JPH078894B2 - Method for producing impact-resistant aromatic vinyl resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an impact-resistant aromatic vinyl-based resin, more specifically, a specific conjugated diene-based polymer as a rubber-like polymer, The present invention relates to a method for producing an impact-resistant aromatic vinyl-based resin having an excellent balance of impact resistance, appearance characteristics and mechanical characteristics by graft-polymerizing an aromatic vinyl compound.

[Conventional technology]

In general, aromatic vinyl resins such as styrene resins are
It has many excellent properties such as flowability at the time of growth, transparency of molded products, and gloss, but it is inferior in impact resistance as a major drawback.

In order to compensate for such drawbacks, a method of mechanically dispersing a rubber-like polymer in a resin, a method of graft-polymerizing an aromatic vinyl compound (for example, styrene) on the rubber-like polymer, and the like are known.

However, the method of mechanically mixing the rubber-like polymer merely gives a brittle mixture when there is no affinity between the rubber-like polymer and the resin. Further, when the affinity between the two is good, the impact resistance is improved, but the mechanical properties of such a resin are not sufficiently improved, and the surface gloss of the molded product is not excellent, and the rubber-like polymer Since it has not been crosslinked, it has a drawback that the orientation of the molded article is large.

On the other hand, in the method of graft-polymerizing an aromatic vinyl compound on the rubber-like polymer, the impact resistance of the obtained resin is improved, but the properties such as mechanical properties, orientation and surface gloss are still sufficiently satisfied. Not a thing.

As a method for improving such a defect, a method of using a butadiene polymer containing a large amount of vinyl bonds as a rubber-like polymer and graft-polymerizing styrene thereto has been proposed (for example, JP-B-45-40546, Kaisho 59-1
(See Japanese Patent No. 84216).

[Problems to be solved by the invention]

However, a resin obtained by using a butadiene polymer containing a large amount of vinyl bonds as the rubber-like polymer and graft-polymerizing styrene on the butadiene polymer is not yet satisfactory in its orientation and surface gloss, and has a mechanical property. It has the drawback of low properties, in particular tensile strength. In particular, when the content of the rubber-like polymer is increased to improve the impact resistance due to the recent cost reduction and thinning, these drawbacks are remarkably exhibited.

In view of the above-mentioned conventional technical problems, the present inventors have diligently studied for the purpose of providing an impact-resistant aromatic vinyl-based resin having an excellent balance of impact resistance, appearance characteristics and mechanical characteristics of the resin. As a result, the inventors have found that the technical problem can be solved by adopting a conjugated diene-based polymer having a specific structure as a rubber-like polymer and graft-polymerizing an aromatic vinyl compound on the rubber-like polymer. Is.

[Means for solving problems]

That is, the present invention is a method of radically polymerizing an aromatic vinyl compound in the presence of a conjugated diene polymer, wherein the conjugated diene polymer is a rubber-like product obtained by solution polymerization of the conjugated diene compound using an organolithium compound as a catalyst. A polymer, and the polymer has a polystyrene-equivalent molecular weight of 100,000 or less in the molecular weight distribution measured by gel permeation chromatography (GPC) of 10% by weight or less, Mooney viscosity (ML _{1 + 4} , 100 C) of 50 to 100, vinyl bond content of more than 35% and 50% or less, and 5 wt% styrene solution viscosity (hereinafter sometimes simply referred to as “styrene solution viscosity”) measured at 25 ° C. is 100 to 200.
The present invention provides a method for producing an impact-resistant aromatic vinyl-based resin, which has a centipoise and a coupling efficiency of 5% or more and less than 50%.

According to the present invention, first, a specific conjugated diene-based polymer is produced, and an aromatic vinyl compound is graft-polymerized in the presence of a radical initiator on the specific conjugated diene-based polymer. Therefore, excellent balance of impact resistance, appearance properties and mechanical properties is achieved. It is intended to produce an aromatic vinyl resin.

Here, the conjugated diene-based polymer used in the present invention,
A rubbery polymer obtained by solution polymerization of a conjugated diene compound using an organolithium compound as a catalyst.

