JP2000248010A - Production of thermoplastic resin and maleimide-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for remarkably reducing the content of a non- reacted monomer in a thermoplastic resin produced from the specific monomer such as a maleimide-based monomer as a raw material, and to provide the maleimide-based polymer having the remarkably reduced content of the non- reacted monomer. SOLUTION: This method for producing a thermoplastic resin comprises polymerizing a monomer component containing an α,β-unsaturated dicarboxylic acid anhydride or its derivative. Therein, the characteristic comprises adding at least one compound selected from dienic compounds and/or their precursors, such as a cyclic diene compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a thermoplastic resin having a low content of unreacted monomers and a maleimide polymer having a low content of unreacted monomers.

[0002]

2. Description of the Related Art As a method for producing thermoplastic resins such as vinyl chloride resin, polystyrene, styrene-acrylonitrile resin, and polymethyl methacrylate, a vinyl monomer as a raw material thereof is polymerized in the absence of a solvent. Bulk polymerization method, a solution polymerization method of polymerizing using a solvent,
A suspension polymerization method or an emulsion polymerization method in which a monomer is dispersed or emulsified in water to perform polymerization is industrially employed.

[0003] The thermoplastic resins obtained by these methods are:
Since the mixture contains a volatile component such as an unreacted vinyl monomer and a solvent, it is necessary to remove the volatile component in order to obtain a thermoplastic resin useful as a molding material. In particular, the vinyl monomer, which is a raw material of these thermoplastic resins, has high reactivity, low molecular weight, irritation, odor, and toxicity. Therefore, reduction of the residual amount is generally required. Although the vinyl monomer is removed to some extent in the solvent removal step after polymerization, a vinyl monomer having a high boiling point, such as a maleimide-based monomer, tends to remain, so that further reduction is required. Further, a thermoplastic resin obtained by the same polymerization method can be used as it is in a paint or an adhesive without separating and removing volatile components, but in this case, in particular, a residual amount of a vinyl monomer. Reduction is required.

Heretofore, for example, a method of reducing the content of unreacted monomer by continuously adding a polymerization initiator after completion of addition of a monomer in a polymerization reaction (JP-A-2-51514) A method in which one monomer is excessively present to reduce the residual amount of the desired monomer in the case of a copolymer (Japanese Unexamined Patent Publication (Kokai) No. 63-175086); Method for reducing the residual amount of maleimide monomer by combining containers (Japanese Patent Laid-Open No. 3-20
No. 5411), a method of removing unreacted monomers by washing with methanol (Japanese Patent Application Laid-Open No. Sho 61-252211),
A method of reducing unreacted monomers by adding an inhibitor during aging (Japanese Patent Laid-Open No. 5-86105), and separating and removing unreacted monomers by precipitating a polymer in a poor solvent such as methanol or ether. (Japanese Patent Publication No. 43-9753) has been proposed.

[0005]

However, according to the method disclosed in Japanese Patent Application Laid-Open No. 2-51514, a low molecular weight polymer is produced to deteriorate the physical properties, or the effect of reducing unreacted monomers is insufficient. is there. Further, the method disclosed in JP-A-5-86105 is improved in that the production of a low molecular weight polymer can be suppressed, but has a problem of thermal coloring due to an inhibitor. Further, in the method of reducing the residual amount of a specific monomer to reduce the polymerization rate as in the methods described in JP-A-63-175086 and JP-A-3-205411, the composition distribution may occur or the effect may be insufficient. Has the disadvantage that Further, JP-A-61-252211, JP-B-43-9
In the method of extracting unreacted monomers from a polymer into a poor solvent as in the method of No. 753, a large amount of solvent is required,
Recruitment on an industrial scale is difficult. In recent years, environmental issues have become more and more important, and analytical methods have advanced, making it possible to quantify even small amounts of residual substances that were previously "below the detection limit". A problem may arise with the remaining amount.

