WO2014069436A1

WO2014069436A1 - Photosensitive conductive paste and method for producing conductive pattern

Info

Publication number: WO2014069436A1
Application number: PCT/JP2013/079212
Authority: WO
Inventors: 水口創; 草野一孝
Original assignee: 東レ株式会社
Priority date: 2012-10-31
Filing date: 2013-10-29
Publication date: 2014-05-08
Also published as: JPWO2014069436A1; TW201423268A

Abstract

The purpose of the present invention is to provide: a photosensitive conductive paste which enables fine patterning and is capable of providing a conductive pattern that has high surface hardness and good adhesion to a substrate or the like, while exhibiting electrical conductivity at relatively low temperatures; and a method for producing a conductive pattern using this photosensitive conductive paste. The present invention provides a photosensitive conductive paste which contains a siloxane compound (A), a compound (B) having an acid value of 30-250 mg/KOH, a photopolymerization initiator (C) and a conductive filler (D).

Description

Photosensitive conductive paste and method for producing conductive pattern

The present invention relates to a photosensitive conductive paste and a method for producing a conductive pattern.

In order to form an organic-inorganic composite conductive pattern containing an organic component such as a resin and an inorganic component such as a conductive filler, a large amount of fine silver flakes, copper powder, or carbon particles are mixed in the resin or adhesive. A so-called polymer-type conductive paste has been put to practical use.

Many of the polymer-type conductive pastes in practical use are those in which a pattern is formed by screen printing and then heat-cured to form a conductive pattern (Patent Documents 1, 2, and 3), but the dimensions are 100 μm. It is difficult to accurately draw the following pattern.

Therefore, in order to accurately draw a fine pattern, a conductive paste capable of acid etching (Patent Document 4) and a photosensitive curable conductive paste (Patent Documents 5 and 6) have been developed.

Although there is an example (Patent Document 7) in which a siloxane compound is applied as an insulating material having improved adhesion and hardness, it has been difficult to impart patternability and conductivity while maintaining adhesion and hardness.

Japanese Patent Laid-Open No. 02-206675 JP 2007-207567 A JP 2007-294451 A JP-A-10-64333 JP 2004-361352 A International Publication No. 2004/61006 JP 2012-088610 A

In order to form a pattern by a photolithography method using a conventional acid-etchable conductive paste, a resist layer must be further formed on the conductive paste coating film, which complicates the manufacturing process of the conductive pattern. It was accompanied by. Moreover, the conductive pattern manufactured using the conventional photosensitive curable conductive paste has not only low conductivity and low surface hardness, but also ITO (indium tin oxide) on a glass or film substrate. The adhesion with the electrode was poor.

Therefore, the present invention is sensitive to the fact that fine patterning is possible, the adhesion of the obtained conductive pattern to the substrate and the like is high and the surface hardness is high, and the conductivity can be expressed even at a relatively low temperature. An object is to provide a conductive paste and a method of manufacturing a conductive pattern using the same.

In order to solve the above problems, the present invention provides a photosensitive conductive paste and a method for producing a conductive pattern described in the following (1) to (9).
(1) A photosensitive conductive paste comprising a siloxane compound A, a compound B having an acid value of 30 to 250 mg / KOH, a photopolymerization initiator C, and a conductive filler D.
(2) The photosensitive conductive paste according to (1), wherein the compound B has an unsaturated double bond.
(3) The photosensitive conductive paste according to (1) or (2) above, wherein the compound B has a glass transition temperature of −10 to 60 ° C.
(4) The photosensitive conductive paste according to any one of (1) to (3), wherein the compound B is an epoxy acrylate.
(5) The siloxane compound A described in any one of (1) to (4) above, which has a substituent selected from the group consisting of an unsaturated double bond, a carboxyl group, a hydroxyl group, an aralkyl group, and a fluoroalkyl group. Photosensitive conductive paste.
(6) The photosensitive conductive paste according to any one of (1) to (5), wherein the siloxane compound A has a substituent selected from the group consisting of a carboxyl group, a hydroxyl group, and a urethane bond.
(7) The photosensitive conductive paste according to any one of (1) to (6), which contains a thermosetting compound E.
(8) The photosensitive conductive paste according to any one of (1) to (7), wherein the thermosetting compound E has an alkoxy group or an epoxy group.
(9) The photosensitive conductive material according to any one of (1) to (8), wherein the conductive filler D is added in an amount of 70 to 95% by weight based on the total solid content in the photosensitive conductive paste. paste.
(10) Applying the photosensitive conductive paste according to any one of (1) to (9) on a substrate to obtain a coating film, a coating process, drying the coating film, a drying process, and after drying An exposure process for pattern exposure of the coating film, a development process for developing the coating film after exposure to form a pattern on the substrate, and a conductive pattern by curing the pattern at 100 to 300 ° C. A method for producing a conductive pattern, comprising: a curing step.

According to the photosensitive conductive paste of the present invention, fine patterning for forming a conductive pattern is possible, and not only the development allowable width is remarkably widened, but also a conductive material having a low specific resistance even under low temperature curing conditions. A pattern can be obtained. In addition, by using the photosensitive conductive paste of the present invention, a conductive pattern having excellent adhesion to a substrate or the like and surface hardness can be obtained. Further, fine bump electrodes or wirings can be easily formed not only on a rigid substrate but also on a flexible substrate.

It is a schematic diagram which shows the translucent pattern of the photomask used for the specific resistivity evaluation of an Example. It is a schematic diagram of the sample used for the flexibility test of the Example.

The photosensitive conductive paste of the present invention contains a siloxane compound A, a compound B having an acid value of 30 to 250 mg / KOH, a photopolymerization initiator C, and a conductive filler D.

