JPS62280211A - Production of impact-resistant resin - Google Patents

Abstract

PURPOSE:To obtain the title resin excellent in impact resistance, appearance, etc., by radical-polymerizing an aromatic vinyl compound in the presence of a specified rubber-like conjugated diene polymer mixture while adjusting the particle diameter of the dispersed rubber in the formed resin to a specified value. CONSTITUTION:A rubber-like conjugated diene polymer (e.g., polybutadiene rubber) is mixed with 5-30wt% aromatic vinyl/conjugated diene block copolymer (e.g., styrene/butadiene block copolymer) having a weight-average MW of 100,000-500,000 and a ratio by weight of the aromatic vinyl compound to the conjugated diene of 36:65-70:30. While the median particle diameter of the conjugated diene polymer particle dispersed in the obtained resin is adjusted to a value in the range of 0.5-1.4mum, a monomer mixture based on an aromatic vinyl compound (e.g., styrene) is radical-polymerized in the presence of the obtained conjugated diene polymer mixture to obtain the purpose impact- resistant resin.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention a. Field of Industrial Application The present invention relates to a method for producing an impact-resistant resin, and more particularly, it relates to a method for producing an impact-resistant resin, and more particularly, it relates to a method for producing an impact-resistant resin. It consists of graft polymerizing an aromatic vinyl compound in the presence of a specific aromatic vinyl-conjugated diene block copolymer and adjusting the dispersed rubber particles in the resulting resin to a specific particle size.
This invention relates to a method for producing an impact-resistant resin with excellent impact resistance and appearance characteristics.

b. Conventional technology In general, aromatic vinyl resins such as styrene resins are
Although it has many excellent properties such as ease of flow during molding, good transparency of molded products, and good surface gloss, its major drawback is poor impact resistance.

Known methods to improve this drawback include, for example, (1) mechanically blending a rubbery polymer into a resin, and (2) grafting an aromatic vinyl compound (such as styrene) onto a rubbery polymer. .

In particular, the method (1) of graft polymerizing an aromatic vinyl compound onto a rubbery polymer is carried out by a bulk polymerization method or a bulk-suspension polymerization method. Products using styrene as a group vinyl compound are known as impact-resistant polystyrene resins, and are widely used as materials for the nozzles of home appliances such as televisions, radios, videos, and cleaners, and for the inner boxes of electric refrigerators. . In this case, it is desired that the material not only has excellent practical impact resistance, but also has good surface gloss.

Generally, the impact resistance of the resin produced by the above method is improved by increasing the amount of rubbery polymer or by increasing the particle size of the dispersed particles, but the surface gloss deteriorates.

On the other hand, by reducing the amount of the rubbery polymer or reducing the particle size of the dispersed rubber particles, the surface gloss is improved, but on the other hand, the impact resistance is significantly reduced.

As described above, since impact resistance and surface gloss are contradictory properties, it has been difficult to obtain an impact resistant aromatic vinyl resin that maintains high impact resistance and has good surface gloss.

Conventionally, methods for improving the properties of impact-resistant aromatic vinyl resins include improving the rubbery polymer used (for example, Japanese Patent Publication No. 58-4934) and making the particle size distribution of dispersed rubber particles specific. (For example, JP-A No. 59-217712,
JP-A-60-130613) and the like have been proposed.

In general, for practical impact resistance, Izotsu impact strength alone is not sufficient, and it is necessary to have excellent falling weight impact strength, but in conventional impact-resistant aromatic vinyl resins, eye shift impact strength, None showed satisfactory properties for simultaneously improving drop weight impact strength and surface gloss.

Problems to be Solved by the C0 Invention In view of the above circumstances, the present inventors aimed to obtain an impact-resistant aromatic vinyl resin with excellent isot impact strength, falling weight impact strength, and surface gloss. As a result of extensive research, we found that an aromatic vinyl compound is radically polymerized in the presence of a rubber-like conjugated diene polymer and a small amount of an aromatic vinyl-conjugated diene diblock copolymer having a specific structure, and the resulting resin is obtained. It has been discovered that the above technical problem can be solved by adjusting the dispersed rubber particles therein to a specific particle size, and the present invention has been achieved.

d. A means for solving the problems, that is, the present invention, consists of a rubber-like conjugated diene polymer; A mixture with an aromatic vinyl-conjugated diene block copolymer having a composition ratio of 35:65 to 70:30 (weight ratio),
Radical polymerization of a monomer mainly composed of an aromatic vinyl compound in the presence of a conjugated diene polymer in which the content of the aromatic vinyl-conjugated diene block copolymer in the mixture is 5 to 30% by weight. and the median particle diameter of the conjugated diene polymer particles dispersed in the resulting resin is 0.5 to 16.
The present invention provides a method for producing an impact-resistant resin, which is characterized in that the impact-resistant resin is adjusted to a range of 4 μm.