[0006] In particular, a maleimide-based polymer using a maleimide-based monomer is very useful as a heat-resistant thermoplastic resin. However, the maleimide-based monomer remaining in the polymer causes coloring, and a food container. When it is used, it is eluted and causes a problem in safety. Therefore, further reduction is required. Therefore, the present invention is a method for significantly reducing the content of unreacted monomers in a thermoplastic resin from a specific monomer such as a maleimide-based monomer, and the content of unreacted monomers significantly It is an object to provide a maleimide-based polymer with a small amount. Similarly, another object is to reduce the content of unreacted monomers in a thermoplastic resin using α, β-unsaturated dicarboxylic anhydride or a derivative thereof as a raw material.

[0007]

Means for Solving the Problems In order to solve the above problems, the present invention provides the following configurations. In a method for producing a thermoplastic resin by polymerizing a monomer component containing a compound (A) which is an α, β-unsaturated dicarboxylic anhydride or a derivative thereof, at least one selected from a diene compound and / or a precursor thereof. A method for producing a thermoplastic resin, comprising adding one kind of compound (B).

[0008] A maleimide-based polymer in which the maleimide-based monomer unit is 30 to 60% by weight of the total monomer units, wherein the content of the maleimide-based monomer is 30 ppm or less. Based polymer.

[0009]

DETAILED DESCRIPTION OF THE INVENTION In the method for reducing unreacted monomers as in the above prior art, a polymer containing a monomer (compound (A)) such as a maleimide monomer has no effect. In addition, a polymer having a different composition and a different molecular weight is formed in the latter half of the polymerization reaction, so that the distribution of the composition and the molecular weight is apt to be widened, and the transparency and the performance are likely to be lowered. Therefore, in the present invention, the compound (A) having a very high reactivity with the compound (A) is used to convert the unreacted compound (A) into a substance which does not adversely affect the polymer. The purpose of the present invention is to reduce the amount of the compound (A) in the reaction, and to utilize the Diels-Alder reaction as a means for that purpose.

By utilizing the method of the present invention, α, β-
It is possible to reduce the content of unreacted monomers in a thermoplastic resin using an unsaturated dicarboxylic anhydride or a derivative thereof as a raw material. In particular, it is preferable to apply the invention to a maleimide-based polymer using a maleimide-based monomer as a raw material, because the amount of the unreacted maleimide monomer can be reduced.

Hereinafter, the present invention will be described in detail. The thermoplastic resin in the present invention is obtained by polymerizing a monomer component containing the compound (A), and is preferably a polymer of the compound (A) and another monomer copolymerizable therewith. Used. The compound (A) is an α, β-unsaturated dicarboxylic anhydride or a derivative thereof, and is a maleimide monomer; maleic acid, fumaric acid, itaconic acid, cytofuconic acid, mesaconic acid, ethyl maleic acid, methyl itaconic acid And dicarboxylic acids such as chloromaleic acid, bromomaleic acid, dichloromaleic acid, dibromomaleic acid and phenylmaleic acid, and anhydrides thereof.

Of these, maleimide monomers and maleic anhydride are preferably used. As the maleimide monomer, the following formula

[0013]

Embedded image

(Wherein R ¹ is hydrogen or C ¹ -C 1)
15 alkyl groups, cycloalkyl groups, substituted alkyl groups, aryl groups or substituted aryl groups. )) Can be preferably used. For example,
Maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N -Chlorophenylmaleimide, N-methylphenylmaleimide, N-bromophenylmaleimide, N-naphthylmaleimide, N-laurylmaleimide, 2-hydroxyethylmaleimide, N-hydroxyphenylmaleimide, N
-Methoxyphenylmaleimide, N-carboxyphenylmaleimide, N-nitrophenylmaleimide, and the like, and one or more of these can be used. By using N-phenylmaleimide and N-cyclohexylmaleimide among these, a maleimide-based polymer having excellent transparency and heat resistance can be obtained.

Other monomers copolymerizable with the compound (A) are not particularly limited, but include unsaturated carboxylic acid alkyl ester monomers, aromatic vinyl monomers and cyanide. Examples include vinyl monomers.
These other monomers may be used alone or in combination of two or more. Examples of unsaturated carboxylic acid alkyl ester monomers include methyl (meth) acrylate,
Ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) Examples include alkyl (meth) acrylates such as acrylate, iso-nonyl (meth) acrylate, dodecyl (meth) acrylate, and stearyl (meth) acrylate. Among them, aliphatic alkyl (meth)
Acrylates are preferred, and methyl (meth) acrylate is particularly preferred.

