WO2014208406A1 - Photocurable resin composition, cured product of same and printed wiring board - Google Patents

Abstract

The purpose of the present invention is to provide: a photocurable resin composition which is suppressed in the generation of an outgas; a cured product which is obtained by curing this photocurable resin composition; and a printed wiring board which is provided with this cured product. A photocurable resin composition which contains a carboxyl group-containing resin, a compound that has two or more ethylenically unsaturated groups in each molecule, and a photopolymerization initiator that is represented by general formula (I). (In the formula, R represents a structure represented by formula (II); l₁ represents an integer of 2-4; and m₁ represents an integer of 1 or more.)

Description

Photocurable resin composition, cured product thereof and printed wiring board

The present invention relates to a photocurable resin composition, a cured product thereof, and a printed wiring board including the same.

A photocurable composition containing a photopolymerization initiator as a component and cured by irradiating active energy rays such as ultraviolet rays has an advantage of being excellent in quick curing, so that a paint, a resin insulating layer, It is used in a wide range of fields such as solder resist and electrode forming paste (for example, Patent Documents 1 and 2).

The photocurable composition has a problem of so-called outgassing, in which components such as a photopolymerization initiator volatilize and gasify and contaminate the surroundings at the time of photocuring or subsequent thermal curing as necessary. There was a need for a solution. For example, Patent Document 3 discloses a photocurable resin composition containing an onium borate complex as a photocurable composition that generates less outgas.

Japanese Patent Laid-Open No. 2000-214584 JP 2001-075281 A JP 2005-336314 A

In recent years, reduction of outgas generation of a photocurable composition has been further demanded for the purpose of improving the performance of the photocurable composition and expanding applications.

Therefore, an object of the present invention is to provide a photocurable resin composition in which the generation of outgas is suppressed, a cured product obtained by curing the composition, and a printed wiring board including the same.

As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by using a specific photopolymerization initiator, and have completed the present invention.

That is, the photocurable resin composition of the present invention comprises a carboxyl group-containing resin, a compound having two or more ethylenically unsaturated groups in the molecule, and a photopolymerization initiator represented by the following general formula (I): , Containing.

(In the formula, R represents a structure represented by the following formula (II), l ₁ represents an integer of 2 to 4, and m ₁ represents an integer of 1 or more.)

The photocurable resin composition of the present invention preferably further contains a thermosetting component.

In the photocurable resin composition of the present invention, the thermosetting component is preferably an epoxy resin.

The photocurable resin composition of the present invention is preferably for resist formation.

The cured product of the present invention is obtained by curing the photocurable resin composition.

The printed wiring board of the present invention is characterized by comprising the cured product.

According to the present invention, it is possible to provide a photocurable resin composition in which outgas generation is suppressed, a cured product obtained by curing the composition, and a printed wiring board including the cured product.

6 is a chart showing a loss on heating curve obtained by simultaneous differential thermal-thermogravimetric measurement (TG / DTA measurement) of a photopolymerization initiator used in Reference Example. The horizontal axis represents temperature (Cel: Celsius temperature), and the vertical axis represents the reduction rate (%) of thermal weight.

Hereinafter, the photocurable resin composition of the present invention will be described in detail.

[Carboxyl group-containing resin]
The photocurable resin composition of the present invention contains a carboxyl group-containing resin. By containing a carboxyl group-containing resin, the photocurable resin composition can be made into a photocurable resin composition capable of alkali development. It does not specifically limit as carboxyl group-containing resin, The well-known carboxyl group-containing resin currently used in the photocurable resin composition for solder resists or interlayer insulation layers is employable.
Further, from the viewpoint of photocurability and development resistance, in addition to the carboxyl group, it is preferable to have an ethylenically unsaturated bond in the molecule, but a carboxyl group-containing resin that does not have an ethylenically unsaturated double bond. There may be. In order to make the composition photocurable when the carboxyl group-containing resin does not have an ethylenically unsaturated bond, a compound having two or more ethylenically unsaturated groups in the molecule (photoreactive monomer) Use together. As the ethylenically unsaturated double bond, those derived from acrylic acid, methacrylic acid or derivatives thereof are preferable.