The rubbery conjugated diene polymer used in the present invention includes:
It is mainly polybutadiene rubber, obtained by polymerizing 1,3-butadiene using an organolithium compound as a catalyst for -C, with a 1,4-cis bond content of 20 to 40%, 1,2-
1.3-
Amount of 1,4-cis bond gold obtained by polymerizing butadiene 9
It is a high cis polybutadiene with an amount of 0 to 98% and a 1.2-vinyl bond amount of 1 to 5%. Especially Mooney viscosity (ML, .4
,1°. °C) is 20-70.5% styrene solution viscosity (2
5°C) of 30 to 200 can be suitably used.

Copolymers of conjugated dienes and other copolymerizable monomers can also be used.

Other copolymerizable monomers with the conjugated diene include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, vinylnaphthalene, vinylethylbenzene, vinylxylene, etc., but styrene is preferred. and is generally obtained using an organolithium compound as a catalyst, with a bound styrene content of 5 to 35%, 1.
Solution-polymerized SBR containing 20 to 40% of 4-cis bonded gold and 10 to 40% of 1.2-vinyl bonded gold can be suitably used.

The aromatic vinyl-conjugated diene block copolymer used in the present invention is (A-8). , (A-8), -8,
Various types of bronc copolymers such as (A-8), , and X (n is a number of 1 or more) can be used;
-B).

Types are preferred, particularly those where n=1. This A-
The B-type diblock copolymer can be obtained by sequentially polymerizing an aromatic vinyl compound and a conjugated diene compound using an organolithium compound according to a known method (for example, Japanese Patent Publication No. 36-19286). can.

Examples of aromatic vinyl compounds include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, vinylnaphthalene, vinylethylbenzene, vinylxylene, etc., but styrene, α-
Methylstyrene and p-methylstyrene are preferred, and styrene is more preferred.

Moreover, as a conjugated diene compound, 1,3-butadiene,
1.3-pentadiene, isoprene, 1.3-hexadiene, 2.4-hexadiene, 2.3-dimethyl-1,
3-butadiene, 2-ethyl-1゜3-butadiene, l
, 3-pentadiene, and various branched conjugated diene compounds having 4 to 7 carbon atoms, preferably 1,3-
Butadiene, isoprene, 1,3-pentadiene, particularly preferably 1,3-butadiene.

The amount of the aromatic vinyl-conjugated diene block copolymer used is 5 to 30% by weight in the conjugated diene polymer (mixture of rubber-like conjugated diene polymer and aromatic vinyl-conjugated diene block copolymer). be. Preferably 6-25% by weight
, more preferably 7 to 20% by weight. When the amount is less than 5% by weight, although it is effective in improving the falling weight impact strength, the effect of improving the isot impact strength is not sufficient. If the amount exceeds 30% by weight, the shape of the dispersed rubber particles becomes unstable during graft polymerization, resulting in only products with poor gloss.

The weight average molecular weight of the aromatic vinyl-conjugated diene block copolymer is 100,000 to 500,000, preferably 150,000 to 450,000, and more preferably 200,000 to 400,000. When the weight average molecular weight is less than 100,000, the effect of improving both the isot impact strength and the falling weight impact strength is poor. Furthermore, if the weight average molecular weight exceeds 500,000, the particle diameters of the dispersed rubber particles become irregular and giant particles are likely to be produced, so that only products with poor gloss can be obtained.

In the aromatic vinyl-conjugated diene block copolymer,
The composition ratio of aromatic vinyl and conjugated diene is 35:65-7
The weight ratio is 0:30. Preferably 40:60
~65:35, more preferably 45:55~
60:40.

