Photosensitive resin composition for inkjet and printed wiring board

Abstract

The present invention relates to a photosensitive resin composition for inkjet, which comprises (A) a (meth)acrylic resin having a weight average molecular weight of 500 or more, (B) a (meth)acrylic compound having a weight average molecular weight of less than 500, (C) a phosphorus-containing compound, and (D) a photopolymerization initiator, wherein the component (C) is a compound other than a phosphate ester and is a compound having a functional group capable of reacting by photoradical polymerization or photocationic polymerization in one molecule.

Description

Technical Field

[0001] This invention relates to a photosensitive resin composition for inkjet printing and a printed wiring substrate. Background Technology

[0002] As a photosensitive resin composition used to form solder resist films on printed wiring substrates, various properties are required, such as solder heat resistance and adhesion to insulating substrates or conductor layers. Currently, this photosensitive resin composition is coated using methods such as screen printing, but in recent years, inkjet coating techniques have also been researched.

[0003] As a photosensitive resin composition suitable for inkjet printing, for example, a curable composition has been proposed, which comprises: (A) a photoalkali-generating agent, (B) an epoxy-containing (meth)acrylate compound, (C) a photopolymerization initiator, and (D) a thermosetting component (except for (B) the epoxy-containing (meth)acrylate compound) (see Reference 1: Japanese Patent Application Publication No. 2015-110765).

[0004] On the other hand, heating elements are sometimes mounted on printed wiring substrates, thus requiring flame retardancy in the solder resist film. To stably spray flame-retardant photosensitive resin compositions using inkjet printing, a fine-particle-size flame retardant, for example, with an average particle size of 1 μm or less, needs to be incorporated into the photosensitive resin composition. Therefore, to apply photosensitive resin compositions using inkjet printing, flame retardants that have been pulverized from powder and refined into fine particles are sometimes incorporated into the photosensitive resin composition.

[0005] However, even pulverizing powdered flame retardants cannot achieve sufficiently fine particle size, leaving room for improvement in the stable spraying of flame-retardant photosensitive resin compositions using inkjet printing. Furthermore, depending on the type of flame retardant, it sometimes seeps out from the solder resist film, causing problems with the anti-seepage properties of the cured coating. Summary of the Invention

[0006] The object of the present invention is to provide an inkjet photosensitive resin composition with excellent coatability and capable of forming a cured material with excellent electrical insulation, flame retardancy and impermeability, as well as a printed wiring substrate using the same.

[0007] One aspect of the present invention is a photosensitive resin composition for inkjet printing comprising (A) a (meth)acrylic resin with a weight-average molecular weight of 500 or more, (B) a (meth)acrylic compound with a weight-average molecular weight of less than 500, (C) a phosphorus-containing compound, and (D) a photopolymerization initiator, wherein the component (C) is a compound other than a phosphate ester and has functional groups in one molecule capable of reacting by photoradical polymerization or photocationic polymerization.

[0008] In one aspect of the inkjet photosensitive resin composition of the present invention, the component (C) preferably has an unsaturated double bond or an epoxy ring in one molecule.

[0009] In one aspect of the inkjet photosensitive resin composition of the present invention, the component (C) is preferably at least one selected from the compounds shown in formulas (1) to (3) below.

[0010]

[0011] In one aspect of the inkjet photosensitive resin composition of the present invention, it is preferable to use two or more of the aforementioned components (C) in combination.

[0012] In one aspect of the inkjet photosensitive resin composition of the present invention, it is preferred that the component (B) has a cyclic skeleton in one molecule.

[0013] In one aspect of the inkjet photosensitive resin composition of the present invention, it is preferred that the component (D) has phosphorus atoms in one molecule.

[0014] One aspect of the printed wiring substrate of the present invention includes a solder resist film formed from the inkjet photosensitive resin composition of one aspect of the present invention described above.

[0015] According to the present invention, an inkjet photosensitive resin composition with excellent coatability and the ability to form a cured product with excellent electrical insulation, flame retardancy and exudation prevention can be provided, as well as a printed wiring substrate using the inkjet photosensitive resin composition. Detailed Implementation

[0016] [Photosensitive resin composition for inkjet printing]

[0017] First, the inkjet photosensitive resin composition (hereinafter also simply referred to as "photosensitive resin composition") of this embodiment will be described.

