JPS6348902B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyorganosiloxane composition that cures by relatively gentle heating and firmly adheres to various materials upon curing. A polyorganosiloxane composition that is cured by an addition reaction between an unsaturated group bonded to a silicon atom and a hydrogen atom bonded to a silicon atom is known as an addition reaction type silicone rubber. This addition reaction type polyorganosiloxane composition can be cured in a short time by heating, generates few byproducts during curing, and the cured product has excellent flame retardancy and electrical insulation properties. , has been applied in many fields. However, such conventionally known addition reaction type polyorganosiloxane compositions have had the disadvantage of poor adhesion to materials with which the composition is in contact during curing. Therefore, when used for potting, dipping, or coating electrical and electronic parts, only inferior moisture resistance and reliability can be obtained, and the range of use for these has been limited to some extent. Therefore, in order to improve the adhesiveness of this polyorganosiloxane composition,
It has been proposed to add various adhesion-imparting components. Examples of such components include, for example, a cohydrolyzate of vinyltrialkoxysilane and vinyltrichlorosilane (Japanese Patent Publication No. 47-36255), a silane or siloxane having an acryloxyalkyl group, and a peroxide (Japanese Patent Publication No. 48-36255). 16952), polyorganohydrodiene siloxane having an epoxy group and/or ester group (Japanese Patent Application Laid-Open No. 1983-39345), and all of them require relatively high heating temperatures to develop adhesive properties. It also adheres well to metals such as aluminum, stainless steel, and mild steel, but it also adheres well to plastics, especially engineering plastics that have become widely used in recent years, such as polycarbonate, polyphenylene oxide (PPO), and polybutylene terephthalate (PBT). , polyphenylene sulfide (PPS), 6-nylon, etc., was a drawback. One of the inventors of the present invention previously proposed that at least one hydrogen atom bonded to a silicon atom is contained in the molecule as an adhesion-imparting component, and the formula ≡Si−Q ¹ −COO−Q ² −Si(OR) ₃ (formula (wherein, Q ¹ and Q ² are linear or molecular alkylene groups, and R is an alkyl group having 1 to 4 carbon atoms) is added. (Japanese Unexamined Patent Publication No. 54-48854). It is also proposed to use polyorganosiloxanes having at least two silicon-bonded alkenyl groups in the molecule, which have epoxy groups, ester groups, or trialkoxysilyl groups in their side chains. (Japanese Unexamined Patent Publication No. 54-58755 to 58757). Unlike the above materials, these compositions do not cure aluminum, even when cured at relatively low temperatures.
Shows good adhesion to metals such as stainless steel and mild steel. However, the adhesion to PPO and PPS in engineering plastics was still insufficient. Now, as a result of intensive studies on adhesion-imparting components, the present inventors have provided a polyorganosiloxane composition that solves these drawbacks by the present invention. That is, the present invention provides the following components (A) to (E), (A) general formula R ¹ _a R ² _b SiO{ _4-(a+b) } _/2 (wherein R ¹ is an alkenyl group, R ² is a substituted or unsubstituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, a is a number selected from 1 and 2, b is a number selected from 0, 1, and 2, and a+b
represents a number selected from 1, 2, and 3) 100 parts by weight of polyorganosiloxane having at least two units in the molecule (B) General formula R ³ _c H _d SiO{ _{4-(c+ d)} } _/2 (wherein R ₃ is a substituted or unsubstituted monovalent hydrocarbon group, c is a number selected from 0, 1 and 2,
d is a number selected from 1 and 2, and c+d is a number selected from 1, 2, and 3), and the molecule contains at least 2 hydrogen atoms bonded to silicon atoms. It has its own
The amount of hydrogen atoms bonded to silicon atoms is 0.5 per R ¹ in the polyorganosiloxane (A).
