Chain transfer agent, method for producing copolymer, copolymer, and composition

Abstract

The present invention provides a chain transfer agent useful for producing copolymers with suppressed polydispersity, as well as a method for producing copolymers with suppressed polydispersity, a copolymer, and a composition. [Solution] The method is a chain transfer agent represented by the following formula (1) or formula (2), a method for producing a copolymer using the chain transfer agent, a copolymer, and a composition. In formulas (1) and (2), R 1 and R 2 Each is independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and R 3 and R 4 Each of these independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms. JPEG2026101549000017.jpg5892

Description

[Technical Field]

[0001] This disclosure relates to chain transfer agents, methods for producing copolymers, copolymers, and compositions. [Background technology]

[0002] When obtaining polymers using monomer compounds, α-methylstyrene dimer derivatives are widely used as chain transfer agents. It is known that hydroxystyrene dimers having a predetermined characteristic structure can be used as chain transfer agents that act on radicals (Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-222285 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The problems that the embodiments of this disclosure aim to solve are to provide a chain transfer agent useful for producing copolymers with suppressed polydispersity, and to provide a method for producing copolymers, copolymers, and compositions that produce copolymers with suppressed polydispersity. [Means for solving the problem]

[0005] The following embodiments are included as specific means for solving the above problems. <1> A chain transfer agent represented by the following formula (1) or formula (2).

[0006] [ka]

[0007] In equations (1) and (2) above, R4 , , , 4 , , , 2 , , 4 , , , , , , , , , , 3 , , , 5 ,

[0010] , , 3 , ,

[0008] , 1 ,

[0009] , ,

[0011] , , and R 2 is each independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and R 3 and R 4 each independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms. <2> R in formula (1) and formula (2) 3 and R 4 is R 3 is a hydrogen atom, and the chain transfer agent according to <1> does not include the case where R 4 is a hydrogen atom. <3> R in formula (1) and formula (2) 3 and R 4 is the hydroxyl group, and the chain transfer agent according to <1>. <4> A method for producing a copolymer, comprising a step of copolymerizing a compound in the presence of at least one of a chain transfer agent represented by the following formula (1) and a chain transfer agent represented by the following formula (2).

[0008]

Chemical formula

[0009] In the above formula (1) and the above formula (2), R 1 and R 2 are each independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and R 3 and R 4 each independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms. <5> The copolymerization step in the method for producing a copolymer according to <4> includes copolymerizing a compound represented by the following formula (3) and a compound represented by the following formula (4).

[0010]

Chemical formula

[0011] In the above formula (3), R 5 represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. In the above equation (4), R 6 and R 7 Each of these independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. <6> A copolymer is produced in which the proportion of constituent unit A, derived from the compound represented by formula (3), and constituent unit B, derived from the compound represented by formula (4), is 50 ml or less. <5> A method for producing the copolymer described above. <7> In equation (3), R 5 It is a methyl group. <5> or <6> A method for producing the copolymer described above. <8> In equation (4), R 6 is a hydrogen atom <5> ~ <7> A method for producing a copolymer as described in any one of the following. <9> To produce copolymers with a weight-average molecular weight of 25,000 or less. <4> ~ <8> A method for producing a copolymer as described in any one of the following. <10> To produce copolymers with a polydispersity of less than 2.0. <4> ~ <9> A method for producing a copolymer as described in any one of the following. <11> A copolymer containing a constituent unit A derived from a compound represented by the following formula (3), and a constituent unit B derived from a compound represented by the following formula (4).

[0012] [ka]

[0013] In the above equation (3), R 5 represents a hydrogen atom or a methyl group. In the above equation (4), R 6 R represents a hydrogen atom or a methyl group. 7 This represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. <12> The weight-average molecular weight is 25,000 or less. <11> The copolymer described above. <13> The polyvariance is less than 2.0. <11> or <12> The copolymer described above. <14> <11> ~ <13> A composition comprising the copolymer described in any one of the following. <15> It is a resist composition. <14> The composition described above. [Effects of the Invention]

[0014] According to one embodiment of the present disclosure, a chain transfer agent useful for producing copolymers with suppressed polydispersity is provided, as well as a method for producing copolymers with suppressed polydispersity, a copolymer, and a composition. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a graph showing the molecular weight distribution of each copolymer obtained in the examples and comparative examples. [Modes for carrying out the invention]

[0016] The following describes in detail an embodiment of the present disclosure, including a chain transfer agent, a method for producing a copolymer, the copolymer, and a composition. The following descriptions of requirements may be based on a typical embodiment of the present disclosure, but the present disclosure is not limited to such embodiments and can be modified as appropriate within the scope of the purpose of the present disclosure.

[0017] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers written before and after "~" as the lower limit and upper limit, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0018] In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0019] In this disclosure, the amount of each constituent unit contained in the copolymer means the total amount of the multiple constituent units present in the copolymer, unless otherwise specified, if there are multiple constituent units corresponding to each constituent unit in the copolymer.

[0020] In this disclosure, "(meth)acrylic" is a term that encompasses both "acrylic" and "methacrylic," and "(meth)acrylate" is a term that encompasses both "acrylate" and "methacrylate."

[0021] In this disclosure, "n-" means normal, "i-" means iso, "s-" means secondary, and "t-" means tertiary.

[0022] In this disclosure, "mass%" and "weight%" are synonymous, and "parts by mass" and "parts by weight" are synonymous. In this disclosure, "monomer" and "monomer" are synonymous, and "polymer," "polymer," and "copolymer" are synonymous.

[0023] In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved.

[0024] [Chain transfer agent] One embodiment of the present disclosure is a chain transfer agent, which is a styrene dimer derivative represented by the following formula (1) or formula (2).

[0025] [ka]

[0026] In equations (1) and (2) above, R 1 and R 2 Each is independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and R 3 and R 4Each of these independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms.

[0027] The styrene dimer derivative represented by formula (1) or formula (2) above functions as a chain transfer agent when a polymer is obtained using a monomer compound. Therefore, the compound represented by formula (1) or formula (2) above, acting as a chain transfer agent, can control the molecular weight (Mw) of the resulting polymer and is suitable for producing polymers with suppressed polydispersity. Specifically, it is possible to produce polymers with reduced high molecular weight molecules, uniform molecular weights, and suppressed polydispersity.

