Resin, paste composition, inorganic sintered body, electronic device, and solar panel

Abstract

Provided are a resin having excellent solvent solubility and thermal decomposability and high thixotropy, a paste composition, an inorganic sintered body, an electronic device, and a solar panel. This resin has a structural unit derived from a (meth) acrylate and a chemical structure derived from a thiol having two or more SH groups, and the ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) is 5.0 or more.

Description

Technical Field

[0001] The present invention relates to a resin, a paste composition, an inorganic sintered body, an electronic device and a solar panel.

[0002] This application claims priority based on Japanese Patent Application No. 2023-049200 filed in Japan on March 27, 2023, the contents of which are incorporated herein by reference. Background Art

[0003] In the internal electrode layers, external electrodes, and solar cell electrodes of laminated electronic components such as laminated ceramic capacitors, molded bodies formed of inorganic materials, and patterns (e.g., wiring patterns, insulation patterns, etc.) formed from these molded bodies are sometimes used. Known methods for forming such molded bodies and patterns include mixing inorganic compounds such as metal powders, metal oxide powders, fluorescent powders, and glass frits with a binder resin to prepare a paste composition, molding this paste composition into a predetermined shape to form a molded body or pattern, and then firing the mixture to thermally decompose the binder resin.

[0004] The binder resin used here serves to improve processability during molding and to bind the inorganic compound to prevent damage during movement. This binder resin is removed by thermal decomposition during sintering of the inorganic compound before the final product is formed. Therefore, it is required to have high thermal decomposability and excellent workability during various processing steps.

[0005] Furthermore, the binder resin used in this application is required to be solid and solvent-free and to be easily soluble in a solvent, because the viscosity range can be easily changed by adjusting the addition amount during compounding and the solvent selectivity is wide.

[0006] Known methods for processing paste compositions include screen printing, forming into a sheet using a doctor blade, dipping, and dispensing. When screen printing is used, the higher the thixotropy of the paste composition, the better the printability and leveling properties after printing. Therefore, when screen printing is used, the paste composition is required to have high thixotropy.

[0007] As a binder resin, for example, Patent Document 1 discloses crosslinked fine particles comprising a (meth)acrylic resin having an average particle size of 0.1 to 0.5 μm and containing 20 to 55% by mass of structural units derived from a monofunctional (meth)acrylate having 1 to 4 carbon atoms at the ester moiety and 45 to 80% by mass of structural units derived from a polyfunctional (meth)acrylate having an alkylene glycol moiety having 2 to 4 carbon atoms. The crosslinked fine particles have a heating residue amount of 0.3% or less when heated to 500°C at 5°C / min in an air atmosphere.

[0008] Patent Document 2 discloses a binder resin for a conductive paste having excellent thixotropy and thermal decomposition properties due to a polymer having a specific structure of a hydroxyurethane structure.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-017478

[0012] Patent Document 2: International Publication No. 2020 / 152939 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] However, the paste composition obtained using the crosslinked fine particles described in Patent Document 1 cannot obtain high thixotropy suitable for screen printing.

[0015] Furthermore, the binder resin for the conductive paste described in Patent Document 2 is not a solid, and thus has problems in terms of solvent selectivity and adjustment of the viscosity range.

[0016] An object of the present invention is to provide a resin, a paste composition, an inorganic sintered body, an electronic device, and a solar panel that are excellent in solvent solubility and thermal decomposition properties and have high thixotropy.

[0017] Solutions for solving problems

[0018] The gist of the present invention lies in the following [1] to

[16] .

[0019] [1] A resin having a structural unit derived from a (meth)acrylate and a chemical structure derived from a thiol having two or more SH groups, wherein the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 5.0 or more.

[0020] [2] The resin according to [1] above, wherein the resin is a solid binder for firing.

[0021] [3] The resin according to [1] or [2] above, wherein the mass average particle size is greater than 100 μm and not more than 1500 μm.

[0022] [4] The resin according to any one of [1] to [3] above, wherein the acid value is 0 to 50 mgKOH / g.

[0023] [5] The resin according to any one of [1] to [4] above, further comprising a chemical structure derived from a thiol having one SH group.

[0024] [6] The resin according to any one of [1] to [5] above, further comprising a structural unit derived from a monomer having two or more polymerizable double bonds.

[0025] [7] The resin according to any one of [1] to [6] above, wherein the structural unit derived from a monomer having two or more polymerizable double bonds accounts for 0.1 to 5.0% by mass relative to the structural units derived from all monomers in the resin.

[0026] [8] The resin according to any one of [1] to [7] above, wherein the thermal weight loss rate determined under the following measurement conditions is 95.0% or more.

[0027] <Measurement Conditions of Thermal Loss Rate>

[0028] Using a differential thermal balance (TG-DTA), 5 mg of a sample was heated from a starting temperature of 30°C to 500°C at a rate of 10°C / min in a nitrogen atmosphere. The mass of the residue at 450°C was measured, and the thermal weight loss rate was calculated from the following formula (1).

[0029] Thermal loss rate (%) = {(mass of measurement sample (mg) - mass of residue (mg)) / mass of measurement sample (mg)} × 100 (1)

[0030] [9] The resin according to any one of [1] to [8] above, wherein a resin solution containing 30% by mass of the resin obtained by dissolving the resin in terpineol satisfies the following formula (2).

[0031] η1 / η1000≥1.5···(2)

[0032] Here, η1 and η1000 are the viscosities (Pa·s) of the resin solution measured using a viscoelasticity measuring apparatus at a cone plate of 1.0° / 20mm and a measurement temperature of 23°C. η1 is the viscosity (Pa·s) at a shear rate of 1 (1 / s), and η1000 is the viscosity (Pa·s) at a shear rate of 1000 (1 / s).

[0033]

[10] The resin according to any one of [1] to [9] above, having a weight average molecular weight of 10,000 to 1,000,000.

[0034]

[11] The resin according to any one of [1] to

[10] above, wherein the water content is 0.01 to 10% by mass relative to the total mass of the resin.

[0035]

[12] A paste composition comprising: the resin according to any one of [1] to

[11] above; a metal or an inorganic compound; and an organic solvent.

[0036]

[13] The paste composition according to

[12] above, wherein the boiling point of the organic solvent is 180° C. or higher.

[0037]

[14] An inorganic sintered body obtained by sintering the paste composition described in

[12] or

[13] above.

[0038]

[15] An electronic device comprising the inorganic sintered body described in

[14] above.

[0039]

[16] A solar panel comprising the inorganic sintered body described in

[14] .

[0040] Effects of the Invention

[0041] According to the present invention, a resin, a paste composition, an inorganic sintered body, an electronic device, and a solar panel having excellent solvent solubility and thermal decomposition properties and high thixotropy can be provided. DETAILED DESCRIPTION

[0042] The present invention will be described in more detail below by giving preferred embodiments of the invention. However, the following description is an example of the embodiment of the present invention, and the present invention is not limited to the following description unless it exceeds the gist of the invention.