The photosensitive conductive paste of the present invention imparts uneven distribution to the dispersibility of the conductive filler D by mixing the compound B with the siloxane compound A, and efficiently forms the conductive path, thereby reducing the conductivity at a low temperature. Achieve both expression and hardness.

Further, the method for producing a conductive pattern of the present invention comprises a coating step of applying the photosensitive conductive paste of the present invention on a substrate to obtain a coating film, a drying step of drying the coating film, and the drying step described above. An exposure process for pattern exposure of the coating film, and development of the coating film after exposure to form a pattern on the substrate, and curing of the pattern at 100 to 300 ° C. to obtain a conductive pattern And a curing step.

The conductive pattern obtained by the method for producing a conductive pattern of the present invention is a composite of an organic component and an inorganic component, and the conductive fillers D contained in the photosensitive conductive paste of the present invention are cured. Conductivity is exhibited by contact with each other by curing shrinkage.

Siloxane compound A refers to a compound having a siloxane bond in the molecule. By using such siloxane compound A, the photosensitive conductive paste of the present invention has improved conductivity and hardness at low temperatures. Examples of the siloxane compound A include dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen silicone oil, polysiloxane, and the like. Among these, polysiloxane is preferable.

Polysiloxane includes polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, polyester-modified methylalkylpolysiloxane, polyether-modified polymethylalkylsiloxane, aralkyl-modified polymethylalkylsiloxane, or a part of the above siloxane compound with epoxy group, hydroxyl group , A mercapto group, an isocyanate group, a carboxyl group, a fluoroalkyl group, an aralkyl group, a long-chain alkyl group, a substituent having a urethane bond, or a substituent having an unsaturated double bond (for example, an acrylic group or a methacryl group), And a compound substituted with any of a substituent having an unsaturated double bond, a substituent having a urethane bond, a carboxyl group, a hydroxyl group, an aralkyl group, or a fluoroalkyl group. Arbitrariness. When the siloxane compound A has an unsaturated double bond, it reacts with the photosensitive component in the exposed area in the exposure process, thereby increasing the solubility difference in the developing solution between the unexposed area and the exposed area, thereby increasing the patterning property. preferable. Further, when the siloxane compound A has a carboxyl group or a hydroxyl group, a condensation reaction is caused at the time of curing, and as a result, the contact probability between the conductive fillers is improved and the conductivity is easily developed. It is preferable to have an alkyl group or a urethane bond, since the hydrophilicity and hydrophobicity are suitable, the difference in solubility between the unexposed area and the exposed area in the developer is increased, and the patterning property is increased. Furthermore, since the siloxane compound A has an unsaturated double bond, a carboxyl group, a hydroxyl group, an aralkyl group, or a fluoroalkyl group, the surface hardness of the resulting conductive pattern can be increased.

The addition amount of the siloxane compound A is preferably 0.01 to 200 parts by weight, more preferably 0.02 to 100 parts by weight with respect to 100 parts by weight of the compound B. When the addition amount with respect to 100 parts by weight of Compound B is 0.01 parts by weight or more, the patterning property and the surface hardness are improved. On the other hand, flexibility is maintained when the addition amount with respect to 100 parts by weight of Compound B is 100 parts by weight or less.

Compound B having an acid value of 30 to 250 mg / KOH (hereinafter sometimes simply referred to as “Compound B”) can have an alkali solubility within an appropriate range by taking such an acid value range. In the development step after the coating film obtained by applying the photosensitive conductive paste of the present invention is exposed, the difference in solubility between the exposed portion and the unexposed portion is widened and fine processing becomes possible. When the acid value is less than 30 mg / KOH, the solubility of the soluble part is lowered in the development step after the coating film obtained by applying the photosensitive conductive paste is exposed. On the other hand, when the acid value exceeds 250 mgKOH / g, the allowable development width becomes narrow. In addition, the acid value of the compound B can be measured according to JIS K 0070: 1992.

Examples of the compound B having an acid value of 30 to 250 mg / KOH include monomers, oligomers or polymers having one or more carboxyl groups in the molecule, or a mixture thereof. More specifically, an acrylic copolymer is mentioned, for example. Here, the acrylic copolymer refers to a copolymer containing an acrylic monomer as a copolymer component.

Examples of the acrylic monomer constituting the acrylic copolymer include acrylic acid (hereinafter referred to as AA), methyl acrylate, ethyl acrylate (hereinafter referred to as EA), 2-ethylhexyl acrylate, n-butyl acrylate, iso-butyl acrylate, iso- Propane acrylate, glycidyl acrylate, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, Nn-butoxymethyl acrylamide, N-isobutoxymethyl acrylamide, butoxytriethylene glycol acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, 2-hydroxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, isodexyl acrylate, isooctyl acrylate Lauryl acrylate, 2-methoxyethyl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate, trifluoroethyl acrylate, acrylamide, aminoethyl acrylate, phenyl acrylate, phenoxyethyl acrylate 1-naphthyl acrylate, 2-naphthyl acrylate, thiophenol acrylate, benzyl mercaptan acrylate, γ-methacryloxypropyltrimethoxysilane, allylated cyclohexyl diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol di Acrylate, ethylene glycol diacrylate, Diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, glycerol diacrylate, methoxylated cyclohexyl diacrylate, neopentyl glycol diacrylate , Propylene glycol diacrylate, polypropylene glycol diacrylate, triglycerol diacrylate, trimethylolpropane triacrylate, bisphenol A diacrylate, bisphenol F diacrylate, diacrylate of bisphenol A-ethylene oxide adduct, bisphenol F-ethylene oxide Diacrylate adduct, diacrylate of bisphenol A- propylene oxide adduct include epoxy acrylates and acrylic acid was added to diglycidyl ether of bisphenol compounds such as bisphenol A, bisphenol F. Moreover, the compound etc. which substituted the acryl group of the said acryl-type monomer by the methacryl group can be used preferably. Of these, epoxy acrylate is preferred.

