JP2005162827A - Conductive polyorganosiloxane composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a room temperature-curable polyorganosiloxane composition which has good curability and excellent workability and whose cured product is stable over time and shows superior conductivity and electromagnetic wave shielding property. <P>SOLUTION: The conductive polyorganosiloxane composition contains as the essential components (A) a silicon-functional polyorganosiloxane which has hydrolyzable groups more than two on the average in the molecule as the silicon-functional groups and viscosity of 10-100,000 mPa×s at 23°C, (B) silver powders and/or silver-plated powders, (C) a conductive carbon black, (D) a crosslinking agent and (E) a volatile organic solvent. Based on 100 pts. wt. of the silicon-functional polyorganosiloxane (A), the silver powders and/or silver-plated powders (B) are incorporated in a proportion of at least 200 pts. wt. and the conductive carbon black (C) is incorporated in a proportion of 0.5-20 pts. wt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a condensation-type conductive polyorganosiloxane composition that cures at room temperature into a rubbery elastic body, and in particular, the cured product exhibits stable conductivity over time, and exhibits excellent electromagnetic shielding effect. The present invention relates to a functional polyorganosiloxane composition.

  Conventionally, conductive silicone powder, carbon black, or a combination of these materials used as electromagnetic shielding materials for electrical and electronic equipment, switch contact materials, or conductive adhesives and sealants. Rubber compositions are known.

  However, in order to make the silicone rubber composition conductive, it is necessary to select the type of the silicone rubber as a base and the crosslinking / curing mechanism. In other words, those based on a room temperature curable silicone rubber that has a condensation reaction type and cures with moisture in the air are easy to handle and adhere to various substrates. However, even if a large amount of metal powder is blended, a good electromagnetic shielding effect cannot be obtained.

  In order to improve this point, a room temperature curable composition having improved conductivity by adding a volatile organic compound together with a conductive metal powder to a known one-component room temperature curable silicone rubber has been proposed. . (For example, see Patent Document 1)

  There is also a room temperature curable silicone rubber composition in which conductivity is stabilized by blending a silanol group-terminated diorganopolysiloxane with a conductive metal powder, a conductive filler such as carbon black, and a volatile organic solvent. Proposed. (For example, see Patent Document 2)

Furthermore, a conductive room temperature-curable polyorganosiloxane composition in which silver-coated mica particles and carbon black are blended with silanol-terminated diorganopolysiloxane has also been proposed. (For example, see Patent Document 3)
Japanese Patent Laid-Open No. 60-199057 JP-A-63-117065 Japanese Patent Publication No. 7-5837

  However, the silicone rubber composition described in Patent Document 1 or Patent Document 2 has a slow curing, and even when silver powder having very high conductivity is used, sufficient conductivity cannot be obtained. In addition, even the composition described in Patent Document 3 could not obtain sufficiently satisfactory conductivity and electromagnetic wave shielding properties.

  The present invention has been made to solve these problems, and is a room temperature curable polymer having excellent curability, excellent workability, stable cured products over time, and excellent conductivity and electromagnetic shielding properties. An object is to provide an organosiloxane composition.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention are based on a silicon-functional polyorganosiloxane having an alkoxy group that is a hydrolyzable group at the molecular end, and silver powder and / or The inventors have found that the electromagnetic shielding properties are greatly improved by mixing silver plating powder and conductive carbon black and coexisting a volatile solvent, thereby completing the present invention.

  That is, the conductive polyorganosiloxane composition of the present invention has (A) molecules having an average number of hydrolyzable groups exceeding 2 as silicon functional groups, and a viscosity at 23 ° C. of 10 to 100,000 mPa · s. s is a silicon-functional polyorganosiloxane, (B) silver powder and / or silver plating powder, (C) conductive carbon black, (D) a crosslinking agent, and (E) a volatile organic solvent. And (A) at least 200 parts by weight of (B) silver powder and / or silver plating powder with respect to 100 parts by weight of the silicon-functional polyorganosiloxane, and (C) conductive carbon black in an amount of 0.5-20. It is characterized by containing each by weight part ratio

  In the conductive polyorganosiloxane composition of the present invention, (D) an organooxysilane or a partially hydrolyzed condensate thereof can be contained as a crosslinking agent. Moreover, (E) The vapor pressure in 23 degreeC of a volatile organic solvent can be 0.1-100 mmHg.

