JP2008156400A - Highly transparent maleimide-olefin copolymer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly transparent maleimide-olefin copolymer containing little maleimide homopolymer causing adverse effect on transparency and to provide a method for producing the copolymer. <P>SOLUTION: The highly transparent maleimide-olefin copolymer is composed of a 2-4C olefin residue unit and a maleimide monomer residue unit and contains ≤500 ppm maleimide homopolymer composed of the maleimide monomer residue unit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a maleimide / olefin copolymer having excellent transparency, and more specifically, a highly transparent maleimide / olefin copolymer having a low content of a maleimide homopolymer that adversely affects transparency and its It relates to a manufacturing method.

  Maleimide copolymers are expected to be used in a wide range of applications such as optical materials and electronic parts as resins with excellent transparency, heat resistance and mechanical properties, and are generally produced by radical copolymerization. Many methods are proposed as a manufacturing method (for example, refer patent documents 1 and 2).

U.S. Pat. No. 2,971,939 JP 2006-036914 A

  However, according to the study of the present inventor, it has been found that the maleimide / olefin copolymer obtained by the method proposed in Patent Documents 1 and 2 still has a problem regarding transparency when used for optical applications. did. As a result of further investigation, it was found that the maleimide homopolymer produced as a by-product during the polymerization reaction adversely affects the transparency of the maleimide / olefin copolymer obtained by the conventional method.

  In the method proposed in Patent Document 1, after a polymerization solvent and a maleimide monomer are charged into a reactor, polymerization is carried out by simultaneously adding an olefin and a radical polymerization initiator. As a result of the radical polymerization reaction proceeding in a state where the monomer and the olefin monomer are not uniformly mixed, a maleimide homopolymer was produced at the initial stage of polymerization.

  In the method proposed in Patent Document 2, the maleimide monomer and the olefin copolymer are added during the polymerization of the maleimide monomer and olefin to control the copolymer composition of the maleimide / olefin copolymer. Since the polymerization proceeded in a state where the maleimide monomer was present inhomogeneously, a maleimide homopolymer was produced.

  Therefore, an object of the present invention is to provide a highly transparent maleimide / olefin copolymer having a low content of maleimide homopolymer and a method for producing the same.

  As a result of intensive studies to solve the above problems, the present inventor has found that a maleimide / olefin copolymer having a maleimide homopolymer content of a specific amount or less has extremely excellent transparency, and the present invention. It came to complete.

  That is, the first invention of the present invention is a maleimide / olefin copolymer comprising an olefin residue unit having 2 to 4 carbon atoms and a maleimide monomer residue unit represented by the following general formula (1). , A highly transparent maleimide / olefin copolymer, wherein the content of the maleimide homopolymer comprising the maleimide monomer residue unit is 500 ppm or less,

（１）
（ここで、Ｒ^１は水素、炭素数１〜６のアルキル基、シクロアルキル基またはフェニル基を示す。）
さらに、第２の発明は、炭素数２〜４個のオレフィン、下記一般式（２）で示されるマレイミド単量体及び重合溶剤を予め反応器に仕込み、均一混合を行い均一溶液とした後にラジカル重合開始剤を添加して重合反応を行うことを特徴とする高透明性マレイミド・オレフィン共重合体の製造方法に関するものである。

(1)
(Here, R ¹ represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, or a phenyl group.)
Furthermore, the second invention is a method in which an olefin having 2 to 4 carbon atoms, a maleimide monomer represented by the following general formula (2), and a polymerization solvent are previously charged in a reactor and mixed uniformly to obtain a uniform solution. The present invention relates to a method for producing a highly transparent maleimide / olefin copolymer, wherein a polymerization reaction is carried out by adding a polymerization initiator.

（２）
（ここで、Ｒ^２は水素、炭素数１〜６のアルキル基、シクロアルキル基またはフェニル基を示す。）
以下に、本発明について詳細に説明する。

(2)
(Here, R ² represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, or a phenyl group.)
The present invention is described in detail below.

  The highly transparent maleimide / olefin copolymer of the present invention has 2 to 4 carbon atoms in which the content of a maleimide homopolymer comprising a maleimide monomer residue unit represented by the general formula (1) is 500 ppm or less. It is a maleimide / olefin copolymer comprising the olefin residue unit and the maleimide monomer residue.