[0028] The present inventors investigated the possibility that during monomer copolymerization, some copolymers may become high molecular weight due to a recombination reaction in which radicals at the ends of the copolymer bond and dimerize. High molecular weight can increase the polydispersity of the copolymer and lead to greater differences in solubility between molecular chains. This can, for example, worsen the roughness of the photoresist (e.g., variation in the width and length of the resist pattern) when the copolymer is used as a resist composition. Therefore, the inventors focused on styrene dimer derivatives and found a styrene dimer derivative that functions favorably as a chain transfer agent. In this specification, the roughness of a photoresist refers to the roughness of lines, irregularities in lines, etc., that are observed after processes such as pattern formation and etching of the photoresist, based on the surface or internal irregularities, non-uniformity, etc., of the photoresist layer when a copolymer is used as a resist composition.

[0029] Although the mechanism by which the above effects are achieved is not clear, it is presumed that, according to one embodiment of the chain transfer agent in this disclosure, it appropriately captures radicals present at the ends of the copolymer and promotes the copolymer reaction.

[0030] In equations (1) and (2) above, R 1 and R 2 Each independently represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. In formulas (1) and (2), R 1 and R2 They may be the same or they may be different. 1 and R 2 It is preferable that they are the same.

[0031] A hydrocarbon group having 1 to 6 carbon atoms may be unsubstituted or substituted. If the hydrocarbon group has substituents, the carbon atoms of the substituents are not included in the carbon number of the hydrocarbon group (1 to 6 carbon atoms). Examples of substituents include hydroxyl groups, carboxyl groups, halogen atoms, cyano groups, isocyanate groups, alkoxysilyl groups, thiol groups, catechol groups, phenol groups, aryl groups, amino groups, and dialkylamino groups. Hydrocarbon groups having 1 to 6 carbon atoms are preferably unsubstituted.

[0032] In equations (1) and (2), R 1 or R 2 Examples of hydrocarbon groups having 1 to 6 carbon atoms, as represented by , include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include alkyl groups having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon atoms may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group. R 1 or R 2 Specific examples of hydrocarbon groups having 1 to 6 carbon atoms represented by include the methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, and phenyl group.

[0033] In equations (1) and (2), R 1 and R 2 These are preferably hydrogen atoms or methyl groups, and more preferably methyl groups.

[0034] In equations (1) and (2) above, R 3 and R 4Each of these independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms. In formulas (1) and (2), R 3 and R 4 They may be the same or they may be different. 3 and R 4 It is preferable that they are the same.

[0035] A hydrocarbon group having 1 to 10 carbon atoms may be unsubstituted or substituted. If the hydrocarbon group has substituents, the carbon atoms of the substituents are not included in the carbon number of the hydrocarbon group. Examples of substituents include hydroxyl groups, carboxyl groups, halogen atoms, cyano groups, isocyanate groups, alkoxysilyl groups, thiol groups, catechol groups, phenol groups, aryl groups, amino groups, and dialkylamino groups. Hydrocarbon groups having 1 to 10 carbon atoms are preferably unsubstituted.

[0036] In equations (1) and (2), R 3 or R 4 Examples of hydrocarbon groups having 1 to 10 carbon atoms, as represented by , include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include alkyl groups having 1 to 10 carbon atoms. The alkyl group having 1 to 10 carbon atoms may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group. Examples of aromatic hydrocarbon groups include the phenyl group.

[0037] In equations (1) and (2), R 3 or R 4 Specific examples of hydrocarbon groups having 1 to 10 carbon atoms represented by include the methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, cyclohexyl group, cyclopentyl group, isobornyl group, and phenyl group.

[0038] R in equations (1) and (2) 3 and R 4 R 3 is a hydrogen atom, and R 4 It is preferable that the structure is one other than the case where it is a hydrogen atom. Furthermore, in equations (1) and (2), R 3 and R 4 These are preferably hydrogen atoms or hydroxyl groups, and more preferably both are hydroxyl groups.

[0039] Preferred specific examples of the chain transfer agent, which is one embodiment of the present disclosure, include styrene dimer derivatives represented by the following formulas: (1-1) (α-methylstyrene dimer: αMSD), (1-2) (SD-1), or (1-3) (SD-2).

[0040] [ka]

[0041] [Copolymers and Methods for Manufacturing Copolymers] One embodiment of the present disclosure is a method for producing a copolymer, which includes the step of copolymerizing a compound in the presence of a chain transfer agent represented by formula (1) and at least one of the chain transfer agents represented by formula (2).

[0042] The copolymerization step preferably includes copolymerizing a compound represented by the following formula (3) with a compound represented by the following formula (4).

[0043] [ka]

[0044] In the above equation (3), R 5 This represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. In the above equation (4), R 6 and R 7Each of these independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.

[0045] One embodiment of the present disclosure is a method for producing a copolymer, which includes the step of copolymerizing a compound represented by formula (3) and a compound represented by formula (4) in the presence of a chain transfer agent represented by formula (1) and at least one of the chain transfer agents represented by formula (2).

[0046] A copolymer manufacturing method, which is one embodiment of the present disclosure, is preferably a method for manufacturing a copolymer as described below. Furthermore, a copolymer, which is a copolymer manufactured by a copolymer manufacturing method, which is one embodiment of the present disclosure. A copolymer according to one embodiment of the present disclosure comprises a constituent unit A derived from the compound represented by formula (3) and a constituent unit B derived from the compound represented by formula (4).

[0047] <Component Unit A> Constituent unit A is a constituent unit derived from the compound represented by the following formula (3). In this disclosure, "constituent unit derived from the compound represented by formula (3)" means a divalent structural unit that forms the main chain of a polymer when the compound represented by formula (3) undergoes an addition polymerization reaction.

[0048] [ka]

[0049] In formula (3), R 5 This represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms.

[0050] A hydrocarbon group having 1 to 6 carbon atoms may be unsubstituted or substituted. If the hydrocarbon group has substituents, the carbon atoms of the substituents are not included in the carbon number of the hydrocarbon group (1 to 6 carbon atoms). Hydrocarbon groups having 1 to 6 carbon atoms are preferably unsubstituted.

[0051] In formula (3), R 5 Examples of hydrocarbon groups having 1 to 6 carbon atoms, as represented by , include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include alkyl groups having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon atoms may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group. R 1 Specific examples of hydrocarbon groups having 1 to 6 carbon atoms represented by include the methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, and phenyl group. Examples of aromatic hydrocarbon groups include the phenyl group.