Here, as the conjugated diene compound, 1,3-butadiene, 1,3-pentadiene, isoprene, chloroprene,
1,3-hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene,
In addition to 1,3-heptadiene, etc., branched carbon number 4-7
Various conjugated diene compounds of, preferably 1,3-
Butadiene, isoprene and 1,3-pentadiene, particularly preferably 1,3-butadiene.

Examples of the organolithium compound that is a catalyst for solution polymerization of the conjugated diene compound include, for example, n-propyllithium, isopropyllithirim, n-butyllithium, sec-butyllithium, tert-butyllithium, n.
-Pentyllithium, lithium toluene, benzyllithium, 1,4-dilithio-n-butane, 1,2-dilithio-1,
Examples thereof include 2-diphenylethane, trimethylenelithium, 2-diphenylethane, trimethylenedilithium and oligoisoprenyldilithium, and generally n-butyllithium and sec-butyllithium.

Furthermore, examples of the hydrocarbon solvent used for the solution polymerization include pentane, hexane, heptane, cyclohexane, methylcyclopentane, benzene, toluene, xylene and the like. These hydrocarbon solvents may be used alone or in combination of two or more.

In this solution polymerization, in order to adjust the vinyl bond content of the resulting conjugated diene-based polymer, an ether compound such as dimethyl ether, diethyl ether, or tetrahydrofuran; a thioether compound such as dimethyl sulfide, diethyl sulfide; A Lewis base represented by amine compounds such as tri-n-propylamine and triethylamine can be added.

In addition, in order to adjust the molecular weight of the obtained conjugated diene polymer, a coupling agent such as tin tetrachloride, carbon tetrachloride, chloroform, silicon tetrachloride, methyltrichlorosilane, etc., is added to the living polymer produced in the polymerization system. Compound: A coupling reaction can be performed with a coupling agent such as a diester compound such as diethyl adipate, methyl adipate, or diethyl fumarate.

Furthermore, the solution polymerization temperature is a normal polymerization temperature, for example, 50 to 15
It is carried out at 0 ° C, preferably 70-120 ° C.

Now, the conjugated diene polymer used in the present invention is a rubbery polymer obtained by solution polymerization of the conjugated diene compound using the organolithium compound as a catalyst as described above. Must meet the requirements of.

The content of the component having a molecular weight of 100,000 or less is 10% by weight or less, preferably 9% by weight or less, more preferably 6% by weight or less.

If the polymer having a polystyrene-equivalent molecular weight of 100,000 or less by GPC exceeds 10% by weight, the conjugated diene polymer used will have too many low-molecular weight components, resulting in low tensile strength of the aromatic vinyl resin. Moreover, the effect of improving impact resistance is small, which is not preferable.

In order to satisfy such constitutional requirements, for example, solution polymerization of a conjugated diene compound is substantially completed to obtain a living polymer having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 20 to 60, preferably 30 to 50. Then, it can be produced by reducing the low molecular weight component by coupling it using the coupling agent.

Therefore, the constituent requirements can be easily achieved by adjusting the Mooney viscosity of the living polymer to be produced and the amount of the coupling agent used.

The Mooney viscosity (ML _{1 + 4} , 100 ° C) is 50 to 100, preferably 55 to 80.

When the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the conjugated diene polymer used in the present invention is less than 50, the effect of improving the impact resistance of the obtained aromatic vinyl resin is not sufficient, while 100 If the amount exceeds the limit, it takes a long time to dissolve in the aromatic vinyl compound, and its solution viscosity is high, which is disadvantageous for stirring and transportation during graft polymerization.

The Mooney viscosity can be easily adjusted by changing the amount of the organolithium compound used in the solution polymerization of the conjugated diene compound and the amount of the coupling agent used.

Vinyl bond content is more than 35% and 50% or less, preferably 37
~ 48%.

When the vinyl bond content of the conjugated diene-based polymer used in the present invention is 35% or less, the degree of graft polymerization of the aromatic vinyl compound with respect to the polymer becomes insufficient and the resulting resin has a large orientation, Moreover, even if a molded product is produced using this, only a product having inferior surface gloss can be obtained.

On the other hand, when the vinyl bond content exceeds 50%, the orientation of the resulting resin is improved, but the thermal stability becomes poor,
In addition, the impact resistance is deteriorated. The vinyl bond content can be easily adjusted by adding the Lewis base to the solution polymerization system and selecting the amount used.

