JPH01172413A - Novel impact-resistant styrene resin and manufacture thereof - Google Patents

Abstract

PURPOSE:To produce a styrene resin excellent in both impact resistance and appearance, by polymerizing a specific butadiene/styrene block copolymer with a styrene monomer. CONSTITUTION:3-25% butadiene/styrene block copolymer wherein (A) the molecular weight at the peak of the molecular weight distribution curve of the copolymer is 200,000-650,000, the proportion of the distribution of the part having a molecular weight of 2/3 or below of the molecular weight at the peak is 15-30wt.% (hereinafter merely %) of the copolymer, and the content of the part having a molecular weight of 3/2 of more of the molecular weight at the peak is 10% or below of the whole copolymer, (B) the molecular weight distribution (MW/MN) is 1.1-1.9, (C) the bonded styrene content is 15-50%, (D) the block styrene content is 65% or more of the whole styrene content, and (E) the molecular weight at the peak of the molecular weight distribution curve of the block styrene section is 30,000 or more, and 97-75% styrene monomer or mixture thereof with a monomer polymerizable therewith are subjected to bulk polymerization, bulk suspension polymerization or solution polymerization to produce the title resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an impact-resistant styrenic resin with excellent impact resistance and appearance, and a method for producing the same.

[Prior art] Styrenic resins have excellent rigidity, transparency, gloss, and moldability, so they are widely used in various applications, but because of their poor impact resistance, rubber-like polymers have been modified. It is added to styrene resins as a quality agent. Examples of this method include mechanically blending a rubbery polymer with a polystyrene resin, and bulk polymerization or bulk suspension polymerization of a styrene solution of a rubbery polymer. In particular, addition by polymerization has been widely practiced industrially as impact-resistant styrenic resin, and is mainly used in household electrical appliances, since the resulting polymer has excellent physical properties.

However, due to the addition of a rubbery polymer to the above-mentioned impact-resistant styrene resin, appearance characteristics such as gloss and transparency are inevitably reduced.

In recent years, as the market has expanded its applications, there has been a strong demand for impact-resistant styrene resins with gloss and transparency that can be used in a wide variety of applications, including food packaging for frozen desserts and food containers such as beverage cups. It is requested.

One method for improving the appearance properties of impact-resistant styrenic resins is to add a block combination of monovinyl aromatic hydrocarbons and conjugated diolefin hydrocarbons to the rubber-like polymer added as an impact modifier. Methods using polymers are known.

For example, in Japanese Patent Publication No. 42-17482, block A (average molecular f
f15,000~eo, ooo) and block B consisting of a polymer of conjugated diene (average molecular weight so, ooo~5
00.000) - Precepts A-B or A-B-A
Bound styrene content 2-40% by weight, about 1-5 dR/g
An impact-resistant styrenic resin is produced by bulk polymerizing a mixture of 1 to 20% by weight of a block copolymer with an intrinsic viscosity (measured in toluene at 25°C) of 99 to 80% by weight of a vinyl aromatic monomer. A method of manufacturing is shown. It is true that when such a block copolymer is used as a rubber-like polymer, the surface gloss of the impact-resistant polystyrene resin is improved to some extent, but its impact resistance is not necessarily sufficient.

In addition, Japanese Patent Publication No. 48-16594 describes a block copolymer with 1,3-butadiene containing 30 to 45% by weight of monovinyl aromatic hydrocarbons, which has a Mooney viscosity (MLI).
-4,100℃) is 50~150.1.2 Vinyl content is 5~25%, Weight average molecular weight (hereinafter abbreviated as Few) 100,000~500,000, Number average molecular weight (hereinafter abbreviated as MN) 80,000~300.0
A method using rubbery polymers in the range of 0.00 is disclosed. However, even this method has not yet been sufficiently improved.

In addition, as a method for obtaining impact-resistant polystyrene resin with a thin layer, a certain degree of transparency, and excellent gloss, Tokko Sho GO
JP-A-57443 discloses that the weight average particle diameter of the dispersed soft component phase is 1. Specific viscosity (at 25°C in toluene) of the rubbery polymer used is limited to the following: 1.51 to 1
．． 76dR/g, bound styrene content 24-39% by weight,
Intrinsic viscosity of polystyrene part 0.28 to 0.47 dR/g
butadiene-styrene diepert floc copolymer,
Alternatively, the intrinsic viscosity is 1.8 to 2.7 dR/g, the styrene content is 32 to 70% by weight, and the intrinsic viscosity of the polystyrene part is 0.
337 to IJ7 dil/g of butadiene-styrene block copolymers are mentioned.

