JP2006012709A - Conductive particulate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a conductive particulate excellent in heat resistance, excellent in dispersibility into resin by the lowering of specific weight, and with cost reduced. <P>SOLUTION: The conductive particulate (C), with a specific weight of 1 or more and 3 or less, has a polymer particulate (A) with a glass transition temperature of 100°C or higher and 300°C or lower composed of a polymer (a) as a kind selected from a group composed of polyurethane resin, polyester resin, polyamide resin, and epoxy resin coated with a conductive metal (B), especially, silver so as to have an average coating film thickness of 0.01 to 10 μm or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to conductive fine particles used for electromagnetic shielding materials and conductive adhesives. More specifically, the present invention relates to conductive fine particles that are low in cost and excellent in heat resistance and dispersibility in a resin by reducing specific gravity.

  An important characteristic required for conductive fine particles used in electromagnetic shielding and conductive adhesives is high conductivity, and metal particles, particularly metal ultrafine particles, are preferred, and silver ultrafine particles are also excellent in oxidation resistance. Because it is widely used. However, silver is an expensive substance, and an alternative material is required for further cost reduction. Silver ultrafine particles have a high specific gravity and have a problem of poor dispersibility in resins.

As an example in which the amount of silver used is reduced and the cost is reduced, the first coating layer of 0.01 to 0.2% Pd with respect to the Cu weight in order from the bottom on the surface of the core of the Cu particles, 1 to There is conductive fine particles (Patent Document 1) made of Ag and Ni-coated Cu powder having a second coating layer of 10.0% Ni, a third coating layer of 0.2 to 5.0% Ag. However, although the conductive fine particles have been improved to some extent in terms of cost, they still have the disadvantage of high specific gravity and poor dispersibility in the resin.
Further, as conductive fine particles having a reduced specific gravity, those having a metal layer on the surface of acrylic fine particles are generally well known (Patent Document 2). However, these conductive fine particles have low heat resistance and are used as conductive pastes. Had the disadvantage that it could not be used.

Japanese Patent Publication No. 7-97717 Japanese Patent Publication No. 7-97717

  The present invention has been made in view of the above situation, and provides conductive fine particles that reduce cost by reducing the amount of expensive silver used, and have excellent heat resistance and dispersibility in resin due to reduced specific gravity. It was made for the purpose of doing.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems.
That is, the present invention provides a polymer fine particle comprising a polymer (a) having a glass transition temperature of 100 ° C. or more and 300 ° C. or less and at least one selected from the group consisting of a polyurethane resin, a polyester resin, a polyamide resin, and an epoxy resin. Conductive fine particles (C), wherein (A) is coated with conductive metal particles (B), a conductive paste comprising (C) and a binder, and an electronic device using the conductive paste And the production method of (C).

  The conductive fine particles of the present invention are characterized in that the cost is reduced by reducing the amount of expensive silver used, and that the resin is excellent in heat resistance and dispersibility in resin due to reduced specific gravity.

The present invention is characterized by a glass transition temperature (hereinafter abbreviated as Tg) of 100 ° C. or higher and 300 ° C. or lower, and at least one selected from the group consisting of polyurethane resins, polyester resins, polyamide resins, and epoxy resins. The conductive fine particles (C) are characterized in that the polymer fine particles (A) made of the polymer (a) are coated with the conductive metal particles (B).
Tg of (A) is 100 ° C or higher, preferably 120 ° C or higher, more preferably 150 ° C or higher, 300 ° C or lower, preferably 270 ° C or lower, more preferably 250 ° C or lower. When Tg is less than 100 ° C., the heat resistance is poor, and when it exceeds 300 ° C., it is difficult to make fine particles.

 The measurement of Tg can be performed, for example, using a differential scanning calorimeter UV-DSC220C (manufactured by Seiko Co., Ltd.) after heat-treating at 180 ° C. for 10 hours and completely evaporating the solvent.

  The composition of the polymer (a) is a polymer having a Tg of 100 ° C. or more and 300 ° C. or less and at least one selected from the group consisting of polyurethane resins, polyester resins, polyamide resins, and epoxy resins.

  Among these, an epoxy resin and a polyamide resin are preferable. More preferable is an epoxy resin from the viewpoint of high heat resistance.

  The polyurethane resin is usually a resin obtained by polyaddition reaction of polyisocyanate (a1) and an active hydrogen-containing compound.

  (A1) includes diisocyanates and trifunctional or higher polyfunctional isocyanates; for example, aromatic polyisocyanates having 6 to 20 carbon atoms (excluding carbon in the NCO group, the same shall apply hereinafter), 18 aliphatic polyisocyanates, alicyclic polyisocyanates having 6 to 15 carbon atoms, araliphatic polyisocyanates having 8 to 15 carbon atoms and modified products of these polyisocyanates (urethane groups, carbodiimide groups, allophanate groups, burettes) Group, uretdione group, uretoimine group, isocyanurate group, modified product containing oxazolidone group) and a mixture of two or more thereof.

  Specific examples of the aromatic polyisocyanate include 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4. '-And / or 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl- 4,4'-diisocyanatodiphenylmethane, crude MDI [crude diaminodiphenylmethane [condensation product of formaldehyde and aromatic amine (aniline) or a mixture thereof; trifunctional of diaminodiphenylmethane and a small amount (for example, 5 to 20% by weight)] A mixture of the above with polyamine]; polyaryl polyiso Aneto], 1,5-naphthylene diisocyanate, 4,4 ', 4 "- triphenylmethane triisocyanate, include m- and p- isocyanatophenyl sulfonyl isocyanate.

  Specific examples of the aliphatic polyisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate. Lysine diisocyanate (2,6-diisocyanatomethylcaproate), bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexa Noate.

  Specific examples of the alicyclic polyisocyanate include, for example, isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl). ) -4-cyclohexene-1,2-dicarboxylate, 2,5- and / or 2,6-norbornane diisocyanate.

  Specific examples of the araliphatic polyisocyanate include m- and / or p-xylylene diisocyanate and α, α, α ', α'-tetramethylxylylene diisocyanate.

  Examples of modified polyisocyanates include modified MDI (urethane-modified MDI, carbodiimide-modified MDI, trihydrocarbyl phosphate-modified MDI), urethane-modified TDI, burette-modified HDI, isocyanurate-modified HDI, and isocyanurate-modified IPDI. Modified products of isocyanate and mixtures of two or more thereof [for example, combined use of modified MDI and urethane-modified TDI (isocyanate group-containing prepolymer)] are included.

  Among these, preferred are aliphatic and cycloaliphatic polyisocyanates, particularly HDI, IPDI, and hydrogenated MDI, which are less likely to discolor due to aging.

  The active hydrogen-containing compound includes a low-molecular polyfunctional active hydrogen-containing compound (a2) and a polymer polyol (a3).

  (A2) includes a low molecular polyol (a21) and a low molecular polyamine (a22).

As (a21), OH equivalent [number average molecular weight per hydroxyl group (measured by gel permeation chromatography (hereinafter abbreviated as GPC) or titration method)] is less than 300 (preferably 30 to 250). Or more (preferably 2-3 valence) polyol can be used.
Specific examples of (a21) include dihydric alcohols such as aliphatic diols [linear diols (ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1, 6-hexanediol, etc.), branched diols (propylene glycol, neopentyl glycol, 3-methyl 1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,2-, 1, 3- or 2,3-butanediol and the like], and diol having a cyclic group (for example, those described in JP-B No. 45-1474; 1,4-bis (hydroxymethyl) cyclohexane, m- or p-xylyl) Renglycol, dihydric phenol [(poly) oxyalkylene group such as bisphenol A Ter (alkylene having 2 to 4 carbon atoms, etc.); trivalent to 10-valent or higher polyhydric alcohol, such as alkane polyol (glycerin, trimethylolpropane, pentaerythritol, sorbitol, etc., and their intermolecular or molecular Internal dehydrates [dipentaerythritol, polyglycerol (degree of polymerization 2 to 8), sorbitan, etc.], saccharides and derivatives thereof (glycosides) (sucrose, methyl glucoside, etc.); and their alkylene oxides (hereinafter abbreviated as AO). C2-C10 or more, for example, what is mentioned in manufacture of below-mentioned (a32)] low molar adduct; and a mixture of these 2 or more types.
Of these, polyhydric alcohols are preferred, and glycerin and pentaerythritol are more preferred.

(A22) includes diamines having an amine equivalent (number average molecular weight per active hydrogen atom-containing amino group) of less than 300 (preferably 30 to 250) and trifunctional or higher polyfunctional amines; ) [Polyamine in which the isocyanate group in (a1) is replaced with an amino group]. Specifically, diamines such as aliphatic diamines [ethylene diamine, hexamethylene diamine, etc.], alicyclic diamines [4,4′-diamino-3,3′-dimethyldicyclohexylmethane, 4,4′-diamino-3, 3′-dimethyldicyclohexyl, diaminocyclohexane, isophoronediamine, etc.], aromatic diamine [diethyltoluenediamine, etc.], araliphatic diamine [xylylenediamine, α, α, α ′, α′-tetramethylxylylenediamine, etc.] A heterocyclic diamine (such as piperidine); a polyfunctional amine having 3 to 6 or more valences, such as polyalkylene (having 2 to 6 carbon atoms) polyamine (such as diethylenetriamine and triethylenetetramine), polyphenylmethane polyamine (formaldehyde and aniline) A condensation product of Mixtures of two or more of these and the like.
Of these, preferred are polyfunctional amines, and particularly preferred are diethylenetriamine and triethylenetetramine.

