JP7464498B2 - Photosensitive resin composition containing epoxy resin and its cured product - Google Patents

Description

The present invention relates to a photosensitive resin composition containing an epoxy resin and a cured product thereof.

In recent years, with the miniaturization of electronic information devices, the use of so-called flexible printed circuit boards has increased due to their characteristics as light, thin, and flexible circuit boards. Since flexible printed circuit boards are literally flexible, the materials used for them are required to have the characteristics of photopatterning by alkaline development, and to form a tough coating with the necessary properties such as high sensitivity, adhesion, scratch resistance, and high mechanical, thermal, and electrical strength, while also having high flexibility to follow the flexible board and an elastic modulus that can protect the wiring.

In general, excellent properties such as sensitivity, curability, chemical resistance, and heat resistance are achieved by introducing many reactive groups into a main chain with a rigid skeleton, thereby imparting a high crosslinking density. Such resins have been used favorably in applications such as ordinary solder resists, color resists for displays, and hard coats. However, this does not impart the flexibility required for flexible substrates.

On the other hand, flexibility has been achieved by introducing a flexible main chain skeleton or introducing reactive groups sparingly, i.e., by moderately reducing the crosslink density. However, such resins have insufficient heat resistance and elastic modulus, and are not strong enough to protect the substrate when they follow a bent flexible substrate. As such, these properties are mutually exclusive, and materials that combine these properties are required for solder resist materials for flexible substrates, etc., and epoxy acrylate-based materials have been mainly used in the past. However, although this material has excellent properties such as chemical resistance and heat resistance, its flexibility is insufficient. Therefore, it is difficult to obtain a tough coating that has heat resistance, high elastic modulus, and flexibility that can be applied to flexible substrates, and further coating-forming materials are desired.

In an attempt to solve these problems, Patent Document 1 describes a reactive urethane compound obtained by reacting a bifunctional unsaturated epoxy carboxylate compound, a compound having two hydroxyl groups and one or more carboxyl groups in one molecule, and a diisocyanate compound. This reactive urethane compound has good flexibility and heat resistance compared to conventional epoxy acrylate-based materials, but is unable to exhibit the higher flexibility currently required.

In addition, in order to impart flexibility, Patent Document 2 proposes a composition that uses a polybutadiene having one or more internal epoxide groups per molecule as a curing agent. This composition has excellent elongation and heat resistance, but the elastic modulus is reduced and sufficient toughness cannot be obtained.

Japanese Patent Application Laid-Open No. 9-52925 JP 2002-293882 A

The objective of the present invention is to provide a resin composition and its cured product that has excellent photosensitivity to active energy rays, can form a pattern of fine images by development with a dilute alkaline aqueous solution, and can form a tough film with high insulation, adhesion, and heat resistance, as well as excellent flexibility and elasticity.

In order to solve the above problems, the present inventors have intensively studied photosensitive resin compositions and have completed the present invention.
That is, the present invention relates to the following (1) to (10).
(1) A photosensitive resin composition comprising a carboxyl group-containing photosensitive resin (A), a crosslinking agent (B), a photopolymerization initiator (C), and an epoxy resin (D) represented by the following general formula (1) as a curing agent:

（式（１）中、複数存在するＡｒは、独立して式（Ｘ）

In formula (1), each of a plurality of Ar's independently represents a group represented by formula (X)

または式（Ｙ）

Or formula (Y)

（式（Ｙ）中Ｒは独立して、水素原子、炭素数１～２のアルキル基、アリル基またはフェニル基を表し、少なくとも１つは水素原子以外である。）
で表される結合基を示し、式（Ｘ）と式（Ｙ）は任意に選択可能であるが、１分子中に式（Ｘ）と式（Ｙ）を少なくとも１個含む。ｎは繰り返し数の平均値であり、１≦ｎ＜２０である。）

(In formula (Y), R independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, an allyl group, or a phenyl group, and at least one R is other than a hydrogen atom.)
Formula (X) and formula (Y) can be arbitrarily selected, but at least one of formula (X) and formula (Y) is contained in one molecule. n is the average number of repetitions, and 1≦n<20.)

(2) The photosensitive resin composition according to (1) above, in which the carboxyl group-containing photosensitive resin (A) is an unsaturated epoxy carboxylate compound (c) obtained by reacting an epoxy compound (a) having two epoxy groups in one molecule with a monocarboxylic acid (b) having an ethylenically unsaturated group in one molecule, and a polyurethane compound (A1) obtained by reacting a diisocyanate compound (d), a carboxylic acid (e) having two hydroxyl groups in one molecule, and, if necessary, an optional polyester diol compound (f).

(3) The photosensitive resin composition according to (2) above, in which the carboxyl group-containing photosensitive resin (A) is an acid-modified polyurethane compound (A2) obtained by reacting a polyurethane compound (A1) with a polybasic acid anhydride (g).

(4) The photosensitive resin composition according to (1) above, in which the carboxyl group-containing photosensitive resin (A) is a reaction product (A3) of an unsaturated epoxy carboxylate compound (c') obtained by reacting an epoxy compound (a') having two or more epoxy groups in one molecule with a monocarboxylic acid (b) having an ethylenically unsaturated group in the molecule, and a polybasic acid anhydride (g).

(5) A photosensitive resin composition according to any one of (1) to (4) above, in which Ar at both ends is represented by formula (Y).

(6) An epoxy photosensitive resin composition according to any one of (1) to (5) above, in which all R in formula (1) are methyl groups.

(7) A photosensitive resin composition according to any one of (1) to (6), which is a resist material.

(8) A cured product of the photosensitive resin composition described in any one of (1) to (7) above.

The photosensitive resin composition contains a carboxyl group-containing photosensitive resin, a crosslinking agent, a photopolymerization initiator, and a curing agent, and is obtained by using an epoxy resin as the curing agent, which is a compound having the structure of general formula (1). The photosensitive resin composition has excellent photosensitivity when it is cured by exposure to ultraviolet light to form a coating film, and is developable. The obtained cured product has excellent heat resistance, elasticity, and flexibility.

The epoxy resin (D) used as a curing agent in the present invention is characterized by being represented by the following general formula (1).

（式（１）中、複数存在するＡｒは、独立して式（Ｘ）

In formula (1), each of a plurality of Ar's independently represents a group represented by formula (X)

または式（Ｙ）

Or formula (Y)

（式（Ｙ）中Ｒは独立して、水素原子、炭素数１～２のアルキル基、アリル基またはフェニル基を表し、少なくとも１つは水素原子以外である。）
で表される結合基を示し、式（Ｘ）と式（Ｙ）は任意に選択可能であるが、１分子中に式（Ｘ）と式（Ｙ）を少なくとも１個含む。ｎは繰り返し数の平均値であり、１≦ｎ＜２０である。）

(In formula (Y), R independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, an allyl group, or a phenyl group, and at least one R is other than a hydrogen atom.)
Formula (X) and formula (Y) can be arbitrarily selected, but at least one of formula (X) and formula (Y) is contained in one molecule. n is the average number of repetitions, and 1≦n<20.)

