JP2010195992A - Polymer fine particle, method for producing the same, and conductive fine particle and anisotropic conductive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polymer fine particles of which heat resistance and mechanical strength are excellent and the mechanical strength is less likely to degraded after experiencing thermal history, and to provide a method for producing the same, and conductive fine particles and an anisotropic conductive material obtained from the polymer fine particles. <P>SOLUTION: The polymer particles have a compression fracture strength index P, which is represented by formula (1): P=P1/P2, of 0.77 or more, and P2 is 2.9 (mN) or more. Wherein, P1 is compression fracture strength (mN) after 1-hour heat treatment at 200°C in the air, and P2 is compression fracture strength (mN) before the heat treatment. The method for producing the polymer fine particles includes the steps of: producing seed particles by polymerizing a monomer component; and allowing the seed particles to absorb a monomer composition obtained by mixing a vinyl monomer with at least one antioxidant selected from a primary antioxidant and a secondary antioxidant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to polymer fine particles. More specifically, the present invention relates to polymer fine particles that are excellent in heat resistance and mechanical strength, and that hardly deteriorate mechanical strength even after heat history, a method for producing the same, and the polymer fine particles. The present invention relates to conductive fine particles obtained.

  Polymer fine particles are used for the purpose of improving physical properties such as light diffusibility, blocking resistance, and slipperiness of resin molded products and for imparting further properties, and for spacers and electrical connection between minute parts of electronic devices. It is used as a base particle for conductive fine particles.

  In recent years, in order to improve productivity, molding is often performed at a high temperature, and polymer fine particles are decomposed by heating to change the color of the molded product, or when used as conductive fine particles, As a result of the decomposition, there is a problem that the distance between the elements cannot be kept constant or an electrical short circuit occurs. From this point of view, there is an increasing demand for polymer fine particles that are hardly decomposed by heating during molding and have improved heat resistance.

  For example, Patent Document 1 discloses a crosslinked spherical particle having a thermal decomposition start temperature increased to 280 ° C. or higher, Patent Document 2 includes acrylic crosslinked fine particle conductive particles having a thermal decomposition start temperature of 260 ° C. or higher, Patent Document 3 Discloses a methacrylate resin particle having a thermal decomposition starting temperature of 250 ° C. to 300 ° C., and Patent Document 4 discloses a conductive material in which a metal layer is provided on the surface of a base particle having a thermal decomposition starting temperature of 300 ° C. or higher. Fine particles have been disclosed.

JP-A-6-220290 JP 2003-171426 A Japanese Patent Laid-Open No. 11-12327 WO2002 / 013205 pamphlet

  As described above, many techniques for increasing the thermal decomposition start temperature of polymer fine particles have been proposed, but even if such polymer fine particles having high heat resistance are used, the temperature is lower than the thermal decomposition temperature of the polymer fine particles. In the molding process that employs the heating temperature, the polymer fine particles are decomposed, resulting in defects in the molded product, and it may be difficult to obtain conduction stability.

  The present invention has been made paying attention to the circumstances as described above, and the object thereof is a polymer fine particle that is excellent in heat resistance and mechanical strength and hardly deteriorates in mechanical strength even after thermal history, It is an object to provide a production method and conductive fine particles obtained from the polymer fine particles.

The polymer fine particles of the present invention that can solve the above-mentioned problems have a compression fracture strength index P represented by the following formula (1) of 0.77 or more and P2 of 2.9 (mN) or more. It has a gist at some point.
P = P1 / P2 (1)
P1: Compressive fracture strength (mN) after heat treatment in air at 200 ° C. for 1 hour
P2: Compressive fracture strength before heat treatment (mN)
The polymer fine particles of the present invention having the above-described configuration are those in which the decrease in compressive fracture strength is small even after heat treatment and the mechanical strength is hardly deteriorated.

  In the polymer fine particles of the present invention, T2 is higher than 280 ° C. and T2 / T1 is 0 when the thermal decomposition start temperature under a nitrogen stream is T1 and the thermal decomposition start temperature under an air stream is T2. .95 or more is preferable.

  Furthermore, the polymer fine particles of the present invention preferably contain at least one kind of antioxidant selected from primary antioxidants and secondary antioxidants, and / or components derived from antioxidants. In addition, it is desirable that the component derived from the styrene monomer contains 0.5% by mass or more in the constituent component of the fine polymer particles. In addition, the polymer fine particles of the present invention preferably have a number average particle size of 0.5 μm to 100 μm and a coefficient of variation of the particle size of 20% or less.

  The present invention also includes a method for producing the polymer fine particles. The production method is a production method of the polymer fine particles described above, a step of producing seed particles by polymerizing monomer components, a vinyl monomer, a primary antioxidant and a secondary antioxidant selected from And a step of allowing the seed particles to absorb a monomer composition mixed with at least one kind of antioxidant.

  In addition, conductive fine particles having a metal coating layer on the surface of the polymer fine particles are also included in the present invention, and the metal coating layer is preferably a layer formed by an electroless plating method. Furthermore, the conductive fine particles of the present invention are suitably used for solder reflow processing.

  An anisotropic conductive material using the conductive fine particles is also a preferred embodiment of the present invention.

  According to the present invention, polymer fine particles that are excellent in heat resistance and mechanical strength and hardly deteriorate in mechanical strength even after heat treatment, and conductive fine particles obtained from the polymer fine particles are obtained.

[Polymer fine particles]
The polymer fine particles of the present invention are characterized in that the compressive fracture strength index P represented by the following formula (1) is 0.77 or more and P2 is 2.9 (mN) or more. It is.
P = P1 / P2 (1)
P1: Compressive fracture strength (mN) of polymer fine particles after heat treatment at 200 ° C. for 1 hour in air
P2: Compressive fracture strength (mN) of polymer fine particles before heat treatment

  The compression fracture strength index P refers to the compression fracture strength P1 (mN) after heat treatment in air at 200 ° C. for 1 hour and the compression fracture strength P2 (mN) of the polymer fine particles before the heat treatment expressed by the above formula (1 ) Is a value calculated by substituting) and serves as an index indicating the degree of decrease in mechanical strength of the polymer fine particles after heat treatment in air. That is, the larger the value of the compressive fracture strength index P, the smaller the decrease in mechanical strength after the polymer fine particle heat treatment. On the other hand, when the compressive fracture strength index P is small, it means that the mechanical strength of the polymer fine particles after the heat treatment is greatly decreased. In such a case, the polymer is reached before reaching the thermal decomposition start temperature. Cutting (decomposition) is likely to occur in the particle skeleton of the fine particles. Therefore, when the polymer fine particles having a small P value are used as the base particles of the conductive fine particles, the conduction reliability after receiving a heat history such as electrical joining or solder reflow is significantly reduced. There is a risk of causing defects in the molded product. The compression fracture strength index P is preferably 0.83 or more, more preferably 0.87 or more.

  The compressive fracture strength P2 before heat treatment of the polymer fine particles of the present invention is preferably 2.9 mN or more. More preferably, it is 3.9 mN or more, More preferably, it is 4.9 mN or more, Most preferably, it is 9.8 mN or more. If P2 is too small, the mechanical strength of the particles is of course too low, and the mechanical strength of the particles is further reduced by heating during processing. Particles are destroyed by a heavy load, and the conduction reliability is lowered. The compressive fracture strength is a load (mN) when the compression is increased and the fracture is reached, and is a value measured by the method described in Examples below.

  The polymer fine particles of the present invention have a T2 higher than 280 ° C. (not including 280 ° C.) when the thermal decomposition starting temperature under a nitrogen stream is T1, and the thermal decomposition starting temperature under an air stream is T2, and T2 / T1 is preferably 0.95 or more. T2 / T1 is 1 or less.

  Thermal decomposition of polymer fine particles is more likely to occur under an air stream than under a nitrogen stream. In particular, the polymer fine particles are decomposed at a lower temperature under an air stream. Here, T2 / T1 of 0.95 or more means that the polymer fine particles of the present invention have a thermal decomposition start temperature equivalent to that under a nitrogen stream even under an air stream, or a thermal decomposition start temperature under an air stream. And the difference of the thermal decomposition start temperature under nitrogen stream is small.

  More preferably, T2 / T1 is 0.96 or more, and further preferably 0.97 or more. T2 is more preferably 290 ° C. or higher, further preferably 300 ° C. or higher, and still more preferably 310 ° C. or higher. Polymer fine particles having a T2 lower than 280 ° C. and a T2 / T1 smaller than 0.95 are likely to undergo an oxidation reaction in the presence of oxygen. Therefore, even in a temperature range sufficiently lower than the thermal decomposition start temperature, the particle skeleton is oxidized. Degradation progresses. When such polymer fine particles are used as the base particles of conductive fine particles, there is a risk that the conduction reliability after receiving a thermal history such as electrical joining or solder reflow may be significantly reduced.

  In the present invention, as the thermal decomposition start temperature, a thermal analysis device (for example, “TG-DTA2000SA” manufactured by Bruker AXS, etc.) is used, and polymer fine particles are used under the conditions described in the examples described later. Based on the baseline of the TG curve obtained at this time, a value obtained by reading the temperature at which mass reduction starts is adopted as the thermal decomposition start temperature.

  The polymer fine particle of the present invention contains therein at least one kind of antioxidant selected from a primary antioxidant and a secondary antioxidant and / or a component derived from the antioxidant. Is preferred. This is because, when these antioxidants are contained in the polymer fine particles, the polymer fine particles can be prevented from being decomposed at a temperature lower than the thermal decomposition start temperature.

  As the primary antioxidant, a primary antioxidant having an ability to donate hydrogen radicals to peroxy radicals is effective. In the present invention, the “primary antioxidant having the ability to donate hydrogen radicals to peroxy radicals” is a compound having at least one hydrogen atom in the molecule that is rapidly extracted by peroxy radicals. Or the aromatic compound substituted by the secondary amino group is mentioned as a preferable thing. More preferred are phenol derivatives having an alkyl group at the ortho position, or diarylamine derivatives. When the nucleophilicity of an amine-based antioxidant such as polyarylate is a problem, a hindered phenol-based antioxidant may be used.

  Specific examples of the hindered phenol antioxidant include 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (trade name). : IRGANOX 1330), pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 1010), 2-t-butyl-6- (3- t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (trade name: Sumilizer GM), 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate (trade name: Sumilizer GS), N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) (commercial product) Name IRGANOX 1098), 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 259), 3,9-bis [2- [ 3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] 1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro [5.5] undecane (trade name: SumilizerGA -80), tris- (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate (trade name: IRGANOX 3114), isooctyl-3- (3,5-di-t-butyl-4-hydroxy) Phenyl) propionate (trade name: IRGANOX 1135), 4,4′-thiobis (6-t-butyl-3-methylphenol) (trade name: Sumilizer WX-R), 6- [3- (3-t-butyl) -4-hydroxy-5 -Methylphenyl) propoxy] -2,4,8,10-tetra-t-butyldibenz [d, f] [1,3,2] dioxaphosphine (trade name: Sumilizer GP) and the following (I -1) to (I-7).

  Examples of amine-based antioxidants include those represented by the following formulas (II-1) to (II-3).