[0043] It should be noted that, in the present invention, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid. "(meth)acrylate" is a general term for acrylate and methacrylate. "(meth)acryloyl" is a general term for acryloyl and methacryloyl.

[0044] In the present invention, the "polymerizable double bond" refers to a double bond capable of radical polymerization.

[0045] In the present invention, "room temperature" refers to 5 to 30°C.

[0046] In the present invention, "to" indicating a numerical range means that the numerical values ​​described before and after it are included as the lower limit and the upper limit.

[0047] [Resin]

[0048] Hereinafter, one embodiment of the resin of the present invention will be described.

[0049] The resin of the present embodiment has a structural unit (a1) derived from a (meth)acrylate (hereinafter also referred to as "monomer (a1)") and a chemical structure (b1) derived from a thiol having two or more SH groups, and has a ratio (Mw / Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 5.0 or more.

[0050] From the viewpoint of improving solvent solubility and thixotropy, the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 5.5 or more, more preferably 10 or more, even more preferably 15 or more, particularly preferably 30 or more, and most preferably 35 or more. Furthermore, it is preferably 100 or less, more preferably 80 or less, even more preferably 60 or less, and particularly preferably 40 or less. The above upper and lower limits may be arbitrarily combined. For example, it may be 5.0 to 100, 5.5 to 100, 10 to 100, 30 to 100, 35 to 100, 5.0 to 80, 10 to 80, 15 to 80, 30 to 80, 35 to 80, 5.0 to 60, 10 to 60, 15 to 60, 30 to 60, 35 to 60, 5.0 to 40, 10 to 40, 15 to 40, 30 to 40, or 35 to 40. Within the above ranges, increasing the ratio of the low molecular weight component improves solvent solubility, thermal decomposition properties, and thixotropy.

[0051] As a method for adjusting the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the resin, for example, the ratio Mw / Mn can be increased by increasing the ratio of the structural unit (a2) relative to the total structural units of the resin. Alternatively, the ratio Mw / Mn can be decreased by decreasing the ratio of the structural unit (a2) relative to the total structural units of the resin.

[0052] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the resin are values ​​calculated in terms of standard polystyrene as measured by gel permeation chromatography (GPC). Detailed measurement conditions are described in the Examples below.

[0053] The resin preferably has, in addition to the structural unit (a1) and the chemical structure (b1), at least one of a structural unit (a2) derived from a monomer having two or more polymerizable double bonds (hereinafter also referred to as "monomer (a2)") and a chemical structure (b2) derived from a thiol having one SH group.

[0054] The resin may further have a structural unit (a3) ​​derived from a monomer other than the monomer (a1) and the monomer (a2) (hereinafter also referred to as "monomer (a3)").

[0055] <Monomer (a1)>

[0056] The monomer (a1) is a (meth)acrylate.

[0057] The monomer (a1) is a monofunctional monomer having one polymerizable double bond, and specifically, is a monofunctional monomer having one (meth)acryloyl group as a functional group having a polymerizable double bond.

[0058] Examples of the monomer (a1) include alkyl (meth)acrylates having a linear or branched hydrocarbon backbone, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and 4-tert-butylcyclohexyl (meth)acrylate.

[0059] Alkyl (meth)acrylates having an alicyclic skeleton, such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, and dicyclopentanyl (meth)acrylate;

[0060] (Meth)acrylates having a glycidyl group, such as glycidyl (meth)acrylate and hydroxybutyl (meth)acrylate glycidyl ether;

[0061] (Meth)acrylates having an aromatic ring, such as phenoxy (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenol EO adduct (meth)acrylate, and o-biphenyloxyethyl (meth)acrylate;

[0062] (Meth)acrylates such as ammonium (meth)acrylate, sodium (meth)acrylate, potassium (meth)acrylate, etc.;

[0063] (Meth)acrylates having a cyclic ether such as tetrahydrofurfuryl (meth)acrylate;

[0064] (Meth)acrylates having an amino group, such as N-dimethylaminoethyl (meth)acrylate and N-diethylaminoethyl (meth)acrylate;

[0065] (Meth)acrylamide derivatives such as (meth)acrylamide, (meth)acrylamide diacetone acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and (meth)acryloylmorpholine;

[0066] Monomers having a phosphate group, such as 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxyethyl acid phosphate monoethanolamine salt, ((meth)acryloyloxyethyl)diphenyl phosphate, (meth)acryloyloxypropyl acid phosphate, 3-chloro-2-acid phosphopropyl (meth)acrylate, acid phosphopolyoxyethylene glycol mono(meth)acrylate, and acid phosphopolyoxypropylene glycol (meth)acrylate;

[0067] Hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,2-dihydroxyethyl (meth)acrylate, 1,2-dihydroxypropyl (meth)acrylate, 1,2-dihydroxybutyl (meth)acrylate, 1,2-dihydroxy 5-ethylhexyl (meth)acrylate, 1,1-dihydroxyethyl (meth)acrylate, 1,1-dihydroxypropyl (meth)acrylate, 1,1-dihydroxybutyl (meth)acrylate, 1,2,3-trihydroxypropyl (meth)acrylate, 1,2,3-trihydroxybutyl (meth)acrylate, 1,1,2-trihydroxypropyl (meth)acrylate, and 1,1,2-trihydroxybutyl (meth)acrylate;

[0068] Hydroxy (meth)acrylates having an aromatic ring, such as 2-hydroxy-3-phenoxypropyl (meth)acrylate;

[0069] Hydroxypolyethylene oxide mono(meth)acrylate, hydroxypolypropylene oxide mono(meth)acrylate, hydroxy(polyethylene oxide-polypropylene oxide) mono(meth)acrylate, hydroxy(polyethylene oxide-propylene oxide) mono(meth)acrylate, hydroxy(polyethylene oxide-polybutylene oxide) mono(meth)acrylate, hydroxy(polyethylene oxide-butylene oxide) mono(meth)acrylate, hydroxy(polypropylene oxide-polybutylene oxide) mono(meth)acrylate, hydroxy(polypropylene oxide-polybutylene oxide) mono(meth)acrylate, hydroxy(polypropylene oxide-polybutylene oxide) mono(meth)acrylate, 1,2-dihydroxypolyethylene oxide (meth)acrylate, 1,2-dihydroxypolypropylene oxide (meth)acrylate, polyhydroxyalkyl (meth)acrylate, 1,2,3-trihydroxypropylene glycol (meth)acrylate, 1,1,2-trihydroxypropylene glycol (meth)acrylate, and other hydroxypolyalkylene oxide (meth)acrylates;

[0070] (Meth)acrylates having a carboxyl group, such as acrylic acid, methacrylic acid, mono(2-(meth)acryloyloxyethyl) succinate, and ω-carboxy-polycaprolactone mono(meth)acrylate. From the viewpoint of thermal decomposition resistance, alkyl (meth)acrylates having a linear or branched hydrocarbon backbone are preferred, and from the viewpoint of versatility, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate are more preferred.

[0071] The monomer (a1) may be used alone or in combination of two or more.

