JP2015063590A - Conductive paste composition and fired body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive paste composition excellent in adhesion to a base material after drying, and a fired body obtained by firing the conductive paste composition.SOLUTION: The conductive paste composition is prepared by blending: a polyurethane resin obtained by reacting at least a polyoxyalkylene glycol containing a C2-C6 alkylene group with a diisocyanate; a solvent; a conductive powder; a coupling agent; and a blocked isocyanate. The fired body is produced by firing the conductive paste composition.

Description

  The present invention relates to a conductive paste composition and a fired body, and more particularly to a conductive paste composition and a fired body obtained by firing the conductive paste composition.

  Conventionally, various electronic parts are coated (printed) on the surface of a substrate with metal paste such as aluminum paste, silver paste, copper paste, and various ceramics (metal oxide) paste, and then dried. Electrodes from which organic components have been removed by firing have been used.

  For example, in a solar cell, a surface paste is formed by applying and baking a silver paste on the light receiving surface (front surface) of a semiconductor substrate, for example, by screen printing, and further aluminum on the back surface of the semiconductor substrate. It is known that a back electrode is formed by applying a paste and a silver paste by, for example, a screen printing method, and baking, and as such a conductive paste, a conductive metal powder and an organic material such as ethyl cellulose are used. A conductive paste containing an organic vehicle in which a binder is dissolved in an organic solvent and glass frit has been proposed (for example, see Patent Document 1).

  Further, in such a conductive paste, it has been proposed to use a polyurethane resin as an organic binder in order to suppress the dripping of the paste at the time of drying and reduce the residue at the time of binder removal (for example, (See Patent Document 2).

JP 2007-026934 A JP 2010-238614 A

  However, conductive paste containing ethyl cellulose or polyurethane resin as an organic binder may not have sufficient adhesion to the substrate after drying, and part of the conductive paste after drying may peel off from the substrate. There is.

  Specifically, for example, in the manufacture of a solar cell, first, the aluminum paste is printed (applied) and dried with the back surface side of the silicon wafer as the upper surface, and then the silicon wafer is turned over to apply the aluminum paste. The silver paste is printed (applied) on the surface (light-receiving surface) side and dried on the surface (light receiving surface) side, and then placed on a conveying device with the coated surface of the aluminum paste on the lower surface, and conveyed to a firing furnace.

  In such a solar cell manufacturing process, the dried aluminum paste rubs against the conveying device or the like, and a part of the aluminum paste may peel off before firing, and when a part of the aluminum paste peels off, There is a problem that the electric characteristics (current value, conversion efficiency, etc.) of the battery are lowered.

  An object of the present invention is to provide a conductive paste composition having excellent adhesion to a substrate after drying, and a fired body obtained by firing the conductive paste composition.

  In order to achieve the above object, the conductive paste composition of the present invention comprises a polyoxyalkylene glycol containing an alkylene group having 2 to 6 carbon atoms and a polyurethane resin obtained by reacting at least a diisocyanate, a solvent, It is characterized by containing at least conductive powder, a coupling agent, and blocked isocyanate.

  The conductive paste composition of the present invention preferably further contains a crosslinkable low molecular weight polyol having 3 or more hydroxyl groups in one molecule and having a molecular weight of 92 or more and 500 or less.

  In the conductive paste composition of the present invention, it is preferable that the polyoxyalkylene glycol is polytetramethylene ether glycol or an ethylene oxide / tetramethylene oxide copolymer.

  In the conductive paste composition of the present invention, the polyurethane resin is 0.5 to 20% by mass, the solvent is 9.48 to 69.48% by mass, and the conductive powder is based on the total amount of the conductive paste composition. 30 to 80% by mass, 0.01 to 10% by mass of a coupling agent, 0.01 to 10% by mass of a blocked isocyanate, and 0 to 10% by mass of a crosslinkable low molecular weight polyol. is there.

  In the conductive paste composition of the present invention, the conductive powder is preferably at least one selected from the group consisting of aluminum powder, silver powder, copper powder, platinum powder, palladium powder and nickel powder. .

  In the conductive paste composition of the present invention, the coupling agent is preferably an alkoxysilane compound having a primary amino group and an alkoxy group.

  In the conductive paste composition of the present invention, the blocked isocyanate is a blocked isocyanate obtained by the reaction of a hexamethylene diisocyanate multimer and a blocking agent, or a polyol-modified product obtained by polyol-modifying a biuret-modified product of hexamethylene diisocyanate. A blocked isocyanate obtained by a reaction with a blocking agent is preferred.

  Moreover, it is preferable that the electrically conductive paste composition of this invention contains low melting glass further.

  In addition, the fired body of the present invention is obtained by firing the above conductive paste composition.

  Since the conductive paste composition of the present invention contains a polyurethane resin obtained by a reaction between a specific polyoxyalkylene glycol and a diisocyanate, a solvent, a conductive powder, a coupling agent, and a blocked isocyanate, It is excellent in the adhesive force between the conductive paste composition after drying and the substrate, and the conductive paste composition can be prevented from peeling off after drying.

  Therefore, according to the fired body of the present invention in which the conductive paste composition of the present invention is used, it is possible to suppress a decrease in electrical characteristics due to peeling of the conductive paste.

  The paste composition of the present invention contains a polyurethane resin, a solvent, a powder, a coupling agent, and a blocked isocyanate.

  The polyurethane resin is obtained by reacting at least polyoxyalkylene glycol and diisocyanate.

  In the present invention, polyoxyalkylene glycol has an alkylene group having 2 to 6 carbon atoms.

  Examples of the alkylene group having 2 to 6 carbon atoms include an alkylene group having 2 to 3 carbon atoms and an alkylene group having 4 to 6 carbon atoms.

  Examples of the alkylene group having 2 to 3 carbon atoms include ethylene, propylene (methylethylene), trimethylene and the like.

  Examples of the alkylene group having 4 to 6 carbon atoms include linear alkylene groups such as tetramethylene, pentamethylene, and hexamethylene, and examples include 2-methyl-trimethylene, 1,1-dimethylethylene, 1,2- Such as dimethylethylene, 2-methyl-tetramethylene, 1,1-dimethyltrimethylene, 2,2-dimethyltrimethylene, 2-methyl-pentamethylene, 1,1-dimethyltetramethylene, 2,2-dimethyltetramethylene, etc. Examples include branched alkylene groups.

  If the alkylene group contains an alkylene group having 2 to 6 carbon atoms, the viscosity change of the polyurethane resin in the temperature range of 20 to 80 ° C. can be suppressed.

  Further, if the alkylene group contains an alkylene group having 4 to 6 carbon atoms, the solubility of the polyurethane resin in a solvent having a low polarity is improved, so that the polyurethane resin can be used as a good paste material. .

  If the alkylene group contains an alkylene group having 2 to 3 carbon atoms, the thermal decomposability of the polyurethane resin is further improved, so that the polyurethane resin can be used as a good baking paste material.

  In the present invention, the alkylene group preferably contains at least an alkylene group having 4 to 6 carbon atoms.

  Moreover, when an alkylene group contains a C2-C3 alkylene group and a C4-C6 alkylene group, those content rates are C2-C3 in polyoxyalkylene glycol. The alkylene group is, for example, 1 to 99 mol%, preferably 10 to 90 mol%, more preferably 30 to 70 mol%, and the alkylene group having 4 to 6 carbon atoms is, for example, 1 to 99 mol%. , Preferably, it is 10-90 mol%, More preferably, it is 30-70 mol%.

  In order to obtain the above polyoxyalkylene glycol, for example, an alkylene oxide having 2 to 6 carbon atoms is polymerized (homopolymerized or copolymerized).

  Examples of the alkylene oxide having 2 to 6 carbon atoms include alkylene oxide having 2 to 3 carbon atoms and alkylene oxide having 4 to 6 carbon atoms.

  Examples of the alkylene oxide having 2 to 3 carbon atoms include ethylene oxide (also known as ethylene oxide), propylene oxide, and trimethylene oxide. These can be used alone or in combination of two or more. Of these, ethylene oxide (ethylene oxide) is preferable.

