Inkjet solder resist composition, cured product, and printed wiring board

Abstract

To provide an inkjet solder resist composition for securing good fluidity while reducing an amount of a volatile organic compound inevitably generated from a solder resist composition during printing, in a solder resist composition (solder resist ink) capable of printing by an inkjet method.SOLUTION: An inkjet solder resist composition includes an acrylic monomer, where the acrylic monomer includes an acrylic monomer having a boiling point of 200°C or higher, the volatile organic compound at 50°C in the inkjet solder resist composition is 500 ppmC or less, and the viscosity at 50°C of the inkjet solder resist composition is 15 mPa s or lower.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an inkjet solder resist composition, in particular to an inkjet solder resist composition that is a curable composition having suitable viscosity. The present invention also relates to a cured product obtained by curing the inkjet solder resist composition and a printed wiring board formed using the cured product. [Background technology]

[0002] In the manufacture of printed wiring boards, solder resist compositions (solder resist inks) that can be printed by the inkjet method have been attracting attention from the viewpoints of process workability, waste liquid treatment, etc. Compared to the formation of resist patterns by conventional screen printing methods, the inkjet method does not require plate making and can reduce the number of steps, and can reduce the amounts of developer, cleaning solution, and high molecular weight photosensitive resin used. For this reason, the inkjet method is advantageous in terms of improving production efficiency and reducing the burden of waste liquid treatment (see Patent Documents 1, 2, 3, etc.).

[0003] Due to the advantages of the inkjet method described above, there is an increasing demand for solder resist compositions that can be printed by the inkjet method. A piezoelectric element is used in an inkjet solder resist composition ejection device. In order to stably eject the solder resist composition from the piezoelectric element, it is necessary to ensure the fluidity of the solder resist composition within the pores. For this reason, the solder resist composition is heated within the device.

[0004] As mentioned above, heating of the inkjet solder resist composition is unavoidable, and the volatilization of the acrylic monomer, which is a component of the solder resist composition, from the nozzle of the head of the discharge device when the solder resist composition is heated is considered to be a problem. There is a demand for a solution to the deterioration of the working environment caused by volatile organic compounds (VOCs) resulting from the acrylic monomer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-147970 A [Patent Document 2] JP 2012-092312 A [Patent Document 3] JP 2012-087298 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned points, and provides an inkjet solder resist composition that can be printed by an inkjet method, which ensures good flowability while reducing the amount of volatile organic compounds that are inevitably generated from the solder resist composition during printing. [Means for solving the problem]

[0007] That is, an embodiment is an inkjet solder resist composition containing an acrylic monomer, the acrylic monomer having a boiling point of 200°C or more, the inkjet solder resist composition having a volatile organic compound content of 500 ppmC or less at 50°C, and the inkjet solder resist composition having a viscosity of 15 mPa s or less at 50°C.

[0008] Furthermore, the acrylic monomer may further contain an acrylic monomer having a boiling point of 100°C or higher and lower than 200°C.

[0009] Furthermore, the acrylic monomer may further contain an acrylic monomer having a boiling point of 300° C. or higher.

[0010] Furthermore, the total parts by mass of the acrylic monomers having a boiling point of 300° C. or higher may be 30 parts by mass or more, based on 100 parts by mass of the total acrylic monomers in the inkjet solder resist composition.

[0011] The cured product is characterized by being obtained by curing the inkjet solder resist composition, and the printed wiring board is characterized by comprising a cured product of the inkjet solder resist composition. Effect of the Invention

