JP4630199B2 - Photosensitive resin composition - Google Patents

Description

  The present invention relates to a photosensitive resin composition that can be photocured to form an image, for example.

  Photosensitive resin compositions for image formation are capable of microfabrication by applying the principle of photolithography (photolithography) and can form images by giving cured products with excellent physical properties. Are widely used for various resist materials and printing plates. There are a solvent development type and an alkali development type in this photosensitive resin composition for image formation, but in recent years, an alkali development type that can be developed with a dilute weak alkaline aqueous solution has become mainstream from the viewpoint of environmental measures. Alkali-developable photosensitive resin compositions are also used in printed wiring board production, liquid crystal display board production, printing plate making and the like.

  When the photosensitive resin composition for image formation is used in a photolithography process as a resin composition for a liquid development type solder resist, for example, the resin composition is first applied on a substrate, and then dried by heating. A series of steps is employed in which after forming a coating film, a film for forming a pattern is attached to the coating film, exposed, and developed. In such a process, if adhesiveness remains in the coating film after drying by heating, a part of the resist adheres to the pattern forming film after peeling, and an accurate pattern cannot be reproduced. There was a problem that the forming film could not be peeled off. For this reason, tack-free property after coating film formation is an important required characteristic of a liquid development type resist.

  In addition, photosensitivity during exposure and developability after exposure are also important required characteristics. That is, in order to form a fine pattern with high reliability and good reproducibility, during development, a portion cured by exposure must not be eroded by the developer, and conversely, an unexposed portion can be promptly developed during development. Must be removed.

  Furthermore, for the cured part, characteristics related to long-term reliability such as heat resistance, water resistance, moisture resistance, etc. that can withstand processing steps under high temperature conditions (solder resist in the case of solder resist, etc.) are required. ing.

  Carboxyl group-containing epoxy (meth) acrylate in which a carboxyl group is introduced by reacting an acid anhydride with an epoxy (meth) acrylate obtained by reacting an epoxy resin with (meth) acrylic acid to satisfy the above characteristics to some extent. It has been known. This carboxyl group-containing epoxy (meth) acrylate satisfies a balanced balance of tack-free properties, photosensitivity, and developability, and compares important properties such as heat resistance and water resistance required for cured products. Good. However, with the advancement of technology, higher level characteristics are required, and for example, it is required to withstand high dimensional stability that can be adapted to fine pattern formation and processing at higher temperature conditions. It has become so.

  If it is said epoxy (meth) acrylate, it is thought that heat resistance will be improved by introducing many double bonds into the resin skeleton using polyfunctional epoxy resin or (meth) acrylate and increasing the crosslinking density. It is done. However, if the amount of double bonds introduced is increased, the dimensional stability becomes poor due to curing shrinkage due to the decrease in free volume during curing, and the cured coating film becomes brittle due to the increased crosslink density. The epoxy (meth) acrylate photosensitive resin has a problem that it is difficult to achieve improvement in dimensional stability and reduction in brittleness while maintaining high heat resistance.

By the way, polyphenylene ether (PPE) obtained by oxidative polymerization is attracting attention as one of engineering plastics because of its excellent heat resistance and mechanical properties. However, PPE is poor in melt fluidity and inferior in moldability, and therefore is often modified by polymer alloy. Moreover, the technique which introduce | transduces a functional group into PPE by selecting a copolymerization partner and makes it a compatibilizer in the case of a polymer alloy is also known (for example, patent documents 1, 2).
JP-A-4-202223 Japanese Patent Laid-Open No. 5-78470

  As described above, recent photosensitive resins are required to have dimensional stability and reduced brittleness as well as heat resistance of the cured coating film, and these required levels are not limited. Therefore, in the present invention, modified PPE is used as a resin component of the photosensitive resin composition to ensure heat resistance, and it has excellent characteristics such as alkali developability, tack-free property, photosensitivity, dimensional stability, and the occurrence of brittleness. An object of the present invention is to provide a photosensitive resin composition that can give a cured product that is not cured.

  In Patent Documents 1 and 2, no consideration is given to the use of PPE as the resin component of the photosensitive resin composition.

  The photosensitive resin composition of the present invention that has solved the above problems has a gist in that it contains a resin (A) having a structural unit (a) represented by the following formula, a radical polymerizable compound, and a photopolymerization initiator.

(In the formula, R ^{1 to} R ⁴ do not have radically polymerizable double bonds, and at least one is a carboxyl group or an organic group having a terminal carboxyl group and a carboxylate ester bond. And the others are the same or different and each represents hydrogen, an alkyl group, an alkoxy group, a hydroxyl group, a hydroxyalkyl group, a hydroxyalkoxy group, a hydroxyalkylthio group, or an aryl group.

  The resin (A) is preferably obtained by a reaction between a resin (B) having a structural unit (b) represented by the following formula and a polybasic acid anhydride.

(Wherein R ^{5 to} R ⁸ do not have radically polymerizable double bonds and at least one is a hydroxyl group or represents an organic group having a hydroxyl group, and the other is the same or different. Represents hydrogen, an alkyl group, an alkoxy group, or an aryl group.

More preferably, at least one of the substituents R ^{5 to} R ⁸ of the structural unit (b) is a 2-hydroxyethoxy group and / or a 2-hydroxyethylthio group. Specifically, the resin (B) Is preferably obtained by oxidative polymerization of a raw material mixture containing the following phenol compound (1).