[0072] When the total of all structural units constituting the resin is set to 100% by mass, the proportion of structural unit (a1) in the resin is preferably 70.0 to 100% by mass, more preferably 90.0 to 99.9% by mass, further preferably 95.0 to 99.7% by mass, particularly preferably 97.0 to 99.5% by mass, and most preferably 99.0 to 99.5% by mass. If the ratio is above the lower limit, the thermal decomposition property of the resin is further improved. If the ratio is below the upper limit, the thixotropy of the resin is further improved.

[0073] <Monomer (a2)>

[0074] The monomer (a2) is a monomer having two or more polymerizable double bonds.

[0075] As the monomer (a2), a polyfunctional monomer having two or more (meth)acryloyl groups as a functional group having a polymerizable double bond can be mentioned.

[0076] Examples of the monomer (a2) include polyfunctional alkyl (meth)acrylates having a linear or branched hydrocarbon backbone, such as ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0077] Polyfunctional polyalkoxylated (meth)acrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and ethoxylated glycerol tri(meth)acrylate;

[0078] Multifunctional (meth)acrylates having a hydroxyl group, such as 2-hydroxy-3-acryloyloxypropyl (meth)acrylate and pentaerythritol tri(meth)acrylate;

[0079] Polyfunctional (meth)acrylates having an ester skeleton, such as neopentyl glycol hydroxypivalate di(meth)acrylate;

[0080] Polyfunctional glycerol (meth)acrylates such as glycerol tri(meth)acrylate and ethoxylated glycerol tri(meth)acrylate. From the viewpoint of thermal decomposition, polyfunctional alkyl (meth)acrylates having a linear or branched hydrocarbon backbone are preferred, and from the viewpoint of crosslink density, ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate are more preferred.

[0081] The monomer (a2) may be used alone or in combination of two or more.

[0082] When the total of all structural units constituting the resin is set to 100% by mass, the ratio of the structural unit (a2) in the resin is preferably 0 to 20% by mass, more preferably 0.01 to 20% by mass, further preferably 0.1 to 10% by mass, particularly preferably 0.1 to 6% by mass, particularly preferably 0.1 to 5.0% by mass, and most preferably 0.3 to 5.0% by mass. If it is above the above lower limit, the thixotropy when the resin is dissolved in a solvent is further improved. If it is below the above upper limit, the solvent solubility of the resin is further improved. If it is within the above range, the resin becomes a moderate degree of crosslinking, and the thixotropy and solvent solubility become good.

[0083] <Monomer (a3)>

[0084] The monomer (a3) ​​is a monomer other than the monomer (a1) and the monomer (a2).

[0085] The monomer (a3) ​​is not particularly limited as long as it is copolymerizable with at least the monomer (a1), and examples thereof include aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, and chlorostyrene.

[0086] Acrylonitrile, methacrylonitrile, α-cyanoacrylate, dicyanoethylene, fumaronitrile and other vinyl cyanide monomers;

[0087] Monomers with carboxyl groups such as crotonic acid, isocrotonic acid, cinnamic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, and glutaconic acid;

[0088] Monomers having a sulfonic acid group, such as vinyl sulfonic acid and 2-acrylamide-2-methylpropanesulfonic acid;

[0089] Multifunctional monomers such as divinylbenzene, divinylnaphthalene, and divinyl ether;

[0090] Vinyl monomers such as vinyl acetate and vinyl propionate; conjugated diene monomers such as 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, and chloroprene.

[0091] The monomer (a3) ​​may be used alone or in combination of two or more.

[0092] When the total of all structural units constituting the resin is set to 100% by mass, the proportion of structural unit (a3) ​​in the resin is preferably 0 to 15% by mass, and more preferably 0 to 9.5% by mass. If it is above the above lower limit, the thixotropy of the resin when dissolved in a solvent is further improved. If it is below the above upper limit, the thermal decomposition property of the resin is further improved. If it is within the above range, the resin has an appropriate degree of crosslinking, and the thixotropy and thermal decomposition property of the resin are improved.

[0093] <Mercaptan having two or more SH groups>

[0094] Mercaptans having two or more SH groups function as chain transfer agents in polymerization reactions.

[0095] When producing a resin, by using a thiol having two or more SH groups as a chain transfer agent in the polymerization reaction, the thiol having two or more SH groups becomes a polymerization initiation point, and a chemical structure (b1) derived from the thiol having two or more SH groups is introduced into the resin. Furthermore, by introducing the chemical structure (b1) derived from the thiol having two or more SH groups into the resin, a spherical resin with a branched structure is formed. This reduces entanglement of side chains between resin particles, thereby improving thixotropy even at high molecular weights and improving stringiness associated with entanglement between polymers.

[0096] The thiol having two or more SH groups is a compound having two or more mercapto groups in a single molecule.

[0097] Examples of the thiol having two or more SH groups include thiols having a linear or branched hydrocarbon skeleton such as 1,2,3-trimercaptopropane, 2,2-bis(mercaptomethyl)-1-mercaptobutane, 1,2,3,4-tetramercaptobutane, and 2,2-bis(mercaptomethyl)-1,3-dimercaptopropane;

[0098] Thiols with a 3-mercaptopropionate structure, such as glycerol tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexa(3-mercaptopropionate), and tetraethylene glycol bis(3-mercaptopropionate);

[0099] Mercaptans having a thioglycolate structure, such as glycerol tris(thioglycolate), trimethylolpropane tris(thioglycolate), pentaerythritol tetra(thioglycolate), dipentaerythritol hexa(thioglycolate), and tetraethylene glycol bis(thioglycolate);

[0100] Monomers having a 2-mercaptobutyrate structure, such as glycerol tris(2-mercaptobutyrate), trimethylolpropane tris(2-mercaptobutyrate), pentaerythritol tetrakis(2-mercaptobutyrate), dipentaerythritol hexa(2-mercaptobutyrate), and tetraethylene glycol bis(2-mercaptobutyrate);

[0101] Monomers having a 3-mercaptobutyrate structure, such as 1,4-bis(3-mercaptobutyryloxy)butane, glycerol tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptobutyrate), dipentaerythritol hexa(3-mercaptobutyrate), and tetraethylene glycol bis(3-mercaptobutyrate);

[0102] Monomers having an isocyanate structure such as tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate and tris-[(3-mercaptobutyryloxy)-ethyl]-isocyanurate are preferred. From the perspective of reactivity, mercaptans having a 3-mercaptopropionate structure and mercaptans having a thioglycolate structure are preferred. As chain transfer agents, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropane tris(thioglycolate), and pentaerythritol tetrakis(thioglycolate) are more preferred from the perspectives of high reactivity, polymerization stability, and easy availability.

[0103] The thiol having two or more SH groups may be used alone or in combination of two or more.

[0104] The proportion of the structural unit (b1) in the resin is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1 to 6 parts by mass, relative to 100 parts by mass of all structural units constituting the resin. When the proportion is at least the lower limit, the thixotropy of the resin when dissolved in a solvent is further improved. When the proportion is at most the upper limit, the solvent solubility and thermal decomposition properties of the resin are further improved.

[0105] <Mercaptan having one SH group>

[0106] Mercaptans having one SH group function as chain transfer agents in polymerization reactions.