  Examples of the olefin residue unit having 2 to 4 carbon atoms constituting the highly transparent maleimide / olefin copolymer of the present invention include an ethylene residue unit, a propylene residue unit, a 1-butene residue unit, and 2-butene. Residue units, isobutene residue units, and the like are mentioned. Among them, an isobutene residue unit is preferable because it has a high molecular weight and a highly transparent maleimide / olefin copolymer excellent in heat resistance and mechanical properties can be obtained. . In addition, the olefin residue unit may be one type or a combination of two or more types.

R ¹ of the maleimide monomer residue unit constituting the highly transparent maleimide / olefin copolymer of the present invention represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, a phenyl group, and 1 carbon atom. Examples of the alkyl group of 6 to 6 include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Examples of the cycloalkyl group include a cyclobutyl group, a cyclopropyl group, and a cyclohexyl group. Can do. When the alkyl group, cycloalkyl group, or phenyl group has more than 6 carbon atoms, the excluded volume effect is large and the copolymerization reaction is difficult to proceed, making it difficult to obtain a copolymer. Examples of the maleimide monomer residue unit include a maleimide monomer residue unit, an N-methylmaleimide monomer residue unit, an N-ethylmaleimide monomer residue unit, and an N-propylmaleimide monomer residue. Group unit, N-butylmaleimide monomer residue unit, N-hexylmaleimide monomer residue unit, N-cyclopropylmaleimide monomer residue unit, N-cyclobutylmaleimide monomer residue unit, N -Cyclohexylmaleimide monomer residue units, N-phenylmaleimide monomer residue units, and the like. Among them, a highly transparent maleimide / olefin copolymer excellent in heat resistance and mechanical properties can be easily obtained. Therefore, an N-phenylmaleimide monomer residue unit is preferable. The maleimide monomer residue units can be used alone or in combination of two or more.

  Specific examples of the highly transparent maleimide / olefin copolymer of the present invention include, for example, maleimide / ethylene copolymer, maleimide / 1-butene copolymer, maleimide / isobutene copolymer, N-methylmaleimide / Ethylene copolymer, N-methylmaleimide / 1-butene copolymer, N-methylmaleimide / isobutene copolymer, N-ethylmaleimide / ethylene copolymer, N-ethylmaleimide / 1-butene copolymer, N -Ethylenemaleimide / isobutene copolymer, N-cyclohexylmaleimide / ethylene copolymer, N-cyclohexylmaleimide / 1-butene copolymer, N-cyclohexylmaleimide / isobutene copolymer, N-phenylmaleimide / ethylene copolymer N-phenylmaleimide / 1-butene copolymer, N-fluoro Nylphenylimide / isobutene copolymer, and the like. Among them, N-phenylmaleimide / isobutene is easily obtained because it becomes a highly transparent maleimide / olefin copolymer having high molecular weight and excellent heat resistance and mechanical properties. A copolymer is preferred.

  The highly transparent maleimide / olefin copolymer of the present invention achieves excellent transparency since the content of the maleimide homopolymer composed of the maleimide monomer residue unit is 500 ppm or less. It is preferable that it does not contain a maleimide homopolymer. When the content of the maleimide homopolymer exceeds 500 ppm, the object of the present invention cannot be achieved. Examples of the maleimide homopolymer include maleimide homopolymer, N-methylmaleimide homopolymer, N-ethylmaleimide homopolymer, N-propylmaleimide homopolymer, N-butylmaleimide homopolymer, and N-hexylmaleimide. Homopolymers, N-cyclopropylmaleimide homopolymers, N-cyclobutylmaleimide homopolymers, N-cyclohexylmaleimide homopolymers, and N-phenylmaleimide homopolymers can be exemplified.

  Further, since the highly transparent maleimide / olefin copolymer of the present invention exhibits particularly excellent transparency, the absorbance at a wavelength of 589 nm measured with a visible ultraviolet spectrophotometer in a 15% by weight methylene chloride solution. Is preferably a maleimide / olefin copolymer having a ratio of 0.3 or less.