(In the formula, at least one of R ^{5 to} R ⁸ is a 2-hydroxyethoxy group and / or 2-hydroxyethylthio group, and the other is the same or different, and represents a hydrogen, an alkyl group, an alkoxy group or an aryl group. To express.)

  An embodiment in which the resin (B) is an oxidative copolymer obtained from the following phenol compound (2) and 2,6-dimethylphenol and / or cresol is the most preferred embodiment of the present invention.

(In the formula, X represents O or S.)

  The resin (A) may further have the following structural unit (c).

(In the formula, at least one of R ^{9 to} R ¹² is an organic group having a radical polymerizable double bond, and the other is the same or different and has hydrogen, an alkyl group, an alkoxy group, a carboxyl group, or a carboxyl group. An organic group, a hydroxyl group, a hydroxyalkyl group, a hydroxyalkoxy group, a hydroxyalkylthio group, or an aryl group is represented.)

  Since the photosensitive resin composition of the present invention combines a modified PPE and a radically polymerizable (photo-curable) compound, it is possible to achieve both sensitivity during exposure and alkali developability, and maintain high heat resistance. However, a cured product having excellent dimensional stability and exhibiting no brittleness could be obtained. Therefore, the photosensitive resin composition of the present invention is an alkali-developable photosensitive resin composition for image formation, such as a solder resist for printed wiring boards, an etching resist, an electroless plating resist, and a build-up method printed wiring board. It can be suitably used for various applications such as an insulating layer, liquid crystal display plate production, and printing plate making.

  The present invention is described in detail below. The resin (A) which is an essential component of the photosensitive resin composition of the present invention has a structural unit (a) represented by the following formula as a repeating unit.

(In the formula, R ^{1 to} R ⁴ do not have radically polymerizable double bonds, and at least one is a carboxyl group or an organic group having a terminal carboxyl group and a carboxylate ester bond. And the others are the same or different and each represents hydrogen, an alkyl group, an alkoxy group, a hydroxyl group, a hydroxyalkyl group, a hydroxyalkoxy group, a hydroxyalkylthio group, or an aryl group.

The carboxyl group which the said structural unit (a) has is required in order to provide alkali developability to resin (A). A carboxyl group may be directly attached to the aromatic ring, or a carboxyl group may be present at the terminal via a carboxylic acid ester bond. Introducing a carboxyl group at a position away from the main chain results in better alkali developability. Therefore, it is preferable that a carboxyl group is present at the terminal via a carboxylate ester bond. Among R ^{1 to} R ^4, the number of the directly bonded carboxyl group and / or the terminal carboxyl group and the organic group having a carboxylate ester bond may be 1 to 4, but is preferably 1.

In the above formula, the reason that “R ^{1 to} R ⁴ do not have radically polymerizable double bonds” is to distinguish from the structural unit (c) described later.

  In the above formula, as the alkyl group, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tert-butyl group, n-amyl group, n-hexyl group, An n-octyl group, 2-cyanoethyl group, 3-cyanopropyl group and the like can be mentioned. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

  Examples of the hydroxyalkyl group include a hydroxymethyl group, a 2-hydroxyethyl group, and a 3-hydroxypropyl group. Examples of the hydroxyalkoxy group include a hydroxymethoxy group, a 2-hydroxyethoxy group, and a 2-hydroxypropoxy group. It is done. Examples of the hydroxyalkylthio group include a hydroxymethylthio group, a 2-hydroxyethylthio group, and a 2-hydroxypropylthio group.

  Examples of the aryl group include a phenyl group and a naphthyl group which may have a substituent.

  In order to impart good alkali developability to the resin (A), the structural unit (a) is preferably present in an average of 5 or more in one molecule of the resin (A). The number of the structural unit (a) is more preferably 6 or more, and even more preferably 7 or more. The greater the amount, the better the alkali developability even with a weak alkaline aqueous solution. However, since the water resistance of the cured coating film may decrease if the amount is too large, the upper limit of the number of structural units (a) is preferably 90.

  Moreover, if the suitable amount of carboxyl groups is expressed as the acid value of the resin (A), it is preferably 30 mgKOH / g or more (more preferably 50 mgKOH / g or more), 180 mgKOH / g or less (more preferably 150 mgKOH / g or less). From the viewpoint of developability, it is preferable that the structural unit (a) is present randomly in the resin (A).

  The resin (A) is preferably obtained by a reaction between a resin (B) having a structural unit (b) represented by the following formula and a polybasic acid anhydride.

(Wherein R ^{5 to} R ⁸ do not have radically polymerizable double bonds and at least one is a hydroxyl group or represents an organic group having a hydroxyl group, and the other is the same or different. Represents hydrogen, an alkyl group, an alkoxy group, or an aryl group.

When a polybasic acid anhydride is reacted with a hydroxyl group having a direct bond in the structural unit (b) of the resin (B) or an organic group having a hydroxyl group, the terminal is a carboxyl group via a carboxylate ester bond. Is introduced into the aromatic ring. That is, —R—O—A—COOH or —R—C (O) O—A—COOH (where R is an organic group to which a hydroxyl group was bonded, A is other than an acid anhydride group in a polybasic acid anhydride) Organic group) is introduced. Further, for example, among R ^{5 to} R ⁸ , when one hydroxyl group or an organic group having a hydroxyl group is made to react with an equimolar amount with a dibasic acid anhydride, the structural unit (a) of the resin (A) is obtained. ), A single organic group having a carboxyl group at the end can be formed through a carboxylic acid ester bond.