As the polymer polyol (a3), a polyol having a OH equivalent [number average molecular weight per hydroxyl group] of 300 or more (preferably 300 to 10,000) of 2 to 4 or more (preferably 2 to 3) is used. Can be used.
(A3) includes polyester polyol (a31), polyether polyol (a32), and mixtures of two or more thereof.

Examples of (a31) include condensed polyester polyol (a311) (by polycondensation of polyol and polycarboxylic acid), polylactone polyol (a312) (one obtained by ring-opening polymerization of a lactone monomer using a polyol as an initiator). Polycarbonate polyol (a313) [by reaction of polyol and alkylene (2 to 4 carbon atoms) carbonate (such as ethylene carbonate), phosgenation or transesterification with diphenyl carbonate]; and a mixture of two or more of these It is done.

As the polyol in (a311), (a312), and (a313), one or more of low-molecular-weight polyols (for example, (a21) described above) and / or polyether polyols (for example (a32)) can be used.

The polycarboxylic acids in (a311) include polycarboxylic acids and their ester-forming derivatives.
Specific examples include aliphatic polycarboxylic acids [polycarboxylic acids having 2 to 6 functional groups and 3 to 30 carbon atoms such as succinic acid, glutaric acid, maleic acid, fumaric acid, adipic acid, azelaic acid, sebacic acid, hexa Hydrophthalic acid, etc.], aromatic polycarboxylic acids [polycarboxylic acids having 2 to 6 functional groups and 8 to 30 carbon atoms, such as phthalic acid, isophthalic acid, terephthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid, trimellit Acid, pyromellitic acid, etc.]; these ester-forming derivatives [acid anhydrides, lower alkyl (carbon number 1-4) esters (dimethyl esters, diethyl esters, etc.), acid halides (acid chlorides, etc.): for example, maleic anhydride Acid, phthalic anhydride, dimethyl terephthalate, etc.]; and mixtures of two or more thereof.
Of these, aliphatic polycarboxylic acids are preferred.

  Examples of the lactone monomer in (a312) include lactones having 3 to 17 carbon atoms (preferably 4 to 12), such as γ-butyrolactone, ε-caprolactone, γ-valerolactone, and mixtures of two or more thereof.

  (A32) includes a compound in which AO is added to a compound having two or more active hydrogen atoms.

  Examples of the compound having an active hydrogen atom include a low molecular polyol [for example, (a21)]; divalent phenols [for example, bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.), monocyclic phenols (catechol, hydroquinone, etc.) )]; Amines [primary monoamines such as alkyl or alkenyl amines (1 to 20 carbon atoms), anilines, alkanolamines (2 to 4 carbon atoms of the hydroxyl alkyl group) (such as those mentioned in the terminators below), polyamines such as (A22), heterocyclic polyamines such as piperazine, aminoalkyl (2 to 4 carbon atoms) piperazine (such as aminoethylpiperazine)] and the like.

  As AO, ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), 1,2-, 1,3-, 1,4- and 2,3-butylene oxide, styrene oxide, carbon number 5 -10 or more α-olefin oxides, epichlorohydrin, and combinations of two or more thereof (block and / or random addition).

  Among these, preferred are those obtained by adding AO (particularly PO) to divalent phenols (particularly bisphenols).

  In this case, the OH equivalent of (a3) is preferably 300 to 10,000, more preferably 500 to 5,000, and particularly preferably 1,000 to 3,000 from the viewpoint of Tg.

  The production of the polyurethane resin can be carried out by an ordinary method, in which the active hydrogen-containing compound and (a1) are all reacted together (one-shot method), and a part of these reaction components is reacted in advance. Examples include a method (prepolymer method) in which a multistage reaction is performed via an isocyanate group or a hydroxyl group-terminated urethane prepolymer (a0). Preference is given to a prepolymer process, in particular a process in which the isocyanate group-terminated urethane prepolymers (a0) and (a2) (extenders and / or crosslinkers) and / or terminators are reacted.

The isocyanate group-terminated urethane prepolymer (a0) is preferably formed by the reaction of (a1) with (a3) and optionally (a2). In this case, the equivalent ratio of (a1) to (a2) and (a3) is usually 0.1 to 0.8 equivalent, preferably 0.2 to 0.6, relative to (a1) 1 equivalent. Equivalent (a3) is usually 0.05 to 0.7 equivalent, preferably 0.1 to 0.5 equivalent.
The isocyanate group content in (a) is usually 0.5 to 10% by weight, preferably 1.5 to 6% by weight.

  Examples of the extender include the diols mentioned in the above (a21), the diamines mentioned in (a22), their ketimine compounds, for example, the above amines and ketones having 3 to 8 carbon atoms [acetone, methyl ethyl ketone, methyl isobutyl ketone (hereinafter referred to as “extensions”). Abbreviated as MIBK) and the like], and water. A ketimine compound is preferred.

  Examples of the crosslinking agent include the polyhydric alcohols mentioned in (a21) and the polyfunctional amines mentioned in (a22) (diethylenetriamine, triethylenetetramine, etc.).

  Examples of the terminator include monoamines having 1 or 2 hydroxyalkyl groups having 2 to 4 carbon atoms, and aliphatic monoamines having no hydroxyl group.

Monoamines having one or two hydroxyalkyl groups include monoalkanolamines [monoethanolamine, monopropanolamine, etc.]; dialkanolamines [diethanolamine, dipropanolamine, etc.] and mixtures of two or more thereof. .
Of these, dialkanolamine is preferable, and diethanolamine and dipropanolamine are particularly preferable.

Aliphatic monoamines having no hydroxyl group include alicyclic monoamines [(mono- and di-cycloalkyl (5 to 18 carbon atoms) such as cyclopentylamine, cyclohexylamine, etc.], aliphatic monoamines [mono-and Di-alkyl or alkenyl (C1-C20) amines such as methylamine, ethylamine, propylamine, butylamine, octylamine, 2-ethylhexylamine, nonylamine, oleylamine, N-methylbutylamine, diethylamine, dibutylamine and the like] and A mixture of two or more of these may be mentioned.
Among these, preferred are aliphatic monoamines having no hydroxyl group, and particularly preferred are butylamine, octylamine, 2-ethylhexylamine, and dibutylamine.

The charging ratio of the extender, the terminator, and the crosslinking agent to the urethane prepolymer (a0) is appropriately selected within a range in which a polyurethane resin having a predetermined number average molecular weight is formed. For example, the equivalent ratio of the extender to 1 equivalent of isocyanate group in (a0) is preferably 0.05 to 0.8 equivalent, more preferably 0.1 to 0.6 equivalent. Moreover, the equivalent ratio of the terminator is usually 0 to 0.2 equivalent, preferably 0.05 to 0.1 equivalent, and the equivalent ratio of the crosslinking agent is usually 0.1 to 0.8 equivalent, preferably 0. .2 to 0.6 equivalents.
In addition, the total equivalent ratio of the extender + termination agent + crosslinking agent to 1 equivalent of the isocyanate group in (a0) is preferably 0.1 to 2.3 equivalents, more preferably 0.3 to 1.7 equivalents. .

When the polymer (a) in the present invention is a polyester resin, examples thereof include polycondensates of polycarboxylic acids and polyols, compounds having carboxyl groups and hydroxyl groups in the same molecule, and polycondensates of anhydrides thereof.
Examples of the polycarboxylic acids include those described in the above (a311). Of these, preferred are aliphatic polycarboxylic acids (especially succinic acid, maleic acid, adipic acid, azelaic acid, sebacic acid) and aromatic polycarboxylic acids (especially phthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride). Dimethyl terephthalate, etc.).
These polycarboxylic acids can be used as one kind or a mixture of two or more kinds.
Moreover, when making it bridge | crosslink in a polyesterification reaction process, trifunctional or more polycarboxylic acid (For example, trimellitic acid, pyromellitic acid, etc.) can be used together.

As the polyol, a low molecular polyol and / or a polyether polyol can be used.
Examples of the low molecular polyol include the above-mentioned (a2). Preferred are dihydric alcohols such as aliphatic diols (especially ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.), branched diols (propylene glycol, neopentyl glycol), bisphenol A (Poly) oxyalkylene ether (alkylene group having 2 to 4 carbon atoms).

As the polyether polyol, the aforementioned (a32) may be mentioned. Preferred are low molecular polyols (especially aliphatic diols) with addition of AO (especially PO).

  The number average molecular weight of these polyether polyols is preferably 1,000 to 20,000. Moreover, these low molecular weight and polyether polyols can be used by 1 type, or 2 or more types of mixtures.

  In the case of crosslinking in the polyesterification reaction step, a trifunctional or higher functional polyol (for example, a tri- to trivalent polyhydric alcohol among those described in the above (a21)) may be used in combination.

