JP7630255B2 - Method for producing polymer solution - Google Patents

Description

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

Alkali-soluble polymers are useful in resist compositions, and are used, for example, as binder polymers in resist compositions for color filters, photolithospacers, and protective films for color filters. These alkali-soluble polymers can 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 the polymer to introduce a polymerizable double bond into the side chain, thereby increasing the curability (see, for example, Patent Document 1). In particular, for alkali-soluble polymers with a large amount of double bonds in the side chain, it is necessary to increase the amount of acid group-containing monomer used to produce the polymer that is the precursor polymer. For this reason, a specific polymerization solvent is used to produce a polymer with a large amount of acid groups (see, for example, Patent Document 2).

When a polymer solution is used in a resist composition, the solvent in the produced polymer solution may be replaced with a resist solvent, so solvent replacement may be performed (see, for example, Patent Documents 3 and 4).

Therefore, there is a demand for an alkali-soluble polymer solution that can reduce the effort required for solvent replacement in the production of resist compositions.

JP 2009-40999 A JP 2004-107401 A JP 2007-45922 A JP 2019-161091 A

For example, when a solvent mainly composed of an ester-based solvent, which is a general-purpose resist solvent, was used as a polymerization solvent for producing an alkali-soluble polymer solution, it was difficult to obtain a transparent polymer solution by polymerization of a specified monomer composition. The present invention was made in consideration of the above-mentioned current situation, and aims to provide a manufacturing method that can efficiently and easily obtain a transparent polymer solution containing a desired solvent.

As a result of intensive research, the inventors have discovered a manufacturing method for obtaining a transparent alkali-soluble polymer solution by polymerizing a monomer solution containing a solvent and a specific monomer, including an acid group-containing monomer.

That is, the object of the present invention is achieved by the following (1) to (7).
(1) A method for producing a polymer solution obtained by polymerizing a monomer containing an acid group-containing monomer and an aromatic vinyl monomer, the method being characterized in that 10% by mass to 48% by mass of the acid group-containing monomer, based on 100% by mass of the total amount of the acid group-containing monomers to be polymerized, is charged in advance into a reaction vessel, the remaining monomer solution is dropped into the reaction vessel, and the solvent for the obtained polymer solution contains an ester solvent in an amount of 90% by mass or more, based on 100% by mass of the total amount of the solvent.
(2) A method for producing a polymer solution obtained by polymerizing a monomer containing an acid group-containing monomer and an aromatic vinyl monomer, characterized in that a drop time of the monomer solution containing the aromatic vinyl monomer into a reaction tank is 1.10 times or more longer than a drop time of the monomer solution containing the acid group-containing monomer, and an ester solvent is used as a solvent for the obtained polymer solution in an amount of 90 mass% or more relative to 100 mass% of the total amount of the solvent.
(3) A method for producing a polymer solution obtained by polymerizing an acid group-containing monomer and a monomer containing an aromatic vinyl monomer, the method comprising: previously charging a reaction vessel with 10% by mass to 48% by mass of the acid group-containing monomer relative to 100% by mass of the total amount of the acid group-containing monomers to be polymerized; dripping the remaining monomer solution into the reaction vessel for a drip time of the monomer solution containing the aromatic vinyl monomer that is 1.10 times or more longer than the monomer solution containing the acid group-containing monomer; and as the solvent for the obtained polymer solution, an ester solvent accounts for 90% by mass or more relative to 100% by mass of the total amount of the solvent.
(4) The method for producing a polymer solution according to any one of (1) to (3), wherein the monomer solution further contains a monomer capable of introducing a ring structure into a main chain.
(5) The method for producing a polymer solution according to (4), wherein the monomer capable of introducing a ring structure into the main chain is an N-substituted maleimide monomer and/or an α-(unsaturated alkoxyalkyl)acrylate monomer.
(6) The method for producing the polymer solution according to any one of (1) to (5), further comprising reacting the polymer solution with a compound having a functional group capable of bonding to an acid group and a polymerizable double bond to introduce a side chain double bond.
(7) A method for producing a photosensitive resin composition, further comprising mixing the polymer solution obtained by any one of the production methods (1) to (6) with a photopolymerization initiator and a polyfunctional polymerizable monomer.

By using the method for producing a polymer solution of the present invention, it was possible to efficiently and easily obtain a transparent polymer solution containing an ester-based solvent that is commonly used as a solvent for resist compositions.

1 is an example of the conversion rate of each monomer when the method for producing a polymer solution of the present invention is used. 1 is an example of the conversion of each monomer when the method for producing a polymer solution of the present invention is not used.

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.
As described above, the method for producing a polymer solution of the present invention may be embodied in the following three forms (1) to (3). In addition, the control methods A to C which exert the effects are specifically described.
(1) A method for producing a polymer solution obtained by polymerizing a monomer containing an acid group-containing monomer and an aromatic vinyl monomer, characterized in that Control A (10% by mass to 48% by mass of the acid group-containing monomer is charged in advance into a reaction vessel, based on 100% by mass of the total amount of the acid group-containing monomers to be polymerized, and the remaining monomer solution is added dropwise to the reaction vessel) and Control B (90% by mass or more of an ester solvent is used as the solvent for the obtained polymer solution, based on 100% by mass of the total amount of the solvent).
(2) A method for producing a polymer solution obtained by polymerizing an acid group-containing monomer and a monomer containing an aromatic vinyl monomer, characterized in that Control C (the drop time of the monomer solution containing the aromatic vinyl monomer into a reaction tank is 1.10 times or more longer than the drop time of the monomer solution containing the acid group-containing monomer) and Control B (the ester solvent is 90 mass% or more relative to 100 mass% of the total amount of the solvent as the solvent for the obtained polymer solution).
(3) A method for producing a polymer solution obtained by polymerizing an acid group-containing monomer and a monomer containing an aromatic vinyl monomer, characterized in that in Control A (10% by mass to 48% by mass of the acid group-containing monomer is charged in advance into a reaction vessel relative to 100% by mass of the total amount of the acid group-containing monomers to be polymerized, and the remaining monomer solution is dropped into the reaction vessel), Control C (the drop time of the monomer solution containing the aromatic vinyl monomer is 1.10 times or more than the drop time of the monomer solution containing the acid group-containing monomer) and Control B (the amount of an ester solvent as the solvent for the obtained polymer solution is 90% by mass or more relative to 100% by mass of the total amount of the solvent).
Each component contained in the monomer solution used in the present invention will be described below.
[Monomer]
The monomers used in the method for producing a polymer solution of the present invention contain an acid group-containing monomer and an aromatic vinyl monomer as essential components, and preferably further contain a monomer capable of introducing a ring structure into the main chain of the polymer.
<Acid Group-Containing Monomer>
Examples of the acid group-containing monomer include monomers having a carboxyl group, such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinic acid, and itaconic acid; and monomers having a carboxylic anhydride group, such as maleic anhydride and itaconic anhydride. Among these, monomers having a carboxyl group are preferred, and (meth)acrylic acid is particularly preferred. (Meth)acrylic acid is an acid group-containing monomer with the simplest structure, and can reduce decomposition gases during heating.