[0018] The photosensitive resin composition of this embodiment contains (A) a (meth)acrylic resin with a weight average molecular weight of 500 or more, (B) a (meth)acrylic compound with a weight average molecular weight of less than 500, (C) a phosphorus-containing compound, and (D) a photopolymerization initiator.

[0019] [Ingredients (A)]

[0020] In this embodiment, any (meth)acrylic resin with a weight-average molecular weight of 500 or higher can be used, regardless of its chemical structure. It should be noted that, in this specification, "weight-average molecular weight" refers to the weight-average molecular weight determined by gel permeation chromatography (GPC) at room temperature and calculated using polystyrene conversion.

[0021] As component (A), examples include: polymers containing monomers of (meth)acrylic acid, polymers containing monomers of (meth)acrylate, polymers containing monomers of (meth)acrylic acid and (meth)acrylate, epoxy (meth)acrylate obtained by reacting (meth)acrylic acid with epoxy resin, and polyurethane (meth)acrylate, etc. Among these, epoxy (meth)acrylate and polyurethane (meth)acrylate are preferred from the viewpoint that the coating properties are further improved by inkjet printing and that a cured product with better anti-bleeding properties can be obtained.

[0022] Epoxy (meth)acrylates can be obtained by reacting (meth)acrylic acid with at least a portion of the epoxy groups of an epoxy resin having one or more epoxy groups in one molecule. Examples of epoxy resins are not particularly limited, but include: biphenyl aralkyl type epoxy resins, phenyl aralkyl type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, rubber-modified epoxy resins (such as organosilicon-modified epoxy resins), ε-caprolactone-modified epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenolic varnish type epoxy resins, cresol phenolic varnish type epoxy resins, cyclic aliphatic polyfunctional epoxy resins, glycidyl ester type polyfunctional epoxy resins, glycidylamine type polyfunctional epoxy resins, heterocyclic polyfunctional epoxy resins, bisphenol-modified phenolic varnish type epoxy resins, and polyfunctional modified phenolic varnish type epoxy resins, etc.

[0023] This epoxy (meth)acrylate does not have a free carboxyl group.

[0024] Examples of polyurethane (meth)acrylates include those obtained by reacting (meth)acrylic acid with polyurethane. Polyurethane is a resin obtained by reacting a compound having two or more isocyanate groups in one molecule with a polyol compound having two or more hydroxyl groups in one molecule.

[0025] Compounds having two or more isocyanate groups in one molecule are not particularly limited, but can include: hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene diisocyanate (MDI), methylene dicyclohexyl isocyanate, trimethylhexamethylene diisocyanate, hexane diisocyanate, hexamethylamine diisocyanate, methylene dicyclohexyl isocyanate, toluene diisocyanate, 1,2-diphenylethane diisocyanate, 1,3-diphenylpropane diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate, etc. These compounds can be used alone or in combination of two or more.

[0026] As a polyol compound having two or more hydroxyl groups in one molecule, there is no particular limitation, but examples include: aliphatic diols (ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, neopentanediol, 1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 3,3-dihydroxymethylheptane, 2-ethyl-2-butyl-1,3-propanediol, 1,12-dodecanediol, 1,18-octadecanediol, etc., alkyl diols with 2 to 22 carbon atoms, 2-butene-1,4-propanediol, etc. ... Alcohols include alkyl hydrides, olefinic diols such as 2,6-dimethyl-1-octen-3,8-diol, alicyclic diols (1,4-cyclohexanediol, 1,4-cyclohexanediol, etc.), aliphatic triols (glycerol, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-(hydroxymethyl)pentane, and 2,2-bis(hydroxymethyl)-3-butanol, etc.), and polyols (tetramethylolmethane, pentaerythritol, dipentaerythritol, and xylitol, etc.). These can be used individually or in combination of two or more.

[0027] This polyurethane (meth)acrylate does not have free carboxyl groups.

[0028] Other polyurethane (meth)acrylates include, for example, epoxy (meth)acrylates obtained by reacting (meth)acrylic acid with at least a portion of the epoxy groups of an epoxy resin having one or more epoxy groups in one molecule, and polyurethane (meth)acrylates obtained by adding a compound having one or more isocyanate groups in one molecule to the generated hydroxyl groups.