  Examples of the compound having a carboxyl group and a hydroxyl group in the same molecule or an anhydride thereof include (a312) described above. Preference is given to γ-butyrolactone, ε-caprolactone, and mixtures thereof.

  Moreover, when using trifunctional or more than polycarboxylic acid and / or polyol, it is 0.01-10 weight% normally with respect to the total weight of polycarboxylic acid and polyol, Preferably it is 0.03-5 weight% 3 or more functional groups are used.

The temperature during the polycondensation of the polyester resin is usually 100 to 300 ° C, preferably 130 to 220 ° C. The atmosphere during the polymerization is desirably performed in the presence of an inert gas such as nitrogen.
The equivalent ratio of polycarboxylic acids and polyols during polymerization is an equivalent ratio of carboxylic acid / hydroxyl group, and preferably 1 / 0.7 to 1 / 1.1.
The acid value after polycondensation is preferably 10 or less.

When the polymer (a) of the present invention is a polyamide resin, examples thereof include polycondensates of polycarboxylic acids and polyamines, compounds having a carboxyl group and an amino group in the same molecule, or polycondensates of anhydrides thereof.
Examples of polycarboxylic acids include the polycarboxylic acids described in (a311) above. Of these, aliphatic polycarboxylic acids (especially maleic acid, adipic acid, azelaic acid) and aromatic polycarboxylic acids (especially phthalic acid, terephthalic acid, dimethyl terephthalate, etc.) are preferred.
These polycarboxylic acids can be used as one kind or a mixture of two or more kinds.

Examples of the polyamine include those described in the above (a22). Of these, preferred are aliphatic diamines (hexamethylenediamine, 1,5-pentanediamine, etc.) and araliphatic diamines (xylylenediamine, etc.). These polyamines can be used alone or in a mixture of two or more.
Specific examples of the compound having a carboxylic acid group and an amino group in the same molecule or an anhydride thereof include amino acids having 2 to 30 carbon atoms such as ε-aminoundecanoic acid, lauryl lactam, enanthractam, ε-caprolactam and the like. Examples thereof include lactams having 4 to 10 carbon atoms.

  In the case of crosslinking in the polyamidation reaction step, a tri- or higher functional polycarboxylic acid (for example, trimellitic acid, pyromellitic acid, etc.) is used in combination, or a tri- or higher functional polyamine [for example, described in (a22) above] 3 to 6 or more polyfunctional amines may be used in combination.

  Moreover, when using polycarboxylic acids and / or polyamines having three or more functional groups, usually 0.1 to 20% by weight, preferably 0.5 to 10% by weight, based on the total weight of the polycarboxylic acids and polyamines. It is.

  The polyamide resin can be obtained by polycondensation of the above polycarboxylic acids and polyamines. The temperature during polycondensation is usually 120 to 300 ° C, preferably 150 to 220 ° C. The atmosphere during the polymerization is desirably performed in the presence of an inert gas such as nitrogen. The equivalent ratio of polycarboxylic acids and polyamines at the time of polymerization is an amine / hydroxyl equivalent ratio, preferably 1 / 0.7 to 1 / 1.1. The amine value after condensation polymerization is preferably 10 or less.

  When the polymer (a) is an epoxy resin, aromatic, heterocyclic, alicyclic and aliphatic polyepoxides (number of epoxy groups is 2 to 4, epoxy equivalent is 70 to 4,000 eq / g). ) Polymerized products and cured products.

Examples of the aromatic polyepoxide include glycidyl ethers of polyhydric phenols and glycidyl aromatic polyamines.
Examples of glycidyl ethers of polyphenols include bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, bisphenol B diglycidyl ether, bisphenol AD diglycidyl ether, bisphenol S diglycidyl ether, halogenated bisphenol A diglycidyl, and tetrachlorobisphenol A. Diglycidyl ether, catechin diglycidyl ether, resorcinol diglycidyl ether, hydroquinone diglycidyl ether, pyrogallol triglycidyl ether, 1,5-dihydroxynaphthalene diglycidyl ether, dihydroxybiphenyl diglycidyl ether, octachloro-4,4'-dihydroxybiphenyl di Glycidyl ether, phenol or cresol novolac tree A glycidyl ether of fat, a diglycidyl ether obtained from the reaction of 2 mol of bisphenol A and 3 mol of epichlorohydrin, a polyglycidyl ether of polyphenol obtained by the condensation reaction of phenol and glycoxal, glutaraldehyde, or formaldehyde, and Examples thereof include polyglycidyl ethers of polyphenols obtained by condensation reaction of resorcin and acetone.
Examples of the glycidyl aromatic polyamine include N, N-diglycidylaniline and N, N, N ′, N′-tetraglycidyldiphenylmethanediamine. Furthermore, in the present invention, as the aromatic system, a diglycidyl urethane compound obtained by addition reaction of tolylene diisocyanate or diphenylmethane diisocyanate and glycidol, a glycidyl group-containing polyurethane (pre) polymer obtained by reacting the two reactants with a polyol. And diglycidyl ethers of bisphenol A alkylene oxide (ethylene oxide or propylene oxide) adducts.

  Heterocyclic systems include trisglycidyl melamine.

  Alicyclics include vinylcyclohexene dioxide, limonene dioxide, dicyclopentadiene dioxide, bis (2,3-epoxycyclopentyl) ether, ethylene glycol bisepoxy dicyclopentyl ale, 3,4-epoxy-6-methyl. Cyclohexylmethyl-3 ′, 4′-epoxy-6′-methylcyclohexanecarboxylate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, and bis (3,4-epoxy-6-methylcyclohexylmethyl) Butylamine is mentioned. Moreover, as an alicyclic type | system | group, the nuclear hydrogenation thing of the said aromatic polyepoxide is also included.

Aliphatics include polyglycidyl ethers of polyhydric alcohols, polyglycidyl esters of polycarboxylic acids, and glycidyl aliphatic amines.
As the polyglycidyl ether of polyhydric alcohol, the polyglycidyl ether of (a21), for example, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tetramethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl. And ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, and sorbitol polyglycidyl ether.
Examples of the polyglycidyl ester of polycarboxylic acid include the polyglycidyl ester of (a311), for example, a (co) polymer of diglycidyl adipate and glycidyl (meth) acrylate.
Examples of the glycidyl aliphatic amine include the polyglycidylated product (a22), for example, N, N, N ′, N′-tetraglycidylhexamethylenediamine.

  As a method for producing an epoxy resin, a method of ring-opening polymerization of the above polyepoxide using a catalyst (an alkaline inorganic compound such as alkali hydroxide, a quaternary ammonium salt, a Lewis acid, etc.) and a polyamine [as described above] And (a22) aliphatic polyamine or aromatic polyamine, etc.], followed by ring-opening and crosslinking to cure.

  The number average molecular weight (Mn) of the polymer (a) is preferably 2000 or more, more preferably 5000 or more, and particularly preferably 10,000 or more from the viewpoint of gas permeability. From the viewpoint of true specific gravity, it is preferably 1,000,000 or less, more preferably 500,000 or less, and particularly preferably 200,000 or less.

As described above, the polymer (a) has a glass transition temperature of 100 ° C. or higher and 300 ° C. or lower. Examples of the production method (a) include a method in which a crosslinking agent is used in the polymerization reaction step as described above, and a method in which a crosslinking agent is further added to each resin after polymerization to perform crosslinking.
As the crosslinking agent after polymerization, known ones can be used. For example, when a carboxyl group is present as a functional group in the resin, polyepoxide [for example, the above-described polyepoxide, preferably aromatic such as bisphenol A diglycidyl ether, trisglycidyl, etc. Heterocyclic systems such as melamine, alicyclic systems such as vinylcyclohexene dioxide, and aliphatic systems such as polyethylene glycol diglycidyl ether, glycidyl (meth) acrylate (co) polymers] and melamine resins [trimethylolmelamine, hexa Methylol melamine, methoxytrimethylol melamine and mixtures thereof] and the like.
When the reactive functional group in the polymer (a) is a hydroxyl group, examples of the crosslinking agent include the aforementioned polycarboxylic acids, polyisocyanate (a1), and the above melamine resin. When the reactive functional group is an epoxy group, the above-described polycarboxylic acids are exemplified.

The polymer (a) is preferably crosslinked from the viewpoint of heat resistance.
The molecular weight between crosslinks of the polymer (a) is preferably 500 or more from the viewpoint of specific gravity after expansion, more preferably 1000 or more, and preferably 5000 or less, more preferably 4000 or less from the viewpoint of liquid retention. .
The molecular weight between crosslinks can be calculated by using, for example, the following formula.