As a carboxyl group-containing resin containing a carboxyl group in the molecule and having no ethylenically unsaturated bond in the molecule,
(1) Obtained by copolymerizing an unsaturated carboxylic acid such as acrylic acid or methacrylic acid with a compound having an unsaturated double bond such as styrene, α-methylstyrene, lower alkyl (meth) acrylate, or isobutylene. Carboxyl group-containing resin,
(2) An organic acid having one carboxyl group in one molecule and no ethylenically unsaturated bond in the epoxy group of the copolymer having an unsaturated double bond and glycidyl (meth) acrylate, For example, a carboxyl group-containing resin obtained by reacting an alkyl carboxylic acid having 2 to 17 carbon atoms, an aromatic group-containing alkyl carboxylic acid and the like, and reacting a saturated or unsaturated polybasic acid anhydride with the generated secondary hydroxyl group,
(3) Obtained by reacting a saturated or unsaturated polybasic acid anhydride with a hydroxyl group-containing polymer, such as an olefinic hydroxyl group-containing polymer, acrylic polyol, rubber polyol, polyvinyl acetal, styrene allyl alcohol resin, or cellulose. Carboxyl group-containing resin,
(4) Bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, brominated bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, biphenol type epoxy resin, bixylenol type epoxy resin, etc. A carboxyl group-containing resin obtained by reacting a reaction product of an epoxy compound with a dicarboxylic acid such as oxalic acid, malonic acid, succinic acid, phthalic acid, isophthalic acid, or the like, and a saturated or unsaturated polybasic acid anhydride; and ,
(5) Carboxy group-containing resins obtained by reacting a reaction product of a bifunctional epoxy compound with bisphenols such as bisphenol A and bisphenol F with a saturated or unsaturated polybasic acid anhydride.

Moreover, as a carboxyl group-containing photosensitive prepolymer having a carboxyl group in the molecule and an ethylenically unsaturated bond in the molecule,
(1) A polyfunctional epoxy compound having at least two epoxy groups in one molecule such as a novolak-type epoxy resin is reacted with an unsaturated monocarboxylic acid such as (meth) acrylic acid, and the resulting hydroxyl group is further mixed with hexa A carboxyl group-containing photosensitive prepolymer obtained by reacting a saturated or unsaturated polybasic acid anhydride such as hydrophthalic acid anhydride or tetrahydrophthalic acid anhydride,
(2) A polyfunctional epoxy compound having at least two epoxy groups in one molecule such as a novolak type epoxy resin, an unsaturated monocarboxylic acid such as (meth) acrylic acid, and an epoxy in one molecule such as nonylphenol A compound having one reactive group other than an alcoholic hydroxyl group that reacts with a group, more preferably an alcoholic group that reacts with at least one alcoholic hydroxyl group in one molecule such as p-hydroxyphenethyl alcohol and an epoxy group A carboxyl group obtained by reacting a compound having one reactive group other than a hydroxyl group and then reacting with a saturated or unsaturated polybasic acid anhydride such as hexahydrophthalic anhydride or tetrahydrophthalic anhydride. Containing photosensitive prepolymer,
(3) In part of the carboxyl group of a copolymer of an unsaturated carboxylic acid such as (meth) acrylic acid or maleic acid and a compound having an ethylenically unsaturated double bond such as methyl (meth) acrylate, glycidyl ( A carboxyl group-containing photosensitive prepolymer obtained by reacting a compound having one epoxy group and an ethylenically unsaturated double bond in one molecule such as (meth) acrylate,
(4) A copolymer of an unsaturated carboxylic acid such as (meth) acrylic acid or maleic acid and a compound having an ethylenically unsaturated double bond such as methyl (meth) acrylate, and 1 such as glycidyl (meth) acrylate Saturated or unsaturated polybasic acid anhydrides such as hexahydrophthalic acid anhydride and tetrahydrophthalic acid anhydride react with a compound having one epoxy group and ethylenically unsaturated double bond in the molecule and the resulting hydroxyl group A carboxyl group-containing photosensitive prepolymer obtained by reacting, and
(5) A copolymer of an unsaturated dibasic acid anhydride such as maleic anhydride and a compound having an ethylenically unsaturated double bond such as methyl (meth) acrylate is used as a copolymer such as 2-hydroxyethyl (meth) acrylate Examples thereof include a carboxyl group-containing photosensitive prepolymer obtained by reacting a hydroxyalkyl (meth) acrylate.

Further, when the polyfunctional epoxy resin used for the synthesis of the resin is a compound having a bisphenol A structure, a bisphenol F structure, a biphenol structure, a biphenol novolak structure, a bisxylenol structure, particularly a biphenyl novolak structure, and a hydrogenated compound thereof, The cured product of the photocurable resin composition to be obtained is preferable because it has low warpage and excellent bending resistance.

In addition, here, (meth) acrylate is a term that collectively refers to acrylate, methacrylate, and a mixture thereof, and the same applies to other similar expressions below.

