JPS61159450A - Polyorganosiloxane composition - Google Patents

Abstract

PURPOSE:To make it possible to decrease the compression set in curing and to increase hardness by forming a composition comprising a polyorganosiloxane, polyorganohydrogensiloxane, a platinum catalyst and polymethylsilsesquioxane as a filler. CONSTITUTION:A composition formed from 100pts.wt. polyorganosiloxane (A) having at least two units of formula I (wherein R' is an alkenyl group, R<2> is an aliphatic unsaturation-free (substituted) monovalent hydrocarbon group, (a) is 1 or 2, (b) is 0-2 and (a)+(b)=1-3) in the molecule, a polyorgano hydrogensiloxane (B) having units of formula II (wherein R<3> is R<2> in formula I, (c) is 0-2, (d) is 1 or 2 and (c)+(d)=1-3) and having at least three Si-bonded hydrogen atoms in the molecule in an amount to provide 0.5-4 Si-bonded hydro gen atoms per R' in A, 1-100ppm (in terms of Pt atoms), based on A, of plati num or its compound (C) and 0.5-300pts.wt. polymethylsilsequioxane (D).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a curable silicone rubber composition, and more specifically, a silicone rubber composition that cures at room temperature or by heating and has a low compression set; , relates to an addition reaction type liquid silicone rubber composition having excellent properties such as not having high viscosity or specific gravity.

[Technical background of the invention and its problems] An addition reaction type liquid silicone rubber composition is an addition reaction of a polyorganosiloxane having an alkenyl group and a polyorganohydrodiene siloxane having a hydrogen atom bonded to a silicon atom with a platinum compound or the like. It is a composition that is cured using a commercially available catalyst, and is already well known (Japanese Patent Publication No. 43
(Refer to Publication No.-27853, etc.). This composition has the advantage that there are no reaction products during curing, that the composition is uniformly cured to the inside, and that the curing time and workable time can be adjusted by adjusting the heating conditions. The resulting silicone rubber generally has excellent heat resistance and electrical insulation properties, and its mechanical strength is improved by adding fillers such as silica, and it is given various functions such as self-extinguishing properties by adding flame retardants. Because of this ability, it has been widely used, mainly as a botting material and coating material for electrical and electronic parts.

However, for these liquid silicone rubber compositions, although the obtained silicone rubber has a relatively low compression set and high hardness, it is difficult to increase the viscosity and specific gravity of the composition more than necessary. There are application requirements that cannot be met with fillers used in conventional liquid silicone rubber compositions, such as silica-based reinforcing fillers, semi-reinforcing fillers such as crystallite and celite, and their combinations. There was something.

[Purpose of the Invention] As a result of studying fillers for improving these properties, the present inventors have developed a method of hydrolyzing and condensing methyltrialkoxysilane or its partially hydrolyzed condensate in an aqueous solution of ammonia or amines. It has been found that by using the obtained polymethylsilsesquioxane as a filler, a polyorganosiloxane composition having excellent properties can be obtained.

The present invention was made based on the above knowledge, and maintains the original advantages of conventional liquid silicone rubber compositions,
Moreover, to provide a polyorganosiloxane composition in which the obtained silicone rubber has a low compression set, and although the composition has high hardness, the viscosity and specific gravity of the composition are not high, and excellent properties such as releasability are imparted. The purpose is

[Configuration 1 of the Invention That is, the polyorganosiloxane composition of the present invention comprises:
(A> General formula: %Formula%() (In the formula, R' is an alkenyl group, R2 is a substituted or unsubstituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and d
is an integer of 1 or 2, b is an integer of O to 2, and a+b is 1
Polyorganosiloxane having at least 2 units represented by the integer of ~3 in the molecule = 100 parts by weight (B) General formula: % formula % () (wherein R3 contains an aliphatic unsaturated bond (C is an integer of 0 to 2, d is an integer of 1 or 2, and C+d is an integer of 1 to 3), and Polyorganohydrodiene siloxane having at least three hydrogen atoms bonded to silicon atoms in one molecule: Polyorganosiloxane (
A) An amount such that the number of hydrogen atoms bonded to silicon atoms is 0.5 to 0.4 per R' in A) (C) A catalyst selected from the group consisting of platinum and platinum compounds: As a platinum atom. It is characterized by comprising 1 to 1100 pp of polyorganosiloxane (A) and 0.5 to 300 parts by weight of polymethylsilsesquioxane (D) having an average particle size of 0.1 to 100 μm.

