JP2000143712A - Styrenic resin and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a styrenic resin excellent in impact strength, heat resistance and flowability by polymerising a styrenic monomer in the presence of a specific amount of a multi-functional organic peroxide and a specific amount of a multi- functional vinyl compound. SOLUTION: This method for producing a styrenic resin comprises polymerizing (A) a styrenic monomer (for example, styrene) and, if necessary, (B) 0-50 wt.% of a copolymerizable vinyl monomer in the presence of (C) a multi- functional organic peroxide in an amount of 10-500 ppm based on the component A and (D) a multifunctional vinyl compound in an amount of 1-30 ppm based on the component A. The component C is preferably a compound of the formula (R3 is H, an alkyl or an aralkyl; R4 is an alkyl or an aralkyl) [for example, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane]. The component D is preferably a di- to tetra-functional vinyl compound (for example, divinyl benzene).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene-based resin having high levels of impact resistance, heat resistance and fluidity in a well-balanced manner, and a method for producing the same.

[0002]

2. Description of the Related Art Styrene resins are excellent in moldability because of their excellent transparency and good thermal stability and fluidity during melting. In particular, it is widely used for various uses such as tableware containers, household products and home appliances. In recent years, there has been a trend in the market to switch from high-quality resins to cheaper resins for the purpose of cost savings, and even for styrenic resins, there is a demand for resins that have an excellent balance of physical properties such as heat resistance, impact resistance and fluidity. Is growing.

[0003] In styrene resins, these physical properties are contradictory to each other. For example, if the molecular weight of the polymer is increased to improve the impact strength, the fluidity decreases, and to improve the fluidity, a high temperature is used. When molding is performed, physical properties are impaired due to yellowing of the molded article, a thermal decomposition reaction, and the like. Further, when a plasticizer such as mineral oil is added to improve the fluidity, the heat resistance of the resin is reduced, or a low-molecular compound contained in the plasticizer at the time of molding contaminates the mold.
Further, as a method of improving flowability without adding an additive, a method of lowering the average molecular weight may be mentioned, but with a decrease in the average molecular weight, mechanical properties tend to decrease, and moldability and mechanical properties At present, there is no balance between physical properties and the fundamental requirements are not solved. As described above, it has been very difficult to obtain a styrene resin excellent in balance between physical properties such as impact strength, heat resistance and fluidity, which are contradictory properties.

In order to solve the above problems, Japanese Patent Publication No.
No. 61231 discloses a method for improving the balance of physical properties of a polystyrene-based polymer by including an ultrahigh molecular weight polymer in the polystyrene-based polymer. However, in this method, productivity is low due to low manufacturing temperature.

JP-A-2-182711 discloses that a polyfunctional vinyl compound such as divinylbenzene is added to an aromatic monovinyl compound and copolymerized to improve moldability and impact resistance. ing. However, even when divinylbenzene is used alone, it is difficult to achieve both high fluidity and high impact resistance at a high level, and the fluidity also strictly limits the conversion rate of the polymerization solution in the reactor. Cannot be improved without control. If the conversion rate of the polymer solution in the reactor is strictly controlled to impart high fluidity while increasing the molecular weight of the resin, gelation is promoted and the polymer solution becomes heterogeneous.

JP-A-8-59721 discloses that a specific tetrafunctional organic peroxide is added to a styrene-based monomer in an amount of 500%.
~ 2000ppm, 1 ~ 300p of polyfunctional vinyl compound
It is disclosed that a styrene-based polymer having a weight average molecular weight of 300,000 to 700,000 by adding pm is produced. But,
In this document, it is necessary to add a relatively large amount of a polymerization initiator, and there is a possibility that the strength of the polymer is reduced. In a continuous bulk polymerization, a gel may adhere to the inner wall of the plant in a continuous bulk polymerization, and the fluidity and mechanical properties may not be significantly improved.

[0007]

Accordingly, an object of the present invention is to provide a styrene resin excellent in impact strength, heat resistance and fluidity, and a method for producing the same.

Another object of the present invention is to provide a method for producing a styrene resin which can shorten the molding cycle. Still another object of the present invention is to provide a method capable of efficiently producing a styrene-based resin while suppressing the formation of a gel even in continuous bulk polymerization.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that a specific polyfunctional organic peroxide and a polyfunctional vinyl compound are used in specific amounts, respectively, to obtain a styrene-based compound. It has been found that polymerizing a monomer can improve the impact resistance, heat resistance and fluidity of a styrene resin,
The present invention has been completed.

