JPH08302196A - Conductive filler and conductive silicone composition - Google Patents

Abstract

PURPOSE: To improve the conductivity without detriment to the curability, physical characteristics and thermal characteristics by blending a silicone composition with silver particles or silver-coated particles having a surface treated with a silicone compound. CONSTITUTION: Flaky, spherical or arborescent silver particles or silver-coated other conductive or nonconductive particles having a diameter or maximum length of 0.1-100μm are subjected to surface treatment with a noncurable liquid silicone compound having a viscosity at 25 deg.C of 10-100,000cP to give a conductive filler. A curable or noncurable silicone composition is mixed with this filler in an amount of 0.1-95wt.% based on the total weight of the mixture to give a conductive silicone composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filler for imparting conductivity to resins and the like and a curable silicone composition having conductivity.

[0002]

BACKGROUND OF THE INVENTION Various organic silicon resins, etc. can be obtained by adding a finely crushed conductive filler of carbon black or metal particles such as gold and silver to a resin composition. It is known to impart conductivity to the organic resin.

Conventionally, epoxy-based and polyimide-based conductive adhesives are commercially available as typical ones of conductive resin pastes. Silver particles are often used as the conductive material filled in these adhesives from the viewpoint of environmental stability, and the shape thereof is often flake-shaped, spherical, or dendritic. Among them, flake-shaped particles are known to be effective for expressing conductivity, but these are processed by processing silver to form finely divided conductive particles and prevent oxidation and aggregation during processing. A higher fatty acid such as stearic acid is used for the purpose, and as a result, the surface of the silver particles is coated or treated with the higher fatty acid. In fact, commercially available flake silver powders from several manufacturers have been coated or treated with higher fatty acids, and these treatments facilitate the dispersion of these silver particles in the resin and are widely used in conductive resins. There is.

However, the epoxy-based or polyimide-based resin adhesive containing the above silver particles has a high elastic modulus and has a drawback that distortion due to thermal expansion or the like cannot be eliminated, and thus it has been used in recent refined parts and circuits. Is not a reliable material.

To further elaborate on this point, silver particles can usually be obtained by various methods. For example, the atomization method is suitable for obtaining high-purity spherical silver, and dendritic silver can also be obtained by an electrolytic method. It is economically suitable to obtain silver particles by a reduction method from the viewpoints of productivity and quality stabilization, but there are drawbacks such as a large amount of ionic impurities remaining. On the other hand, as the silver powder to be filled in the conductive material, it is known that it is effective to use a flake-shaped silver powder, this is the atomization method, a stamp mill the silver powder obtained by the reduction method, Ball mill, stirring mill,
It can be obtained by a mechanical grinding method such as a fluid energy mill. At this time, a higher fatty acid is often coated in order to prevent the flakes from being recombined with each other or settling volume when mixed with a resin binder.

The silver particles coated with these higher fatty acids have a platinum catalyst when they are filled in a silicone composition, for example, when the curing system of the silicone composition is based on a hydrosilylation reaction (addition reaction). The lower hydrosilyl group and the carboxylic acid group of the higher fatty acid cause a dehydrogenation reaction, which causes foaming and curing inhibition, and makes the curability of the composition and the physical properties (hardness, strength, etc.) of the cured product extremely unstable. There are problems such as Regarding the heat resistance of the cured product, the inherent heat resistance of the silicone rubber is lost due to the deterioration of the higher fatty acid. On the other hand, even when the curing system is a condensation reaction (for example, dealcohol curing type), the fatty acid group of the higher fatty acid causes a dealcohol reaction with the alkoxy group or the like, which causes retardation or inhibition of curing. Further, the filling amount with respect to the silicone composition also decreases, and it becomes difficult to obtain a material having excellent electrical conductivity or thermal conductivity. Furthermore, when exposed to a high temperature, a large amount of volatiles and the like are volatilized due to thermal deterioration of organic substances, which causes problems such as contamination of the surroundings.