An alkali-soluble acrylic copolymer having a carboxyl group can be obtained by using an unsaturated acid such as an unsaturated carboxylic acid other than acrylic acid and methacrylic acid as a copolymerization monomer. In the present invention, the term “unsaturated acid” is intended to include not only an unsaturated acid of the original meaning but also an acid anhydride of an unsaturated acid and a vinyl ester of an organic acid. Examples of the unsaturated acid used as the copolymerization monomer include unsaturated acids such as itaconic acid, crotonic acid, maleic acid, and fumaric acid, acid anhydrides of these unsaturated acids, vinyl acetate, and the like.

In addition to the unsaturated acid, the alkali-soluble acrylic copolymer having a carboxyl group may be styrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, α-methylstyrene, chloromethylstyrene or hydroxy. Styrenes such as methylstyrene, 1-vinyl-2-pyrrolidone and the like may be used as a part of the copolymerization monomer.
The acid value of the acrylic copolymer to be obtained can be adjusted depending on the amount of the copolymer component used (unsaturated acid or copolymer monomer other than unsaturated acid).

Moreover, it has a reactive unsaturated double bond in the side chain by reacting the carboxyl group of the acrylic copolymer with a compound having an unsaturated double bond such as glycidyl (meth) acrylate. An alkali-soluble acrylic copolymer is obtained.

The glass transition temperature (hereinafter referred to as Tg) of Compound B is preferably −10 to 60 ° C., and more preferably 10 to 40 ° C. When the Tg is −10 ° C. or higher, the coating film obtained by applying the photosensitive conductive paste can be dried to suppress the tackiness of the dried film. When the Tg is 10 ° C. or higher, the above drying The shape stability with respect to the temperature change of the film is increased. When the Tg is 60 ° C. or less, the conductive pattern produced from the photosensitive conductive paste has flexibility at room temperature, and when the Tg is 40 ° C. or less, the internal stress when the conductive pattern is bent. Can be mitigated, and particularly the occurrence of cracks can be suppressed. In addition, Tg of compound B can be calculated | required by a differential scanning calorimeter (DSC) measurement.

The photopolymerization initiator C refers to a compound that decomposes by absorbing light having a short wavelength such as ultraviolet rays or generates a radical by causing a hydrogen abstraction reaction. By using such a photopolymerization initiator C, the photosensitive conductive paste of the present invention increases the crosslink density in the exposed area by adding the photopolymerization initiator C and increases the alkali solubility difference. As a result, fine processing becomes possible. Examples of the photopolymerization initiator C include 1,2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyloxime)], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, Bis (2,4,6-trimethylbenzoyl) -phenyl-phosphine oxide, ethanone, 1- [9-ethyl-6-2 (2-methylbenzoyl) -9H-carbazol-3-yl] -1- (O— Acetyloxime), benzophenone, methyl o-benzoylbenzoate, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 4,4′-dichlorobenzophenone, 4-benzoyl-4 ′ -Methyl diphenyl ketone, dibenzyl ketone, fluorenone, 2,2'-diethoxyacetophe 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, pt-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethyl Thioxanthone, benzyl, benzyldimethyl ketal, benzyl-β-methoxyethyl acetal, benzoin, benzoin methyl ether, benzoin butyl ether, anthraquinone, 2-t-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzo Suberon, methyleneanthrone, 4-azidobenzalacetophenone, 2,6-bis (p-azidobenzylidene) cyclohexanone, 6-bis (p Azidobenzylidene) -4-methylcyclohexanone, 1-phenyl-1,2-butanedione-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2- (o-ethoxycarbonyl) oxime, 1-phenyl- Propanedione-2- (o-benzoyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime , Michler's ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, naphthalenesulfonyl chloride, quinolinesulfonyl chloride, N-phenylthioacridone, 4,4′-azobisisobutyronitrile , Diphenyl disulfide, ben Photoreducing dyes such as thiazole disulfide, triphenylphosphine, camphorquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, carbon tetrabromide, tribromophenylsulfone, benzoin peroxide, eosin or methylene blue and ascorbic acid or triethanol The combination with reducing agents, such as an amine, is mentioned.

The addition amount of the photopolymerization initiator C is preferably 0.05 to 30 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the compound B. When the added amount with respect to 100 parts by weight of Compound B is 5 parts by weight or more, the cured density of the exposed part of the photosensitive conductive paste increases, and the residual film ratio after development increases. On the other hand, when the added amount with respect to 100 parts by weight of compound B is 20 parts by weight or less, excessive light absorption of photopolymerization initiator C in the upper part of the coating film obtained by applying the photosensitive conductive paste is suppressed. The As a result, a decrease in adhesion with the substrate due to the manufactured conductive pattern having an inversely tapered shape is suppressed.

The photosensitive conductive paste of the present invention may contain a sensitizer together with the photopolymerization initiator C.

Examples of the sensitizer 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) Aminobenzal) acetone, 1,3-carbonylbis (4-diethylaminobenzal) acetone, 3,3-carbonylbis (7-diethylaminocoumarin), N-phenyl-N-ethylethanolamine, N-phenylethanolamine, N- Examples include tolyldiethanolamine, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, 3-phenyl-5-benzoylthiotetrazole or 1-phenyl-5-ethoxycarbonylthiotetrazole, or a mixture of these sensitizers.

