JP2019114497A - Conductive paste and method for producing conductive pattern forming substrate - Google Patents

Abstract

To provide a photosensitive conductive paste that allows formation of a fine pattern not easily noticeable, and expresses high conductivity.SOLUTION: A conductive paste contains a conductive particle (A), a compound (B) having an unsaturated double bond, a photopolymerization initiator (C) and C.I. solvent black 3 (D). The content of the C.I. solvent black 3 (D) is 0.5-15 pts.wt. relative to 100 pts.wt. of the conductive particle (A).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive paste, a conductive pattern forming substrate using the same, a method of manufacturing the same, and a touch panel with an electrode.

  In recent years, touch panels have been widely used as input means. The touch panel includes a display unit such as a liquid crystal panel, and a touch panel sensor that detects information input to a specific position. The touch panel methods are roughly classified into a resistive film method, a capacitance method, an optical method, an electromagnetic induction method, an ultrasonic method, and the like according to a detection method of an input position. Among them, a capacitive touch panel is widely used for reasons of optically bright, excellent in design, simple in structure, and excellent in function. The capacitive touch panel sensor has a second electrode which is orthogonal to the first electrode and the insulating layer, applies a voltage to the electrode on the touch panel surface, and the capacitance when a conductor such as a finger touches the electrode. The contact position obtained by detecting the change is output as a signal. As a touch panel sensor used in the capacitance method, for example, a structure in which an electrode and an external connection terminal are formed on a pair of opposing transparent substrates, and an electrode and an external connection terminal are formed on both surfaces of one transparent substrate. The structure etc. are known. As wiring electrodes used for touch panel sensors, transparent wiring electrodes were generally used from the viewpoint of making the wiring electrodes difficult to see, but in recent years, metal has been used by increasing sensitivity and increasing screen size and definition. Wiring electrodes made of materials are in widespread use, and finer patterns are required.

  A touch panel sensor having a wiring electrode using a metal material has a problem that the wiring electrode is visually recognized due to the metallic gloss of the wiring electrode. As a method of making the wiring electrodes less visible, it is conceivable to suppress reflection by blackening treatment of metal. As a metal blackening treatment liquid, for example, a hydrochloric acid solution in which tellurium is dissolved is proposed (see, for example, Patent Document 1). Moreover, in order to reduce the reflectance of a conductive circuit pattern, the photosensitive conductive resin composition containing a black material is proposed (for example, refer patent document 2).

JP, 2006-233327, A JP 2014-170111 A

  However, when the metal blackening technology described in Patent Document 1 is applied to a touch panel sensor, there is a problem that the conductivity of the wiring electrode is reduced due to the oxidation of metal. Further, in the technology described in Patent Document 2, the black pigment material inhibits contact between metal particles and reduces the conductivity, and the black pigment material does not sufficiently develop color and has sufficient metallic gloss. Problems such as difficulty in suppressing This invention is made in view of the said situation, and an object of this invention is to provide the electrically conductive paste which can form fine pattern which is hard to be recognized visually, and expresses high conductivity.

In order to solve the above-mentioned subject, the present invention mainly has the following composition.
Conductive particles (A), compounds having unsaturated double bonds (B), photopolymerization initiators (C) and C.I. I. Solvent black 3 (D); I. The electrically conductive paste whose content of solvent black 3 (D) is 0.5-15 weight parts with respect to 100 weight parts of said conductive particles (A).

  According to the conductive paste of the present invention, it is possible to form a conductive pattern of a fine pattern which is hard to be recognized visually and which is excellent in conductivity.

It is the schematic which shows the electroconductive pattern for fine pattern processability in the Example and a comparative example, electroconductivity, visibility (inconspicuousness) evaluation.

  The conductive paste of the present invention comprises conductive particles (A), a compound (B) having an unsaturated double bond, a photopolymerization initiator (C) and C.I. I. Contains Solvent Black 3 (D). The conductive pattern obtained by the conductive paste of the present invention is a composite of an organic component and an inorganic component, and the conductive particles (A) are brought into contact with each other by curing shrinkage during heat curing. It is expressed. The compound (B) having an unsaturated double bond and the photopolymerization initiator (C) enable fine pattern formation using a photolithography method. Furthermore, C.I. I. By the solvent black 3 (D), the reflection of the conductive pattern can be suppressed and the conductive pattern can be made less visible. Furthermore, among the black dyes, C.I. I. Solvent Black 3 (D) is less likely to inhibit contact between conductive particles (A) during heat curing; I. The conductivity can be improved by selecting the solvent black 3 (D).

(Conductive particles (A))
In the present invention, “conductive” means that the electrical resistivity at 20 ° C. is 500 μΩ · cm or less. Examples of the conductive particles (A) include particles of gold, silver, copper, platinum, lead, tin, nickel, bismuth, zinc, palladium, aluminum, tungsten, molybdenum, chromium, titanium, indium, and alloys thereof. It can be mentioned. Two or more of these may be contained. Among these, particles of gold, silver, copper, platinum, lead, tin, nickel and aluminum are preferable, and particles of silver are more preferable, from the viewpoint of further improving the conductivity.