Since the highly transparent maleimide / olefin copolymer of the present invention is a maleimide / olefin copolymer having excellent heat resistance and mechanical properties, it contains 55 to 65 mol% of the maleimide monomer residue unit amount. A maleimide / olefin copolymer is preferred. In addition, since it is excellent in moldability, mechanical properties, hue, etc., when measured at a temperature of 40 ° C. using N-methylpyrrolidone as a solvent using gel permeation chromatography (hereinafter referred to as GPC). the weight average molecular weight in terms of standard polystyrene value (Mw) is preferably a ^{1 × 10 5 ~3 × 10 5} .

  As the method for producing the highly transparent maleimide / olefin copolymer of the present invention, any production method can be used as long as it can produce a maleimide / olefin copolymer having a maleimide homopolymer content of 500 ppm or less. Specific examples of the production method that enables the highly transparent maleimide / olefin copolymer of the present invention to be produced particularly efficiently will be described below.

  The highly transparent maleimide / olefin copolymer of the present invention is prepared by previously charging an olefin having 2 to 4 carbon atoms, a maleimide monomer represented by the above general formula (2), and a polymerization solvent into a reactor in advance and mixing them uniformly. It becomes possible to manufacture efficiently by adding a radical polymerization initiator and carrying out a polymerization reaction after preparing a uniform solution. The reason why the production of maleimide homopolymer is suppressed by this production method is not clear, but when the mixed liquid of maleimide monomer, olefin and polymerization solvent is heterogeneous, it is isolated due to uneven local concentration in the polymerization reaction system. While the polymerization is likely to proceed, it is considered that local concentration unevenness is suppressed by using a uniform solution, and the copolymerization reaction proceeds efficiently.

  Here, examples of the olefin having 2 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, isobutene, etc. Among them, they easily have a high molecular weight and are excellent in heat resistance and mechanical properties. Isobutene is preferred because a highly transparent maleimide / olefin copolymer can be obtained. Moreover, this olefin can be used 1 type or in combination of 2 or more types.

R ² of the maleimide monomer represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, or a phenyl group. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, A butyl group, a hexyl group, etc. can be mentioned, As a cycloalkyl group, a cyclobutyl group, a cyclopropyl group, a cyclohexyl group etc. can be mentioned, for example. Examples of the maleimide monomer include maleimide monomer, N-methylmaleimide monomer, N-ethylmaleimide monomer, N-propylmaleimide monomer, N-butylmaleimide monomer, and N-hexylmaleimide. Monomer, N-cyclopropylmaleimide monomer, N-cyclobutylmaleimide monomer, N-cyclohexylmaleimide monomer, N-phenylmaleimide monomer, etc. Among them, heat resistance, An N-phenylmaleimide monomer is preferred because a highly transparent maleimide / olefin copolymer having excellent mechanical properties can be obtained. The maleimide monomers can be used alone or in combination of two or more.

  The amount of the olefin used in the copolymerization reaction of the maleimide monomer and olefin at this time is not limited as long as a highly transparent maleimide / olefin copolymer can be obtained. Since it is possible to produce a transparent maleimide / olefin copolymer, maleimide monomer: olefin = 1: 0.7-1: 2 (molar ratio) is preferable.

  As the polymerization solvent, a polymerization solvent capable of radical polymerization reaction may be used, and a known polymerization solvent can be used. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; tetrahydrofuran, tetrahydropyran, 1,4-dioxane, Cyclic ethers such as 1,3-dioxolane and cyclohexene oxide; acetates such as ethyl acetate, propyl acetate and butyl acetate; aromatic solvents such as benzene, toluene and xylene; acetates or aromatic solvents and alcohols In particular, it is excellent in the solubility of maleimide monomers and olefins, and a uniform solution can be easily obtained, making it possible to produce particularly excellent highly transparent maleimide / olefin copolymers. To methyl ethyl ketone. Further, the amount of the polymerization solvent is preferably 2 to 5 times the weight of the total amount of the olefin and the maleimide monomer.