[0012] According to the inkjet solder resist composition of the present invention, the inkjet solder resist composition contains an acrylic monomer having a boiling point of 200° C. or higher, the inkjet solder resist composition contains no more than 500 ppmC of volatile organic compounds at 50° C., and the inkjet solder resist composition has a viscosity of no more than 15 mPa s at 50° C., so that the amount of volatile organic compounds inevitably generated from the solder resist composition during printing can be reduced while ensuring good flowability. Furthermore, in a printed wiring board comprising a cured product of the inkjet solder resist composition of the present invention, the amount of volatile organic compounds during production can be reduced, reducing the burden on the working environment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The inkjet solder resist composition of the embodiment is a solder resist composition that can be printed by an inkjet method, i.e., a so-called ink compatible with inkjet printing to be applied to a printed wiring board. It is a homogenized liquid containing an acrylic monomer and a thermosetting component, a coloring agent component, etc. In preparing the inkjet solder resist composition, the acrylic monomer as the main component, the thermosetting component, the coloring agent component, etc. are weighed out in a predetermined blending ratio, and are stirred and mixed by a known ink manufacturing method.

[0014] [(A) Acrylic monomer] The acrylic monomer is a monomer having an ethylenically unsaturated double bond, and for example, a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate can be used. As the polyfunctional (meth)acrylate, a bifunctional (meth)acrylate and a trifunctional or higher (meth)acrylate can be used. In this specification, the acrylic monomer is a general term for acrylate, methacrylate and a mixture thereof, and the same applies to other similar expressions. The acrylic monomer may be used alone or in combination of two or more kinds. In particular, it is preferable to use two or more kinds in combination for the convenience of blending acrylic monomers with different boiling points.

[0015] Examples of monofunctional (meth)acrylates include (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and glycidyl methacrylate; and acryloylmorpholine.

[0016] Examples of bifunctional (meth)acrylates include diol diacrylates such as 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and 1,10-decanediol diacrylate; ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol diacrylate, and diol diacrylates obtained by adding at least one of ethylene oxide and propylene oxide to neopentyl glycol; glycol diacrylates such as caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate; bisphenol A EO adduct diacrylate; and bisphenol A. Examples of the diacrylate include diacrylates having a cyclic structure such as PO adduct diacrylate, tricyclodecane dimethanol diacrylate, hydrogenated dicyclopentadienyl diacrylate, and cyclohexyl diacrylate.

[0017] Examples of the trifunctional or higher (meth)acrylate include trimethylolpropane triacrylate, trimethylolmethane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate, epichlorohydrin-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, tetramethylolmethane tetraacrylate, ethylene oxide-modified phosphate triacrylate, propylene oxide-modified phosphate triacrylate, epichlorohydrin-modified glycerol triacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, and polyfunctional acrylates such as silsesquioxane-modified products thereof, or methacrylate monomers corresponding thereto, and ε-caprolactone-modified trisacryloxyethyl isocyanurate.

[0018] When preparing the inkjet solder resist composition of the embodiment, the boiling point of the acrylic monomer (acrylate, methacrylate) itself to be blended, the viscosity (fluidity) in the temperature range, the kneadability with other components, the durability, etc. are taken into consideration. In particular, it is desired to reduce the amount of volatile organic compounds (VOCs). Therefore, it is effective and efficient to select the type of acrylic monomer based on the boiling point of the acrylic monomer.

[0019] Specifically, from among the acrylic monomers (acrylates, methacrylates) listed above, it is desirable to use an acrylic monomer having a boiling point of 200° C. or higher, and it is more desirable to use in combination an acrylic monomer having a boiling point of 200° C. or higher and an acrylic monomer having a boiling point of 100° C. or higher and lower than 200° C. Furthermore, it is more preferable to use in combination an acrylic monomer having a boiling point of 200° C. or higher, an acrylic monomer having a boiling point of 100° C. or higher and lower than 200° C., and an acrylic monomer having a boiling point of 300° C. or higher.

[0020] By increasing the amount of acrylic monomers with a boiling point of 200°C or higher in the inkjet solder resist composition, the volatilization of organic components caused by heating during printing can be suppressed. Of course, if the composition is too concentrated with acrylic monomers with a boiling point of 200°C or higher, there is a risk of poor fluidity and clogging inside the nozzle, so to adjust for this, acrylic monomers with boiling points of 100°C or higher and less than 200°C are blended.

