JP3294146B2 - Metal-coated fine particles and conductive materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to conductive materials such as metal-coated fine particles and anisotropic conductive films, conductive paints, conductive inks, conductive adhesives, and electrical contact particles.

[0002]

2. Description of the Related Art Conventionally, as a conductive material such as a conductive paste and a conductive adhesive, a mixture of a metal powder such as gold, silver and nickel in a resin paste or a curable resin liquid has been used. However, since the metal powder has a non-uniform particle diameter, it is necessary to mix a large amount of the metal powder. Further, the metal powder has a drawback such that the metal powder precipitates during storage and the electric conductivity is not stable.

In recent years, instead of metal powder, gold, silver, or the like has been deposited on the surface of materials such as glass beads, silica beads, glass fiber chips, and synthetic resin fine particles having relatively uniform particle diameters and diameters.
Fine particles provided with a coating such as nickel and imparted with conductivity have been developed and used.

Among these fine particles, particularly metal-coated synthetic resin fine particles having a uniform particle diameter are mixed and dispersed in a plastic synthetic resin film or a synthetic resin adhesive, and are made of an anisotropic conductive material which conducts only in the pressure bonding direction. Used in manufacturing. However, such fine particles have poor adhesion between the resin and the metal, and therefore, it is necessary to make the synthetic resin fine particles porous or to generate irregularities on the synthetic resin surface by etching to have an anchor effect. .

[0005]

The metal coating layer manufactured in this manner sometimes peels off due to shear stress or vibration when kneading with a plastic resin to produce an anisotropic conductive material. In addition, the metal coating layer may be peeled off by the pressure applied during the conduction treatment.

Further, as described above, when the synthetic resin fine particles are made porous or subjected to an etching treatment that causes oxidative decomposition or hydrolysis, the strength of the synthetic resin fine particles is significantly reduced,
Alternatively, the particle diameter becomes small, and there arises a problem that the particles themselves are destroyed during the compression treatment, or the particles are not recovered while being compressed and deformed. As a result, the metal coating often peels off from the fine synthetic resin particles, resulting in poor conduction.

An object of the present invention is to improve heat resistance and further improve the adhesion between the synthetic resin surface and the metal coating layer.
An object is to obtain metal-coated fine particles having high adhesion.

[0008]

The present invention relates to metal-coated fine particles comprising synthetic resin fine particles and a metal layer formed on the surface thereof. In the present invention, at least the surface portion of the synthetic resin fine particles substantially contains 1 to 30% by weight of a carboxyl group-containing monomer, 10 to 97% by weight of a polyfunctional monomer, and 70% by weight or less of a monofunctional monomer. A copolymer obtained by adding 0.05 to 3 parts by weight of a chain transfer agent to 100 parts by weight of the monomer mixture to be polymerized.

The present inventors have proposed that synthetic resin
For 100 parts by weight of a monomer mixture containing 0% by weight of a carboxyl group-containing monomer, 10 to 97% by weight of a polyfunctional monomer and 70% by weight or less of a monofunctional monomer,
By adding 0.05 to 3 parts by weight of a chain transfer agent and polymerizing, and by adding a highly polar carboxyl group to the fine synthetic resin particles, the adhesion between the synthetic resin surface and the metal coating layer is remarkably improved. I found that. The synthetic resin fine particles according to the present invention have sufficient adhesiveness to the metal coating layer even if the surface is not chemically treated. Further, such synthetic resin fine particles show excellent adhesion even when subjected to chemical plating under mild conditions.

The metal-coated fine particles of the present invention prevent peeling of the metal layer, and are excellent in ultrasonic resistance in a washing step after the coating treatment, stability of kneading with a plastic resin, and conduction stability by pressure treatment. In addition, since the synthetic resin fine particles according to the present invention have less damage due to the chemical plating, the compression recovery can be maintained at a level similar to or close to that before the plating. Therefore, the metal-coated fine particles of the present invention,
There is no breakage due to the crimping process or permanent crushing deformation, and perfect conduction can be maintained semipermanently.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A synthetic resin fine particle according to the present invention is prepared by adding a predetermined amount of a chain containing a predetermined amount of a carboxyl group-containing monomer, a predetermined amount of a polyfunctional monomer, and a predetermined amount of a monofunctional monomer to a monomer mixture. It is a copolymer obtained by adding a transfer agent and polymerizing. These synthetic resin fine particles can be produced by aqueous suspension polymerization.