  The primary particle diameter of the conductive particles (A) is preferably 0.1 μm or more from the viewpoint of further improving the fine pattern processability. On the other hand, the primary particle diameter of the conductive particles (A) is preferably 1.0 μm or less, more preferably 0.4 μm or less, from the viewpoint of further improving the conductivity. Here, the primary particle diameter of the conductive particles (A) means the number average value of the particle diameters of the primary particles of 100 conductive particles (A) randomly selected. The conductive particles (A) are collected from the conductive paste, observed at a magnification of 25000 using an electron microscope, and the major axis and the minor axis of the primary particles of 100 randomly selected conductive particles (A). The average value is measured as the primary particle diameter, and the primary particle diameter of the conductive particles (A) can be calculated from the number average value. As a method of collecting the conductive particles (A) from the conductive paste, for example, the resin component is dissolved with an organic solvent, the precipitated conductive particles (A) are collected, and 10 at 70 ° C. using a box oven. The method of drying for a minute is mentioned.

  From the viewpoint of further improving the conductivity, the content of the conductive particles (A) in the conductive paste of the present invention is preferably 60% by weight or more, more preferably 65% by weight or more, and 70% by weight or more in the total solid content. Is more preferred. On the other hand, the content of the conductive particles (A) is preferably 95% by weight or less, more preferably 90% by weight or less, and still more preferably 85% by weight or less in terms of improving the fine pattern processability. . Here, the total solid content refers to all components except for the solvent of the conductive paste.

(Compound (B) having an unsaturated double bond)
Examples of the compound (B) having an unsaturated double bond in the present invention include styrenes, acrylic monomers, acrylic polymers, and reaction products of carboxyl compounds having unsaturated double bonds and epoxy compounds. Epoxy carboxylate compounds, 1-vinyl-2-pyrrolidone and the like can be mentioned. Two or more of these may be contained.

  Examples of styrenes include styrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, α-methylstyrene, chloromethylstyrene, hydroxymethylstyrene and the like.

  Examples of acrylic monomers include methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, iso-butyl acrylate, iso-propane acrylate, glycidyl acrylate, butoxytriethylene glycol acrylate, dicyclopentanyl acrylate, Cyclopentenyl acrylate, 2-hydroxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, isodexyl acrylate, isooctyl acrylate, lauryl acrylate, 2-methoxyethyl acrylate, methoxy ethylene glycol acrylate, methoxy diethylene glycol acrylate, octafluoro Pentyl acrylate, phenoxyethyl acrylate , Stearyl acrylate, trifluoroethyl acrylate, aminoethyl acrylate, phenyl acrylate, phenoxyethyl acrylate, 1-naphthyl acrylate, 2-naphthyl acrylate, thiophenol acrylate, benzyl mercaptan acrylate, allylated cyclohexyl diacrylate, methoxylated cyclohexyl diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, polypropylene Glycol diacrylate Triglycerol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol monohydroxy pentaacrylate, dipentaerythritol hexaacrylate, acrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, Nn-butoxy Methyl acrylamide, N-isobutoxy methyl acrylamide, acrylic acid adduct of ethylene glycol diglycidyl ether having hydroxyl group with ring opening of epoxy group with unsaturated acid, acrylic acid adduct of diethylene glycol diglycidyl ether, neopentyl glycol diglycidyl Acrylic acid adduct of ether, Acrylic acid adduct of glycerin diglycidyl ether, bisphenol A Epoxy acrylate monomers such as acrylic acid adducts of diglycidyl ether, acrylic acid adducts of bisphenol F, acrylic acid adducts of cresol novolac, γ-acryloxypropyltrimethoxysilane and compounds in which their acrylic groups are substituted with methacryl groups Etc.

  The acrylic polymer refers to a polymer or copolymer of a monomer containing an acrylic monomer. It is preferable that an acryl-type polymer has a carboxyl group, and the copolymer of the above-mentioned acryl-type monomer, and unsaturated acid or its acid anhydride is more preferable. Examples of unsaturated acids or their acid anhydrides include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate and acid anhydrides thereof. The acid value of the acrylic copolymer can be adjusted by the copolymerization ratio of the unsaturated acid.

  As an epoxy compound which is a raw material of an epoxy carboxylate compound, for example, methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether , Neopentyl glycol diglycidyl ether, bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, bisphenol fluorene glycidyl ether, biphenol diglycidyl ether, tetramethyl biphenol glycidyl ether , Trimethylol prop Glycidyl ethers such as triglycidyl ether; alicyclic epoxy resins such as 3 ', 4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate; glycidyl amines such as tert-butyl glycidyl amine; glycidyl esters etc. . Moreover, as a carboxyl compound which has an unsaturated double bond which is a raw material of an epoxy carboxylate, (meth) acrylic acid, crotonic acid, cinnamic acid, (alpha)-cyano cinnamic acid etc. are mentioned, for example.

  The compound (B) having an unsaturated double bond preferably has a urethane bond. As a method of introducing a urethane bond into the compound (B) having an unsaturated double bond, for example, in the case of an acrylic polymer having a hydroxyl group or an epoxy carboxylate compound, a method of reacting a diisocyanate compound with these hydroxyl groups is mentioned Be Examples of the diisocyanate compound include hexamethylene diisocyanate, tetramethylxylene diisocyanate, naphthalene-1,5-diisocyanate, tolidene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, allyl cyan diisocyanate, norbornane diisocyanate and the like. Two or more of these may be used.