[Problems to be solved by the invention] When a styrene-based resin is polymerized in a region with a relatively small particle size using a rubber-like polymer as described above, impact resistance with gloss and transparency improved to some extent can be obtained. A polystyrene resin is obtained. However, this improved resin is not sufficient for use in a wide range of fields including food containers, and its impact resistance is also not sufficient to meet the requirements of various electrical products.

Furthermore, this type of rubbery polymer is more likely to become powdery than general rubbery polymers, making it difficult to handle during the production of styrenic resins, making it particularly unsuitable for production on an industrial scale.

As described above, in order to obtain an impact-resistant styrenic resin with excellent gloss and transparency, it is easy to handle, uses a toughening agent to impart sufficient impact resistance to the styrene-based resin, and has an appearance similar to that of the styrene-based resin. There is a need for rubber-like polymers that do not impair the

[Means and effects for solving the problem] Under such circumstances, the present inventors have developed a rubber to be used in order to obtain a styrenic resin that has particularly excellent appearance properties such as gloss and also has improved impact resistance. As a result of extensive and detailed study of the structures of structural polymers, especially butadiene-styrene block copolymers, we found that the above objectives were achieved by using extremely limited butadiene-styrene block copolymers. The inventors discovered that an impact-resistant styrenic resin can be obtained, leading to the present invention.

That is, 1 the present invention provides that (a) the molecular weight of the peak part of the molecular weight distribution curve of the copolymer is 200,000 to 650,000, and the content of the molecular weight part of the peak part molecular weight of 273 or less is in the entire copolymer. 15 to 30% by weight of the peak molecular weight, and further 3% of the peak molecular weight
The content of molecular weight parts of 72 or more is 10% by weight or less of the entire copolymer (b) Molecular weight distribution (Wl w /FIN) is 1.1
-1.9(c) Bound styrene content of 15 to 50% by weight (
d) Block copolymer 3 consisting of butadiene and styrene in which the block styrene content is 65% by weight or more of the total styrene content (e) The block copolymer consisting of butadiene and styrene has a molecular weight of 30,000 or more at the peak part of the molecular weight distribution curve of the block styrene part
An impact-resistant styrenic resin containing 25% by weight of a toughening agent and a method for producing the same are provided.

The present invention will be explained in detail below.

The rubbery polymer used in the present invention is a butadiene-styrene block copolymer (hereinafter abbreviated as block copolymer) having a limited structure.

The molecular weight at the peak of the molecular weight distribution curve of the block copolymer used in the present invention (hereinafter abbreviated as Mp) is 2.
00.000 to 650,000, preferably 250.000.
000 to 550.000, and the content of molecular weight parts of 2 Mp/3 or less is in the range of 15 to 30 weight %, and the content of molecular weight parts of 3 Mp/2 or more is 10 weight %.
It is as follows.

If the Mp of the block copolymer used is less than 200.000, the resulting styrenic resin will not have sufficient impact strength, and if the Mp exceeds 650.000, the styrenic resin will not be processed on an industrial scale. When producing in styrene, it takes time to dissolve in styrene, the solution becomes highly viscous, and the energy for transfer increases, which is undesirable.The content of molecular weight parts of 2 Mp/3 or less is 15% by weight. When the amount is less, the copolymer molded product tends to become powdery, resulting in poor moldability. This not only makes it difficult to industrially produce the block copolymer, but also reduces workability during the process of dissolving it in styrenic monomers during the production of impact-resistant styrenic resins, and causes problems with the inner wall surface of the mixing tank. In the manufacturing process, such as the formation of gel-like substances due to the adhesion and retention of powdered rubber-like polymers to
Furthermore, this poses a big problem in terms of quality. Furthermore, the gloss level of the resulting styrenic resin is reduced. Moreover, when it is more than 30%, the impact strength of the resulting impact-resistant styrenic resin is poor.

Further, when the content of the molecular weight part of 3 MP/2 or more is more than 10% by weight, the gloss level of the resulting styrenic resin is lowered.