[0107] When producing the resin, in addition to the thiol having two or more SH groups, a thiol having one SH group is used as a chain transfer agent in the polymerization reaction. Thus, in addition to the thiol having two or more SH groups, the thiol having one SH group also serves as an initiation point for polymerization, and the chemical structure (b2) derived from the thiol having one SH group is introduced into the resin.

[0108] A thiol having one SH group is a compound having one mercapto group in a single molecule.

[0109] Examples of the mercaptan having one SH group include n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, n-butyl mercaptan, mercaptoacetic acid, 3-mercaptopropionic acid, 2-mercaptoethanol, 2-ethylhexyl 3-mercaptopropionate, 2-ethylhexyl thioglycolate, isooctyl 3-mercaptopropionate, isooctyl thioglycolate, and 2-methoxybutyl 3-mercaptopropionate. As the chain transfer agent, n-octyl mercaptan, n-dodecyl mercaptan, and tert-dodecyl mercaptan are preferred from the viewpoints of high reactivity and polymerization stability and easy availability.

[0110] The thiol having one SH group may be used alone or in combination of two or more.

[0111] The proportion of the structural unit (b2) in the resin is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, and even more preferably 0 to 6 parts by mass, relative to 100 parts by mass of all structural units constituting the resin. If the proportion is below the upper limit, the thermal decomposition property of the resin is further improved.

[0112] <Physical properties>

[0113] The resin is preferably a solid binder for firing at room temperature. If the resin is a solid binder for firing at room temperature, the amount added can be easily adjusted when preparing the paste composition described below, thereby facilitating adjustment of the viscosity range. Furthermore, since a variety of solvents can be selected, various formulations can be applied.

[0114] The specific shape of the resin is not particularly limited, and examples thereof include powder, plate, crushed flake, spherical, particle, granular, pelletized solids, etc. Among them, powder, crushed flake, spherical, particle, and pelletized solids are preferred from the perspective of easy handling when dissolved in a solvent.

[0115] From the perspective of good thermal decomposition properties, the resin of the present invention is preferably a binder for firing. Here, the binder for firing refers to a material used for printing the paste composition of the present invention on a printed material and then heating and firing it in a high-temperature furnace for the purpose of forming an electronic circuit of the electronic device of the present invention, an electrode of the solar panel of the present invention, an inorganic sintered body of the present invention, or an electromagnetic wave shielding material having the inorganic sintered body of the present invention.

[0116] The acid value of the resin (also called solid acid value) is not particularly limited, but is preferably 0 to 50 mgKOH / g, more preferably 0 to 43 mgKOH / g, further preferably 0 to 35 mgKOH / g, particularly preferably 0 to 15 mgKOH / g, and most preferably 1 to 19 mgKOH / g. When it is below the above upper limit, the thixotropy of the paste composition obtained using the resin is further improved. The above upper and lower limits can be arbitrarily combined. For example, it can be 1 to 50 mgKOH / g, 1 to 43 mgKOH / g, 1 to 35 mgKOH / g, 1 to 15 mgKOH / g, or 0 to 19 mgKOH / g.

[0117] The acid value of the resin is a value measured by neutralization titration using a potassium hydroxide (KOH) solution. Detailed measurement conditions are described in the Examples below.

[0118] The mass average particle size of the resin is preferably greater than 100 μm and less than 1500 μm, more preferably 110 to 1000 μm, even more preferably 130 to 800 μm, particularly preferably 150 to 340 μm, and most preferably 170 to 280 μm. When the particle size is greater than or equal to the lower limit, the risk of dust explosion is suppressed. When the particle size is less than or equal to the upper limit, the solvent solubility of the resin is further improved. The upper and lower limits described above may be arbitrarily combined. For example, it may be greater than 100 μm and less than 1000 μm, greater than 100 μm and less than 800 μm, greater than 100 μm and less than 340 μm, greater than 100 μm and less than 280 μm, 110 μm to 1000 μm or less, 110 μm to 800 μm or less, 110 μm to 340 μm or less, 110 μm to 280 μm or less, 130 μm to 1500 μm or less, 130 μm to 1000 μm or less, 130 μm to 800 μm or less, or 130μm to 340μm or less, can be 130μm to 280μm or less, can be 150μm to 1500μm or less, can be 150μm to 1000μm or less, can be 150μm to 800μm or less, can be 150μm to 340μm or less, can be 150μm to 280μm or less, can be 170μm to 1500μm or less, can be 170μm to 1000μm or less, can be 170μm to 800μm or less, can be 170μm to 340μm or less, can be 170μm to 280μm or less.

[0119] The mass average particle size of the resin can be calculated by classifying 20 g of the resin by shaking it for 5 minutes using a standard sieve.

[0120] The thermal weight loss rate of the resin is preferably 95.0% or greater, more preferably 99.0% or greater, even more preferably 99.8% or greater, and particularly preferably 99.9% or greater. A higher thermal weight loss rate indicates better thermal decomposition properties. When the thermal weight loss rate is above the lower limit, the amount of impurities in the inorganic sintered body obtained using the resin can be suppressed.

[0121] The upper limit of the thermal weight loss rate of the resin is 100%.

[0122] The thermal weight loss rate of the resin was determined under the following measurement conditions.

[0123] Specifically, using a differential thermal balance (TG-DTA), 5 mg of a measurement sample was heated from a starting temperature of 30°C to 500°C at a rate of 10°C / min in a nitrogen atmosphere. The mass of the residue when the temperature reached 450°C was measured, and the thermal weight loss rate was calculated from the following formula (1).

[0124] Thermal loss rate (%) = {(mass of measurement sample (mg) - mass of residue (mg)) / mass of measurement sample (mg)} × 100 (1)

[0125] As a method for adjusting the numerical value of the thermal weight loss rate of the resin, for example, if the ratio of the structural unit (b1) to all the structural units constituting the resin is set to 0.1 parts by mass or more relative to 100 parts by mass of all the structural units constituting the resin, the numerical value of the thermal weight loss rate can be reduced. Alternatively, if the ratio of the structural unit (b1) to all the structural units constituting the resin is set to 20 parts by mass or less relative to 100 parts by mass of all the structural units constituting the resin, the numerical value of the thermal weight loss rate can be increased.

[0126] The weight average molecular weight (Mw) of the resin is preferably 10,000 to 1,000,000, more preferably 50,000 to 500,000, even more preferably 100,000 to 400,000, particularly preferably 150,000 to 350,000, and most preferably 200,000 to 300,000. When the weight average molecular weight is at least the lower limit, the thixotropy of the paste composition obtained using the resin is further improved. When the weight average molecular weight is at most the upper limit, the solvent solubility of the resin is further improved.

[0127] The moisture content of the resin is preferably 0.01 to 10% by mass, more preferably 0.02 to 8.0% by mass, further preferably 0.1 to 5.0% by mass, and particularly preferably 0.3 to 3.0% by mass, relative to the total mass of the resin. When the moisture content is above the lower limit, the risk of dust explosion is suppressed. When the moisture content is below the upper limit, the uniform coating properties of the paste composition obtained using the resin during screen printing are improved.