  As the secondary antioxidant, a secondary antioxidant having a reducing action on peroxide is preferable. In the present invention, the “secondary antioxidant having a reducing action on peroxide” means a reducing agent capable of rapidly reducing peroxide to convert it into a hydroxyl group. As the secondary antioxidant having a reducing ability for peroxide, a sulfur-based antioxidant and a phosphorus-based antioxidant are preferable.

  As the sulfur-based antioxidant, those having an aromatic ring include thiodiethylene bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 4,6-bis (dodecylthiomethyl). -O-cresol, 4,6-bis (octylthiomethyl) -o-cresol (trade name: IRGANOX 1520), 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1 , 3,5-triazin-2-ylamino) phenol, 2-mercaptobenzimidazole (trade name: Sumilizer MB), 1,3,5-tris-β-stearylthiopropionyloxyethyl isocyanurate, 4,4′-thiobis (6-t-butyl-3-methylphenol) (trade name: Sumilizer WX-R) ", 4,6-bis (octylthiomethyl) -o-cresol (trade) Product name: IRGANOX 1520) and compounds represented by the following chemical formula (III-1).

  Further, the compound (IV) having a structural unit represented by the following chemical formula (1) can also be preferably used as the sulfur-based antioxidant according to the present invention.

In the chemical formula (1), n means an integer of 1 to 5 (preferably n = 2).

  Among the compounds (IV), compounds having two or more structural units represented by the chemical formula (1) in the molecule are preferable. More preferably, it is a compound having 2 to 4 structural units represented by the chemical formula (1) in the molecule, and particularly preferred is a structure having 4 structural units represented by the chemical formula (1) in the molecule. It is a compound that has.

  More specifically, among the compounds (IV), the compound (V) having a structural unit represented by the following chemical formula (2) is preferable. The compound (V) is more preferably a compound having 2 to 4 structural units represented by the following chemical formula (2) in the molecule, and more preferably 4 structural units represented by the following chemical formula (2). It is a compound that has.

Here, n is an integer of 1 to 5 (preferably n = 2), R ¹ is at least one group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and an alkenyl group, and R ¹ May have a substituent.

  The alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 3 to 20 carbon atoms, and still more preferably an alkyl group having 6 to 18 carbon atoms in terms of high heat resistance improvement effect. It is a group. Specific examples include alkyl groups such as propyl, butyl, pentyl, hexyl, octyl, dodecyl (lauryl), tridecyl, myristyl, and octadecyl (stearyl).

  Examples of the aryl group include a phenyl group, a hydroxyphenyl group, a tolyl group, and an o-xylyl group. Among these, a phenyl group and a hydroxyphenyl group are preferable.

  Examples of the aralkyl group include a benzyl group, a methylbenzyl group, a phenethyl group, a methylphenethyl group, a phenylbenzyl group, and a naphthylmethyl group. Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, a 1-butenyl group, Examples include 2-butenyl group. Among these, an alkyl group and an aryl group are preferable, and an alkyl group is particularly preferable.

Examples of the substituent that R ¹ has include a hydroxyl group, an amino group, a carboxyl group, an alkyl group, an aryl group, an aralkyl group, and an alkenyl group.

  Preferred examples of the compound (V) having four structural units represented by the chemical formula (2) include pentaerythrityl tetrakis (3-alkylthiopropionate). Specifically, pentaerythrityl tetrakis (3-methylthiopropionate), pentaerythrityl tetrakis (3-ethylthiopropionate), pentaerythrityl tetrakis (3-propylthiopropionate), pentaerythrityl tetrakis (3-butylthiopropionate), pentaerythrityltetrakis (3-hexylthiopropionate), pentaerythrityltetrakis (3-octylthiopropionate), pentaerythrityltetrakis (3-laurylthiopropionate) ) (Trade name: Sumilizer TP-D), pentaerythrityltetrakis (3-tridecylthiopropionate), pentaerythrityltetrakis (3-myristylthiopropionate), pentaerythrityltetrakis (3-stearylthiopropionate) One And pentaerythrityltetrakis (3-phenylthiopropionate). Among them, those having an alkyl group having 3 to 20 carbon atoms are preferable, more preferably a compound having 6 to 18 carbon atoms in the alkyl group, and particularly preferably a compound having 12 to 18 carbon atoms in the alkyl group.

  In particular, pentaerythrityltetrakis (3-laurylthiopropionate) having an alkyl group having 12 carbon atoms is preferred because it is easily available industrially.

  Among the compounds (IV), the compound (VI) having a structural unit represented by the following chemical formula (3) is also preferably used as the sulfur-based antioxidant according to the present invention.

In chemical formula (3), n is an integer of 1 to 5 (preferably n = 2).
Among the compounds (VI) having the structural unit represented by the chemical formula (3), a compound represented by the following chemical formula (4) is more preferable.

n is an integer of 1 to 5 (preferably n = 2).

In the chemical formula (4), R ² and R ³ are each independently at least one group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and an alkenyl group, and R ² and R ³ May have a substituent. In addition, as an alkyl group, an aryl group, an aralkyl group, and an alkenyl group, the thing similar to the case of R < ¹ > in the said compound (V) can be illustrated preferably. R ² and R ³ are preferably an alkyl group or an aryl group, and particularly preferably an alkyl group.

Examples of the substituent of R ² and R ³ include an alkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an amino group, and a carboxyl group.

  Preferred examples of the compound (VI) represented by the chemical formula (4) include dialkyl-3,3′-thiodipropionate. Specifically, dimethyl-3,3′-thiodipropionate, diethyl-3,3′-thiodipropionate, dipropyl-3,3′-thiodipropionate, dibutyl-3,3′-thiodiprote Pionate, dihexyl-3,3′-thiodipropionate, dioctyl-3,3′-thiodipropionate, didodecyl-3,3′-thiodipropionate (dilauryl-3,3′-thiodipropionate ) (Trade name: Sumilizer TPL-R, or trade name: IRGANOX PS 800FL), ditridecyl-3,3′-thiodipropionate (trade name: Sumilizer TL or trade name: Adeka Stab AO-503A), dimyristyl -3,3'-thiodipropionate (trade name: Sumilizer TPM), dihexadecyl-3,3'-thiodipropionate, dioctadecyl-3,3'-thiodipropionate Examples include onate (distearyl-3,3'-thiodipropionate) (trade name: IRGANOX PS 802FL or trade name: Sumilizer TPS). Among these, those having an alkyl group having 3 to 20 carbon atoms are preferable, compounds having 6 to 18 carbon atoms in the alkyl group are more preferable, and compounds having 12 to 18 carbon atoms in the alkyl group are more preferable.

  Particularly, didodecyl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, ditridecyl-3,3′-thiodipropionate, dioctadecyl having an alkyl group having 12 to 18 carbon atoms. -3,3'-thiodipropionate is preferred because it is easily available industrially.

  The phosphorus-based antioxidant is bis (2,4-di-t-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphite, 9,10-dihydro-9-oxa-10. -Phosphaphenanthrene-10-oxide (trade name: SANKOHCA), triethyl phosphite (trade name: JP302), tri-n-butyl phosphite (trade name: JP304), triphenyl phosphite (trade name: ADK STAB TPP) , Diphenyl monooctyl phosphite (trade name: Adeka Stub C), tri (p-cresyl) phosphite (trade name: Chelex-PC), diphenyl monodecyl phosphite (trade name: Adeka Stub 135A), diphenyl mono (tridecyl) phos Phyto (trade name: JPM313), Tris (2-ethylhexyl) phosphite (trade name: JP308), Phenyldidecylphosphine Ito (Adekastab 517), tridecyl phosphite (trade name: Adekastab 3010), tetraphenyldipropylene glycol diphosphite (trade name: JPP100), bis (2,4-di-t-butylphenyl) pentaerythritol diphos Phyto (trade name: ADK STAB PEP-24G), Tris (tridecyl) phosphite (trade name: JP333E), bis (nonylphenyl) pentaerythritol diphosphite (trade name: ADK STAB PEP-4C), bis (2,6- Di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (trade name: ADK STAB PEP-36), bis [2,4-di (1-phenylisopropyl) phenyl] pentaerythritol diphosphite (trade name: ADK STAB PEP-45), trilauryl trithiophosphite (trade name: JPS312) , Tris (2,4-di-t-butylphenyl) phosphite (trade name: IRGAFOS 168), tris (nonylphenyl) phosphite (trade name: ADK STAB 1178), distearyl pentaerythritol diphosphite (trade name: ADK STAB) PEP-8), tris (mono, dinonylphenyl) phosphite (trade name: ADK STAB 329K), trioleyl phosphite (trade name: Chelex-OL), tristearyl phosphite (trade name: JP318E), 4, 4 '-Butylidenebis (3-methyl-6-tert-butylphenylditridecyl) phosphite (trade name: JPH1200), tetra (C12-C15 mixed alkyl) -4,4'-isopropylidene diphenyl diphosphite (trade name: Adekastab 1500), tetra (tridecyl) -4,4'-butylidenebis (3-methyl-6-t-butyl) Enol) diphosphite (trade name: ADK STAB 260), hexa (tridecyl) -1,1,3-tris (2-methyl-5-tert-butyl-4-hydroxyphenyl) butane-triphosphite (trade name: ADK STAB 522A) Hydrogenated bisphenol A phosphite polymer (HBP), tetrakis (2,4-di-t-butylphenyloxy) -4,4'-biphenylene-di-phosphine (trade name: IRGAFOS P-EPQ), tetrakis (2 , 4-Di-t-butyl-5-methylphenyloxy) -4,4′-biphenylene-di-phosphine (trade name: GSY-101P), 2-[[2,4,8,10-tetrakis (1 , 1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphin-6-yl] oxy] -N, N-bis [2-[[2,4,8,10- Trakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphepin-6-yl] oxy] -ethyl] ethanamine (trade name: IRGAFOS 12), 2,2 ′ -Methylenebis (4,6-di-t-butylphenyl) octyl phosphite (trade name: ADK STAB HP-10), tris [2-[[2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphine-6-yl] oxy] ethyl] amine, bis [2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphorous Acid, tetrakis (2,4-di-tert-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite, and the following (VII-1) to (VII-12) Compounds The

  Among the secondary antioxidants, phosphorus-based antioxidants are preferable. This is because, when a sulfur-based antioxidant is used, a sulfur component is taken into the polymer fine particles, so that a sulfur-specific odor may be avoided.

  The above antioxidants may be used alone or in combination of two or more. Further, the primary antioxidant and the secondary antioxidant may be combined, and of course, only the primary antioxidant may be used in combination, or only the secondary antioxidant may be used in combination.

  The molecular weight (Mw) of the antioxidant is preferably 2000 or less, more preferably 1500 or less, and still more preferably 1300 or less. When the molecular weight of the antioxidant exceeds 2000, the solubility of the antioxidant in the polymerizable monomer that is the raw material of the polymer fine particles is lowered, and the antioxidant may not be easily taken into the polymer fine particles. is there. In addition, when the polymer fine particles of the present invention are produced by the seed polymerization method or the sol-gel seed polymerization method described later, the antioxidant is hardly absorbed into the seed particles, and as a result, the oxidation into the polymer fine particles is prevented. This is because the introduction of the agent may be insufficient.

