JPH1053620A - Thermoplastic copolymer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic copolymer excellent in a variety of physical properties, for example, heat resistance and mechanical strengths, and resistant to discoloration, and its production. SOLUTION: An aromatic vinyl monomer, a vinyl cyanide monomer and, when necessary, a monomer copolymerizable to these monomers are copolymerized to give a thermoplastic copolymer. At this time, at least a part or the whole part of the vinyl cyanide monomer is charged in a reactor to initiate the copolymerization, then the weight of the aromatic vinyl monomer unreacted in the reaction solution is adjusted to be larger than that of the unreacted vinyl cyanide, when all of the monomers are charged up whereby the proportion of the vinyl cyanide monomer can be reduced in the structure units of the thermoplastic copolymer formed at the latter-half step of the copolymerization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic copolymer which is excellent in various physical properties such as heat resistance and mechanical strength and is hardly colored, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, for example, in automobiles, electric / electronic devices, office machines, etc., weight reduction, energy saving,
BACKGROUND ART For the purpose of cost reduction and the like, a molded product made of metal is replaced with a molded product made of synthetic resin. Examples of the synthetic resin include resins having excellent heat resistance and impact resistance, such as polycarbonate and ABS (acrylonitrile-
Polymer alloys with butadiene-styrene) resin, modified PPE (polyphenylene ether) and the like are used.

[0003] On the other hand, AS (acrylonitrile-styrene) resin, which is a thermoplastic resin, is excellent in chemical resistance and mechanical strength, is transparent, and is excellent in miscibility with the ABS resin and the like. For this reason, AS resin is generally used as a molding material. However,
The AS resin has a drawback that it is not suitable for use at high temperatures because of its poor heat resistance. Therefore,
In order to improve the heat resistance of the AS resin, for example, a terpolymer of acrylonitrile-styrene-N-substituted maleimide using N-substituted maleimide has been proposed.

[0004] However, acrylonitrile has lower reactivity than styrene and N-substituted maleimide. Therefore, when acrylonitrile, styrene, and N-substituted maleimide are charged at once and copolymerized, the thermoplastic copolymer produced in the first half of the polymerization reaction has a high ratio of styrene and N-substituted maleimide in its structural units. On the other hand, the proportion of acrylonitrile in the structural units of the thermoplastic copolymer produced in the latter half of the polymerization reaction is high. In other words, the composition of the thermoplastic copolymer obtained in the first half of the polymerization reaction is significantly different from that of the thermoplastic copolymer obtained in the second half of the polymerization reaction. As a result, the composition of the thermoplastic copolymer is significantly non-uniform. turn into. Therefore, the thermoplastic copolymer is inferior in heat resistance and mechanical strength, and has low transparency.

Therefore, various methods for producing a thermoplastic copolymer having a substantially uniform composition have been proposed. For example, JP-A-3-205411 discloses that after the total amount of acrylonitrile, the total amount of N-substituted maleimide, and a part of styrene are collectively charged and continuously subjected to solution copolymerization, the remaining styrene is added. A method for aging is disclosed. Japanese Patent Application Laid-Open No. 7-278232 discloses a method in which emulsion polymerization is carried out while dropping an emulsion obtained by emulsifying acrylonitrile, styrene and N-substituted maleimide. As a method for obtaining a thermoplastic copolymer having excellent mechanical strength, Japanese Patent Application Laid-Open No. 63-162708 discloses a solution copolymerization method in which acrylonitrile and styrene are charged at once and then N-substituted maleimide is dropped. There is disclosed a method for causing this to occur.

[0006]

However, in the above-mentioned conventional method, the uniformity of the composition is insufficient, and
The thermoplastic copolymer produced in the latter half of the polymerization reaction has a high acrylonitrile ratio in its structural unit. Then, the thermoplastic copolymer having a high ratio of acrylonitrile in the structural unit is easily colored when heated. Further, the thermoplastic copolymer has a degree of coloring before heating,
The difference from the degree of coloring once heated (recoloring property) is large. That is, the thermoplastic copolymer obtained by the above-mentioned conventional method has a problem that it is easy to be colored, and it is not possible to suppress the recoloring property at the time of molding or the like. Therefore, a thermoplastic copolymer which is excellent in various physical properties such as heat resistance and mechanical strength and is hardly colored, and a method for producing the same are keenly desired.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a thermoplastic copolymer which is excellent in various physical properties such as heat resistance and mechanical strength and is hardly colored, and a thermoplastic copolymer thereof. It is to provide a manufacturing method.

[0008]

Means for Solving the Problems The present inventors have intensively studied a thermoplastic copolymer and a method for producing the same in order to solve the above conventional problems. As a result, at the time of producing a thermoplastic copolymer by copolymerizing monomer components including an aromatic vinyl monomer and a vinyl cyanide monomer, at least the vinyl cyanide monomer After starting the copolymerization reaction by charging a part or all of the monomers, when all the monomer components have been charged, the weight of the unreacted aromatic vinyl monomer in the reaction solution is unreacted vinyl cyanide. The proportion of the unreacted aromatic vinyl monomer in the reaction solution in the latter half of the copolymerization reaction is increased by increasing the weight of the monomer. It has been found that the ratio of the vinyl cyanide monomer to the structural units of the thermoplastic copolymer formed in the latter half of the copolymerization reaction can be reduced.

By adopting the above method, the coloring property when heated (heat coloring property) can be reduced, and the difference between the coloring degree before heating and the coloring degree once heated. (Recolorability) was confirmed to be small. In other words, they have found that a thermoplastic copolymer excellent in various physical properties such as heat resistance and mechanical strength and hardly colored can be obtained by the above production method, and the present invention has been completed.

That is, in order to solve the above-mentioned problems, a method for producing a thermoplastic copolymer according to the first aspect of the present invention provides a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer. Is a method for producing a thermoplastic copolymer by copolymerizing the above-mentioned copolymers.At least a part or all of a vinyl cyanide monomer is charged into a reactor to start a copolymerization reaction. At the end of charging the monomer components,
It is characterized in that the weight of the unreacted aromatic vinyl monomer in the reaction solution is larger than the weight of the unreacted vinyl cyanide monomer.

According to a second aspect of the present invention, there is provided a method for producing a thermoplastic copolymer, comprising the steps of: The remaining monomer component is added to the reaction solution so that the weight of the aromatic vinyl monomer becomes larger than the weight of the unreacted vinyl cyanide monomer.

According to a third aspect of the present invention, there is provided a method for producing a thermoplastic copolymer, comprising the steps of: Is characterized by further containing an unsaturated dicarboxylic acid derivative copolymerizable with an aromatic vinyl monomer and a vinyl cyanide monomer.

According to a fourth aspect of the present invention, there is provided a method for producing a thermoplastic copolymer, comprising the steps of: It is characterized in that a vinyl monomer and an unsaturated dicarboxylic acid derivative are separately added.