  The compound (B) having an unsaturated double bond preferably has a phenolic hydroxyl group. The acid value of the compound (B) having an unsaturated double bond is preferably 30 mg KOH / g or more from the viewpoint of solubility in a developer. On the other hand, the acid value of the compound (B) having an unsaturated double bond is preferably 250 mg KOH / g or less from the viewpoint of suppressing excessive dissolution of the unexposed area. The acid value of the compound (B) having an unsaturated double bond can be measured in accordance with JIS K 0070 (1992).

  For example, in the case of an acrylic polymer, the acid value of the compound (B) having an unsaturated double bond can be adjusted to a desired range by the ratio of the unsaturated acid in the component. In the case of the epoxy carboxylate compound, it can adjust to a desired range by making polybasic acid anhydride react. Examples of polybasic acid anhydrides include succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, itaconic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, anhydride Trimellitic acid, maleic anhydride and the like can be mentioned.

  Further, by reacting the carboxyl group of the above-mentioned acrylic polymer and epoxy carboxylate compound with a compound having an unsaturated double bond such as glycidyl (meth) acrylate, the unsaturated di-reactivity reactive with the side chain The amount of reactive unsaturated double bonds can be adjusted to the desired range by the ratio of compounds which can introduce heavy bonds and react with unsaturated double bonds.

(Photopolymerization initiator (C))
As the photopolymerization initiator (C), for example, benzophenone, methyl O-benzoylbenzoate, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 4,4′-dichloromethane Benzophenone, 4-benzoyl-4'-methyl diphenyl ketone, benzophenone derivatives such as fluorenone; p-t-butyl dichloroacetophenone, 4-azidobenzalacetophenone, acetophenone derivatives such as 2,2'-diethoxyacetophenone; thioxanthone, 2 Thioxanthone derivatives such as methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone; benzyl derivatives such as benzyl, benzyldimethyl ketal, benzyl-β-methoxyethyl acetal; Ben Benzoin derivatives such as zoin, benzoin methyl ether, benzoin butyl ether; 1,2-octanedione-1- [4- (phenylthio) -2- (O-benzoyloxime)], ethanone-1- [9-ethyl-6- (2-Methylbenzoyl) -9H-carbazol-3-yl] -1- (O-acetyloxime), 1-phenyl-1,2-butanedione-2- (O-methoxycarbonyl) oxime, 1-phenyl-propane Dione-2- (O-ethoxycarbonyl) oxime, 1-phenyl-propanedione-2- (O-benzoyl) oxime, 1,3-diphenyl-propanetrione-2- (O-ethoxycarbonyl) oxime, 1-phenyl Oxime compounds such as 3-ethoxy-propanetrione-2- (O-benzoyl) oxime 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, etc. Α-hydroxy ketone compounds of the formula: 2-methyl- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane- Α-aminoalkylphenone compounds such as 1-one, 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholin-4-yl-phenyl) butan-1-one; 2,4 Phosphine oxide such as 6, 6-trimethyl benzoyl diphenyl phosphine oxide, bis (2, 4, 6 trimethyl benzoyl) phenyl phosphine oxide, etc. Compounds; aromatic sulfonyl chloride compounds such as naphthalene sulfonyl chloride and quinoline sulfonyl chloride; anthraquinone compounds such as anthraquinone, 2-t-butyl anthraquinone, 2-amyl anthraquinone, .beta. Anthrone compounds such as verone and methylene anthrone; 2,6-bis (p-azidobenzylidene) cyclohexanone, 6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2,6-bis (p-azidobenzylidene) cyclohexanone, 6-bis (p-azidobenzylidene) -4-methylcyclohexanone, N-phenylthioacridone, 4,4'-azobisisobutyronitrile, diphenyl disulfide, benzthiazo Disulfide, triphenylphosphine, camphorquinone, carbon tetrabromide, tribromophenylsulfone, benzoyl peroxide and the like. Two or more of these may be contained. Among these, oxime compounds having high photosensitivity are preferable.

  The content of the photopolymerization initiator (C) in the conductive paste of the present invention is 0.05 parts by weight with respect to 100 parts by weight of the compound (B) having an unsaturated double bond, from the viewpoint of sufficiently curing the exposed part It is preferably at least part, and more preferably at least 1.0 part by weight. On the other hand, the content of the photopolymerization initiator (C) is preferably 30 parts by weight or less, and more preferably 10 parts by weight or less, from the viewpoint of suppressing wire thickening due to high sensitivity.

  C. I. As the solvent black 3 (D), for example, oil black 803, oil black BS, oil black NO5, oil black HBB, oil black 860 (above, made by Orient Chemical Industry Co., Ltd.), Neptun black X60 (made by BASF Corporation) And Fat Black HB01 (manufactured by Hoechst), Oil Color Black 141 (manufactured by Chuo Synthetic Chemical Co., Ltd.), and the like. Two or more of these may be contained.

  In the conductive paste of the present invention, C.I. I. The content of the solvent black 3 (D) is preferably 0.5 parts by weight or more with respect to 100 parts by weight of the conductive particles (A) from the viewpoint of making it harder to be recognized visually by blackening. Meanwhile, C.I. I. The content of the solvent black 3 (D) is 100 parts by weight of the conductive particles (A) from the viewpoint of suppressing excessive light absorption in the upper part of the coating film of the conductive paste and further improving the fine pattern processability and the conductivity. On the other hand, 15 parts by weight or less is preferable, and 5 parts by weight or less is more preferable.

