Method for producing isopropenyl phenol copolymer

Abstract

To provide a method for producing an isopropenyl phenol copolymer capable of reducing a residual monomer amount.SOLUTION: A method for producing an isopropenyl phenol copolymer includes a process of dropping a monomer mixture solution, and a polymerization initiator solution into a reaction vessel at the same time, wherein a relation of a drop time (t1) of the monomer mixture solution and a drop time (t2) of the polymerization initiator solution is 0.2≤t1 / (t1+t2)<0.5, and a monomer mixture includes 5 to 40 pts.mass of a monomer (a), 1 to 30 pts.mass of a monomer (b), and 30 to 94 pts.mass of the other monomer when a total amount of monomers including the monomer (a) represented by the following formula (1), the maleimide-based monomer (b), and the other monomer is 100 pts.mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing an isopropenyl phenol copolymer. [Background technology]

[0002] In recent years, photoresist materials have been widely used and have become indispensable microfabrication materials in the manufacturing or processing of electronic products such as televisions and smartphones. Such resist materials are patterned by irradiating them with active energy rays using a mask to reveal a difference in solubility in alkaline solution between exposed and unexposed areas, and the exposed areas are dissolved in alkaline solution, followed by heating to remove the solvent and harden the material, thereby forming a pattern of a desired shape.

[0003] Isopropenylphenol, which has a phenolic hydroxyl group, can be copolymerized with a (meth)acrylic monomer to introduce a hydroxyl group into the polymer, and the resulting acrylic polymer exhibits excellent properties as a positive resist resin, and is therefore widely used in semiconductor applications, display applications, etc. In the production of such resins, in order to accommodate the increasing demand for high-resolution displays, it is necessary to reduce as much as possible the amount of residual monomer that adversely affects pattern formation.

[0004] Patent Document 1 discloses a polymer made of a monomer having a phenolic hydroxyl group and a maleimide that is highly copolymerizable with the monomer as an alkali-soluble resin for forming a resist. Patent Document 2 discloses, as a radiation-sensitive composition, a polymer containing a structural unit having an acidic group and a structural unit having at least one structure selected from the group consisting of an oxetane structure and an oxirane structure. Patent Document 3 discloses a polymer having an acid group protected by an acid-decomposable group as a component of a photosensitive positive curable composition for a thin film transistor substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-34641 [Patent Document 2] Japanese Patent Publication No. 2022-171270 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-154230 Summary of the Invention [Problem to be solved by the invention]

[0006] Because isopropenylphenol has low copolymerizability, there is a problem that the amount of residual monomer increases when it is polymerized with a monomer with low polymerizability. However, conventional polymerization methods have low reactivity, making it difficult to reduce the amount of residual monomer. Furthermore, as described in Patent Documents 1, 2, and 3, a method for reducing the amount of residual monomer is known in which isopropenylphenol is used in combination with a large amount of a maleimide structural unit with high copolymerizability. However, the reduction effect is limited, and furthermore, there are problems such as limitations on the polymer configuration. Therefore, a new polymerization method for reducing the amount of residual monomer is desired in order to achieve higher resolution displays.

[0007] In view of the above circumstances, an object of the present invention is to provide a method for producing an isopropenyl phenol copolymer that can reduce the amount of residual monomers. [Means for solving the problem]