The addition amount of the sensitizer is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of Compound B. Photosensitivity improves enough that the addition amount with respect to 100 weight part compound B is 0.1 weight part or more. On the other hand, when the added amount with respect to 100 parts by weight of Compound B is 10 parts by weight or less, excessive light absorption of the photopolymerization initiator C in the upper part of the coating film obtained by applying the photosensitive conductive paste is suppressed. . As a result, a decrease in adhesion with the substrate due to the manufactured conductive pattern having an inversely tapered shape is suppressed.

Examples of the conductive filler D include silver (Ag), gold (Au), copper (Cu), platinum (Pt), lead (Pb), tin (Sn), nickel (Ni), aluminum (Al), and tungsten. (W), molybdenum (Mo), chromium (Cr), metals such as titanium (Ti) or indium (In) or alloys thereof, or tin oxide, tin oxide (SnO ₂ ) -antimony (Sb) dope, Examples include particles of indium oxide (In ₂ O ₃ ) -tin oxide dope, metal oxides such as ruthenium oxide (RuO ₂ ), or a mixture of these particles. From the viewpoint of conductivity, particles of Ag, Cu, or Au are preferable. From the viewpoints of cost and stability, Ag particles are more preferable. By using the conductive filler D, the conductivity of the photosensitive conductive paste of the present invention is exhibited.

The volume average particle diameter of the conductive filler D is preferably from 0.1 to 10 μm, more preferably from 0.5 to 6 μm. When the volume average particle diameter is 0.1 μm or more, the contact probability between the conductive fillers in the curing step is improved, and the specific resistivity and the disconnection probability of the manufactured conductive pattern are lowered. Furthermore, in the exposure process, the exposure light can smoothly pass through the coating film obtained by applying the photosensitive conductive paste, facilitating fine patterning. On the other hand, when the volume average particle diameter is 10 μm or less, the surface smoothness, pattern accuracy, and dimensional accuracy of the manufactured conductive pattern are improved. The volume average particle diameter can be measured by a Coulter counter method.

The amount of the conductive filler D added is preferably 70 to 95% by weight, more preferably 80 to 90% by weight, based on the total solid content in the photosensitive conductive paste. When the addition amount with respect to the total solid content is 70% by weight or more, the contact probability between the conductive fillers D in the curing process is improved, and the specific resistivity and the disconnection probability of the manufactured conductive pattern are lowered. On the other hand, when the addition amount with respect to the total solid content is 95% by weight or less, the exposure light can smoothly pass through the coating film obtained by applying the photosensitive conductive paste in the exposure step, and fine patterning is performed. Becomes easy. Here, the total solid content means all components of the photosensitive conductive paste excluding the solvent when the photosensitive conductive paste contains a solvent.

The photosensitive conductive paste of the present invention may contain a solvent. Examples of the solvent include N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethyl sulfoxide, γ-butyrolactone, ethyl lactate, 1-methoxy-2-propanol. 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate or propylene glycol monomethyl ether acetate, or a mixture of these solvents. It is done.

The photosensitive conductive paste of the present invention is a non-photosensitive polymer or plasticizer having no unsaturated double bond, leveling agent, surfactant, silane coupling agent, erasing agent, as long as the desired properties are not impaired. You may contain additives, such as a foaming agent or a pigment.

Examples of the non-photosensitive polymer include an epoxy resin, a novolac resin, a phenol resin, a polyimide precursor, or a closed ring polyimide.

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

Examples of the leveling agent include a special vinyl polymer or a special acrylic polymer.

Examples of the silane coupling agent include methyltrimethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and vinyltrimethoxysilane. Methoxysilane is mentioned.

The photosensitive conductive paste is produced, for example, using a dispersing machine or a kneader such as a three-roller, a ball mill or a planetary ball mill.

Next, a method for producing a conductive pattern using the photosensitive conductive paste of the present invention will be described. The manufacturing method of a conductive pattern using the photosensitive conductive paste of the present invention includes the following steps. Applying the photosensitive conductive paste of the present invention on a substrate to obtain a coating film, coating process, drying the coating film obtained, drying process, pattern exposure of the coating film after drying, exposure process, after exposure A development step of developing the coating film to form a desired pattern on the substrate, and a curing step of curing the obtained pattern at 100 to 300 ° C. to obtain a conductive pattern.

Examples of the substrate include polyethylene terephthalate film (hereinafter referred to as PET film), polyimide film, polyester film or aramid film, epoxy resin substrate, polyetherimide resin substrate, polyetherketone resin substrate, polysulfone resin substrate, glass. A substrate, a silicon wafer, an alumina substrate, an aluminum nitride substrate, or a silicon carbide substrate can be used.

Examples of the method for applying the photosensitive conductive paste on the substrate include spin coating using a spinner, spray coating, roll coating, screen printing, or coating using a blade coater, die coater, calendar coater, meniscus coater, or bar coater. Is mentioned. The film thickness of the coating film to be obtained may be appropriately determined according to the coating method or the total solid content concentration or viscosity of the photosensitive conductive paste, but the film thickness after drying should be 0.1 to 50 μm. Is preferred. The film thickness can be measured using a stylus type step meter such as “Surfcom” (registered trademark) 1400 (manufactured by Tokyo Seimitsu Co., Ltd.). More specifically, the film thickness at three random positions may be measured with a stylus-type step gauge (length measurement: 1 mm, scanning speed: 0.3 mm / sec), and the average value may be defined as the film thickness. it can.

Examples of the method for drying the obtained coating film (including the case where the photosensitive conductive paste contains a solvent includes volatilization and removal of the solvent) include, for example, heating drying using an oven, a hot plate, infrared rays, or vacuum drying or vacuum drying. It is done. The heating temperature is preferably 50 to 180 ° C., and the heating time is preferably 1 minute to several hours.

