JPH06293815A - New maleimide copolymer and its production - Google Patents

Abstract

PURPOSE:To obtain a new maleimide copolymer having excellent moldability, impact resistance, etc., by carrying out radical copolymerization of a monomer component having a specific composition in an organic solvent and removing volatile component from the reaction mixture under specific condition. CONSTITUTION:A monomer component composed of (A) 20-80wt.% of an aromatic vinyl monomer, (B) 20-60wt.% of a maleimide-type monomer, (C) 0.005-0.1wt.% of divinylbenzene monomer and (D) 0-30wt.% of other vinyl monomer (the sum of A to D is 100wt.%) is subjected to radical copolymerization in an organic solvent. Volatile components are removed from the reaction mixture under a condition to keep the produced maleimide copolymer in molten state to obtain the objective copolymer composed of 35-70wt.% of the unit derived from the component A, 30-65wt.% of the unit derived from the component B, 0.01-0.1wt.% of the unit derived from the component C and 0-30wt.% of the unit derived from the component D, having a weight-average molecular weight of 100,000-350,000 in terms of polystyrene determined by gel permeation chromatography and free from component insoluble in THF.

Description

Detailed Description of the Invention

[0001]

This invention relates to a novel aromatic vinyl monomer unit (A), a maleimide monomer unit (B) and a divinylbenzene monomer unit (C) as essential structural units. The present invention relates to a maleimide copolymer and a method for producing the same. More specifically, the present invention relates to heat resistance, impact resistance,
As a constituent raw material of a molding material with excellent thermal stability,
The present invention relates to a novel maleimide copolymer useful as a material for improving various properties such as heat resistance when blended with a thermoplastic resin, and a method for producing the same.

[0002]

2. Description of the Related Art Maleimide-based copolymers are used as raw materials for forming molding materials having excellent heat resistance, impact resistance, thermal stability, etc.
It is also known to be useful as a material for improving various properties such as heat resistance by blending with a thermoplastic resin. Among the maleimide-based copolymers, the copolymers having a maleimide-based monomer unit and an aromatic vinyl-based monomer unit as essential structural units are heat-resistant, impact-resistant, AS resin, A
It has excellent compatibility with BS resin and is particularly useful.

However, in order to produce such a maleimide-based copolymer, when the radical copolymerization of a monomer component essentially containing a maleimide-based monomer and an aromatic vinyl-based monomer is carried out, these maleimides are used. Since the alternating monomer and the aromatic vinyl monomer have high alternating copolymerizability, an alternating copolymer having a molar ratio of 1: 1 between the maleimide monomer unit and the aromatic vinyl monomer unit is Obtained preferentially. Since this 1: 1 alternating copolymer has a high heat distortion temperature, it requires an extremely high temperature for melt molding and has the drawback of being brittle.

Therefore, various production methods have been investigated in order to suppress the formation of 1: 1 alternating copolymers as much as possible. For example, a method of carrying out polymerization while feeding a maleimide-based monomer into a reaction system containing a vinyl-based monomer mainly containing an aromatic vinyl-based monomer (JP-A-58-162616).
(See Japanese Patent Publication) and the like are proposed.

[0005]

However, as described above,
A conventional method for suppressing the formation of an alternating copolymer having a molar ratio of 1: 1 of a maleimide-based monomer unit and an aromatic vinyl-based monomer unit is a copolymer excellent in heat resistance and moldability. However, even if the copolymer is blended with a thermoplastic resin to form a resin composition, the mechanical strength and heat resistance of the composition cannot be sufficiently improved.

Therefore, the present invention is excellent in moldability, impact resistance, thermal stability and the like and, when used as a constituent component of a resin composition, has sufficient mechanical strength and heat resistance. An object of the present invention is to provide a novel maleimide-based copolymer that can be improved and a method capable of producing this copolymer.

[0007]

In order to solve the above problems, the inventors have made various studies. As a result, when a divinylbenzene monomer is added to the aromatic vinyl-based monomer and the maleimide-based monomer at a specific ratio and these are copolymerized, the above-mentioned maleimide-based copolymer is obtained. After confirming this through experiments, the present invention was completed.