  Examples of the alkylene oxide having 4 to 6 carbon atoms include linear alkylene oxides such as tetramethylene oxide (also known as tetrahydrofuran), pentamethylene oxide, and hexamethylene oxide, and examples thereof include 2-methyl-trimethylene oxide, 1, 1-dimethylethylene oxide, 1,2-dimethylethylene oxide, 2-methyl-tetramethylene oxide, 1,1-dimethyltrimethylene oxide, 2,2-dimethyltrimethylene oxide, 2-methyl-pentamethylene oxide, 1, Examples include branched alkylene oxides such as 1-dimethyltetramethylene oxide and 2,2-dimethyltetramethylene oxide. These can be used alone or in combination of two or more. Of these, tetramethylene oxide (tetrahydrofuran) and 2-methyl-tetramethylene oxide are preferable.

  The above-described polymerization of the alkylene oxide may be a known method (for example, living polymerization with an alkali metal or the like). The polymerization conditions are such that the polymerization temperature is, for example, 50 to 150 ° C., preferably 80 to 120. ° C. The polymerization time is, for example, 1 to 10 hours, preferably 2 to 7 hours.

  The polyoxyalkylene glycol obtained as described above can be obtained as a homopolymer or a copolymer.

  As the homopolymer, for example, polyethylene glycol obtained by addition reaction of alkylene oxide such as ethylene oxide and / or propylene oxide using a known initiator (for example, low molecular weight polyol, low molecular weight polyamine, etc.) And polypropylene glycol. Examples thereof include polytetramethylene ether glycol obtained by ring-opening polymerization of tetrahydrofuran.

  The low molecular weight polyol is a compound having two or more hydroxyl groups and a number average molecular weight of 500 or less. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butylene glycol, 1,3-butylene glycol 1,2-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, 3,3 Dimethylol heptane, alkane (C7-20) diol, 1,3- or 1,4-cyclohexanedimethanol and mixtures thereof, 1,3- or 1,4-cyclohexanediol and mixtures thereof, hydrogenated bisphenol A 1,4-dihydroxy-2-butene, 2,6-dimethyl Di-1-octene-3,8-diol, bisphenol A, dihydric alcohols such as diethylene glycol, triethylene glycol and dipropylene glycol, for example, trihydric alcohols such as glycerin, trimethylolpropane and triisopropanolamine, such as tetra Tetrahydric alcohols such as methylolmethane (pentaerythritol) and diglycerin, for example, pentahydric alcohols such as xylitol, for example, hexahydric alcohols such as sorbitol, mannitol, allitol, iditol, dulcitol, altritol, inositol, dipentaerythritol, For example, a 7-valent alcohol such as perseitol, an 8-valent alcohol such as sucrose, and a condensate thereof may be used. Examples of the condensate include condensates having a number average molecular weight in the above range (for example, polyethylene glycol, polypropylene glycol, etc.).

  These low molecular weight polyols can be used alone or in combination of two or more.

  The low molecular weight polyamine is a compound having two or more amino groups and a number average molecular weight of 500 or less, such as ethylenediamine, 1,3-propanediamine, 1,3- or 1,4-butanediamine, 1,6- Hexamethylenediamine, 1,4-cyclohexanediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophoronediamine), 4,4′-dicyclohexylmethanediamine, 2,5 (2,6) -bis ( Low molecular weight diamines such as aminomethyl) bicyclo [2.2.1] heptane, 1,3-bis (aminomethyl) cyclohexane, hydrazine, o, m or p-tolylenediamine (TDA, OTD), such as diethylenetriamine Low molecular weight triamines such as triethylenetetramine, tetraethylene A low molecular weight polyamine having an amino group such as Ntamin 4 or more can be mentioned.

  These low molecular weight polyamines can be used alone or in combination of two or more.

  These initiators can be used alone or in combination of two or more.

  Examples of the structure of the copolymer include a random structure and a block structure, and a random structure is preferable.

  Specific examples of polyoxyalkylene glycol copolymers include, for example, ethylene oxide / propylene oxide copolymers, ethylene oxide / tetramethylene oxide copolymers, ethylene oxide / pentamethylene oxide copolymers, ethylene oxide / Linear copolymer such as hexamethylene oxide copolymer, ethylene oxide / 2-methyl-trimethylene oxide copolymer, ethylene oxide / 1,1-dimethylethylene oxide copolymer, ethylene oxide 1,2- Examples include branched copolymers such as dimethylethylene oxide copolymer. Among these, Preferably, a linear copolymer is mentioned, More preferably, an ethylene oxide tetramethylene oxide copolymer is mentioned.

  The number average molecular weight (Mn) of the polyoxyalkylene glycol is, for example, more than 500, preferably 650 or more, more preferably 1000 or more, and usually, for example, 100,000 or less, preferably 20000 or less. More preferably, it is 10,000 or less, particularly preferably 3000 or less. The number average molecular weight (Mn) of the polyoxyalkylene glycol is determined according to JIS K1557-1 (2007) “Plastic-Polyurethane Raw Material Polyol Test Method—Part 1: Determination of Hydroxyl Value”. And the number of functional groups of the initiator).

  If the number average molecular weight of polyoxyalkylene glycol exceeds 500, a polyurethane resin having a length sufficient to obtain a uniform printed surface can be obtained. When the number average molecular weight of the polyoxyalkylene glycol is 100,000 or less, it is possible to obtain a polyurethane resin that can sufficiently accelerate the polymerization reaction and can substantially prevent the occurrence of stringing. In particular, if the number average molecular weight of the polyoxyalkylene glycol is 1000 or more, the blending ratio of diisocyanate can be reduced, and the amount of residual carbon when the resulting paste composition is fired at 400 ° C. or less is extremely reduced, A paste composition having higher thermal decomposability can be obtained.

  These polyoxyalkylene glycols can be used alone or in combination of two or more.

  Preferred examples of the polyoxyalkylene glycol include polytetramethylene ether glycol and ethylene oxide / tetramethylene oxide copolymer.

  By using these, it is possible to improve the adhesion to the substrate after drying the paste.

  In the polymerization of the polyurethane resin (reaction between polyoxyalkylene glycol and diisocyanate (described later)), the diol component (excluding polyoxyalkylene glycol (hereinafter the same)) is used as a reaction component and the polyoxyalkylene glycol described above. , And a diisocyanate to be described later. That is, the polyurethane resin can be obtained by reaction of polyoxyalkylene glycol and diisocyanate (described later) as essential reaction components with a diol component as an optional reaction component.

  The diol component is a compound having two hydroxyl groups and a number average molecular weight of 62 to 1000, preferably 62 to 120, such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, Tripropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, 2,4- Pentanediol, 2-methyl-1,2-butanediol, -Methyl-2,3-butanediol, 2-methyl-1,4-butanediol, 3-methyl-1,2-butanediol, 3-methyl-1,3-butanediol, 2-ethyl-1,3- Propanediol, 2,2-dimethyl-1,3-propanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 3,3-hexanediol 2-methyl-1,3-pentanediol, 2-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 3-methyl-2 , 3-pentanediol, 3-methyl-2,4-pentanediol, 4-methyl-1,2-pentanediol, 2-ethyl-2-methyl-1,3-propanedioe 2,2-dimethyl-2,4-butanediol, 2,3-dimethyl-1,2-butanediol, 1,2-heptanediol, 1,7-heptanediol, 3,4-heptanediol, 2-propyl 2-methyl-1,3-propanediol, 2-isopropyl-2-methyl-1,3-propanediol, 1,2-octanediol, 1,8-octanediol, 3,6-octanediol, 2- Ethyl-1,3-hexanediol, 2-sec-butyl-2-butyl-1,3-propanediol, 2,2-dimethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexane Diol, 2,2,4-trimethyl-1,3-pentanediol, 1,2-nonanediol, 1,3-nonanediol, 1,9-nonanediol, 3,6-octane Tandiol, 2-ethyl-2- (2-methyl) propyl-1,3-propanediol, 2,2,4-trimethyl-1,6-hexanediol, 2,4,4-trimethyl-1,6-hexane Diol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 1,2-decanediol, 1, 10-decanediol, 5,6-decanediol, 3,6-dimethyl-3,6-octanediol, 3,7-dimethyl-1,6-octanediol, 3,7-dimethyl-1,7-octanediol 1,2-undecanediol, 1,4-undecanediol, 1,11-undecanediol, 6-ethyl-3-methyl-1,6-octanediol, 1,2-dodecane Diol, 1,10-dodecanediol, 1,12-dodecanediol, 2,4-diethyl-1,5-octanediol, 2,8,8-trimethyl-2,7-nonanediol, 1,2-tetradecanediol 1,14-tetradecanediol, 7,8-tetradecanediol, 1,2-pentadecanediol, 1,2-hexadecanediol, 1,16-hexadecanediol, 1,17-heptadecanediol, 1,2-octadecanediol 1,12-octadecanediol, 1,2-eicosanediol, 1,2-docosanediol, saturated diols such as 1,2-tetracosanediol, or condensates thereof.