  The antioxidant is preferably contained in 0.05% by mass to 5% by mass in the polymer fine particles of the present invention. More preferably, it is 0.1 mass%-4 mass%, More preferably, it is 0.5 mass%-3 mass%. When there are too few antioxidants, it may be difficult to ensure heat resistance and the mechanical strength after a heating. On the other hand, when the amount is too large, particularly when the seed polymerization method or the sol-gel seed polymerization method is employed, the antioxidant becomes difficult to be absorbed in the seed particles, and as a result, aggregation occurs between the particles in the polymerization reaction stage. May be easier to do. The cause is not clear, but in the reaction system, the antioxidant that is not absorbed in the particles is partly dissolved or dispersed in the polymer medium (aqueous medium). It is assumed that surfactants and dispersants that contribute to stabilization between particles at the stage are used for dissolution and dispersion of antioxidants, resulting in insufficient dispersion and stabilization of particles. . Although some antioxidants are consumed as radical scavengers during the synthesis of polymer fine particles, the polymer fine particles of the present invention are of the same level as those used in the production of polymer fine particles. The amount of antioxidant is preferably included.

  Moreover, it is preferable that the polymer fine particle of the present invention contains a component derived from a styrene monomer in an amount of 0.5% by mass or more in the constituent component of the polymer fine particle. This is because an effect of improving the heat resistance and an effect of suppressing the decrease in the compression fracture strength of the polymer fine particles after the heat treatment are expected. More preferably, it is 1 mass% or more. The amount of the component derived from the styrenic monomer in the polymer fine particle can be confirmed by GC-MS or the like, but in the present invention, substantially all of the monomer component used is contained in the polymer fine particle. Since it can be considered that it is taken in, the charging ratio (use mass%) of the styrene monomer to the total monomers used in the synthesis of the polymer fine particles is adopted as the amount of the component derived from the styrene monomer.

  The shape of the polymer fine particles of the present invention is not particularly limited, and may be any of, for example, a spherical shape, a spheroid shape, a confetti shape, a thin plate shape, a needle shape, and an eyebrows shape, and the particle surface shape is also smooth, wrinkled The shape may be either porous or porous. Among these, when used as conductive fine particles, a spherical shape is preferable in that a good surface contact state is formed when the particles are deformed between the electrodes.

  The size of the polymer fine particles is preferably 0.5 μm to 100 μm in number average particle diameter. This is because polymer fine particles exceeding 100 μm have limited applications when processed into conductive fine particles, and there are few industrial applications. The number average particle diameter is more preferably 1.0 μm to 30 μm, still more preferably 2.0 μm to 10 μm. When the number average particle diameter of the polymer fine particles is too small, the particles are likely to aggregate when coating the conductive metal layer such as electroless plating, and it may be difficult to form a uniform conductive metal layer. The number average particle diameter means a value obtained as the number average particle diameter in a conventionally known particle size distribution measuring method, and specifically, a precision particle size distribution measuring apparatus using the Coulter principle (for example, trade name “ It is a value measured by “Coulter Multisizer Type III” manufactured by Beckman Coulter, Inc.).

Further, the coefficient of variation (CV value) of the polymer fine particles of the present invention is preferably 20% or less, more preferably 10% or less, and even more preferably 7% or less. This is because the smaller the CV value, the smaller the particle size distribution. The CV value is a value obtained by applying the following formula to the number average particle diameter of polymer fine particles measured by a precision particle size distribution measuring apparatus using the Coulter principle and the standard deviation of the particle diameter of the polymer fine particles. is there.
Variation coefficient (%) of particle diameter of polymer fine particles = 100 × standard deviation of particle diameter / number average particle diameter

The mechanical properties of the polymer fine particles of the present invention can be evaluated by, for example, the compression elastic modulus, the compression deformation recovery rate, the above-described compression fracture strength, and the like. The compression elastic modulus in the present invention is an elastic modulus (N / mm ² : MPa) when a particle is loaded and deformed by 10%, and the recovery rate is a recovery rate (%) after compression. In any of the polymer particles and conductive fine particles also, the compression modulus is preferably 1000 N / mm ² or more, more preferably 2000N / mm ² or more, more preferably 3000N / mm ² or more, it is 30000 N / mm ² or less Is more preferably 25000 N / mm ² or less, and still more preferably 20000 N / mm ² or less. The compression deformation recovery rate is preferably 0.5% or more, more preferably 1.0% or more, further preferably 2.0% or more, preferably 95% or less, more preferably 90% or less. Yes, more preferably 85% or less.

[Polymer fine particles]
The polymer fine particles of the present invention may be either organic polymer fine particles made of only a vinyl polymer or organic-inorganic composite particles made of a material in which organic and inorganic materials are combined. The term “vinyl” used in the present invention includes (meth) acryloyl. Specific examples of the polymer fine particles include particles composed only of vinyl polymers such as (meth) acrylic (co) polymers, (meth) acrylic-styrene copolymers, and polymerizable (vinyl group). Meaning of inclusion; the same applies hereinafter) Examples include organic-inorganic composite particles such as alkoxysilane radical polymers and / or condensation polymers, and copolymers of polymerizable alkoxysilanes and vinyl monomers. In the following description, the term “vinyl polymer” means an organic-only polymer obtained by polymerizing vinyl monomers. In addition, the “vinyl polymer” as used in the present invention means that it contains a component or skeleton composed of “vinyl polymer”. The composition of the fine particles can be confirmed by GC-MS or the like.

  Although details of the method for producing the polymer fine particles of the present invention will be described later, emulsion polymerization, suspension polymerization, dispersion polymerization, seed polymerization, sol-gel seed polymerization method, etc. can be adopted, but seed polymerization or sol-gel seed polymerization method has a particle size distribution. Since it can be made small, it is preferable. Also, seed polymerization or sol-gel seed polymerization is preferable because the effect of suppressing the decrease in particle strength by the antioxidant is easily obtained. The sol-gel seed polymerization method is an embodiment of seed polymerization, and particularly means that seed particles are synthesized by the sol-gel method. For example, the case where polysiloxane obtained by the hydrolytic condensation reaction of alkoxysilane is used as seed particles can be mentioned. Therefore, the seed polymerization includes a case where the seed particles are made of an organic polymer and a case where the seed particles are made of a material in which an organic material and an inorganic material are combined (in the case of a sol-gel seed polymerization method).

[Organic polymer fine particles]
The organic polymer fine particles are obtained by polymerizing a monomer composition containing a monomer mixture containing a vinyl monomer. The vinyl monomer contained in the monomer mixture is a non-crosslinkable monomer having one vinyl group in one molecule, and a crosslinkable monomer having two or more vinyl groups in one molecule. Any of these can be used.

  Examples of the non-crosslinkable monomer include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, glycidyl (meth) acrylate, cyclohex (Meth) acrylates such as xyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2 (Meth) acrylic monomers such as hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylate; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p- Styrenic monomers such as methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, parahydroxystyrene; 2-hydroxyethyl vinyl ether, 4-hydroxy Examples include hydroxyl group-containing vinyl ethers such as butyl vinyl ether; hydroxyl group-containing allyl ethers such as 2-hydroxyethyl allyl ether and 4-hydroxybutyl allyl ether. In addition, when (meth) acrylic acid is used as the non-crosslinkable monomer, it may be partially neutralized with an alkali metal. The above-mentioned non-crosslinkable monomers may be used alone or in combination of two or more. Among these non-crosslinkable monomers, styrene is preferable in that it has a high heat resistance improving effect and a high suppression effect on the compression fracture strength of the polymer fine particles after the heat treatment.

  Examples of the crosslinkable monomer include trimethylolpropane triacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, decaethylene glycol dimethacrylate, pentadecaethylene glycol dimethacrylate, pentacontact ethylene glycol dimethacrylate. Multifunctional (meth) acrylates such as methacrylate, 1,3-butylene dimethacrylate, allyl methacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate; 1,4-butanediol di (meth) acrylate, 1,6-hexanediol Di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, polyethylene glycol di (meth) a Polyalkylene glycol di (meth) acrylates such as relate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate; aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and derivatives thereof; N, Cross-linking agents such as N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfonic acid; polybutadiene, polyisoprene unsaturated polyester, and the like. These crosslinkable monomers may be used alone or in combination of two or more. Among these crosslinkable monomers, divinylbenzene, which is a styrene monomer, is preferable in that it has a high heat resistance improvement effect and a high suppression effect on the compression fracture strength of the polymer fine particles after the heat treatment. The styrene monomer is preferably 0.5% by mass or more in the monomer mixture, more preferably 1% by mass or more, preferably 95% by mass or less, more preferably 90% by mass. % Or less.

  The content of the crosslinkable monomer in the monomer mixture is preferably 1% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more. By setting the content of the crosslinkable monomer in the monomer mixture to 1% by mass or more, the solvent resistance and heat resistance of the vinyl polymer fine particles are increased, and the mechanical properties can be appropriately controlled. .

  The polymerization of the monomer composition is preferably performed in the presence of at least one antioxidant selected from the primary antioxidants and secondary antioxidants described above. This is because the antioxidant can be present in the polymer fine particles. Therefore, the antioxidant is preferably one that dissolves in the monomer component or the polymerization solvent. The blending amount of the antioxidant is 0.05% by mass to 5% by mass when the total amount of the monomer components (including the monomer component used for seed particle synthesis in seed polymerization) is 100% by mass. It is preferable that it is 0.1 mass% to 4 mass%, more preferably 0.5 mass% to 3 mass%.

  Moreover, when polymerizing a monomer composition, you may use a polymerization initiator and a dispersion stabilizer as needed. As the polymerization initiator, any of those usually used for polymerization can be used. For example, a peroxide initiator, an azo initiator, or the like can be used. Examples of the peroxide initiator include hydrogen peroxide, peracetic acid, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide. Oxide, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, methyl ethyl ketone peroxide, diisopropyl Examples include peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, and the like.

  Examples of the azo initiator include dimethyl-2,2-azobisisobutyronitrile, azobiscyclohexacarbonitrile, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4- Dimethylvaleronitrile), 2,2′-azobis (2,3-dimethylbutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,3,3- Trimethylbutyronitrile), 2,2′-azobis (2-isopropylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (4-methoxy-2,4) -Dimethylvaleronitrile), 2- (carbamoylazo) isobutyronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 4,4'-azobis (4-cyano) Pentane acid), 4,4'-azobis (4-cyanovaleric acid), dimethyl-2,2'-azobis isobutyrate, and the like.

  These polymerization initiators may be used alone or in combination of two or more. The addition amount of these polymerization initiators is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and 5 parts by mass or less with respect to 100 parts by mass of the monomer mixture. And more preferably 3 parts by mass or less.

  The dispersion stabilizer is used to stabilize the droplets of the monomer composition before the polymerization reaction and to stabilize the generated particles in the polymerization reaction stage. As the dispersion stabilizer, any of an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant may be used. A dispersion stabilizer may be used independently and may use 2 or more types together. Among these, fatty acid oils such as sodium oleate and castor oil potassium; alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; polyoxyethylene distyryl phenyl ether sulfate ammonium salt, polyoxyethylene distyryl phenyl ether sulfate Polyoxyethylene distyryl phenyl ether sulfate such as sodium salt; alkylbenzene sulfonate such as sodium dodecylbenzene sulfonate; alkyl naphthalene sulfonate, alkane sulfonate, dialkyl sulfosuccinate, alkyl phosphate ester, naphthalene Anion such as sulfonic acid formalin condensate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl sulfate Emissions surfactants are preferred.

