JP2000128908A - Styrene polymer and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a styrene polymer having high impact and fluidity by controlling the degree of branching in a wide range and independently controlling the degree of branching and the molecular weight. SOLUTION: A styrenic monomer is polymerized by a radical polymerization method by using a polyfunctional vinyl compound and a polyfunctional chain transfer agent in combination and, if necessary, using a polymerization initiator to produce a styrenic polymer. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a styrene-based polymer having a branched structure capable of controlling the degree of branching in a wide range. More specifically, the present invention relates to a method for producing a styrene-based polymer having an excellent balance between physical properties of impact strength and fluidity.

[0002]

2. Description of the Related Art Conventionally, a branched structure has been introduced into a styrene-based polymer in order to improve the fluidity and impact strength of the polymer. The purest method for producing a styrene-based polymer having a branched structure is a method of performing anionic polymerization using an alkyllithium compound. In this method, a branched styrene-based polymer can be efficiently obtained by an anionic polymerization coupling method by reacting an active terminal of a produced polymer with a polyfunctional compound. However, this method requires strict polymerization conditions.

[0003] Radical polymerization is a general industrial production method for styrene-based polymers. To obtain a styrene-based polymer having a branched structure by this method, 1) a method using a polyfunctional initiator, and 2) a multi-functional polymerization method. There are a method of copolymerizing a functional vinyl compound with a styrene monomer, and a method of using a polyfunctional chain transfer agent.

Japanese Patent Publication No. 41-19511 discloses a tetrafunctional peroxyketal such as 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane as a polyfunctional initiator. A method for obtaining a styrenic polymer using the same is disclosed. However, according to this method, the degree of branching can be controlled only in a very narrow range, only a star-shaped branched structure polymer is formed, and the length of each branch is equal to the chain length of the simultaneously formed linear polymer. Only coalescence can be manufactured.

JP-A-2-170806 discloses that a polyfunctional vinyl compound and a styrene monomer are copolymerized with heat or an initiator to obtain a styrene polymer having a wide molecular weight distribution. Exhibit high impact strength. However, in this method, when the polymerization conversion rate is increased, a crosslinking reaction with the polyfunctional vinyl compound occurs rapidly, and there is a risk of gelation, particularly when the amount of the polyfunctional vinyl compound is large. Therefore, it was difficult to independently control the molecular weight and the degree of branching. In this method, the state of branching is so-called random branching, and the length of each branch is half the chain length of the linear polymer produced simultaneously.

A method for obtaining a styrene polymer having a branched structure using a polyfunctional chain transfer agent is disclosed in Macro.
mol. chem. 178, 1403-1426 (19
77) and Macromol. chm. 178, 142
7-1437 (1977). JP-A-64-81805, JP-A-64-81806, and JP-A-1-158007 disclose a method of forming a styrene-based polymer into a branched structure by using a polyfunctional mercaptan compound. ing. Further, JP-A-7-278
No. 217 also discloses a method of using a polyfunctional initiator and a polyfunctional mercaptan compound in combination to form a styrene polymer into a branched structure. However, in any case, it is difficult to control the degree of branching. The branched structure synthesized by this method
It has a star-shaped branched structure, and the length of each branch is considered to be equal to the chain length of the linear polymer produced at the same time.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a styrenic polymer in which the degree of branching can be controlled in a wide range and the degree of branching and the molecular weight can be independently controlled, and a method for producing the same. .

Another object of the present invention is to provide a styrenic polymer which can achieve both high impact strength and fluidity at a high level, has high uniform foaming properties, and has high moldability such as sheet and container moldability, and a method for producing the same. It is in.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, radically polymerize a styrene monomer using a polyfunctional vinyl compound and a polyfunctional chain transfer agent in combination. As a result, the present inventors have found a method for producing a styrene-based polymer in which the branching parameter can be controlled in a wide range and the branching parameter and the molecular weight can be controlled independently, and the present invention has been completed.

