suspension method, a water-soluble polymer such as polyvinyl alcohol or an alkali metal salt of polymethacrylic acid is used as a dispersant, and the amount of the water-soluble polymer is 0 to 100 parts by weight of a monomer solution in which rubber is dissolved. It is about 0.5 to 10 parts by weight. Also, if necessary, α
A chain transfer agent such as -methylstyrene dimer, n-dodecylmercaptan, t-dodecylmercaptan, or terpylene is used, and its use amount is about 50 to 10000 ppm based on the grafting monomer.

The polymerization temperature varies depending on the presence or absence of a polymerization initiator, but is usually appropriately selected in the range of 20 to 200 ° C. When the polymerization is carried out by heat without using a polymerization initiator, the temperature is generally from 90 to 200 ° C., and when a polymerization initiator is used, polymerization at a lower temperature is also possible. The polymerization may be carried out at a constant temperature, but the temperature may be increased stepwise as the polymerization proceeds. By performing polymerization while raising the temperature stepwise, a product having a more excellent balance between impact resistance and gloss can be obtained. The grafting monomer may be added in its entirety at the start of the polymerization or gradually added after the start of the polymerization, and the polymerization may be of a batch type or a continuous type.

Examples of the polymerization initiator include azo compounds such as 2,2-azobisisobutyronitrile and azobiscyclohexanecarbonyl, and peroxides such as benzoyl peroxide, dicumyl peroxide and t-butyl hydroperoxide. Is mentioned. Among them, peroxide functions as a cross-linking agent for the block copolymer rubber (a), and is therefore preferable when cross-linking of the rubber component is desired. The amount of polymerization initiator depends on the type of initiator used,
It is not necessarily uniform depending on the types and amounts of the monomer and the block copolymer rubber (a), but usually 0% based on the total amount of the block copolymer rubber (a) and the monomer consumed by the polymerization. 0.001 to 3% by weight.

As the polymerization of the grafting monomer proceeds and the solid content concentration increases, the graft polymerization of the monomer onto the block copolymer rubber (a) also proceeds to form rubber particles (A). In the batch method, as the solid content concentration increases,
The phase of the block copolymer rubber (a), the phase of the newly formed resin, and the unreacted grafting monomer are mixed. When the solid concentration is 35% by weight or more, and in many cases about 40 to 50% by weight, rubber particles (A) having a shell portion composed of rubber (a) and a core portion composed of resin are formed. Is done. In the continuous polymerization, the formation mechanism of the rubber particles (A) is unknown, but in both the batch type and the continuous type, the rubber particles (A) are contained in the polymerization reaction solution having a solid concentration of 50% by weight or more. Exists.

After the formation of the rubber particles (A), desired components such as water, a dispersant, and an additional monomer are added, if necessary, and the polymerization is continued to obtain the rubber particles (A). Can be obtained in which the first aromatic vinyl resin composition is dispersed in the matrix. Although the conversion of the monomer is not particularly limited, it is desirable to make the conversion as high as possible from the viewpoint of productivity. 90-100% by weight of polymerization conversion
, The crosslinking of the rubber (a) constituting the shell portion of the rubber particles (A) often progresses.

After completion of the polymerization, the resin composition produced from the polymerization system is separated and recovered according to a standard method. For example, in the case of the bulk-suspension polymerization method, after removing unreacted grafting monomers as necessary, the product is separated from the polymerization suspension by filtration, washed with water, and then reduced under reduced pressure. Drying by heating,
The desired aromatic vinyl resin composition can be obtained by hot-air drying.

The second aromatic vinyl resin composition is the same as the above except that the conjugated diene rubber (b) is used instead of the block copolymer rubber (a) used in the production of the first resin composition. It can be obtained in the same manner as in the case of the first resin composition. The amount of the conjugated diene rubber (b) used is usually 2 to 25% by weight of the second resin composition, preferably 3 to 20%.
%, Particularly preferably 5 to 15% by weight. If the amount is too small, the impact resistance is not sufficiently improved, and if it is too large, the gloss tends to decrease.

