JPS61148213A - Impact-resistant polystyrene based resin and production thereof - Google Patents

Abstract

PURPOSE:To obtain the titled resin, containing rubber particles, having a specific particle diameter, and dispersed in the resin, and having improved external appearance characteristics, e.g. gloss, by polymerizing a styrene based monomer, etc., in the presence of a specific butadiene rubber prepared by polymerizing butadiene in the presence of an Li based catalyst using a branching agent. CONSTITUTION:An impact-resistant polystyrene resin obtained by radically polymerizing (B) 98-80wt% styrene based monomer or an unsaturated compound, e.g. acrylonitrile, copolymerizable therewith in the presence of (A) 2-20wt% polybutadiene rubber, obtained by polymerizing butadiene in the presence of an Li catalyst, e.g. n-butyl lithium, using 0.2-1.5 equivalents, based on the catalyst, branching agent, e.g. SnCl4, and having (i) 50,000-500,000 weight-average molecular weight (measured by the GPC method), monomodal molecular weight distribution of 1.5-4.0 ratio between the weight-average molecular weight and number-average molecular weight, (ii) 20-90 Mooney viscosity [ML] measured by the L rotor method at 100 deg.C and (iii) 20-100cP (25 deg.C) viscosity [SV] of 5(wt)% styrene solution,,and satisfying relations of formula I (R is rubber particle diameter in the resultant resin and 0.5-2mu) and formula II.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a polystyrene resin that has extremely excellent impact resistance and rigidity, and also has excellent physical properties such as gloss, and a method for producing the same. Regarding.

[Conventional technology]

Conventionally, in order to improve the brittleness of polystyrene, a solution of unvulcanized rubber in styrene was bulk polymerized or
High-impact polystyrene has been produced by suspension polymerization or by mechanically mixing polystyrene and unvulcanized rubber. In particular, polystyrene obtained by bulk polymerization and bulk-suspension polymerization has excellent impact resistance and is widely used industrially.

In this case, the unvulcanized rubber used as a toughening agent includes polybutadiene rubber and butadiene-styrene copolymer rubber, but in general, polybutadiene rubber is used at a lower temperature than, for example, butadiene-styrene copolymer rubber. It has the feature of excellent impact resistance. Such polybutadiene rubber has a cis-1,4 content of 25 to 45, which is obtained by solution polymerization using a lithium catalyst.
Examples include so-called high-cis polybutadiene, which has a cis-1,4 bond of 90 or more and is obtained by polymerizing a so-called low-cis polybutadiene with a Ziegler catalyst. Solution-polymerized polybutadiene is thus useful as a toughening agent that provides impact-resistant polystyrene polymers with excellent properties, and has been widely used depending on the application and purpose.

However, the physical properties required of recent impact-resistant polystyrene resins have become more sophisticated than before, and various physical properties that were difficult to achieve using conventional unvulcanized rubber, such as It is desired to improve appearance properties such as gloss, which has an inverse relationship with impact resistance, without affecting impact resistance.
It is desired that polystyrene-based resins with excellent appearance properties can be substituted for resins with excellent appearance properties such as gloss.

As various countermeasures for this, for example,
No. 72010 discloses that the 1,2-vinyl bond is 10 to 2
5 molar ratio, 1,4-cis bond is 25 to 45 molar ratio, 1,
4-trans bond has a molar ratio of 30 to 65 and 30 to 6
A rubber-like elastic body having a solution viscosity of 0.07% is used as a toughening agent, and the soft component particles, that is, the rubber particles as we call them, have an average particle size of 0.5 to 1.5μ. polystyrene has been shown to have high gloss. Also, in Japanese Patent Application Laid-open No. 57-30713,
1゜ Impact resistance using a mixed rubbery polymer of a sitadiene polymer containing 60% or more of 2-vinyl bonds and a butadiene polymer containing 30% or less of 1,2-vinyl bonds as a toughening agent. A polystyrene resin composition is shown,
The composition is said to have excellent impact resistance, weather resistance, and surface gloss of molded products. Furthermore, in JP-A-57-143313, the number of 1,2-vinyl bonds is 4 to 20, the 1.4-cis bond is 78 to 96, and the number of 1.4-) u/su bonds is 2 or less. It has been shown that impact-resistant polystyrene resins made of polycitadiene rubber having an intrinsic viscosity of 0.5 to 5 as a toughening agent have excellent gloss. However, although polystyrene resin compositions using these special rubbers as toughening agents have some level of surface gloss, they lack impact resistance, especially impact resistance for practical use. There was a continuing demand for this improvement.

