JPS595219B2 - Polyorganosiloxane composition that can be cured into a rubbery state - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to self-adhesive silicone rubber compositions that cure at relatively low temperatures and adhere strongly to substrates such as metals and plastics without the use of primers.

Silicone rubbers that are cured by the reaction of hydrosilyl groups with vinyl groups bonded to silicon atoms are already well known.

This type of silicone rubber has excellent heat resistance and electrical insulation, and those containing fillers such as silica have self-extinguishing properties, so they are used for casting electrical and electronic parts. However, since silicone rubber does not have adhesive properties, when it is cast into electrical or electronic parts, moisture can enter through the gap between the parts and the silicone rubber, causing corrosion of the parts. It also had the disadvantage of causing poor insulation.

Therefore, various types of brimers have been developed to bond silicone rubber to such electric/electronic parts. However, using these primers is complicated because steps required for primer treatment and drying are added. Furthermore, since many primers use solvents such as toluene and isopropyl alcohol, consideration must be given to their flammability and toxicity. On the other hand, attempts have also been made to impart self-adhesive properties to silicone rubber by adding an appropriate third component to the raw material composition during curing of silicone rubber.

It is a type of room-temperature vulcanizable silicone rubber that is especially suitable for casting into electrical and electronic parts to form insulating and protective layers. Regarding the so-called addition-type cold-vulcanizable silicone rubber that cures by cross-linking molecular chains, the third component is (1) trimethylsiloxane units or dimethylsiloxane units and methylhydrogensiloxane units\Si-/(CH2 )x-
Si(0R) 8-containing unit (Tazoshi, x is 2 or 3, R
is added with a polysiloxane consisting of a group selected from methyl, ethyl and acetyl (Japanese Unexamined Patent Publication No. 48-16
952), (2) acryloxyalkyl group-containing silane or siloxane and organic peroxide added (JP-A-50-126855), (3) epoxy group or ester bonded to silicon atom via carbon atom There is a polysiloxane containing a hydrogen atom directly bonded to a group and a silicon atom (Japanese Unexamined Patent Publication No. 50-39345), but all of them have sufficient self-adhesion to various base materials used in electrical and electronic parts. It has not yet reached the point where it shows its gender.

In order to improve these disadvantages, the present inventors have previously developed a silicone rubber composition that is cured by a reaction between a hydroxyl group and a vinyl group bonded to a silicon atom, as a method of imparting self-adhesive properties to silicone rubber. By adding an unsaturated hydrocarbon compound having an oxirane group to,
It has been found that self-adhesive properties can be imparted.

According to this, silicone rubber that firmly adheres to base materials such as metals and plastics can be obtained by heating at relatively low temperatures and for a short time, but unsaturated hydrocarbon compounds with oxirane groups are different from organosiloxanes. There is almost no compatibility, and the resulting silicone rubber composition is translucent to opaque, and filling with silica etc. is a commonly used means to improve self-extinguishing properties. When a filler is added, this type of silicone rubber has the disadvantage that the self-extinguishing property that it inherently has due to the use of a platinum catalyst is significantly reduced by the presence of the filler. As a result of extensive research, the present inventors have discovered that an organopolysiloxane composition containing an oxirane group, a trialkoxysilyl group, and a hydrosilyl group in one molecule can be converted into an addition reaction type curable organopolysiloxane composition using a platinum catalyst. By adding
The present inventors have discovered that silicone rubber can have self-adhesive properties without impairing its excellent properties, and have completed the present invention.

That is, the present invention provides (self) general formula (wherein R1 is a group selected from a vinyl group and an allyl group,
R2 is a monovalent hydrocarbon group containing no aliphatic unsaturated bond, a
is a number selected from 0, 1, and 2, and b is a number selected from 0, 1, and 2.
100 parts by weight of a polyorganosiloxane having at least two R1 units in the molecule;
(B) General formula (in the formula, R3 is a monovalent hydrocarbon group containing no aliphatic unsaturated bond, c is a number selected from 0, 1 and 2, and d is a number selected from 0, 1 and 2) , c0d is a number selected from 1, 2, and 3), and a polyorganohydrodiene siloxane having at least three silicon-bonded hydrogen atoms in the molecule, in component (A) Rll of
0.5 to 4 hydrogen atoms bonded to silicon atoms for each component, (0 catalyst selected from platinum and platinum compounds, 1 to 100 P for component (4) as platinum,
(auto) (i) At least one siloxane unit in the molecule having a trialkoxysilyl group bonded to the silicon atom via R4 (Tamashi R4 is 2 selected from an alkylene group or an oxydimethylsilylalkylene group) At least one siloxane unit in the molecule has at least one siloxane unit having a monovalent hydrocarbon group having an oxirane oxygen atom, which is bonded to an octa(b) silicon atom representing a valent group via R5. (representing an alkylene group with/or without type oxygen)
(c) A polyorganosiloxane having at least one siloxane unit having a hydrogen atom directly bonded to a silicon atom in the molecule and having 1 to 10 parts by weight of a polyorganosiloxane that is compatible with the aαA component and can be cured into a rubbery state. A polyorganosiloxane composition is provided.

