JP7611686B2 - Method for producing polymer solution and polymer solution - Google Patents

Description

The present invention relates to a method for producing a polymer solution and a polymer solution. More preferably, the present invention relates to a method for producing an alkali-soluble polymer solution and an alkali-soluble polymer solution.

Alkali-soluble polymers are useful as binder polymers for resist compositions for color filters and photolithospacers. In particular, N-substituted maleimide polymers have a high glass transition temperature and can improve thermal properties, and are therefore widely used in the field of electronics resins. For example, in the field of surface protection materials and interlayer insulating materials such as protective films for color filters, hard coat materials, and sealing materials for organic devices, materials that are resistant to yellowing, deformation, etc. even when exposed to heat during the assembly process of electric and electronic parts are required, and it is preferable to use N-substituted maleimide polymers (see, for example, Patent Documents 1 and 2).
This alkali-soluble polymer may be produced by polymerizing a monomer solution containing an acid group-containing monomer such as a carboxyl group, and then adding a compound containing a polymerizable unsaturated double bond to this polymer (precursor polymer) to introduce a polymerizable double bond into the side chain, thereby increasing the curability. When the amount of side chain double bonds to be introduced is increased, it is necessary to increase the amount of acid group-containing monomer used to produce the precursor polymer. For this reason, a specific polymerization solvent is used in the production of a polymer with a large amount of acid groups (see, for example, Patent Document 3).

In addition, the content of N-substituted maleimide monomers may be increased to improve the thermal properties of the polymer (see, for example, Patent Document 4).

Therefore, there is a need for a polymerization solvent that can dissolve the acid group-containing monomer and N-substituted maleimide monomer in the monomer solution to be polymerized uniformly and can be produced stably even when the contents of the monomers are widely changed.

JP 2003-201316 A JP 2003-192739 A JP 2004-107401 A JP 2010-210962 A

For example, N-substituted maleimide monomers are solid at room temperature, and if the amount used is increased to obtain a polymer with good heat resistance, a large amount of solvent may be required to dissolve the monomer. Therefore, when a general-purpose ester solvent is used in the usual amount as a polymerization solvent when producing a polymer solution, it is difficult to obtain a transparent polymer solution. The present invention has been made in consideration of the above-mentioned current situation, and aims to efficiently obtain a polymer solution in which the desired monomer composition is uniformly dissolved.

As a result of intensive research, the present inventors have found a method for producing an alkali-soluble polymer solution and a uniformly dissolved alkali-soluble polymer solution in the polymerization of a monomer solution containing a specific monomer and a solvent. The present inventors have also found that a curable resin composition obtained from such a polymer solution is particularly suitable as a resist composition for forming members for applications such as color filters, and have completed the present invention.
That is, the object of the present invention is achieved by the following (1) and (2).
(1) A method for producing a polymer solution by polymerizing monomers including an acid group-containing monomer and an N-substituted maleimide monomer in the presence of a solvent, the method being characterized in that the content of the acid group-containing monomer is 5 to 40 mass% and the content of the N-substituted maleimide monomer is 1 to 60 mass% relative to 100 mass% of the total amount of the monomers, and the content of the carbonate solvent is 10 to 100 mass% relative to 100 mass% of the total amount of the solvent.
(2) A polymer solution containing a polymer having structural units derived from an acid group-containing monomer and structural units derived from an N-substituted maleimide monomer, and a solvent, wherein the polymer contains 5 to 40 mass% of structural units derived from the acid group-containing monomer and 1 to 60 mass% of structural units derived from the N-substituted maleimide monomer, relative to 100 mass% of the total amount of structural units, and the polymer solution contains 10 to 100 mass% of a carbonate solvent, relative to 100 mass% of the total amount of the solvent.

By using the method for producing a polymer solution of the present invention, a uniformly dissolved polymer solution with a specific monomer composition can be efficiently obtained. The polymers contained therein are of high quality and can be suitably used for various applications such as color filters used in liquid crystal display devices and solid-state imaging devices, inks, printing plates, printed wiring boards, semiconductor devices, photoresists and other optical components, as well as electrical and electronic devices.

The present invention will be described in detail below.
In addition, a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.
In this specification, "(meth)acrylic acid" means "acrylic acid and/or methacrylic acid", and "(meth)acrylate" means "acrylate and/or methacrylate".
In the present application, a numerical range "Min to Max" means a range equal to or greater than the minimum value Min and equal to or less than the maximum value Max. Furthermore, when the upper and lower limit values are described as suitable numerical values in a stepwise manner, a numerical range obtained by appropriately combining the upper and lower limit values described separately is also a suitable numerical range.
[Method for producing polymer solution (raw materials)]
The present invention is a method for producing a polymer solution by polymerizing monomers including an acid group-containing monomer and an N-substituted maleimide monomer in the presence of a solvent, characterized in that the content of the acid group-containing monomer is 5 to 40 mass% and the content of the N-substituted maleimide monomer is 1 to 60 mass% relative to 100 mass% of the total amount of the monomers, and the content of the carbonate solvent is 10 to 100 mass% relative to 100 mass% of the total amount of the solvent.The present invention is preferably a method for producing an alkali-soluble polymer solution.
The monomers and other components used in the present invention will now be described.

[Monomer]
The monomers used in the method for producing a polymer solution of the present invention essentially comprise an acid group-containing monomer and an N-substituted maleimide monomer.
<Acid Group-Containing Monomer>
Examples of the acid group-containing monomer (also referred to as monomer (a)) include compounds having an acid group and/or an acid anhydride group and a polymerizable double bond. Examples of the polymerizable double bond include, for example, a (meth)acryloyl group, a vinyl group, an allyl group, and a methallyl group. Among these, a (meth)acryloyl group is preferable. Specific examples of the acid group-containing monomer include, for example, unsaturated monocarboxylic acids such as (meth)acrylic acid, crotonic acid, cinnamic acid, and vinylbenzoic acid; unsaturated polyvalent carboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid; unsaturated long-chain monocarboxylic acids in which the unsaturated group and the carboxyl group are chain-extended, such as mono(2-acryloyloxyethyl) succinate and mono(2-methacryloyloxyethyl) succinate; and unsaturated acid anhydrides such as maleic anhydride and itaconic anhydride. Among these, from the viewpoints of versatility, availability, etc., unsaturated monocarboxylic acids are preferred, and (meth)acrylic acid is more preferred. The above-mentioned acid group-containing monomers may be used alone or in combination of two or more. Among these, monomers having a carboxyl group are preferred, and (meth)acrylic acid is particularly preferred.

The proportion of the acid group-containing monomer in the monomer to be polymerized is preferably 1 to 60% by mass, more preferably 5 to 50% by mass, particularly preferably 5 to 40% by mass, and most preferably 10 to 35% by mass, based on the total amount of all monomers. If the amount of the acid group-containing monomer is too small, the alkali solubility may be insufficient. If the amount is too large, the thermal decomposition resistance may decrease, or the solubility in the solvent may decrease. In the present invention, as described later, glycidyl (meth)acrylate or the like may be reacted in order to introduce a reactive double bond into the side chain. In such a case, it is necessary to add the amount of the acid group-containing monomer to be consumed in advance. The total amount of the acid group-containing monomer in the monomer component (monomer unit) of the polymer solution after the modification by reacting glycidyl (meth)acrylate or the like is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, particularly preferably 5 to 30% by mass, and most preferably 10 to 30% by mass, based on the total amount of all monomers.
<N-substituted maleimide monomer>
The N-substituted maleimide monomer (also referred to as monomer (b)) may, for example, be a compound represented by the following general formula (1):