That is, the present invention relates to a method for producing a styrene polymer, in which a styrene monomer is polymerized by using a polyfunctional vinyl compound and a polyfunctional chain transfer agent in combination. In the polymerization, an initiator may be used as necessary.
The initiator may be a peroxide. The polyfunctional vinyl compound may be used at about 1 to 700 ppm, and the polyfunctional chain transfer agent may be used at about 10 to 2000 ppm.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the degree of branching can be controlled in a wide range by using a polyfunctional vinyl compound and a polyfunctional chain transfer agent and, if necessary, using an organic peroxide. A styrene-based polymer having a branched structure whose molecular weight can be independently controlled can be produced. It is considered that the styrene-based polymer produced here contains a random branched structure, a star-shaped branched structure, and a structure in which the branched structure coexists in the same polymer molecule. Furthermore, since the length of the branch of the branched polymer has a wide distribution, the styrene-based polymer has a uniform foaming property, a low uneven thickness,
Exhibits features such as deep drawability.

[Polyfunctional vinyl compound] The polyfunctional vinyl compound is a compound having two or more vinyl groups (including allyl group and (meth) acryloyl group) and copolymerizable with a styrene monomer. If there is, there is no particular limitation. Specific examples of the polyfunctional vinyl compound include divinylbenzene, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, propylene glycol (meth) acrylate, 1,4- Alkylene glycol di (meth) acrylates such as butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di ( (Meth) acrylate, tetraethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di ( (T) Bifunctional vinyl compounds such as polyoxyalkylene glycol di (meth) acrylate such as acrylate; trifunctional such as trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate Examples include vinyl compounds and tetrafunctional vinyl compounds such as tetramethylolmethanetetra (meth) acrylate and pentaerythritoltetra (meth) acrylate. These polyfunctional vinyl compounds are used alone or in combination of two or more.

The amount of the polyfunctional vinyl compound used is 1 to 700 ppm by weight based on the styrene monomer,
Preferably 50-550 ppm, more preferably 100
About 400 ppm.

[Polyfunctional chain transfer agent] As the polyfunctional chain transfer agent, a plurality of thiol groups (for example,
And 4) having a polyfunctional mercaptan compound, for example, a compound represented by the following formula (1).

R-[(A)_m-SH]_n (1) (wherein, R is an aliphatic or aromatic carbon having 1 to 17 carbons)
A represents an organic group containing a hydrogen group or a hetero atom, and A represents an organic group.
You. S is a sulfur atom, m is 0 or 1, and n is 2 or more.
Or 3 or 4. In R, examples of the aliphatic or aromatic hydrocarbon group include:
For example, alkyl groups (methyl, ethyl, propyl,
C such as tyl group_1-17An alkyl group, preferably C _1-10Al
A cycloalkyl group (cyclopentyl,
C such as clohexyl group_4-17Cycloalkyl group, preferred
Kuha C_4-8Cycloalkyl group), alkenyl group (bi
C such as nil group and allyl group_1-17Alkenyl groups, preferably
Is C_1-10Alkenyl group), cycloalkenyl group (si
C such as clopentenyl group and cyclohexenyl group_4-17Shi
Chloroalkenyl group, preferably C_4-8Cycloalkenyl
Group), aryl group (phenyl group, tolyl group, naphthy
C such as_6-17An aryl group, preferably C_6-14Ally
Aralkyl group (benzyl group, phenethyl group, etc.)
Such as C_7-17An aryl group, preferably C_7-14Aralkyl
And the like). In addition, those containing heteroatoms
As the organic group, for example, a cyclic organic group is preferable,
Organic groups whose atoms constitute a ring are particularly preferred. This
Such organic groups include, for example, pyrrole, pyrrolidine,
Piperidine, piperazine, pyridine, triazine ring, etc.
A 5- to 8-membered heterocyclic ring containing a nitrogen atom as a hetero atom,
5 to 8 membered compound containing oxygen atom as hetero atom such as orchid
Sulfur atoms as heteroatoms such as elementary rings and thiapiran
A 5- to 8-membered heterocyclic ring, or a nitrogen atom as a hetero atom;
At least two selected from oxygen and sulfur atoms
5 to 8-membered heterocyclic ring having an atom of (e.g., oxazolidi
, Oxazolone, oxazine, oxadiazine, oki
With heteroatoms such as sadiazole and oxatriazole
A 5- to 8-membered heterocycle having a nitrogen atom and an oxygen atom,
Azan, thiazine, thiazolidine, thiazoline, thiazo
, Thiadiazine, thiadiazoline, thiadiazole
Has a nitrogen atom and a sulfur atom as hetero atoms such as
5-8 membered heterocycle, heteroatoms such as oxathiazine
5 to 8 having a nitrogen atom, an oxygen atom and a sulfur atom
Membered heterocycle, etc.). Preferred R is C
_4-8Alkyl group (neopentyl group, neohexyl group
Etc.), triazines (1,3,5-triazine etc.)
Etc. are included.