For the number average molecular weight, charge weight, number of functional groups of each component,
Molecular weight between crosslinks = ΣW / Σ [{W (f-2)} / M]
(M is the number average molecular weight of each monomer component constituting the polymer (a), W is the charged weight of each monomer component constituting the polymer (a), and f is each single amount constituting the polymer (a). Number of functional groups in body components)

Although the method for obtaining the polymer fine particles (A) of the present invention in the form of fine particles (beads) is not particularly limited, the following (1) to (4) can be mentioned.
(1) When the polymer (a) is a polyaddition or condensation resin such as a polyamide resin, a polyester resin, a polyurethane resin, or an epoxy resin, the precursor (monomer, oligomer, etc.) of (a), or (a) A method in which the following emulsifier is dissolved in a solvent (X) solution of a precursor (preferably a liquid. It may be liquefied by heating), and then water is added to perform phase inversion emulsification and polymerization.
(2) A resin obtained by dissolving a polymer (a) previously prepared by a polymerization reaction (any polymerization reaction mode such as addition polymerization, ring-opening polymerization, polyaddition, addition condensation, condensation polymerization, etc.) in a solvent (X) A polymer in which a poor solvent (Y) is added to the solution, or a poor solvent (Y) is added to a resin solution in which the polymer (a) is dissolved in the solvent (X), or the polymer is previously dissolved in the solvent (X) by heating. A method in which the polymer (a) particles are precipitated by cooling the solution of (a) and dispersed in water.
(3) Dissolved in the solvent (X) containing the polymer (a) prepared in advance by a polymerization reaction (any polymerization reaction mode such as addition polymerization, ring-opening polymerization, polyaddition, addition condensation, condensation polymerization, etc.) A method in which the polymer (a) solution is dispersed in an aqueous medium in the presence of the following dispersant, and the solvent is removed by heating or decompression.
(4) A polymer prepared by previously dissolving a polymer (a) in a solvent (X) by a polymerization reaction (any polymerization reaction mode such as addition polymerization, ring-opening polymerization, polyaddition, addition condensation, condensation polymerization, etc.) (A) A method in which the following emulsifier is dissolved in a solution, and then water is added to perform phase inversion emulsification.
Among the above methods, the method (1) is most preferable.

The solvent (X) is used for the purpose of dissolving the resin and needs to be able to uniformly dissolve the polymer (a).
Specific examples include aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ester or ester ether solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate, methyl cellosolve acetate, and ethyl cellosolve acetate; acetone, methyl ethyl ketone, methyl Ketone solvents such as isobutyl ketone, di-n-butyl ketone and cyclohexanone; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, 2-ethylhexyl alcohol and benzyl alcohol; Amide solvents such as dimethylformamide and dimethylacetamide; Sulfoxide solvents such as dimethylsulfoxide, and heterocyclic compound systems such as N-methylpyrrolidone Agent, and a mixed solvent of two or more thereof. Of these, preferred are aromatic hydrocarbon solvents, and more preferred are toluene and xylene.

The poor solvent (Y) is used for the purpose of precipitating the resin, and the solubility of the polymer (a) is required to be 1% by weight or less at 25 ° C.
Specific examples include aliphatic or alicyclic hydrocarbon solvents such as n-hexane, n-heptane, mineral spirit, and cyclohexane; methyl chloride, methyl bromide, methyl iodide, methylene dichloride, carbon tetrachloride, trichloroethylene, Halogen solvents such as perchloroethylene; ether solvents such as diethyl ether, tetrahydrofuran, dioxane, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, di-n-butyl ketone, and cyclohexanone A solvent and a mixed solvent of two or more of these may be mentioned. Of these, preferred are aliphatic hydrocarbon solvents, and more preferred are n-hexane and n-heptane.

  In the above methods (1) to (4), as the emulsifier or dispersant to be used, a known surfactant (S), water-soluble polymer (T) or the like can be used. Moreover, a solvent (U) etc. can be used together as an auxiliary agent for emulsification or dispersion.

  As the surfactant (S), anionic surfactant (S-1), cationic surfactant (S-2), amphoteric surfactant (S-3), nonionic surfactant (S-4) and the like. Is mentioned. The surfactant (S) may be a combination of two or more surfactants.

  Examples of the anionic surfactant (S-1) include carboxylic acid or a salt thereof, a sulfate ester salt, a salt of carboxymethylated product, a sulfonate salt, and a phosphate ester salt.

  Examples of carboxylic acids or salts thereof include saturated or unsaturated fatty acids having 8 to 22 carbon atoms or salts thereof. Specifically, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. , Oleic acid, linoleic acid, ricinoleic acid and a mixture of higher fatty acids obtained by saponifying coconut oil, palm kernel oil, rice bran oil, beef tallow and the like. Examples of the salt include salts of sodium, potassium, ammonium, alkanolamine and the like.

  Examples of sulfate salts include higher alcohol sulfate esters (sulfate esters of aliphatic alcohols having 8 to 18 carbon atoms) and higher alkyl ether sulfate esters salts (1 to 10 moles of ethylene oxide of aliphatic alcohols having 8 to 18 carbon atoms). Sulfates of adducts), sulfated oils (natural unsaturated oils or unsaturated waxes that have been neutralized by sulfation), sulfated fatty acid esters (sulfurized lower alcohol esters of unsaturated fatty acids) And sulphated olefins (sulphated and neutralized olefins having 12 to 18 carbon atoms). Examples of the salt include sodium salt, potassium salt, ammonium salt, and alkanolamine salt. Specific examples of higher alcohol sulfates include octyl alcohol sulfate, decyl alcohol sulfate, lauryl alcohol sulfate, stearyl alcohol sulfate, alcohols synthesized using Ziegler catalysts (for example, ALFOL 1214: CONDEA's sulfate ester salt, alcohols synthesized by the oxo method (for example, Dovanol 23, 25, 45: Mitsubishi Yuka, Tridecanol: Kyowa Hakko, Oxocol 1213, 1215, 1415: Nissan Chemical, Diadol 115 -L, 115H, 135: manufactured by Mitsubishi Chemical); specific examples of higher alkyl ether sulfates include lauryl alcohol ethylene oxide 2-mol adduct sulfate, octyl alcohol ethylene Oxide 3-mole adduct sulfate ester; Specific examples of sulfated oils include sodium, potassium, ammonium, alkanolamine salts sulfated fatty acids of castor oil, peanut oil, olive oil, rapeseed oil, beef tallow, sheep fat, etc. Specific examples of the ester include sodium, potassium, ammonium, and alkanolamine salts of sulfates such as butyl oleate and butyl ricinoleate; specific examples of the sulfated olefin include Typol (manufactured by Shell).

  Examples of the carboxymethylated salt include a carboxymethylated salt of an aliphatic alcohol having 8 to 16 carbon atoms and a carboxymethylated salt of an ethylene oxide 1 to 10 mol adduct of an aliphatic alcohol having 8 to 16 carbon atoms. It is done. Specific examples of salts of carboxymethylated products of aliphatic alcohols include octyl alcohol carboxymethylated sodium salt, decyl alcohol carboxymethylated sodium salt, lauryl alcohol carboxymethylated sodium salt, dovanol 23 carboxymethylated sodium salt, tridecanol Specific examples of salts of carboxymethylated sodium salt of carboxymethylated product of aliphatic alcohol ethylene oxide 1-10 mol adduct include octyl alcohol ethylene oxide 3 mol adduct carboxymethylated sodium salt, lauryl alcohol ethylene oxide 4 Mole adduct carboxymethylated sodium salt, dovanol 23 ethylene oxide 3 mol adduct carboxymethylated sodium salt, tridecanol ethylene oxide Such as 5 mole adduct carboxymethylated sodium salt.

  Examples of the sulfonate include (d1) alkylbenzene sulfonate, (d2) alkylnaphthalene sulfonate, (d3) sulfosuccinic acid diester type, (d4) α-olefin sulfonate, (d5) Igepon T type, (d6 ) Other sulfonates of aromatic ring-containing compounds. Specific examples of alkylbenzene sulfonate include sodium dodecylbenzene sulfonate; specific examples of alkyl naphthalene sulfonate; sodium dodecyl naphthalene sulfonate; specific examples of sulfosuccinic acid diester type include di-2 sulfosuccinic acid di-2 -Ethylhexyl ester sodium salt and the like. Examples of the sulfonate of the aromatic ring-containing compound include mono- or disulfonate of alkylated diphenyl ether, styrenated phenol sulfonate, and the like.

  Examples of phosphoric acid ester salts include (e1) higher alcohol phosphoric acid ester salts and (e2) higher alcohol ethylene oxide adduct phosphoric acid ester salts.

  Specific examples of higher alcohol phosphoric acid ester salts include lauryl alcohol phosphoric acid monoester disodium salt, lauryl alcohol phosphoric acid diester sodium salt; specific examples of higher alcohol ethylene oxide adduct phosphoric acid ester salts include oleyl alcohol ethylene oxide 5 mol adduct phosphate monoester disodium salt.

  Examples of the cationic surfactant (S-2) include a quaternary ammonium salt type and an amine salt type.

  The quaternary ammonium salt type is obtained by a reaction between a tertiary amine and a quaternizing agent (an alkylating agent such as methyl chloride, methyl bromide, ethyl chloride, benzyl chloride, dimethyl sulfate; ethylene oxide, etc.) For example, lauryl trimethyl ammonium chloride, didecyl dimethyl ammonium chloride, dioctyl dimethyl ammonium bromide, stearyl trimethyl ammonium bromide, lauryl dimethyl benzyl ammonium chloride (benzalkonium chloride), cetyl pyridinium chloride, polyoxyethylene trimethyl ammonium chloride, stearamide ethyl diethyl Examples include methylammonium methosulfate.