The conductive paste of the present invention preferably further contains a thermosetting resin. By containing the thermosetting resin, the adhesion to the substrate is improved, so that a finer wiring pattern can be formed. As a thermosetting resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, unsaturated polyester resin, a silicone resin, a polyurethane etc. are mentioned, for example. Two or more of these may be contained. Among these, epoxy resins are preferable because they have higher adhesion to substrates. As an epoxy resin, for example, ethylene glycol modified epoxy resin, bisphenol A type epoxy resin, brominated epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, alicyclic epoxy resin, glycidyl amine type epoxy resin, glycidyl ether type Epoxy resin, heterocyclic epoxy resin and the like can be mentioned. The epoxy equivalent of the epoxy resin is preferably 500 g / equivalent or less from the viewpoint of further improving pattern processability by adhesion improvement. On the other hand, the epoxy equivalent of the epoxy resin is preferably 150 g / equivalent or more from the viewpoint of suppressing the decrease in solubility in the unexposed area due to heat curing. Here, an epoxy equivalent means the mass of the epoxy resin containing an epoxy group of 1 equivalent, and it can obtain | require it by dividing the molecular weight calculated | required from molecular structure by the number of the epoxy groups contained in the structure. Molecular structure: gel permeation chromatography (GPC) analysis, infrared spectroscopy (IR) analysis, proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) analysis, pyrolysis gas chromatography / mass (GC / MS) analysis, matrix assisted Identification by selecting and analyzing an analysis method according to the structure from analysis methods such as laser desorption ionization / time-of-flight mass spectrometry (MALDI / TOFMS), gas chromatography (GC) analysis, CHN elemental analysis, etc. it can. In addition, when 2 or more types of epoxy resins are contained, it is preferable to contain 1 or more types of epoxy resin which has an epoxy equivalent of the said range.

  The content of the thermosetting resin in the conductive paste of the present invention is 1 weight with respect to 100 parts by weight of the compound (B) having an unsaturated double bond, from the viewpoint of further improving the fine pattern processability by adhesion improvement. It is preferably at least part, and more preferably at least 30 parts by weight. On the other hand, the content of the thermosetting resin is preferably 100 parts by weight or less, and more preferably 80 parts by weight or less, from the viewpoint of suppressing the decrease in solubility in the unexposed area due to thermosetting.

  The conductive paste of the present invention can further contain a sensitizer. Examples of sensitizers include 2,4-diethylthioxanthone, isopropylthioxanthone, 2,3-bis (4-diethylaminobenzal) cyclopentanone, 2,6-bis (4-dimethylaminobenzal) cyclohexanone, 2 , 6-Bis (4-dimethylaminobenzal) -4-methylcyclohexanone, Michler's ketone, 4,4-bis (diethylamino) benzophenone, 4,4-bis (dimethylamino) chalcone, 4,4-bis (diethylamino) chalcone P-Dimethylaminocinnamylidene indanone p-dimethylaminobenzylidene indanone 2- (p-dimethylaminophenylvinylene) isonaphthothiazole 1,3-bis (4-dimethylaminophenylvinylene) isonaphthothiazole 1,3-bis (4-dimethyl) Minobenzal) acetone, 1,3-carbonylbis (4-diethylaminobenzal) acetone, 3,3-carbonylbis (7-diethylaminocoumarin), N-phenyl-N-ethylethanolamine, N-phenylethanolamine, N- Examples include tolyl diethanolamine, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, 3-phenyl-5-benzoylthiotetrazole, 1-phenyl-5-ethoxycarbonylthiotetrazole and the like. Two or more of these may be contained.

  The content of the sensitizer in the conductive paste of the present invention is preferably 0.05 parts by weight or more with respect to 100 parts by weight of the compound (B) having an unsaturated double bond, from the viewpoint of improving the photosensitivity. On the other hand, the content of the sensitizer is preferably 10 parts by weight or less with respect to 100 parts by weight of the compound (B) having an unsaturated double bond, from the viewpoint of suppressing wiring thickening due to high sensitivity.

  The conductive paste of the present invention can further contain a solvent. As the solvent, for example, N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethylsulfoxide, γ-butyrolactone, ethyl lactate, 1-methoxy-2-propanol 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate , “DMEA”), diethylene glycol monobutyl ether, diethylene glycol, 2,2,4-trimethyl-1,3-propane Such as Tan monoisobutyrate and the like. Two or more of these may be contained. The boiling point of the solvent is preferably 150 ° C. or more. When the boiling point is 150 ° C. or more, volatilization of the solvent is suppressed, and thickening of the conductive paste can be suppressed.

  The conductive paste of the present invention is a non-photosensitive polymer having no unsaturated double bond, a plasticizer, a leveling agent, a surfactant, a silane coupling agent, an antifoaming agent, and a pigment as long as the desired properties are not impaired. Etc. can be contained.

  Examples of the non-photosensitive polymer include polyethylene terephthalate, a polyimide precursor, and a closed ring polyimide.

  Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, polyethylene glycol, glycerin and the like.

  Examples of the leveling agent include special vinyl polymers and special acrylic polymers.

  As a silane coupling agent, for example, methyltrimethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrilyl. Methoxysilane etc. are mentioned.

  The conductive paste of the present invention comprises conductive particles (A), a compound (B) having an unsaturated double bond, a photopolymerization initiator (C) C.I. I. It can be obtained by mixing Solvent Black 3 (D) and, if necessary, solvents and additives. As a mixing apparatus, dispersers, such as a 3-roller mill, a ball mill, a planetary ball mill, a kneader, etc. are mentioned, for example.

  The conductive pattern-formed substrate of the present invention has a conductive pattern made of the cured product of the above-mentioned conductive paste. It is preferable to have a conductive pattern on the substrate.

  As the substrate, for example, polyester film such as polyethylene terephthalate (PET), polyimide film, aramid film, epoxy resin substrate, polyetherimide resin substrate, polyetherketone resin substrate, polysulfone resin substrate, glass substrate, silicon wafer, alumina Examples include a substrate, an aluminum nitride substrate, a silicon carbide substrate, a decorative layer forming substrate, and an insulating layer forming substrate.

  The thickness of the conductive pattern is preferably 5 μm or less, more preferably 3 μm or less, and still more preferably 2 μm or less from the viewpoint of forming a finer conductive pattern wiring. On the other hand, from the viewpoint of further improving the conductivity, 0.1 μm or more is preferable, 0.2 μm or more is more preferable, and 0.3 μm or more is more preferable. The thickness of the conductive pattern can be measured using a stylus-type profilometer such as "Surfcom" (registered trademark) 1400 (manufactured by Tokyo Seimitsu Co., Ltd.). More specifically, the thicknesses of three positions randomly selected from the conductive pattern are measured using a stylus type step gauge (length measurement: 1 mm, scanning speed: 0.3 mm / sec), respectively. It can obtain | require by calculating the average value of.

  The reflectance of the conductive pattern at a wavelength of 550 nm is preferably 30% or less. By reducing the reflectance of visible light, light reflection of the conductive pattern can be further suppressed, and the conductive pattern can be made less visible. In the present invention, attention is focused on the reflectance at a wavelength of 550 nm as an index of the reflectance of visible light. By setting the reflectance at a wavelength of 550 nm to 30% or less, the conductive pattern can be made less visible. In addition, a reflectance can be measured using a reflectometer (VSR-400: Nippon Denshoku Kogyo Co., Ltd. product) about a 0.1 mm square or more conductive pattern. The reflectance of the conductive pattern at a wavelength of 550 nm is, for example, C.I. I. The content of the solvent black 3 (D) can be reduced to 30% or less by setting the content in the above-described preferable range.

The volume resistivity of the conductive pattern is preferably less than 100 μΩ · cm. By setting the volume resistivity to less than 100 μΩ · cm, the conductivity can be further improved, and the touch sensitivity when used for a touch panel can be improved. The volume resistivity of the conductive pattern is the thickness (μm) and line width of the conductive pattern measured by using a resistance measuring tester such as 2407A manufactured by BK Precision Co., for the conductive pattern on a straight line. (Μm) The pattern length (μm) can be measured and calculated from the following equation (1).
Volume resistivity (μΩ · cm) = resistance value (Ω) × film thickness (μm) × line width (μm) × 100 / pattern length (μm) (1).

  The volume resistivity of the conductive pattern is, for example, setting the content of the conductive particles (A) in the conductive paste to the above-mentioned preferable range, and setting the heating temperature in the method for producing a conductive pattern-formed substrate to the preferable range described later. And can be less than 100 μΩ · cm.

  The line width of the conductive pattern is preferably 1 μm or more, more preferably 1.5 μm or more, and still more preferably 2 μm or more, from the viewpoint of further improving the conductivity. On the other hand, the line width of the conductive pattern is preferably 10 μm or less, more preferably 7 μm or less, and still more preferably 6 μm or less, from the viewpoint of making it harder to visually recognize.

  Next, the method for producing a conductive pattern-formed substrate of the present invention will be described. It is preferable to heat at a temperature of 100 to 250 ° C. after the above-mentioned conductive paste is applied onto a substrate, exposed and developed.

  The conductive paste may be applied by, for example, spin coating using a spinner, spray coating, roll coating, screen printing, offset printing, gravure printing, letterpress printing, flexo printing, blade coater, die coater, calendar coater, meniscus coater or Coating with a bar coater may, for example, be mentioned. Among these, screen printing is preferable because the surface flatness of the coating film of the conductive paste is excellent, and the film thickness adjustment is easy by the selection of the screen plate.

  When the conductive paste contains a solvent, it is preferable to dry the coating film to volatilize and remove the solvent. Examples of the drying method include heating and drying with an oven, an electromagnetic wave ultraviolet lamp, an infrared heater, a halogen heater, and the like, and vacuum drying. The drying temperature is preferably 50 to 130 ° C., and the drying time is preferably 1 minute to several hours.