As the organic group A, for example, an alkylene group
(C such as methylene group and ethylene group _1-4Alkylene group
Oxyalkylene group (oxymethylene group, oxy
C such as ethylene group_1-4Oxyalkylene group), d
Stele group (-OCOCH_Two-, -OCOCH_TwoCH
_Two-, -OCOCH_TwoCH_TwoCH_Two-Such as C_2-6S
Ter group), cycloalkylene group (cyclohexylene
C such as a group_4-8Cycloalkylene group), arylene
And the like. Preferred organic groups A are
Group.

In the above formula (1), m is 0 or 1, n
Is an integer of 2 to 4, preferably 3 or 4.

Specific examples of the polyfunctional mercaptan represented by the formula (1) include, for example, bifunctional mercaptans (eg, ethylene glycol thiocarboxylate diester such as ethylene glycol bisthioglycolate and ethylene glycol bisthiopropionate, Diolthiocarboxylic acid diesters such as dimethylolpropanethiocarboxylic acid diesters such as methylolpropanebisthioglycolate, dimethylolpropanebisthiopropionate and dimethylolpropanebisthiobutanoate), and trifunctional mercaptan compounds such as trimethylol Propane tristhioglycolate, trimethylolpropane tristhiopropionate, trimethylolpropane tristhiobutanoate, 1,3,5-triazine-2,4,6-triti And tetrafunctional mercaptan compounds such as pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, pentaerythritol tetrakis (4-mercaptobutanate), and pentaerythritol tetrakis (6-mercaptohexanate). And the like. These polyfunctional mercaptan compounds are used alone or in combination of two or more.

The amount of the polyfunctional chain transfer agent used is 10 to 2000 ppm by weight based on the styrene monomer.
Preferably 50 to 1500 ppm, more preferably 10 ppm
It is about 0 to 1000 ppm.

The ratio between the polyfunctional vinyl compound and the polyfunctional chain transfer agent is from 1/30 to 30/1, preferably from 1/20 to 2/1.
0/1, more preferably 1/10 to 10/1 (by weight) can be used. The degree of branching can be controlled by changing the amount of the polyfunctional vinyl compound used within the above range.

[Polymerization Initiator] In the production of the styrenic polymer of the present invention, either a thermal polymerization method in which polymerization is performed without using an initiator or a polymerization method using an initiator can be used. Can be used.

As the polymerization initiator, an initiator generally used for polymerization of a styrene polymer can be used. For example,
Peroxides, azo compounds and the like can be used. The polymerization initiator may be monofunctional or polyfunctional. As the monofunctional or bifunctional peroxide among the peroxides, for example,
Ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, and 1,1-bis (t-butylperoxy) -3,3
5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, n-butyl-4,4
Peroxy ketals such as -bis (t-butylperoxy) valerate, p-menthahydroperoside,
Cumene hydroperoxide, diisopropylbenzene peroxide, 2,5-dimethylhexane-2,5
Hydroperoxides such as dihydroperoxide, t-butylcumyl peroxide, di-t-butyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5- Dimethyl-2,5-di (t-butylperoxy) hexyne-3
Dialkyl peroxides, decanoyl peroxide, m-toluoyl peroxide, lauroyl peroxide, benzoyl peroxide, 2,4-
Diacyl peroxides such as dichlorobenzoyl peroxide, peroxycarbonates such as dimyristyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-
Butyl peroxybenzoate, 2,5-dimethyl-
It is a peroxyester such as 2,5-bis (benzoylperoxy) hexane, and examples of the trifunctional or higher polyfunctional peroxide include compounds represented by the following formulas (2) to (4).

[0023]

Embedded image

Wherein R is a tertiary alkyl group. Examples of the trifunctional peroxide represented by the formula (2) include tris (t-butylperoxy) triazine and tris (t-amylperoxy). Examples include triazine, tris (di-t-butylperoxycyclohexyl) triazine, tris (dicumylperoxycyclohexyl) triazine, and the like.