The acid value of the carboxyl group-containing resin is preferably in the range of 20 to 200 mgKOH / g, more preferably in the range of 40 to 150 mgKOH / g. When the acid value of the carboxyl group-containing resin is 20 mgKOH / g or more, the adhesion of the coating film is good, and in the case of a photocurable resin composition, the alkali developability is excellent. In addition, when the acid value is 200 mgKOH / g or less, dissolution of the exposed portion by the developer is suppressed, the line does not fade more than necessary, and the developer is dissolved and peeled without distinction between the exposed portion and the unexposed portion. This makes it easy to draw a normal resist pattern.

The weight average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000. When the weight average molecular weight is 2,000 or more, the tack-free performance is excellent, the moisture resistance of the coated film after exposure is good, the film is not reduced during development, and the resolution is good. Further, when the weight average molecular weight is 150,000 or less, the developability is good and the storage stability is also excellent. More preferably, it is 5,000 to 100,000.

[Compound having two or more ethylenically unsaturated groups in the molecule]
The photocurable resin composition of the present invention contains a compound (photoreactive monomer) having two or more ethylenically unsaturated groups in the molecule. A compound having two or more ethylenically unsaturated groups in the molecule is photocured by irradiation with active energy rays to insolubilize or aid insolubilization of the carboxyl group-containing resin in an alkaline aqueous solution. The photoreactive monomer is also used as a diluent for the photocurable resin composition.

Examples of the compound used as the photoreactive monomer include conventionally known polyester (meth) acrylate, polyether (meth) acrylate, urethane (meth) acrylate, carbonate (meth) acrylate, epoxy (meth) acrylate, and the like. It is done. Specifically, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and 2-hydroxymethyl methacrylate; glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, propylene glycol and diethylene glycol Diacrylates; acrylamides such as N, N-dimethylacrylamide, N-methylolacrylamide, N, N-dimethylaminopropyl acrylamide; amino such as N, N-dimethylaminoethyl acrylate and N, N-dimethylaminopropyl acrylate Alkyl acrylates; hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, tris-hydroxyl Polyhydric alcohols such as ethyl isocyanurate or polyhydric acrylates such as these ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone adducts; phenoxy acrylate, bisphenol A diacrylate, and ethylene oxides of these phenols Polyvalent acrylates such as adducts or propylene oxide adducts; glycidyl ethers such as glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, triglycidyl isocyanurate; Directly acrylates polyols such as polyether polyol, polycarbonate diol, hydroxyl-terminated polybutadiene, and polyester polyol. Examples thereof include acrylates and melamine acrylates urethane-acrylated via diisocyanate, and / or methacrylates corresponding to the acrylates.

Furthermore, an epoxy acrylate resin obtained by reacting acrylic acid with a polyfunctional epoxy resin such as a cresol novolac type epoxy resin, and further a hydroxy acrylate such as pentaerythritol triacrylate and a diisocyanate such as isophorone diisocyanate on the hydroxyl group of the epoxy acrylate resin. An epoxy urethane acrylate compound or the like obtained by reacting a half urethane compound may be used as the photosensitive monomer. Such an epoxy acrylate resin can improve curability without reducing tackiness (touch-drying property).

In particular, in the present invention, polyhydric acrylates such as polyhydric alcohols or their ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone adducts, and polyphenols such as ethylene oxide adducts or propylene oxide adducts of phenols. Valent acrylates and further (meth) acrylate-containing urethane oligomers can be suitably used from the viewpoint of low warpage and bendability.

The photoreactive monomer may be used alone or in combination of two or more. The amount of the photoreactive monomer is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, and particularly preferably 5 to 15% by mass in the photocurable resin composition in terms of solid content. is there. When it is 30% by mass or less, the surface is not sticky and the dryness to the touch is good. Moreover, when it is 1 mass% or more, sufficient photocurability is obtained at the time of exposure, and pattern formability becomes good.

[Photopolymerization initiator]
Moreover, the photocurable resin composition of this invention contains the photoinitiator represented by the following general formula (I).

(In the formula, R represents a structure represented by the following formula (II), l ₁ represents an integer of 2 to 4, and m ₁ represents an integer of 1 or more.)

In the general formula (I), l ₁ is preferably 2 or 4, m ₁ is preferably 1 to 5, more preferably 1 to 3, and particularly preferably 1.