Furthermore, the molecular weight of the block copolymer used in the present invention * (hereinafter referred to as Fa II/F; abbreviated as 'i N) C1.
Range of 1 to 1.9 @MII/FvlN is 1.3
If it exceeds 20%, the impact strength of the resulting impact-resistant styrenic resin decreases. Further, copolymers having less than 1.1 styrene are difficult to manufacture.The total styrene content in the block copolymer used in the present invention is in the range of 15 to 50% by weight. If the styrene content is less than 15% by weight, the resulting impact-resistant styrenic resin will have poor appearance characteristics, and if it exceeds 50% by weight, the impact strength of the resin will be poor.

Next, the block styrene content of the block copolymer used in the present invention is in the range of 65% by weight or more of the total styrene content. If it is less than 655% by weight, the surface gloss of the resulting resin will decrease, which is not preferable.

Next, the molecular weight (hereinafter S
Mp) is limited to 30,000 or more.

In this case, it is easy to control the small particle size of the rubber particles in the production of impact-resistant polystyrene resin, and
It is possible to obtain a resin with a small rubber particle size of t, o #L. If it is less than 30,000, it becomes difficult to control the rubber particle diameter of the resulting impact-resistant styrenic resin within an arbitrary range, especially in the range of relatively small rubber particle diameters.

It is known that there is a correlation between rubber particle size, gloss, and impact strength, and that the balance can be changed depending on the application.When producing impact-resistant styrene resin, the control range of the rubber particle size is It is clear that being narrow is a major drawback.

As described above, the block copolymer used in the present invention has a structure with limited molecular weight, styrene content, etc., and the value of Mp/SMp is preferably in the range of 3 to 10.

Further, the solution viscosity (5 weight % styrene solution viscosity at 25°C) is preferably 18 to 80 centivoise (cps).

Next, the content of the block copolymer in the impact-resistant styrenic resin of the present invention is in the range of 3 to 25% by weight. When the content of the block copolymer is less than 3% by weight, the effect of improving the impact resistance of the resin is not substantially observed, and when the content is more than 25% by weight, the appearance property is one of the characteristics of the resin of the present invention. This is not preferred because the improving effect of the block copolymer is reduced and it takes a long time to dissolve the block copolymer, which is disadvantageous in terms of production.

Next, we will explain the butadiene-styrene block copolymer used in the present invention and the method for measuring its constituent components.The molecular weight defined in the present invention was measured and calculated by gel permeation chromatography (hereinafter abbreviated as GPC). It is a value.

APC B constant condition measurement model Waters M-8000 type solvent
IF (tetrahydrofuran) column
DuPont crane/<-/ Kusu (ZORBAX) PSNlooo
S 2 zo / l / bar / ') S (ZORBAX) PSM'
130s 1 column temperature 35℃ Liquid flow rate 0.7 layer I! / wet in Liquid feeding pressure 800 psi Sample concentration 0.1% by weight Sample liquid amount 0.1 mg Detector Differential refractometer According to the above conditions, standard polystyrene (manufactured by Waters;
Monodisperse polystyrene molecular weight 1.74 million.

440,000, 110,000, 49,000, 6500.1650)
The retention capacity at the peak position (hereinafter referred to as V
(abbreviated as R) is determined, and a correlation curve between molecular weight and VR is plotted.

(2) Measure GPC of the Mp block copolymer, and calculate from the correlation curve based on the VR of the peak position.

■Content ratio of 2MP/3 or less, 3Mp/2 or more, and 2
Calculate each molecular weight of Mp/3 and 3 MP/2, and
/3, and vR', which corresponds to 3Mp/2, are determined from the correlation curve between molecular weight and VR.

(The ratio of the molecular weight part of 3 Mp/2 or more is determined by the GPC chart image vR'Niyori and the ratio of the molecular weight part of 3 Mp/2 or more by VR'. (A specific example is a method by integrating chart data.

(The method used is to cut out a chart and find it based on its weight.)

■Faw, M) GPC of the sample is measured in the same manner as for Mp, and calculated by the dividing method.

The division method is a general method that divides the GPC chart into units of vR and calculates the average molecular weight from the molecular weight and its content. In this case, as described on page 123, the finer the VR division width, the higher the accuracy, so in the present invention, VR was divided into 11° 87 μp (every second as retention time) for calculation. .

■A method of oxidative decomposition of SMp block copolymer with tert-butyl hydroperoxide using osmium tetroxide as a catalyst (L, M, KOLTHO-FF,
etal,, J, poly+w, Sci
, 1. 429 (194B)) was measured by GPC in the same manner as in (2). More specifically, 0.05 g of a block copolymer sample was dissolved in 10+sj' of carbon tetrachloride, and 70% of tert-butyl hydroperoxide was dissolved.
Add 18 mf of aqueous solution and 0.05% chloroform solution of osmium tetroxide 4+i), and decompose under reflux for 15 minutes in a 90°C bath. After cooling, methanol 200% was added to the solution.
mf! is added under stirring to precipitate the polystyrene component,
This is filtered through a glass filter, and the separated polystyrene component is dissolved in THF to obtain a GPC sample.