Carboxy group-containing monomers include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, acrylic acid dimer, methacrylic acid dimer, and mono ((meth) acryloyloxyethyl)
Monoesters of (meth) acryloyloxyalkylmaleic acid such as maleate, mono ((meth) acryloyloxypropyl) maleate and mono ((meth) acryloyloxybutyl) maleate, and mono ((meth) acryloyloxyethyl) phthalate, mono ( (Meth) acryloyloxypropyl) phthalate, mono ((meth)
(Meth) acryloyloxyalkyl phthalic acid monoesters such as (acryloyloxybutyl) phthalate are included. In addition to carboxylic acid monomers such as vinylbenzoic acid, acid anhydride monomers such as maleic anhydride and itaconic anhydride are also included.

In the present invention, one or more of these carboxy group-containing monomers may be contained in an amount of 1 to 30 in the total monomer mixture.
%, Preferably 3 to 15% by weight. Content is 1
When the amount is less than the weight percentage, the adhesion of the metal film is not improved.
On the other hand, if the content exceeds 30% by weight, alkali swelling occurs in the chemical plating treatment, which is not preferable.

The polyfunctional monomer includes ethylene di (meth)
Acrylate, propylene di (meth) acrylate, butylene di (meth) acrylate, hexylene di (meth)
Acrylate, trimethylolethanedi (meth) acrylate, trimethylolethanetri (meth) acrylate, trimethylolpropanedi (meth) acrylate,
Trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate Dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, di (meth) allyl ether, di (meth) allyl phthalate, tri (meth) allyl Isocyanurate, ditrimethylolpropanetetra (meth) acrylate, tripentaerythol octa (meth) acrylate, tetrapentaerythritol Ca (meth) acrylate and the like. In the present invention, one or more of these polyfunctional monomers are used in an amount of 10 to 97% by weight based on the total monomer mixture.

Incidentally, these polyfunctional monomers are rarely marketed as pure products, and most of them contain impurities or similar monomers. However, even such a commercial product can be used in the present invention as long as it is 50% or more as a display component. Among these polyfunctional monomers, (meth) acrylate monomers are most preferable because they have almost no non-polymerizable impurities.

In the present invention, one or more monofunctional monomers may be used in addition to the above two essential monomers. Monofunctional monomers include (meth) methyl acrylate, (meth)
Ethyl acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, -t- (meth) acrylate
Butyl, isobutyl (meth) acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, (meth)
Cyclohexyl acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth)
Stearyl acrylate, benzyl (meth) acrylate,
Cyclohexylmethyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene, vinyl acetate, vinyl chloride, propyl acetate,
(Meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, dimethyl itaconate and the like are included.

When a large amount of monofunctional monomer is contained, the compression recovery of the resulting synthetic resin fine particles is reduced. Therefore, the amount of the monofunctional monomer to be contained is preferably 70% by weight or less in the monomer mixture. In order to obtain even higher compression recovery, a monofunctional monomer of 40% by weight or less is preferable.

The monomer mixture can be polymerized using a known oil-soluble radical initiator. Oil-soluble radical initiators include benzoyl peroxide, lauroyl peroxide, t
-Butyl perbenzoate, t-butyl octanoate, t-butyl peroxyisobutyrate, t-butyl peroxyisopropyl carbonate, azobisisobutyronitrile, azobisvaleronitrile and the like.
These oil-soluble radical initiators comprise the monomer mixture 10
0.1 to 5 parts by weight is used with respect to 0 parts by weight.