The epoxy resin (D) used in the present invention is represented by the above formula (1) and is usually a solid resin at room temperature. A high molecular weight resin with a large number of repeating units is more likely to disperse stress and become stronger. The average value of n in the above formula (1) can be determined by the area ratio of a GPC chart. The average value of n is preferably 1≦n<50, more preferably 1≦n<20, and even more preferably 1≦n<10. If the average value of n is less than 1, the cured product is likely to be brittle, and if it is more than 20, the resin may gel.
The softening point is preferably 40 to 200° C., more preferably 40 to 180° C. If it is 40° C. or lower, it will be semi-solid and difficult to handle, while if it exceeds 200° C., problems such as difficulty in kneading when preparing the composition may occur.
Furthermore, the epoxy equivalent is preferably 300 to 2000 g/eq, and more preferably 300 to 1000 g/eq. If the epoxy equivalent is less than 300 g/eq, the crosslinking density is high and the cured product is likely to become brittle, and if it is more than 2000 g/eq, there is a risk that heat resistance will not be exhibited.

The epoxy resin (D) represented by the formula (1) may be a commercially available high molecular weight epoxy resin, or may be an epoxy resin obtained by reacting a known bifunctional epoxy resin with a bifunctional phenolic resin.

When a known bifunctional epoxy resin is reacted with a bifunctional phenolic resin, the following formula (2) is obtained.

（式中、Ｒは前述の式（１）中Ｒと同じ意味を表す。）
で表される２官能のフェノール化合物と、下記式（３）

(In the formula, R has the same meaning as R in the above formula (1).)
and a bifunctional phenol compound represented by the following formula (3):

（式中、Ｒは前述の式（１）中Ｒと同じ意味を表す。）
で表される２官能のエポキシ化合物を用いることができる。仕込み割合としては、前記式（２）で表されるフェノール化合物に対して前記式（３）で表されるエポキシ化合物を等モルより多く仕込み、触媒存在下、反応させることで得ることができる。
一般式（２）で表されるフェノール化合物の具体例としては、４，４’－ビフェノール（以下、単にビフェノールということもある。）、３，３’－ジメチルビフェノール、３，３’，５，５’－テトラメチルビフェノール３，３’－ジエチルビフェノール３，３’，５，５’－テトラエチルビフェノール、３，３’－ジフェニルビフェノール等が挙げられる。一般（３）で表されるエポキシ化合物は、一般式（２）のフェノール化合物に公知の方法でエピハロヒドリンを反応させて得られるが、これらに限定されるものではない。前記式（２）で表されるフェノール化合物および前記式（３）で表されるエポキシ化合物は単一で用いても、複数種類を併用してもよい。

(In the formula, R has the same meaning as R in the above formula (1).)
The epoxy compound represented by the formula (3) can be used in an amount greater than equimolar to the phenol compound represented by the formula (2) and reacted in the presence of a catalyst.
Specific examples of the phenol compound represented by the general formula (2) include 4,4'-biphenol (hereinafter, sometimes simply referred to as biphenol), 3,3'-dimethylbiphenol, 3,3',5,5'-tetramethylbiphenol, 3,3'-diethylbiphenol, 3,3',5,5'-tetraethylbiphenol, and 3,3'-diphenylbiphenol. The epoxy compound represented by the general formula (3) can be obtained by reacting the phenol compound represented by the general formula (2) with epihalohydrin by a known method, but is not limited thereto. The phenol compound represented by the formula (2) and the epoxy compound represented by the formula (3) may be used alone or in combination of two or more kinds.

From the viewpoint of imparting solubility, it is preferable to use 20 mol% or more of a compound containing an alkyl group having 1 to 2 carbon atoms in at least one of the Rs described in the phenol compound represented by formula (2) or the epoxy compound represented by formula (3), and a reaction product combining biphenol as the phenol compound represented by formula (2) and an epoxidized product of 3,3',5,5'-tetramethylbiphenol as the epoxy compound represented by formula (3) can be suitably used. The amount of the phenol compound represented by formula (2) used in this reaction is usually 0.05 to 0.8 mol, preferably 0.1 to 0.7 mol, and particularly preferably 0.2 to 0.6 mol per mol of epoxy group in the epoxy compound represented by formula (3).

If necessary, a catalyst can be used in this reaction. Specific examples of catalysts that can be used include quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, and trimethylbenzylammonium chloride; quaternary phosphonium salts such as triphenylethylphosphonium chloride and triphenylphosphonium bromide; alkali metal salts such as sodium hydroxide, potassium hydroxide, potassium carbonate, and cesium carbonate; imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, and 2-ethyl-4-methylimidazole; 2-(dimethylaminomethyl)phenol, triethylamine, and the like. Examples of suitable catalysts include tertiary amines such as phenyldiamine, triethanolamine, and 1,8-diazabicyclo(5,4,0)undecene-7; organic phosphines such as triphenylphosphine, diphenylphosphine, and tributylphosphine; metal compounds such as tin octylate; tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium tetraphenylborate and tetraphenylphosphonium ethyltriphenylborate; and tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate. Although the amount of these catalysts varies depending on the type of catalyst, they are generally used in an amount of 10 to 30,000 ppm, preferably 100 to 5,000 ppm, based on the total weight of the phenol compound represented by formula (2) and the epoxy compound represented by formula (3), as necessary. In the post-reaction, the reaction proceeds without the addition of a catalyst, so the catalyst is used appropriately taking into account the reaction temperature and the amount of reaction solvent.

In this reaction, a solvent may be used. When using a solvent, any solvent that does not affect the reaction may be used, and examples of the solvents that can be used include the following: polar solvents, ethers; ester-based organic solvents such as dimethyl sulfoxide, N,N'-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, diglyme, triglyme, and propylene glycol monomethyl ether; ketone-based organic solvents such as ethyl acetate, butyl acetate, butyl lactate, and γ-butyrolactone; aromatic organic solvents such as methyl isobutyl ketone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; toluene, xylene, etc. The amount of the solvent used is usually 0 to 300% by weight, and preferably 0 to 100% by weight, based on the total weight of the phenol compound represented by formula (2) and the epoxy compound represented by formula (3).

The reaction temperature and reaction time in this reaction depend on the amount of solvent and the type and amount of catalyst used, but the reaction time is usually 1 to 200 hours, preferably 1 to 100 hours. From the viewpoint of productivity, a short reaction time is preferable. The reaction temperature is usually 0 to 250°C, preferably 80 to 150°C.

After the reaction is complete, the catalyst, etc., is removed by washing with water as necessary, or left as is, and the solvent is distilled off under heating and reduced pressure to obtain the epoxy resin (D) used in the present invention. Depending on the application, the solvent concentration can be adjusted and the product can be used as an epoxy resin varnish.

The carboxyl group-containing photosensitive resin (A) in the present invention can be, for example, a polyurethane compound (A1) obtained by reacting an unsaturated epoxy carboxylate compound (c) obtained by reacting an epoxy compound (a) having two epoxy groups in one molecule with a monocarboxylic acid (b) having an ethylenically unsaturated group in one molecule, a diisocyanate compound (d), a carboxylic acid (e) having two hydroxyl groups in one molecule, and, if necessary, an optional polyester diol compound (f).

That is, the polyurethane resin (A1) in the present invention is produced through two reaction steps. First, an epoxy compound (a) having two epoxy groups per molecule is reacted with a monocarboxylic acid (b) having an ethylenically unsaturated group per molecule to obtain an unsaturated epoxy carboxylate compound (c). In the present invention, this step is called a carboxylation step.
The next step is to react the thus obtained unsaturated epoxy carboxylate compound (c), a carboxylic acid having two hydroxyl groups in one molecule (e), a diisocyanate compound (d) and, if necessary, an optional polyester diol compound (f). In the present invention, this step is referred to as a urethanization step.