That is, the novel maleimide-based copolymer according to the present invention comprises 35 to 70% by weight of the structural unit (A) derived from the aromatic vinyl-based monomer (a) and the maleimide-based monomer (b). 30 to 65% by weight of the structural unit (B) derived from the above, 0.01 to 0.1% by weight of the structural unit (C) derived from the divinylbenzene monomer (c), and the above-mentioned monomers (a) and (b). ), The structural unit (D) derived from the other vinyl-based monomer (d) copolymerizable with (c) is composed of 0 to 30% by weight (however, these structural units (A) and (B)). ,
(The total of (C) and (D) is 100% by weight), the polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography is 100,000 to 350,000, and substantially contains a component that does not dissolve in tetrahydrofuran. A copolymer having a molecular weight retention at 280 ° C. of 80% or more.

The method for producing a maleimide copolymer according to the present invention is a method for producing the above novel maleimide copolymer, which comprises aromatic vinyl monomer (a) 20-80. % By weight, maleimide-based monomer (b) 2
0-60% by weight, divinylbenzene monomer (c) 0.0
05 to 0.1% by weight and 0 to 30% by weight of another vinyl-based monomer (d) copolymerizable with these monomers (however,
The total of the monomers (a), (b), (c) and (d) is 100.
(% By weight) is subjected to a radical copolymerization reaction in an organic solvent, and then a volatile component and a maleimide copolymer are melted from the reaction mixture containing the produced maleimide copolymer. By removing under the following conditions,
This is a method for obtaining a maleimide-based copolymer.

The structural unit (A) contained in the maleimide-based copolymer of the present invention is derived from the aromatic vinyl-based monomer (a). The ratio of (A) in the structure of the maleimide-based copolymer is 35 to 70% by weight, preferably 35 to 6%.
It is 0% by weight. When the ratio of (A) is within these ranges, the moldability and impact resistance are good. But,
When the proportion of (A) is less than 35% by weight, moldability or impact resistance is lowered, and when the proportion of (A) is more than 70% by weight, heat resistance is lowered and the resin is blended with a thermoplastic resin. In that case, the compatibility may decrease, which is not preferable.

The structural unit (B) contained in the maleimide-based copolymer of the present invention is derived from the maleimide-based monomer (b). The proportion of (B) in the structure of the maleimide-based copolymer is 30 to 65% by weight, preferably 40 to 65.
% By weight. When the ratio of (B) is within these ranges, the copolymer has excellent heat resistance and thermal stability and is useful as a resin modifier. However, when the proportion of (B) is less than 30% by weight, when the copolymer is blended as a constituent component of the resin composition, it becomes impossible to impart sufficient heat resistance to the composition, and (B) If the ratio exceeds 65% by weight, moldability of the copolymer deteriorates and impact resistance decreases, which is not preferable.

The structural unit (C) contained in the maleimide copolymer of the present invention is derived from the divinylbenzene monomer (c). The proportion of (C) in the structure of the maleimide-based copolymer is 0.01 to 0.1% by weight, preferably 0.01 to 0.05% by weight. When the ratio of (C) is within these ranges, the thermal stability, mechanical strength and moldability are excellent. However, if the ratio of (C) is less than 0.01% by weight, the effect of improving mechanical strength and heat resistance is not sufficient, and if the ratio of (C) exceeds 0.1% by weight, it dissolves in tetrahydrofuran. The content of the components that are not used is increased, and the moldability and impact resistance are impaired, which is not preferable.

The maleimide type copolymer of the present invention may be composed of only the structural units (A), (B) and (C), or if necessary, the structural unit (A),
It may have a structural unit (D) in addition to (B) and (C). The structural unit (D) is the monomer (a),
It is derived from another vinyl-based monomer (d) copolymerizable with (b) and (c). In the structure of the maleimide-based copolymer,
The proportion of (D) is 0 to 30% by weight, preferably 0 to 25% by weight. When the ratio of (D) is within these ranges, properties such as reactivity, compatibility or solvent resistance can be imparted without impairing moldability, impact resistance or heat resistance. However, if the ratio of (D) exceeds 30% by weight, it becomes difficult to obtain a balance of physical properties such as moldability, impact resistance or heat resistance, which is not preferable.

The structural units (A), (B), (C) and (D) occupying in the maleimide type copolymer described above.
The sum of the ratios is 100% by weight. The maleimide-based copolymer of the present invention has a weight average molecular weight of 100,000 to
It is within the range of 350,000. This is because when the weight average molecular weight is within this range, the maleimide copolymer is excellent in moldability and thermal stability during molding, and has a good balance of heat resistance and mechanical strength. If the weight average molecular weight is less than 100,000, sufficient mechanical strength cannot be obtained, and if the weight average molecular weight exceeds 350,000, the moldability is deteriorated, which is not preferable.