  The conductive polyorganosiloxane composition of the present invention is stable and excellent in the contact between the compounded silver powder and / or silver plating powder in the rubber-like elastic body formed by curing the conductive polyorganosiloxane composition. Conductivity and electromagnetic shielding properties can be exhibited.

  Therefore, by applying the composition of the present invention to an elastic contact material of an electric / electronic device, a conductive adhesive or a sealing material, an electromagnetic wave shielding material, an antistatic material, etc., an electric / electronic device having excellent reliability is provided. can do.

  Embodiments of the present invention will be described below.

  An embodiment of the conductive polyorganosiloxane composition of the present invention has (A) an average of more than two hydrolyzable groups as silicon functional groups in one molecule, and a viscosity at 23 ° C. of 10 to 100, 000 mPa · s of silicon functional polyorganosiloxane, (B) silver powder and / or silver plating powder, (C) conductive carbon black, (D) cross-linking agent, and (E) volatile organic solvent, respectively contains.

で示されるポリジオルガノシロキサンを使用することができる。分子の形状は、実質的に直鎖状のものが好ましいが、一部分岐状のものが含まれていても良い。 In the embodiment of the present invention, the component (A) used as the base polymer is a silicon-functional polyorganosiloxane having an average of more than two hydrolyzable groups as silicon functional groups in the molecule, which will be described later ( D) A reaction (crosslinking reaction) is caused by the crosslinking agent to cure. The crosslinking reaction is a hydrolysis reaction followed by a condensation reaction, and the reaction proceeds in the presence of moisture in the air.
As the component (A), the following general formula:

The polydiorganosiloxane shown by these can be used. The molecular shape is preferably substantially linear, but may be partially branched.

In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other, and n represents the viscosity of the component (A) at 23 ° C. of 10 to 100,000 mPa · s. It is a number to do. R ² is a silicon-functional siloxy unit having at least one hydrolyzable group X represented by the general formula: —ZSiR ³ _3-p X _p . Here, Z represents oxygen and / or a divalent hydrocarbon group, and R ³ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same as or different from each other.

R ¹ is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group or a dodecyl group; an alkenyl group such as a vinyl group or an aryl group; a phenyl group And aryl groups such as tolyl group and xylyl group; aralkyl groups such as 2-phenylethyl group and 2-phenylpropyl group are exemplified, and a part of hydrogen atoms of these hydrocarbon groups is another atom or group. Substituted with, i.e., halogenated alkyl groups such as chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl; substituted carbons such as cyanoalkyl such as 3-cyanopropyl A hydrogen group is illustrated.

  It is easy to synthesize the raw material intermediate, and the component (A) has a low viscosity relative to the molecular weight, and the physical properties of the rubber-like elastic body after curing are well balanced. % Or more is preferably a methyl group, and it is more preferable that substantially all organic groups are methyl groups.

On the other hand, when imparting heat resistance, radiation resistance, cold resistance or transparency to the composition, a necessary amount of phenyl groups as part of R ¹ , when imparting oil resistance and solvent resistance, In the case where a 3,3,3-trifluoropropyl group or 3-cyanopropyl group is provided as a part of R ¹ or a surface having paintability is provided, a long chain alkyl group or aralkyl is provided as a part of R ^1. A group can be arbitrarily selected depending on the purpose, for example, in combination with a methyl group.