  Polybasic acid anhydrides include phthalic anhydride, succinic anhydride, octenyl succinic anhydride, pentadodecenyl succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, 3,6- Reaction of endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, tetrabromophthalic anhydride, 9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide with itaconic anhydride or maleic anhydride Dibasic acid anhydrides such as products; trimellitic anhydride; biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarbo Acid dianhydride, pyromellitic acid anhydride, aliphatic such as benzophenone tetracarboxylic acid dianhydride or aromatic tetracarboxylic acid dianhydride and the like, can be used alone or in combination.

  The reaction between the resin (B) and the polybasic acid anhydride is carried out in such a manner that the hydroxyl group and the acid anhydride group are equimolar (if the hydroxyl group is to remain as described later, the number of moles of the acid anhydride group is the hydroxyl group. The reaction temperature is preferably 60 to 150 ° C., more preferably 80 to 130 ° C. in the presence of a catalyst or a solvent as necessary. Specific catalysts include tertiary amines such as triethylamine, quaternary ammonium salts such as triethylbenzylammonium chloride, imidazole compounds such as 2-ethyl-4-methylimidazole, phosphorus such as triphenylphosphine and tetraphenylphosphonium bromide. Examples thereof include a compound, a carboxylic acid metal salt such as lithium acetate, and an inorganic metal salt such as lithium carbonate.

Preferred examples of the organic group having a hydroxyl group in the above formula include the hydroxyalkyl group and hydroxyalkylthio group described above. Of these, a 2-hydroxyethoxy group and a 2-hydroxyethylthio group are preferable. These are preferably R ⁵ or R ⁸ . At this time, at least one of the other substituents is preferably hydrogen. In addition, the preferable specific example of the alkyl group in the said formula, an alkoxy group, and an aryl group is as said illustration.

  The resin (B) can be obtained by oxidative polymerization of a raw material mixture containing a phenol compound represented by the following formula.

(Wherein R ^{5 to} R ⁸ do not have radically polymerizable double bonds and at least one is a hydroxyl group or represents an organic group having a hydroxyl group, and the other is the same or different. Represents hydrogen, an alkyl group, an alkoxy group, or an aryl group.

More preferred phenolic compounds are those in which at least one of R ^{5 to} R ⁸ is a 2-hydroxyethoxy group and / or 2-hydroxyethylthio group, and the other is the same or different and is a hydrogen, alkyl group And a phenol compound (1) represented by the following formula, which is an alkoxy group or an aryl group.

  Specific examples of the phenol compound (1) include 2- (2-hydroxyethoxy) -3-methylphenol, 2- (2-hydroxyethoxy) -6-methylphenol, and 3- (2-hydroxyethoxy) -2. -Methylphenol, 2-ethyl-5- (2-hydroxyethoxy) phenol and the like.

  A more preferred phenolic compound is a phenolic compound (2) represented by the following formula, having a 2-hydroxyethoxy group or a 2-hydroxyethylthio group and having no other substituents (others are hydrogen).

(In the formula, X represents O or S.)

  The substituent of the phenol compound (2) is a 2-hydroxyethoxy group when X is O, and a 2-hydroxyethylthio group when X is S. These substituents are preferably in the 2-position with respect to the hydroxyl group of the aromatic ring.

  In the oxidative polymerization, the phenol compound (1) or (2) and polyphenylene ether (PPE) are usually synthesized with a phenol used in the synthesis to form the structural unit (b) in the resin (B). ) (Which is the same as the number of structural units (a) in the resin (A)), and as a result, the number of structural units (a) and the acid value of the resin (A) are controlled within the above range. It is preferable. In order to keep the acid value in the resin (A) within the above range, the phenol compound (1) or (2) is 5 to 95% by mass in 100% by mass of the raw material mixture used for the polymerization of the resin (B). It is recommended. When the phenol compound (1) other than the phenol compound (2) is used, the acid value can also be controlled by controlling the amount of hydroxyl groups of the phenol compound (1).

  Further, as described later, when the radical polymerizable double bond introduction reaction is performed using the carboxyl group of the resin (A) or the hydroxyl group of the resin (B), the resin (A) finally obtained The amount of the phenol compound (1) or (2) is determined in consideration of the amount of carboxyl group and / or hydroxyl group consumed in the radical polymerizable double bond introduction reaction so that the acid value falls within the above range. It is preferable.

  Preferable examples of phenols that can be used as a copolymerization partner for the phenol compound (1) or (2) include 2,6- (2,4-, 2,5-, 3,5-) dimethylphenol, 2 , 6- (2,4-, 2,5-, 3,5-) dimethoxyphenol, o- (m-, p-) cresol, 2,6-diphenylphenol, 2-methyl-6-t-butylphenol, 2-methoxy-6-t-butylphenol, 2,3,6-trimethylphenol, 2,3,6-trimethoxyphenol and the like. Two or more of these may be used. Among these, 2,6-dimethylphenol and cresol are preferable, and 2,6-dimethylphenol is most preferable.