In the case of batch polymerization, when the polymerization of the grafting monomer proceeds and the solid content concentration becomes 25% by weight or more, particularly about 30 to 40% by weight, the conjugated diene rubber (b) becomes Incorporating newly generated resin, rubber (b)
Thus, salami structure particles (B) composed of the resin and the resin are formed. Once these particles are formed, they remain in the polymerization reaction liquid in their original form, even if the monomer is added to the polymerization reaction liquid to lower the solids concentration. Although the formation mechanism of the particles (β) is unknown in the continuous polymerization, the particles (B) are contained in the polymerization reaction liquid having a solid content concentration of 40% by weight or more in both the batch polymerization and the continuous polymerization. ) Is present.

[0036] The aromatic vinyl resin composition of the present invention is obtained by mixing the first resin composition and the second resin composition. The mixing method is not particularly limited, a method of mechanically kneading, a method of removing the solvent after mixing the solutions of the respective resin compositions, after dissolving the other resin composition in the solution of one resin composition Although there is a method of removing the solvent and the like, mechanical kneading is awarded from an economic viewpoint. In any case, the obtained resin composition is preferably pelletized using a kneader.

The rubber component contained in the aromatic vinyl resin composition of the present invention is the total amount of the block copolymer rubber (a) and the conjugated diene rubber (b), and is usually 2 to 2 of the resin composition.
It is 5% by weight, preferably 3 to 20% by weight, particularly preferably 5 to 15% by weight. If the amount is too small, the impact resistance is not sufficiently improved, and if it is too large, the gloss tends to decrease.

The mixing ratio of the first resin composition and the second resin composition is such that the rubber component contained in the finally obtained resin composition is a block copolymer rubber (a) / conjugated diene rubber ( b) is 70 to 99/30 to 1, preferably 75 to 98/25 to 2 by weight. If the amount of the block copolymer rubber (a) is too small, the gloss decreases, and if it is too large, the impact resistance may be difficult. Further, as long as the effects of the present invention are not substantially impaired, rubber particles composed of other rubber components can be coexistent in addition to these two rubber components.

In the second method, a graft monomer is polymerized in the presence of a block copolymer rubber (a) to contain rubber particles (A) and an unreacted aromatic vinyl monomer. Is prepared, and on the other hand, the grafting monomer is polymerized in the presence of the conjugated diene rubber (b) to give rubber particles (B).
And a second polymerization reaction liquid containing an unreacted aromatic vinyl monomer and then mixing both polymerization reaction liquids, and then continuing the polymerization of the aromatic vinyl monomer.

In this method, first, in step (I), the grafting monomer is polymerized in the presence of the block copolymer rubber (a) to convert the rubber particles (A) and the unreacted aromatic vinyl monomer. A first polymerization reaction solution is produced. Similarly,
A second polymerization reaction solution containing a rubber particle (B) and an unreacted aromatic vinyl monomer by polymerizing the grafting monomer in the presence of the conjugated diene rubber (b) in the step (II) Is manufactured. Next, in the step (III), the first polymerization reaction liquid (I) obtained in the step (I) and the step (I)
After mixing the second polymerization reaction solution obtained in I), the aromatic vinyl resin composition is obtained by polymerizing the monomers contained in the polymerization reaction solution in step (IV).

In the steps (I) and (II), the polymerization is carried out in the same manner as described in the first method, and the desired amount of rubber particles (A) and rubber particles (B) are produced respectively. To stop the polymerization. Thereafter, in step (III), the polymerization reaction solution obtained in step (I) and the polymerization reaction solution obtained in step (II) are mixed at a desired ratio, and in step (IV), the first method is used. Polymerization is continued in the same manner as described, and after the polymerization is completed, the desired aromatic vinyl-based resin composition can be obtained by separating and recovering the resin composition according to a standard method.