[0025]

Embedded image

(Wherein R is a tertiary alkyl group or a tertiary aralkyl group, and R ₁ and R ₂ are alkyl groups having 1 to ₂ carbon atoms.) A tetrafunctional peroxide represented by the formula (3) As 2,2-
Bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-hexylperoxycyclohexyl) propane, 2,2-bis (4,4-di- t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,4-dicumylperoxycyclohexyl) propane, 2, Examples thereof include 2-bis (4,4 di-t-butylperoxycyclohexyl) butane.

[0027]

Embedded image

(In the formula, R is a tertiary alkyl group or a tertiary aralkyl group.) As the tetrafunctional peroxide represented by the formula (4),
3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-amylperoxycarbonyl) benzophenone,
Examples thereof include 3,3 ', 4,4'-tetra (t-hexylperoxycarbonyl) benzophenone and 3,3', 4,4'-tetra (t-cumylperoxycarbonyl) benzophenone.

Examples of the azo compound include 2,2-azobis (2-methylbutyronitrile) and 1,1'-azobis (cyclohexane-1-carbonitrile). These polymerization initiators are used alone or in combination of two or more.

When a polymerization initiator is used, a polyfunctional peroxide is preferably used, and more preferably a compound represented by the formula (2)
Polyfunctional peroxides represented by (4).

The polymerization initiator is added to a polymerization system (a raw material solution or a solution in the course of polymerization) in an arbitrary polymerization step of a styrene-based monomer. In general, it is added to the raw material solution for polymerization, but it may be added to the solution in the course of polymerization in a plurality of portions as necessary.

The polymerization initiator is 2,000 ppm or less, preferably 50 to 1 ppm by weight based on the styrene monomer.
500 ppm, more preferably 100-1000 ppm
It is about. [Styrene-based monomer] The styrene-based monomer constituting the styrene-based polymer of the present invention is a styrene-based monomer and, if necessary, a vinyl monomer copolymerizable therewith. The upper limit is 50% by weight.

Examples of the styrene monomer include styrene, alkyl-substituted styrene (vinyl toluene such as o-methylstyrene, m-methylstyrene and p-methylstyrene;
Vinyl xylene such as 2,4-dimethylstyrene, ethyl styrene, pt-butyl styrene, etc.), α-methyl styrene, α such as α-methyl-p-methyl styrene
-Halogen-substituted styrene such as alkyl-substituted styrene, bromostyrene, chlorostyrene, etc., 1,1-diphenylethylene, p- (N, N-diethylaminoethyl) styrene, p- (N, N-diethylaminomethyl) styrene and the like. Especially styrene, α-methylstyrene,
Vinyl toluene is preferred. These styrene monomers may be used alone or in combination of two or more.

Examples of the copolymerizable vinyl monomer include vinyl cyanide compounds such as (meth) acrylonitrile; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and amyl. (Meth) acrylate, hexyl (
Meth) acrylate, octyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, dodecyl (
(Meth) acrylic esters such as _C1-20 alkyl (meth) acrylates such as meth) acrylate and octadecyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate and benzyl (meth) acrylate; anhydrous Unsaturated acid anhydrides such as maleic acid, itaconic anhydride and citraconic anhydride; unsaturated acids such as acrylic acid and methacrylic acid; maleimide, N-
Α, such as N-alkylmaleimide such as methylmaleimide and N-butylmaleimide, N-arylmaleimide such as N- (p-methylphenyl) maleimide and N-phenylmaleimide, and N-cycloalkylmaleimide such as N-cyclohexylmaleimide. An imide compound of β-unsaturated dicarboxylic acid (maleimide-based monomer) can be exemplified.

In preparing the styrenic polymer of the present invention, the styrenic monomer is polymerized in the presence of a desired amount of the rubbery polymer, and the rubbery polymer is contained in the styrenic polymer matrix. It may be a polymer present as a dispersed phase. The content of the rubbery polymer is, for example, 2 to 40% by weight, preferably 3 to 30% by weight, and more preferably 4 to 40% by weight.
20% by weight.

A rubber-like polymer is one whose glass transition point is-
Refers to those at 30 ° C. or lower. Specific examples include diene polymers such as polybutadiene rubber, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and ethylene-propylene-diene rubber (EPD).
M), acrylic rubber, silicone rubber and the like. As the polybutadiene rubber, both high cis rubber and low cis rubber can be suitably used.
Further, as the above-mentioned polybutadiene rubber, SBR and NBR, those obtained by hydrogenating part or all of the unsaturated double bonds can be used.