As the aromatic vinyl monomer, for example,
Styrene, α-methylstyrene and the like can be mentioned. Of these, styrene is particularly preferred. Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile. Among these, acrylonitrile is particularly preferred. The amount of compound (A) used in all the monomer components is not particularly limited,
It is preferably 65% by weight, more preferably 10 to 60% by weight, and even more preferably 30 to 60% by weight. The compound (A) is excellent in heat resistance and compatibility in chemical structure, and a polymer containing the compound (A) is useful as a heat-resistant molding material or a heat-resistant modifier. Therefore, when the amount of the compound (A) is too small, the heat resistance of the thermoplastic resin tends to decrease, and when it is too large, the physical properties such as heat resistance and transparency of the thermoplastic resin tend to decrease.

Preferred thermoplastic resins in the present invention are:
It is a maleimide polymer. As a method for polymerizing a monomer component containing the compound (A) to obtain a thermoplastic resin, a normal polymerization method may be appropriately employed. For example, solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like can be mentioned. In the case of solution polymerization or bulk polymerization, a polymerization product is obtained in a state of being dissolved in a solvent, and in the case of suspension polymerization or emulsion polymerization, a polymerization product is obtained in a state of being dispersed in a dispersion medium such as water. When the polymerization product is dissolved in the solvent, the compound (A) and the compound (B) are easily mixed uniformly, and therefore, it is preferable to use solution polymerization or bulk polymerization. Preferred examples of the solvent include toluene, xylene, ethylbenzene, methyl ethyl ketone, dimethylformamide, methyl isobutyl ketone, and ethyl acetate.

In order to reduce the content of the unreacted compound (A) contained in the polymerization product obtained by the above-mentioned polymerization, in the present invention, the compound is prepared at least at any stage before, during or after the polymerization. (B) is added. Compound (B)
Is not particularly limited as long as it has high reactivity with the compound (A) and can be converted into a substance which does not adversely affect the thermoplastic resin by reacting with the unreacted compound (A) remaining in the system. Is preferably a compound selected from diene compounds and / or precursors thereof. Therefore, when the compound (B) is a diene compound, the compound (B) is converted into a diene compound when the compound (B) is a precursor of the diene compound. Allow Alder reaction. The substance obtained by this reaction is a substance that does not adversely affect the polymer even if it remains in the thermoplastic resin (specifically, does not cause coloring, etc.), or is easily removed together with volatile components. Since it does not easily remain, a thermoplastic resin having excellent transparency and heat resistance can be obtained.

The compound (B) is a compound selected from a diene compound and / or a precursor thereof. Specifically, for example, butadiene, 2,3-dimethylbutadiene, cyclohexadiene, furan, furfuryl alcohol, fulvene , Cyclopentadiene, 1,2,3,4-
Tetrachloro-5,5-dimethoxycyclopentadiene and its precursors. Here, the precursor of the diene compound is a compound that can generate a diene compound by heating. In particular, since the cyclic diene compound has high reactivity with the compound (A), the compound (A) which remains can be rapidly reduced by adding the compound to the polymerization solution,
preferable. Particularly preferred as compound (B) are cyclopentadiene, cyclohexadiene, furan, furfuryl alcohol and precursors thereof, and particularly preferred is dicyclopentadiene which is a precursor of cyclopentadiene.

The Diels-Alder reaction between the diene compound (B) and the compound (A) which is an α, β-unsaturated dicarboxylic anhydride or a derivative thereof proceeds rapidly.
Although the treatment temperature is not particularly limited, specifically, the temperature is preferably from room temperature (about 25 ° C) to about the polymerization temperature ± 30 ° C,
Particularly, 30 to 140 ° C. is preferable. Diene compound (B)
When the boiling point of the diene compound is extremely lower than the polymerization temperature, it is effective and preferable to lower the treatment temperature and add the diene compound to the gas phase to reduce the volatilization.