In the general formula representing the terminal group R ^{2 of the} component (A): —ZSiR ³ _3-p X _p , R ³ bonded to the silicon atom may be the same as or different from each other, and is the same as or different from R ^1. A substituted or unsubstituted monovalent hydrocarbon group. Examples of R ³ are the same as those of R ¹ . A methyl group or a vinyl group is preferred because synthesis is easy and the reactivity of the hydrolyzable group X is excellent.

  Examples of Z include oxygen atoms and alkylene groups such as methylene group, ethylene group and trimethylene group; divalent hydrocarbon groups such as phenylene group, which may be the same or different. In view of easy synthesis, an oxygen atom and an ethylene group are preferable, and an oxygen atom is particularly preferable.

X is a terminal group R ² is a hydrolyzable group is at least one existing silicon functional group. Examples of such X include alkoxy groups such as methoxy group, ethoxy group, propoxy group, and butoxy group; substituted alkoxy groups such as 2-methoxyethoxy group and 2-ethoxyethoxy group; enoxy groups such as isopropenoxy group, etc. And may be the same as or different from each other. In view of the ease of synthesis, the physical properties of the composition before curing, the stability during storage, the curability, the economy, and the wide range of applications, especially the corrosion resistance in applications of electrical and electronic components, the alkoxy group preferable. Furthermore, the number p of hydrolyzable groups which are silicon functional groups in the terminal group R ² is preferably 1, 2 or 3.

  In addition, in order to give good coating properties to the composition before curing and to give excellent physical properties (elongation and mechanical strength) to the rubber-like elastic body after curing, the component (A) at 23 ° C. The viscosity is in the range of 10 to 100,000 mPa · s. When the viscosity of the component (A) is less than 10 mPa · s, the rubber-like elastic body after curing is not sufficiently stretched and the mechanical strength is inferior. When the viscosity exceeds 100,000 mPa · s, it is difficult to obtain a uniform composition, and workability and workability also deteriorate. A particularly preferred viscosity is in the range of 100 to 50,000 mPa · s because physical properties required for the composition before and after curing can be obtained in a well-balanced manner.

  The silver powder and / or silver plating powder used in the embodiment of the present invention is an essential component for enhancing the conductivity of the composition and obtaining an excellent electromagnetic shielding effect. The shape may be any of particles, flakes, fibers, and the like. Moreover, the silver plating powder etc. which gave silver plating on the glass bead can be used similarly.

  (B) The compounding quantity of a component is at least 200 weight part with respect to 100 weight part of above-mentioned (A) component, More preferably, it is 300-1000 weight part. If it is less than 200 parts by weight, sufficient conductivity and electromagnetic wave shielding effect cannot be obtained, and if it exceeds 1000 parts by weight, the workability of the composition at the time of use is undesirably lowered.

  The conductive carbon black (C) used in the embodiment of the present invention is a composition that stabilizes the conductivity of the composition, prevents sedimentation of the conductive material during storage, adjusts the mechanical strength and viscosity, decreases the specific gravity, It is an effective component for cost reduction. Examples include acetylene black, furnace black, thermal black, lamp black, channel black, roll black, and disk black.

  (C) The compounding quantity of component is 0.5-20 weight part with respect to 100 weight part of (A) component, More preferably, it is 5-15 weight part. When the blending amount of the component (C) is less than 0.5 parts by weight, conductivity stability and mechanical strength cannot be obtained, and when it exceeds 20 parts by weight, the workability of the composition at the time of use decreases. It is not preferable.

  The component (D) used in the embodiment of the present invention is a crosslinking agent used in combination with the silicon-functional polyorganosiloxane of the component (A) described above, and (A) in the presence of water and a curing catalyst. Reacts with the silicon functional group X in the component to cure the composition. As shown below, a silicon compound having a silicon functional group and / or a partial hydrolysis condensate thereof is used.

That is, as the (D) crosslinking agent, the following general formula: R ⁴ _4-q SiY _q
(In the formula, R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other, Y represents a hydrolyzable group, and q is a number of 3 or 4.) Or a partially hydrolyzed condensate thereof.