The styrenic polymer of the present invention comprises a monomer containing the styrenic monomer as a main component, the above-mentioned polyfunctional vinyl compound, the above-mentioned polyfunctional chain transfer agent and, if necessary, a polymerization initiator. Lower, bulk, bulk / suspension or solution polymerization can be carried out, but generally, bulk polymerization is preferred because it is economically superior. At this time, a desired amount of a solvent such as ethylbenzene or toluene may be added to the reaction solution. The polymerization can be carried out in either a batch system or a continuous system, but the continuous system is preferred because it is economical and stable in quality. The type of the reactor is not particularly limited, and any of a plug flow type reactor and a complete mixing type reactor can be applied. The polymerization is carried out at a temperature in the range of 60 to 180 ° C according to a standard method. After completion of the polymerization, unreacted monomers and an inert solvent are removed by a devolatilizer under a high temperature and a high vacuum by a conventional method.

The weight average molecular weight Mw of the styrenic polymer obtained by the present invention is 15 to 1,000,000, preferably 18
７５750,000, more preferably about 200,000 to 500,000.
Such a polymer is preferable from the viewpoint of the balance between fluidity, moldability and impact resistance. The molecular weight distribution (ratio of weight average molecular weight Mw to number average molecular weight Mn) is 10 or less, preferably 1.5 to 7, and more preferably about 1.8 to 6.

In the present invention, the branch parameter g (= [η] _branch / [η] _linear ) is used to indicate the degree of _branch . The branching parameter is also called the shrinkage factor (Kyoritsu Shuppan, New Polymer Experiment 1, Basic Polymer Experiment, Molecular Characterization, 29
5 (1994)). That is, it is known that the spread in a dilute solution of a polymer dissolved in a good solvent or a θ solvent at a certain temperature varies depending on the structure of the polymer molecule (BH Zimm).
and W. H. Stockmayer, J .; Che
m. Phys. , 17, 1301 (1949)). For example, when comparing a linear polymer and a branched polymer having the same molecular weight, the spread of the polymer molecule having a branched structure is smaller than that of the linear polymer molecule. As a result, the intrinsic viscosity of the branched polymer and the mean square radius of rotation representing the size of the molecule are observed to be smaller than those of the linear polymer. From this, the intrinsic viscosity of the styrenic polymer of the present invention was determined under the same conditions by gel permeation chromatography (GP).
C), and the ratio of the intrinsic viscosity of the linear polymer synthesized by thermal polymerization to the intrinsic viscosity is determined by the branch parameter g (= [η] _branch /
[η] _linear ). However, the intrinsic viscosity of the linear polymer is calculated by Schultz's viscosity formula [η] = 4.9 × 1.
Based on 0 ^-3 Mw ^0.794 (Mw indicates a weight average molecular weight), the molecular weight distribution was calculated on the basis of the Schultz-Zimm exponential function.

The branching parameter g of the resulting branched styrenic polymer in the present invention _{(= [η] bran ch /} [η] linear) is preferably less than 0.5 to 0.99, more preferably 0.7 to It is about 0.98.

The styrenic polymer of the present invention has an elongation rate of 0.0025 to 0.005, which is an index of resin fluidity and moldability.
0.003sec ^-1, in measurement of extensional viscosity at 130 ° C., the slope α of the straight line plots shown in an extended strain amount ε and the logarithm of the non-linear parameter λ _n (lnλ _n) is 0.
It is a polymer having a value of 15 or more, and has good fluidity and moldability.

In the measurement of elongational viscosity, a phenomenon in which the elongational viscosity suddenly rises out of the linear region is called strain hardening. The logarithm (lnλ _n ) of the nonlinear parameter λ _n as a parameter indicating the degree of strain hardening is Hencky.
The length of the sample at the known to increase linearly with the extension strain amount ε [= ln (l / l 0)] ( where, l _0, l each extension time 0 and t [References: Kiyoto Koyama, Osamu Ishizuka; Journal of the Textile Society of Japan, 37 , T-258
(1981)]. The slope α of this straight line is an index indicating the fluidity and moldability of the resin. In the present invention, the elongational viscosity (λ) of the sample is measured, and the ratio of the obtained elongational viscosity to the elongational viscosity (λ ₁ ) of the linear region having the same elongation time is determined by a nonlinear parameter (λ _n = λ / λ ₁ ). Was used to determine the inclination α of the straight line.