The ratio of the acid group-containing monomer in the monomer to be polymerized is not particularly limited, but the substantial ratio is preferably 10 to 60% by mass, particularly preferably 25 to 50% 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. Here, the substantial ratio of the acid group-containing monomer is the ratio excluding the amount consumed by reacting with glycidyl (meth)acrylate or the like in order to introduce a reactive double bond (polymerizable double bond) to the side chain described later. In the present invention, as described later, glycidyl (meth)acrylate or the like may be reacted in order to introduce a reactive double bond to the side chain. In such a case, it is necessary to add the amount of the acid group-containing monomer consumed in advance. The total amount of acid group-containing monomers in the monomer components (monomer units) of the polymer solution after modification by reaction with glycidyl (meth)acrylate or the like is preferably 1 to 50 mass% based on the total amount of all monomers, and particularly preferably 5 to 30 mass%, at which a remarkable effect can be exhibited.
<Aromatic vinyl monomer>
The aromatic vinyl monomer is a monomer having an aromatic group and a vinyl group. The aromatic group increases the steric hindrance near the main chain and can suppress the association of the acid group, thereby contributing to suppression of cloudiness during synthesis. In addition, the aromatic group contributes to dispersion stability, and when a photosensitive resin composition is prepared, it can suppress the generation of residues during development. Examples of the aromatic group include groups containing a benzene ring, a naphthalene ring, etc., and among them, a group containing a benzene ring is preferable. The aromatic group may have a substituent. Examples of the substituent include an alkyl group having 1 to 5 carbon atoms and an alkoxy group having 1 to 5 carbon atoms. Examples of the aromatic vinyl monomer include styrene, vinyltoluene, α-methylstyrene, xylene, methoxystyrene, ethoxystyrene, etc., and among them, styrene and vinyltoluene are preferable in terms of improving thermal decomposition resistance, and further, vinyltoluene is more preferable in terms of having a high dissolution rate in organic solvents and alkalis and the methyl group contributes to improving the above-mentioned steric hindrance and hydrophobicity. Considering the compatibility with other monomers, the amount is preferably 10 to 90% by mass relative to 100% by mass of the total amount of all monomers during polymerization. Considering the polymerizability, the amount is more preferably 15% by mass or more, and even more preferably 25% by mass or more, and more preferably 85% by mass or less, and even more preferably 80% by mass or less, relative to 100% by mass of the total amount of all monomers.

The vinyltoluene may be o-vinyltoluene, p-vinyltoluene, or m-vinyltoluene. Among these, m-vinyltoluene, p-vinyltoluene, and a mixture of m-vinyltoluene and p-vinyltoluene, which are easily available industrially, are preferred, and a mixture of m-vinyltoluene and p-vinyltoluene, which is easily available industrially, is particularly preferred.
The proportion of vinyltoluene in the monomer components of the modified polymer solution of the present invention is not particularly limited, but is preferably 5 to 85% by mass, preferably 10 to 80% by mass, and more preferably 20 to 70% by mass, based on the total monomer components. If the amount of vinyltoluene is too large, the solubility in alkali may decrease. If the amount is too small, the thermal stability may decrease, and the generation of decomposition gas during heating may increase.
<Monomer capable of introducing a ring structure into the main chain of a polymer>
Examples of the ring structure in the monomer capable of introducing a ring structure into the main chain of the polymer include an imide ring, a tetrahydropyran ring, a tetrahydrofuran ring, a lactone ring, etc. Examples of the monomer capable of introducing a ring structure into the main chain of the polymer include an N-substituted maleimide monomer, a dialkyl-2,2'-
Examples of the monomers include (oxydimethylene)diacrylate monomers, α-(unsaturated alkoxyalkyl)acrylate monomers [preferably alkyl-(α-allyloxymethyl)acrylate monomers], etc. Among them, when an N-substituted maleimide monomer and/or an α-(unsaturated alkoxyalkyl)acrylate monomer (preferably alkyl-(α-allyloxymethyl)acrylate monomer) is used, a polymer solution capable of giving a cured product having improved heat resistance, hardness, colorant dispersibility, etc. can be obtained. As a monomer capable of introducing a ring structure into the main chain of a polymer, an N-substituted maleimide monomer is preferred. N-substituted maleimide monomers have good copolymerizability with both acid group-containing monomers/aromatic vinyl monomers, and contribute to synthesis stability. In addition, depolymerization of the main chain end can be suppressed, and generation of decomposition gas during heating can be reduced.

Specific examples of the N-substituted maleimide monomer include alkyl-substituted maleimides such as N-methylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide;
Among these, N-phenylmaleimide, N-cyclohexylmaleimide, N-
Benzylmaleimide is preferred from the viewpoints of solubility in a solvent, resistance to thermal decomposition, ease of industrial availability, etc. Among these, N-benzylmaleimide is most preferred from the viewpoints of solubility in a solvent and little coloration on heating.