  As amine salt type, primary to tertiary amines are inorganic acids (hydrochloric acid, nitric acid, sulfuric acid, hydroiodic acid, etc.) or organic acids (acetic acid, formic acid, oxalic acid, lactic acid, gluconic acid, adipic acid, alkylphosphoric acid, etc.) It is obtained by neutralizing with For example, the primary amine salt type includes inorganic or organic acid salts of higher aliphatic amines (higher amines such as laurylamine, stearylamine, cetylamine, hardened tallow amine, and rosinamine); Examples include fatty acid (stearic acid, oleic acid, etc.) salts and the like. Examples of the secondary amine salt type include inorganic acid salts or organic acid salts such as ethylene oxide adducts of aliphatic amines. Examples of the tertiary amine salt type include aliphatic amines (triethylamine, ethyldimethylamine, N, N, N ′, N′-tetramethylethylenediamine, etc.), ethylene oxides of aliphatic amines (2 moles). Above) Adducts, alicyclic amines (N-methylpyrrolidine, N-methylpiperidine, N-methylhexamethyleneimine, N-methylmorpholine, 1,8-diazabicyclo (5,4,0) -7-undecene, etc.) , Inorganic acid salts or organic acid salts of nitrogen-containing heterocyclic aromatic amines (4-dimethylaminopyridine, N-methylimidazole, 4,4′-dipyridyl, etc.); triethanolamine monostearate, stearamide ethyl diethyl methyl ethanol Examples include inorganic acid salts or organic acid salts of tertiary amines such as amines.

  The amphoteric surfactant (S-3) used in the present invention includes a carboxylate type amphoteric surfactant, a sulfate ester type amphoteric surfactant, a sulfonate type amphoteric surfactant, and a phosphate ester type amphoteric interface. Examples of the surfactant include amphoteric surfactants and amino acid-type amphoteric surfactants and betaine-type amphoteric surfactants.

Examples of the carboxylate-type amphoteric surfactants include amino acid-type amphoteric surfactants, betaine-type amphoteric surfactants, and imidazoline-type amphoteric surfactants. Examples of amphoteric surfactants having an amino group and a carboxyl group include compounds represented by the following general formula.
[R—NH— (CH ₂ ) n —COO] mM [wherein R is a monovalent hydrocarbon group; n is usually 1 or 2; m is 1 or 2; M is a hydrogen atom, an alkali metal atom, an alkali An earth metal atom, an ammonium cation, an amine cation, an alkanolamine cation and the like. Specific examples include, for example, alkylaminopropionic acid type amphoteric surfactants (such as sodium stearylaminopropionate and sodium laurylaminopropionate); alkylaminoacetic acid type amphoteric surfactants (such as sodium laurylaminoacetate), and the like. It is done.

  Betaine-type amphoteric surfactants are amphoteric surfactants having a quaternary ammonium salt-type cation moiety and a carboxylic acid-type anion moiety in the molecule. For example, alkyldimethylbetaine (stearyl) represented by the following general formula: Dimethylaminoacetic acid betaine, lauryl dimethylaminoacetic acid betaine, etc.), amide betaine (coconut oil fatty acid amide propyl betaine etc.), alkyl dihydroxyalkyl betaine (lauryl dihydroxyethyl betaine etc.) etc. are mentioned.

  Furthermore, examples of the imidazoline type amphoteric surfactant include 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine.

  Examples of other amphoteric surfactants include glycine-type amphoteric surfactants such as sodium lauroyl glycine, sodium lauryl diaminoethyl glycine, lauryl diaminoethyl glycine hydrochloride, dioctyl diaminoethyl glycine hydrochloride; pentadecylsulfotaurine and the like Examples include sulfobetaine-type amphoteric surfactants.

  Examples of the nonionic surfactant (S-4) include alkylene oxide addition type nonionic surfactants and polyvalent alcohol type nonionic surfactants.

  Alkylene oxide addition type nonionic surfactants include polyalkylene glycols obtained by adding alkylene oxide directly to higher alcohols, higher fatty acids or alkylamines, or by adding alkylene oxides to glycols. It is obtained by reacting a higher fatty acid with a higher fatty acid, adding an alkylene oxide to an esterified product obtained by reacting a higher fatty acid with a polyhydric alcohol, or adding an alkylene oxide to a higher fatty acid amide.

  Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide. Of these, preferred are ethylene oxide and random or block adducts of ethylene oxide and propylene oxide. The number of moles of alkylene oxide added is preferably 10 to 50 moles, and 50 to 100% by weight of the alkylene oxide is preferably ethylene oxide.

  Specific examples of the alkylene oxide addition type nonionic surfactant include oxyalkylene alkyl ethers (for example, octyl alcohol ethylene oxide addition product, lauryl alcohol ethylene oxide addition product, stearyl alcohol ethylene oxide addition product, oleyl alcohol ethylene oxide addition product). , Lauryl alcohol ethylene oxide propylene oxide block adduct, etc.); polyoxyalkylene higher fatty acid ester (eg, stearyl acid ethylene oxide adduct, lauric acid ethylene oxide adduct, etc.); polyoxyalkylene polyhydric alcohol higher fatty acid ester (For example, polyethylene glycol lauric acid diester, polyethylene glycol oleic acid diester, polyethylene glycol Polyoxyalkylene alkylphenyl ether (eg, nonylphenol ethylene oxide adduct, nonylphenol ethylene oxide propylene oxide block adduct, octylphenol ethylene oxide adduct, bisphenol A ethylene oxide adduct, dinonylphenol ethylene oxide addition) Polyoxyalkylene alkylamino ether and (for example, laurylamine ethylene oxide adduct, stearylamine ethylene oxide adduct, etc.); polyoxyalkylene alkyl alkanolamide (for example, Hydroxyethyl lauric acid amide ethylene oxide adduct, hydroxypropyl oleic acid Ethylene oxide adducts of bromide, ethylene oxide adducts of dihydroxy ethyl lauric acid amide, etc.) and the like.

  Examples of the polyhydric alcohol type nonionic surfactant include polyhydric alcohol fatty acid esters, polyhydric alcohol fatty acid ester alkylene oxide adducts, polyhydric alcohol alkyl ethers, and polyhydric alcohol alkyl ether alkylene oxide adducts.

  Specific examples of polyhydric alcohol fatty acid esters include pentaerythritol monolaurate, pentaerythritol monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan monolaurate, sorbitan dilaurate, sorbitan dioleate, sucrose monostearate, etc. Is mentioned. Specific examples of the polyhydric alcohol fatty acid ester alkylene oxide adduct include ethylene glycol monooleate ethylene oxide adduct, ethylene glycol monostearate ethylene oxide adduct, trimethylolpropane monostearate ethylene oxide propylene oxide random adduct, sorbitan mono Examples include laurate ethylene oxide adduct, sorbitan monostearate ethylene oxide adduct, sorbitan distearate ethylene oxide adduct, sorbitan dilaurate ethylene oxide propylene oxide random adduct, and the like. Specific examples of the polyhydric alcohol alkyl ether include pentaerythritol monobutyl ether, pentaerythritol monolauryl ether, sorbitan monomethyl ether, sorbitan monostearyl ether, methyl glycoside, lauryl glycoside and the like. Specific examples of polyhydric alcohol alkyl ether alkylene oxide adducts include sorbitan monostearyl ether ethylene oxide adduct, methylglycoside ethylene oxide propylene oxide random adduct, lauryl glycoside ethylene oxide adduct, stearyl glycoside ethylene oxide propylene oxide random adduct Etc.

  Examples of the water-soluble polymer (T) include cellulosic compounds (eg, methylcellulose, ethylcellulose, hydroxyethylcellulose, ethylhydroxyethylcellulose, carboxymethylcellulose, hydroxypropylcellulose, and saponified products thereof), gelatin, starch, dextrin, gum arabic, and chitin. , Chitosan, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine, polyacrylamide, acrylic acid (salt) -containing polymer (sodium polyacrylate, potassium polyacrylate, ammonium polyacrylate, in the sodium hydroxide part of polyacrylic acid) Sodium hydroxide, acrylic acid ester copolymer), styrene-maleic anhydride copolymer sodium hydroxide Beam (partial) neutralization product, water-soluble polyurethane (polyethylene glycol, reaction products of polycaprolactone diol with polyisocyanate and the like) and the like.

The solvent (U) used in the present invention is used for the purpose of imparting dispersion stability, and may be added to an aqueous medium as needed during emulsification dispersion. The solvent (U) needs to have a solubility in water of 1% by weight or more. Among the solvent (X) and the poor solvent (Y), those having a solubility in water of 1% by weight or more can be used as the solvent (U).
Specific examples include ester solvents such as ethyl acetate, butyl acetate, and methoxybutyl acetate; ether solvents such as tetrahydrofuran, dioxane, ethyl cellosolve, and butyl cellosolve; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. Alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and t-butanol; amide solvents such as dimethylformamide and dimethylacetamide; sulfoxide solvents such as dimethyl sulfoxide, N-methylpyrrolidone And the like, and a mixed solvent of two or more of these. Of these, preferred are ketone solvents, and more preferred are acetone and methyl ethyl ketone.