  The amount of the dispersion stabilizer used is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the total amount of monomer components (including the monomer component used for seed particle synthesis in seed polymerization). More preferably, it is 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less.

  In addition, pigments, plasticizers, polymerization stabilizers, fluorescent brighteners, magnetic powders, ultraviolet absorbers, antistatic agents, flame retardants, and the like may be added to the monomer composition. The amount of these additives used is preferably 0.01 parts by mass or more and preferably 10 parts by mass or less with respect to 100 parts by mass of the monomer mixture.

[Method for producing organic polymer fine particles]
The method for producing organic polymer fine particles is to polymerize a monomer composition containing the monomer mixture as described above. As the polymerization method, known polymerization methods such as suspension polymerization, seed polymerization, emulsion polymerization, and dispersion polymerization can be employed, and among these, suspension polymerization and seed polymerization are preferable. Polymer fine particles having a narrow distribution can be synthesized, and a decrease in particle strength due to an antioxidant can be effectively suppressed, which is preferable. The reason why the decrease in the particle strength is effectively suppressed is not clear, but probably the monomer composition in which the antioxidant is dissolved is absorbed by the seed particles, thereby It is presumed that the antioxidant is present uniformly without segregation.

  When the suspension polymerization method is employed, the solvent used is not particularly limited as long as it does not completely dissolve the monomer composition, but an aqueous medium is preferably used. These solvents can be suitably used within a range of usually 300 parts by mass or more and 10000 parts by mass or less with respect to 100 parts by mass of the monomer composition. As a method for producing organic polymer fine particles by suspension polymerization, a monomer mixture in which a polymerization initiator and an antioxidant are dissolved is suspended in an aqueous solvent in which the dispersion stabilizer is dissolved. A method of polymerizing is preferable.

  The polymerization temperature of the suspension polymerization is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, further preferably 60 ° C. or higher, preferably 95 ° C. or lower, more preferably 90 ° C. or lower, still more preferably. Is 85 ° C. or lower. The polymerization reaction time is preferably 1 hour or longer, more preferably 2 hours or longer, preferably 10 hours or shorter, more preferably 8 hours or shorter, still more preferably 5 hours or shorter. In order to control the particle diameter of the vinyl polymer to be produced, the polymerization reaction is preferably performed after regulating the droplet diameter of the monomer composition or while regulating the droplet diameter. The regulation of the droplet diameter of the monomer composition is, for example, that a suspension in which the monomer composition is dispersed in an aqueous medium is changed to T.P. K. It can be carried out by stirring with a high-speed stirrer such as a homomixer or a line mixer. And the organic polymer fine particles produced | generated by the polymerization reaction may be used for processes, such as drying and a classification as needed. In addition, it is preferable to perform drying at 150 degrees C or less, More preferably, it is 120 degrees C or less, More preferably, it is 100 degrees C or less.

  The seed polymerization is a method in which the monomer mixture is absorbed in the seed particles in the presence of the seed particles, the seed particles are expanded, and radical polymerization of the monomer mixture is performed in the seed particles. In the present invention, a step of synthesizing seed particles in the presence of an antioxidant, or a step of allowing the seed particles to absorb a monomer composition in which a vinyl monomer and an antioxidant are dissolved and dispersed. It is preferable to include. In order to effectively obtain the effect of suppressing the strength reduction of the polymer fine particles by the antioxidant, the seed particles absorb the monomer composition in which the above antioxidant is dissolved and dispersed in the vinyl monomer. It is recommended to adopt the process.

  In the case of employing the seed polymerization method, it is preferable to use a styrene-based or (meth) acrylate-based polymer as the seed particle, and it is more preferable to use a non-crosslinked type or a fine particle having a low degree of crosslinking. The number average particle size of the seed particles is preferably 0.1 μm to 10 μm, and the coefficient of variation of the particle size of the polymer fine particles is preferably 10% or less. Further, when synthesizing seed particles, a chain transfer agent may be used in order to obtain a preferable molecular weight and molecular weight distribution described later. As the chain transfer agent, an alkyl mercaptan chain transfer agent having 1 to 10 carbon atoms, α-methylstyrene dimer, or the like is preferably used. As a method for producing such seed particles, a conventionally used method can be employed, and examples thereof include soap-free emulsion polymerization and dispersion polymerization.

  The polymer constituting the seed particles preferably has a weight average molecular weight of 500 to 20,000 and a molecular weight distribution (Mw / Mn) of 2.5 or less. This is because if the weight average molecular weight or molecular weight distribution of the seed particles is out of the above range, the antioxidant may be hardly absorbed by the polymer fine particles. The molecular weight of the seed particles is measured by gel permeation chromatography (GPC) (reference material: polystyrene), and the weight average molecular weight and molecular weight distribution (Mw / Mn) may be calculated based on the obtained values.

  The obtained seed particles are subjected to a step of absorbing the monomer composition into the seed particles. At this time, the synthesized seed particles may be subjected to the subsequent absorption step as a seed particle dispersion in which the seed particles are dispersed in a solvent. Alternatively, the seed particles are synthesized, and the seed particles are separated from the reaction system. After the release, it may be dispersed again in the solvent for the absorption process and then used for the absorption process.

  The charged amount of the monomer composition in the seed polymerization is preferably 0.5 to 50 parts by mass with respect to 1 part by mass of the seed particles. If the charged amount of the monomer composition is too small, the increase in the particle size due to polymerization is small, and if it is too large, the monomer composition is not completely absorbed by the seed particles and polymerizes independently in the medium. May produce abnormal particles. Further, the blending amount of the antioxidant is 0.05% by mass to 5% by mass when the total amount of the monomer components (including the monomer component used for seed particle synthesis) is 100% by mass. Is preferred. More preferably, it is 0.1 mass%-4 mass%, More preferably, it is 0.5 mass%-3 mass%.

  Further, the molecular weight (Mw) of the antioxidant is preferably 2000 or less, more preferably 1500 or less, and still more preferably 1300 or less. When the molecular weight of the antioxidant exceeds 2000, the solubility of the antioxidant in the polymerizable monomer that is the raw material of the polymer fine particles is lowered, and the introduction of the antioxidant into the polymer fine particles becomes insufficient. In addition, when the polymerizable monomer is absorbed into the seed particles, the antioxidant may be difficult to be absorbed into the seed particles. In such a case, oxidation into the polymer fine particles may occur. This is because the introduction of the inhibitor may be insufficient.

  The absorption step is preferably performed in the temperature range of 0 ° C. to 60 ° C. with stirring for 5 minutes to 720 minutes. These conditions may be set as appropriate depending on the type of seed particles and monomers used, and these conditions may be used alone or in combination of two or more.

  In the absorption process, for determining whether the monomer composition is absorbed by the seed particles, for example, before adding the monomer composition and after completion of the absorption step, observe the particles with a microscope, It can be easily determined by confirming that the particle size is increased by absorption of the selenium.

  In addition, about the polymerization temperature and the drying conditions of the obtained particle | grains, the conditions similar to the said suspension polymerization are applicable.

[Organic-inorganic composite particles and method for producing the same]
Organic-inorganic composite particles are particles comprising an organic part derived from a vinyl polymer and an inorganic part. As an aspect of the organic-inorganic composite particles, an aspect in which inorganic fine particles such as metal oxides such as silica, alumina and titania, metal nitrides, metal sulfides and metal carbides are dispersed and contained in the vinyl polymer; Organo) A mode in which a metalloxane chain (a molecular chain containing a “metal-oxygen-metal” bond) such as polysiloxane and polytitanoxane is combined with an organic molecule at a molecular level; a vinyl polymer such as vinyltrimethoxysilane is formed. Particles obtained by hydrolyzing condensation reaction or vinyl group polymerization reaction of organoalkoxysilane having vinyl group to be obtained, and polysiloxane having vinyl group and polymerization property having silane compound having hydrolyzable silyl group as raw materials Organic-inorganic composite particles containing a vinyl polymer skeleton and a polysiloxane skeleton, such as particles obtained by reacting with a monomer or the like Embodiment consists, and the like. Among these, an embodiment composed of organic-inorganic composite particles containing a vinyl polymer skeleton and a polysiloxane skeleton obtained by seed polymerization, particularly, a sol-gel seed polymerization method is preferable.

  Hereinafter, organic-inorganic composite particles containing a vinyl polymer skeleton and a polysiloxane skeleton obtained by a sol-gel seed polymerization method will be described in detail.

  The vinyl polymer skeleton is a vinyl polymer having a main chain composed of a repeating unit represented by the following chemical formula (5), having a side chain, having a branched structure, and further having a crosslinked structure. It may be a thing. The hardness of the organic-inorganic composite particles can be controlled appropriately.

  The polysiloxane skeleton is defined as a portion in which a siloxane unit represented by the following chemical formula (6) is continuously chemically bonded to form a network of a network structure.

The amount of SiO ₂ constituting the polysiloxane skeleton is preferably 0.1% by mass or more, more preferably 1% by mass or more, and 80% by mass or less with respect to the mass of the organic-inorganic composite particles. Is more preferable, and 60% by mass or less is more preferable. When the amount of SiO ₂ in the polysiloxane skeleton is within the above range, the hardness of the organic-inorganic composite particles can be easily controlled. The amount of SiO ₂ constituting the polysiloxane skeleton is a mass percentage obtained by measuring the mass before and after firing the particles at a temperature of 800 ° C. or higher in an oxidizing atmosphere such as air.

  The organic-inorganic composite particles can be arbitrarily adjusted by appropriately changing the ratio of the polysiloxane skeleton portion or the vinyl polymer skeleton portion with respect to each of the mechanical properties such as hardness and breaking strength. The polysiloxane skeleton in the organic-inorganic composite particles is preferably obtained by hydrolytic condensation reaction of a silane compound having a hydrolyzable group.

Although it does not specifically limit as a silane compound which has hydrolyzability, For example, the silane compound represented by following Chemical formula (7), its derivative (s), etc. are mentioned.
R ' _m SiX _4-m (7)
(In the formula, R ′ may have a substituent and represents at least one group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group and an unsaturated aliphatic group, and X represents a hydroxyl group, an alkoxy group. And represents at least one group selected from the group consisting of a group and an acyloxy group, and m is an integer from 0 to 3.)

  Although it does not specifically limit as a silane compound represented by Chemical formula (7), For example, as m = 0, tetrafunctionality, such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, etc. Silanes; those with m = 1 include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, benzyltrimethoxysilane, Naphthyltrimethoxysilane, methyltriacetoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3- (meth) acryloxypropyl Trifunctional silanes such as limethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane; m = 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diacetoxydimethylsilane, diphenylsilanediol and the like. Examples of bifunctional silanes: m = 3 include monofunctional silanes such as trimethylmethoxysilane, trimethylethoxysilane, and trimethylsilanol.

  The derivative of the silane compound represented by the chemical formula (7) is not particularly limited. For example, a compound in which a part of X is substituted with a group capable of forming a chelate compound such as a carboxyl group and a β-dicarbonyl group. And a low condensate obtained by partially hydrolyzing the silane compound.

  The hydrolyzable silane compound may be used alone or in combination of two or more. In addition, in the chemical formula (7), when only the silane compound and its derivative with m = 3 are used as raw materials, organic-inorganic composite particles cannot be obtained.

  When the polysiloxane skeleton of the organic / inorganic composite particles has an organic silicon atom in which the silicon atom is directly bonded to at least one carbon atom in the vinyl polymer skeleton, the hydrolyzable silane As the compound, it is necessary to use a compound having an organic group containing a vinyl bond.