The unsaturated epoxy carboxylate compound (c) obtained in the carboxylation step is a carboxylate compound having two hydroxyl groups derived from the epoxy group of the epoxy compound (a) having two epoxy groups in one molecule.

In the subsequent urethane-forming step, the two hydroxyl groups of the unsaturated epoxy carboxylate compound (c) are reacted with a carboxylic acid (e) having two hydroxyl groups per molecule, a diisocyanate compound (d) and, if necessary, an optional polyester diol compound (f) to obtain a polyurethane resin (A1).

First, the carboxylation step will be described in detail.
The epoxy compound (a) having two epoxy groups in one molecule (hereinafter also referred to simply as "epoxy compound (a)") used in the production of the polyurethane resin (A) in the present invention is not particularly limited as long as it has two epoxy groups in one molecule. With a monofunctional epoxy compound, it is not possible to adjust the molecular weight of the polyurethane resin (A) obtained by the urethanization step, and with an epoxy compound having three or more functionalities, it is difficult to obtain suitable physical properties of the cured product due to the multi-branched structure.

Examples of the epoxy compound (a) include bisphenol-based diglycidyl ethers such as bisphenol-A diglycidyl ether, bisphenol-F diglycidyl ether, bisphenol-S diglycidyl ether, and bisphenol fluorene diglycidyl ether, aromatic diglycidyl ether compounds such as biphenyl-based glycidyl ethers such as biphenol diglycidyl ether and tetramethylbiphenol glycidyl ether, alkyldiol diglycidyl ethers such as hexanediol diglycidyl ether, and polyethylene glycol. Examples of such compounds include saturated hydrocarbon diglycidyl ether compounds such as alkylene glycol diglycidyl ethers such as diglycidyl ether, cycloalkyldiol diglycidyl ethers such as cyclohexanediol diglycidyl ether and hydrogenated bisphenol-A diglycidyl ether; and so-called bifunctional alicyclic epoxy compounds such as 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate (Celloxide 2021, manufactured by Daicel Corporation) and 1,2,8,9-diepoxylimonene (Celloxide 3000, manufactured by Daicel Corporation).

Of these, aromatic diglycidyl ether compounds are preferred because they have good heat resistance.

The epoxy compound (a) is preferably one that does not have a hydroxyl group. This is because the unsaturated epoxy carboxylate compound (c) obtained in the epoxy carboxylation step becomes a polyol compound with three or more functional groups, making it difficult to control the molecular weight of the polyurethane resin (A1).

The monocarboxylic acid (b) having an ethylenically unsaturated group in one molecule used in the production of the polyurethane resin (A1) in the present invention (hereinafter also referred to simply as "compound (b)") has the purpose of introducing an ethylenically unsaturated group into the reactive polyurethane resin (A1) and converting the epoxy compound (a) into a diol compound capable of reacting with an isocyanate group. The number of ethylenically unsaturated groups in the compound (b) is preferably 1 to 4.

Examples of the compound (b) include (meth)acrylic acids, crotonic acid, α-cyanocinnamic acid, cinnamic acid, or reaction products of saturated or unsaturated dibasic acids with unsaturated group-containing monoglycidyl compounds excluding monoglycidyl (meth)acrylate derivatives.
Examples of the (meth)acrylic acids include (meth)acrylic acid, β-styryl (meth)acrylic acid, β-furfuryl (meth)acrylic acid, a reaction product of (meth)acrylic acid and ε-caprolactone, a (meth)acrylic acid dimer, half esters which are equimolar reaction products of a saturated or unsaturated dibasic acid anhydride and a (meth)acrylate derivative having one hydroxyl group per molecule, and half esters which are equimolar reaction products of a saturated or unsaturated dibasic acid and a monoglycidyl (meth)acrylate derivative.

Among these, (meth)acrylic acid, a reaction product of (meth)acrylic acid and ε-caprolactone, or cinnamic acid is preferred in terms of sensitivity when made into a photosensitive resin composition.

Furthermore, it is preferable that the compound (b) does not have a hydroxyl group in the compound.

In the carboxylation step, it is preferable that the amount of compound (b) is 90 to 120 equivalent percent per equivalent of the epoxy compound (a). Within this range, production can be performed under relatively stable conditions. If the amount of compound (b) charged is greater than this, compound (b) having a carboxy group will remain, which is not preferable. If the amount is too small, unreacted epoxy compound (a) will remain, causing problems with the stability of the resin.

The carboxylation step can be carried out without a solvent or diluted with a solvent. When a solvent is used, it is not particularly limited as long as it is an inert solvent for the carboxylation reaction. It is also preferable to use an inert solvent in the subsequent urethane formation step or in the acid addition step described below, which is used as needed.

When a solvent is used, its amount should be adjusted appropriately depending on the viscosity and use of the resulting resin, but it is preferable to use a solvent so that the solid content is 99 to 30% by weight, and more preferably 99 to 45% by weight. If the compound used in the reaction has a high viscosity, the viscosity will be suppressed and the reaction will proceed smoothly.

Examples of such solvents include aromatic hydrocarbon solvents such as toluene, xylene, ethylbenzene, and tetramethylbenzene, aliphatic hydrocarbon solvents such as hexane, octane, and decane, and mixtures thereof such as petroleum ether, white gasoline, and solvent naphtha. Ester-based solvents, ether-based solvents, and ketone-based solvents may also be used.

Examples of the ester solvent include alkyl acetates such as ethyl acetate, propyl acetate, and butyl acetate; cyclic esters such as γ-butyrolactone; mono- or polyalkylene glycol monoalkyl ether monoacetates such as ethylene glycol monomethyl ether monoacetate, diethylene glycol monomethyl ether monoacetate, diethylene glycol monoethyl ether monoacetate, triethylene glycol monoethyl ether monoacetate, diethylene glycol monobutyl ether monoacetate, propylene glycol monomethyl ether monoacetate, and butylene glycol monomethyl ether monoacetate; dialkyl glutarates such as dimethyl glutarate; dialkyl succinates such as dimethyl succinate; and dialkyl adipates such as dimethyl adipate.

Examples of the ether solvent include alkyl ethers such as diethyl ether and ethyl butyl ether, glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, triethylene glycol dimethyl ether and triethylene glycol diethyl ether, and cyclic ethers such as tetrahydrofuran.

Examples of ketone solvents include acetone, methyl ethyl ketone, cyclohexanone, and isophorone.

In addition, if the reaction is inert, the crosslinking agent (B) described below may be used alone or in combination as a solvent. In this case, the composition may be used as it is as a curable composition.

In the carboxylation step, it is preferable to use a catalyst to promote the reaction. When the catalyst is used, the amount of the catalyst is about 0.1 to 10% by weight based on the total amount of the reactants, i.e., the epoxy compound (a), the compound (b), and the solvent, if used. The reaction temperature is 60 to 150° C., and the reaction time is preferably 5 to 60 hours.
Examples of the catalyst include general basic catalysts such as triethylamine, benzyldimethylamine, triethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium iodide, triphenylphosphine, triphenylstibine, chromium octanoate, and zirconium octanoate.

A thermal polymerization inhibitor may also be used. Examples of the thermal polymerization inhibitor that can be used preferably include hydroquinone monomethyl ether, 2-methylhydroquinone, hydroquinone, diphenylpicrylhydrazine, diphenylamine, and 3,5-di-t-butyl-4-hydroxytoluene.