The dried coating film is exposed by a photolithography method. As a light source for exposure, i-line (365 nm), h-line (405 nm) or g-line (436 nm) of a mercury lamp is preferable.

The desired pattern is obtained by developing the exposed coating film using a developer and dissolving and removing unexposed portions.

Examples of the developer used for alkali development include tetramethylammonium hydroxide, diethanolamine, diethylaminoethanol, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, diethylamine, methylamine, dimethylamine, and dimethyl acetate. An aqueous solution of aminoethyl, dimethylaminoethanol, dimethylaminoethyl methacrylate, cyclohexylamine, ethylenediamine or hexamethylenediamine may be mentioned. These aqueous solutions include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N— Polar solvents such as dimethylacetamide, dimethylsulfoxide or γ-butyrolactone, alcohols such as methanol, ethanol or isopropanol, lactic acid ester Esters such as Le or propylene glycol monomethyl ether acetate, may be added to cyclopentanone, cyclohexanone, ketones such as isobutyl ketone or methyl isobutyl ketone or surfactant.

Examples of the developer for organic development include N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide or hexamethylphosphoryl Examples thereof include polar solvents such as amides or mixed solvents of these polar solvents with methanol, ethanol, isopropyl alcohol, xylene, water, methyl carbitol or ethyl carbitol.

As a development method, for example, a method of spraying a developer onto the coating film surface while the substrate is left standing or rotating, a method of immersing the substrate in the developer, or an ultrasonic wave while immersing the substrate in the developer The method of applying is mentioned.

The pattern obtained by development may be rinsed with a rinse solution. Examples of the rinsing liquid include water or an aqueous solution in which an alcohol such as ethanol or isopropyl alcohol or an ester such as ethyl lactate or propylene glycol monomethyl ether acetate is added to water.

As a method for curing the obtained pattern, for example, heating drying or vacuum drying using an oven, an inert oven, a hot plate, infrared rays, or the like can be given.

The temperature during curing (hereinafter sometimes simply referred to as “curing temperature”) is 100 to 300 ° C. When the curing temperature is less than 100 ° C., the volume shrinkage of the resin does not increase and the specific resistivity cannot be reduced. On the other hand, when the curing temperature exceeds 300 ° C., a conductive pattern cannot be formed on a material such as a substrate having low heat resistance. From this viewpoint, the curing temperature is preferably 120 to 180 ° C.

The conductive pattern manufactured using the photosensitive conductive paste of the present invention is suitably used as a peripheral wiring for a touch panel. Examples of the touch panel system include a resistive film type, an optical type, an electromagnetic induction type, and a capacitance type. However, since the capacitance type touch panel particularly requires fine wiring, the photosensitive conductive paste of the present invention. The conductive pattern manufactured using is more preferably used.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. In addition, the material and evaluation method which were used by each Example and the comparative example are as follows. In addition, the measurement n number was performed by 1 unless otherwise indicated.

<Patternability evaluation method>
The photosensitive conductive paste was applied onto a PET film (thickness: 100 μm) by a screen printing method so that the thickness of the dried film was 7 μm, and the obtained coated film was dried in a drying oven at 100 ° C. for 5 minutes. A group of straight lines arranged in a constant line and space (hereinafter referred to as L / S), that is, a translucent pattern, is defined as one unit, and after drying through a photomask having 11 types of units having different L / S values. The coating film was exposed and developed to obtain patterns having different L / S values. Thereafter, all of the obtained 11 patterns were cured in a drying oven at 140 ° C. for 30 minutes to obtain conductive patterns having different L / S values. The L / S value of each unit included in the photomask is 500/500, 250/250, 100/100, 50/50, 40/40, 30/30, 25/25, 20/20, 17 / 17, 15/15, and 10/10 (representing line width (μm) / interval (μm), respectively). The obtained conductive pattern is observed with an optical microscope, a conductive pattern having no residue between the patterns and having no pattern peeling is confirmed, and the L / S value can be developed. The value was / S. The exposure was performed using an exposure apparatus (PEM-6M; manufactured by Union Optics Co., Ltd.) for full line exposure with an exposure amount of 200 mJ / cm ² (wavelength 365 nm conversion), and development was performed with 0.25 wt% sodium carbonate (Na ₂ The substrate was immersed in an aqueous solution of CO ₃ ) for 30 seconds, and then rinsed with ultrapure water.

<Evaluation method of specific resistivity>
The photosensitive conductive paste was applied onto a PET film (thickness: 100 μm) by a screen printing method so that the thickness of the dried film was 7 μm, and the obtained coated film was dried in a drying oven at 100 ° C. for 5 minutes. The dried coating film was exposed and developed through a photomask having a light-transmitting portion A having the pattern shown in FIG. 1 to obtain a pattern. Thereafter, the obtained pattern was cured in a drying oven at 140 ° C. for 30 minutes to obtain a conductive pattern for measuring specific resistivity. The line width of the conductive pattern for specific resistivity measurement was 0.400 mm, and the line length was 80 mm. The exposure and development conditions were the same as in the patterning evaluation method. The surface resistance value was measured by connecting a surface resistance meter to each end of the obtained conductive pattern for measuring specific resistivity, and the specific resistivity was calculated based on the following formula (1).
Specific resistivity = surface resistance value × film thickness × line width / line length (1)
The line width is an average value obtained by observing the line width at three random positions with an optical microscope and analyzing the image data.