That is, in the present invention, a polyfunctional organic peroxide having a content of 10 ppm or more and less than 500 ppm (weight basis) and a content of 1 ppm or more and 30 ppm or less based on the styrene monomer.
A styrenic resin is produced by adding less than (by weight) a polyfunctional vinyl compound and polymerizing. The polyfunctional vinyl compound may be a 2- to 4-functional vinyl compound.

The present invention also includes a styrenic resin obtained by the above method. The styrene resin may have a weight average molecular weight Mw of about 2 × 10 ⁵ to 2 × 10 ⁶ and a methyl ethyl ketone insoluble content of 2% by weight or less.

The acrylic monomer and the methacrylic monomer are collectively referred to as a (meth) acrylic monomer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The styrene resin of the present invention can be produced by polymerizing a styrene monomer in the presence of a polyfunctional organic peroxide and a polyfunctional vinyl compound.

The styrene resin can be composed of a styrene monomer alone or a copolymer, a copolymer of a styrene monomer and a copolymerizable vinyl monomer, or the like. Examples of the styrene monomer include styrene, alkylstyrene (for example, vinyltoluenes such as o-, m-, p-methylstyrene, and 2,4-dimethylstyrene, ethylstyrene, p-isopropylstyrene, and butylstyrene. And p
Alkyl-substituted styrenes such as -t-butylstyrene), α-alkyl-substituted styrenes (eg, α-methylstyrene and α-methyl-p-methylstyrene, etc.),
Examples thereof include halostyrene (for example, o-, m- and p-chlorostyrene, p-bromostyrene, and the like). These styrene monomers can be used alone or in combination of two or more. Preferred styrene monomers include styrene, vinyltoluene, α-methylstyrene and the like, and styrene is particularly preferred.

Examples of the copolymerizable vinyl monomer include, for example,
(Meth) acrylonitrile, alkyl (meth) acrylate, vinyl ester-based monomer (eg, vinyl acetate), hydroxyl group-containing monomer [hydroxy C ₁ such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc. _-4 alkyl (meth) acrylate, etc.], glycidyl group-containing monomer [glycidyl (meth) acrylate, etc.], carboxyl group-containing monomer [(meth) acrylic acid, maleic anhydride, fumaric acid, etc.], imide monomer Monomers (maleimide, N-methylmaleimide, N-phenylmaleimide, etc.). The alkyl (meth) acrylate includes methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
_C1-20 alkyl (meth) acrylates such as lauryl (meth) acrylate are included. These vinyl monomers can be used alone or in combination of two or more. The use amount of these copolymerizable monomers can be selected, for example, in the range of 0 to 50% by weight, preferably about 0 to 30% by weight.

As the polyfunctional organic peroxide as the polymerization initiator, various compounds having a plurality of peroxy groups, for example, compounds represented by the following formulas (1) to (4) can be used.

[0017]

Embedded image

(Where R¹And R^TwoAre the same or different
Represents a hydrogen atom or an alkyl group. R^ThreeAre the same or
Differently represent a hydrogen atom, an alkyl group or an aralkyl group.
Then R ^FourAre the same or different and each represents an alkyl group or an arral
Represents a kill group. R^FiveAre the same or different and are a hydrogen atom,
It represents an alkyl group or an aralkyl group. n is 2 or 3
You. In the above formulas (1) to (4), R¹And R^TwoIs preferably
Is an alkyl group, usually a tertiary alkyl group (t-butyl
Group, t-amyl group, t-hexyl group and t-octyl
T-C such as a group_4-10Alkyl group). In particular, t
C such as -butyl group_4-8Alkyl groups and the like are preferred. R
^ThreeAnd R^FiveIs preferably a hydrogen atom, an alkyl group (particularly
And C such as methyl group and ethyl group_1-4Alkyl group)
R^FourIs usually the same tertiary alkyl group or 3
Aralkyl groups (C such as 2-phenylpropyl group)_9-14
Aralkyl group). In particular, R^ThreeAs hydrogen
Atoms, methyl and ethyl are preferred;^Fouras
C such as t-butyl group_4-8Alkyl groups and the like are preferred.
R^FiveIs a C-group such as a t-butyl group._4-8Alkyl group,
C such as 2-phenylpropyl group_9-14Aralkyl groups, etc.
Is preferred. n is preferably 2.

