JP2011138037A - Curable resin composition and printed wiring board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable resin composition for forming a solder resist film having flexibility and low warping properties, while preventing reduction in reflectance with the lapse of time and by heat history. <P>SOLUTION: The curable resin composition comprises (A-1) a copolymer resin obtained by reacting a compound of general formula (I) with a compound of general formula (II) and/or a compound of general formula (III) or (A-2) a copolymer resin obtained by adding a compound having an oxirane ring and an ethylenically unsaturated bond to part of carboxyl groups in a copolymer obtained by reacting a compound of general formula (I) with a compound of general formula (II) and/or a compound of general formula (III), (B) a curing agent, and (C) a diluent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a curable composition suitable for a solder resist or various resists of a printed wiring board, and a printed wiring board coated with a cured product obtained by curing the curable composition.

  A printed wiring board is used to form a pattern of a conductor circuit on a substrate and to mount electronic components on the soldering land of the pattern by soldering, and the circuit portion excluding the soldering land is used as a permanent protective film. It is covered with a solder resist film. This prevents solder from adhering to unnecessary parts when soldering electronic components to a printed wiring board, and prevents circuit conductors from being directly exposed to air and being corroded by oxidation or humidity. To do.

  Therefore, Patent Document 1 discloses a photosensitive resin composition useful as a one-part liquid photoresist that can be developed with a dilute alkaline aqueous solution that is excellent in stability, heat resistance, and chemical resistance.

  The printed wiring board is also used as a mounting substrate for light emitting diode elements (LEDs) and the like, and the solder resist film formed on the mounting surface is required to have a function of improving the reflectance of light from the light source. . In such applications, white solder resist is mainly used as the solder resist composition for forming the solder resist film.

  However, in the case of a white solder resist, when the coating film is heated and cured, discoloration may occur and coloring may occur, resulting in a decrease in light reflectance. In particular, in the case of a white solder resist, since the discoloration and the decrease in the reflectance are conspicuous, the commercial value has been reduced. Therefore, Patent Document 2 proposes a solder resist composition that can suppress discoloration and a decrease in reflectance.

  In recent years, solder resists have been used for flexible wiring boards having a soft structure due to the progress of downsizing of electronic devices and complication of internal structures. In this case, in order to give a flexible structure to the flexible wiring board, the solder resist composition not only suppresses a decrease in reflectance, but also requires flexibility and low warpage. Therefore, it was necessary to further improve the above characteristics.

JP-A-3-172301 JP2007-322546A

  In view of the above circumstances, an object of the present invention is to provide a curable resin composition capable of forming a solder resist film having flexibility, low warpage, and flame retardancy while preventing a decrease in reflectance and yellowing due to aging and thermal history. The purpose is to provide goods.

  In a first aspect of the present invention, (A-1) the general formula (I)

(Wherein R ¹ represents a hydrogen atom or a methyl group), and a general formula (II)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. A group, an adamantyl group or a trifluoromethyl group, and m is an integer of 0 or 1-3) and / or the general formula (III)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. Group, an adamantyl group or a trifluoromethyl group, A ¹ represents a C 2-10 alkylene group or a C 3-10 hydroxyalkylene group containing a linear or cyclic skeleton, and m is 0 or 1-3. An integer, p is an integer of 1 to 5), or a copolymer resin obtained by reacting the compound represented by (A-2) general formula (I)

(Wherein R ¹ represents a hydrogen atom or a methyl group), and a general formula (II)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. A group, an adamantyl group or a trifluoromethyl group, and m is an integer of 0 or 1-3) and / or the general formula (III)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. Group, an adamantyl group or a trifluoromethyl group, A ¹ represents a C 2-10 alkylene group or a C 3-10 hydroxyalkylene group containing a linear or cyclic skeleton, and m is 0 or 1-3. An integer, p is an integer of 1 to 5), and a copolymer obtained by adding a compound having an oxirane ring and an ethylenically unsaturated bond to a part of the carboxyl group of the copolymer obtained by reacting the compound represented by A curable resin composition comprising a polymer resin, (B) a curing agent, and (C) a diluent.

  That is, the copolymer resin of (A-1) is represented by the compound represented by the general formula (I), the compound represented by the general formula (II), and / or the general formula (III). And a carboxyl group-containing copolymer resin having an aromatic ring. The copolymer resin (A-2) is an aromatic ring-containing carboxyl obtained by adding a compound having an oxirane ring and an ethylenically unsaturated bond to the copolymer (A-1). It is a group-containing copolymer resin.

  In a second aspect of the present invention, the compound having an oxirane ring and an ethylenically unsaturated bond is represented by the general formula (IV):

(Wherein R ¹ represents a hydrogen atom or a methyl group, A ² represents an alkylene group having 2 to 10 carbon atoms, and q is 0 or an integer of 1 to 5). The curable resin composition is characterized.

  According to a third aspect of the present invention, the (A-1) copolymer resin and the (A-2) copolymer resin have an aromatic hydrocarbon skeleton of 5 to 40% by mass. It is a resin composition. That is, (A-1) copolymer resin and (A-2) copolymer resin each contain 5 to 40% by mass of an aromatic hydrocarbon skeleton. According to a fourth aspect of the present invention, there is provided a curable resin composition wherein the acid value of the (A-1) copolymer resin and the acid value of the (A-2) copolymer resin are 30 to 150 mgKOH / g. It is a thing.

  The fifth aspect of the present invention is a curable resin composition characterized by further containing (D) an inorganic white pigment, and the sixth aspect of the present invention is the above-mentioned (D) inorganic white pigment. A curable resin composition characterized by being rutile titanium oxide.

  The seventh aspect of the present invention is characterized in that the (B) curing agent contains at least one selected from the group consisting of a compound having two or more epoxy groups in one molecule, melamine and a melamine derivative. Curable resin composition, 8th aspect of this invention WHEREIN: The said (C) diluent contains the compound which has one or more ethylenically unsaturated groups in 1 molecule, The curable resin composition characterized by the above-mentioned. The ninth aspect of the present invention is characterized in that the diluent (C) is a compound having two or more (meth) acrylic groups and having a (meth) acrylic equivalent of 200 g / eq or more. It is a curable resin composition.

  A tenth aspect of the present invention further includes (E) a curable resin composition comprising a photopolymerization initiator, and an eleventh aspect of the present invention further comprises (F) a phosphorus-based flame retardant A curable resin composition characterized by containing the curable resin composition, wherein the twelfth aspect of the present invention further comprises (G) a metal hydroxide, and the thirteenth aspect of the present invention. An aspect is a printed wiring board coated with a solder resist film formed using the curable resin composition.