（式中、Ｒ^１は、置換基を有していてもよい、炭素数１～３０の一価の炭化水素基を表す。）
一般式（１）中、Ｒ^１は、置換基を有していてもよい、炭素数１～３０の一価の炭化水素基である。上記一価の炭化水素基は、炭素数が１～２０であることが好ましく、６～１２であることがより好ましい。
上記炭化水素基としては、鎖状又は環状の脂肪族炭化水素基、又は芳香族炭化水素基が挙げられる。
上記脂肪族炭化水素基は、飽和脂肪族炭化水素基であってもよいし、不飽和脂肪族炭化水素基であってもよいが、飽和脂肪族炭化水素基であることが好ましい。
鎖状の飽和脂肪族炭化水素基としては、例えば、メチル基、エチル基、ｎ－プロピル基、ｉｓｏ－プロピル基、ｎ－ブチル基、ｔｅｒｔ－ブチル基、ｓｅｃ－ブチル基、ペンチル基、イソペンチル基、ネオペンチル基、ヘキシル基、２－メチルペンチル基、３－メチルペンチル基、２，２－ジメチルブチル基、２，３－ジメチルブチル基、ヘプチル基、２－メチルヘキシル基、３－メチルヘキシル基、２，２－ジメチルペンチル基、２，３－ジメチルペンチル基、２，４－ジメチルペンチル基、３－エチルペンチル基、２，２，３－トリメチルブチル基、オクチル基、メチルヘプチル基、ジメチルヘキシル基、２－エチルヘキシル基、３－エチルヘキシル基、トリメチルペンチル基、３－エチル－２－メチルペンチル基、２－エチル－３－メチルペンチル基、２，２，３，３－テトラメチルブチル基、ノニル基、メチルオクチル基、３，７－ジメチルオクチル基、ジメチルヘプチル基、３－エチルヘプチル基、４－エチルヘプチル基、トリメチルヘキシル基、３，３－ジエチルペンチル基、デシル基、ウンデシル基、ドデシル基等の直鎖状又は分岐鎖状のアルキル基が挙げられる。なかでも、炭素数１～３０のアルキル基であることが好ましく、炭素数１～２０のアルキル基であることがより好ましく、炭素数１～１２のアルキル基であることが更に好ましい。
環状の脂肪族炭化水素基としては、例えば、シクロプロピル基、シクロブチル基、シクロペンチル基、シクロヘキシル基、シクロヘプチル基、シクロオクチル基、シクロノニル基、シクロデシル基、シクロドデシル基等の単環系脂環式炭化水素基；ジシクロペンタニル基、ノルボルニル基、アダマンチル基等の多環系脂環式炭化水素基；が挙げられる。
なかでも、炭素数３～３０の単環又は多環系脂環式炭化水素基であることが好ましく、炭素数３～１８の単環又は多環系脂環式炭化水素基であることがより好ましく、炭素数６～１２の単環系脂環式炭化水素基であることが更に好ましい。
上記芳香族炭化水素基としては、例えば、フェニル基、ナフチル基、ベンジル基等を挙げることができる。なかでも、炭素数６～３０の芳香族炭化水素基であることが好ましく、炭素数６～１２の芳香族炭化水素基であることがより好ましい。
上記炭化水素基は、置換基を有していてもよい。上記置換基としては、例えば、アルキル基、アリール基、水酸基、ハロゲン原子、カルボキシル基、アルコキシ基、アリールオキシ基等が挙げられる。
上記Ｎ－置換マレイミド系単量体の具体例としては、例えば、Ｎ－メチルマレイミド、Ｎ－エチルマレイミド、Ｎ－プロピルマレイミド、Ｎ－イソプロピルマレイミド、Ｎ－ｔ－ブチルマレイミド、Ｎ－ドデシルマレイミド、Ｎ－シクロヘキシルマレイミド、Ｎ－オクチルマレイミド、Ｎ－２－エチルヘキシルマレイミド、Ｎ－デシルマレイミド、Ｎ－ラウリルマレイミド、Ｎ－テトラデシルマレイミド、Ｎ－ステアリルマレイミド、Ｎ－２－デシルテトラデシルマレイミド、Ｎ－フェニルマレイミド、Ｎ－ベンジルマレイミド、Ｎ－ナフチルマレイミド、Ｎ－クロロフェニルマレイミド、Ｎ－メチルフェニルマレイミド、Ｎ－ヒドロキシルエチルマレイミド、Ｎ－ヒドロキシルフェニルマレイミド、Ｎ－メトキシフェニルマレイミド、Ｎ－カルボキシフェニルマレイミド、Ｎ－ニトロフェニルマレイミド、Ｎ－トリブロモフェニルマレイミド、Ｎ，Ｎ’－オルトフェニレンビスマレイミド、Ｎ，Ｎ’－メタフェニレンビスマレイミド、Ｎ，Ｎ’－パラフェニレンビスマレイミド等が挙げられる。なかでも、共重合性の点から、Ｎ－ベンジルマレイミド、Ｎ－フェニルマレイミド、Ｎ－シクロヘキシルマレイミドが好ましく、加熱での着色の少なさの点からＮ－ベンジルマレイミドがより好ましい。
上記Ｎ－ベンジルマレイミドとしては、例えば、ベンジルマレイミド；ｐ－メチルベンジルマレイミド、ｐ－ブチルベンジルマレイミド等のアルキル置換ベンジルマレイミド；ｐ－ヒドロキシベンジルマレイミド等のフェノール性水酸基置換ベンジルマレイミド；ｏ－クロロベンジルマレイミド、ｏ－ジクロロベンジルマレイミド、ｐ－ジクロロベンジルマレイミド等のハロゲン置換ベンジルマレイミド；等が挙げられる。
上記Ｎ－置換マレイミド系単量体は、１種単独で使用してもよいし、２種以上を組み合わせて使用してもよい。
重合する単量体中における、Ｎ－置換マレイミド系単量体の割合は、全単量体総量１００質量％に対して好ましくは１～６０質量％、より好ましくは５～５０質量％、さらに好ましくは１０～４０質量％であるのがよい。Ｎ－置換マレイミド系単量体の量が多すぎると、溶媒やアルカリへの溶解性が低下したり、重合の際、析出又はゲル化し易くなったりする恐れがあり、一方、少なすぎると、耐熱性や基板との密着性が不充分となる恐れがある。
本発明の変性後の重合体溶液を得る際の単量体成分中におけるＮ-置換マレイミド系単量体の割合は、特に制限されないが、全単量体成分中１～５０質量％、好ましくは５～４５質量％、さらに好ましくは１０～４０質量％であるのがよい。
Ｎ-置換マレイミド系単量体の量が多すぎると、溶媒やアルカリへの溶解性が低下したり、重合の際、析出又はゲル化し易くなったりする恐れがあり、一方、少なすぎると、耐熱性が不充分となる恐れがある。

(In the formula, R ¹ represents a monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.)
In general formula (1), ^R1 is a monovalent hydrocarbon group having 1 to 30 carbon atoms, which may have a substituent. The monovalent hydrocarbon group preferably has 1 to 20 carbon atoms, and more preferably has 6 to 12 carbon atoms.
The hydrocarbon group may be a linear or cyclic aliphatic hydrocarbon group, or an aromatic hydrocarbon group.
The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group, but is preferably a saturated aliphatic hydrocarbon group.
Examples of the chain-like saturated aliphatic hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a sec-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a hexyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, a heptyl group, a 2-methylhexyl group, a 3-methylhexyl group, a 2,2-dimethylpentyl group, a 2,3-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3-ethylpentyl group, a 2,2,3-trimethyl ...4-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3-ethylpentyl group, a 2,4-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3-ethylpentyl group, a 2,4-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3 Examples of the alkyl group include linear or branched alkyl groups such as butyl, octyl, methylheptyl, dimethylhexyl, 2-ethylhexyl, 3-ethylhexyl, trimethylpentyl, 3-ethyl-2-methylpentyl, 2-ethyl-3-methylpentyl, 2,2,3,3-tetramethylbutyl, nonyl, methyloctyl, 3,7-dimethyloctyl, dimethylheptyl, 3-ethylheptyl, 4-ethylheptyl, trimethylhexyl, 3,3-diethylpentyl, decyl, undecyl, and dodecyl. Among these, alkyl groups having 1 to 30 carbon atoms are preferred, alkyl groups having 1 to 20 carbon atoms are more preferred, and alkyl groups having 1 to 12 carbon atoms are even more preferred.
Examples of cyclic aliphatic hydrocarbon groups include monocyclic alicyclic hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cyclododecyl group; and polycyclic alicyclic hydrocarbon groups such as a dicyclopentanyl group, a norbornyl group, and an adamantyl group.
Of these, a monocyclic or polycyclic alicyclic hydrocarbon group having 3 to 30 carbon atoms is preferable, a monocyclic or polycyclic alicyclic hydrocarbon group having 3 to 18 carbon atoms is more preferable, and a monocyclic alicyclic hydrocarbon group having 6 to 12 carbon atoms is even more preferable.
Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, a benzyl group, etc. Among these, an aromatic hydrocarbon group having 6 to 30 carbon atoms is preferable, and an aromatic hydrocarbon group having 6 to 12 carbon atoms is more preferable.
The hydrocarbon group may have a substituent, for example, an alkyl group, an aryl group, a hydroxyl group, a halogen atom, a carboxyl group, an alkoxy group, an aryloxy group, and the like.
Specific examples of the N-substituted maleimide monomer include N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-t-butylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, N-octylmaleimide, N-2-ethylhexylmaleimide, N-decylmaleimide, N-laurylmaleimide, N-tetradecylmaleimide, N-stearylmaleimide, N-2-decyltetradecylmaleimide, and N-phenylmaleimide. Examples of the maleimide include N-benzylmaleimide, N-naphthylmaleimide, N-chlorophenylmaleimide, N-methylphenylmaleimide, N-hydroxylethylmaleimide, N-hydroxylphenylmaleimide, N-methoxyphenylmaleimide, N-carboxyphenylmaleimide, N-nitrophenylmaleimide, N-tribromophenylmaleimide, N,N'-o-phenylenebismaleimide, N,N'-metaphenylenebismaleimide, and N,N'-paraphenylenebismaleimide. Among these, N-benzylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide are preferred from the viewpoint of copolymerizability, and N-benzylmaleimide is more preferred from the viewpoint of less coloration on heating.
Examples of the N-benzylmaleimide include benzylmaleimide; alkyl-substituted benzylmaleimides such as p-methylbenzylmaleimide and p-butylbenzylmaleimide; phenolic hydroxyl group-substituted benzylmaleimides such as p-hydroxybenzylmaleimide; and halogen-substituted benzylmaleimides such as o-chlorobenzylmaleimide, o-dichlorobenzylmaleimide and p-dichlorobenzylmaleimide.
The above N-substituted maleimide monomers may be used alone or in combination of two or more.
The proportion of the N-substituted maleimide monomer in the monomers to be polymerized is preferably 1 to 60% by mass, more preferably 5 to 50% by mass, and even more preferably 10 to 40% by mass, relative to 100% by mass of the total amount of all monomers. If the amount of the N-substituted maleimide monomer is too large, there is a risk that the solubility in solvents or alkalis will decrease, or that the polymer will be prone to precipitation or gelation during polymerization, whereas if the amount is too small, there is a risk that the heat resistance and adhesion to the substrate will be insufficient.
The ratio of the N-substituted maleimide monomer in the monomer components when obtaining the modified polymer solution of the present invention is not particularly limited, but is preferably 1 to 50 mass %, more preferably 5 to 45 mass %, and further preferably 10 to 40 mass % of the total monomer components.
If the amount of the N-substituted maleimide monomer is too large, there is a concern that the solubility in solvents or alkalis may decrease, or that precipitation or gelation may occur during polymerization. On the other hand, if the amount is too small, there is a concern that the heat resistance may be insufficient.