The dialkyl-2,2'-(oxydimethylene)diacrylate monomers include
For example, 2,2'-[oxybis(methylene)]bisacrylic acid, dialkyl-2,2'
Examples of such compounds include compounds in which at least one of the ester moieties contains a tertiary carbon, such as dialkyl-2,2'-[oxybis(methylene)]bis-2-propenoate and dialkyl-2,2'-[oxybis(methylene)]bis-2-propenoate. Among these, from the viewpoints of transparency, dispersibility, ease of industrial availability, and the like, it is preferable to use, for example, dimethyl-2,2'-[oxybis(methylene)]bis-2-propenoate.

The α-(unsaturated alkoxyalkyl)acrylate monomers include, for example, α-
Allyloxymethylacrylic acid, methyl α-allyloxymethylacrylate, ethyl α-allyloxymethylacrylate, n-propyl α-allyloxymethylacrylate, α-
Examples of the allyloxymethylacrylate include i-propyl allyloxymethylacrylate, n-butyl α-allyloxymethylacrylate, s-butyl α-allyloxymethylacrylate, t-butyl α-allyloxymethylacrylate, n-amyl α-allyloxymethylacrylate, s-amyl α-allyloxymethylacrylate, t-amyl α-allyloxymethylacrylate, and neopentyl α-allyloxymethylacrylate. Among these, alkyl-(α-allyloxymethyl)acrylate monomers are preferred. As the alkyl-(α-allyloxymethyl)acrylate monomer, it is preferred to use, for example, methyl-(α-allyloxymethyl)acrylate from the viewpoints of transparency, dispersibility, ease of industrial availability, and the like. The above-mentioned α-(unsaturated alkoxyalkyl)acrylate can be produced, for example, by the production method disclosed in WO 2010/114077.
The proportion of monomers capable of introducing a ring structure into the main chain of the polymer among the monomers to be polymerized is preferably 3 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 monomers capable of introducing a ring structure into the main chain of the polymer 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, while 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 and/or α-(unsaturated alkoxyalkyl)acrylate monomer in the monomer component when obtaining the modified polymer solution of the present invention is not particularly limited, but is preferably 1 to 50 mass %, preferably 2 to 40 mass %, and more preferably 3 to 35 mass % of the total monomer component.
If the amount of the N-substituted maleimide monomer and/or the α-(unsaturated alkoxyalkyl)acrylate monomer is too large, there is a concern that the solubility in a solvent or an alkali may decrease, or that precipitation or gelation may occur easily during polymerization. On the other hand, if the amount is too small, there is a concern that the heat resistance may be insufficient.

The monomers used in the method for producing a polymer solution of the present invention may or may not contain other monomers other than the above-mentioned monomers, but the total mass ratio of the above-mentioned monomers (acid group-containing monomer, aromatic vinyl monomer, and monomer capable of introducing a ring structure into the main chain) in the monomers is, for example, preferably 50 to 100 mass%, more preferably 80 to 100 mass%, and most preferably 100 mass%, relative to 100 mass% of the total amount of all monomers during polymerization. By setting it in the above-mentioned range, it is possible to reduce easily decomposable units such as ester bonds and suppress the generation of decomposition gas during heating.
The arrangement of the monomer units in the above polymer may be, for example, any of a random copolymer, an alternating copolymer, and a block copolymer.
<Other monomers>
Examples of other monomers other than the above monomers include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate; butadiene or substituted butadiene compounds such as butadiene and isoprene; ethylene or substituted ethylene compounds such as ethylene, propylene, vinyl chloride, and acrylonitrile; vinyl esters such as vinyl acetate; and the like. Among these, methyl (meth)acrylate and benzyl (meth)acrylate are preferred. These other copolymerizable monomers may be used alone or in combination of two or more.
[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 a solvent is used in the polymerization of the monomer, a solvent used in a normal radical polymerization reaction can be used as the solvent. In the present invention, it is preferable to use an ester-based solvent that is generally used as a solvent for a resist composition in an amount of 90% by mass or more relative to 100% by mass of the total amount of the solvent. Specifically, the following can be mentioned.
<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 may be used in combination of two or more kinds. In addition, solvents other than ester solvents may be used in a range of less than 10% by mass relative to the total amount of the solvents (100% by mass), preferably less than 5% by mass, more preferably less than 3% by mass, and most preferably not used substantially (0% by mass). By using ester solvents as the main component as much as possible, the trouble of solvent replacement can be reduced, and when a pigment is contained in the resist composition, the dispersibility of the pigment can be improved. For reference, in the above-mentioned document of the prior art, when the content of the acid group-containing monomer exceeds 30% by mass, a mixed solvent of an ester solvent such as propylene glycol monomethyl ether acetate and an alcohol solvent such as propylene glycol monomethyl ether or isopropanol is mentioned as a preferred embodiment in order to prevent precipitation of the polymer, but when the solvent of the resist composition is used as a single solvent, the trouble of solvent replacement is required. Note that the content of the acid group-containing monomer here is the amount consumed to introduce a reactive double bond into the side chain.

[Method for producing polymer solution (polymerization step)]
Examples of the method for polymerizing the monomer used in the present invention include bulk polymerization, solution polymerization, emulsion polymerization, and the like. 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 from an active energy source such as heat, electromagnetic waves (e.g., infrared rays, ultraviolet rays, X-rays, etc.) to the monomer component, 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 the polymerization initiator, the polymerization temperature, and the type and amount of the chain transfer agent. When the above monomer is polymerized by a solution polymerization method, the solvent used for polymerization is preferably inactive to the polymerization reaction. For example, it may be appropriately set depending on polymerization conditions such as the polymerization mechanism, the type and amount of the monomer used, the polymerization temperature, and the polymerization concentration, but when a solvent is used as a diluent or the like when a curable resin composition (resist composition) is subsequently produced, it is efficient and preferable to use a solvent containing the solvent for solution polymerization of the monomer. In the present invention, an efficient production method using an ester-based solvent as a polymerization solvent as a main component has been found.