[0128] The specific method for measuring the moisture content of the resin is described in the examples below.

[0129] A resin solution having a resin concentration of 30% by mass obtained by dissolving the resin in terpineol, that is, a resin solution containing 30% by mass of the resin relative to the total mass of the resin solution, preferably satisfies the following formula (2).

[0130] η1 / η1000≥1.5···(2)

[0131] Here, η1 and η1000 are the viscosities (Pa·s) of the resin solution measured using a viscoelasticity measuring apparatus at a cone plate of 1.0° / 20mm and a measurement temperature of 23°C. η1 is the viscosity (Pa·s) at a shear rate of 1 (1 / s), and η1000 is the viscosity (Pa·s) at a shear rate of 1000 (1 / s).

[0132] The above-mentioned η1 / η1000 is preferably 1.5 or greater, more preferably 2.0 or greater, and even more preferably 2.3 or greater. When it is at least the above lower limit, the thixotropy of the resin when dissolved in a solvent is further improved. As a result, the printability when screen-printing the paste composition obtained using the resin and the leveling properties after printing are further improved.

[0133] The upper limit of η1 / η1000 is not particularly limited, and for example, η1 / η1000 is preferably 6.0 or less. For example, η1 / η1000 may be 1.5 to 6.0, 2.0 to 6.0, or 2.3 to 6.0.

[0134] As a method for adjusting the value of η1 / η1000, for example, the value of η1 / η1000 can be increased by setting the ratio of the structural unit (b1) to 0.1 parts by mass or more relative to 100 parts by mass of all the structural units constituting the resin. Furthermore, the value of η1 / η1000 can be reduced by setting the ratio of the structural unit (b1) to 20 parts by mass or less relative to 100 parts by mass of all the structural units constituting the resin.

[0135] The terpineol used in the viscosity measurement is a mixture of α-terpineol, β-terpineol, and γ-terpineol as main components. Commercially available terpineol may be used, and examples thereof include "TERPINEOL PG" manufactured by Takasago Flavor Industry Co., Ltd., "Terpineol C" manufactured by Nippon Terpene Chemicals, Inc., and "Terpineol" manufactured by Nippon Flavors & Pharmaceuticals Co., Ltd.

[0136] The resin may be a homopolymer or a copolymer of the monomer (a1), and is particularly preferably a copolymer of the monomer (a1), the monomer (a2), and, if necessary, the monomer (a3).

[0137] When the resin is a copolymer, the resin may have any structure such as a random copolymer, a graft copolymer, or a block copolymer.

[0138] <Manufacturing method>

[0139] The resin can be produced by, for example, bulk polymerization, solution polymerization, suspension polymerization, or other commonly known polymerization methods, but is not limited to these polymerization methods. Among them, suspension polymerization is preferred because it can produce spherical particles that are easy to handle.

[0140] Hereinafter, an example of a method for producing a resin by suspension polymerization will be described.

[0141] The method for producing the resin of the present embodiment preferably includes the following steps of suspension polymerization, a first dehydration step, a washing step, a second dehydration step, and a drying step in this order.

[0142] (Suspension polymerization process)

[0143] The suspension polymerization step is a step of dispersing the monomer (a1) or a monomer mixture (M1) containing the monomer (a1), the monomer (a2), and, if necessary, the monomer (a3) ​​in water, and performing suspension polymerization in the presence of a thiol having two or more SH groups and, if necessary, a thiol having one SH group, to obtain a resin.

[0144] The content of the monomer (a1) is preferably 70 to 100% by mass, more preferably 90 to 100% by mass, further preferably 95 to 100% by mass, particularly preferably 97 to 100% by mass, and most preferably 99 to 100% by mass relative to the total mass of the monomer mixture (M1).

[0145] The content of monomer (a2) is preferably 0 to 20 mass %, more preferably 0.01 to 20 mass %, further preferably 0.1 to 10 mass %, particularly preferably 0.1 to 6 mass %, especially preferably 0.1 to 5 mass %, and most preferably 0.3 to 5 mass %, relative to the total mass of the mixture (M2).

[0146] The content of the monomer (a3) ​​is preferably 0 to 15% by mass, more preferably 0 to 9.5% by mass, relative to the total mass of the mixture (M2).

[0147] As the suspension polymerization method, a known method can be adopted, and examples thereof include a method of polymerizing the monomer (a1) or the monomer mixture (M1) in a suspended state in water in the presence of a polymerization auxiliary in a container having polymerization temperature control and stirring functions.

[0148] Examples of the polymerization aid include chain transfer agents, radical polymerization initiators, dispersants, and dispersing aids. In this embodiment, at least the aforementioned thiol having two or more SH groups is used as the chain transfer agent.

[0149] By using a polymerization aid, specifically a thiol having two or more SH groups as a chain transfer agent, a resin having the chemical structure (b1) can be obtained. By using a thiol having one SH group in addition to the thiol having two or more SH groups as a chain transfer agent, a resin having the chemical structure (b2) in addition to the chemical structure (b1) can be obtained.

[0150] As the chain transfer agent, the above-mentioned mercaptan having two or more SH groups is used.

[0151] Furthermore, as the chain transfer agent, in addition to the mercaptan having two or more SH groups, the above-mentioned mercaptan having one SH group may be used in combination.

[0152] Furthermore, chain transfer agents other than the mercaptan having one SH group and the mercaptan having two or more SH groups may be used in combination.

[0153] Examples of other chain transfer agents include hydrogen, diphenyl disulfide, dibenzyl disulfide, α-methylstyrene dimer, terpenes, and cobalt chain transfer agents.

[0154] The other chain transfer agents may be used alone or in combination of two or more.

[0155] The amount of the thiol having two or more SH groups used is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1 to 6 parts by mass, based on 100 parts by mass of all monomers used in the suspension polymerization.

[0156] The amount of thiol having one SH group used is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, and even more preferably 0 to 6 parts by mass, based on 100 parts by mass of all monomers used in the suspension polymerization.

[0157] The radical polymerization initiator is not particularly limited, and examples thereof include organic peroxides and azo compounds.

[0158] Examples of the organic peroxide include tert-butyl peroxypivalate, o-methylbenzoyl peroxide, bis(3,5,5-trimethylhexanoyl) peroxide, octanoyl peroxide, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropylbenzene peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxy-2-ethylhexanoate, and 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate.

[0159] Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile).

[0160] From the viewpoint of monomer polymerizability, benzoyl peroxide, lauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile) are preferred.

[0161] The radical polymerization initiator may be used alone or in combination of two or more.

[0162] The amount of the radical polymerization initiator used is not particularly limited, but is preferably 0.0001 to 10 parts by mass based on 100 parts by mass of all monomers used in the suspension polymerization from the viewpoint of increasing the polymerization rate of the monomers.

[0163] The dispersant is not particularly limited, and examples thereof include surfactants that stably disperse the monomer in water, and specific examples include copolymers of sodium methacrylate and methacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0164] The dispersants may be used alone or in combination of two or more.