<Flexibility evaluation method>
FIG. 2 is a diagram schematically showing a sample used for the flexibility test. A photosensitive conductive paste is applied to a rectangular PET film (thickness 40 μm) having a length of 10 mm and a width of 100 mm by a screen printing method so that the thickness of the dry film becomes 7 μm, and the obtained coating film is dried in a drying oven at 100 ° C. For 5 minutes. A photomask having a light-transmitting portion A having the pattern shown in FIG. 1 was placed, exposed and developed so that the light-transmitting portion A was at the center of the sample, and a pattern was obtained. Then, it was cured in a drying oven at 140 ° C. for 30 minutes to obtain a conductive pattern. The exposure and development conditions were the same as in the patterning evaluation method. After measuring the resistance value of the obtained conductive pattern using a tester, the bending operation of bending the conductive pattern alternately inside and outside and bringing the sample short side B and the sample short side C into contact is repeated 100 times. The resistance value of the conductive pattern was measured again using a tester. The change amount of the resistance value before and after the bending operation was 20% or less and the conductive pattern was not cracked, peeled off or disconnected, was determined as A (good), and the other change was determined as B (poor).

<Method for evaluating adhesion to indium tin oxide (ITO)>
A photosensitive conductive paste was applied onto a PET film with ITO “ELECRYSTA” (registered trademark) V270L-TFS (manufactured by Nitto Denko Corporation) by a screen printing method so that the film thickness of the dried film was 7 μm. The coating film was dried in a drying oven at 100 ° C. for 5 minutes, and then the entire surface was exposed. The exposure conditions were the same as in the patterning evaluation method. Then, after curing in a drying oven at 140 ° C. for 30 minutes, a 1 mm wide, 10 × 10 grid pattern was cut with a cutter, and a constant temperature and humidity chamber SH-661 (Espec (85 ° C., 85% RH) For 240 hours. Cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the whole cut-out cut portion of the sample taken out and peeled off, and the number of remaining cells was counted.

<Evaluation method of surface hardness>
A photosensitive conductive paste is applied onto a glass substrate by screen printing so that the dry film thickness is 7 μm, and the resulting coating film is dried in a drying oven at 100 ° C. for 5 minutes, and then the entire surface is exposed. did. The exposure conditions were the same as in the patterning evaluation method. Then, it was cured in a drying oven at 140 ° C. for 30 minutes, and the surface hardness of the obtained conductive film was measured. In addition, the surface hardness of the electrically conductive film was measured based on JISK5600: 1999.

The materials used in the examples and comparative examples are as follows.

