JPH0218452A - Adhesive polyorganosiloxane composition - Google Patents

Abstract

PURPOSE:To provide an adhesive polyorganosiloxane composition containing nitrile group-containing compound as an additive, curable in a short time by heating for a short time at a relatively low temperature and exhibiting remarkably improved development of the adhesivitiy. CONSTITUTION:The objective composition is produced by compounding (A) 100pts.wt. of a polyorganosiloxane containing >=2 units of formula I [R<1> is alkenyl; R<2> is univalent hydrocarbon group free from aliphatic unsaturated bond; etc.] in one molecule with (B) a polyorganohydrogensiloxane containing the unit of formula II [R<3> is (substituted)univalent hydrocarbon group; etc.] (the number of Si-bonded hydrogen atoms in the component B is 0.5-4 based on one R<1> group in the component A), (C) 0.1-20pts.wt. of an organic silicon compound selected from e.g. organic silicon compound of formula III (Q<1> and Q<2> are alkylene; R<4> is 1-4C alkyl) containing one or more Si-bonded hydrogen atoms in one molecule and (D) 0.1-500ppm (in terms of metal based on A+B) of a platinum-based catalyst containing a compound having nitrile group.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application TI) The present invention relates to a polyorganosiloxane composition, and in particular, to a polyorganosiloxane composition that is cured by an addition reaction upon heating. The present invention relates to a polyorganosiloxane composition with improved adhesive properties.

(Prior Art and Problems to be Solved by the Invention) Conventional addition reaction type siloxane compositions usually include an alkenyl group-containing polyorganosiloxane, a polyorganohydrodiene siloxane having a hydrogen atom bonded to a silicon atom, and an addition reaction type siloxane composition. Consists of a catalyst. When the composition is heated, an addition reaction occurs between the alkenyl group and the hydrosilyl group, resulting in a silicone rubber which is a cured product. At this time, the composition has characteristics such as not producing reaction by-products during curing and curing uniformly to the inside, and also has excellent heat resistance and electrical insulation properties, so it is electrically - Widely used, mainly for botting and coating of electronic parts.

However, since the silicone rubber obtained from the above-mentioned siloxane composition does not have adhesive properties, when the composition is used for potting electrical/electronic parts, the gap between the part and the silicone rubber may be removed. Moisture invades
This has the drawback of causing corrosion of parts and poor insulation. Therefore, attempts have been made to impart adhesiveness to the resulting silicone rubber by adding various compounds to the above-mentioned siloxane composition. As such a method, silicon atoms are added as a third component to so-called addition-reactive silicone rubbers, which are cured by crosslinking through an addition reaction between a vinyl group-containing polyorganosiloxane and a hydrosilyl group-containing polyorganosiloxane. Addition of polysiloxane having a bonded hydrogen atom and a trialkoxysilylalkyl group (Japanese Unexamined Patent Publication No. 4
8-16952), silanes or siloxanes having acryloxyalkyl groups and organic peroxides (see JP-A-50-26855), epoxy groups and/or ester groups on silicon atoms, and silicon Addition of polysiloxane having a hydrogen atom directly connected to an atom (see JP-A-50-39345)
However, none of them have shown sufficient self-adhesiveness to the various base materials used in electric fist electronic parts.

In order to improve these disadvantages, a method has been proposed in which a polyorganosiloxane composition having an oxysilane group, a trialkoxysilyl group, and a hydrosilyl group is used as the third component (see JP-A-53-33256). In order to obtain curability and self-adhesiveness when heated at a low temperature around 70°C, as a third component, msi -Q"-C-0-Ql-Si-(OR')3
(m) an organosilicon compound having a group represented by the formula (in the formula, Ql and Ql represent a linear or branched fullkylene group, and R4 represents an alkyl group having 1 to 4 carbon atoms) and a hydrosilyl group; A composition has been proposed that has excellent adhesive properties even when heated at a low temperature of 70° C. (see Japanese Patent Laid-Open No. 48853/1983).

Addition-reactive polyorganosiloxane compositions with excellent adhesive properties have been obtained using these methods, but recent applications in electrical and electronic components require compositions that develop adhesive properties in a shorter time. ing. One way to solve this problem is to increase the amount of platinum-based compounds used in the catalyst, but if the amount is increased beyond an appropriate amount, not only will it not be possible to accelerate curing, but also the electrical There is a problem in that it has an adverse effect on mechanical properties and the like.