It is preferable to expose the coating film or the dried film of the conductive paste by a photolithography method through an arbitrary mask for pattern formation. It is preferable that exposure light has light emission in the ultraviolet region that matches the absorption wavelength of the photopolymerization initiator (C) contained in the conductive paste composition, that is, in the wavelength region of 200 nm to 450 nm. As a light source for obtaining such exposure light, a mercury lamp, a halogen lamp, a xenon lamp, an LED lamp, a semiconductor laser, a KrF, an ArF excimer laser etc. are mentioned, for example. Among these, the i-line (wavelength 365 nm) of a mercury lamp is preferable. The exposure dose is preferably 50 mJ / cm ² or more, more preferably 200 mJ / cm ² or more, in terms of wavelength 365 nm, from the viewpoint of solubility of the exposed portion in the developer.

  After exposure, development is carried out using a developer to dissolve and remove the unexposed area to obtain a desired pattern. As a developing solution in the case of performing alkali development, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, ammonia water, etc .; 1 such as ethylamine, n-propylamine Secondary amines; Secondary amines such as diethylamine and di-n-propylamine; Tertiary amines such as triethylamine and methyldiethylamine; Tetraalkyl ammonium hydroxides such as tetramethyl ammonium hydroxide (TMAH); Choline etc. Quaternary ammonium salts; alcohol amines such as triethanolamine, diethanolamine, monoethanolamine, dimethylaminoethanol, diethylaminoethanol, etc .; pyrrole, piperidine, 1,8-diazabicyclo [5,4,0] -7-cobalt Decene, 1,5-diazabicyclo [4,3,0] -5-nonane, and alkali aqueous solutions the alkaline material was dissolved in water such as organic alkalis such cyclic amines such as morpholine and the like. One or more kinds of water-soluble organic solvents such as ethanol, γ-butyrolactone, dimethylformamide, N-methyl-2-pyrrolidone and surfactants may be added to these.

  As a developing method, for example, a method of spraying a developing solution on the surface of the coating film of the conductive paste while allowing the substrate on which the coating film of the conductive paste is formed to stand, rotate or transport, a coating film of the conductive paste in the developing solution The method of immersing, the method of applying an ultrasonic wave, immersing the coating film of a conductive paste in a developing solution, etc. may be mentioned.

  After development, rinse treatment with a rinse solution may be performed. Examples of the rinse solution include water; aqueous solutions of alcohols such as ethanol and isopropyl alcohol; and aqueous solutions of esters such as ethyl lactate and propylene glycol monomethyl ether acetate.

  A conductive pattern can be obtained by heating the obtained pattern. The heating atmosphere, temperature, and time can be appropriately set according to the composition of the conductive paste and the thickness of the coating film. In the present invention, heating in air is preferred. The heating temperature is preferably 100 ° C. or more, and more preferably 120 ° C. or more, from the viewpoint of sufficiently curing and further improving the conductivity. On the other hand, from the viewpoint of the heat resistance of the substrate, the heating temperature is preferably 200 ° C. or less, more preferably 150 ° C. or less. As a heating apparatus, the apparatus illustrated in the heat-drying of a coating film is mentioned.

  The conductive pattern-formed substrate of the present invention can be suitably used in applications where it is necessary that the conductive pattern is not easily visible. For example, members for touch panels, members for electromagnetic shielding, members for transparent LED lights, etc. may be mentioned. Above all, it can be suitably used as a member for a touch panel which is required to be more highly miniaturized and to make it difficult to visually recognize a conductive pattern.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

  The evaluation method in each example is as follows.

<Fine pattern processability>
The conductive paste obtained in each Example and Comparative Example was applied onto a PET film so that the film thickness after drying was 2 μm, and dried for 10 minutes in a drying oven at 100 ° C. It exposed by the exposure amount 500 mJ / cm < ² > (wavelength 365 nm conversion) using exposure apparatus (PEM-6M; Union Optical Co., Ltd. product) through the photomask which has a mesh-shaped opening part. In addition, the pitch of the mesh shape was 300 μm, and the mask opening width of the mesh portion was seven types of 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, and 7.0 μm. . The distance between the terminals was 20 mm, the width was 2 mm, and the pad portion was a square of 4 mm ² . After exposure, spray development was performed for 20 seconds using a 0.1 wt% aqueous Na ₂ CO ₃ solution, and rinsing was performed with ultrapure water. Thereafter, heating was performed for 120 minutes in drying at 140 ° C., and seven types of conductive patterns having different line widths were obtained. FIG. 1 shows a schematic view of a conductive pattern for fine pattern processability evaluation. The pad portion 1 was provided at both ends of the mesh portion, the distance 2 between terminals was 20 mm, and the pad portion width 3 was 2 mm. The obtained conductive pattern was observed with an optical microscope, and the presence or absence of pattern peeling was observed. From the smallest mask opening width at which pattern peeling is not observed, the fine pattern processability was evaluated according to the following evaluation criteria. Pass 1 or more.
5: Mask opening width 1.5 μm or more and no pattern peeling 4: Mask opening width 2.0 μm or more and no pattern peeling 3: Mask opening width 3.0 μm or more and no pattern peeling 2: Mask opening width 4.0 μm or more No peeling 1: No peeling of pattern at mask opening width of 5.0 μm or more 0: There is peeling of pattern at mask opening width of 6.0 μm or more.