  According to the first and second aspects of the present invention, (meth) acrylic acid is a constituent element of the copolymer, and the carboxyl group of the copolymer resin is specified as a structure derived from (meth) acrylic acid. Discoloration of the coating film, particularly discoloration of the cured coating film mainly due to heat when forming a cured coating film on the copper wiring can be suppressed. Further, as shown in the general formula (II) and the general formula (III), a compound having no hydrogen atom at the side chain α-position of the aromatic hydrocarbon skeleton is a constituent element of the copolymer resin after polymerization. That is, a compound having no hydrogen atom at the α-position of the side chain relative to the aromatic hydrocarbon skeleton or a compound in which a hydrogen atom at the α-position relative to the aromatic hydrocarbon skeleton is present in the main chain Therefore, discoloration of the cured coating film can be suppressed.

  According to the 3rd aspect of this invention, since (A-1) copolymer resin and (A-2) copolymer resin have 5-40 mass% aromatic-hydrocarbon frame | skeleton, it is heat resistant. It has excellent flame retardancy and compatibility with (C) diluent, etc., so that it has excellent alkali developability when used as an alkali development type photosensitive solder resist, and also has good photocurability. Since the coating film is excellent in flexibility due to its thermosetting property, workability at the time of manufacturing a wiring board is improved.

  From the above characteristics, in the present invention, since it is excellent in alkali developability and can form a solder resist film having flexibility, low warpage, and flame retardancy, not only printed wiring boards such as copper-clad laminates, etc. It can also be used for flexible wiring boards that require flexibility. Also, by blending inorganic white pigments such as rutile type titanium oxide, it is possible to prevent the decrease in reflectance and discoloration from white to yellow due to the aging and thermal history of the solder resist film, so the wiring board on which the light emitting diode element is mounted The illuminance can be further improved.

  Next, the curable resin composition of the present invention will be described. The curable resin composition of the present invention comprises (A-1) a compound represented by the above general formula (I), a compound represented by the above general formula (II) and / or the above general formula (III). A copolymer resin obtained by reacting the compound represented by formula (I), or (A-2) a compound represented by formula (I), a compound represented by formula (II) and / or the formula A copolymer resin obtained by adding a compound having an oxirane ring and an ethylenically unsaturated bond to a part of the carboxyl group of the copolymer obtained by reacting the compound represented by (III), (B) a curing agent, And (C) a curable resin composition comprising a diluent.

(A-1), (A-2): The copolymer resin of the copolymer resin (A-1) is represented by the acrylic acid or methacrylic acid represented by the general formula (I) and the general formula (II). And an ethylenically unsaturated monomer having an aromatic ring and / or (meth) acrylate having an aromatic ring represented by the general formula (III). The copolymer resin (A-2) is a copolymer of the copolymer (A-1) obtained by copolymerizing the general formula (I) with the general formula (II) and / or the general formula (III). It is obtained by adding a compound having an oxirane ring and an ethylenically unsaturated bond to a part of the carboxyl group.

  Examples of the ethylenically unsaturated monomer having an aromatic ring represented by the general formula (II) include styrene, α-methylstyrene, p-methoxystyrene, mt-butoxystyrene, pt-butoxystyrene, and p- (1 -Ethoxyethoxy) styrene, p-fluorostyrene and the like. These compounds may be used alone or in combination of two or more.

  Examples of the (meth) acrylate having an aromatic ring represented by the general formula (III) include phenoxy polyethylene glycol (meth) such as phenoxyethyl (meth) acrylate and 2- (2-phenoxyethoxy) ethyl (meth) acrylate. Phenoxypolypropylene glycol (meth) acrylate such as acrylate, phenoxypropyl (meth) acrylate and 2-phenoxypropyl (meth) acrylate, phenylglycidyl ether (meth) acrylate, 4-α-cumylphenoxyethyl (meth) acrylate and other 4- α-cumylphenoxypolyethylene glycol (meth) acrylate and 2-phenylphenoxypolyethylene glycol (meth) acrylate such as 2-phenylphenoxyethyl (meth) acrylate Can be mentioned. These compounds may be used alone or in combination of two or more.

  In addition, in order to obtain the copolymer resin of (A-1) and (A-2), it is represented by the ethylenically unsaturated monomer having an aromatic ring represented by the general formula (II) or the general formula (III). Any one of (meth) acrylates having an aromatic ring may be used, or both may be mixed and used.

  The compound having an oxirane ring and an ethylenically unsaturated bond is not particularly limited as long as it is a compound having an oxirane ring and an ethylenically unsaturated bond, and examples thereof include compounds represented by the above general formula (IV), More specifically, glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, hydroxyalkyl (meth) acrylate glycidyl ether, β-methylglycidyl (meth) acrylate, (3,4-epoxycyclohexyl) methyl Examples thereof include epoxy cyclohexyl derivatives of (meth) acrylic acid such as (meth) acrylate, alicyclic epoxy derivatives of (meth) acrylate, and the like. These compounds may be used alone or in combination of two or more.

  In addition, if necessary, an ethylenically unsaturated monomer having an aromatic ring represented by the general formula (II), a (meth) acrylate having an aromatic ring represented by the general formula (III), and an aromatic ring also having a carboxyl group In addition, an ethylenically unsaturated monomer that does not have the above may be added and copolymerized with acrylic acid or methacrylic acid represented by the general formula (I). Examples of ethylenically unsaturated monomers having neither an aromatic ring nor a carboxyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl acrylate, and n-butyl (meth). Acrylate, i-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, di Cyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate and 2-ethyl-2-adamantyl ( Meta) Acu Alkyl (meth) acrylates having a straight chain, branched or alicyclic skeleton such as rate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Hydroxy mono (meth) acrylates such as (meth) acrylate, 4-hydroxybutyl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate and nonanediol mono (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, cyclic trimethylol Cyclic ether skeleton-containing (meth) acrylates such as propane formal (meth) acrylate and alkoxylated tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate cap Lactone adducts and hydroxymono (meth) acrylate / caprolactone adducts such as 2-hydroxypropyl (meth) acrylate / caprolactone adducts, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polypropylene glycol mono (meta) ) Acrylate, poly (ethylene glycol / propylene glycol) mono (meth) acrylate, poly (ethylene glycol / tetramethylene glycol) mono (meth) acrylate and poly (propylene glycol / tetramethylene glycol) mono (meth) acrylate Glycol-modified hydroxy mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, methoxypolypropylene Alkyl-terminated polyalkylene glycol mono (meth) acrylates such as glycol mono (meth) acrylate and ethoxypolyethylene glycol mono (meth) acrylate, 2,2,2-trifluoromethyl (meth) acrylate, 2- (perfluorobutyl) ethyl Fluorine-containing (meth) acrylates such as (meth) acrylate, 3- (perfluorobutyl) -2-hydroxypropyl (meth) acrylate and 2- (perfluorohexyl) ethyl (meth) acrylate, N-cyclohexylmaleimide and N- Examples include (meth) acrylate-containing (meth) acrylates such as (meth) acryloyloxyethyl hexahydrophthalimide, and (meth) acryl silicone compounds such as mono (meth) acrylates having a dimethylsiloxane skeleton. It can be.

