JP2007169356A - Polyorganosiloxane composition curable at room temperature - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyorganosiloxane composition curable at room temperature excellent in light shielding, concealing property and having excellent electric property and storing stability. <P>SOLUTION: The composition is obtained by formulating (A) 100 pts.wt of the polyorganosiloxane having at least two silicon functional groups in the molecule and having 0.02-1,000 Pa s of viscosity at 23°C, (B) 0.5-15 pts.wt of a crosslinking agent, (C) 0.01-15 pts.wt of a hardening catalyst and (D) 0.01-10 pts.wt of carbon black having ≤20 μm of particle diameter, ≥200 m<SP>2</SP>/g of nitrogen adsorption specific surface area and ≤100 cm<SP>3</SP>/100g of DBP oil absorption. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a room temperature curable polyorganosiloxane composition that cures at room temperature to produce a rubbery elastic body, and is particularly useful as a coating material for electrical and electronic equipment that requires light shielding and concealing properties. The present invention relates to a room temperature curable polyorganosiloxane composition having high properties and concealability, and excellent electrical properties and storage stability.

  Various room temperature curable polyorganosiloxane compositions that cure at room temperature to produce rubbery elastic bodies are known in the art. Among these, for applications such as coating materials and potting materials for electrical and electronic equipment such as LCD (Liquid Crystal Display), it is a type that causes a curing reaction by contact with moisture in the air. A substance that releases alcohol, acetone, or the like, which is less corrosive to, is generally used because of its good workability, low risk of electrode and wiring corrosion, and excellent adhesion.

  Examples of such a composition include a polyorganosiloxane whose end is blocked with a hydroxyl group, a composition comprising an alkoxysilane and an organic titanium compound, an alkoxysilyl group end-blocked polyorganosiloxane having an alkoxy group bonded to a terminal silicon atom, Examples include compositions comprising alkoxysilane and alkoxytitanium (see, for example, Patent Documents 1 and 2).

  By the way, a room temperature-curable polyorganosiloxane composition for use in electrical and electronic equipment may be required to have a light shielding property and a concealing property. In that case, those characteristics are given by blending the carbon black of the pigment. Conventionally, as the carbon black, a thermal black having a low structure or a high purity acetylene black has good dispersibility, few impurities, etc. It is generally used for the reason.

However, the low structure thermal black has a weak light shielding and hiding power, and is easily separated when the viscosity of the polyorganosiloxane of the base polymer is low, resulting in a problem that the composition lacks storage stability. . High-purity acetylene black was also superior to thermal black in terms of light shielding power, hiding power and ease of separation, but was not at a satisfactory level. In addition, since acetylene black has high conductivity, there is a problem that when the filling amount is increased in order to improve the light shielding property and the concealing property, the electrical characteristics are deteriorated.
Japanese Examined Patent Publication No. 39-27643 Japanese Unexamined Patent Publication No. Hei 4-2933962

  As described above, a room temperature-curable polyorganosiloxane composition imparted with a light shielding property and a concealing property by blending carbon black is known for use in applications requiring a light shielding property and a concealing property. In addition to insufficient light shielding and concealing properties, there are problems such as easy separation and reduced electrical properties.

  The present invention was made in response to such problems of the prior art, and has excellent light shielding properties and concealing properties useful for electrical and electronic equipment applications that require light shielding properties and concealing properties, and An object is to provide a room temperature-curable polyorganosiloxane composition having good electrical properties and storage stability.

The present inventors, the the prior art result object intensive studies to solve the following 20μm particle size, with nitrogen adsorption specific surface area of 200 meters ² / g or more, and, DBP oil absorption amount 100 cm ^3/100 g By using carbon black having the following specific quality characteristics, it has been found that a room temperature-curable polyorganosiloxane composition having excellent light-shielding properties and concealing properties, and excellent electrical characteristics and storage stability can be obtained. The present invention has been completed.

That is, the present invention
(A) For 100 parts by weight of polyorganosiloxane having 2 or more silicon functional groups in the molecule and having a viscosity at 23 ° C. of 0.02 to 1000 Pa · s,
(B) 0.5 to 15 parts by weight of a crosslinking agent,
(C) a curing catalyst 0.01 to 15 parts by weight, and (D) the particle size of 20μm or less, a nitrogen adsorption specific surface area of 200 meters ² / g or more, and, DBP oil absorption amount 100 cm ^3/100 g or less of carbon black 0 It is room temperature-curable polyorganosiloxane composition characterized by containing 0.01-5 weight part.