As an organic group containing a vinyl bond, the organic group etc. which are represented by following Chemical formula (8), (9) and (10) can be mentioned, for example.
^{_{CH 2 = C (-R a)}} -COOR b - (8)
(In the formula, R ^a represents a hydrogen atom or a methyl group, and R ^b represents a C 1-20 divalent organic group which may have a substituent.)
^{_{CH 2 = C (-R c)}} - (9)
(In the formula, R ^c represents a hydrogen atom or a methyl group.)
^{_{CH 2 = C (-R d)}} -R e - (10)
(In the formula, R ^d represents a hydrogen atom or a methyl group, and R ^e represents a C 1-20 divalent organic group which may have a substituent.)

  Examples of the organic group of the chemical formula (8) include a (meth) acryloxy group, and the silane compound of the general formula (7) having a (meth) acryloxy group includes, for example, γ-methacryloxypropyltrimethoxysilane. , Γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltriacetoxysilane, γ-methacryloxyethoxypropyltrimethoxysilane (or γ -Trimethoxysilylpropyl-β-methacryloxyethyl ether), γ- (methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropylmethyldimethoxysilane, etc. These may be used alone or in combination of two or more.

  Examples of the organic group of the chemical formula (9) include a vinyl group and an isopropenyl group. Examples of the silane compound of the chemical formula (7) having these organic groups include vinyltrimethoxysilane and vinyltrimethyl. Examples include ethoxysilane, vinyltriacetoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, and vinylmethyldiacetoxysilane. These may be used alone or in combination of two or more.

  Examples of the organic group of the chemical formula (10) include a 1-alkenyl group or vinylphenyl group, an isoalkenyl group or an isopropenylphenyl group, and the silane compound of the general formula (7) having these organic groups. As, for example, 1-hexenyltrimethoxysilane, 1-hexenyltriethoxysilane, 1-octenyltrimethoxysilane, 1-decenyltrimethoxysilane, γ-trimethoxysilylpropyl vinyl ether, ω-trimethoxysilylundecanoic acid Examples thereof include vinyl ester, p-trimethoxysilylstyrene, 1-hexenylmethyldimethoxysilane, 1-hexenylmethyldiethoxysilane and the like. These may be used alone or in combination of two or more.

  The vinyl polymer skeleton contained in the organic-inorganic composite particles is polymerized after the vinyl monomer component is absorbed into the particles (seed particles) having a polysiloxane skeleton obtained by hydrolysis condensation reaction of the silane compound. Can be obtained.

  The organic-inorganic composite particles are (i) a form (chemical bond) in which the polysiloxane skeleton has an organic silicon atom in which a silicon atom is directly chemically bonded to at least one carbon atom in the vinyl polymer skeleton. Type) or (ii) a form not having such an organosilicon atom in the molecule (IPN type), although not particularly limited, the form (i) is preferred. .

  Examples of the monomer that can be absorbed by the seed particles having a polysiloxane skeleton include the vinyl monomers described above, and can be appropriately selected according to the desired physical properties of the organic-inorganic composite particles. These may be used alone or in combination of two or more.

  For example, a hydrophobic vinyl-based monomer is preferable because a stable emulsion in which the monomer component is emulsified and dispersed can be formed when the monomer component is absorbed into particles having a polysiloxane skeleton. If the crosslinkable monomer is used, the mechanical properties of the resulting organic / inorganic composite particles can be easily adjusted, and the solvent resistance of the organic / inorganic composite particles can be improved. As the crosslinkable monomer, those exemplified as those used for the organic polymer fine particles can be used.

  The method for producing organic-inorganic composite particles preferably includes a hydrolysis-condensation step and a polymerization step. In the present invention, after the hydrolysis and condensation step, before the polymerization step, the polymerizable monomer and the antioxidant And an absorption step of absorbing a monomer composition comprising: By including the absorption step, the antioxidant can be incorporated into the organic-inorganic composite particles, and the content of the vinyl polymer skeleton component in the organic-inorganic composite particles can be adjusted.

  The hydrolysis-condensation step is a step of performing a reaction in which a silane compound is hydrolyzed in a solvent containing water to undergo condensation polymerization. By the hydrolysis condensation step, particles having a polysiloxane skeleton (polysiloxane particles) can be obtained. Hydrolysis and polycondensation can employ any method such as batch, split, and continuous. In the hydrolysis and condensation polymerization, basic catalysts such as ammonia, urea, ethanolamine, tetramethylammonium hydroxide, alkali metal hydroxide, and alkaline earth metal hydroxide can be preferably used as the catalyst.

  In the solvent containing water, an organic solvent can be contained in addition to water and the catalyst. Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol; acetone, Examples thereof include ketones such as methyl ethyl ketone; esters such as ethyl acetate; (cyclo) paraffins such as isooctane and cyclohexane; aromatic hydrocarbons such as benzene and toluene. These may be used alone or in combination of two or more.

  In the hydrolysis-condensation step, anionic, cationic and nonionic surfactants and polymer dispersants such as polyvinyl alcohol and polyvinylpyrrolidone can be used in combination. These may be used alone or in combination of two or more.

  Hydrolytic condensation is performed by mixing the silane compound as a raw material with a solvent containing a catalyst, water, and an organic solvent, and then at a temperature of 0 ° C. to 100 ° C., preferably 0 ° C. to 70 ° C., for 30 minutes to 100 hours. It can carry out by stirring below. Thereby, polysiloxane particles are obtained. Moreover, after producing a particle by performing a hydrolysis-condensation reaction to a desired degree, this may be used as a seed particle, and a silane compound may be further added to the reaction system to grow the seed particle.

  The absorption process is not particularly limited as long as it proceeds in the presence of the monomer composition in the presence of polysiloxane particles (seed particles). Therefore, the monomer composition may be added to the solvent in which the polysiloxane particles are dispersed, or the polysiloxane particles may be added to the solvent containing the monomer composition. Especially, like the former, it is preferable to add the monomer composition in a state where it is emulsified and dispersed in a solvent in which polysiloxane particles are dispersed in advance. Conventionally known emulsifiers can be used as the emulsifier used in the emulsification dispersion, and among these, anionic emulsifiers are preferably used. In addition, the method of adding the monomer component to the reaction liquid without taking out the polysiloxane particles obtained in the hydrolysis and condensation process from the reaction liquid (polysiloxane particle dispersion) does not complicate the process. It is preferable because of its excellent properties.

  In the absorption step, the monomer component and the antioxidant are absorbed in the structure of the polysiloxane particles. However, the polysiloxane particles and the single particles are absorbed so that the absorption of the monomer components and the antioxidant proceeds quickly. The concentration of each of the monomer components, the mixing ratio of the polysiloxane and the monomer component, the processing method and means for mixing, the temperature and time during mixing, the processing method and means after mixing, etc. are appropriately set, and the conditions are It is preferable to carry out with.

  Moreover, also about antioxidant, it is preferable to use the antioxidant which has the same molecular weight as the case of the organic polymer fine particle mentioned above from a viewpoint of improving the absorption efficiency to a polysiloxane particle (seed particle).

  The necessity of these conditions may be appropriately considered depending on the type of polysiloxane particles and monomer components used. Moreover, these conditions may apply only 1 type, or may apply 2 or more types together.

  The addition amount of the monomer component in the absorption step is preferably 0.5 to 50 parts by mass with respect to the mass of the silane compound used as the raw material for the polysiloxane particles. If the charged amount of the monomer composition is too small, the increase in particle diameter due to polymerization is small. On the other hand, if the charged amount is too large, the monomer composition is not completely absorbed by the seed particles and is polymerized uniquely in the medium. Then, there is a risk of generating abnormal particles. The amount of the antioxidant is 0.05% by mass to 5% by mass when the total amount of the monomer components (including the monomer component used for the synthesis of the seed particles) is 100% by mass. More preferably, it is 0.1 mass%-4 mass%, More preferably, it is 0.5 mass%-3 mass%.

  The reaction conditions (temperature, time) in the absorption step can be the same as those for the organic polymer fine particles. Moreover, what is necessary is just to confirm in the absorption process by the method similar to the case of organic polymer microparticles also about the judgment whether the monomer composition was absorbed by the polysiloxane particle.

  The polymerization step is a step of obtaining particles having a vinyl polymer skeleton by polymerizing a monomer component. Specifically, when a silane compound having an organic group having a vinyl bond is used, it is a step of polymerizing the vinyl bond of the organic group to form a vinyl polymer skeleton. Is a process of polymerizing the absorbed monomer component, or the absorbed monomer component and the vinyl bond of the polysiloxane skeleton to form a vinyl (system) polymer skeleton, if both fall under Can be a step of forming a vinyl (system) polymer skeleton by either reaction.

  The polymerization reaction may be performed in the middle of the hydrolysis-condensation step or the absorption step, and may be performed after one or both of the steps, and is not particularly limited, but usually after the hydrolysis-condensation step (the absorption step). If done, of course, start after the absorption step).

  The polymerization reaction is not particularly limited, and for example, any of a method using a radical polymerization initiator, a method of irradiating ultraviolet rays or radiation, a method of applying heat, and the like can be adopted. Although it does not specifically limit as said radical polymerization initiator, For example, what is used for superposition | polymerization of the said organic polymer fine particle can be mentioned. These radical polymerization initiators may be used alone or in combination of two or more.

  The amount of the radical polymerization initiator used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and still more preferably 0.001 part by mass with respect to 100 parts by mass of the total mass of the monomer components. It is 1 part by mass or more, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 5 parts by mass or less. When the usage-amount of a radical polymerization initiator is less than 0.001 mass part, the polymerization degree of a monomer component may not rise. The method of charging the radical polymerization initiator into the solvent is not particularly limited, and is a method in which the entire amount is initially charged (before the reaction is started) (the mode in which the radical polymerization initiator is emulsified and dispersed together with the monomer component, the monomer component is A mode in which a radical polymerization initiator is charged after absorption); a method in which a part is charged first, and the rest is continuously fed, or intermittently pulsed, or a combination of these, etc. Any known method can be employed.

  The reaction temperature at the time of performing radical polymerization is preferably 40 ° C or higher, more preferably 50 ° C or higher, preferably 100 ° C or lower, more preferably 80 ° C or lower. If the reaction temperature is too low, the degree of polymerization does not increase sufficiently, and the mechanical properties of the organic-inorganic composite particles tend to be insufficient. Aggregation tends to occur. In addition, what is necessary is just to change suitably the reaction time at the time of performing radical polymerization according to the kind of polymerization initiator to be used, Usually, 15 minutes-600 minutes are preferable, More preferably, they are 60 minutes-300 minutes. When the reaction time is too short, the degree of polymerization may not be sufficiently increased, and when the reaction time is too long, aggregation tends to occur between particles.

  According to the manufacturing method described above, vinyl polymer fine particles having the above-described preferable characteristics (such as mechanical characteristics and particle size distribution characteristics) can be obtained.