  Examples of the condensate include condensates having a number average molecular weight in the above range (for example, polyethylene glycol, polypropylene glycol, etc.).

  These diol components can be used alone or in combination of two or more.

  As the diol component, preferably, 1,4-butanediol is used.

  By copolymerizing these diol components, it is possible to improve the adhesion to the substrate after the conductive paste composition is dried.

  When the diol component is reacted with polyoxyalkylene glycol and diisocyanate, the blending ratio of the diol component is, for example, 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polyoxyalkylene glycol.

  In the present invention, examples of the diisocyanate include known diisocyanates usually used in the production of polyurethane resins.

  Specific examples of the diisocyanate include aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate.

  Examples of the aliphatic diisocyanate include methylene diisocyanate, ethylene diisocyanate, trimethylene diisocyanate, 1-methylethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 2-methylbutane-1,4-diisocyanate, hexamethylene diisocyanate (HMDI), and hepta. Methylene diisocyanate, 2,2′-dimethylpentane-1,5-diisocyanate, lysine diisocyanatomethyl ester (LDI), octamethylene diisocyanate, 2,5-dimethylhexane-1,6-diisocyanate, 2,2,4- Trimethylpentane-1,5-diisocyanate, nonamethylene diisocyanate, 2,4,4-trimethylhexane-1,6-diisocyanate DOO, decamethylene diisocyanate, undecamethylene diisocyanate, dodecamethylene diisocyanate, tridecamethylene diisocyanate, tetradecamethylene diisocyanate, pentamethylene decamethylene diisocyanate, hexamethylene decamethylene diisocyanate, trimethylhexamethylene diisocyanate.

Examples of the alicyclic diisocyanate include cyclohexane-1,2-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-methylcyclohexane-2,4-diisocyanate, and 1-methylcyclohexane-2. , 6-diisocyanate, 1-ethylcyclohexane-2,4-diisocyanate, 4,5-dimethylcyclohexane-1,3-diisocyanate, 1,2-dimethylcyclohexane-ω, ω'-diisocyanate, 1,4-dimethylcyclohexane- ω, ω′-diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate, dicyclohexylmethylmethane-4,4′-diisocyanate, dicyclohexyldimethyl Rumethane-4,4′-diisocyanate, 2,2′-dimethyldicyclohexylmethane-4,4′-diisocyanate, 3,3′-dimethyldicyclohexylmethane-4,4′-diisocyanate, 4,4′-methylene-bis ( Isocyanatocyclohexane), isopropylidenebis (4-cyclohexylisocyanate) (IPCI), 1,3-bis (isocyanatomethyl) cyclohexane, hydrogenated tolylene diisocyanate (H-TDI), hydrogenated 4,4′-diphenylmethane diisocyanate (H ₁₂ MDI), hydrogenated xylylene diisocyanate (H ₆ XDI), norbornane diisocyanatomethyl (NBDI) and the like.

  Examples of the aromatic diisocyanate include 1,3- and 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate (2,4-TDI), 1-methyl-2,6-phenylene diisocyanate (2 , 6-TDI), 1-methyl-2,5-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, m-xylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene Diisocyanate, 1-methyl-3,5-diethylbenzene-2,4-diisocyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3,5-triethylbenzene-2,4-diisocyanate, naphthalene -1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methylnaphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7-diisocyanate, 1,1-dinaphthyl-2, 2'-diisocyanate, biphenyl-2,4'-diisocyanate, biphenyl-4,4'-diisocyanate, 1,3-bis (1-isocyanato-1-methylethyl) benzene, 3,3'-dimethylbiphenyl-4, 4'-diisocyanate, diphenylmethane , 4'-diisocyanate (MDI), diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, and the like xylylene diisocyanate (XDI).

  These diisocyanates can be used alone or in combination of two or more. Of these diisocyanates, alicyclic diisocyanates are preferable, and HMDI is more preferable.

  When the alicyclic diisocyanate is used, the residue of the polyurethane resin can be reduced at the time of firing the conductive paste composition. Moreover, when HMDI is used, the printability (spinning property) of the conductive wire paste composition can be improved.

  And a polyurethane resin is obtained by making the above-mentioned polyoxyalkylene glycol, diisocyanate, and said diol component react as needed.

  In this reaction, the equivalent ratio of the isocyanate group of the diisocyanate (NCO group / OH group) to the hydroxyl group of the polyoxyalkylene glycol and optionally included diol component is, for example, 0.8 to 1.1, preferably 0.85 to 1.05.

  The reaction conditions may be those usually used in the production of polyurethane resins. For example, in a nitrogen atmosphere, polyoxyalkylene glycol, if necessary, the above diol component, and diisocyanate have the above equivalent ratio. For example, it is polymerized at 50 to 120 ° C. for 3 to 15 hours.

  In this reaction, the above-described components can be bulk polymerized as they are without blending a polymerization solvent, or, for example, a polymerization solvent can be blended and solution polymerization can be performed.

  Examples of the polymerization solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, nitriles such as acetonitrile, alkyl esters such as methyl acetate, ethyl acetate, butyl acetate and isobutyl acetate, for example, n- Aliphatic hydrocarbons such as hexane, n-heptane, octane and isooctane, for example, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, such as benzene, toluene (including dehydrated toluene), xylene, ethylbenzene and the like Aromatic hydrocarbons such as methyl cellosolve acetate, ethyl cellosolve acetate, methyl carbitol acetate, ethyl carbitol acetate, ethylene glycol ethyl ether acetate, propylene glycol Glycol ether esters such as tilether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate, for example, ethers such as diethyl ether, tetrahydrofuran, dioxane, such as methyl chloride, methylene chloride, Halogenated aliphatic hydrocarbons such as chloroform, carbon tetrachloride, methyl bromide, methylene iodide, dichloroethane, such as N-methylpyrrolidone, dimethylformamide, N, N′-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphonyl Examples include polar aprotic compounds such as amides.

  Moreover, the mixing ratio of the polymerization solvent in the case of solution polymerization is, for example, 300 to 1000 parts by mass with respect to 100 parts by mass of the total amount of polyoxyalkylene glycol and diisocyanate (including the diol component as necessary).

  Furthermore, in these reactions, a catalyst (for example, a tin-based catalyst such as dibutyltin dilaurate (DBTDL), an amine-based catalyst such as monoethanolamine, etc.), an antioxidant (for example, di-tert. Additives such as -butylhydroxytoluene (BHT) etc. can be added.

  The weight average molecular weight of the polyurethane resin thus obtained is, for example, 10,000 to 2,000,000, and preferably 50,000 to 1,000,000 from the viewpoint of printing characteristics. The weight average molecular weight of the polyurethane resin is a weight average molecular weight based on a calibration curve of standard polystyrene by gel permeation chromatography.