  The oxidation polymerization may be performed by a method known as a PPE synthesis method. For example, a cuprous salt (such as copper chloride) and an amine (such as pyridine) are used as the catalyst, and the reaction is performed at about 10 to 50 ° C. in an air atmosphere. The oxidative polymerization is preferably carried out in a solvent. Solvents that can be used include aromatic compounds such as toluene, xylene, nitrobenzene and chlorobenzene; cellosolve acetate, carbitol acetate, (di) propylene glycol monomethyl ether acetate, glutaric acid ( Di) Esters such as methyl, succinic acid (di) methyl, adipic acid (di) methyl, methyl acetate, ethyl acetate, butyl acetate, methyl propionate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; diethyl ether , Ethers such as diisopropyl ether, tetrahydrofuran, 1,4-dioxane, methyl-t-butyl ether, (di) ethylene glycol dimethyl ether; amides such as N, N-dimethylacetamide; Sulfoxides such as methyl sulfoxide and the like, can be used as a mixture of two or more thereof.

  The molecular weight of the resin (B) is preferably 1000 or more, more preferably 2000 or more, as a weight average molecular weight (Mw). If it is too small, the properties of the cured coating film may be deteriorated. The upper limit of Mw is not particularly limited, but is preferably 100,000 or less and more preferably 50000 or less from the viewpoint of handleability.

  If resin (B) is synthesize | combined, as above-mentioned, resin (A) can be obtained by making a polybasic acid anhydride react with a hydroxyl group.

  When synthesizing a resin (A) having a carboxyl group directly bonded to an aromatic ring, hydroxybenzoic acid such as salicylic acid or methylsalicylic acid is used as the phenol compound (1), or carboxylic acid esters thereof. The ester group may be decomposed and converted to a carboxyl group after oxidative polymerization.

  In this invention, you may use what has the following structural unit (c) as resin (A).

(In the formula, at least one of R ^{9 to} R ¹² is an organic group having a radical polymerizable double bond, and the other is the same or different and has hydrogen, an alkyl group, an alkoxy group, a carboxyl group, or a carboxyl group. It represents any one of an organic group, a hydroxyl group, a hydroxyalkyl group, a hydroxyalkoxy group, and a hydroxyalkylthio group.)

  If the resin (A) has the above structural unit (c), it will have a radical polymerizable double bond in the molecule, so that the photocuring reaction is carried out together with the radical polymerizable compound in the resin composition. Therefore, heat resistance, dimensional stability, mechanical properties, etc. of the resulting cured coating film are improved.

  Examples of the organic group having a radical polymerizable double bond include an alkenyl group and an allyl group. The functional group capable of reacting with the carboxyl group on the carboxyl group of the structural unit (a) of the resin (A) and a radical A functional group capable of reacting with the hydroxyl group and a radically polymerizable double bond are reacted with the hydroxyl group of the structural unit (b) of the resin (B) by reacting an ethylenically unsaturated compound having a polymerizable double bond. An organic group obtained by reacting a compound having the above is desirable. As the radical polymerizable double bond, a (meth) acryloyl group having excellent photopolymerizability is desirable.

  Examples of the functional group capable of reacting with a carboxyl group include an epoxy group, a vinyl ether group, an oxazolinyl group, an aziridinyl group, and an oxetanyl group. Specific examples of the ethylenically unsaturated compound having a functional group capable of reacting with a carboxyl group include aliphatic epoxy compounds such as glycidyl (meth) acrylate, allyl glycidyl ether, 4-hydroxybutyl acrylate glycidyl ether, and 3,4- Epoxy group-containing ethylenically unsaturated compounds such as alicyclic epoxy compounds such as epoxycyclohexylmethyl (meth) acrylate, 2- (vinyloxyethoxy) ethyl (meth) acrylate, 2-isopropenyl-2-oxazoline, N- (Meth) acryloylaziridine, 3- (meth) acryloxymethyloxetane, and the like can be used, and one or more of these can be used.

  Examples of the functional group capable of reacting with a hydroxyl group include an isocyanate group and a vinyl ether group. Specific examples of the ethylenically unsaturated compound having a functional group capable of reacting with a hydroxyl group include isocyanate ethyl (meth) acrylate, 2- (vinyloxyethoxy) ethyl (meth) acrylate, etc. Among these, 1 Species or two or more can be used. In addition, when making the hydroxyl group of resin (B) and the ethylenically unsaturated compound which has a functional group which can react with a hydroxyl group react before and after reaction with a polybasic acid anhydride, simultaneously, arbitrary Can be done in stages. The radical polymerizable double bond introduction reaction may be performed by appropriately selecting a catalyst and a reaction temperature for each functional group by a known method.

  When introducing the radical polymerizable double bond in both the resin (A) and the resin (B), the final amount of the carboxyl group of the resin (A) is not short, that is, the resin (A). It is necessary to introduce a radically polymerizable double bond so that the acid value of is not less than the preferred range. However, when alkali developability is not required for the use of the photosensitive resin, the structural unit (a) may be small, for example, the resin (A) is composed only of the structural unit (c).

  A suitable amount in the case of introducing a radical polymerizable double bond is not particularly limited, but the ethylenically unsaturated compound is contained in 1 mol of the carboxyl group of the resin (A) or 1 mol of the hydroxyl group of the resin (B). It is preferable that the functional group be 0.8 mol or less.

  In the photosensitive resin composition of the present invention, the second essential component is a radical polymerizable compound. This is used for photo radical polymerization to cure the resin coating. Since the photosensitive resin composition of the present invention can be photocured by the presence of the radical polymerizable compound, the resin (A) does not necessarily have the above structural unit (c).

