JP7706484B2 - Alkaline developable polymer and alkaline developable polymer composition - Google Patents

Description

The present invention relates to an alkaline developable polymer and an alkaline developable polymer composition.

Alkaline-developable polymers are used as patterning materials for photoresists and the like in the manufacture of printed wiring boards, semiconductor packages, insulating films, printing plates, spacers for liquid crystal cells, color filters, black matrices, and the like. Alkaline-developable polymers are polymers that are used to develop the parts exposed to ultraviolet light by hardening them and the parts not exposed to ultraviolet light by dissolving them with an alkali.

As such alkaline developable polymers, various polymers with improved properties such as developability, heat resistance, and patterning ability have been developed (Patent Documents 1 to 3). For example, a curable polymer has been proposed in which a radically polymerizable double bond has been introduced into a polymer synthesized from a monomer blend containing a maleimide monomer, acrylic acid, and an acrylic acid ester, but not containing methacrylic acid and its esters (Patent Document 1). In addition, an alkaline developable resin obtained by using an epoxy resin, an unsaturated monocarboxylic acid, an unsaturated monocarboxylic acid anhydride, and a dicarboxylic acid anhydride has been proposed (Patent Document 2). Furthermore, an alkaline developable resin has been proposed by reacting a compound having a hydroxyl group and an epoxy group with the hydroxyl group of a phenolic resin, and further reacting the hydroxyl group of the product obtained with a polybasic acid anhydride (Patent Document 3).

Patent No. 5671369 Patent No. 6721858 International Publication No. 2014/010204

In recent years, there has been a demand for even higher definition patterning, as well as for further improvements in the durability and heat resistance of the cured product obtained by patterning. In addition, in order to improve productivity, there is a demand for resins that can be developed more quickly. Furthermore, from the standpoint of cost and environmental impact, there is a demand for resins that can be easily developed even with low-concentration alkaline developers. There is also a demand for compositions that contain such developable resins and that suppress the amount of outgassing generated before and after the resin is cured as much as possible.

The present invention has been made in consideration of the problems associated with the conventional techniques, and it is an object of the present invention to provide an alkali-developable polymer that allows high-definition patterning, has good curing properties and developability, and is capable of forming a cured product with excellent hardness and heat resistance, and can be easily developed even when a low-concentration alkali developer is used. Another object of the present invention is to provide an alkali-developable polymer composition that contains this alkali-developable polymer and suppresses the generation of outgassing.

That is, according to the present invention, there is provided the following alkaline developable polymer.
[1] An alkali-developable polymer which is a reaction product obtained by reacting an A'B' block copolymer which satisfies the following requirements (1) to (3) with an epoxy group-containing (meth)acrylate, the alkali-developable polymer being an AB block copolymer including a polymer chain A and a polymer chain B, the number average molecular weight being 7,000 to 20,000, the molecular weight distribution (weight average molecular weight/number average molecular weight) being 1.2 to 1.8, the acid value being 40 to 100 mg/KOH, and the unsaturated group equivalent being 900 to 3,000 g/mol.
[Requirement (1)]
The block copolymer has a number average molecular weight of 6,000 to 18,000, a molecular weight distribution of 1.1 to 1.7, and an acid value of 70 to 130 mgKOH/g, and includes a polymer chain A' and a polymer chain B'.
[Requirement (2)]
The polymer chain A' is a polymer block which contains 15 to 55 mass% of structural units (ia) derived from at least one monomer selected from the group consisting of methyl methacrylate and benzyl methacrylate, 15 to 60 mass% of structural units (ii-a) derived from at least one monomer selected from the group consisting of cyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, 4-t-butylcyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate, 5 to 30 mass% of structural units (iii-a) derived from a methacrylate having a hydroxyl group, and 5 to 30 mass% of structural units (iv-a) derived from mono(2-methacryloyloxyethyl)succinate, and the total content of the structural units (ia) to (iv-a) is 90 mass% or more, the number average molecular weight is 4,000 to 10,000, and the molecular weight distribution is 1.1 to 1.6.
[Requirement (3)]
The polymer chain B' is a polymer block which contains 10 to 60 mass% of structural units (ib) derived from at least one monomer selected from the group consisting of methyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate, and 40 to 90 mass% of structural units (ii-b) derived from mono(2-methacryloyloxyethyl)succinate, the total content of the structural units (ib) and (ii-b) being 90 mass% or more, and has a number average molecular weight of 2,000 to 8,000.
[2] The alkali-developable polymer according to [1] above, wherein the epoxy group-containing (meth)acrylate is (3,4-epoxycyclohexyl)methyl methacrylate.

According to the present invention, there is also provided the following alkaline developable polymer composition.
[3] An alkali-developable polymer composition comprising the alkali-developable polymer according to [1] or [2] above and an organic solvent, wherein the organic solvent contains 50 mass % or more of at least one selected from the group consisting of propyl acetate, butyl acetate, and methoxycyclopentane.

According to the present invention, it is possible to provide an alkali-developable polymer that is capable of high-definition patterning, has good curing properties and developability, and is capable of forming a cured product with excellent hardness and heat resistance, and can be easily developed even when a low-concentration alkaline developer is used. Furthermore, according to the present invention, it is possible to provide an alkali-developable polymer composition that contains this alkali-developable polymer and suppresses the generation of outgassing.