It is an object of the present invention to solve the problems of the prior art and to provide an addition reaction type polyorganosiloxane composition that exhibits rapid self-adhesive properties.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors have developed a method containing a nitrile group as an additive for an addition reaction type polyorganosiloxane composition. The inventors have discovered that the development of adhesive properties can be significantly improved by using a compound that provides the following properties, and has thus arrived at the present invention.

Specifically, the self-adhesive polyorganosiloxane composition of the present invention has the following formula: Represents an unsubstituted monovalent hydrocarbon group; a represents 1 or 2; b represents 0, l or 2; a+b represents 1.2 or 3) at least 2 units in the molecule. 100 parts of polyorganosiloxane having: (B) General formula (■): (R3). HdSiO Shikou (II) (in the formula, R3
represents a substituted or unsubstituted monovalent hydrocarbon group; C is 0.
1 or 2; d represents 1 or 2; C÷d represents 1, 2 or 3). (C) one or more types of organosilicon selected from the group consisting of (a) to (C); Compound, 0.1 to 20 parts by weight (a) at least one hydrogen atom bonded to a silicon atom in the molecule;
General formula (■): “5i-Q”-C-OQ2-3i (OR')!
(m).

(In the formula, Ql and Ql represent a linear or branched alkylene group, and R4 represents an alkyl group having 1 to 4 carbon atoms); (b) an alkoxy group bonded to a silicon atom; Organosilicon compound having at least two epoxy groups in the molecule and at least one epoxy group in the molecule: (C) At least one alkoxy group bonded to a silicon atom in the molecule and an unsaturated double bond in the molecule and (D) a platinum-based catalyst, consisting of 0.1 to 500 ppm as a metal based on the total amount of components (A) and (B);
D) is (d) a mixture of one or more selected from platinum-based metals and platinum-based compounds and a compound having a nitrile group; and/or (e) an organic compound having at least one nitrile group in the molecule. A platinum-based compound coordinated with

The polyorganosiloxane as component (A) used in the present invention has a unit represented by the above general formula (I) in its molecule, and its structure may be linear or branched, and A mixture of these may be used.

Examples of the alkenyl group represented by R1 in the general formula (I) include a vinyl group, an allyl group, a l-butenyl group, a l-hexenyl group, and a vinyl group is most advantageous due to ease of synthesis. .

In addition to R2, a substituted or unsubstituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond and Hi, Hz, organic groups bonded to the silicon atom of the siloxane unit include methyl group, ethyl group, propyl group, butyl group. , an alkyl group such as a hexyl group or a dodecyl group; an aryl group such as a phenyl group;
Examples include aralkyl groups such as 2-phenylethyl group and 2-phenylpropyl group, and furthermore, chloromethyl group,
Substituted hydrocarbon groups such as 3,3.3-)lifluoropropyl group are also exemplified. Among these, synthesis is easy;
Furthermore, the methyl group is most preferred because it has the degree of polymerization of the polyorganosiloxane necessary to maintain good mechanical properties after curing and maintains a low viscosity before curing.

In addition, in order for the composition to have properties suitable for use in botting, coating, impregnation, etc., in particular adequate flowability before curing, and excellent mechanical properties after curing, it is necessary to The viscosity is 50-100.0
OOcP, preferably 100-10.000cP
It is. When the viscosity is 50 cP, sufficient elongation and elasticity cannot be obtained after curing, and when it exceeds 100,000 cP, workability in casting, botting, and other operations is significantly reduced. However, when used as an adhesive that is cured at room temperature, there is no problem even if the adhesive has a high viscosity exceeding 100.000 cP.

The polyorganohydrodiene siloxane as the component CB) used in the present invention has the unit represented by the above-mentioned (II), and in order to give the composition a network structure by crosslinking, hydrogen bonded to silicon atoms is added. It is necessary to have at least 3 atoms.

The substituted or unsubstituted monovalent hydrocarbon group bonded to the silicon atom of the R3 and other siloxane units in the above-mentioned -Siloxane (II) are the same as R2 in the general formula (I) in the above-mentioned component (A). Among them, a methyl group is most preferred because it is easy to synthesize.

The structure of such polyorganohydrodiene siloxane may be linear, branched or cyclic, or a mixture thereof,
In particular, the following compounds (1) to (2) are preferred.