[Conductive fine particles]
The conductive fine particles of the present invention have a conductive metal layer that covers the surface of the polymer fine particles. Therefore, the conductive fine particles of the present invention have the characteristics of the polymer fine particles described above. The metal constituting the conductive metal layer is not particularly limited. For example, gold, silver, copper, platinum, iron, lead, aluminum, chromium, palladium, nickel, rhodium, ruthenium, antimony, bismuth, germanium, tin, Examples thereof include metals such as cobalt, indium, nickel-phosphorus, and nickel-boron, metal compounds, and alloys thereof. Among these, nickel, gold, silver, and copper are preferable because they are excellent in conductivity and industrially inexpensive.

  The conductive metal layer preferably has a thickness of 10 nm to 500 nm. More preferably, it is 20 nm-400 nm, More preferably, it is 50 nm-300 nm. When the thickness of the conductive metal layer is too thin, there is a tendency that it is difficult to maintain a stable electrical connection when the conductive fine particles are used as the anisotropic conductive material. On the other hand, when the conductive metal layer is too thick, the surface hardness of the conductive fine particles becomes too high, and there is a possibility that the mechanical properties of the base material particles such as the recovery rate cannot be fully utilized.

  In addition, it is preferable that a conductive metal layer does not have the surface where a substantial crack and a conductive metal layer are not formed in the surface. Here, “a surface on which a substantial crack or a conductive metal layer is not formed” means that the surface of any 10,000 conductive fine particles is observed using an electron microscope (1000 times magnification). It means that the crack of the metal layer and the exposure of the surface of the base material particle are not substantially visually observed. A detailed evaluation method will be described later.

  The conductive fine particles of the present invention may further have an insulating resin layer on the surface of the conductive metal layer. The insulating resin layer is not particularly limited as long as the insulating property between the particles of the conductive fine particles can be ensured, and the insulating resin layer can be easily collapsed or peeled off by a certain pressure and / or heating. For example, polyolefins such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer; polymethyl (meth) acrylate, polyethyl (meth) acrylate, in addition to resins similar to vinyl polymer fine particles described later (Meth) acrylate polymers and copolymers such as polybutyl (meth) acrylate; polystyrene, styrene-acrylate copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and Block polymers such as these hydrogenated compounds; Thermoplastic resins such as ethylene-based polymers and copolymers, and particularly crosslinked products thereof; Thermosetting resins such as epoxy resins, phenol resins, melamine resins; polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, polyethylene oxide, Examples thereof include water-soluble resins such as methyl cellulose and mixtures thereof.

  However, when the insulating resin layer is too hard as compared with the polymer fine particles, the polymer fine particles themselves may be destroyed before the insulating resin layer is destroyed. Therefore, it is preferable to use an uncrosslinked or relatively low degree of crosslinking resin for the insulating resin layer.

  The insulating resin layer may be a single layer or a plurality of layers. For example, a single or a plurality of film-like layers may be formed, or particles having insulating particles, spheres, lumps, scales, or other shapes attached to the surface of conductive fine particles, Furthermore, it may be formed by chemically modifying the surface of the conductive fine particles, or a combination of these.

  The thickness of the resin insulation layer is preferably 0.01 μm to 1 μm. More preferably, it is 0.1 micrometer-0.5 micrometer. If the thickness of the resin insulating layer is too thin, the electrical insulation is insufficient. On the other hand, if the thickness is too thick, the conduction characteristics may be deteriorated.

  The conductive fine particles of the present invention are also suitably used when a material incorporating conductive fine particles (for example, an anisotropic conductive material described later) undergoes solder reflow processing.

  Generally, an electronic component is mounted on a circuit board by combining soldering or an anisotropic conductive film (ACF) using conductive fine particles as a conductive material. When mounting components such as resistors and capacitors by soldering, mounting technology is used in which the components are placed on a circuit board printed with solder paste and then soldered by passing the circuit board through a reflow furnace. Yes. This mounting technology is usually called surface mounting technology. With the progress of miniaturization of components and high density mounting, this method has become mainstream in the production of circuit boards.

  In the surface mounting technology using the solder, first, prior to melting of the solder, the circuit board and the component are placed in a reflow furnace for the purpose of mitigating rapid thermal shock to the component, volatilization of the organic solvent, etc. Preheating (generally about 150 ° C. to 170 ° C.) is carried out in a process called preheating, followed by a high temperature treatment in a process called main heating for a short time to heat the solder and melt it (reflow process, In general, the entire circuit board may be heated to a high temperature, for example, about 260 ° C. in a reflow furnace. Therefore, if the circuit board is subjected to solder reflow processing after mounting using the ACF, the ACF is exposed to a high temperature during the solder reflow processing, resulting in a problem that connection reliability is lowered. However, since the conductive fine particles of the present invention are excellent in heat resistance and are difficult to cause a decrease in strength due to heating, a material incorporating the conductive fine particles (for example, an anisotropic conductive material described later), It is also suitably used when receiving solder reflow processing in which solder joining is performed in a lump in a horizontal conveyance type continuous furnace or the like.

[Method for producing conductive fine particles]
The conductive fine particles of the present invention can be obtained by forming a conductive metal layer on the surface of the polymer fine particles. The method for coating the surface of the polymer fine particles with the conductive metal layer is not particularly limited. For example, a method by plating such as electroless plating or displacement plating; a paste obtained by mixing metal fine powder alone or mixed with a binder as a base material Methods for coating particles: physical vapor deposition methods such as vacuum vapor deposition, ion plating, ion sputtering and the like. Among these, the electroless plating method is preferable because a conductive metal layer can be easily formed without requiring a large-scale apparatus.

  In the electroless plating method, first, a catalyst layer serving as a starting point for electroless plating is formed on the surface of the polymer fine particles ((i) catalytic step), and then a conductive metal is formed on the surface of the polymer fine particles on which the catalyst layer is formed. A layer is formed ((ii) electroless plating step). Hereinafter, each process will be described in detail.

[(I) Catalytic step]
In the catalyzing step, a catalyst layer serving as a base point of electroless plating performed in the next step is formed on the surface of the polymer fine particles. The method for forming the catalyst layer is not particularly limited, and may be performed using a catalytic reagent commercially available for electroless plating. For example, after immersing polymer fine particles in a solution containing palladium chloride and tin chloride as a catalyzing reagent to adsorb palladium ions on the surface of the polymer fine particles, an acid such as sulfuric acid and hydrochloric acid, sodium hydroxide, etc. A method of reducing the palladium ions with an alkaline solution to deposit palladium on the surface of the polymer fine particles; after immersing the polymer fine particles in a palladium sulfate solution and adsorbing the palladium ions on the surface of the polymer fine particles, dimethylamine borane, etc. And a method in which palladium ions are reduced with a solution containing a reducing agent to deposit palladium on the surface of the polymer fine particles.

  Examples of the catalyzing reagent include palladium chloride, palladium nitrate, tin chloride, and mixtures thereof. The catalytic reagent is used after being dissolved in hydrochloric acid or the like. Examples of the reducing agent include dimethylamine borane and hypophosphorous acid.

[(Ii) Electroless plating step]
Next, an electroless plating process for forming a conductive metal layer on the surface of the polymer fine particles on which the catalyst layer has been formed is performed. In this step, polymer fine particles having a catalyst layer formed therein are immersed in a plating solution in which a reducing agent and a desired metal salt are dissolved, and starting from the catalyst, metal ions in the plating solution are reduced with a reducing agent, A desired metal is deposited on the surface of the coalesced fine particles to form a conductive metal layer.

  First, the polymer fine particles subjected to the catalyst treatment are sufficiently dispersed in water to prepare an aqueous slurry of the polymer fine particles. Here, the polymer fine particles need to be sufficiently dispersed in an aqueous medium to be plated. When the electroless plating process is performed in a state in which the polymer fine particles are aggregated, an untreated surface (a surface on which no conductive metal layer is present) is formed on the contact surface between the polymer fine particles. This is because characteristics cannot be obtained. A known dispersing means may be used for dispersing the polymer fine particles. As a conventionally known dispersing means, normal stirring, high-speed stirring, or a shearing dispersion device such as a colloid mill or a homogenizer can be used. In addition, ultrasonic waves may be used in the dispersion operation, and a dispersant such as a surfactant may be added as necessary.

  Next, an aqueous slurry of polymer fine particles is added to an electroless plating solution containing a desired conductive metal salt, a reducing agent, a complexing agent and various additives, and an electroless plating treatment is performed.

  Examples of the conductive metal salt include metal chlorides, sulfates, and acetates exemplified above as the conductive metal layer. For example, if it is desired to form a nickel layer as the conductive metal layer, nickel salts such as nickel chloride, nickel sulfate, and nickel acetate can be used. What is necessary is just to determine suitably the density | concentration of the electroconductive metal salt in an electroless-plating liquid according to the size (surface area) of a base particle so that the electroconductive metal layer of a desired film thickness may be formed.

  As the reducing agent, sodium hypophosphite, dimethylamine borane, sodium borohydride, potassium borohydride, hydrazine and the like are used.

  As the complexing agent, a compound having a complexing action with respect to ions of the conductive metal to be used can be used. For example, compounds having a complexing action on nickel include citric acid, hydroxyacetic acid, tartaric acid, malic acid, lactic acid, gluconic acid or carboxylic acids (salts) such as alkali metal salts and ammonium salts thereof, and amino acids such as glycine. Amine acids such as ethylenediamine and alkylamine, other ammonium, EDTA, pyrophosphate (salt), and the like. These may be used individually by 1 type and may be used in combination of 2 or more type. The preferable pH of the electroless plating solution in the electroless plating treatment step is 4 to 14.

  The electroless plating reaction starts rapidly when the polymer fine particle slurry is added. Further, this reaction is accompanied by generation of hydrogen gas. Therefore, the electroless plating treatment process ends when the generation of hydrogen gas is not completely recognized. After completion of the reaction, the conductive fine particles on which the conductive metal layer is formed are taken out from the reaction system, and washed and dried as necessary.

  Although the conductive fine particles of the present invention are obtained as described above, the surface of the conductive fine particles can be coated with several layers of different metals by repeating the electroless plating treatment step. For example, after nickel plating is applied to the substrate particles (nickel-coated particles), the gold-coated plating is performed by introducing the nickel-coated particles into the electroless gold plating solution, so that the outermost layer has a gold coating layer. Conductive fine particles are obtained.

[(Iii) Other steps]
When the conductive fine particles of the present invention have an insulating resin layer, the surface of the conductive metal layer is subjected to insulation treatment with a resin or the like after the electroless plating step.

  The method for forming the insulating resin layer is not particularly limited, for example, in the presence of conductive fine particles after the electroless plating treatment, interfacial polymerization, suspension polymerization, emulsion polymerization of the raw material of the insulating resin layer is performed, A method of microencapsulating conductive fine particles with an insulating resin; a dipping method in which conductive fine particles are dispersed in an insulating resin solution in which an insulating resin is dissolved in an organic solvent and then dried; a spray drying method, by hybridization Any conventionally known method such as a method can be used.

[Anisotropic conductive material]
The conductive fine particles of the present invention are also suitable as a constituent material of the anisotropic conductive material. An anisotropic conductive material using the conductive fine particles of the present invention is also one of the preferred embodiments of the present invention. is there. The form of the anisotropic conductive material is not particularly limited as long as the conductive fine particles of the present invention are used. For example, an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive adhesive is used. And various forms such as anisotropic conductive ink. That is, electrical connection can be achieved by providing these anisotropic conductive materials between opposing substrates or between electrode terminals.