[0008] That is, the present invention comprises the following configurations. [1] A method for producing an isopropenyl phenol copolymer, comprising a step of simultaneously dropping a monomer mixture solution and a polymerization initiator solution into a reaction vessel, the relationship between the dropping time (t1) of the monomer mixture solution and the dropping time (t2) of the polymerization initiator solution is 0.2≦t1 / (t1+t2)<0.5, A method for producing an isopropenyl phenol copolymer, characterized in that the monomer mixture contains 5 to 40 parts by mass of monomer (a), 1 to 30 parts by mass of monomer (b), and 30 to 94 parts by mass of other monomers, when the total amount of monomers including monomer (a) represented by formula (1) below, monomer (b) represented by formula (2) below, and other monomers is taken as 100 parts by mass. [ka] [ka] R 1 represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. [2] The production method according to the above item [1], wherein the monomer mixture (w1) is 20 to 90 parts by mass when the total amount of the monomer mixture solution is taken as 100 parts by mass, the polymerization initiator (w2) is 1 to 30 parts by mass when the total amount of the polymerization initiator solution is taken as 100 parts by mass, and the mass ratio of the monomer mixture solution (W1) to the polymerization initiator solution (W2) satisfies the relationship 1≦W1 / W2≦15. [3] The method according to the above [1] or [2], wherein the other monomer contains a monomer (c) represented by the following formula (3): [ka] X 1 represents an oxygen atom or a nitrogen atom, and R 2 represents a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 22 carbon atoms, and n represents X 1 If is an oxygen atom, it indicates 1, and X 1 When is a nitrogen atom, it indicates 2. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for producing an isopropenyl phenol copolymer that can reduce the amount of residual monomers. DETAILED DESCRIPTION OF THE INVENTION

[0010] The method for producing an isopropenyl phenol copolymer of the present invention comprises simultaneously dropping a monomer mixture solution and a polymerization initiator solution into a reaction vessel, wherein the relationship between the dropping time (t1) of the monomer mixture solution and the dropping time (t2) of the polymerization initiator solution is 0.2≦t1 / (t1+t2)<0.5, and the monomer mixture is characterized in that, when the total amount of monomers including monomer (a) represented by formula (1), monomer (b) represented by formula (2), and other monomers is taken as 100 parts by mass, monomer (a) is 5 to 40 parts by mass, monomer (b) is 1 to 30 parts by mass, and other monomers are 30 to 94 parts by mass. The present invention provides a method for producing an isopropenyl phenol copolymer that can reduce the amount of residual monomers.

[0011] [Monomer mixture solution] In the production method of the present invention, a monomer mixture solution is used. The monomer mixture solution contains a monomer mixture and a solvent. The monomer mixture is a mixture of a monomer (a) represented by formula (1), a monomer (b) represented by formula (2), and other monomers. The other monomers are monomers other than the monomers (a) and (b) that are copolymerizable with the monomers (a) and (b).

[0012] <Monomer (a)> The monomer (a) is a monomer represented by the following formula (1) and is a structural unit having a phenolic hydroxyl group. The copolymer contains a structural unit derived from the monomer (a), which can impart good alkali solubility to the copolymer component. In this specification, "alkali soluble" means that the copolymer is soluble in an alkaline aqueous solution such as a 2.38% by mass aqueous solution of tetramethylammonium hydroxide. [ka]

[0013] Specific examples of the monomer (a) include 4-isopropenylphenol, 3-isopropenylphenol, and 2-isopropenylphenol, with 4-isopropenylphenol being preferred.

[0014] The content of the monomer (a) in the monomer mixture is 5.0 to 40.0 parts by mass, where the total amount of the monomers including the monomers (a), (b) and other monomers is 100 parts by mass. From the viewpoint of reducing the amount of residual monomer in the copolymer, the content is preferably 10.0 to 25.0 parts by mass, and more preferably 15.0 to 20.0 parts by mass.

[0015] <Monomer (b)> The monomer (b) is a monomer represented by the following formula (2), and is an N-substituted maleimide compound. When the copolymer contains a structural unit derived from the monomer (b), it is possible to reduce the amount of residual monomer in the copolymer. [ka] R 1 represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms.

[0016] R of the monomer (b) 1 represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. The hydrocarbon group may be linear, branched, or cyclic. Specific examples of the hydrocarbon group having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, tert-butyl, n-pentyl, n-hexyl, thexyl (2,3-dimethyl-2-butyl), n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, cyclohexyl, phenyl, dicyclopentanyl, and adamantyl.

[0017] R 1Specific examples of the N-substituted maleimide compound in which is a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, Nt-butylmaleimide, Nn-hexylmaleimide, N-2-ethylhexylmaleimide, N-dodecylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, and N-(2-hydroxyethyl)maleimide.