[0052] In formula (3), R 5 It is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A hydrogen atom or a methyl group is more preferable, and a methyl group is even more preferable. R in equation (3) 5 The compound in which is a methyl group is p-isopropenylphenol (hereinafter also referred to as "PIPE"), and R in formula (3) 5 The compound in which the atom is a hydrogen atom is p-hydroxystyrene (PHS).

[0053] A copolymer according to one embodiment of the present disclosure may contain one type of constituent unit A alone, or it may contain two or more types of constituent unit A.

[0054] In a copolymerization reaction between a compound represented by formula (3) and a compound represented by formula (4), the chain transfer agent R, which is an embodiment of the present disclosure represented by formula (1) or formula (2), is used. 3 and R 4If all of them are hydroxyl groups, it is thought that a compound having hydroxyl groups similar to that of formula (3), based on this chain transfer agent, will act. Therefore, copolymers with a uniform variety of monomers can be obtained. Accordingly, in particular, in the copolymerization reaction between the compound represented by formula (3) and the compound represented by formula (4), among the above chain transfer agents, R 3 and R 4 It is preferable to use a chain transfer agent in which all of the components are hydroxyl groups.

[0055] The content of constituent unit A in the copolymer, which is one embodiment of the present disclosure, is not particularly limited. In a copolymer according to one embodiment of the present disclosure, the proportion of constituent unit A to the total of constituent unit B is preferably, for example, in the range of more than 0 mol% and 80 mol% or less, more preferably in the range of 1 mol% to 70 mol%, even more preferably in the range of 10 mol% to 60 mol%, and particularly preferably in the range of 30 mol% to 60 mol%. Most preferably, it is 50 mol% or less. In a copolymer according to one embodiment of the present disclosure, if the proportion of constituent unit A to the total of constituent unit B is within the above range, the polydispersity of the copolymer tends to decrease.

[0056] <Component Unit B> Constituent unit B is a constituent unit derived from the compound represented by the following formula (4). In this disclosure, "constituent units derived from the compound represented by formula (4)" means divalent constituent units that form the main chain of the polymer when the compound represented by formula (4) undergoes an addition polymerization reaction.

[0057] [ka]

[0058] In formula (4), R 6 and R 7 Each of these independently represents either a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.

[0059] In formula (4), R 6 and R 7 They may be the same or they may be different. In formula (4), R 6 and R 7 The hydrocarbon group having 1 to 20 carbon atoms represented by may be unsubstituted or may have substituents. If the hydrocarbon group has substituents, the carbon atoms of the substituents are not included in the carbon number range of 1 to 10 of the hydrocarbon group. Examples of substituents include hydroxyl groups, carboxyl groups, halogen atoms, cyano groups, isocyanate groups, alkoxysilyl groups, thiol groups, catechol groups, phenol groups, aryl groups, amino groups, and dialkylamino groups.

[0060] In formula (4), R 6 and R 7 Examples of hydrocarbon groups having 1 to 20 carbon atoms, as represented by , include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include alkyl groups having 1 to 20 carbon atoms. The alkyl group having 1 to 20 carbon atoms may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group. Examples of aromatic hydrocarbon groups include phenyl groups and trityl groups (triphenylmethyl groups).

[0061] In formula (4), R 6 and R 7Specific examples of hydrocarbon groups with 1 to 20 carbon atoms represented include unsubstituted alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, cyclohexyl group, cyclopentyl group, isobornyl group, norbornyl group, and adamantyl group, as well as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxyn-propyl group, 2-hydroxyn-propyl group, 3-hydroxyn-propyl group, 1-hydroxyisopropyl group, 2,3-dihydroxy-n-propyl, 1-hydroxyn-butyl group, 2-hydroxyn-butyl group, and 3 Examples include hydroxysubstituted alkyl groups such as -hydroxyn-butyl group and 4-hydroxyn-butyl group, halogen-substituted alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, 2,2,2,2',2',2'-hexafluoroisopropyl group, 2,2,3,4,4,4-hexafluorobutyl group, 2-chloroethyl group, trichloroethyl group, 3-bromoethyl group, and heptafluoroisopropyl group, cyanosubstituted alkyl groups such as 2-cyanoethyl group, dialkylamino-substituted alkyl groups such as 2-(dimethylamino)ethyl group, 3-(dimethylamino)propyl group, and 3-dimethylaminoneopentyl group, and phenyl group and trityl group.

[0062] In formula (4), R 6 It is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0063] In formula (4), R 7 It is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 6 carbon atoms (i.e., an n-hexyl group or a cyclohexyl group), and even more preferably a cyclohexyl group.

[0064] Specific examples of compounds represented by formula (4) include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, s-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate, isobornyl acrylate, norbornyl acrylate, adamantyl acrylate, hydroxymethyl acrylate, 1-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, trifluoromethyl acrylate, 2,2,2-trifluoroethyl acrylate, hexafluoroisopropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl acrylate, 2-cyanoethyl acrylate, and 2-(di) acrylate. Examples include methylaminoethyl methacrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, hydroxymethyl methacrylate, 1-hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, trifluoromethyl methacrylate, 2,2,2-trifluoroethyl methacrylate, hexafluoroisopropyl methacrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2-cyanoethyl methacrylate, and 2-(dimethylamino)ethyl methacrylate, phenyl acrylate, trityl acrylate, etc. Among these, the compound represented by formula (4) is more preferably at least one selected from the group consisting of n-butyl acrylate, i-butyl acrylate, s-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate, isobornyl acrylate, norbornyl acrylate, and adamantyl acrylate; more preferably at least one selected from n-hexyl acrylate and cyclohexyl acrylate; and particularly preferably n-butyl acrylate.

[0065] In formula (4), R 6 It is preferably a hydrogen atom, and R7 It is preferable that it is a cyclohexyl group. In equation (4), R 6 is hydrogen, and R 7 The compound in which the group is a cyclohexyl group is cyclohexyl acrylate (hereinafter also referred to as "CHA").

[0066] One embodiment of the copolymer of the present disclosure may contain one type of constituent unit B alone, or two or more types, but it is preferable to contain two or more types of constituent unit B. In one embodiment of the present disclosure, the copolymer tends to have a lower degree of polydispersity when it contains two or more constituent units B.