On the other hand, as a means for solving these problems, a material having good heat resistance and capable of reducing strain associated with thermal expansion has been proposed. For example, Japanese Examination 6
No. 42616 discloses that impact resistance is improved by using a material containing a silicone-modified resin containing 60 to 80% by weight of flaky silver powder for fixing a crystal resonator. In addition, Japanese Patent Publication No. 5-230373 proposes a composition which is coated with a silicone elastomer, a resin, and a fatty acid esterified to a gel, and which contains a finely divided silver particle in a high blending amount, and is long-term at high temperature. Teaches that there is little change in conductivity upon exposure to. However, even in these proposals, the curability of silicone-based compositions and the problem of volatilization of organic substances when exposed to high temperatures have not been solved, and they still have sufficient reliability for the above applications. Not not.

The present invention has been made in view of the above circumstances and is capable of relieving strain due to stress, stabilizing conductivity when exposed to high temperatures, and silicone resins, elastomers and gels. , An adhesive, when blended with a silicone composition such as grease, without impairing the curability, physical properties, and thermal properties of the composition,
A conductive filler that imparts high conductivity, and a conductive silicone composition containing the filler, such as a curable composition or silicone that cures to give a silicone resin, silicone rubber, silicone gel, silicone adhesive, etc. It is an object to provide a non-curable composition such as grease and thickener.

[0009]

Means and Actions for Solving the Problems The present inventor has conducted diligent studies to achieve the above object, and as a result, silver particles,
Especially when the silver particles are processed into flakes, a silicone compound (that is, an organo (poly) siloxane compound), preferably at least one hydrosilyl group (Si-H) is used.
In the case of surface-treating with a silicone compound having a group), not only can recombination of flakes, which is a conventional object of surface treatment, or precipitation volume when mixed with a resin binder can be prevented, but also silver particles in a silicone composition can be prevented. High filling is possible, strain due to stress can be relaxed, and conductivity can be stabilized when exposed at high temperature.
Furthermore, it has been found that it is effective in foaming, retardation of curing, and stabilization of physical properties. Even more surprisingly, when a silicone compound having a hydrosilyl group is used, the curability is further improved, the silicone composition is further highly filled, and ionic impurities are reduced. It is possible to obtain a material suitable as a silver particle, and since the silicone treatment agent has a smaller viscosity change with temperature than a higher fatty acid, it is advantageous in that the work of the silver particle shape processing step is easy. Based on the above findings, the present invention has been completed.

Therefore, the present invention provides a conductive filler composed of silver particles or silver-coated particles which are surface-treated with a silicone compound, and a conductive silicone composition containing the conductive filler.

The present invention will be described in more detail below. As the silver particles surface-treated with the silicone compound of the present invention, flaky, spherical, dendritic silver particles are used, and copper, nickel, carbon and graphite are used. It is also possible to use conductive particles such as the above and non-conductive particles such as mica, glass, and organic polymer coated with silver. In this case, the particle shape is preferably flake shape. The size of the particles is 0.1 to 1 as the diameter or the maximum length.
The thickness is preferably 00 μm, particularly preferably 0.5 to 10 μm.

On the other hand, the silicone used for the above surface treatment
The compound is a non-curable liquid silicone compound.
Is preferable, and in terms of workability, the viscosity at 25 ° C is
10 to 100,000 cP, more preferably 100 to 1
It is desirable to be 30,000 cP. This silicone
The compound is a linear, cyclic, branched, or three-dimensional network structure tree.
It may be any oily substance, and there is no particular regulation on the structure.
If [Si (CH₃)₂O] unit [Si (C₆H_Five)₂O] unit [Si (C₆H_Five) (CH₃) O] unit [Si (C H₂C H₂C F₃) (CH₃) O] unit [SiH (CH₃) O] unit [SiH (CH₃)₂O_1/2] Unit [Si (CH₃)₃O_1/2] Unit [Si (CH₃) O_3/2] It is possible to contain one kind or two or more kinds such as a unit, and especially S
It preferably contains a unit having an i-H group.