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 appropriately set depending on the type and amount of the monomer used, the type and amount of the polymerization initiator, etc., but is preferably a temperature that is 20°C or more lower than the boiling point of the polymerization solvent. In the case of a mixed solvent, the temperature is preferably 20°C or more 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. Similarly, the polymerization time can be appropriately set, but is preferably, for example, 1 to 8 hours, and more preferably 2 to 6 hours.
[Control A]
Control A in the method for producing an alkali-soluble polymer solution of the present invention is a control in which at least 10% by mass or more of the acid group-containing monomer is charged in advance into a reaction tank, based on 100% by mass of the total amount of the acid group-containing monomers to be polymerized, and the remaining monomer solution is added dropwise to the reaction tank.
The monomers used as essential components in the production method of the present invention are an acid group-containing monomer and an aromatic vinyl monomer. The present inventors have found that in the presence of a solvent mainly composed of an ester solvent, by initially charging at least 10% by mass, preferably 15% by mass or more, and particularly preferably 20% by mass or more of the acid group-containing monomers in advance in a reaction tank relative to 100% by mass of the total amount of the acid group-containing monomers, a transparent polymer solution can be obtained with a good balance of the polymerization rate (conversion rate to polymer). The upper limit is preferably 48% by mass or less, more preferably 45% by mass or less, particularly preferably 40% by mass or less, and most preferably 35% by mass or less. When the remaining monomer solution is dropped into the reaction tank, the components to be dropped include the remaining acid group-containing monomers not initially charged, aromatic vinyl monomers, preferably monomers capable of introducing a ring structure into the main chain of the polymer, other monomers, polymerization initiators, and chain transfer agents. It is preferable to drop each of the above components separately, but they may be appropriately combined. When they are combined, they are mixed in advance in a dropping tank. In addition, the optional monomers may be mixed in advance and dropped separately, or may be mixed in advance with the above-mentioned essential monomers and dropped. In the present invention, it is preferable to drop the acid group-containing monomer and the aromatic vinyl monomer separately. It is also preferable to drop the polymerization initiator and the chain transfer agent separately. The remaining monomer solution may be partially charged initially to the extent that the balance of the polymerization behavior is not lost. For example, when the aromatic vinyl monomer is initially charged, it may be initially charged in an amount of preferably 20% by mass or less, more preferably 15% by mass or less, particularly preferably 10% by mass or less, and most preferably 5% by mass or less, based on 100% by mass of the total amount of the aromatic vinyl monomers.

[Control B]
Control B in the method for producing an alkali-soluble polymer solution of the present invention is a control in which the amount of an ester solvent in the resulting polymer solution is 90% by mass or more relative to 100% by mass of the total amount of the solvent, preferably 95% by mass or more, more preferably 98% by mass or more, and particularly preferably 100% by mass, which is the upper limit, and it is most preferable to use an ester solvent in its entirety.
The solvent used is the above-mentioned ester-based solvent as the main component. An example is shown below.
When the polymer (alkali-soluble polymer) obtained by the production method of the present invention is used as a resist resin, it is preferable to use the same solvent as the solvent constituting the resist, since the resist can be used without removing the solvent when preparing the resist, and the process can be simplified. Such a solvent preferably contains an ester solvent such as propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, ethyl lactate, etc., and more preferably contains it as the main component (90% by mass or more of the total solvent). Examples of the remaining solvent include, but are not limited to, ketone solvents such as cyclohexanone, and ether solvents such as ethylene glycol dimethyl ether and ethylene glycol diethyl ether. In addition, low-boiling solvents that are easy to remove, such as methyl acetate, ethyl acetate, acetone, and methyl ethyl ketone, are also preferable. In addition, when removing the solvent, low-boiling alcohol solvents that are easy to remove, such as methanol, ethanol, and isopropanol, are more preferable. Therefore, when used as a resin for an alkali development type negative resist such as a resist for a color filter, the solvent is preferably a mixed solvent containing 90 mass % or more of an ester solvent such as propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, ethyl lactate, or the like, and less than 10 mass % of a ketone solvent such as cyclohexanone, an ether solvent such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, or other alcohol solvent, and it is particularly preferable that the ester solvent be 100 mass %.

The total amount of the solvent is preferably 50 to 1000% by mass relative to 100% by mass of the total amount of the monomers. More preferably, it is 120 to 900% by mass, and particularly preferably, it is 100 to 200% by mass. The solvent may be partially charged into the reaction tank at the beginning, or may be mixed with the monomer to be dropped and then dropped. When the monomer is polymerized by a radical polymerization mechanism, it is industrially advantageous and preferable to use a polymerization initiator that generates radicals by heat. Such a polymerization initiator is not particularly limited as long as it generates radicals by supplying thermal energy, and the above-mentioned polymerization initiator may be appropriately selected according to the polymerization conditions such as the polymerization temperature, the solvent, and the type of the monomer to be polymerized. In addition, a reducing agent such as a transition metal salt or an amine may be used in combination with the polymerization initiator.

[Control C]
Control C in the method for producing an alkali-soluble polymer solution of the present invention is a control in which the drop time of the monomer solution containing an aromatic vinyl monomer into a reaction vessel is 1.10 times or more, preferably 1.20 times or more, of the drop time of the monomer solution containing an acid group-containing monomer, and the upper limit is preferably 2.00 times or less, more preferably 1.80 times or less, particularly preferably 1.50 times or less, and most preferably 1.40 times or less.
By controlling the dropping time, the polymerization rates of the individual monomers (conversion rates to polymer) can be well balanced, and a transparent polymer solution can be obtained.
The drop time of the acid group-containing monomer into the reaction vessel is preferably 0.5 to 10.0 hours. The drop time of the aromatic vinyl monomer into the reaction vessel is longer than the drop time of the acid group-containing monomer, and is preferably 1.0 to 20 hours. The drop time of the aromatic vinyl monomer is preferably 1.10 to 1.80 times, more preferably 1.10 to 1.50 times, and even more preferably 1.20 to 1.40 times, the drop time of the acid group-containing monomer.