-5.0 polyorganohydrodiene siloxane (C) 0.1 to 20 parts by weight of an epoxy compound (D) 0.01 to 10 parts by weight of an organoaluminum compound (E) A catalytic amount of a platinum-based, palladium-based or rhodium-based compound The composition contains a polyorganosiloxane composition having adhesive properties. The polyorganosiloxane (A) used in the present invention has at least two alkenyl groups directly bonded to a silicon atom in one molecule. This polyorganosiloxane may be linear, branched, resin-like, or a mixture thereof, but chain-like polyorganosiloxane is preferable because it is easy to synthesize and provides an elastic adhesive. Polyorganosiloxanes are preferred. On the other hand, to obtain high strength, it is common to use resin-like polyorganosiloxane in combination. In the general formula above
Examples of R ¹ include a vinyl group, an allyl group, and a 1-butenyl group, but a vinyl group is preferred from the viewpoint of economy and ease of production. The organic groups bonded to the silicon atom of R ² and other siloxy units include alkyl groups such as methyl, ethyl, and propyl, aryl groups such as phenyl, chloromethyl, 3,3,3-tri A fluoropropyl group is preferred, and a methyl group is particularly preferred from the viewpoint of economy and ease of production. In component (A), the above formula R ¹ _a
The unit represented by R ² _b SiO{ _4-(a+b) } _/2 (in the formula, R ¹ , R ² , a, and b are as described above) is the unit at the end or middle of the molecular chain of polyorganosiloxane. Although it may be present in either or both, it is preferably present at least at the ends in order to impart excellent mechanical properties to the cured composition. In addition, in order to use the composition for potting, coating, adhesion, etc., the viscosity at 25°C must be 10 to 10.
Preferably it is 500,000 cP, especially 100-100,000 cP. The polyorganohydrodiene siloxane as the component (B) used in the present invention undergoes an addition reaction with the alkenyl group of the component (A) in the presence of an addition reaction catalyst described later to cure the composition of the present invention. It is an essential ingredient of This (B) component has Si-
As long as it has two or more H bonds, there is no particular restriction on its molecular structure, and conventionally known linear, cyclic, or branched structures may be used; however, from the viewpoint of ease of synthesis, linear or R Polyorganohydrodiene siloxanes consisting of ³² HSiO _1/2 units and SiO ₂ units are preferred _. Examples of the organic group bonded to the silicon atom of R ³ and other siloxy units include alkyl groups such as methyl group and ethyl group, and aryl groups such as phenyl group. Alternatively, a phenyl group is preferable, and a methyl group is more preferable from the viewpoint of economy and ease of production. The amount of component (B) to be used is such that the number of hydrogen atoms bonded to silicon atoms is 0.5 to 5.0, preferably 0.7 to 3.0 per R ¹ of component (A), that is, one alkenyl group. . This is because if the number of hydrogen atoms is less than 0.5, no crosslinking occurs, and if the number exceeds 5.0, foaming is likely to occur during curing, and changes in physical properties (especially heat resistance) after curing become large. The epoxy compound as component (C) used in the present invention is a component used together with the aluminum compound as component (D) to impart excellent self-adhesive properties to the composition of the present invention. This epoxy compound has 1
Any compound having at least one epoxy group in its molecule may be used. Examples of such compounds include the following. In addition, in the following formula, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, and Bu represents a butyl group. These epoxy compounds are preferably epoxy group-containing alkoxysilanes because they are less irritating, especially glycidoxypropyltrialkoxysilane or 3,4-epoxycyclohexyltrialkoxysilane, which has good compatibility with component (A). Silanes are particularly preferred. Also preferred are epoxy compounds having unsaturated groups in the molecule that do not reduce the physical properties of the composition after curing. The amount of these epoxy compounds used is 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of component (A). This is because if it is less than 0.1 part by weight, sufficient adhesive strength cannot be obtained, and if it exceeds 20 parts by weight, the physical properties of the resulting cured product will be greatly reduced. The organoaluminum compound as component (D) used in the present invention is used together with the epoxy compound as component (C) for the purpose of imparting adhesive properties to the composition of the present invention. These include (MeO) ₃ Al, (EtO) ₃ Al, (n-
PrO) ₃ Aluminum alcoholates such as Al, aluminum salts such as naphthenic acid, stearic acid, octylic acid or benzoic acid, and aluminum alcoholates obtained by reacting with acetoacetic esters or dialkyl malonates, etc. Examples include aluminum chelates, organic acid salts of aluminum oxide, and aluminum acetylacetonate, but aluminum chelates or aluminum alcoholates are preferred from the viewpoint of hydrolyzability. Further, bisethylacetoacetate aluminum monoacetylacetonate or acetalkoxyaluminum diisopropylate is preferred because they are liquid and easy to handle. The amount of component (D) used is 0.01 per component (A).