A compound represented by the following general composition formula R ′ _x R ″ _y Si _{(4-xy) / 2} can be preferably used, wherein R ′ is a hydrogen atom or a hydroxyl group. An unsubstituted or substituted monovalent hydrocarbon group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group,
Alkyl group such as decyl group, vinyl group, allyl group, alkenyl group such as propenyl group, isopropenyl group, butenyl group, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, benzyl group, phenylethyl group, etc. Aralkyl groups of and some hydrogen atoms of these groups are fluorine,
Ordinary C1-C12, preferably C1-C8 unsubstituted such as chloromethyl, bromoethyl, chloropropyl, trifluoropropyl, cyanoethyl, etc. substituted with halogen atoms such as chlorine and bromine, and cyano groups, or Substituted monovalent hydrocarbon groups may be mentioned. x and y are 0 ≦ x ≦ 1, 0.8 <
y ≦ 3, 0.8 <x + y ≦ 3, preferably 0.001 ≦
x ≦ 1, 1.5 ≦ y ≦ 2.3, 1.5 ≦ x + y ≦ 2.4
Is.

In this case, the silicone compound may be adjusted by using treating agents having different viscosities in order to adjust the viscosity to an appropriate value for a mechanical crushing process such as a ball mill operation.
Further, the silicone compound (that is, the organo (poly) siloxane compound) may contain a silicone-curable functional group such as a silanol group or a vinyl group.

The method of surface treating silver or silver coated particles with the above silicone compounds may be applied using the same methods used to apply conventional coatings of fatty acids or other materials to silver products. For example, when the particles are in the form of flakes formed by ball milling, the silicone compound coating may be applied during ball milling.

The conductive filler comprising silver or silver-coated particles coated with the above-mentioned surface-treated silicone compound of the present invention is compounded and filled in various organic resin compositions, and is particularly curable or uncured. It is suitably used as a conductive filler for a conductive silicone composition. In this case, the curing mechanism of this curable silicone composition can be selected according to the properties required of the composition. For example, even if it is used in either condensation curing type or addition curing type, which is a typical curing mechanism of liquid silicone rubber, it does not hinder the problem of foaming or the curing thereof, and the heat resistance of the cured product is essentially silicone rubber. It is possible to maintain the heat resistance of. In addition,
The curable or non-curable silicone composition may be in any form such as silicone resin, elastomer, gel, adhesive, grease and the like.

The amount of the conductive filler of the present invention to be added to such a silicone composition is appropriately selected and is usually 0.1 to 95% by weight, preferably 1 to 95% by weight in the composition. More preferably, it is mixed in the range of 10 to 95% by weight so as to give the required conductivity. That is, the filling amount of the conventional silver conductive filler is limited to about 80% by weight at the most, and it is disclosed in JP-B-6-42616 and JP-A-5-230.
As disclosed in Japanese Patent No. 373, it is said that the conductive filler of the present invention can be highly filled up to 95% by weight, and a composition excellent in heat conduction and electric conductivity can be obtained. Has specificity. In this case, in order to give the silicone composition the highest conductivity, the concentration of the inventive filler in the composition is the highest value at which this composition can be prepared and processed in the desired manner. In the case of up to 95% by weight of filler. If it exceeds 95% by weight, the viscosity becomes too high, and the handleability of the composition may deteriorate.

The silicone composition will be described in more detail below. When the conductive filler of the present invention is used in a condensation-curable liquid silicone rubber composition, a silanol group-containing organopolysiloxane and a hydrolyzable organosilicon compound are used. The compound and the curing catalyst are essential components, and the above-mentioned filler is added to this composition.

In this case, the silanol group-containing organopolysiloxane may be linear or branched. Usually, the main chain portion of the molecular chain is composed of repeating diorganosiloxane units, and the molecular chain end is diorganohydroxy. It is generally blocked with a siloxy group and / or a triorganosiloxy group, but it also contains a branched structure (that is, a monoorganosiloxy unit or a SiO ₂ unit) in a part of the main chain part. It may be Also,
The hydroxy group may be bonded to a silicon atom at the end of the molecular chain or may be bonded to a silicon atom in the middle of the molecular chain, but from the viewpoint of the curing speed of the composition, the physical properties of the gel cured product, etc. It preferably has at least a hydroxy group bonded to a silicon atom at the terminal of the molecular chain. Although the viscosity is not particularly limited, it is 25 ° C from the viewpoint of workability.
The viscosity is preferably 10 to 1,000,000 cP, and more preferably 100 to 10,000 cP. The silanol group-containing organopolysiloxane is represented by the following general composition formula (1) and has at least 1 at the terminal of the molecular chain.
Those having one, preferably one to five, and especially two to four hydroxyl groups are suitably used. R ¹ _a (HO) _b SiO _{(4-ab) / 2} (1)