The total amount of the surfactant (S) and the water-soluble polymer (T) used is usually 0.1 to 5% with respect to the weight of the polymer (a) (hereinafter, unless otherwise specified,% represents% by weight). Preferably, it is 0.2 to 4%. Further, the dispersant is preferably 0.01 to 5%, more preferably 0.1 to 3% based on the weight of water. If it is 0.01 to 5%, resin fine particles having a preferable average particle diameter are easily obtained. Moreover, the usage-amount of the dispersing agent solution which consists of a dispersing agent and water with respect to the weight of a polymer (a) becomes like this. Preferably it is 50 to 1,000%, More preferably, it is 100 to 1,000%. If it is 50 to 1,000%, the dispersion state of the polymer (a) tends to be good, and resin fine particles having a preferable average particle diameter are easily obtained. If necessary, the polymer (a) may be heated to 40 to 60 ° C. in order to reduce the viscosity.
The amount of the solvent (U) added is preferably from 0.1 to 20%, more preferably from 0.5 to 5%, based on the weight of the polymer (a).

  As a method of dispersing (a) in water containing a dispersing agent in the methods (1) and (4), a known method such as a high-speed shearing method, a friction method, a high-pressure jet method, or an ultrasonic method is preferable. A disperser can be used. Of these, a more preferable method is a high-speed shearing method. When a high-speed shearing disperser is used, the number of rotations is preferably 1,000 to 30,000 rpm, more preferably 2,000 to 10,000 rpm. The dispersion time is preferably 0.1 to 5 minutes. If the rotation speed and dispersion time are within these ranges, resin fine particles having a preferable average particle diameter can be easily obtained.

The reaction time between the precursor and the extender in the method (1) is not particularly limited, and is appropriately selected according to the reactivity and reaction temperature. For example, when the reaction temperature is 30 ° C., it is usually 1 hour to 40 hours, preferably 5 hours to 20 hours.
In the manufacturing method of this invention, reaction temperature is 0-50 degreeC normally, Preferably it is 20-40 degreeC.

The dispersion is filtered or separated using a known equipment such as a filter press, a spatula filter, a centrifuge, and the resulting fine particles are dried to obtain the polymer fine particles (A) of the present invention.
The obtained fine particles can be dried using a known facility such as a circulating dryer, a spray dryer or a fluidized bed dryer.

  The number average particle size of the polymer fine particles (A) obtained by the above production method is preferably 0.1 μm or more, more preferably 0.5 μm or more, and preferably 60 μm or less from the viewpoint of conductivity. Preferably it is 20 micrometers or less.

  The particle shape of the polymer fine particles (A) of the present invention may be indefinite or spherical, but preferably contains 50% or more of spherical particles from the viewpoint of fluidity at room temperature. Here, the term “spherical” refers to particles having a major axis / minor axis ratio in the range of 1.0 to 1.5.

  The conductive fine particles (C) of the present invention can be obtained by preparing the polymer fine particles (A) and then coating the conductive metal (B) on the surface of (A).

As the conductive metal (B) in the present invention, a conductive metal can be used, for example, chromium, iron, copper, cobalt, nickel, zinc, tin, gold, silver, aluminum, and alloys of two or more thereof. Can be used.
Among these, nickel, copper, aluminum, silver, gold, and alloys thereof are preferable from the viewpoint of conductivity. Silver is more preferable from the viewpoint of oxidizing properties.

  The method for coating the polymer fine particles (A) with the conductive metal (B) is not particularly limited. For example, the method by electroless plating, the method by electroplating, the method for coating metal fine particles, vacuum deposition, ion plating, ion Examples of the method include sputtering. Of these, the electroless plating method is preferred.

  In the method of coating the metal fine particles, the number average particle diameter of the metal fine particles is preferably 1 nm or more, more preferably 10 nm or more, preferably 1000 nm or less, more preferably 100 nm or less, from the viewpoint of conductivity. It is.

  The process of forming a metal plating layer (conductive layer) by an electroless plating method is generally divided into an etching process, an activation process, and an electroless plating process, but the etching process is not necessarily required.

  The etching step is a step of forming irregularities on the surface of the polymer fine particles (A) to improve the adhesion of the metal plating layer (conductive layer). The etching solution used in the etching step is not particularly limited, and examples thereof include an alkaline aqueous solution such as a caustic soda aqueous solution and an acid aqueous solution such as an aqueous chromic acid solution. These etching liquids may be used independently and 2 or more types may be used together.

  The activation step is a step of activating the catalyst layer while forming a catalyst layer on the surface of the polymer fine particle (A) that has undergone the etching step or the surface of the polymer fine particle (A) that has not undergone the etching step. Activation of the catalyst layer promotes metal deposition in the electroless plating process. The catalyst used in the activation step is not particularly limited, and examples thereof include an alkali catalyst (alkali catalyst) such as a commercially available amine complex-based catalyst. These catalysts may be used independently and 2 or more types may be used together.

  The electroless plating step is a step of coating the surface of the polymer fine particles (A) on which the catalyst layer is formed with a conductive metal (B). The conductive metal (B) layer is formed on the surface of the polymer particles (A) by immersing the polymer particles (A) on which the catalyst layer is formed in an electroless metal plating solution.

For example, when an Ag plating layer is formed on the surface of resin fine particles, the catalyst layer of resin fine particles is reduced with a reducing agent such as dimethylaminoborane and then immersed in an electroless Ag plating solution, or a catalyst layer is formed. After immersing the polymer fine particles (A) in an electroless Ag plating solution, an Ag plating layer can be formed on the surface of the polymer fine particles (A) by adding and reducing a reducing agent.

  The average coating thickness of the conductive metal (B) layer in the conductive fine particles (C) is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 2 μm, still more preferably 0 from the viewpoint of specific gravity. .1 μm to 1 μm.

  The number average particle diameter of the conductive fine particles (C) by the light scattering method is preferably 0.1 μm or more, more preferably 0.5 μm or more, and preferably 60 μm or less from the viewpoint of conductivity. 20 μm or less.

  The particle shape of the conductive fine particles (C) of the present invention may be indefinite or spherical, but preferably contains 50% or more of spherical particles from the viewpoint of powder fluidity at room temperature. . Here, the term “spherical” refers to particles having a major axis / minor axis ratio in the range of 1.0 to 1.5.

  A conductive paste can be produced by dispersing the conductive fine particles (C) of the present invention in a binder (D). The conductive paste is used for an electromagnetic shielding material or a conductive adhesive.

As the binder (D), known thermosetting resins and thermoplastic resins can be used.
As a thermosetting resin, an epoxy resin, a phenol resin, a melamine resin, etc. are mentioned, for example.
Examples of the thermoplastic resin include polyolefin resins, acrylate resins, and polystyrene resins.
Examples of the polyolefin resin include polyethylene, ethylene-vinyl acetate copolymer, and ethylene- (meth) acrylic acid ester copolymer.
Examples of the acrylate resin include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate.
Examples of polystyrene resins include polystyrene, styrene-acrylic acid ester copolymers, SB type styrene-butadiene block copolymers, styrene-isoprene block copolymers, and block polymers such as these water additives. .
Among these, from the viewpoint of adhesion to the conductive metal (B), a thermosetting resin is preferable, and an epoxy resin is particularly preferable.
Mw by GPC (measurement conditions: temperature 40 ° C., tetrahydrofuran solvent, polystyrene conversion) of (D) is usually 1,000 to 2,000,000, preferably 3,000 to 1,000,000.

  The usage-amount of electroconductive fine particles (C) is 50 to 150 weight% based on a binder (D) weight, Preferably it is 80 to 120 weight% from a conductive viewpoint.

In the conductive paste of the present invention, a solvent (H) can be used as necessary.
As (H), water, C4-C30 aliphatic hydrocarbon, C6-C18 aromatic hydrocarbon, C1-C18 alcohol, C3-C18 ketone, C3-C3 36 esters, ethers having 4 to 18 carbon atoms, halogenated hydrocarbons having 1 to 12 carbon atoms, and mixtures thereof.
Examples of the aliphatic hydrocarbon include hexane, octane, and paraffin oil.
Examples of the aromatic hydrocarbon include benzene, toluene and xylene.
Examples of the alcohol include methanol, isopropyl alcohol and butanol.
Examples of the ketone include acetone, methyl ethyl ketone, and isobutyl methyl ketone.
Examples of the ester include ethyl acetate, butyl acetate, and methyl propionate.
Examples of ethers include diethyl ether, dibutyl ether and tetrahydrofuran.
Examples of the halogenated hydrocarbon include chloroform, methylene dichloride, ethylene dichloride, and the like.
When (H) is used, the amount of (H) used is usually 0.1 to 100 parts by weight, preferably 10 to 80 parts by weight, based on 100 parts by weight of (C) and (D). Particularly preferred is 20 to 60 parts by weight.