  Examples of the radical polymerizable compound include a radical polymerizable resin and a radical polymerizable monomer.

  As the radical polymerizable resin, unsaturated polyester, epoxy (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, or the like can be used.

  When these radical polymerizable resins are used as the radical polymerizable compound, in order to effectively exhibit the heat resistance improving effect derived from the resin (A) of the photosensitive resin composition of the present invention, the resin ( A) It is preferable to use the radical polymerizable resin at 300 parts by mass or less with respect to 100 parts by mass. A more preferred upper limit is 200 parts by mass, and a more preferred upper limit is 150 parts by mass.

  Among the above radical polymerizable resins, epoxy (meth) acrylate, in particular, has good photopolymerizability and is effective in improving the properties of the resulting cured product. Therefore, the photosensitivity of the photosensitive resin composition of the present invention. It can be suitably used as a resin component. As the epoxy (meth) acrylate, a reaction product of a known epoxy resin having two or more epoxy groups in one molecule and an unsaturated monobasic acid (such as (meth) acrylic acid) can be used as it is.

  A preferable epoxy resin is an epoxy resin having three or more epoxy groups in one molecule, more preferably a novolac type epoxy resin, and further, when a novolac type epoxy resin having a softening point of 75 ° C. or higher is used, the heat drying is performed. It is preferable in that the tack-free property at the time of coating film formation is improved. It is also possible to use a carboxyl group-containing epoxy (meth) acrylate obtained by addition reaction of the above-mentioned polybasic acid anhydride with the hydroxyl group of the epoxy (meth) acrylate to the epoxy (meth) acrylate. A level of alkali developability can be ensured. The reaction between the epoxy (meth) acrylate and the polybasic acid anhydride can be performed in the same manner as the reaction between the hydroxyl group and the polybasic acid anhydride.

  A radical polymerizable monomer can be used as the radical polymerizable compound, and either a monofunctional (one radical polymerizable double bond) monomer or a polyfunctional monomer (two or more radical polymerizable double bonds) can be used. It is. Since the radical polymerizable monomer is involved in photopolymerization, the viscosity of the photosensitive resin composition can be adjusted while improving the properties of the obtained cured product. When using a radical polymerizable monomer, the preferable usage-amount is 300 mass parts or less (more preferably 100 mass parts or less) with respect to 100 mass parts of total amounts of resin (A) of this invention and the said radical polymerizable resin. .

  Specific examples of the radical polymerizable monomer include aromatic vinyl monomers such as styrene, α-methylstyrene, α-chlorostyrene, vinyl toluene, divinylbenzene, diallyl phthalate, and diallylbenzene phosphonate; vinyl acetate, vinyl adipate, and the like. Vinyl ester monomer; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, β-hydroxyethyl (meth) acrylate, (2-oxo-1,3-dioxolan-4-yl) -methyl (meth) ) Acrylate, (di) ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tet (Meth) acrylic monomers such as (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tris [2- (meth) acryloyloxyethyl] triazine; 2- (vinyloxyethoxy) ethyl (meth) acrylate, ( 2- (isopropenoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxyethoxyethoxyethoxy) ethyl (meth) acrylate, etc. And a vinyl (thio) ether compound having a radical polymerizable double bond; a polyfunctional monomer having two or more radical polymerizable double bonds such as triallyl cyanurate. These are suitably selected according to the use and required characteristics of the photosensitive resin composition, and can be used alone or in combination of two or more.

  A photopolymerization initiator is also essential in the photosensitive resin composition of the present invention. This is because radical polymerization is initiated by light irradiation. The photosensitive resin composition of the present invention can be thermally cured by using a known thermal polymerization initiator. However, in order to perform microfabrication or image formation by photolithography, a photopolymerization initiator is added to light. It is preferable to cure.

  Known photopolymerization initiators can be used such as benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether and alkyl ethers thereof; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone. , Acetophenones such as 4- (1-t-butyldioxy-1-methylethyl) acetophenone; anthraquinones such as 2-methylanthraquinone, 2-amylanthraquinone, 2-t-butylanthraquinone, 1-chloroanthraquinone; 2,4 -Thioxanthones such as dimethylthioxanthone, 2,4-diisopropylthioxanthone and 2-chlorothioxanthone; Ketals such as acetophenone dimethyl ketal and benzyldimethyl ketal; Benzophenone, 4- (1- -Benzophenones such as butyldioxy-1-methylethyl) benzophenone and 3,3 ', 4,4'-tetrakis (t-butyldioxycarbonyl) benzophenone; 2-methyl-1- [4- (methylthio) phenyl]- Examples include 2-morpholino-propan-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1; acylphosphine oxides and xanthones.

  These photopolymerization initiators are used as one or a mixture of two or more, and are preferably contained in an amount of 0.5 to 30 parts by mass with respect to 100 parts by mass in total of the resin (A) and the radical polymerizable compound. . When the amount of the photopolymerization initiator is less than 0.5 parts by mass, it is necessary to increase the light irradiation time or it is difficult for polymerization to occur even if light irradiation is performed, so that an appropriate surface hardness can be obtained. Disappear. In addition, even if it mixes a photoinitiator exceeding 30 mass parts, there is no merit which uses it in large quantities.

