Method for producing polymers, and resin compositions

Abstract

To provide a method for efficiently producing an N-alkylmaleimide-based polymer having excellent optical characteristics, heat resistance and mechanical strength.SOLUTION: A method for producing an N-alkylmaleimide-based polymer includes suspension-polymerizing a monomer mixture comprising 20-100 wt.% of an N-alkylmaleimide represented by the following general formula (1) and 0-80 wt.% of other copolymerizable monomer, using an oil-soluble radical polymerization initiator, in an aqueous medium, in the presence of one or more dispersants selected from the group consisting of a nonionic compound which is coupled to oxygen or nitrogen and has no hydrogen, a polyacrylic acid salt and polyalkylene glycol. In the general formula (1), R represents a straight-chain alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing N-alkylmaleimide polymers and resin compositions, and more specifically, to a method for efficiently producing N-alkylmaleimide polymers having excellent optical properties, heat resistance, and mechanical strength, and to resin compositions containing N-alkylmaleimide polymers. [Background technology]

[0002] Homopolymers or copolymers obtained from N-alkylmaleimide (N-alkylmaleimide polymers) are known to exhibit higher heat resistance and superior transparency compared to general thermoplastic vinyl polymers. Therefore, N-alkylmaleimide polymers are promising materials as transparent resins that can be used in a variety of applications in the field of optics (see, for example, Non-Patent Document 1).

[0003] N-alkylmaleimide polymers, including alternating copolymers of N-alkylmaleimide and vinyl aromatic hydrocarbons such as styrene, have been reported to enable the creation of polymer materials with simple compositions, low birefringence, and the ability to maintain this low birefringence over a wide range of ambient temperatures (see, for example, Patent Document 1).

[0004] N-alkylmaleimide polymers can be produced by radical polymerization. Furthermore, they can be produced by conventionally known methods such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization. However, bulk polymerization has the problem of requiring special manufacturing equipment due to the difficulty of heat removal and the difficulty of removing unreacted monomers. Emulsion polymerization has the problem of difficulty in removing emulsifiers, resulting in impaired polymer transparency. Solution polymerization has the problem of producing polymers with relatively low molecular weights and insufficient mechanical strength. On the other hand, suspension polymerization is an industrially preferred manufacturing method because it allows for easy temperature control of the polymerization system, yields high molecular weight polymers, and allows for relatively easy removal of monomers after polymerization. However, suspension polymerization also has the problem of difficulty in removing dispersants, resulting in impaired polymer transparency.

[0005] In response to this, suspension polymerization using water-soluble celluloses as a dispersant has been proposed as a method for producing N-alkylmaleimide polymers with excellent transparency (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-126229 [Patent Document 2] Japanese Patent Publication No. 2009-102495 [Patent Document 3] Japanese Patent Publication No. 2009-215346 [Non-patent literature]

[0007] [Non-Patent Document 1] Takayuki Otsu, "Future Materials," Vol. 3, No. 1, pp. 74-79. [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in suspension polymerization using water-soluble celluloses as dispersants, it cannot yet be said to be sufficient, and further improvement is desired.

[0009] The present invention has been made in view of the above problems, and an object thereof is to provide a method for efficiently producing an N-alkyl maleimide polymer having excellent optical properties, heat resistance, and mechanical strength, and related technologies.

Means for Solving the Problems

[0010] As a result of intensive studies to solve the above problems, the present inventors have found a method for producing an N-alkyl maleimide polymer by suspension polymerization using a specific dispersant, and have completed the present invention.

[0011] That is, Embodiment 1 of the present invention comprises a monomer mixture consisting of 20 to 100% by weight of an N-alkyl maleimide represented by the following general formula (1) and 0 to 80% by weight of other copolymerizable monomers, and a nonionic compound having no hydrogen bonded to oxygen or nitrogen, polyacrylate, and polyalkylene glycol. The present invention relates to a method for producing an N-alkyl maleimide polymer, which comprises suspension polymerization in an aqueous medium using an oil-soluble radical polymerization initiator in the presence of at least one dispersant selected from the group consisting of:

Chemical formula

[0012] In the production method according to Embodiment 2 of the present invention, in addition to the configuration of Embodiment 1 described above, R is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a hexyl group, a cyclohexyl group, or an octyl group.

[0013] In the production method according to embodiment 3 of the present invention, in addition to the configuration of embodiment 1 or 2 described above, the other copolymerizable monomer is a vinyl aromatic hydrocarbon, an olefin, an alkyl acrylate, an alkyl methacrylate, or a vinyl carboxylate.

[0014] In the manufacturing method according to aspect 4 of the present invention, in addition to the configuration of any one of aspects 1 to 3 described above, the dispersant is at least one selected from the group consisting of polyvinylpyrrolidone, sodium polyacrylate, and polyethylene glycol.

[0015] In the manufacturing method according to aspect 5 of the present invention, in addition to the configuration of any one of aspects 1 to 4 described above, the weight-average molecular weight of the N-alkylmaleimide polymer is 200,000 to 2,000,000.

[0016] The production method according to embodiment 6 of the present invention further includes, in addition to any one of embodiments 1 to 5 described above, filtering the N-alkylmaleimide polymer obtained by suspension polymerization, washing the N-alkylmaleimide polymer with a solvent that dissolves the dispersant without dissolving the N-alkylmaleimide polymer, and washing the N-alkylmaleimide polymer with a solvent that dissolves unreacted monomers without dissolving the N-alkylmaleimide polymer.

[0017] Furthermore, aspect 7 of the present invention relates to a resin composition comprising 100 parts by weight of an N-alkylmaleimide polymer consisting of 20 to 100% by weight of an N-alkylmaleimide residue represented by the following general formula (1A) and 0 to 80% by weight of other copolymerizable monomer residues, and 2 parts by weight or less of at least one dispersant selected from the group consisting of nonionic compounds without hydrogen bonded to oxygen or nitrogen, polyacrylates, and polyalkylene glycols. [ka] Here, R represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.

Effects of the Invention

[0018] By the production method of the present invention, an N-alkyl maleimide-based polymer excellent in optical properties, heat resistance, and mechanical strength can be efficiently produced.

Modes for Carrying Out the Invention

[0019] Hereinafter, each aspect of the present invention will be described in detail. In this specification, the numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively.

[0020] <Production Method of N-Alkyl Maleimide-Based Polymer> The production method of an N-alkyl maleimide-based polymer according to one aspect of the present invention is to subject a monomer mixture composed of 20 to 100% by weight of N-alkyl maleimide represented by the following general formula (1) and 0 to 80% by weight of other copolymerizable monomers to suspension polymerization in an aqueous medium using an oil-soluble radical polymerization initiator in the presence of at least one dispersant selected from the group consisting of a nonionic compound having no hydrogen bonded to oxygen or nitrogen, a polyacrylate, and a polyalkylene glycol.

Chemical formula

[0021] The manufacturing method according to this embodiment allows for the efficient production of N-alkylmaleimide polymers with excellent optical properties, heat resistance, and mechanical strength. Specifically, films formed using polymers obtained by the manufacturing method according to this embodiment exhibit superior mechanical strength and transparency compared to films formed using polymers obtained by conventional suspension polymerization with dispersants. Furthermore, although the manufacturing method according to this embodiment uses suspension polymerization, which is simpler to operate than bulk polymerization, films formed using polymers obtained by this method exhibit excellent optical properties (transparency, low birefringence), heat resistance, and mechanical strength, similar to films formed using polymers obtained by bulk polymerization. Therefore, N-alkylmaleimide polymers with superior optical properties, heat resistance, and mechanical strength can be produced more efficiently than by bulk polymerization.