Further, the total styrene content of the block copolymer of the present invention was measured by a conventional method using an ultraviolet spectrophotometer. Similarly, the block styrene content was determined by measuring the amount of polystyrene obtained by the above-described decomposition method using tert-butyl hydroperoxide using an ultraviolet spectrophotometer, and expressed as weight % with respect to the block copolymer before decomposition.

The block copolymer used in the present invention is usually produced in a hydrocarbon solvent using an organolithium catalyst. Examples of organic lithium catalysts include n-propyllithium, 1so-propyllithium, n-butyllithium, 5ed-butyllithium, tert-butyllithium, benzyllithium, etc., but preferably n-butyllithium, 5ec -Butyllithium etc. are used. As the hydrocarbon solvent, aliphatic hydrocarbons such as butane, pentane and hexane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene are used.

The block copolymer used in the present invention can be produced by a batch polymerization method in which the organolithium catalyst is added in portions, or further, the organolithium catalyst and the monomer are added in portions. As another method,
It can be produced by a method in which a specific amount of 1,2-butadiene is contained in a hydrocarbon solvent or a 1,3-butadiene system and polymerized.

Furthermore, polar substances such as triethylamine, tri-n-butylamine, hexamethylphosphoramide, diethyl ether, and tetrahydrofuran may be added to the polymerization system.

As an example of manufacturing the block copolymer used in the present invention, a solution of about 15% by weight of butadiene and styrene in cyclohexane (5 to 30% by weight of styrene) is prepared in an autoclave.
and add 50pp+*-11000pp of tetrahydrofuran to cyclohexane. Furthermore 1.
After adding 10pp+s to 500pp layer of 2-butadiene, the temperature was raised to 40 to 80°C, and 0.05 to 0.2% by weight of n-butyllithium was added based on the amount of 70% to start the reaction. - After the completion of the reaction, immediately add styrene and continue the reaction. At this time, the maximum temperature of the reaction is 70-10
After the reaction is completed, a stabilizer is added and the solvent is separated to obtain the desired block copolymer.

The impact-resistant styrenic resin of the present invention may be obtained by any known method as long as it satisfies the requirements of the present invention, but in particular, bulk polymerization, bulk/suspension polymerization, etc. preferable.

Hereinafter, embodiments of the bulk polymerization method and the bulk/suspension polymerization method will be described.

Generally, in the bulk polymerization method, a rubbery polymer is dissolved in styrene monomer, and if necessary, a diluent such as toluene or ethylbenzene, an internal lubricant such as liquid paraffin or mineral oil, an antioxidant, mercaptans, etc. A chain transfer agent such as α-methylstyrene dimer is added, and in the case of non-catalytic polymerization, heating polymerization is usually carried out at 95 to 200°C, while in catalytic polymerization, it is generally carried out at a lower temperature, i.e., 60 to 200°C.
The polymerization operation is continued at 150° C. until the polymerization of styrene is substantially complete.

In the case of catalytic polymerization, 1,1-bis(te) is used as an initiator.
Peroxy ketals such as rt-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, di-tert-butylperoxide, 2,5-dimethyl-
2,5-di(tert-butylperoxy)hexane,
Dialkyl peroxides such as dicumyl peroxide, diacyl peroxides such as benzoyl peroxide, ta-toluoyl peroxide, lauroyl peroxide, peroxydicarbonate such as di-myristyl peroxydicarbonate, diisopropyl peroxydicarbonate, etc. Carbonates, tert-butyl baroxy isopropyl carbonate, tert-butyl peroxy acetate, di-tert-butyl peroxy isophthalate, tert-butyl peroxybenzoate, etc., oxyesters, cyclohexanone peroxide, methyl ethyl ketone peroxide, etc. hydroperoxides such as ketone peroxides, p-mentha hydroperoxide, tert-butyl hydroperoxide, cumene hydroperoxide,
Azo compounds such as azobisisobutyronitrile, azobiscyclohexane, and hebonitrile are used. These may be used alone or in combination of two or more.

Furthermore, chain transfer agents such as mercaptans, α-methylstyrene linear dimer, and terbinolene can be used as necessary.