[Siloxane Compound A]
As shown in Synthesis Examples 1 to 5 below, siloxane compounds A-1 to A-5 were prepared.
(Synthesis Example 1)
A 300 mL eggplant flask was charged with 23.23 g of p-aminobenzoic acid and 209.05 g of propylene glycol monomethyl ether acetate (PGMEA), stirred at room temperature for 30 minutes, and then 46.53 g of isocyanate propyltriethoxysilane and 1.19 g of dibutyltin dilaurate was further added and stirred in an oil bath at 70 ° C. for 1 hour. Thereafter, the mixture was allowed to cool to room temperature, and the precipitated solid was collected by filtration with a glass filter and dried to obtain 46.7 g of a carboxyl group-containing siloxane compound (A-1).
(Synthesis Example 2)
In a 500 mL three-necked flask, 17.03 g of methyltrimethoxysilane (0.125 mol), 19.83 g of phenyltrimethoxysilane (0.1 mol), 38.42 g of a carboxyl group-containing silane compound (A-1; 1 mol), 41.02 g of γ-acryloylpropyltrimethoxysilane (0.175 mol) and 109.61 g of diethylene glycol monoethyl ether acetate (hereinafter referred to as DMEA) were placed in an oil bath at 40 ° C. and stirred, An aqueous phosphoric acid solution in which 0.237 g of phosphoric acid (0.2 part by weight with respect to 100 parts by weight of charged monomer) was dissolved in 27.0 g was added over 10 minutes with a dropping funnel. After stirring at 40 ° C. for 1 hour, the oil bath temperature was set to 70 ° C. and stirred for 1 hour, and the oil bath was further heated to 115 ° C. over 30 minutes. One hour after the start of temperature increase, the internal temperature of the three-necked flask reached 100 ° C., and from that point, the mixture was heated and stirred for 2 hours (the internal temperature of the three-necked flask changed at 100 to 110 ° C.). During the reaction, a total of 55 g of methanol, ethanol and water as by-products were distilled out. DMEA was added to the obtained siloxane compound solution so that the siloxane compound concentration was 40% by weight to obtain a siloxane compound solution (A-2).
(Synthesis Example 3)
In a 500 mL three-necked flask, 54.48 g (0.40 mol) methyltrimethoxysilane, 79.32 g (0.40 mol) phenyltrimethoxysilane, 77.32 g (0.20 mol) hydroxymethyltriethoxysilane 50 wt. % Ethanol solution and 118.32 g of DMEA were charged, and 0.345 phosphoric acid (0.2 parts by weight with respect to 100 parts by weight of charged monomer) was dissolved in 54 g of water while being immersed in an oil bath at 40 ° C. and stirred. The aqueous phosphoric acid solution was added with a dropping funnel over 10 minutes. After stirring at 40 ° C. for 1 hour, the oil bath temperature was set to 70 ° C. and stirred for 1 hour, and the oil bath was further heated to 115 ° C. over 30 minutes. One hour after the start of temperature increase, the internal temperature of the three-necked flask reached 100 ° C., and from that point, the mixture was heated and stirred for 2 hours (the internal temperature of the three-necked flask changed at 100 to 110 ° C.). During the reaction, a total of 165 g of methanol, ethanol and water as by-products were distilled out. DMEA was added to the obtained siloxane compound solution so that the concentration of the siloxane compound was 40% by weight to obtain a hydroxyl group-containing siloxane compound solution (A-3).
(Synthesis Example 4)
In a 500 mL three-necked flask, 54.48 g (0.40 mol) methyltrimethoxysilane, 98.51 g (0.50 mol) phenyltrimethoxysilane, 25.41 g (0.10 mol) 3-trimethoxysilylpropyl succinic acid Phosphoric acid in which 0.349 phosphoric acid (0.2 part by weight with respect to 100 parts by weight of the charged monomer) was dissolved in 54 g of water while adding anhydride and 74.68 g of DMEA, being immersed in an oil bath at 40 ° C. and stirring. The acid aqueous solution was added with a dropping funnel over 10 minutes. After stirring at 40 ° C. for 1 hour, the oil bath temperature was set to 70 ° C. and stirred for 1 hour, and the oil bath was further heated to 115 ° C. over 30 minutes. One hour after the start of temperature increase, the internal temperature of the three-necked flask reached 100 ° C., and from that point, the mixture was heated and stirred for 2 hours (the internal temperature of the three-necked flask changed at 100 to 110 ° C.). During the reaction, a total of 112.5 g of methanol, ethanol and water as by-products were distilled out. DMEA was added to the obtained siloxane compound solution so that the siloxane compound concentration was 40% by weight to obtain a carboxyl group-containing siloxane compound solution (A-4).
(Synthesis Example 5)
In a 500 mL three-necked flask, 54.48 g (0.40 mol) methyltrimethoxysilane, 79.32 g (0.40 mol) phenyltrimethoxysilane, 49.48 g (0.20 mol) 3-isocyanatopropyltriethoxysilane and An aqueous phosphoric acid solution prepared by dissolving 103.34 g of DMEA, dipping in an oil bath at 40 ° C. and stirring, dissolving 0.345 phosphoric acid (0.2 part by weight with respect to 100 parts by weight of the charged monomer) in 54 g of water, It was added over 10 minutes with a dropping funnel. After stirring at 40 ° C. for 1 hour, the oil bath temperature was set to 70 ° C. and stirred for 1 hour, and the oil bath was further heated to 115 ° C. over 30 minutes. One hour after the start of temperature increase, the internal temperature of the three-necked flask reached 100 ° C., and from that point, the mixture was heated and stirred for 2 hours (the internal temperature of the three-necked flask changed at 100 to 110 ° C.). During the reaction, a total of 125 g of methanol, ethanol and water as by-products were distilled out. DMEA was added to the resulting siloxane compound solution so that the siloxane compound concentration was 40% by weight to obtain a urethane bond-containing siloxane compound solution (A-5).
[Other siloxane compound A]
The following commercially available products (all manufactured by Big Chemie Japan Co., Ltd.) were prepared.
・ BYK-307
・ BYK-UV3500 (having an acrylic group)
.BYK-377 (having hydroxyl groups)
.BYK-322 (having an aralkyl group)
[Compound B having an acid value of 30 to 250 mg KOH]
B-1 to 5 were prepared as shown in Synthesis Examples 6 to 10 below.
(Synthesis Example 6)
In a nitrogen atmosphere reaction vessel, 150 g of DMEA was charged and heated to 80 ° C. using an oil bath. To this was added a mixture of 20 g EA, 40 g 2-ethylhexyl acrylate, 20 g styrene, 15 g AA, 0.8 g 2,2′-azobisisobutyronitrile and 10 g DMEA over 1 hour. And dripped. After completion of the dropping, a polymerization reaction was further performed for 6 hours. Thereafter, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. The obtained reaction solution was purified with methanol to remove unreacted impurities, and further vacuum-dried for 24 hours to obtain Compound (B-1). The resulting compound (B-1) had an acid value of 122 mgKOH / g and Tg of 17.7 ° C.
(Synthesis Example 7)
In a nitrogen atmosphere reaction vessel, 150 g of DMEA was charged and heated to 80 ° C. using an oil bath. To this, a mixture consisting of 50 g ethylene oxide modified bisphenol A diacrylate (FA-324A), 20 g EA, 15 g AA, 0.8 g 2,2′-azobisisobutyronitrile and 10 g DMEA, The solution was added dropwise over 1 hour. After completion of the dropping, a polymerization reaction was further performed for 6 hours. Thereafter, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. Subsequently, a mixture consisting of 5 g of glycidyl methacrylate, 1 g of triethylbenzylammonium chloride and 10 g of DMEA was added dropwise over 0.5 hours. After completion of the dropwise addition, an additional reaction was performed for 2 hours. The obtained reaction solution was purified with methanol to remove unreacted impurities, and further vacuum-dried for 24 hours to obtain compound (B-2). The acid value of the obtained compound (B-2) was 96 mgKOH / g, and Tg was 19.9 ° C.
(Synthesis Example 8)
In a reaction vessel, 200 g of epoxy ester 3000A (manufactured by Kyoeisha Chemical Co., Ltd .; epoxy acrylate compound having bisphenol A skeleton), 500 g of DMEA, 0.5 g of 2-methylhydroquinone (thermal polymerization inhibitor) 0.5 g And 75 g of dihydroxypropionic acid were charged and heated to 45 ° C. using an oil bath. To this, 84.1 g of hexamethylene diisocyanate was gradually added dropwise so that the reaction temperature did not exceed 50 ° C. After completion of the dropping, the reaction temperature was raised to 80 ° C., and after 6 hours, the reaction solution was analyzed by an infrared absorption spectrum measurement method, and it was confirmed that there was no absorption near 2250 cm ⁻¹ . After adding 165 g of glycidyl methacrylate to this reaction solution, the temperature was further raised to 95 ° C., and the reaction was performed for 6 hours to obtain a 51.2 wt% compound (B-3) solution. The resulting compound (B-3) had an acid value of 89 mgKOH / g and Tg of 27.2 ° C.
(Synthesis Example 9)
In a nitrogen atmosphere reaction vessel, 150 g of DMEA was charged and heated to 80 ° C. using an oil bath. To this was added a mixture of 30 g EA, 40 g 2-ethylhexyl acrylate, 20 g styrene, 5 g AA, 0.8 g 2,2′-azobisisobutyronitrile and 10 g DMEA over 1 hour. And dripped. After completion of the dropping, a polymerization reaction was further performed for 6 hours. Thereafter, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. The reaction solution thus obtained was purified with methanol to remove unreacted impurities, and further dried under vacuum for 24 hours to obtain compound (B-4). The obtained compound (B-4) had an acid value of 35 mgKOH / g and Tg of 10.2 ° C.
(Synthesis Example 10)
In a nitrogen atmosphere reaction vessel, 150 g of DMEA was charged and heated to 80 ° C. using an oil bath. To this was added a mixture of 20 g EA, 25 g 2-ethylhexyl acrylate, 20 g styrene, 30 g AA, 0.8 g 2,2′-azobisisobutyronitrile and 10 g DMEA over 1 hour. And dripped. After completion of the dropping, a polymerization reaction was further performed for 6 hours. Thereafter, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. The reaction solution obtained was purified with methanol to remove unreacted impurities, and further dried under vacuum for 24 hours to obtain Compound (B-5). The compound (B-5) obtained had an acid value of 222 mgKOH / g and Tg of 34.7 ° C.