<Alkaline Developable Polymer>
Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the alkali-developable polymer of the present invention is a reaction product obtained by reacting a specific A'B' block copolymer with an epoxy group-containing (meth)acrylate. The alkali-developable polymer of this embodiment is an AB block copolymer containing polymer chain A and polymer chain B, having a number average molecular weight of 7,000 to 20,000, a molecular weight distribution (weight average molecular weight/number average molecular weight) of 1.2 to 1.8, an acid value of 40 to 100 mg/KOH, and an unsaturated group equivalent of 900 to 3,000 g/mol. Hereinafter, the alkali-developable polymer of this embodiment will be described in detail.

(A'B' Block Copolymer)
The A'B' block copolymer is a precursor of the AB block copolymer which is the alkaline developable polymer of this embodiment. The A'B' block copolymer is a block copolymer which satisfies the requirements (1) to (3) which will be described in detail below.

[Requirement (1)]
The A'B' block copolymer is a block copolymer containing a polymer chain A' and a polymer chain B', having a number average molecular weight of 6,000 to 18,000, a molecular weight distribution of 1.1 to 1.7, and an acid value of 70 to 130 mgKOH/g.

The number average molecular weight (Mn) of the A'B' block copolymer is 6,000 to 18,000, preferably 7,000 to 16,000. If the Mn of the A'B' block copolymer is less than 6,000, the molecular weight is too small, and the durability of the cured product of the AB block copolymer (alkaline developable polymer) obtained using this A'B' block copolymer is insufficient. On the other hand, if the Mn of the A'B' block copolymer is more than 18,000, the molecular weight is too large, and it may take a long time to dissolve the alkaline developable polymer obtained using this A'B' block copolymer in an alkaline developer (alkaline developer). Note that the number average molecular weight (Mn) and weight average molecular weight (Mw) in this specification are both values calculated in terms of polystyrene measured by gel permeation chromatography (GPC).

The molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) of the A'B' block copolymer is 1.1 to 1.7, preferably 1.2 to 1.6. In other words, the A'B' block copolymer is a polymer with a relatively uniform molecular weight. This uniformity in molecular weight results in uniform molecular chain properties, which improves the developability of the AB block copolymer (alkali developable polymer) obtained using this A'B' block copolymer. In addition, since it dissolves uniformly, the pixel shape is good and it is less likely to become peeled off even when dissolved.

The AB block copolymer must have a sufficient acid value to be developed in an alkaline environment. Therefore, the A'B' block copolymer, which is the precursor of the AB block copolymer, must also have a sufficient acid value. That is, the acid value of the A'B' block copolymer is 70 to 130 mgKOH/g, preferably 80 to 120 mgKOH/g. If the acid value of the A'B' block copolymer is less than 70 mgKOH/g, the amount of carboxyl groups remaining after the reaction with the epoxy group-containing (meth)acrylate may be small, and the alkaline developability may be reduced. On the other hand, if the acid value of the A'B' block copolymer is more than 130 mgKOH/g, even if the epoxy group-containing (meth)acrylate is reacted, too many carboxyl groups remain. Therefore, while there is a possibility that the developability may be improved, the water resistance of the cured product formed may be reduced.

[Requirement (2)]
The polymer chain A' (hereinafter also referred to as "A'chain") is a polymer block containing 15 to 55% by mass of the structural unit (ia), 15 to 60% by mass of the structural unit (ii-a), 5 to 30% by mass of the structural unit (iii-a), and 5 to 30% by mass of the structural unit (iv-a) (wherein the total of the structural units (ia) to (iv-a) is 100% by mass). The structural unit (ia) is a structural unit derived from at least one monomer selected from the group consisting of methyl methacrylate and benzyl methacrylate. The structural unit (ii-a) is a structural unit derived from at least one monomer selected from the group consisting of cyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, 4-t-butylcyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate. The structural unit (iii-a) is a structural unit derived from a methacrylate having a hydroxyl group. The structural unit (iv-a) is a structural unit derived from mono(2-methacryloyloxyethyl) succinate. The total content of the structural units (ia) to (iv-a) in the A' chain is 90 mass% or more. The number average molecular weight of the A' chain is 4,000 to 10,000, and the molecular weight distribution is 1.1 to 1.6.

The A' chain contains a structural unit (iv-a) derived from mono(2-methacryloyloxyethyl) succinate. The carboxy group in this structural unit (iv-a) reacts with the epoxy group of the epoxy group-containing (meth)acrylate to form a polymer chain A that constitutes the AB block copolymer. The polymer chain A thus formed has an unsaturated bond and has little or no remaining carboxy group, or only a small amount if any, and therefore has poor water solubility. For this reason, a cured film having water resistance can be formed by using an AB block copolymer containing this polymer chain A.

The content of the structural unit (iv-a) in the A' chain is 5 to 30% by mass, preferably 10 to 25% by mass. If the content of the structural unit (iv-a) in the A' chain is less than 5% by mass, the amount of unsaturated groups introduced into the AB block copolymer is small, resulting in insufficient curability. On the other hand, if the content of the structural unit (iv-a) in the A' chain is more than 30% by mass, a large amount of carboxyl groups remain even after reaction with an epoxy group-containing (meth)acrylate, resulting in reduced water resistance of the cured film that is formed.