[0018] R 1 In the case of R , the cyclic structure may be directly bonded to the nitrogen atom, or the cyclic structure may be bonded via a divalent linking group. Examples of the divalent linking group include a methylene group, an ethylene group, and an alkanediyl group such as a 1,3-propanediyl group. Among these, from the viewpoint of reducing the amount of residual monomers, R 1 is preferably a cyclic hydrocarbon group in which the ring structure of the cyclic hydrocarbon group is directly bonded to the nitrogen atom, and more preferably an alicyclic hydrocarbon group in which the alicyclic hydrocarbon structure is directly bonded to the nitrogen atom.

[0019] R 1 Specific examples of the N-substituted maleimide compound having a cyclic structure containing 1 to 12 carbon atoms include N-cyclohexylmaleimide, N-cyclopentylmaleimide, N-(2-methylcyclohexyl)maleimide, N-(4-methylcyclohexyl)maleimide, N-(4-ethylcyclohexyl)maleimide, N-(2,6-dimethylcyclohexyl)maleimide, N-norbornylmaleimide, N-tricyclodecylmaleimide, N-adamantylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(4-ethylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-benzylmaleimide, and N-naphthylmaleimide.

[0020] Of these, the N-substituted maleimide compound is preferably at least one selected from the group consisting of N-cyclohexylmaleimide, N-(4-methylcyclohexyl)maleimide, N-phenylmaleimide, and N-(4-methylphenyl)maleimide, and more preferably at least one of N-cyclohexylmaleimide and N-phenylmaleimide.

[0021] The content of the monomer (b) in the monomer mixture is 1.0 to 30.0 parts by mass, and from the viewpoint of reducing the amount of residual monomer in the polymer, preferably 3.0 to 20.0 parts by mass, and more preferably 5.0 to 15.0 parts by mass, when the total amount of monomers including the monomers (a), (b) and other monomers is 100 parts by mass.

[0022] In the monomer mixture, the mass ratio ((a) / (b)) of the monomer (a) to the monomer (b) is preferably 0.5 to 4.0, more preferably 1.0 to 3.0, and even more preferably 1.0 to 2.0, from the viewpoint of reducing the amount of residual monomers.

[0023] <Other monomers> In the monomer mixture, other monomers may be used in addition to the monomers (a) and (b). The other monomer is not particularly limited as long as it is a monomer that can be copolymerized with the monomers (a) and (b), and one or more types may be contained. Specific examples include (meth)acrylic acid ester monomers, aromatic vinyl compounds, etc., and (meth)acrylic acid ester monomers are particularly preferred from the viewpoint of reducing the amount of residual monomers in the copolymer.

[0024] In view of copolymerizability with the monomer (a) and the monomer (b), the monomer mixture preferably contains, in addition to the monomers (a) and (b), a monomer (c) represented by the following formula (3), which is an acrylic monomer, and a monomer (d) represented by the following formula (4), which is a methacrylic monomer.

[0025] [ka] In equation (3), X 1 represents an oxygen atom or a nitrogen atom, and R 2 represents a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 22 carbon atoms, and n represents X 1 If is an oxygen atom, it indicates 1, and X 1 When is a nitrogen atom, it indicates 2. [ka] In equation (4), X 2 represents an oxygen atom or a nitrogen atom, and R 3 represents a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 22 carbon atoms, and n represents X 2 If is an oxygen atom, it indicates 1, and X 2 When is a nitrogen atom, it indicates 2.

[0026] <Monomer (c)> The monomer (c) is an acrylic monomer represented by the following formula (3): There are no particular limitations on the monomer (c) as long as it is copolymerizable with the monomer (a) and the monomer (b), and one type of the monomer (c) may be used alone, or two or more types may be used in combination. [ka]

[0027] In the monomer (c), X 1 represents an oxygen atom or a nitrogen atom, and R 2 represents a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 22 carbon atoms, and n represents X 1 If is an oxygen atom, it indicates 1, and X 1 When X is a nitrogen atom, it represents 2. From the viewpoint of copolymerizability with the monomer (a) and the monomer (b), 1 is preferably an oxygen atom.

[0028] In the monomer (c), R 2Examples of compounds in which is a hydrogen atom include acrylic acid and acrylamide.