  The room temperature-curable polyorganosiloxane composition of the present invention is excellent in light-shielding properties and concealing properties, and also has good electrical characteristics and storage stability, and is a coating material for electrical and electronic equipment that requires light-shielding properties and concealing properties. It is useful for applications such as potting materials.

Hereinafter, embodiments of the present invention will be described.
The polyorganosiloxane which is the component (A) of the room temperature curable polyorganosiloxane composition of the present invention has two or more silicon functional groups in the molecule, and is typically represented by the following general formula (1). Is a substantially linear polyorganosiloxane.

In the formula (1), a plurality of R ¹ are substituted or unsubstituted monovalent hydrocarbon groups which may be the same or different from each other. R ¹ includes methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, alkyl group such as dodecyl group; cycloalkyl group such as cyclohexyl group; vinyl group, allyl group An alkenyl group such as a group; an aryl group such as a phenyl group, a tolyl group and a xylyl group; an aralkyl group such as a benzyl group, a 2-phenylethyl group and a 2-phenylpropyl group; and a hydrogen atom of these hydrocarbon groups A halogenated alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group substituted by another atom or group such as a halogen atom; Examples thereof include substituted hydrocarbon groups such as a cyanoalkyl group such as a propyl group. Among these, the synthesis is easy, the component (A) has a low viscosity for the molecular weight, gives good extrudability to the composition before curing, and good physical properties to the composition after curing. Therefore, 85% or more of all organic groups are preferably methyl groups, and substantially all organic groups are more preferably methyl groups. However, when it is necessary to impart heat resistance and cold resistance to the cured rubber-like elastic body, it is preferable to use a necessary amount of aryl groups as a part of R ¹ .

In the formula (1), ^{R 2} represents a group _{^{-Z-SiR 3 (3-p}} ) X p. R ³ is a substituted or unsubstituted monovalent hydrocarbon group which may be the same as or different from each other, and examples thereof are the same as those for R ¹ . A methyl group or a vinyl group is preferable because of easy synthesis and excellent X reactivity. Z may be the same as or different from each other, and examples thereof include an oxygen atom, and an alkylene group such as a methylene group, an ethylene group, and a trimethylene group, and a divalent hydrocarbon group such as a phenylene group. . From the viewpoint of ease of synthesis, an oxygen atom and an ethylene group are preferable, and an oxygen atom is particularly preferable. X is at least one silicon functional group present in the terminal group R ² , that is, a hydroxyl group and a hydrolyzable group. Examples of the hydrolyzable group include an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group; a substituted alkoxy group such as a 2-methoxyethoxy group and a 2-ethoxyethoxy group; an enoxy group such as an isopropenoxy group, Examples include a ketoximato group such as a methyl ethyl ketoxime group, an acetoxy group, and the like, which may be the same or different. From the viewpoints of ease of synthesis, physical properties of the composition before curing, stability during storage, curability, corrosiveness to metals, etc., an alkoxy group and an enoxy group are preferred. The number p of the silicon functional group X in the terminal group R ² is 1 to 3.

  In the present invention, in order to impart moderate extrudability to the composition before curing and to give excellent mechanical properties to the rubber-like elastic body after curing, the polyorganosiloxane as the component (A) is 23 ° C. Therefore, n in the formula (1) is a number (integer) in which the viscosity of the component (A) at 23 ° C. falls within the above range. If the viscosity of the component (A) at 23 ° C. is less than 0.02 Pa · s, the rubber-like elastic body after curing is insufficiently stretched, and conversely if it exceeds 1000 Pa · s, workability such as dischargeability and flow characteristics. Decreases. The particularly preferred viscosity of the component (A) is in the range of 0.1 to 100 Pa · s because the properties required for the composition before and after curing are harmonized.

  Such a polyorganosiloxane can be obtained, for example, by ring-opening polymerization or ring-opening copolymerization of a cyclic diorganosiloxane monomer such as octamethylsiloxane with an acidic catalyst or an alkaline catalyst in the presence of water. it can

  The crosslinking agent as the component (B) of the room temperature curable polyorganosiloxane composition of the present invention includes the silicon functional group X in the component (A) in the presence of water and the curing catalyst of the component (C) described below. A silicon compound having a silicon functional group and / or a partially hydrolyzed condensate thereof is used for reacting and curing the composition.