[0029] There are no particular limitations on the epoxy resin used; the same epoxy resin used in the epoxy (meth)acrylates described above can be used.

[0030] Compounds having one or more isocyanate groups in one molecule are not particularly limited, but can include: hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene diisocyanate (MDI), methylene dicyclohexyl isocyanate, trimethylhexamethylene diisocyanate, hexane diisocyanate, hexamethylamine diisocyanate, methylene dicyclohexyl isocyanate, toluene diisocyanate, 1,2-diphenylethane diisocyanate, 1,3-diphenylpropane diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate, etc. These compounds can be used alone or in combination of two or more.

[0031] This polyurethane (meth)acrylate does not have free carboxyl groups.

[0032] The weight-average molecular weight of component (A) is 500 or more, and from the viewpoint of further improving the ejectibility in inkjet printing, it is preferably 550 or more, and particularly preferably 1000 or more. On the other hand, there is no particular upper limit to the weight-average molecular weight of component (A), but from the viewpoint of reliably preventing the viscosity of the photosensitive resin composition from increasing and obtaining excellent coating properties even with inkjet printing, it is preferably 5000, and particularly preferably 4000 or less.

[0033] [Ingredient (B)]

[0034] In this embodiment, (B) (meth)acrylic acid compounds with a weight average molecular weight of less than 500 are acceptable as long as they are (meth)acrylic acid compounds with a weight average molecular weight of less than 500, and their chemical structures are not particularly limited.

[0035] Examples of component (B) include monofunctional (meth)acrylate monomers and (meth)acrylate monomers with two or more functions. By incorporating component (B) into the photosensitive resin composition of this embodiment, the viscosity of the photosensitive resin composition at 25°C is reduced. Therefore, it can be used for inkjet printing even without the addition of a non-reactive diluent (e.g., an organic solvent).

[0036] Furthermore, from the viewpoint of good compatibility with component (C) described later, component (B) preferably has a cyclic skeleton in one molecule. Examples of cyclic skeletons include benzene rings and alicyclic rings (isobornyl, cyclohexane ring, etc.). Among these, benzene rings are preferred.

[0037] The viscosity of component (B) at 25°C is not particularly limited. From the viewpoint of further improving the coating properties in inkjet printing and obtaining better anti-bleeding properties, it is preferably 1 mPa·s or more and 300 mPa·s or less, more preferably 2 mPa·s or more and 50 mPa·s or less, and particularly preferably 3 mPa·s or more and 20 mPa·s or less.

[0038] As component (B), examples include: monofunctional (meth)acrylate compounds, difunctional (meth)acrylate compounds, and (meth)acrylate compounds with three or more functions.

[0039] Examples of monofunctional (meth)acrylate compounds include: benzyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, phenoxyethyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0040] Examples of difunctional (meth)acrylate compounds include: 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, dicyclopentyl dimethacrylate, ethylene oxide-modified phosphate dimethacrylate, allylated cyclohexyl dimethacrylate, and isocyanurate dimethacrylate, etc.

[0041] Examples of (meth)acrylate compounds with three or more functions include: trimethylolpropane tri(meth)acrylate, di(trimethylolpropane)tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0042] These compounds can be used alone or in combination of two or more.

[0043] The amounts of components (A) and (B) in the photosensitive resin composition are not particularly limited. However, from the viewpoint of reliably imparting strength to the cured product of the photosensitive resin composition, the amount of component (A) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more, relative to 100 parts by mass of component (B). On the other hand, from the viewpoint of further improving the coatability in inkjet printing, the amount of component (A) is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less, relative to 100 parts by mass of component (B).

[0044] [Ingredient (C)]

[0045] The phosphorus-containing compound (C) used in this embodiment is a compound containing phosphorus atoms, is a compound other than a phosphate ester, and has functional groups in one molecule that can react through photoradical polymerization or photocationic polymerization. This component (C) imparts flame retardancy to the photosensitive resin composition. Furthermore, with this component (C), there is no adverse effect on electrical insulation and impermeability, nor on the coating properties in inkjet printing.

[0046] Functional groups that can react through photoradical polymerization or photocationic polymerization include: functional groups with unsaturated double bonds and functional groups with epoxy rings.