The carboxylation process is terminated when the acid value of the sample, taken as appropriate, is 5 mg KOH/g or less, preferably 2 mg KOH/g or less.

Next, the urethane-forming step will be described in detail.
The carboxylic acid (e) having two hydroxyl groups per molecule used in the production of the polyurethane resin (A1) in the present invention (hereinafter, also referred to simply as "compound (e)") introduces a carboxy group into the polyurethane resin (A1) to make it soluble in an aqueous alkaline solution required for photopatterning. The number of carboxy groups in the compound (e) is preferably 1 to 4.

As the compound (e), for example, dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolvaleric acid, etc. are preferred, and among them, dimethylolpropionic acid and dimethylolbutanoic acid are particularly preferred in consideration of the availability of raw materials.

By using any polyester diol compound (f) used as necessary in the production of the polyurethane resin (A1) of the present invention, it is possible to obtain a polyurethane resin (A1) that has an excellent balance between sensitivity, heat resistance, chemical resistance, etc., and flexibility. The polyester diol compound (f) is characterized by having two hydroxyl groups in one molecule and further having an ester bond in the main skeleton.

Examples of the polyester polyester diol compound (f) include diol dicarboxylic acid ester diols in which a diol compound and a dicarboxylic acid are linked by an ester bond, polylactone diols obtained by ring-opening polymerization of cyclic esters with a diol compound, polycarbonate diols having a carbonate bond obtained by reaction of an alkyl carbonate with a diol compound, and polyester diols which are a composite combination of these. These polyester diol compounds are not particularly limited as long as they are compounds having two hydroxyl groups other than the unsaturated epoxy carboxylate compound (c) and compound (e).

Examples of diol dicarboxylate diols in which a diol compound and a dicarboxylic acid compound are linked by an ester bond include ethylene glycol adipate diol, propylene glycol adipate diol, butylene glycol adipate diol, neopentyl glycol adipate diol, methylpentanediol adipate diol, hexanediol adipate diol, ethylene glycol sebacic acid ester diol, hexanediol decanedioic acid ester diol, ethylene glycol phthalic acid ester diol, ethylene glycol azelaic acid ester diol, and ethylene glycol Examples of the polyester diol include sebacic acid polyester diol, propylene glycol sebacic acid polyester diol, butylene glycol sebacic acid polyester diol, neopentyl glycol sebacic acid polyester diol, methylpentanediol sebacic acid polyester diol, hexanediol sebacic acid polyester diol, ethylene glycol sebacic acid polyester diol, ethylene glycol dimer acid polyester diol, propylene glycol dimer acid polyester diol, hexanediol decanedioic acid ester diol, ethylene glycol dodecanedioic acid ester diol, and ethylene glycol adodecanedioic acid ester diol.

Examples of polylactone diol compounds obtained by ring-opening polymerization of cyclic esters include polybutyrolactone diol, polyvalerolactone diol, and polycaprolactone diol.

Examples of polycarbonate diol compounds include polypropylene carbonate diol, polybutylene carbonate diol, polyhexamethylene carbonate diol, polyoctamethylene carbonate diol, polynonanediol carbonate diol, polycyclohexane carbonate diol, polycyclohexanedimethanol carbonate diol, etc.

Among these, as the polyester diol compound (f), polycaprolactone diols and polycarbonate diols are particularly preferred because they exhibit favorable cured physical properties. In particular, polycarbonate diols are even more preferred because they can derive polyurethane resin (A1) that gives a tough cured film.

The preferred molecular weight of polyester diol compound (f) is in the range of 250 to 5000, and more preferably 650 to 3000. If the molecular weight is smaller than this range, the effect of imparting flexibility is low, and if it is larger than this range, the heat resistance is significantly reduced.

The diisocyanate compound (d) (hereinafter also referred to simply as "isocyanate compound (d)") used in the production of the polyurethane resin (A1) in the present invention is used in the urethane-forming process with the unsaturated epoxy carboxylate compound (c), compound (e), and optional polyester diol compound (f) used as needed, and provides suitable flexibility to the polyurethane resin (A1).

Examples of the isocyanate compound (d) include aliphatic linear diisocyanates, alicyclic diisocyanates, and aromatic isocyanates.

Examples of aliphatic linear diisocyanates include hexamethylene diisocyanate and trimethylhexamethylene diisocyanate.

Examples of alicyclic diisocyanates include isophorone diisocyanate, norbornene diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated methylene bisphenylene diisocyanate.

Examples of aromatic diisocyanates include tolylene diisocyanate, xylylene diisocyanate, and methylene bisphenylene diisocyanate.

Of these, aliphatic or alicyclic diisocyanates are preferred when increasing flexibility, and linear aliphatic diisocyanates are particularly preferred.

The urethanization process is carried out by mixing a mixture of an unsaturated epoxy carboxylate compound (c), a carboxylic acid having two hydroxyl groups per molecule (e), and an optional polyester diol compound (f) used as needed, with a compound having an isocyanate group (d).

In the production of polyurethane resin (A1), the value represented by (molar number of unsaturated epoxy carboxylate compound (c)+molar number of compound (e)+molar number of polyester diol compound (f))÷(molar number of isocyanate compound (d)), i.e., the ratio of hydroxyl groups to isocyanate groups in the reaction system, is preferably in the range of 1.05 to 2, particularly preferably in the range of 1.15 to 1.6. That is, from the viewpoint of the storage stability of polyurethane resin (A1), the urethanization step is carried out so that at least the number of hydroxyl groups is greater than the number of isocyanate groups, so that no isocyanate groups remain in the final product.
Furthermore, if it is larger than this range, the molecular weight of the resulting polyurethane resin (A1) will be too small, making it difficult to obtain a tough cured product. If it is too small, the molecular weight of the resulting polyurethane resin (A1) will be too large, which may have an adverse effect on developability, etc.

In the production of the polyurethane resin (A1) of the present invention, the preferred weight ratios of the weight of the unsaturated epoxy carboxylate compound (c), the weight of the compound (e), the weight of the polyester diol compound (f) used as needed, and the weight of the isocyanate compound (d) are 5 to 65 parts by weight of the unsaturated epoxy carboxylate compound (c), 5 to 25 parts by weight of the compound (e), 0 to 60 parts by weight of the polyester diol compound (f), and 20 to 40 parts by weight of the isocyanate compound (d), assuming the total weight of the resin composition to be 100 parts. Within these ranges, a polyurethane resin (A1) having photopatterning and developability with an alkaline aqueous solution and suitable properties as a resist material can be obtained, and a cured product having a particularly high level of well-balanced properties of high heat resistance, chemical resistance, and excellent flexibility can be obtained.

The urethane-forming process can be carried out without a solvent or diluted with a solvent. If a solvent is used, there are no particular limitations as long as it is an inert solvent for the urethane-forming reaction.

When a solvent is used, its amount should be adjusted appropriately depending on the viscosity and use of the resulting resin, but it is preferable to use it so that the solid content is 99 to 30% by weight, more preferably 90 to 45% by weight. It is also possible to use the solvent used in the carboxylation process as is, provided that it is an inert in both processes.

The solvent may be, for example, the same as the solvent exemplified in the carboxylation step. If the solvent is inert in the reaction, the reactive compound (B) described below may be used alone or in combination as a solvent. In this case, the composition may be used as it is as a curable composition.