Examples of the bifunctional or trifunctional peroxide represented by the formula (1) include di (t-butylperoxycarbonyl) benzene, di (t-amylperoxycarbonyl)
Di (t-C _{4-10 alkylperoxycarbonyl} ) benzene such as benzene and di (t-hexylperoxycarbonyl) benzene; tri (t-butylperoxycarbonyl) benzene, tri (t-amylperoxycarbonyl) benzene And tri (t-C _{4-10 alkylperoxycarbonyl} ) benzene such as tri (t-hexylperoxycarbonyl) benzene.

Examples of the trifunctional peroxide represented by the formula (2) include tris (t-alkylperoxy) triazines such as tris (t-butylperoxy) triazine and tris (t-amylperoxy) triazine. And the like. Also, tris (di-t-alkylperoxycycloalkyl) triazine such as tris (di-t-butylperoxycyclohexyl) triazine, tris (di-2-phenylpropylperoxycyclohexyl)
Tris (di-t-aralkylperoxycycloalkyl) triazines such as triazine can also be used.

Examples of the tetrafunctional peroxide of the formula (3) include 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane and 2,2-bis (4,4-di -T-amylperoxycyclohexyl) propane,
2,2-bis (4,4-di-t-hexylperoxycyclohexyl) propane, 2,2-bis (4,4-di-
bis (4,4-di-t-alkylperoxycyclohexyl) alkanes such as t-octylperoxycyclohexyl) propane and bis such as 2,2-bis (4,4-di-2-phenylpropylperoxycyclohexyl) propane (4,4-Di-t-aralkyl peroxycyclohexyl) C _2-8 alkane and the like can be exemplified. Preferred tetrafunctional peroxide (3) is 2,2-bis (4,4-di-
bis (4,4-di-t-C _4-10 alkylperoxycyclohexyl) alkanes such as t-butylperoxycyclohexyl) propane;

Examples of the tetrafunctional peroxide represented by the formula (4) include 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 3,3',
4,4'-tetra (t-amyl peroxycarbonyl)
Benzophenone, tetra (t-alkylperoxycarbonyl) benzophenone such as 3,3 ′, 4,4′-tetra (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-2) Examples thereof include tetra (t-aralkylperoxycarbonyl) benzophenone such as -phenylpropylperoxycarbonyl) benzophenone.

These organic peroxides can be used alone or in combination of two or more. In particular, it is preferable to use at least a tetrafunctional organic peroxide represented by the formula (3).
The polyfunctional organic peroxide is plural (2 or more) in one molecule.
It is possible to increase the molecular weight of the polymer because of having the functional group, and to improve the fluidity of the obtained polymer because the polymer has a partially branched structure.

The ratio of the polyfunctional organic peroxide is from 10 ppm to less than 500 ppm, preferably 50 to 400 ppm (for example, 100 to 400 ppm) based on the styrene monomer.
400 ppm) (weight basis).
Usually, it is about 50 to 350 ppm. Usage is 10
If the amount is less than ppm, the reaction rate is low and the economic efficiency is poor.
If it is more than ppm, gelation may occur in the reactor.

In the polymerization, unless the reaction is inhibited,
As the polymerization initiator, a conventional organic peroxide may be used in addition to the polyfunctional organic peroxide. Examples of such an organic peroxide include ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide, and 1,1-bis (t-butylperoxy). -3,3,5-trimethylcyclohexane,
Peroxyketals such as 1,1-bis (t-butylperoxy) cyclohexane, n-butyl-4,4-bis (t-butylperoxy) valate, cumene hydroperoxide, diisopropylbenzene hydroperoxide, , 5-dimethylhexane-2,5-
Hydroperoxides such as dihydroperoxide, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, α, α ′
Dialkyl peroxides such as -bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, benzoyl peroxide, decanoylperoxide Diacyl peroxides such as oxide, lauroyl peroxide and 2,4-dichlorobenzoyl peroxide; peroxycarbonates such as bis (t-butylcyclohexyl) peroxydicarbonate; t-butylperoxybenzoate; Dimethyl-2,
Peroxyesters such as 5-di (benzoylperoxy) hexane are exemplified. Also, hydrogen peroxide,
Persulfate (potassium persulfate, ammonium persulfate, etc.)
Such inorganic peroxides may be used in combination.