According to a fifth aspect of the present invention, there is provided a method for producing a thermoplastic copolymer, comprising: a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer; Is a method for producing a thermoplastic copolymer by copolymerizing a vinyl cyanide monomer, at least a part or all of the vinyl cyanide monomer is charged into the reactor to start the copolymerization reaction. It is characterized in that after the monomer has been charged, the aromatic vinyl monomer has been charged.

Further, according to a sixth aspect of the present invention, there is provided a method for producing a thermoplastic copolymer, comprising: a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer; Is a method for producing a thermoplastic copolymer by copolymerizing the at least a vinyl cyanide monomer in a reactor, at least a part or all of the copolymerization reaction is started, and then the reaction solution Add the remaining monomer components,
After all the monomer components have been charged, unreacted vinyl cyanide monomer is distilled off from the reaction solution.

According to the above method, the coloring property can be reduced, and the difference between the coloring degree before heating and the coloring degree once heated (recoloring property) can be reduced. This makes it possible to obtain a thermoplastic copolymer which is excellent in various physical properties such as heat resistance and mechanical strength and is hardly colored. That is, it is possible to obtain a thermoplastic copolymer which is excellent in various physical properties such as heat resistance and mechanical strength, is difficult to be colored, and can suppress recoloration during molding and the like. According to the method of the fourth aspect, in addition to the various effects described above, a thermoplastic copolymer having a relatively low proportion of low molecular weight components can be obtained.

Further, the thermoplastic copolymer of the invention according to claim 7 is obtained by the method according to any one of claims 1 to 6 in order to solve the above-mentioned problems. .

In order to solve the above-mentioned problems, the thermoplastic copolymer according to the present invention has an aromatic vinyl monomer residue in an amount of 5 to 85% by weight of cyanide. Residues of vinyl monomers in the range of 5% by weight to 35% by weight, residues of unsaturated dicarboxylic acid derivatives in the range of 10% by weight to 50% by weight, and copolymerizable with the above three monomers A thermoplastic copolymer containing a vinyl monomer (b) residue in a range of 0% by weight to 20% by weight, and the yellowness of a 15% by weight chloroform solution of the thermoplastic copolymer is determined by YI ₁ , 2
Of the thermoplastic copolymer after heating at 65 ° C. for 4 minutes,
YI ₂ yellowness weight% chloroform solution, when the weight percent of the unsaturated dicarboxylic acid derivative residue and _{X, YI 1 <(1.5 ×} X 2/100) +5 and YI ₂ / YI _{1 <1.} 5.

According to a ninth aspect of the present invention, there is provided a thermoplastic copolymer according to the eighth aspect of the present invention, which has a low molecular weight containing an unsaturated dicarboxylic acid derivative residue. The ratio of the component is (0.1 × X) or less.

The above thermoplastic copolymer is excellent in various physical properties such as heat resistance and mechanical strength, and is hardly colored. That is, the above-mentioned thermoplastic copolymer is excellent in various physical properties such as heat resistance and mechanical strength, is hardly colored, and can suppress recoloring property during molding and the like.
According to the configuration of the ninth aspect, in addition to the various effects described above, a thermoplastic copolymer having more excellent heat resistance and impact resistance can be obtained.

Hereinafter, the present invention will be described in detail. The production method of the thermoplastic copolymer according to the present invention is an aromatic vinyl monomer, a vinyl cyanide monomer, and, if necessary,
In this method, a monomer component containing a vinyl monomer (a) copolymerizable with both of these monomers is copolymerized. The vinyl monomer (a) is an unsaturated dicarboxylic acid derivative, and
At least one of the vinyl monomers (b) copolymerizable with the above three monomers (ie, an aromatic vinyl monomer, a vinyl cyanide monomer, and an unsaturated dicarboxylic acid derivative) Contains.

Specific examples of the aromatic vinyl monomer include, for example, styrene, o-methylstyrene, and m-methylstyrene.
Methyl styrene, p-methyl styrene, α-methyl styrene, α-ethyl styrene, α-methyl methyl styrene, dimethyl styrene, t-butyl styrene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene, vinylnaphthalene, etc. Can be One of these aromatic vinyl monomers may be used alone, or two or more thereof may be used in combination. Of the compounds exemplified above, styrene and α-methylstyrene are more preferred.

The total of the aromatic vinyl monomer, the vinyl cyanide monomer, and the vinyl monomer (a), that is, the total amount of all the monomer components (hereinafter referred to as all monomer components) The proportion of the aromatic vinyl monomer is not particularly limited, but is preferably in the range of 15% by weight to 95% by weight.
More preferably, it is in the range of 25% by weight to 75% by weight. If the proportion of the aromatic vinyl monomer is less than 15% by weight, the polymerization rate will be low, and the mechanical strength of the resulting thermoplastic copolymer will be low. When the proportion of the aromatic vinyl monomer exceeds 95% by weight, the heat resistance of the obtained thermoplastic copolymer decreases.

Specific examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile. These vinyl cyanide monomers are:
Only one type may be used, or two or more types may be used in combination. Among the compounds exemplified above, acrylonitrile is more preferred.

The proportion of the vinyl cyanide monomer in the total monomer components is not particularly limited, but may be 5% by weight.
The range is preferably from 35 to 35% by weight, more preferably from 5 to 25% by weight. When the proportion of the vinyl cyanide monomer is less than 5% by weight, the mechanical strength such as the impact resistance of the obtained thermoplastic copolymer decreases. On the other hand, when the proportion of the vinyl cyanide monomer exceeds 35% by weight, the heat resistance of the obtained thermoplastic copolymer decreases, and the thermoplastic copolymer is liable to be colored.

Specific examples of the unsaturated dicarboxylic acid derivatives include, for example, maleimide; N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, -Phenylmaleimide, N-cyclohexylmaleimide, N- (chlorophenyl) maleimide, N-
N-substituted maleimides such as (bromophenyl) maleimide;
And unsaturated dicarboxylic acids such as maleic anhydride. One of these unsaturated dicarboxylic acid derivatives may be used alone, or two or more thereof may be used in combination. Of the compounds exemplified above,
N-phenylmaleimide and N-cyclohexylmaleimide are more preferred from the viewpoints of availability, economy, and the like.

The proportion of the unsaturated dicarboxylic acid derivative in the total monomer components is not particularly limited, but may be 50%.
% By weight or less, and more preferably in the range of 20% by weight to 50% by weight. When the proportion of the unsaturated dicarboxylic acid derivative exceeds 50% by weight, the fluidity is reduced, and the mechanical strength such as impact resistance and the moldability of the obtained thermoplastic copolymer are reduced. Further, the thermoplastic copolymer is easily colored. In addition, when the unsaturated dicarboxylic acid derivative is not used, the heat resistance of the obtained thermoplastic copolymer may be reduced.