[0029] R 2 Examples of the hydrocarbon group having no substituent include linear, branched, and cyclic alkyl groups having 1 to 22 carbon atoms.

[0030] In the monomer (c), R 2 Specific examples of the compound having a linear or branched alkyl group having 1 to 22 carbon atoms include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate, lauryl acrylate, hexadecyl acrylate, stearyl acrylate, isostearyl acrylate, docosyl acrylate, dimethylacrylamide, and diethylacrylamide. From the viewpoint of copolymerizability with the monomers (a) and (b), methyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, and stearyl acrylate are preferred.

[0031] R 2 In the monomer (c), the unsubstituted cyclic hydrocarbon group may be, for example, a monocyclic or polycyclic alkyl group having 3 to 22 carbon atoms. 2 Specific examples of the compound in which is a cyclic hydrocarbon group having no substituent include cyclohexyl acrylate, isobornyl acrylate, dicyclopentanyl acrylate, and 1-adamantyl acrylate. From the viewpoint of copolymerizability with the monomer (a) and the monomer (b), cyclohexyl acrylate and isobornyl acrylate are preferred.

[0032] R 2When the hydrocarbon group in has a substituent, the substituent may be at least one selected from the group consisting of a hydroxyl group, an ether group, an epoxy group, a carbonyl group, an ester group, an amide group, an imide group, an isocyanate group, a urethane group, a urea group, a vinyl group, an amino group, an onium salt group, a heterocyclic group, an aryl group, and an organosiloxane group. 2 is preferably a hydrocarbon group having an aryl group, a hydroxyl group, or an ether group.

[0033] In the monomer (c), R 2 Specific examples of compounds in which the hydrocarbon group has a substituent include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, glycerol monoacrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, methoxyethyl acrylate, methoxypolyethylene glycol acrylate, methoxypolypropylene glycol acrylate, glycidyl acrylate, (2-oxo-1,3-dioxolan-4-yl)methyl acrylate, 2-isocyanatoethyl acrylate, dimethylaminoethyl acrylate, trimethylammonium ethyl acrylate chloride, tetrahydrofurfuryl acrylate, benzyl acrylate, 4-hydroxyphenyl acrylate, diacetone acrylamide, N-methylolacrylamide, 4-acryloylmorpholine, etc. From the viewpoint of copolymerizability with the monomer (a) and the monomer (b), 2-hydroxyethyl acrylate, methoxypolyethylene glycol acrylate, polyethylene glycol acrylate, benzyl acrylate, diacetone acrylamide, and N-methylolacrylamide are preferred.

[0034] <Monomer (d)> The monomer (d) is a methacrylic monomer represented by the following formula (4): There are no particular limitations on the monomer (d) as long as it is copolymerizable with the monomer (a) and the monomer (b), and one type of the monomer (d) may be used alone, or two or more types may be used in combination. [ka]

[0035] In the monomer (d), X 2 represents an oxygen atom or a nitrogen atom, and R 3 represents a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 22 carbon atoms, and n represents X 2 If is an oxygen atom, it indicates 1, and X 2 When X is a nitrogen atom, it represents 2. From the viewpoint of copolymerizability with the monomer (a) and the monomer (b), 2 is preferably an oxygen atom.

[0036] In the monomer (d), R 3 Examples of compounds in which is a hydrogen atom include methacrylic acid and methacrylamide.

[0037] R 3 Examples of the hydrocarbon group having no substituent include linear, branched, and cyclic alkyl groups having 1 to 22 carbon atoms.

[0038] In the monomer (d), R 3Specific examples of the compound having a linear or branched alkyl group having 1 to 22 carbon atoms include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hexadecyl methacrylate, stearyl methacrylate, isostearyl methacrylate, docosyl methacrylate, dimethylmethacrylamide, and diethylmethacrylamide. From the viewpoint of copolymerizability with the monomer (a) and the monomer (b), methyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, and stearyl methacrylate are preferred.

[0039] R 3 In the monomer (d), the unsubstituted cyclic hydrocarbon group may be, for example, a monocyclic or polycyclic alkyl group having 3 to 22 carbon atoms. 3 Specific examples of the compound in which is a cyclic hydrocarbon group having no substituent include cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentanyl methacrylate, and 1-adamantyl methacrylate. From the viewpoint of copolymerizability with the monomer (a) and the monomer (b), cyclohexyl methacrylate and isobornyl methacrylate are preferred.