[0067] One embodiment of the present disclosure is a copolymer comprising a constituent unit A derived from a compound represented by formula (3) and a constituent unit B derived from a compound represented by formula (4), wherein in formula (3), R 5 R represents a hydrogen atom or a methyl group, and in formula (4), 6 R represents a hydrogen atom or a methyl group. 7 It is preferable that R is a copolymer representing a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. 7 Examples of hydrocarbon groups having 1 to 10 carbon atoms, or preferred compounds, are the same as described above.

[0068] In a copolymer that is one embodiment of the present disclosure, preferred specific examples of constituent units A and B include a constituent unit derived from a compound represented by the following formula (3-1)(PIPE) and a constituent unit derived from a compound represented by the formula (4-1)(CHA). The term "constituent unit" refers to the divalent structural unit that forms the main chain of the polymer when each compound represented by formula (3-1) or formula (4-1) undergoes an addition polymerization reaction.

[0069] [ka]

[0070] <Other constituent units> The copolymer may, as necessary, contain constituent units (so-called other constituent units) derived from compounds other than the compound represented by formula (3) and the compound represented by formula (4) (so-called other compounds), to the extent that it does not impair the effects of the present disclosure. Other compounds include, for example, derivative compounds in which the hydroxyl group of formula (3) is replaced with a protecting group (e.g., an acetoxy group), and the hydroxyl group in formula (4) (e.g., R 3 Examples of compounds include derivative compounds in which (when the atom is a hydrogen atom) is substituted with a protecting group (e.g., an acetoxy group), compounds containing a (meth)acrylamide group, compounds containing a (meth)acrylonitrile group, and vinyl group-containing aromatic hydrocarbon compounds such as styrene. If the copolymer of the present disclosure contains other constituent units, these other constituent units may consist of one type alone or two or more types. The proportion of other constituent units to the total constituent units of the copolymer, which is one embodiment of this disclosure, is preferably in the range of 0 mol% to 20 mol%, more preferably in the range of 0 mol% to 10 mol%, even more preferably in the range of 0 mol% to 5 mol%, and particularly preferably 0 mol%.

[0071] The proportion (in %) of each constituent unit contained in a copolymer according to one embodiment of this disclosure can be controlled by the amount of each monomer charged and the conversion rate of each monomer. More specifically, by adjusting the amount of each monomer charged, taking into account the conversion rate of each monomer, the proportion of each constituent unit contained in the copolymer can be controlled to a desired value. For example, the proportion of each monomer in a copolymer of monomer X and monomer Y can be calculated using the following formula, for instance, if the amount of monomer X charged (in mol%) is X1, the amount of monomer Y charged (in mol%) is Y1, the conversion rate of monomer X (in %) is X2, and the conversion rate of monomer Y (in %) is Y2. Percentage of monomer X in copolymer (%) =(X1×X2) / [(X1×X2)+(Y1×Y2)]×100 Percentage of monomer Y in copolymer (%) =(Y1×Y2) / [(X1×X2)+(Y1×Y2)]×100

[0072] The monomer conversion rate of the copolymer is calculated using the following formula based on the area value A1 of the monomer before polymerization, the area value A2 of the monomer after polymerization, the area value B1 of the internal standard before polymerization, and the area value B2 of the internal standard after polymerization, obtained by gas chromatography (GC) under the following conditions. Decane is used as the internal standard. Monomer conversion rate (%) = [1 - (A2 / B2) / (A1 / B1)] × 100

[0073] ~GC conditions~ Measuring device: GC [Model number: GC-2030, manufactured by Shimadzu Corporation] Detector: Flame ionization detector (FID) Detection temperature: 270℃ Column: HP-INNOwax 19091N-236I [Length 60m x Inner diameter 0.25mm, Film thickness 0.50μm, manufactured by Agilent Technologies, Inc.] Column temperature: 40℃ Evaporation temperature: 250℃ Flow rate: 1.3mL / min Concentration of sample solution: 20 mg / mL (methanol solution) Injection volume: 1.0μL

[0074] The proportion (in %) of each constituent unit contained in a copolymer, which is one embodiment of this disclosure, can be confirmed by analytical methods such as nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) absorption spectroscopy, or gas chromatography-mass spectroscopy (GC-MS). Alternatively, it may be confirmed by combining two or more of these analytical methods.

[0075] <polymerization modes of copolymers> The polymerization form of the copolymer, which is one embodiment of the present disclosure, is not particularly limited. The copolymer in one embodiment of the present disclosure may be, for example, a random copolymer, an alternating copolymer, a block copolymer, or a graft copolymer. With a chain transfer agent according to one embodiment of the present disclosure, when the compound represented by formula (3) and the compound represented by formula (4) are used as copolymer monomers, random polymerization tends to be difficult and alternating polymerization tends to be easy. With a chain transfer agent according to one embodiment of the present disclosure, an alternating copolymer can be formed by alternating polymerization of the compound represented by formula (3) and the compound represented by formula (4) in a 1:1 ratio. Therefore, by using a chain transfer agent, which is one embodiment of the present disclosure, when the compound represented by formula (3) and the compound represented by formula (4) are used as copolymer monomers, a copolymer in which the two types of monomers are regularly arranged is easily formed, which is preferable because the degree of polydispersity is suppressed, and as a result the physical properties are stabilized and phase separation is prevented.

[0076] <Weight-average molecular weight and polydispersity of copolymers> The weight-average molecular weight (Mw) of a copolymer according to one embodiment of this disclosure is not particularly limited. The lower limit of the weight-average molecular weight (Mw) of a copolymer according to one embodiment of the present disclosure is preferably, for example, 3,000, more preferably 4,000, even more preferably 5,000, and particularly preferably 7,000. The upper limit of the weight-average molecular weight (Mw) of the copolymer according to the present disclosure is preferably, for example, 80,000, more preferably 70,000, even more preferably 60,000, particularly preferably 50,000, and most preferably 25,000. In some embodiments, the weight-average molecular weight (Mw) of a copolymer that is an embodiment of the present disclosure may be in the range of 3,000 to 80,000, 4,000 to 70,000, 5,000 to 60,000, 7,000 to 50,000, or 7,000 to 25,000.

[0077] The degree of polydispersity of the copolymer, which is one embodiment of the present disclosure, is not particularly limited. In this disclosure, polydispersity is defined as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) [Mw / Mn]. The polydispersity of the copolymer according to one embodiment of the present disclosure is preferably in the range of 1.0 to 5.0, more preferably in the range of 1.2 to 4.0, and even more preferably in the range of 1.4 to 3.0. The polydispersity of the copolymer according to one embodiment of the present disclosure is particularly preferably less than 2.0, and most preferably 1.6 to less than 2.0.