[0021] In the examples described later, 4-hydroxybutyl acrylate is used as the acrylic monomer having a boiling point of 200° C. or more, dipropylene glycol diacrylate (manufactured by Daicel-Allnex Corporation) and 6-hexanediol diacrylate are used as the acrylic monomer having a boiling point of 100° C. or more and less than 200° C., and ethoxylated bisphenol A diacrylate and nonanediol diacrylate are used as the acrylic monomer having a boiling point of 300° C. or more. Of course, the type of acrylic monomer used in the inkjet solder resist composition is not limited to the compositions in the examples.

[0022] Regarding the acrylic monomers (acrylate, methacrylate) blended in the inkjet solder resist composition of the embodiment, the total parts by mass of the acrylic monomers having a boiling point of 300°C or more is 30 parts by mass or more, preferably 40 parts by mass or more, and more preferably 45 parts by mass or more, relative to 100 parts by mass of the total acrylic monomers in the inkjet solder resist composition.

[0023] [(B) Photopolymerization initiator] The photopolymerization initiator is a compound that reacts with the acrylic monomer by exposure to light (ultraviolet light irradiation) to polymerize it. The photopolymerization initiator may be used alone or in combination of two or more kinds.

[0024] Examples of the photopolymerization initiator include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. phosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and other bisacylphosphine oxides; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphine acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenyl Isopropyl phosphinate, monoacylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxycyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one , hydroxyacetophenones such as 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzoins such as benzoin, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone;Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone, N,N-dimethyla acetophenones such as aminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; Ketals such as cetophenone dimethyl ketal and benzil dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoic acid ethyl ester; oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, and 1-(O-acetyloxime); bis(η5-2,4-cyclopentadiene-1-yl) Titanocenes such as bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrrol-1-yl)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrrol-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, etc.;

[0025] Commercially available α-aminoacetophenone photopolymerization initiators include Omnirad 907, 369, 369E, and 379 manufactured by IGM Resins. Commercially available acylphosphine oxide photopolymerization initiators include Omnirad TPO H and 819 manufactured by IGM Resins. Commercially available oxime ester photopolymerization initiators include Irgacure OXE01 and OXE02 manufactured by BASF Japan Ltd., N-1919 manufactured by ADEKA Corporation, ADEKA Arcles NCI-831 and NCI-831E, and TR-PBG-304 manufactured by Changzhou Strong Electronic New Materials Co., Ltd.

[0026] Other examples include carbazole oxime ester compounds described in JP-A-2004-359639, JP-A-2005-097141, JP-A-2005-220097, JP-A-2006-160634, JP-A-2008-094770, JP-T-2008-509967, JP-T-2009-040762, and JP-T-2011-80036.

[0027] The amount of the photopolymerization initiator is necessary and sufficient to promote the reaction of the acrylic monomer. The relative amount of the photopolymerization initiator in 100 parts by mass of the inkjet solder resist composition is 3 to 10 parts by mass. The amount of the photopolymerization initiator can be adjusted depending on the composition of the photopolymerization initiator, the type of the acrylic monomer, the reaction conditions, etc.

[0028] A photoinitiator assistant or sensitizer may be used in combination with the above-mentioned photopolymerization initiator. Examples of the photoinitiator assistant or sensitizer include benzoin compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. In particular, it is preferable to use thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. By including a thioxanthone compound, it is possible to improve the deep curing property. These compounds can be used as photopolymerization initiators. In particular, it is preferable to use them in combination with a photopolymerization initiator. In addition, the photoinitiator assistant or sensitizer may be used alone or in combination of two or more kinds.

[0029] [(C) Thermosetting component] The heat resistance of the cured film is improved by including a thermosetting component in the inkjet solder resist composition. As the thermosetting component, for example, an amino resin such as a melamine resin, a benzoguanamine resin, a melamine derivative, or a benzoguanamine derivative, an isocyanate compound, a blocked isocyanate compound, a cyclocarbonate compound, an epoxy compound, an oxetane compound, an episulfide resin, a bismaleimide, or a carbodiimide resin is used. A preferred component is a thermosetting component having a plurality of cyclic ether groups or cyclic thioether groups (hereinafter, cyclic ether groups and cyclic thioether groups are abbreviated as cyclic (thio)ether groups) in the molecule. The thermosetting component may be one type alone or two or more types in combination.