The compound (B) is added at least at any stage before, during or after the polymerization. However, since a large amount of the compound (A) remains in the reaction system during the polymerization reaction, when a diene compound is used as the compound (B),
Even when a precursor of a diene compound is used as the compound (B), if a chemical reaction from the precursor to the diene compound easily occurs under the polymerization reaction conditions, the reaction between the compound (A) and the diene compound is polymerization. Will happen during the reaction,
It is preferable to add the compound (B) to the polymerization product after the polymerization because the compound (B) does not inhibit the original polymerization reaction and the compound (B) does not have the effect of reducing the compound (A). Conversely, if a precursor is used as the compound (B) and the chemical reaction from the precursor to the diene compound hardly occurs under the polymerization reaction conditions, the compound (B) is added before or after the polymerization. be able to.

Therefore, when the compound (B) is added after the polymerization, the residual amount of the compound (A) in the polymerization product is determined within a range that does not affect the performance. It is preferable to previously reduce the temperature, the type and amount of the solvent, the polymerization method, and the like, and it is preferable to set the content to 1.0 to 0.01% by weight. When the compound (B) is added after the polymerization, the compound (A) and the compound (B) are mixed by stirring the polymerization product after the addition. Heating may be performed as necessary, or a certain reaction time may be taken. In particular, when the compound (B) is dicyclopentadiene which is a precursor of cyclopentadiene, dicyclopentadiene is a dimer of cyclopentadiene, and
Since it is decomposed by thermal decomposition at 60 ° C. to form cyclopentadiene, it is preferable to heat the mixture to the above-mentioned thermal decomposition temperature or higher after addition, more preferably 170 ° C. or higher, particularly preferably 190 ° C. or higher. When dicyclopentadiene is used, if the polymerization reaction is carried out at a temperature not higher than the above-mentioned thermal decomposition temperature, addition of dicyclopentadiene before or during polymerization does not affect the polymerization reaction, and the thermal decomposition temperature after polymerization is not affected. By heating and depolymerizing as described above, cyclopentadiene can be generated and reacted with the compound (A), so that the step of separately mixing the compound (B) becomes unnecessary.

Further, a method is preferred in which cyclopentadiene obtained by previously distilling dicyclopentadiene by simple distillation is added in the range of ordinary temperature to polymerization temperature and reacted with compound (A). The amount of the compound (B) to be added depends on the content of the compound (A) remaining in the polymerization product, but is preferably 10 to 0.01% by weight, and more preferably 5 to 0.
05% by weight is more preferred. When the amount is less than 0.01% by weight, the effect of reducing the compound (A) tends to be insufficient, and when the amount is more than 10% by weight, the effect of reducing the compound (A) does not improve so much. Undesirably results in a large amount of compound (B) remaining.

According to the method of the present invention, the content of compound (A) can be remarkably reduced as compared with the conventional method. As described above, in the maleimide-based polymer using the maleimide-based monomer, particularly, the content of the unreacted maleimide-based monomer is required to be reduced. In the maleimide polymer which is 30 to 60% by weight of the monomer unit, the content of the maleimide monomer is 30%.
ppm or less, and more preferably 20 ppm or less.
ppm or less, more preferably 15 ppm or less, and most preferably 10 ppm or less.

Looking at each of the other monomers copolymerized with the maleimide monomer, the maleimide monomer unit accounts for 10 to 40% by weight of the total monomer units, and the methyl methacrylate unit accounts for all monomer units. In the case of a methyl methacrylate-maleimide copolymer in which the monomer unit is 90 to 50% by weight and the other monomer units are 0 to 40% by weight of the total monomer unit, the reactivity of the maleimide monomer is conventionally known. And the maleimide-based monomer was easily retained, but according to the present invention, the content can be reduced to 100 ppm or less. Further, the maleimide-based monomer unit is 30 to 6 of all monomer units.
In a styrene-maleimide copolymer in which 0% by weight, styrene units are 70 to 40% by weight of all monomer units, and other copolymerizable monomer units are 0 to 30% by weight of all monomer units. The maleimide monomer is less likely to remain than the methyl methacrylate-maleimide copolymer, but according to the present invention, it can be further reduced as compared with the conventional one, and can be reduced to 20 ppm or less.

The thermoplastic resin obtained by the method of the present invention may be used without removing volatile components from a polymerization product, or may be used after removing volatile components, depending on the application. There is. For example, when used as a paint, an adhesive or the like, volatile components are removed in the use step, and a cross-linking agent or the like is added as necessary, so that the thermoplastic resin exhibits its performance as a target thermoplastic resin. On the other hand, when used for molding materials, films, etc., after removing volatile components in advance, they are heated and used in their respective forms.