<Conductive evaluation>
Among the conductive patterns obtained by the evaluation method of fine pattern machinability, the conductive pattern of the minimum mask opening width in which pattern peeling is not observed is measured using a resistance measuring tester (2407A; made by BK Precision Co., Ltd.) The resistance value was measured. In addition, the thickness of the same conductive pattern was measured using a surface roughness shape measuring machine ("Surfcom" (registered trademark) 1400D; manufactured by Tokyo Seimitsu Co., Ltd.). Further, using the optical microscope, the same conductive pattern was magnified and observed at a magnification of 1000 and the line width was measured. The volume resistivity (μΩ · cm) was calculated according to the following equation (2), and the conductivity was evaluated according to the following evaluation criteria. Pass 1 or more. However, Comparative Example 3 in which all the patterns were peeled off could not be evaluated.
Volume resistivity (μΩ · cm) = {resistance value (Ω) × film thickness (μm) × line width (μm) × pad portion width (μm)} / {terminal distance (μm) / pitch (μm)} × 100 ... (2)
5: 50 μΩ · cm or less 4: 50 μΩ · cm or more 60 μΩ · cm or less 3: 60 μΩ · cm or more 70 μΩ · cm or less 2: 70 μΩ · cm or more 80 μΩ · cm or less 1: 80 μΩ · cm or more 100 μΩ · cm or less 0: 100 μΩ ·· cm or more.

<Visibility (visual difficulty) (visual)
The conductive pattern-formed substrate obtained by the evaluation method of fine pattern processability is placed on a black film, light is projected using a light projector, and 10 people visually observe from positions 30 cm apart, respectively, in a mesh shape It was evaluated according to the following evaluation criteria whether or not the electrode part of was visible. Pass 2 or more. However, Comparative Example 3 in which all the patterns were peeled off could not be evaluated.
5: 10 people are not visible 4: 8 or more and less than 10 are not visible 3: 6 or more and less than 8 are not visible 2: 4 or more and 6 or less are not visible 1: 2 or more and less than 4 are visible Impossible 0: Less than 2 people can not see.

<Visibility (visual difficulty) (reflectance)>
The reflectance at a wavelength of 550 nm was measured using a reflectometer (VSR400: manufactured by Nippon Denshoku Kogyo Co., Ltd.) for the pad portion of the conductive pattern formed substrate obtained by the method of evaluating fine pattern processability. It evaluated according to the following evaluation criteria. Passed 3 or more.
5: less than 20% 4: 20% more than 25% less than 3: 25% more than 30% less than 2: 30% more than 35% less than 1: 35% more than 40% less than 0: 40%.

The materials used in each example are as follows.
[Conductive particle (A)]
A-1: Silver particles having a primary particle diameter of 0.3 μm (electrical resistivity at 20 ° C. of 3 μΩ · cm or less)
A-2: Silver particles having a primary particle diameter of 0.8 μm (electrical resistivity at 20 ° C. of 3 μΩ · cm or less)
The primary particle diameter of the conductive particles was obtained by observing the conductive particles at a magnification of 25000 using an electron microscope, and measuring the major and minor diameters of the primary particles of 100 conductive particles randomly selected. It measured and made the average value primary particle diameter, and it computed from the number average value.

[Compound having unsaturated double bond (B)]
Synthesis Example 1 Carboxyl Group-Containing Acrylic Copolymer (B-1)
In a nitrogen atmosphere reaction vessel, 150 g of diethylene glycol monoethyl ether acetate (hereinafter, “DMEA”) was charged, and the temperature was raised to 80 ° C. using an oil bath. In this, 20 g of ethyl acrylate (hereinafter, "EA"), 40 g of 2-ethylhexyl methacrylate (hereinafter, "2-EHMA"), 20 g of styrene (hereinafter, "St"), 15 g of acrylic acid (hereinafter, A mixture consisting of "AA"), 0.8 g of 2,2-azobisisobutyronitrile and 10 g of DMEA was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was further stirred at 80 ° C. for 6 hours for polymerization reaction. Thereafter, 1 g of hydroquinone monomethyl ether was added to terminate the polymerization reaction. Subsequently, a mixture consisting of 5 g of glycidyl methacrylate (hereinafter "GMA"), 1 g of triethylbenzene ammonium chloride and 10 g of DMEA was dropped over 0.5 hours. After completion of the dropwise addition, the mixture was further stirred at 80 ° C. for 2 hours to carry out an addition reaction. Unreacted impurities are removed by purifying the resulting reaction solution with methanol, and vacuum drying is further performed for 24 hours to obtain a copolymerization ratio (by mass): EA / 2-EHMA / St / GMA / AA = 20/40. A carboxyl group-containing acrylic copolymer of / 20/5/15 was obtained. It was 103 mgKOH / g when the acid value of the obtained copolymer was measured. The acid value was measured in accordance with JIS K 0070 (1992).

[Photoinitiator (C)]
C-1: "IRGACURE" (registered trademark) 369 (manufactured by Ciba Japan Co., Ltd., α-aminoalkylphenone compound)
C-2 "IRGACURE" (registered trademark) OXE 02 (Ciba Japan KK, oxime compound)
[C. I. Solvent Black 3 (D)]
D-1: Oil Black (registered trademark) HBB (manufactured by Orient Chemical Industry Co., Ltd.)
D-2: Oil Black (registered trademark) 860 (manufactured by Orient Chemical Industry Co., Ltd.)
D-3: Neptun Black (registered trademark) X60 (manufactured by BASF)
[Epoxy resin]
E-1: “JER” (registered trademark) 828 (Mitsubishi Chemical Corporation, epoxy equivalent 188)
E-2: “ADECA RESIN” (registered trademark) EPR-4030 (manufactured by ADEKA, epoxy equivalent: 380)
E'-3: "JER" (registered trademark) 1002 (manufactured by Mitsubishi Chemical Co., Ltd., epoxy equivalent 650).