Succinic acid mono(2-methacryloyloxyethyl) has a long ester residue. Furthermore, when the carboxy group in the structural unit (iv-a) is reacted with an epoxy group-containing (meth)acrylate, the ester residue becomes even longer, so that the glass transition temperature (Tg) of the polymer chain A becomes lower and the cured film formed tends to be soft. For this reason, the A' chain contains a structural unit (ii-a) derived from at least one monomer selected from the group consisting of cyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, 4-t-butylcyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate. By including such a structural unit (ii-a) having a cycloalkyl group, the glass transition temperature (Tg) of the polymer chain A formed can be increased, and a hard cured film can be formed.

In the A' chain, the content of the structural unit (ii-a) is 15 to 60% by mass, preferably 20 to 55% by mass. If the content of the structural unit (ii-a) in the A' chain is less than 15% by mass, it becomes difficult to increase the hardness of the cured film formed. On the other hand, if the content of the structural unit (ii-a) in the A' chain is more than 60% by mass, the cycloalkyl group is highly hydrophobic, and development may become difficult.

The A' chain further contains a structural unit (i-a) derived from at least one monomer selected from the group consisting of methyl methacrylate and benzyl methacrylate. The structural unit (i-a) is a water-insoluble or poorly water-soluble structural unit derived from a monomer with a small molecular weight or a monomer having an aromatic ring. By containing such a structural unit (i-a), it is possible to obtain an AB block copolymer capable of forming a cured film that has both developability and hardness. Note that if the number of carbon atoms is greater than that of methyl methacrylate, the hydrophobicity becomes too high, making alkaline development difficult and the cured film formed may be soft.

In the A' chain, the content of the structural unit (i-a) is 15 to 55% by mass, preferably 20 to 50% by mass. If the content of the structural unit (i-a) in the A' chain is less than 15% by mass, the developability may decrease. On the other hand, if the content of the structural unit (i-a) in the A' chain is more than 55% by mass, the polymer chain A may become soft.

The A' chain further contains a structural unit (iii-a) derived from a methacrylate having a hydroxyl group. By containing the hydrophilic structural unit (iii-a) having a hydroxyl group, the alkaline developability of the AB block copolymer can be improved. Examples of methacrylates having a hydroxyl group include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2,3-dihydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxypropyl methacrylate. Of these, 2-hydroxyethyl methacrylate is preferred.

The content of the structural unit (iii-a) in the A' chain is 5 to 30% by mass, preferably 7.5 to 25% by mass. If the content of the structural unit (iii-a) in the A' chain is less than 5% by mass, the alkaline developability decreases. On the other hand, if the content of the structural unit (iii-a) in the A' chain is more than 30% by mass, the hydrophilicity becomes too high, and the water resistance of the cured film formed decreases. In addition, the cured film may swell in water or become sticky.

In the A' chain, the total content of the structural units (i-a) to (iv-a) is 90% by mass or more, and preferably 95% by mass or more. It is particularly preferable that the total content of the structural units (i-a) to (iv-a) in the A' chain is 100% by mass, i.e., the A' chain is substantially composed only of the structural units (i-a) to (iv-a).

The A' chain may further contain other structural units in addition to the structural units (i-a) to (iv-a). Examples of monomers forming the other structural units include methacrylic acid and methacrylates. Examples of methacrylates include methacrylates having an alkyl group or an alkenyl group, such as ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate; hydroxyl group-containing methacrylates, such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 3-hydroxypropyl methacrylate; glycol ether-based methacrylates, such as (poly)ethylene glycol monomethyl ether methacrylate, (poly)ethylene glycol monoethyl ether methacrylate, and (poly)propylene glycol monomethyl ether methacrylate; amino group-containing methacrylates, such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and t-butylaminoethyl methacrylate; and the like.

The number average molecular weight (Mn) of the A' chain is 4,000 to 10,000, preferably 4,500 to 9,500. If the Mn of the A' chain is less than 4,000, the durability and water resistance of the cured film will be insufficient. On the other hand, if the Mn of the A' chain is more than 10,000, the developability will decrease.

The molecular weight distribution (PDI) of the A' chain is 1.1 to 1.6, preferably 1.2 to 1.5. In other words, the A' chain is a polymer block with a relatively uniform molecular weight. This uniformity in molecular weight can improve the developability of the AB block copolymer (alkali developable polymer) obtained using the A'B' block copolymer containing this A' chain. In addition, since it dissolves uniformly, the pixel shape is good and it is less likely to become peeled off even when dissolved.

[Requirement (3)]
The polymer chain B' (hereinafter also referred to as "B'chain") is a polymer block containing 10 to 60% by mass of the structural unit (ib) and 40 to 90% by mass of the structural unit (ii-b) (wherein the total of the structural units (ib) and (ii-b) is 100% by mass). The structural unit (ib) is a structural unit derived from at least one monomer selected from the group consisting of methyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate. The structural unit (ii-b) is a structural unit derived from mono(2-methacryloyloxyethyl) succinate. The total content of the structural units (ib) and (ii-b) in the B' chain is 90% by mass or more. The number average molecular weight of the B' chain is 2,000 to 8,000.

The B' chain contains a structural unit (ii-b) derived from mono(2-methacryloyloxyethyl) succinate. By introducing a large amount of this structural unit (ii-b), a large amount of carboxyl groups can be introduced into the B' chain. By introducing a predetermined amount of carboxyl groups into the B' chain, many carboxyl groups can be left even when reacting with an epoxy group-containing (meth)acrylate. The remaining carboxyl groups are neutralized by the alkali in the alkaline developer and dissolve in water, improving the alkaline developability. In addition, the carboxyl groups are present at a position away from the main chain composed of polymethacrylate. This makes it easier to come into contact with the alkali in the alkaline developer and to undergo a neutralization reaction, shortening the dissolution time and improving the alkaline developability. Furthermore, by reacting with an epoxy group-containing (meth)acrylate, unsaturated bonds are densely introduced, so that the crosslink density can be increased and a cured product with high hardness and excellent heat resistance can be formed.