  The anisotropic conductive film, for example, after adding a solvent to the film-forming composition containing the conductive fine particles of the present invention and a binder resin to form a solution, and applying this solution on a polyethylene terephthalate film, It can be obtained by evaporating the solvent. The obtained anisotropic conductive film is disposed on, for example, electrodes, and is used for connection between the electrodes by superposing a counter electrode on the anisotropic conductive film and heating and compressing the counter electrode.

  The anisotropic conductive paste is obtained, for example, by making a resin composition containing the conductive fine particles of the present invention and a binder resin into a paste. The obtained anisotropic conductive paste is placed in, for example, a suitable dispenser, applied on the electrode to be connected with a desired thickness, and the counter electrode is superimposed on the coated anisotropic conductive paste. It is used for connection between electrodes by heating and pressurizing to cure the resin.

  The anisotropic conductive adhesive is obtained, for example, by adjusting a resin composition containing the conductive fine particles of the present invention and a binder resin to a desired viscosity. The obtained anisotropic conductive adhesive is used to connect between electrodes by coating the electrodes with a desired thickness, then overlaying the counter electrodes and bonding them together, as with the anisotropic conductive paste. Is done.

  The anisotropic conductive ink can be obtained, for example, by adjusting a viscosity suitable for printing by adding a solvent to the resin composition containing the conductive fine particles of the present invention and a binder resin. The obtained anisotropic conductive ink is obtained by, for example, screen-printing on the electrode to be bonded, evaporating the solvent, superimposing the counter electrode on the printing surface with the anisotropic conductive ink, and heating and compressing the electrode. Used for connection between.

  The anisotropic conductive material is produced by dispersing the conductive fine particles of the present invention in an insulating binder resin to obtain a desired form. Of course, the insulating binder resin and the conductive fine particles May be used separately to connect between substrates or between electrode terminals.

  The binder resin is not particularly limited, for example, thermoplastic resins such as acrylic resin, ethylene-vinyl acetate resin, styrene-butadiene block copolymer; monomers and oligomers having a glycidyl group, and curing agents such as isocyanate. Examples thereof include a curable resin composition that is cured by reaction and a curable resin composition that is cured by light and heat.

  The content ratio of the conductive fine particles in the anisotropic conductive material of the present invention may be appropriately determined according to the application. For example, the ratio of the conductive fine particles in the anisotropic conductive material is 2% by volume to 70% by volume is preferably used, more preferably 5% by volume to 50% by volume, and still more preferably 10% by volume to 40% by volume. If the content of the conductive fine particles is too small, it may be difficult to obtain sufficient electrical continuity. On the other hand, if the content of the conductive fine particles is too large, the conductive fine particles are in contact with each other, and anisotropy is caused. The function as a conductive material may be difficult to be exhibited.

  The film thickness of the anisotropic conductive material, the coating thickness of the paste and adhesive, and the printed thickness are calculated from the average particle diameter of the conductive fine particles used and the specifications of the electrode to be connected. It is preferable to set so that the conductive fine particles are sandwiched between the power electrodes and the gap between the bonding substrates on which the electrodes to be connected are formed is sufficiently filled with the binder resin layer.

  The anisotropic conductive material of the present invention not only exhibits high conductivity, but also does not cause peeling or breakage of the conductive metal layer even when subjected to weight compression, and ensures electrical connection between opposing electrode substrates. can do. In addition, since the stability over time is excellent, the electrical connection between the electrode substrates can be maintained and the reliability can be improved without causing a decrease in conductivity due to plating cracking or the like even in long-term use.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

[Average particle size, coefficient of variation of particle size (CV value)]
The average particle size of the particles was determined by measuring the particle size of 30000 particles using a Coulter Multisizer III type (manufactured by Beckman Coulter, Inc.) to determine the number average particle size. The CV value (coefficient of variation) of the particle diameter was determined according to the following formula.

[Compressive fracture load]
A circular plate indenter with a diameter of 50 μm per sample particle spread on a sample table (material: SKS flat plate) at room temperature (25 ° C.) by a Shimadzu micro-compression tester (manufactured by Shimadzu Corporation, “MCTW-500”) Using (material: diamond), a load was applied in the center direction of the particle at a constant load speed (2.275 mN / sec), and the load (mN) when the particle was broken by deformation was defined as a compressive breaking load.

  The compressive fracture load value before heat treatment is P2 (mN), and the compressive fracture load value after heat treatment at 200 ° C. for 1 hour in air is P1 (mN). , Manufactured by Bruker AXS) under a stream of air at a flow rate of 50 ml / min, heated to 200 ° C. at a rate of temperature increase of 10 ° C./min, and then held at 200 ° C. for 1 hour. It was.

[10% compression modulus (10% K value: hardness)]
In the same manner as the measurement of the compression fracture load value, a load is applied to the particles, and the load and the amount of displacement (mm) when the particles are deformed until the compression displacement becomes 10% of the particle diameter are measured. The measured compression load, particle compression displacement, and particle radius are expressed as follows:

(Where K: 10% compression modulus (N / mm ² ), F: compression load (N), S: compression displacement (mm), R: particle radius (mm)). Calculate the value. This operation was performed for three different particles, and the average value was defined as the 10% compression modulus (N / mm ² ) of the base particles.

[Compression deformation recovery rate (recovery rate)]
Using a micro-compression tester (manufactured by Shimadzu Corporation: “MCTW-500”), after compressing the sample particles to a reverse load of 9.8 mN, measure the relationship between the load value and the compression displacement when the load is reduced. Displacement to the point of reversal when measuring the end point when removing the load as the origin load value of 0.098 mN and the compression (recovery) speed at load and removal as 1.486 mN / sec. It is a value expressed as a ratio (L1 / L2) (%) between (L1) and the displacement (L2) from the reversal point to the point where the origin load value is taken.

[Pyrolysis start temperature]
The thermal decomposition start temperature of the polymer fine particles was measured using a thermal analyzer (“TG-DTA2000SA”, Bruker AXS) under the conditions of a sample amount of 10 mg to 20 mg and a temperature rising temperature of 10 ° C./min. T1 was measured under a flow of nitrogen at a flow rate of 50 ml / min, and T2 was measured under a flow of air at a flow rate of 50 ml / min.

  First, a sample is weighed in a specified aluminum cup, this aluminum cup is set at a predetermined position of the thermal analyzer, adjusted so that nitrogen or air flows at a specified flow rate (50 ml / min), and after the apparatus is stabilized, Heating started. Based on the baseline (horizontal line part) of the TG curve obtained at this time, the temperature at which mass reduction starts was read and used as the thermal decomposition start temperature (° C.) of the polymer fine particles.

Example 1
<Preparation of polymer fine particles>
Polyoxyethylene styrenated phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku, "Hitenol (registered trademark) NF-08") as a surfactant in a four-necked flask equipped with a condenser, thermometer, and dripping port 150 parts of aqueous solution of ion-exchanged water in which 2 parts were dissolved. Thereto, 50 parts of styrene prepared in advance and 50 parts of divinylbenzene 960 (manufactured by Nippon Steel Chemical Co., Ltd.) were added to Irganox (registered trademark) 1010 (pentaerythrityl-tetrakis [3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate], molecular weight: 1177.7, manufactured by Ciba Specialty Chemicals), and 2,2-azobis (2,4-dimethylvalero) as a polymerization initiator Nitrile (manufactured by Wako Pure Chemical Industries, Ltd.) 2 parts was charged, and emulsified and dispersed at 5000 rpm for 5 minutes using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a suspension. To this suspension, 250 parts of ion-exchanged water was added, the temperature was raised to 65 ° C. under a nitrogen atmosphere, and the mixture was held at 65 ° C. for 2 hours to perform radical polymerization of the monomer. After radical polymerization, the produced emulsion was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and then with methanol. Thereafter, classification was performed, and vacuum drying was performed at 40 ° C. for 2 hours in a nitrogen atmosphere to obtain polymer fine particles (1). When the particle size of the polymer fine particles (1) was measured by Coulter Multisizer III type (manufactured by Beckman Coulter, Inc.), the number average particle size was 3.5 μm and the coefficient of variation was 4.7%.

<Creation of conductive fine particles>
In a beaker, 50 parts of “Pink Summer (manufactured by Nippon Kanigen Co., Ltd.)” and 400 parts of ion-exchanged water were mixed. Separately, 50 parts of ion-exchanged water and 10 parts of polymer fine particles (1) ultrasonically dispersed were prepared. This was added to the mixed solution and stirred at 30 ° C. for 10 minutes to form a suspension. The cake obtained by solid-liquid separation was washed in the order of ion-exchanged water and methanol, and vacuum dried at 100 ° C. for 2 hours in a nitrogen atmosphere.

  Next, 10 parts of the dried particles are ultrasonically dispersed in 50 parts of ion-exchanged water, and this is added to a solution obtained by mixing 100 parts of “Red Summer (manufactured by Nippon Kanisen Co., Ltd.)” and 350 parts of ion-exchanged water. And stirred at 30 ° C. for 10 minutes to obtain a suspension. This suspension was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and methanol in that order, and vacuum-dried at 100 ° C. for 2 hours in a nitrogen atmosphere, so that palladium was deposited on the surface of the polymer fine particles (1). Adsorbed.

  Polymer fine particles (1) activated with palladium were added to 500 parts of ion-exchanged water and subjected to ultrasonic treatment for 30 minutes to sufficiently disperse the particles, thereby obtaining a fine particle suspension. While stirring this fine particle suspension at 50 ° C., nickel sulfate hexahydrate 50 g / L, sodium hypophosphite monohydrate 20 g / L, dimethylamine borane 2.5 g / L, citric acid 50 g / L An electroless plating solution (pH 7.5) consisting of the above was gradually added to the fine particle suspension to perform electroless nickel plating of the polymer fine particles (1). While sampling the particles during the plating process over time and observing them with a scanning electron microscope (SEM, manufactured by HITACHI: “S-3500N”), the particle size of any 10 particles is measured to determine the weight before plating. The plating thickness was calculated from the difference from the measurement result of the coalesced fine particles (1), and the addition of the electroless plating solution was stopped when the plating thickness reached 0.1 μm. The obtained conductive fine particles were separated by filtration, washed with ion-exchanged water, further washed with methanol, and vacuum dried at 60 ° C. for 12 hours to obtain conductive fine particles (1).

Example 2
In Example 1, Irganox1010 was changed to Irgafos168 (Tris (2,4-di-t-butylphenyl) phosphite, molecular weight: 646, manufactured by Ciba Specialty Chemicals), and was the same as Example 1. By the method, polymer fine particles (2) and conductive fine particles (2) were obtained.

Example 3
<Preparation of polymer fine particles>
In a four-necked flask equipped with a condenser, a thermometer, and a dripping port, put 800 parts of ion-exchanged water, 1.2 parts of 25% aqueous ammonia and 330 parts of methanol, and add 3-methacryloxypropyl from the dripping port with stirring. A mixed liquid of 50 parts of trimethoxysilane and 60 parts of methanol was added, and hydrolysis and condensation reaction of 3-methacryloxypropyltrimethoxysilane was performed to prepare an emulsion of organopolysiloxane particles.

  Next, 3.85 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd .: “Hytenol (registered trademark) NF-08”) as an emulsifier is added with 150 parts of ion-exchanged water. To the dissolved solution, 120 parts of styrene, 30 parts of 1,6-hexanediol dimethacrylate, 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd .: “V-65”) 2 A solution in which 2 parts of Irganox 10102 were dissolved was added, and the mixture was emulsified and dispersed at 6000 rpm for 5 minutes with a TK homomixer to prepare an emulsion of monomer components.