In the urethane-forming process, a thermal polymerization inhibitor or the like may be used, and the same compounds as those exemplified in the carboxylate-forming process can be used.

The urethane-forming process can be carried out substantially without a catalyst, but a catalyst can also be used to accelerate the reaction. When a catalyst is used, the amount used is about 0.01 to 1% by weight based on the total amount of reactants. Examples of such catalysts include general basic catalysts, such as Lewis base catalysts such as tin ethylhexanoate.

The reaction temperature for the urethane formation process is preferably 40 to 150°C, and the reaction time is preferably 5 to 60 hours.

The end point of the urethanization reaction is determined when almost no isocyanate groups remain. The end point of the reaction is determined by observing a peak at about 2250 cm ⁻¹ due to isocyanate groups by infrared absorption spectroscopy or by a titration method as specified in JIS K1556:1968 or the like.

The preferred molecular weight range of the polyurethane resin (A1) of the present invention thus obtained is a weight average molecular weight in terms of polystyrene measured by GPC of 1,000 to 30,000, more preferably 3,000 to 25,000. If the molecular weight is smaller than this range, the toughness of the cured product will not be fully exhibited, and if it is too large, the viscosity will increase, making coating and other processes difficult and also reducing developability.

The carboxyl group-containing photosensitive resin (A) in the present invention also includes an acid-modified polyurethane resin (A2) obtained by reacting a polybasic acid anhydride (g) with a reactive polyurethane resin (A1) as necessary. This makes it possible to appropriately add the acid value required for alkaline development according to the desired properties of the resin, rather than just adding a carboxylic acid (e) having two hydroxyl groups in one molecule. In the present invention, this reaction process is referred to as the acid addition process.

Next, the acid addition step will be described in detail. The acid addition step is a step in which a polybasic acid anhydride (g) is reacted with the hydroxyl groups remaining after the urethanization reaction to introduce a carboxyl group via an ester bond. Therefore, it is not possible to add acid in an amount greater than the equivalent of the hydroxyl groups remaining after the urethanization step is completed.

Examples of the polybasic acid anhydride (g) include compounds having a cyclic acid anhydride structure in one molecule, and from the viewpoints of alkaline aqueous solution developability, heat resistance, hydrolysis resistance, etc., preferred are succinic anhydride (SA), phthalic anhydride (PAH), tetrahydrophthalic anhydride (THPA), hexahydrophthalic anhydride (HHPA), itaconic anhydride, 3-methyl-tetrahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, trimellitic anhydride, maleic anhydride, etc.

The acid addition step is carried out by adding a polybasic acid anhydride (g) to the polyurethane resin (A1).

When the polyurethane resin (A1) and/or acid-modified polyurethane resin (A2) of the present invention is used as an alkali development type resist, the solid content acid value (based on JIS K5601-2-1:1999) of the finally obtained polyurethane resin is preferably 30 to 120 mg KOH/g, more preferably 40 to 105 mg KOH/g. When the solid content acid value is within this range, the active energy ray curable resin composition of the present invention exhibits good developability with an alkaline aqueous solution. In other words, it is possible to achieve a good balance between the solubility of the non-active energy ray irradiated area and the insolubility of the active energy ray irradiated area.

In the acid addition step, it is preferable to use a catalyst to promote the reaction, and the amount of the catalyst used is about 0.1 to 10% by weight based on the total amount of the reactants. The reaction temperature is 60 to 150° C., and the reaction time is preferably 5 to 60 hours.
Examples of the catalyst include triethylamine, benzyldimethylamine, triethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium iodide, triphenylphosphine, triphenylstibine, chromium octanoate, and zirconium octanoate.

The acid addition step can be carried out without a solvent or diluted with a solvent. If a solvent is used, there are no particular limitations on the solvent as long as it is an inert solvent in the acid addition reaction. Also, if a solvent was used in the preceding urethane formation step, the acid addition reaction can be carried out without removing the solvent if it is an inert solvent in both reactions.

The amount of the solvent used should be adjusted appropriately depending on the viscosity and use of the resulting resin, but it is preferable to use the solvent in such an amount that the solid content becomes 90 to 30% by weight, more preferably 80 to 50% by weight.
As the solvent, the same solvents as those exemplified in the carboxylation reaction and urethanization step may be used.

If the reaction is inert, the crosslinking agent (B) described below may be used alone or in combination as a solvent. In this case, the composition may be used as it is as a curable composition.

In the acid addition step, a thermal polymerization inhibitor or the like may be used, and the same compounds as those exemplified in the carboxylation step and the urethanization step can be used.

The reaction in the acid addition process is sampled as appropriate, and the end point is reached when the acid value of the reactant falls within the range of plus or minus 10% of the set acid value.

The carboxyl group-containing photosensitive resin (A) in the present invention also includes a reaction product (A3) of an unsaturated epoxy carboxylate compound (c') obtained by reacting an epoxy compound (a') having two or more epoxy groups in one molecule with a monocarboxylic acid (b) having an ethylenically unsaturated group in the molecule, and a polybasic acid anhydride (g).

Examples of the epoxy compound (a') having two or more epoxy groups in one molecule used to produce the reaction product (A3) in the present invention include phenol novolac type epoxy resins, cresol novolac type epoxy resins, trishydroxyphenylmethane type epoxy resins, dicyclopentadiene phenol type epoxy resins, bisphenol-A type epoxy resins, bisphenol-F type epoxy resins, biphenol type epoxy resins, bisphenol-A novolac type epoxy resins, naphthalene skeleton-containing epoxy resins, glyoxal type epoxy resins, heterocyclic epoxy resins, etc.

Examples of the phenol novolac type epoxy resin include Epiclon N-770 (manufactured by DIC Corporation), D.E.N438 (manufactured by The Dow Chemical Company), jER154 (manufactured by Japan Epoxy Resins Co., Ltd.), EPPN-201, and RE-306 (all manufactured by Nippon Kayaku Co., Ltd.).
Examples of the cresol novolac type epoxy resin include Epicron N-695 (manufactured by DIC Corporation), EOCN-102S, EOCN-103S, EOCN-104S (all manufactured by Nippon Kayaku Co., Ltd.), UVR-6650 (manufactured by Union Carbide Corporation), and ESCN-195 (manufactured by Sumitomo Chemical Co., Ltd.).

Examples of the trishydroxyphenylmethane type epoxy resin include EPPN-503, EPPN-502H, EPPN-501H (all manufactured by Nippon Kayaku Co., Ltd.), TACTIX-742 (manufactured by The Dow Chemical Company), jER E1032H60 (manufactured by Japan Epoxy Resins Co., Ltd.), and the like.
Examples of the dicyclopentadiene phenol type epoxy resin include Epicron EXA-7200 (manufactured by DIC Corporation) and TACTIX-556 (manufactured by The Dow Chemical Company).

Examples of the bisphenol type epoxy resin include bisphenol-A type epoxy resins such as jER828, jER1001 (both manufactured by Japan Epoxy Resins Co., Ltd.), UVR-6410 (manufactured by Union Carbide Corporation), D.E.R-331 (manufactured by Dow Chemical Co., Ltd.), YD-8125 (manufactured by Tohto Kasei Co., Ltd.), NER-1202, NER-1302 (both manufactured by Nippon Kayaku Co., Ltd.), and bisphenol-F type epoxy resins such as UVR-6490 (manufactured by Union Carbide Corporation), YDF-8170 (manufactured by Tohto Kasei Co., Ltd.), NER-7403, NER-7604 (both manufactured by Nippon Kayaku Co., Ltd.).