The resin composition of the present invention may contain additives such as a lubricant, a plasticizer, a release agent, a flame retardant, an antioxidant, an ultraviolet absorber, an antistatic agent, a colorant, and a filler, if necessary. Can be blended.

The thus obtained aromatic vinyl resin composition of the present invention is excellent in impact resistance, flexural elasticity and gloss, especially when exposed to a high temperature environment. Is low, so electronic devices such as TVs and VTRs,
Housing materials for household electrical appliances such as air conditioners and refrigerators and office automation equipment; can be widely used for miscellaneous goods, stationery, toys, leisure goods, sports goods, household goods, packaging supplies, house supplies, building materials, and the like.

[0044]

The present invention will be described more specifically below with reference to examples. The parts and percentages in the examples are on a weight basis unless otherwise specified. The methods for measuring various physical properties are as follows.

(1) The vinyl bond amount of the bound butadiene unit and the styrene unit amount in the block copolymer rubber were determined by the Hampton method (R. Hampto) using an infrared spectrophotometer.
n, Anal. Chem. , 21, 923 (194)
9)).

(2) The block ratio of styrene is determined by M.
Kolthoff, et al. , J .; Polym. S
ci. , 1,429 (1948). That is, 0.05 g of the copolymer rubber was dissolved in 10 ml of carbon tetrachloride, and tert-
16 ml of 70% aqueous solution of butyl hydroperoxide
And 4% of 0.05% chloroform solution of osmium tetroxide in chloroform
Then, the mixture was refluxed in a 90 ° C. bath for 15 minutes to carry out an oxidative decomposition reaction. After the completion of the reaction, the reaction solution was cooled, and 200 ml of methanol was added with stirring to precipitate the blocked styrene component.
The mixture was filtered through a glass filter of μm, and the weight was shown as a ratio to the total styrene units in the styrene-butadiene block copolymer rubber.

(3) The Izod impact strength was measured using an injection molding machine SAV-30 / 30 (Yamashiro Seiki Co., Ltd .; mold temperature 50 ° C.)
Specimen molded at a nozzle tip temperature of 240 ° C (vertical 9c)
m, width 5 cm, thickness 2 mm) using JIS K-71
Measured at 25 ° C. according to 10. The injection port is 1 cm inside the lateral center.

(4) DuPont impact strength was measured by Method F and Geometry FB according to ASTM D3029 using test pieces obtained in the same manner as in (3) above.

(5) Gloss was measured at an incident angle of 60 ° according to JIS Z8741. The gate section means 2 cm inside (1 cm from the injection port) of the lateral center of the test piece, and the end section means 7 cm inside (6 cm from the injection port).

(6) The evaluation of the thermal stability of gloss was shown by the ratio of the gloss of the end portion before and after the heat treatment of the test piece. The heat treatment was performed by leaving the test piece in a forced air circulation oven at 90 ° C. for 3 hours.

(7) As for the particles in the resin composition, each composition was press-molded at 180 ° C. into a plate having a thickness of 1 mm, dyed with osmium tetroxide, and then taken with a transmission electron micrograph by an ultrathin section method. This is an average value of 200 particles taken and measured.

Reference Example 1 Styrene-butadiene copolymer rubber s (styrene unit content: 40.6%, styrene block rate: 97%, vinyl bond content in butadiene unit: 8%, 5% styrene solution viscosity: 21c
ps) 8 parts were dissolved in 92 parts of styrene, and a chain transfer agent (n
-Dodecylmercaptan) to prepare a styrene polymerization stock solution containing 300 ppm. Next, 2300 parts of the styrene polymerization stock solution was put into a jacketed reactor, and the mixture was polymerized with stirring at 130 ° C. until the solid content concentration became 45% to obtain a first polymerization reaction solution. Rubber particles having a rubber s as a shell layer were formed in the first polymerization reaction liquid.