[0165] The dispersing aid is not particularly limited, and examples thereof include sodium sulfate, sodium carbonate, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium chloride, calcium acetate, magnesium sulfate, and manganese sulfate.

[0166] The dispersing aids may be used alone or in combination of two or more.

[0167] The resin obtained by suspension polymerization is obtained in the form of a slurry. By dehydrating the slurry, the resin is generally obtained as nearly spherical beads.

[0168] (Dehydration process)

[0169] As the dehydration process, for example, there can be listed: a first dehydration process, in which the slurry after suspension polymerization is dehydrated using a dehydrator or the like to separate the resin from the reaction liquid; and a second dehydration process, in which the resin after the washing process described later is dehydrated using a dehydrator or the like to separate the resin as resin particles from the washing liquid.

[0170] Various dehydrators can be used in each dehydration step, such as those that filter using filter cloth, centrifugal dehydrators, or those that remove water by suction on a porous belt. A single dehydrator can be used, or two of the same model can be prepared and used in each dehydration step. Alternatively, multiple dehydrators of different models can be used. The model that best suits the purpose can be selected based on factors such as product quality, equipment investment costs, productivity, and operating costs. If a balance between product quality and production speed is important, dedicated dehydrators can be used for each dehydration step.

[0171] (Cleaning process)

[0172] The washing step is a step of washing the resin obtained in the first dehydration step.

[0173] The resin's purity is improved through the cleaning process. Examples of resin cleaning methods include adding a cleaning solution to the resin particles dehydrated in the first dehydration process, re-slurrying the particles, and stirring and mixing them; and performing the first dehydration process in a dehydrator equipped with a cleaning function, followed by adding a cleaning solution for cleaning. These cleaning methods can also be combined to clean the resin.

[0174] The type and amount of the cleaning liquid may be selected to achieve the purpose of the cleaning step. Examples of the cleaning liquid include water such as ion-exchanged water, distilled water, and purified water; aqueous solutions containing sodium salts; and alcohols such as methanol.

[0175] The cleaning liquids may be used alone or in combination of two or more.

[0176] (Drying process)

[0177] The drying step is a step of drying the resin particles (resin particles) obtained in the second dehydration step.

[0178] Water remains on the surface of the resin particles after the second dehydration step. When the interior of the resin is close to being saturated with water, drying is preferably performed to further reduce the water content of the resin from the viewpoint of improving the purity of the resin.

[0179] Various dryers can be used to dry the resin, for example: a dryer that dries by heating under reduced pressure; a dryer that dries while using heated air to transport the resin particles in a tube; and a dryer that dries while blowing heated air from the bottom of a porous plate to flow the resin particles located on the upper side.

[0180] The drying step is preferably performed so that the moisture content of the resin in the resin particles after the drying step is 0.01 to 10% by mass relative to the total mass of the resin.

[0181] <Effects>

[0182] The resin of the present embodiment described above is solid and has structural unit (a1), so it has excellent solvent solubility and thermal decomposition properties. In addition, the resin also has chemical structure (b1) in addition to structural unit (a1), so it has high thixotropy. The reason why the resin has high thixotropy due to having chemical structure (b1) is not clear, but it is believed to be as follows.

[0183] By having chemical structure (b1), the resin has many branched structures instead of a linear structure. Generally speaking, the more resin there is in a resin solution, the more thixotropic it becomes. However, when the resin has a linear structure, it is difficult to increase the amount of high-molecular-weight resin added due to the progress of thickening. On the other hand, in the case of a resin with a branched structure, the chain length is shorter than that of a linear structure, so thickening can be suppressed, and the amount of high-molecular-weight resin added can be increased. Therefore, it is believed that the resin has high thixotropy by having chemical structure (b1).

[0184] In particular, when the resin has the structural unit (a2) in addition to the structural unit (a1) and the chemical structure (b1), the thixotropy of the binder resin when dissolved in a solvent is improved.

[0185] Furthermore, when the resin has the chemical structure (b2) in addition to the structural unit (a1) and the chemical structure (b1), it is possible to suppress the thickening of the resin when it is dissolved in a solvent.

[0186] <Purpose>

[0187] The resin can be used as a raw material for internal electrode layers, a raw material for external electrode layers, and a raw material for pastes of solar cell electrodes in laminated electronic parts such as electronic devices, solar panels, and laminated ceramic capacitors.

[0188] [Paste composition]

[0189] Hereinafter, one embodiment of the paste composition of the present invention will be described.

[0190] The paste composition of this embodiment contains: the resin of the present invention described above; a metal or an inorganic compound; and an organic solvent.

[0191] The paste composition may further contain components other than the resin, the metal or the inorganic compound, and the organic solvent (hereinafter also referred to as “optional components”) as needed within a range that does not impair the effects of the present invention.

[0192] The resin content is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, relative to the total mass of the paste composition. A content of at least the above lower limit improves the formability of the paste composition. A content of at most the above upper limit increases the solids concentration of components other than the resin in the paste composition.

[0193] There are no particular restrictions on the metal or inorganic compound, and examples thereof include oxides such as aluminum oxide, zirconium oxide, titanium oxide, barium titanate, and calcium oxide; nitrides such as aluminum nitride, silicon nitride, and boron nitride; metals such as copper, silver, and nickel; silica-based powders such as low-melting-point glass powder; carbon-based powders such as carbon black; and various phosphors.

[0194] The metal or inorganic compound may be used alone or in combination of two or more.

[0195] The content of the metal or inorganic compound is preferably 40 to 90% by mass relative to the total mass of the paste composition. When the content is above the lower limit, the molding efficiency of the paste composition is improved. When the content is below the upper limit, the moldability of the paste composition is improved.

[0196] The organic solvent is not particularly limited, but is preferably an organic solvent having a boiling point of 180° C. or higher, more preferably an organic solvent having a boiling point of 200° C. or higher.

[0197] When the boiling point of the organic solvent is at least the above lower limit, uneven drying of the coating film during screen printing can be reduced.

[0198] The upper limit of the boiling point of the organic solvent is not particularly limited, but for example, the boiling point of the organic solvent is preferably 400°C or lower. For example, the boiling point of the organic solvent may be 180 to 400°C, or 200 to 400°C.

[0199] Examples of organic solvents having a boiling point of 180° C. or higher include α,β,γ-terpineol, terpineol acetate, dihydroterpineol, dihydroterpineol acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoisobutyl ether, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, isophorone, benzyl alcohol, 1-octane Alcohol, 1-nonanol, 2-ethyl-1-hexanol, 1-decanol, 1-undecanol, 1,2-ethanediol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, Texanol, butyl lactate, dioctyl phthalate, dioctyl adipate, phenylpropylene glycol, cresol, dimethyl sulfoxide, N-methylpyrrolidone.

[0200] From the viewpoint of having a boiling point of 200° C. or higher and being generally applicable, α,β,γ-terpineol, terpineol acetate, dihydroterpineol, dihydroterpineol acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoisobutyl ether, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate are preferred.

[0201] The organic solvent may be used alone or in combination of two or more.