[0047] Examples of functional groups with unsaturated double bonds include vinyl, allyl, acryloyl, and methacryloyl. Acryloyl or methacryloyl is preferred.

[0048] Examples of functional groups containing an epoxy ring include glycidyl groups.

[0049] Component (C) is preferably a compound represented by the following general formula (C1).

[0050]

[0051] In formula (C1), X is a monovalent group having at least one group selected from vinyl, allyl, acryloyl, methacryloyl, and glycidyl. X is more preferably acryloyl, methacryloyl, or glycidyl.

[0052] Y is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms, which may optionally have substituents. Alternatively, these groups may optionally form a cyclic structure with a benzene ring bonded to phosphorus.

[0053] In addition, as the compound shown in (C1), the compounds shown in formulas (1) to (3) below can be listed.

[0054]

[0055] As component (C), examples include: phosphine oxides ((meth)acryloylmethyl diphenylphosphine oxide, and 2-(3,4-epoxycyclohexyl)ethyl diphenylphosphine oxide, etc.), compounds having a phosphenanthrene ring (10-(3-glycidyloxypropyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide (the compound shown in formula (2), and the compound shown in formula (3), etc.), 10-[2-(3,4-epoxycyclohexyl)ethyl]-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide, 10-(3-glycidyloxypropyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide, 9,10-dihydro-9-oxa-10-vinyl-10-phosphenanthrene-10-oxide, and phenylvinylphosphino acid, etc. From the viewpoint that a cured product with better impermeability can be obtained, the preferred compounds are methacryloylmethyl diphenylphosphine oxide (the compound shown in formula (1), 10-(3-glycidyloxypropyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (the compound shown in formula (2)) or the compound shown in formula (3).

[0056] These compounds can be used alone or in combination of two or more. From the perspective of balancing flame retardancy and other physical properties, it is preferable to use two or more in combination.

[0057] The amount of component (C) is not particularly limited, but it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more, relative to 100 parts by mass of component (B). As long as the amount of component (C) is at or above the above-mentioned lower limit, it is possible to reliably impart flame retardancy to the photosensitive resin composition. On the other hand, regarding the amount of component (C), from the viewpoint of imparting flexibility to the cured photosensitive resin composition so that it can be used on flexible substrates, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less, relative to 100 parts by mass of component (B).

[0058] [Ingredient (D)]

[0059] The photopolymerization initiator (D) used in this embodiment is not particularly limited, and any known photopolymerization initiator may be used appropriately. Examples of component (D) include: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-methyl-4'-(methylthio)-2-morpholinophenylacetone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-methyl-1-(4-methylthiophenyl)-2-... - Morpholinopropane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)one, benzophenone, p-phenylbenzophenone, 4,4'-bis(diethylamino)benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, and ethyl p-dimethylaminobenzoate, etc. These compounds can be used alone or in combination of two or more.

[0060] It should be noted that, from the viewpoint of preventing discoloration of the cured coating, component (D) preferably has phosphorus atoms in one molecule.

[0061] The amount of component (D) is not particularly limited, but is preferably 5 parts or more and 30 parts or less, and particularly preferably 10 parts or more and 20 parts or less, relative to 100 parts by mass of component (B).

[0062] [Ingredient (E)]

[0063] The photosensitive resin composition of this embodiment optionally further comprises (E) a dielylnadic imide compound. This component (E) can be used as a substitute for component (A).

[0064] Component (E) is preferably a compound represented by the following general formula (E1).

[0065]

[0066] In equation (E1), R 1 alkylene groups having 2 to 18 carbon atoms, -R 2 -phenylene-R 3 - or -phenylene-R4 -Phenylidene-. R 2 R 3 and R 4 Each can independently represent an alkylene group having 1 to 5 carbon atoms. R 1 Preferred is -R 2 -phenylene-R 3 - or -phenylene-R 4 -Phenylidene-. Additionally, R 2 R 3 and R 4 Preferably, each is an alkylene group having 1 to 3 carbon atoms.

[0067] Examples of compounds represented by formula (E1) include BANI-M(R) manufactured by Maruzen Petrochemical Co., Ltd. 1 (for -phenylene-methylene-phenylene-), and BANI-X(R) 1 (e.g., methylene-phenylene-methylene-). These compounds can be used alone or in combination of two or more.