A chain transfer agent is added to the monomer mixture. Examples of the chain transfer agent include 1-mercaptooctane, 3-mercaptooctane, 1-mercaptodecane, 3-mercaptodecane, 1-mercaptododecane,
3-mercapdodecane, dibutylamine, dioctylamine, N-methylaniline, N-ethylaniline and the like.

Generally, a polymer having a large amount of a polyfunctional monomer component becomes a three-dimensional polymer after polymerization. Particularly in suspension polymerization, it is considered that one molecule of such a polymer becomes one fine particle. Therefore, generally, if the particle size is adjusted, there is no need to adjust the molecular weight, and no chain transfer agent is used. However, when heat resistance is required for the metal-coated fine particles after the metal coating treatment or after being incorporated into an electric component, the polymerization terminal is reacted with a chain transfer agent to stop the polymerization reaction. The chain transfer agent is added in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the monomer mixture.

When no chain transfer agent is used, the thermal decomposition onset temperature is around 200 ° C. On the other hand, when 0.1 part by weight of the chain transfer agent is added, the thermal decomposition starting temperature rises to 260 ° C. or higher. However, when the chain transfer agent is added in an amount of 10 parts by weight or more, the polymer becomes a crosslinked product of a short branched polymer, which not only reduces the strength but also remains in the particles and lowers the adhesion of metal plating.

Suspension stabilizers for performing aqueous suspension polymerization include gelatin, starch, hydroxyethyl cellulose,
Hydroxymethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, fully or partially saponified polyvinyl alcohol, polyvinylalkyl ether, styrene / maleate alternating copolymer, isobutylene / maleate alternating copolymer, poly (meth) acrylate, poly In addition to water-soluble polymers such as (meth) acrylamide, there are poorly water-soluble inorganic salts such as barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, calcium phosphate, magnesium carbonate and the like. The stabilizers can be used alone or in combination of two or more.

As the polymerization method, a known method can be used. An aqueous solution in which a predetermined amount of a suspension stabilizer is dissolved or dispersed is charged into a condenser and a heating canister with a stirrer.
An auxiliary agent such as a polymerization initiator is added to the monomer mixture and dissolved. This solution is charged in a heating can and stirred vigorously.
Disperse in fine particles. Next, after heating and polymerizing these fine particles, they are washed and dried to obtain synthetic resin fine particles.

The obtained synthetic resin fine particles can be directly coated with metal. However, when applied to an anisotropic conductive film or an anisotropic conductive adhesive, synthetic resin fine particles having a uniform particle size distribution are preferable. Such fine particles, the coefficient of variation of the particle size distribution, that is, the ratio of the standard deviation to the average particle size,
It is at most 20%, preferably at most 10%.

If the particle size distribution of the synthetic resin fine particles as the base material is uniform, agglomerates are less likely to be generated in the chemical plating step, and metal-coated particles of only primary particles having good dispersibility tend to be obtained. is there.

Therefore, when uniform particles are required as described above, the particles are classified by a known means such as a sieving method, a wind method, and a water method. Although the classification may be performed after the metal coating step, the stage of the base material, that is, the synthetic resin fine particles is preferable because the specific gravity of the particles does not vary.

The synthetic resin fine particles manufactured as described above are coated with a metal film by using a known method. At that time, since the synthetic resin fine particles contain a carboxyl group in the base material, etching treatment with a strong alkali is not preferable. Therefore, in the metal-coated fine particles of the present invention, it is preferable to use a gentle method that does not damage the base material. It is preferable to perform at least one of the sensitization treatment and the activation treatment.

In the present invention, the metal film can be coated by using a physical metal deposition method or a chemical electroless plating method. As long as the metal has conductivity, gold, silver, copper, aluminum, chromium or the like is used in the vapor deposition method, and gold, silver, copper, nickel or the like is used in the electroless plating method. These metal films may cover two or more layers.