  When the weight average molecular weight of the polyurethane resin is 10,000 or more, the viscosity of the conductive paste composition (in particular, the silver conductive paste composition, the copper conductive paste composition, and the aluminum conductive paste composition) can be increased. Moreover, if a weight average molecular weight is 2000000 or less, it is between the screen and the printing surface at the time of screen printing of electrically conductive paste composition (especially silver electrically conductive paste composition, copper electrically conductive paste composition, and aluminum electrically conductive paste composition). Generation of stringing can be prevented. That is, in the above range, the printing characteristics of the paste composition can be improved.

  In addition, the hydroxyl value of the polyurethane resin is, for example, 0 to 11.3, preferably 0 to 2.3.

  Moreover, the isocyanate group content of a polyurethane resin is 0-1 mass%, for example, Preferably, it is 0-0.2 mass%.

  In the present invention, the solvent is not particularly limited as long as it can dissolve the polyurethane resin and can disperse the powder. Examples of such a solvent include 3 to 12 carbon atoms such as ethyl carbitol, butyl carbitol, terpineol (α-, β-, γ-, I-, IV-terpineol, etc.), dodecanol, isopropanol, butanol and the like. Alcohols such as 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol For example, ketones such as methyl ethyl ketone, methyl isobutyl ketone, propylene carbonate, such as dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dioctyl phthalate, ethyl acetate, butyl acetate, ethyl carbitol acetate, butyl carbitol acetate, etc. 3 to 12 carbon esters For example, ethers such as tetrahydrofuran, aromatic compounds such as toluene, xylene, benzyl alcohol, 2-phenoxyethanol, pyrrolidones such as N-methylpyrrolidone (NMP), such as dimethylformamide, dimethylsulfoxide, etc. Examples include aprotic polar solvents.

The solvent preferably has a low polarity so that the influence of the plate-making emulsion during screen printing is small, and a low-polarity powder such as a metal powder (described later) can be more uniformly dispersed. More specifically, the solubility parameter (Solubility Parameter: SP value) is, for example, 8 to 13 (cal / cm ³ ) ^1/2 .

  Among the solvents described above, examples of the solvent within the range of the solubility parameter include, for example, aromatic compounds such as toluene, xylene, benzyl alcohol and 2-phenoxyethanol, carbon numbers such as butyl carbitol, terpineol, dodecanol and butanol. Examples thereof include 4 to 12 alcohols, esters having 4 to 12 carbon atoms such as butyl carbitol acetate and diethyl phthalate, and pyrrolidones such as NMP. These can be used alone or in combination of two or more. Of these, butyl carbitol, terpineol, ethyl carbitol acetate, and butyl carbitol acetate are preferable.

  In the present invention, the conductive powder can be appropriately selected according to the use of the fired body described later, and examples thereof include powdered metal.

  Examples of the powder metal include metal powder and metal oxide powder.

  Examples of the metal powder include silver powder, copper powder, aluminum powder, platinum powder, palladium powder, and nickel powder.

  Examples of the metal oxide powder include tin oxide powder, nickel oxide powder, manganese oxide powder, and cobalt oxide powder.

  The powder metal includes a metal alloy powder formed from two or more selected from the above metal powder and the above metal oxide powder.

  Examples of the metal alloy powder include a silver-tin alloy powder, a silver-platinum alloy powder, a silver-palladium alloy powder, and a silver-aluminum alloy powder.

  These powdery metals can be used alone or in combination of two or more.

  As a powder metal, Preferably, metal powder, More preferably, silver powder, copper powder, aluminum powder, nickel powder is mentioned.

  The shape of these powdery metals varies depending on the production method and the like, but is, for example, spherical or flaky, and the average particle diameter is, for example, 0.1 μm to 100 μm, more preferably 0.5 μm to 10 μm. .

  When the average particle diameter of the powder metal is in the above range, the conductive paste composition can be reliably applied by screen printing or the like.

  In the present invention, as the coupling agent, for example, a reactive group (for example, a methoxy group, an ethoxy group, and a silanol group) chemically bonded to an inorganic substance, and a reactive group (for example, a vinyl group, an epoxy group, and a methacryl group) chemically bonded to an organic substance , An amino group, a mercapto group, etc.). Moreover, for example, an aluminum coupling agent such as acetoalkoxyaluminum diisopropylate, and a metal coupling agent such as a titanate coupling agent such as isopropyl triisostearoyl titanate are also included.

  These coupling agents can be used alone or in combination of two or more.

  The coupling agent is preferably a silane coupling agent, more preferably a silane coupling agent having a primary amino group and / or a secondary amino group and an alkoxy group, and having an epoxy group and an alkoxy group. Examples include silane coupling agents and silane coupling agents having a mercapto group and an alkoxy group.

  Specific examples of the silane coupling agent having a primary amino group and an alkoxy group include N-2 (aminoethyl) -3-aminopropylmethyldimethoxysilane and N-2 (aminoethyl) -3-amino. Examples include propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

  Examples of the silane coupling agent having a secondary amino group and an alkoxy group include N-phenyl-3-aminopropyltrimethoxysilane.

  Examples of the silane coupling agent having an epoxy group and an alkoxy group include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3- Examples thereof include glycidoxypropyltriethoxysilane.

  Examples of the silane coupling agent having a mercapto group and an alkoxy group include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

  As the silane coupling agent, a silane coupling agent having a primary amino group or a secondary amino group and an alkoxy group is more preferable, and a silane coupling agent having a primary amino group and an alkoxy group is particularly preferable. Agents.

  By using a silane coupling agent having a primary amino group and an alkoxy group, it is possible to improve adhesion to the substrate after drying the paste.

  The mixing ratio of the coupling agent is, for example, 0.01 to 30 parts by mass, preferably 0.1 to 3 parts by mass, and more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the conductive powder. It is.

  In the present invention, blocked isocyanate is defined as an isocyanate compound in which the blocking agent is separated by heating and the isocyanate group is regenerated.

  More specifically, the blocked isocyanate can be obtained, for example, by reacting a polyisocyanate component with a known blocking agent and blocking the isocyanate group of the polyisocyanate component with the blocking agent.

  Examples of the polyisocyanate component include diisocyanate and derivatives thereof.

  Examples of the diisocyanate include the above-described diisocyanates (such as aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate).

  Examples of the diisocyanate derivatives include, for example, the above-described diisocyanate monomer multimer (eg, dimer, trimer (eg, isocyanurate-modified, iminooxadiazinedione-modified), pentamer, and 7-mer). Body, etc.), allophanate modified body (for example, allophanate modified body produced by reaction of diisocyanate monomer and low molecular weight polyol as described above), polyol modified body (for example, polyol produced by reaction of diisocyanate monomer and polyol component) Modified products, etc.), biuret modified products (for example, biuret modified products produced by reaction of diisocyanate monomer with water or amines), urea modified products (eg, urea modified product produced by reaction of diisocyanate monomer and diamine). Etc.), Oxazi Modified gintrione (for example, oxadiazine trione generated by reaction of diisocyanate monomer and carbon dioxide), modified carbodiimide (modified carbodiimide generated by decarboxylation condensation reaction of diisocyanate monomer), modified uretdione, modified uretonimine Examples include the body.

  In addition, as the diisocyanate derivative, the above-mentioned modified products can be used in combination. Specifically, for example, a diisocyanate derivative (for example, biuret-modified product) and a polyol component are reacted, and the diisocyanate derivative can be further polyol-modified and used.

  Examples of the polyol component include low molecular weight polyols and high molecular weight polyols.

  Examples of the low molecular weight polyol include low molecular weight polyols similar to those used as an initiator for the polyoxyalkylene glycol described above.

  The high molecular weight polyol is a compound having two or more hydroxyl groups and a number average molecular weight exceeding 500, for example, polyether polyol, polyester polyol, polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, Examples include acrylic polyol and vinyl monomer-modified polyol.

  Preferred examples of the high molecular weight polyol include polyether polyols, polyester polyols, and polycarbonate polyols, and more preferred examples include polyether polyols.

  Examples of polyether polyols include the polyoxyalkylene glycols described above, and preferably polypropylene glycol.