[0068] When using component (E), there is no particular limitation on its amount, but it is preferably 5 parts or more and 35 parts or less, and particularly preferably 10 parts or more and 20 parts or less, relative to 100 parts by mass of component (B).

[0069] In the photosensitive resin composition of this embodiment, in addition to the components (A) to (E) described above, other components may be added as needed, such as colorants, various additives, and non-reactive diluents.

[0070] Pigments and colorants are examples of colorants, and there are no particular limitations. Furthermore, depending on the color imparted to the cured photosensitive resin composition, the colorant can be any color selected from white, blue, green, yellow, purple, and black colorants. Examples of colorants include: titanium dioxide as a white colorant, inorganic colorants such as carbon black as a black colorant, phthalocyanine green as a green colorant, phthalocyanine blue as a blue colorant, Cromophtal Yellow as a yellow colorant, and anthraquinone colorants. These colorants can be used alone or in mixtures of two or more.

[0071] Among various additives, examples include: defoamers (organosilicon defoamers, hydrocarbon defoamers, and acrylic defoamers), inorganic fillers (talc, barium sulfate, alumina, aluminum hydroxide, mica, and silica, etc.), and organic fillers (powdered urethane resins, (meth)acrylic polymers, vinyl polymers, carboxyl-containing polymer modifiers, and carboxylic esters, etc.). These additives can be used individually or in combination of two or more.

[0072] To adjust the viscosity and drying properties of the photosensitive resin composition, a non-reactive diluent is added as needed. Examples of non-reactive diluents include organic solvents. Examples of organic solvents include: ketones (e.g., methyl ethyl ketone, cyclohexanone), aromatic hydrocarbons (e.g., toluene, xylene), alcohols (e.g., methanol, isopropanol, cyclohexanol), alicyclic hydrocarbons (e.g., cyclohexane, methylcyclohexane), petroleum solvents (e.g., petroleum ether, petroleum naphtha), cellolytic agents (e.g., cellolytic agents, butyl cellolytic agents), carbitols (e.g., carbitol, butyl carbitol), and esters (e.g., ethyl acetate, butyl acetate, ethyl acetate cellolytic agent, butyl acetate cellolytic agent, carbitol acetate, butyl carbitol acetate, diethylene glycol ethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate), etc. These solvents can be used alone or in mixtures of two or more.

[0073] The method for manufacturing the photosensitive resin composition of this embodiment is not limited to a specific method. For example, after combining the above-mentioned components in a given ratio, the composition can be manufactured by mixing or blending at room temperature using a mixing apparatus such as a three-roll mill, ball mill, bead mill, or sand mill, or a stirring apparatus such as a super mixer or planetary mixer. In addition, pre-mixing or pre-blending can be performed as needed before the above-mentioned mixing or blending.

[0074] Next, examples of the use of the photosensitive resin composition of this embodiment will be described. The photosensitive resin composition of this embodiment can be used to form cured materials (e.g., solder resist film and markings, etc.) on a substrate (e.g., a printed wiring substrate having a given circuit pattern) using inkjet printing.

[0075] Printed wiring substrate

[0076] Next, the printed wiring substrate of this embodiment will be described.

[0077] The printed wiring substrate of this embodiment includes a solder resist film formed from the photosensitive resin composition of this embodiment described above. Furthermore, the printed wiring substrate of this embodiment can be manufactured as described below.

[0078] First, the photosensitive resin composition of this embodiment is applied to a printed wiring substrate in a desired pattern using an inkjet method (e.g., an inkjet method using a jet dispenser). After application, the coating is photocured using laser direct patterning (LDI) or active energy rays such as ultraviolet light. It should be noted that when photocuring is performed using active energy rays such as ultraviolet light, the irradiation intensity is, for example, 100–2000 mJ / cm². 2 Within the range. After photocuring of the coating, post-curing (thermal curing) is performed for 20 to 80 minutes using a hot air circulating dryer at 130 to 170°C, thereby forming a solder resist film with a desired pattern on the printed wiring substrate.

[0079] Example

[0080] The present invention will be further described in detail below through examples and comparative examples, but the present invention is not limited to these examples in any way.

[0081] (ingredient (A))

[0082] Epoxy acrylate A: Functional group number 2, weight average molecular weight 1500, trade name "EBECRYL 3708", manufactured by DAICEL-CYTEC.