The polymerization solution of the present invention, in which the diene compound (B) or the like is acted to reduce the amount of monomer components remaining in the polymerization solution to some extent, further reduces volatile components such as unreacted monomers and organic solvents. In the case of removal, it is generally preferable to remove by evaporation using a vacuum flash method, a thin film evaporation method, a heating devolatilization method such as a single or twin screw vented extruder, or a heating devolatilization apparatus. At this time, the compound (A) remaining in the polymerization solution
(Remaining monomer) is preferable because it can be further reduced in this evaporation removal step. In particular, when the volatile component is removed using the above-described extruder with a vent, it is more preferable because the remaining compound (A) can be effectively reduced.

Among them, the maleimide-based polymer of the present invention can be effectively used as a molding material or as a material for improving various properties such as heat resistance by being blended with various thermoplastic resins. Since the maleimide-based polymer of the present invention has a low content of residual maleimide-based monomer, it can be effectively used for food containers and the like where safety is required.

The maleimide-based polymer and the thermoplastic resin composition containing the maleimide-based polymer of the present invention preferably have a Diels-Alder adduct of the compound (A) and the compound (B) of not more than 500 ppm. It is. Preferably, 200 ppm or less, more preferably 100 ppm
It is as follows. In the present invention, the polymer having a specific amount of the Diels-Alder adduct and the composition have a small amount of the remaining compound (A) such as a maleimide-based monomer.
It is preferable because the safety is good and there are no problems (coloring, discoloration of the material with time, etc.) caused by residual monomers and the like.

The Diels-Alder adduct contained in the polymer or the composition of the present invention is preferable because it does not adversely affect the physical properties of the polymer or the thermoplastic resin composition of the present invention.

[0031]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, “parts” and “%” are unless otherwise specified.
The terms “parts by weight” and “% by weight” are respectively represented. [Method for measuring residual maleimide monomer content] The residual maleimide was measured by quantifying a chloroform solution of a sample by gas chromatography (GC-14A, manufactured by Shimadzu Corporation). In particular, measurements at levels below 20 ppm require N
An ion of m / z = 173 of phenylmaleimide was selected and measured by a mass chromatogram method by GC-MS (JEOL, manufactured by JEOL Ltd.). [Measurement method of heat resistance] JIS-K
According to -7121, using a differential scanning calorimeter (DCS-8230, manufactured by Rigaku Denki Co., Ltd.), using nitrogen gas atmosphere, α-alumina as a reference, 250
DSC measured at 10 ° C / min.
(Differential Scanning Co
Lorimetry) curve was calculated by the midpoint method. [Deflection temperature under load] The deflection temperature under load was determined for the test piece 812.
A load corresponding to a stress of 18.5 kgf / cm ² was applied to the center of the specimen (5 mm × 6 mm), the temperature was increased at a rate of 2 ° C./min, and the specimen was bent at a temperature at which a deflection of 0.26 mm was generated. Temperature. [Measurement of Optical Properties] A test piece was measured with a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: SZ-Σ80 COLOR MEA).
ASTMD1 using SURRING SYSTEM).
According to 003, the total light transmittance and the turbidity were measured. [Method of Measuring Polymer Composition] The polymer solution was diluted, poured into methanol, the polymer component was separated, filtered, and dried. It was calculated from the nitrogen content of a 3% solution of the sample in chloroform by infrared spectroscopy (infrared absorption method) and elemental analysis. [Analysis of Diels-Alder Reaction Adduct] The structure of the Diels-Alder reaction adduct corresponding to the maleimide monomer as the compound (A) of the present invention and the diene compound (B) used was determined by GC-MS (JEOL, JEOL Ltd.). Was detected and determined by a mass chromatogram method according to the method described in US Pat. Also,
The amount was measured by gas chromatography (manufactured by Shimadzu Corporation, GC
-14A type), and GC-MS for trace amounts. Example 1 First, a dropping tank was attached to a stainless steel polymerization tank with a stirrer having a content of 20 L, and 44.5 parts of methyl methacrylate, 5.0 parts of N-phenylmaleimide, and 0.1 part of N-phenylmaleimide were added.
Using 5 parts of methyl acrylate, 50 parts of toluene, and 0.02 parts of n-dodecyl mercaptan, and substituting with nitrogen, 0.1 parts of t-butyl peroxyisopropyl carbonate was added as a polymerization initiator. Polymerization was conducted at 100 to 110 ° C. for 3.5 hours under boiling point conditions. Thereafter, the temperature was maintained at 110 ° C. for 5.5 hours, followed by cooling to terminate the polymerization reaction. At this time, the content of residual N-phenylmaleimide in the polymerization solution was 510 ppm. The obtained maleimide-based copolymer had 10.5% of N-phenylmaleimide units, 88.5% of methyl methacrylate units,
It contained 1.0% of methyl acrylate units and had a glass transition temperature of 130 ° C.