~10 parts by weight, preferably 0.1 to 5 parts by weight.
If it is less than 0.01 part by weight, good adhesion cannot be obtained;
This is because if the amount exceeds parts by weight, the heat resistance will deteriorate. In addition, for the above (C) component, (C) component 100
The amount is preferably 1 to 50 parts by weight. The platinum-based, rhodium-based, or palladium-based compound used in the present invention as the component (E) is used as an addition reaction catalyst between the component (A) and the component (B) to cure the composition of the present invention. It is a catalyst. These include chloroplatinic acid, alcohol-modified chloroplatinic acid, complexes of platinum and olefins, complexes of platinum and ketones, complexes of platinum and vinyl siloxane, and platinum supported on a carrier such as alumina or silica. , platinum-based compounds such as platinum black, palladium-based compounds such as tetrakis(triphenylphosphine)palladium, a mixture of palladium black and triphenylphosphine, or rhodium-based compounds. This component (E) is used in the amount necessary as a catalyst, and this amount is in the range of 0.1 to 1000 ppm in terms of the amount of each element of platinum, palladium, and rhodium relative to component (A),
Preferably it is in the range of 0.5 to 200 ppm. 0.1ppm
If it is less than that, the catalyst concentration will be low and the effect will be insufficient. On the other hand, component (E) contains precious metals and is generally expensive, so adding a large amount will be uneconomical.
Such a range is tentatively defined because there is no point in increasing the content more than 1000 ppm, and the heat resistance will further deteriorate. The composition of the present invention may contain fillers, pigments, heat resistance improvers, fungicides, etc. as necessary, and these include fumed silica, precipitated silica, quartz powder, diatom Earth, titanium oxide, aluminum oxide, zinc oxide, iron oxide, cerium oxide, mica, clay, carbon black, graphite,
Examples include calcium carbonate, zinc carbonate, manganese carbonate, cerium hydroxide, glass beads, and metal powder. Further, a solvent or other polyorganosiloxane may be used in combination or diluted within a range that does not impair the effects of the present invention. Addition reaction modifiers such as acetylene alcohol, allyl cyanurate, alkynyloxysilanes and siloxanes may also be used to increase the workability of the compositions of the invention. Examples of the present invention are shown below. As is clear from these examples, the composition of the present invention is cured by relatively gentle heating and exhibits good adhesion not only to metals but also to engineering plastics such as PPO and PBT. have Therefore, unlike conventional addition reaction type polyorganosiloxane compositions, it has a wide range of uses for various materials, and can be particularly preferably used as a coating agent for electrical and electronic parts. In addition, in the examples, all parts represent parts by weight. Example 1 Formula A polyorganosiloxane whose molecular chain ends are blocked with dimethylvinylsilyl groups (25℃
(viscosity at 500 cP), 100 parts of quartz powder with an average particle size of 10 μ, 0.1 part of an octanol solution of chloroplatinic acid containing 2% by weight of platinum and the formula To 100 parts of a base compound consisting of 5 parts of polyorganohydrodiene siloxane shown in Table 1, γ-glycidoxypropyltrimethoxysilane as an epoxy compound and bisethylacetoacetate aluminum monoacetylacetonate as an aluminum compound were added. Mix the indicated amount (parts), apply it on a PPO board, and heat it at 100℃.