Specific examples of the vinyl monomer (b) include acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Alkyl acrylates, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate; alkyl acrylates, such as benzyl acrylate; benzyl methacrylate, etc. Aryl methacrylate; and the like. These vinyl monomers (b) may be used alone,
Further, two or more kinds may be used in combination.

Vinyl monomer (b) in all monomer components
Is not particularly limited, but 20% by weight.
Or less, more preferably 10% by weight or less. When the proportion of the vinyl monomer (b) exceeds 20% by weight, the mechanical strength such as impact resistance and the heat resistance of the obtained thermoplastic copolymer decrease.

Since the vinyl monomer (a) contains at least one of the unsaturated dicarboxylic acid derivative and the vinyl monomer (b), the vinyl monomer accounts for all of the monomer components. The proportion of the monomer (a) is preferably 50% by weight or less, and more preferably in the range of 20% by weight to 50% by weight. Further, the vinyl monomer (a) more preferably contains an unsaturated dicarboxylic acid derivative.

In the production method according to the present invention, all the above monomer components are copolymerized by using a batch system.
More preferably, solution copolymerization is performed. In the solution copolymerization, a solvent and a polymerization initiator are used.

Examples of the solvent include, for example, saturated hydrocarbons such as hexane, heptane, octane and cyclohexane; alcohols such as butyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol and decyl alcohol; methyl ethyl ketone and the like. Ketones; ethers such as tetrahydrofuran; aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; halogenated hydrocarbons such as carbon tetrachloride; These solvents may be used alone or as a mixture of two or more. Among the compounds exemplified above, aromatic hydrocarbons are more preferred. The amount of the solvent to be used may be appropriately set according to the combination of the monomer components, the reaction conditions, and the like, and is not particularly limited.

As the above-mentioned polymerization initiator, specifically,
For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, p-menthane hydroperoxide,
Lauroyl peroxide, benzoyl peroxide, t-butylperoxy isopropyl carbonate, 1,1-bis (t-butylperoxy) -3,3,3
Organic peroxides such as 5-trimethylcyclohexane; ammonium persulfate, potassium persulfate, sodium persulfate;
Radical polymerization initiators such as inorganic peroxides such as hydrogen peroxide; azo compounds such as 2,2'-azobisisobutyronitrile; One of these polymerization initiators may be used alone, or two or more thereof may be used in combination. Furthermore, a redox initiator can also be obtained by combining the above peroxide with a reducing agent such as sulfite, bisulfite, thiosulfate, formamidine sulfinic acid, and ascorbic acid. The amount of the polymerization initiator used may be appropriately set depending on the combination of the monomer components and the reaction conditions, and the like.
There is no particular limitation.

In the production method according to the present invention, first, at least a part or all of the vinyl cyanide monomer among all the monomer components is placed in a predetermined reactor equipped with a stirrer or the like. After charging a monomer component (hereinafter, referred to as a monomer component (A)), a copolymerization reaction is started. In order to further improve the uniformity of the composition, at least a part of the aromatic vinyl monomer and a part of the vinyl cyanide monomer among all the monomer components are added to the reactor. It is more preferable to start the copolymerization reaction after charging the monomer component containing all or part thereof.

The solvent and the polymerization initiator may be charged in advance to the reactor in their entirety. Alternatively, a part of the solvent and the polymerization initiator may be charged to the reactor, while the remaining amount to be added to the reaction solution after starting the copolymerization reaction. The remainder may be mixed with a monomer component (hereinafter, referred to as a monomer component (a)). That is, the method of charging the solvent and the polymerization initiator into the reactor is not particularly limited. However, at least a part of the polymerization initiator needs to be charged to the reactor before adding the monomer component (a) to the reaction solution.

The reaction temperature is not particularly limited, but is preferably about 70 ° C to 180 ° C, more preferably 90 ° C to 1 ° C.
About 60 ° C. is more preferable. The reaction time may be appropriately set according to reaction conditions such as the reaction temperature and the time required for addition of the monomer component (a), and is not particularly limited.

After the start of the copolymerization reaction and when all the monomer components have been charged, the weight of the unreacted aromatic vinyl monomer in the reaction solution is reduced by the amount of the unreacted vinyl cyanide monomer. To be more than the weight of. Specifically, for example, the monomer component (a) is added to the reaction solution such that the weight of the unreacted aromatic vinyl monomer in the reaction solution is greater than the weight of the unreacted vinyl cyanide monomer. ) Is added. Also,
More preferably, at the time when all the monomer components have been charged, the weight of the unreacted aromatic vinyl monomer in the reaction solution is the weight of the unreacted monomer other than the aromatic vinyl monomer, that is, The monomer component (a) is added to the reaction solution so as to be larger than the weight of the unreacted vinyl cyanide monomer and the vinyl monomer (a).

That is, when the monomer component (a) has been charged into the reaction solution, the weight of the unreacted aromatic vinyl monomer in the reaction solution is smaller than the weight of the unreacted vinyl cyanide monomer. To be more. At the time when the monomer component (a) has been charged into the reaction solution, the weight of the unreacted aromatic vinyl monomer in the reaction solution is reduced by the amount of unreacted vinyl cyanide monomer and vinyl monomer ( More preferably, the weight is larger than a). Further, when the monomer component (a) has been charged into the reaction solution, the ratio of the aromatic vinyl monomer to the unreacted monomer component in the reaction solution is 6%.
It is particularly preferred that the content be 0% by weight or more.
The yield of the thermoplastic copolymer was 50% in terms of productivity.
Or more, and more preferably 70% or more.

Thus, in the latter half of the copolymerization reaction, the ratio of the unreacted aromatic vinyl monomer in the reaction solution can be made higher than the ratio of the unreacted vinyl cyanide monomer. The proportion of the vinyl cyanide monomer in the structural units of the thermoplastic copolymer formed in the latter half of the polymerization reaction can be reduced.

Then, the weight of the unreacted aromatic vinyl monomer in the reaction solution is made larger than the weight of the unreacted vinyl cyanide monomer in all the stages of the copolymerization reaction. More preferred. The weight of the unreacted aromatic vinyl monomer in the reaction solution is greater than the weight of the unreacted vinyl cyanide monomer and the vinyl monomer (a) throughout the copolymerization reaction. Is particularly preferable.

The method of adding the monomer component (a) to the reaction solution includes, for example, a method of adding continuously, and a method of adding it in several divided portions and sequentially. Among these addition methods, a method of adding continuously is more preferable.
The time required for the addition of the monomer component (a) is not particularly limited. The time at which the monomer component (a) starts to be added to the reaction solution may be after the copolymerization reaction has started, and is not particularly limited, but is preferably as early as possible.