For example, in the electroless plating method, an alkali such as aqueous ammonia is added to a solution of a metal salt such as silver nitrate, silver cyanide, potassium potassium cyanide or nickel sulfate, and the synthetic resin fine particles according to the present invention are added thereto. Add and disperse while sufficiently wetting the surface. Then formalin,
An aqueous solution of glucose, tartaric acid, sodium hypophosphite, borohydride or the like is gradually added to reduce metal ions and deposit a metal film on the surface of the synthetic resin.

The thickness of the metal film must be 0.02 μm or more. This is for obtaining sufficient conductivity as a conductive material. However, when the thickness exceeds 5 μm, it is not preferable because it cannot follow the deformation of the synthetic resin particles due to the compression and the metal coating peels from the surface.

[0031]

The metal-coated fine particles of the present invention can be used as a chain transfer agent.
Good adhesion between the synthetic resin fine particles and the metal film whose heat resistance has been increased, and is good at kneading with thermoplastic resins, rubber, paints, adhesives, etc., and also when the particles are deformed by compression,
Excellent conductivity is obtained without peeling of the metal film. Also,
Since the synthetic resin fine particles according to the present invention are not subjected to severe processing such as etching, the strength and compression recovery inherent in the synthetic resin fine particles are substantially maintained. For this reason, the metal-coated fine particles of the present invention can exhibit stable conductivity.

In the present invention, the initial 10% compression modulus at 20 ° C.
The breaking strength, the compression recovery, the particle size distribution, the metal film peeling degree, the electric resistance value, and the thickness of the metal layer were measured as follows.

<Breaking Strength at 20 ° C. and Initial 10% Compression Modulus> The hardness index of the fine particles is represented by Hiramatsu's formula [Nikko 8
1, 1024 (1965)]. In the Hiramatsu ceremony,
Tensile strength are shown, in the present invention, the breaking strength S ₀ of the fine particles is represented by the following formula. S ₀ = 2.8 Q / πd ² [kgf / mm ² ] (where Q is the breaking stress [kg when the particles are crushed]
f], and d is the diameter [mm] of the particles. )

FIG. 1 is a graph showing the relationship between the compressive stress applied to the fine particles and the compressive deformation by applying the fine particles to a compression tester. The breaking strength Q is the breaking stress when the particles are crushed. As shown in FIG. 1, the fine particles are deformed when pressure is applied, and eventually break down. Measuring the breaking strength Q of such particles, by substituting the values into the above formulas, the breaking strength S ₀ of the fine particles is obtained.

However, such a breaking strength S ₀ is not appropriate as an index of hardness of the fine particles according to the present invention. This is because the breaking strength Q of the fine particles does not accurately reflect the hardness of the fine particles in a normal state. Therefore, in the present invention, the initial 10% compression modulus (hereinafter referred to as “G value”) of the fine particles is used as the hardness index. This G value is calculated on the basis of the compressive stress shown when the fine particles are deformed by 10% of the diameter at 20 ° C.

FIG. 1 shows the compressive stress P when the fine particles are deformed by 10% (indicated by d / 10). In the present invention, this compressive stress P is detected and substituted into the following equation to obtain a deformation rate 100
It is converted to the compression modulus corresponding to the stress at%. G = 28P / πd ² [kgf / mm ² ] (where P is the compressive stress [k when the particles are deformed by 10%]
gf], and d is the diameter [mm] of the particles. )

A load was applied to one sample particle scattered on the sample table in the direction of the center of the particle by a Shimadzu micro compression tester [MCTM-200 manufactured by Shimadzu Corporation], and the load was changed as shown in FIG. -The compression displacement was measured. This operation was repeated for five different particles whose diameter was observed to be the most average, and they were averaged. The measurement temperature was 20
C. and a compression rate of 0.675 g / sec. The load when the particles were crushed was defined as the breaking strength of the particles.

From the obtained load-compression displacement, the load at the time of the initial 10% displacement of the particle diameter was determined. The G value at 20 ° C. was calculated by substituting this load as the compressive stress P into the above equation.