On the other hand, after a polymerization reaction is performed using lithium metal as a solution polymerization catalyst base material, a so-called living polymer is subjected to a coupling reaction using a branching agent.
It is also known to reduce the solution viscosity of polymers and to use the resulting branched polybutadiene as impact modifier for high impact polystyrene resins.

For example, in Japanese Patent Publication No. 48-13954, it is stated that the Mooney viscosity is 25 to ]00 and the solution has a specific viscosity.
It has been shown that a butadiene-based polymer can be used as a toughening agent for impact-resistant polystyrene-based monomers, and that this butadiene-based polymer can be obtained using tin halide or silicon halide as a coupling agent. ,
It is stated that the use of this polybutadiene rubber, which has a relatively high Mooney viscosity, improves the impact resistance of polystyrene resins. Still, special public service 1163-1973
According to Publication No. 3, a polystyrene resin using a rubber polymer having a Mooney viscosity of 30 to 150 and statistically randomly branched has excellent sheet properties such as impact resistance and tensile modulus, and is suitable for extrusion molded products. It has been shown that it is suitable for Furthermore, Japanese Patent Publication No. 53-44188 discloses a specified microorganism having a 1,2-vinyl content of 15 to 35 and a 1°4-cis content of 20 to 85, obtained using a branching agent. A polystyrene resin obtained by bulk or bulk suspension polymerization of polycitadiene with styrene and having a specific structure, Mooney viscosity, and solution viscosity has excellent dart impact strength at low temperatures and is suitable for injection molded products at low temperatures. It has also been shown that there is.

In particular, Japanese Patent Publication No. 49-11633 states that the obtained polystyrene resin also has excellent appearance properties.

[Problem that the invention seeks to solve]

However, although these polystyrene resins have some improvement in impact resistance strength, they are insufficient in terms of physical properties such as surface gloss and other physical properties, and even higher levels of appearance and other physical properties are insufficient. The improvement of the Nono Lance was expected to be t3. As mentioned above, it is not industrially easy to obtain a rubber toughening agent having a limited structure, and therefore the cost is high.

[Failure to solve the problem]

As a result of intensive research to solve the above-mentioned problems, the present inventors discovered that after polymerization using a lithium-based catalyst,
Polystyrene-based resins containing polybutadiene rubber with a specific structure using a branching agent in a limited weight and in a limited shape are known for their particularly excellent gloss and impact resistance. The present invention was based on this discovery.

That is, the present invention provides a gel permeation chromatograph obtained by polymerizing with a lithium-based catalyst and further using a branching agent in an amount of 0.2 to 1.5 equivalents to the lithium-based catalyst. having a monomodal molecular weight distribution with a weight average molecular weight of 50,000 to 500,000 and a ratio of weight average molecular weight to number average molecular weight of 1.5 to 4.0; b) using an L rotor; Mooney viscosity (ML: + is 20 to 90, c) measured at 25° C. A polybutadiene rubber having a 5 weight ratio styrene solution viscosity [Sv] of 20 to 100 centipoise is added to a 2 to 20 weight ratio weighting agent. and the rubber particle diameter [R) in the resin is 0.5~
A polystyrene resin having a diameter of 2 microns and having excellent gloss and impact resistance, which satisfies the relationship of the following formula (1), and a method for producing the same.

This impact-resistant polystyrene resin is a mixture of 2 to 20% by weight of the polybutadiene rubber specified in the present invention and a styrene monomer or an unsaturated compound copolymerizable with the styrene monomer. 98 to 80 weight percent by radical polymerization using bulk polymerization, combined bulk suspension polymerization, or solution polymerization, and the resulting resin has extremely high physical properties, that is, excellent impact resistance and external appearance properties such as gloss. This shows the lance.