[0022] Examples of linear alkyl groups having 1 to 12 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, and dodecyl groups. Examples of branched alkyl groups having 3 to 12 carbon atoms include isopropyl, isobutyl, sec-butyl, and tert-butyl groups. Examples of cyclic alkyl groups having 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, and cyclohexyl groups. Among these, it is preferable that R is a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, cyclohexyl, or octyl group, as this results in a more heat-resistant N-alkylmaleimide polymer. Furthermore, because N-alkylmaleimides have high safety as compounds, reducing the need for safety measures in equipment, and can be manufactured efficiently and economically, ethyl groups, tert-butyl groups, and cyclohexyl groups are preferred as R in general formula (1). The N-alkylmaleimide represented by general formula (1) may be used alone or as a mixture of multiple types.

[0023] Specific examples of N-alkylmaleimides represented by general formula (1) include N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, N-sec-butylmaleimide, N-tert-butylmaleimide, N-pentylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-decylmaleimide, N-dodecylmaleimide, N-cyclopropylmaleimide, N-cyclobutylmaleimide, and N-cyclohexylmaleimide. Among these, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, N-sec-butylmaleimide, N-tert-butylmaleimide, N-hexylmaleimide, N-cyclohexylmaleimide, and N-octylmaleimide are preferred as N-alkylmaleimides, and N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-tert-butylmaleimide, and N-cyclohexylmaleimide are preferred because the resulting N-alkylmaleimide polymers have superior heat resistance. Furthermore, N-ethylmaleimide, N-tert-butylmaleimide, and N-cyclohexylmaleimide are even more preferred because they have high safety as compounds of N-alkylmaleimides, reduce safety measures on equipment, and can be manufactured efficiently and economically.

[0024] Examples of other copolymerizable monomers in one aspect of the present invention include vinyl aromatic hydrocarbons such as styrene and α-methylstyrene; olefins such as ethylene, propylene, 1-butene and isobutene; alkyl acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate; and vinyl carboxylates such as vinyl acetate, vinyl propionate and vinyl pivalate. Among these, vinyl aromatic hydrocarbons such as styrene and α-methylstyrene; alkyl acrylates such as methyl acrylate, ethyl acrylate, and butyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate are preferred, as they allow for the creation of N-alkylmaleimide polymers with a simple composition, low birefringence, and the ability to maintain this low birefringence over a wide range of ambient temperatures. Particularly preferred are vinyl aromatic hydrocarbons such as styrene and α-methylstyrene; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Other copolymerizable monomers may be used individually or in combination of multiple types.

[0025] In one embodiment of the present invention, the mixing ratio of the monomer mixture consisting of N-alkylmaleimide represented by general formula (1) and other copolymerizable monomers is 20 to 100% by weight of N-alkylmaleimide and 0 to 80% by weight of other copolymerizable monomers. Among these, a polymer with particularly excellent heat resistance and optical properties can be obtained, so it is preferably 35 to 100% by weight of N-alkylmaleimide and 0 to 65% by weight of other copolymerizable monomers, and more preferably 50 to 100% by weight of N-alkylmaleimide and 0 to 50% by weight of other copolymerizable monomers. Furthermore, since good photoelastic coefficient and intrinsic birefringence are obtained, it is particularly preferable to have 55 to 80% by weight of N-alkylmaleimide and 20 to 45% by weight of other copolymerizable monomers.

[0026] In one aspect of the present invention, the dispersant is a nonionic compound that does not have hydrogen bonded to oxygen or nitrogen. That is, the compound does not have hydrogen bonded to oxygen or nitrogen. Nonionic compounds that do not have hydrogen bonded to oxygen or nitrogen have weak interactions with N-alkylmaleimide polymers and can be efficiently removed by washing after polymerization. Because they can be efficiently removed by washing after polymerization, suspension polymerization using this compound yields N-alkylmaleimide polymers with excellent optical properties and mechanical strength. It should be noted that it has never been reported that transparency and mechanical strength can be improved by using nonionic compounds that do not have hydrogen bonded to oxygen or nitrogen.

[0027] Examples of nonionic compounds without hydrogen bonded to oxygen or nitrogen in one aspect of the present invention include polyoxyethylene alkyl ethers, poly(N-vinylamide), and polyoxypropylene / polyoxyethylene block copolymers.

[0028] Examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene myristyl ether, and polyoxyethylene octyldodecyl ether.

[0029] Examples of poly(N-vinylamide) include poly(N-vinylformamide), poly(N-vinylacetamide), poly(N-vinylisobutylamide), polyvinylpyrrolidone, and polyvinylcaprolactam. Among these, poly(N-vinylformamide), poly(N-vinylacetamide), and polyvinylpyrrolidone are particularly preferred because the resulting N-alkylmaleimide polymers are obtained as granular particles, and the poly(N-vinylamide) after polymerization can be removed more efficiently, resulting in N-alkylmaleimide polymers with superior optical properties and mechanical strength.

[0030] When polyvinylpyrrolidone is used as a nonionic compound that does not contain hydrogen bonded to oxygen or nitrogen, the viscosity property value (K value) calculated by Fikentscher's formula shown in formula (2) below is preferably 10 to 130. In particular, the obtained N-alkylmaleimide polymer is obtained as granular particles, and the water-soluble poly(N-vinylamide) after polymerization can be removed more efficiently, resulting in an N-alkylmaleimide polymer with superior optical properties and mechanical strength. Therefore, the K value is more preferably 20 to 125, and particularly preferably 30 to 120. K = (1.5 × logη) rel -1) / (0.15+0.003×c)+{300×c×logη rel +(c+1.5×c×logη rel ) 2} 1 / 2 / (0.15×c+0.003×c 2 ) (2) η rel : Relative viscosity of polyvinylpyrrolidone aqueous solution with respect to water c: Concentration of polyvinylpyrrolidone in an aqueous solution of polyvinylpyrrolidone (%).

[0031] Furthermore, in one embodiment of the present invention, the dispersant is a polyacrylate salt. Polyacrylate salts do not have hydrogen bonded to oxygen or nitrogen in the polyacrylic acid main chain excluding the cation portion, and therefore have weak interactions with N-alkylmaleimide polymers, and can be efficiently removed by washing after polymerization. As a result of being efficiently removed by washing after polymerization, suspension polymerization using this polyacrylate salt yields N-alkylmaleimide polymers with excellent optical properties and mechanical strength. It should be noted that the ability to improve transparency and mechanical strength by using polyacrylate salts has not been reported to date.

[0032] Examples of polyacrylates in one aspect of the present invention include sodium polyacrylate, potassium polyacrylate, calcium polyacrylate, magnesium polyacrylate, and ammonium polyacrylate. Among these, sodium polyacrylate is particularly preferred because the resulting N-alkylmaleimide polymer is obtained as granular particles, and the polyacrylate can be removed more efficiently after polymerization, resulting in an N-alkylmaleimide polymer with superior optical properties and mechanical strength.