In the B' chain, the content of the structural unit (ii-b) is 40 to 90% by mass, preferably 45 to 85% by mass. If the content of the structural unit (ii-b) in the B' chain is less than 40% by mass, the amount of carboxyl groups remaining when reacted with the epoxy group-containing (meth)acrylate is reduced, resulting in poor developability. On the other hand, if the content of the structural unit (ii-b) in the B' chain is made to exceed 90% by mass, the polymerization rate decreases due to the large molecular weight of the monomer, and the monomer is more likely to remain.

The B' chain further contains a structural unit (i-b) derived from at least one monomer selected from the group consisting of methyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate. By containing such a structural unit (i-b), it is possible to obtain an AB block copolymer capable of forming a cured film having both developability and hardness, and it is possible to increase the glass transition temperature (Tg) of the formed polymer chain B and form a hard cured film. Furthermore, by containing such a structural unit (i-b), it is possible to suppress the remaining of mono(2-methacryloyloxyethyl) succinate, which has a large molecular weight and is difficult to increase the polymerizability of.

In the B' chain, the content of the structural unit (i-b) is 10 to 60% by mass, preferably 5 to 50% by mass. If the content of the structural unit (i-b) in the B' chain is less than 10% by mass, the copolymerizability of mono(2-methacryloyloxyethyl) succinate is insufficient, and mono(2-methacryloyloxyethyl) succinate may remain. On the other hand, if the content of the structural unit (i-b) in the B' chain is more than 60% by mass, the content of the structural unit (ii-b) is relatively reduced, resulting in reduced developability.

The structural unit (i-b) is preferably a structural unit formed from at least one monomer selected from the group consisting of methyl methacrylate and benzyl methacrylate, and at least one monomer selected from the group consisting of cyclohexyl methacrylate and dicyclopentenyloxyethyl methacrylate. This makes it possible to adjust the glass transition temperature (Tg) of the B' chain, as well as the hardness and stickiness of the cured film formed.

In the B' chain, the total content of the structural units (i-b) and (ii-b) is 90% by mass or more, and preferably 95% by mass or more. It is particularly preferable that the total content of the structural units (i-b) and (ii-b) in the B' chain is 100% by mass, i.e., the B' chain is substantially composed only of the structural units (i-b) to (ii-b).

The B' chain may further contain other structural units in addition to the structural units (i-b) and (ii-b). Examples of monomers that form the other structural units include methacrylic acid and the above-mentioned methacrylates.

The number average molecular weight (Mn) of the B' chain is 2,000 to 8,000, preferably 3,000 to 7,000. The Mn of the B' chain is the value obtained by subtracting the Mn of the A' chain from the Mn of the A'B' block copolymer. If the Mn of the B' chain is less than 2,000, the water-soluble polymer block becomes small, and alkaline developability decreases. On the other hand, if the Mn of the B' chain is more than 8,000, the water resistance of the cured film decreases, even though the film contains a water-insoluble or poorly soluble A' chain.

(Method for Producing A'B' Block Copolymer)
Since the A'B' block copolymer has a special structure, it is difficult to produce it by normal radical polymerization. For this reason, it is preferable to produce the A'B' block copolymer by a polymerization method having living properties, such as a living anionic polymerization method, a living cationic polymerization method, and a living radical polymerization method. Among them, it is preferable to produce it by a living radical polymerization method from the viewpoints of conditions, materials, and equipment. Furthermore, the RTCP method and the RCMP method, which use an organic compound as a catalyst and an organic iodide as a polymerization initiator compound, are preferable. These methods use relatively safe commercially available compounds, do not use heavy metals or special compounds, and are advantageous in terms of cost and purification. Furthermore, by making the growth terminal a tertiary iodine, a block structure with good accuracy can be easily formed by general equipment.

Either the A' chain or the B' chain may be polymerized first. It is preferable to polymerize the A' chain and then the B' chain. If the B chain is polymerized first, and if mono(2-methacryloyloxyethyl) succinate remains in the polymerization system, a large amount of the structural unit (iv-a) may be introduced into the A' chain that is polymerized later.

The A'B' block copolymer is preferably produced by solution polymerization. The organic solvent used in the solution polymerization may be the organic solvent used in the alkali-developable polymer composition described below. After polymerization in the organic solvent, the polymer may be precipitated by adding a poor solvent, and the resulting solid may be dissolved in the organic solvent.

(AB block copolymer)
The alkali-developable polymer of this embodiment is an AB block copolymer containing a polymer chain A (hereinafter also simply referred to as "A chain") and a polymer chain B (hereinafter also simply referred to as "B chain"), which are reaction products obtained by reacting the above-mentioned A'B' block copolymer with an epoxy group-containing (meth)acrylate. All of the constituent monomers of the alkali-developable polymer (AB block copolymer) of this embodiment are methacrylate-based monomers such as methacrylic acid esters. In other words, the monomers forming the constituent units in the alkali-developable polymer of this embodiment are preferably substantially composed only of methacrylate-based monomers such as methacrylic acid esters.