Examples of R ⁴ include the same groups as the organic group R ¹ directly bonded to the silicon atom of the component (A). A methyl group or a vinyl group is preferred because it is easily available and an excellent crosslinking reaction rate is obtained. Examples of the hydrolysis-reactive group Y include the same groups as those exemplified as X existing at the terminal of the component (A).

  Examples of such (D) crosslinking agents include tetramethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane. , Tetrapropoxysilane, tetraisopropoxysilane and alkoxy group-containing compounds such as partially hydrolyzed condensates thereof; tetrakis (2-ethoxyethoxy) silane, methyltris (2-methoxyethoxy) silane, vinyl (2-ethoxyethoxy) Substituted alkoxy group-containing compounds such as silane, phenyltris (2-methoxyethoxy) silane and partial hydrolysis condensates thereof; methyltriisopropenoxysilane, vinyltriisopropenoxysilane, phenyl Li isopropenoxysilane silane, dimethyl isopropenoxysilane silane, such as an enoxy group-containing compounds such as methyl vinyl di- isopropenoxysilane silane and their partially hydrolyzed condensates are exemplified.

  Considering that the synthesis is easy, the storage stability of the composition is not impaired, and a large crosslinking reaction rate, that is, a high curing rate is obtained, among these silane compounds, tetramethoxysilane, tetraethoxysilane, It is preferable to use methyltrimethoxysilane, vinyltrimethoxysilane, methyltris (isopropenoxy) silane, vinyltris (isopropenoxy) silane and partial hydrolysis condensates thereof.

Further, in the embodiment of the present invention, in addition to the silicon functional compound having a monovalent hydrocarbon group described above as R ⁴ , a similar carbon functional compound having a substituted monovalent hydrocarbon group is represented by ( D) You may use as a part or all of a crosslinking agent. Examples of such R ⁴ include substituted amino groups, epoxy groups, isocyanato groups, (meth) acryloxy groups, mercapto groups, or alkyl groups and phenyl groups substituted with halogen atoms. Examples of the substituted alkyl group include a substituted methyl group, a 3-substituted propyl group, and a 4-substituted butyl group, but a 3-substituted propyl group is preferable because of easy synthesis.

Examples of such (D) crosslinking agent having R ⁴ include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriisopropoxysilane, 3-aminopropyltriacetamidosilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N-methyl-3-aminopropyltrimethoxysilane, N-phenyl-3- Substituted or unsubstituted amino group-containing silanes such as aminopropyltrimethoxysilane, N, N-dimethyl-3-aminopropyltrimethoxysilane; 3-glycidoxysilane trimethoxysilane, 3-glycidoxymethyldimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysila Epoxy group-containing silanes such as 3-isocyanatopropyltrimethoxysilane, isocyanato group-containing silanes such as 3-isocyanatopropylmethyldimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxy Silanes, (meth) acryloxy group-containing silanes such as 3-acryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane; mercapto group-containing silanes such as 3-mercaptopropyltrimethoxysilane; and 3-chloropropyl Illustrative are halogen atom-containing silanes such as trimethoxysilane.

  Such substituted hydrocarbon group-containing silanes and the above-mentioned vinyl group-containing silanes are carbon-functional silanes, and by adding them, the adhesion to various substrates when the composition is cured is improved. be able to.

  (D) The compounding quantity of a crosslinking agent is 0.1-15 weight part normally with respect to 100 weight part of (A) component, Preferably it is 0.3-10 weight part. If the amount is less than 0.1 part by weight, crosslinking is not sufficiently performed, and not only a cured product having low hardness can be obtained, but also the storage stability of the composition containing the crosslinking agent is deteriorated. On the other hand, if it exceeds 15 parts by weight, it is not preferable because it is economically meaningless and the balance between the curability of the composition and the mechanical properties after curing is significantly reduced.

  In the embodiment of the present invention, a curing catalyst for promoting the reaction (curing reaction) between (A) the silicon-functional polyorganosiloxane and (D) the crosslinking agent can be blended.