[0033] When sodium polyacrylate is used as the polyacrylate, there are no particular restrictions on the weight-average molecular weight (Mw) of sodium polyacrylate. However, a weight-average molecular weight (Mw) of 100,000 to 5,000,000 is preferred, more preferably 500,000 to 3,000,000, and most preferably 1,000,000 to 3,000,000, as this allows the resulting N-alkylmaleimide polymer to be obtained as granular particles and enables efficient removal of sodium polyacrylate after polymerization, thereby obtaining an N-alkylmaleimide polymer with superior optical properties and mechanical strength.

[0034] Furthermore, in one embodiment of the present invention, the dispersant is polyalkylene glycol. Polyalkylene glycol is a polymer of alkylene oxide having 2 to 4 carbon atoms and has hydrogen atoms bonded to oxygen, but it has weak interaction with N-alkylmaleimide polymers and can be efficiently removed by washing after polymerization. As it can be efficiently removed by washing after polymerization, suspension polymerization using this polyalkylene glycol yields N-alkylmaleimide polymers with excellent optical properties and mechanical strength. It should be noted that the ability to improve transparency and mechanical strength by using polyalkylene glycol has not been reported to date.

[0035] Examples of polyalkylene glycols in one aspect of the present invention include polyethylene glycol, polypropylene glycol, polybutylene glycol, and polyoxyethylene polyoxypropylene glycol. Among these, polyethylene glycol is particularly preferred because the resulting N-alkylmaleimide polymer is obtained as granular particles, and the polyalkylene glycol after polymerization can be removed more efficiently, resulting in an N-alkylmaleimide polymer with superior optical properties and mechanical strength.

[0036] When polyethylene glycol is used as the polyalkylene glycol, there are no particular restrictions on the viscosity-average molecular weight of polyethylene glycol. However, a viscosity-average molecular weight of 20,000 to 10,000,000 is preferred, more preferably 150,000 to 8,000,000, and most preferably 1,000,000 to 5,000,000, as this allows the resulting N-alkylmaleimide polymer to be obtained as granular particles and enables efficient removal of the polyalkylene glycol after polymerization, thereby obtaining an N-alkylmaleimide polymer with superior optical properties and mechanical strength.

[0037] In one embodiment of the present invention, the dispersant is one or more selected from the group consisting of nonionic compounds that do not contain hydrogen bonded to oxygen or nitrogen, polyacrylates, and polyalkylene glycols. The dispersant may be used alone or in combination of multiple types.

[0038] In one aspect of the present invention, the amount of at least one dispersant selected from the group consisting of nonionic compounds without hydrogen bonded to oxygen or nitrogen, polyacrylates, and polyalkylene glycols is preferably 0.01 to 25 parts by weight per 100 parts by weight of the monomer mixture. In particular, the amount of dispersant added is more preferably 0.01 to 20 parts by weight, and especially preferably 0.01 to 15 parts by weight, because the resulting N-alkylmaleimide polymer is obtained as granular particles and the dispersant can be efficiently removed after polymerization, resulting in an N-alkylmaleimide polymer with superior optical properties and mechanical strength.

[0039] In one aspect of the present invention, oil-soluble radical polymerization initiators include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-tert-butyl peroxide, tert-butylcumyl peroxide, dicumyl peroxide, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-hexyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1,1, Examples include organic peroxides such as 3,3-tetramethylbutylperoxy-2-ethylhexanoate, tert-butylperoxypivalate, tert-hexylperoxypivalate, tert-butylperoxyneodecanoate, and tert-hexylperoxyneodecanoate, as well as azo initiators such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-butyronitrile), 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, and 1,1'-azobis(cyclohexane-1-carbonnitrile).

[0040] Furthermore, the amount of oil-soluble radical polymerization initiator used can be set as appropriate, for example, 0.0001 to 2 parts by weight per 100 parts by weight of monomer mixture. In particular, the resulting N-alkylmaleimide polymer exhibits superior optical properties and mechanical strength, so the amount of oil-soluble radical polymerization initiator used is preferably 0.001 to 1 part by weight, and more preferably 0.01 to 0.5 parts by weight.

[0041] In one embodiment of the present invention, the aqueous medium may be any medium that is normally treated as an aqueous medium, such as water, industrial water, deionized water, and distilled water. The amount of aqueous medium used is, for example, 100 to 500 parts by weight per 100 parts by weight of monomer mixture, and among these, 125 to 400 parts by weight is preferred, and particularly preferred is 150 to 300 parts by weight, in order to efficiently produce granular N-alkylmaleimide polymers.

[0042] In a manufacturing method according to one aspect of the present invention, when the N-alkylmaleimide is in a solid state, an oily medium may be added to efficiently produce the N-alkylmaleimide polymer by charging the N-alkylmaleimide in a solution state during the monomer charging process. As the oily medium, at least one selected from the group consisting of aromatic hydrocarbons, ethers, esters, ketones, and halogen compounds can be used.

[0043] Examples of aromatic hydrocarbons include toluene and xylene. Examples of ethers include diethyl ether and diisopropyl ether. Examples of esters include ethyl acetate, butyl acetate, and dimethyl carbonate. Examples of ketones include methyl ethyl ketone and methyl isobutyl ketone. Examples of halogen compounds include chloroform, methylene chloride, and 1,2-dichloroethane. Among these, aromatic hydrocarbons, ethers, esters, and ketones are preferred, with toluene and xylene being particularly preferred, in order to efficiently produce N-alkylmaleimide polymers with excellent mechanical strength.

[0044] Furthermore, when an oily medium is added, the amount used may be any amount as long as the manufacturing method of the present invention can be carried out. In particular, in order to efficiently produce an N-alkylmaleimide polymer having excellent mechanical strength, the amount used is preferably 0.01 to 70 parts by weight, more preferably 0.1 to 50 parts by weight, and especially preferably 5 to 25 parts by weight per 100 parts by weight of the monomer mixture.

[0045] In one embodiment of the manufacturing method of the present invention, the polymerization temperature can be appropriately set according to the decomposition temperature of the oil-soluble radical polymerization initiator. In particular, in order to efficiently produce an N-alkylmaleimide polymer having excellent optical properties and mechanical strength, the polymerization temperature is preferably in the range of 40 to 150°C, more preferably in the range of 50 to 90°C, and especially preferably in the range of 60 to 80°C.

[0046] In a manufacturing method according to one aspect of the present invention, in order to efficiently and economically produce an N-alkylmaleimide polymer having excellent optical properties and mechanical strength in granular form, it is preferable to include filtering the N-alkylmaleimide polymer obtained by suspension polymerization, washing the N-alkylmaleimide polymer with a solvent that dissolves a dispersant without dissolving the N-alkylmaleimide polymer, and washing the N-alkylmaleimide polymer with a solvent that dissolves unreacted monomers without dissolving the N-alkylmaleimide polymer.

[0047] A solvent that dissolves a dispersant without dissolving the N-alkylmaleimide polymer may also dissolve unreacted monomers as well as the dispersant. Similarly, a solvent that dissolves unreacted monomers without dissolving the N-alkylmaleimide polymer may also dissolve the dispersant as well as the unreacted monomers. That is, the solvent used may be one in which the N-alkylmaleimide polymer is insoluble and (i) only the dispersant is soluble, (ii) only the unreacted monomers are soluble, or (iii) both the dispersant and the unreacted monomers are soluble. Such solvents are not particularly limited and examples include water, methanol, ethanol, methanol / toluene mixed solvent, ethanol / toluene mixed solvent, methanol / water mixed solvent, and ethanol / water mixed solvent. For example, water is soluble in both the dispersant and the unreacted N-alkylmaleimide monomers. On the other hand, methanol, ethanol, methanol / toluene mixed solvent, ethanol / toluene mixed solvent, methanol / water mixed solvent, and ethanol / water mixed solvent are soluble in dispersants, unreacted N-alkylmaleimide monomers, and unreacted other copolymerizable monomers.