<Compression recovery rate>
It measured using the small compression tester MCTM-200. FIG.
Indicates a displacement-load curve. The vertical axis is load, and the horizontal axis is displacement
is there. For one sample particle sprayed on the sample stage,
After applying a load up to 1 grf in the center direction, the load is reduced to 0 gr
Unload to f. The data during this time is recorded in the displacement-load curve.
The displacement from the origin to 1 grf (L₁),
Recovery displacement when unloaded to 0 grf (L _Two) Percentage of measured values
Is expressed as a percentage. The compression speed at this time is 0.029 g
/ Sec mode was used.

<Measurement of Average Particle Size and Particle Size Distribution> The average particle size was measured and averaged using a Coulter Counter ZM / C-256 type measuring device manufactured by Coulter Electronics Co., Ltd. . When using,
Calibration was performed using the company's standard particles. However, particles having an average particle diameter exceeding 30 μm were measured with an optical microscope.

<Degree of Peeling of Metal Coating> About 5 mg of metal-coated fine particles were placed in a test tube, and treated in an ultrasonic water layer (manufactured by Kagaku Kyoeisha, 100 V, 70 W, 42 kHz) for 30 minutes in a dry state. Observation is performed with a transmission optical microscope at a magnification of 600 times. More than 1,000 fine particles were observed in 5 visual fields or more, and the fine particles from which the metal coating was peeled by 50% or more were counted, and the ratio to the total number of observations was measured. Due to variation, ◎ <0.5%,
It is represented by a symbol of 0.5 ≦ O <3%, 3 ≦ Δ <10%, and 10% ≦ X.

<Electrical Resistance Value> 1.5 g of metal-coated fine particles were placed in a polyethylene cylinder having an inner diameter of 10 mm, a stainless steel electrode rod closely inserted into the cylinder was inserted, and a volume of 5 kg was applied between the electrodes under a load of 5 kg. The resistance was measured.

<Thickness of Metal Layer> In plating, metal adheres almost uniformly to 100% synthetic resin fine particles.
The thickness was calculated from the weight of the charged metal, the specific gravity of the metal, the weight of the synthetic resin fine particles, the average particle size, and the specific gravity. In the vapor deposition method, measurement was performed with an electron microscope.

[0044]

EXAMPLES < Reference Example 1> Polyvinyl alcohol [GH-1 manufactured by Nippon Synthetic Chemical Co., Ltd.]
7, saponification degree 87%], 8500 g of a 5% aqueous solution is vigorously stirred, into which 60 g (4% by weight) of methacrylic acid (manufactured by Wako Pure Chemical Industries) as a carboxyl group-containing monomer.
A mixture of 1,440 g (96% by weight) of pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a polyfunctional monomer and 20 g of benzoyl peroxide as an initiator and 1 g of monomethoxyhydroquinone was added under air. It was dispersed in fine particles. Thereafter, the temperature was raised to 80 ° C. under nitrogen, and polymerization was performed for 8 hours. After sufficiently washing the obtained polymer fine particles with water, a classification operation was performed to obtain an average particle diameter of 5.0 μm.
m and a standard deviation of 0.24 μm were obtained as synthetic resin fine particles (variation coefficient 4.80%).

10 g of the particles are put in 100 ml of a 5% aqueous ethanol solution, and ultrasonic waves (42 kHz,
Output 70W). Then, 0.1% by weight of first chloride
It was sensitized in a tin aqueous solution, and then activated in a 0.05% by weight aqueous solution of palladium chloride acidified with hydrochloric acid. Thereafter, the mixture is filtered, and the fine particles are separated from each other by 5.3% by weight of silver nitrate and 5% by weight.
Is dispersed in 300 ml of an aqueous solution containing 28% aqueous ammonia, and a 7% by weight aqueous formalin solution 100 is stirred.
ml was added over 15 minutes and silver plated. afterwards,
The obtained fine particles were washed with water and dried.