In this specification, the weight average molecular weight of the maleimide copolymer is a polystyrene-equivalent value measured by gel permeation chromatography (also called gel permeation chromatography, GPC). The maleimide-based copolymer of the present invention is tetrahydrofuran (TH
It does not substantially contain components that do not dissolve in F). Here, that the maleimide-based copolymer does not substantially contain a component that is insoluble in tetrahydrofuran means that 3 g of the copolymer is mixed and dissolved in 27 g of tetrahydrofuran,
This means that no insoluble matter was observed when visually observed. If the insoluble content is substantially absent, the moldability is good, but if the insoluble content is contained, the moldability and impact resistance are deteriorated.

The maleimide type copolymer of the present invention is 28
It has a molecular weight retention rate of 80% or more at 0 ° C.
Here, the molecular weight retention is measured by using a differential thermal balance, by heating the copolymer at 280 ° C. for 10 minutes under a reduced pressure condition (20 mmHg or less), and then rapidly cooling the copolymer. It is the ratio of the value to the value before processing. That is, the maleimide-based copolymer of the present invention is excellent in thermal stability, and even after holding at 280 ° C. for 10 minutes,
Almost no decrease in the molecular weight occurs, and the molecular weight retention rate is 80% or more, preferably 90% or more, as compared with that before the heat treatment.

The aromatic vinyl monomer (a) in the present invention is not particularly limited, but for example, the following formula:

[0018]

[Chemical 1]

(In the formula, R ¹ , R ² and R ³ each independently represent hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ⁴
Represents an aryl group or a substituted aryl group. ) And the like. Examples of the compound represented by the above formula include styrene (hereinafter, this may be referred to as “St”); o-methylstyrene, m-methylstyrene, p-methylstyrene (o-, m-, p -Methylstyrene is also referred to as vinyltoluene), 1,3-dimethylstyrene, 2,4-dimethylstyrene, ethylstyrene, alkylstyrene such as p-tertiary butylstyrene;
α-Methylstyrene, α-ethylstyrene, α-methyl-p-methylstyrene, vinylnaphthalene; halogenated styrene such as o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dibromostyrene; Examples thereof include halogenated alkylstyrenes such as 2-methyl-4-chlorostyrene. One or more of these can be used. From the viewpoint of the balance between productivity and physical properties, it is particularly desirable to use at least one of styrene and α-methylstyrene. When an aliphatic vinyl-based monomer is used instead of the aromatic vinyl-based monomer, the reactivity of the monomer becomes low, and the resulting copolymer has low heat resistance and moisture absorption. It has a great effect.

The maleimide type monomer (b) in the present invention is not particularly limited, but for example, the following formula:

[0021]

[Chemical 2]

(In the formula, R ⁵ is hydrogen or a carbon number of 1 to
15 is an alkyl group, a substituted alkyl group, a cycloalkyl group, a substituted cycloalkyl, an aryl group or a substituted aryl group. ) And the like. Examples of the compound represented by the above formula include maleimide, N-methylmaleimide, N-ethylmaleimide and N.
-Propylmaleimide, N-isopropylmaleimide,
N-butyl maleimide, N-isobutyl maleimide, N
-T-butylmaleimide, N-cyclohexylmaleimide (hereinafter this may be referred to as "CHMI"), N
-Phenylmaleimide (hereinafter sometimes referred to as "PMI"), N-chlorophenylmaleimide, N-methylphenylmaleimide, N-bromophenylmaleimide, N-naphthylmaleimide, N-laurylmaleimide, 2-hydroxyethyl Maleimide, N-hydroxyphenyl maleimide, N-methoxyphenyl maleimide, N-carboxyphenyl maleimide, N-nitrophenyl maleimide, etc. are mentioned. One or more of these can be used. In particular, the use of either one or both of N-cyclohexylmaleimide and N-phenylmaleimide provides a copolymer that is easily available and has excellent heat resistance.
preferable.

The divinylbenzene monomer (c) in the present invention is a compound represented by the following formula: o-, m
-, P- isomers are included.