The photopolymerization initiator represented by the general formula (I) is preferably liquid at room temperature. Here, the liquid state at room temperature means that at any temperature of 10 to 40 ° C., when a sample is placed up to a height of 55 mm in a test tube with an inner diameter of 30 mm and the test tube is leveled, it is 90 until it passes through a portion 85 mm from the bottom. A state that is within seconds.

The photopolymerization initiator represented by the general formula (I) preferably has a 5% weight loss temperature of 260 ° C. or higher. Moreover, as an upper limit, 500 degrees C or less is preferable. In this specification, the 5% weight loss temperature is the temperature at which the thermogravimetric weight is reduced by 5% in the heating weight loss curve obtained by differential thermal-thermogravimetric simultaneous measurement (TG / DTA measurement) (measurement conditions: 10 ° C / min).

Examples of the photopolymerization initiator represented by the general formula (I) include polyethylene glycol (200) di (β-4- [4- (2-dimethylamino-2-benzyl) butanoylphenyl] piperazine) propionate. Etc.

The chemical formula of the specific example of the photoinitiator represented by the said general formula (I) is described. However, the present invention is not limited by the following compounds.

(In the formula, n represents an integer of 1 or more.)

Examples of commercially available photopolymerization initiators represented by the above general formula (I) include Omnipol 910, Omnipol 9210, Omnipol 9220 and the like manufactured by IHT.

The photopolymerization initiator represented by the general formula (I) may be used alone or in combination of two or more. The blending amount of the photopolymerization initiator represented by the general formula (I) is preferably 0.01 to 15% by mass, more preferably 0.1 to 15% by mass in the photocurable resin composition in terms of solid content. 15% by mass. When it is 15% by mass or less, the coating film formation is good. Moreover, when it is 0.01 mass% or more, sufficient photocurability will be obtained and pattern formation property will become favorable.

(Thermosetting component)
In order to impart heat resistance to the photocurable resin composition of the present invention, it is preferable to add a thermosetting component. As the thermosetting component used in the present invention, known and commonly used compounds such as blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, polyfunctional epoxy compounds, polyfunctional oxetane compounds, episulfide resins, etc. A thermosetting resin etc. are mentioned. Among these, a preferable thermosetting component is a thermosetting component having at least one of a plurality of cyclic ether groups and cyclic thioether groups (hereinafter abbreviated as cyclic (thio) ether groups) in one molecule. . There are many commercially available thermosetting components having a cyclic (thio) ether group, and various properties can be imparted depending on the structure.

Such a thermosetting component having a plurality of cyclic (thio) ether groups in the molecule includes either one of a three-, four- or five-membered cyclic ether group or a cyclic thioether group or two kinds of groups in the molecule. A compound having a plurality of epoxy groups in the molecule, i.e., a polyfunctional epoxy compound, a compound having a plurality of oxetanyl groups in the molecule, i.e., a polyfunctional oxetane compound, a plurality of compounds in the molecule Examples thereof include a compound having a thioether group, that is, an episulfide resin.

The polyfunctional epoxy compound is a polyfunctional epoxy compound having two or more epoxy groups (oxirane rings) in one molecule, or a resin obtained by polymerizing the polyfunctional epoxy compound. Examples of the polyfunctional epoxy compounds include epoxidized vegetable oils; bisphenol A type epoxy resins; hydroquinone type epoxy resins, bisphenol type epoxy resins, thioether type epoxy resins; brominated epoxy resins; novolac type epoxy resins; biphenol novolac type epoxy resins; F type epoxy resin; hydrogenated bisphenol A type epoxy resin; glycidylamine type epoxy resin; hydantoin type epoxy resin; alicyclic epoxy resin; trihydroxyphenylmethane type epoxy resin; bixylenol type or biphenol type epoxy resin or a mixture thereof Bisphenol S type epoxy resin; bisphenol A novolac type epoxy resin; tetraphenylol ethane type epoxy resin; heterocyclic epoxy resin; Ruphthalate resin; Tetraglycidylxylenoylethane resin; Naphthalene group-containing epoxy resin; Epoxy resin having dicyclopentadiene skeleton; Glycidyl methacrylate copolymer epoxy resin; Copolymer epoxy resin of cyclohexylmaleimide and glycidyl methacrylate; Examples thereof include, but are not limited to, polybutadiene rubber derivatives and CTBN-modified epoxy resins. These epoxy resins can be used alone or in combination of two or more. Among these, bisphenol type epoxy resins are particularly preferable.