<Other monomers>
The monomer component for producing the precursor polymer may further contain another monomer (also referred to as monomer (c)) copolymerizable with the above-mentioned acid group-containing monomer and N-substituted maleimide monomer. The arrangement form of the monomer units in the polymer may be, for example, any of a random copolymer, an alternating copolymer, and a block copolymer. The monomer (c) is not particularly limited as long as it is copolymerizable with the above-mentioned monomers (a) and (b), and examples thereof include the following monomers. These may be used alone or in combination of two or more.
Hydroxyl group-containing monomers such as hydroxyalkyl (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2,3-hydroxypropyl (meth)acrylate;
Methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-amyl (meth)acrylate, s-amyl (meth)acrylate, t-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, ) (meth)acrylic acid esters such as 2-ethoxyethyl acrylate, tetrahydrofurfuryl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, 1,4-dioxaspiro[4,5]dec-2-yl methacrylic acid, (meth)acryloylmorpholine, 4-(meth)acryloyloxymethyl-2-methyl-2-ethyl-1,3-dioxolane, 4-(meth)acryloyloxymethyl-2-methyl-2-isobutyl-1,3-dioxolane, 4-(meth)acryloyloxymethyl-2-methyl-2-cyclohexyl-1,3-dioxolane, and 4-(meth)acryloyloxymethyl-2,2-dimethyl-1,3-dioxolane;
Cyclohexyl (meth)acrylate, cyclohexylmethyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, (3,4-epoxycyclohexyl)methyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, pentacyclo Alicyclic (meth)acrylates such as lopentadecanedimethanol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, norbornanedimethanol di(meth)acrylate, p-menthane-1,8-diol di(meth)acrylate, p-menthane-2,8-diol di(meth)acrylate, p-menthane-3,8-diol di(meth)acrylate, and bicyclo[2.2.2]-octane-1-methyl-4-isopropyl-5,6-dimethylol di(meth)acrylate;
(meth)acrylates containing an aromatic ring, such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate;
Epoxy group-containing monomers other than glycidyl (meth)acrylate, such as β-methyl glycidyl (meth)acrylate, β-ethyl glycidyl (meth)acrylate, vinylbenzyl glycidyl ether, allyl glycidyl ether, (3,4-epoxycyclohexyl)methyl (meth)acrylate, and vinylcyclohexene oxide;
(Meth)acrylamides such as N,N-dimethyl(meth)acrylamide and N-methylol(meth)acrylamide; macromonomers having a (meth)acryloyl group at one end of the polymer molecular chain, such as polystyrene, polymethyl(meth)acrylate, polyethylene oxide, polypropylene oxide, polysiloxane, polycaprolactone, and polycaprolactam; conjugated dienes such as 1,3-butadiene, isoprene, and chloroprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl ... vinyl ethers such as butyl vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, 2-hydroxyethyl vinyl ether, and 4-hydroxybutyl vinyl ether; N-vinyl compounds such as N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylimidazole, N-vinylmorpholine, and N-vinylacetamide; aromatic vinyls such as styrene, vinyltoluene, α-methylstyrene, xylene, methoxystyrene, and ethoxystyrene; unsaturated isocyanates such as isocyanatoethyl (meth)acrylate and allyl isocyanate; and the like.

Among other monomers, it is preferable to copolymerize an alicyclic hydrocarbon group-containing monomer, particularly an alicyclic (meth)acrylate, from the viewpoint of solubility. The alicyclic hydrocarbon group-containing monomer will be described below.
The alicyclic hydrocarbon group-containing monomer includes a monomer having an alicyclic hydrocarbon group and a polymerizable double bond.
The alicyclic hydrocarbon group preferably includes an alicyclic hydrocarbon group having 3 to 12 carbon atoms, more preferably 7 to 10 carbon atoms, and specifically includes monocyclic hydrocarbon groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, cycloheptyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, etc.; and polycyclic hydrocarbon groups such as dicyclopentanyl, dicyclopentenyl, tricyclodecanyl, adamantyl, isobornyl, etc. Among these, the alicyclic hydrocarbon group is preferably a polycyclic hydrocarbon group, more preferably dicyclopentanyl, dicyclopentenyl, isobornyl, and particularly preferably dicyclopentanyl, in terms of exhibiting even more excellent solubility and heat coloration resistance.
Examples of the polymerizable double bond include a (meth)acryloyl group, a vinyl group, an allyl group, and a methallyl group. The monomer having the polymerizable double bond is preferably a (meth)acrylate monomer. That is, the alicyclic hydrocarbon group-containing monomer is preferably an alicyclic hydrocarbon group-containing (meth)acrylate monomer.
Specific examples of the alicyclic hydrocarbon group-containing monomer include the alicyclic (meth)acrylates described above. Among them, the alicyclic hydrocarbon group-containing monomer is more preferably dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, or isobornyl (meth)acrylate, more preferably dicyclopentanyl (meth)acrylate, and particularly preferably dicyclopentanyl methacrylate. The alicyclic hydrocarbon group-containing monomer may contain only one of the above-mentioned monomers, or may contain two or more of the above-mentioned monomers.
The contents of the above monomers (a), (b) and (c) can be appropriately set depending on the purpose and application of the polymer to be obtained.
The content of the above monomer (a) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to 100% by mass of the total monomer components, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.
The content of the above monomer (b) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the total monomer components, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less.
The content of the above monomer (c) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 30% by mass or more, relative to 100% by mass of the total monomer components, and is preferably 94% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less.
When two or more kinds of monomers (a), (b) and (c) are contained, the content of each of the monomers (a), (b) and (c) is the total amount thereof.

[Polymerization initiator]
The polymerization initiator used in the method for producing a polymer solution of the present invention is not particularly limited, and examples thereof include organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, and t-butylperoxy-2-ethylhexanoate; azo compounds such as 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobis(2-methylpropionate); and the like. These polymerization initiators may be used alone or in combination of two or more. The amount of the initiator used may be appropriately set depending on the combination of monomers used, the reaction conditions, the molecular weight of the target polymer, and the like, and is not particularly limited. However, in terms of reducing the concentration of oligomers (e.g., molecular weight of 500 or less) and obtaining a polymer with a narrow molecular weight distribution, the amount of the initiator used is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and less than 3% by mass, relative to the total monomer components (total amount of all monomers: 100% by mass).
[Chain transfer agent]
When polymerizing the monomer components, a chain transfer agent that is commonly used may be added as necessary to adjust the molecular weight. Examples of the chain transfer agent include mercaptan-based chain transfer agents such as n-dodecyl mercaptan, mercaptopropionic acid, mercaptoacetic acid, and methyl mercaptoacetate, and α-methylstyrene dimer. However, n-dodecyl mercaptan and mercaptopropionic acid are preferable because they have a high chain transfer effect, can reduce residual monomers, and are easily available. When using a chain transfer agent, the amount of the chain transfer agent used may be appropriately set depending on the combination of monomers used, reaction conditions, and the molecular weight of the target polymer, and is not particularly limited. However, it is preferable to use 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, based on the total monomer components (total amount of all monomers: 100% by mass) in order to obtain a polymer having a weight average molecular weight of several thousand to several tens of thousands without gelation.

[solvent]
When the monomers are polymerized in the presence of a solvent, the content of the carbonate-based solvent used in the present invention is 10 to 100% by mass, preferably 10 to 90% by mass, more preferably 10 to 80% by mass, and particularly preferably 10 to 70% by mass, based on 100% by mass of the total amount of the solvent.
If the content of the monomer (b) is less than 10% by mass, it may be difficult to dissolve the monomer (b) when the content of the monomer (b) is increased. In addition, if the content of the carbonate solvent is 100% by mass, the adjustment range of the monomer composition is widened in terms of solubility, which is preferable, but if it is desired to increase the polymerization temperature, a mixed solvent with a solvent having a higher boiling point than the carbonate solvent used is preferable.
In addition, when the monomer solution containing an N-substituted maleimide monomer is dropped into the reaction tank, the carbonate solvent is contained in an amount of preferably 20 to 90 mass%, particularly preferably 30 to 90 mass%, and most preferably 30 to 80 mass%, relative to 100 mass% of the total solvent amount of the monomer solution.
The carbonate-based solvent and/or other solvent preferably has a boiling point at 1 atm of 80° C. or higher and 250° C. or lower, more preferably 85° C. or higher and 200° C. or lower.
As the solvent other than the carbonate-based solvent, a solvent used in a normal radical polymerization reaction can be used. In the present invention, an ester-based solvent or an alcohol-based solvent that is generally used as a solvent for a resist composition is preferable. Specifically, including the carbonate-based solvent, the following solvents can be mentioned.
<Carbonate-based solvent>
Examples of carbonate solvents include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, divinyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, di-sec-butyl carbonate, dihexadecyl carbonate, di-2-ethylhexyl carbonate, diphenyl carbonate, dicyclohexyl carbonate, etc. Among these, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and diphenyl carbonate are preferred, and dialkyl carbonates having 1 to 6 carbon atoms such as dimethyl carbonate and diethyl carbonate are particularly preferred.
<Ester Solvents>
Examples of ester-based solvents include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate (propylene glycol methyl ether acetate), propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl esters of glycol monoethers such as ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, and 3-methoxybutyl acetate; alkyl esters such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl lactate, ethyl lactate, butyl lactate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl acetoacetate, and ethyl acetoacetate; and the like.
<Alcohol-based solvent>
An alcohol-based solvent means a saturated alcohol, that is, a compound that does not have an unsaturated double bond and contains at least one hydroxyl group.
Specifically, preferred are, for example, monoalcohols such as methanol, ethanol, isopropanol, n-butanol, and s-butanol, polyhydric alcohols such as ethylene glycol and propylene glycol, glycol monoethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, and 3-methoxybutanol, etc. More preferred are ethylene glycol, diethylene glycol, and propylene glycol monomethyl ether.
<Other Solvents>
Examples of ether solvents include cyclic ethers such as tetrahydrofuran and dioxane; glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol dimethyl ether, and propylene glycol diethyl ether; and the like.
Examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of aromatic hydrocarbon-based solvents include benzene, toluene, xylene, and ethylbenzene. Examples of aliphatic hydrocarbon-based solvents include hexane, cyclohexane, and octane. Examples of amide-based solvents include dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.
These solvents may be used alone or in combination of two or more kinds of carbonate-based solvents. In addition, a solvent other than the carbonate-based solvent may be used in a range of less than 10% by mass relative to the total amount of the solvent, 100% by mass. In the case of a mixed solvent, a solvent other than the carbonate-based solvent may be used in a range of less than 50% by mass, or even less than 30% by mass. For example, an ester-based solvent such as propylene glycol monomethyl ether acetate, or a mixed solvent with an alcohol-based solvent such as propylene glycol monomethyl ether or isopropanol, may be mentioned as a preferred form.