The monomer component (a) comprises the remainder of the aromatic vinyl monomer, part or all of the vinyl monomer (a), and the remainder of the vinyl cyanide monomer (that is, May not be added as a monomer component (a)), respectively, or these three types of monomers may be appropriately mixed and added. Of these, it is more preferable to add the aromatic vinyl monomer and the vinyl cyanide monomer separately. In this case, the vinyl monomer (a) may be added separately, may be added as a mixture with an aromatic vinyl monomer, or may be added as a mixture with a vinyl cyanide monomer. You may. Further, when the vinyl monomer (a) contains an unsaturated dicarboxylic acid derivative and a vinyl monomer (b), the unsaturated dicarboxylic acid derivative and the vinyl monomer (b) are separately prepared. It can also be added.

Particularly, when the vinyl monomer (a) contains an unsaturated dicarboxylic acid derivative, that is, when the monomer component (a) contains an aromatic vinyl monomer and an unsaturated dicarboxylic acid derivative, When these are contained, it is more preferable to add these aromatic vinyl monomers and unsaturated dicarboxylic acid derivatives separately, that is, without mixing them.

Specifically, for example, after a monomer component (a) containing a part of an aromatic vinyl monomer is charged and a copolymerization reaction is started, the monomer component (a) is added to the reaction solution. As
A method of separately adding a monomer component containing the remainder of the aromatic vinyl monomer and a monomer component containing the unsaturated dicarboxylic acid derivative; a monomer component containing a part of the unsaturated dicarboxylic acid derivative After charging (A) and starting the copolymerization reaction, the reaction solution contains, as the monomer component (A), a monomer component containing the remainder of the unsaturated dicarboxylic acid derivative and an aromatic vinyl monomer A method of separately adding a monomer component and a monomer component; a monomer component containing the entire amount of the unsaturated dicarboxylic acid derivative and a total amount of the aromatic vinyl monomer as the monomer component (a) in the reaction solution. And separately adding the monomer components to be contained.

Thus, a Diels-Alder reaction between the aromatic vinyl monomer and the unsaturated dicarboxylic acid derivative (Diels-Alder reaction)
Since side reactions such as els-Alder reaction can be further suppressed, it is possible to obtain a thermoplastic copolymer having a relatively low proportion of low molecular weight components (which will be described in detail later).

It is particularly preferred that after the vinyl cyanide monomer has been charged, the aromatic vinyl monomer has been charged. The vinyl monomer (a) may be charged at any stage of the copolymerization reaction.
When the compound contains an unsaturated dicarboxylic acid derivative, it is more preferable to finish charging the unsaturated dicarboxylic acid derivative before finishing charging the aromatic vinyl monomer.

In the polymerization step, if necessary, a chain transfer agent such as alkyl mercaptan or α-methylstyrene dimer, a hindered amine or benzotriazole weather resistance stabilizer, a hindered phenol antioxidant, a molecular weight You may add additives, such as a regulator, a plasticizer, a heat stabilizer, and a light stabilizer.

In another production method according to the present invention, after the copolymerization reaction is started, the monomer component (a) is added to the reaction solution, and after all the monomer components have been charged, the reaction is continued. Unreacted vinyl cyanide monomer is distilled off from the reaction solution.
Specifically, for example, after finishing charging all the monomer components,
Unreacted vinyl cyanide monomer is distilled off from the reaction solution so that the weight of unreacted aromatic vinyl monomer in the reaction solution is greater than the weight of unreacted vinyl cyanide monomer. I do.

That is, after all the monomer components have been charged,
By distilling off the unreacted vinyl cyanide monomer from the reaction solution, the weight of the unreacted aromatic vinyl monomer in the reaction solution becomes larger than the weight of the unreacted vinyl cyanide monomer To do. Furthermore, by distilling off the unreacted vinyl cyanide monomer from the reaction solution, the proportion of the aromatic vinyl monomer in the unreacted monomer component in the reaction solution becomes 60% by weight or more. Is particularly preferable.

The method of distilling off the unreacted vinyl cyanide monomer from the reaction solution includes, for example, a method of refluxing the vinyl cyanide monomer and extracting a part thereof; a method of distillation under reduced pressure, and the like. . The time required for distilling off the vinyl cyanide monomer is not particularly limited. Further, the time when the distillation of the vinyl cyanide monomer is started may be performed after all the monomer components have been charged, and is not particularly limited, but is preferably as early as possible.

The copolymerization reaction may be terminated at the stage when all the monomer components have been substantially polymerized. If necessary, for example, at the stage where unreacted aromatic vinyl monomer remains. It may end. Thereby, the thermoplastic copolymer according to the present invention is produced. The thermoplastic copolymer is excellent in various physical properties such as mechanical strength such as impact resistance, heat resistance, chemical resistance, weather resistance, and fluidity.

The method for removing the thermoplastic copolymer from the reaction solution is not particularly limited. For example, the reaction solution is introduced into a so-called volatile separation / removal apparatus such as a twin-screw extruder equipped with a vent, and the reaction is carried out. A simple method is to remove (evaporate) volatile components from the solution to separate the thermoplastic copolymer from unreacted monomer components and solvents. The method using the devolatilizer is industrially advantageous.

Further, for example, the reaction solution is poured into a solvent (poor solvent) that does not dissolve the thermoplastic copolymer, and the thermoplastic copolymer is precipitated (precipitated). Alternatively, a method of filtering and drying the thermoplastic copolymer may be employed.

Thus, the thermoplastic copolymer according to the present invention can be separated. Further, the obtained thermoplastic copolymer, if necessary, the antioxidant, the weather resistance stabilizer, a flame retardant, an antistatic agent, additives such as a coloring agent,
Alternatively, various fillers may be added.

According to the above-mentioned production method, the thermoplastic copolymer according to the present invention can be obtained. The thermoplastic copolymer produced as described above contains, for example, an aromatic vinyl monomer residue when the monomer component contains an unsaturated dicarboxylic acid derivative and a vinyl monomer (b). 5% to 85% by weight
In the range of 5% by weight to 35% by weight of the vinyl cyanide monomer residue.
In the range of 10% by weight of the unsaturated dicarboxylic acid derivative residue.
More preferably, the vinyl monomer (b) residue is contained in the range of 0% to 20% by weight, and the aromatic vinyl monomer is further contained in the range of 0% to 50% by weight. Residues in the range of 15% to 75% by weight, vinyl cyanide monomer residues in the range of 5% to 25% by weight, unsaturated dicarboxylic acid derivative residues in the range of 20% to 50% by weight. Within the range, and 0% by weight to 1% of the vinyl monomer (b) residue.
It is particularly preferred that the content is within the range of 0% by weight.

The 15% by weight chloroform solution of the thermoplastic copolymer containing the monomer component residues within the above ranges was obtained by heating the 15% by weight yellow solution of YI ₁ at 265 ° C. for 4 minutes. Assuming that the yellowness of a 15% by weight chloroform solution of a thermoplastic copolymer is YI ₂ and the weight% of an unsaturated dicarboxylic acid derivative residue is X, the following inequalities (1) and (2)
To be satisfied. That is, a thermoplastic copolymer described above, YI ₁ satisfies ^{<(1.5 × X 2/100} ) +5 ...... (1) and _{YI 2 / YI 1 <1.5 ......} (2). The method of heating the thermoplastic copolymer at 265 ° C. for 4 minutes is not particularly limited.