Examples of the biphenol type epoxy resin include biphenol type epoxy resins such as NC-3000, NC-3000-H, and NC-3000-L (all manufactured by Nippon Kayaku Co., Ltd.), bixylenol type epoxy resins such as YX-4000 (manufactured by Japan Epoxy Resins Co., Ltd.), and YL-6121 (manufactured by Japan Epoxy Resins Co., Ltd.).
Examples of the bisphenol A novolac type epoxy resin include Epicron N-880 (manufactured by DIC Corporation) and jER E157S75 (manufactured by Japan Epoxy Resins Co., Ltd.).

Examples of the naphthalene skeleton-containing epoxy resin include NC-7000 (manufactured by Nippon Kayaku Co., Ltd.) and EXA-4750 (manufactured by DIC Corporation).
An example of the glyoxal type epoxy resin is GTR-1800 (manufactured by Nippon Kayaku Co., Ltd.).
An example of the alicyclic epoxy resin is EHPE-3150 (manufactured by Daicel Corporation).
An example of the heterocyclic epoxy resin is TEPIC (manufactured by Nissan Chemical Industries, Ltd.).

Among these, bisphenol type epoxy resins and biphenol type epoxy resins are particularly effective in terms of flexibility, and for example, NER-1202, NER-1302, NER-7403, NER-7604, NC-3000, NC-3000-H, NC-3000-L, etc. are most preferred.

Examples of the crosslinking agent (B) used in the photosensitive resin composition of the present invention include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate, carbitol (meth)acrylate, acryloylmorpholine, (meth)acrylates having a hydroxyl group (e.g., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate, etc.) and acid anhydrides of polycarboxylic acids (e.g., succinic anhydride, anhydrous succinic acid, etc.). maleic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc.), half esters as reaction products of such acids, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate, glycerin polypropoxy tri(meth)acrylate, di(meth)acrylate of ε-caprolactone adduct of hydroxypivalic acid neopen glycol (e.g., KAYARAD, manufactured by Nippon Kayaku Co., Ltd.), HX-220, HX-620, etc.), pentaerythritol tetra(meth)acrylate, poly(meth)acrylates which are reaction products of dipentaerythritol and ε-caprolactone (for example, DPCA described in the Examples below), dipentaerythritol poly(meth)acrylate, mono- or polyglycidyl compounds (for example, butyl glycidyl ether, phenyl glycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hexahydrophthalic acid diglycidyl ether, Examples of the crosslinking agent (B) include epoxy (meth)acrylate, which is a reaction product of glycerin polyglycidyl ether, glycerin polyethoxyglycidyl ether, trimethylolpropane polyglycidyl ether, trimethylolpropane polyethoxypolyglycidyl ether, etc. with (meth)acrylic acid. The crosslinking agent (B) may be used alone or in combination of two or more. The content of these in the photosensitive resin composition is usually 2 to 40% by mass, preferably 3 to 30% by mass, when the solid content of the photosensitive resin composition is taken as 100% by mass.

The photopolymerization initiator (C) used in the photosensitive resin composition of the present invention can be used without any particular limitation, and specific examples thereof include benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, and benzoin isobutyl ether; acetophenones such as acetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-phenylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (for example, Omnirad-907 described in the Examples below); and 2-ethylanthraquinone. , anthraquinones such as 2-tertiary butyl anthraquinone, 2-chloro anthraquinone, 2-amyl anthraquinone, etc.; thioxanthones such as 2,4-diethyl thioxanthone (for example, DETX-S described in the examples below), 2-isopropyl thioxanthone, 2-chloro thioxanthone, etc.; ketals such as acetophenone dimethyl ketal, benzyl dimethyl ketal, etc.; benzophenones such as benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 4,4'-bismethylaminobenzophenone, etc.; phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. The photopolymerization initiator (C) can be used alone or in a mixture of two or more kinds. The content ratio of these in the photosensitive resin composition is usually 1 to 30% by mass, preferably 2 to 25% by mass, when the solid content of the photosensitive resin composition is 100% by mass.

These photopolymerization initiators (C) can be used alone or as a mixture of two or more kinds, and can be used in combination with accelerators such as tertiary amines such as triethanolamine and methyldiethanolamine, and benzoic acid derivatives such as N,N-dimethylaminobenzoic acid ethyl ester and N,N-dimethylaminobenzoic acid isoamyl ester. The amount of these accelerators added is preferably 100% by mass or less relative to the photopolymerization initiator (C).

The content of the epoxy resin (D) represented by the general formula (1) is preferably 200% or less of the equivalent amount calculated from the solid acid value of the carboxyl group-containing photosensitive resin (A) and the amount used. A more preferred range is 80% to 200%, and even more preferably 80 to 140%. If the content of the epoxy resin (D) exceeds 200%, the developability of the photosensitive resin composition of the present invention may be significantly reduced, which is not preferable. If the content of the epoxy resin (D) is less than 80%, carboxyl groups may remain in the cured product of the present invention, which may reduce the insulation reliability.

The epoxy resin (D) represented by the general formula (1) may be mixed in advance with the resin composition, but it is preferable to mix it before applying it to the printed circuit board. In other words, it is preferable to mix a base solution mainly made of the component (A) and containing an epoxy curing accelerator, etc., and an epoxy resin solution mainly made of the epoxy resin (D) represented by the general formula (1) into a two-liquid type, and mix these when using.

When preparing the photosensitive resin composition of the present invention, various additives can be added as necessary to enhance the performance of the composition, such as fillers such as talc, barium sulfate, calcium carbonate, magnesium carbonate, barium titanate, aluminum hydroxide, aluminum oxide, silica, and clay, thixotropy-imparting agents such as Aerosil, colorants such as phthalocyanine blue, phthalocyanine green, and titanium oxide, silicone-based leveling agents (e.g., KS-66), fluorine-based leveling agents and defoamers (e.g., BYK-354), polymerization inhibitors such as hydroquinone and hydroquinone monomethyl ether, and heat curing catalysts (e.g., triphenylphosphine, described in the Examples below).

The photosensitive resin composition of the present invention can be obtained, for example, by mixing the carboxyl group-containing photosensitive resin (A) with a crosslinking agent (B), a photopolymerization initiator (C), and an epoxy resin (D) as a curing agent.

The photosensitive resin composition of the present invention can also be used as a dry film resist having a structure in which the resin composition is sandwiched between a support film and a protective film. The photosensitive resin composition of the present invention is preferably processed into a liquid or film form.

The photosensitive resin composition of the present invention is useful, for example, as a solder resist for printed circuit boards, a resist material such as a coverlay, an insulating material between layers of electronic components, and an optical waveguide for connecting optical components. It can also be used as a color filter, a printing ink, a sealant, a paint, a coating agent, an adhesive, etc.

The cured product of the present invention is obtained by curing the above-mentioned photosensitive resin composition of the present invention by irradiation with energy rays such as ultraviolet rays. Curing by irradiation with energy rays such as ultraviolet rays can be carried out by a conventional method. For example, when irradiating with ultraviolet rays, an ultraviolet generating device such as a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, or an ultraviolet emitting laser (excimer laser, etc.) may be used.