The silicon compound having a silicon functional group is represented by the following general formula (2):
R ⁴ _(4-q) SiY _q (2)
Wherein 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 2 or more and 4 or less. It is the number of

As R ⁴ , the same group as the organic group R ¹ directly bonded to the silicon atom of the component (A) can be exemplified, and since it is easily available and has an excellent crosslinking reaction rate, a methyl group Or a vinyl group is preferable. Examples of the hydrolyzable group Y are the same as those exemplified as the hydrolyzable group of X existing in the terminal group of the component (A).

  Examples of such crosslinking agents include tetramethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetrapropoxy. Alkoxy group-containing compounds such as silane, tetraisopropoxysilane, dimethyldimethoxysilane, vinylmethyldimethoxysilane, dimethyldiethoxysilane and partial hydrolysis condensates thereof; tetrakis (2-ethoxyethoxy) silane, methyltris (2-methoxy) Substituted alkoxy group-containing compounds such as ethoxy) silane, vinyl (2-ethoxyethoxy) silane, phenyltris (2-methoxyethoxy) silane and partial hydrolysis condensates thereof; Enoxy group-containing compounds such as tillyisopropenoxy silane, vinyl triisopropenoxy silane, phenyl triisopropenoxy silane, dimethyl diisopropenoxy silane, methyl vinyl diisopropenoxy silane and their partial hydrolysis condensates Ketoximato group-containing compounds such as methyltris (methylethylketoxime) silane, vinyltris (methylethylketoxime) silane and their partial hydrolysates; acyloxy group-containing compounds such as methyltriacetoxysilane and their partial hydrolysates However, a substituted alkoxy group-containing compound and an enoxy group-containing compound are preferred from the viewpoint of corrosiveness to metals. These may be used alone or in combination of two or more.

  Considering that the crosslinking agent of component (B) is easy to synthesize, does not impair the storage stability of the composition, has little corrosiveness to metals, and gives a high crosslinking reaction rate and thus a high curing rate. Then, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, dimethyldimethoxysilane, vinylmethyldimethoxysilane, dimethyldiethoxysilane, methyltris (isopropenoxy) silane, vinyltris (isopropenoxy) silane and their partial hydrolysis It is preferable to use a decomposition condensate.

  The compounding amount of the crosslinking agent of the component (B) is 0.5 to 15 parts by weight, preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the component (A). That is, when the amount is less than 0.5 part by weight, the crosslinking is not sufficiently performed, and only a cured product having low hardness may be obtained, and the storage stability of the composition containing the crosslinking agent becomes poor. On the contrary, if it exceeds 15 parts by weight, a part thereof is separated from the system during storage, the shrinkage rate at the time of curing is increased, and physical properties such as elasticity after curing are lowered.

  In addition, when (A) component itself uses a polymer having crosslinkability (for example, in general formula (1), X is a hydrolyzable group and p is more than 1 on average), basically, crosslinking Curing is possible without an agent, but even in such a case, by blending the crosslinking agent in the above range, the curability of the composition and the mechanical properties of the rubber-like elastic body obtained by curing are obtained. Can be realized in a balanced manner.

  The curing catalyst which is the component (C) of the room temperature curable polyorganosiloxane composition of the present invention is the presence of moisture in the components (A) X and / or the components (A) X and (B) Y. It is a curing catalyst for obtaining a rubber-like elastic body by reacting downward to form a crosslinked structure. Examples of such component (C) include organic titanium such as tetraethoxy titanium, tetrapropoxy titanium, tetrabutoxy titanium, diisopropoxy-bis (ethyl acetoacetate) titanium, and 1,3-propoxy titanium bis (ethyl acetylacetate). Compounds: Iron octoate, manganese octoate, zinc octoate, tin naphthate, tin caprylate, tin oleate, carboxylic acid metal salts; dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin diolate, diphenyltin diacetate, dibutyltin oxide , Organotin compounds such as dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate; tetraethoxytitanium, aluminum Organic aluminum such as subacetylacetonate, aluminum trisethylacetoacetate, diisopropoxyaluminum ethylacetoacetate, triethoxyaluminum; zirconium tetraacetylacetonate, tetraisopropoxyzirconium, tetrabutoxyzirconium, tributoxyzirconium acetylacetonate, An organic zirconium compound such as tributoxyzirconium stearate is exemplified. These may be used individually by 1 type, and may mix and use 2 or more types. Of these, organotitanium compounds are preferred because not only have a small amount of catalyst activity but also a composition with few impurities. In particular, titanium chelates such as diisopropoxy-bis (ethyl acetoacetate) titanium and 1,3-propoxytitanium bis (ethylacetylacetate) are preferable.