When using the above two monomers, the conversion rates of each monomer to polymer will be well balanced and stable if the dropwise addition of the acid group-containing monomer is completed, for example, 30 to 100 minutes earlier. Also, if the ratio is outside the above range, the conversion rates will be unbalanced and a transparent polymer solution may not be obtained.

Figures 1 and 2 show examples of conversion curves (changes over time from the start of polymerization to temperature rise and aging) of the essential monomers, an acid group-containing monomer (AA: acrylic acid) and an aromatic vinyl monomer (VT: vinyl toluene), when the method for producing an alkali-soluble polymer solution of the present invention is used and when it is not used.

After the dropwise addition of each monomer, preferably the polymerization initiator and the chain transfer agent, to obtain the desired polymer is completed, the polymerization process is carried out, and then the temperature is raised and the process moves to the aging process. The aging process preferably lasts for 0.5 to 3 hours, during which the remaining monomers and polymerization initiator are consumed. To consume the monomers, it is preferable to add a polymerization initiator.

The example shown in Figure 1, which shows the polymerization behavior of the above form (3), is explained. To obtain a polymer solution in which the polymerization solvent (synthetic solvent) is only an ester-based solvent (propylene glycol monomethyl ether acetate), 25% by mass of a total amount of acrylic acid (100% by mass) is initially charged into the reaction tank, and the dropwise addition of acrylic acid is completed in 3 hours and the dropwise addition of vinyltoluene in 4 hours. The conversion rate of vinyltoluene is slightly lower than that of acrylic acid in the early stages of polymerization. At the start of the temperature-raising and aging (after 300 minutes of polymerization), the conversion rate of vinyltoluene slightly exceeds that of acrylic acid, but the balance is good. In addition, cloudiness during the temperature-raising and aging is suppressed.

The example in Figure 2 is explained. To obtain a polymer solution in which the polymerization solvent is only an ester solvent (propylene glycol monomethyl ether acetate), no initial charge of monomers is made to the reaction vessel, and the dripping of acrylic acid is completed in 3.75 hours and the dripping of vinyltoluene in 4 hours. At the start of the temperature-raising and maturing process (after 300 minutes of polymerization), the conversion rate of vinyltoluene is significantly higher than the conversion rate of acrylic acid. In addition, the polymer solution becomes cloudy during the temperature-raising and maturing process.

Although the reason why the effect of the present invention is manifested is not clear, it is believed that the degree of cloudiness is reduced as the conversion rate curves of the individual monomers become more equivalent (matching and well-balanced).
It is preferable to control the difference in conversion rate between acrylic acid and vinyltoluene to preferably 10% or less, particularly preferably 8% or less, and particularly preferably 5% or less.
[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 and a polymerizable double bond that can be bonded to an acid group 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 to give a cured product with excellent adhesion to a substrate or the like and excellent surface hardness. In this way, it is also preferable that the production method of the present invention is in a form including the polymerization step and the double bond addition step.

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 an epoxy group-containing monomer with a polymer solution after polymerization.
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 preferably obtain a side chain double bond-containing polymer. The double bond equivalent of the side chain double bond-containing polymer is preferably 300 to 1500 (g/equivalent), more preferably 350 to 800 (g/equivalent), and most preferably 400 to 600 (g/equivalent). By controlling it within the above range, both curability and developability can be achieved. In addition, the glass transition temperature (Tg) of the side chain double bond-containing polymer is preferably 80°C or less. This improves adhesion. More preferably, it is 70°C or less, even more preferably 60°C or less, particularly preferably 50°C or less, and most preferably 40°C or less. The lower limit is not particularly limited, but from the viewpoint of heat resistance, it is preferably -10°C or more. More preferably, it is 0°C or more.
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.
[Alkali-soluble polymer]
The alkali-soluble polymer preferably obtained by the production method of the present invention has an acid value of 30 to 300 mgKOH/g. When the acid value is in this range, sufficient alkali solubility is exhibited, so that, 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. Furthermore, by employing the production method of the present invention, an alkali-soluble polymer having an acid value in such a range can be efficiently and easily obtained.
In order for the effects of the present invention to be prominent, the acid value of the base polymer 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, both excellent development speed and curability can be achieved. In this way, the above-mentioned production method is a method for obtaining an alkali-soluble polymer having an acid value of 30 to 300 mgKOH/g, which is one of the preferred embodiments of the present invention. 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 150 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. Having a molecular weight within this range makes it possible to obtain better plate-making properties. More preferably, it is 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. When the alkali-soluble polymer has a high molecular weight, a higher acid value tends to provide better plate-making properties, whereas when the alkali-soluble polymer has a low molecular weight, good plate-making properties tend to be obtained even with a low acid value.

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 the eluent and a TSKgel Super HZM-M (manufactured by Tosoh Corporation) column, in terms of standard polystyrene.

The double bond equivalent is the mass of the solid content of the polymer solution per 1 mol of double bonds in 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 determined 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 in the copolymer can be determined 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, and IR, or by differential scanning calorimetry.

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.