[0030] The thermosetting component having multiple cyclic (thio)ether groups in the molecule is a compound having multiple 3-, 4-, or 5-membered cyclic (thio)ether groups in the molecule, and examples thereof include compounds having multiple epoxy groups in the molecule, i.e., polyfunctional epoxy compounds, compounds having multiple oxetanyl groups in the molecule, i.e., polyfunctional oxetane compounds, and compounds having multiple thioether groups in the molecule, i.e., episulfide resins.

[0031] Examples of such epoxy compounds include bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, and the like.

[0032] Other examples include epoxy acrylate resins obtained by reacting acrylic acid with a polyfunctional epoxy resin such as a cresol novolac epoxy resin, and epoxy urethane acrylate compounds obtained by reacting a half urethane compound of a hydroxy acrylate such as pentaerythritol triacrylate and a diisocyanate such as isophorone diisocyanate with a hydroxy group of the epoxy acrylate resin.

[0033] Examples of commercially available epoxy resins include jER 828, 806, 807, YX8000, YX8034, and 834 manufactured by Mitsubishi Chemical Corporation; YD-128, YDF-170, ZX-1059, and ST-3000 manufactured by Nippon Steel Chemical & Material Co., Ltd.; EPICLON 830, 835, 840, 850, N-730A, and N-695 manufactured by DIC Corporation; and RE-306 manufactured by Nippon Kayaku Co., Ltd.

[0034] Examples of polyfunctional oxetane compounds include bis[(3-methyl-3-oxetanylmethoxy)methyl]ether, bis[(3-ethyl-3-oxetanylmethoxy)methyl]ether, 1,4-bis[(3-methyl-3-oxetanylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, (3-methyl-3-oxetanyl)methyl acrylate, (3-ethyl-3-oxetanyl)methyl acrylate, and (3-ethyl-3-oxetanyl)methyl acrylate. Examples of the oxetanes include polyfunctional oxetanes such as acrylate, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, and their oligomers or copolymers, as well as ethers of oxetane alcohols and novolac resins, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, calixresorcinarenes, or silsesquioxanes or other resins having hydroxyl groups. Other examples include copolymers of unsaturated monomers having an oxetane ring and alkyl (meth)acrylates.

[0035] An example of a compound having multiple cyclic thioether groups in the molecule is bisphenol A type episulfide resin. In addition, episulfide resins in which the oxygen atoms of the epoxy groups of novolac type epoxy resins are replaced with sulfur atoms using a similar synthesis method can also be used.

[0036] Examples of amino resins such as melamine derivatives and benzoguanamine derivatives include methylolmelamine compounds, methylolbenzoguanamine compounds, methylolglycoluril compounds, and methylolurea compounds.

[0037] Polyisocyanate compounds can be blended as the isocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, and 2,4-tolylene dimer; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate) and isophorone diisocyanate; alicyclic polyisocyanates such as bicycloheptane triisocyanate; and adducts, biuret bodies, and isocyanurates of the above-mentioned isocyanate compounds.

[0038] The blocked isocyanate compound may be an addition reaction product of an isocyanate compound and an isocyanate blocking agent. Examples of isocyanate compounds that can react with an isocyanate blocking agent include the above-mentioned polyisocyanate compounds. Examples of isocyanate blocking agents include phenol-based blocking agents, lactam-based blocking agents, active methylene-based blocking agents, alcohol-based blocking agents, oxime-based blocking agents, mercaptan-based blocking agents, acid amide-based blocking agents, imide-based blocking agents, amine-based blocking agents, imidazole-based blocking agents, and imine-based blocking agents.