[0083] Epoxy acrylate B: Functional group number 2, weight average molecular weight 520, trade name "Miramer PE210", manufactured by Miwon.

[0084] Epoxy acrylate C: Functional group number 2, weight average molecular weight 550, trade name "Miramer PE250", manufactured by Miwon.

[0085] Epoxy acrylate D: Functional group number 2, weight average molecular weight 850, trade name "EBECRYL 3703", manufactured by DAICEL-CYTEC.

[0086] Polyurethane acrylate A: 4 functional groups, weight average molecular weight 2700, trade name "EBECRYL 8405", manufactured by DAICEL-CYTEC.

[0087] Polyurethane acrylate B: Functional group number 2, weight average molecular weight 1000, trade name "EBECRYL 8402", manufactured by DAICEL-CYTEC.

[0088] Polyurethane acrylate C: Functional group number 2, weight average molecular weight 2600, trade name "Miramer PU210", manufactured by Miwon.

[0089] (Component (E))

[0090] Diallyl nadic diimide compound: trade name "BANI-M", manufactured by Maruzen Petrochemical Co., Ltd.

[0091] (Ingredient (B))

[0092] (Meth)acrylic acid compound A: benzyl acrylate, functional group number 1, viscosity 3-8 mPa·s, trade name "Viscoat #160", manufactured by Osaka Organic Chemicals Co., Ltd.

[0093] (Meth)acrylic acid compound B: 1,4-Butanediol dimethacrylate, functional group number 2, viscosity 5 mPa·s, trade name "Light Ester 1,4BG", manufactured by Kyoei Chemical Co., Ltd.

[0094] (Meth)acrylic acid compound C: polypropylene glycol diacrylate, functional group number 2, viscosity 8-16 mPa·s, trade name "ARONIX M-220", manufactured by Toa Sangyo Co., Ltd.

[0095] (Meth)acrylate compound D: 1,6-hexanediol diacrylate, functional group number 2, viscosity 7 mPa·s, trade name "HDDA", manufactured by DAICL-CYTEC.

[0096] (Meth)acrylic acid compound E: diethylene glycol dimethacrylate, functional group number 2, viscosity 2 mPa·s, trade name "Light Ester 2EG", manufactured by Kyoei Chemical Co., Ltd.

[0097] (Meth)acrylic acid compound F: Tetrahydrofurfuryl acrylate, functional group number 1, viscosity 3 mPa·s, trade name "Viscoat #150", manufactured by Osaka Organic Chemicals Co., Ltd.

[0098] (Meth)acrylate compound G: isobornyl acrylate, functional group number 1, viscosity 8 mPa·s, trade name "IBXA", manufactured by Osaka Organic Chemicals Co., Ltd.

[0099] (Meth)acrylic acid compound H: phenolic acrylate, functional group number 1, viscosity 8–20 mPa·s, trade name "Miramer M140", manufactured by Miwon.

[0100] (Ingredient (C))

[0101] Phosphorus-containing compound A: Methacryloxymethyl diphenylphosphine oxide (the compound shown in formula (1)), trade name "MC-4", manufactured by Katayama Chemical Industry Co., Ltd.

[0102] Phosphorus-containing compound B: 10-(3-glycidyloxypropyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (the compound shown in formula (2)), trade name "E-10g", manufactured by Katayama Chemical Industry Co., Ltd.

[0103] Phosphorus-containing compound C: The compound shown in formula (3), trade name "FRM-1000", manufactured by Nippon Kayaku Co., Ltd.

[0104] (Other ingredients)

[0105] Phosphorus compound D: Phosphinate metal salt, trade name "OP-935", manufactured by Clariant.

[0106] Phosphorus-containing compound E: Phosphazene derivative, trade name "FP-110", manufactured by Sanko Co., Ltd.

[0107] Phosphorus compound F: bis(2-methacryloyloxyethyl) phosphate, trade name "PM-2", manufactured by Nippon Kayaku Co., Ltd.

[0108] Phosphorus compound G: Triphenyl phosphate, trade name "TPP", manufactured by Daihachi Chemical Industry Co., Ltd.

[0109] (Ingredient (D))

[0110] Photopolymerization initiator A: 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one, trade name "IRGACURE 907", manufactured by BASF.