  And this manufacturing method prepares a maleimide monomer, an olefin, and a polymerization solvent in a reactor prior to the polymerization reaction, and after mixing to make a uniform solution, a radical polymerization initiator is added to start the polymerization reaction. It is characterized by. As the reactor at that time, for example, a reactor having a stirring blade such as a full zone blade, a max blend blade, a fiddler blade, a paddle blade, a bull margin blade, etc. can be used. A homogeneous solution composed of a solvent can be obtained efficiently, and as a result, a highly transparent maleimide / olefin copolymer can be produced particularly efficiently, so that the stirring blade diameter / reactor inner diameter is 0.4 or more. Some reaction vessels are preferred. Further, a baffle plate may be attached to the reactor in order to improve the uniform mixing property. Furthermore, when efficiently preparing a homogeneous mixed solution of a maleimide monomer, an olefin, and a polymerization solvent, it is preferable to stir and mix at a temperature of 25 ° C. or higher where the solubility of the maleimide monomer is high.

  Examples of radical polymerization initiators include benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, t-butyl peroxyneodecanate, t-butyl peroxypivalate, and t-butyl peroxy-2-ethylhexanoate. , Organic peroxides such as t-hexylperoxy-2-ethylhexanoate; 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis- (2-butyronitrile), Azo initiators such as 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, 1,1'-azobis- (cyclohexane-1-carbonitrile) It is done. In addition, the radical polymerization initiator may be added as appropriate before the temperature increase, during the temperature increase, or during the reaction as long as it is after preparing a uniform solution comprising a maleimide monomer, an olefin, and a polymerization solvent. . Moreover, what is necessary is just to set suitably the polymerization temperature at the time of performing radical copolymerization reaction according to the decomposition temperature of this radical polymerization initiator, and generally it is preferable to carry out in 40 to 120 degreeC.

  In addition, when adjusting the molecular weight of the highly transparent maleimide / olefin copolymer to be produced, it is possible to adjust by adjusting the conditions such as monomer concentration, radical polymerization initiator concentration, polymerization temperature and the like. The chain transfer agent may be adjusted by adding a chain transfer agent. Examples of such a chain transfer agent include sulfur compounds such as lauryl mercaptan and sulfur; nitrogen compounds such as amine and urea; aldehydes such as benzaldehyde; α-methyl Examples include styrene dimers.

  The highly transparent maleimide copolymer of the present invention may be blended with other resins without departing from the object of the present invention. Examples of such resins include acrylonitrile-styrene resin and acrylonitrile-methyl methacrylate resin. , Methyl methacrylate resin, methyl methacrylate-styrene resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and the like.

  Since the highly transparent maleimide / olefin copolymer of the present invention has excellent transparency, it is suitable as a resin material for optical members.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

-Confirmation of structure of maleimide / olefin copolymer-
¹ H-NMR measurement was performed using a nuclear magnetic resonance measuring apparatus (trade name JSX, manufactured by JEOL Ltd.), and the structure was confirmed.

-Measurement of weight average molecular weight (Mw)-
N-methyl-2-pyrrolidone (NMP) was used as a solvent, and measurement was performed at 40 ° C. using GPC (trade name HLC-8020 GPC, manufactured by Tosoh Corporation).

~ Transparency evaluation ~
3 g of maleimide / olefin copolymer was dissolved in 17 g of methylene chloride, and the absorbance at a wavelength of 589 nm was measured with a visible ultraviolet spectrophotometer (trade name UVIDEC-650, manufactured by JASCO Corporation) to evaluate the transparency.

-Content of maleimide homopolymer and confirmation of its structure-
100 g of maleimide / olefin copolymer was dissolved in 900 g of methylene chloride and separated into a methylene chloride soluble part and an insoluble part by a centrifuge (trade name H-103N, manufactured by Kokusan). The weight was measured after drying at 100 ° C. under reduced pressure, and the content of methylene chloride insoluble part (maleimide homopolymer is insoluble in methylene chloride) was calculated. The structure of the obtained methylene chloride insoluble part was confirmed by ¹ H-NMR measurement using a nuclear magnetic resonance measuring apparatus (manufactured by JEOL Ltd., trade name: JSX).