[0024]

[Chemical 3]

The copolymer having the structural unit (C) derived from the divinylbenzene monomer (c) has particularly good thermal stability, and is generally used for physical properties in the process of removing volatile components while heating. Is less likely to decrease. When a polyfunctional monomer other than divinylbenzene, which is generally used in radical polymerization, is used, the thermal stability of the copolymer is deteriorated. Therefore, molded products blended with this copolymer have sufficient heat resistance and resistance. Impact and mechanical strength are not given.

In the present invention, other vinyl-based monomer (d) copolymerizable with the above-mentioned monomers (a), (b) and (c) can be used if necessary. The monomer (d) is a compound having an ethylenically unsaturated bond other than the monomers (a), (b) and (c), and has, for example, impact resistance, solvent resistance and compatibility. Used for the purpose of improving. Although the monomer (d) is not particularly limited, for example, acrylonitrile (hereinafter, referred to as “A
N)), unsaturated nitriles such as methacrylonitrile, ethacrylonitrile, phenylacrylonitrile; and cycloalkyl groups and benzyl groups.
(Meth) acrylic acid ester having an alkyl group having 1 to 18 carbon atoms (for example, methyl (meth) acrylate,
Ethyl (meth) acrylate, Butyl (meth) acrylate, Isobutyl (meth) acrylate, t-Butyl (meth) acrylate, Amyl (meth) acrylate, Isoamyl (meth) acrylate, Octyl (meth) acrylate ,
2-Ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, (meth)
Cyclohexyl acrylate, benzyl (meth) acrylate, etc .; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol (meth) acrylate; ethylene, propylene,
Olefins such as isobutylene and diisobutylene; dienes such as butadiene and isoprene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl ethers such as methyl vinyl ether and butyl vinyl ether; vinyl acetate , Vinyl esters of saturated monocarboxylic acids such as vinyl propionate; allyl esters or methallyl esters of saturated aliphatic monocarboxylic acids such as allyl acetate and allyl propionate; glycidyl (meth) acrylate, allyl glycidyl ether, (meth ) Acrylic acid, itaconic acid, maleic acid,
Examples include fumaric acid and half-esterified products thereof. These may be used alone or in combination of two or more, and the type may be selected within the range not departing from the object of the present invention.

In order to produce the maleimide-based copolymer of the present invention, the above-mentioned monomers (a), (b) and (c) and, if necessary, the monomer (d) used are copolymerized. Let At that time, the amount of the monomer (a) used is preferably 20 to 80% by weight. The amount of (a) used is 20% by weight
If it is less than the above range, the moldability of the obtained maleimide-based copolymer may be deteriorated and the impact resistance may be lowered, which is not preferable. Further, if the amount of (a) used exceeds 80% by weight, the resulting maleimide-based copolymer may not be able to impart sufficient heat resistance to the resin composition, which is not preferable.

The amount of the monomer (b) used is preferably 20 to 60% by weight. 20% by weight of (b)
If it is less than the above range, the resulting maleimide-based copolymer may not be able to impart sufficient heat resistance to the resin composition, which is not preferable. On the other hand, if the amount of (b) used exceeds 60% by weight, the resulting maleimide-based copolymer may have poor moldability and impact resistance.
Not preferable.

The amount of the monomer (c) used is 0.005
It is preferably 0.1% by weight. When the amount of (c) used is less than 0.005% by weight, the resulting maleimide-based copolymer may not be able to impart sufficient mechanical strength to the resin composition, which is not preferable. Also,
When the amount of (c) used exceeds 0.1% by weight, the resulting maleimide-based copolymer may not be able to give sufficient impact resistance to the resin composition, which is not preferable.

The amount of the monomer (d) used as required is preferably 0 to 30% by weight, more preferably 0 to 20% by weight. The usage of (d) is 30
When the content exceeds the weight%, it may be difficult to obtain a balance of physical properties such as moldability and impact resistance of the obtained maleimide-based copolymer. In addition, the above-mentioned monomer (a),
The amounts of each of (b), (c) and (d) used are based on the total of 100% by weight.

The method of copolymerizing the monomers (a), (b), (c) and the monomer (d) used as necessary is not particularly limited, and a known method is appropriately adopted. However, the solution polymerization method in which radical copolymerization is carried out in an organic solvent is preferable because the insoluble matter is less likely to be produced when the copolymerization is carried out by the solution polymerization method. When the crosslinkable monomer (c) is used for copolymerization by a suspension polymerization method or an emulsion polymerization method, the insoluble matter is likely to be produced.