  About each content of the aromatic hydrocarbon frame | skeleton of above-mentioned (A-1) copolymer resin and (A-2) copolymer resin, the lower limit is flame retardance and compatibility with (C) diluent etc. From this point, 5 mass% is preferable, and 10 mass% is particularly preferable. The upper limit is preferably 40% by mass, particularly preferably 30% by mass, from the viewpoint of the flexibility of the solder resist film.

  The (A-1) copolymer resin and the (A-2) copolymer resin can be synthesized by a known solution polymerization method. The solvent used is not particularly limited as long as it is inert to radical polymerization. Examples thereof include ethylene glycol monoalkyl ether acetates such as ethyl acetate, isopropyl acetate, cellosolve acetate and butyl cellosolve acetate; diethylene glycol monoalkyl ether acetates such as diethylene glycol monomethyl ether acetate, carbitol acetate and butyl carbitol acetate; propylene glycol Acetic esters such as monoalkyl ether acetates and dipropylene glycol monoalkyl ether acetates; Diethylene glycol dialkyl ethers, diethylene glycol dialkyl ethers such as methyl carbitol, ethyl carbitol, and butyl carbitol; Triethylene glycol dialkyl ethers; Propylene glycol dialkyl ether Diether ethers such as 1,4-dioxane and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; hydrocarbons such as benzene, toluene, xylene, octane and decane; petroleum Examples include petroleum solvents such as ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha; lactic acid esters such as methyl lactate, ethyl lactate, and butyl lactate; dimethylformamide, N-methylpyrrolidone, and the like. These solvents may be used alone or in combination of two or more. The usage-amount of a solvent is 30-1000 mass parts with respect to 100 mass parts of copolymer resins, Preferably it is 50-800 mass parts.

  The radical polymerization initiator used in the solution polymerization method is not particularly limited, and for example, an organic peroxide or an azo compound can be used. Specific examples include benzoyl peroxide, dicumyl peroxide, diisopropyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoate, t-hexyl peroxybenzoate, t-butylperoxy-2-ethylhexa Noate, t-hexylperoxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis ( t-butylperoxy) hexyl-3,3-isopropyl hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, dicumyl hydroperoxide, acetyl peroxide, bis (4-t-butylcyclohexyl) peroxy Dicarbonate, diisopropyl par Xidicarbonate, isobutyl peroxide, 3,3,5-trimethylhexanoyl peroxide, lauryl peroxide, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (T-Hexylperoxy) 3,3,5-trimethylcyclohexane, azobisisobutyronitrile, azobiscarbonamide and the like can be used. A radical polymerization initiator having an appropriate half-life is appropriately selected according to the polymerization temperature. The usage-amount of a radical polymerization initiator is 0.5-20 mass parts with respect to a total of 100 mass parts of a radically polymerizable unsaturated compound, Preferably it is 1-10 mass parts.

  In the polymerization method, the unsaturated monomer and the radical polymerization initiator may be added dropwise to a heated solvent, followed by stirring. The unsaturated monomer and the radical polymerization initiator are dissolved in the solvent, and the temperature is increased while stirring. May be performed. Moreover, you may add an unsaturated monomer dropwise while adding a radical polymerization initiator in a solvent and heating up.

  By subjecting a part of the carboxyl group in the copolymer resin (A-1) obtained by the above polymerization method to an addition reaction with a compound having an oxirane ring and an ethylenically unsaturated bond, the copolymer (A-2) can be reacted. A polymerized resin can be obtained. About the addition amount of the compound which has an oxirane ring and an ethylenically unsaturated bond with respect to 1 equivalent of carboxyl groups in the copolymer resin of (A-1), the lower limit is 0.1 equivalent from the point which ensures sufficient photosensitivity. And preferably 0.2 equivalents. Moreover, the upper limit is 0.8 equivalent from the point which prevents that the amount of a carboxyl group decreases too much and developability becomes inadequate, Preferably it is 0.6 equivalent.

  The catalyst used for the reaction between the carboxyl group in the copolymer resin (A-1) and the compound having an oxirane ring and an ethylenically unsaturated bond is, for example, triphenylphosphine, lithium naphthenate, zirconium naphthenate. , Chromium naphthenate, chromium acetylacetonate, chromium chloride and the like. Moreover, methoxyhydroquinone etc. can be mentioned as a polymerization inhibitor. The reaction can be carried out by a known method, for example, a compound having an oxirane ring and an ethylenically unsaturated bond after setting the copolymer resin (A-1) in the solvent obtained by the polymerization reaction to a predetermined temperature. , The catalyst and the polymerization inhibitor are mixed and stirred. At this time, the usage-amount of a catalyst is 0.01-1 mass% with respect to the sum total of the compound which has (A-1) copolymer resin, an oxirane ring, and an ethylenically unsaturated bond. The usage-amount of a polymerization inhibitor is 0.01-1 mass% with respect to the sum total of the compound which has (A-1) copolymer resin, an oxirane ring, and an ethylenically unsaturated bond. Moreover, reaction temperature is 60-150 degreeC, and reaction time is 3 to 60 hours.

  (A-1) About the weight average molecular weight of a copolymer resin, the lower limit is 3000 from the point of the toughness of a cured coating film, and touch-drying property, Preferably it is 5000. On the other hand, the upper limit is 200000, preferably 50000, from the viewpoint of compatibility with (C) diluent and the like and alkali developability. Moreover, (A-2) About the weight average molecular weight of copolymer resin, the lower limit is 3000 from the point of the toughness of a cured coating film, and touch-drying property, Preferably it is 5000. On the other hand, the upper limit is 200000, preferably 50000, from the viewpoint of compatibility with (C) diluent and the like and alkali developability.

  The acid values of the obtained (A-1) copolymer resin and (A-2) copolymer resin are preferably in the range of 30 to 150 mgKOH / g, respectively. When the acid value is less than 30 mgKOH / g, the curability with the (B) curing agent component is lowered, or it is difficult to remove the uncured resin composition with a dilute alkaline aqueous solution, and when it exceeds 150 mgKOH / g, the moisture resistance of the cured film is reduced. This is because the properties and electrical characteristics are inferior.

(B) Curing agent The curing agent is for increasing the crosslinking density of the cured coating film to obtain a sufficient cured coating film. For example, an epoxy resin is added. Examples of the epoxy resin include bisphenol A type epoxy resin, novolak type epoxy resin (phenol novolak type epoxy resin, o-cresol novolak type epoxy resin, p-tert-butylphenol novolak type, etc.), bisphenol F and bisphenol S with epichlorohydrin. Bisphenol F type, bisphenol S type epoxy resin, bisphenol E type epoxy resin, 2,5-di-tert-butylhydroquinone type epoxy resin, biphenyl type epoxy resin, cyclohexene oxide group, tricyclodecane oxide obtained by reaction Hydrogenated epoxy resins such as cycloaliphatic epoxy resins having thiol groups, cyclopentene oxide groups, nuclear hydrogenated bisphenol A type epoxy resins, nuclear hydrogenated biphenyl type epoxy resins, tris 2,3-epoxypropyl) isocyanurate, triglycidyltris (2-hydroxyethyl) isocyanurate and the like triglycidyl isocyanurate having a diazine ring, dicyclopentadiene type epoxy resin, adamantane type epoxy resin, diglycidyl phthalic anhydride ester And ester type epoxy resins such as diglycidyl anhydride of hexahydrophthalic anhydride, melamine, methylated methylol melamine, butylated methylol melamine, imidazole, dicyandiamide and the like. These compounds may be used alone or in combination of two or more. The usage-amount of a hardening | curing agent is 10-100 mass parts with respect to 100 mass parts of copolymer resins from the point which obtains a sufficient coating film after hardening, and 20-50 mass parts is preferable.