Examples of the polyfunctional oxetane compound include bis [(3-methyl-3-oxetanylmethoxy) methyl] ether, bis [(3-ethyl-3-oxetanylmethoxy) methyl] ether, 1,4-bis [(3-methyl -3-Oxetanylmethoxy) methyl] benzene, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, (3-methyl-3-oxetanyl) methyl acrylate, (3-ethyl-3-oxetanyl) In addition to polyfunctional oxetanes such as methyl acrylate, (3-methyl-3-oxetanyl) methyl methacrylate, (3-ethyl-3-oxetanyl) methyl methacrylate and oligomers or copolymers thereof, oxetane alcohol and novolak resin, Poly (p-hydroxystyrene), cardo type bisph Nord acids, calixarenes, calix resorcin arenes or etherified products such as the resin having a hydroxyl group such as silsesquioxane and the like. In addition, a copolymer of an unsaturated monomer having an oxetane ring and an alkyl (meth) acrylate is also included.

Examples of the episulfide resin having a plurality of cyclic thioether groups in the molecule include YL7000 (bisphenol A type episulfide resin) manufactured by Mitsubishi Chemical Corporation and YSLV-120TE manufactured by Tohto Kasei Co., Ltd. Moreover, episulfide resin etc. which substituted the oxygen atom of the epoxy group of the novolak-type epoxy resin by the sulfur atom using the same synthesis method can also be used.

In addition, the photocurable resin composition of the present invention can use a thermosetting component such as an amino resin such as a melamine derivative or a benzoguanamine derivative, in addition to the above thermosetting component. Examples of such thermosetting components include methylol melamine compounds, methylol benzoguanamine compounds, methylol glycoluril compounds, methylol urea compounds, alkoxymethylated melamine compounds, alkoxymethylated benzoguanamine compounds, alkoxymethylated glycoluril compounds, alkoxymethylated compounds. A urea compound etc. are mentioned. The type of the alkoxymethyl group is not particularly limited, and for example, it can be a methoxymethyl group, an ethoxymethyl group, a propoxymethyl group, a butoxymethyl group, or the like. In particular, a melamine derivative having a formalin concentration which is friendly to the human body and the environment is preferably 0.2% or less. The said thermosetting component may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, when using as a soldering resist, it is preferable to mix | blend the said thermosetting component.

(Other ingredients)
The photocurable resin composition of the present invention may be blended with known additives other than the above components as long as the effects of the present invention are not impaired. Additives include thermal polymerization inhibitors, UV absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, anti-aging agents, antibacterial / antifungal agents, antifoaming agents, leveling agents, fillers, thickeners , Adhesion imparting agent, thixotropic property imparting agent, colorant, photopolymerization initiator other than the above, photoinitiator assistant, sensitizer and the like. A solvent may be used in the case of photocuring after applying and drying on the surface of the base material like a solder resist.

(Other photopolymerization initiators)
The photocurable resin composition of the present invention may contain a photopolymerization initiator other than the above photopolymerization initiator. Examples of other photopolymerization initiators include oxime ester photopolymerization initiators, alkylphenone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, and titanocene photopolymerization initiators.

Examples of commercially available oxime ester photopolymerization initiators include CGI-325, Irgacure OXE01, Irgacure OXE02 manufactured by BASF Japan, and N-1919 manufactured by ADEKA.

In addition, a photopolymerization initiator having two oxime ester groups in the molecule can also be suitably used. Specific examples include oxime ester compounds having a carbazole structure represented by the following general formula (2). .

(In the formula, X is a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a phenyl group, a phenyl group (an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms). Group, an amino group, an alkylamino group having an alkyl group having 1 to 8 carbon atoms or a dialkylamino group), a naphthyl group (an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms), And Y and Z are each a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, or a carbon number of 1), and is substituted by an alkylamino group having a C 1-8 alkyl group or a dialkylamino group. Alkoxy group having 8 to 8 alkoxy group, halogen group, phenyl group, phenyl group (alkyl group having 1 to 17 carbon atoms, alkoxy group having 1 to 8 carbon atoms, amino group, alkyl group having 1 to 8 carbon atoms) Alkyl groups having 1 to 17 carbon atoms, alkoxy groups having 1 to 8 carbon atoms, amino groups, alkyl groups having 1 to 8 carbon atoms, substituted with a mino group or a dialkylamino group Or substituted with a dialkylamino group), anthryl group, pyridyl group, benzofuryl group, benzothienyl group, Ar is alkylene having 1 to 10 carbon atoms, vinylene, phenylene, biphenylene, pyridylene, naphthylene, thiophene, anthrylene , Thienylene, furylene, 2,5-pyrrole-diyl, 4,4′-stilbene-diyl, 4,2′-styrene-diyl, and n is an integer of 0 or 1)

In particular, the oxime ester system in which X and Y are each a methyl group or an ethyl group, Z is methyl or phenyl, n is 0, and Ar is phenylene, naphthylene, thiophene or thienylene in the above formula Photoinitiators are preferred.