[Photoinitiator C]
The following commercial products were prepared.
・ "IRGACURE" (registered trademark) 369 (manufactured by Ciba Japan Co., Ltd.)
[Conductive filler D]
The materials listed in Table 1 and those having a volume average particle size were used.

[Thermosetting compound E]
The following commercial products were prepared.
・ N-660 (manufactured by DIC Corporation) ・・・ Cresol novolac type epoxy resin ・ Nn-butoxymethylacrylamide [monomer]
The following commercial products were prepared.
・ Light acrylate BP-4EA (manufactured by Kyoeisha Chemical Co., Ltd.)
[solvent]
The following commercial products were prepared.
・ DMEA (manufactured by Tokyo Chemical Industry Co., Ltd.)
(Example 1)
In a 100 mL clean bottle, 1.0 g BYK-307, 10.0 g compound B-1, 0.50 g “IRGACURE” (registered trademark) 369, 2.0 g BP-4A, 5.0 g DMEA, The mixture was mixed using “Awatori Rentaro” (registered trademark) (ARE-310; manufactured by Sinky Corporation) as a mixer, and 16.5 g of a photosensitive resin solution (solid content: 69.7% by weight) was added. Obtained.

11.7 g of the photosensitive resin solution and 50.0 g of Ag particles (volume average particle diameter: 2 μm) were mixed and kneaded using a three-roller (EXAKT M-50; manufactured by EXAKT). 0.7 g of photosensitive conductive paste was obtained.

Using the obtained photosensitive conductive paste, the patterning property of the conductive pattern, the development margin, the specific resistivity, the flexibility, the adhesion with ITO, and the surface hardness were evaluated. The developable value L / S, which is an evaluation index of patterning property, was 17/17 μm, and it was confirmed that a good pattern was processed. The specific resistivity was 6.9 × 10 ⁻⁵ Ωcm, and good results were obtained for the flexibility. The surface hardness was 2H.

(Examples 2 to 14)
Table 2 shows the results of the same evaluation as in Example 1 using the photosensitive conductive paste having the composition shown in Table 1.

(Comparative Examples 1 to 3)
Table 2 shows the results of the same evaluation as in Example 1 using the photosensitive conductive paste having the composition shown in Table 1.

The photosensitive conductive pastes of Examples 1 to 12 were all excellent in patterning property and surface hardness, but the photosensitive conductive pastes of Comparative Examples 1 to 3 were all inferior in surface hardness.

A Translucent part B, C Sample short side D Conductive pattern E PET film

The photosensitive conductive paste of the present invention can be suitably used for manufacturing conductive patterns such as peripheral wiring for touch panels.

Claims

Siloxane compound A;
Compound B having an acid value of 30 to 250 mg / KOH,
Photopolymerization initiator C;
A photosensitive conductive paste comprising a conductive filler D.
The photosensitive conductive paste according to claim 1, wherein the compound B has an unsaturated double bond.
3. The photosensitive conductive paste according to claim 1, wherein the compound B has a glass transition temperature of −10 to 60 ° C.
The photosensitive conductive paste according to any one of claims 1 to 3, wherein the compound B is an epoxy acrylate.
The siloxane compound A has a substituent selected from the group consisting of a substituent having an unsaturated double bond, a substituent having a urethane bond, a carboxyl group, a hydroxyl group, an aralkyl group, and a fluoroalkyl group. The photosensitive electrically conductive paste as described in any one of these.
The photosensitive conductive paste according to any one of claims 1 to 5, wherein the siloxane compound A has a substituent selected from the group consisting of a carboxyl group, a hydroxyl group, and a substituent having a urethane bond.
The photosensitive conductive paste according to any one of claims 1 to 6, comprising a thermosetting compound E.
The photosensitive conductive paste according to any one of claims 1 to 7, wherein the thermosetting compound E has an alkoxy group or an epoxy group.
The photosensitive conductive paste according to any one of claims 1 to 8, wherein the addition amount of the conductive filler D is 70 to 95% by weight with respect to the total solid content in the photosensitive conductive paste.
A coating step of coating the photosensitive conductive paste according to any one of claims 1 to 9 on a substrate to obtain a coating film;
Drying the coating film, and a drying step;
An exposure step of pattern-exposing the coating film after drying; and
Developing the coating film after exposure to form a pattern on the substrate; and
And a curing step of curing the pattern at 100 to 300 ° C. to obtain a conductive pattern.