When an organic solvent is used, the amount used is
For example, a range of 30 to 70% by weight based on the total weight of raw materials is preferable. The organic solvent that can be used is not particularly limited as long as it can dissolve the monomer, and is, for example, toluene (hereinafter this may be referred to as “Tol”), an aromatic solvent such as benzene. Ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate;
Examples include halogenated hydrocarbons such as chloroform; dimethylformamide; dimethylacetamide; polar organic solvents such as dimethylsulfoxide. Of these, toluene or methyl ethyl ketone is preferable in consideration of economy and ease of handling at room temperature. 60
An organic solvent having a boiling point of ˜140 ° C. is preferable because it is less likely to remain as a volatile component in the copolymer by being removed from the reaction mixture by the method described later.

When copolymerizing the monomers, if necessary,
A polymerization initiator, a chain transfer agent, etc. may be present in the reaction system. Although the polymerization initiator is not particularly limited, for example, 1,1-bis (t-butylperoxy) -3,
3,5-trimethylcyclohexane, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, t-butyl peroxyacetate, t
-Butylperoxyisobutyrate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, t-
Peroxides such as butylperoxybenzoate and t-butylperoxyisopropyl carbonate; azo compounds such as azobisisobutyronitrile, azobisdimethylvaleronitrile, azobis-1-cyclohexanecarbonitrile, etc., used for ordinary radical polymerization The compounds used are used in the usual amounts. The entire amount of the polymerization initiator may be charged in the reactor in advance, or may be supplied during the reaction.

During the polymerization reaction, it is preferable to carry out the polymerization by removing the dissolved oxygen in the reaction mixture with an inert gas or the like. This is because oxygen acts as a polymerization inhibitor. The polymerization is performed at a temperature of 60 to 200 ° C. for 1 to 20.
Do on time. The polymerization conversion rate is based on all the monomers used.
For example, it is preferable that the content be 50 to 95% by weight. After all the monomers have been gradually supplied, the polymerization reaction may be continued at the same temperature and atmosphere or at least one of them may be changed as necessary.

After the completion of the polymerization, the reaction mixture usually contains volatile components such as unreacted monomers and organic solvents in addition to the produced maleimide copolymer.
Therefore, it is necessary to remove this volatile component from the reaction mixture. The volatile component contained in the reaction mixture is generally removed by evaporation using a vacuum flash method, a thin film evaporation method, a single-screw or twin-screw vent extruder, and the volatile component is a maleimide-based compound. It is preferably removed from the reaction mixture under conditions where the copolymer is in the molten state. Under the condition that the maleimide copolymer will be in a molten state, it is effective to reduce the heat resistance of the molded product blended with the maleimide copolymer and to effectively eliminate the volatile components that cause foaming of this molded product. This is because the volatile components can be continuously removed.

In particular, when the reaction mixture contains a large amount of volatile components, the removal of volatile components is preferably carried out, for example, by the following method. The reaction mixture is preheated and then introduced into an extruder, where the reaction mixture is treated at a temperature above the preheat temperature to evaporate and remove volatile components. Examples of the apparatus used here include a vented extruder equipped with a preheater. In preheating with a preheater or the like, for example, the reaction mixture is pressurized to 5 to 30 atm and heated to a temperature of 150 to 250 ° C. The reaction mixture preheated as described above is introduced into an extruder having one or more vent holes capable of maintaining a reduced pressure,
The volatile component is volatilized and removed from the vent hole while heating so that the maleimide copolymer is in a molten state.

The maleimide copolymer is obtained by removing the volatile components from the reaction mixture by the above-mentioned method. The maleimide-based copolymer thus obtained preferably has a residual volatile component content of 1,000.
It is below ppm. Further, this maleimide-based copolymer,
Weight average molecular weight 100,000-350,000, number average molecular weight 30,000-2
Viscosity of 10,000 to 10 million poise at a temperature of 260 ° C,
It has a glass transition temperature of 150 to 230 ° C.