The above printed circuit board can be obtained, for example, as follows. That is, when a liquid resin composition is used, the photosensitive resin composition of the present invention is applied to a printed wiring board in a film thickness of 5 to 160 μm by a method such as screen printing, spraying, roll coating, electrostatic painting, or curtain coating, and the coating film is dried at a temperature of usually 50 to 110 ° C., preferably 60 to 100 ° C., to form a coating film. Thereafter, the coating film is directly or indirectly irradiated with high-energy rays such as ultraviolet rays at an intensity of usually about 10 to 2000 mJ/cm ² through a photomask having an exposure pattern such as a negative film, and the unexposed parts are developed using a developer described later, for example, by spraying, rocking immersion, brushing, scrubbing, or the like. Thereafter, if necessary, ultraviolet rays are further irradiated, and then heat treatment is performed at a temperature of usually 100 to 200 ° C., preferably 140 to 180 ° C., to obtain a printed circuit board having a permanent protective film that is excellent in gold plating and satisfies various properties such as heat resistance, solvent resistance, acid resistance, adhesion, and flexibility.

The alkaline aqueous solution used for development can be an inorganic alkaline aqueous solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, or potassium phosphate, or an organic alkaline aqueous solution such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, monoethanolamine, diethanolamine, or triethanolamine.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, parts are by weight unless otherwise specified.

The epoxy equivalent, acid value and GPC were measured under the following conditions.
1) Epoxy equivalent (WPE): Measured according to a method in accordance with JIS K 7236:2001.
2) Acid value: Measured according to a method in accordance with JIS K 0070:1992.
3) The measurement conditions for GPC are as follows:
Model: TOSOH HLC-8220GPC
Column: TSKGEL Super HZM-N
Eluent: THF (tetrahydrofuran); 0.35 ml/min, temperature 40° C.
Detector: Differential refractometer Molecular weight standard: Polystyrene

Synthesis Example 1: Synthesis of Acid-Modified Polyurethane Resin Solution (A-1) In a 300 mL flask equipped with a stirrer and a reflux condenser, 342.38 g of bisphenol A type epoxy resin (trade name RE-310S, WPE = 184 g / eq, manufactured by Nippon Kayaku Co., Ltd.) as an epoxy compound (a) having two or more epoxy groups in one molecule, 155.38 g of methacrylic acid as a monocarboxylic acid (b) having an ethylenically unsaturated group in one molecule, and 0.75 g of triphenylphosphine as a catalyst were added, and reacted at a temperature of 120 ° C. until the acid value of the reaction solution became 3 mg KOH / g or less, to obtain an unsaturated epoxy carboxylate compound. In addition, the epoxy value was measured to be 13 kg / eq, and it was also confirmed that the epoxy group had reacted sufficiently. The reaction time at this time was 24 hours.

Next, in a 300 mL flask equipped with a stirrer and reflux condenser, 475.06 g of the unsaturated epoxy carboxylate compound obtained earlier, 116.55 g of dimethylolpropionic acid as a carboxylic acid having two hydroxyl groups in one molecule (d), 234.53 g of dimer acid polyester polyol (trade name PRIPLAST XL 101, manufactured by CRODA Co., Ltd.) as an arbitrary diol compound (e), and diethylene glycol monoethyl ether acetate (abbreviated CA) as a solvent were added in the amounts shown in Table 1 so that the solid content of polyurethane compound (A) was 63%, and the mixture was stirred and dissolved at 80 ° C. Then, 233.77 g of hexamethylene diisocyanate was added as diisocyanate compound (c) using a dropping funnel and reacted. After the dropwise addition, the reaction was continued at a temperature of 80 ° C. for 10 hours, and it was confirmed that there was no absorption peak derived from the isocyanate group in the infrared absorption spectrum, and a polyurethane compound was obtained. At this time, the weight average molecular weight measured using GPC in terms of polystyrene was 17,000.

After that, 7.42 g of the CA solution of the polyurethane compound obtained earlier was added to a 300 mL flask equipped with a stirrer and reflux condenser, and further 4.94 g of succinic anhydride (manufactured by New Japan Chemical Co., Ltd.) as polybasic acid anhydride (f) was added. CA was further added as a solvent so that the final solid content was 63%, and the mixture was stirred and dissolved, and the reaction was continued at a temperature of 100°C for 5 hours to obtain a resin solution (A-1) containing an acid-modified polyurethane compound. The acid value of this acid-modified polyurethane compound was 75.1 mg KOH/g. At this time, the weight average molecular weight in terms of polystyrene measured using GPC was 18,000.

Synthesis Example 2: Synthesis of Epoxy Resin (D-1) While purging with nitrogen into a flask equipped with a thermometer, a cooling tube, a fractionating tube, and a stirrer, 380 g of tetramethylbiphenol type epoxy resin (trade name YX-4000H, manufactured by Mitsubishi Chemical Corporation), 98 g of 4,4'-biphenol, and 100 g of methyl isobutyl ketone were charged, and the temperature was raised to 100°C under stirring, after which 0.38 g of triphenylphosphine was added, and the reaction was carried out at 100°C for 3 hours and at 120°C for 10 hours, and then methyl isobutyl ketone was distilled off to obtain epoxy resin (D-1) (represented by formula (1), n calculated from the area ratio of GPC was about 2.1 on average) as a resinous solid. The softening point of the obtained resin was 84°C, and the epoxy equivalent was 501 g/eq.

The resin solution (A-1) containing the acid-modified polyurethane compound obtained in Synthesis Example 1 and the epoxy resin (D-1) obtained in Synthesis Example 2 were mixed in the proportions shown in Table 1, and then uniformly dispersed in a stirrer to obtain a photosensitive resin composition.

注
＊１ 日本化薬（株）製：ε－カプロラクトン変性ジペンタエリスリトールヘキサアクリレート
＊２ ＩＧＭ Ｒｅｓｉｎｓ Ｂ．Ｖ． 製：２－メチル－（４－（メチルチオ）フェニル）－２－モルホリノプロパン－１－オン
＊３ 日本化薬（株）製：２，４－ジエチルチオキサントン
＊４ 日鉄ケミカル＆マテリアル（株）製：ビスフェノール－Ａ型エポキシ樹脂
＊５ 三菱ケミカル（株）製：テトラメチルビフェノール型エポキシ樹脂
＊６ 日本化薬（株）製：特殊多官能型エポキシ樹脂
＊７ 日本化薬（株）製：ビスフェノール－Ａ型エポキシ樹脂
＊８ 日本化薬（株）製：ジシクロペンタジエンフェノール型エポキシ樹脂
＊９ 北興化学工業（株）製：トリフェニルホスフィン
＊１０ 神港有機化学工業（株）製：ジエチレングリコールモノエチルエーテルアセテート [Table 1]

Notes *1 Nippon Kayaku Co., Ltd.: ε-caprolactone modified dipentaerythritol hexaacrylate *2 IGM Resins B.V.: 2-methyl-(4-(methylthio)phenyl)-2-morpholinopropan-1-one *3 Nippon Kayaku Co., Ltd.: 2,4-diethylthioxanthone *4 Nippon Steel Chemical & Material Co., Ltd.: Bisphenol-A type epoxy resin *5 Mitsubishi Chemical Co., Ltd.: Tetramethylbiphenol type epoxy resin *6 Nippon Kayaku Co., Ltd.: Special multifunctional epoxy resin *7 Nippon Kayaku Co., Ltd.: Bisphenol-A type epoxy resin *8 Nippon Kayaku Co., Ltd.: Dicyclopentadiene phenol type epoxy resin *9 Hokko Chemical Industry Co., Ltd.: Triphenylphosphine *10 Shinko Organic Chemical Industry Co., Ltd.: Diethylene glycol monoethyl ether acetate

Each evaluation item is explained in detail below.