Next, 625 parts of the first polymerization reaction solution cooled to 20 ° C. and 0.5% of polyvinyl alcohol (Gohsenol GH-20, manufactured by Nippon Synthetic Chemical Industry) as a dispersant
1875 parts of the aqueous solution was placed in a stainless steel reactor equipped with a stirrer, and heated to 70 ° C. while stirring. Thereafter, 1.25 parts of benzoyl peroxide and 0.63 part of dicumyl peroxide were added, and the mixture was added at 70 ° C. for 1 hour, 90 ° C. for 1 hour, 110 ° C. for 1 hour, and 130 ° C. for 4 hours.
Suspension polymerization was performed. After completion of the polymerization, a part was cooled to 20 ° C., and the polymer was collected by filtration and washed with water. After dehydration, 12
After drying under reduced pressure at 60 ° C. for a time, a resin composition S containing particles having a core-shell structure with an average particle diameter of 0.25 μm was obtained.

Reference Example 2 The same treatment as in Reference Example 1 was carried out except that butadiene rubber 11 (vinyl bond amount 74%, 5% styrene solution viscosity 37 cps) was used instead of styrene-butadiene copolymer rubber s.
A polystyrene resin composition L1 containing salami structure particles having an average particle size of 1.1 μm was obtained. During the polymerization of styrene, the one in which the polymerization conversion of styrene became 45% was used as a second polymerization reaction liquid. Particles having a salami structure were present in the second polymerization reaction solution.

Reference Example 3 Reference Example 1 was repeated except that butadiene rubber 12 (78% vinyl bond, 5% styrene solution viscosity 65 cps, coupling ratio with tetramethoxysilane 69%) was used instead of styrene-butadiene copolymer rubber s. To obtain a resin composition L2 containing core-shell particles having an average particle size of 1.8 μm.

Reference Example 4 Instead of styrene-butadiene copolymer rubber s, butadiene rubber 13 (vinyl bond content 9%, 5% styrene solution viscosity 3
The same treatment as in Reference Example 1 was carried out except that 0 cps) was used, to obtain a resin composition L3 containing salami structure particles having an average particle size of 0.8 μm.

Reference Example 5 The same treatment as in Reference Example 1 was carried out except that butadiene rubber 14 (vinyl bond amount 10%, 5% styrene solution viscosity 85 cps) was used instead of styrene-butadiene copolymer rubber s.
A polystyrene resin composition L4 containing salami structure particles having an average particle size of 0.8 μm was obtained.

Example 1 625 parts of a polymerization reaction liquid obtained by mixing 95% of the first polymerization reaction liquid obtained in Reference Example 1 and 5% of the second polymerization reaction liquid obtained in Reference Example 2, and polyvinyl alcohol (Gohsenol GH) -20)
1875 parts of a 0.5% aqueous solution was placed in a stainless steel reactor equipped with a stirrer, and heated to 70 ° C. while stirring. Then, 1.25 parts of benzoyl peroxide and 0.63 part of dicumyl peroxide were added, and the mixture was added at 70 ° C. for 1 hour and 9 hours.
1 hour at 0 ° C., 1 hour at 110 ° C., and 4 hours at 130 ° C.
The suspension polymerization was performed for a time. After completion of the polymerization, a part was cooled to 20 ° C., and the polymer was collected by filtration and washed with water. After dehydration, dried under reduced pressure at 60 ° C. for 12 hours to obtain an average particle size of 0.25
A resin composition containing core-shell structured particles having a size of μm and salami structure particles having an average particle size of 1.1 μm was obtained. After kneading the resin composition with a roll at 180 ° C. and pelletizing,
Test pieces were prepared, and the physical properties of Izod impact strength, Dupont impact strength, gloss, gloss ratio before and after thermal load, and bending elasticity were measured. The results are shown in Table 1.

Example 2 95 parts of the resin composition S and 5 parts of the resin composition L2 were mixed, kneaded with a roll at 180 ° C., and then pelletized.
A test piece was prepared using the pellet, and the physical properties were evaluated in the same manner as in the example. The results are shown in Table 1.

Example 3 An experiment was carried out in the same manner as in Example 2 except that 75 parts of the resin composition S and 25 parts of the resin composition L2 were mixed.
The results are shown in Table 1.