During this bulk polymerization, known internal lubricants are often used,
For example, if 1 to 5 parts by weight of liquid paraffin is added to 100 parts by weight of the polymer and a small amount (1 to 20%) of unreacted styrene is contained in the resulting polymer after completion of polymerization, such styrene is It is desirable to remove the styrene by a method such as removal under reduced pressure or using an extrusion device designed for the purpose of removing volatile components.Agitation during such bulk polymerization is performed as necessary, but the styrene After the conversion to coalescence, that is, the polymerization rate of styrene reaches 60% or more, it is desirable to stop or moderate the stirring; excessive stirring may reduce the strength of the resulting polymer. Also, if necessary, a small amount of toluene,
Polymerization may be carried out in the presence of a diluent such as ethylbenzene, and after completion of the polymerization, these diluents may be removed by heating together with unreacted styrene.

In the bulk/suspension polymerization method, the first half of the reaction is carried out in bulk, and the second half of the reaction is carried out in suspension. That is, a styrene solution of a rubbery polymer is polymerized by heating in the absence of a catalyst or with the addition of a catalyst in the same manner as in the previous bulk polymerization, and the styrene content is usually 50% or less, preferably 10-4%.
Partially polymerize up to 0%. 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 a suspension stabilizer and a surfactant, and the second half of the reaction is completed by suspension polymerization, and finally It is washed, dried, and, if necessary, made into pellets or powder for practical use.

In addition to the above methods, useful impact-resistant styrenic resins can be obtained by conventionally known methods that have been modified and improved.

In addition, a part of the styrene forming the impact-resistant styrenic resin together with the specific block copolymer of the present invention may be replaced with a monomer other than styrene that can be radically copolymerized with styrene. The copolymerizable monomer is used in an amount of 50% by weight or less based on the total monomers including styrene. Examples of copolymerizable monomers other than styrene include monovinyl aromatic hydrocarbons such as α-methylstyrene, vinyltoluene, vinylethylbenzene, vinylxylene, and vinylnaphthalene; conjugated dienes such as butadiene and isoprene; One or more monomers selected from acrylonitrile, methyl methacrylate, maleic anhydride, etc. are used.

The impact-resistant styrenic resin of the present invention can be used as a variety of practically useful products by processing methods such as injection molding and extrusion molding. Furthermore, during processing, antioxidants may be added as necessary.
Other thermoplastic resins such as ultraviolet absorbers, flame retardants, lubricants, mold release agents, fillers, etc., such as general polystyrene, methacrylic resin, polyphenylene ether, polycarbonate, styrene-butadiene block copolymer resin, methyl methacrylate styrene copolymer It may be used in combination with a polymer resin, a maleic anhydride/styrene copolymer resin, or the like.

[Examples] Some examples are shown below to show specific embodiments of the present invention, but these are intended to explain the gist of the present invention more specifically, and are not intended to limit the present invention. isn't it.

(I) Production of butadiene-styrene block copolymer sample A block copolymer (sample A) used in the present invention was obtained by the method shown below.

An autoclave with an internal volume of 10 g was washed and dried, and after purging with nitrogen, 2800 g of previously purified and dried cyclohexane and 0.8 g of tetrahydrofuran were added, followed by 305 g of dried 1,3-butadiene. and 95 g of dried styrene were added.

Next, after heating this monomer solution to 65°C, n
-10% by weight solution of butyllithium in cyclohexane5.
2g was added to start the reaction.

After the reaction was completed, 100 g of styrene was added to restart the reaction, and 2,6-tert-4-methylphenol (BIT) was added as a stabilizer to the resulting polymer solution.
) was added in an amount of 0.6 parts by weight per 100 parts by weight of rubber, and the solvent was removed by heating with a two-roll roll.

Hereinafter, Example B was prepared using the same method under the conditions shown in Table 1.
, C, D, E, comparative examples F, G, H, I.

A block copolymer of J was obtained.

Table 2 shows the analytical values of these block copolymers.

Mp, Mw, MN, SMp, the content of molecular weight parts of 2 Mp/3 or less, the content of molecular weight parts of 3 Mp/2 or more, total styrene content, and block styrene content were measured by the methods described above.

The solution viscosity was measured by dissolving 5 parts by weight of the obtained block copolymer in 95 parts by weight of styrene and using a Cannon-Fenske viscometer at a measurement temperature of 25°C.