[0040] R 3 When the hydrocarbon group in has a substituent, the substituent may be at least one selected from the group consisting of a hydroxyl group, an ether group, an epoxy group, a carbonyl group, an ester group, an amide group, an imide group, an isocyanate group, a urethane group, a urea group, a vinyl group, an amino group, an onium salt group, a heterocyclic group, an aryl group, an organosiloxane group, and a polydimethylsiloxane group. 3 is preferably a hydrocarbon group having an aryl group, a polydimethylsiloxane group, a hydroxyl group, or an ether group. The molecular weight of the hydrocarbon group-containing monomer having a polydimethylsiloxane group is preferably 1,000 to 30,000.

[0041] Specific examples of the monomer (d) include methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, dodecyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-methyl methacrylate, Methacrylate-3-methoxybutyl, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, dicyclopentanyl methacrylate, glycerol methacrylate, hydroxyphenyl methacrylate, stearyl methacrylate, glycidyl methacrylate, ethylene oxide adduct of methacrylic acid, (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate, 2-isopropyl methacrylate Examples of suitable methacrylates include isocyanatoethyl, dimethylaminoethyl methacrylate, trimethylammonium ethyl methacrylate chloride, tetrahydrofurfuryl methacrylate, 4-hydroxyphenyl methacrylate, diacetone methacrylamide, N-methylol methacrylamide, 4-methacryloylmorpholine, "Placcel FM Series" (manufactured by Daicel Corporation, ε-caprolactone adduct of 2-hydroxyethyl methacrylate, trade name), 3-(trimethoxysilyl)propyl methacrylate, "Silaplane FM-0721 (manufactured by JNC Corporation, polydimethylsiloxane group-containing macromonomer (molecular weight 5,000), trade name)," "Silaplane FM-0725 (manufactured by JNC Corporation, polydimethylsiloxane group-containing macromonomer (molecular weight 10,000)), and "Silaplane FM-7721 (manufactured by JNC Corporation, polydimethylsiloxane group-containing bifunctional macromonomer (molecular weight 5,000)), trade name)."From the viewpoint of copolymerizability with the monomer (a) and the monomer (b), methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, 2-hydroxyethyl methacrylate, dicyclopentanyl methacrylate, glycerol methacrylate, hydroxyphenyl methacrylate, and glycidyl methacrylate are preferred.

[0042] Examples of aromatic vinyl compounds that can be used as other monomers in addition to the monomers (a) and (b) include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, t-butylstyrene, chlorostyrene, hydroxystyrene, t-butoxystyrene, vinyltoluene, and vinylnaphthalene.

[0043] The content of the other monomer in the monomer mixture is 30.0 to 94.0 parts by mass, when the total amount of the monomers including the monomers (a), (b) and the other monomers is 100 parts by mass. From the viewpoint of reducing the amount of residual monomer in the polymer, the content is preferably 40.0 to 90.0 parts by mass, and more preferably 60.0 to 80.0 parts by mass.

[0044] As the solvent contained in the monomer mixture solution, one in which the monomers are soluble can be used, and specific examples include acetone, methyl ethyl ketone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl 2-hydroxypropionate, etc. These solvents may be used alone or in combination of two or more.

[0045] [Polymerization initiator solution] In the production method of the present invention, a polymerization initiator solution is used. The polymerization initiator solution contains a polymerization initiator and a solvent.

[0046] <Polymerization initiator> Known polymerization initiators can be used. Examples include organic peroxides such as 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and azo polymerization initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(isobutyrate) dimethyl. These polymerization initiators may be used alone or in combination of two or more.

[0047] <Solvent> As the solvent contained in the polymerization initiator solution, one in which the polymerization initiator dissolves can be used, and specific examples include acetone, methyl ethyl ketone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl 2-hydroxypropionate, etc. These polymerization solvents may be used alone or in combination of two or more.