An azo compound or the like may be used as a polymerization initiator. Examples of the azo compound include azobisnitrile [for example, 2,2′-azobisbutyryl such as 2,2′-azobisisobutyronitrile (AIBN) and 2,2′-azobis (2-methylbutyronitrile). Ronitriles: 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-
2,2′-azobisvaleronitriles such as dimethylvaleronitrile); 2,2′-azobispropionitrile such as 2,2′-azobis (2-hydroxymethylpropionitrile); 1,1 ′ -1,1'-azobis-1- such as azobiscyclohexane-1-carbonitrile
Alkanenitrile, especially 1,1′-azobis-1-cycloalkanenitrile (for example, 1,1′-azobis-1-C _{5-8cycloalkanenitrile} ); 4,4′-azobis (4-cyanoknitrile) Azobiscyanocarboxylic acids such as herbic acid), azobutyronitriles such as azonitrile [2- (carbamoylazo) isobutyronitrile;
Azovaleronitriles such as 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, etc.], azobisalkanes [eg, 2,2′-azobis (2-methylpropane), 2,2′-azobis ( 2,2′-azobisC _3-10 alkanes such as 2,4,4-trimethylpentane), and dimethyl 2,2′-azobisisobutyrate.

The polymerization initiators other than such polyfunctional organic peroxides can be used alone or in combination of two or more. The polyfunctional vinyl compound used for the polymerization is not particularly limited as long as it has a plurality of unsaturated bonds, and various compounds can be used. Examples of the polyfunctional vinyl compound include aromatic compounds having a vinyl group or an allyl group (divinylbenzene,
1-allyl-3-vinylbenzene, etc.), alkenyl (meth) acrylates (such as allyl (meth) acrylate), di (meth) acrylates of polyhydric alcohols (ethylene glycol (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate
Bifunctional vinyl compounds such as acrylates and diol di (meth) acrylates such as tetraethylene glycol di (meth) acrylate; tri (meth) acrylates (trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate) Trifunctional vinyl compounds such as; tetra (meth) acrylate (tetramethylolmethanetetraacrylate,
Tetrafunctional vinyl compounds such as pentaerythritol tetra (meth) acrylate). These polyfunctional vinyl compounds can be used alone or in combination of two or more. Preferred are 2- to 4-functional vinyl compounds, particularly bifunctional vinyl compounds (such as divinylbenzene).

The ratio of the polyfunctional vinyl compound to the styrene monomer is 1 ppm or more and less than 30 ppm, preferably 5 ppm or more and less than 30 ppm, more preferably 1 ppm or less.
It can be selected from a range of about 0 ppm to less than 30 ppm (weight basis), and is usually 1 to 20 ppm (for example, 5 to 20 ppm).
pm) (weight basis). The ratio is 1 ppm
If it is less than 3, impact strength and heat resistance are not sufficient, and 3
If the content is 0 ppm or more, gelation occurs in the reactor, and there is a possibility that the generated polymerization solution becomes heterogeneous.

The ratio of the polyfunctional organic peroxide to the polyfunctional vinyl compound is as follows: the former / the latter = 100/1 to 100/5
0 (weight ratio), preferably 100/2 to 100/40
(Weight ratio), for example, 100/20 to 100
/ 50 (weight ratio).

In order to control the molecular weight of the polymer, a chain transfer agent may be added, if necessary, as long as the impact resistance, heat resistance and fluidity are not impaired. The type of the chain transfer agent is not particularly limited, and a conventional chain transfer agent can be used. For example, it is preferable to use mercaptans, styrene dimers, terpenes (such as terpinolene) and the like. As the terpene, for example, “NOFMER TP” (manufactured by NOF Corporation) or the like can be used.