  The number average molecular weight of the high molecular weight polyol is, for example, more than 500, preferably 1000 or more, for example, 10,000 or less, preferably 3000 or less.

  These polyol components can be used alone or in combination of two or more.

  As a polyol component, Preferably high molecular weight polyol is mentioned, More preferably, polyether polyol is mentioned, More preferably, polypropylene glycol is mentioned.

  In preparing the polyol-modified product, the reaction ratio of the polyisocyanate component and the polyol component is appropriately set according to the purpose and application.

  The blocking agent is not particularly limited as long as it is a blocking agent that is dissociated from isocyanate by heat treatment. For example, alcohol compounds, phenol compounds, active methylene compounds, amine compounds, imine compounds, oxime compounds, Examples include carbamic acid compounds, urea compounds, acid amide compounds (lactam compounds), acid imide compounds, triazole compounds, pyrazole compounds, imidazole compounds, imidazoline compounds, mercaptan compounds, and bisulfites. .

  Examples of the alcohol compound include methanol, ethanol, 2-propanol, n-butanol, s-butanol, 2-ethylhexyl alcohol, 1- or 2-octanol, cyclohexyl alcohol, ethylene glycol, benzyl alcohol, 2,2 , 2-trifluoroethanol, 2,2,2-trichloroethanol, 2- (hydroxymethyl) furan, 2-methoxyethanol, methoxypropanol, 2-ethoxyethanol, n-propoxyethanol, 2-butoxyethanol, 2-ethoxy Ethoxyethanol, 2-ethoxybutoxyethanol, butoxyethoxyethanol, 2-ethylhexyloxyethanol, 2-butoxyethylethanol, 2-butoxyethoxyethanol, N, N-dibutyl-2 Hydroxyacetamide, N-hydroxysuccinimide, N-morpholine ethanol, 2,2-dimethyl-1,3-dioxolane-4-methanol, 3-oxazolidineethanol, 2-hydroxymethylpyridine, furfuryl alcohol, 12-hydroxystearic acid, Examples include triphenylsilanol and 2-hydroxyethyl methacrylate.

  Examples of phenolic compounds include phenol, cresol, ethylphenol, n-propylphenol, isopropylphenol, n-butylphenol, s-butylphenol, t-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, n -Nonylphenol, di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-s-butylphenol, di-t-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n -Nonylphenol, nitrophenol, bromophenol, chlorophenol, fluorophenol, dimethylphenol, styrenated phenol, methyl salicyla , Methyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 2-ethylhexyl hydroxybenzoate, 4-[(dimethylamino) methyl] phenol, 4-[(dimethylamino) methyl] nonylphenol, bis (4-hydroxy Phenyl) acetic acid, pyridinol, 2- or 8-hydroxyquinoline, 2-chloro-3-pyridinol, pyridine-2-thiol and the like.

  Examples of the active methylene compound include Meldrum's acid, dialkyl malonate (for example, dimethyl malonate, diethyl malonate, di-n-butyl malonate, di-t-butyl malonate, di-2-ethylhexyl malonate, malonic acid. Methyl n-butyl, ethyl n-butyl malonate, methyl s-butyl malonate, ethyl s-butyl malonate, methyl t-butyl malonate, ethyl t-butyl malonate, diethyl methylmalonate, dibenzyl malonate, malon Diphenyl acid, benzyl methyl malonate, ethyl phenyl malonate, t-butylphenyl malonate, isopropylidene malonate, etc.), alkyl acetoacetate (eg methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, isopropyl acetoacetate) , N-butyl acetoacetate, acetoacetic acid - butyl acetoacetate benzyl, phenyl acetoacetate, etc.), 2-acetoacetoxyethyl methacrylate, acetylacetone, and the like such as ethyl cyanoacetate.

  Examples of the amine compound include dibutylamine, diphenylamine, aniline, N-methylaniline, carbazole, bis (2,2,6,6-tetramethylpiperidinyl) amine, di-n-propylamine, diisopropylamine, Isopropylethylamine, 2,2,4- or 2,2,5-trimethylhexamethyleneamine, N-isopropylcyclohexylamine, dicyclohexylamine, bis (3,5,5-trimethylcyclohexyl) amine, piperidine, 2,6 -Dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, (dimethylamino) -2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethyl-4-piperidine, 6- Examples include methyl-2-piperidine, 6-aminocaproic acid, etc. It is.

  Examples of the imine compound include ethyleneimine, polyethyleneimine, 1,4,5,6-tetrahydropyrimidine, guanidine and the like.

  Examples of oxime compounds include formaldehyde oxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, diacetyl monooxime, benzophenoxime, 2,2,6,6-tetramethylcyclohexanone oxime, diisopropyl ketone oxime. , Methyl t-butyl ketone oxime, diisobutyl ketone oxime, methyl isobutyl ketone oxime, methyl isopropyl ketone oxime, methyl 2,4-dimethylpentyl ketone oxime, methyl 3-ethyl heptyl ketone oxime, methyl isoamyl ketone oxime, n-amyl ketone Oxime, 2,2,4,4-tetramethyl-1,3-cyclobutanedione monooxime, 4,4′-dimethoxybenzophenone oxime, 2-he Tanon'okishimu and the like.

  Examples of the carbamic acid compound include phenyl N-phenylcarbamate.

  Examples of the urea compound include urea, thiourea, and ethylene urea.

  Examples of acid amide (lactam) compounds include acetanilide, N-methylacetamide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, pyrrolidone, 2,5-piperazinedione, laurolactam, and the like. It is done.

  Examples of the acid imide compound include succinimide, maleic imide, phthalimide, and the like.

  Examples of triazole compounds include 1,2,4-triazole and benzotriazole.

  Examples of the pyrazole compound include pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3, Examples include 5-dimethylpyrazole and 3-methyl-5-phenylpyrazole.

  Examples of the imidazole compound include imidazole, benzimidazole, 2-methylimidazole, 4-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2 -Phenylimidazole, 4-methyl-2-phenylimidazole and the like.

  Examples of the imidazoline-based compound include 2-methylimidazoline and 2-phenylimidazoline.

  Examples of mercaptan compounds include butyl mercaptan, dodecyl mercaptan, hexyl mercaptan, and the like.

  Examples of the bisulfite include sodium bisulfite.

  Moreover, as a blocking agent, it is not limited to the above, For example, other blocking agents, such as N, N'- diphenylformamidine, benzoxazolone, isatoic anhydride, tetrabutylphosphonium acetate, are mentioned.

  These blocking agents can be used alone or in combination of two or more.

  The blocking agent is appropriately selected in consideration of the dissociation temperature and stability.

  As the blocked isocyanate, a block isocyanate obtained by reaction of a block isocyanate, preferably a block isocyanate obtained by reaction of a multimer of hexamethylene diisocyanate with a blocking agent, a polyol modified form of a biuret modified of hexamethylene diisocyanate, and a blocking agent. Isocyanates.

  Moreover, as a blocking agent, Preferably, an oxime type compound is mentioned. That is, as the blocked isocyanate, more preferably, a blocked isocyanate obtained by a reaction between a hexamethylene diisocyanate multimer and an oxime compound, a polyol-modified product obtained by polyol-modifying a biuret-modified product of hexamethylene diisocyanate, and an oxime compound. The blocked isocyanate obtained by reaction is mentioned.

  By using these blocked isocyanates, it is possible to improve the adhesion to the substrate after drying the paste.

  The blocked isocyanate can be obtained according to a known method, for example, the method described in JP2011-236388A.

  The blending ratio of the blocked isocyanate is, for example, 0.01 to 30 parts by mass, preferably 0.1 to 3 parts by mass, more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the conductive powder. is there.

  The conductive paste composition of the present invention preferably has a crosslinkable low molecular weight polyol (hereinafter referred to as a crosslinkable low molecular weight polyol) having 3 or more hydroxyl groups in one molecule and having a molecular weight of 92 or more and 500 or less. ).