[0048] <Polymerization method> Next, the polymerization method for the copolymer of the present invention will be described. The copolymer of the present invention can be obtained by simultaneously dropping a monomer mixture solution and a polymerization initiator solution into a reaction vessel to radically polymerize the monomer mixture. The polymerization can be carried out by a known method. For example, solution polymerization, suspension polymerization, emulsion polymerization, etc. are mentioned, but solution polymerization is preferred from the viewpoints that the amount of residual monomer in the polymer is easily reduced and the weight average molecular weight is easily adjusted within the range described below. Here, "concurrently dropping into the reaction vessel" means that the dropping of the monomer mixture solution and the dropping of the polymerization initiator solution overlaps at least partially. In other words, "concurrently dropping into the reaction vessel" means that the dropping period from the start to the end of dropping of the monomer mixture solution and the dropping period from the start to the end of dropping of the polymerization initiator solution overlap at least partially.

[0049] The amount of the polymerization initiator used can be appropriately determined depending on the combination of monomers used, reaction conditions, and the like. The polymerization initiator solution is added dropwise to the reaction vessel simultaneously with the monomer mixture solution. The relationship between the drop time (t1) of the monomer mixture solution and the drop time (t2) of the polymerization initiator solution is 0.2≦t1 / (t1+t2)<0.5. From the viewpoint of workability and reducing the amount of residual monomer in the polymer, the relationship is preferably 0.2≦t1 / (t1+t2)≦0.4, and more preferably 0.25≦t1 / (t1+t2)≦0.3. In this specification, the drop time refers to the time from the start of dropwise addition to the completion of dropwise addition. Furthermore, dropwise addition refers to continuous addition to the reaction vessel at a substantially constant rate; adding the solution all at once to the reaction vessel is not considered dropwise addition.

[0050] The dropping time (t1) of the monomer mixture solution may be appropriately set so that the above "t1 / (t1+t2)" falls within a predetermined range, and is, for example, 1 to 6 hours, and preferably 1 to 3 hours. The dropping time (t2) of the polymerization initiator solution may be appropriately set so that the above "t1 / (t1+t2)" falls within a predetermined range, and is, for example, 1 to 6 hours, and preferably 3 to 5 hours.

[0051] The temperature inside the reaction vessel when the monomer mixture solution and the polymerization initiator solution are dropped depends on the type of polymerization solvent, etc., and is, for example, 50° C. to 110° C. The polymerization time depends on the type of polymerization initiator and the polymerization temperature; for example, when di(4-t-butylcyclohexyl)peroxydicarbonate is used as the polymerization initiator, and polymerization is carried out at a polymerization temperature of 70° C., a polymerization time of about 6 hours is suitable.

[0052] When the total amount of the monomer mixture solution is 100 parts by mass, the concentration (w1) of the monomer mixture is preferably 20 to 90 parts by mass, and from the viewpoints of easy reaction control and reducing the amount of residual monomer in the polymer, it is more preferably 30 to 80 parts by mass, and even more preferably 40 to 70 parts by mass.

[0053] When the total amount of the polymerization initiator solution is taken as 100 parts by mass, the concentration (w2) of the polymerization initiator is preferably 1 to 30 parts by mass, and from the viewpoints of facilitating reaction control and reducing the amount of residual monomer in the polymer, it is more preferably 3 to 25 parts by mass, and even more preferably 5 to 20 parts by mass.

[0054] The mass ratio of the monomer mixture solution (W1) to the polymerization initiator solution (W2) preferably satisfies the relationship 1≦W1 / W2≦15, and from the viewpoint of adjusting the weight-average molecular weight within the range described below and reducing the amount of residual monomer in the polymer, it is more preferably 2≦W1 / W2≦12, and even more preferably 3≦W1 / W2≦10.

[0055] The isopropenyl phenol copolymer produced by the production method of the present invention is a copolymer of the above-mentioned monomer mixture, and contains a constituent unit derived from the monomer (a) represented by formula (1), a constituent unit derived from the monomer (b) represented by formula (2), and a constituent unit derived from other monomers. The weight-average molecular weight of the isopropenyl phenol copolymer produced by the production method of the present invention can be determined in polystyrene equivalent terms using gel permeation chromatography (GPC). The weight-average molecular weight of the isopropenyl phenol copolymer is 1,000 to 100,000, preferably 3,000 to 50,000, and more preferably 5,000 to 30,000. The weight average molecular weight is measured under the following conditions.