5% by weight styrene solution viscosity measured at 25 ° C is 100-200
Centipoise, preferably 110-180 centipoise.

When the viscosity of a 5% by weight styrene solution of the conjugated diene polymer used in the present invention measured at 25 ° C. is less than 100 centipoise, the resulting aromatic vinyl resin has insufficient effect of improving impact resistance, while Those having a viscosity exceeding the centipoise take a long time to dissolve in the aromatic vinyl compound, and the solution viscosity is high, which is disadvantageous in stirring and transportation during the graft polymerization.

This styrene solution viscosity can be adjusted by changing the polymerization temperature in solution polymerization, the amount of coupling agent used, or the type of coupling agent.

The coupling efficiency is more than 5% and less than 50%, preferably 5-30%.

Next, the present invention uses the above-mentioned specific conjugated diene-based polymer and graft-polymerizes an aromatic vinyl compound thereto.

Here, examples of the aromatic vinyl compound applied in the present invention include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, vinylnaphthalene, vinylethylbenzene, and vinylxylene, but preferably styrene. , Α-methylstyrene and p-methylstyrene, and more preferably styrene.

The method of radically copolymerizing the aromatic vinyl compound with the specific conjugated diene polymer is not particularly limited, but for example, an aromatic vinyl compound solution in which the conjugated diene polymer is dissolved is used. Bulk polymerization,
It is carried out by a method of radical polymerization by a combination of bulk polymerization and suspension polymerization.

Here, the mixing ratio of the conjugated diene polymer and the aromatic vinyl compound is 3 to 25% by weight of the former, preferably 5 to 15% by weight, and 97 to 75% by weight of the latter, preferably 95 to 85% by weight. .

When the amount of the conjugated diene polymer used is less than 3% by weight, the impact resistance of the resulting resin is lowered and it is difficult to achieve the object of the present invention, while when it exceeds 25% by weight, the viscosity of the graft polymerization solution becomes very high. It becomes difficult to actually carry out graft polymerization.

In the case of bulk polymerization, the conjugated diene-based polymer is dissolved in an aromatic vinyl compound, and then a molecular weight modifier is added if necessary.

As the molecular weight modifier, for example, α-methylstyrene dimer, n-decyl mercaptan, tert-dodecyl mercaptan, 1-phenylbutene-2-fluorene and mercaptans such as dipentel and chloroform, terpenes, halogen compounds and the like are used.

Further, a lubricant is generally added to improve the moldability of the obtained resin. As this example, ester lubricants such as butyl stearate and butyl phthalate, and lubricants used in conventional resin processing such as mineral oil and paraffin wax can be used.

After dissolving these in the polymer solution, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, methyl ethyl ketone peroxide, dicumyl peroxide, diisopropyl peroxydicarbonate, tertiary butyl peroxyacetate, zeta as an initiator Add shary butyl diperoxyisophthalate or azobisisobutyronitrile, etc., under an inert gas atmosphere, reaction temperature 60 ~ 200
The reaction is completed with stirring at ° C.

In bulk polymerization, it is also possible to perform polymerization by heat or light without using an initiator.

During the bulk polymerization reaction, it is usually preferable to stir effectively until the polymerization rate of the aromatic vinyl compound reaches about 30%, while the polymerization rate of the aromatic vinyl compound exceeds about 30%. After proceeding, it is preferable to moderate stirring.

At this time, a hydrocarbon solvent such as toluene, ethylbenzene or xylene may be added for the purpose of lowering the viscosity of the polymerization system.

After the completion of the polymerization, the monomer and the solvent are recovered by demonomerization and desolvation by a vented ruder or steam stripping.

Next, in the combination of bulk polymerization-suspension polymerization, first, bulk polymerization is carried out until about 10 to 45% by weight of the monomer (aromatic vinyl compound) is converted into a polymer, and this dissolution is carried out by dissolving polyvinyl alcohol, A suspension stabilizer such as methacrylate and tricalcium phosphate is dispersed in an aqueous solution in which the suspension is maintained, and the polymerization is completed at a reaction temperature of 60 to 150 ° C while maintaining the suspension state. After completion of the polymerization, the suspension stabilizer is thoroughly washed with water, removed, and dried to recover the aromatic vinyl resin.