[0039] The amount of the thermosetting component is necessary and sufficient for curing the inkjet solder resist composition. The relative amount of the thermosetting component in 100 parts by mass of the inkjet solder resist composition is 5 to 15 parts by mass, preferably 8 to 12 parts by mass. The amount of the thermosetting component can be adjusted depending on the composition of the thermosetting component, the type of acrylic monomer, reaction conditions, etc.

[0040] [(E) Colorant] A colorant is blended in the inkjet solder resist composition of the embodiment. As the colorant, a known colorant such as red, blue, green, yellow, etc. can be used, and any of a pigment, dye, and coloring matter can be used. From the viewpoint of reducing the environmental load and the influence on the human body, it is preferable that the colorant does not contain halogen.

[0041] Red colorants include monoazos, disazos, azo lakes, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azos, anthraquinones, and quinacridones. Specific examples of red colorants include those having the following Color Index (CI; published by The Society of Dyers and Colourists) numbers:

[0042] Examples of monoazo red colorants include Pigment Red 1, 2, 3, 4, 5, 6, 8, 9, 12, 14, 15, 16, 17, 21, 22, 23, 31, 32, 112, 114, 146, 147, 151, 170, 184, 187, 188, 193, 210, 245, 253, 258, 266, 267, 268, and 269. Examples of disazo red colorants include Pigment Red 37, 38, and 41. In addition, examples of monoazo lake-based red colorants include Pigment Red 48:1, 48:2, 48:3, 48:4, 49:1, 49:2, 50:1, 52:1, 52:2, 53:1, 53:2, 57:1, 58:4, 63:1, 63:2, 64:1, and 68. In addition, examples of benzimidazolone-based red colorants include Pigment Red 171, 175, 176, 185, and 208. Examples of perylene-based red colorants include Solvent Red 135, 179, Pigment Red 123, 149, 166, 178, 179, 190, 194, and 224. Examples of diketopyrrolopyrrole-based red colorants include Pigment Red 254, 255, 264, 270, and 272. Condensed azo-based red colorants include Pigment Red 220, 144, 166, 214, 220, 221, and 242. Anthraquinone-based red colorants include Pigment Red 168, 177, and 216, Solvent Red 149, 150, 52, and 207. Quinacridone-based red colorants include Pigment Red 122, 202, 206, 207, and 209.

[0043] Blue colorants include phthalocyanine and anthraquinone types, and examples of pigment types include compounds classified as pigments, such as Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, and 60, and examples of dye types include Solvent Blue 35, 63, 68, 70, 83, 87, 94, 97, 122, 136, 67, and 70. In addition to the above, metal-substituted or unsubstituted phthalocyanine compounds can also be used.

[0044] Yellow colorants include monoazo, disazo, condensed azo, benzimidazolone, isoindolinone, anthraquinone, etc. For example, anthraquinone yellow colorants include Solvent Yellow 163, Pigment Yellow 24, 108, 193, 147, 199, 202, etc. Isoindolinone yellow colorants include Pigment Yellow 110, 109, 139, 179, 185, etc. Condensed azo yellow colorants include Pigment Yellow 93, 94, 95, 128, 155, 166, 180, etc. Benzimidazolone yellow colorants include Pigment Yellow 120, 151, 154, 156, 175, 181, etc. Examples of monoazo yellow colorants include Pigment Yellow 1, 2, 3, 4, 5, 6, 9, 10, 12, 61, 62, 62:1, 65, 73, 74, 75, 97, 100, 104, 105, 111, 116, 167, 168, 169, 182, and 183. Examples of disazo yellow colorants include Pigment Yellow 12, 13, 14, 16, 17, 55, 63, 81, 83, 87, 126, 127, 152, 170, 172, 174, 176, 188, and 198.