[0056] (Measurement of weight average molecular weight) Using gel permeation chromatography (GPC), the weight The average molecular weight (Mw) was determined. Equipment: Tosoh Corporation, HLC-8220 Column: Shodex LF-804 Standard material: polystyrene Eluent: THF (tetrahydrofuran) Flow rate: 1.0ml / min Column temperature: 40℃ Detector: RI (differential refractive index detector) [Example]

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0058] (Comparative Example 1) A 500 mL separable flask equipped with a stirrer, a thermometer, a condenser, a dropping funnel and a nitrogen inlet tube was charged with 66.1 g of propylene glycol monomethyl ether, and the atmosphere inside the flask was replaced with nitrogen to create a nitrogen atmosphere. A monomer mixture solution (w1 = 58.1) was prepared by mixing 63.2 g of propylene glycol monomethyl ether, 13.1 g of monomer (a1): 4-isopropenylphenol, 8.8 g of monomer (b1): N-phenylmaleimide, 26.3 g of monomer (c1): 2-ethylhexyl acrylate, 17.5 g of monomer (d1): methacrylic acid, and 21.9 g of monomer (d2): methyl methacrylate. A polymerization initiator solution (w2 = 9.0) was also prepared by mixing 26.3 g of propylene glycol monomethyl ether and 2.6 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (product name: V-65 (Wako Pure Chemical Industries, Ltd.)) (W1 / W2 = 5.2).

[0059] The temperature inside the reaction vessel was raised to 75°C, and the monomer mixture solution and the polymerization initiator solution were simultaneously added dropwise over 2 hours and 2 hours, respectively (t1 / (t1+t2)=0.5). After the addition of the polymerization initiator solution was completed, the mixture was allowed to react at 75°C for 1 hour, and then a polymerization initiator solution containing 2.2 g of propylene glycol monomethyl ether and 0.5 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was added all at once and allowed to react for 2 hours. After the reaction was completed, a propylene glycol monomethyl ether solution containing the isopropenyl phenol copolymer of Comparative Example 1 was obtained. Using this polymer solution, the amount of residual monomer was measured as described below.

[0060] (Comparative Examples 2 and 3) Comparative Examples 2 and 3 were carried out in the same manner as in Production Example 1, except that the types of the respective monomer raw materials and the amounts (parts by mass) thereof were changed as shown in Table 1.

[0061] (Examples 1 and 2) A propylene glycol monomethyl ether solution (polymer solution) containing an isopropenyl phenol copolymer was obtained in the same manner as in Comparative Example 1, except that the polymerization method (t1 / (t1+t2)) was changed as shown in Table 1. Using the polymer solution, the amount of residual monomer, which will be described later, was measured.

[0062] Examples 3 and 4 A propylene glycol monomethyl ether solution (polymer solution) containing an isopropenyl phenol copolymer was obtained in the same manner as in Comparative Example 2, except that the polymerization method (t1 / (t1+t2)) was changed as shown in Table 1. Using this polymer solution, the amount of residual monomer, which will be described later, was measured.

[0063] (Examples 5 to 6) A propylene glycol monomethyl ether solution (polymer solution) containing an isopropenyl phenol copolymer was obtained in the same manner as in Comparative Example 3, except that the polymerization method (t1 / (t1+t2)) was changed as shown in Table 1. Using the polymer solution, the amount of residual monomer, which will be described later, was measured.

[0064] The polymer solutions of the examples and comparative examples obtained above were evaluated by the following evaluation methods, and the results are shown in Table 1.