(C) Diluent A diluent is a photopolymerizable monomer, for example, and is used to obtain a solder resist film having sufficient acid resistance, heat resistance, alkali resistance, etc., by sufficiently photocuring a curable resin. Examples of the photopolymerizable monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Dipentaerythritol hexaacrylate, bisphenol A type EO modified di (meth) acrylate, bisphenol A type PO modified di (meth) acrylate, caprolactone modified dipentaerythritol hexaacrylate, EO modified dipentaerythritol hexaacrylate, for example (meth) acrylic group And a urethane-based acrylic compound obtained by reacting a compound having at least one hydroxy group with a compound having at least one isocyanate group. The usage-amount of a diluent is 2.0-150 mass parts with respect to 100 mass parts of copolymer resins, and 10-80 mass parts is preferable. In the case of a diluent having two or more (meth) acryl groups, the (meth) acryl equivalent is preferably 200 g / eq or more, particularly preferably 300 g / eg or more from the viewpoint of flexibility and low warpage. In addition, the (meth) acryl equivalent in this specification means the molecular weight per (meth) acryloyl group.

  In the present invention, in addition to the above components, the following components can be blended as necessary.

(D) Inorganic white pigment The inorganic white pigment is for whitening the coating film, and examples thereof include anatase type titanium oxide and rutile type titanium oxide. Anatase-type titanium oxide has a higher whiteness than rutile-type titanium oxide, but has photocatalytic activity and may cause discoloration of the resin in the curable resin composition. On the other hand, rutile type titanium oxide is preferable in that it has almost no photocatalytic activity and can prevent discoloration of the solder resist film. The average particle size of the rutile-type titanium oxide particles is not particularly limited, but is usually 0.01 to 1 μm. Further, the surface treating agent for rutile type titanium oxide particles is not particularly limited. Examples of rutile titanium oxide include “TR-600”, “TR-700”, “TR-750”, “TR-840” manufactured by Fuji Titanium Industry Co., Ltd., and “R-550” manufactured by Ishihara Sangyo Co., Ltd. ”,“ R-580 ”,“ R-630 ”,“ R-820 ”,“ CR-50 ”,“ CR-60 ”,“ CR-90 ”,“ CR-93 ”, manufactured by Titanium Industry Co., Ltd. “KR-270”, “KR-310”, “KR-380”, “JR-1000” manufactured by Teika Co., Ltd., and the like can be used. The usage-amount of a rutile type titanium oxide is 30-800 mass parts with respect to 100 mass parts of copolymer resins, Preferably it is 50-500 mass parts.

(E) Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is generally used. For example, oxime initiator, benzoin, acetophenone, 2-hydroxy-2-methyl-1-phenyl Propan-1-one, 1-hydroxycyclohexyl phenyl ketone, benzophenone, and the like. The usage-amount of a photoinitiator is 5-20 mass parts with respect to 100 mass parts of copolymer resins, and 8-15 mass parts is preferable.

(F) Phosphorus-based flame retardant Phosphorus-based flame retardant is for imparting flame retardancy to the curable resin composition, for example, tris (chloroethyl) phosphate, tris (2,3-dichloropropyl) Phosphate, tris (2-chloropropyl) phosphate, tris (2,3-bromopropyl) phosphate, tris (bromochloropropyl) phosphate, 2,3-dibromopropyl-2,3-chloropropyl phosphate, tris (tribromophenyl) ) Halogen-containing phosphates such as phosphate, tris (dibromophenyl) phosphate, tris (tribromoneopentyl) phosphate; trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, etc. Non-halogen aliphatic phosphate esters of: triphenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, tricresyl phosphate, trixylenyl phosphate, xylenyl diphenyl phosphate, tris (isopropylphenyl) phosphate, isopropylphenyl diphenyl phosphate , Non-halogen aromatic phosphates such as diisopropylphenylphenyl phosphate, tris (trimethylphenyl) phosphate, tris (t-butylphenyl) phosphate, hydroxyphenyldiphenyl phosphate, octyldiphenyl phosphate; aluminum trisdiethylphosphinate, trismethylethylphosphine Aluminum oxide, aluminum trisdiphenylphosphinate Zinc, bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, bisdiphenylphosphine Metal salts of phosphinic acid such as titanyl acid, titanium tetrakisdiphenylphosphinate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter HCA), addition reaction product of HCA and acrylate , HCA and epoxy resin addition reaction products, HCA and hydroquinone addition reaction products such as HCA-modified compounds, diphenylvinylphosphine oxide, triphenylphosphine oxide, trialkyl Examples thereof include phosphine oxide compounds such as phosphine oxide and tris (hydroxyalkyl) phosphine oxide. Of these, non-halogen phosphates, metal salts of phosphinic acid, HCA-modified compounds, and phosphine oxide compounds are preferred from the viewpoint of reducing environmental burden. In small amounts, not only flame retardancy but also bleed out resistance The metal salt of phosphinic acid is particularly preferable from the viewpoint of excellent properties and discoloration resistance. The amount of the phosphorus-based flame retardant used is 3 to 20 parts by mass with respect to 100 parts by mass of the copolymer resin, and the reduction of the mechanical strength of the solder resist film is surely suppressed while ensuring sufficient flame resistance. From 4 to 15 parts by mass is preferable.

  A metal hydroxide is mix | blended as a flame retardant adjuvant, for example, aluminum hydroxide etc. can be mentioned. The usage-amount is 1-100 mass parts with respect to 100 mass parts of copolymer resins.

  In the present invention, various additional components such as an antifoaming agent, a dispersant, an extender pigment, an inorganic ion catcher, an organic solvent, and the like can be appropriately blended as necessary. A well-known thing can be used for an antifoamer, for example, a silicone type, a hydrocarbon type, an acrylic type etc. can be mentioned. Examples of the dispersant include silane-based, titanate-based, and alumina-based coupling agents. The extender pigment is for increasing the physical strength of the coated solder resist film, and examples thereof include silica, barium sulfate, alumina, aluminum hydroxide, talc, and mica. Examples of inorganic ion catchers include zirconium phosphate compounds.