  From the viewpoint of workability and the like when applying the photosensitive resin composition of the present invention to a substrate, a solvent may be blended in the composition. As the solvent, a solvent that can be used for oxidative polymerization can be used here, and one or a mixture of two or more can be used. An appropriate amount of the solvent may be used so that the composition has an optimum viscosity during the coating operation.

  You may mix | blend the compound which has 2 or more of functional groups which can react with a carboxyl group in the photosensitive resin composition of this invention in 1 molecule. This compound is a crosslinking agent that performs a crosslinking reaction on the carboxyl group in the resin (A). If this compound is blended, light and heat can be used in combination to cause a three-dimensional curing reaction, and a stronger cured coating film can be obtained. When used for image formation, heat treatment after light irradiation and alkali development can increase the degree of crosslinking while consuming carboxyl groups in the cured coating film, and can further improve physical properties such as durability.

  Examples of the compound include an epoxy compound, an oxazoline compound, and an oxetane compound. Specifically, examples of the epoxy compound include novolak type epoxy resin, bisphenol type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin, triglycidyl isocyanurate, etc., and examples of the oxazoline compound include 1,3-phenylenebisoxazoline. However, examples of the oxetane compound include 1,4-bis {3- (3-ethyloxetanyl) methoxy} benzene.

  The preferable usage-amount of the said compound is 5-70 mass parts with respect to a total of 100 mass parts of resin (A) and a radically polymerizable compound, and a more preferable usage-amount is 10-60 mass parts. At this time, a curing agent such as dicyandiamide or an imidazole compound may be used in combination.

  If necessary, the photosensitive resin composition of the present invention may further include a filler such as talc, clay, barium sulfate, a coloring pigment, an antifoaming agent, a coupling agent, a leveling agent, a sensitizer, and a release agent. Well-known additives such as lubricants, plasticizers, antioxidants, ultraviolet absorbers, flame retardants, polymerization inhibitors, thickeners, and the like may be added. Furthermore, various reinforcing fibers can be used as reinforcing fibers to form a fiber-reinforced composite material.

  When the photosensitive resin composition of the present invention is used for image formation, it is usually applied to a substrate by a known method, dried, exposed to obtain a cured coating film, and then an unexposed portion is treated with an alkaline aqueous solution. Then, alkali development is performed. Specific examples of alkalis that can be used for development include alkali metal compounds such as sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide; alkaline earth metal compounds such as calcium hydroxide; ammonia; monomethylamine and dimethylamine Water-soluble organic amines such as trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dimethylpropylamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, dimethylaminoethyl methacrylate, polyethyleneimine, These 1 type (s) or 2 or more types can be used.

  The photosensitive resin composition of the present invention can be used in the form of a dry film which is previously applied to a film of polyethylene terephthalate or the like and dried in addition to a method of directly applying a liquid resin to a substrate. In this case, a dry film may be laminated on a substrate, and the film may be peeled off before or after exposure.

  In addition, the CTP (Computer To Plate) system, which is frequently used in the printing plate making field, that is, without using a pattern forming film during exposure, laser light is directly scanned and exposed on the coating film using digitized data. The drawing method can be adopted.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the present invention are within the technical scope of the present invention. Is included. In the following description, “part” represents “part by mass” and “%” represents “% by mass” unless otherwise specified. Moreover, the measuring method of each physical property value in the following examples is as follows.

[Developability]
Irgacure 907 (Irgacure is a registered trademark; photopolymerization initiator manufactured by Ciba Specialty Chemicals Co., Ltd.), solid content of a mixture of a resin (A) solution and a radical polymerizable compound solution, or a radical polymerizable compound solution After adding 5% of the solid content of the single component (Comparative Example) to obtain a uniform solution, the solution was applied on a copper plate so that the film thickness after drying was 50 μm, and then heated at 80 ° C. for 30 minutes. Thereafter, the film was immersed in an aqueous 1% sodium carbonate solution at 30 ° C. to evaluate developability (alkali solubility). A sample in which the coating film was dissolved and removed within 60 seconds was marked with ◯, and a coating film remaining even after 60 seconds was marked with x.

[Photocurability]
The dried coating film obtained in the same manner as in the evaluation of developability was exposed to ² J / cm ² using an ultraviolet exposure device, and then immersed in a 1% aqueous sodium carbonate solution at 30 ° C. for 90 seconds. Photocurability was evaluated according to the degree of remaining. The case where there was no influence on the coating film was marked with ◯, and the case where the coating film was peeled off was marked with ×.

[Heat resistance: Glass transition temperature]
A functional group capable of reacting with a carboxyl group is contained in one molecule with respect to the solid content of the mixture of the resin (A) solution and the radical polymerizable compound solution or the solid content of the radical polymerizable compound solution alone (Comparative Example). 40% of cresol novolac type epoxy resin (trade name “EOCN-104S”; manufactured by Nippon Kayaku Co., Ltd .; epoxy equivalent 219) as a compound having two or more, 5% of Irgacure 907, and 2% of dicyandiamide as a curing agent To obtain a homogeneous solution. This was applied to a polyethylene terephthalate film so that the film thickness after drying was 100 μm, and then heated at 80 ° C. for 30 minutes. Next, after performing exposure at ² J / cm ² using an ultraviolet exposure device, it was further heated at 160 ° C. for 1 hour. After cooling to room temperature, the cured coating film was peeled from the polyethylene terephthalate film to obtain a test piece. As a measure of heat resistance, glass transition temperature (Tg; ° C.) was measured by TMA (using TMA-50 manufactured by Shimadzu Corporation). The sample for TMA measurement was a rectangle of about 20 mm in length, width, and about 5 mm. Tg was measured by tensile in the vertical direction while increasing the temperature from 23 ° C. to 200 ° C. at a temperature increase rate of 5 ° C./min. .