  As the crosslinkable low molecular weight polyol, specifically, for example, a crosslinkable low molecular weight polyol having three hydroxyl groups in one molecule (for example, trimethylolethane, trimethylolpropane, glycerin, etc.), a hydroxyl group in one molecule is used. Four crosslinkable low molecular weight polyols (eg, pentaerythritol, diglycerin, etc.) One crosslinkable low molecular weight polyol (eg, triglycerin, etc.) having five hydroxyl groups in one molecule, six hydroxyl groups in one molecule Crosslinkable low molecular weight polyol (for example, tetraglycerin etc.) etc. are mentioned.

  These crosslinkable low molecular weight polyols can be used alone or in combination of two or more.

  The blending ratio of the crosslinkable low molecular weight polyol is, for example, 33 parts by mass or less, preferably 10 parts by mass or less, and usually 0.1 parts by mass or more with respect to 100 parts by mass of the conductive powder.

  By blending the crosslinkable low molecular weight polyol, the adhesion of the conductive paste composition after drying to the substrate can be improved.

  That is, preferably, 0.1 to 10 parts by mass of a crosslinkable low molecular weight polyol having 3 to 6 hydroxyl groups in one molecule is added to 100 parts by mass of the conductive powder.

  Furthermore, the conductive paste composition of the present invention may contain an inorganic powder other than the conductive powder described above.

  Examples of the inorganic powder other than the conductive powder include a low-melting glass powder (also known as glass frit).

  The low melting glass powder is a glass powder that can be heat-sealed at a temperature at which the plate glass (soda lime glass) is not thermally deformed (for example, 600 ° C. or less) or at a temperature lower than the heat resistance temperature of the plate glass (for example, 750 to 800 ° C.). Thus, for example, sealing glass, sealing glass, and solder glass can be used. Such a low-melting glass powder has a glass transition point (Tg) of, for example, 250 to 600 ° C., or preferably 350 to 500 ° C.

  Further, the low melting point glass powder has an average particle size of, for example, 0.1 μm to 100 μm, preferably 0.5 μm to 10 μm.

  If the average particle diameter of the low melting glass powder is in the above range, the conductive paste composition can be reliably applied by screen printing or the like.

Examples of the low melting point glass powder include oxide glass powder, and more specifically, PbO—B ₂ O ₃ —SiO ₂ glass, PbO—B ₂ O ₃ —SiO ₂ —CaO glass, PbO—B. ₂ O ₃ —SiO ₂ —ZnO—CaO glass, PbO—B ₂ O ₃ —SiO ₂ —ZnO—BaO—CaO glass, PbO—B ₂ O ₃ —SiO ₂ —ZnO—BaO—CaO—Bi ₂ O ₃ based _{glass, ZnO-Bi 2 O 3 -B} 2 O 3 -SiO 2 -CaO-SrO-BaO -based _glass, B ₂ O 3 -PbO type _glass, B ₂ O 3 -PbO-ZnO-based glass, _Cu 2 O -P ₂ O ₅ based _glass, P ₂ O 5 -SnO-based _{glass, P 2 O 5 -SnO-B} 2 O 3 based _{glass, BaO-ZnO-B 2 O} 3 -SiO 2 based glass, ZnO-Bi ₂ Examples thereof include powder of O ₃ —B ₂ O ₃ —SiO ₂ glass.

  When the low melting point glass powder is blended as the inorganic powder, the blending ratio is, for example, 0.1 to 100 parts by weight, preferably 0.5 to 12 parts by weight with respect to 100 parts by weight of the conductive powder. Part.

  Moreover, in the electrically conductive paste composition of this invention, an inorganic filler can also be contained as inorganic powder as needed.

  The inorganic filler is arbitrarily blended as an inorganic powder, and is blended to adjust the fluidity and thermal expansion coefficient of the conductive paste composition.

  Examples of the inorganic filler are those excluding the low melting point glass powder, and examples thereof include alumina, α-quartz, titania, zirconia, cordierite, zircon, tin oxide, niobium oxide, zirconium phosphate, willemite, and mullite. .

The average particle diameter D50 of such an inorganic filler is, for example, 0.1 to 100 μm, preferably 1 to ₅₀ μm.

  When an inorganic filler is blended as the inorganic powder, the blending ratio is, for example, 0.1 to 100 parts by weight, preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the conductive powder. is there.

  Moreover, in the electrically conductive paste composition of this invention, another well-known organic binder can be mix | blended in the ratio which does not inhibit the effect of this invention. Examples of other organic binders include ethyl cellulose, butyral resin, and acrylic resin.

  In the conductive paste composition, when the above polyurethane resin and other organic binder are blended, the above polyurethane resin is, for example, 20% by mass or more, preferably 50% by mass with respect to the total amount thereof. % Or more, more preferably 70% by mass or more, and the other organic binder is, for example, 80% by mass or less, preferably 50% by mass or less, more preferably 30% by mass or less.

  When the blending ratio of the polyurethane resin and the other organic binder is within the above range, dripping of the paste at the time of drying can be suppressed, and a residue at the time of debinding can be reduced.

  Furthermore, the conductive paste composition of the present invention includes additives such as plasticizers, dispersants, antifoaming agents, antioxidants, urethanization catalysts (tin catalysts and amine catalysts) at a ratio that does not inhibit the effects of the present invention. ) Can be added.

  And in order to prepare the electrically conductive paste composition of this invention, the binder resin solution (henceforth a binder resin solution may be called) which consists of a polyurethane resin and a solvent is prepared, and the electroconductive powder prepared separately, A coupling agent, and if necessary, a crosslinkable low molecular weight polyol, a solvent for dilution and other inorganic powders are blended.

  In order to prepare a binder resin solution, a polyurethane resin and a solvent are charged in a container such as a separable flask at a blending ratio described later, and for example, while heating at 40 to 80 ° C., for 30 to 120 minutes (specifically, , 60 minutes).

  Thus, the binder resin solution obtained contains 1-50 mass% of polyurethane resins, for example, and contains 50-99 mass% of solvents, for example. Further, the binder resin solution has a viscosity at 20 ° C. of, for example, 1 to 1000 Pa · s.

  The binder resin solution prepared as described above, a separately prepared conductive powder, if necessary, other inorganic powders, a coupling agent, a blocked isocyanate, and a crosslinkable low molecular weight polyol as necessary will be described later. The conductive paste composition of the present invention can be obtained by kneading at a blending ratio using a kneading machine such as a rotation / revolution mixer or a three-roll mill.

  In the preparation of the conductive paste composition, the blending ratio of the inorganic powder (conductive powder and, if necessary, other inorganic powder) is the inorganic powder (conductive) with respect to 100 parts by mass of the polyurethane resin contained in the binder resin solution. The powder and, if necessary, other inorganic powders) are, for example, 150 to 16000 parts by mass, preferably 500 to 5000 parts by mass.

  Moreover, the compounding ratio of the coupling agent is, for example, 0.01 to 2000 parts by mass, preferably 0.05 to 200 parts by mass with respect to 100 parts by mass of the polyurethane resin contained in the binder resin solution. Part.

  The blending ratio of the blocked isocyanate is, for example, 0.01 to 2000 parts by mass, preferably 0.05 to 200 parts by mass with respect to 100 parts by mass of the polyurethane resin contained in the binder resin solution. is there.

  When the crosslinkable low molecular weight polyol is blended, the blending ratio is, for example, 0.01 to 2000 parts by mass of the crosslinkable low molecular weight polyol with respect to 100 parts by mass of the polyurethane resin contained in the binder resin solution. The amount is preferably 0.1 to 200 parts by mass.

  In the conductive paste composition thus prepared, the content ratio of the polyurethane resin is, for example, 0.5% by mass or more, preferably 1% by mass or more with respect to the total amount of the conductive paste composition. 20% by mass or less, preferably 10% by mass or less.

  Moreover, the content rate of a solvent is 9.48 mass% or more with respect to the total amount of an electrically conductive paste composition, Preferably, it is 20 mass% or more, for example, 69.48 mass% or less, Preferably, it is 50 It is below mass%.