In the radical polymerization by bulk polymerization or bulk-suspension polymerization, it is preferable that 50% by weight or more of the monomer used is the aromatic vinyl compound, and less than 50% by weight of the monomer other than the compound. It may be replaced with an aliphatic vinyl compound such as acrylonitrile, methacrylonitrile, acrylic acid, methyl acrylate, or methyl methacrylate.

In addition, the resins obtained by each of the above polymerization methods include known antioxidants such as 2,6-di-tert-butyl-4-methylphenol and 2- (1-methylcyclohexyl) -4,6-dimethyl. Phenol, 2,2'-methylene-bis (4-ethyl-6-tert-butylphenol), 4,4'-thiobis- (6-tert-butyl-3-methylphenol), dilaurylthiodipropionate, Tris (Di-nonylphenyl) phosphite, wax; known UV absorbers,
For example, p-tert-butylphenyl salicylate, 2,2 '
-Dihydroxy-4-methoxybenzophenone, 2-
(2'-hydroxy-4'-n-octoxyphenyl)
Benzothiazole; known lubricants such as paraffin wax, stearic acid, hardened oil, stearamide, methylenebis stearamide, n-butyl stearate, ketone wax, octyl alcohol, lauryl alcohol, hydroxystearic acid triglyceride; known flame retardants, For example, antimony oxide, aluminum hydroxide, zinc borate, tricresyl phosphate, tris (dichloropropyl) phosphate, chlorinated paraffin, tetrabromobutane, hexabromobenzene, tetrabromobisphenol A; known antistatic agents such as stearamide Propyldimethyl-β-hydroxyethylammonium nitrate; known colorants such as titanium oxide, carbon black, other inorganic or organic pigments; known fillers such as calcium carbonate Cium, clay, silica, glass fibers, glass spheres, carbon fibers and the like can be added if necessary.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples.
The invention is not limited by these examples.

In the examples, parts and% are based on weight unless otherwise specified.

In addition, various measurements in the examples were as follows.

That is, the microstructure of the butadiene polymer was measured by an infrared method (Morero method), and the styrene solution viscosity was measured by a Canon Fenske viscometer.

The molecular weight distribution of the butadiene polymer was measured under the following conditions using HLC-802A GPC manufactured by Toyo Soda Kogyo Co., Ltd. and a differential refractometer as a detector.

Column: Toyo Soda Industry Co., Ltd. column, GMH-3, GMH-
6 Mobile phase: Tetrahydrofuran Measurement temperature: 40 ° C. Further, regarding the molecular weight in terms of polystyrene, a monodisperse styrene polymer manufactured by Waters Co. The molecular weight in terms of polystyrene of the butadiene polymer was determined using a calibration curve for which the relationship was determined in advance.

The physical properties of the impact resistant polyethylene resin were measured according to the following methods.

Izod impact (1/4 inch, notched); 8 _OZ
Using an injection molding machine, a molded product at a cylinder temperature of 200 ° C. was measured according to ASTM D-256.

Tensile strength; Cylinder temperature 200 ℃ using 8 _OZ injection molding machine
The molded product in Example 1 was measured according to ASTM D-638.

Gloss: Using a 8 _OZ injection molding machine, the 45 ° reflection glossiness of a molded product at a cylinder temperature of 200 ° C. was measured according to ASTM D-523.

Orientation: Cylinder temperature 200 ℃ using 3.5 _OZ injection molding machine
Then, the molded product of Fig. 1 is molded, cut into strips as shown by the dotted line in Fig. 1, and Izod impact with a vertical flow notch is obtained from the sample cut as shown in (A), and (B). The Izod impact with flow parallel direction notch was measured from the sample cut as above.

In FIG. 1, reference numeral 1 is a gate through which resin is poured.

The degree of non-orientation (%) was calculated by the following formula.

Example 1 Two polymerization reactors with an internal volume of 15 and a stirrer connected in series were used. First, from the bottom of the first polymerization reactor 1,3-
Butadiene 1,500 g / hr, cyclohexane 10,500 g / hr, n
-Butyl lithium 1.00 g / hr, tetrahydrofuran 68 g / hr
Was continuously supplied using a metering pump. The inside of the polymerization reactor was kept at 90 ° C throughout.