The oxime ester photopolymerization initiator may be used alone or in combination of two or more. When the oxime ester-based photopolymerization initiator is used, the amount is preferably 0.1 to 25% by mass, more preferably 5 to 15% by mass in the photocurable resin composition in terms of solid content. . When it is 25% by mass or less, the coating film formation is good. Moreover, when it is 0.1 mass% or more, sufficient photocurability will be obtained and pattern formation property will become favorable.

Examples of the alkylphenone photopolymerization initiator include benzyldimethyl ketal photopolymerization initiators such as 2,2-dimethoxy-1,2-diphenylethane-1-one; 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy -2-Methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy- Α-hydroxyalkylphenone photopolymerization initiators such as 1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one; 2-methyl -1- [4- (methylthio) phenyl] -2-morpholinopropanone-1,2-benzyl-2-dimethylamino-1- (4-morpholino Enyl) -butan-1-one, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, N, N-dimethyl And α-aminoacetophenone photopolymerization initiators such as aminoacetophenone. Examples of commercially available benzyldimethyl ketal photopolymerization initiators include Irgacure 651 manufactured by BASF Japan. Examples of commercially available α-hydroxyalkylphenone photopolymerization initiators include Irgacure 184, Darocur 1173, Irgacure 2959, and Irgacure 127 manufactured by BASF Japan. Examples of commercially available α-aminoacetophenone photopolymerization initiators include Irgacure 907, Irgacure 369, and Irgacure 379 manufactured by BASF Japan.

Acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2 4,4-trimethyl-pentylphosphine oxide and the like. Examples of commercially available products include Lucilin TPO, Irgacure 819 manufactured by BASF Japan.

Titanocene photopolymerization initiators include bis (cyclopentadienyl) -di-phenyl-titanium, bis (cyclopentadienyl) -di-chloro-titanium, bis (cyclopentadienyl) -bis (2,3 4,5,6 pentafluorophenyl) titanium, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyrrol-1-yl) phenyl) titanium, and the like. Examples of commercially available products include Irgacure 784 manufactured by BASF Japan.

Each of the alkylphenone photopolymerization initiator, acylphosphine oxide photopolymerization initiator, and titanocene photopolymerization initiator may be used alone or in combination of two or more. The amount of each photopolymerization initiator used is preferably 2 to 25% by mass, more preferably 5 to 15% by mass in the photocurable resin composition in terms of solid content. When it is 25% by mass or less, the coating film formation is good. Moreover, when it is 2 mass% or more, sufficient photocurability will be obtained and pattern formation property will become favorable.

(Filler)
The photocurable resin composition of the present invention may contain a filler (inorganic filler). The filler is used for suppressing the curing shrinkage of the cured product of the photocurable resin composition and improving properties such as adhesion and hardness. Examples of fillers include barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, boron nitride, and Neuburg Sisius Earth. Etc.

The average particle diameter (D50) of the filler is preferably 1 μm or less, more preferably 0.7 μm or less, and even more preferably 0.5 μm or less. When the average particle diameter exceeds 1 μm, the photocurable resin composition may become cloudy, which is not preferable depending on the application. The average particle diameter (D50) can be measured by a laser diffraction / scattering method. When the average particle size is in the above range, the refractive index is close to that of the resin component, and the transparency is improved.

(solvent)
The photocurable resin composition of the present invention may contain an organic solvent in order to adjust the viscosity of the composition. Any known organic solvent can be used as long as it can dissolve the photopolymerization initiator according to the present invention. For example, toluene, xylene, ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, isobutyl alcohol, 1-butanol, diacetone alcohol, ethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, terpineol, methyl ethyl ketone Carbitol, carbitol acetate, butyl carbitol, butyl carbitol acetate and the like. A solvent may be used individually by 1 type and may be used in combination of 2 or more type.

The photocurable resin composition of the present invention is cured by, for example, irradiating with ultraviolet rays, preferably with a wavelength of 10 to 400 nm, more preferably with a wavelength of 250 to 400 nm, after coating on a substrate or the like by the following coating method. be able to.

Examples of the ultraviolet light source include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, xenon lamps or metal halide lamps, lasers, and UV-LEDs.