Examples of epoxy group-containing (meth)acrylates include glycidyl (meth)acrylate and (3,4-epoxycyclohexyl)methyl (meth)acrylate. Among these, (3,4-epoxycyclohexyl)methyl methacrylate, which has a cycloalkyl ring, is preferred from the standpoints of availability and improving the hardness of the polymer.

The number average molecular weight (Mn) of the AB block copolymer is 7,000 to 20,000, preferably 8,000 to 18,000. If the Mn of the AB block copolymer is less than 7,000, the molecular weight is too small, and the durability of the cured film is insufficient. On the other hand, if the Mn of the AB block copolymer is more than 20,000, the molecular weight is too large, and the alkaline developability is reduced.

The molecular weight distribution (PDI) of the AB block copolymer is 1.2 to 1.8, preferably 1.2 to 1.7. In other words, the AB block copolymer is a polymer with a relatively uniform molecular weight. This uniformity in molecular weight results in uniform molecular chain properties, which can improve developability. In addition, since it dissolves easily and uniformly, the pixel shape is good and it is less likely to peel off when dissolved.

Since the AB block copolymer is a reaction product of the A'B' block copolymer and the epoxy group-containing (meth)acrylate, the acid value of the AB block copolymer is smaller than that of the A'B' block copolymer. That is, the acid value of the AB block copolymer is 40 to 100 mg KOH/g, preferably 45 to 90 mg KOH/g. If the acid value of the AB block copolymer is less than 40 mg KOH/g, development is not possible or the development speed (dissolution speed) is slow. On the other hand, if the acid value of the AB block copolymer is more than 100 mg KOH/g, the amount of remaining carboxyl groups is too large, and the water resistance of the cured film is reduced. The acid value of the AB block copolymer can be controlled by adjusting the acid value of the A'B' block copolymer or the number of moles of the epoxy group-containing (meth)acrylate to be reacted with the A'B' block copolymer.

The unsaturated group equivalent of the AB block copolymer is 900 to 3,000 g/mol, preferably 1,000 to 2,800 g/mol. If the unsaturated group equivalent of the AB block copolymer is less than 900 g/mol, it becomes difficult to increase the crosslink density of the cured film formed, and the strength of the cured film is insufficient. On the other hand, if the unsaturated group equivalent of the AB block copolymer is more than 3,000 g/mol, the alkaline developability decreases.

The A'B' block copolymer and the epoxy group-containing (meth)acrylate can be reacted according to a conventional method. For example, they may be reacted at a temperature of 120°C or less in the presence of a catalyst such as a phosphorus compound such as triphenylphosphine or a quaternary ammonium salt such as tetrabutylammonium bromide. In order to prevent the unsaturated bonds of the epoxy group-containing (meth)acrylate from reacting or polymerizing, a polymerization inhibitor such as hydroquinone may be added or air may be fed. The end point of the reaction can be confirmed by measuring IR with an infrared spectrophotometer to confirm the disappearance of absorption due to the epoxy group; measuring the epoxy equivalent to confirm that the epoxy equivalent becomes zero; measuring the acid value to confirm that the acid value becomes a predetermined value; etc.

<Alkaline Developable Polymer Composition>
An embodiment of the alkali-developable polymer composition of the present invention contains the above-mentioned alkali-developable polymer and an organic solvent. The organic solvent is at least one selected from the group consisting of propyl acetate, butyl acetate, and methoxycyclopentane. The alkali-developable polymer composition of this embodiment (hereinafter also referred to as "resist ink composition") will be described in detail below.

In general, when an alkali-developable resist composition containing a high-boiling organic solvent is used, the organic solvent remains in the pre-bake and post-bake processes, and the remaining organic solvent becomes outgassed and easily contaminates mechanical devices and the like. In contrast, the alkali-developable polymer composition (resist ink composition) of this embodiment uses at least one organic solvent with a relatively low boiling point selected from the group consisting of propyl acetate, butyl acetate, and methoxycyclopentane, which can dissolve the alkali-developable polymer. Under normal pressure conditions, the boiling points of propyl acetate are 102°C, butyl acetate are 126°C, and methoxycyclopentane are 106°C. These organic solvents have high vapor pressure, are easily volatilized, and are unlikely to remain even after baking.

In the organic solvent contained in the alkaline developable polymer composition, the content of at least one selected from the group consisting of propyl acetate, butyl acetate, and methoxycyclopentane is 50% by mass or more, and preferably 80% by mass or more. It is particularly preferable that the content of at least one selected from the group consisting of propyl acetate, butyl acetate, and methoxycyclopentane in the organic solvent is 100% by mass, that is, the organic solvent is substantially composed of at least one selected from the group consisting of propyl acetate, butyl acetate, and methoxycyclopentane.

The organic solvent in the alkaline developable polymer composition may further contain other organic solvents in addition to the above organic solvents. Examples of other organic solvents include propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, N-methylpyrrolidone, and γ-butyrolactone.

There are no particular limitations on the content of the alkaline developable polymer (AB block copolymer) in the alkaline developable polymer composition, and the viscosity of the alkaline developable polymer composition, and these may be set appropriately depending on the application. The alkaline developable polymer composition can be produced, for example, by reacting an epoxy group-containing (meth)acrylate with an A'B' block copolymer formed by polymerization in an organic solvent, and then diluting the mixture by adding an organic solvent to achieve the desired content of the AB block copolymer.

The alkali-developable polymer composition may contain additives. Examples of additives include photopolymerizable monomers, photopolymerizable oligomers, ultraviolet absorbers, light stabilizers, photopolymerization initiators, photosensitizers, acid-base generators, antioxidants, leveling agents, defoamers, thickeners, and colorants such as pigments.