[0202] The content of the organic solvent is preferably 9.9 to 50% by mass relative to the total mass of the paste composition. When the content is above the lower limit, the moldability of the paste composition improves. When the content is below the upper limit, the solid content concentration of the paste composition improves.

[0203] Examples of the optional components include a plasticizer, a dispersing aid, a defoaming agent, and resins other than the resin of the present invention.

[0204] The optional components may be used alone or in combination of two or more.

[0205] The paste composition can be obtained by mixing, for example, a resin, an inorganic compound, an organic solvent, and optionally, any other components.

[0206] Since the paste composition of the present embodiment described above contains the resin of the present invention, it has high thixotropy and is excellent in both printability when the paste composition is screen-printed and leveling property after printing.

[0207] The paste composition of this embodiment has excellent printability using screen printing. Therefore, when forming a pattern on a substrate using the paste composition of this embodiment, screen printing is preferably used. However, methods other than screen printing can also be used. For example, when the viscosity of the paste composition is high, dipping methods, dispenser coating methods, etc. can be used, while when the viscosity is low, blade coating methods, cast coating methods, etc. can be used.

[0208] The substrate on which the paste composition is printed or applied is not particularly limited, and examples thereof include ceramic substrates and capacitors.

[0209] [Inorganic sintered body]

[0210] Hereinafter, one embodiment of the inorganic sintered body of the present invention will be described.

[0211] The inorganic sintered body of the present embodiment is obtained by firing the above-mentioned paste composition of the present invention.

[0212] The firing method is not particularly limited, and examples thereof include a method of placing a substrate on which the paste composition is printed or applied in a high-temperature atmosphere.

[0213] During the firing process, organic substances such as resin contained in the paste composition are decomposed and removed, and metals or inorganic compounds contained in the paste composition are melted and sintered, thereby obtaining an inorganic sintered body.

[0214] The firing temperature can be appropriately determined depending on the melting temperature of the substrate, the inorganic powder, the type of organic substance contained in the paste composition, etc., and is usually about 200 to 1500°C, preferably 300 to 1000°C.

[0215] From the perspective of current collection performance, the electronic device of the present invention preferably comprises the above-mentioned inorganic sintered body. Examples of the above-mentioned electronic device include semiconductors such as logic circuits, memory circuits, analog circuits, lithium-ion batteries, capacitors, printed circuits, and current collection circuits of solar panels.

[0216] From the viewpoint of solar power generation, the solar panel of the present invention preferably has an inorganic sintered body.

[0217] Example

[0218] Hereinafter, the present invention will be described in further detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0219] Various measurement and evaluation methods in the following Examples and Comparative Examples are as follows.

[0220] In the following description, unless otherwise specified, "parts" means parts by mass and "%" means % by mass.

[0221] [Measurement / Evaluation Method]

[0222] <Measurement of Mass Average Particle Size>

[0223] The mass average particle size is determined by classifying 20 g of the granular resin by shaking it for 5 minutes using a standard sieve.

[0224] <Determination of Moisture Content>

[0225] The moisture content of the granular resin after drying the resin at 105° C. for 2 hours was set to 0%, and the moisture content was calculated from the loss on drying of the resin mass before and after drying.

[0226] <Measurement of Weight Average Molecular Weight (Mw) and Number Average Molecular Weight (Mn)>

[0227] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the resin were measured by gel permeation chromatography (GPC) and calculated as polystyrene-converted values ​​using a standard polystyrene calibration curve. To exclude the influence of unreacted substances, the lower limit of the molecular weight was calculated as 300. The GPC measurement conditions are as follows.

[0228] (GPC measurement conditions)

[0229] Device: Product name “HLC-8220GPC” manufactured by Tosoh Corporation.

[0230] Column: Two TSKgel SuperHZM-H ( )" are connected in series to form a column.

[0231] Eluent: tetrahydrofuran.

[0232] Sample concentration: 0.27% by mass

[0233] ·Measurement temperature: 40℃

[0234] Injection volume: 10 μL.

[0235] Flow rate: 0.5 mL / min.

[0236] Detectors: RI (built-in), UV (product name "UV-8220" manufactured by Tosoh Corporation).

[0237] <Determination of Acid Value>

[0238] Accurately weigh approximately 0.5 g of resin (α(g)) into a beaker and add 50 mL of a mixed solution of toluene and ethanol (mass ratio 1:1). Add a few drops of phenolphthalein and perform neutralization titration with a 0.05 N KOH solution (solvent: ethanol). (Titration = β(mL), potency of KOH solution = f). Perform a similar blank measurement (titration = γ(mL)) and calculate the solid acid value according to the following formula (3).

[0239] Acid value (mg KOH / g)={(β-γ)×0.05×56.11×f} / α…(3)

[0240] <Evaluation of Solvent Solubility>

[0241] 14 g of terpineol (manufactured by Takasago Fragrance Industry Co., Ltd., trade name "TERPINEOL PG") and a stirrer were placed in a glass bottle (manufactured by Kashiwayo Glass Co., Ltd., trade name "Standard Bottle No. 6"). While stirring, 6 g of resin was added and the bottle was capped. The mixture was then maintained at 50°C in a water bath and stirred at 500 rpm for 2 hours using a stirrer. The mixture was then cooled to room temperature to prepare a resin solution containing 30% by mass of the resin.

[0242] The appearance of the obtained resin solution was visually observed, and the solvent solubility was evaluated according to the following evaluation criteria.

[0243] A: No dissolved residue, no gelation, and a colorless and transparent resin solution.

[0244] B: Transparent resin solution, but gelation or generation of insoluble components was observed.

[0245] C: Cloudiness of the resin solution or precipitation of the resin was observed.

[0246] <Evaluation of Thermal Decomposition Properties>

[0247] Using a differential thermal balance (TG-DTA) (manufactured by Rigaku Corporation, product name "Thermo plus EVO"), 5 mg of a sample was heated from a starting temperature of 30°C to 500°C at a rate of 10°C / min in a nitrogen atmosphere. The mass of the residue at 450°C was measured, and the thermal weight loss (%) was calculated using the following formula (1). A higher thermal weight loss value indicates better thermal decomposition properties.

[0248] Thermal loss rate (%) = {(mass of measurement sample (mg) - mass of residue (mg)) / mass of measurement sample (mg)} × 100 (1)

[0249] <Evaluation of Thixotropy>

[0250] A resin solution containing 30% by mass of the resin was prepared in the same manner as in the evaluation of solvent solubility.

[0251] The viscosity (Pa·s) of the resin solution was measured using a viscoelasticity measuring instrument (manufactured by Thermo Fisher Scientific, product name "HAAKEMARS") at a cone-plate angle of 1.0° / 20 mm and a measurement temperature of 23°C. Solvent solubility was evaluated according to the following evaluation criteria, with the viscosity (Pa·s) at a shear rate of 1 (1 / s) being η1 and the viscosity (Pa·s) at a shear rate of 1000 (1 / s) being η1000. A higher value of η1 / η1000 indicates superior thixotropy.

[0252] A: The value of η1 / η1000 is 2.3 or more.