(D (CH3)2 Consists of R31oy2 units and 5 groups 02 units, and the content of hydrogen atoms bonded to silicon atoms is 0
．． Branched polyorganohydrodiene siloxane ranging from 3 to 1.2% by weight.

■It is represented by the general formula (where p is 3 to 100 and q is a number from θ to 10o), and the content of hydrogen atoms bonded to silicon atoms is in the range of 0.5 to 1.6% by weight. Straight-chain polyorganoturodiene siloxane.

■It is represented by the general formula (where p is a number from 1 to 100 and q is a number from 0 to 100), and the content of hydrogen atoms bonded to silicon atoms is in the range of 0.5 to 1.6% by weight. Straight-chain polyorganoturodiene siloxane.

The amount of component CB) is such that the number of silicon-bonded hydrogen atoms in component (B) is 0.5 to 4.0 per R1 group in component (A). , preferably 1.0
The amount is such that there will be ~3.0 pieces. If the amount of component (B) is too small than the above amount, the curing of the composition will not proceed sufficiently and the hardness of the cured composition will be low; if it is too large, the hardness of the cured composition will be The mechanical properties and heat resistance of objects decrease.

The organosilicon compound as component (C) used in the present invention is 1
This component contributes to imparting self-adhesive properties to the composition of the present invention.

Component (C) is one or more selected from the group consisting of components (a), (b), and (C).

The organosilicon compound of component (a) is usually a silane derivative or a polysiloxane derivative, but for ease of synthesis, the 5i-H bond and the group represented by -siloxane (m) are separated into separate siloxane units. In this case, Ql is preferably a hydrocarbon group consisting of a carbon chain having 2 or more carbon atoms, especially a compound having the general formula :
-CH2CH- (in the formula, R6 represents a hydrogen atom or a methyl group) is preferable, and Q2 is, from the viewpoint of hydrolysis resistance,
A hydrocarbon group consisting of a carbon chain having 3 or more carbon atoms, particularly a propylene group, is preferable.As the alkyl group having 1 to 4 carbon atoms for R4 in -carboxylation (m), methyl group, ethyl group, propyl group, etc. Among these, methyl and ethyl groups are preferred because the composition exhibits good adhesion.Siloxane units containing such side chains are It can be synthesized by a method such as adding trialkoxysilylpropyl ester of acrylic acid or methacrylic acid to a part of the 5i-H bond. The siloxane skeleton of such an organosilicon compound may be cyclic, chain, or a mixture thereof, but it is most preferable to have a cyclic polysiloxane skeleton for ease of synthesis. Therefore, the number of silicon atoms forming the siloxane ring is 3 to 6, preferably 4. In the case of a m-shaped siloxane chain, a siloxane chain having 2 to 20 silicon atoms, preferably 4 to 10 silicon atoms is used, since a large molecular weight increases the viscosity and makes synthesis and handling inconvenient.

The organosilicon compound of component (b) is an alkoxysilane or siloxane containing an epoxy group, and it is more preferable that the number of alkoxy groups bonded to the silicon atom is 3 or more in order to improve the adhesion to the base material. , such compounds include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane. Toxicilla (O
Examples include siloxanes such as CH3)2.

The organosilicon compound of component (C) is an alkoxysilane or siloxane having an unsaturated double bond, and in order to improve the adhesion to the substrate, it is necessary to have three or more alkoxy groups bonded to the silicon atom. More preferred examples of unsaturated double bonds include fluorenyl groups such as vinyl and allyl groups; groups such as 7-acryloyl, methacryloyl, acryloxypropyl, and methacryloxypropyl groups. Examples of such organosilicon compounds include vinyltrimethoxysilane, vinyltriethoxysilane, and γ-
Examples include methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, silanes represented by the following formula, and hydrolyzed condensates thereof.

These organosilicon compounds as components (a), (b), and (C) are all useful as adhesion-imparting agents for addition reaction type compositions, and can be used alone, but they can be used more easily with the base material. In order to improve adhesion, (a), (
It is preferable to use two or more, preferably three, of components b) and (C) in combination.

The blending amount of component (C) is 1 to 10 parts by weight per 100 parts by weight of component (A). If the amount is less than 1 part by weight, sufficient adhesive strength will not be obtained, and if it exceeds 10 parts by weight, the mechanical properties of the cured elastic body will deteriorate.