When the aromatic vinyl weight is less than 35% by weight, the effect of improving both the isot impact strength and the falling weight impact strength is not sufficient. In addition, if the aromatic vinyl content exceeds 70% by weight,
During graft polymerization, the shape of the dispersed rubber particles becomes unstable, and only products with poor gloss can be obtained.

In the present invention, the aromatic vinyl-conjugated diene block copolymer is used in a specific amount, and at the same time, the average particle diameter of the rubber particles dispersed in the resulting resin is adjusted to 0.5 to 1.4 in terms of median diameter. It is necessary to set it to μm.

Preferably it is 0.6 to 1.2 μm. Median diameter is 0
．． If it is less than 5 μm, both the isot impact strength and the falling weight impact strength are poor. If the median diameter exceeds 1.4 μm, only a resin with poor surface gloss can be obtained, and the tensile strength will rapidly decrease, resulting in a resin with poor balance of physical properties.

As mentioned above, adjusting the particle size of rubber particles depends on various factors such as the shape of the stirrer in the polymerization tank, the rotation speed of the stirrer, the stirring time, and the polymerization temperature, and it cannot be determined uniquely. Although this is not possible, the particle size can be reduced by -a) stirring during graft polymerization under conditions where stress is applied to the rubber, for example by increasing the rotational speed.

Generally, since a rubbery polymer is used in the graft polymerization described above, the viscosity of the polymerization system becomes extremely high, and it is not easy to increase the stirring strength. The presence of a specific amount of the vinyl-conjugated diene diblock copolymer has the advantage that the resulting resin has a small particle size, making it easy to obtain a small particle size.

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

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, vinylnaphthalene, vinylethylbenzene, vinylxylene, etc., but preferably styrene,
α-methylstyrene and p-methylstyrene, more preferably styrene.

The mixing ratio of the conjugated diene polymer and the aromatic vinyl compound is 3 to 25% by weight for the former, preferably 5 to 15% by weight, more preferably 7 to 13% by weight, and 97 to 7% by weight for the latter.
5% by weight, preferably 95-85% by weight, more preferably 93-87% by weight. If the amount of the conjugated diene polymer used is less than 3% by weight, the impact resistance of the resulting resin will decrease, making it difficult to achieve the object of the present invention, while if it exceeds 25% by weight, the viscosity of the graft polymerization solution will be extremely low. This makes it difficult to carry out graft polymerization in practice.

The method of radical copolymerization of the aromatic vinyl compound to the specific conjugated diene polymer is not particularly limited, but for example, it may be bulk polymerization of an aromatic vinyl compound solution in which the conjugated diene polymer is dissolved. This is carried out by a radical polymerization method combining bulk polymerization and suspension polymerization.

When a conjugated diene polymer and an aromatic vinyl compound are radically polymerized by bulk polymerization, the conjugated diene polymer is dissolved in the aromatic vinyl compound, and then a molecular weight regulator is added as necessary.

Examples of molecular weight modifiers that can be used include α-methylstyrene dimer, n-decylmercaptan, tert-dodecylmercaptan, 1-phenylbutene-2-fluorene, mercaptans such as dipentene and chloroform, terpenes, and halogen compounds. .

Furthermore, a common lubricant is added to improve the moldability of the resulting resin. For example, ester lubricants such as butyl stearate and butyl phthalate, mineral oil, paraffin wax, and other lubricants used in conventional resin processing can be used.

After dissolving these molecular weight regulators and lubricants in the above polymer solution, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, methyl ethyl ketone peroxide, dicumyl peroxide, diisopropyl peroxydicarbonate,
Tertiary-butylperoxyacetate, di-tertiary-butylciba-oxyisophthalate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane or azobisisobutyronitrile, etc. The reaction is completed under an active gas atmosphere at a reaction temperature of 60 to 200° C. while stirring.

Furthermore, during bulk polymerization, it is also possible to initiate polymerization using 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%. In particular, in the present invention, the dispersed rubber particle size is within the range of the present invention. It is necessary to adjust the stirring so that the following occurs, and on the other hand, it is preferable to relax the stirring after the polymerization rate of the aromatic vinyl compound exceeds about 30%.

Further, at this time, a hydrocarbon solvent such as toluene, ethylbenzene, xylene, etc. may be added in order to reduce the viscosity of the polymerization system.