  The organic solvent is for adjusting the viscosity and drying property of the curable resin composition, for example, ketones such as methyl ethyl ketone and cyclohexane, aromatic hydrocarbons such as toluene and xylene, methanol, isopropanol, and cyclohexanol. Alcohols such as cyclohexane and methylcyclohexane, petroleum solvents such as petroleum ether and petroleum naphtha, cellosolves such as cellosolve and butylcellosolve, carbitols such as carbitol and butylcarbitol, acetic acid Examples thereof include acetates such as ethyl, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, and butyl carbitol acetate.

  The method for producing the curable resin composition of the present invention described above is not limited to a specific method. For example, after blending each of the above components at a predetermined ratio, the components are premixed with a stirrer and mixed and dispersed with a three roll at room temperature. Can be manufactured.

  Next, the coating method of the curable resin composition of the present invention described above will be described. When thermosetting the curable resin composition of the present invention obtained as described above, for example, screen printing on a printed wiring board having a circuit pattern formed by etching a copper foil of a copper-clad laminate. After applying to a desired thickness using a method such as spraying or spray coating, the curable resin composition is thermally cured by heating for 20 to 80 minutes with a hot air circulating dryer at 130 to 170 ° C. A desired solder resist film can be formed on the printed wiring board.

  When photocuring the curable resin composition of the present invention obtained as described above, for example, on a flexible wiring board having a circuit pattern formed by etching a copper foil, a screen printing method, a spray coating method. In order to volatilize the solvent in the curable resin composition, preliminary drying is performed by heating at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes. Then, the negative film which has the pattern which made translucent except the land of the said circuit pattern was stuck on the apply | coated curable resin composition, and an ultraviolet-ray is irradiated from it. Then, the coating film is developed by removing the non-exposed areas corresponding to the lands with a dilute alkaline aqueous solution. As a developing method, a spray method, a shower method, or the like is used. As a dilute alkali aqueous solution used, a 0.5 to 5% sodium carbonate aqueous solution is generally used, but other alkalis can also be used. Next, the target solder resist film can be formed on the flexible wiring board by performing post-cure for 20 to 80 minutes with a hot air circulation dryer at 130 to 170 ° C.

  An electronic circuit unit is formed by soldering an electronic component to the flexible wiring board covered with the solder resist film thus obtained by a jet soldering method, a reflow soldering method, or the like.

  Next, examples of the present invention will be described. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

(A-1) (A-2) Synthesis of carboxyl group-containing copolymer resin having aromatic ring Synthesis Example 1
Into a 500 mL four-necked flask equipped with a stirrer, a thermometer, and a reflux tube, 110 g of dipropylene glycol monomethyl ether (hereinafter referred to as DPM) was added, heated to 120 ° C. in a nitrogen atmosphere, and then 17.2 g (0 .2 mol), phenoxyethyl methacrylate (SR-340 manufactured by Sartomer, hereinafter referred to as PEMA) 92.8 g (0.45 mol), dimethyl 2,2′-azobis (2-methylpropionate) (V- 601 (hereinafter referred to as DMAMP) and a mixed solution of 4.6 g of DPM and 10 g of DPM over about 1 hour, and then stirred at 120 ° C. for 3 hours to produce a DPM solution containing about 49% by mass of the copolymer resin of Synthesis Example 1. Thus, a copolymer resin of Synthesis Example 1 was obtained. The weight average molecular weight of the carboxyl group-containing copolymer resin having an aromatic ring was about 25000 (polystyrene conversion), and the solid content acid value was 98 mgKOH / g.

Synthesis example 2
A 500 mL four-necked flask equipped with a stirrer, a thermometer, and a reflux tube was charged with 125 g of dipropylene glycol monomethyl ether (hereinafter DPM), heated to 120 ° C. in a nitrogen atmosphere, and then 34.4 g of methacrylic acid (0. 4 mol), 82.5 g (0.4 mol) of PEMA, 5.5 g of DMAMP, and 10 g of DPM were added dropwise over about 1 hour, followed by stirring at 120 ° C. for 3 hours to obtain a copolymer having a carboxyl group.

  Next, after lowering the temperature in the flask to 100 ° C., a mixture gas of air and nitrogen (air volume to nitrogen volume ratio is 1 to 2) is bubbled through the flask at 200 mL / min while glycidyl methacrylate (Japan) Add 21.3 g (0.15 mol) of an oil and fat blender GH (hereinafter GMA), 0.3 g of triphenylphosphine (hereinafter TPP) as a reaction catalyst, 0.1 g of methoxyhydroquinone (hereinafter MEHQ) as a polymerization inhibitor, and add 100 ° C. The reaction is continued for 5 hours at 115 ° C. until the acid value finishes decreasing to produce a DPM solution containing about 52% by mass of the copolymer resin of Synthesis Example 2, and the copolymer resin of Synthesis Example 2 is obtained. It was. The weight average molecular weight was about 18000 (polystyrene conversion), and the solid content acid value was 97 mgKOH / g.

Synthesis example 3
82.5 g (0.4 mol) of PEMA in Synthesis Example 2 was converted to 74.2 g (0.36 mol), and 21.3 g (0.15 mol) of GMA was 4-hydroxybutyl acrylate glycidyl ether (4-HBAGE, Nippon Kasei Chemical Co., Ltd., hereinafter referred to as 4- HBAGE) A DPM solution containing about 52% by mass of the copolymer resin of Synthesis Example 3 was produced in the same manner as in Synthesis Example 2 except that the amount was changed to 30.0 g (0.15 mol). Obtained. The weight average molecular weight was about 16000 (polystyrene conversion), and the solid content acid value was 97 mgKOH / g.

Synthesis example 4
125 g DPM of Synthesis Example 2 to 160 g, 34.4 g (0.4 mol) of methacrylic acid to 56.8 g (0.66 mol), 82.5 g (0.4 mol) of PEMA to 47.4 g (0.23 mol), The copolymer resin of Synthesis Example 4 was prepared in the same manner as Synthesis Example 2 except that 5.5 g of DMAMP was changed to 6.5 g, and further 21.3 g (0.15 mol) of GMA was changed to 70.1 g (0.35 mol) of 4-HBAGE. A DPM solution containing about 52% by mass was produced, and a copolymer resin of Synthesis Example 4 was obtained. The weight average molecular weight was about 19000 (polystyrene conversion), and the solid content acid value was 96 mgKOH / g.

Synthesis example 5
Synthetic Example 2 except that 82.5 g (0.4 mol) of PEMA in Synthetic Example 2 was changed to 85.1 g (0.34 mol) of 2 (2-phenoxyethoxy) ethyl methacrylate (Nippon Bremer PAE-100, hereinafter referred to as 2 PEEMA). In the same manner as above, a DPM solution containing about 52% by mass of the copolymer resin of Synthesis Example 5 was produced, and the copolymer resin of Synthesis Example 5 was obtained. The weight average molecular weight was about 18000 (polystyrene conversion), and the solid content acid value was 96 mgKOH / g.