Developability evaluation (abbreviation in table: developability)
The resist resin composition was applied to a copper-clad laminate ELC-4762 (manufactured by Sumitomo Bakelite Co., Ltd.) with an applicator to a thickness of 20 μm, and the coating film was dried for 30 minutes in a hot air dryer at 80° C., after which it was covered with a mask of vias (diameter 500 μm) and irradiated with ultraviolet light at an energy of 500 mJ/cm ² using an ultraviolet irradiator (USHIO (ultra-high pressure mercury lamp)). Thereafter, spray development was carried out using a 1% aqueous sodium carbonate solution as a developer. The developability was evaluated based on whether the coating film was completely dissolved and the vias were opened.
〇 No residue × Residue present

Thermal decomposition resistance evaluation (abbreviation in table: thermal decomposition resistance)
The resist resin composition was applied to rolled copper foil BHY-82F-HA-V2 (manufactured by JX Metals Co., Ltd.) with an applicator to a thickness of 20 μm, and the coating was dried in a hot air dryer at 80 ° C for 30 minutes, and then irradiated with ultraviolet light at an energy of 500 mJ / cm ² using an ultraviolet irradiator (GS YUASA: CS 30L-1). Next, the cured product was obtained by curing in an oven at 150 ° C for 30 minutes. The copper foil was removed with iron (III) chloride 45 ° Baume (manufactured by Junsei Chemical Co., Ltd.). The temperature at which the weight of the sample produced by 3 mg of the cured product was reduced by 5% was measured using a METTLER TGA / DSC1 in an air flow of 100 ml per minute.

Glass transition temperature measurement (abbreviated as Tg in the table)
The resist resin composition was applied to rolled copper foil BHY-82F-HA-V2 (manufactured by JX Metals Co., Ltd.) with an applicator to a thickness of 20 μm, and the coating was dried in a hot air dryer at 80 ° C. for 30 minutes, and then irradiated with ultraviolet light at an energy of 500 mJ / cm ² using an ultraviolet irradiator (GS YUASA: CS 30L-1). Next, the product was cured in an oven at 150 ° C. for 30 minutes to obtain a cured product. The copper foil was removed with iron (III) chloride 45 ° Baume (manufactured by Junsei Chemical Co., Ltd.). The sample from which the cured product was produced was subjected to DMA measurement (TA Instruments: RSA-G2) to determine the temperature at which tangent δ was maximized.

Measurement of tensile modulus and elongation at break The resist resin composition was applied to rolled copper foil BHY-82F-HA-V2 (manufactured by JX Metals Co., Ltd.) with an applicator to a thickness of 20 μm, and the coating film was dried in a hot air dryer at 80 ° C. for 30 minutes, and then irradiated with ultraviolet light at an energy of 500 mJ / cm ² using an ultraviolet irradiator (GS YUASA: CS 30L-1). Next, the film was cured in an oven at 150 ° C. for 30 minutes to obtain a cured product, and the copper foil was removed with iron (III) chloride 45 ° Baume (manufactured by Junsei Chemical Co., Ltd.). The obtained cured film was cut into a length of 50 mm and a width of 5 mm, and the tensile modulus (MPa) and elongation at break (%) were measured using Tensilon (A & D Co., Ltd.: RTG-1210) at a chuck distance of 4 cm and a temperature of 23 ° C. at a pulling speed of 5 mm / min.

Migration evaluation Each composition was applied to a thickness of 25 μm on ESPANEX M series (manufactured by Nippon Steel Chemical: base imide thickness 25 μm, Cu thickness 18 μm) on which a comb-shaped pattern of L/S=100 μm/100 μm was formed, and the coating film was dried in an oven at 80 ° C. for 30 minutes. Next, the coating was cured by exposure to 500 mJ/cm ² using an ultraviolet exposure device (manufactured by GS YUASA: CS 30L-1), and then dried in an oven at 150 ° C. for 1 hour to obtain a test substrate for evaluation. The electrode portion of the obtained substrate was wired and connected by solder, placed in an environment of 130 ° C./85% RH, and migration evaluation was performed by applying a voltage of 100 V.
○ 100 hours or more △ 50 hours or more but less than 100 hours × Less than 50 hours

[Table 2]

As is clear from the above results, the photosensitive resin composition of the present invention has excellent developability, does not peel off after development, and has sufficient adhesion. In addition, the cured film also has excellent heat resistance, elasticity, and flexibility, making it particularly suitable as a photosensitive resin composition for printed circuit boards.

The photosensitive resin composition of the present invention has excellent developability when it is exposed to ultraviolet light and cured to form a coating film, and the obtained cured product has sufficient heat resistance, elastic modulus, flexibility, and resistance to electroless gold plating, and can be suitably used for photocurable coating materials, photocurable adhesives, etc., and is particularly suitable for use as a photosensitive resin composition for printed circuit boards and a photosensitive resin composition for forming optical waveguides.
The composition can be suitably used in applications requiring particularly high reliability, such as solder resists for flexible printed wiring boards, solder resists for printed wiring boards, interlayer insulating materials for multilayer printed wiring boards, plating resists, and photosensitive optical waveguides.

Claims (8)

A photosensitive resin composition comprising a carboxyl group-containing photosensitive resin (A), a crosslinking agent (B), a photopolymerization initiator (C), and an epoxy resin (D) represented by the following general formula (1) as a curing agent:

In formula (1), each of a plurality of Ar's independently represents a group represented by formula (X)

Or formula (Y)

(In formula (Y), R independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, an allyl group, or a phenyl group, and at least one R is other than a hydrogen atom.)
Formula (X) and formula (Y) can be arbitrarily selected, but at least one of formula (X) and formula (Y) is contained in one molecule. n is the average number of repetitions, and 1≦n<20.) The photosensitive resin composition according to claim 1, wherein the carboxyl group-containing photosensitive resin (A) is a polyurethane compound (A1) obtained by reacting an unsaturated epoxy carboxylate compound (c) obtained by reacting an epoxy compound (a) having two epoxy groups in one molecule with a monocarboxylic acid (b) having an ethylenically unsaturated group in one molecule, a diisocyanate compound (d), a carboxylic acid (e) having two hydroxyl groups in one molecule, and, if necessary, an optional polyester diol compound (f). The photosensitive resin composition according to claim 2, wherein the carboxyl group-containing photosensitive resin (A) is an acid-modified polyurethane compound (A2) obtained by reacting a polyurethane compound (A1) with a polybasic acid anhydride (g). The photosensitive resin composition according to claim 1, wherein the carboxyl group-containing photosensitive resin (A) is a reaction product (A3) of an unsaturated epoxy carboxylate compound (c') obtained by reacting an epoxy compound (a') having two or more epoxy groups in one molecule with a monocarboxylic acid (b) having an ethylenically unsaturated group in one molecule, and a polybasic acid anhydride (g). The photosensitive resin composition according to any one of claims 1 to 4, wherein Ar at both ends is represented by formula (Y). The epoxy photosensitive resin composition according to any one of claims 1 to 5, wherein all R in formula (1) are methyl groups. The photosensitive resin composition according to any one of claims 1 to 6, which is a resist material. A cured product of the photosensitive resin composition according to any one of claims 1 to 7.