[0065] <Measurement of residual monomer amount> 0.3 g of the polymer solution was placed in a 10 mL volumetric flask, and 1 mL of a solution prepared by diluting 0.10 g of n-undecane (internal standard) with 25 mL of methyl ethyl ketone (MEK) was added. MEK was then added up to the measuring line. The solution was then filtered through a 0.22 μm membrane filter and measured. A calibration curve was obtained by diluting each monomer and the internal standard n-undecane with MEK at three points. <Condition> GC: SHIMADZU GC-2010 Column: Zebron ZB-1, manufactured by Shimadzu GLC, length 30 m, inner diameter 0.53 mm, film thickness 5.0 μm Column temperature: 50°C for 1 minute, then increase the temperature to 250°C at 10°C per minute INJ temperature: 210℃ DET temperature: 250℃

[0066] The amount of residual monomer was evaluated according to the following criteria: In the production method of the present invention, a residual monomer amount of ◯ or more was considered to be acceptable. (evaluation) ◎: The total amount of residual monomer in the polymer solution is less than 5.0 wt% ○: The total residual monomer content in the polymer solution is 5.0 wt% or more and less than 15.0 wt% △: The total residual monomer amount in the polymer solution is 15.0 wt% or more but less than 20.0 wt% ×: The total amount of residual monomers in the polymer solution is 20.0 wt% or more

[0067] The difference (B-A) between the residual monomer amount A in each example and the residual monomer amount B in a comparative example in which an experiment was conducted using a monomer mixture of the same composition as the example under the condition of t1 / (t1+t2)=0.5 was defined as the residual monomer reduction amount. The residual monomer reduction amount was evaluated according to the following criteria: In the production method of the present invention, a residual monomer reduction amount of ◯ or more was rated as pass. (evaluation) ◎: 7.0 wt% or more ○: 3.0 wt% or more and less than 7.0 wt% △: Less than 3.0 wt%

[0068] [Table 1]

[0069] The monomers in Table 1 are as follows: a1 is 4-isopropenylphenol (Mitsui Chemicals, Inc., trade name "Mirex PM") b1 is N-phenylmaleimide (manufactured by Nippon Shokubai Co., Ltd., trade name "Imilex P") b2 is N-cyclohexylmaleimide (manufactured by Nippon Shokubai Co., Ltd., trade name "Imilex C") c1 is 2-ethylhexyl acrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) d1 is methacrylic acid (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "MAA") d2 is methyl methacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0070] For the polymers of Examples 1 to 6, the evaluation results for the amount of residual monomers satisfied the target value. In Comparative Examples 1, 2, and 3, the relationship between the dropwise addition time (t1) of the monomer mixture solution and the dropwise addition time (t2) of the polymerization initiator solution, t1 / (t1+t2), was too long, and as a result, the amount of residual monomer was larger than in the Examples using the monomer mixture of the same composition.

Claims

1. 1. A method for producing an isopropenyl phenol copolymer, comprising a step of simultaneously dropping a monomer mixture solution and a polymerization initiator solution into a reaction vessel, the relationship between the dropping time (t1) of the monomer mixture solution and the dropping time (t2) of the polymerization initiator solution is 0.2≦t1 / (t1+t2)<0.5, A method for producing an isopropenyl phenol copolymer, characterized in that the monomer mixture contains 5 to 40 parts by mass of monomer (a), 1 to 30 parts by mass of monomer (b), and 30 to 94 parts by mass of other monomers, when the total amount of monomers including monomer (a) represented by formula (1) below, monomer (b) represented by formula (2) below, and other monomers is taken as 100 parts by mass. 【Chemical 1】 【Chemistry 2】 R １ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms.

2. The production method according to claim 1, wherein the monomer mixture (w1) is contained in an amount of 20 to 90 parts by mass when the total amount of the monomer mixture solution is taken as 100 parts by mass, the polymerization initiator (w2) is contained in an amount of 1 to 30 parts by mass when the total amount of the polymerization initiator solution is taken as 100 parts by mass, and the mass ratio of the monomer mixture solution (W1) to the polymerization initiator solution (W2) satisfies the relationship 1≦W1 / W2≦15.

3. The method according to claim 1, wherein the other monomer contains a monomer (c) represented by the following formula (3): 【Chemistry 3】 X １ represents an oxygen atom or a nitrogen atom, and R ２ represents a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 22 carbon atoms; n represents X １ is an oxygen atom, it represents 1, and X １ When is a nitrogen atom, it represents 2.

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