[0078] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of a copolymer according to one embodiment of this disclosure are values ​​measured by gel permeation chromatography (GPC). Specifically, these values ​​are obtained by measuring the molecular weight distribution by GPC under the following conditions and converting them using a calibration curve for monodisperse standard polystyrene.

[0079] ~GPC conditions~ Measurement device: High-speed GPC [Model number: LC-40D, manufactured by Shimadzu Corporation] Detector: Differential refractive index (RI) detector Column: Shodex GPC KF-802 (manufactured by Resonac Corporation), Shodex The GPC KF-803 (manufactured by Resonac Corporation) and the Shodex GPC KF-804 (manufactured by Resonac Corporation) are used in conjunction with each other. Column temperature: 40℃ Flow rate: 1.0mL / min Eluent: Tetrahydrofuran (THF) Concentration of sample solution: 5 mg / mL (THF solution) Sample solution injection volume: 10 μL

[0080] <Uses of copolymers> The applications of the copolymer, which is one embodiment of the present disclosure, are not particularly limited. Applications of the copolymer according to one embodiment of this disclosure include, for example, resist materials, coatings, paints, adhesives, tacks, dispersants, and binders. The copolymers of this disclosure are suitable, for example, as resist materials. One embodiment of the copolymer present disclosure has a suppressed and relatively small polydispersity, a reduction in high molecular weight molecules, and uniform molecular weights, resulting in smaller differences in solubility between molecular chains. For example, it can improve the roughness of a photoresist.

[0081] <Method for producing copolymers> A method for producing a copolymer according to one embodiment of the present disclosure includes the step of copolymerizing a compound in the presence of at least one of a chain transfer agent represented by formula (1) and a chain transfer agent represented by formula (2), according to one embodiment of the present disclosure. A copolymer according to one embodiment of the present disclosure can be produced, for example, by mixing a monomer mixture containing a compound represented by formula (3), a compound represented by formula (4), and other compounds to be copolymerized as needed, a polymerization initiator, and a solvent, and heating the mixture.

[0082] The chain transfer agent is the same as described above. There are no restrictions on the amount of chain transfer agent used, but from the viewpoint of ensuring the reaction proceeds smoothly, it is preferably 0.1 mol% to 10 mol%, more preferably 0.5 mol% to 8.0 mol%, and even more preferably 1.0 mol% to 6.0 mol%, based on the total number of moles of the monomer mixture.

[0083] The polymerization initiator is not particularly limited, as long as it is a known polymerization initiator. Among known polymerization initiators, radical polymerization initiators are preferred. Specific examples of radical polymerization initiators include azo-based initiators such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonnitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(isobutyric acid) dimethyl, 2,2'-azobisisobutylamidine dihydrochloride, 4,4'-azobis-4-cyanovaleric acid, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxide, lauroyl peroxide, acetyl peroxide, diisopropyl dicarbonate peroxide, and benzoyl peroxide. Examples of peroxide initiators include menhydroperoxide, t-butylhydroperoxide, dicumylperoxide, p-menthanehydroperoxide, pinanhydroperoxide, methylethyl ketone peroxide, cyclohexanone peroxide, diisopropylperoxydicarbonate, t-butylperoxylaurate, di-t-butylperoxyphthalate, dibenzyloxide, and 2,5-dimethylhexane-2,5-dihydroperoxide; benzoyl peroxide-N,N-dimethylaniline initiators; and redox initiators such as peroxodisulfate-sodium bisulfite. Among these, azo-based initiators or peroxide-based initiators are preferred as radical polymerization initiators, and at least one selected from the group consisting of 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonnitrile), 2,2'-azobis(isobutyric acid)dimethyl, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxide, lauroyl peroxide, diisopropyl dicarbonate peroxide, and acetyl peroxide is more preferred.

[0084] In one embodiment of the present disclosure, a polymerization initiator may be used alone, or two or more may be used simultaneously or sequentially.

[0085] The amount of polymerization initiator used is not particularly limited. The lower limit of the amount of polymerization initiator used is preferably 0.0001 molar times or more, more preferably 0.001 molar times or more, and even more preferably 0.005 molar times or more, relative to the total amount of the compound represented by formula (1), the compound represented by formula (2), and other compounds copolymerized as needed. The upper limit of the amount of polymerization initiator used is preferably 0.1 molar times or less, and more preferably 0.05 molar times or less, relative to the total amount of the compound represented by formula (1), the compound represented by formula (2), and other compounds copolymerized as needed. If the total amount of polymerization initiator used is as stated above, the entire amount may be added at the start of heating, or You can prepare a portion of the ingredients at the start of heating and the rest after heating begins, or you can prepare the entire amount after heating begins.

[0086] The solvent is not particularly limited, as long as it does not inhibit the polymerization reaction. Specific examples of solvents include ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, and γ-butyrolactone; alcohol compounds such as n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, n-octanol, 2-ethylhexanol, and n-dodecyl alcohol; glycol compounds such as ethylene glycol, propylene glycol, and diethylene glycol; ether compounds such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, tetrahydrofuran, and dioxane; alcohol ether compounds such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, diethylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate (PGMEA); and n-propyl formate, isopropyl formate, and n-propyl formate. -Butyl, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, n-hexyl acetate, methyl propionate, ethyl propionate, methyl butyrate, and other ester compounds; monooxycarboxylic acid ester compounds such as methyl 2-oxypropionate, ethyl 2-oxypropionate, n-propyl 2-oxypropionate, isopropyl 2-oxypropionate, ethyl 2-oxy-2-methylpropionate, methyl 2-oxy-3-methylbutyrate, ethyl methoxyethyl, ethyl ethoxyethyl, 3- Alkoxycarboxylic acid ester compounds such as methyl methoxypropionate, ethyl 3-methoxypropionate, and methyl 3-ethoxypropionate; cellosolve ester compounds such as cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate; aromatic hydrocarbon compounds such as benzene, toluene, and xylene; halogenated hydrocarbon compounds such as trichloroethylene, chlorobenzene, and dichlorobenzene; and dimethylacetamide, dimethylformamide, N-methylacetamide, N-methylpyrrolidone, N,Examples include amide compounds such as N'-dimethylimidazolidinone. Among these, at least one solvent selected from the group consisting of methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isopropyl alcohol, n-butyl alcohol, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME), ethyl acetate, propylene glycol monomethyl ether acetate (PGMEA), cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, and toluene is preferred.