With respect to the obtained particles, the compression rupture strength before and after plating, the compression recovery rate, the conductivity of the plated particles, the plating thickness, and the degree of metal film peeling were measured. The results are summarized in Table 1. It was found that the plated fine particles had little peeling of the metal film and had good adhesion.

Reference Example 2 In the same manner as in Reference Example 1, synthetic resin fine particles having an average particle diameter of 10.2 μm and a standard deviation of 0.45 μm (coefficient of variation 4.41)
%). 20 g of these particles were obtained in the same manner as in Reference Example 1 to obtain silver-plated particles. Each property of the fine particles was measured, and the results are summarized in Table 1. These metal-plated fine particles also had good adhesion, and had no practical problems.

Reference Example 3 In Reference Example 1, the composition of the monomer mixture was 240 g (16% by weight) of methacrylic acid, 630 g (42% by weight) of pentaerythritol tetraacrylate, and 1,4-butanediol diacrylate (Nippon Kagaku). 630g
(42% by weight), the polymerization initiator was changed to 20 g of azobisisobutyronitrile, and the average particle size was 30.2 μm, standard deviation in the same manner as in Reference Example 1 except that the stirring speed of the aqueous polyvinyl alcohol solution was reduced. 1.20 μm synthetic resin fine particles (coefficient of variation: 3.97%) were obtained. 40 g of this was subjected to silver plating in the same manner as in Reference Example 1 to obtain metal-coated fine particles. The properties of the fine particles were measured, and the results are summarized in Table 1. These plated fine particles also had no practical problem.

REFERENCE EXAMPLE 4 In Reference Example 3, the composition of the monomer mixture was changed to 150 g (10% by weight) of acrylic acid and 1,05 butyl acrylate.
The suspension polymerization was carried out in the same manner as in Reference Example 3 except that the stirring speed was further reduced, and the stirring speed was further reduced to 0 g (70% by weight) and 300 g (20% by weight) of 1,6-hexamethylene diacrylate. The obtained fine particles are sieved, and the average particle size is 250 μm.
m, standard deviation 24 μm synthetic resin fine particles (coefficient of variation 9.
60%).

Gold was applied to the particles in the presence of argon using a sputtering device JFC-1300 manufactured by JEOL Ltd. Sputtering was performed at 30 mA for 60 seconds so that gold adhered to the surface of the spherical particles as much as possible. Then, the particles were rolled and stirred on a sample table, and sputtered three times by a spattering method. The gold-coated particles were squeezed, the metal layer was forcibly peeled off, and the thickness was measured with an electron microscope. Table 1 collectively shows other measurement results.

< Reference Example 5> The silver- plated particles produced in Reference Example 2 were mixed in an epoxy resin Cemedine Co., Ltd. Super C main ingredient at 2% by weight,
Further, a curing agent was mixed in the same amount as the main agent to produce a thermosetting anisotropic conductive adhesive (conductive material). This conductive material is
Approximately 10 mm on the end of a stainless steel plate of 50 mm x 50 mm x 1 mm
mm × 10 mm × 1 mm, and a stainless steel plate of the same size was brought into contact with the glass, and the stainless steel plate was hardened while keeping the gap between the stainless steel plates at 0.8 mm or more. When measured with a tester, no current flowed.

On the other hand, this conductive material was separately applied to a stainless steel plate of the same type in a size of 10 mm × 10 mm × 0.05 mm, and another stainless steel plate was overlaid and pressed so that the two stainless steel plates did not come into direct contact. It was then cured and measured for conductivity using a tester.

[0053] In <Comparative Example 1> Example 1, pentaerythritol tetraacrylate as 1,500 g (100 wt%), except using no methacrylic acid, in the same manner as in Reference Example 1, an average particle diameter of 5. Synthetic resin fine particles having a diameter of 1 μm and a standard deviation of 0.22 μm were obtained. The fine particles were prepared in the same manner as in Reference Example 1,
Silver plated fine particles were produced. Table 1 summarizes the characteristic values of these fine particles. The metal-coated fine particles of this example are inferior in anti-peeling property to those of Reference Example 1.