The above inequalities (1) and (2) are inequalities found as a result of intensive studies by the present inventors. Further, the thermoplastic copolymer according to the present invention satisfies the inequality (1) because it is less colored. On the other hand, conventional thermoplastic copolymers do not satisfy inequality (1) because they are easily colored. The thermoplastic copolymer according to the present invention satisfies the inequality (2) because the difference (recolorability) between the degree of coloring before heating and the degree of coloring after heating is relatively small. On the other hand, the conventional thermoplastic copolymer does not satisfy the inequality (2) because the recoloring property is relatively large. That is, since the thermoplastic copolymer according to the present invention has improved coloring properties as compared with conventional thermoplastic copolymers, it is difficult to be colored, and the recoloring properties at the time of molding and the like are suppressed. Have been.

The proportion of low molecular weight impurities in the above thermoplastic copolymer, that is, for example, when the molecular weight is 200
It is preferable that the ratio of the low-molecular-weight component containing the unsaturated dicarboxylic acid derivative residue be within the range of from 1000 to as small as possible. Specifically, the ratio of the low molecular weight component is more preferably (0.1 × X) or less, and (0.06 × X)
X) or lower is more preferable, and (0.04 × X) or lower is particularly preferable. When the ratio of the low molecular weight component exceeds (0.1 × X), the heat resistance and impact resistance of the thermoplastic copolymer tend to decrease. In addition, the low molecular weight component is not removed together with the unreacted material even when distilling off the unreacted vinyl cyanide monomer from the reaction solution in the production method according to the present invention. Remains.

The low molecular weight component will be described in more detail. As a result of intensive studies conducted by the inventors of the present application, when a maleimide-based monomer that is an unsaturated dicarboxylic acid derivative and an aromatic vinyl monomer and a vinyl cyanide monomer are radically polymerized, Deals between
It was found that side reactions such as the Alder reaction occurred. That is, a reactant obtained by reacting a maleimide-based monomer with an aromatic vinyl monomer and / or a vinyl cyanide monomer together with a copolymer as a target substance, It was found that a low molecular weight component such as a reactant produced by further reaction with the monomer and / or the vinyl cyanide monomer was generated.

Accordingly, the low molecular weight component contained in the above thermoplastic copolymer is not a compound produced by radical polymerization of the monomer component, but an unsaturated dicarboxylic acid derivative and, for example, an aromatic vinyl monomer. Deal with-
It is a compound generated by a side reaction such as an Alder reaction. The molecular weight of the low molecular weight component and the content (ratio) of the low molecular weight component in the thermoplastic copolymer are determined by GPC.
(Gel permeation chromatography) or the like.

Thermoplastic copolymers include, for example, interior parts of automobiles, parts of electric and electronic equipment, parts of various industrial products,
It is suitable as a molded product such as office supplies or a food packaging material. The molding method of the thermoplastic copolymer and its use are not particularly limited.

[0062]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. In the Examples and Comparative Examples, “parts” indicates “parts by weight”, and “%” indicates
"% By weight" is shown.

The composition of the thermoplastic copolymer was determined as follows. That is, a predetermined amount of the thermoplastic copolymer, precisely weighed,
It was dissolved in chloroform to make a 3% solution. Next, using this solution, infrared spectroscopy (so-called infrared absorption method) was performed under the condition of a cell thickness of 0.05 mm.

Then, the amounts of cyano group, carbonyl group and benzene ring contained in the thermoplastic copolymer are determined from the measured absorption intensity of the infrared absorption spectrum (IR) to obtain the thermoplastic copolymer. The composition of the polymer was determined. The cyan group is derived from a vinyl cyanide monomer and absorbs infrared rays having a wave number of 2237 cm ^-1 . The carbonyl group is derived from the vinyl monomer (a) and has a wave number of 1712c.
absorbs m ^-1 infrared radiation. The benzene ring is derived from an aromatic vinyl monomer and absorbs infrared rays having a wave number of 760 cm ^-1 .

The concentration of the unreacted monomer components in the reaction solution at the time when all the monomer components have been charged, ie, the aromatic vinyl monomer, vinyl cyanide monomer, and The concentration of the vinyl monomer (a) was measured using gas chromatography (GC). Further, the concentration of the unreacted monomer component in the reaction solution at the time when the copolymerization reaction was completed was measured in the same manner. The concentration of the thermoplastic copolymer in the reaction solution at the time when the copolymerization reaction was completed was determined from the amount of the thermoplastic copolymer taken out of the reaction solution.

The glass transition temperature of the thermoplastic copolymer (T
g) shows differential scanning calorimetry (DSC).
measurement using a device (manufactured by Rigaku Denki Co., Ltd .; trade name: DSC-8230) with α-Al ₂ O ₃ as a standard substance under a nitrogen gas flow at a heating rate of 5 ° C./min. It was determined from the obtained DSC curve by the midpoint method.

Further, the yellowness of the thermoplastic copolymer (Y
I) is a color difference meter (manufactured by Nippon Denshoku Industries Co .;
SZ- $ 80 COLOR MEASURING SY
It was determined by performing a transmission method measurement at a cell thickness of 1 cm using STEM).

Example 1 5.0 parts of styrene as an aromatic vinyl monomer was placed in a reactor equipped with a thermometer, a nitrogen gas inlet tube, two dropping devices, a reflux condenser, and a stirrer.
Acrylonitrile 5.0 as vinyl cyanide monomer
And 47.3 parts of toluene as a solvent. In addition, 15.0 parts of styrene was added to one dropping device,
A mixture (A) consisting of 0.2 parts of a polymerization initiator (manufactured by Kayaku Akzo Co., Ltd .; trade name Kayacarbon BIC-75) is charged, and acrylonitrile 1.0 part, unsaturated dicarboxylic acid derivative is added to the other dropping device. 16.0 parts of N-phenylmaleimide as (vinyl monomer (a))
Then, a mixture (B) consisting of 10.7 parts of toluene was charged. The mixture (B) was prepared by mixing acrylonitrile and N-phenylmaleimide in toluene, and then heating the mixture to 70 ° C. to dissolve both.

Next, the above toluene solution was heated to 100 ° C. while stirring under a nitrogen atmosphere, and then 0.05 part of a polymerization initiator (same as above) was added to the toluene solution to carry out a copolymerization reaction. Started. After the start of the copolymerization reaction, the mixture (A) is continuously dropped into the reaction solution over 3.5 hours, and the mixture (B) kept at 70 ° C. is continuously dropped over 3.0 hours. It was dropped.

The concentration of the unreacted monomer component in the reaction solution at the time when all the monomer components had been charged, that is, when the mixture (A) had been dropped, was measured. As a result, the concentration of styrene was 3.2%, the concentration of acrylonitrile was 1.6%, and the concentration of N-phenylmaleimide was 0.5%. Therefore, the ratio of styrene to the unreacted monomer components in the reaction solution was 60.4%.