[0111] Photopolymerization initiator B: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, trade name "IRGACURE 369E", manufactured by BASF.

[0112] Photopolymerization initiator C: 2,4,6-trimethylbenzoyl diphenylphosphine oxide, trade name "LUCIRIN TPO", manufactured by BASF.

[0113] Photopolymerization initiator D: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, trade name "IRGACURE 819", manufactured by BASF.

[0114] Photopolymerization initiator E: Diethylthioxanthone, trade name "Chemcure DETX", manufactured by Chembridge International.

[0115] (Other ingredients)

[0116] Pigment A: Trade name "LIONOL BLUE FG-7351", manufactured by TOYOCOLOR.

[0117] Coloring Pigment B: Trade name "Cromophtal Yellow AGR", manufactured by Ciba Specialty Chemicals.

[0118] Additive A: Trade name "FLOWLEN G-700", manufactured by Kyoei Chemical Co., Ltd.

[0119] Additive B: Trade name "UVX-189", manufactured by Kusumoto Chemical Co., Ltd.

[0120] Additive C: Trade name "BYK-361N", manufactured by BYK-Chemie Japan Co., Ltd.

[0121] Additive D: Trade name "BYK-168", manufactured by BYK-Chemie Japan. Organic solvent: Diethylene glycol monoethyl ether acetate, trade name "EDGAC", manufactured by Kamikō Organic Chemicals Co., Ltd.

[0122] [Example 1]

[0123] 15 parts by weight of epoxy acrylate A, 73 parts by weight of (meth)acrylic acid compound A, 20 parts by weight of phosphorus-containing compound A, 5 parts by weight of photopolymerization initiator A, 5 parts by weight of photopolymerization initiator C, 1 part by weight of coloring pigment A, and 1 part by weight of coloring pigment B were added to a container, premixed using a stirrer, and then dispersed using a three-roll mill at room temperature to obtain a photosensitive resin composition for inkjet printing.

[0124] [Examples 2-12]

[0125] Except that the materials were formulated according to the composition shown in Table 1, the same photosensitive resin composition for inkjet printing was obtained as in Example 1.

[0126] [Examples 13-24]

[0127] Except that the materials were formulated according to the composition shown in Table 2, the same photosensitive resin composition for inkjet printing was obtained as in Example 1.

[0128] [Examples 25 and 26]

[0129] Except that the materials were formulated according to the composition shown in Table 3, the same photosensitive resin composition for inkjet printing was obtained as in Example 1.

[0130] [Comparative Examples 1-5]

[0131] Except that the materials were formulated according to the composition shown in Table 4, the same photosensitive resin composition for inkjet printing was obtained as in Example 1.

[0132] <Evaluation of Photosensitive Resin Compositions for Inkjet Printing>

[0133] The following methods were used to evaluate the photosensitive resin compositions for inkjet printing (coating properties, adhesion, flame retardancy, electrical insulation, and anti-bleeding properties). The results are shown in Tables 1 to 4.

[0134] It should be noted that the test subject manufacturing process is as follows.

[0135] (Test subject manufacturing process)

[0136] Substrate: Copper foil laminate (1.6mm thick)

[0137] Surface treatment: scrubbing and polishing

[0138] Printing method: Inkjet printing (Inkjet device: "MJP2013F1-DU", Microcraft Company)

[0139] DRY film thickness: 20–23 μm

[0140] Exposure: 1000 mJ / cm on the coating 2 EYEGRAPHICS company "UB093-5AM"

[0141] Post-curing: Curing at 150°C for 60 minutes in a BOX-type drying oven.

[0142] (1) Coating properties

[0143] Using the inkjet device described above, a 100×100 dot pattern is coated. The coated substrate is then observed using a magnifying glass (30x) to confirm whether the coating is identical to the pattern. It should be noted that if the coating is identical to the pattern, it is judged as "B"; if there are problems such as failure to spray, it is judged as "D".

[0144] (2) Fit

[0145] For the test specimens produced in the above test specimen manufacturing process, the adhesion to copper was evaluated according to JIS K 5400, and the evaluation was carried out based on the remaining number of checkerboard squares as follows.