  The amount of the (C) component curing catalyst is 0.01 to 15 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the component (A). If it is less than 0.01 part by weight, it does not act sufficiently as a curing catalyst, and not only takes a long time for curing, but also the curing in the deep part of the rubber layer far from the contact surface with air becomes insufficient. On the other hand, if it exceeds 15 parts by weight, it has no effect corresponding to the blending amount and is meaningless as well as uneconomical. In addition, the storage stability is lowered.

The carbon black of component (D) of the room temperature curable polyorganosiloxane composition of the present invention imparts excellent light shielding properties and concealing properties to the composition, and prevents deterioration of its electrical properties and storage stability. It is an important and characteristic component in the invention, and satisfies the following quality characteristics.
(1) Particle size: 20μm or less
(2) Nitrogen adsorption specific surface area: 200 m ² / g or more
(3) DBP oil absorption amount: 100 cm ^3/100 g or less particle size, if any one of the nitrogen adsorption specific surface area and DBP oil absorption outside the imparts excellent light-shielding property, a hiding property, and good electrical It cannot give properties and storage stability.

In the present invention, the particle diameter is preferably 10 to 20 μm, and more preferably 10 to 15 μm. Further, the nitrogen adsorption specific surface area is preferably 200 to 500 m ² / g, more preferably 300~500m ² / g. Additionally, DBP oil absorption is preferably 40~100cm ³ / 100g, and more preferably 40~80cm ³ / 100g.

Here, the said particle diameter, nitrogen adsorption specific surface area, and DBP oil absorption amount are demonstrated.
[Particle size] This is an average diameter obtained by measuring and calculating a small spherical component (having a contour due to microcrystals and cannot be separated) constituting the carbon black aggregate with an electron microscope.
[Nitrogen adsorption specific surface area] BET specific surface area.
[DBP oil absorption] This is a characteristic value defined in JIS K 6217. In the present invention, an absorption meter is used, and per 100 g obtained from 70% of the maximum torque when DBP is added to carbon black. It shows with DBP oil absorption.

  The blending amount is also important in order to impart excellent light-shielding properties and concealing properties to the composition and to give good electrical properties and storage stability. In the present invention, the component (D) is added in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.2 to 2 parts by weight with respect to 100 parts by weight of the component (A). , Mix. If it is less than 0.01 part by weight, excellent light-shielding properties and concealing properties cannot be obtained. Conversely, if it exceeds 10 parts by weight, the electrical properties and stability of the composition are lowered.

  Carbon black is classified into types such as thermal black, furnace black, and acetylene black depending on the production method and quality characteristics, but the type is not particularly limited as long as the quality characteristics satisfy the above range. .

  The room temperature curable polyorganosiloxane composition of the present invention includes, in addition to the above-described components, inorganic fillers and adhesion improvers that are usually blended in this type of composition as long as the effects of the present invention are not impaired. Various additives such as pigments, thixotropy imparting agents, viscosity modifiers for improving extrusion workability, UV absorbers, fungicides, heat resistance improvers, flame retardants, etc. may be blended as necessary. it can. Examples of inorganic fillers include fumed silica, calcined silica, precipitated silica, fumed titanium, and those whose surfaces are hydrophobized with organochlorosilanes, polyorganosiloxanes, hexamethyldisilazane, and the like. In addition, calcium carbonate, organic acid surface-treated calcium carbonate, diatomaceous earth, pulverized silica, aluminosilicate, magnesia, alumina and the like can also be used. The blending amount of the inorganic filler is preferably in the range of 1 to 100 parts by weight, more preferably in the range of 3 to 50 parts by weight with respect to 100 parts by weight of the component (A).

  The room temperature curable polyorganosiloxane composition of the present invention can be obtained by mixing the above components (A) to (D) and various components blended as necessary in a state where moisture is blocked. The obtained composition can be used as a so-called one-packaging room temperature curable composition that is stored as it is in a closed 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 order of mixing the components is not particularly limited.

  The room temperature curable polyorganosiloxane composition obtained according to the present invention is stable under sealed conditions where moisture is not present, and is cured at room temperature upon contact with moisture in the air to produce a rubber-like elastic body. In particular, the room temperature curable polyorganosiloxane composition of the present invention is excellent in light-shielding properties and concealing properties, and also has good electrical characteristics and storage stability. Therefore, the composition of the present invention is useful as an elastic adhesive for electric / electronic devices, a coating material, a potting material, and the like, and particularly useful as an electrode / wiring coating material. Specifically, for example, a wiring board in which electrodes and wirings made of ITO, copper, aluminum, silver, gold, etc. are formed on a board made of epoxy resin, phenol resin, polyimide resin, etc. or a board made of ceramic such as alumina. Further, it is suitably used as an electrode / wiring coating material or the like on a mounting substrate on which electronic parts such as semiconductor devices such as ICs, resistors, and capacitors are mounted.