[0054] The synthetic resin microparticles prepared in <Comparative Example 2> Comparative Example 1, 10 wt% aqueous sodium hydroxide was immersed for 1 hour at room temperature to etch, washed with water, in the same manner as in Reference Example 1, silver plating fine particles Was manufactured. The fine particles of this example are inferior to those of Reference Example 1 in the breaking strength and the compression recovery after plating.

Comparative Example 3 In Reference Example 1, 60 g of divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.) (4% by weight) and 1,4 styrene were used.
Except for changing the 40g (Wako Pure Chemical Industries, Ltd.) (96 wt%), participation
To obtain resin fine particles having an average particle size of 7.5μm in the same manner as considered Example 1. 15 g of these fine particles were obtained in the same manner as in Reference Example 1,
Silver plated fine particles were produced. Table 1 summarizes the characteristic values of these fine particles. The fine particles of this example were extremely poor in anti-peeling properties.

Comparative Example 4 In Reference Example 4, 1,200 g of butyl acrylate was used.
(80% by weight) and 300 g (20% by weight) of 1,6-hexamethylene diacrylate, and metal-evaporated particles were obtained in the same manner as in Reference Example 4 except that acrylic acid was not used. Average particle size before vapor deposition is 252 μm, standard deviation 26
μm. The metal-coated fine particles of this example are inferior in anti-peeling property to those of Reference Example 4.

[0057]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between compressive stress and compressive deformation.

FIG. 2 is a graph showing compression recovery.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08K 9/02 C08K 9/02 C09D 5/24 C09D 5/24 11/00 11/00 H01B 1/00 H01B 1/00 C 1 / 22 1/22 A // B22F 1/02 B22F 1/02 A (56) References JP-A-8-113654 (JP, A) JP-A-9-27214 (JP, A) JP-A-7-287423 (JP, A) JP-A-5-295123 (JP, A) JP-A-5-230114 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 3/00-3 / 28 C08F 20/00-20/70

Claims (6)

(57) [Claims] 1. A metal-coated fine particle comprising a synthetic resin fine particle and a metal film formed on the surface thereof, wherein the synthetic resin fine particle comprises 1 to 30% by weight of a carboxyl group-containing monomer and 10 to 97% by weight. With polyfunctional monomers
A metal comprising a copolymer obtained by adding 0.05 to 3 parts by weight of a chain transfer agent to 100 parts by weight of a monomer mixture containing 70% by weight or less of a monofunctional monomer ; Coated fine particles. 2. The method according to claim 1, wherein the carboxyl group-containing monomer is acrylic acid, methacrylic acid, itaconic acid, maleic acid,
Fumaric acid, crotonic acid, acrylic acid dimer, methacrylic acid dimer, acryloyloxyalkylmaleic acid monoester, methacryloyloxyalkylmaleic acid monoester, acryloylalkylphthalic acid monoester, methacryloylalkylphthalic acid monoester, vinylbenzoic acid 2. The metal-coated fine particles according to claim 1, wherein the fine particles are at least one monomer selected from the group consisting of, maleic anhydride, and itaconic anhydride. Wherein the polyfunctional monomer, characterized in that at least one of acrylic acid esters and methacrylic acid esters according to claim 1 or 2, wherein metal-coated fine particles. 4. The method according to claim 1, wherein the fine particles of the synthetic resin have a coefficient of variation of 20%.
Characterized by having the following particle size distribution:
4. The metal-coated fine particles according to any one of 3 . 5. The method according to claim 1, wherein the metal-coated fine particles have a particle size of 1 to 500 μm.
The metal-coated fine particles according to any one of claims 1 to 4 , having an average particle diameter of: 6. The thermoplastic resin, thermosetting resin, paint, in a conductive material comprising at least one matrix material and a metal-coated fine particles selected from the group consisting of ink and adhesive of claim 1 to 5 A conductive material comprising the metal-coated fine particles according to any one of the preceding claims.