[Resist Composition]
The alkali-soluble polymer preferably obtained by the production method of the present invention has excellent physical properties such as photosensitivity, adhesion to a substrate, developability, heat resistance, transparency, etc., and also has excellent image forming properties and surface smoothness, and can provide 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 (photosensitive resin composition) is also one of the preferred forms of the present invention. The resist composition containing the alkali-soluble polymer solution obtained by the production method and the method for producing the resist composition are also one of the present inventions.
In the method for producing the resist composition, it is preferable to mix the alkali-soluble polymer solution, a polymerizable compound, and 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 according to the type of the polymerizable compound and the (meth)acrylate 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.
The above-mentioned solvent can be a commonly used solvent, and may be appropriately selected according to the purpose and use. Although not particularly limited, it is preferable that an ester-based solvent (esters) is essential. Examples of the solvent, including other solvents, include the following compounds. These may be used alone or in combination of two or more.
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; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and other ketones; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and other aromatic hydrocarbons; hexane, cyclohexane, octane, and other aliphatic hydrocarbons; amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and other amides; 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 obtained by the production method of the present invention with other components, the amount of solvent can be adjusted so as to fall within the above numerical range after confirming the solid contents of the polymer solution and other components.
[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 is particularly excellent in photosensitivity and curability, and gives a cured product that is excellent in basic performance such as developability, solvent resistance, adhesion to a substrate (base material), heat resistance, and transparency. Such a cured product is also excellent in image formability 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 and displays using the cured product. 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. In particular, it is preferably used for color filters. Thus, a color filter using the resist composition, that is, specifically, a method for producing a color filter having a cured product formed by the resist composition on a substrate, is one of the preferred embodiments of the present invention. In addition, a member for a display device and a method for producing a display device having a cured product formed by the resist composition are also included in the preferred embodiments of the present invention. As the display device, a liquid crystal display device, a solid-state imaging element, a touch panel display device, etc. are suitable, and the cured product is useful as a protective film or an 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 solids (mg KOH/g) was calculated from the acid value of the solution and the solids of the solution. The BP acid value is the acid value of the base polymer solution (polymer solution before modification).
(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) Amount of unreacted monomer in the reaction vessel (amount of remaining monomer)
The amount of unreacted monomer in the reaction vessel was determined by a known method using gas chromatography. The conversion rate was calculated by subtracting the amount of unreacted monomer (%) from 100 (%).

[Example 1]
In a separable flask equipped with a cooling tube as a reaction vessel, 94.3 parts of propylene glycol monomethyl ether acetate (PGMEA), 4.5 parts of acrylic acid (AA), and 8.3 parts of vinyl toluene (VT) were charged, and after nitrogen replacement, the temperature was raised to 90 ° C. On the other hand, 15.0 parts of N-benzylmaleimide (BzMI), 25.5 parts of acrylic acid, and 60.0 parts of PGMEA were mixed in the dropping vessel 1. In addition, 46.8 parts of vinyl toluene were prepared in the dropping vessel 2. In addition, 2.0 parts of perbutyl O (PBO) and 8.0 parts of PGMEA were mixed in the dropping vessel 3. In addition, 2 parts of n-dodecyl mercaptan (nDM) and 8 parts of propylene glycol monomethyl ether acetate were mixed in the dropping vessel 4. While maintaining the reaction temperature at 90 ° C., the reaction tank was dripped at a constant rate over 3.5 hours in drip tank 1, 4.0 hours in drip tank 2, 4.0 hours in drip tank 3, and 4.0 hours in drip tank 4. After the dripping was completed, the temperature was kept at 90 ° C. for 30 minutes, and then 0.5 parts of Perbutyl O (PBO) was added, and the reaction was continued for another 30 minutes at 90 ° C. Then, the reaction temperature was raised to 115 ° C., and the reaction was continued for 1.5 hours to obtain a base polymer solution (BPMw 14000, BP acid value 230 mg KOH / g). After cooling to room temperature once, 29.6 parts of glycidyl methacrylate (GMA), 0.19 parts of Antage W-400, and 0.39 parts of triethylamine were added, and the temperature was raised to 110 ° C. while bubbling a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, and the reaction was carried out for 1 hour. Thereafter, the temperature was raised to 115°C and the reaction was carried out for 7.5 hours, and the reaction was completed. The reaction was then cooled to room temperature to obtain a polymer solution (A-1). The weight average molecular weight of the obtained polymer solution (A-1) was 15,000, and the acid value per solid content was 100 mgKOH/g. The polymer solution (A-1) was a transparent solution without becoming cloudy.
[Example 2]
In a separable flask equipped with a cooling tube as a reaction vessel, 128.7 parts of propylene glycol monomethyl ether acetate (PGMEA) and 9.4 parts of acrylic acid (AA) were charged, and after nitrogen replacement, the temperature was raised to 90 ° C. On the other hand, 15.0 parts of N-benzylmaleimide (BzMI), 28.1 parts of acrylic acid, and 60.0 parts of PGMEA were mixed in the dropping vessel 1. In addition, 47.5 parts of vinyl toluene were prepared in the dropping vessel 2. In addition, 2.0 parts of perbutyl O (PBO) and 8.0 parts of PGMEA were mixed in the dropping vessel 3. In addition, 5.7 parts of n-dodecyl mercaptan and 4.3 parts of propylene glycol monomethyl ether acetate were mixed in the dropping vessel 4. While maintaining the reaction temperature at 90 ° C., the reaction tank was dripped at a constant speed over 3.0 hours in drip tank 1, 4.0 hours in drip tank 2, 4.0 hours in drip tank 3, and 4.0 hours in drip tank 4. After the dripping was completed, the temperature was kept at 90 ° C. for 30 minutes, and then 0.5 parts of Perbutyl O (PBO) was added, and the reaction was continued for another 30 minutes at 90 ° C. Thereafter, the reaction temperature was raised to 115 ° C., and the reaction was continued for 1.5 hours to obtain a base polymer solution (BPMw 8600, BP acid value 277 mg KOH / g). After cooling to room temperature once, 49.3 parts of glycidyl methacrylate (GMA), 0.19 parts of Antage W-400, and 0.39 parts of triethylamine were added, and the temperature was raised to 110 ° C. while bubbling a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, and the reaction was carried out for 1 hour. Thereafter, the temperature was raised to 115°C and the reaction was carried out for 7.5 hours, the reaction was completed, and the mixture was cooled to room temperature to obtain a polymer solution (A-2). The weight average molecular weight of the obtained polymer solution (A-2) was 13,500, and the acid value per solid content was 75 mgKOH/g. The polymer solution (A-2) was a transparent solution without becoming cloudy.