  Such curing catalysts include iron octoate, manganese octoate, zinc octoate, tin naphthate, tin caprylate, tin oleate, carboxylic acid metal salts; dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dioleate, diphenyltin Organotin compounds such as diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate; tetraethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, 1,3-propoxytitanium bis (ethylacetyl) Alkoxytitanium such as acetate); aluminum trisacetylacetonate, aluminum trisethylacetoacetate, diiso Organic aluminum compounds such as lopoxyaluminum ethyl acetoacetate and triethoxyaluminum; organic zirconium compounds such as zirconium tetraacetylacetonate, tetraisopropoxyzirconium tetrabutoxyzirconium, tributoxyzirconium acetylacetonate, tributoxyzirconium stearate . Organotin compounds and alkoxy titanium compounds are preferred because they have a large catalytic ability in the presence of a small amount. Moreover, these use is not limited to 1 type, Two or more types can be used together.

  The compounding quantity of a curing catalyst is 0.01-10 weight part per 100 weight part of (A) component, Preferably it is 0.1-5 weight part. Depending on the type of cross-linking agent, it may not be necessary to add such a curing catalyst. However, in a system that requires a catalyst, if it is less than 0.01 parts by weight, it takes a long time to cure and the conductivity is low. Will be delayed. On the other hand, if it exceeds 10 parts by weight, the curing time becomes too short and workability is impaired, and the elasticity and heat resistance of the cured product are inferior.

  The (E) volatile solvent used in the embodiment of the present invention is a component for stabilizing the conductivity of the composition over time and improving workability during processing and molding. This (E) volatile solvent is selected from organic solvents whose vapor pressure at 25 ° C. is 0.1 to 100 mmHg. If the vapor pressure of the solvent is less than 0.1 mmHg, the solvent will not evaporate sufficiently during curing, so that good contact with the silver powder as the component (B) cannot be obtained, and the vapor pressure of the solvent exceeds 100 mmHg Since the solvent volatilizes before curing, (B) stable contact of silver powder or the like cannot be obtained.

  Examples of such solvents include hydrocarbon solvents such as toluene, xylene, cyclohexane, n-heptane, and n-octane; ester solvents such as ethyl acetate, butyl acetate, and amyl acetate; methyl ethyl ketone, methyl isobutyl ketone, and acetophenone. Ketone solvents such as methanol, ethanol, isopropanol, butanol, alcohol solvents such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol; hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, etc. Chain siloxane solvents: cyclic siloxa such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, heptamethylvinylcyclotetrasiloxane, decamethylcyclopentasiloxane Such as system solvent is exemplified.

  The amount of the (E) volatile solvent is 5 to 500 parts by weight, more preferably 10 to 100 parts by weight, based on 100 parts by weight of the component (A). When the volatile solvent is less than 5 parts by weight, the conductivity of the rubber cured after being stored for a certain period of time varies greatly, and in some cases, an unexpected phenomenon such as an insulating property occurs. On the other hand, when the amount exceeds 500 parts by weight, there are disadvantages such as sedimentation of the conductive carbon black or a desired thickness cannot be obtained by a single application.

  In the embodiment of the present invention, in addition to the above components, a silica-based filler usually used in a silicone rubber composition can be blended. Further, depending on the purpose, various additives such as a plasticizer, a heat resistance improver, a flame retardant, and a processing aid may be appropriately added as long as the object of the present invention is not impaired.

  In the conductive polyorganosiloxane composition of the embodiment, the components (A) to (E) described above and various additives as necessary are uniformly mixed and dispersed in a state where moisture is blocked by a conventional method. Is obtained. For example, component (A) is charged into an all-purpose kneader or kneader, (B) silver powder and / or silver plating powder and (C) conductive carbon black are added in several portions, and mixing is repeated to uniformly disperse. Let At this time, in order to improve the dispersibility and reduce the change over time, a part of the component (A) is left to be charged, and the remaining amount after the total amount of the component (B) and the component (C) is added. It is also possible to add the component (A). Moreover, these mixtures can be passed through three rolls, or can be heat-kneaded. The homogeneous mixture thus obtained is cooled to around room temperature, and then a crosslinking agent and a volatile organic solvent are added.