It was heated for a period of time and its adhesion was examined. In addition, experiment No. 2,
3 and 4 are comparative examples. Example 2 A second compound was added to the base compound described in Example 1.
Add the epoxy compounds and aluminum compounds shown in the table in the amounts (parts) shown in Table 2, PBT board,
It was sandwiched between an Al plate and a PPO plate and heated at 100°C for 1 hour to examine its adhesion. However, Experiment No. 6, 8,
10 and 11 are comparative examples. Note that the evaluation of the adhesiveness results was the same as in Example 1.

[Table] ×: Easy to remove.

【table】

[Table] ｜
｜
｜／
(CH ₂ ) ₃ OCH ₂ CH−CH ₂
O
｜／
O

Claims (1)

[Claims] 1. The following components (A) to (E), that is, (A) general formula R ¹ _a R ² _b SiO{ _4-(a+b) } _/2 (wherein R ¹ is alkenyl group, R ² is a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, a is a number selected from 1 and 2, and b is a number selected from 0, 1 and 2. Yes, a+b
represents a number selected from 1, 2, and 3) 100 parts by weight of polyorganosiloxane having at least two units in the molecule (B) General formula R ³ _c H _d SiO{ _{4-(c+ d)} } _/2 (wherein R ³ is a substituted or unsubstituted monovalent hydrocarbon group, c is a number selected from 0, 1 and 2,
d is a number selected from 1 and 2, and c+d is a number selected from 1, 2, and 3), and the molecule contains at least 2 hydrogen atoms bonded to silicon atoms. Owned by
The amount of hydrogen atoms bonded to silicon atoms is 0.5 per R ¹ in the polyorganosiloxane (A).
-5.0 polyorganohydrodiene siloxane (C) 0.1 to 20 parts by weight of an epoxy compound (D) 0.01 to 10 parts by weight of an organoaluminum compound (E) A catalytic amount of a platinum-based, palladium-based or rhodium-based compound A polyorganosiloxane composition having adhesive properties. 2. The composition according to claim 1, wherein R ¹ in (A) is a vinyl group. 3 The polyorganosiloxane (A) has the general formula The composition according to claim ² , which is a polyorganosiloxane represented by the formula (wherein R2 is a number from 20 to 5000, as described above). 4 (A) The polyorganosiloxane has the general formula The composition according to claim 3, which is a polyorganosiloxane represented by the formula (wherein n is as described above). 5 (B) The polyorganohydrodiene siloxane has the general formula (In the formula, R ⁴ is a hydrogen atom or a methyl group, p is 0
~100 (However, when R ⁴ is a methyl group, p is 2 ~
100), q is a number from 0 to 100), and q is a number from 0 to 100. 6. The composition according to claim 1, wherein the polyorganohydrodiene siloxane (B) comprises (CH ₃ ) ₂ HSiO _1/2 units and SiO ₂ units. 7. The composition according to any one of claims 1 to 6, wherein the epoxy compound (C) is an epoxy group-containing alkoxysilane. 8 The epoxy compound (C) is 8. The composition according to claim 7, which is an epoxy compound represented by the formula (wherein R ⁵ represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond). 9. The epoxy compound of (C) is The composition according to claim 7, which is an epoxy compound represented by the formula (wherein R ⁵ is as described above). 10. The composition according to any one of claims 1 to 6, wherein the epoxy compound (C) is an epoxy compound having an unsaturated group in its molecule. 11. The composition according to any one of claims 1 to 10, wherein the aluminum compound (D) is an aluminum chelate or an aluminum alcoholate. 12. The composition according to claim 11, wherein the aluminum compound (D) is an aluminum chelate. 13. The composition according to claim 12, wherein the aluminum compound (D) is bisethylacetoacetate aluminum monoacetylacetonate. 14. The composition according to claim 12, wherein the aluminum compound (D) is acetalkoxyaluminum diisopropylate.