In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, which does not contain an aliphatic unsaturated bond, a methyl group, an ethyl group, Propyl group, isopropyl group, butyl group, isobutyl group, t
ert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group and other alkyl groups, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group, hexenyl group Group, alkenyl group such as cyclohexenyl group, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group, and hydrogen atom of these groups. Examples thereof include a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, and a cyanoethyl group, which are partially or wholly substituted with a halogen atom such as fluorine, chlorine, bromine, or a cyano group.

Further, a is a positive number of 1.8≤a≤2.2, preferably 1.9≤a≤2.1, particularly 1.95≤a≤2.0, and b is 0 <b. ≦ 0.06, preferably 0.00
01 ≤ b ≤ 0.02, particularly 0.001 ≤ b ≤ 0.01, and a + b is a positive number 1.8 <a + b ≤ 2.26, preferably 1.9 ≤ a + b ≤ 2.22. Is.

Specific examples of the above-mentioned organopolysiloxane include the following compounds. In the following examples, Me represents a methyl group and Ph represents a phenyl group (hereinafter,
Similar).

[0023]

Embedded image

The above-mentioned organopolysiloxane can be produced by carrying out an equilibration reaction using a desired organocyclopolysiloxane or organopolysiloxane oligomer as a raw material with an alkali or acid catalyst.

The second component, a hydrolyzable organosilicon compound, functions as a cross-linking agent, reacts with the organopolysiloxane of the first component or water, and then reacts with the organopolysiloxane of the first component to form three-dimensional crosslinking. To form.

As the above-mentioned hydrolyzable organosilicon compound, at least two, preferably 2 to 3 in the molecule.
Alkoxy group, substituted alkoxy group or alkenyloxy substituted alkoxy group bonded to a silicon atom represented by 0, particularly 3 to 15 ≡Si-O-R (R is a carbon number of 1 to 4).
Is an alkyl group, an alkoxy-substituted alkyl group or an alkenyl group, such as a methyl group, an ethyl group, a propyl group,
Isopropyl group, butyl group, isobutyl group, tert-
Examples thereof include a butyl group, a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, an isobutenyl group, a 2-butenyl group, a methoxymethyl group, a methoxyethyl group, an ethoxydimethyl group and an ethoxyethyl group. ) Or a polymer thereof (i.e., a siloxane compound) is preferably used, and this silane is ≡Si—O.
In the case of having an organic group bonded to a silicon atom other than the -R group, this organic group is a substituted or unsubstituted monovalent carbon atom having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, similar to R ¹ described above. It is a hydrogen group. In particular, as the silane or its organosilicon compound, those represented by the following general formulas (2) to (4) are preferably used.

R² _mSi (OR)_4-m … (2) R² _nSi (OR)_3-n-R³ -Si (OR)_3-nR² _n (3) RO- (Si (OR)₂O)_p-Si (OR)₃ … (4)

In the formula, R is independently as defined above, and R ² is independently C 1-8, especially 1-6.
A substituted or unsubstituted monovalent hydrocarbon group of R
The same group as ¹ is exemplified. m is an integer of 0 to 3, and it is particularly preferably 0, 1 or 2. Also, n
Is an integer of 0 to 3 as long as it has at least two ≡Si—O—R groups in the molecule, and it is particularly preferably 0, 1 or 2. Furthermore, p is an integer of 0 to 50, especially 0 to 10. R ³ is a divalent hydrocarbon group having 1 to 8 carbon atoms, especially 2 to 4, and is an alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a methylethylene group, a phenylene group or a tolylene group. , An arylene group such as a xylylene group, —Ph—CH ₂ —, —Ph—CH ₂ C
_{H 2 -, - CH 2 -Ph} -CH 2 - , etc. are exemplified.