The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. Note that "parts" and "%" in the examples and comparative examples are based on mass unless otherwise specified.

<Preparation of Alkaline Developable Polymer>
(Synthesis Example 1)
239.1 parts of propylene glycol monomethyl ether acetate (PGMAc), 4.0 parts of iodine, 14.8 parts of 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70) (trade name "V-70", Fujifilm Wako Pure Chemical Industries, Ltd.), 0.7 parts of diphenylmethane (DPM), 58.2 parts of benzyl methacrylate (BzMA), 58.2 parts of cyclohexyl methacrylate (CHMA), 32.5 parts of 2-hydroxyethyl methacrylate (HEMA), and 27.2 parts of succinic acid mono (2-methacryloyloxyethyl) (SA) (trade name "SA", Shin-Nakamura Chemical Co., Ltd., Mw 230.21) were placed in a reaction vessel. The mixture was heated to 45 ° C. while flowing nitrogen, stirred, and polymerized for 4 hours to form an A' chain (polymer). A part of the sample was sampled, and the solid content measured using a moisture meter was 39.7%, and the polymerization conversion calculated from the solid content was 88.2%. The molecular weight of the polymer was measured by gel permeation chromatography (GPC) using a differential refractive index detector with tetrahydrofuran as a developing solvent. As a result, the number average molecular weight (Mn) of the polymer in terms of polystyrene was 4,700, the molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) was 1.28, and the peak top molecular weight (PT) was 6,200. The theoretical acid value of the A' chain was 37.5 mg KOH / g. The theoretical acid value was calculated as follows.
Amount of SA in 1 g of A' chain (g)
= 27.2 / (58.2 + 58.2 + 32.5 + 27.2) = 0.154
・Acid value (mgKOH/g)
= (0.154/230.21) x 56.11 x 1,000 = 37.5

After adding 10.6 parts of V-70, a monomer solution containing 74.5 parts of BzMA, 138.1 parts of SA, and 272.8 parts of PGMAc was further added. The mixture was heated to 45°C and stirred, and polymerized for 4 hours to form B' chains, obtaining a polymer. A portion was sampled and the solid content was measured, confirming that the target product was obtained almost quantitatively. The Mn of the obtained polymer was 10,100, the PDI was 1.55, and the PT was 15,200. Since the Mn was larger than that of the A' chain, the obtained polymer is considered to be an A'B' block copolymer. The Mn of the B' chain, calculated by subtracting the Mn of the A' chain from the Mn of the A'B' block copolymer, was 5,400.

0.8 parts of 4-methoxyphenol (MEHQ), 3.9 parts of tetrabutylammonium bromide (TBAB), and 58.9 parts of (3,4-epoxycyclohexyl)methyl methacrylate (M100) (product name "Cyclomer M100", Daicel Corporation, Mw 196.2) were added. The mixture was heated to 90°C and reacted for 3 hours to obtain a solution containing an AB block copolymer (a solution of alkaline developable polymer EP-1). A portion was sampled and IR was measured using an infrared spectrophotometer to confirm the disappearance of the absorption peak derived from the epoxy group, thereby confirming the completion of the reaction. The solid content was 47.5%. After dilution with toluene and ethanol, the acid value (actual acid value) was measured by acid-base titration using a phenolphthalein solution as an indicator and a 0.1% ethanolic potassium hydroxide solution, and was 53.5 mg KOH/g.

(Synthesis Examples 2 to 5)
Solutions of alkali-developable polymers EP-2 to EP-5 were obtained in the same manner as in Synthesis Example 1 above, except that the types and amounts (unit: parts) of various materials shown in Tables 1-1 and 1-2 were used. The physical properties and the like of the obtained alkali-developable polymers are shown in Tables 1-1 and 1-2. The meanings of the abbreviations in Tables 1-1 and 1-2 are as follows:
MMA: methyl methacrylate TMCHMA: 3,3,5-trimethylcyclohexyl methacrylate TBCHMA: 4-t-butylcyclohexyl methacrylate FA513M: dicyclopentanyl methacrylate (product name "Fancryl FA513M", manufactured by Showa Denko Materials Co., Ltd.)
FA512M: dicyclopentenyloxyethyl methacrylate (product name "Fancryl FA512M", manufactured by Showa Denko Materials Co., Ltd.)
GMA: glycidyl methacrylate SA·M100: adduct of SA and M100 (Mw 426.41)
・SA・GMA: Adduct of SA and GMA (Mw 372.36)

The "unsaturated group equivalent" in Tables 1-1 and 1-2 was calculated as follows. For example, in the case of Synthesis Example 1, 1 g of polymer contains 0.286 g of SA·M100, so the amount (mol) of SA·M100 in 1 g of polymer is "0.286/426.41 = 0.0006707 mol." Therefore, the unsaturated group equivalent of the alkali-developable polymer EP-1 obtained in Synthesis Example 1 can be calculated as "1/0.0006707 = 1,491 g/mol."

(Synthesis Example 6)
PGMAc 119.5 parts, propyl acetate 119.6 parts, iodine 4.0 parts, V-70 14.8 parts, DPM 0.7 parts, BzMA 33.2 parts, CHMA 99.5 parts, HEMA 16.2 parts, and SA 27.2 parts were placed in a reaction vessel. The mixture was heated to 45 ° C. and stirred while flowing nitrogen, and polymerized for 4 hours to form an A' chain (polymer). The solid content was 41.5%, and the polymerization conversion calculated from the solid content was 92.2%. The Mn measured by GPC was 5,100, the PDI was 1.36, and the PT was 6,900. The theoretical acid value of the A' chain was 37.5 mg KOH / g.