After the polymerization is completed, the monomer and solvent are recovered by removing the monomer and the solvent using a vented Ruder or steam stripping.

Next, when performing radical polymerization by a combination of bulk polymerization and suspension polymerization, first perform bulk polymerization until about 10 to 45% by weight of the monomer (aromatic vinyl compound) is converted into a polymer, and then is dispersed in an aqueous solution containing a suspension stabilizer such as polyvinyl alcohol, polymethacrylate, or tricalcium phosphate, and the polymerization is completed at a reaction temperature of 60 to 160° C. while maintaining the suspended state. After the polymerization is completed, the suspension stabilizer is thoroughly washed with water to remove it, and after drying, the aromatic vinyl resin is recovered.

In addition, when performing radical polymerization by the 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 is other than the above compound. 7 may be replaced with aliphatic vinyl compounds such as acrylonitrile, methacrylonitrile, acrylic acid, methyl acrylate, and methyl methacrylate.

In addition, known antioxidants such as 2,6-tert-butyl-4, monomethylphenol, 2-(1-methylcyclohexyl)-
4,6-dimethylphenol, 2. 2'-methylene-bis(4-ethyl-6tert-butylphenol), 4,4'-thiobis-(6-tert-butyl-3-methylphenol), dilaurylthiodibropiofut, tris(di-nonylphenyl ) phossuite,
Wax; known UV absorbers such as p-tert-
Butylphenyl salicylate, 2,2'-dihydroxy-4-methoxybenzophenone, 2-(2'-hydroxy-4'-n-octoxyphenyl)benzothiazole; known lubricants such as paraffin wax, stearic acid, hydrogenated oils. , stearamide, methylene bisstearamide, n-butyl stearate, ketone wax, octyl alcohol, lauryl alcohol, hydroxystearic acid triglyceride; known flame retardants such as antimony oxide, aluminum hydroxide, zinc borate, tricresyl phosphate, Chlorinated paraffins, tetrabromobutane, hexabromobenzene, tetrabromobisphenol A; known antistatic agents, such as stearamide propyl dimethyl-β-hydroxyethylammonium nitrate; known colorants, such as titanium oxide, carbon black, Other inorganic or organic pigments; known fillers such as calcium carbonate, clay, silica, glass fibers, glass spheres, carbon fibers, etc. can be added as required.

e. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

In the examples, unless otherwise specified, parts and % indicate parts by weight and % by weight.

Moreover, various measurements in the examples were performed in accordance with the following.

The microstructure of the polybutadiene rubber was measured by an infrared method (Morello method), and the styrene solution viscosity was measured by a Cannon-Fenske viscometer.

The amount of bound styrene in the styrene-butadiene broth copolymer was determined by measuring the intensity of the infrared absorption peak due to phenyl groups at a wave number of 699 am-', and determining the amount from a previously determined calibration curve.

Moreover, the molecular weight distribution of the styrene-butadiene block copolymer was measured using HLC-802A type GPC manufactured by Toyo Soda Kogyo ■ under the following conditions.

Column 2 Toyo Soda Kogyo Column G-4000HX
L Mobile phase: Tetrahydrofuran sample concentration = 0.1% by weight Measurement temperature = 40"C Detector: Differential refractometer Weight Based on the molecular weight distribution obtained in the above measurement, water's monodisperse styrene polymer The weight average molecular weight of the styrene-butadiene block copolymer in terms of polystyrene was determined using a calibration curve in which the relationship between the peak molecular weight of the monodisperse styrene polymer and the GPC count number was determined in advance by GPC. I asked for

The physical properties of the impact-resistant polystyrene resin were measured according to the following method.

Eye shift impact strength C'A inch, with notch); 8o
A molded product obtained by molding using a Z injection molding machine at a cylinder temperature of 200°C was measured according to ASTM D-256.

Tensile strength: Using an 8o2 injection molding machine, cylinder temperature 2
For molded products obtained by molding at 00°C, ASTM
Measured according to D-638.

Gloss: Using an 8o2 injection molding machine, cylinder temperature 200
ASTM D-
The 60° reflective gloss was measured according to 523.

Falling weight impact strength: Molded product 40m x 3Qmm x 3 using an 8゜2 injection molding machine at a cylinder temperature of 200"C
Using a Qm square plate and an Ikg striking core, calculate the energy (height x weight of the weight) when a crack occurs in the sample.