  The obtained composition can be used as a so-called one-packaging room temperature curable composition which is stored only in a sealed container and cured only by exposure to moisture in the air during use. In addition, the composition of the present invention is prepared as a composition in which, for example, a crosslinking agent and a curing catalyst are separated, and is stored in two or three separate containers as appropriate, and these are mixed at the time of use. It can also be used as a room temperature curable composition.

  The polyorganosiloxane composition according to the embodiment of the present invention is used as an elastic contact material for electric / electronic devices, a conductive adhesive or a sealing material, an elastic electric resistor, an electromagnetic wave shielding material, an antistatic material, a conductive paint, and the like. By applying, it is possible to provide an electric / electronic device having excellent reliability with no fear that the conductivity will change over time.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to a following example. In the examples, “parts” means parts by weight, and all viscosities are values at 23 ° C. and relative humidity 50%.

Example 1
100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 3000 mPa · s, 5 parts of Denka Black HS-100 (trade name of carbon black manufactured by Denki Kagaku Kogyo Co., Ltd.) and FA2-3 which is silver powder ( 700 parts of Dowa Mining Co., Ltd. trade name, average particle size 5 μm) were added and mixed uniformly at room temperature for 20 minutes, and then kneaded uniformly at room temperature under reduced pressure for 30 minutes. Next, 5 parts of toluene was added as a volatile solvent, and the mixture was stirred and dispersed uniformly. Then, 2 parts of methyltrimethoxysilane, 2.5 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane and dibutylbis ( Triethoxysiloxy) tin (0.5 part) was added thereto and mixed uniformly while blocking moisture to obtain a conductive polyorganosiloxane composition.

Example 2
As shown in Table 1, instead of 100 parts α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 3000 mPa · s, 100 parts α, ω-trimethoxysiloxypolydimethylsiloxane having a viscosity of 4500 mPa · s. A conductive polyorganosiloxane composition was prepared in the same manner as in Example 1 except that was used.

Example 3
As shown in Table 1, a conductive polyorganosiloxane composition was prepared in the same manner as in Example 1 except that 20 parts of xylene was used instead of 20 parts of toluene.

Example 4
As shown in Table 1, a conductive polyorganosiloxane composition was prepared in the same manner as in Example 1 except that 20 parts of decamethylcyclopentasiloxane was used instead of 20 parts of toluene.

Example 5
To 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane with a viscosity of 3000 mPa · s, add 5 parts of Denka Black HS-100 and 700 parts of silver powder (FA2-3), and mix uniformly at room temperature for 20 minutes. Then, the mixture was uniformly kneaded for 30 minutes under reduced pressure at room temperature. Next, after adding 20 parts of decamethylcyclopentasiloxane and mixing and stirring uniformly, 3 parts of methyltrimethoxysilane and 2.5 parts of diisopropoxytitanium bis (ethylacetylacetate) were added thereto. Then, the mixture was uniformly mixed under moisture shielding to obtain a conductive polyorganosiloxane composition.

Comparative Example 1
After adding 700 parts of silver powder (FA2-3) to 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 3000 mPa · s, uniformly mixing at room temperature for 20 minutes, and then uniformly at room temperature under reduced pressure for 30 minutes Kneaded. Next, 2 parts of methyltrimethoxysilane, 2.5 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane and 0.5 part of dibutylbis (triethoxysiloxy) tin were added to each of these without adding a solvent. It mixed uniformly under interruption | blocking, and the electroconductive polyorganosiloxane composition was obtained.

Comparative Example 2
As shown in Table 1, a conductive polyorganosiloxane composition was prepared in the same manner as in Example 1 except that toluene as a solvent was not blended.