[0043]

According to the present invention, the styrene monomer is polymerized using a polyfunctional vinyl compound, a polyfunctional chain transfer agent and, if necessary, a polyfunctional initiator, so that the degree of branching and the molecular weight of the styrene polymer are reduced. Can be controlled independently. Furthermore, while maintaining impact resistance, rigidity, and heat resistance, it is possible to obtain a styrene-based resin having excellent moldability such as uniform foaming properties, ease of stretching, deep drawability, and low thickness unevenness. .

[0044]

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 polymer were measured by the following methods.

(1) Weight average molecular weight The weight average molecular weight was determined by gel permeation chromatography (GPC) at 40 ° C. using chloroform as an eluent.

(2) Branching parameter g (= [η]
_branch / [η] _linear ) g = [η] _branch / [η] _linear [η] _branch is the intrinsic viscosity of the branched polymer in chloroform at 40 ° C, and [η] _linear is the weight average molecular weight Intrinsic viscosity of the same linear polymer in chloroform at 40 ° C. The intrinsic viscosity of each of the samples was determined, and was determined from the above equation.

(3) Slope of linear plot α temperature 130 ° C., elongation rate 0.0025 to 0.0035 s
The elongational viscosity was measured in the range of ec ^-1 and determined by the following equation.

Α = (ln λ _n2 −lnλ _n1 ) / (ε ₂ −ε ₁ ) λ _n = λ / λ ₁ ε = ln (l / l ₀ ) where λ _n is a non-linear parameter, and λ is a non-linear parameter. extensional viscosity in the linear region, lambda ₁ is extensional viscosity in the linear region of the lambda same extension time, epsilon elongation strain amount of Hencky, l ₀
And 1 denote the length of the sample at extension times 0 and t, respectively.

(4) Measurement of elongational viscosity Measurement temperature: 130 ° C. Strain rate: 0.0005 to 0.1 sec ^-1 Measuring equipment: MRLTEN RHOMETER (manufactured by Toyo Seiki Co., Ltd.) Measuring method: Pinch both sides of a flat measurement sample After being supported by a roller or a caterpillar, the sample was rotated at a constant strain rate to apply elongation deformation to the measurement sample, and the elongational viscosity was determined by detecting the sample cross-sectional area during deformation and the torque applied to the pinch roller or the caterpillar.

(5) Impact strength Measured with an Izod universal impact tester (manufactured by Yasuda Seiki Co., Ltd.) according to JIS K7210.

(6) Melt index Melt index according to JIS K7210
It was measured at 200 ° C. and 5 kg by R (manufactured by Takara Industry Co., Ltd.).

(7) Comprehensive Judgment Evaluation of Formability: Appearance of Sheet, Average Thickness Difference (The thickness of the formed sheet was measured at intervals of about 2 cm, and the sum of squares of the difference between the thickness at each measurement point and the average thickness was measured. The moldability was evaluated based on the overall evaluation of impact strength and the like. Judgment was made based on the following criteria. ◎ The moldability is particularly excellent. ○ Excellent moldability. × Poor moldability.

Example 1 A styrene monomer solution of a polyfunctional vinyl compound (divinylbenzene) and a polyfunctional chain transfer agent (pentaerythritol tetrakisthiopropionate) prepared in a 20 liter reaction vessel at the ratios shown in Table 1. Was charged and replaced with nitrogen, and then heated to 110 ° C. Polymerized at 110 ° C for 2 hours,
Subsequently, polymerization was carried out at 125 ° C. for 2 hours, and further at 140 ° C. for 2 hours, whereby the residual amount of the styrene monomer in the polymerization solution was reduced to 20% by weight or less. Thereafter, the unreacted monomer and the solvent in the reaction solution were devolatilized at 230 ° C. under a high vacuum to obtain a styrene resin. The conversion of styrene was 82.7%. Table 1 shows the measured physical property values.