[Method for producing polymer solution (polymerization step)]
Examples of the method for polymerizing the monomer used in the present invention include solution polymerization and emulsion polymerization. Among them, solution polymerization is preferred because it is industrially advantageous and easy to adjust the structure such as molecular weight. In addition, the polymerization mechanism of the above monomer can be a polymerization method based on a mechanism such as radical polymerization, anionic polymerization, cationic polymerization, and coordination polymerization, but a polymerization method based on a radical polymerization mechanism is preferred because it is industrially advantageous. The polymerization initiation method in the above polymerization reaction can be performed by supplying the energy required for polymerization initiation to the monomer component from an active energy source such as heat, electromagnetic waves (e.g., infrared rays, ultraviolet rays, X-rays, etc.), and electron beams, and further, by using a polymerization initiator in combination, the energy required for polymerization initiation can be greatly reduced and the reaction can be easily controlled, which is preferred. The molecular weight of the polymer obtained by polymerizing the above monomer can be controlled by adjusting the amount and type of polymerization initiator, the polymerization temperature, and the type and amount of chain transfer agent. When the above monomer is polymerized by solution polymerization, the solvent used for polymerization should be inactive to the polymerization reaction. In the present invention, an efficient production method using a carbonate-based solvent as the polymerization solvent has been found. The present inventors have found a production method in which the solubility of the monomer is improved by containing a carbonate-based solvent in an amount of 20 to 90% by mass, preferably 30 to 90% by mass, and particularly preferably 30 to 80% by mass, relative to 100% by mass of the total solvent amount in the monomer solution to be dropped into the reaction vessel.

The volume of the reaction tank (reaction vessel) used in the present invention is 0.5 to 10 liters on a laboratory scale, and usually 0.1 to 50 ^m3 on an industrial production scale. It is preferably 0.2 to 45 ^m3 , and more preferably 0.3 to 40 ^m3 . The material of the inside of the reaction tank is not particularly limited, and is, for example, made of stainless steel, preferably made of SUS such as SUS304, SUS316, and SUS316L, from the viewpoint of corrosion resistance. In addition, it is desirable that the inside of the reaction tank is glass-lined or the like to be inert to the reaction raw materials and reaction products.

The volume of the polymer solution finally obtained is preferably controlled to 40 to 80% by volume of the volume of the reaction tank, and more preferably to 50 to 70% by volume. If the volume exceeds 80% by volume, the proportion of the polymerization reaction solution becomes high, which may lead to difficulties in polymerization control and safety, such as dealing with a sudden temperature rise. In addition, the solids concentration (polymerization concentration) of the finally obtained polymer solution is preferably 10 to 70% by mass, and more preferably 30 to 50% by mass.
In addition, it is preferable to reduce the oxygen concentration in the gas phase, which is the upper part of the polymer solution, by replacing with an inert gas (preferably nitrogen replacement). For example, a method of bubbling an inert gas (nitrogen, helium, argon, carbon dioxide, etc.) into the polymerization reaction solution, or a method of blowing an inert gas into the reaction system to reduce the oxygen in the gas phase can be mentioned. A specific method of bubbling nitrogen can be a method of inserting a nitrogen line equipped with a porous filter into the reaction liquid (preferably the lower part) and flowing nitrogen while stirring the reaction liquid. A method of blowing an inert gas into the reaction system can be a method of blowing in an inert gas by providing a nitrogen inlet at the top of the reaction tank. In that case, an exhaust port is provided. As the inert gas, nitrogen is preferable because it is the gas most abundant in the atmosphere, is extremely inert at normal temperature and normal pressure, and is inexpensive compared to rare gases such as argon. The amount of nitrogen introduced is, for example, preferably at a flow rate of 0.1 (ml/min) to 300 (ml/min) on a laboratory scale (0.5 to 5 liters), and more preferably at a flow rate of 1 (ml/min) to 150 (ml/min). On an industrial production scale (0.5 to 5 ^m3 ), it is preferably at a flow rate of 0.1 (l/min) to 300 (l/min), and more preferably at a flow rate of 1 (l/min) to 150 (l/min). As a result, the oxygen concentration in the gas phase can be controlled to 5% by volume or less, and preferably 3% by volume or less.

The shape of the reaction tank (reaction vessel) used is not particularly limited, and may be, for example, polygonal or cylindrical, but cylindrical is preferred from the viewpoints of stirring effect, ease of handling, versatility, etc. In addition, a baffle may or may not be provided, but the provision of a baffle can improve the uniformity of the polymerization reaction solution. The agitator is composed of a power source such as an electric motor, a rotating shaft, an agitator, etc., but the shape of the agitator blade is not important. Examples of the agitator include a disk turbine, a fan turbine, a curved fan turbine, an arrowhead turbine, a multi-stage fan turbine, a Pfaudle blade, a Bull Margin type, an angled blade, a propeller type, a multi-stage blade, an anchor type, a gate type, a double ribbon blade, a screw blade, a Max Blend blade, etc. The agitation power during the polymerization reaction (industrial production scale) is 0.1 to 4.0 kW/m ³ , preferably 0.1 to 3.0 kW/m ³ , and more preferably 0.2 to 2.0 kW/m ³ . That is, when the stirring power is less than 0.1 kW/m ³ , the uniformity of the polymerization reaction solution tends to decrease. On the other hand, when the stirring power exceeds 4.0 kW/m ³ , the polymerization reaction solution may splash on the inner wall surface of the reaction tank (reaction vessel), and may react on the inner wall surface of the reaction tank and gel. In addition, the pressure inside the vessel during the polymerization reaction may or may not be controlled by pressurization or reduction. Unless special operations are performed or special raw materials are used, the polymerization reaction may usually be carried out at normal pressure. The method of feeding the monomer during the polymerization reaction is not particularly limited, and a part of the monomer may be initially charged and the rest may be dripped, or the entire amount may be dripped. However, from the viewpoint of controlling the amount of heat generated, it is preferable to initially charge a part of the monomer and drip the rest, or to drip the entire amount. In this specification, charging the monomer into the reaction tank in advance (charging the monomer into the reaction tank before polymerization) is also referred to as initial charging.

Regarding the polymerization conditions, the polymerization temperature may be set appropriately depending on the type and amount of the monomer used, the type and amount of the polymerization initiator, etc., but is preferably at least 20°C lower than the boiling point of the polymerization solvent. In the case of a mixed solvent, it is preferably at least 20°C lower than the boiling point of the solvent with the highest boiling point. For example, 50 to 150°C is preferred, and 70 to 120°C is more preferred. The polymerization time can also be set appropriately, but is preferably 1 to 8 hours, and more preferably 2 to 6 hours.

[Step of adding double bonds to polymer]
In the method for producing an alkali-soluble polymer solution of the present invention, it is also preferable to include a step (also called a double bond addition step or a modification step) of reacting a compound having a functional group capable of bonding to an acid group and a polymerizable double bond with the polymer (also called a base polymer) obtained in the polymerization step (after the aging step if there is one). This makes it possible to obtain an alkali-soluble polymer as a polymer having a double bond in the side chain (also called a side chain double bond-containing polymer), and it is possible to give a cured product having superior adhesion to a substrate or the like and superior surface hardness. In this way, it is also preferable that the method for producing a polymer solution of the present invention is in a form including the polymerization step and the double bond addition step. In addition, in order to use the polymer solution in a resist composition, it is also preferable to replace the solvent of the polymer solution after the polymerization step or the double bond addition step with a solvent for a resist. The solvent to be replaced is preferably at least one solvent selected from ester solvents, ketone solvents, ether solvents, and alcohol solvents.

In the compound having a functional group and a polymerizable double bond that can be bonded to the acid group, the polymerizable double bond can be, for example, a (meth)acryloyl group, a vinyl group, an allyl group, a methallyl group, etc., and the compound preferably has one or more of these. Among them, in terms of reactivity, a (meth)acryloyl group is preferred. In addition, as the functional group that can be bonded to the acid group, for example, a hydroxyl group, an epoxy group, an oxetanyl group, an isocyanate group, etc., and the compound preferably has one or more of these. Among them, in terms of the speed of the modification reaction, heat resistance, and dispersibility, an epoxy group (including a glycidyl group) is preferred.
Examples of the compound having a functional group capable of bonding to an acid group and a polymerizable double bond include glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, β-methyl glycidyl (meth)acrylate, β-ethyl glycidyl (meth)acrylate, vinylbenzyl glycidyl ether, allyl glycidyl ether, (3,4-epoxycyclohexyl)methyl (meth)acrylate, vinylcyclohexene oxide, etc., and one or more of these can be used. Among these, it is preferable to use a compound (monomer) having an epoxy group and a (meth)acryloyl group.

A particularly preferred embodiment is to introduce a side chain double bond by reacting a polymer (base polymer) in a polymer solution with an epoxy group-containing monomer.
The amount of the compound having a functional group and a polymerizable double bond capable of bonding with the acid group is preferably 1 to 170 parts by mass, for example, relative to 100 parts by mass of the base polymer component (total amount of monomer components constituting the base polymer). More preferably, it is 3 to 150 parts by mass, and even more preferably, it is 5 to 120 parts by mass. In the step of reacting the base polymer with a compound having a functional group and a polymerizable double bond capable of bonding with an acid group, for example, a method in which the amount of the acid group (preferably a carboxyl group) of the base polymer component is in excess of the amount of the compound having a functional group and a polymerizable double bond capable of bonding with the acid group; a method in which the base polymer component is reacted with a compound having a functional group and a polymerizable double bond capable of bonding with an acid group, and then a compound having a polybasic acid anhydride group is further reacted; or the like is preferably adopted. This makes it possible to suitably obtain a side chain double bond-containing polymer. The double bond equivalent of the side chain double bond-containing polymer is preferably 300 to 2000 (g/equivalent), more preferably 400 to 2000 (g/equivalent). By controlling the temperature within the above range, it is possible to achieve both curability and developability. In addition, the glass transition temperature (Tg) of the side chain double bond-containing polymer is preferably 120° C. or lower. This improves adhesion. More preferably, it is 100° C. or lower. The lower limit is not particularly limited, but from the viewpoint of heat resistance, it is preferably −10° C. or higher. More preferably, it is 0° C. or higher.
The step of reacting the base polymer (preferably a polymer having a carboxyl group) with a compound having a functional group capable of bonding to an acid group and a polymerizable double bond is preferably carried out at a temperature range of 50 to 160°C in order to ensure a good reaction rate and prevent gelation. The temperature is more preferably 70 to 140°C, and even more preferably 90 to 130°C. In order to improve the reaction rate, a basic catalyst or an acid catalyst that is commonly used for esterification or transesterification can be used as a catalyst. Among them, it is preferable to use a basic catalyst since side reactions are reduced.