As the coating method, any method such as a dip coating method, a flow coating method, a roll coating method, a bar coater method, a screen printing method, a curtain coating method, a gravure printing method, and an offset printing method can be applied.

The photocurable resin composition of the present invention is preferably for a solder resist. The solder resist is formed by applying and curing the photo-curable resin composition of the present invention on a substrate.
Any known method can be employed for applying and curing the photocurable resin composition for the solder resist. For example, the following method can be used.
If necessary, it is diluted with a solvent and adjusted to a viscosity suitable for the coating method, and this is applied to a printed wiring board formed with a circuit by a method such as a screen printing method, a curtain coating method, a spray coating method, or a roll coating method. A tack-free coating film can be formed by coating and evaporating and drying an organic solvent contained in the composition at a temperature of about 60 to 100 ° C., for example. Thereafter, active energy rays such as laser light are directly irradiated according to a pattern, or selectively exposed to ultraviolet rays through a photomask having a pattern and cured. When the photocurable resin composition is an alkali development type, a resist pattern can be formed by developing an unexposed portion with a dilute alkaline aqueous solution. Furthermore, if desired, a cured film (cured product) is formed by heat curing after ultraviolet irradiation or final curing (main curing).

The photo-curable resin composition of the present invention can be suitably used for forming resists such as solder resists, etching resists and plating resists. Moreover, it can be used for applications such as an interlayer insulating layer of a printed wiring board, a conductive paste for electrode formation in a plasma display panel and a touch panel. Further, the photocurable resin composition of the present invention is a coating layer formed by applying and drying a photocurable resin composition on a film such as a polyethylene terephthalate film in advance, in addition to a method of directly applying to a substrate in a liquid state. It can also be used in the form of a dry film having

The photo-curable resin composition of the present invention is suitable as a permanent film for a printed wiring board, and particularly suitable as a solder resist or an interlayer insulating material.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples. Unless otherwise specified, “part” means mass part, and “%” means mass%.

[Reference example]
(Measurement of 5% weight loss temperature of photopolymerization initiator)
Using a differential thermal-thermogravimetric simultaneous measurement device (TG / DTA) with a 5% weight loss temperature of Omnipol 910 manufactured by IHT, the weight loss during temperature rise was measured at a constant speed under the following conditions. The temperature when the percentage decreased was obtained. The obtained heating loss curve is shown in FIG. The 5% weight loss temperature was 318 ° C.
Measurement sample: photopolymerization initiator (10 mg of the sample is weighed in a sample pan).
Measuring instrument: TG / DTA6200 manufactured by Hitachi High-Tech Science Corporation.
Measurement range: 30 ° C to 600 ° C.
Temperature increase rate: 10 ° C./min.

(Synthesis or preparation of carboxyl group-containing resin)
[A-1: Synthesis of carboxyl group-containing resin]
An ortho cresol novolak type epoxy resin (Epiclon N-695, manufactured by DIC, softening point 95 ° C., epoxy equivalent 214, average functional group number 7.6) 1070 g (number of glycidyl groups (total number of aromatic rings)): 600 g of diethylene glycol monoethyl ether acetate 5.0 mol), 360 g (5.0 mol) of acrylic acid, and 1.5 g of hydroquinone were charged, heated and stirred at 100 ° C., and dissolved until uniform. Next, 4.3 g of triphenylphosphine was charged into the above solution and heated to 110 ° C. to react for 2 hours. Then, it heated up at 120 degreeC and reacted for 12 hours. To the obtained reaction solution, 415 g of aromatic hydrocarbon (Sorvesso 150) and 456.0 g (3.0 mol) of tetrahydrophthalic anhydride were added and reacted at 110 ° C. for 4 hours. After cooling, the solid content acid value 89 mgKOH / G, a carboxyl group-containing resin solution having a solid content of 65% was obtained. The obtained resin solution is hereinafter referred to as A-1.

[A-2: Preparation of carboxyl group-containing resin]
Cyclomer P (ACA) Z250 (solid content 45%, acid value 70.0 mgKOH / g) manufactured by Daicel Chemical Industries, Ltd. was used. The resin solution is hereinafter referred to as A-2.

[Examples 1 to 3 and Comparative Examples 1 and 2]
(Preparation of photocurable resin composition)
Each component shown in the following Table 1 was kneaded by a three-roll mill to prepare a photocurable resin composition. The unit of the blending amount in the table is part by mass. In addition, as said photoinitiator represented by the said general formula (I), said Chemical formula No.1. 1 photoinitiator was used.
The following evaluation was performed about the obtained photocurable resin composition. The evaluation results are shown in Table 2 below.