When nine hours had passed since the start of the copolymerization reaction, the copolymerization reaction was terminated. The obtained reaction solution was introduced into a twin-screw extruder equipped with a vent. Then, the pressure was reduced to a predetermined pressure and heated to 280 ° C. to remove volatile components such as a solvent from the reaction solution, thereby obtaining a thermoplastic copolymer in a pellet state. The glass transition temperature of the thermoplastic copolymer was 165 ° C.

The composition of the thermoplastic copolymer was determined. As a result, the thermoplastic copolymer had a styrene residue (aromatic vinyl monomer residue) of 47%, an acrylonitrile residue (vinyl cyanide monomer residue) of 14%, and an N-phenylmaleimide residue. Group (unsaturated dicarboxylic acid derivative residue) 39% (X = 39). The concentration of the thermoplastic copolymer in the reaction solution was 41.5%. Further, the concentration of the unreacted monomer component in the filtrate, that is, the concentration of the unreacted monomer component in the reaction solution at the time when the copolymerization reaction was completed was measured. As a result, the concentration of styrene was 0.1% and the concentration of acrylonitrile was 0.3%.
And no N-phenylmaleimide was detected.

Further, the content (proportion) of the low molecular weight component in the above thermoplastic copolymer was measured by GPC using tetrahydrofuran (THF) as a free liquid. As the molecular weight, a value determined in terms of standard polystyrene was adopted.
The calibration curve was prepared using a sample obtained by adding a known amount of a low molecular weight component to a thermoplastic copolymer containing no low molecular weight component.

As a result, the content of the low molecular weight component, which was determined from the ratio of the area of the entire thermoplastic copolymer to the area of the low molecular weight component, was 1.0%. Further, the low molecular weight component is separated by GPC using THF as a release liquid, and concentrated and concentrated.
Dried. When the infrared absorption spectrum (IR), ¹ H-NMR (nuclear magnetic resonance) spectrum and ¹³ C-NMR spectrum of the obtained low molecular weight component were measured, the low molecular weight component was found to be an unsaturated dicarboxylic acid derivative residue. N as
Phenylmaleimide residue was confirmed. Since X was 39, “0.1 × X” was 3.9.
It is. Therefore, the content of the low molecular weight component (1.0
%) Was found to be within the preferred range.

Next, the yellownesses YI ₁ and YI ₂ of the thermoplastic copolymer were measured. As a result, YI ₁ is 25.0,
YI ₂ was 33.0, and “YI ₂ / YI ₁ ” was 1.32. Further, since X was 39, “(1.5 × X ²
/ 100) +5 "is about 27.8. Therefore, it was found that the above thermoplastic copolymer satisfied the above inequalities (1) and (2). The above main reaction conditions and results are summarized in Table 1.

Example 2 The same copolymerization reaction and operation as in Example 1 were carried out except that the mixture (B) was continuously dropped over 2.0 hours. And the like to obtain a thermoplastic copolymer. The glass transition temperature of the thermoplastic copolymer was 165 ° C.

At the time when the mixture (A) was dropped, the concentration of unreacted styrene in the reaction solution was 4.0%, the concentration of acrylonitrile was 1.8%, and the concentration of N-phenylmaleimide was 0.1%. 1%. Therefore, the ratio of styrene to the unreacted monomer component in the reaction solution was 67.8%.
Met. Further, at the time when the copolymerization reaction was completed, the concentration of unreacted styrene in the reaction solution was 0.4%, the concentration of acrylonitrile was 0.2%, and N-phenylmaleimide was not detected.

The above thermoplastic copolymer has a styrene residue of 47%, an acrylonitrile residue of 14%,
-Contains 39% of phenylmaleimide residue (X = 39). The concentration of the thermoplastic copolymer in the reaction solution was 41.3%.

The content of the low molecular weight component in the thermoplastic copolymer measured in the same manner as in Example 1 was 1.0%
Met. Further, it was confirmed that the low molecular weight component contained an N-phenylmaleimide residue. X is 39
Therefore, “0.1 × X” is 3.9. Therefore, it was found that the content (1.0%) of the low molecular weight component was within a preferable range.

Next, the yellownesses YI ₁ and YI ₂ of the thermoplastic copolymer were measured. As a result, YI ₁ is 13.0,
YI ₂ was 17.0, and “YI ₂ / YI ₁ ” was 1.31. Further, since X was 39, “(1.5 × X ²
/ 100) +5 "is about 27.8. Therefore, it was found that the above thermoplastic copolymer satisfied the above inequalities (1) and (2). The above main reaction conditions and results are summarized in Table 1.

Example 3 The same procedure as in Example 1 was carried out except that the mixture (B) was continuously dropped over 3.5 hours. Finished the body composition. That is, the time required for dropping the mixture (A) and the time required for dropping the mixture (B) were made equal.

At the time when all the monomer components have been charged, that is, when the mixture (A) / (B) has been dropped, the concentration of unreacted styrene in the reaction solution is 3.2% and acrylonitrile is Was 1.7% and the concentration of N-phenylmaleimide was 1.7%. Therefore, the ratio of styrene to the unreacted monomer component in the reaction solution is 48.5%
Met.

When all the monomer components had been charged, the operation of distilling off a part of the reaction solution was started. That is,
Of the reflux liquid condensed by the reflux condenser, 10 parts were withdrawn. At the time when 10 parts of the reflux liquid was withdrawn, the concentration of unreacted styrene in the reaction solution was 3.5%, the concentration of acrylonitrile was 0.7%, and the concentration of N-phenylmaleimide was 0.9%. . Therefore, the ratio of styrene in the unreacted monomer components in the reaction solution was 68.6%.

Next, when 9 hours had passed since the start of the copolymerization reaction, the copolymerization reaction was terminated. afterwards,
The same operations and the like as in Example 1 were performed to separate the thermoplastic copolymer. The glass transition temperature of the obtained thermoplastic copolymer was 166 ° C.

Then, the composition of the thermoplastic copolymer was determined. As a result, the thermoplastic copolymer contained 47% of styrene residues, 13% of acrylonitrile residues, and 40% of N-phenylmaleimide residues (X = 40).
The concentration of the thermoplastic copolymer in the reaction solution was 45.
2%. Further, the concentration of the unreacted monomer component in the reaction solution at the time when the copolymerization reaction was completed was measured. As a result, the concentration of styrene was 0.3%, the concentration of acrylonitrile was 0.1%, and N-phenylmaleimide was not detected.

The content of the low molecular weight component in the thermoplastic copolymer measured in the same manner as in Example 1 was 1.1%
Met. Further, it was confirmed that the low molecular weight component contained an N-phenylmaleimide residue. X is 40
Therefore, “0.1 × X” is 4.0. Therefore, it was found that the content (1.1%) of the low molecular weight component was within a preferable range.