Synthesis Example 6
A DPM solution containing about 52% by mass of the copolymer resin of Synthesis Example 6 in the same manner as Synthesis Example 2 except that 82.5 g (0.4 mol) of PEMA of Synthesis Example 2 was changed to 75.1 g (0.3 mol) of 2PEEMA. To obtain a copolymer resin of Synthesis Example 6. The weight average molecular weight was about 20000 (polystyrene conversion), and the solid content acid value was 97 mgKOH / g.

Synthesis example 7
125 g DPM of Synthesis Example 2 to 105 g, 34.4 g (0.4 mol) of methacrylic acid to 25.8 g (0.3 mol), 82.5 g (0.4 mol) of PEMA to 42.7 g (0.4 mol) of styrene and normal Synthesis example except that 15.6 g (0.1 mol) of butyl methacrylate (Mitsubishi Rayon acrylate ester BMA, hereinafter referred to as nBMA) and GMA 21.3 g (0.15 mol) were changed to 4-HBAGE 22.0 g (0.11 mol) In the same manner as in Example 2, a DPM solution containing about 47% by mass of the copolymer resin of Synthesis Example 7 was produced to obtain the copolymer resin of Synthesis Example 7. The weight average molecular weight was about 14,000 (polystyrene conversion), and the solid content acid value was 95 mgKOH / g.

Synthesis example 8
125 g DPM of Synthesis Example 2 to 110 g, 34.4 g (0.4 mol) methacrylic acid to 25.2 g (0.35 mol) acrylic acid, 82.5 g (0.4 mol) PEMA to 59.8 g (0.29 mol) A DPM solution containing about 48% by mass of the copolymer resin of Synthesis Example 8 was produced in the same manner as Synthesis Example 2 except that 5.5 g of DMAMP was changed to 4 g, and the copolymer resin of Synthesis Example 8 was obtained. The weight average molecular weight was about 16000 (polystyrene conversion), and the solid content acid value was 101 mgKOH / g.

Synthesis Example 9
34.4 g (0.4 mol) of methacrylic acid of Synthesis Example 2 was added to 23.8 g (0.33 mol) of acrylic acid, 82.5 g (0.4 mol) of PEMA was added to 57.6 g (0.23 mol) of 2 PEEMA, and 5.5 g of DMAMP was added. A DPM solution containing about 48% by mass of the copolymer resin of Synthesis Example 9 was produced in the same manner as in Synthesis Example 2 except that the amount was changed to 4.0 g, and a copolymer resin of Synthesis Example 9 was obtained. The weight average molecular weight was about 15000 (polystyrene conversion), and the solid content acid value was 94 mgKOH / g.

  Table 1 below shows the raw material ratio (mol), aromatic hydrocarbon skeleton ratio (mass%), and acid value (mgKOH / g) of the resins according to Synthesis Examples 1 to 9.

Comparative Synthesis Example 1
Into a 500 mL four-necked flask equipped with a stirrer, a thermometer, and a reflux tube, 80 g of propylene glycol diacetate (hereinafter referred to as PGDA) was added, heated to 90 ° C. in a nitrogen atmosphere, and then 28.4 g (0.2 mol) of GMA. 2-hydroxyethyl methacrylate caprolactone adduct (average 1 mol addition, Placel Cell FM1D manufactured by Daicel Chemical Industries) 49.9 g (0.2 mol), DMAMP 1 g, mercaptopropionic acid-2-ethylhexyl (manufactured by Sakai Chemical Industry, EHMP) 1 g and PGDA After 80 g of the mixed solution was dropped over about 1 hour, the mixture was stirred at 90 ° C. for 8 hours to obtain a copolymer having an epoxy group.

  Next, 72.02 g (0.21 mol) of acrylic acid and 0.5 g of TPP as a reaction catalyst were passed through the flask while aerated with a mixed gas of air and nitrogen (air volume to nitrogen volume ratio of 1 to 2) at 200 mL / min. Add 0.2g of MEHQ as a polymerization inhibitor, react at 100 ° C for 5 hours, and continue the reaction at 115 ° C until the acid value has finished decreasing, adding the epoxy group of the copolymer and the carboxyl group of acrylic acid. Went. After the acid value became 2 or less, the temperature in the flask was lowered to 90 ° C., and 16.0 g (0.16 mol) of succinic anhydride was added and reacted for 8 hours or longer to open the ring of acid anhydride. An addition reaction was performed. A solution of the copolymer resin of Comparative Synthesis Example 1 having no aromatic hydrocarbon skeleton was obtained with the point when the acid anhydride peak disappeared by IR as the end point of the reaction. This resin solution had a solid content of about 40% by mass, a weight average molecular weight of about 12000 (in terms of polystyrene), and a solid content acid value of 78 mgKOH / g.

Comparative Synthesis Example 2
In a 500 mL four-necked flask equipped with a stirrer, thermometer, and reflux tube, 105 g of DPM was charged and heated to 120 ° C. in a nitrogen atmosphere. Then, 43.0 g (0.5 mol) of methacrylic acid, 21.3 g of n-BMA ( 0.15 mol), a mixed solution of DMAMP 4.5 g and DPM 10 g was added dropwise over about 1 hour, followed by stirring at 120 ° C. for 3 hours to obtain a copolymer having a carboxyl group.

  Next, after the temperature in the flask was lowered to 100 ° C., 14.2 g of GMA (0. 2 g) was added while a gas mixture of air and nitrogen (air volume to nitrogen volume ratio of 1 to 2) was bubbled through the flask at 200 mL / min. 1 mol) and m, p-cresyl glycidyl ether (Sakamoto Yakuhin m, p-CGE) 32.8 g (0.2 mol), reaction catalyst as triphenylphosphine (TPP) 0.3 g, polymerization inhibitor as methoxyhydroquinone (Hereafter MEHQ) 0.1 g was added, reacted at 100 ° C. for 5 hours, and continued at 115 ° C. until the acid value decreased, and the aromatic hydrocarbon having a hydrogen atom at the α-position of the carboxyl group and side chain A DPM solution containing about 48% by mass of a copolymer resin having a skeleton and a methacryl group was produced, and a copolymer resin of Comparative Synthesis Example 2 was obtained. The weight average molecular weight was about 15000 (polystyrene conversion), and the solid content acid value was 96 mgKOH / g.

Comparative Synthesis Example 3
Comparative Production Example 2 except that GMA 14.2 g (0.1 mol) and m, p-cresyl glycidyl ether 32.8 g (0.2 mol) were replaced with GMA 42.6 g (0.3 mol). Similarly, a DPM solution containing about 49% by mass of a copolymer resin having a carboxyl group and a methacryl group but not having an aromatic hydrocarbon skeleton was produced, and a copolymer resin of Comparative Synthesis Example 3 was obtained. The weight average molecular weight was about 15000 (polystyrene conversion), and the solid content acid value was 100 mgKOH / g.