The platinum-based catalyst as component (D) used in the present invention is one or two selected from (d) platinum-based metals and platinum-based compounds.
A mixture of one or more species and a compound having a nitrile group and/or
or (e) a platinum-based compound in which an organic compound having at least one nitrile group is coordinated in the molecule.

Here, platinum-based metals constituting component (d) include simple platinum (platinum black), simple palladium (palladium black),
An example is rhodium alone. In addition, platinum-based compounds include chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum-ketone complexes, platinum-vinylsiloxane complexes, tetrakis(triphenylphosphine)platinum, tetrakis(triphenylphosphine)platinum, Examples include palladium (phosphine). Among these, it is preferable to use chloroplatinic acid or a platinum-olefin complex dissolved in an alcohol solvent, a ketone solvent, an ether solvent, a hydrocarbon solvent, etc.; It is necessary to grind finely to improve the
The carrier used also preferably has a small particle size and a large specific surface area.

The compound having a nitrile group constituting component (d) is a component that contributes to significantly promoting the development of adhesive properties of the composition of the present invention.

Examples of compounds having a nitrile group include acrylonitrile, acetonitrile, adiponitrile, isobutyronitrile, benzonitrile, and isovaleronitrile.

For convenience of use, compounds with nitrile groups must be liquid at room temperature and have a boiling point that is not too low (
It satisfies conditions such as having a boiling point higher than room temperature), having no reactive functional groups in the molecule (because this functional group acts as a reaction retardant), and being stable against heat and light. Examples of compounds having a nitrile group that satisfy these conditions include acetonitrile (melting point: 45.72°C, boiling point: 81.77°C), isobutyronitrile (melting point: 71.50°C, boiling point: 103.8°C)
5℃), bezonitrile (melting point: 13.20℃, boiling point:
191.10°C).

(e) A platinum-based compound in which an organic compound having at least one nitrile group is coordinated in the molecule constituting the component.

P L (PhCN) 2 CJ12, Pt (Ph
CN) 2 Br2, Pd (PhCN) 2 C12
, Pd (PhCN) 2 Br2, and the like.

The blending amount of component (D) is 0.1 to 500 ppm as the amount of platinum atoms and 0.1 to 1000 PPII as the amount of the organic compound having a nitrile group relative to component (A).

If the amount of platinum atoms is less than 0.1 ppm, the curing of the composition will be insufficient, while if it exceeds 500 ppm, it will have a negative effect on the mechanical properties after curing. is 0.3 to 200 pp■.

If the amount of the organic compound having a nitrile group is 0.1 ppm without swirling, the curing inhibiting effect at room temperature will not be exhibited, and if it exceeds 11,000 pp, curing will be insufficient. The amount of organic compound having a nitrile group is preferably 0.
3 to 200 ppm.

The composition of the present invention consists of each component (A) to (D), and if necessary, by further adding an inorganic filler, the composition has flowability suitable for its use, hardness after curing, It can provide tensile strength, elongation, modulus, etc. Such inorganic fillers are typically fumed silica, silica aerogel, precipitated silica, ground silica, diatomaceous earth, iron oxide.

Examples include zinc oxide, titanium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, and carbon black.

The amount of these fillers to be used is not limited as long as it does not impair the purpose of the present invention, and if necessary, suitable pigments, dyes,
Adhesion aids, fungicides, heat resistance improvers, flame retardants or antioxidants can be added. Furthermore, when carrying out the present invention, the composition of the present invention may be used after being dispersed or dissolved in a suitable organic solvent such as toluene or xylene, depending on the use.

When storing the composition of the present invention, it is preferable to store a portion of component (A) and component (D), and the remainder of component (A) and components (B) and (C) separately.

[Effects of the Invention] The polyorganosiloxane composition of the present invention is cured by heating at a relatively low temperature and for a short time, and exhibits adhesive properties. Therefore, the compositions of the present invention are useful as adhesives for plastics to which high temperatures cannot be applied. Furthermore, the cured product formed by heating exhibits excellent adhesion to the base material, and will not peel off from the base material even when left in high temperature and high humidity conditions or in hot water for a long time.

(Example) The present invention will be explained below with reference to Examples. In addition.

In the examples, all parts indicate parts by weight, and all viscosity means the viscosity at 25°C.

In addition, in the examples, compounds of formulas (a) to (c) were used.