After adding 7.1 parts of V-70, a monomer solution containing 12.4 parts of BzMA, 37.2 parts of CHMA, 92.1 parts of SA, 90.9 parts of PGMAc, and 91.0 parts of propyl acetate was further added. The mixture was heated to 45°C and stirred, and polymerized for 4 hours to form B' chains, obtaining a polymer. A portion was sampled and the solid content was measured, confirming that the target product was obtained almost quantitatively. The Mn of the obtained polymer was 8,000, the PDI was 1.45, and the PT was 11,700. Since the Mn was larger than that of the A' chain, the obtained polymer is considered to be an A'B' block copolymer. The Mn of the B' chain, calculated by subtracting the Mn of the A' chain from the Mn of the A'B' block copolymer, was 2,900.

0.5 parts of MEHQ, 2.6 parts of TBAB, and 39.3 parts of M100 were added. The mixture was heated to 90°C and reacted for 3 hours to obtain a solution containing an AB block copolymer (a solution of alkaline developable polymer EP-6). A portion was sampled and IR was measured using an infrared spectrophotometer to confirm the disappearance of the absorption peak derived from the epoxy group, thereby confirming the completion of the reaction. The solid content was 47.8%. The measured acid value was 52.2 mg KOH/g.

(Synthesis Examples 7 and 8)
Solutions of alkali-developable polymers EP-7 and 8 were obtained in the same manner as in Synthesis Example 6 above, except for using various materials whose types and amounts (unit: parts) are shown in Table 2. The physical properties of the obtained alkali-developable polymers are shown in Table 2.

Comparative Synthesis Example 1
PGMAc 239.0 parts, iodine 4.0 parts, V-70 14.8 parts, DPM 0.7 parts, BzMA 58.2 parts, CHMA 58.2 parts, HEMA 32.5 parts, and methacrylic acid (MAA) 27.2 parts were placed in a reaction vessel. The mixture was heated to 42 ° C. and stirred while flowing nitrogen, and polymerized for 4.5 hours to form an A' chain (polymer). The solid content was 38.4%, and the polymerization conversion calculated from the solid content was 85.3%. The Mn measured by GPC was 5,000, the PDI was 1.26, and the PT was 6,400. The theoretical acid value of the A' chain was 100.4 mg KOH / g.

After adding 10.5 parts of V-70, a monomer solution containing 141.0 parts of BzMA, 68.9 parts of MAA, and 731.7 parts of PGMAc was further added. The mixture was heated to 42°C and stirred, and polymerized for 4 hours to form B' chains, obtaining a polymer. A portion was sampled and the solid content was measured, confirming that the target product was obtained almost quantitatively. The Mn of the obtained polymer was 9,400, the PDI was 1.49, and the PT was 14,200. Since the Mn was larger than that of the A' chain, the obtained polymer is considered to be an A'B' block copolymer. The Mn of the B' chain, calculated by subtracting the Mn of the A' chain from the Mn of the A'B' block copolymer, was 4,400.

0.3 parts of MEHQ, 5.2 parts of TBAB, and 78.5 parts of M100 were added. The mixture was heated to 90°C and reacted for 3 hours to obtain a solution containing an AB block copolymer (a solution of alkaline developable polymer HEP-1). A portion was sampled and IR was measured using an infrared spectrophotometer to confirm the disappearance of the absorption peak derived from the epoxy group, thereby confirming the completion of the reaction. The solid content was 47.3%. The measured acid value was 87.2 mg KOH/g.

(Comparative Synthesis Examples 2 to 4)
Solutions of alkali-developable polymers HEP-2 to HEP-4 were obtained in the same manner as in Comparative Synthesis Example 1 described above, except that the types and amounts (unit: parts) of various materials shown in Tables 3-1 and 3-2 were used. The physical properties and the like of the obtained alkali-developable polymers are shown in Tables 3-1 and 3-2. Note that "MAA·M100" in Tables 3-1 and 3-2 means an adduct of MAA and M100 (Mw 282.29).

Comparative Synthesis Example 5
583.1 parts of PGMAc was placed in a reaction vessel and heated to 70°C. A monomer solution containing 12.0 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65) (trade name "V-65", Fujifilm Wako Pure Chemical Industries, Ltd.), 132.7 parts of BzMA, 58.2 parts of CHMA, 32.5 parts of HEMA, and 165.3 parts of SA was added dropwise over 1.5 hours. After the dropwise addition, the mixture was polymerized at 70°C for 6 hours to form a polymer, and a polymer solution was obtained. The solid content of the obtained polymer solution was 41.5%. The Mn of the polymer was 16,700, the PT was 36,500, and the PDI was 2.15.

0.8 parts of MEHQ, 3.9 parts of TBAB, and 58.9 parts of M100 were added. The mixture was heated to 90°C and reacted for 3 hours to obtain a solution containing a random copolymer (a solution of alkaline developable polymer HEP-5). A portion was sampled and IR was measured using an infrared spectrophotometer to confirm the disappearance of the absorption peak derived from the epoxy group, thereby confirming the completion of the reaction. The solid content was 43.8%. The measured acid value was 54.1 mg KOH/g.