Examples of the basic catalyst include tertiary amines such as dimethylbenzylamine, triethylamine, tri-n-octylamine, and tetramethylethylenediamine; quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, tetrabutylammonium bromide, and n-dodecyltrimethylammonium chloride; urea compounds such as tetramethylurea; alkyl guanidines such as tetramethylguanidine; amide compounds such as dimethylformamide and dimethylacetamide; tertiary phosphines such as triphenylphosphine and tributylphosphine; quaternary phosphonium salts such as tetraphenylphosphonium bromide and benzyltriphenylphosphonium bromide; and the like. One or more of these can be used. Among these, dimethylbenzylamine, triethylamine, tetramethylurea, and triphenylphosphine are preferred in terms of reactivity, ease of handling, and halogen-free properties.

The amount of the catalyst used is preferably 0.01 to 5 parts by mass per 100 parts by mass of the total amount of the base polymer component (the monomer component constituting the base polymer) and the compound having a functional group capable of bonding to an acid group and a polymerizable double bond group. More preferably, it is 0.1 to 3 parts by mass.

The step of reacting the base polymer with a compound having a functional group capable of bonding to an acid group and a polymerizable double bond is also preferably carried out in the presence of a molecular oxygen-containing gas with the addition of a polymerization inhibitor to prevent gelation. As the molecular oxygen-containing gas, air or oxygen gas diluted with an inert gas such as nitrogen is usually used and blown into the reaction vessel.

As the polymerization inhibitor, a polymerization inhibitor for a radical polymerizable monomer that is normally used can be used, for example, hydroquinone, methylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, methoquinone, 6-t-butyl-2,4-xylenol, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methoxyphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), and other phenol-based inhibitors, organic acid copper salts, phenothiazine, and the like can be mentioned, and one or more of these can be used. Among them, phenol-based inhibitors are preferred in terms of low coloration and polymerization inhibition ability, and 2,2'-methylenebis(4-methyl-6-t-butylphenol), methoquinone, 6-t-butyl-2,4-xylenol, and 2,6-di-t-butylphenol are more preferred in terms of availability and economy.

The amount of the polymerization inhibitor used is preferably 0.001 to 1 part by mass per 100 parts by mass of the total amount of the base polymer component and the compound having a functional group capable of bonding to an acid group and a polymerizable double bond, from the viewpoints of ensuring a sufficient polymerization inhibition effect and curing properties when formed into a curable resin composition (resist composition). More preferably, it is 0.01 to 0.5 parts by mass.

Examples of the compound having a polybasic acid anhydride group include succinic anhydride, dodecenylsuccinic acid, pentadecenylsuccinic acid, octadecenylsuccinic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, maleic anhydride, itaconic anhydride, phthalic anhydride, glutaric anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. One or more of these may be used.
[Polymer solution (composition containing polymer and solvent)]
The present invention relates to a polymer solution (preferably an alkali-soluble polymer solution) comprising a polymer having structural units derived from an acid group-containing monomer and structural units derived from an N-substituted maleimide monomer, and a solvent, wherein the polymer contains 5 to 40 mass% of structural units derived from an acid group-containing monomer and 1 to 60 mass% of structural units derived from an N-substituted maleimide monomer, relative to 100 mass% of the total amount of structural units, and the carbonate solvent is contained in an amount of 10 to 100 mass% relative to 100 mass% of the total amount of the solvent.
The constituent units derived from the acid group-containing monomer (monomer (a)) and the constituent units derived from the N-substituted maleimide monomer (monomer (b)), which are essential components, and the solvent are the constituent units derived from the monomers and the solvent in the above-mentioned method for producing a polymer solution. The other monomers (monomer (c)) and the solvents, which are optional components, are also as described above.
In addition, the preferred ranges of the values of the structural units and the carbonate-based solvent are the same as those in the above-mentioned method for producing the polymer solution.

The amount of the structural units derived from monomer (a) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to 100% by mass of the total amount of the structural units, and is preferably 40% by mass or less, and more preferably 30% by mass or less.
The amount of the constituent units derived from the monomer (b) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the total amount of the constituent units, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less.
The amount of the constituent units derived from the monomer (c) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 30% by mass or more, relative to 100% by mass of the total amount of the constituent units, and is preferably 94% by mass or less, more preferably 80% by mass or less, and even more preferably 50% by mass or less.
The content of the carbonate-based solvent is preferably 10 to 90 mass%, more preferably 10 to 80 mass%, particularly preferably 10 to 70 mass%, and most preferably 10 to 50 mass%, relative to 100 mass% of the total amount of the solvent.
By adjusting the content within the above numerical range, a transparent and uniform alkali-soluble polymer solution (a composition of the alkali-soluble polymer and the solvent) can be obtained.
The alkali-soluble polymer contained in the alkali-soluble polymer solution of the preferred embodiment of the present invention preferably has an acid value of 30 to 300 mgKOH/g, and particularly preferably 40 to 160 mgKOH/g. When the acid value is in this range, sufficient alkali solubility is exhibited, and therefore, for example, when a resist composition containing this alkali-soluble polymer is used as an alkali development type resist, particularly good plate making properties can be exhibited.
The polymer may have a double bond added to the side chain. When a double bond is added, the acid value of the base polymer (precursor polymer) before the double bond is added (before modification) is preferably 250 mgKOH/g or more and 350 mgKOH/g or less.
By setting the acid value in the above range, the acid value of the final polymer after modification can be designed to be high, and the amount of double bonds that can be introduced can be increased. As a result, excellent development speed and curability can be achieved at the same time. The acid value of the alkali-soluble polymer is more preferably 40 mgKOH/g or more, more preferably 270 mgKOH/g or less, even more preferably 250 mgKOH/g or less, particularly preferably 230 mgKOH/g or less, even more preferably 210 mgKOH/g or less, and most preferably 160 mgKOH/g or less.

The acid value of the polymer can be determined, for example, by measuring the acid value of the polymer solution using an automatic titrator (product name: COM-555, manufactured by Hiranuma Sangyo Co., Ltd.) using a 0.1 normal (N) KOH aqueous solution as a titrant, and calculating the acid value per 1 g of polymer (mg KOH/g) from the acid value of the polymer solution and the solid content concentration of the polymer solution. Here, the solid content of the polymer solution can be determined as follows.
Approximately 0.3 g of the polymer solution is weighed out into an aluminum cup, and approximately 1 g of acetone is added to dissolve it, and then the solution is naturally dried at room temperature. After that, the solution is dried at 140°C for 3 hours using a hot air dryer (product name: PHH-101, manufactured by Espec Corporation), and then allowed to cool in a desiccator and its weight is measured. The weight of the solid content (resin) of the polymer solution is calculated from the weight loss.
The alkali-soluble polymer also preferably has a weight average molecular weight of 2,000 to 250,000. With the molecular weight in this range, better plate-making properties can be obtained. The weight average molecular weight is more preferably 3,000 to 100,000, even more preferably 4,000 to 50,000, particularly preferably 4,000 to 40,000, and most preferably 4,000 to 30,000.

The weight average molecular weight of the polymer can be determined, for example, by using GPC (gel permeation chromatography; HLC-8220GPC, manufactured by Tosoh Corporation) with THF as an eluent and a TSKgel Super HZM-M (manufactured by Tosoh Corporation) column in terms of standard polystyrene.
The present invention also provides a polymer (preferably an alkali-soluble polymer) characterized in that a side chain double bond is introduced by reacting a compound having a functional group capable of bonding to an acid group and a polymerizable double bond with the polymer contained in the above-mentioned polymer solution.

In the case of an alkali-soluble polymer containing a side chain double bond by the above-mentioned double bond addition process of a polymer, the double bond equivalent is preferably 300 to 2000 (g/equivalent), more preferably 400 to 800 (g/equivalent). By controlling it within the above range, both curability and developability can be achieved.
The double bond equivalent is the mass of the solid content of the polymer solution per 1 mol of double bonds of the copolymer. The mass of the solid content of the polymer solution is the sum of the mass of the monomer components constituting the copolymer and the mass of the polymerization inhibitor. The double bond equivalent can be obtained by dividing the mass (g) of the polymer solid content of the polymer solution by the amount of double bonds (mol) of the polymer. The amount of double bonds of the copolymer can be obtained from the amount of the monomer containing an acid group and the compound having a polymerizable double bond used in the polymerization. It can also be measured by titration and various analyses such as elemental analysis, NMR, IR, and differential scanning calorimetry.
The glass transition temperature (Tg) of the alkali-soluble polymer is preferably 120° C. or lower. This improves adhesion. More preferably, it is 100° C. or lower. There is no particular restriction on the lower limit, but from the viewpoint of heat resistance, it is preferably −10° C. or higher. More preferably, it is 0° C. or higher.