Next, the yellownesses YI ₁ and YI ₂ of the thermoplastic copolymer were measured. As a result, YI ₁ is 16.0,
YI ₂ was 22.0 and “YI ₂ / YI ₁ ” was 1.38. In addition, since X was 40, “(1.5 × X ²
/ 100) +5 "is 29.0. Therefore, it was found that the above thermoplastic copolymer satisfied the above inequalities (1) and (2). The above main reaction conditions and results are summarized in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that the mixture (B) was continuously dropped over 3.5 hours. That is, the time required for the mixture (A) to be dropped and the amount of the mixture (B) A copolymerization reaction and operation similar to the copolymerization reaction and operation of Example 1 were performed except that the time required for dropping was made equal to obtain a thermoplastic copolymer for comparison.
The glass transition temperature of the comparative thermoplastic copolymer is 164 ° C.
Met.

The concentration of unreacted styrene in the reaction solution at the time when the mixture (A) / (B) was dropped was 3.2.
%, The concentration of acrylonitrile was 1.7%, and the concentration of N-phenylmaleimide was 1.7%. Therefore, the proportion of styrene in the unreacted monomer components in the reaction solution is:
48.5%. Further, the concentration of unreacted styrene in the reaction solution at the time when the copolymerization reaction is completed is 0.1%.
%, The concentration of acrylonitrile was 0.4%, and N-phenylmaleimide was not detected.

The comparative thermoplastic copolymer has a styrene residue of 49% and an acrylonitrile residue of 1%.
3%, N-phenylmaleimide residue 38% (X = 3
8) contained. The concentration of the comparative thermoplastic copolymer in the reaction solution was 41.5%.

The content of the low molecular weight component in the comparative thermoplastic copolymer measured in the same manner as in Example 1 was as follows:
1.1%. Further, it was confirmed that the low molecular weight component contained an N-phenylmaleimide residue.
Since X was 38, “0.1 × X” is 3.8. Therefore, the content of the low molecular weight component (1.1%)
Was found to be within a preferred range.

Next, the yellowness Y of the comparative thermoplastic copolymer
I ₁ and YI ₂ were measured. As a result, YI ₁ is 3
0.0, YI ₂ is 52.0, and “YI ₂ / YI ₁ ” is 1.
73. Since X was 38, "(1.
5 × X ^2/100) +5 "is about 26.7. Therefore, it was found that the comparative thermoplastic copolymer did not satisfy the above inequalities (1) and (2). Further, it was found that the comparative thermoplastic copolymer was easier to be colored and had a higher recoloring property than the thermoplastic copolymer in Example 1. The above main reaction conditions and results are summarized in Table 1.

Comparative Example 2 In a reactor similar to the reactor of Example 1, 5.0 parts of styrene and 5.0 parts of acrylonitrile were added.
Parts and 47.3 parts of toluene. A polymerization initiator (manufactured by Kayaku Akzo);
0.2 parts of trade name Kayacarbonate BIC-75) were charged as a mixture (A), and 15.0 parts of styrene, 1.0 part of acrylonitrile, 16.0 parts of N-phenylmaleimide, and toluene were added to the other dropping device. A mixture (B) consisting of 10.7 parts was charged. The mixture (B) was prepared by mixing styrene, acrylonitrile, and N-phenylmaleimide in toluene, and then heating the mixture to 70 ° C. to dissolve the three.

Next, the temperature of the toluene solution was raised to 100 ° C. while stirring under a nitrogen atmosphere, and 0.05 parts of a polymerization initiator (same as above) was added to the toluene solution to carry out a copolymerization reaction. Started. After the start of the copolymerization reaction, the mixture (A) is continuously dropped into the reaction solution over 3.5 hours, and the mixture (B) kept at 70 ° C. is continuously dropped over 3.5 hours. It was dropped.

That is, in Example 1, the mixture (A)
The copolymerization reaction and operation of Example 1 were carried out except that the composition of (B) was changed as described above, and the time for dropping the mixture (A) was equal to the time for dropping the mixture (B). The same copolymerization reaction and operation as those described above were performed to obtain a thermoplastic copolymer for comparison. The glass transition temperature of the comparative thermoplastic copolymer was 152 ° C.

At the time when the mixture (A) / (B) was dropped, the concentration of unreacted styrene in the reaction solution was 3.1.
%, The concentration of acrylonitrile was 1.8%, and the concentration of N-phenylmaleimide was 1.7%. Therefore, the proportion of styrene in the unreacted monomer components in the reaction solution is:
47.0%. Further, the concentration of unreacted styrene in the reaction solution at the time when the copolymerization reaction is completed is 0.1%.
%, The concentration of acrylonitrile was 0.4%, and N-phenylmaleimide was not detected.

The above-mentioned thermoplastic copolymer for comparison has a styrene residue of 49% and an acrylonitrile residue of 1%.
3%, N-phenylmaleimide residue 38% (X = 3
8) contained. The concentration of the comparative thermoplastic copolymer in the reaction solution was 41.5%.

The content of the low molecular weight component in the comparative thermoplastic copolymer measured in the same manner as in Example 1 was as follows:
It was 5.3%. Further, it was confirmed that the low molecular weight component contained an N-phenylmaleimide residue.
Since X was 38, “0.1 × X” is 3.8. Therefore, the content of the low molecular weight component (5.3%)
Was found to be outside the preferred range. That is, as compared with the thermoplastic copolymer of Example 1, the comparative thermoplastic copolymer has a higher content of low molecular weight components.
For this reason, the glass transition temperature of the comparative thermoplastic copolymer is lower than the glass transition temperature of the thermoplastic copolymer of Example 1.

Next, the yellowness Y of the comparative thermoplastic copolymer
I ₁ and YI ₂ were measured. As a result, YI ₁ is 3
2.0, YI ₂ is 54.0, and “YI ₂ / YI ₁ ” is 1.
69. Since X was 38, "(1.
5 × X ^2/100) +5 "is about 26.7. Therefore, it was found that the comparative thermoplastic copolymer did not satisfy the above inequalities (1) and (2). Further, it was found that the comparative thermoplastic copolymer was easier to be colored and had a higher recoloring property than the thermoplastic copolymer in Example 1. The above main reaction conditions and results are summarized in Table 1.

[0100]

[Table 1]

[0101]

According to the method for producing a thermoplastic copolymer according to the first aspect of the present invention, as described above, a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer is copolymerized. Is a method for producing a thermoplastic copolymer, wherein at least a part or all of a vinyl cyanide monomer is charged into a reactor to initiate a copolymerization reaction, and then all monomer components are reacted. At the end of the charging, the weight of the unreacted aromatic vinyl monomer in the reaction solution becomes larger than the weight of the unreacted vinyl cyanide monomer.