[0045] In addition, colorants such as purple, orange, brown, black, and white may be added as necessary.Specific examples include Pigment Black 1, 6, 7, 8, 9, 10, 11, 12, 13, 18, 20, 25, 26, 28, 29, 30, 31, and 32, Pigment Violet 19, 23, 29, 32, 36, 38, 42, Solvent Violet 13 and 36, CI Pigment Orange 1, 5, 13, 14, 16, 17, 24, 34, 36, 38, 40, 43, 46, 49, 51, 61, 63, 64, 71, and 73, Pigment Brown 23 and 25, carbon black, and titanium oxide.

[0046] The amount of the colorant is not particularly limited, and is a necessary and sufficient amount for coloring the inkjet solder resist composition. The relative amount of the colorant in 100 parts by mass of the inkjet solder resist composition is 0.2 to 2 parts by mass, preferably 0.3 to 1 part by mass. The amount of the colorant can be adjusted depending on the coloring strength of the colorant itself, dispersibility in the acrylic monomer, etc.

[0047] [Other added ingredients] The inkjet solder resist composition of the embodiment may contain, as necessary, components such as organic solvents, photoinitiator assistants, cyanate compounds, elastomers, mercapto compounds, urethanization catalysts, thixotropic agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, antioxidants, surface tension regulators, rust inhibitors, thickeners such as fine silica, organic bentonite, and montmorillonite, antifoaming agents and / or leveling agents such as silicone-based, fluorine-based, and polymer-based agents, silane coupling agents such as imidazole-based, thiazole-based, and triazole-based agents, and flame retardants such as phosphorus compounds such as phosphinates, phosphate ester derivatives, and phosphazene compounds. These may be known in the field of electronic materials.

[0048] [Physical properties (viscosity)] The inkjet solder resist composition of the embodiment preferably has a viscosity that takes into consideration the flowability in a discharge device for inkjet printing, the flying properties of the ink particles, and the adhesion to a printed wiring board after application. The viscosity of the inkjet solder resist composition at 50°C is preferably 20 mPa·s or less, and more preferably 15 mPa·s or less. The viscosity of the inkjet solder resist complies with JIS Z 8803:2011, Section 10 "Method of measuring viscosity using a cone-plate rotational viscometer". Detailed conditions will be described in the examples below.

[0049] [Physical properties (volatile organic compounds (VOCs))] The inkjet solder resist composition of the embodiment has been developed with the aim of suppressing the generation of volatile organic compounds due to heating during inkjet printing on a printed wiring board. Therefore, the amount of volatile organic compounds generated from the inkjet solder resist composition is evaluated. Specifically, the amount of volatile organic compounds is converted into the amount of carbon in a sample of the inkjet solder resist composition and detected using a flame ionization detector (FID). The amount of carbon is then measured as total volatile organic compounds (T-VOC: Total Volatile Organic Compounds (unit: ppmC)). As shown in the examples below, the amount of volatile organic compounds in the inkjet solder resist composition at 50°C is 500 ppmC or less, preferably 400 ppmC or less.

[0050] [Application] The inkjet solder resist composition of the embodiment is useful for forming a pattern layer as a permanent coating of a printed wiring board such as a solder resist, a coverlay, an interlayer insulating layer, etc., and is particularly useful for forming a solder resist. In addition, since the inkjet solder resist composition of the present invention has heat resistance, it is also useful as a marking ink or the like that requires heat resistance.

[0051] [Cured product] The cured product of the inkjet solder resist composition of the embodiment is obtained by curing the inkjet solder resist composition by inkjet printing using an inkjet printer. The cured product of the inkjet solder resist composition is generated by photocuring after being irradiated with light immediately after printing. The light irradiation is irradiation with active energy rays such as ultraviolet rays, electron beams, and chemical rays, and is preferably ultraviolet irradiation. In the ultraviolet irradiation in the inkjet printer, for example, a light source such as a high-pressure mercury lamp, a metal halide lamp, and an ultraviolet LED is attached to the side of the print head, and the print head side or the substrate side (printed wiring board side) is moved, and a predetermined range is scanned and irradiated. In this case, printing and curing by ultraviolet irradiation are performed almost simultaneously. Note that drying such as post-cure is added as necessary. For the inkjet printer, a piezo type is mainly preferably used. Therefore, the cured product of the inkjet solder resist composition of the embodiment is suitably used for printed wiring boards, electric and electronic components, etc.