[0087] In one embodiment of the present disclosure, a solvent may be used alone or in a mixture of two or more solvents. In one embodiment of the present disclosure, the method for producing a copolymer is preferable to produce a homogeneous reaction solution by using a solvent, but it may also be a heterogeneous multiple-phase solution.

[0088] The amount of solvent used is not particularly limited and can be appropriately set depending on, for example, the type and amount of monomer, the type and amount of polymerization initiator, and the molecular weight of the desired copolymer. The lower limit of the amount of solvent used is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 50 parts by mass or more, per 100 parts by mass of the total amount of the monomer mixture. The upper limit of the amount of solvent used is preferably 10,000 parts by mass or less, more preferably 5,000 parts by mass or less, and even more preferably 1,000 parts by mass or less, per 100 parts by mass of the total amount of the monomer mixture. A particularly preferred amount of solvent used is one in which the solid content concentration of the copolymer produced by the polymerization reaction is 25% by mass to 75% by mass without any concentration adjustment after the polymerization reaction.

[0089] The method of carrying out the polymerization reaction in a copolymer production method according to one embodiment of the present disclosure is not particularly limited, as long as the compound represented by formula (3), the compound represented by formula (4), and other compounds to be copolymerized as needed, as well as the polymerization initiator and solvent, are effectively mixed and brought into contact. For example, it may be a batch method, a semi-batch method, or a continuous flow method. In the method for producing copolymers according to the present disclosure, it is preferable to employ methods such as charging a compound represented by formula (3), a compound represented by formula (4), and other compounds to be copolymerized as needed, along with a polymerization initiator and a solvent, into a reactor all at once and heating it; or continuously or intermittently adding a compound represented by formula (3), a compound represented by formula (4), and other compounds to be copolymerized as needed, along with a polymerization initiator and a solvent, to a reactor that has been partially charged with solvent, and then heating it.

[0090] In one embodiment of the present disclosure, a method for producing a copolymer is preferably carried out by heating. The heating temperature is not particularly limited as long as it is the temperature at which the polymerization reaction proceeds, and can be set appropriately depending on, for example, the degree of polymerization and composition of the desired copolymer, as well as the type and amount of polymerization initiator used. The lower limit of the heating temperature is preferably 40°C, more preferably 45°C, even more preferably 50°C, and particularly preferably 60°C. The upper limit of the heating temperature is preferably 250°C, more preferably 180°C, even more preferably 160°C, and particularly preferably 150°C.

[0091] The polymerization time is not particularly limited and can be set appropriately depending on, for example, the degree of polymerization and composition of the desired copolymer, as well as the type and amount of polymerization initiator used. The lower limit of the polymerization time is preferably, for example, 0.01 hours or more. The upper limit of the polymerization time is preferably, for example, 40 hours or less, and more preferably 20 hours or less.

[0092] The polymerization reaction may be carried out under reflux if necessary. Carrying the polymerization reaction under reflux is preferable because it allows for efficient removal of the reaction heat. The polymerization reaction may be carried out under reduced pressure, at atmospheric pressure, or under increased pressure. Furthermore, while polymerization reactions can be carried out in the presence of molecular oxygen such as air, it is preferable to carry them out in an inert gas atmosphere such as nitrogen or argon.

[0093] In one embodiment of the present disclosure, a method for producing a copolymer may use additives such as phenolic compounds for purposes such as improving the yield of the copolymer or changing the arrangement of the constituent units of the copolymer.

[0094] Furthermore, in one embodiment of the present disclosure, if the compound represented by formula (3) and / or the compound represented by formula (4) has a highly reactive functional group (so-called reactive functional group), it can be produced by first introducing a protecting group to the reactive functional group (e.g., a hydroxyl group) to deactivate the functional group, then carrying out the polymerization reaction, and then removing the protecting group (so-called deprotection). Alternatively, the copolymer of the present disclosure may be produced, for example, by using a compound having a protecting group as a raw material, carrying out the polymerization reaction, and then removing the protecting group (so-called deprotection). In this disclosure, the method for deprotection after the polymerization reaction is not particularly limited, and known methods can be employed. For example, after the polymerization reaction is complete, the protecting groups can be removed by alkaline hydrolysis of the obtained copolymer in an organic solvent. For alkaline hydrolysis, bases such as aqueous ammonia and triethylamine can be used. The reaction temperature is, for example, -20°C to 100°C, preferably 0°C to 60°C. The reaction time is, for example, 0.2 hours to 100 hours, preferably 0.5 hours to 20 hours.

[0095] After the polymerization reaction is complete, the copolymer can be isolated from the solution containing the copolymer by methods such as solvent extraction, fractional precipitation, or thin-film evaporation. For example, when using a copolymer, which is one embodiment of the present disclosure, as a resist material, the solution containing the copolymer may be used as the resist material without isolating the copolymer from the solution containing the copolymer.

[0096] [Composition] A composition that is one embodiment of the present disclosure comprises a copolymer that is one embodiment of the present disclosure. A composition according to one embodiment of the present disclosure may contain one copolymer according to one embodiment of the present disclosure alone, or it may contain two or more copolymers according to one embodiment of the present disclosure. The content of the copolymer according to one embodiment of the present disclosure in the composition according to one embodiment of the present disclosure is not particularly limited and can be set as appropriate depending on the purpose. For example, the content of the copolymer according to one embodiment of the present disclosure in the composition according to one embodiment of the present disclosure may be 10% to 90% by mass with respect to the total mass of the composition.

[0097] A composition according to one embodiment of the present disclosure may optionally contain components other than the copolymer according to one embodiment of the present disclosure (so-called other components). Other components include, for example, solvents, surfactants, polar resins, curing agents, curing catalysts, leveling agents, defoamers, antioxidants, heat stabilizers, light stabilizers (e.g., UV absorbers), plasticizers, pigments (e.g., rutile titanium dioxide, zinc oxide, and carbon black), thixotropes, thickeners, tackifiers (e.g., rosin resins and terpene resins), surface modifiers, anti-settling agents, weathering agents, pigment dispersants, antistatic agents, fillers, organic microparticles, inorganic microparticles, antifungal agents, and silane coupling agents. The curing agent is not particularly limited, but examples include polyisocyanate monomers, modified polyisocyanates, epoxy resins, and amino resins. Of these, polyisocyanate monomers are monomeric compounds having multiple isocyanate groups in one molecule, and examples of such polyisocyanate monomers include aromatic polyisocyanates, aromatic aliphatic polyisocyanates, and aliphatic polyisocyanates. Examples of epoxy resins include bisphenol A type epoxy resins and alicyclic epoxy resins. Examples of amino resins include alkylated urea resins, alkylated melamine resins, and alkylated benzoguanamine resins.