Specifically as the above-mentioned organosilicon compound,
The following compounds may be mentioned. In the formula below, Et
Is an ethyl group, Pr is a propyl group, and Vi is a vinyl group.
(The same applies below). R'Si (OMe)₃, R '₂Si (O
Me)₂, Si (OMe)_Four, R ' Si (OEt)₃,
R ’₂Si (OEt)₂, Si (OEt)_Four, R ' Si
(OC (CH₃) = CH₂)₃(R ' Is Me, Et, P
r, Ph or Vi. ) (MeO )₃Si-CH₂-CH₂-Si (OMe)₃, M
eO (Si (OMe)₂O)_qSi (OMe)₃(Q is
1, 2, 3, 4, 5, 6, 7, 8, 9 or 10
It )

The content of the hydrolyzable organosilicon compound is 0.001 to 2 with respect to 100 parts of the silanol group-containing organopolysiloxane (parts by weight, the same applies hereinafter).
0 part, preferably 0.1 to 20 parts, particularly 0.5 to 10 parts are suitable, and if the compounding amount is less than 0.1 part, the composition may not be sufficiently cured, and if it exceeds 20 parts. The cured product of silicone rubber becomes too hard.

As the hydrolysis catalyst, those capable of functioning as a hydrolysis catalyst with respect to the ≡Si—O—R group of an organosilicon compound having a hydrolyzability, for example, tin, titanium,
Organic complexes of metals such as aluminum, such as fatty acid salts and alcoholates, are suitable, and specific examples thereof include the following compounds. Of these, tin complexes are preferably used from the viewpoint of workability such as reactivity and pot life.

[0032]

Embedded image

In the formula, R ⁴ has 1 to 20 carbon atoms, especially 1 to 1 carbon atoms.
5 represents a substituted or unsubstituted monovalent hydrocarbon group, and is preferably an alkyl group or an alkenyl group. R ⁵ is an alkyl group having 1 to 10 carbon atoms, preferably a methyl group,
It is an ethyl group, a propyl group or a butyl group. Also, ac
ac represents an acetylacetonate group.

The amount of the above-mentioned hydrolysis catalyst is 1
0.001 to 10 parts, especially 0.1 to 2 parts is desirable with respect to 00 parts, and if it is less than 0.001 part, a satisfactory effect may not be obtained, and if it exceeds 10 parts, it is economically disadvantageous. May be

When the filler of the present invention is used in an addition-curing liquid silicone rubber composition, an organopolysiloxane containing an aliphatic unsaturated group such as an alkenyl group, an organohydrogensiloxane, and a curing catalyst are essential components. The above-mentioned filler will be added to the composition.

In this case, the aliphatic unsaturated group-containing organopolysiloxane is a known organopolysiloxane usually used as a main raw material for addition-curable silicone rubbers, and has a viscosity at 25 ° C. of 10 to 10,000. 000c
P is a diorganopolysiloxane represented by the general formula R ⁶ _a SiO _{(4-a) / 2} and containing at least two aliphatic unsaturated groups in one molecule. Here, R ⁶ is an aliphatic unsaturated group such as an alkenyl group having 2 to 8 carbon atoms such as a vinyl group, an allyl group, a propenyl group or a butenyl group, an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group. , A phenyl group, an aryl group such as a tolyl group, or a halogen-substituted monovalent hydrocarbon group selected from a 3,3,3-trifluoropropyl group and the like. a represents 1.8 <a <2.2. Further, each substituent may be different or the same. Furthermore, even if this organopolysiloxane is linear,
It may have a branched shape containing R ⁶ SiO _3/2 units or SiO _4/2 units. The substituent of the silicon atom may be basically any of the above, but as the aliphatic unsaturated group,
It is preferable to introduce a vinyl group and a methyl group or a phenyl group as other substituents. This organopolysiloxane can be produced by a conventionally known method, and can be generally obtained by carrying out an equilibration reaction of an organocyclosiloxane and a hexaorganodisiloxane in the presence of an alkali or acid catalyst.