Since the maleimide copolymer of the present invention has high heat resistance and excellent moldability (fluidity), it is blended with one or more other thermoplastic resins to produce a thermoplastic resin. It can also be used as a plastic resin composition. For example, methyl methacrylate resin, methyl methacrylate-styrene resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene oxide resin, vinyl chloride resin, chlorinated vinyl chloride resin, acrylonitrile-styrene resin, acrylonitrile-methyl methacrylate resin, styrene. When the maleimide copolymer of the present invention is used as a modifier for a methacrylic acid resin, a styrene-methacrylic acid-acrylonitrile resin, an unsaturated polyester resin, etc., the heat resistance of these resins is improved. In particular, A
Rubber modified resin represented by BS resin (acrylonitrile-butadiene-styrene resin), MBS resin (methylmethacrylate-butadiene-styrene resin) and the like, crystalline resin such as polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin and the like. By blending with the maleimide-based copolymer of the invention, a molding material excellent in heat resistance, impact resistance and the like can be obtained. Using a device such as a twin-screw extruder, under normal operating conditions, the weight ratio of the above resin to the maleimide copolymer is 10:90 to 90: 1.
Blending at a ratio of 0 is preferable because the thermoplastic resin composition has improved heat resistance and excellent moldability without impairing the characteristics of the above resin.

In addition to the maleimide copolymer and the other thermoplastic resin, the above thermoplastic resin composition may contain a hindered phenolic antioxidant or a phosphite in order to improve thermal stability, if necessary. A system stabilizer, a benzophenone-based or hindered amine-based UV absorber for improving weather resistance, or an amide-based lubricant or metal soap for improving moldability can be used by mixing, respectively. . Further, additives such as inorganic fillers such as calcium carbonate, calcium sulfate, talc, mica, bentonite and glass fiber, flame retardants, antistatic agents, coloring agents and the like can be added. These can contain 1 type (s) or 2 or more types. The contents of these may be appropriately set as necessary.

The above thermoplastic resin composition is, for example,
A predetermined molded product can be obtained by a molding method such as injection molding, extrusion molding, or vacuum molding. This molded product is used, for example, in automobile interior parts such as console boxes, speaker boxes, instrument panels, automobile exterior parts such as wheel covers and air spoilers, and electrical and electronic parts such as word processor and personal computer housings. It

[0041]

In addition to the aromatic vinyl-based monomer unit (A) and the maleimide-based monomer unit (B), the divinylbenzene monomer unit (C) is an essential structural unit in the above-mentioned predetermined ratio, and is defined as above. When the weight average molecular weight is 100,000 to 350,000, it does not substantially contain insoluble matter in tetrahydrofuran, and the molecular weight retention rate at 280 ° C. is 80% or more, moldability, impact resistance and thermal stability are obtained. The resulting maleimide-based copolymer is excellent. When this maleimide-based copolymer is used as a constituent component of the resin composition, the mechanical strength and heat resistance of the composition are sufficiently improved.

In addition to the aromatic vinyl-based monomer (a) and the maleimide-based monomer (b), the divinylbenzene monomer (c) is used as an essential raw material in the above-mentioned predetermined ratio, and these monomer components are used. When a radical copolymerization reaction of is carried out in an organic solvent, a maleimide-based copolymer is produced. When the volatile component is removed from the reaction mixture containing this copolymer under the condition that the maleimide copolymer is in a molten state, the maleimide copolymer having the above-mentioned excellent performance is obtained.

[0043]

EXAMPLES Specific examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the following examples.
Unless otherwise specified, "part" means "part by weight", "%"
Is "% by weight" and "ppm" is based on weight. -Example 1-1-with condenser, stirrer and two dropping funnels,
In a polymerization reaction tank with an internal volume of 30 liters, styrene 7.2
Parts, divinylbenzene (crosslinking agent) 0.005 parts and toluene 36.5 parts were charged, and the inside was replaced with nitrogen. On the other hand, 17.5 parts of styrene and 0.021 part of t-butylperoxyisopropyl carbonate were added to the dropping tank (1), and 23.3 parts of N-phenylmaleimide was added to 1 part of toluene.
The solution dissolved in 5.5 parts was charged into the dropping tank (2). The dropping tank (2) was maintained at a temperature (here, 60 ° C.) at which N-phenylmaleimide was completely dissolved and became a uniform solution.

The monomer-containing solution in the polymerization reaction tank was added to 11
The temperature was raised to 5 ° C., 0.011 part of t-butylperoxyisopropyl carbonate was added to start polymerization, and then the raw materials in the dropping tank (1) and the dropping tank (2) were uniformly mixed for 3.5 hours. Polymerization was carried out by adding dropwise separately at a rate. Furthermore, by aging by heating as it is for 1.5 hours after completion of the dropping, styrene 5.7%, toluene 5
A reaction liquid containing 2.0% and the produced maleimide copolymer 42.3% was obtained. In this reaction liquid, N-phenylmaleimide was less than 0.02% and divinylbenzene was less than 0.02%.
The content was less than 004%.