The polybutadiene rubber used as a toughening agent in the present invention is solution polymerized using a lithium-based catalyst. Examples of lithium-based catalysts include n-propyllithium, isopropyllithium, n-butyllithium,
free-butyllithium, t-butyllithium, n-
Pentyllithium, Li 10 = Thiumtoluene, Benzyllithium, 1,4 dilithio-
Examples include n-butane, 1,2-dilithium-1,2-diphenylethane, trimethylene dilithium, oryzaisoprenyl dilithium, and especially n-butyl lithium, 1lee
-Butyllithium is preferred. Alternatively, modified catalysts may be used, in which polar compounds such as amines and ethers are added. Further, the polybutadiene rubber is polymerized using the above-mentioned lithium-based catalyst, and then processed into a so-called cup by using a branching agent in an amount of 0.2 to 1.5 equivalents to the lithium-based catalyst. Obtained by carrying out a ring reaction. The branching agent referred to herein refers to a polyfunctional reagent of tetrafunctional or more-F, whose functional group has reactivity with lithium.

Specifically, tetrachlorosilane, hexachlordisilane, pentachloromethyldisilane, tetrachlordimethyldisilane, hexachlordimethylenedisilane, hexazolomodylan, tetrachlortin, tetrayo1tin,
Silicon or tin compounds such as carbon tetrachloride, diesters such as diethyl adipate and diphenyl carbonate, diacyl halide Ps such as phthaloyl chloride to ethylenedicarginylchloride P, pyridines such as meta- or o-raviridine carboxylic acid, etc. In particular, tetrachlorosilane,
Hexachlordisilane is preferred.

When the functionality of the branching agent reagent is less than 4, it is difficult to obtain a polybutadiene rubber having the specified structure of the present invention in terms of branching efficiency; The effects of the present invention cannot be achieved with polystyrene-based resins using the following as a toughening agent. Generally, when 1 mole atom of a functional group reacts with 1 mole atom of lithium, it is an equivalent reaction, and therefore, 1 mole of lithium-based catalyst and n
This is an equivalent reaction with 1/n mole of a branching agent having an oval group. In the case of the present invention, the amount of branching agent used is 0.2 to 1.5 equivalents based on the lithium-based catalyst used. If the amount is less than 0.02 equivalents, the branching efficiency as a branching agent will be insufficient, and if the amount exceeds 1.5 equivalents, it is not necessary to use the branching agent. , which is also industrially disadvantageous. The necessary and sufficient amount of branching agent to be used to obtain a polybutadiene rubber having the specified structure to exhibit the effects of the present invention is within the above range, and more preferably, This is the case when the amount is 0.4 to 1.2 equivalents relative to the lithium-based catalyst.

In the case of polybutadiene rubber obtained using the above-mentioned branching agent, its composition is strictly a mixture of a branched polymer and some unbranched polymer, and the branching efficiency is insufficient. In the case of a polymer coupled with a polymer having an extremely sharp molecular weight distribution such as that obtained by Nototsuchi polymerization, the gel permeation chromatography is more than an immodal ratio of one part of the unbranched polymer and one part of the branched polymer. or a complex shape with shoulder beaks. In this case, it may be difficult to obtain the styrene solution viscosity specified in the present invention, or such polybutadiene rubber may not be able to carry out a uniform grafting reaction with the styrene monomer, and may be difficult to obtain as described below. The rubber particle size also becomes non-uniform. Therefore, the obtained polystyrene resin cannot obtain the high level of physical properties that are the effects of the present invention. The polybutadiene rubber used in the present invention has a high substantial coupling efficiency, and its gel emission chromatogram also has a monomodal shape.

Moreover, the polybutadiene rubber used in the present invention is
The weight average molecular weight (Afw) measured by a migration chromatograph is 50,000 to 500,000, and the molecular weight distribution (Mw/
kin ) is required to be 1.5 to 4.0. When Afw is less than 50,000, a sufficient toughening effect of the polystyrene resin cannot be obtained and it becomes difficult to handle it as a rubber. On the other hand, if Mw exceeds 500,000, 1. The processability of the rubber itself is insufficient, and the viscosity of the styrene solution of the rubber is also high, making it difficult to handle, and the effects of the present invention cannot be obtained in terms of gloss.