As described above, the method for producing a thermoplastic copolymer according to claim 2 of the present invention is characterized in that the weight of the unreacted aromatic vinyl monomer in the reaction solution is In this method, the remaining monomer components are added to the reaction solution so as to be larger than the weight of the body.

In the method for producing a thermoplastic copolymer according to claim 3 of the present invention, as described above, the monomer component can be copolymerized with an aromatic vinyl monomer and a vinyl cyanide monomer. , An unsaturated dicarboxylic acid derivative.

In the method for producing a thermoplastic copolymer according to claim 4 of the present invention, as described above, an aromatic vinyl monomer and an unsaturated dicarboxylic acid derivative are separately added to a reaction solution. Is the way.

In the method for producing a thermoplastic copolymer according to the fifth aspect of the present invention, a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer is copolymerized as described above. Is a method for producing a thermoplastic copolymer, wherein at least a part or all of a vinyl cyanide monomer is charged into a reactor to start a copolymerization reaction, and then a vinyl cyanide monomer is charged. After finishing, the method is to finish charging the aromatic vinyl monomer.

In the method for producing a thermoplastic copolymer according to the sixth aspect of the present invention, a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer is copolymerized as described above. Is a method for producing a thermoplastic copolymer, wherein at least a part or all of a vinyl cyanide monomer is charged into a reactor to start a copolymerization reaction, and then the remaining monomer is added to a reaction solution. After adding the components and charging all the monomer components, unreacted vinyl cyanide monomer is distilled off from the reaction solution.

Therefore, the coloring property can be reduced, and the difference (the coloring property) between the coloring degree before heating and the coloring degree once heated can be reduced.
This makes it possible to obtain a thermoplastic copolymer which is excellent in various physical properties such as heat resistance and mechanical strength and is hardly colored. That is, it is possible to obtain a thermoplastic copolymer which is excellent in various physical properties such as heat resistance and mechanical strength, is hard to be colored, and can suppress recoloration during molding and the like. Play.

Further, by separately adding an aromatic vinyl monomer and an unsaturated dicarboxylic acid derivative to the reaction solution, in addition to the various effects described above, a heat-sensitive material having a relatively low proportion of low molecular weight components can be obtained. An effect that a plastic copolymer can be obtained is also exhibited.

The thermoplastic copolymer according to claim 7 of the present invention has a structure obtained by the method according to any one of claims 1 to 6 as described above.

As described above, the thermoplastic copolymer according to claim 8 of the present invention contains 5% by weight of aromatic vinyl monomer residues.
In the range of from about 85% by weight to 5% by weight of the vinyl cyanide monomer residue.
Wt.% To 35 wt.%, 10 to 50 wt.% Of unsaturated dicarboxylic acid derivative residues, and a vinyl monomer (b) residue copolymerizable with the above three monomers. A thermoplastic copolymer containing a group in the range of 0% to 20% by weight, and the yellowness of a 15% by weight chloroform solution of the thermoplastic copolymer is heated at 265 ° C. for 4 minutes at YI ₁ . thermoplastic copolymer after, yellowness YI ₂ of 15 wt% chloroform solution, when the weight percent of the unsaturated dicarboxylic acid derivative residue and _{X, YI 1 <(1.5 ×} X 2/100) +5 and YI ₂ / YI ₁ <1.5.

As described above, in the thermoplastic copolymer according to the ninth aspect of the present invention, the ratio of the low molecular weight component containing the residue of the unsaturated dicarboxylic acid derivative is (0.1 × X) or less. Configuration.

Therefore, the above-mentioned thermoplastic copolymer is excellent in various physical properties such as heat resistance and mechanical strength, and hardly colored. That is, the thermoplastic copolymer is excellent in various physical properties such as heat resistance and mechanical strength, and hardly colored,
In addition, there is an effect that the recoloring property at the time of molding or the like can be suppressed.

The ratio of the low molecular weight component is (0.1 ×
X) In the case of not more than the above, in addition to the various effects described above, the effect that a thermoplastic copolymer having more excellent heat resistance and impact resistance can be obtained can be obtained.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuchika Fujioka 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo 1 Nippon Shokubai Co., Ltd.

Claims (9)

[Claims] 1. A method for producing a thermoplastic copolymer by copolymerizing a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer, comprising: After starting the copolymerization reaction by charging part or all of the vinylated monomer, when all the monomer components have been charged, the weight of the unreacted aromatic vinyl monomer in the reaction solution is reduced. A method for producing a thermoplastic copolymer, characterized in that the weight is greater than the weight of unreacted vinyl cyanide monomer. 2. The remaining monomer components are added to the reaction solution so that the weight of the unreacted aromatic vinyl monomer in the reaction solution is greater than the weight of the unreacted vinyl cyanide monomer. The method for producing a thermoplastic copolymer according to claim 1, wherein 3. The method according to claim 1, wherein the monomer component further comprises an unsaturated dicarboxylic acid derivative copolymerizable with an aromatic vinyl monomer and a vinyl cyanide monomer. A method for producing a thermoplastic copolymer. 4. The method for producing a thermoplastic copolymer according to claim 3, wherein the aromatic vinyl monomer and the unsaturated dicarboxylic acid derivative are separately added to the reaction solution. 5. A method for producing a thermoplastic copolymer by copolymerizing a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer, comprising: A thermoplastic copolymer characterized in that after a part or all of the vinyl cyanide monomer is charged and the copolymerization reaction is started, the vinyl cyanide monomer is charged and then the aromatic vinyl monomer is charged. A method for producing a polymer. 6. A method for producing a thermoplastic copolymer by copolymerizing a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer, comprising: After charging a part or all of the vinyl monomer and starting the copolymerization reaction, the remaining monomer components are added to the reaction solution, and after all the monomer components have been charged, the reaction solution is used. A method for producing a thermoplastic copolymer, comprising removing unreacted vinyl cyanide monomer by distillation. 7. A thermoplastic copolymer obtained by the method according to any one of claims 1 to 6. 8. An aromatic vinyl monomer residue in an amount of 5 to 85% by weight.
5% by weight of vinyl cyanide monomer residue within the range of
To 35% by weight, an unsaturated dicarboxylic acid derivative residue in a range of 10% to 50% by weight, and a vinyl monomer (b) residue copolymerizable with the above three monomers. A thermoplastic copolymer containing 0% to 20% by weight of a 15% by weight chloroform solution of the thermoplastic copolymer having a yellowness of YI ₁ after heating at 265 ° C. for 4 minutes; The yellowness of a 15% by weight chloroform solution of a thermoplastic copolymer is represented by Y
I _2, when the weight percent of the unsaturated dicarboxylic acid derivative residue and X, characterized in that it is a ^{_{YI 1 <(1.5 × X 2}} /100) +5 and YI ₂ / YI ₁ <1.5 Thermoplastic copolymer. 9. The thermoplastic copolymer according to claim 8, wherein the proportion of the low molecular weight component containing the residue of the unsaturated dicarboxylic acid derivative is (0.1 × X) or less.