In addition to (C), (D), and (H), other components can be added to the conductive paste as necessary.
Examples of other components include an antifoaming agent, a leveling agent, a viscosity modifier, a dispersant, and a stabilizer.
When other components are used, the amount of other components used is usually 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the total of (C) and (D). Particularly preferred is 1 to 10 parts by weight.

The conductive paste can be obtained by uniformly mixing and dispersing the conductive fine particles (C) and the binder (D).
For uniform mixing / dispersing, for example, a three-roll, bead mill, disper mill, high-pressure homogenizer, kneader or planetary mixer can be used. The mixing / dispersing temperature is usually 5 to 100 ° C., and the mixing / dispersing time is usually 5 minutes to 10 hours.

  The specific gravity of the conductive fine particles (C) is preferably 1 to 3, more preferably 1 to 2, particularly preferably 1 to 1.5 from the viewpoint of dispersibility. The specific gravity of silver generally used as conductive particles is usually 10-11.

    In the conductive fine particles of the present invention, fine particles (A) made of a polymer (a) having a glass transition temperature of 100 ° C. or higher and 300 ° C. or lower are coated with a conductive metal (B), thereby reducing the amount of expensive silver used. Therefore, it has the feature of being excellent in dispersibility in resin by reducing the cost and reducing the specific gravity. The polymer (a) has a feature that Tg is as high as 100 ° C. or more and 300 ° C. or less and excellent in heat resistance.

  From this characteristic, the conductive paste in which the conductive fine particles (C) of the present invention are dispersed in the binder (D) is useful as an electromagnetic shielding material, a conductive adhesive, or the like.

As a method for applying the conductive paste of the present invention to a housing or the like, it can be applied by screen printing or a dispenser.
In any case, the film thickness is a dry thickness, usually 5 to 300 μm, preferably 10 to 200 μm, particularly preferably 20 to 100 μm.
The conductive paste of the present invention can be used when electromagnetic shielding is applied to a housing of a personal computer, a housing of a mobile phone, a building wall of a medical facility, or the like.

Examples Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto. In the following, parts and% indicate parts by weight and% by weight, respectively.

Tg, number average particle diameter, specific gravity and metal layer average coating thickness were measured by the following methods.
<Tg> The Tg of the polymer (A) was measured by heating at 180 ° C. for 10 hours to completely evaporate the solvent, and then using a differential scanning calorimeter UV-DSC220C (manufactured by Seiko Co., Ltd.). It was.
<Number average particle diameter> The number average particle diameter was measured with a laser scattering particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.) using toluene as a solvent.
<Specific gravity> Specific gravity was measured using the Le Chatelier specific gravity bottle method (JISR5201).
<Metal layer average coating film thickness> Conductive fine particles 0.5g was precisely weighed and dissolved in 10ml of 30% nitric acid aqueous solution. The silver content WAg was measured with 0.01 MEDTA standard solution using -PAN as an indicator, and the silver plating layer thickness was calculated by the following formula.
Silver plating layer thickness (μm) = (ρ _P × W _Ag × D) / {6 × ρ _Ag × (100−W _Ag )}
ρ _P : Specific gravity of resin fine particles ρ _Ag : Specific gravity of silver W _Ag : Silver content (%) D: Number average particle diameter (μm) of resin fine particles

Example 1 <Production of Epoxy Fine Particle “A-1”>
In a reaction vessel equipped with a stir bar and a thermometer, 47 parts of a styrenated phenol polyethylene oxide adduct (Eleminol HB-12, Sanyo Chemical Industries) and bisphenol A diglycidyl ether (Epicoat 828, Yuka Shell) 232 The part was added and dissolved uniformly. Water was added dropwise to the reaction vessel with stirring. When 38 parts of water was added, the system emulsified milky white. Further, 224 parts of water was added dropwise to obtain an emulsion. This was heated to raise the temperature in the system to 70 ° C., and then a solution prepared by dissolving 20 parts of ethylenediamine in 446 parts of water was added dropwise over 2 hours while maintaining 70 ° C. After dropping, the reaction and aging were carried out at 70 ° C. for 5 hours and at 90 ° C. for 5 hours to obtain an aqueous epoxy resin dispersion. Then, the obtained resin dispersion was taken out of the water by filtration with a filter paper and dried with a circulating dryer at 40 ° C. to obtain epoxy fine particles (A-1) (number average particle size 0.7 μm, polymer Tg: 172.6 ° C).

<Production of silver-coated conductive epoxy fine particles “C-1”>
Etching was carried out by dispersing 10 g of the obtained epoxy fine particles (A-1) in a pre-dip solution for powder plating (Okuno Pharmaceutical Co., Ltd.) and stirring at 30 ° C. for 30 minutes. After washing with water, it was added to 100 ml of a Pd catalyst containing 1% by weight of palladium sulfate and stirred at 30 ° C. for 30 minutes to adsorb palladium ions to the particles. The particles were collected by filtration, washed with water, and then added to a 0.5% by weight dimethylamine borane solution (adjusted to pH 6.0) to obtain polymer fine particles in which Pd was activated.
Distilled water (500 ml) was added to the obtained Pd-activated resin fine particles, and sufficiently dispersed using an ultrasonic processor to obtain a fine particle suspension. While stirring this suspension at 50 ° C., an electroless plating solution (pH adjusted to 7.5) consisting of 50 g / L of silver sulfate, 40 g / L of sodium hypophosphite, and 50 g / L of citric acid is gradually added. It was added and electroless silver plating was performed. When the metal coating layer became approximately 0.10 μm, the addition of the electroless plating solution was stopped, alcohol substitution was performed, and then vacuum drying was performed to obtain silver-coated conductive epoxy fine particles (C-1) (Ag plating layer) (Thickness: 0.24 μm, specific gravity: 1.56, number average particle size 1.1 μm).

Example 2 <Production of polyamide fine particles “A-2”>
100 parts of isophthalic acid chloride, 80 parts of hexamethylene diamine, 15 parts of diethylenetriamine and 120 parts of MEK are added and dissolved to obtain an oil phase. 10 parts of emulsifier (Calibon B (Sanyo Chemicals)) is dissolved in 800 parts of ion-exchanged water, and this is used as an aqueous phase. The aqueous phase and the oil phase are mixed and dispersed under the condition of 4000 rpm × 1 minute using a homomixer. The volume average particle diameter of the oil droplets was 20 μm. This dispersion is reacted at 60 ° C. for 10 hours. After completion of the reaction, the obtained spherical resin was taken out of the water by filtration with a filter paper and dried by a circulating dryer at 40 ° C. to obtain 280 parts of polyamide fine particles (A-2) (number average particle size 1 0.7 μm, polymer Tg: 154.6 ° C.).

<Manufacture of silver-coated conductive polyamide fine particles “C-2”>
Silver-coated conductive polyamide fine particles (C-2) were obtained by the same operation as in Example 1 except that the polyamide fine particles (A-2) were used (Ag plating layer thickness: 0.19 μm, specific gravity: 1.45, number Average particle size 1.9 μm).

Example 3 <Production of polyurethane fine particles “A-3”>
1,000 parts of toluene is added to 650 parts of polyethylene terephthalate (number average molecular weight 2,000, acid value 0.2), 142 parts of diphenylmethane diisocyanate is added, and the mixture is refluxed with toluene at 120 ° C. for 5 hours. After the reaction (isocyanate group content 3.2%), the mixture was cooled to room temperature, 25 parts of ethylenediamine and 20 parts of diethylenetriamine were added, and the reaction was carried out at 60 ° C. for 5 hours. To obtain a polyurethane resin having hydroxyl groups at both ends and having urethane and urea bonds. 400 parts of the obtained resin, 12 parts of yellow iron oxide, and 380 parts of ethyl acetate were mixed and dispersed while being added dropwise to 2000 parts of a previously prepared 0.5% aqueous polyvinyl alcohol solution. The obtained resin was taken out of the water by filtration with filter paper and dried with a circulating dryer at 40 ° C. to obtain polyurethane fine particles (A-3) (volume average particle size 1.5 μm, polymer Tg: 153.6). ° C).

<Production of silver-coated conductive polyurethane fine particles “C-3”>
Silver-coated conductive polyurethane fine particles (C-3) were obtained by the same operation as in Example 1 except that the polyurethane fine particles (A-3) were used (Ag plating layer thickness: 0.16 μm, specific gravity: 1.48, number (Average particle size 1.7 μm).

Example 4 <Production of polyester fine particle “A-4”>
To 450 parts of bisphenol A ethylene oxide (EO) 2 mol adduct (BPE-20T manufactured by Sanyo Kasei Kogyo Co., Ltd.), 242 parts of terephthalic acid and 28 parts of trimellitic anhydride are added, and 3 parts of dibutyltin oxide is added as a catalyst. The reaction was carried out at 230 ° C. for 10 hours (acid value 0.5, number average molecular weight 5000). This was taken out into a vat at 150 ° C. and cooled to room temperature to obtain a polyester resin. 400 parts of the obtained resin and 380 parts of ethyl acetate are mixed to form an oil phase. 20 parts of an emulsifier (Calibon B (manufactured by Sanyo Chemical Industries)) is dissolved in 800 parts of ion-exchanged water to obtain an aqueous phase. While the aqueous phase was stirred at 8,000 rpm with a TK homomixer, the oil phase was added and stirred for 3 minutes. Next, this mixed liquid was transferred to a reaction vessel equipped with a stir bar and a thermometer, and the temperature was raised to distill off ethyl acetate. The resulting resin dispersion was removed from the water by filtration with a filter paper, and a circulating dryer at 40 ° C. To obtain polyester fine particles (A-4) (volume average particle size 2.3 μm, polymer Tg: 156.6 ° C.).
<Production of silver-coated conductive polyester fine particles “C-4”>
Silver-coated conductive polyester fine particles (C-4) were obtained by the same procedure as in Example 1 except that the polyester fine particles (A-4) were used (Ag plating layer thickness: 0.16 μm, specific gravity: 1.48, number Average particle size 2.5 μm).