Furthermore, the molecular weight distribution represented by Mw/Afn is 1.5.
-4.0, and if the value is less than 1.5 or even 4.0, the toughening effect is insufficient. Therefore, the polybutadiene rubber specified in the present invention has an Afw of 50,000 to 500,000, which is approximately Ilfw, as measured by gel migration chromatography.
/A/n is 1.5 to 4.0, particularly preferably, Afw is 100,000 to 30,000, and Mw /Afn is 1.
8 to 2.5.

Further, it is necessary that the Mooney viscosity (ML) measured at 100° C. using the polybutadiene rubber Id, Lo-tar of the present invention is 20 to 90.

When the ML exceeds 90, it is difficult to handle it as a rubber in terms of processability and the like. On the other hand, if the ML is less than 20, it is difficult to achieve the objective of the present invention, which is a high level of physical properties such as excellent gloss and impact resistance. Preferable ML is 25-80.

Furthermore, the polybuta-citric rubber used in the present invention is heated at 25°C.
The solution viscosity [SV:] of the styrene solution is required to be 20 to 100 centipoise.

If the solution viscosity is 20 centipoise without grooves, it will be difficult to form the particle size of the rubber contained in the polystyrene resin specified in the present invention, the effect as a toughening agent will be insufficient, and the impact resistance will be insufficient. become inferior. Furthermore, an SV exceeding 10 centivoise is not desirable in the production of the polystyrene resin because the solubility in styrene decreases and the productivity deteriorates. A particularly preferred solution viscosity is between 30 and 70 centipoise.

Polybutadiene having a specified structure as described above can be easily produced, for example, by a continuous polymerization method.

That is, immediately after finishing the polymerization step, which consists of continuously feeding a butadiene monomer, a lithium-based catalyst, and an inert solvent into a predetermined polymerization tank and carrying out a polymerization reaction in the tank, Furthermore, a coupling step is carried out continuously in a separate reaction vessel. By going through such a manufacturing process, the productivity of the polybutadiene rubber is dramatically improved compared to the Nonotsuchi polymerization method, and it is also extremely advantageous in terms of its industrial utility value. .

The impact-resistant polystyrene resin of the present invention is a polystyrene resin containing the above-mentioned polybutadiene rubber in an amount of 2 to 20 times, preferably 3 to 12 times. If the amount of rubber used is within this range, the effect of improving impact resistance that is the objective of the present invention will not be sufficient.On the other hand, if the amount used exceeds this range, although the impact resistance will be improved, the original characteristics of the polystyrene resin will be For example, it causes loss of strength and rigidity, which is undesirable. In addition, in the present invention, other unvulcanized rubber known to be used as a toughening agent in addition to the polybutadiene rubber of the present invention is contained as a toughening agent in a small amount, for example, 1 to 10% by weight. Also good. In this case, in order to exhibit the effects of the present invention, at least 30 parts of the toughening agent used must be the polybutadiene rubber used in the present invention.

A preferred method for obtaining the impact-resistant polystyrene resin of the present invention is to mix 2 to 20 weight percent of the polybutadiene rubber used in the present invention with a styrenic monomer or an unsaturated compound copolymerizable with the styrenic monomer. 98 to 80 weight J of mixture with
This method involves radical-17 polymerization of e-cent by bulk polymerization, combined bulk suspension polymerization, or solution polymerization.

Examples of the styrenic monomer used in the present invention include styrene, α-methylstyrene, vinyltoluene, etc.
Used as a mixture of more than one species. Furthermore, examples of unsaturated compounds copolymerizable with styrene monomers include acrylonitrile and methyl methacrylate. The particularly preferred styrenic monomer in the present invention is styrene, which is used alone or in a mixture with other monomers, when the ratio of styrene in the mixture is 50 ξ-cents by weight or more. .