The method for polymerizing the styrenic monomer is not particularly limited, and conventional polymerization methods such as bulk polymerization, solution polymerization,
Suspension polymerization, emulsion polymerization, bulk-suspension polymerization and the like can be employed. Bulk polymerization method (bulk polymerization method) advantageous for industrial production
In, a solvent may be added. The solvent is not particularly limited, and a conventional solvent such as an aromatic hydrocarbon (benzene, toluene, ethylbenzene, xylene, etc.), an alicyclic hydrocarbon (cyclohexane, etc.), an aliphatic hydrocarbon (hexane, octane, etc.) Etc.) can be exemplified.

The amount of the solvent (solvent) used is, for example, 0 to 30% by weight, preferably 5 to 2% by weight, based on the whole reaction mixture.
It can be selected from a range of about 0% by weight. Solvent ratio is 30
If the content exceeds% by weight, economic efficiency such as solvent recovery may be reduced.

The polymerization can be carried out at normal pressure or under pressure. The polymerization temperature depends on the type of polymerization method, the composition of the polymerization initiator system,
80 to 180 ° C., preferably 9 to 80 ° C., depending on the polymerization rate and the like.
It can be selected from the range of about 0 to 150 ° C. Polymerization temperature is 8
If the temperature is lower than 0 ° C., the productivity is reduced. If the temperature is higher than 180 ° C., the molecular weight of the resin is reduced, and the impact strength is lowered.

The polymerization may be carried out usually in an atmosphere of an inert gas such as nitrogen, helium, argon or the like, for example, under a flow of an inert gas. The polymer may be separated and purified, for example, after the polymerization reaction, if necessary, by diluting with a solvent and precipitating in a poor solvent, or removing volatile components such as monomers and solvents.

The styrene resin composed of the styrene polymer obtained by the above method has a weight average molecular weight Mw.
Is 1 × 10 ^{5 to} 5 × 10 ⁶ , preferably 2 × 10 ⁵ to 2
× 10 ⁶ , more preferably about 2 × 10 ^{5 to} 5 × 10 ⁵ .

The styrene resin has a resin insoluble content (methyl ethyl ketone insoluble content) of 2% by weight or less (0 to 2% by weight), preferably 1% by weight or less, more preferably 1% by weight, when dissolved in methyl ethyl ketone. Is 0.
It is about 5% by weight or less.

According to the present invention, a high-molecular-weight styrene resin having a good balance of impact resistance, heat resistance and fluidity can be produced at a low cost. For example, various molded articles such as injection molding and extrusion molding can be used for producing molded articles (especially food containers, household articles, etc.).

When a styrene resin is used for molding, various additives such as stabilizers (ultraviolet absorbers, antioxidants, etc.), lubricants, mold release agents, plasticizers, reinforcing agents, fillers, slip agents, An anti-blocking agent, a nucleating agent, a cross-linking agent, an antistatic agent, an anti-fogging agent, a flame retardant, a light-shielding agent such as titanium oxide, a coloring agent (eg, a pigment or a dye) may be added.

[0039]

According to the present invention, the styrene monomer is polymerized by using a specific polyfunctional organic peroxide and a polyfunctional vinyl compound in specific amounts, respectively, so that it is excellent in impact strength, heat resistance and fluidity. Styrene resin. When a specific polyfunctional organic peroxide and a polyfunctional vinyl compound are used, a molded article can be efficiently produced while shortening the molding cycle.

[0040]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

The physical properties of the styrene resin were measured by the following methods. (1) Measurement of Weight Average Molecular Weight The weight average molecular weight of the styrene resin was measured by gel permeation chromatography (GPC) using GPC (LC-6A) manufactured by Shimadzu Corporation, GPC column (KF-806L manufactured by Showa Denko, 3 pieces) (In series). (2) Impact strength measurement The test piece without notch was measured according to JIS K7110. (3) DuPont Impact Strength Measurement For a 3 mm thick flat plate test piece, a load of 0.0456 kgf and a punch diameter of 1 were measured using an apparatus according to JIS K5400.
The impact strength was measured under the conditions of 2.5 mm and a breaking height of 50%. (4) Tensile test Measured according to JIS K7113. (5) Melt flow rate (MFR) Measured according to JIS K7210. (6) Deflection temperature test under load Measured according to JIS K7202. (7) Measurement of Insoluble Content of Methyl Ethyl Ketone 0.5 g (W ₁ ) of a styrene resin pellet was precisely weighed, 50 mL of methyl ethyl ketone was added, and the mixture was shaken for 2 hours to dissolve. -4 ° C, 15000 rpm in a refrigerated centrifuge
and centrifuged at 20 m for 20 minutes. The supernatant was removed, and the precipitate was taken out and dried under vacuum at 60 ° C. for 3 hours, and the dry weight (W ₂ ) (g) of the insoluble matter (precipitate) was measured. The methyl ethyl ketone insoluble content was calculated according to the following formula.