[0052] [Printed wiring board] The printed wiring board is a substrate comprising a cured product obtained by applying the inkjet solder resist composition of the embodiment and curing the composition on the substrate. As the substrate, in addition to a printed wiring board or flexible printed wiring board in which a circuit is formed in advance using copper or the like, materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, copper-clad laminates for high-frequency circuits using fluororesin, polyethylene, polyphenylene ether, polyphenylene oxide, cyanate, etc. are used, and examples thereof include copper-clad laminates of all grades (such as FR-4), as well as metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer substrates, etc.

[0053] In the following description of examples and comparative examples, the present invention is not limited to the embodiments of the examples and comparative examples. In the following, "parts" and "%" are all based on mass unless otherwise specified. EXAMPLES

[0054] In the following description of examples and comparative examples, the present invention is not limited to the embodiments of the examples and comparative examples. In the following, "parts" and "%" are all based on mass unless otherwise specified.

[0055] [Preparation of Inkjet Solder Resist Composition] The components were charged into a dissolver and stirred based on the composition and amounts (parts by mass) shown in Table 1. The mixture was then dispersed for 2 hours using a bead mill to prepare the inkjet solder resist compositions of the Examples and Comparative Examples. A conical type K-8 bead mill (manufactured by BEULA Co., Ltd.) was used, and the mixture was kneaded under the conditions of a rotation speed of 1200 rpm, a discharge amount of 20%, a bead particle size of 0.65 mm, and a filling rate of 88%.

[0056] [Raw materials used] The raw materials and abbreviations used in the examples and comparative examples are as follows. SBL-100: Blocked isocyanate (manufactured by Asahi Kasei Corporation) A-BPE-4: Ethoxylated bisphenol A diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) DPGDA: Dipropylene glycol diacrylate (manufactured by Daicel Allnex Corporation) 1,9-NDA: 1,9-nonanediol diacrylate (Dai-ichi Kogyo Seiyaku Co., Ltd.) HDDA: 6-Hexanediol diacrylate (manufactured by Daicel-Allnex Corporation) AOMA: 2-(allyloxymethyl)methyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) 4HBA: 4-hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation) Omnirad® 379: 2-Dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (IGM Resins BV) Omnirad® 819: Bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide (manufactured by IGM Resins B.V.) Phthalocyanine blue: FASTOGEN (registered trademark) BLUE (DIC Corporation) Chromophthal Yellow: Chromophthal Yellow GR (BASF Japan Ltd.) Melamine (Melamine: Nissan Chemical Co., Ltd.) BYK-307: Silicone additive (manufactured by BYK Japan Co., Ltd.)

[0057] [Table 1]

[0058] [Viscosity measurement] The viscosity of the inkjet solder resists in the examples and comparative examples was measured in accordance with JIS Z 8803:2011, Clause 10 "Method of measuring viscosity using a cone-plate type rotational viscometer" at 50°C, 100 rpm, and 30 seconds using a cone rotor of 1°34'×R24 and a cone-plate type viscometer (TVE-33H, manufactured by Toki Sangyo Co., Ltd.). The viscosity of the example at 50°C was 13 mPa·s. The viscosity of the comparative example at 50°C was 12 mPa·s.

[0059] [Measurement of volatile organic compounds] For the inkjet solder resist compositions of the Examples and Comparative Examples, the amount of volatile organic compounds generated during heating was measured using a flame ionization detector (FID). The volatile organic compounds of the samples were converted into carbon amounts, and the total volatile organic compounds (T-VOC: Total Volatile Organic Compounds (unit: ppmC)) were measured based on the carbon amounts.