[Black material]
CB: carbon black # 240 (manufactured by Mitsubishi Chemical Corporation, average particle size 45 nm)
NH 805: C.I. I. Solvent Black 5 NUBIAN BLACK (registered trademark) NH-805 (manufactured by Orient Chemical Industry Co., Ltd.)
Example 1
In a 100 mL clean bottle, 10.0 g of a compound (B-1) having unsaturated double bonds, 0.50 g of a photopolymerization initiator (C-2), 0.24 g of C.I. I. Add Solvent Black 3 (D-1) and 5.0 g of DMEA, mix them using a rotation-revolution vacuum mixer “Awatori Fuyutaro” (registered trademark) ARE-310 (manufactured by Shinky Co., Ltd.), 15 .74 g of a resin solution (solid content 68.2% by mass) was obtained.

  The resulting 15.74 g of resin solution and 40.4 g of conductive particles (A-1) were mixed and kneaded using a three-roller mill (EXAKT M-50; made by EXAKT) to give 55.78 g of A conductive paste was obtained. Table 1 shows the composition of the conductive paste.

  The fine pattern processability, conductivity, visibility (visual difficulty) (visual difficulty) and visibility (visual difficulty) (reflectance) were evaluated by the methods described above using the obtained conductive paste. . The fine pattern processability was as good as "5" and the conductivity as "4". Although the visibility (inconspicuousness) (visual observation) and the visibility (inconspicuousness) (reflectance) were all “2”, it was a usable range without any problem. The evaluation results are shown in Table 2.

[Examples 2 to 14]
The conductive paste of the composition shown in Table 1 was produced by the same method as in Example 1 and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

Comparative Examples 1 to 5
The electrically conductive paste of the composition shown in Table 1 was manufactured by the same method as Example 1, and it carried out similarly to Example 1, and evaluated. The evaluation results are shown in Table 2.

Comparative Example 6
The photosensitive electrically conductive paste of the composition shown in Table 1 was manufactured by the same method as Example 1, and the electrically conductive pattern for each evaluation was formed.

  An aqueous solution of hydrochloric acid was prepared by adding 40 g of 36% by mass hydrochloric acid to 50 g of water. Next, 3 g of tellurium oxide was added to 90 g of this aqueous hydrochloric acid solution. After visually confirming that tellurium oxide was completely dissolved in the aqueous solution of hydrochloric acid, 5 g of acetic acid was added to the aqueous solution of hydrochloric acid, and water was further added to make the total amount 100 g to prepare a blackening solution. The substrate having the conductive pattern formed thereon was immersed in the obtained blackening solution for 10 seconds to be blackened, thereby forming a conductive pattern-formed substrate. Evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.

  As shown in Table 2, the conductive patterns obtained by the conductive pastes of Examples 1 to 14 are all fine pattern processability, the conductivity is “1” or more, visibility (poor visibility) (visual), Visibility (visual difficulty) (reflectance) was a range that can be used without problems at "2" or more. On the other hand, the conductive pattern obtained by the conductive paste of Comparative Examples 1 to 6 has fine pattern processability, conductivity, visibility (visibility) (visually) or visibility (visibility) (reflectance) Either was insufficient.

  The conductive paste of the present invention can be suitably used as a member for a touch panel which is required to be highly miniaturized and to make it hard to visually recognize wiring electrodes.

1 pad 2 distance between terminals 3 pad width

Claims (8)

Conductive particles (A), compounds having unsaturated double bonds (B), photopolymerization initiators (C) and C.I. I. Solvent black 3 (D); I. The electrically conductive paste whose content of solvent black 3 (D) is 0.5-15 weight parts with respect to 100 weight parts of said conductive particles (A). The conductive paste according to claim 1, further comprising an epoxy resin (E) having an epoxy equivalent of 150 to 500 g / equivalent. The electrically conductive paste of Claim 1 or 2 in which the said photoinitiator (C) contains an oxime type compound. The conductive particle according to any one of claims 1 to 3, wherein the primary particle diameter of the conductive particles (A) is 0.1 to 0.4 μm. A method for producing a conductive pattern-formed substrate, wherein the conductive paste according to any one of claims 1 to 4 is applied onto a substrate, exposed and developed, and then heated at a temperature of 100 to 250 ° C to obtain a conductive pattern. The manufacturing method of the conductive pattern formation board | substrate of Claim 5 whose thickness of the said conductive pattern is 2 micrometers or less. The conductive pattern formation board | substrate which has the conductive pattern which consists of hardened | cured material of the conductive paste in any one of Claims 1-4 on a board | substrate. The conductive pattern forming substrate according to claim 7, wherein a reflectance of the conductive pattern at a wavelength of 550 nm is 30% or less and a volume resistivity is less than 100 μΩ · cm.

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