A polyorganosiloxane having a unit of general formula 1 used in the present invention (A has a vinyl group or an allyl group bonded to a silicon atom, and may be linear or branched, or a mixture thereof.

R1 in the above general formula is selected from a vinyl group and an allyl group, but from the viewpoint of ease of synthesis, a vinyl group is preferred. R2 is selected from monovalent hydrocarbon groups that do not contain an aliphatic unsaturated bond, but from the viewpoint of thermal stability and ease of synthesis, it is preferably a group selected from a methyl group and a phenyl group; More preferably, it is a methyl group. The viscosity of such polyorganosiloxane is 50
~1,000,000 centipoise is selected, but considering the working conditions of the composition, preferably 50 to 100,00 centipoise.
00 centipoise. General formula used in the present invention:
Organohydrodiene polysiloxane with units (
B may be linear, cyclic, or branched.

The number of hydrogen atoms bonded to silicon atoms must be at least three in a molecule; if the number is less than this, curing will not occur or curing will be extremely slow. As the monovalent hydrocarbon group R3, a methyl group,
Examples include ethyl group, propyl group, and phenyl group, but methyl group is preferred because of its chemical stability and ease of synthesis.

Further, the position of the silicon atom to which the hydrogen atom is bonded may be at the end or in the middle of the polysiloxane. The amount of component (B) to be used is 0.5 to 4 hydrogen atoms bonded to silicon atoms, preferably 1.5 to 4 hydrogen atoms per Rll in the prisoner component.
A good amount is 3 pieces. (C) used in the present invention
The components are catalysts for the addition reaction of vinyl or allyl groups with hydrosilyl groups, including platinum units adsorbed on holding carriers, H2PtCl6, NaHP
tCl6, KHPtCl6, Na2PtCl6, K2P
tCj6, ptcl4, ptCl2, H2ptcl4 and their crystal water adducts are used, and solutions of these compounds in alcohols or ethers, compounds containing these compounds and alcoholic hydroxyl groups or olefinic unsaturated groups A complex obtained from is used.
(The amount of 0 component used is 1 to 1 as platinum to the prisoner component.
100PP01 is preferably used in the range of 1 to 40 pIm. Component (D) used in the present invention is an essential component of the present invention that makes the polyorganosiloxane composition of the present invention self-adhesive.

This is a siloxane unit having at least one (a) trialkoxysilyl group bonded to a silicon atom via R4 in the molecule (R4 is as described above), and (b) a siloxane unit having a trialkoxysilyl group bonded to a silicon atom via R5. (3) A polyorganosiloxane having a siloxane unit having a hydrogen atom directly bonded to a silicon atom (R5 is as described above), and a monovalent hydrocarbon group having an oxirane oxygen atom, Those that are compatible with the component (self) are selected.

This is because if the compatibility between component (5) and component (self) is poor, sufficient self-adhesiveness cannot be obtained and the mechanical properties of the cured silicone rubber will deteriorate. The siloxane structure may be broken, linear, or branched, but in the case of a cyclic structure, one having 3 to 6, preferably 4 silicon atoms constituting the siloxane ring is used for ease of synthesis. In the case of a chain, there are no particular restrictions as long as it is compatible with component (4), but if the molecular weight is large, not only will the compatibility with the component be impaired, but the viscosity will become high, making it inconvenient for synthesis and handling. Therefore, 3 to 50 silicon atoms make up the siloxane chain,
Preferably between 5 and 20 are used. ([)
Even if the component polyorganosiloxane lacks any of the above-mentioned (a), (c), and (c) as its siloxane unit, sufficient self-adhesion cannot be obtained.

The (a) unit is essential because the (D component reacts with the (,A) component by the catalytic action of the (0 component) to form a part of the rubber-like elastic body during curing of the composition. The (c) unit and (c) unit increase the affinity with the adherend based on their carbon functionality and silicon functionality and contribute to adhesion, but their effects will be discussed in the examples below. YoV-JH(C
H3-2Si0-5-(diH3-H8lUJ, so that the number of moles of Si-H bonds in ensiloxane is equal to or less,
Can be easily synthesized.

Examples of the organosilicon compounds used include CH2=
CHSi(0CH3)3, CH2=CHSl(0C2H
5) 3,CH2-CHSi(0C3H7)5,CH2=
CHCH2Sl(0CH,)3,CH2=CH(0H3
)2S10Si(0C2H5)3, but when the number of carbon atoms in the alkoxy group exceeds 3, the adhesiveness tends to decrease. In addition, examples of the above oxirane compounds include ＼
/ υ *The silicone rubber composition according to the present invention has excellent heat resistance and electrical insulation properties, so it is suitable for electrical and
Can be used for casting and coating electronic parts.

Further, by adding 0.01 to 10 parts by weight of an ethylenically unsaturated isocyanurate such as triallyl isocyanurate to the silicone rubber composition of the present invention, the curing rate can be adjusted, and more desirably, the curing rate can be adjusted. At the same time, it improves adhesion.