The obtained reaction solution was introduced into a twin-screw extruder with a vent having a diameter of 44 mm and operated at a barrel temperature of 280 to 300 ° C. and a vacuum degree of 20 to 200 Torr to remove volatile components in the reaction solution. The molten maleimide-type copolymer discharged from the extruder outlet is 300 ° C., and the pelletized maleimide-type copolymer (A-1) is obtained by cutting this in a strand state and then cutting. It was

This maleimide copolymer (A-1) is
It had a molecular structure of 44.9% styrene units, 55.1% N-phenylmaleimide units, and 110 ppm divinylbenzene units. -Example 1-2 to 1-4-4-In Example 1-1, the polymerization reaction tank, the amount added to the dropping tank (1), the dropping tank (2), the temperature in the dropping tank (2), and the polymerization Maleimide copolymers (A-2) to (A-4) were obtained in the same manner as in Example 1-1, except that the operating conditions such as temperature were as shown in Table 1 below.

-Comparative Example 1-1-Comparative Example 1-1 was carried out in the same manner as in Example 1-1, except that the polymerization was carried out without using divinylbenzene (crosslinking agent). Maleimide-based copolymer (B-
1) was obtained. -Comparative Example 1-2 Example 1-Except that the amount of divinylbenzene (crosslinking agent) used was changed to 0.103 parts in Example 1-1.
The same operation as in 1 was performed to obtain a comparative maleimide-based copolymer (B-2).

-Comparative Example 1-3-An example except that 0.013 parts of polyethylene glycol diacrylate (crosslinking agent) (molecular weight 302) was used in place of divinylbenzene (crosslinking agent) in Example 1-1. The same operation as in 1-1 was performed to obtain a maleimide-based copolymer for comparison (B-3).

-Comparative Example 1-4-A polymerization reaction tank having a condenser and a stirrer and an internal volume of 30 liters was used. 60.0 parts of styrene, 40.0 parts of N-phenylmaleimide, 0.02 of divinylbenzene (crosslinking agent).
Parts, 1.0 part of t-butylperoxy-2-ethylhexanoate, and 233.3 parts of a 0.2% aqueous solution of polyvinyl alcohol having a saponification rate of 98% and a viscosity of 45 cps were charged, and the inside was stirred under nitrogen. Was replaced with to obtain a suspension of the monomer. Then, while maintaining the suspension state, the temperature of the polymerization reaction tank was raised to 70 ° C., the temperature was kept at this temperature for 2.5 hours to carry out the polymerization, and further the mixture was heated at 95 ° C. for 2.0 hours to perform aging. It was

After cooling the reaction product, the solid content is separated by filtration, washed, and dried in a hot air dryer at 100 ° C.
A bead-shaped comparative maleimide copolymer (B-4) was obtained. This comparative maleimide-based copolymer (B-4) has a styrene unit of 59.7% and an N-phenylmaleimide unit of 4
It had a molecular structure of 0.3% and a divinylbenzene unit of 200 ppm.

For each of the maleimide copolymers obtained in the above Examples and Comparative Examples, the types and ratios of the monomer units in the structure, the weight average molecular weight, the insoluble content and the molecular weight retention rate were determined by the following method. I asked. The results are shown in Table 2 below. The types and ratios of the monomer units in the structure are determined by infrared absorption spectrum of copolymer, ¹ H-NMR spectrum, thermal decomposition GC-MS, analysis by elemental analysis, and gas chromatography analysis of recovered volatile components. It was decided by performing.

The weight average molecular weight is a value obtained by calibrating the molecular weight measured by gel permeation chromatography (GPC) with standard polystyrene using tetrahydrofuran (THF) as an eluent. Insoluble matter is copolymer pellet 3
g was mixed and dissolved in 27 g of THF, and the presence or absence of insoluble matter was visually confirmed.