CH3CH3 (a) CH2CH2-0 (CHz) s Si (OCH
3) s\ 1 0
(b) CH2= CH-S i (OC2H5)
s (c) Examples 1 to 3 72 parts of polydimethylsiloxane with a viscosity of 3000 cP and both molecular chain ends blocked with dimethylvinylsilyl groups, CC
Hs) 18 parts of polyorganosiloxane consisting of 37 mol% of Jsio unit, 56 mol% of 5i02 unit and 7 mol% of (CH2=CH)CH3S to unit, both molecular chain ends are capped with trimethylsilyl group, (CH3)2S
10 parts 2 units 42 mol%, (CH3)H3iO local units 58 mol% polymethylhydrodiene siloxane with a viscosity of 20 cP 4 parts, 120 parts of ground silica with a particle size of 5 IL,
10 parts of fumed silica surface-treated with silazane, 4 parts of an organosilicon compound having a hydrogen atom bonded to a silicon atom and represented by the above formula (a), and 1 part of an unsaturated group-containing alkoxysilane represented by the above formula (b). , 1 part of an epoxy group-containing alkoxysilane represented by the above formula (c), 0.1 part of an n-hexanol solution of chloroplatinic acid containing 3.5% platinum, [(C
H2 Engineering CH) CH3S f O] 40, 04 parts and CHs (CH3)CHCH2CCCHs) (OH)
1 part of c=cHO00 was mixed uniformly to obtain a base composition. To 240 parts of this base m acid, 0.44 parts of a benzonitrile solution diluted with xylene, 0.18 parts of an acetonitrile solution diluted to 1% with xylene, and 1% diethylene glycol dimethyl ether of chloroplatinic acid coordinated with benzonitrile. 0.81 part of each solution was added and mixed thoroughly to obtain the compositions of Examples 1-3. Note that a composition containing only the base composition was used as a comparative composition.

Next, a test for adhesive strength was conducted. First, each of the above-obtained compositions was poured between two aluminum plates or polybutylene terephthalate resin plates.Then, in the case of aluminum plates, the compositions were poured into a circulating hardening furnace.
For polybutylene terephthalate resin plates, cured by heating at 0℃ for 6 minutes or 60 minutes, at 100℃ for 10 minutes.
The test pieces were prepared by heating and curing for 60 minutes or 60 minutes, respectively.

For each test device obtained, two aluminum plates or polybutylene terephthalate resin plates were placed at ia
The shear adhesive strength was measured by pulling in the "o" direction. The cohesive failure rate was also tested. The results are shown in the table.

Claims (1)

[Claims] (A) General formula (I): (R^1)_a(R^2)_bSiO_{_4_-_(
_a_+_b_)_}_/_2(I) (in the formula, R^1
represents an alkenyl group; R^2 represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond; a represents 1 or 2; b represents 0, 1 or 2; a+b
100 parts by weight of a polyorganosiloxane having at least two units represented by 1, 2 or 3 in the molecule; (B) General formula (II): (R^3)_cH_dSiO_{_4_-_(_c_+
_d_)_}_/_2(II) (wherein, R^3 represents a substituted or unsubstituted monovalent hydrocarbon group; c is 0, 1 or 2
d represents 1 or 2; c + d represents 1, 2 or 3). (C) one or more organosilicon compounds selected from the group consisting of (a) to (c), such that the amount of hydrogen atoms bonded to silicon atoms is 0.5 to 4.0; .1 to 20 parts by weight (a) at least one hydrogen atom bonded to a silicon atom in the molecule;
General formula (III): ▲Mathematical formulas, chemical formulas, tables, etc.▼(III) (In the formula, Q^1 and Q^2 represent linear or branched alkylene groups, and R^4 has a carbon number of 1 ~4 alkyl group); (b) an organosilicon compound having at least two alkoxy groups bonded to a silicon atom in the molecule and at least one epoxy group in the molecule; (c ) an organosilicon compound having at least one alkoxy group bonded to a silicon atom in the molecule and at least two unsaturated double bonds in the molecule; and (D) a platinum-based catalyst (A) component and (B) component. (D
) is (d) a mixture of one or more selected from platinum-based metals and platinum-based compounds and a compound having a nitrile group, and/or (e) an organic compound having at least one nitrile group in the molecule. A self-adhesive polyorganosiloxane composition comprising: a coordinated platinum-based compound.