<Photopolymerization initiator properties>
Whether the photopolymerization initiator is liquid or powder at room temperature was visually confirmed.

<Solder heat resistance>
A rosin flux was applied to the test substrate and immersed in a solder bath set at 260 ° C. for 30 seconds.
After the test substrate was washed with an organic solvent, a peeling test using a cellophane adhesive tape was performed, and the following criteria were evaluated.
○: No change is observed at all.
X: The thing by which the float of a cured coating film is recognized.

<Pencil hardness>
The cured coating film was tested according to the test method of JIS C 5400, and the highest hardness without damaging the coating film was observed.

<Sensitivity>
The photocurable resin compositions of Examples and Comparative Examples were applied on the entire surface of a copper solid substrate by screen printing and dried at 80 ° C. for 20 minutes. Next, the substrate is exposed to 400 mJ / cm ² with a metal halide lamp through a step tablet (Kodak No. 2), and then developed with a 1 wt% Na ₂ CO ₃ aqueous solution with a spray pressure of 0.2 MPa. Sensitivity was used.

<Outgas>
The photocurable compositions of Examples and Comparative Examples were applied on the entire surface of a patterned copper foil substrate by screen printing and dried at 80 ° C. for 20 minutes. Next, this substrate was exposed through a photomask using an exposure apparatus equipped with a metal halide lamp, and developed with a 1 mass% Na ₂ CO ₃ aqueous solution with a spray pressure of 0.2 MPa at 30 ° C. to form a resist pattern. Next, a part of the substrate was heated at 150 ° C. for 60 minutes for additional processing, and a thermosetting substrate was also produced. A powder sample was collected from the produced resist in a heat desorption device (TDU) manufactured by GUSTER. Thereafter, outgas components were collected at −60 ° C. using liquid nitrogen for 10 minutes at a heat extraction temperature of 150 ° C. The collected outgas component was subjected to separation analysis using a gas chromatography mass spectrometer (6890N / 5973N) manufactured by Agilent Technologies, quantified in terms of n-dodecane, and evaluated according to the following criteria.
○: There is almost no outgas component.
Δ: Some outgas components were confirmed.
X: There are many outgas components.

* 1: Carboxyl group-containing resin solution A-1 obtained above: Orthocresol novolac epoxy resin (CN) / acrylic acid (AA) / tetrahydrophthalic anhydride (THPAn) (The amount in the table indicates the solid content) )
* 2: Carboxyl group-containing resin solution A-2 (cyclomer P (ACA) Z250) obtained above; copolymer resin (the amount in the table indicates the solid content)
* 3: OMNIPOL 910 (manufactured by IHT); polyethylene glycol (200) di (β-4- [4- (2-dimethylamino-2-benzyl) butanoylphenyl] piperazine) propionate * 4: Irgacure 907 (BASF Japan) 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one * 5: Lucillin TPO-L (manufactured by BASF Japan); ethyl-2,4,6-trimethylbenzoyl Phenyl phosphinate
* 6: DPHA (manufactured by Nippon Kayaku Co., Ltd.); dipentaerythritol hexaacrylate * 7: TMPTA (manufactured by Nippon Kayaku Co., Ltd.); trimethylolpropane triacrylate * 8: B-30 (manufactured by Sakai Chemical Industry Co., Ltd.); barium sulfate * 9: KS-66 (manufactured by Shin-Etsu Silicone); polydimethylsiloxane * 10: jER828 (manufactured by Mitsubishi Chemical); bisphenol A type epoxy resin

From the results shown in Table 1, it can be seen that the photocurable resin compositions of Examples containing the photopolymerization initiator represented by the general formula (I) are excellent in suppressing outgas generation.

Claims (6)

1. Carboxyl group-containing resin,
   A compound having two or more ethylenically unsaturated groups in the molecule,
   and,
   A photopolymerization initiator represented by the following general formula (I):
   The photocurable resin composition characterized by containing.
   

   

   (In the formula, R represents a structure represented by the following formula (II), l ₁ represents an integer of 2 to 4, and m ₁ represents an integer of 1 or more.)
   

   
2. The photocurable resin composition according to claim 1, further comprising a thermosetting component.
3. 3. The photocurable resin composition according to claim 2, wherein the thermosetting component is an epoxy resin.
4. The photocurable resin composition according to claim 1, wherein the photocurable resin composition is for resist formation.
5. A cured product obtained by curing the photocurable resin composition according to any one of claims 1 to 4.
6. A printed wiring board comprising the cured product according to claim 5.

Images