[0048] If the N-alkylmaleimide polymer is insoluble and both the dispersant and unreacted monomers are soluble in the solvent, the dispersant and unreacted monomers can be removed simultaneously with a single solvent. Alternatively, the dispersant and unreacted monomers may be removed individually using different solvents. When removing the dispersant and unreacted monomers individually, the N-alkylmaleimide polymer may be washed with a solvent that dissolves the dispersant, and then washed with a solvent that dissolves the unreacted monomers, or it may be washed with a solvent that dissolves the unreacted monomers, and then washed with a solvent that dissolves the dispersant. In order to efficiently remove the dispersant, it is preferable to wash the N-alkylmaleimide polymer with a solvent that dissolves the dispersant, and then wash the N-alkylmaleimide polymer with a solvent that dissolves the unreacted monomers, from the viewpoint of washing the dispersant while the N-alkylmaleimide polymer is swollen with unreacted monomers.

[0049] In addition, in one aspect of the present invention, if necessary, a chain transfer agent such as an alkyl mercaptan, or a hindered phenol-based or phosphorus-based antioxidant may be used at the initial stage of polymerization, during polymerization, or after polymerization.

[0050] The weight average molecular weight (M w ) of the N-alkyl maleimide-based polymer obtained by the production method in one aspect of the present invention is not particularly limited, but in order to produce an N-alkyl maleimide-based polymer having excellent optical properties and mechanical strength, it is preferably 200,000 to 2,000,000, more preferably 500,000 to 1,800,000, and particularly preferably 800,000 to 1,500,000. The weight average molecular weight (M w ) of the N-alkyl maleimide-based polymer can be controlled at the polymerization temperature.

[0051] The ratio of the unit derived from N-alkyl maleimide, that is, the N-alkyl maleimide residue, in the N-alkyl maleimide-based polymer obtained by the production method in one aspect of the present invention is in the range of 20 to 100% by weight. Among them, particularly, since an N-alkyl maleimide-based polymer having excellent heat resistance and optical properties can be obtained, it is preferably 35 to 100% by weight, more preferably 50 to 100% by weight.

[0052] The particle shape of the N-alkyl maleimide-based polymer obtained by the production method in one aspect of the present invention is not particularly limited, but by efficiently removing a dispersant, an unreacted monomer, or both, an N-alkyl maleimide-based polymer having excellent optical properties and mechanical strength can be obtained. Therefore, it is preferably granular, the average particle diameter is in the range of 20 to 2,000 μm, more preferably the average particle diameter is in the range of 30 to 1,000 μm, and particularly preferably the average particle diameter is in the range of 50 to 900 μm. Note that the average particle diameter in this specification is the particle diameter at which the cumulative particle amount based on volume determined by the laser diffraction / scattering method is 50%.

[0053] The glass transition temperature (Tg) of an N-alkylmaleimide polymer serves as an indicator of its heat resistance. While there are no particular limitations on the glass transition temperature (Tg) of an N-alkylmaleimide polymer obtained by one embodiment of the manufacturing method of the present invention, it is preferably 120°C or higher, more preferably 135°C or higher, and particularly preferably 150°C or higher, as this yields an N-alkylmaleimide polymer with excellent heat resistance.

[0054] The tensile stress of an N-alkylmaleimide polymer serves as an indicator of its mechanical strength. While there are no particular limitations on the tensile stress of an N-alkylmaleimide polymer obtained by one embodiment of the manufacturing method of the present invention, it is preferably 30 MPa or higher, more preferably 35 MPa or higher, and particularly preferably 40 MPa or higher, as this yields an N-alkylmaleimide polymer with excellent mechanical strength. Note that the tensile stress of an N-alkylmaleimide polymer is M w It can be controlled by [this method].

[0055] The tensile elongation, which is an indicator of the mechanical strength of the N-alkylmaleimide polymer obtained by the manufacturing method in one embodiment of the present invention, is not particularly limited. However, since an N-alkylmaleimide polymer with excellent mechanical strength can be obtained, it is preferably 1.5% or more, more preferably 2% or more, even more preferably 2.5% or more, and particularly preferably 3% or more.

[0056] The haze of an N-alkylmaleimide polymer is one of the indicators of its optical properties. The haze of an N-alkylmaleimide polymer obtained by one embodiment of the manufacturing method of the present invention is not particularly limited, but it is preferably less than 3%, more preferably less than 2.5%, and especially preferably less than 2%, in order to obtain an N-alkylmaleimide polymer with excellent transparency. The haze of an N-alkylmaleimide polymer can be controlled by the type of dispersant, the amount of dispersant remaining in the N-alkylmaleimide polymer, and the amount of monomer remaining.

[0057] Photoelastic constant (C) and intrinsic birefringence (Δn) of N-alkylmaleimide polymers 0The photoelastic constant (C) and intrinsic birefringence (Δn) of the N-alkylmaleimide polymer obtained by one embodiment of the manufacturing method of the present invention are one of the indicators of optical properties. 0 While there are no particular restrictions on the absolute values ​​of each, a low birefringence N-alkylmaleimide polymer is obtained, so preferably the absolute value of C is 50 × 10 -12 Pa -1 The following, and Δn 0 The absolute value is 20 × 10 -3 The following, and more preferably, the absolute value of C is 10 × 10 -12 Pa -1 The following, and Δn 0 The absolute value is 5 × 10 -3 The following is the case, and in particular, the absolute value of C is 2 × 10 -12 Pa -1 The following, and Δn 0 The absolute value is 1 × 10 -3 The following applies. Note that C and Δn of the N-alkylmaleimide polymer. 0 This constant can be controlled by the type of monomer and the ratio of monomer units, i.e., residues, in the N-alkylmaleimide polymer.

[0058] The temperature constant (dΔn) of the intrinsic birefringence of N-alkylmaleimide polymers. 0 The temperature constant (dΔn) of the intrinsic birefringence of an N-alkylmaleimide polymer obtained by one embodiment of the manufacturing method of the present invention is one of the indicators of optical properties. 0 While there are no particular restrictions on the absolute value of / dT, a preferred value of 2 × 10 is preferable because it yields an N-alkylmaleimide polymer that can maintain low birefringence over a wide range of ambient temperatures. -5 ℃ -1 The following, and more preferably 1 × 10 -5 ℃ -1 The following applies. Note that the dΔn of N-alkylmaleimide polymers 0 / dT is a constant that can be controlled by the type of monomer and the ratio of monomer units, i.e., residues, in the N-alkylmaleimide polymer.

[0059] <Resin composition> A resin composition according to one aspect of the present invention comprises 100 parts by weight of an N-alkylmaleimide polymer consisting of 20 to 100% by weight of an N-alkylmaleimide residue represented by the following general formula (1A) and 0 to 80% by weight of other copolymerizable monomer residues, and 2 parts by weight or less of at least one dispersant selected from the group consisting of nonionic compounds without hydrogen bonded to oxygen or nitrogen, polyacrylates, and polyalkylene glycols. The resin composition according to one aspect of the present invention can be produced by a method for producing an N-alkylmaleimide polymer according to one aspect of the present invention, which preferably includes washing the N-alkylmaleimide polymer.