Median particle size measurement of dispersed rubber particles; resin pellets 1~
Place 2 tablets in about 50 ml of dimethylformamide and leave for about 3 hours. Next, electrolyze this dimethylformamide solution! <l5OTON■■) and measured with a Coulter counter to obtain an appropriate particle concentration, and the 50% median diameter was calculated from the obtained particle size distribution.

The properties of the polybutadiene rubber and styrene-butadiene-Bronok copolymer used in the Examples and Comparative Examples are shown in Tables 1 and 2.

Table-1 PBD-A: City version low cis polybutadiene DIE
NE 35 (manufactured by Asahi Kasei) PBD-B: City version high system BRUBEPOL 15H
B (manufactured by Ube Kosanen) Table 2 □□□ Honey Example 1 A mixture of polybutadiene, styrene-butadiene block copolymer and styrene having the composition shown in Table 3 was stirred at room temperature for 8 hours to uniformly dissolve it. did. This solution has an internal volume of 5
Transfer to a polymerization reactor equipped with a stirrer in step 1, and add 1 part of white mineral oil, 0.04 part of tert-dodecyl mercaptan, and 0.04 part of benzoyl peroxide, and the polymerization rate of styrene will be about 25% at 95°C. It was polymerized until In addition, the stirring rotation speed was 8 times so that the diameter of the dispersed rubber particles was 0.7 μm.

Then, 2,5-dimethyl-2 per 100 parts of this solution
, 0.08 parts of 5-di(t-butylperoxy)hexane, and further contains 2 parts of tricalcium phosphate as a suspension stabilizer and 0.005 parts of sodium dodecylhenzenesulfonate as a surfactant. 150 parts were added and the solution was suspended with stirring. While stirring this suspension mixture, 1
4 hours at 20°C, 2 hours at 140°C, 2 hours at 160°C
Polymerization was carried out by heating for a period of time.

The resulting bead-shaped resin was filtered, washed with water, dried, and pelletized using an extruder. The impact-resistant styrene resin thus obtained was injection molded to prepare test pieces for measuring physical properties.

Table 3 shows the measurement results for each physical property.

Examples 2 to 4, Comparative Examples 1 to 2 In the same manner as in Example 1, polybutadiene rubber, styrene-butadiene blank copolymer, and
An impact-resistant polystyrene resin was obtained from a monomer mixture consisting of styrene. Dispersed rubber particle size is 0.5 to 1.4 μ
The stirring rotation speed was adjusted so that the stirring speed was 100 m.

Table 3 shows the measurement results for each physical property.

As is clear from the results of Examples 1 to 4 shown in Table 3,
It can be seen that the resin of the present invention obtained by using a specific amount of a specific styrene-butadiene block copolymer is excellent in all of eye shift impact strength, falling weight impact strength, and gloss. On the other hand, as is clear from Comparative Example 1 shown in Table 3, when the amount of styrene-butadiene block copolymer used was less than the range of the present invention, the eye shift impact strength was poor, and the styrene-butadiene block copolymer It can be seen that the resin obtained in Comparative Example 2, in which the proportion of the copolymer used exceeds the range of the present invention, has poor gloss.

Comparative Examples 3 to 6 In the same manner as in Example 1, polybutadiene rubber, styrene-butadiene block copolymer, and
A monomer mixture consisting of styrene was polymerized by adjusting the stirring rotation speed so that the median particle size of dispersed rubber particles was 0.4 to 1.7 μm to obtain an impact-resistant polystyrene resin.

Table 4 shows the measurement results for each physical property.

As is clear from Table 4, even if a specific styrene-butadiene block copolymer is used in a limited amount within the range of the present invention, the median particle size of the dispersed rubber particles is less than the range of the present invention. It can be seen that Comparative Example 3 has poor eye impact strength and falling weight impact strength, and Comparative Example 4, in which the median particle size of the dispersed rubber particles exceeds the range of the present invention, has poor gloss and tensile strength.

Furthermore, from Tables 3 and 4, when using the specific styrene-butadiene block copolymer of the present invention, the median particle diameter of the dispersed rubber particles must be within the range of the present invention. However, in Comparative Examples 5 and 6, which did not use the specific styrene-butadiene block copolymer of the present invention, impact resistance improved when the median particle size of the dispersed rubber particles was reduced. It can be seen that the value decreases significantly.