<Preparation of resist ink composition (alkali developable polymer composition)>
Example 1
26.3 parts of the alkali-developable polymer EP-1 solution, 52.7 parts of PGMAc, 20.0 parts of dipentaerythritol hexaacrylate (DPHA) (product name "SR899NS", manufactured by Arkema), and 1.0 part of 1-[6-(2-methylbenzoyl)-9-ethyl-9H-carbazol-3-yl]ethanone O-acetyloxime (OXE-02) (product name "Irgacure OXE-02", manufactured by BASF Corporation) were blended and thoroughly mixed using a mixer, to obtain resist ink composition-1.

(Examples 2 to 8, Comparative Examples 1 to 5)
Resist ink compositions 2 to 13 were obtained in the same manner as in Example 1 except that the formulations shown in Table 4 were used.

<Production of Resin-Coated Glass Substrate>
(Application Example 1)
Resist ink composition-1 was spin-coated on a thoroughly washed glass substrate so that the final film thickness was 2.0 μm. After pre-baking at 90° C. for 2 minutes, the substrate was exposed to light at a light intensity of 100 mJ/cm ² using a photomask for forming a 1 cm×3 cm pattern using an ultra-high pressure mercury lamp. Then, the substrate was post-baked at 230° C. for 30 minutes to obtain a resin-coated glass substrate-1.

(Application Examples 2 to 8, Comparative Application Examples 1 to 5)
Resin-coated glass substrates 2 to 13 were produced in the same manner as in Application Example 1, except that the resist ink compositions shown in Table 5 were used.

<Evaluation>
The unexposed portion of the resin-coated glass substrate was subjected to alkaline development using a 5% aqueous solution of tetramethylammonium hydroxide. The time required for the unexposed portion to completely dissolve (dissolution time (sec)) was measured, and the development behavior, the presence or absence of dissolved residue, and the presence or absence of stickiness of the coating were confirmed. The results are shown in Table 5.

When the edges of the exposed areas that did not dissolve in the resin-coated glass substrates 1 to 8 obtained in Application Examples 1 to 8 were observed under a microscope, it was confirmed that all of them were sharp. This demonstrated that all of Resist Ink Compositions 1 to 8 had excellent alkaline developability.

It was also found that the resin-coated glass substrates-1 to -8 obtained in Application Examples 1 to 8 all had excellent light transmittance. The resin-coated glass substrates-6 to -8 obtained in Application Examples 6 to 8 were manufactured using an alkali-developable polymer polymerized by co-polymerization with specific organic solvents (propyl acetate, butyl acetate, methoxycyclopentane) that have a lower boiling point than PGMAc. Furthermore, since the resist ink composition used in manufacturing these resin-coated glass substrates-6 to 8 contained the specific organic solvent, it was found that almost no outgassing was generated in the resin-coated glass substrates-6 to 8.

The alkali-developable polymer of the present invention and a composition (resist ink composition) using the same are useful as patterning materials used in the manufacture of, for example, printed wiring boards, semiconductor packages, insulating films, printing plates, spacers for liquid crystal cells, color filters, and black matrices.

Claims (3)

The present invention is a reaction product obtained by reacting an A'B' block copolymer satisfying the following requirements (1) to (3) with an epoxy group-containing (meth)acrylate,
The alkali developable polymer is an AB block copolymer containing a polymer chain A and a polymer chain B, the number average molecular weight being 7,000 to 20,000, the molecular weight distribution (weight average molecular weight/number average molecular weight) being 1.2 to 1.8, the acid value being 40 to 100 mg/KOH, and the unsaturated group equivalent being 900 to 3,000 g/mol.
[Requirement (1)]
The block copolymer has a number average molecular weight of 6,000 to 18,000, a molecular weight distribution of 1.1 to 1.7, and an acid value of 70 to 130 mgKOH/g, and includes a polymer chain A' and a polymer chain B'.
[Requirement (2)]
The polymer chain A' is
The composition contains 15 to 55% by mass of structural units (ia) derived from at least one monomer selected from the group consisting of methyl methacrylate and benzyl methacrylate, 15 to 60% by mass of structural units (ii-a) derived from at least one monomer selected from the group consisting of cyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, 4-t-butylcyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate, 5 to 30% by mass of structural units (iii-a) derived from a methacrylate having a hydroxyl group, and 5 to 30% by mass of structural units (iv-a) derived from mono(2-methacryloyloxyethyl) succinate,
the total content of the structural units (ia) to (iv-a) is 90 mass% or more,
The polymer block has a number average molecular weight of 4,000 to 10,000 and a molecular weight distribution of 1.1 to 1.6.
[Requirement (3)]
The polymer chain B' is
Contains 10 to 60 mass% of structural units (ib) derived from at least one monomer selected from the group consisting of methyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, and dicyclopentenyloxyethyl methacrylate, and 40 to 90 mass% of structural units (ii-b) derived from mono(2-methacryloyloxyethyl) succinate,
the total content of the structural units (ib) and (ii-b) is 90 mass% or more,
The polymer block has a number average molecular weight of 2,000 to 8,000. The alkali-developable polymer according to claim 1, wherein the epoxy group-containing (meth)acrylate is (3,4-epoxycyclohexyl)methyl methacrylate. A liquid composition comprising the alkaline developable polymer according to claim 1 or 2 and an organic solvent,
the organic solvent contains 50% by mass or more of at least one selected from the group consisting of propyl acetate, butyl acetate, and methoxycyclopentane;