[0060] [ka] Here, R represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.

[0061] A resin composition according to one aspect of the present invention can be produced by a method for producing an N-alkylmaleimide polymer according to one aspect of the present invention, which preferably includes washing the N-alkylmaleimide polymer. In other words, the N-alkylmaleimide residue represented by general formula (1A) is a residue derived from the N-alkylmaleimide represented by general formula (1). Therefore, the technical features of the N-alkylmaleimide residue represented by general formula (1A) can be described by referring to the description of the N-alkylmaleimide represented by general formula (1), and a detailed description thereof will be omitted. Similarly, in a resin composition according to one aspect of the present invention, the other copolymerizable monomers and at least one dispersant selected from the group consisting of nonionic compounds that do not have hydrogen bonded to oxygen or nitrogen, polyacrylates, and polyalkylene glycols are the same as the other copolymerizable monomers and at least one dispersant selected from the group consisting of nonionic compounds that do not have hydrogen bonded to oxygen or nitrogen, polyacrylates, and polyalkylene glycols described above. Therefore, since the explanations of each of these technical features can also be made by referring to the respective explanations of the method for producing an N-alkylmaleimide polymer according to one aspect of the present invention, their explanations will be omitted.

[0062] In one embodiment of the present invention, the content of at least one dispersant selected from the group consisting of nonionic compounds without hydrogen bonded to oxygen or nitrogen, polyacrylates, and polyalkylene glycols in the resin composition is 2 parts by weight or less per 100 parts by weight of the N-alkylmaleimide polymer. Among these, a resin composition with particularly excellent optical properties and mechanical strength is obtained, so it is preferably 0.01 to 2 parts by weight, and especially preferably 0.01 to 1.5 parts by weight.

[0063] <Application> The N-alkylmaleimide polymer obtained by the manufacturing method in one aspect of the present invention, and the resin composition in one aspect of the present invention, are excellent in heat resistance in addition to optical properties and mechanical strength, and can therefore be used in various optical components, optical lenses, optical sheets, optical films, and the like. [Examples]

[0064] The present invention will be described below based on examples, but the present invention is not limited in any way by these examples. Unless otherwise specified, commercially available reagents were used. Polyvinylpyrrolidone (PVP) K30 and K90 were special grade from Fujifilm Wako Pure Chemical Corporation. Polyvinylpyrrolidone (PVP) K120 was PVP K-120 from Ashland Japan Co., Ltd. Hydroxypropyl methylcellulose (HPMC) was Metroze® 90SH-100 from Shin-Etsu Chemical Co., Ltd. Polyethylene glycol (PEG) was first grade from Fujifilm Wako Pure Chemical Corporation. Sodium polyacrylate (NaPAA) was Alonbis® MX from Toagosei Co., Ltd. Tert-butyl peroxy-2-ethylhexanoate was Perbutyl O from NOF Corporation. Tert-butyl peroxypivalate was Perbutyl PV from NOF Corporation. 1-Dodecanethiol used was a special grade product from Fujifilm Wako Pure Chemical Industries, Ltd.

[0065] The following describes the evaluation and measurement methods for N-alkylmaleimide polymers obtained in the examples.

[0066] <Average particle size> 150 mg of N-alkylmaleimide polymer was dispersed in 20 g of deionized water and measured using a particle size distribution analyzer MT-3300 manufactured by Nikkiso Co., Ltd. The shape was set to a perfect sphere, and the refractive index was set to 1.549.

[0067] <Particle form> Using a Hitachi High-Tech TM3030Plus desktop microscope, the image signal was set to secondary electrons, and observations were performed in standard mode at magnifications of 30 to 100 times.

[0068] <N-alkylmaleimide content in the polymer> A predetermined amount of N-alkylmaleimide polymer was dissolved in deuterated chloroform (approximately 5% by weight), and the resulting solution was analyzed using a 400 MHz NMR spectrometer (JNM-ECZ400S / L1) from JEOL Ltd. 1 1H-NMR measurements were performed. For copolymers of N-alkylmaleimide and styrene, the N-alkylmaleimide content was calculated from the integral ratio of the peaks between 5.0 and 0.3 ppm to the peaks between 8.0 and 5.5 ppm.

[0069] <Molecular weight of polymer> Molecular weight distribution was measured using a Tosoh GPC (HLC-8320GPC). Two Tosoh TSKgel Super HM-H columns were used, the column temperature was set to 40°C, and tetrahydrofuran was used as the eluent. A molecular weight calibration curve was created using Tosoh standard polystyrene with known molecular weight.

[0070] <Dispersant content in resin composition> A predetermined amount of the resin composition is dissolved in deuterated chloroform (approximately 5% by weight), and the resulting solution is analyzed using a 400 MHz NMR spectrometer (JNM-ECZ400S / L1) from JEOL Ltd. 1 ¹H-NMR measurements were performed. For resin compositions of N-alkylmaleimide copolymers and PEG, the dispersant content was calculated from the ratio of the sum of the integrated peak values ​​of the N-alkylmaleimide polymer between 8.0 and 5.5 ppm and between 5.0 and 0.3 ppm to the integrated peak value of the dispersant at 3.6 ppm.

[0071] <Filming (1)> An N-alkylmaleimide polymer was dissolved in 10 times its volume of methylene chloride and spread onto a release PET film using an applicator. The PET film on which the polymer solution was spread was covered with a lid, and the solvent was slowly evaporated. The polymer film formed on the release PET film was peeled off and dried under reduced pressure in a vacuum dryer set to 105°C for 24 hours.

[0072] <Filming (2)> An N-alkylmaleimide polymer was added to chloroform and stirred using a magnetic stirrer or mixer to prepare a polymer solution of a predetermined concentration. The obtained polymer solution was filtered through a 30 μm PP filter and then spread onto a PET film using a coater. The film was dried by gradually increasing the temperature in the range of 60°C to 155°C using three ovens with different temperature settings. After drying, the polymer film formed on the PET film was peeled off, the four sides of the film were fixed, and it was dried again in the oven at a predetermined temperature to obtain a film with no residual solvent [<0.2 wt% (gas chromatography analysis)] and a thickness of approximately 50 μm.

[0073] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of the film obtained in <Film Forming (1)> was measured during the second scan heating (heating rate = 10°C / min) using a differential scanning calorimeter DSC-60 from Shimadzu Corporation.

[0074] <Tensile strength> Tensile strength was measured using an A&D TENSILON RTG-1210 universal material tester. The film obtained in <Film Formation (2)> was cut into strips 10 mm wide and 90 mm long to form test specimens. Tensile tests were performed under conditions of a chuck distance of 50 mm and a tensile speed of 30 mm / min, and the tensile elongation at fracture and tensile stress at fracture were measured.

[0075] <Hayes> To evaluate the transparency of the N-alkylmaleimide polymer, the haze of the film obtained in <Film Formation (2)> was measured using a spectroscopic haze meter (SH7000, Nippon Denshoku Industries Ltd.).

[0076] <Photoelastic constant> Measurements were taken using the ABR-EX automatic birefringence control device manufactured by UniOpt Inc. A film with a width of 4-5 mm and a thickness of 35-55 μm, prepared in <Film Forming (1)>, was subjected to stresses of 0-2 N at approximately 0.1 N intervals, and the phase difference was measured. The photoelastic constant C was calculated from the phase difference and the width of the measured area in the range of 0.3-2 N.