Comparative Examples 1 and 2 An experiment was performed in the same manner as in Example 3 except that the resin composition L3 or the resin composition L4 was used instead of the resin composition S. The results are shown in Table 1.

Comparative Example 3 An experiment was conducted in the same manner as in Example 1 except that only the resin composition S was used. The results are shown in Table 1.

[0063]

[Table 1]

(*) In Example 1, the mixing ratio of the first polymerization reaction liquid obtained in Reference Example 1 and the second polymerization reaction liquid obtained in Reference Example 2 is shown.

When butadiene rubber is used in place of the block copolymer rubber (a), the gloss is not sufficient, and the decrease in gloss due to heat load is particularly large. In addition, it is inferior in bending elasticity (Comparative Example 1). The same result is obtained when butadiene rubber having a low vinyl bond content is used as the conjugated diene rubber (b) (Comparative Example 2). Further, when the conjugated diene rubber (b) is not present, the gloss is good but the impact resistance is poor. (Comparative Example 3).

On the other hand, the resin compositions of the present invention shown in Examples 1 to 3 have high flexural elasticity, excellent gloss, and little decrease in gloss due to heat load.

[0067]

The aromatic vinyl resin composition according to the present invention comprises:
It has excellent impact resistance and thermal stability of gloss, and also has excellent bending elasticity. Therefore, it is useful as a material for electrical equipment, office equipment, packaging containers, miscellaneous goods, and the like.

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Claims (4)

[Claims] 1. An aromatic vinyl resin matrix having an aromatic vinyl monomer content of 25 to 50% by weight, an aromatic vinyl block ratio of 70% or more, and a 5% styrene solution viscosity of 200 cps or less. A rubber particle (A) composed of an aromatic vinyl-conjugated diene block copolymer rubber (a) having a conjugated diene monomer content of more than 75% by weight and a vinyl bond amount in a conjugated diene monomer unit An aromatic vinyl resin composition characterized by dispersing rubber particles (B) composed of a conjugated diene rubber (b) having a styrene solution viscosity of 40% or more and a 5% styrene solution of 20 cps or more. 2. The weight ratio of the block copolymer (a) and the conjugated diene rubber (b) contained in the matrix is from 70 to 70.
The resin composition according to claim 1, wherein the ratio is 99/30 to 1. 3. An aromatic vinyl resin matrix having an aromatic vinyl monomer content of 25 to 50% by weight, an aromatic vinyl block ratio of 70% or more and a 5% styrene solution viscosity of 200 cps or less. A first aromatic vinyl resin composition in which rubber particles (A) composed of an aromatic vinyl-conjugated diene block copolymer rubber (a) are dispersed, and a conjugated diene monomer content of 75% by weight More than 40% of vinyl bonds in the conjugated diene monomer unit
2. A second aromatic vinyl resin composition in which rubber particles (B) composed of a conjugated diene rubber (b) having a 20% styrene solution viscosity of 20 cps or more are mixed. A method for producing the aromatic vinyl resin composition according to the above. 4. An aromatic vinyl monomer content of 25 to 50.
Wt.%, Aromatic vinyl block ratio 70% or more, 5% Styrene solution viscosity 200 cps or less in the presence of an aromatic vinyl-conjugated diene block copolymer rubber (a) Step (I) of forming rubber particles (A) composed of rubber (a) by partially polymerizing, wherein the conjugated diene monomer content is more than 75% by weight, and A rubber (b) is obtained by polymerizing a part of an aromatic vinyl monomer in the presence of a conjugated diene rubber (b) having a vinyl bond content of 40% or more and a 5% styrene solution viscosity of 20 cps or more. (II) for forming the cured rubber particles (B), the step (I)
Mixing the polymerization reaction solution obtained in (II) and (II) (I
II), a method for producing an aromatic vinyl resin composition, comprising a step (IV) of polymerizing an unreacted aromatic vinyl monomer in a polymerization reaction solution.