Bulk polymerization, which is one of the methods for obtaining the impact-resistant polystyrene resin of the present invention, is generally carried out as follows. First, the polybutadiene rubber specified in the present invention is dissolved in styrene.
Polymerization is carried out by heating at a polymerization temperature of 50'C. Further, when a radical initiator is used as a catalyst, polymerization is carried out at 20 to 200° C. in accordance with the decomposition temperature of the radical initiator, and the polymerization operation is continued until the reaction rate of styrene reaches a desired level. During this bulk polymerization, a known internal lubricant, such as fluid rough-in, is often added in an amount of 0.1 to 5 parts by weight per 100 parts by weight of polymer. After completion of the polymerization, if the resulting polymer contains a small amount of unreacted styrene, usually less than 30 percent by weight, such styrene can be removed by known methods such as vacuum removal under heat or designed for the purpose of devolatilization. It is desirable to remove it by a method such as removal using an extrusion device. Stirring during such bulk polymerization is carried out as necessary, but the conversion rate of styrene to a polymer, that is, the polymerization rate of styrene is 30%.
% or more, it is desirable to stop or reduce agitation. Excessive stirring may reduce the strength of the resulting polymer.

If necessary, the polymerization may be carried out in the presence of a small amount of a diluting solvent such as toluene or ethylbenzene, and after the completion of the polymerization, these diluting solvents may be removed together with unreacted styrene by heating.

Bulk suspension combined polymerization is also useful in producing the high impact polystyrene resin of the present invention. In this method, the first half of the reaction is carried out in bulk, and the second half is carried out in suspension. That is, a styrene solution of the specific polybutadiene of the present invention is subjected to heat polymerization in the absence of a catalyst or polymerization with the addition of a catalyst in the same manner as in the previous bulk polymerization, or to irradiation polymerization to obtain a styrene concentration of usually 50 or less, particularly preferably 10. or 40
Partially polymerize up to the first part. This is the first half of bulk polymerization. This partially polymerized mixture is then dispersed under stirring in an aqueous medium in the presence of a suspension stabilizer or both thereof and a surfactant, and the second half of the reaction is completed by suspension polymerization.
As in the case of bulk polymerization, it is washed, dried, and, if necessary, made into pellets or powder for practical use.

The impact-resistant polystyrene resin of the present invention thus obtained is a polymer obtained by graft copolymerizing a hard phase of a styrene polymer with a soft component, such as styrene.

It consists of dispersed particles of ribtadienzam and a styrenic polymer encapsulated therein.

In the impact-resistant polystyrene resin of the present invention, the particle diameter [R] of the soft component particles, that is, the rubber particles, is 0.5 to 2 microns expressed as the average value, that is, the average particle diameter.

The average particle diameter is defined by taking an electron microscope photograph of the resin using an ultra-thin section method, measuring the particle diameters of 200 to 500 soft component particles in the photograph, and calculating the weight average using the following formula.

Weight average diameter [R] - ΣnD'/ΣnD2 where n is the number of soft component particles in the particle diameter.

If the rubber particle size is less than 0.5 microns, although excellent physical properties such as gloss can be obtained, the resin will have poor impact strength and the effect of the rubber as a toughening agent will not be obtained. On the other hand, if it exceeds 2.0 microns, a toughening effect can be obtained, but the resin will have poor physical properties in terms of gloss. In order to best balance these contradictory physical properties, it is necessary that the rubber particle diameter is within the above range, and more preferably, the rubber particle diameter is between 0.8 and 1.
．． This is a case where the value is within the range of 5.

Furthermore, in order to obtain an impact-resistant polystyrene resin with extremely high gloss, which is an effect of the present invention, the Mooney viscosity of polybutadiene rubber (WCML) and the 5 weight coefficient styrene solution viscosity at 25°C (SV : ] and the rubber particle diameter [R] in the polystyrene resin made using it, the relationship of the following formula (1) needs to hold true.

The ratio of the logarithms of the 5 wt% styrene solution viscosity and Mooney viscosity of polybutadiene rubber is within the range of 0.82 to 1.18, and if it is smaller than 0.82, the rubber has a high Mooney viscosity. Even if the solution is present, the viscosity of the solution is still too low, and the resulting polystyrene resin will not have the desired physical properties and will have low impact strength.