Furthermore, evaluation of moldability into a solid form and powderization of the block copolymer was measured under the following conditions.

[Check the appearance of compression molded product] Compression mold shape 10c+sX 10cmX 2
c+w Compression pressure: 150 kg/cm2 Compression time: 1 minute Compression temperature: 50℃ Amount of sample used: 250 g After pressure molding under the above conditions, remove the sample that protrudes from the mold, and check the appearance of the molded product visually and by touch. Based on the following criteria, the results were evaluated in three stages.

(II) Production of impact-resistant styrenic resins Impact-resistant styrenic resins were obtained by the bulk polymerization method described below using each of the blow 2 copolymers shown in Table 2.

That is, each block copolymer shown in Table 2 is uniformly dissolved in a mixture of styrene, mineral oil, and a stabilizer (Irganox 10713) in the proportions shown in Table 3.

This was transferred to a reactor equipped with a stirring device and heated at 120°C for 3 hours.
Polymerization was carried out by heating at 135°C for 2 hours, at 150°C for 2 hours, and at 170°C for 2 hours.

After removing unreacted substances from the obtained polymer at 230°C under reduced pressure,
It was pelletized using an extruder.

Izotsu impact strength is measured by thickness 3 made by compression molding.
．． Measurement was performed using a test piece of 21 intestines according to JIS K-7110.

Injection molding was carried out in a mold with a single-pin gate measuring 150 mm x 150 mm and having a thickness of 2 layers, and the average value of the gloss at the gate and the opposite side of the gate was measured according to JIS K-8741. The results obtained are shown in Table 3.

As is clear from the results of Examples 1 to 5 in Table i3, the impact-resistant polystyrene resin using the block copolymer of the present invention has particularly excellent gloss and is also a resin with improved impact strength.
It turns out that you can get

Further, when handling the block copolymer of the present invention during the production of these resins, the work was easy because it did not become powdery.

On the other hand, as shown in Comparative Examples 1 to 5, when a block copolymer outside the scope of the present invention is used, impact strength or gloss is poor, and a resin excellent in both cannot be obtained.

Furthermore, as is clear from the check evaluation results of the appearance of compression molded products of the block copolymer, the molded products of the block copolymer used in Comparative Example 3.4.5 tend to fall apart, and are difficult to dissolve in styrene. It was difficult to handle and operate.

[Effects of the Invention] The impact-resistant styrenic resin of the present invention has particularly excellent gloss and sufficient impact resistance, so it can be used in electrical products and food containers, especially those that require both appearance and impact resistance. It can be used in a wider range of fields.

Applicant: Hiki Elastomer Co., Ltd. Agent Yutaka 1) Yoshio

Claims (2)

[Claims] (1) (a) The molecular weight of the peak part of the molecular weight distribution curve of the copolymer is 200,000 to 650,000, and the content ratio of the molecular weight part of 2/3 or less of the molecular weight of the peak part is the entire copolymer. (b) The molecular weight distribution (@M@_W/@M@_N) is 15 to 30% by weight, and the content of the molecular weight part of 3/2 or more of the peak molecular weight is 10% by weight or less of the entire copolymer. 1.1
~1.9 (c) The bound styrene content is 15 to 50% by weight (d) The block styrene content is 65% by weight or more of the total styrene content (e) The molecular weight at the peak of the molecular weight distribution curve of the block styrene portion is 30,000 Block copolymer 3 consisting of the above butadiene and styrene
An impact-resistant styrenic resin characterized by containing 25% by weight. (2) (a) The molecular weight of the peak part of the molecular weight distribution curve of the copolymer is 200,000 to 650,000, and the content of the molecular weight part of 2/3 or less of the molecular weight of the peak part is the entire copolymer. (b) The molecular weight distribution (@M@_W/@M@_N) is 15 to 30% by weight, and the content of the molecular weight part of 3/2 or more of the peak molecular weight is 10% by weight or less of the entire copolymer. 1.1
~1.9 (c) The bound styrene content is 15 to 50% by weight (d) The block styrene content is 65% by weight or more of the total styrene content (e) The molecular weight at the peak of the molecular weight distribution curve of the block styrene portion is 30,000 3 of the above block copolymers consisting of butadiene and styrene
~25% by weight and 97-75% by weight of a mixture of a styrenic monomer or a monomer copolymerizable with a styrenic monomer
A method for producing an impact-resistant styrenic resin, which comprises bulk polymerization, bulk suspension polymerization, or solution polymerization.