  Two hours after the start of the reaction, the obtained emulsion was added to an emulsion of polysiloxane particles and further stirred. Two hours after the addition of the emulsified liquid, the mixed liquid was sampled and observed with a microscope. As a result, it was confirmed that the polysiloxane particles were enlarged by absorbing the monomer.

  Next, the reaction solution was heated to 65 ° C. in a nitrogen atmosphere and held at 65 ° C. for 2 hours to perform radical polymerization of the monomer component. The emulsion after radical polymerization was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and methanol, and then vacuum-dried at 80 ° C. for 12 hours to obtain polymer fine particles (3). When the particle size of the polymer fine particles (3) was measured by Coulter Multisizer III type (manufactured by Beckman Coulter, Inc.), the number average particle size was 3.6 μm and the coefficient of variation (CV value) was 3.3%. .

<Preparation of conductive fine particles>
Conductive fine particles (3) were obtained in the same manner as in Example 1 except that the polymer fine particles (3) were used.

Example 4
Polymer fine particles (4) and conductive fine particles (4) were obtained in the same manner as in Example 3, except that the amount of Irganox1010 used was changed to 6 parts.

Example 5
Polymer fine particles (5) and conductive fine particles (5) were obtained in the same manner as in Example 3 except that Irganox1010 was changed to Irgafos168.

Example 6
Polymer fine particles (6) and conductive fine particles (6) were obtained in the same manner as in Example 3, except that Irganox1010 was changed to ADK STAB (registered trademark) 522A (molecular weight: 1832).

Example 7
Polymer fine particles (7) and conductive fine particles (7) were obtained in the same manner as in Example 3 except that styrene was changed to 2 parts and 1,6-hexanediol dimethacrylate was changed to 148 parts.

Example 8
Polymer fine particles (8) and conductive fine particles (8) were obtained in the same manner as in Example 3, except that styrene was changed to 0.6 parts and 1,6-hexanediol dimethacrylate was changed to 149.4 parts. It was.

Example 9
To a four-necked flask equipped with a condenser, a thermometer, and a dropping port, 90 parts of ion-exchanged water, 10 parts of styrene, 0.5 part of n-decyl mercaptan, and 0.1 part of sodium chloride are added. Nitrogen was purged for a period of time in the reaction vessel. Thereafter, the temperature of the mixed solution was raised to 70 ° C., and 0.1 part of potassium persulfate dissolved in a small amount of ion-exchanged water was added to the reaction system by a syringe. Thereafter, the reaction was carried out at 70 ° C. for 24 hours. After completion of the reaction, the obtained emulsion was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and then with methanol. When the particle size of the obtained polymer seed particles was measured with a Coulter Multisizer (manufactured by Beckman Coulter, Inc.), the number average particle size was 0.7 μm and the coefficient of variation was 3.0%.

  To a four-necked flask equipped with a condenser, a thermometer, and a dropping port, add 0.5 parts of the obtained polymer seed particles, 50 parts of ion-exchanged water, and 0.05 parts of sodium lauryl sulfate, and uniformly disperse them. A polymer seed particle dispersion was prepared, and 20 parts of a 3% by weight aqueous solution of polyvinyl alcohol was added thereto. Next, as an emulsifier, a solution obtained by dissolving 0.1 part of sodium lauryl sulfate in 50 parts of ion exchange water, 4 parts of styrene, 1 part of 1,6-hexanediol dimethacrylate, 0.05 part of Irganox 1010, benzoyl peroxide A solution in which 0.10 parts were dissolved was added and stirred with a homogenizer to prepare a monomer emulsion. The obtained monomer emulsion was added to the polymer seed particle dispersion and further stirred. Next, the temperature of the reaction solution was raised to 70 ° C. in a nitrogen atmosphere and held at 70 ° C. for 24 hours to perform radical polymerization of the monomer component. After the radical polymerization reaction, the obtained emulsion was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and methanol in order, and then vacuum-dried at 80 ° C. for 12 hours to obtain polymer fine particles (9). Obtained. Further, by the same method as in Example 1, a metal coating layer was formed on the surface of the polymer fine particles (9) to produce conductive fine particles (9).

Comparative Example 1
Comparative polymer fine particles (1) and comparative conductive fine particles (1) were obtained in the same manner as in Example 1 except that Irganox 1010 as an antioxidant was not used.

Comparative Example 2
Comparative polymer fine particles (2) and comparative conductive fine particles (2) were obtained in the same manner as in Example 5 except that Irganox 1010 as the antioxidant was not used.

Comparative Example 3
Comparative polymer fine particles (3) and comparative conductive fine particles (3) were obtained in the same manner as in Example 7 except that Irganox 1010 as the antioxidant was not used.

Comparative Example 4
A flask equipped with a stirrer, a dripping port and a thermometer was charged with 10 parts of 25% aqueous ammonia, 400 parts of water, and 6 parts of a 10% by weight aqueous solution of polyvinyl alcohol (Kuraray, “PVA-205”). , Stirred and mixed. The mixed solution was adjusted to a temperature of 20 ± 0.5 ° C., and while stirring, 55 parts of phenyltrimethoxysilane, 5 parts of styryltrimethoxysilane, and 2,2-azobis (4-methoxy-2,4 -Dimethylvaleronitrile) After adding a mixed solution in which 0.05 part is dissolved in 150 parts of methanol, the radical polymerization of a vinyl group is carried out by continuing the stirring for 2 hours, followed by hydrolysis and condensation reaction. Went.

  Next, the reaction product after radical polymerization is filtered through a 100-mesh wire mesh, dewatered by circular separation to form a cake, and this cake layer is dried in a dryer at 40 ° C. Comparative polymer fine particles (4) were obtained by crushing using a product manufactured by Matic Kogyo Co., Ltd. Further, using the obtained comparative fine particles (4), comparative conductive fine particles (4) were obtained in the same manner as in Comparative Example (3).

[Evaluation of anisotropic conductive material]
An anisotropic conductive material was prepared using the conductive fine particles obtained in Examples 1 to 9 and Comparative Examples 1 to 4, and the resistance value between the electrodes was evaluated.

  2 g of conductive fine particles were mixed and dispersed in 100 g of an epoxy resin (manufactured by Mitsui Chemicals: “Structbond (registered trademark) XN-5A”) to produce a conductive adhesive paste. Then, 0.1 mg of this paste was sandwiched between two glass substrates having an ITO transparent electrode film formed on the inner surface, and subjected to thermocompression bonding at 150 ° C. for 30 minutes while applying a pressure of 13.7 MPa with a press. A piece was made.

A heat-resistant connection reliability test was performed on the prepared test piece. In the heat resistance connection reliability test, the test piece was heat-treated at an ultimate temperature of 260 ° C./5 minutes, the connection resistance value after four heat treatments was measured, and the rate of change calculated by the following formula was less than 10%. The case where it was ○ was evaluated as good (good), the case where it was 10% or more and less than 15% was evaluated as Δ (good), and the case where it was 15% or more was evaluated as × (inferior). The results are shown in Table 2.
Rate of change (%) = [(connection resistance value after heat treatment−connection resistance value before heat treatment) / connection resistance value before heat treatment] × 100

  From Table 1, the polymer fine particles of Examples 1 to 9 having a compression fracture index P of 0.77 or more are compared with the polymer fine particles of Comparative Examples 1 to 3 having a compression fracture index P of less than 0.77. It can be seen that it has high heat resistance and mechanical strength. In particular, the polymer fine particles obtained by the seed polymerization method and the sol-gel seed polymerization method (Examples 3 to 7 and 9) have higher heat resistance and mechanical strength than the polymer fine particles of Examples 1 and 2. Had. In addition, since the polymer fine particle of Example 8 had little component amount derived from the styrene-type monomer which exists in polymer fine particle, compared with the other polymer fine particle, the thermal decomposition start temperature was a little low. Further, the polymer fine particles of Comparative Example 4 had a compression fracture index P of 0.96, but the compression fracture strengths P1 and P2 before and after the heat treatment were low and the mechanical strength was poor.

  From Table 2, it can be seen that the conductive fine particles of the present invention are those in which the conduction reliability is hardly lowered even after the heat treatment. In addition, when the compression fracture strength index P of the base particle (polymer fine particle) is 0.77 or more from the comparison between Example 6 (P: 0.77) and Comparative Example 3 (P: 0.76), It can be seen that the change rate of the connection resistance value after the heat treatment is significantly reduced. In particular, polymer particles (Examples 3 to 9) produced by a seed polymerization method or a sol-gel seed polymerization method, including an antioxidant, and using styrene as a monomer component in an amount of 0.5% by mass or more. It can be seen that the conductive fine particles having the polymer particles as the base particles (Examples 3 to 7 and 9) have a low connection resistance value even after the heat treatment and have high conduction reliability.

  The polymer fine particles of the present invention have excellent heat resistance and mechanical strength, and the mechanical strength after heat treatment is unlikely to decrease. Therefore, the conductive fine particles using the polymer fine particles of the present invention as the base particles are less likely to lower the conduction reliability after being subjected to a thermal history during electrical joining or solder reflow. The conductive fine particles of the present invention are highly reliable capable of maintaining an electrical connection between electrode substrates, such as anisotropic conductive films, anisotropic conductive pastes, conductive adhesives and conductive adhesives, It is suitably used as a conductive material for connecting the electrodes.

Claims (10)

A polymer fine particle characterized by having a compressive fracture strength index P represented by the following formula (1) of 0.77 or more and P2 of 2.9 (mN) or more.
P = P1 / P2 (1)
P1: Compressive fracture strength (mN) after heat treatment in air at 200 ° C. for 1 hour
P2: Compressive fracture strength before heat treatment (mN)   The T2 is higher than 280 ° C and T2 / T1 is 0.95 or more, where T1 is a thermal decomposition start temperature under a nitrogen stream and T2 is a thermal decomposition start temperature under an air stream. Polymer fine particles.   The polymer fine particle according to claim 1 or 2, comprising at least one kind of antioxidant selected from a primary antioxidant and a secondary antioxidant, and / or a component derived from an antioxidant.   The polymer fine particle according to any one of claims 1 to 3, wherein the polymer fine particle contains a component derived from a styrene monomer in an amount of 0.5% by mass or more in the constituent component of the polymer fine particle.   The polymer fine particles according to claim 1, wherein the number average particle diameter is 0.5 μm to 100 μm, and the coefficient of variation of the particle diameter is 20% or less. It is a manufacturing method of the polymer particulates according to any one of claims 1 to 5,
A step of polymerizing monomer components to produce seed particles;
A step of allowing the seed particles to absorb a monomer composition in which a vinyl monomer and at least one antioxidant selected from a primary antioxidant and a secondary antioxidant are mixed;
A method for producing polymer fine particles, comprising:   The electroconductive fine particle which has a metal coating layer on the surface of the polymer microparticle as described in any one of Claims 1-5.   The conductive fine particles according to claim 7, wherein the metal coating layer is a layer formed by an electroless plating method.   The conductive fine particles according to claim 8, which are used for solder reflow processing.   An anisotropic conductive material comprising the conductive fine particles according to claim 7 or 8.