Comparative Example 3
As shown in Table 1, a conductive polyorganosiloxane composition was prepared in the same manner as in Example 1 except that Denka Black HS-100 was not blended.

Comparative Example 4
To 100 parts of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 3200 mPa · s, 5 parts of Denka Black HS-100 and 700 parts of silver powder (FA2-3) are added and mixed uniformly at room temperature for 20 minutes, and then decompressed at room temperature. The mixture was uniformly kneaded for 30 minutes. Next, 20 parts of toluene was added and mixed and stirred to disperse uniformly, and then 2.5 parts of 1,3-propanedioxytitanium bis (ethylacetylacetate) was added thereto and mixed uniformly while blocking moisture, A conductive polyorganosiloxane composition was obtained.

  Next, the viscosity and tack-free time were measured for the polyorganosiloxane compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 4, respectively. The tack free time was measured according to JIS K6249.

  Further, the compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were extruded into a sheet having a thickness of 1 mm, and the obtained sheets were left at 23 ° C. and 50% RH for 168 hours to be moisture in the air. Cured. About these sheets, the volume resistivity was measured by the constant current application method. Further, the electromagnetic shielding property was measured by measuring the intensity attenuation rate at an electric field (1 GHz) by the KEC method.

  Furthermore, the adhesion to metal (aluminum) was measured according to the method described in JIS K6301 as shown below.

  Measurement of adhesiveness: The composition was applied onto a flat aluminum member having a width of 25 mm and a length of 80 mm, and a shear adhesion test specimen was produced with an overlap width of 10 mm. This was left standing at 23 ° C. and 50% RH for 168 hours, cured by moisture in the air, and then the cured product was pulled so as to be peeled 180 degrees, and the shear adhesive strength was measured.

These measurement results are shown in Table 1.

  As can be seen from Table 1, the polyorganosiloxane compositions prepared in Examples 1 to 5 have a viscosity with good workability such as coating and a tack-free time. In addition, the cured product has low volume resistivity and good electrical conductivity, and also has an extremely high level of electromagnetic shielding properties. That is, since the value of the electromagnetic wave shielding effect is 60 dB or higher, it is evaluated that the electromagnetic wave shielding property is higher than the average, and that of 90 dB or higher is at a higher level, so the compositions of Examples 1 to 5 It was confirmed that the cured silicone rubber obtained from No. 1 had the highest electromagnetic shielding properties. Furthermore, it turned out that the hardened | cured material obtained from the composition of Examples 1-5 has favorable adhesiveness with respect to aluminum.

  According to the conductive polyorganosiloxane composition of the present invention, a cured product that is stable and exhibits excellent conductivity and electromagnetic shielding properties can be obtained. Therefore, by applying the composition of the present invention to an elastic contact material of an electric / electronic device, a conductive adhesive or a sealing material, an electromagnetic wave shielding material, an antistatic material, etc., an electric / electronic device having excellent reliability is provided. can do.

Claims (3)

(A) a silicon-functional polyorganosiloxane having an average number of hydrolyzable groups exceeding two as silicon functional groups in the molecule and having a viscosity at 23 ° C. of 10 to 100,000 mPa · s; and (B) Silver powder and / or silver plating powder, (C) conductive carbon black, (D) cross-linking agent, and (E) volatile organic solvent are essential components, respectively.
The (B) silver powder and / or silver plating powder is at least 200 parts by weight, and the conductive carbon black (C) is 0.5 to 20 parts by weight with respect to 100 parts by weight of the (A) silicon-functional polyorganosiloxane. The electroconductive polyorganosiloxane composition characterized by containing each by these.   2. The conductive polyorganosiloxane composition according to claim 1, wherein (D) the crosslinking agent contains organooxysilane or a partial hydrolysis condensate thereof.   The conductive polyorganosiloxane composition according to claim 1, wherein the vapor pressure of the (E) volatile organic solvent at 23 ° C is 0.1 to 100 mmHg.