[0077] <Natural birefringence> The films prepared in <Film Forming (1)> were uniaxially stretched using an IMC-11A9 biaxial film stretching machine manufactured by Imoto Seisakusho at a temperature above Tg, a stretching speed of 40-100 mm / min, and a stretching ratio of 2-3 times. After that, the films were left to stand for more than 24 hours to relax the internal stress, and the absorbance in the infrared region was measured using a Shimadzu IRTracer-100 Fourier transform infrared spectrophotometer. The degree of orientation f of each stretched film was evaluated from the measured absorbance using the infrared two-color method. The thickness d of each film was measured with a micrometer. In addition, the phase difference Re of each stretched film was measured using an ABR-10A automatic birefringence control device manufactured by UniOpt. From the measured values ​​of degree of orientation f, film thickness d, and phase difference Re, the intrinsic birefringence Δn was calculated using the following formula (3). 0 The result was calculated. Re=Δn 0 ·f·d (3) <Temperature constant of intrinsic birefringence> A stretched film prepared using <intrinsic birefringence> was heated from 15°C to 70°C in 5°C increments, and the phase difference at each temperature was measured using the ABR-10A automatic birefringence control device manufactured by UniOpt Inc., and the temperature constant dΔn of intrinsic birefringence was measured. 0 / dT was calculated.

[0078] Example 1 In a 500 mL four-necked flask equipped with a stirrer, nitrogen inlet tube, and thermometer, 0.852 g of PVP K30, 346.4 g of distilled water, 103.9 g of N-ethylmaleimide, 25.8 g of styrene, 18.4 g of toluene, and 0.100 g of tert-butylperoxy-2-ethylhexanoate were added. After 1 hour of nitrogen bubbling, suspension polymerization was carried out by holding at 70°C for 2 hours while stirring at 600 rpm. After the suspension polymerization was complete, the contents were introduced into 2,500 g of distilled water stirred with a magnetic stirrer, and the resulting N-alkylmaleimide polymer particles were recovered by filtration. The recovered polymer particles were washed six times with 2,000 g of distilled water, and then five times with 1,582 g of methanol. Subsequently, the polymer particles were washed once with a mixed solvent of 487 g of toluene and 1,137 g of methanol, followed by five washes with 1,582 g of methanol. Furthermore, they were washed once with a mixed solvent of 827 g of toluene and 827 g of methanol, followed by five washes with 1,582 g of methanol. The washed polymer particles were placed in a dryer set to 95°C and dried under vacuum. Drying was stopped when there was no further weight loss due to drying, yielding 74.5 g of N-ethylmaleimide / styrene copolymer. Observation of the polymer particle morphology using a bench microscope revealed that the particle size ranged from approximately 50 μm to approximately 2,000 μm. Tables 1 and 2 show the polymerization composition, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the copolymer, and the dispersant content of the resin composition. Table 3 shows the solubility in chloroform and the haze of the resulting film.

[0079] Comparative Example 1 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 1, except that 0.852 g of hydroxypropyl methylcellulose (HPMC), a nonionic compound with hydrogen atoms bonded to oxygen, was used as a dispersant instead of PVP K30. As a result, 67.5 g of N-alkylmaleimide polymer was obtained. The starting composition for polymerization, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content in the N-alkylmaleimide polymer, Mw, and Mw / Mn are shown in Tables 1 and 2. The solubility in chloroform, mechanical strength of the film, and haze are shown in Table 3.

[0080] By using HPMC, a nonionic compound with hydrogen atoms bonded to oxygen, as a dispersant, a gel insoluble in chloroform was formed. Furthermore, when a film was formed, the haze value of the film increased, and the mechanical strength was lower than that of the N-alkylmaleimide copolymer produced in Example 2 described later, which had a nearly equivalent ratio of units derived from N-alkylmaleimide.

[0081] Example 2 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 1, except that the polymerization time was changed from 2 hours to 2.25 hours. As a result, 77.3 g of N-alkylmaleimide polymer was obtained. Observation of the particle morphology of the N-alkylmaleimide polymer particles using a bench microscope revealed that the particle size ranged from approximately 50 μm to approximately 2,000 μm. The starting composition for polymerization, yield, N-ethylmaleimide unit content in the N-alkylmaleimide polymer, Mw and Mw / Mn, and the dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform, heat resistance, mechanical strength, and optical properties of the film are shown in Table 3.

[0082] As shown in Tables 1 and 2, the N-ethylmaleimide unit content increased with increasing polymerization time. Furthermore, it exhibited mechanical strength, transparency, photoelastic constant, and intrinsic birefringence temperature constant equivalent to the N-alkylmaleimide polymer obtained by bulk polymerization as shown in Comparative Example 2 below.

[0083] Comparative Example 2 3.8 g of N-ethylmaleimide and 1.2 g of styrene were placed in a test tube and mixed. After sealing the test tube, the contents were mixed by shaking thoroughly. The test tube was left to stand in a 70°C water bath for 24 hours to allow bulk polymerization to occur. The resulting N-alkylmaleimide polymer was a cylindrical mass adhered to the inside of the test tube. To remove unreacted monomers, the cylindrical mass was removed from the test tube, crushed into approximately 1 cm cubes, and placed in methylene chloride to prepare a clear N-alkylmaleimide polymer solution. Then, the obtained N-alkylmaleimide polymer solution was added dropwise to methanol to precipitate the N-alkylmaleimide polymer. After filtration with filter paper to remove the filtrate containing dissolved unreacted monomers, the N-alkylmaleimide polymer remaining on the filter paper was collected and dried under reduced pressure in a desiccator for 3 hours. The polymer was then further dried under reduced pressure in a vacuum dryer at 105°C for 24 hours to obtain 4.0 g of N-alkylmaleimide polymer. The particle morphology of the N-alkylmaleimide polymer particles was visually amorphous. The starting composition for polymerization, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform, heat resistance, mechanical strength, and optical properties of the resulting film are shown in Table 3.

[0084] By producing an N-alkylmaleimide polymer by bulk polymerization, a polymer was obtained that possessed mechanical strength and transparency equivalent to the polymer obtained in Example 2, while also exhibiting low birefringence (low absolute value of both photoelastic constant and intrinsic birefringence), and maintaining its low birefringence over a wide range of ambient temperatures. However, unlike the production method in Example 2, the production method of Comparative Example 2 required additional steps to remove unreacted monomers: removing the produced N-alkylmaleimide polymer from the test tube, pulverizing it and dissolving it in a solvent, and precipitating the N-alkylmaleimide polymer from the resulting solution.

[0085] Comparative Example 3 6.1 g of N-ethylmaleimide, 2.7 g of styrene, 35.4 g of toluene, and 0.019 g of tert-butyl peroxypivalate were placed in a 75 mL ampoule tube. After degassing the ampoule tube, it was melt-sealed with a burner. The sealed ampoule tube was placed in a water bath (set to 50°C) attached to a shaker and shaken for 10 hours to carry out solution polymerization. The obtained product was added to 400 mL of chloroform to prepare a clear N-alkylmaleimide polymer solution. Then, the obtained N-alkylmaleimide polymer solution was added dropwise to methanol to precipitate the N-alkylmaleimide polymer. The solution was filtered through filter paper, and the N-alkylmaleimide polymer remaining on the filter paper was collected and dried under reduced pressure in a vacuum dryer set to 95°C for 10 hours to obtain 7.9 g of N-alkylmaleimide polymer. The particle morphology of the N-alkylmaleimide polymer particles was visually amorphous. Tables 1 and 2 show the starting composition for polymerization, yield, N-ethylmaleimide unit content in the N-alkylmaleimide polymer, Mw and Mw / Mn, and the dispersant content of the resin composition. Table 3 shows the solubility in chloroform, the heat resistance of the film, and the optical properties of the resulting film.