[Flexibility]
Using TMA measurement test piece and the test piece obtained in the same manner, room temperature (23 ° C.) below, with the mandrel of 10 mm [phi, we were evaluated bending resistance in accordance with 8.1 of JIS K 5400 ^-1990. The presence or absence of cracks was evaluated visually. The case where no crack was generated was marked with ◯, and the case where a crack occurred was marked with ×.

[Adhesion (dimensional stability)]
The dried coating film obtained in the same manner as in the evaluation of developability was exposed at ² J / cm ² using an ultraviolet exposure device, and then heated at 180 ° C. for 30 minutes as a high temperature condition. After cooling to room temperature, cellophane tape (manufactured by Nichiban Co., Ltd .; product number “CT-24”) is applied by hand so that it has an adhesive surface of about 20 mm square, and the coating film when it is peeled by hand again remains. The state was evaluated visually. The case where there was no effect on the coating film was indicated as ◯, the case where a part of the coating film was peeled off, and the case where the majority of the coating film was peeled off were indicated as x.

Synthesis example 1
[Synthesis of Resin B; 2,6-dimethylphenol / 2- (2-hydroxyethoxy) phenol = 50/50 (mol)]
In a vessel equipped with a stirrer, gas introduction tube, thermometer, and cooling tube, 1610 parts of nitrobenzene, 480 parts of pyridine, 6.7 parts of copper (I) chloride, 48.9 parts of 2,6-dimethylphenol, 2- (2 -Hydroxyethoxy) phenol 61.7 parts was added, and oxidative polymerization was carried out with stirring in an air atmosphere for 6 hours. After the polymerization, the resulting solution was diluted with 990 parts of chloroform and charged into a mixed solution of 24 parts of hydrochloric acid and 5800 parts of methanol. The precipitated resin B (referred to as B-1) was filtered off, and this resin B-1 was washed with 1300 parts of methanol, a mixed solution of 78 parts of hydrochloric acid and 1300 parts of methanol, and 1300 parts of methanol in this order. The washed resin B-1 was dissolved in 5000 parts of chloroform, and poured into a mixed solution of 24 parts of hydrochloric acid and 6300 parts of methanol to cause reprecipitation. Resin B-1 was filtered off, washed with methanol, and then dried at 110 ° C. under reduced pressure. The yield was 74.7 parts (yield 67.5%).

Synthesis example 2
[Synthesis of Resin A; Addition of Polybasic Acid Anhydride]
In a vessel equipped with a stirrer, thermometer, reflux condenser, and gas introduction tube, 50 parts of the above resin B-1, 28 parts of tetrahydrophthalic anhydride, 117 parts of propylene glycol monomethyl ether acetate, and benzyltriethylammonium as a catalyst 0.08 parts of chloride was charged and reacted at 110 ° C. for 5 hours in an air atmosphere to obtain a propylene glycol monomethyl ether acetate solution containing 40.0% of resin A (referred to as A-1) having an acid value of 136 mgKOH / g. It was.

Synthesis example 3
[Synthesis of radical polymerizable compounds; carboxyl group-containing epoxy acrylate]
In a container equipped with a stirrer, a thermometer, a reflux condenser, and a gas introduction tube, 414 parts of cresol novolac type epoxy resin (trade name “YDCN-703”; manufactured by Tohto Kasei; epoxy equivalent 207), 145 parts of acrylic acid, propylene 314 parts of glycol monomethyl ether acetate, 1.7 parts of benzyltriphenylphosphonium chloride as an esterification catalyst, 0.5 part of methyl hydroquinone as a polymerization inhibitor, and a mixed gas of nitrogen / air = 1/1 (vol.%) The reaction was performed at 120 ° C. for 20 hours in an atmosphere, and it was confirmed that the acid value of the reaction product was 2 mgKOH / g. Next, 109 parts of tetrahydrophthalic anhydride and 0.3 part of benzyltriethylammonium chloride as a catalyst were charged and reacted at 100 ° C. for 2 hours in a mixed gas atmosphere of nitrogen / air = 1/1 (vol.%). A propylene glycol monomethyl ether acetate solution containing 68.0% of a radically polymerizable compound of 63 mg KOH / g was obtained.

Example 1
10 parts of the resin A-1 solution and 8.7 parts of the radical polymerizable compound solution were mixed, and developability, photocurability, heat resistance, and flex resistance were evaluated by the methods described above. The developability was good, and the coating film was dissolved and removed by immersion for 60 seconds (evaluation ○). The photocurability was also good, and the coated film after exposure was not changed even after being immersed in an aqueous sodium carbonate solution for 90 seconds (evaluation ○). The glass transition temperature was 135 ° C., and no crack was observed in the flex resistance evaluation (evaluation ○). In addition, adhesion (dimensional stability) was also good (evaluation ○).