Comparative Example 1 <Production of polyacrylic fine particle “A′-1”>
(1) Adjustment of aqueous phase To 340 parts by weight of ion-exchanged water, 25 parts by weight of a 20% by weight aqueous solution of colloidal silica and 10 parts by weight of a 10% by weight aqueous solution of polystyrenesulfonic acid are uniformly mixed to obtain an aqueous phase.
(2) Preparation of oil phase 20 parts by weight of methacrylic acid, 0.8 parts by weight of hydroxyethyl methacrylate, 1.5 parts by weight of ethylene glycol dimethacrylate, 80 parts by weight of methyl methacrylate, 0.5 parts by weight of azobisisobutyronitrile Are mixed and dissolved uniformly to form an oil phase.
(3) Preparation of suspension and suspension polymerization The adjusted aqueous phase and oil phase are mixed and stirred at 16000 rpm for 1 minute with a homomixer to obtain an oil phase / water phase suspension. This suspension was charged into a three-necked flask and polymerized at 60 ° C. for 20 hours.
(4) The obtained resin dispersion was taken out from the water by filtration with a filter paper and dried with a circulating dryer at 40 ° C. to obtain polyacrylic fine particles (A′-1) (volume average particle diameter 3.6 μm). , Polymer Tg: 78.8 ° C.).
<Manufacture of polyacrylic fine particles "C'-1">
Silver-coated conductive polyester fine particles (C′-1) were obtained by the same operation as in Example 1 except that the polyacrylic fine particles (A′-1) were used (Ag plating layer thickness: 0.18 μm, specific gravity: 1. 44, number average particle size 3.8 μm).

Comparative Example 2 <Production of polyacrylic fine particles “A′-2”>
(1) Adjustment of aqueous phase To 340 parts by weight of ion-exchanged water, 25 parts by weight of a 20% by weight aqueous solution of colloidal silica and 10 parts by weight of a 10% by weight aqueous solution of polystyrenesulfonic acid are uniformly mixed to obtain an aqueous phase.
(2) Preparation of oil phase 80 parts by weight of methacrylic acid, 0.8 parts by weight of hydroxyethyl methacrylate, 1.5 parts by weight of ethylene glycol dimethacrylate, 20 parts by weight of methyl methacrylate, 0.5 parts by weight of azobisisobutyronitrile Are mixed and dissolved uniformly to form an oil phase.
(3) Preparation of suspension and suspension polymerization The adjusted aqueous phase and oil phase are mixed and stirred at 16000 rpm for 1 minute with a homomixer to obtain an oil phase / water phase suspension. This suspension was charged into a three-necked flask and polymerized at 60 ° C. for 20 hours.
(4) The obtained resin dispersion was taken out of the water by filter paper filtration and dried with a circulating dryer at 40 ° C. to obtain polyacrylic fine particles (A′-2) (volume average particle size 3.5 μm). , Polymer Tg: 127.8 ° C.).
<Manufacture of polyacrylic fine particles "C'-2">
Silver-coated conductive polyacrylic fine particles (C′-2) were obtained by the same operation as in Example 1 except that the polyacrylic fine particles (A′-2) were used (Ag plating layer thickness: 0.19 μm, specific gravity: 1). .44, number average particle size 3.7 μm).

Comparative Example 3 <Production of polyurethane fine particles “A′-3”>
1,000 parts of toluene is added to 650 parts of polyethylene terephthalate (number average molecular weight 2,000, acid value 0.2), 142 parts of hexamethylene diisocyanate is further added, and 5% at 120 ° C. under toluene reflux. After carrying out the reaction for a period of time (isocyanate group content 3.2%), the mixture was cooled to room temperature, 25 parts of hexamethylenediamine and 20 parts of diethylenetriamine were added, and the reaction was carried out at 60 ° C. for 5 hours. Distilled downward, a polyurethane resin having hydroxyl groups at both ends and having urethane and urea bonds was obtained. 400 parts of the obtained resin, 12 parts of yellow iron oxide, and 380 parts of ethyl acetate were mixed and dispersed while being added dropwise to 2000 parts of a previously prepared 0.5% aqueous polyvinyl alcohol solution. The obtained resin was taken out of the water by filtration with filter paper and dried with a circulating dryer at 40 ° C. to obtain polyurethane fine particles (A′-3) (volume average particle size 1.9 μm, polymer Tg: 83. 6 ° C).
<Production of silver-coated conductive polyurethane fine particles “C′-3”>
Silver-coated conductive polyurethane fine particles (C′-3) were obtained by the same operation as in Example 1 except that the polyurethane fine particles (A′-3) were used (Ag plating layer thickness: 0.16 μm, specific gravity: 1.48). , Number average particle size 2.2 μm).

Comparative Example 4 <Production of silver-coated conductive copper fine particles “C′-4”>
Silver-coated conductive copper fine particles (C′-4) were obtained by the same operation as in Example 1 except that atomized copper powder (A′-4: volume average particle size 3.9 μm) was used (Ag plating layer thickness: 0.16 μm, specific gravity: 7.9, number average particle size 4.2 μm).

  The conductive fine particles (C-1 to 4, C′-1 to 4) obtained above were evaluated for powder resistivity, heat resistance change ratio, and surface resistivity of the conductive paste coating film. The results are shown in Table 1.

<Powder resistivity (× 10 ⁻⁴ Ω · cm)>
A 20 g sample was compressed at a press pressure of 500 kgf and measured with a Loresta AP and Loresta PD-41 type (both manufactured by Mitsubishi Chemical).

<Heat resistance change ratio>
The sample was kept for 80 hours in a heating furnace at 156 ° C. in a heat-resistant air atmosphere. From the resistivity before the heat test and the resistivity after the heat test obtained by the powder resistivity measurement method, the resistance change magnification was obtained by the following formula, and the heat resistance of the conductivity was evaluated.
Heat resistance change ratio (times) = {Resistivity after heat resistance test (Ω · cm) / Resistivity before heat resistance test (Ω · cm)}

<Surface resistivity of conductive paste coating (× 10 ⁻² Ω · cm)>
Add 40 parts by weight of Acrylic 2000GL (manufactured by Kansai Paint Co., Ltd.), an acrylic lacquer, to 60 parts by weight of the sample, knead it with a homogenizer, apply this conductive paste on the film, and dry at 70 ° C. for 20 minutes. To form a conductive film. The surface resistivity of this coating film was measured by Loresta AP.

The conductive fine particles of the present invention have a small amount of silver used, can reduce costs, and are excellent in dispersibility in resins by reducing specific gravity. The resin used has a high Tg and is excellent in heat resistance. From these characteristics, it is useful as an electromagnetic shielding material or a conductive adhesive when used as a conductive paste.

Claims (11)

A polymer fine particle (A) having a glass transition temperature of 100 ° C. or more and 300 ° C. or less and comprising at least one polymer (a) selected from the group consisting of polyurethane resin, polyester resin, polyamide resin, and epoxy resin is electrically conductive. Conductive fine particles (C), characterized by being coated with a conductive metal (B). The conductive fine particles (C) according to claim 1, wherein the polymer (a) is a crosslinked polymer. The conductive fine particles (C) according to claim 1 or 2, wherein the polymer (a) is an epoxy resin. The conductive fine particles (C) according to any one of claims 1 to 3, wherein the conductive metal (B) is silver. The conductive fine particles (C) according to any one of claims 1 to 4, wherein an average coating film thickness of the conductive metal (B) is 0.01 µm or more and 10 µm or less. The conductive fine particles (C) according to any one of claims 1 to 5, having a number average particle size of 0.1 µm or more and 60 µm or less. The conductive fine particles (C) according to any one of claims 1 to 6, having a specific gravity of 1 or more and 3 or less. The conductive fine particles (C) according to any one of claims 1 to 7, wherein the polymer fine particles (A) are coated with a conductive metal (B) by an electroless plating method. The electroconductive paste which consists of electroconductive fine particles (C) and binder (D) in any one of Claims 1-8. An electronic device using the conductive paste according to claim 9. Surface of polymer fine particles (A) having a glass transition temperature of 100 ° C. or more and 300 ° C. or less and comprising at least one polymer (a) selected from the group consisting of polyurethane resin, polyester resin, polyamide resin, and epoxy resin Is coated with a conductive metal (B) by an electroless plating method, a method for producing conductive fine particles (C).