After the polymerization, 1.5 parts of dicyclopentadiene was added to the polymerization solution, and the temperature was raised to 200 ° C. and maintained for 20 minutes. The pressure at this time was 3 kg / cm ² .
The polymer solution after cooling was colorless and transparent, and N-phenylmaleimide contained in the polymer solution was 40 ppm. The amount of the Diels-Alder reaction adduct was 450 ppm.
Met. Further, there was no change in the composition and Tg of the copolymer. Comparative Example 1 A polymerization liquid was obtained in the same manner as in Example 1, except that dicyclopentadiene was not added after the polymerization. The polymer solution after cooling is pale yellow and transparent,
The N-phenylmaleimide contained in this polymerization solution is 42
It was 0 ppm, and there was no change in the copolymer composition and Tg. [Comparative Example 2] In the same manner as in Example 1, except that dicyclopentadiene was added after the polymerization, 0.2 part of t-butylperoxyisopropyl carbonate as a polymerization initiator was added, and the same operation was performed. The polymer solution after cooling is pale yellow and transparent, the polymer solution contains 280 ppm of N-phenylmaleimide, and the composition of the copolymer is
The content was 10.1% of N-phenylmaleimide unit and 89.9% of methyl methacrylate unit, and Tg was 131 ° C. Example 2 Using the same apparatus as in Example 1, starting with 20.0 parts of styrene, 6.0 parts of acrylonitrile, 58.0 parts of toluene and 16.0 parts of N-phenylmaleimide 0.25 parts of t-butyl peroxyisopropyl carbonate was added as an agent,
Polymerization was carried out at a temperature of 00 to 115 ° C for 3.5 hours. afterwards,
After maintaining at 110 ° C. for 5.5 hours, the mixture was cooled to terminate the polymerization reaction. At this time, the content of the remaining N-phenylmaleimide was 180 ppm. Moreover, the obtained maleimide-based copolymer contained 49% of styrene units, 13% of acrylonitrile units, and 38% of N-phenylmaleimide units, and had a glass transition temperature of 169 ° C.

After the polymerization, 0.3 parts of cyclopentadiene obtained by previously distilling dicyclopentadiene at 170 ° C. is added to the polymerization solution, and then the mixture is aged for 2 hours at 110 ° C. which is the same as the polymerization temperature. Continued. The polymerization solution after this contained 28 ppm of N-phenylmaleimide. Further, the amount of the Diels-Alder reaction adduct was 130 ppm. Example 3 The same operation as in Example 2 was performed except that the amount of cyclopentadiene was changed to 1.5 parts. Remaining N
-The content of phenylmaleimide was 18 ppm.
The amount of the Diels-Alder reaction adduct was 110 pp.
m. Example 4 Cyclopentadiene in Example 3
The polymerization reaction solution after the addition of 5 parts was supplied to a vented 30 mmφ twin-screw extruder controlled at a cylinder temperature of 250 ° C., and the extruded strand was pelletized by vacuum devolatilization from the vent port to form a maleimide copolymer. A coalescence was obtained.
At this time, the temperature of the polymerization reaction liquid in the twin-screw extruder is 200 to 250.
° C. The content of residual N-phenylmaleimide contained in the obtained maleimide-based copolymer was 8 ppm. The amount of the Diels-Alder reaction adduct is 90 p.
pm.