Example 1
N-phenyl in an autoclave (stirring blade diameter / reactor inner diameter = 0.5) equipped with a Max blend type stirrer, baffle plate, nitrogen introduction pipe, olefin introduction pipe, initiator introduction pipe, thermometer, and deaeration pipe 359 g (2.07 mol) of maleimide and 595 g of methyl ethyl ketone as a polymerization solvent were charged and dissolved by stirring at 30 ° C. for 10 minutes. After purging with nitrogen at 30 ° C. for 20 minutes, 116 g (2.07 mol) of liquefied isobutene was introduced from the olefin introduction tube and stirred for 5 minutes to prepare a uniform solution. Thereafter, after adding 1.6 g of 97 wt% t-butylperoxy-2-ethylhexanoate as a radical polymerization initiator from the initiator introduction tube, the temperature was raised to 80 ° C. and the reaction was carried out for 5 hours. Table 1 shows the polymerization conditions.

  After completion of the polymerization reaction, the polymerization solution was added to a large amount of methanol to precipitate an N-phenylmaleimide / isobutene copolymer, and 432 g of N-phenylmaleimide / isobutene copolymer powder was recovered by drying at 100 ° C. under reduced pressure.

  When the structure of the obtained N-phenylmaleimide / isobutene copolymer was confirmed and the weight average molecular weight was measured, it contained 60.0 mol% of N-phenylmaleimide residue units and had Mw of 127,000.

  Furthermore, 100 g of N-phenylmaleimide / isobutene copolymer was dissolved in 900 g of methylene chloride and an attempt was made to measure the methylene chloride insoluble part. However, the content of the insoluble part was 0 ppm, and the N-phenylmaleimide homopolymer was not contained. Confirmed that there is no. Further, 3 g of N-phenylmaleimide / isobutene copolymer was dissolved in 17 g of methylene chloride, and the absorbance at a wavelength of 589 nm was measured with a visible ultraviolet spectrophotometer. As a result, the absorbance was 0.0. The transparency of the coalescence was excellent. Table 2 shows the evaluation results of the N-phenylmaleimide / isobutene copolymer.

Comparative Example 1
T-Butylperoxy-2-ethylhexanoate in an autoclave similar to Example 1 except that there was no baffle plate and a propeller-type stirrer was attached (however, stirring blade diameter / reactor inner diameter = 0.3) 1.6 g, 359 g (2.07 mol) of N-phenylmaleimide and 595 g of methyl ethyl ketone were charged simultaneously. The mixing system at this time was non-uniform. Then, after nitrogen substitution at 15 ° C., 116 g (2.07 mol) of isobutene was added, the temperature was raised to 80 ° C., and the reaction was performed for 5 hours. Table 1 shows the polymerization conditions.

  The N-phenylmaleimide / isobutene copolymer was recovered by the same method as in Example 1, and the copolymer composition and the weight average molecular weight were measured. The obtained N-phenylmaleimide / isobutene copolymer contained 60.4 mol% of N-phenylmaleimide residue units and had Mw120,000.

  Further, 100 g of N-phenylmaleimide / isobutene copolymer was dissolved in 900 g of methylene chloride, and an attempt was made to measure the insoluble part of methylene chloride, but the content of the insoluble part was 5000 ppm. It was confirmed that they were coalesced. Further, 3 g of N-phenylmaleimide / isobutene copolymer was dissolved in 17 g of methylene chloride, and the absorbance at a wavelength of 589 nm was measured with a visible ultraviolet spectrophotometer. As a result, the absorbance was 1.4, and N-phenylmaleimide · The isobutene copolymer was inferior in transparency. Table 2 shows the evaluation results of the N-phenylmaleimide / isobutene copolymer.

Example 2
In an autoclave similar to that in Example 1, 327 g (1.86 mol) of N-phenylmaleimide and 606 g of methyl ethyl ketone as a polymerization solvent were charged and stirred and dissolved at 30 ° C. for 10 minutes. After nitrogen substitution at 30 ° C. for 20 minutes, 84 g (1.49 mol) of liquefied isobutene was introduced from the olefin introduction tube, and the mixture was stirred for 5 minutes to prepare a uniform solution. Then, after adding 2.0 g of 71 wt% t-butyl peroxypivalate as a radical polymerization initiator from the initiator introduction tube, the temperature was raised to 60 ° C. and reacted for 5 hours. Table 1 shows the polymerization conditions.