The glass transition temperature (Tg) can be measured, for example, by the following method. The copolymer solution is applied to a 5 cm square glass substrate, spin-coated on the glass substrate, and dried at room temperature under reduced pressure for 4 hours to form a thin film with a film mass of 30 mg or less, thereby removing volatile components and obtaining a solid content. The obtained solid content is measured using a DSC (differential scanning calorimeter, measuring device: Netsch DSC3500) in a nitrogen stream at a heating rate of 10°C/min in accordance with JIS-K7121.
A curable resin composition (resist composition) containing the above-mentioned polymer, a photopolymerization initiator, and a polymerizable compound also constitutes one embodiment of the present invention.

[Resist Composition]
The alkali-soluble polymer suitably obtained from the polymer solution or the method for producing the polymer solution of the present invention is excellent in various physical properties such as heat resistance, transparency, adhesion to a substrate, developability, and photosensitivity, and is also excellent in image forming properties and surface smoothness, and can give a cured product (cured film) that is free of residues or background stains in unexposed areas and has a sufficiently reduced film thickness. Therefore, the alkali-soluble polymer is preferably used for various optical members and electric/electronic devices, such as colored layers, black matrices, photospacers, black column spacers, inks, printing plates, printed wiring boards, semiconductor elements, and photoresists of color filters used in liquid crystal display devices and solid-state imaging devices. Among them, it is preferable to use it as a component contained in a resist composition used for these applications. The form in which the alkali-soluble polymer is used in a resist composition (curable resin composition) in this way is also one of the suitable forms of the present invention.
The resist composition preferably contains the alkali-soluble polymer and a polymerizable compound (preferably a polyfunctional polymerizable monomer), and particularly preferably further contains a photopolymerization initiator.
[Polymerizable compound]
The polymerizable compound is also called a polymerizable monomer, and is a low molecular weight compound having a polymerizable unsaturated bond (also called a polymerizable unsaturated group) that can be polymerized by irradiation with active energy rays such as free radicals, electromagnetic waves (e.g., infrared rays, ultraviolet rays, X-rays, etc.), electron beams, etc. Examples of the polymerizable compound include a monofunctional compound having one polymerizable unsaturated group in the molecule and a polyfunctional compound having two or more polymerizable unsaturated groups.

Examples of the monofunctional polymerizable monomer include, among the compounds exemplified as other monomers preferably contained in the monomer component of the (meth)acrylate polymer, N-substituted maleimides and (meth)acrylic acid esters; (meth)acrylamides; unsaturated monocarboxylic acids; unsaturated polycarboxylic acids; unsaturated monocarboxylic acids in which the unsaturated group and the carboxyl group are chain-extended; unsaturated acid anhydrides; aromatic vinyls; conjugated dienes; vinyl esters; vinyl ethers; N-vinyl compounds; unsaturated isocyanates; and the like.

Examples of the polyfunctional polymerizable monomer include the following compounds.
Bifunctional (meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, bisphenol A alkylene oxide di(meth)acrylate, and bisphenol F alkylene oxide di(meth)acrylate. acrylate compounds; trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, ethylenediaminetetraacetate ... Ethylene oxide-added trimethylolpropane tri(meth)acrylate, Ethylene oxide-added ditrimethylolpropane tetra(meth)acrylate, Ethylene oxide-added pentaerythritol tetra(meth)acrylate, Ethylene oxide-added dipentaerythritol hexa(meth)acrylate, Propylene oxide-added trimethylolpropane tri(meth)acrylate, Propylene oxide-added ditrimethylolpropane tetra(meth)acrylate, Propylene oxide-added pentaerythritol hexa(meth)acrylate Polyfunctional (meth)acrylate compounds having three or more functionalities, such as erythritol tetra(meth)acrylate, propylene oxide-added dipentaerythritol hexa(meth)acrylate, ε-caprolactone-added trimethylolpropane tri(meth)acrylate, ε-caprolactone-added ditrimethylolpropane tetra(meth)acrylate, ε-caprolactone-added pentaerythritol tetra(meth)acrylate, and ε-caprolactone-added dipentaerythritol hexa(meth)acrylate;
Ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether polyfunctional vinyl ethers such as dipentaerythritol vinyl ether and ethylene oxide-added dipentaerythritol hexavinyl ether; vinyl ether group-containing (meth)acrylic acid esters such as 2-vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 5-vinyloxypentyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, 4-vinyloxymethylcyclohexylmethyl (meth)acrylate, p-vinyloxymethylphenylmethyl (meth)acrylate, 2-(vinyloxyethoxy)ethyl (meth)acrylate, and 2-(vinyloxyethoxyethoxyethoxy)ethyl (meth)acrylate;
Ethylene glycol diallyl ether, diethylene glycol diallyl ether, polyethylene glycol diallyl ether, propylene glycol diallyl ether, butylene glycol diallyl ether, hexanediol diallyl ether, bisphenol A alkylene oxide diallyl ether, bisphenol F alkylene oxide diallyl ether, trimethylolpropane triallyl ether, ditrimethylolpropane tetraallyl ether, glycerin triallyl ether, pentaerythritol tetraallyl ether, dipentaerythritol pentaallyl ether, dipentaerythritol hexaallyl ether, ethylene oxide-added trimethylolpropane triallyl ether, ethylene oxide-added ditrimethylolpropane tetraallyl ether, ethylene oxide-added pentaerythritol tetraallyl ether, ethylene oxide-added dipentaerythritol hexaallyl ether polyfunctional allyl ethers such as allyl ether; allyl group-containing (meth)acrylic acid esters such as allyl (meth)acrylate; polyfunctional (meth)acryloyl group-containing isocyanurates such as tri(acryloyloxyethyl)isocyanurate, tri(methacryloyloxyethyl)isocyanurate, alkylene oxide-added tri(acryloyloxyethyl)isocyanurate, and alkylene oxide-added tri(methacryloyloxyethyl)isocyanurate; polyfunctional allyl group-containing isocyanurates such as triallyl isocyanurate; polyfunctional urethane (meth)acrylates obtained by reacting polyfunctional isocyanates such as tolylene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate with hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; polyfunctional aromatic vinyls such as divinylbenzene; and the like.

Among the above polymerizable compounds, it is preferable to use a polyfunctional polymerizable compound from the viewpoint of further enhancing the curability of the resist composition. When a polyfunctional polymerizable compound is used as the polymerizable compound, the functionality is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. In addition, from the viewpoint of further suppressing cure shrinkage, the functionality is preferably 10 or less, more preferably 8 or less.
The molecular weight of the polymerizable compound is not particularly limited, but is preferably, for example, 2000 or less from the viewpoint of handling.

When a polyfunctional polymerizable compound is used as the polymerizable compound, it is preferable to use a compound having a (meth)acryloyl group, such as a polyfunctional (meth)acrylate compound, a polyfunctional urethane (meth)acrylate compound, or a (meth)acryloyl group-containing isocyanurate compound, from the viewpoints of reactivity, economy, availability, etc. Among the polymerizable compounds, it is preferable to use a compound having a (meth)acryloyl group, such as a polyfunctional (meth)acrylate compound, a polyfunctional urethane (meth)acrylate compound, or a (meth)acryloyl group-containing isocyanurate compound. A polyfunctional (meth)acrylate compound is more preferable, as this makes the resist composition more excellent in photosensitivity and curability, and makes it possible to obtain a cured product with even higher hardness and transparency. It is even more preferable to use a polyfunctional (meth)acrylate compound having three or more functionalities.

The content ratio of the polymerizable compound may be appropriately set depending on the type of polymerizable compound or polymer used, as well as the purpose and application, but from the viewpoint of superior developability and plate making property, it is preferably 2% by mass or more and suitably 85% by mass or less relative to 100% by mass of the total solid content of the resist composition. The lower limit is more preferably 5% by mass or more, even more preferably 8% by mass or more, particularly preferably 10% by mass or more, and the upper limit is more preferably 83% by mass or less, even more preferably 80% by mass or less, particularly preferably 78% by mass or less, and most preferably 75% by mass or less.
[Photopolymerization initiator]
The photopolymerization initiator is preferably a radically polymerizable photopolymerization initiator. The radically polymerizable photopolymerization initiator generates polymerization initiation radicals by irradiation with active energy rays such as electromagnetic waves and electron beams, and one or more of those usually used can be used. In addition, one or more of photosensitizers and photoradical polymerization promoters may be used in combination as necessary. A photosensitizer and/or a photoradical polymerization promoter may or may not be used together with the photopolymerization initiator. When used in combination, the sensitivity and curability are further improved.
Specific examples of the photopolymerization initiator include the following compounds.
Alkylphenone compounds such as 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone;
Benzophenone-based compounds such as benzophenone, 4,4'-bis(dimethylamino)benzophenone, and 2-carboxybenzophenone; benzoin-based compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; thioxanthone-based compounds such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, and 2,4-diethylthioxanthone;
Halomethylated triazine compounds such as 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-ethoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, and 2-(4-ethoxycarbonylnaphthyl)-4,6-bis(trichloromethyl)-s-triazine; halomethylated oxadiazole compounds such as 2-trichloromethyl-5-[β-(2'-benzofuryl)vinyl]-1,3,4-oxadiazole, 4-oxadiazole, and 2-trichloromethyl-5-furyl-1,3,4-oxadiazole; 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole; biimidazole compounds such as 2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole and 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl) )-9H-carbazol-3-yl]-, 1-(O-acetyloxime) and other oxime ester compounds; bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium and other titanocene compounds; p-dimethylaminobenzoic acid, p-diethylaminobenzoic acid and other benzoic acid ester compounds; 9-phenylacridine and other acridine compounds.
Examples of the photosensitizer or photoradical polymerization accelerator that may be used in combination with the photopolymerization initiator include dye compounds such as xanthene dyes, coumarin dyes, 3-ketocoumarin compounds, and pyrromethene dyes; dialkylaminobenzene compounds such as ethyl 4-dimethylaminobenzoate and 2-ethylhexyl 4-dimethylaminobenzoate; and mercaptan hydrogen donors such as 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 2-mercaptobenzimidazole.
The content of the photopolymerization initiator may be appropriately set according to the purpose, application, etc., and is not particularly limited, but is preferably 0.1 parts by mass or more relative to 100 parts by mass of the total solid content of the resist composition excluding the photopolymerization initiator. This makes it possible to obtain a cured product with excellent adhesion, and peeling is more sufficiently suppressed even after exposure to high temperatures. In addition, in consideration of the balance between the influence of the decomposition product of the photopolymerization initiator and economic efficiency, it is preferably 30 parts by mass or less. The lower limit is more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 2 parts by mass or more, and the upper limit is more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less.
As described above, the photosensitizer and photoradical polymerization accelerator do not have to be used, but when used, from the viewpoint of a balance between curability, the effects of decomposition products, and economic efficiency, the amount of the photosensitizer and photoradical polymerization accelerator is preferably 0.001 to 20 mass %, more preferably 0.01 to 15 mass %, and even more preferably 0.05 to 10 mass %, relative to 100 mass % of the total solid content of the resist composition.