[0086] By producing the N-alkylmaleimide polymer by solution polymerization, the Mw was reduced compared to the polymer produced in Example 2. As a result, the resulting film became brittle, and its mechanical strength could not be evaluated.

[0087] Example 3 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 1, except that the polymerization time was changed from 2 hours to 5 hours. As a result, 84.1 g of N-alkylmaleimide polymer was obtained. Observation of the particle morphology of the N-alkylmaleimide polymer particles using a bench microscope revealed that the particle size ranged from approximately 50 μm to approximately 2,000 μm. The polymerization starter composition, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform is shown in Table 3.

[0088] As shown in Tables 1 and 2, the N-ethylmaleimide unit content increased with increasing polymerization time.

[0089] Example 4 The N-ethylmaleimide / styrene copolymer was produced in the same manner as in Example 2, except that the amount of PVP K30 added was changed to 17.04 g. As a result, 69.8 g of N-alkylmaleimide polymer was obtained. The average particle size of the N-alkylmaleimide polymer particles was 490 μm, and the generation of millimeter-order particles was suppressed by increasing the amount of PVP K30 added. The polymerization starter composition, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0090] Example 5 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 2, except that 0.852 g of PVP K30 was replaced with 3.04 g of PVP K90. As a result, 75.0 g of N-alkylmaleimide polymer was obtained. The average particle size of the N-alkylmaleimide polymer particles was 359 μm, and the change from PVP K30 to PVP K90 suppressed the generation of millimeter-order particles. The polymerization starter composition, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform is shown in Table 3.

[0091] Example 6 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 5, except that the polymerization time was changed from 2.25 hours to 5 hours. As a result, 83.4 g of N-alkylmaleimide polymer was obtained. The polymerization starter composition, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform is shown in Table 3.

[0092] As shown in Tables 1 and 2, the N-ethylmaleimide unit content increased with increasing polymerization time.

[0093] Example 7 The N-ethylmaleimide / styrene copolymer was produced in the same manner as in Example 6, except that the amount of N-ethylmaleimide added was changed to 98.1 g and the amount of styrene added to 31.8 g. The polymer composition, yield, average particle size of the N-alkylmaleimide polymer particles, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and the dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0094] As shown in Tables 1 and 2, the N-ethylmaleimide unit content in the N-alkylmaleimide polymer could be controlled by reducing the N-ethylmaleimide ratio in the polymerization preparation.

[0095] Example 8 The N-ethylmaleimide / styrene copolymer was produced in the same manner as in Example 6, except that the amount of N-ethylmaleimide added was changed to 70.5 g and the amount of styrene added to 58.7 g. The polymer composition, yield, average particle size of the N-alkylmaleimide polymer particles, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and the dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the heat resistance of the resulting film are shown in Table 3.

[0096] As shown in Tables 1-3, by reducing the N-ethylmaleimide ratio in the polymerization preparation, the N-ethylmaleimide unit content in the N-alkylmaleimide polymer could be controlled. Compared to the film produced in Example 2, which had an N-ethylmaleimide unit content of 68% by weight, the Tg was lower, and the heat resistance of the film could be controlled.

[0097] Example 9 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 5, except that the amount of PVP K90 added was changed to 0.856 g. As a result, 73.4 g of N-alkylmaleimide polymer was obtained. The average particle size of the N-alkylmaleimide polymer particles was 335 μm, and the average particle size was almost maintained even when the amount of PVP K90 added was reduced. The polymerization starter composition, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0098] Example 10 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 5, except that the amount of PVP K90 added was changed to 0.416 g. As a result, 75.8 g of N-alkylmaleimide polymer was obtained. The average particle size of the N-alkylmaleimide polymer particles was 429 μm, and the average particle size tended to increase as the amount of PVP K90 added was reduced to 0.416 g. The starting composition for polymerization, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0099] As shown in Table 3, reducing the amount of PVP K90 added showed a tendency to decrease the haze of the film.

[0100] Example 11 The N-cyclohexylmaleimide / styrene copolymer was prepared in the same manner as in Example 8, except that 81.7 g of N-cyclohexylmaleimide was used instead of N-ethylmaleimide and the amount of styrene added was changed to 47.5 g. The polymerization composition, yield, average particle size of N-alkylmaleimide polymer particles, N-cyclohexylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and the dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the heat resistance of the resulting film are shown in Table 3.

[0101] Example 12 The N-tert-butylmaleimide / styrene copolymer was prepared in the same manner as in Example 8, except that 77.1 g of N-tert-butylmaleimide was used instead of N-ethylmaleimide and the amount of styrene added was changed to 52.4 g. The polymerization composition, yield, average particle size of N-alkylmaleimide polymer particles, N-tert-butylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and the dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the heat resistance of the resulting film are shown in Table 3.

[0102] Example 13 The N-ethylmaleimide / styrene copolymer was produced in the same manner as in Example 1, except that the polymerization time was changed from 2 hours to 3 hours, PVP K30 was changed to PVP K120, and tert-butylperoxy-2-ethylhexanoate 0.100 g was changed to 0.164 g. As a result, 79.9 g of N-alkylmaleimide polymer was obtained. The average particle size of the N-alkylmaleimide polymer particles was 297 μm, and the change from PVP K30 to PVP K120 suppressed the generation of millimeter-order particles. The polymerization starter composition, yield, N-ethylmaleimide unit content in the N-alkylmaleimide polymer, Mw and Mw / Mn, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0103] Example 14 The N-ethylmaleimide / styrene copolymer was produced in the same manner as in Example 13, except that the amount of N-ethylmaleimide added was changed to 104.5 g, the amount of styrene added to 29.0 g, the amount of toluene added to 14.9 g, and the amount of PVP K120 added to 0.276 g. As a result, 83.5 g of N-alkylmaleimide polymer was obtained. The polymer composition, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0104] Example 15 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 13, except that 0.855 g of PVP K120 was replaced with 0.216 g of sodium polyacrylate. As a result, 83.1 g of N-alkylmaleimide polymer was obtained. The starting composition for polymerization, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content in the N-alkylmaleimide polymer, Mw and Mw / Mn, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0105] Example 16 The N-ethylmaleimide / styrene copolymer was produced in the same manner as in Example 14, except that the amount of N-ethylmaleimide added was changed to 103.3 g, the amount of styrene added to 30.2 g, and 0.276 g of PVP K120 was replaced with 0.075 g of polyethylene glycol. As a result, 87.5 g of N-alkylmaleimide polymer was obtained. The polymer composition, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform, heat resistance of the film, and optical properties are shown in Table 3.

[0106] Example 17 The N-ethylmaleimide / styrene copolymer was prepared in the same manner as in Example 16, except that the amount of polyethylene glycol added was changed to 0.031 g. As a result, 91.2 g of N-alkylmaleimide polymer was obtained. The polymerization starter composition, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform, heat resistance of the film, and optical properties are shown in Table 3.