  After completion of the polymerization reaction, the polymerization solution was added to a large amount of methanol to precipitate an N-phenylmaleimide / isobutene copolymer, and 387 g of N-phenylmaleimide / isobutene copolymer powder was recovered by drying at 100 ° C. under reduced pressure.

  When the structure of the obtained N-phenylmaleimide / isobutene copolymer was confirmed and the weight average molecular weight was measured, it contained 61.9 mol% of N-phenylmaleimide residue units and had Mw118000.

  Furthermore, 100 g of N-phenylmaleimide / isobutene copolymer was dissolved in 900 g of methylene chloride and an attempt was made to measure the methylene chloride insoluble part. However, the content of the insoluble part was 0 ppm, and the N-phenylmaleimide homopolymer was not contained. Confirmed that there is no. Further, 3 g of N-phenylmaleimide / isobutene copolymer was dissolved in 17 g of methylene chloride, and the absorbance at a wavelength of 589 nm was measured with a visible ultraviolet spectrophotometer. As a result, the absorbance was 0.0. The transparency of the polymer was excellent. Table 2 shows the evaluation results of the N-phenylmaleimide / isobutene copolymer.

Comparative Example 2
327 g (1.86 mol) of N-phenylmaleimide in an autoclave similar to Example 2 except that there was no baffle and a propeller-type stirrer was attached (however, stirring blade diameter / reactor inner diameter = 0.3) and 606 g of methyl ethyl ketone was charged, and after nitrogen substitution at 20 ° C., 84 g (1.49 mol) of isobutene and 2.0 g of t-butyl peroxypivalate were added simultaneously. The mixing system at this time was non-uniform. Then, it heated up to 60 degreeC and reacted for 5 hours. Table 1 shows the polymerization conditions.

  The N-phenylmaleimide / isobutene copolymer was recovered in the same manner as in Example 2, and the copolymer composition and the weight average molecular weight were measured. The obtained N-phenylmaleimide / isobutene copolymer contained 62.0 mol% of N-phenylmaleimide residue units and had Mw116000.

  Further, 100 g of N-phenylmaleimide / isobutene copolymer was dissolved in 900 g of methylene chloride, and an attempt was made to measure the insoluble part of methylene chloride. However, the content of the insoluble part was 900 ppm, and the insoluble part was N-phenylmaleimide homopolymer. It was confirmed that they were coalesced. Further, 3 g of N-phenylmaleimide / isobutene copolymer was dissolved in 17 g of methylene chloride, and the absorbance at a wavelength of 589 nm was measured with a visible ultraviolet spectrophotometer. As a result, the absorbance was 0.4, and N-phenylmaleimide · The isobutene copolymer was inferior in transparency. Table 2 shows the evaluation results of the N-phenylmaleimide / isobutene copolymer.

Claims (5)

A maleimide / olefin copolymer comprising an olefin residue unit having 2 to 4 carbon atoms and a maleimide monomer residue unit represented by the following general formula (1), comprising the maleimide monomer residue unit A highly transparent maleimide / olefin copolymer, wherein the content of the maleimide homopolymer is 500 ppm or less.

(1)
(Here, R ¹ represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, or a phenyl group.) 2. The highly transparent maleimide / olefin copolymer according to claim 1, wherein the absorbance at a wavelength of 589 nm measured with a visible ultraviolet spectrophotometer is 0.3 or less in a 15 wt% methylene chloride solution. 3. The highly transparent maleimide / olefin copolymer according to claim 1, wherein the olefin residue unit is an isobutene residue unit, and the maleimide monomer residue unit is an N-phenylmaleimide residue unit. Coalescence. An olefin having 2 to 4 carbon atoms, a maleimide monomer represented by the following general formula (2), and a polymerization solvent are previously charged in a reactor, mixed uniformly to obtain a uniform solution, and then a radical polymerization initiator is added to perform polymerization. A process for producing a highly transparent maleimide / olefin copolymer, characterized by carrying out a reaction.

(2)
(Here, R ² represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, or a phenyl group.) The method for producing a highly transparent maleimide / olefin copolymer according to claim 4, wherein a reactor having a stirring blade diameter / reactor inner diameter of 0.4 or more is used as the reactor.