The organohydrogensiloxane reacts with an aliphatic unsaturated group-containing organopolysiloxane and acts as a cross-linking agent, and its molecular structure is not particularly limited, and is conventionally produced, for example, linear or cyclic. Although various structures such as a branched structure can be used, it is necessary that each molecule contains at least 2, preferably 3 or more, hydrogen atoms directly bonded to silicon atoms. The substituents bonded to silicon atoms other than hydrogen in this compound are the same as the substituents in the organopolysiloxane of the aliphatic unsaturated group-containing organopolysiloxane component. This compound can be produced by a conventionally known method, and is generally octamethylcyclotetrasiloxane and / or tetramethylcyclotetrasiloxane and hexamethyldisiloxane or 1,1′-dihydro-2 which can serve as a terminal group. , 2 ',
Easily obtained by equilibrating a compound containing a 3,3′-tetramethyldisiloxane unit with a compound such as sulfuric acid, trifluoromethanesulfonic acid or methanesulfonic acid at a temperature of about −10 ° C. to + 40 ° C. be able to.

The amount of this component added is 0.5 to 3 with respect to 100 parts of the aliphatic unsaturated group-containing organopolysiloxane component.
0 copy is desirable. If the amount added exceeds 30 parts, the number of hydrogen atoms directly linked to silicon atoms becomes excessive, causing foaming, and the physical properties after curing become too hard or too soft to obtain sufficient properties as an elastomer. You will not be able to.

The curing catalyst platinum or platinum group compound is
The catalyst is used as a catalyst for promoting the addition curing reaction (hydrosilation) of the above-mentioned aliphatic unsaturated group-containing organopolysiloxane and organohydrogensiloxane, and known catalysts can be used. Specific examples thereof include platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, and complexes of chloroplatinic acid with olefins, aldehydes, vinyl siloxanes, acetylene alcohols, and the like. The addition amount may be appropriately increased or decreased according to the desired curing rate, but it is usually in the range of 1 to 2,000 ppm, preferably 1 to 200 ppm in terms of platinum metal amount relative to the composition.

Further, when it is necessary to adjust the curing time in order to put these materials into practical use, a vinyl group-containing organopolysiloxane such as vinylcyclotetrasiloxane, triallyl isocyanurate, or
Alkyl maleate, acetylene alcohols and silanes thereof, siloxane modified products, hydroperoxide,
A compound selected from the group consisting of tetramethylethylenediamine, benzotriazole and a mixture thereof may be used.

When imparting adhesiveness to the curable silicone composition, it is possible to add an adhesion-imparting component which does not interfere with curing. The addition amount is 20 parts or less, preferably 10 parts or less. If the amount added is too large, the physical properties of the cured product may deteriorate.

Further, regardless of whether it is a condensation type or an addition type, a reinforcing silica filler in an amount that does not impair the effects of the present invention, or a non-reinforcing filler such as quartz powder, diatomaceous earth or calcium carbonate, cobalt blue or the like. It is also possible to add colorants such as inorganic pigments and organic dyes, heat resistance and flame retardancy improvers such as cerium oxide, zinc carbonate, manganese carbonate, red iron oxide, titanium oxide and carbon black. Further, spherical or dendritic silver may be added to these compositions, or powdery, whisker-like, carbon black with a well-developed structure, graphite or the like may be added to these compositions for the purpose of improving the conductivity stability.

Further, the silicone resin composition, the silicone gel composition and the like can be prepared into known compositions, and the composition of the silicone composition is not particularly limited.

The application of such a silicone composition is used in the case where high heat such as soldering cannot be applied when fixing an electronic component in which an epoxy resin conductive adhesive is conventionally used to a substrate. To be done. For example, it can be used for fixing a crystal oscillator, fixing an IC, LED, or LSI chip to a lead frame such as a ceramic substrate, or other portions requiring conductivity.

[0045]

The conductive filler of the present invention, when added to a silicone composition or the like, imparts excellent fluidity, curability, conductivity and heat resistance to obtain a conductive resin having good heat resistance. It is very useful as a starting material. Further, a silicone composition containing such a conductive filler is useful as a conductive material having good heat resistance.

[0046]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples and Comparative Examples] Ag. No.
The silver particles shown in 1, 2, and 3 were obtained by the following method. Using 500 g of silver powder obtained by the reduction method, 500 g of each of the treating agents A, B and C shown in Table 1 was added thereto, and mechanically pulverized by a ball mill at room temperature (25 ° C.). The treated slurry obtained is used to remove excess A,
The B and C components were removed by filtration and then dried under reduced pressure at 100 ° C. to obtain the desired silicone-treated silver powder. These properties are as shown in Table 1.