Examples 1-25, Comparative Examples 1-9
Each component shown in the following Tables 2, 3, and 4 was blended at the blending ratios shown in the following Tables 2, 3, and 4, and after premixing with a stirrer, mixed and dispersed at room temperature using three rolls, The curable resin composition used in Examples 1-25 and Comparative Examples 1-9 was prepared. And the prepared curable resin composition was applied as follows and the test piece was created. The compounding amounts shown in the following Tables 2, 3, and 4 represent parts by mass.

In Table 2,
Epicoat 828: Japan Epoxy Resin Co., Ltd. bisphenol A type epoxy resin,
DPHA: Nippon Kayaku Co., Ltd. dipentaerythritol hexaacrylate,
DPM: Kyowa Hakko Kogyo Co., Ltd. dipropylene glycol monomethyl ether,
Rutile titanium oxide: “CR-80” manufactured by Ishihara Sangyo Co., Ltd.
KS-66: Silicon oil manufactured by Shin-Etsu Silicone.

In Table 3,
YX-8000: Nuclear hydrogenated bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd.
TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide,
BAPO: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide.

In Table 4,
ACA-Z250: resin solution manufactured by Daicel Chemical Industries, Ltd. (having an alicyclic skeleton, no aromatic hydrocarbon skeleton, having a carboxyl group and an acrylic group),
Epicoat 1004F: Bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd.
YDC-1312: Ditertiary butyl hydroquinone modified epoxy resin manufactured by Toto Kasei Co., Ltd.
BP4EA: EO-modified bisphenol A acrylate (EO = 4) manufactured by Kyoeisha Chemical,
AH-600: Bifunctional urethane-modified epoxy acrylate manufactured by Kyoeisha Chemical,
EBECRYL 3708: Daicel Cytec Co., Ltd. bifunctional epoxy acrylate,
UF-8001G: Bifunctional urethane acrylate made by Kyoeisha Chemical,
SPEEDCURE TPO: Made by Nippon Siebel Hegner,
IRGACURE 819: manufactured by Ciba Specialty Chemicals.

Test piece preparation process 1 (Examples 1-4, Comparative Examples 1-3)
It is a test piece preparation process for evaluating the reflectance and discoloration of the heat-cured coating film, and a curable resin composition is applied by screen printing on a copper clad laminate that has been surface-treated by buffing. After coating, curing was performed at 150 ° C. for 60 minutes in a BOX furnace to form a cured coating film. The thickness of the cured coating film after curing was 20 to 23 μm.

Test piece preparation process 2 (Examples 5-14, Comparative Examples 4-6)
This is a test piece preparation process for evaluating the reflectance and discoloration of a cured coating film formed on a rigid substrate. It is cured by screen printing on a copper clad laminate that has been surface-treated by buffing. After applying the resin composition, preliminary drying was performed at 80 ° C. for 20 minutes in a BOX furnace. After preliminary drying, the coating film was exposed to 500 mJ / cm ² with an exposure device (OMW HMW-680GW), developed with 30 ° C., 1% aqueous sodium carbonate solution, and then heated at 150 ° C. in a BOX furnace at 60 ° C. The cured film was formed on the copper clad laminate by curing for a minute. The thickness of the cured coating film was 20-23 μm.

Test piece preparation step 3 (Examples 15 to 25, Comparative Examples 7 to 9)
This is a test piece preparation process for evaluating the reflectivity and discoloration of a cured coating film formed on a flexible substrate. A flexible substrate (Espanex made by Nippon Steel Chemical Co., Ltd.) that has been surface-treated with dilute sulfuric acid (3%) After applying the curable resin composition on a copper body of MB series) by screen printing, preliminary drying was performed at 80 ° C. for 20 minutes in a BOX furnace. After preliminary drying, the coating film was exposed to 500 mJ / cm ² with an exposure device (OMW HMW-680GW), developed with 30 ° C., 1% aqueous sodium carbonate solution, and then heated at 150 ° C. in a BOX furnace at 60 ° C. A cured coating film was formed on the flexible substrate by curing for a minute. The thickness of the cured coating film was 20-23 μm.

Test piece preparation step 4 (Examples 15 to 25, Comparative Examples 7 to 9)
This is a test piece preparation process for evaluating alkali developability, flexibility, warpage, and flame retardancy of a cured coating film formed on a flexible substrate. To polyimide film (Kapton 100H manufactured by Toray DuPont Co., Ltd.) After the surface treatment of the flexible substrate on which the copper circuit pattern is formed with dilute sulfuric acid (3%), the curable resin composition is applied by screen printing, and then pre-dried at 80 ° C. for 20 minutes in a BOX furnace. went. After preliminary drying, the coating film was exposed to 500 mJ / cm ² with an exposure device (OMW HMW-680GW), developed with 30 ° C., 1% aqueous sodium carbonate solution, and then heated at 150 ° C. in a BOX furnace at 60 ° C. A cured coating film was formed on the flexible substrate by curing for a minute. The thickness of the cured coating film was 20-23 μm.

(1) Reflectance The reflectivity at 450 nm was measured using a spectrophotometer U-3410 (manufactured by Hitachi, Ltd .: φ60 mm integrating sphere). “Initial” is after curing, “After thermal degradation” is after reflow treatment, “After photodegradation” is after UV irradiation 50 J / cm ² treatment, “After humidification” is 85 ° C., 85% RH means 1000 hours after standing.
(2) Visual inspection It is an index for visually confirming the degree of discoloration from white to yellow with respect to the appearance of the cured coating film. A: Appearance with high whiteness without yellow discoloration at all. Yellowish discoloration is slightly observed but white appearance, Δ: yellow discoloration is observed and slightly yellowish appearance, x: yellow discoloration is strongly observed and brown yellow appearance is evaluated in 4 stages did.
(3) Alkali developability After development, the presence or absence of residue on the copper body and the polyimide was visually evaluated. ○: No residue on the copper body and polyimide, Δ: No residue on the copper body However, the evaluation was made in three stages: a residue remained on the polyimide, x: a residue remained on the copper body and the polyimide.
(4) Flexibility For the coated film after exposure, the flexibility of the coated film was evaluated by visual observation and optical microscope observation of × 200 by a cylindrical mandrel method. ○: No abnormality at a diameter of 2 mm or less, Δ : No abnormality at a diameter of 4 mm, but abnormalities such as cracks and peeling at a diameter of 2 mm or less, and x: Anomalies such as cracks and peeling at a diameter of 4 mm or more were evaluated in three stages.
(5) Warpage property After cutting the test piece into 2cm x 2.5cm, place the test piece gently on a horizontal table so that the top is concave, and make sure that no external force is applied. The vertical distance between the corner and the table was measured to a unit of 1 mm with a straight scale, and the maximum value was taken as the amount of warpage. About the measurement result, (circle): The amount of curvature of less than 5 mm, (triangle | delta): The amount of curvature of 5-8 mm, and x: The amount of curvature exceeding 8 mm evaluated.
(6) Flame retardancy The test piece was subjected to a vertical combustion test based on the UL94 standard. Evaluation was expressed as VTM-0 to combustion based on the UL94 standard.