  The content of the conductive powder is, for example, 30% by mass or more, preferably 45% by mass or more, for example, 80% by mass or less, preferably 75% by mass with respect to the total amount of the conductive paste composition. It is as follows.

  The content of the coupling agent is, for example, 0.01% by mass or more, preferably 0.1% by mass or more, for example, 10% by mass or less, preferably, with respect to the total amount of the conductive paste composition. 1% by mass or less.

  Further, the content ratio of the blocked isocyanate is, for example, 0.01% by mass or more, preferably 0.05% by mass or more, for example, 10% by mass or less, preferably, with respect to the total amount of the conductive paste composition. 1% by mass or less.

  Moreover, when a crosslinkable low molecular weight polyol is contained, the content ratio is, for example, 10% by mass or less, preferably 5% by mass or less, with respect to the total amount of the conductive paste composition.

  And such an electrically conductive paste composition contains the polyurethane resin obtained by reaction of specific polyoxyalkylene glycol and diisocyanate, a solvent, electroconductive powder, a coupling agent, and block isocyanate. Therefore, it is excellent in the adhesive force of the electrically conductive paste after drying, and a base material, and can suppress that an electrically conductive paste peels after drying.

  Next, a method for producing the fired body of the present invention using the paste composition of the present invention will be described.

  In this method, first, the conductive paste composition is applied and printed using a known coating / printing method such as brush coating, coating by a roll coater, coating by a bar coater, coating by a dispenser, coating by screen printing, or the like. It applies | coats to the base material (for example, a board | substrate, a support body etc.) used as the object of printing. As the coating / printing method, preferably, screen printing is used from the viewpoint of the thickness (film thickness) of the coated conductive paste composition, the accuracy of the shape, the high productivity, and the like.

  The shape of the substrate on which the conductive paste is applied / printed varies, and the coating / printing surface may be a flat surface or a curved surface.

  The film thickness of the conductive paste composition formed by these methods is, for example, about 1 to 1000 μm. In particular, the film thickness of the conductive paste composition by screen printing is, for example, about 1 to 100 μm.

  In this method, the substrate on which the conductive paste composition has been applied and printed is then dried.

  The drying time is, for example, 80 to 290 ° C, preferably 100 to 260 ° C, and the drying time is, for example, 0.1 to 60 minutes, preferably 0.5 to 30 minutes. Thereby, the solvent can be removed from the conductive paste composition.

  Thereafter, in this method, the conductive paste composition is fired.

  In firing, the conductive paste composition is first heated at, for example, 300 to 500 ° C., preferably 400 to 450 ° C., for example, for 0.1 to 60 minutes, preferably 0.5 to 10 minutes, and removed. Binder (that is, the polyurethane resin is removed by combustion and / or thermal decomposition), and then, if necessary, further heat treatment is performed at a temperature corresponding to the conductive powder.

  For example, when the conductive paste composition is an aluminum paste containing a low-melting glass powder, after debinding, the softening temperature of the low-melting glass powder is higher than the softening temperature of the low-melting glass powder, for example, 500 to 800 ° C., and further 0.01 to 10 Heat-treat for minutes.

  When the conductive paste composition is a metal powder paste that does not contain low-melting glass powder, heat treatment is performed at a temperature that is at least equal to or higher than the melting point of the metal. Specifically, for example, a paste of aluminum powder (melting point: 660 ° C.) is heat-treated at 660 ° C. or higher, preferably 700-800 ° C., for example, for 0.01-10 minutes.

  When metal powder or the like is used as the conductive powder, the atmospheric conditions for drying and firing include, for example, an air atmosphere (oxygen atmosphere) or a nitrogen atmosphere depending on the degree of oxidization of the metal powder. Either can be selected.

  More specifically, when a metal powder that is easily oxidized as the conductive powder, such as a copper powder or a nickel powder, is used, preferably, a nitrogen atmosphere is used as an atmospheric condition for debinding.

  Thereby, the sintered body of the present invention can be obtained.

  Specifically, the fired body is formed, for example, as a solar cell electrode (aluminum electrode, silver electrode), a solid electrolyte fuel cell electrode, a multilayer ceramic capacitor electrode, or the like.

  For example, as a back electrode of a semiconductor substrate (silicon substrate) of a solar cell, a conductive paste composition (more specifically, an aluminum conductive paste composition in which aluminum powder is used as a conductive powder) is obtained by screen printing or the like. For example, an aluminum electrode with a controlled film thickness is formed by applying to a thickness of 10 to 100 μm, drying and baking.

  Furthermore, in a solar cell, a conductive paste composition (more specifically, a silver conductive paste composition in which silver powder is used as a conductive powder) is used as an electrode on the light receiving surface (front surface) of the semiconductor substrate (silicon substrate). The silver electrode having a uniform line width and film thickness is formed by screen-printing the product so as to have a width of, for example, 10 to 200 μm, and drying and firing.

  And as above-mentioned, this electrically conductive paste composition is excellent in the adhesive force of the electrically conductive paste composition after drying, and a base material, and can suppress that an electrically conductive paste composition peels after drying.

  Therefore, according to the fired body in which this conductive paste composition is used, it is possible to suppress a decrease in electrical characteristics due to peeling of the conductive paste composition.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples. Moreover, the numerical value of the Example shown below can be substituted for the numerical value (namely, upper limit value or lower limit value) described in embodiment.

The measurement is based on the following example.
<< weight average molecular weight >>
... Gel permeation chromatography (based on polystyrene calibration curve)
・ Mobile phase Dimethylformamide (DMF)
・ Use column Plgel GUARD (nothing)
5 μmMixed-C (3)
・ System used: Alliance (Waters)
.. 2410 differential refraction detector (manufactured by Waters)
..996 type multi-wavelength detector (manufactured by Waters)
..Millennium data processor (Waters)
<Production of resin solution>
Production Example 1
(Synthesis of polyurethane resin 1)
In a 1000 mL glass separable flask, ethylene oxide (EO), tetrahydrofuran (THF) random copolymer (trade name “Polyserine DC3000E” manufactured by NOF Corporation, molar ratio (EO / THF) = 50/50, number average molecular weight 3161) was charged and dried at 120 ° C. for 1 hour under reduced pressure (100 Pa) with stirring.

  Subsequently, the temperature was lowered to 70 ° C., and the flask was filled with 1 atm of nitrogen.

  Next, 199 g of toluene and 0.08 g of antioxidant were added. Next, 5.36 g of hexamethylene diisocyanate (HMDI) was charged while stirring the flask (NCO / OH = 0.998 mol / mol).

  Next, 0.01 g of catalyst (DBTDL, dibutyltin dilaurate) was added, reacted at 70 ° C. for 1 hour, and further reacted at 90 ° C. for 6 hours to obtain a toluene solution of polyurethane resin 1.

The resulting polyurethane resin 1 had a weight average molecular weight of about 80,000.
(Preparation of binder resin solution 1)
The toluene solution of polyurethane resin 1 obtained as described above was charged with 520 g of butyl carbitol, and toluene was distilled off under reduced pressure (100 Pa) to obtain a binder resin solution 1 having a resin concentration of 17% by mass.

Production Example 2
(Synthesis of polyurethane resin 2)
A 1000 mL glass separable flask was charged with 300 g of polytetramethylene ether glycol (trade name “PTG-2000SN” manufactured by Hodogaya Chemical Co., Ltd., number average molecular weight 2011) and stirred at 120 ° C. under reduced pressure (100 Pa). Let dry for hours.

  Subsequently, the temperature was lowered to 70 ° C., and the flask was filled with 1 atm of nitrogen.

  Next, 330 g of toluene and 9 g of antioxidant were added. Next, while stirring the flask, 24.59 g of hexamethylene diisocyanate (HMDI) was charged (NCO / OH = 0.98 mol / mol).

  Next, 0.03 g of a catalyst (DBTDL, dibutyltin dilaurate) was added, reacted at 70 ° C. for 1 hour, and further reacted at 90 ° C. for 6 hours to obtain a toluene solution of polyurethane resin 2.