[0060] A certain amount of the inkjet solder resist composition sample of the Examples and Comparative Examples was dispensed into a 12 mL crimp vial, sealed with a cap with a packing, and then heated at 50°C for 1 hour. The amount of volatile organic compounds emitted from the sample was made constant, and 0.2 mL of gas sample was dispensed from the crimp vial with a gas-tight syringe. The gas sample was loaded into an FID detector (Shimadzu Corporation: GC-2010) and measured as total volatile organic compounds (T-VOC) based on the amount of carbon. The amount of the sample dispensed into the crimp vial of the Examples and Comparative Examples was 10±1 mg per sample, and each of the Examples and Comparative Examples was measured three times to obtain an average value.

[0061] Pure methane (99.9%) (manufactured by Taiyo Nippon Sanso JFP Co., Ltd.) was used as the standard gas for quantification. The standard gas was diluted in sequence to prepare standard gases of 100 to 10,000 ppmC, and a calibration curve was created from the peak area values ​​obtained by measurement. Using the calibration curve, the total volatile organic compounds (T-VOCs) in the gas phase were calculated from the peak area values ​​obtained by measuring each sample. The results are shown in Table 2.

[0062] [Table 2]

[0063] [Consideration] From the results of the Examples and Comparative Examples, the Examples significantly reduce the generation of total volatile organic compounds. It is presumed that the cause of the variation in the amount of total volatile organic compounds in the Examples depending on the amount of sample used is that the amount of volatilization is small from the beginning and is dependent on the amount of sample used. Therefore, from the results of the Examples, the amount of volatile organic compounds in the inkjet solder resist composition at 50°C is 500 ppmC or less, preferably 400 ppmC or less.

[0064] Furthermore, since it is necessary to suppress the amount of evaporation during heating in the inkjet solder resist, it is necessary to select the boiling point of the acrylic monomer, and specifically, rather than using an acrylic monomer with a boiling point of 200° C. or more alone, it is preferable to use an acrylic monomer with a boiling point of 200° C. or more in combination with an acrylic monomer with a boiling point of 100° C. or more and less than 200° C., and it is particularly preferable to use an acrylic monomer with a boiling point of 300° C. or more in combination with an acrylic monomer with a boiling point of 100° C. or more and less than 200° C. As described above, by using acrylic monomers with different boiling points in combination, it is possible to improve the fluidity during heating.

[0065] Therefore, the total parts by mass of acrylic monomers having a boiling point of 300° C. or more per 100 parts by mass of the acrylic monomers in the inkjet solder resist composition is derived to be 30 parts by mass or more, preferably 40 parts by mass or more, and more preferably 45 parts by mass or more.

[0066] Furthermore, in order to achieve both suppression of the amount of volatile organic compounds volatilized and the fluidity of the ink, acrylic monomers with lower boiling points are blended in while being based on acrylic monomers with high boiling points of 200°C or higher. Therefore, the viscosity of the inkjet solder resist composition at 50°C is 15 mPa s or less, and preferably 13 mPa s or less.

Claims

1. An inkjet solder resist composition containing an acrylic monomer, The acrylic monomer contains an acrylic monomer having a boiling point of 200° C. or higher, The inkjet solder resist composition has a volatile organic compound content of 500 ppmC or less at 50° C., The inkjet solder resist composition has a viscosity of 15 mPa·s or less at 50° C.

1. An ink-jet solder resist composition comprising:

2. The inkjet solder resist composition according to claim 1 , wherein the acrylic monomer further comprises an acrylic monomer having a boiling point of 100° C. or higher and lower than 200° C.

3. The inkjet solder resist composition according to claim 2 , wherein the acrylic monomer further contains an acrylic monomer having a boiling point of 300° C. or higher.

4. 4. The inkjet solder resist composition according to claim 3, wherein the total parts by mass of the acrylic monomers having a boiling point of 300° C. or higher is 30 parts by mass or more, based on 100 parts by mass of the total acrylic monomers in the inkjet solder resist composition.

5. A cured product obtained by curing the inkjet solder resist composition according to claim 1.

6. A printed wiring board comprising the ink-jet solder resist according to claim 5.

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