[0146] A: 100 / 100

[0147] B: 70 / 100~99 / 100

[0148] C: 10 / 100~69 / 100

[0149] D: 0 / 100~9 / 100

[0150] (3) Flame retardancy

[0151] Except for changing the substrate from a copper foil laminate to a 25μm thick polyimide substrate, the test body was fabricated according to the above-mentioned process, with a DRY film thickness of 20μm applied to both sides to form a cured coating, and then evaluated according to the UL94VTM test standard.

[0152] (4) Electrical insulation

[0153] Except for changing the substrate from a copper foil laminate to a comb-shaped test pattern (100μm line width and 100μm line spacing), a cured coating was formed according to the above test body manufacturing process. A 30V DC current was applied in a gas atmosphere with a temperature of 85°C and a humidity of 85%, and the test body was left to stand for 100 hours. Then the test body was taken out of the tank and the insulation resistance value was measured.

[0154] (5) Impermeability

[0155] For the test specimens produced in the above test specimen manufacturing process, the exudation from the test specimens after being pressed at 150°C, 3MPa, and for 300 seconds was observed with the naked eye and with a magnifying glass (30x), and the evaluation was carried out as follows.

[0156] A: After pressing, there was no exudate that could be identified with a magnifying glass.

[0157] B: After pressing, there is exudate that can be identified with a magnifying glass.

[0158] C: After compression, there is exudate that can be observed and identified with the naked eye.

[0159] D: There was exudation after the test subject was made.

[0160] [Table 1]

[0161]

[0162] [Table 2]

[0163]

[0164] [Table 3]

[0165]

[0166] [Table 4]

[0167]

[0168] As shown in Tables 1 to 4, when the inkjet photosensitive resin composition of the present invention was used (Examples 1 to 26), the results for coatability, adhesion, flame retardancy, electrical insulation, and anti-bleeding properties were all excellent. Therefore, the inkjet photosensitive resin composition of the present invention has demonstrated excellent coatability in inkjet printing and can form a cured product with excellent electrical insulation, flame retardancy, and anti-bleeding properties.

[0169] In contrast, it can be seen that when using inkjet photosensitive resin compositions that do not contain component (C) of the present invention (Comparative Examples 1-5), at least one of coating properties, flame retardancy, electrical insulation, and anti-bleeding properties is problematic.

Claims

1. A photosensitive resin composition for inkjet printing, comprising (A) a (meth)acrylic resin with a weight-average molecular weight of 500 or more, (B) a (meth)acrylic compound with a weight-average molecular weight of less than 500, (C) a phosphorus-containing compound, and (D) a photopolymerization initiator, wherein the photosensitive resin composition does not contain phosphate esters, wherein, The component (A) is selected from at least one of epoxy (meth)acrylates and polyurethane (meth)acrylates. The component (C) is a compound other than a phosphate ester, and has functional groups in one molecule that can react via photoradical polymerization or photocationic polymerization. The component (C) is selected from at least one of the compounds shown in formulas (1) and (2) below.

2. The photosensitive resin composition for inkjet printing according to claim 1, wherein, Two or more of the ingredients (C) may be used in combination.

3. The photosensitive resin composition for inkjet printing according to claim 1, wherein, The weight-average molecular weight of component (A) is 500 or more and 4000 or less. The viscosity of component (B) at 25°C is greater than 1 mPa·s and less than 300 mPa·s.

4. The photosensitive resin composition for inkjet printing according to claim 1, wherein, The component (B) has a cyclic skeleton in one molecule.

5. The photosensitive resin composition for inkjet printing according to claim 1, wherein, The component (B) is selected from at least one of monofunctional (meth)acrylate compounds and difunctional (meth)acrylate compounds.

6. The photosensitive resin composition for inkjet printing according to any one of claims 1 to 5, wherein, The amount of component (A) is 5 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of component (B). The amount of component (C) is 5 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of component (B). The amount of component (D) is 5 or more and 30 or less, relative to 100 parts by mass of component (B).

7. The inkjet photosensitive resin composition according to claim 1, further comprising (E) dielyl nadic diimide compound.

8. A printed wiring substrate comprising a solder resist film formed from any one of claims 1 to 7 of the inkjet photosensitive resin composition.

9. A method for manufacturing a printed wiring substrate, the method comprising: The process of applying the inkjet photosensitive resin composition of any one of claims 1 to 7 onto a printed wiring substrate in a desired pattern using an inkjet method.

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