The resulting polyurethane resin 2 had a weight average molecular weight of about 65,000.
(Preparation of binder resin solution 2)
The toluene solution of polyurethane resin 1 obtained as described above was charged with 330 g of butyl carbitol, and toluene was distilled off under reduced pressure (100 Pa) to obtain a binder resin solution 2 having a resin concentration of 50% by mass.

Production Example 3
(Synthesis of polyurethane resin 3)
A 1000 mL glass separable flask was charged with 240 g of polytetramethylene ether glycol (trade name “PTG-1000” manufactured by Hodogaya Chemical Co., Ltd., number-average molecular weight 1013) and stirred at 120 ° C. under reduced pressure (100 Pa) at 120 ° C. Let dry for hours.

  Subsequently, the temperature was lowered to 70 ° C., and the flask was filled with 1 atm of nitrogen.

  Next, 300 g of toluene and 7 g of antioxidant were added. Next, while stirring the inside of the flask, 4.8 g of 1,4-butanediol and 48.00 g of hexamethylene diisocyanate (HMDI) were charged (NCO / OH = 0.383 mol / mol).

  Next, 0.03 g of a catalyst (DBTDL, dibutyltin dilaurate) was added, reacted at 70 ° C. for 1 hour, and further reacted at 90 ° C. for 6 hours to obtain a toluene solution of polyurethane resin 2.

The resulting polyurethane resin 3 had a weight average molecular weight of about 60,000.
(Preparation of binder resin solution 3)
300 g of butyl carbitol was added to the toluene solution of the polyurethane resin 3 obtained as described above, and the toluene was distilled off under reduced pressure (100 Pa) to obtain a binder resin solution 3 having a resin concentration of 50% by mass.

Production Example 4
(Preparation of binder resin solution 4)
20 g of commercially available ethyl cellulose (Ethocel Std-100) was dissolved in 80 g of butyl carbitol to obtain a binder resin solution 4 having a resin concentration of 20% by mass.
<Preparation of conductive paste composition>
Each raw material component is weighed in a mixing container at the ratio shown in Tables 1 to 3, and mixed for 5 minutes at a rotation speed of 2000 rpm with a rotating and rotating mixer, followed by defoaming at a rotation speed of 2200 rpm for 1 minute, and a conductive paste. A composition was obtained. The composition of the conductive paste composition in each Example and each Comparative Example is shown in Tables 1-3.

In addition, raw materials other than polyurethane resin are shown below.
(Dilution solvent)
・ Butyl carbitol (hereinafter abbreviated as BC)
・ 1,6-hexanediol (hereinafter abbreviated as HD)
1,4-butanediol (hereinafter abbreviated as BD)
(powder)
・ Spherical aluminum powder with an average particle diameter of 5 μm ・ Glass frit with an average particle diameter of 2 μm (PbO—B ₂ O ₃ —SiO ₂ glass)
(Coupling agent)
3-glycidoxypropyltrimethoxysilane (hereinafter abbreviated as SC-1)
N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (hereinafter abbreviated as SC-2)
(Block isocyanate)
-Solvent naphtha / butyl acetate (20% / 10%) solution of blocked isocyanate in which HMDI trimer is blocked with methyl ethyl ketone oxime, resin concentration 70%, regenerated NCO group concentration 10.7% (hereinafter referred to as BI-1) (Omitted)
A methyl isobutyl ketone solution of blocked isocyanate in which an adduct of HMDI burette modified with PPG (molecular weight 2000) is blocked with methyl ethyl ketone oxime, resin concentration 70%, regenerated NCO group concentration 6.1% (hereinafter referred to as BI-2) Abbreviated)
These blocked isocyanates were obtained according to the method described in JP2011-236388A.
(Crosslinkable low molecular weight polyol having 3 or more hydroxyl groups in one molecule)
・ Trimethylolpropane (hereinafter abbreviated as TMP)
Diglycerin (hereinafter abbreviated as DG)
<Application and drying of conductive paste>
The conductive paste composition was applied to the surface of a 4 inch diameter p-type silicon wafer and dried at a predetermined temperature for a predetermined time to obtain a dried conductive paste composition. Tables 1 to 3 show the drying temperature, the drying time, and the film thickness of the conductive paste composition after drying.
<Adhesion test>
Place the dried silicon wafer on the test bench with the surface coated with the conductive paste composition facing up, let stand at room temperature for 5 minutes, and then the part from the end of the cellophane tape having a width of 24 mm and a length of 10 cm to a length of 5 cm Was affixed to the surface of the paste and pressed with a finger to cause pressure bonding.

  Subsequently, the opposite end of the cellophane tape was pinched with a finger and pulled upward to peel the cellophane tape from the silicon wafer.

From the amount of paste adhered to the surface of the peeled tape and the state of adhesion of the paste to the finger when the surface of the paste where the cellophane tape was not applied was rubbed with the finger, the adhesive strength of the paste was 1-5 Evaluation was made in 5 stages. The criteria for the score are as follows.
Score 1: The paste adheres to almost the entire surface of the cellophane tape in the crimped portion, and when the portion that has not been crimped on the cellophane tape is lightly rubbed once with a finger, aluminum powder adheres to the finger.
Score 3: The paste adheres to almost half of the cellophane tape at the crimped portion, and when the portion not crimped with the cellophane tape is rubbed ten times with a finger, aluminum powder adheres to the finger.
Score 5: Almost no paste adheres to the cellophane tape of the crimped portion, and even if the portion where the cellophane tape is not crimped is rubbed ten times with a finger, aluminum powder does not adhere to the finger.
Grade 2: Intermediate state between grade 1 and grade 3.
Grade 4: Intermediate state between grade 3 and grade 5.

  In addition, although the adhesive force test was implemented twice, the score corresponded twice.

  Moreover, if the score of adhesion is 4-5, the adhesion of the paste after drying to the silicon wafer can suppress the peeling of the paste due to friction during conveyance of the wafer, and the efficiency of the solar cell after firing is reduced. It is thought that it can be suppressed.

  The evaluation results of the adhesion force are shown in Tables 1-3.

Claims (9)

A polyoxyalkylene glycol containing an alkylene group having 2 to 6 carbon atoms and a polyurethane resin obtained by reacting at least a diisocyanate;
Solvent,
Conductive powder;
A coupling agent;
A conductive paste composition comprising at least a blocked isocyanate.   The conductive paste composition according to claim 1, further comprising a crosslinkable low molecular weight polyol having three or more hydroxyl groups in one molecule and having a molecular weight of 92 or more and 500 or less. Polyoxyalkylene glycol is
The conductive paste composition according to claim 1, which is polytetramethylene ether glycol or an ethylene oxide / tetramethylene oxide copolymer. For the total amount of the conductive paste composition,
0.5-20% by mass of polyurethane resin,
9.48-69.48% by weight of solvent,
30-80% by mass of conductive powder,
0.01 to 10% by mass of a coupling agent,
0.01 to 10% by weight of blocked isocyanate,
0-10 mass% of crosslinkable low molecular weight polyol
The conductive paste composition according to claim 1, wherein the conductive paste composition is contained at a ratio of Conductive powder
The conductive paste according to any one of claims 1 to 4, wherein the conductive paste is at least one selected from the group consisting of aluminum powder, silver powder, copper powder, platinum powder, palladium powder and nickel powder. Composition. Coupling agent
It is an alkoxysilane compound which has a primary amino group and an alkoxy group, The electrically conductive paste composition as described in any one of Claims 1-5 characterized by the above-mentioned. Blocked isocyanate
Blocked isocyanate obtained by reaction of a polymer of hexamethylene diisocyanate with a blocking agent, or
The electrically conductive paste composition according to any one of claims 1 to 6, which is a blocked isocyanate obtained by a reaction between a polyol-modified product obtained by modifying a biuret-modified product of hexamethylene diisocyanate with a polyol and a blocking agent. object.   Furthermore, low-melting glass is contained, The electrically conductive paste composition as described in any one of Claims 1-7 characterized by the above-mentioned.   A fired body obtained by firing the conductive paste composition according to any one of claims 1 to 8.