[solvent]
The resist composition also preferably contains a solvent. The solvent is preferably used as a diluent or the like. Specifically, the solvent is preferably used to reduce the viscosity and improve the handling property; to form a coating film by drying; to serve as a dispersion medium for a coloring material; and the like, and is a low-viscosity organic solvent or water that can dissolve or disperse each component contained in the resist composition.
As the above-mentioned solvent, it is preferable to use a solvent other than a carbonate-based solvent, and it may be appropriately selected according to the purpose and use, and it is particularly preferable to use an ester-based solvent (esters) as an essential solvent, although it is not particularly limited. Examples of the solvent, including other solvents, include the following compounds. These may be used alone or in combination of two or more kinds.
Monoalcohols such as methanol, ethanol, isopropanol, n-butanol, and s-butanol; glycols such as ethylene glycol and propylene glycol; cyclic ethers such as tetrahydrofuran and dioxane; glycol monoethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, and 3-methoxybutanol; glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol dimethyl ether, and propylene glycol diethyl ether;
Glycol monoethers such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, and 3-methoxybutyl acetate. esters such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl lactate, ethyl lactate, butyl lactate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl acetoacetate, ethyl acetoacetate, and other alkyl esters; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and other aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and other aliphatic hydrocarbons such as hexane, cyclohexane, octane, and other amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and other water, and the like.
The total amount of the solvents used may be appropriately set depending on the purpose and application, and is not particularly limited, but it is preferable for the solvent to be contained in an amount of 10 to 90 mass %, and more preferably 20 to 80 mass %, relative to 100 mass % of the total amount of the resist composition.
When a resist composition is produced by mixing the polymer solution of the present invention with other components, the amount of the carbonate-based solvent to be used for solvent substitution and the solid contents of the polymer and other components may be confirmed, and then the amount of the solvent may be adjusted so as to fall within the above numerical range.

[Other ingredients]
The resist composition may further contain one or more of the following, depending on the required characteristics of each application to which it is applied: colorant (also called colorant, pigment, or dye); dispersant; heat resistance improver; leveling agent; development aid; inorganic fine particles such as silica fine particles; coupling agents such as silane, aluminum, and titanium; filler, epoxy resin, phenolic resin, polyvinylphenol, and other thermosetting resins; curing aids such as polyfunctional thiol compounds; plasticizer; polymerization inhibitor; ultraviolet absorber; antioxidant; matting agent; defoaming agent; antistatic agent; slip agent; surface modifier; thixotropic agent; thixotropic aid; quinone diazide compound; polyhydric phenol compound; cationic polymerizable compound; acid generator; etc. For example, when the resist composition is used for a color filter application, it is preferable to mix a colorant. The embodiment in which a colorant is further mixed into the resist composition in this way is also one of the preferred embodiments of the present invention. Also preferred is an embodiment in which at least one selected from the group consisting of a coloring material, a dispersant, a heat resistance improver, a leveling agent, a coupling agent, and a developing assistant is mixed.

[Method of producing resist composition]
The method for producing the resist composition is not particularly limited, and for example, the resist composition can be prepared by mixing and dispersing the above-mentioned components using various mixers and dispersers. The mixing and dispersing steps are not particularly limited, and may be carried out by a conventional method. In addition, the resist composition may further include other steps that are usually carried out. When the resist composition contains a coloring material, it is preferable to produce the resist composition through a coloring material dispersion treatment step.
The colorant dispersion process may be, for example, a method in which a colorant (preferably an organic pigment), a dispersant, and a solvent are weighed out in predetermined amounts, and the colorant is finely dispersed using a dispersing machine such as a paint conditioner, a bead mill, a roll mill, a ball mill, a jet mill, a homogenizer, a kneader, or a blender to obtain a liquid colorant dispersion (also called a mill base). Preferably, the kneading and dispersion process is performed using a roll mill, a kneader, a blender, or the like, and then a fine dispersion process is performed using a media mill such as a bead mill filled with beads of 0.01 to 1 mm. The obtained mill base is mixed with a composition (preferably a transparent liquid) containing an alkali-soluble polymer, a polymerizable monomer, and a photopolymerization initiator, as well as a solvent and a leveling agent, if necessary, which have been separately stirred and mixed, and mixed to obtain a uniform dispersion solution, thereby obtaining a resist composition. The obtained resist composition is preferably filtered using a filter or the like to remove fine dust.
[Cured product and method for producing the cured product]
As described above, the resist composition provides a cured product that is particularly excellent in heat resistance and transparency, and is excellent in basic performance such as developability, solvent resistance, adhesion to a substrate (base material), photosensitivity, and curability. Such a cured product also has excellent image forming properties and surface smoothness, and is free of, for example, residues or background stains in unexposed areas after development. A cured product obtained by curing such a resist composition and a method for producing a cured product by curing the resist composition are also preferred embodiments of the present invention.
The cured product (cured film) preferably has a film thickness of 0.1 to 20 μm. This makes it possible to fully meet the demand for low height for members using the cured product, laminates having the cured product on a substrate, display devices, etc. The film thickness is more preferably 0.5 to 10 μm, and even more preferably 0.5 to 8 μm.
The cured product can be suitably used for various optical components and components of electric and electronic devices, such as color filters, black matrices, photospacers, black column spacers, inks, printing plates, printed wiring boards, semiconductor elements, photoresists, insulating films, films, organic protective films, etc., used in liquid crystal, organic EL, quantum dot, and micro LED liquid crystal displays, solid-state imaging elements, and touch panel display devices. Among them, it is preferably used for color filters. Thus, a color filter using the resist composition, that is, specifically, a color filter having a cured product formed by the resist composition on a substrate, and a method for producing a color filter are one of the preferred embodiments of the present invention. The substrates used in the color filter include, for example, glass substrates such as white plate glass, blue plate glass, alkali-strengthened glass, and silica-coated blue plate glass; sheets, films, or substrates made of thermoplastic resins such as polyester, polycarbonate, polyolefin, polysulfone, ring-opening polymers of cyclic olefins, and hydrogenated products thereof; sheets, films, or substrates made of thermosetting resins such as epoxy resins and unsaturated polyester resins; metal substrates such as aluminum plates, copper plates, nickel plates, and stainless steel plates; ceramic substrates; semiconductor substrates having photoelectric conversion elements; glass substrates having a coloring material layer on the surface (e.g., color filters for LCDs); and other members made of various materials. Among these, from the viewpoint of heat resistance, glass substrates and sheets, films, or substrates made of heat-resistant resins are preferred. In addition, it is preferable that the substrate is a transparent substrate.
If necessary, the substrate may be subjected to a corona discharge treatment, an ozone treatment, or a chemical treatment using a silane coupling agent or the like.
In addition, preferred embodiments of the present invention also include a display device member having a cured product formed from the resist composition and a method for manufacturing a display device. Suitable display devices include liquid crystal display devices, solid-state imaging devices, touch panel display devices, etc., and the cured product is useful as a protective film or insulating film in various display devices.

The present invention will be described in more detail below with reference to examples. However, the following examples do not limit the present invention, and all modifications and variations within the scope of the present invention are included in the technical scope of the present invention.
The present invention will be specifically illustrated by examples, comparative examples, and property evaluations. In the examples and comparative examples, % means % by mass, and parts means parts by mass, unless otherwise specified.
[Evaluation method]
Weight average molecular weight (Mw)
The weight average molecular weight (Mw) was measured by GPC (gel permeation chromatography) using polystyrene as a standard substance and tetrahydrofuran as an eluent, with an HLC-8220GPC (manufactured by Tosoh Corporation) and a column: TSKgel Super HZM-M (manufactured by Tosoh Corporation).
(2) Acid value (AV)
3 g of the polymer solution was precisely weighed out and dissolved in a mixed solvent of 90 g of acetone and 10 g of water, and titrated using a 0.1 N KOH aqueous solution as a titrant. The titration was performed using an automatic titrator (product name: COM-555, manufactured by Hiranuma Sangyo Co., Ltd.), and the acid value per 1 g of solid content (mg KOH/g) was calculated from the acid value of the solution and the solid content of the solution.
(3) Solid content Approximately 1 g of the polymer solution was weighed out in an aluminum cup, and about 3 g of acetone was added to dissolve it, and then the solution was naturally dried at room temperature. Then, the solution was dried at 140°C under vacuum for 1.5 hours using a hot air dryer (product name: PHH-101, manufactured by Espec Corporation), and then allowed to cool in a desiccator, and the mass was measured. The solid content (mass%) of the polymer solution was calculated from the amount of mass loss.
(4) 22.5 parts of Light Acrylate DPE-6A (Kyoeisha Chemical Co., Ltd.) and 5 parts of Irgacure 907 (BASF Japan Co., Ltd.) were added to 64.3 parts of the heat-resistant polymer solution and mixed to prepare a curable resin composition. The obtained curable resin composition was uniformly applied onto a 5 cm square glass substrate (soda-lime glass AS-2K, Toshin Riko Co., Ltd.) using a spin coater (Mikasa Co., Ltd., 1H-D7) so that the coating amount was 0.2 to 0.5 mg/cm ² in terms of solid content. At this time, for each curable resin composition, the rotation speed of the spin coater was changed to change the coating amount (solid content equivalent) and two coated plates with different coating amounts were prepared. The coating amount of one of the two plates was always greater than 0.3 mg/cm ² , and the coating amount of the other plate was always less than 0.3 mg/cm ² .
These coated plates were dried for 3 minutes at 90° C. to obtain a laminate in which a coating film was formed on the glass substrate. After removing the resin adhering to the edge of the glass substrate, the obtained laminate was subjected to a heat treatment at 250° C. for 2 hours using a Perfect Oven Thermostat (manufactured by Espec Corporation) and then cooled to room temperature.
The coating film surface of the obtained laminate was measured using a spectrophotometer (CM-3700A, manufactured by Konica Minolta, Inc.) to obtain the b ^* value after heat treatment. For each coating film, an approximate straight line (calibration curve) of the coating amount (x) and the b ^* value (y) was determined from the measurements of the two coating films prepared as described above, and the b ^* value when the coating amount was 0.3 mg/ ^cm2 was used as the result of the heat coloration resistance of each coating film, and it was evaluated according to the following criteria.
○: b ^* value is 1 to 3.
△: b ^* value is 3 to 5.
×: b ^* value is 5 to 10.
(5) Solubility: The polymer solution was visually observed and evaluated according to the following criteria.
A: The polymer solution is colorless and transparent.
×: The polymer solution is cloudy.