Examples of the present invention are shown below along with comparative examples.

In the examples, all parts indicate parts by weight. Example 1
- general formula polyorganosiloxane (component a1), general formula ± (diH
3 no 251 U na 25! -(UH3-2 polymethylhydrodiene siloxane (component b1) Molecular formula d1 8 Si-H bonded polysiloxane (component D2)
), molecular formula Example 2 component AllOO part of Example 1, component Bll. Si-H bonded gold-containing polysiloxane (component D3) shown in Part 8
A chloroplatinic acid isopropyl alcohol solution (component C1) containing 1% by weight of platinum in terms of platinum atoms was blended in the proportions shown in Table 1 to obtain compositions 11 to 15.

However, components D2 and d3 do not correspond to the (own) components of the present invention, and components 12 to 15 are comparative examples. These compositions were cured by heating on an aluminum plate for 10°C, 3O minutes.

When the adhesion to the aluminum plate was measured, the results shown in Table 1 were obtained, demonstrating the effect of component d1, which is the additive of the present invention. Furthermore, when the adhesive properties of various synthetic resins were similarly investigated, the results shown in Table 2 were obtained, demonstrating that the composition 11 of the present invention had excellent adhesive properties.

Claims (1)

[Claims] 1 (A) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1 is a group selected from a vinyl group and an allyl group, and R^2 is an aliphatic unsaturated bond. monovalent hydrocarbons,
a is a number selected from 0, 1 and 2, b is a number selected from 0, 1 and 2, and a+b is a number selected from 1, 2 and 3), and the molecule contains a 100 parts by weight of polyorganosiloxane having at least two R^1s, (B) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^3 is a monovalent hydrocarbon that does not contain an aliphatic unsaturated bond. group, c is a number selected from 0, 1 and 2, d is 0, 1
and a number selected from 2, and c+d is a number selected from 1, 2, and 3), and a polyorganohydrodiene siloxane having at least 3 silicon-bonded hydrogen atoms in the molecule, (A) R^ in the ingredients
0.5 to 11 hydrogen atoms bonded to silicon atoms
(C) a catalyst selected from platinum and platinum compounds; platinum in an amount of 1 to 100 relative to component (A);
ppm, (D) (a) At least one siloxane unit in the molecule having a trialkoxysilyl group bonded to the silicon atom via R^4 (R^4 is an alkylene group or oxydimethylsilylalkylene) 2 selected from
(b) At least one siloxane unit in the molecule, which has a monovalent hydrocarbon group bonded to a silicon atom via R^5 and has an oxirane oxygen atom. (R^5 represents an alkylene group having/or having no ether type oxygen), (c) the component (A) having at least one siloxane unit having a hydrogen atom directly bonded to a silicon atom in the molecule; A rubber-curable polyorganosiloxane composition comprising 1 to 1.0 parts by weight of a polyorganosiloxane which is compatible with the polyorganosiloxane. 2 Polyorganosiloxane (A
) is the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. A composition according to scope 1. 3 Polyorganosiloxane (A
) is a polyorganosiloxane terminated with a vinyl group at both ends, represented by the general formula ▲A numerical formula, a chemical formula, a table, etc.▼ (wherein n is as described above). 4 General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Polyorganohydrodiene siloxane (B) having units represented by the general formula ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (In the formula, p is 3 to 100, q is expressed as 0-100),
The content of hydrogen atoms bonded to silicon atoms is 0.5 to 1.
A composition according to claim 1, wherein the composition is 6% by weight polymethylhydrodiene siloxane. 5 General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Polyorganohydrodiene siloxane (B) has a unit represented by the general formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, r is 1 to 50. (s is an integer from 0 to 50), and the content of hydrogen atoms bonded to silicon atoms is 0.
5 to 1.6% by weight of polymethylhydrodiene siloxane. 6 Polyorganosiloxane (D) has the formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^a is -CH_2CH_2Si(OC_2H_
5)_3, -CH_2-CH_2Si(OCH_3)_
3 or -CH_2CH_2CH_2Si(OC_2H
＿５）＿３, and R^b is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼ where e is 0 or 1, f is 1 or 2, g is 1 or 2, e+f+g is 2
or 3, e+f+g+h is 4). 7 Polyorganosiloxane (D) has the formula (CH_3)_3SiO-[(CH_3)_2SiO]
_t [(CH_3)HSiO]_u-[(CH_3)R
^aSiO〕_v-[(CH_3)R^bSiO〕_w
-Si(CH_3)_3 (in the formula, R^a and R^b are the same as in item 6, t is an integer of 0 or 1 or more, and u, v, and w are integers of 1 or more). A composition according to claim 1. 8 General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Polyorganohydrodiene siloxane (B) having units represented by (CH_3)_2HSiO_0_
．． The composition according to claim 1, which is a polymethylhydrodiene siloxane consisting of _5 units and SiO_2 units and having a content of hydrogen atoms bonded to silicon atoms of 0.3 to 1.2% by weight. .