[Comparative Example 1]
A separable flask equipped with a cooling tube was charged with 128.7 parts of propylene glycol monomethyl ether acetate (PGMEA) as a reaction vessel, and after nitrogen replacement, the temperature was raised to 90°C. On the other hand, 15.0 parts of N-benzylmaleimide (BzMI), 37.5 parts of acrylic acid, and 60.0 parts of PGMEA were mixed in the dropping vessel 1. In addition, 47.5 parts of vinyltoluene were prepared in the dropping vessel 2. In addition, 2.0 parts of perbutyl O (PBO) and 8.0 parts of PGMEA were mixed in the dropping vessel 3. In addition, 5.7 parts of n-dodecyl mercaptan and 4.3 parts of propylene glycol monomethyl ether acetate were mixed in the dropping vessel 4. While maintaining the reaction temperature at 90°C, dropping was performed at a constant rate into the reaction tanks over 3.75 hours in dropping tank 1, 4.0 hours in dropping tank 2, 4.0 hours in dropping tank 3, and 4.0 hours in dropping tank 4. After completion of dropping, the temperature was maintained at 90°C for 30 minutes, and then 0.5 parts of Perbutyl O (PBO) was added, and the reaction was continued for another 30 minutes at 90°C. Thereafter, the reaction temperature was raised to 115°C, but the reaction was stopped because the solution became cloudy. The obtained polymer solution (A-3) became cloudy during temperature raising and maturation, and therefore a transparent solution was not obtained.
[Comparative Example 2]
In a separable flask equipped with a cooling tube as a reaction vessel, 128.7 parts of propylene glycol monomethyl ether acetate (PGMEA) and 1.9 parts of acrylic acid (AA) were charged, and after nitrogen replacement, the temperature was raised to 90 ° C. On the other hand, 15.0 parts of N-benzylmaleimide (BzMI), 35.6 parts of acrylic acid, and 60.0 parts of PGMEA were mixed in the dropping vessel 1. In addition, 47.5 parts of vinyl toluene were prepared in the dropping vessel 2. In addition, 2.0 parts of perbutyl O (PBO) and 8.0 parts of PGMEA were mixed in the dropping vessel 3. In addition, 5.7 parts of n-dodecyl mercaptan and 4.3 parts of propylene glycol monomethyl ether acetate were mixed in the dropping vessel 4. While maintaining the reaction temperature at 90°C, dropping was performed at a constant rate into the reaction tanks over 4.0 hours in dropping tank 1, 4.0 hours in dropping tank 2, 4.0 hours in dropping tank 3, and 4.0 hours in dropping tank 4. After completion of dropping, the temperature was maintained at 90°C for 30 minutes, and then 0.5 parts of Perbutyl O (PBO) was added, and the reaction was continued for another 30 minutes at 90°C. Thereafter, the reaction temperature was raised to 115°C, but the reaction was stopped because the solution became cloudy. The obtained polymer solution (A-4) became cloudy during temperature raising and maturation, and therefore a transparent solution was not obtained.
[Comparative Example 3]
In a separable flask equipped with a cooling tube as a reaction vessel, 128.7 parts of propylene glycol monomethyl ether acetate (PGMEA) and 18.8 parts of acrylic acid (AA) were charged, and after nitrogen replacement, the temperature was raised to 90 ° C. On the other hand, 15.0 parts of N-benzylmaleimide (BzMI), 18.8 parts of acrylic acid, and 60.0 parts of PGMEA were mixed in the dropping vessel 1. In addition, 47.5 parts of vinyl toluene were prepared in the dropping vessel 2. In addition, 2.0 parts of perbutyl O (PBO) and 8.0 parts of PGMEA were mixed in the dropping vessel 3. In addition, 5.7 parts of n-dodecyl mercaptan and 4.3 parts of propylene glycol monomethyl ether acetate were mixed in the dropping vessel 4. While maintaining the reaction temperature at 90°C, attempts were made to drop the solution into the reaction tanks at a uniform rate over 4.0 hours in dropping tank 1, 4.0 hours in dropping tank 2, 4.0 hours in dropping tank 3, and 4.0 hours in dropping tank 4. However, the polymerization solution became cloudy at the initial polymerization stage (A-5), and a transparent solution was not obtained.

The conditions and the physical property evaluation results are shown in Table 1.

Ｆｅｅｄモノマー：滴下する単量体
ＢＰＭｗ：ベースポリマー（変性前の重合体溶液）の重量平均分子量
ＢＰ酸価：ベースポリマー溶液（変性前の重合体溶液）での溶液酸価
ＶＴ：ライオンデル社製、ビニルトルエン
アンテージＷ－４００：川口化学工業株式会社製、２，２′－メチレン－ビス（４－メチル－６－ｔｅｒｔ－ブチルフェノール）
ＰＢＯ：パーブチルＯ（ｔ－ブチルパーオキシ－２－エチルヘキサノエート）

実施例１では、制御Ａ（重合するアクリル酸の総量１００質量％に対し、１５質量％のアクリル酸をあらかじめ反応槽に初期仕込みし、残りのアクリル酸、ベンジルマレイミド及びビニルトルエンを反応槽に滴下）と制御Ｃ（ビニルトルエンを含む単量体溶液の滴下時間が、アクリル酸を含む単量体溶液の滴下時間の１．１４倍）を行うことで溶媒としてＰＧＭＥＡ１００質量％含む（制御Ｂ）透明な重合体溶液が得られた。
実施例２では、制御Ａ（重合するアクリル酸の総量１００質量％に対し、２５質量％のアクリル酸をあらかじめ反応槽に初期仕込みし、残りのアクリル酸、ベンジルマレイミド及びビニルトルエンを反応槽に滴下）と制御Ｃ（ビニルトルエンを含む単量体溶液の滴下時間が、アクリル酸を含む単量体溶液の滴下時間の１．３３倍）を行うことで溶媒としてＰＧＭＥＡ１００質量％含む（制御Ｂ）透明な重合体溶液が得られた。
比較例１では、アクリル酸の初期仕込みはなし（制御Ａなし）、ビニルトルエンを含む単量体溶液の滴下時間が、アクリル酸を含む単量体溶液の滴下時間の１．０７倍（制御Ｃなし）であり、昇温熟成時にアクリル酸の転化率が向上しなかったため、アクリル酸大過剰のポリマーが生じ白濁したと推察している。
比較例２では、アクリル酸の初期仕込みは５質量％（制御Ａなし）、ビニルトルエンを含む単量体溶液の滴下時間が、アクリル酸を含む単量体溶液の滴下時間の１．００倍（制御Ｃなし）であり、昇温熟成時にアクリル酸の転化率が向上しなかったため、アクリル酸大過剰のポリマーが生じ白濁したと推察している。
比較例３では、アクリル酸の初期仕込みは５０質量％（制御Ａなし）、ビニルトルエンを含む単量体溶液の滴下時間が、アクリル酸を含む単量体溶液の滴下時間の１．００倍（制御Ｃなし）であり、重合開始時にアクリル酸大過剰のポリマーが生じ析出し白濁したと推察している。
実施例１及び２と、比較例１～３との比較より、本発明の製造方法の優位性を確認できた。