The molecular weight retention was measured as follows using a differential thermal balance. Approximately 10 mg of the sample of the copolymer was placed in an aluminum pan and placed on the measuring part of the differential thermal balance.
Cover with a furnace heated to 80 ° C, and immediately use a vacuum pump to reduce the pressure (20 mmHg or less). 2 for 10 minutes in this state
After holding at 80 ° C., the copolymer is taken out and rapidly cooled to obtain a sample for measuring the molecular weight retention rate. The weight average molecular weight of the sample for measuring the molecular weight retention was measured by the above method, and the ratio of the value to the weight average molecular weight of the copolymer before the heat treatment obtained above was determined to be the molecular weight retention.

-Examples 2-1 to 2-4 and Comparative Example 2-
1-2-4-4 Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-
30 parts by weight of each maleimide copolymer obtained in 4 and AB
70 parts by weight of S resin (acrylonitrile content 18%, butadiene content 40%, styrene content 42%) 2 parts
The mixture was kneaded with a shaft extruder at a barrel temperature of 240 to 260 ° C. to give pellets. The obtained pellet-shaped resin composition is 220
A test piece was obtained by injection molding at ℃. The heat resistance, impact resistance, mechanical strength and moldability of this test piece were evaluated by the following methods. The results are shown in Table 3 below.

The heat resistance is based on JIS-K7207.
Deflection temperature under load (HD of 18.5 Kgf / cm ²⁾
It evaluated by T). The larger this value, the better the heat resistance. The impact resistance was evaluated by the Izod impact value (IZOD) measured by performing the Izod impact test based on JIS-K7110. The larger this value, the better the impact resistance.

The mechanical strength was evaluated by the bending strength and bending elastic modulus measured according to JIS-K7203.
The larger these values are, the better the mechanical strength is. Moldability is based on JIS-K6874, load 10kg
f, the melt flow rate (MFR) measured at a test temperature of 240 ° C. was used for evaluation. The larger the value of this melt flow rate, the better the moldability.

[0057]

[Table 1]

[0058]

[Table 2]

In Tables 1 and 2 above, St is styrene, P
MI is N-phenylmaleimide, Tol is toluene, and the cross-linking agent is divinylbenzene, except for Comparative Examples 1-3.
Comparative Examples 1-3 are polyethylene glycol diacrylates. In Table 1, the composition of the reaction solution at the end of aging was measured by gas chromatography for volatile components (St, PMI, Tol, cross-linking agent), and for the copolymer, the reaction solution was measured with methyl ethyl ketone. It was obtained by diluting, pouring it into methanol, drying the resulting precipitate, and measuring the weight of the dried product.

[0060]

[Table 3]

As can be seen from Table 3, the resin compositions of Examples have higher heat resistance, higher impact resistance, and lower impact resistance than the resin compositions of Comparative Examples.
It was confirmed that both the mechanical strength and the moldability were excellent.

[0062]

The novel maleimide copolymer according to the present invention is excellent in moldability, impact resistance and thermal stability and the like, and when used as a constituent component of a resin composition,
The mechanical strength and heat resistance of this composition can be sufficiently improved. According to the production method of the present invention, the above excellent maleimide-based copolymer can be obtained.

Claims (2)

[Claims] 1. A structural unit (A) of 35 to 70% by weight derived from an aromatic vinyl-based monomer (a) and a structural unit (B) of 30 to 65% by weight derived from a maleimide-based monomer (b). , A structural unit (C) derived from a divinylbenzene monomer (c)
0.01 to 0.1% by weight and the monomer (a),
The structural unit (D) derived from another vinyl-based monomer (d) copolymerizable with (b) and (c) is composed of 0 to 30% by weight (however, these structural units (A), ( B),
(The total of (C) and (D) is 100% by weight), the polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography is 100,000 to 350,000, and substantially contains a component that does not dissolve in tetrahydrofuran. A novel maleimide-based copolymer having a molecular weight retention of 80% or more at 280 ° C. 2. A method for producing the novel maleimide-based copolymer according to claim 1, wherein the aromatic vinyl-based monomer (a) is 20 to 80% by weight, and the maleimide-based monomer (b) 2.
0-60% by weight, divinylbenzene monomer (c) 0.0
05 to 0.1% by weight and 0 to 30% by weight of another vinyl-based monomer (d) copolymerizable with these monomers (however,
The total of the monomers (a), (b), (c) and (d) is 100.
(% By weight) is subjected to a radical copolymerization reaction in an organic solvent, and then a volatile component and a maleimide copolymer are melted from the reaction mixture containing the produced maleimide copolymer. By removing under the following conditions,
A method for producing a maleimide-based copolymer for obtaining a maleimide-based copolymer.