Example 2 A monofunctional peroxide (benzoyl peroxide), a polyfunctional vinyl compound (divinylbenzene) and a polyfunctional chain transfer agent (pentaerythritol tetrakisthiopropionate) were used in the proportions shown in Table 1. Except for the above, a styrene resin was obtained in the same manner as in Example 1. Table 1 shows the measured physical properties.
Shown in

[0055] Example 3 polyfunctional peroxide (1,1-bis (t-butylperoxy) _{-3, 3,} 5-trimethylcyclohexane) and the polyfunctional vinyl compound (divinylbenzene) and polyfunctional chain transfer agents ( A styrene resin was obtained in the same manner as in Example 1 except that pentaerythritol tetrakisthiopropionate) was used in the proportions shown in Table 1. Table 1 shows the measured physical properties.
Shown in

Example 4 Table 1 shows polyfunctional peroxide (tris (t-butylperoxy) triazine), polyfunctional vinyl compound (divinylbenzene), and polyfunctional chain transfer agent (pentaerythritol tetrakisthiopropionate). A styrene resin was obtained in the same manner as in Example 1 except that the styrene resin was used in the proportions shown. Table 1 shows the measured physical property values.

Comparative Example 1 A styrene resin was obtained in the same manner as in Example 1 except that only the polyfunctional vinyl compound (divinylbenzene) was used at the ratio shown in Table 1. Table 1 shows the measured physical property values.

Comparative Examples 2 and 3 Only polyfunctional chain transfer agents (pentaerythritol tetrakisthiopropionate (Comparative Example 2) and trimethylolpropane tristhiopropionate (Comparative Example 3)) are shown in Table 1.
In the same manner as in Example 1 except that
A styrene resin was obtained. Table 1 shows the measured physical property values.

Comparative Examples 4 to 6 Peroxides (benzoyl peroxide (Comparative Example 4),
1,1-bis (t-butylperoxy) _{-3, 3,} 5-
Trimethylcyclohexane (Comparative Example 5), Tris (t-
A styrene resin was obtained in the same manner as in Example 1 except that only (butylperoxy) triazine (Comparative Example 6)) was used at the ratio shown in Table 1. Table 1 shows the measured physical property values.

[0060]

[Table 1]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J011 NB04 NB05 NB06 4J015 BA03 BA04 BA05 BA07 BA08 BA10 4J100 AB02P AB03P AB07P AB08P AB09P AB13P AB16Q AL62Q AL63Q AL66Q AL75Q BA02Q BA31P CA01 DA01 DA04 DA09 DA19 FA03 FA04

Claims (10)

[Claims] 1. A method for producing a styrene polymer in which a styrene monomer is polymerized using a polyfunctional vinyl compound and a polyfunctional chain transfer agent. 2. The method for producing a styrenic polymer according to claim 1, wherein the amount of the polyfunctional vinyl compound added is 1 to 700 ppm by weight based on the styrenic monomer. 3. The method for producing a styrenic polymer according to claim 1, wherein the amount of the polyfunctional chain transfer agent to be added is 10 to 2000 ppm by weight based on the styrenic monomer. 4. The method for producing a styrenic polymer according to claim 1, further comprising using a polymerization initiator. 5. The method for producing a styrenic polymer according to claim 4, wherein the polymerization initiator is a peroxide. 6. The amount of the polymerization initiator to be added is not more than 2000 ppm based on the weight of the styrene monomer.
The method for producing a styrene-based polymer according to the above. 7. A weight average molecular weight (Mw) of 150,000 to 10
The method for producing a styrene-based polymer according to claim 1, wherein the molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is 10 or less. 8. The branch parameter g (= [η] _branch /
[η] _linear ) (where [η] _branch is in chloroform,
Intrinsic viscosity of the branched polymer at 40 ° C., and [η]
_linear indicates the intrinsic viscosity at 40 ° C. of a linear polymer having the same weight average molecular weight as the branched polymer in chloroform. ) Is 0.5 or more and less than 0.99. 9. An elongation rate of 130 ° C. and an elongation rate of 0.0025-0.
In the measurement of the extensional viscosity in the range of 0035 sec ^-1, the nonlinear parameter λ _n (= λ / λ ₁ ) (where λ is the extensional viscosity at an arbitrary extension time, λ ₁ is the extension in the linear region having the same extensional time as λ) Of the linear plot represented by the logarithm (lnλ _n ) of the viscosity) and the elongation strain ε is 0.15.
The method for producing a styrenic polymer according to claim 1, which is as described above. 10. A styrenic polymer produced by the method according to claim 1.