[0253] B: The value of η1 / η1000 is 2.0 or more and less than 2.3.

[0254] C: The value of η1 / η1000 is 1.5 or more and less than 2.0.

[0255] D: The value of η1 / η1000 is less than 1.5.

[0256] E: Unable to measure

[0257] [Example 1]

[0258] A monomer mixture consisting of 97.4 parts of isobutyl methacrylate and 2.6 parts of trimethylolpropane triacrylate uniformly dissolved, 1.9 parts of pentaerythritol tetrakis(thioglycolate), 1.9 parts of n-octyl mercaptan, and 1.9 parts of n-dodecyl mercaptan were added to a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer. The mixture was stirred and mixed until uniform. 0.3 parts of 2,2'-azobis(2-methylbutyronitrile) was then added and stirred and mixed until uniform. A mixture consisting of 145 parts of pure water, 0.15 parts of sodium sulfate, and 0.025 parts by mass of a copolymer of sodium methacrylate and methacrylic acid as a dispersant was then added and the atmosphere was replaced with nitrogen while stirring. The temperature in the flask was then controlled at 80°C to initiate suspension polymerization. After the peak of the polymerization exotherm was detected, the reaction mixture was kept at 85°C for 60 minutes, then cooled to below 40°C to obtain a suspension containing a resin.

[0259] The obtained suspension was filtered through a filter cloth, and the filtrate was washed with deionized water, dehydrated, and dried at 40° C. for 16 hours to obtain a particulate solid resin (A1).

[0260] The mass average particle size, water content, weight average molecular weight, and acid value of the obtained resin (A1) were measured, and the solvent solubility, thermal decomposition properties, and thixotropy were evaluated. The results are shown in Table 1.

[0261] [Examples 2 to 8, Comparative Examples 1 to 3]

[0262] Resins (A2) to (A11) were produced in the same manner as in Example 1 except that the formulations were set as shown in Table 1, and various measurements and evaluations were performed. The results are shown in Table 1.

[0263] [Table 1]

[0264] [Table 1]

[0265] The abbreviations in Table 1 have the following meanings. In addition, the blank column in the table means that the component was not blended (blending amount 0 part).

[0266] IBMA: Isobutyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "ACRYESTER IB")

[0267] MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "ACRYESTER M")

[0268] MAA: Methacrylic acid (manufactured by Mitsubishi Chemical Corporation, trade name "METHACRYLIC ACID")

[0269] TMPTA: trimethylolpropane triacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name "A-TMPT")

[0270] PETG: Pentaerythritol tetrakis(thioglycolate) (manufactured by Yodo Chemical Co., Ltd., trade name "Pentaerythritol tetrakis(thioglycolate) (PETG)")

[0271] PEMP: Pentaerythritol tetrakis(3-mercaptopropionate) (manufactured by SC Organic Chemical Co., Ltd., trade name "PEMP")

[0272] nDM: n-dodecyl mercaptan (manufactured by Chevron Phillips Chemical Company LLC., trade name "n-DM")

[0273] nOM: n-octyl mercaptan (manufactured by ARKEMA, trade name "n-OM")

[0274] AMBN: 2,2'-azobis(2-methylbutyronitrile) (manufactured by Otsuka Chemical Co., Ltd., trade name "AMBN")

[0275] As apparent from Table 1, it was confirmed that the resins (A1) to (A8) obtained in Examples 1 to 8 all exhibited excellent solvent solubility, thermal decomposition properties, and thixotropy.

[0276] On the other hand, the resins (A9) and (A10) obtained in Comparative Examples 1 and 2 lacked the chemical structure (b1) derived from a difunctional or higher-functional thiol group and therefore had poor thixotropy. Note that the thixotropy of Comparative Example 2 could not be measured due to significant gelation. However, due to the gelation, the thixotropy evaluation was E, and the weight-average molecular weight (Mw) and Mw / Mn could not be measured.

[0277] The resin (A11) obtained in Comparative Example 3 had a ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) outside the range specified in the present application, and therefore had poor thixotropy.

[0278] Industrial applicability

[0279] The resin of the present invention has excellent solvent solubility and thermal decomposition properties, and exhibits high thixotropy, resulting in excellent screen printability and post-printing leveling properties. The resin of the present invention is extremely important industrially as a raw material for internal electrode layers, a raw material for external electrodes, and a raw material for pastes used in multilayer electronic components such as electronic devices, solar panels, and multilayer ceramic capacitors.

Claims

A resin having a structural unit derived from a (meth)acrylate and a chemical structure derived from a thiol having two or more SH groups, wherein the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 5.0 or more.

2. The resin according to claim 1, wherein The resin is a solid binder for firing.

3. The resin according to claim 1 or 2, wherein The mass average particle size is greater than 100 μm and is 1500 μm or less.

4. The resin according to claim 1 or 2, wherein The acid value is 0 to 50 mgKOH / g. The resin according to claim 1 or 2, further comprising a chemical structure derived from a thiol having one SH group. The resin according to claim 1 or 2, further comprising a structural unit derived from a monomer having two or more polymerizable double bonds.

7. The resin according to claim 6, wherein The content of the structural unit derived from a monomer having two or more polymerizable double bonds is 0.1 to 5.0% by mass based on the structural units derived from all monomers of the resin.

8. The resin according to claim 1 or 2, wherein The thermal loss rate determined under the following measurement conditions is 95.0% or more. <Measurement Conditions of Thermal Loss Rate> Using a differential thermal balance (TG-DTA), 5 mg of the sample was heated from a starting temperature of 30°C to 500°C at a rate of 10°C / min in a nitrogen atmosphere. The mass of the residue at 450°C was measured, and the thermal weight loss rate was calculated using the following formula (1): Thermal weight loss rate (%) = {(mass of measurement sample (mg) - mass of residue (mg)) / mass of measurement sample (mg)} × 100 (1).

9. The resin according to claim 1 or 2, wherein A resin solution containing 30% by mass of the resin obtained by dissolving the resin in terpineol satisfies the following formula (2): η1 / η1000≥1.5···(2) Here, η1 and η1000 are the viscosities (Pa·s) of the resin solution measured using a viscoelasticity measuring apparatus at a cone plate of 1.0° / 20mm and a measurement temperature of 23°C. η1 is the viscosity (Pa·s) at a shear rate of 1 (1 / s), and η1000 is the viscosity (Pa·s) at a shear rate of 1000 (1 / s).

10. The resin according to claim 1 or 2, which has a weight average molecular weight of 10,000 to 1,000,000.

11. The resin according to claim 1 or 2, wherein The water content is 0.01 to 10% by mass relative to the total mass of the resin. 12 . A paste composition comprising: the resin according to claim 1 ; a metal or an inorganic compound; and an organic solvent.

13. The paste composition according to claim 12, wherein The boiling point of the organic solvent is 180° C. or higher. 14 . An inorganic sintered body obtained by sintering the paste composition according to claim 13 . 15 . An electronic device comprising the inorganic sintered body according to claim 14 . A solar panel comprising the inorganic sintered body according to claim 14 .

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