[0107] Example 18 In a 500 mL four-necked flask equipped with a stirrer, nitrogen inlet tube, and thermometer, 0.860 g of PVP K30, 347.1 g of distilled water, 99.2 g of N-ethylmaleimide, 22.6 g of styrene, 26.9 g of methyl methacrylate, and 0.185 g of tert-butylperoxy-2-ethylhexanoate were placed. After 1 hour of nitrogen bubbling, suspension polymerization was carried out by holding at 70°C for 2 hours while stirring at 600 rpm. After the suspension polymerization was complete, the contents were introduced into 2,500 g of distilled water stirred with a magnetic stirrer and filtered to recover the resulting N-alkylmaleimide polymer particles. The recovered polymer particles were washed six times with 2,000 g of distilled water, and then five times with 1,582 g of methanol. The washed polymer particles were placed in a drying oven set to 90°C and dried under vacuum. Drying was stopped when there was no further weight loss due to drying, yielding 96.1 g of N-ethylmaleimide / styrene / methyl methacrylate copolymer. The starting composition for polymerization, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content, Mw and Mw / Mn in the copolymer, and the dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0108] Example 19 The N-ethylmaleimide / styrene / methyl methacrylate copolymer was produced in the same manner as in Example 18, except that the amount of N-ethylmaleimide added was changed to 96.4 g, the amount of styrene added to 24.1 g, the amount of methyl methacrylate to 28.3 g, the amount of PVP K30 0.860 g was changed to polyethylene glycol 0.029 g, the polymerization time was changed to 7 hours, and 0.148 g of 1-dodecanethiol was added as a chain transfer agent. As a result, 108.4 g of N-alkylmaleimide polymer was obtained. The polymer composition, yield, average particle size of N-alkylmaleimide polymer particles, N-ethylmaleimide unit content in the N-alkylmaleimide polymer, Mw and Mw / Mn, and the dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform and the haze of the film are shown in Table 3.

[0109] Comparative Example 4 The N-ethylmaleimide / styrene / methyl methacrylate copolymer was prepared in the same manner as in Example 18, except that hydroxypropyl methylcellulose (HPMC), a nonionic compound with hydrogen atoms bonded to oxygen, was used as a dispersant instead of PVP K30. As a result, 85.3 g of the N-alkylmaleimide polymer was obtained. The polymerization composition, yield, average particle size of the N-alkylmaleimide polymer particles, N-ethylmaleimide unit content in the N-alkylmaleimide polymer, Mw, and Mw / Mn are shown in Tables 1 and 2. The solubility in chloroform is shown in Table 3.

[0110] By using HPMC, a nonionic compound with hydrogen atoms bonded to oxygen, as a dispersant, a gel insoluble in chloroform was generated.

[0111] Comparative Example 5 3.15 g of N-ethylmaleimide, 0.85 g of styrene, and 1.00 g of methyl methacrylate were placed in a test tube and mixed. After sealing the test tube, the contents were mixed by shaking thoroughly. The test tube was left to stand in a 70°C water bath for 24 hours to allow bulk polymerization to occur. The resulting N-alkylmaleimide polymer was a cylindrical mass adhered to the inside of the test tube. To remove unreacted monomers, the cylindrical mass was removed from the test tube, crushed into approximately 1 cm cubes, and placed in methylene chloride to prepare a clear N-alkylmaleimide polymer solution. Then, the obtained N-alkylmaleimide polymer solution was added dropwise to methanol to precipitate the N-alkylmaleimide polymer. After filtration through filter paper to remove the filtrate containing dissolved unreacted monomers, the N-alkylmaleimide polymer remaining on the filter paper was collected and dried under reduced pressure in a desiccator for 3 hours. The polymer was then further dried under reduced pressure in a vacuum dryer at 105°C for 24 hours to obtain 3.9 g of N-alkylmaleimide polymer.

[0112] The particle morphology of the N-alkylmaleimide polymer particles was observed to be amorphous. The polymerization starter composition, yield, N-ethylmaleimide unit content, Mw and Mw / Mn in the N-alkylmaleimide polymer, and dispersant content of the resin composition are shown in Tables 1 and 2. The solubility in chloroform, heat resistance, mechanical strength, and optical properties of the resulting film are shown in Table 3.

[0113] By producing an N-alkylmaleimide polymer by bulk polymerization, a polymer with transparency equivalent to that of the polymer obtained in Example 18 was obtained. However, unlike the method used in Example 18, the production method of Comparative Example 5 required additional steps to remove unreacted monomers: removing the produced N-alkylmaleimide polymer from the test tube, pulverizing it and dissolving it in a solvent, and precipitating the N-alkylmaleimide polymer from the resulting solution.

[0114] Comparative Example 6 To 100 parts by weight of the N-alkylmaleimide polymer synthesized in Comparative Example 2, 3.36 parts by weight of PVP K30 was added to obtain a resin composition. A film was obtained using the obtained resin composition in <Film Forming (2)>.

[0115] Table 2 shows the dispersant content of the resin composition. Table 3 shows the solubility in chloroform and the haze of the resulting film.

[0116] Increasing the dispersant content in the resin composition resulted in a decrease in the haze of the resulting film.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3]

Claims

1. A method for producing an N-alkylmaleimide polymer, characterized by suspend polymerization of a monomer mixture consisting of 35 to 100% by weight of an N-alkylmaleimide represented by the following general formula (1) and 0 to 65% by weight of other copolymerizable monomers in an aqueous medium using an oil-soluble radical polymerization initiator in the presence of at least one dispersant selected from the group consisting of poly(N-vinylamide), polyacrylates, and polyalkylene glycols. 【Chemistry 1】 (Here, R represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.)

2. A method for producing an N-alkylmaleimide polymer according to claim 1, characterized in that R is a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, hexyl group, cyclohexyl group, or octyl group.

3. The method for producing an N-alkylmaleimide polymer according to claim 1 or 2, characterized in that the other copolymerizable monomers are vinyl aromatic hydrocarbons, olefins, alkyl acrylates, alkyl methacrylates, or vinyl carboxylates.

4. The method for producing an N-alkylmaleimide polymer according to claim 1 or 2, characterized in that the dispersant is at least one selected from the group consisting of polyvinylpyrrolidone, sodium polyacrylate, and polyethylene glycol.

5. A method for producing an N-alkylmaleimide polymer according to claim 1 or 2, characterized in that the weight-average molecular weight of the N-alkylmaleimide polymer is 200,000 to 2,000,000.

6. After filtering the N-alkylmaleimide polymer obtained by suspension polymerization, Washing the N-alkylmaleimide polymer with a solvent that dissolves the dispersant without dissolving the N-alkylmaleimide polymer, and A method for producing an N-alkylmaleimide polymer according to claim 1 or 2, further comprising washing the N-alkylmaleimide polymer with a solvent that dissolves unreacted monomers without dissolving the N-alkylmaleimide polymer.

7. A resin composition comprising 100 parts by weight of an N-alkylmaleimide polymer consisting of 35 to 100% by weight of an N-alkylmaleimide residue represented by the following general formula (1A) and 0 to 65% by weight of other copolymerizable monomer residues, and 2 parts by weight or less of at least one dispersant selected from the group consisting of poly(N-vinylamide), polyacrylate, and polyalkylene glycol. 【Chemistry 2】 (Here, R represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.)

Images