Then, the polymerization solution polymerized by the first group was continuously supplied from the bottom of the second polymerization reactor, and at the same time, methyldichlorosilane was continuously supplied by a metering pump at 0.62 g / hr. did.

The polymerization solution continuously withdrawn from the top of the second polymerization reactor contained 0.4 parts of 2,6-di-tert-per 100 parts of the polymer.
Butyl-p-cresol was added, the resulting polymerization solution was desolvated by steam stripping, and dried on a 110 ° C. hot roll to obtain a butadiene polymer.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the butadiene polymer obtained from the first group was 35. The butadiene polymer obtained from the second group had a Mooney viscosity of 65,
The vinyl bond content of the polymer is 40%, the styrene solution viscosity is
The proportion of the polymer having a polystyrene equivalent molecular weight of 100,000 or less measured by GPC at 145 centipoise was 8%.

The coupling efficiency was calculated by the peak area ratio from the measurement chart of the gel permeation chromatography (GPC) of the polymer of the first group and the polymer of the second group according to a conventional method.

Next, using this butadiene polymer, an impact resistant styrene resin was produced by the method described below.

That is, a mixture of 10 parts of the butadiene polymer obtained above and 90 parts of styrene was stirred at room temperature for 8 hours and uniformly dissolved. This solution was transferred to a polymerization reactor with an internal volume of 10 and equipped with a stirrer, 0.05 parts of tert-dodecyl mercaptan and 0.05 part of benzoyl peroxide were added, and polymerization was carried out at 90 ° C. until the polymerization rate of styrene was about 30%. It was

Then, 0.05 part of benzoyl peroxide and 0.10 part of dicumyl peroxide were added per 100 parts of this solution, and further 2 parts of calcium triphosphate as a suspension stabilizer and 0.005 part of dodecylbenzenesulfonic acid as a surfactant. 150 parts of water containing sodium was added and suspended under stirring. The suspension mixture was heated with stirring at 100 ° C. for 2 hours, at 130 ° C. for 2 hours, and at 150 ° C. for 2 hours to polymerize.

The obtained bead-like resin was separated by filtration, washed with water, dried and pelletized with an extruder.

The styrene resin thus obtained was injection molded to prepare a test piece for measuring physical properties.

The measurement results are shown in Table 1.

Example 2 In Example 1, the feed amount of tetrahydrofuran was 32 g /
It carried out like Example 1 except having changed to hr. The results are shown in Table 1.

Example 3 In Example 1, the feed amount of tetrahydrofuran was 105 g.
It carried out like Example 1 except having changed into / hr. The results are shown in Table 1.

Comparative Example 1 As a comparative example, a butadiene polymer polymerized by a usual continuous polymerization method was produced by the following method.

That is, a polymerization reactor equipped with a stirrer with an internal volume of 15 was used, and 1,3-butadiene 1,500 g / hr, cyclohexane 10,500 g / hr, and n-butyl lithium 0.75 g / h were used from the bottom of the polymerization reactor.
It was continuously supplied using a metering pump so that r and tetrahydrofuran were 70 g / hr. 100 in the polymerization reactor from beginning to end
It was kept at ℃.

Then, the polymerization solution in which the polymerization was substantially completed was continuously withdrawn from the top of 0.4 parts of 2,6-di-ter per 100 parts of the polymer.
t-Butyl-p-cresol was added, the resulting polymerization solution was desolvated by steam stripping, and dried on a 110 ° C. hot roll to obtain a butadiene polymer.

Thereafter, graft polymerization was performed in the same manner as in Example 1 to produce a styrene resin.

Table 1 shows the physical properties of the butadiene polymer and the obtained styrene resin.

In this comparative example, a butadiene polymer having a molecular weight of 100,000 or less and a component amount exceeding the range of the present invention is used, and it can be seen that the resulting resin has poor impact strength and tensile strength.

Comparative Example 2 In Comparative Example 1, the temperature in the polymerization reactor was set to 110 ° C. and n
-Except that the supply of butyllithium was changed to 1.00 g / hr
It carried out like Comparative Example 1. The evaluation results are shown in Table 1.

This comparative example is a case where a Mooney viscosity is less than the range of the present invention and a butadiene polymer having a molecular weight of 100,000 or less and the amount of components exceeding the range of the present invention is used, and the resulting resin has poor impact strength and tensile strength. I understand.