Examples 5-6, Comparative Examples 7-10 Regarding the styrene-butadiene block copolymer, polybutadiene rubber with the composition shown in Table 5, styrene-butadiene block copolymer, A monomer mixture consisting of styrene was polymerized by adjusting the stirring rotation speed so that the median particle size of the dispersed rubber particles was 0.5 to 1.4 μm to obtain an impact-resistant polystyrene resin.

Table 5 shows the measurement results for each physical property.

As is clear from Table 5, the resins of Examples 5 and 6, in which the weight average molecular weight of the styrene-butadiene block copolymer and the amount of bound styrene are within the range of the present invention, have Izot impact strength, falling weight impact strength, It can be seen that both gloss levels are excellent.

On the other hand, when the resin of Comparative Example 7 in which the weight average molecular weight of the styrene-butadiene Pronk copolymer was less than the range of the present invention, both the isot impact strength and the falling weight impact strength were inferior, and the It can be seen that the resin of Comparative Example 8, which exceeds the range, has poor gloss.

Comparative Example 9, in which the composition ratio of styrene and getadiene in the styrene-butadiene block copolymer is less than the range of the present invention, is a comparative example that is inferior in both isot impact strength and falling weight impact strength, and is beyond the scope of the present invention. It can be seen that in No. 10, the shape of the dispersed comb particles becomes unstable and the gloss is poor.

Example 7, Comparative Example 11 Polybutadiene rubber and styrene rubber having the composition shown in Table 6 were prepared in the same manner as in Example 1, except that the species of polybutadiene rubber used [1-PBD-8 was changed] - An impact-resistant polystyrene resin was obtained from a monomer mixture consisting of a butadiene block copolymer and styrene.

Table 6 shows the measurement results for each physical property.

As is clear from Table 6, when the specific styrene-butadiene prosol copolymer of the present invention was used in a limited amount in place of the type of polybutadiene rubber used, the Izot impact strength, drop strength, It can be seen that it is excellent in both weight impact strength and gloss.

Table 6 Example 8, Comparative Example 12 The rubber-like polymer used was solution polymerized SBR (T manufactured by Asahi Kasei).
ofdene-2000: 25% bound styrene, Mooney viscosity 46.4'I11. Viscosity (5% styrene cp
s) 52.1,2-vinyl bond 1t13%, 1,4-
Solution-polymerized SBI? with the composition shown in Table 7 was carried out in the same manner as in Example 1, except that the amount of cis-bond gold was replaced with 34%). An impact-resistant polystyrene resin was obtained from a monomer mixture consisting of , styrene-butadiene block copolymer, and styrene.

Table 7 shows the results of measuring various physical properties of the resulting impact-resistant polystyrene resin.

As is clear from Table 7, even if the rubbery polymer used is replaced with styrene-butadiene copolymer rubber, the product using a specific amount of the specific styrene-butadiene block copolymer of the present invention is Impact strength, falling weight impact strength,
It can be seen that the gloss is excellent in all respects.

f1 Effect of the invention According to the invention, a specific aromatic vinyl-conjugated diene block copolymer is used as a part of the conjugated diene polymer, and the median particle diameter of the conjugated diene polymer particles dispersed in the resin is By controlling the amount within a specific range, it is possible to obtain an impact-resistant aromatic vinyl resin with excellent impact resistance and appearance characteristics, and its industrial significance is extremely large.

Claims (1)

[Claims] (1) A rubber-like conjugated diene polymer, [1] having a weight average molecular weight of 100,000 to 500,000, and [
2] The composition ratio of aromatic vinyl compound and conjugated diene is 35
:65 to 70:30 (weight ratio) with an aromatic vinyl-conjugated diene block copolymer, and the content of the aromatic vinyl-conjugated diene block copolymer in the mixture is 5 to 30. % by weight of a monomer mainly composed of an aromatic vinyl compound in the presence of a conjugated diene polymer, and the median particle diameter of the conjugated diene polymer particles dispersed in the resulting resin is 0. A method for producing an impact-resistant resin, the method comprising adjusting the impact-resistant resin to a range of .5 to 1.4 μm.