[0098] <Uses of the composition> The uses of the composition, which is one embodiment of the present disclosure, are not particularly limited. Applications of the composition, which is one embodiment of the present disclosure, include, for example, resist materials, coatings, paints, adhesives, tacks, dispersants, and binders. The copolymer of the present disclosure contained in a composition according to one embodiment of the present disclosure has, for example, a suppressed and relatively small polydispersity, a reduction in high molecular weight molecules, and uniform molecular weight size, resulting in a small difference in solubility between molecular chains. Therefore, the composition according to one embodiment of the present disclosure is suitable as a resist composition from the viewpoint of improving the roughness of the photoresist. [Examples]

[0099] Hereinafter, a copolymer, which is one embodiment of the present disclosure, will be described in more detail by reference to examples. The present disclosure is not limited to the following examples unless it exceeds the spirit of the disclosure.

[0100] [Measurement of the molar ratio of styrene dimer] In the example, the molar ratio of styrene dimers (SD-1 and SD-2) was 1It was calculated by measuring the 1H-NMR spectrum. Using deuterated dimethyl sulfoxide with δ = 2.50 ppm as the reference signal, for SD-1, the integral value of the peak at the hydroxyl group signal of the external double bond δ = 5.00 ppm was measured, and for SD-2, the integral value of the peak at the hydroxyl group signal of the internal double bond δ = 5.93 ppm was measured. The ratio of the integral values was calculated as the molar ratio.

[0101] ~ 1 1H-NMR conditions~ Measuring device: Nuclear magnetic resonance apparatus [Model number: ECZ400S, manufactured by JEOL Ltd.] Measuring solvent: Deuterated dimethyl sulfoxide (DMSO-d6) Sample concentration: 1.0 mass% Measuring temperature: 25 °C

[0102] [Measurement of weight-average molecular weight (Mw), number-average molecular weight (Mn) and molecular weight distribution of the copolymer] In the examples, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the copolymer were determined by measuring the molecular weight distribution by gel permeation chromatography (GPC) under the following conditions and converting using the calibration curve of monodisperse standard polystyrene. The polydispersity (Mw / Mn) of the copolymer was measured by GPC in the same manner as above.

[0103] ~GPC conditions~ Measuring device: High-speed GPC [Model number: LC-40D, manufactured by Shimadzu Corporation] Detector: Differential refractive index (RI) detector Columns: Shodex GPC KF-802 [manufactured by Resonac Co., Ltd.], Shodex GPC KF-803 [manufactured by Resonac Co., Ltd.], and Shodex GPC KF-804 [manufactured by Resonac Co., Ltd.] were connected and used Column temperature: 40 °C Flow rate: 1.0 mL / min Eluent: Tetrahydrofuran (THF) Concentration of the sample solution: 5 mg / mL (THF solution) Injection volume of the sample solution: 10 μL

[0104] [Measurement of monomer conversion rate] In the examples, the monomer conversion rate (in %) was calculated using the following formula based on the area value A1 of the monomer before polymerization, the area value A2 of the monomer after polymerization, the area value B1 of the internal standard before polymerization, and the area value B2 of the internal standard after polymerization, obtained by gas chromatography (GC) under the following conditions. Decane was used as the internal standard. Monomer conversion rate (%) = [1 - (A2 / B2) / (A1 / B1)] × 100

[0105] ~GC conditions~ Measuring device: GC [Model number: GC-2030, manufactured by Shimadzu Corporation] Detector: Flame ionization detector (FID) Detection temperature: 270℃ Column: HP-INNOwax 19091N-236I [Length 60m x Inner diameter 0.25mm, Film thickness 0.50μm, manufactured by Agilent Technologies, Inc.] Column temperature: 40℃ Evaporation temperature: 250℃ Flow rate: 1.3mL / min Concentration of sample solution: 20 mg / mL (methanol solution) Injection volume: 1.0μL

[0106] [Method for producing styrene dimer] α-methylstyrene dimer (indicated as αMSD in Table 1) was manufactured by Tokyo Chemical Industry Co., Ltd. SD-1 and SD-2 were synthesized as follows. In a 300 mL round-bottom flask, 15.6 g of bisphenol A and 90.3 g of concentrated sulfuric acid were added under ice cooling, and then stirred at room temperature for 40 minutes. Separately, 500 mL of ice water was prepared in a 1 L beaker. Next, after stirring in the round-bottom flask was complete, the solution from the flask was slowly poured into a beaker and stirred at room temperature for 30 minutes. The resulting solid was filtered by suction, and the obtained solid was dissolved in 150 mL of ethyl acetate and washed three times with 150 mL of 5% sodium bicarbonate aqueous solution. The washed solution was concentrated using an evaporator and then purified by silica gel column chromatography (methanol / chloroform). The purified solid was placed in a separate beaker, 10 mL of toluene was added, and the mixture was washed by decantation with stirring. After this washing was repeated four times, the solvent was changed to chloroform, and the washing was repeated four times in the same manner as the toluene washing. The resulting solution was concentrated in an evaporator and then dried in a desiccator to obtain 2.0 g of a simple yellow powder (SD-1:SD-2 = 1:0.3). The molar ratio of the obtained SD-1 to SD-2 was as described above. 1 The measurement was performed using 1H-NMR.

[0107] [Manufacturing of copolymers] <Example 1> In a 100 mL Schlenk tube, 2.00 g of p-isopropenylphenol (PIPE), 2.30 g of cyclohexyl acrylate (CHA), 0.21 g of α-methylstyrene dimer (αMSD; chain transfer agent (styrene dimer derivative)), 2.10 g of propylene glycol monomethyl ether acetate (PGMEA), and 0.20 g of dodecane as an internal standard were charged at room temperature. A stirrer, a nitrogen introduction line, and a cap made of silicone rubber stopper were then installed. Separately, 140 mg of 2,2'-azobis(isobutyrate)dimethyl (V-601) was weighed into a round-bottom flask as a polymerization initiator, and 0.50 g of PGMEA was added and dissolved to prepare a polymerization initiator solution. Next, nitrogen bubbling was performed on the solution in the Schlenk tube at a rate of 0.5 mL / min for 30 minutes, and on the polymerization initiator solution in the round-bottom flask at a rate of 0.5 mL / min for 10 minutes, to replace the system with nitrogen gas. After stopping the nitrogen bubbling, the Schlenk tube was heated to 80°C under a nitrogen flow and stirring was started. Once the internal temperature reached 80°C, the polymerization initiator solution was added to the solution in the Schlenk tube and stirred for 9 hours to obtain a copolymer solution of PIPE and CHA (Mw=12,000, Mw / Mn=1.87).