On the other hand, if it is larger than 1.18, the solution viscosity is too high, and in terms of physical properties, appearance properties such as gloss are poor. Good trench, ρogSV and I! ,
This is the case when the ratio with og M L is in the range of 0.91 to 1.09. Furthermore, when the value of the above ratio is within this range and the relationship of the above formula (1) is established between the value of the ratio and the diameter of the rubber particles in the polystyrene resin, the effects of the present invention are strongly exhibited. be done. That is, when the value of the above formula (1) is less than 1.0, the rubber particle diameter is too low,
Although the resulting polystyrene resin has high gloss, its impact strength is low, making it unfavorable in terms of physical properties. On the other hand, if the value of the above formula (1) exceeds 1.4, a resin with excellent impact resistance can be obtained, but it is inferior in terms of gloss, and it is difficult to maintain high physical properties. is in trouble. The particularly favorable range of the above formula (1) is from 1.1 to
It is 1.3.

〔Effect of the invention〕

The impact-resistant polystyrene resin of the present invention exhibits particularly excellent high gloss compared to conventional styrene or impact-resistant polystyrene resins containing styrene as a main component, and has extremely excellent impact resistance. It is far superior to conventional resins in terms of tensile strength, elongation, etc. Furthermore, as mentioned above, the productivity is sufficient, and the industrial significance of the present invention is extremely high.

The impact-resistant polystyrene resin of the present invention can be used as a practically useful product in a wide variety of ways by processing methods such as injection molding and extrusion molding.
Antioxidants, ultraviolet absorbers, lubricants, mold release agents, fillers, etc.
Furthermore, it may be used in combination with other thermoplastic resins such as general polystyrene, methacrylic resin, etc.

〔Example〕

Hereinafter, specific embodiments of the present invention will be shown with some Examples, but these are intended to explain the gist of the present invention more specifically, and are not intended to limit the present invention.

Example 1 Continuous polymerization described below was carried out to identify the present invention 1
Polycytadiene A was synthesized.

In a polymerization tank with an internal volume of 10β and equipped with a stirring blade and a jacket, a mixed solution of 1,3-butadiene-n-hexane with a concentration of 15% was added at 200 m//min, and 40.2 ppnrl of n-dityllithium-n- The hexane mixture was pumped continuously at 50 m/min. Rotation speed 120 revolutions/minute,
The polymer solution, which was mixed and stirred at a polymerization temperature of 100° C. and further overflowed, was fed into a coupling reaction tank having the same shape and equipment as the above-mentioned polymerization tank. The fed polymer solution and an n-hexane solution of 5iCj14 were pumped at a flow rate of 50 d/min so that the amount was 0.6 equivalent to n-butyllithium, and the mixture was stirred and mixed at a temperature of 80°C. Di-tert-butyl-4-methylphenol was added as a stabilizer to the polymer obtained by over-flowing from the coupling reaction tank, and the solvent was distilled off under heating to obtain Polymer A. Table 1 shows the physical properties of the obtained polymer.

Using this rubber as a toughening agent, the following bulk polymerization was carried out.

6 parts by weight of the above polymer A was dissolved in 94 parts by weight of styrene and 8 parts by weight of ethylbenzene, and 0.0% by weight of the polymer A was dissolved in 94 parts by weight of styrene and 8 parts by weight of ethylbenzene.
0.5 parts by weight of 4-nzoyl oxide and 0.10 parts by weight of α-methylstyrene dimer were added, and 4
Polymerization was carried out under stirring for 4 hours at 110°C and 4 hours at 150°C. Further, heat treatment was performed at around 230° C. for 30 minutes, and then unreacted styrene and ethylbenzene were removed in vacuo to obtain a polystyrene resin. After pulverizing this, it was made into pellets using an extruder, injection molded, and the physical properties were measured. The results are shown in Table 2.

Examples 2, 3 and Comparative Examples 1 to 4 Polybutadiene samples B-G were prototyped by performing the same operation as shown in Example 1 and varying the amount of n-butyllithium and branching agent equivalent. . Here, sample C does not use a branching agent, and sample F uses Si2 as a branching agent.
C2H4Cf), 6. Furthermore, using these rubbers as toughening agents, in the same manner as in Example 1,
Bulk polymerization was performed to obtain polystyrene resin. The physical properties of the obtained polymer and resin are shown in Tables 1 and 2.

Comparative Example 5 In Comparative Example 5, a polystyrene resin was prepared using polybutadiene rubber H obtained by the following tsuchi polymerization method as a toughening agent.