  When the composition of the present invention is used as a coating material for electrodes and wirings on a substrate, a dipping method, a brush coating method, a spray method, a dispensing method, etc. can be used as the coating method. Is usually 0.01 to 3 mm, preferably 0.05 to 2 mm. If the thickness is less than 0.01 mm, there is a possibility that sufficient light shielding properties and concealing properties cannot be obtained. On the other hand, if the thickness exceeds 3 mm, not only a further effect cannot be obtained, but it takes time to cure the inside, which is uneconomical.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the scope of the present invention. In the examples, “part” means “part by weight”, and all physical properties such as viscosity are values at 23 ° C. and relative humidity 50%.

Example 1
100 parts of tridimethylsilyl-blocked polydimethylsiloxane (viscosity: 1 Pa · s), 5 parts of dimethyldichlorosilane-treated fumed silica (trade name Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.), 3 parts of methyltrimethoxysilane, diiso 2 parts of propoxy-bis (ethyl acetoacetate) titanium and 1 part of carbon black A shown in Table 1 were added and mixed uniformly while blocking moisture to obtain a polyorganosiloxane composition.

Example 2, Comparative Examples 1-3
A polyorganosiloxane composition was obtained by the same composition and the same method as in Example 1 except that carbon blacks B, C, D and E shown in Table 1 were used instead of carbon black A, respectively.

About the polyorganosiloxane composition obtained by each said Example and each comparative example, various characteristics were evaluated by the method shown below.
[Light shielding]
A polyorganosiloxane composition was applied on a 1 mm thick glass plate to a thickness of 100 μm and allowed to cure in an atmosphere of 23 ° C. and 50% RH for 24 hours to prepare a test sample. The light transmittance was measured at a wavelength of 400 nm using a spectral hardness meter manufactured by Seisakusho Co., Ltd. and a U-3410 type spectral hardness meter.
[Volume resistivity]
The polyorganosiloxane composition was cured at 23 ° C. and 50% RH for 3 days to prepare a sheet having a thickness of 1 mm, and measured according to JIS K 6249.
[Stability]
40 g of the polyorganosiloxane composition is placed in a 50 ml glass bottle, centrifuged for 1 hour at 2000 rpm with a centrifuge manufactured by Kokusan Co., Ltd., and an H-103N centrifuge, and then visually observed for occurrence of separation in the bottle. did.

These results are shown in Table 2 together with the composition.

  As is clear from Table 1, the polyorganosiloxane compositions prepared in the examples were excellent in light shielding properties, as well as in insulating properties and stability.

Claims (6)

(A) For 100 parts by weight of polyorganosiloxane having two or more silicon functional groups in the molecule and having a viscosity at 23 ° C. of 0.02 to 1000 Pa · s,
(B) 0.5 to 15 parts by weight of a crosslinking agent,
(C) a curing catalyst 0.01 to 15 parts by weight, and (D) the particle size of 20μm or less, a nitrogen adsorption specific surface area of 200 meters ² / g or more, and, DBP oil absorption amount 100 cm ^3/100 g or less of carbon black 0 A room temperature-curable polyorganosiloxane composition containing 0.01 to 10 parts by weight. The component (D), wherein, wherein the particle size 10 to 20 [mu] m, a specific surface area by nitrogen adsorption at 200 to 500 m ² / g, and, DBP oil absorption amount is carbon black 40~100cm ³ / 100g Item 2. A room temperature-curable polyorganosiloxane composition according to Item 1.   The room temperature-curable polyorganosiloxane composition according to claim 1 or 2, wherein the component (D) is contained in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the component (A).   The room temperature-curable polyorganosiloxane composition according to any one of claims 1 to 3, wherein the inorganic filler is contained in an amount of 1 to 100 parts by weight per 100 parts by weight of the component (A).   The room temperature-curable polyorganosiloxane composition according to any one of claims 1 to 4, which is a room temperature-curable polyorganosiloxane composition for electric and electronic devices.   6. The room temperature curable polyorganosiloxane composition according to claim 5, which is a room temperature curable polyorganosiloxane composition for electrode / wiring coating.