  The measurement results of Examples 1 to 25 and Comparative Examples 1 to 9 are shown in Tables 5, 6, and 7 below.

About the case where the curable resin composition of the present invention is thermally cured, from Examples 1 to 4 and Comparative Examples 1 and 2, by using methacrylic acid as a raw material of the copolymer, the reflectance reduction and discoloration of the cured film are achieved. I was able to suppress it. Moreover, from Examples 1-4 and Comparative Example 3, after polymerization, by using the general formula (II) and the general formula (III) having no hydrogen atom at the side chain α-position of the aromatic hydrocarbon skeleton, The decrease in reflectance and discoloration of the cured film could be suppressed. On the other hand, by adding m, p-cresyl glycidyl ether, in Comparative Example 3 containing an aromatic hydrocarbon having a hydrogen atom at the side chain α-position after polymerization, in the initial stage (after curing), Although the decrease in reflectance and the occurrence of discoloration could be suppressed, even when methacrylic acid was used as the raw material for the copolymer, after heat deterioration (after reflow) and after light deterioration (after UV irradiation 50 J / cm ² ), The reflectivity of the cured film decreased and discoloration occurred.

When the curable resin composition of the present invention was photocured on a rigid substrate, from Examples 5 to 14 and Comparative Examples 4 and 5, the cured film was formed by using (meth) acrylic acid as a raw material for the copolymer. Reduction in reflectance and discoloration could be suppressed. Further, from Examples 5 to 14 and Comparative Example 6, by using the general formula (II) and the general formula (III) having no hydrogen atom at the side chain α-position of the aromatic hydrocarbon skeleton after polymerization, The decrease in reflectance and discoloration of the cured film could be suppressed. On the other hand, by adding m, p-cresyl glycidyl ether, after the polymerization, in Comparative Example 6 containing an aromatic hydrocarbon having a hydrogen atom at the side chain α-position, in the initial stage (after post-cure), a cured film was obtained. Although the decrease in reflectance and the occurrence of discoloration could be suppressed, even if methacrylic acid was used as a raw material for the copolymer, after heat deterioration (after reflow) and after light deterioration (after UV irradiation 50 J / cm ² ) The reflectivity of the cured film was lowered and discoloration occurred.

  When the curable resin composition of the present invention was photocured on a flexible substrate, (meth) acrylic acid was used as a raw material for the copolymer in comparison with Examples 15 to 25, Comparative Examples 8 and 9 and Comparative Example 7. It was possible to suppress the decrease in reflectance and discoloration of the cured film. In Examples 15 to 25, all of alkali developability, flexibility, low warpage, and flame retardancy were excellent. On the other hand, since Comparative Examples 7 and 8 did not contain an aromatic hydrocarbon skeleton, compatibility with (C) diluent and the like was inferior, alkali developability was lowered, and flame retardancy and flexibility were also lowered. From Examples 15 to 25 and Comparative Example 9, by using (meth) acrylic acid as a raw material for the copolymer, the decrease in reflectance is small and the occurrence of discoloration is suppressed even if it does not contain an aromatic hydrocarbon skeleton. However, since it has an alicyclic skeleton without containing an aromatic hydrocarbon skeleton, the compatibility with the diluent (C) is poor and the alkali developability is lowered, and the flame retardancy and flexibility are also improved. Declined. Further, in Comparative Example 9, the warpage was large and the warpage was inferior.

  Since the curable resin composition of the present invention can form a cured coating film having flexibility and low warpage while preventing a decrease in reflectance due to aging and thermal history, a solder resist film of a printed wiring board, in particular, light emission. The utility value is high in the field of a solder resist film of a mounting substrate such as a diode element (LED).

Claims (13)

(A-1) General formula (I)
(Wherein R ¹ represents a hydrogen atom or a methyl group),
Formula (II)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. A group, an adamantyl group or a trifluoromethyl group, and m is an integer of 0 or 1-3) and / or the general formula (III)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. Group, an adamantyl group or a trifluoromethyl group, A ¹ represents a C 2-10 alkylene group or a C 3-10 hydroxyalkylene group containing a linear or cyclic skeleton, and m is 0 or 1-3. An integer, p is an integer of 1 to 5), and a copolymer resin obtained by reacting the compound represented by
Or (A-2) general formula (I)
(Wherein R ¹ represents a hydrogen atom or a methyl group),
Formula (II)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. A group, an adamantyl group or a trifluoromethyl group, and m is an integer of 0 or 1-3) and / or the general formula (III)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a phenyl group, an α-cumyl group, an alkoxy group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms in an alkyl group, and t-butyl. Group, an adamantyl group or a trifluoromethyl group, A ¹ represents a C 2-10 alkylene group or a C 3-10 hydroxyalkylene group containing a linear or cyclic skeleton, and m is 0 or 1-3. An integer, p is an integer of 1 to 5), and a copolymer obtained by adding a compound having an oxirane ring and an ethylenically unsaturated bond to a part of the carboxyl group of the copolymer obtained by reacting the compound represented by Polymerization resin,
A curable resin composition comprising (B) a curing agent and (C) a diluent. The compound having an oxirane ring and an ethylenically unsaturated bond has the general formula (IV)
(Wherein R ¹ represents a hydrogen atom or a methyl group, A ² represents an alkylene group having 2 to 10 carbon atoms, and q is 0 or an integer of 1 to 5). The curable resin composition according to claim 1.   The curable resin composition according to claim 1, wherein the (A-1) copolymer resin and the (A-2) copolymer resin have an aromatic hydrocarbon skeleton of 5 to 40% by mass. .   2. The curable resin composition according to claim 1, wherein the acid value of the (A-1) copolymer resin and the acid value of the (A-2) copolymer resin are 30 to 150 mg KOH / g. .   Furthermore, (D) inorganic white pigment is contained, The curable resin composition of Claim 1 characterized by the above-mentioned.   6. The curable resin composition according to claim 5, wherein the (D) inorganic white pigment is rutile titanium oxide.   2. The curable resin according to claim 1, wherein the (B) curing agent includes at least one selected from the group consisting of a compound having two or more epoxy groups in one molecule, melamine, and a melamine derivative. Composition.   The curable resin composition according to claim 1, wherein the diluent (C) contains a compound having one or more ethylenically unsaturated groups in one molecule.   The curing according to claim 1 or 8, wherein the (C) diluent is a compound having two or more (meth) acrylic groups and having a (meth) acrylic equivalent of 200 g / eq or more. Resin composition.   The curable resin composition according to claim 1, further comprising (E) a photopolymerization initiator.   The curable resin composition according to claim 1, further comprising (F) a phosphorus-based flame retardant.   The curable resin composition according to claim 1, further comprising (G) a metal hydroxide.   The printed wiring board with which the soldering resist film formed using the curable resin composition of any one of Claims 1 thru | or 12 was coat | covered.