Methyl ethyl ketone insoluble matter (%) = (W ₂
/ W ₁ ) × 100 Examples 1 to 3 Multifunctional organic peroxide [2,2-bis (4,4-di-t-
[Butyl peroxycyclohexyl] propane, manufactured by NOF CORPORATION, Pertetra A], a polyfunctional vinyl compound [divinylbenzene], and a styrene monomer were mixed at a ratio shown in Table 1, and the mixture was obtained in a reaction vessel (20 liter). A mixed solution and a chain transfer agent terpinolene [NOFMER TP, manufactured by NOF CORPORATION] were charged and, after purging with nitrogen, heated to the polymerization temperature shown in Table 1 until the styrene monomer in the polymerization liquid became 15% by weight or less. Polymerized (about 4 hours). The styrene-based resin was recovered by devolatilization of unreacted monomers and solvents in the reaction solution. Various physical properties were evaluated according to the measurement methods described above. Table 1 shows the results.

As comparative examples, an example in which the polyfunctional organic peroxide and the polyfunctional vinyl compound were not added (Comparative Example 1), an example in which the amount of the polyfunctional vinyl compound was increased (Comparative Example 2), and a polyfunctional organic peroxide With respect to an example in which the amount of the polyfunctional vinyl compound was increased without adding the oxide (Comparative Example 3), the reaction was performed in the same manner as in the example, and the physical properties were evaluated. Table 1 shows the results.

[0044]

[Table 1]

As is clear from the table, in Examples 1 to 3, the Izod impact strength, the DuPont impact strength, the tensile strength, the tensile elongation at break, and the melt flow rate were higher than those of a general styrene resin (Comparative Example 1). Are high, and the balance between impact properties and fluidity is excellent. In Comparative Example 2, although the balance between the fluidity and the impact strength was excellent, the insoluble matter in methyl ethyl ketone was large, and the generation of gel could not be controlled. Comparative Example 3 has excellent fluidity,
Other physical properties are inferior to the examples.

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Claims (10)

[Claims] 1. 10 ppm based on a styrene monomer
A method for producing a styrenic resin in which a polyfunctional organic peroxide of at least 500 ppm (by weight) and a polyfunctional vinyl compound of at least 1 ppm and less than 30 ppm (by weight) are added and polymerized. 2. The method according to claim 1, wherein the styrene monomer is styrene. 3. The method for producing a styrene resin according to claim 1, wherein a polyfunctional organic peroxide represented by the following formula is used. Embedded image (In the formula, R ³ is the same or different and represents a hydrogen atom, an alkyl group or an aralkyl group, and R ⁴ is the same or different and represents an alkyl group or an aralkyl group.) 4. The method according to claim ^{3, wherein} R ³ is a C _1-4 alkyl group, and R ⁴ is a tertiary alkyl group or a tertiary aralkyl group. 5. The polyfunctional organic peroxide is 2,2-bis (4,4-di-t-butylperoxycyclohexyl).
The method for producing a styrenic resin according to claim 1, which is propane. 6. The method according to claim 1, wherein the polyfunctional vinyl compound is a 2- to 4-functional vinyl compound. 7. The method according to claim 1, wherein the polyfunctional vinyl compound is divinylbenzene. 8. The styrenic monomer has a content of 50 to 40.
0 ppm (by weight) of a polyfunctional organic peroxide and 5 pp
m and less than 30 ppm (by weight) of a bi- or tri-functional vinyl compound is added and polymerized, the styrene resin weight average molecular weight Mw is 1 × 10 ^{5 to} 5 × 10 ⁶ , and the methyl ethyl ketone insoluble content is 0.5% by weight or less. A method for producing a styrene resin. 9. A styrenic resin obtained by the method according to claim 1. 10. A weight average molecular weight Mw of 2 × 10 ⁵ to 2
× 10 ⁶ , 2% by weight of methyl ethyl ketone insoluble matter
The styrenic resin according to claim 9, which is as follows.