4 is a commercially available product (manufactured by Fukuda Metal Foil & Powder Co., Ltd.,
The product name is AGC-B). 5 was obtained by using ethyl stearate in place of the silicone binder to obtain Ag. No.
The same process as 1, 2, 3 is performed. 6 is a spherical silver powder obtained by an unprocessed atomizing method of a commercial product (trade name G-1 manufactured by Tokoriki Kagaku Kenkyusho Co., Ltd.).

[0049]

[Table 1] A: Terminal trimethylsilyldimethylsiloxane, viscosity 5,000 cs (25 ° C.), KF manufactured by Shin-Etsu Chemical Co., Ltd.
-96 B: A terminal trimethylsilylmethyl hydrogen siloxane at A (number of methyl hydrogen siloxane units:
(About 40 pieces on average), Shin-Etsu Chemical Co., Ltd. KF-99)
What was added 10 wt% C: following siloxane HO-SiMe ₂ O-in _{A (SiMe 2 O) 10 -SiMe} 2 O
10% by weight of H added

Next, a silicone composition Sx having the following composition
1. And Sx2. The above binder coating in the amounts shown in Table 2
Add silver particles and cure under the following conditions.
Immediately after and after heat resistance test (150 ° C, 300 hours)
Examined. The results are shown in Table 2.Sx1. Addition-curable silicone rubber composition (Vi represents a vinyl group and Me represents a methyl group) ViMe₂SiO- (SiMe₂O)₃₀₀-SiMe₂Vi 100 parts Me₃SiO- (SiMe₂O)₅₀-(SiMe HO)₃₀-SiMe₃ 5 parts Pt 1,2-divinyl-1,1,2,2-tetramethyldisiloxane complex Amount of 5 ppm as platinum atom 50% Ethynylcyclohexanol / toluene solution 0.05 parts Me₃SiO- (SiMe₂O)₂₀-(SiMe HO)_Five-(SiMe (CH ₂CH ₂ Si (OMe)₃) O)₂-SiMe₃ 1.5 parts Curing condition is 150 ° C / 30 minutesSx2. Condensation-curable silicone composition (Ph = phenyl group, Me = methyl group) HO-SiMe₂O- (SiMe₂O)₂₅₀-SiMe₂-OH 100 parts HO-SiMe₂O- (SiMe₂O)_Ten-SiMe₂-OH 5 parts Ph-Si (OMe )₃ 8.5 parts Dibutyltin dilaurate 1 part Curing conditions: 25 ° C / 3 days

[0051]

[Table 2]

From the results shown in Table 2, Ag. 1-Ag. 3 is
There is no problem in any of fluidity, curability, conductivity, and heat resistance, and especially Ag. The one using 2 has very good conductivity. In contrast, stearic acid-treated Ag. Four
When used in an addition type silicone rubber composition, it causes curing inhibition and is uncured, so that physical properties after curing cannot be obtained. Even when used in a condensation type silicone rubber composition, the curing is insufficient. Also, A of ethyl stearate treatment
g. No. 5 can satisfy the initial characteristics, but the characteristics of the silicone rubber are lost due to the oxidation of ethyl stearate during heat resistance. In addition, Ag. 6
Of 600 parts exceeds the filling limit, and the viscosity cannot be measured. The filling property is poor and the viscosity is very high.

From the above, it can be seen that the silicone compound-coated silver particles of the present invention and the curable silicone rubber composition containing the same are excellent.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // H01B 1/22 H01B 1/22 A

Claims (4)

[Claims] 1. A conductive filler comprising silver particles or silver-coated particles which are surface-treated with a silicone compound. 2. The conductive filler according to claim 1, wherein the silicone compound is a silicone compound having at least one hydrosilyl group. 3. The conductive filler according to claim 1, wherein the silver particles or the silver-coated particles have a flake shape. 4. A conductive silicone composition containing the conductive filler according to claim 1, 2, or 3.