Comparative Example Using the solution of the radical polymerizable compound synthesized in Synthesis Example 3 (resin A-1 was not used), the developability, photocurability, thermal characteristics, and flex resistance were evaluated by the methods described above. The developability was good, and the coating film was dissolved and removed by immersion for 60 seconds (evaluation ○). The photocurability was also good, and the coated film after exposure was not changed even after being immersed in an aqueous sodium carbonate solution for 90 seconds (evaluation ○). Although the glass transition temperature was 130 ° C., in the bending resistance evaluation, cracks were generated, and it was confirmed that the bending resistance was inferior to the examples (Evaluation ×). In addition, adhesion (dimensional stability) was also x.

Synthesis example 4
[Synthesis of Resin B; 2,6-dimethylphenol / 2- (2-hydroxyethoxy) phenol = 40/60 (mol)]
According to the same formulation as in Synthesis Example 1, except that 39.1 parts of 2,6-dimethylphenol and 74 parts of 2- (2-hydroxyethoxy) phenol were used in Synthesis Example 1, resin B (B-2 and Obtained). The yield was 72.1 parts (yield 63.7%).

Synthesis example 5
[Synthesis of Resin A; Addition of polybasic acid anhydride and introduction reaction of radical polymerizable double bond]
Using the same apparatus as in Synthesis Example 2, 50 parts of the above resin B-2, 32.8 parts of tetrahydrophthalic anhydride, 131.8 parts of propylene glycol monomethyl ether acetate, 0.08 of benzyltriethylammonium chloride as a catalyst The reaction was carried out at 110 ° C. for 5 hours in an air atmosphere. Next, 5.1 parts of glycidyl methacrylate was added to the reaction apparatus for introducing a radical polymerizable double bond, and the reaction was further performed at 110 ° C. for 5 hours to obtain Resin A (represented as A-2 with an acid value of 119 mg KOH / g). ) To obtain a propylene glycol monomethyl ether acetate solution containing 40.0%.

Example 2
Ten parts of the resin A-2 solution and 8.7 parts of the radical polymerizable compound solution were mixed, and developability, photocurability, heat resistance, and flex resistance were evaluated by the methods described above. The developability was good, and the coating film was dissolved and removed by immersion for 60 seconds (evaluation ○). The photocurability was also good, and the coated film after exposure was not changed even after being immersed in an aqueous sodium carbonate solution for 90 seconds (evaluation ○). The glass transition temperature was 137 ° C., and no crack was observed in the evaluation of flex resistance (evaluation ○). In addition, adhesion (dimensional stability) was also good (evaluation ○).

  As described above, the photosensitive resin composition of the present invention has good developability and photocurability, and the cured coating film has flex resistance while maintaining a relatively high glass transition temperature. It became good. That is, by using the photosensitive resin composition of the present invention, it was possible to improve the heat resistance of the cured product and the conflicting properties of dimensional stability and reduced brittleness in a balanced manner.

  Therefore, the photosensitive resin composition of the present invention is an alkali-developable photosensitive resin composition for image formation, such as a solder resist for printed wiring boards, an etching resist, an electroless plating resist, and a build-up method printed wiring board. It can be suitably used for various applications such as an insulating layer, liquid crystal display plate production, and printing plate making.

Claims (6)

A photosensitive resin composition comprising a resin (A) having a structural unit (a) represented by the following formula, a radical polymerizable compound, and a photopolymerization initiator.

(In the formula, R ^{1 to} R ⁴ do not have radically polymerizable double bonds, and at least one is a carboxyl group or an organic group having a terminal carboxyl group and a carboxylate ester bond. And the others are the same or different and each represents hydrogen, an alkyl group, an alkoxy group, a hydroxyl group, a hydroxyalkyl group, a hydroxyalkoxy group, a hydroxyalkylthio group, or an aryl group. The photosensitive resin composition according to claim 1, wherein the resin (A) is obtained by a reaction between a resin (B) having a structural unit (b) represented by the following formula and a polybasic acid anhydride. object.

(Wherein R ^{5 to} R ⁸ do not have radically polymerizable double bonds and at least one is a hydroxyl group or represents an organic group having a hydroxyl group, and the other is the same or different. Represents hydrogen, an alkyl group, an alkoxy group, or an aryl group. The photosensitive resin composition according to claim 2, wherein at least one of the substituents R ^{5 to} R ⁸ of the structural unit (b) is a 2-hydroxyethoxy group and / or a 2-hydroxyethylthio group. The photosensitive resin composition according to claim 3, wherein the resin (B) is obtained by oxidative polymerization of a raw material mixture containing the following phenol compound (1).

(In the formula, at least one of R ^{5 to} R ⁸ is a 2-hydroxyethoxy group and / or 2-hydroxyethylthio group, and the other is the same or different, and represents a hydrogen, an alkyl group, an alkoxy group or an aryl group. To express.) The photosensitive resin composition according to claim 4, wherein the resin (B) is an oxidative copolymer obtained from the following phenol compound (2) and 2,6-dimethylphenol and / or cresol.

(In the formula, X represents O or S.) The photosensitive resin composition according to claim 1, wherein the resin (A) further has the following structural unit (c).

(In the formula, at least one of R ^{9 to} R ¹² is an organic group having a radical polymerizable double bond, and the other is the same or different and has hydrogen, an alkyl group, an alkoxy group, a carboxyl group, or a carboxyl group. An organic group, a hydroxyl group, a hydroxyalkyl group, a hydroxyalkoxy group, a hydroxyalkylthio group, or an aryl group is represented.)