A test piece having a thickness of 3 mm was prepared by injection molding using the maleimide-based copolymer. The obtained test piece had an HDT of 151 ° C., a total light of 89%, and a value of 1.6%.
Met. Comparative Example 3 A polymerization liquid was obtained in the same manner as in Example 2 except that cyclopentadiene was not added after the polymerization. The content of residual N-phenylmaleimide contained in the obtained polymerization solution was 175 ppm. Comparative Example 4 A maleimide-based copolymer was obtained in the same manner as in Example 4 except that cyclopentadiene was not added after the polymerization. The content of residual N-phenylmaleimide contained in the obtained maleimide-based copolymer is 1
It was 10 ppm. Example 5 A polymerization reaction was carried out for 3.5 hours in the same manner as in Example 2, and the same operation was carried out until the temperature was maintained at 110 ° C. for 5.5 hours. Was added and the reaction was continued at the same temperature for 2.0 hours, and then the polymerization reaction was terminated. The remaining N- at this time
The content of phenylmaleimide was 60 ppm. Further, the obtained maleimide-based copolymer has a styrene unit of 5
It contains 2% of acrylonitrile units and 36% of N-phenylmaleimide units, and has a glass transition temperature of 1%.
67 ° C.

After the polymerization, 1.0 part of cyclopentadiene obtained by previously distilling dicyclopentadiene at 170 ° C. is added to the polymerization solution, and the mixture is aged at 110 ° C. for 2 hours at the same polymerization temperature. Stirring was continued. The polymer solution after this contained 12 ppm of N-phenylmaleimide. The amount of the Diels-Alder reaction adduct was 40 ppm. Example 6 Cyclopentadiene in Example 5
The polymerization reaction solution after the addition of 0 part is supplied to a vented 30 mmφ twin-screw extruder controlled at a cylinder temperature of 250 ° C., and the extruded strand is pelletized by vacuum devolatilization from the vent port to form a maleimide copolymer. A coalescence was obtained.
The content of residual N-phenylmaleimide contained in the obtained maleimide-based copolymer was 7 ppm. This time 2
The polymerization reaction liquid temperature in the screw extruder was 200 to 250 ° C. The amount of the Diels-Alder adduct was 40 p
pm.

Using the maleimide copolymer, a test piece having a thickness of 3 mm was prepared by injection molding. The obtained test piece was HDT 145 ° C., total light 84%, and value 5.3%.
Met.

[0037]

[Table 1]

As shown in Table 1, the content of the residual maleimide monomer is reduced in Examples in which dicyclopentadiene or cyclopentadiene is added. Moreover, the transparency and heat resistance of the maleimide-based copolymer have not changed or have been improved as compared with the case where dicyclopentadiene is not added, and the Diels-Alder reaction product of the maleimide-based monomer and dicyclopentadiene is It can be seen that this is not a substance that adversely affects the transparency and heat resistance of the copolymer.

[0039]

According to the present invention, the content of unreacted monomers in a thermoplastic resin starting from a specific monomer such as a maleimide monomer without adversely affecting transparency or heat resistance. Can be significantly reduced.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuchika Fujioka 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. F-term (reference) 4J011 AA02 PA23 PB40 PC03 PC08 4J100 AJ08P AJ09P AJ10P AK31P AK32P AK33P AM43P AM45P AM47P AM48P AM49P CA01 FA02 GB01 JA01 JA03

Claims (5)

[Claims] 1. A method for producing a thermoplastic resin by polymerizing a monomer component containing an α, β-unsaturated dicarboxylic anhydride or a compound (A) which is a derivative thereof, comprising the steps of: A method for producing a thermoplastic resin, comprising adding at least one compound (B) selected from a body. 2. The method for producing a thermoplastic resin according to claim 1, wherein the compound (B) is a cyclic diene compound. 3. The compound (A) according to claim 1, wherein the compound (A) is either a maleimide monomer or maleic anhydride.
The method for producing a thermoplastic resin according to any one of the above. 4. The method for producing a thermoplastic resin according to claim 1, wherein the content of the unreacted compound (A) contained in the thermoplastic resin is 20 ppm or less. 5. A maleimide polymer wherein the maleimide monomer unit is 30 to 60% by weight of the total monomer unit,
A maleimide-based polymer, wherein the content of the maleimide-based monomer is 30 ppm or less.