[0108] Table 1 shows the types and amounts of monomers, the amount of polymerization initiator, the amount of solvent used, and the type and amount of solvent added during the reprecipitation process in the production of the copolymer of Example 1. Table 2 shows the amount of monomers used in the production of the copolymer of Example 1, as well as the composition and properties of the copolymer of Example 1.

[0109] <Examples 2-4 and Comparative Example 1> Copolymers of Examples 2-4 and Comparative Example 1 were obtained by performing the same procedure as in Example 1, except that the type and concentration of the chain transfer agent (styrene dimer derivative) were changed as shown in Tables 1 and 2. In Examples 3 and 4, a mixture of SD-1 and SD-2 was used as the styrene dimer derivative. The mixing ratio was 1.0:0.3 molar ratio of SD-1:SD-2. Table 1 shows the types and amounts of monomers, the amount of polymerization initiator, the amount of solvent, and the type and amount of solvent added during the reprecipitation treatment in the production of the copolymers of Examples 2-4 and Comparative Example 1. Table 2 shows the composition and physical properties of the copolymers.

[0110] [Table 1]

[0111] [Table 2]

[0112] Details of each component listed in Tables 1 and 2 are as follows. <Styrene dimer derivatives> "αMSD": α-methylstyrene dimer [In formula (1), R 1 = methyl group, R 2 = methyl group, R 3 = hydrogen atom, R 4 = hydrogen atom, formula (1-1)] "SD-1": Styrene dimer 1 [In formula (1), R 1 = methyl group, R 2 = methyl group, R 3 = hydroxyl group, R 4 = hydroxyl group, formula (1-2)] "SD-2": Styrene dimer 2 [In formula (2), R 1 = methyl group, R 2 = methyl group, R 3 = hydroxyl group, R 4 = hydroxyl group, formula (1-3)] <Compound represented by formula (3)> "PIPE": p-isopropenylphenol [In formula (3), R 5 = methyl group] <Compound represented by formula (4)> "CHA": Cyclohexyl acrylate [In formula (4), R 6 = hydrogen atom, R 7 = cyclohexyl group]

[0113] <Solvent> "PGMEA": Propylene glycol monomethyl ether acetate

[0114] All polymerization initiators in Table 1 and Table 2 are "2,2'-azobis(isobutyric acid) dimethyl". In Table 1 and Table 2, "-" means that the component corresponding to that column is not used.

[0115] From the results in Table 2, it was demonstrated that the copolymers of the examples can control the weight average molecular weight with a styrene dimer derivative, reduce the weight average molecular weight, and also control the polydispersity and reduce the polydispersity.

[0116] Figure 1 is a graph showing the molecular weight distribution of the copolymers measured in Examples 1 to 4 and Comparative Example 1. The horizontal axis represents the retention time (RT, in minutes (min)), and the vertical axis represents the GPC response intensity. The Mw / Mn results in Figure 1 and Table 1 demonstrate that by using the chain transfer agent of one embodiment of this disclosure, the proportion of low molecular weight components increases and polydispersity is suppressed in all copolymers. Furthermore, it was demonstrated that the proportion of low molecular weight components can be controlled and polydispersity can be suppressed by adjusting the amount of styrene dimer used as the chain transfer agent, and that the molecular weight size can be made uniform. Therefore, a styrene dimer derivative, which is one embodiment of the present disclosure, has been demonstrated to be excellent as a chain transfer agent.

Claims

1. A chain transfer agent represented by the following formula (1) or formula (2). 【Chemistry 1】 In the above formulas (1) and (2), R １ and R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, R ３ and R ４ Each of these independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms.

2. R in equations (1) and (2) ３ and R ４ R ３ is a hydrogen atom, and R ４ The chain transfer agent according to claim 1, which does not include the case where is a hydrogen atom.

3. R in formula (1) and formula (2) ３ and R ４ The chain transfer agent according to claim 1, wherein R is a hydroxyl group.

4. A method for producing a copolymer, comprising the step of copolymerizing a compound in the presence of a chain transfer agent represented by the following formula (1) and at least one of the chain transfer agents represented by the following formula (2). 【Chemistry 2】 In the above formulas (1) and (2), R １ and R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, R ３ and R ４ Each of these independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms.

5. The method for producing a copolymer according to claim 4, comprising the step of copolymerizing a compound represented by the following formula (3) with a compound represented by the following formula (4). 【Transformation 3】 In the above formula (3), R ５ This represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. In the above formula (4), R ６ and R ７ Each of these independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.

6. The method for producing a copolymer according to claim 5, wherein the proportion of constituent unit A to the total of constituent unit A derived from the compound represented by formula (3) and constituent unit B derived from the compound represented by formula (4) is 50 mol% or less.

7. In equation (3), R ５ A method for producing the copolymer according to claim 5, wherein is a methyl group.

8. In equation (4), R ６ The method for producing a copolymer according to claim 5, wherein is a hydrogen atom.

9. The method for producing a copolymer according to claim 4, wherein the copolymer has a weight-average molecular weight of 25,000 or less.

10. A method for producing a copolymer having a polydispersity of less than 2.0, according to claim 4.

11. A constituent unit A derived from the compound represented by the following formula (3), A constituent unit B derived from the compound represented by the following formula (4), A copolymer containing [a specific component]. 【Chemistry 4】 In the above formula (3), R ５ represents a hydrogen atom or a methyl group. In the above formula (4), R ６ R represents a hydrogen atom or a methyl group. ７ represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

12. The copolymer according to claim 11, wherein the weight-average molecular weight is 25,000 or less.

13. The copolymer according to claim 11, wherein the polydispersity is less than 2.

0.

14. A composition comprising the copolymer according to any one of claims 11 to 13.

15. The composition according to claim 14, which is a resist composition.

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