[Example 1]
Preparation of Polymer Solution 1: Into a reaction vessel equipped with a thermometer, a stirrer, a gas inlet pipe, a cooling pipe, and a dropping vessel inlet, 123 parts of propylene glycol monomethyl ether acetate (PGMEA) was charged, and after replacing with nitrogen, the temperature was raised to 90° C. by heating with stirring.
On the other hand, a dropping tank (A) was prepared by thoroughly mixing 40 parts of N-cyclohexylmaleimide (CHMI), 20 parts of methacrylic acid (MAA), 40 parts of dicyclopentanyl methacrylate ("Fancryl FA-513M" manufactured by Hitachi Chemical Co., Ltd., hereinafter also referred to as DCPMA), 2 parts of t-butylperoxy-2-ethylhexanoate (polymerization initiator, "Perbutyl O" manufactured by NOF Corporation, hereinafter referred to as "PBO"), 13 parts of PGMEA, and 35 parts of dimethyl carbonate (DMC).
It was confirmed that the entire amount of CHMI was dissolved. 3.5 parts of n-dodecyl mercaptan (n-DM) and 5.1 parts of PGMEA were stirred and mixed in the dropping tank (B) to prepare the solution. After the temperature of the reaction tank reached 90°C, the dropping tank was started over 135 minutes while maintaining the same temperature, and polymerization was performed. After that, the temperature was maintained at 90°C for 60 minutes, and then the temperature was increased to 110°C and aged for 180 minutes to obtain a polymer solution 1.
The obtained polymer solution 1 was a transparent solution, and had a weight average molecular weight of 11,000, an acid value of the polymer of 126 mgKOH/g, and a solid content of 35% by mass.
The heat resistance was evaluated as good.
[Example 2]
Preparation of Polymer Solution 2 Polymer solution 2 was obtained in the same manner as in Example 1, except that 40 parts of CHMI as a monomer was replaced with 40 parts of benzylmaleimide (BzMI).
The obtained polymer solution 2 was a transparent solution, and had a weight average molecular weight of 11,000, an acid value of the polymer of 126 mgKOH/g, and a solid content of 35% by mass.
The heat resistance was evaluated as good.
[Example 3]
Preparation of Polymer Solution 3 Polymer solution 3 was obtained in the same manner as in Example 1, except that 35 parts of DMC in the solvent was replaced with 35 parts of diethyl carbonate (DEC).
The obtained polymer solution 3 was a transparent solution, and had a weight average molecular weight of 11,000, an acid value of the polymer of 126 mgKOH/g, and a solid content of 35% by mass.
The heat resistance was evaluated as good.

[Comparative Example 1]
Preparation of polymer solution 4 The monomers and solvent were changed to the formulation in Table 1, and it was not possible to carry out the same operation as in Example 1. Since a large amount of CHMI remained undissolved in this formulation, polymerization was not carried out. Therefore, it was not possible to evaluate the heat resistance of polymer solution 4.
[Comparative Example 2]
Preparation of Polymer Solution 5 Polymer solution 5 was obtained in the same manner as in Example 1, except that 40 parts of CHMI as a monomer was replaced with 40 parts of cyclohexyl methacrylate (CHMA).
The obtained polymer solution 5 was a transparent solution, and had a weight average molecular weight of 11,000, an acid value of the polymer of 126 mgKOH/g, and a solid content of 35% by mass.
The heat resistance was evaluated as poor, ie, .DELTA..

The conditions and evaluation results are shown in Table 1.

実施例１～３では、単量体成分としてＮ-置換マレイミド系単量体を高い割合で使用しているが、滴下槽（Ａ）におけるモノマー希釈溶媒としてカーボネート系溶媒であるＤＭＣ又はＤＥＣを約７３％と高い割合で使用しているのでＮ-置換マレイミド系単量体が溶解し、最終的に透明な重合体溶液が得られた。
Ｎ-置換マレイミド系単量体及びカーボネート系溶媒（総溶媒量の１０～１００質量％、好ましくは３０～９０質量％）を含む単量体溶液も本発明の一形態である。
比較例１では、モノマー希釈溶媒としてカーボネート系溶媒を使用していないのでＣＨＭＩが溶解せずに溶け残った。
比較例２で得られる重合体では、単量体成分としてＮ-置換マレイミド系単量体を使用していないので実施例１～３で得られる重合体に比べて耐熱性が低いと考えられる。
実施例１～３と、比較例１及び２との比較より、本発明の重合体溶液及び重合体溶液の製造方法の優位性を確認できた。

In Examples 1 to 3, a high proportion of N-substituted maleimide monomer was used as the monomer component, but the carbonate solvent DMC or DEC was used in a high proportion of about 73% as the monomer dilution solvent in the dropping tank (A), so that the N-substituted maleimide monomer was dissolved, and a transparent polymer solution was finally obtained.
A monomer solution containing an N-substituted maleimide monomer and a carbonate solvent (10 to 100% by mass, preferably 30 to 90% by mass of the total solvent amount) is also one embodiment of the present invention.
In Comparative Example 1, since a carbonate-based solvent was not used as the monomer dilution solvent, CHMI did not dissolve and remained undissolved.
The polymer obtained in Comparative Example 2 does not contain an N-substituted maleimide monomer as a monomer component, and is therefore considered to have lower heat resistance than the polymers obtained in Examples 1-3.
Comparison of Examples 1 to 3 with Comparative Examples 1 and 2 confirmed the superiority of the polymer solution and the method for producing the polymer solution of the present invention.

The polymer solution of the present invention is a transparent, homogeneous, alkali-soluble polymer solution containing a carbonate-based solvent. Therefore, it can be suitably used for various applications such as color filters, black matrices, photospacers, black column spacers, inks, printing plates, printed wiring boards, semiconductor elements, photoresists, insulating films, and other optical components used in liquid crystal, organic EL, quantum dot, and micro LED liquid crystal displays, solid-state imaging elements, and touch panel display devices; surface protection materials such as protective films for color filters, hard coat materials, and sealants for organic devices; etc.

Claims (6)

A method for producing an alkali-soluble polymer solution, comprising radically polymerizing , in the presence of a solvent, a monomer comprising (meth)acrylic acid , at least one N-substituted maleimide monomer selected from N-benzylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide, and at least one alicyclic hydrocarbon group-containing monomer selected from dicyclopentanyl(meth)acrylate, dicyclopentenyl(meth)acrylate, cyclohexyl(meth)acrylate, and isobornyl(meth) acrylate , A method for producing an alkali-soluble polymer solution, characterized in that a content of (meth)acrylic acid is 10 to 40 mass%, a content of the N-substituted maleimide monomer is 10 to 40 mass%, and a content of the alicyclic hydrocarbon group-containing monomer is 10 to 40 mass%, relative to a total amount of 100 mass%, and a mixed solvent is used, the mixed solvent comprising a content of a carbonate solvent of 10 to 80 mass%, and a content of a solvent other than a carbonate solvent selected from an ester solvent and an alcohol solvent of less than 30 mass%, relative to a total amount of 100 mass% of the solvent. The method for producing an alkali-soluble polymer solution according to claim 1, characterized in that the alkali-soluble polymer is a binder polymer of a resist composition for a color filter. 3. The method for producing an alkali-soluble polymer solution according to claim 1, wherein the alkali-soluble polymer solution has a solids concentration of 30 to 50 % by mass. An alkali-soluble polymer solution comprising an alkali-soluble polymer having a constitutional unit derived from (meth)acrylic acid , a constitutional unit derived from at least one N-substituted maleimide monomer selected from N-benzylmaleimide, N-phenylmaleimide, and N- cyclohexylmaleimide, and a constitutional unit derived from at least one alicyclic hydrocarbon group-containing monomer selected from dicyclopentanyl(meth)acrylate, dicyclopentenyl(meth)acrylate, cyclohexyl(meth)acrylate, and isobornyl(meth)acrylate, and a solvent, the alkali-soluble polymer contains, relative to 100% by mass of the total amount of structural units, 10 to 40% by mass of structural units derived from (meth)acrylic acid , 10 to 40% by mass of structural units derived from the N-substituted maleimide monomer, and 10 to 40% by mass of structural units derived from the alicyclic hydrocarbon group-containing monomer, and the alkali-soluble polymer solution contains, relative to 100% by mass of the total amount of the solvent, a mixed solvent in which a content ratio of a carbonate-based solvent is 10 to 80% by mass and a content ratio of a solvent other than a carbonate-based solvent selected from an ester-based solvent and an alcohol-based solvent is less than 30 % by mass. The alkali-soluble polymer solution according to claim 4, characterized in that the alkali-soluble polymer is a binder polymer of a resist composition for a color filter. 6. The alkali-soluble polymer solution according to claim 4, wherein the alkali-soluble polymer solution has a solids concentration of 30 to 50 mass %.