Feed monomer: Monomer to be dropped BPMw: Weight average molecular weight of base polymer (polymer solution before modification) BP acid value: Solution acid value of base polymer solution (polymer solution before modification) VT: Vinyl toluene manufactured by Lyondell Co., Ltd. Antage W-400: 2,2'-methylene-bis(4-methyl-6-tert-butylphenol manufactured by Kawaguchi Chemical Industry Co., Ltd.
PBO: Perbutyl O (t-butylperoxy-2-ethylhexanoate)

In Example 1, a transparent polymer solution containing 100% by mass of PGMEA as a solvent (Control B) was obtained by carrying out Control A (15% by mass of acrylic acid was initially charged in advance into the reaction tank relative to 100% by mass of the total amount of acrylic acid to be polymerized, and the remaining acrylic acid, benzylmaleimide and vinyltoluene were added dropwise to the reaction tank) and Control C (the drop time of the monomer solution containing vinyltoluene was 1.14 times the drop time of the monomer solution containing acrylic acid).
In Example 2, a transparent polymer solution containing 100% by mass of PGMEA as a solvent (Control B) was obtained by carrying out Control A (25% by mass of acrylic acid was initially charged in advance into the reaction tank relative to 100% by mass of the total amount of acrylic acid to be polymerized, and the remaining acrylic acid, benzylmaleimide and vinyltoluene were added dropwise to the reaction tank) and Control C (the drop time of the monomer solution containing vinyltoluene was 1.33 times the drop time of the monomer solution containing acrylic acid).
In Comparative Example 1, there was no initial charge of acrylic acid (no control A), and the drop time of the monomer solution containing vinyltoluene was 1.07 times that of the monomer solution containing acrylic acid (no control C), and the conversion rate of acrylic acid did not improve during temperature-raising and maturation, so it is presumed that a polymer with a large excess of acrylic acid was produced, causing the mixture to become cloudy.
In Comparative Example 2, the initial charge of acrylic acid was 5% by mass (without Control A), the dropwise addition time of the monomer solution containing vinyltoluene was 1.00 times the dropwise addition time of the monomer solution containing acrylic acid (without Control C), and the conversion rate of acrylic acid did not improve during temperature-raising and maturation, so it is presumed that a polymer with a large excess of acrylic acid was produced, causing the mixture to become cloudy.
In Comparative Example 3, the initial charge of acrylic acid was 50% by mass (without Control A), and the dropwise addition time of the monomer solution containing vinyltoluene was 1.00 times the dropwise addition time of the monomer solution containing acrylic acid (without Control C), and it is presumed that a polymer containing a large excess of acrylic acid was generated at the start of polymerization, which precipitated and turned cloudy.
By comparing Examples 1 and 2 with Comparative Examples 1 to 3, the superiority of the manufacturing method of the present invention was confirmed.

The method for producing a polymer solution of the present invention can efficiently and easily obtain a transparent polymer solution containing an ester-based solvent as a main component. Therefore, the polymer solution can be suitably used for various optical components such as colored layers of color filters used in liquid crystal display devices and solid-state imaging devices, black matrices, photospacers, black column spacers, inks, printing plates, printed wiring boards, semiconductor devices, and photoresists.

Claims (5)

A method for producing a polymer solution obtained by polymerizing a monomer containing an acid group-containing monomer and an aromatic vinyl monomer, characterized in that the dripping time of the monomer solution containing the aromatic vinyl monomer into the reaction vessel is 1.10 times or more the dripping time of the monomer solution containing the acid group-containing monomer, and the solvent for the obtained polymer solution is an ester solvent in an amount of 90 mass% or more relative to 100 mass% of the total amount of the solvent. A method for producing a polymer solution obtained by polymerizing an acid group-containing monomer and a monomer containing an aromatic vinyl monomer, the method being characterized in that 10% by mass to 48% by mass of the acid group-containing monomer is charged in advance into a reaction tank relative to 100% by mass of the total amount of the acid group-containing monomers to be polymerized, and the dripping time of the monomer solution containing the aromatic vinyl monomer in dripping the remaining monomer solution into the reaction tank is 1.10 times or more longer than the dripping time of the monomer solution containing the acid group-containing monomer, and the solvent for the obtained polymer solution is an ester solvent in an amount of 90% by mass or more relative to 100% by mass of the total amount of the solvent. The method for producing a polymer solution according to claim 1 or 2, characterized in that the monomer solution further contains a monomer capable of introducing a ring structure into the main chain. The method for producing a polymer solution according to any one of claims 1 to 3 further comprises reacting the polymer solution with a compound having a functional group capable of bonding to an acid group and a polymerizable double bond to introduce a side chain double bond. A method for producing a photosensitive resin composition, comprising mixing the polymer solution obtained by the method for producing a photosensitive resin composition according to any one of claims 1 to 4 with a photopolymerization initiator and a polyfunctional polymerizable monomer.

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