Inner volume 10! A 1,3-butadiene-n-hexane mixed solution 82 with a concentration of 15 and an n-butyllithium solution with a concentration of 0.12 mol/L were placed in a polymerization vessel equipped with a stirrer and a jacket at a rate of 15.7 d. Polymerization was carried out at 120° C. for 30 minutes. Furthermore, a solution of 5iCf14 in n-hexane was added in an amount of 08 times that of n-butyllithium to give a solution of 10
The reaction was carried out at 0° C. for 30 minutes with stirring. The subsequent treatment was carried out in the same manner as in Example 1 to obtain Polymer H. The obtained polymer was used as a toughening agent and subjected to bulk polymerization in the same manner as in Example 1 to obtain a polystyrene resin. The physical properties of Polymer H and the obtained polystyrene resin are shown in Tables 1 and 2, respectively.

From the results shown in Table 2, the polystyrene resins using polybutadiene rubbers A, B, and F specified in the present invention as toughening agents are different from those using other unspecified polybutadiene rubbers as toughening agents. It can be seen that not only the impact resistance is sufficient, but also the appearance, particularly in terms of gloss, is extremely excellent.

Example 4 The same procedure as in Example 1 was carried out except that Polymer A was changed to 12 parts by weight and styrene was changed to 88 parts by weight. The results obtained are shown in Table 2.

Example 5 A high-impact polystyrene resin was obtained by combined bulk suspension polymerization. Styrene 95 is added to 5 parts by weight of polysitadiene rubber B.
150 parts by weight of water containing 3 parts by weight of tribasic calcium phosphate and 2 parts by weight of sodium P-decylbenzenesulfonate. The heavy scene is suspended,
To this suspension, 13 parts by weight of penzoylno-e-oxai PO and 0.05 parts by weight of ditertiary ditylno-oxai were added, and the polymerization was carried out at 80°C for 2 hours, at 110°C for 2 hours, and then at 130°C for 2 hours. Completed. The obtained suspended particles were dried in Sawabetsu and injection molded into pellets using an extruder, and the physical properties were measured. The results are shown in Table 2.

(Hereafter, remainder b)

Claims (2)

[Claims] (1) Polymerized using a lithium-based catalyst and further using a branching agent in an amount of 0.2 to 1.5 equivalents to the lithium-based catalyst a) Measured by gel permeation chromatography It has a monomodal molecular weight distribution with a weight average molecular weight of 50,000 to 500,000 and a ratio of weight average molecular weight to number average molecular weight of 1.5 to 4.0, b) Uses an L rotor and is used at 100 ° C. Mooney viscosity [ML] of 20 to 90, c) 5 wt% styrene solution viscosity [SV
] is 20 to 100 centipoise using 2 to 20% by weight of polybutadiene rubber as a toughening agent, and the rubber particle size [R] in the resin is 0.
．． Polystyrene resin 1.0<(logSV)/(logML)+0.2R<1.0<(logSV)/(logML)+0.2R<
1.4 Here, 0.82<(logSV)/(logML)<
1.18 (2) Polymerized using a lithium-based catalyst and further using a branching agent in an amount of 0.2 to 1.5 equivalents to the lithium-based catalyst a) Measured by gel permeation chromatography It has a monomodal molecular weight distribution with a weight average molecular weight of 50,000 to 500,000 and a ratio of weight average molecular weight to number average molecular weight of 1.5 to 4.0, b) Measured at 100°C using an L rotor. Mooney viscosity [ML] of 20 to 90, c) 5 wt% styrene solution viscosity [SV] at 25°C
2 to 20% by weight of polybutadiene rubber having a diameter of 20 to 100 centipoise, and 98 to 80% by weight of a mixture of a styrenic monomer or an unsaturated compound copolymerizable with the styrenic monomer, in the form of a lump or a lump suspension. A rubber particle size [R] in the resin obtained by radical polymerization in a cloudy or solution state is 0.5 to 2 microns, and has good gloss and impact resistance, and is characterized by satisfying the relationship of the following formula. Excellent method for producing polystyrene resin 1.0<(lo
gSV)/(logML)+0.2R<1.4 where 0.82<(logSV)/(logML)<
1.18