Example 4 Cyclohexane was added to a polymerization reactor equipped with a stirrer and having an inner volume of 10.
After charging 4,000 g, 800 g of butadiene and 8 g of tetrahydrofuran, 0.40 g of n-butyllithium was added, and the inside of the polymerization reactor was adjusted to 85 ° C. to carry out polymerization for 1 hour.

The Mooney viscosity of the obtained living polymer (ML _{1 + 4} , 100
C) was 38.

Then, 0.08 g of silicon tetrachloride was added as a coupling agent and reacted for 1 hour. Further, 0.4 part of 2,6-di-tert-butyl-p-cresol was added to 100 parts of the butadiene polymer, the resulting polymerization solution was desolvated by steam stripping, and dried on a hot roll at 100 ° C. , A butadiene polymer was obtained.

The butadiene polymer had a Mooney viscosity of 70, a vinyl bond content of 40%, a styrene solution viscosity of 140 centipoise, and a component content of 100,000 or less in terms of polystyrene measured by GPC, of 4%.

The coupling efficiency is determined by gel permeation chromatography (GP
C) The peak area ratio of the high molecular weight portion and the low molecular weight portion was calculated from the measurement chart.

The same procedure as in Example 1 was carried out using this butadiene polymer. The results are shown in Table 1.

Comparative Example 3 In Example 1, the amount of tetrahydrofuran supplied was 21 g /
It carried out like Example 1 except having changed to hr. The results are shown in Table 1.

This comparative example is a case of a butadiene polymer having a vinyl bond content less than the range of the present invention, and it can be seen that the orientation property and gloss characteristics of the obtained resin are inferior.

Comparative Example 4 In Example 1, the amount of tetrahydrofuran supplied was 200 g.
It carried out like Example 1 except having changed into / hr. The results are shown in Table 1.

This comparative example is a case of a butadiene polymer having a vinyl bond content exceeding the range of the present invention, and it can be seen that the resulting resin has poor impact strength and tensile strength.

Comparative Example 5 A commercially available butadiene polymer as the butadiene polymer used in Example 1 (“DIENE55 (Asahi Kasei Kogyo Co., Ltd.)
Manufactured in accordance with the procedure of Example 1).
The results are shown in Table 1.

This comparative example is an example using a commercially available butadiene polymer, which has a vinyl bond content and a molecular weight of 100,000.
It can be seen that the amounts of the following components are out of the range of the present invention, and the physical properties of the obtained resin are all inferior.

Comparative Example 6 The procedure of Example 4 was repeated, except that the amount of the coupling agent was changed to 0.16 g. The results are shown in Table 1.

It can be seen that if the coupling efficiency is too high, the non-orientation is poor and the strength becomes non-uniform depending on the molding direction.

[Effects of the Invention] According to the present invention, an impact-resistant aromatic vinyl compound resin having an excellent balance of impact resistance, appearance characteristics and mechanical characteristics can be obtained, and its industrial significance is extremely great.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a molded article for measuring the Izod impact with a flow parallel direction notch and the Izod impact with a flow vertical direction notch. In FIG. 1, (A) shows how to make a flow vertical direction test piece, (B) shows how to make a flow parallel direction test piece, and 1 is a gate for pouring resin.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Takeuchi 2-11-24 Tsukiji, Chuo-ku, Tokyo Inside Nippon Synthetic Rubber Co., Ltd. (56) Reference JP-A-60-203618 (JP, A)

Claims (1)

[Claims] 1. A method of radically polymerizing an aromatic vinyl compound in the presence of a conjugated diene polymer, wherein the conjugated diene polymer is obtained by solution polymerization of the conjugated diene compound using an organolithium compound as a catalyst. A polymer, and the molecular weight in terms of polystyrene in the molecular weight distribution measured by gel permeation chromatography of the polymer is 100,
000 or less components are 10% by weight or less, Mooney viscosity (ML _{1 + 4} , 100 ° C) is 50 to 100, vinyl bond content is more than 35% and 50% or less, and 5% by weight styrene solution viscosity measured at 25 ° C is 100-200
A method for producing an impact-resistant aromatic vinyl-based resin, which has a centipoise and a coupling efficiency of 5% or more and less than 50%.