The polyorganosiloxane (A>) used in the present invention is
It has at least two alkenyl groups in one molecule directly bonded to a silicon atom, and may be linear or branched, or may be a mixture thereof. R1 in the above formula
Examples include vinyl group, allyl group, 1-butenyl group, 2-
Examples include hexenyl groups, but vinyl groups are most advantageous due to ease of synthesis. Examples of organic groups bonded to the silicon atom of R2 and other siloxane units include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups, aryl groups such as phenyl, and β-phenyl. Examples include aralkyl groups such as ethyl group and β-phenylpropyl group, and further examples include substituted hydrocarbon groups such as chloromethyl group and 3,3,3-trifluoropropyl group. Among these, it is easy to synthesize and maintains good physical properties after curing.
A methyl group is most preferred because it has a low viscosity before curing.

The unit represented by the formula (I>) may be present at either the end or the middle of the molecular chain of the polyorganosiloxane, or both, but the composition after curing has excellent mechanical properties. In order to have this, it is preferable that it be present at least at the end.

In addition, when the composition is used for casting, botting, coating, impregnation, etc., it has properties suitable for this purpose, especially appropriate flowability before curing, and excellent physical properties after curing. The viscosity at 25°C is 5.
0~500. (100 c P, especially 100 to 100,
It is preferably in the range of 000cP. Viscosity is 50
If it is less than cP, sufficient elongation and elasticity will not be obtained after curing,
This is because if the viscosity exceeds 500.0 OOcP, workability in casting, botting, and other operations will be significantly impaired. Note that when used as an adhesive that cures at room temperature, there is no problem with using a high viscosity of 10,0OOCP or more, but in the case of an adhesive that cures at high temperature, the viscosity must be 10,0OOCP or less. It is preferable for improving sexual performance. Further, in the case of LIM molding (liquid injection molding), there is almost no problem even if the viscosity is 100.0OOCR or more.

The polyorganohydrodiene disiloxane used in the present invention as component (8) needs to have at least three hydrogen atoms bonded to silicon atoms in the molecule in order to form a network through crosslinking. As the organic group bonded to the silicon atom of R3 and other siloxy units, the same ones as R2 in the above-mentioned (A> component) are exemplified, but a methyl group is most preferable from the viewpoint of easy synthesis. The polyorganohydrodienedisiloxane may be linear, branched or cyclic (it may also be a mixture thereof).

As component (B), the compounds shown in the following a to C are preferred in that they provide good physical properties to the cured composition.

a, (CH3)2 H8iox unit and SiO2 unit, the content of hydrogen atoms bonded to silicon atoms is 0.3
~1.2% by weight of branched polyorganohydrodiene siloxa represented by the following formula (where p is an integer of 3 to 100 and q is an integer of θ to 100), and is bonded to a silicon atom. A linear polyorganohydrodiene siloxane C0-order formula in which the content of hydrogen atoms is in the range of 0.5 to 1.6% by weight (where p is an integer of 1 to 100, and q is an integer of O to 100). The amount of the linear polyorganohydrodiene siloxane (B) component, represented by Alkenyl group in component 1
The amount is such that the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 4.0, preferably 1.0 to 3.0. If the number of hydrogen atoms is less than 0.5, the curing of the composition will not proceed sufficiently and the hardness of the composition after curing will be low, and if the number of hydrogen atoms exceeds 4.0, the composition after curing will deteriorate. The physical properties and heat resistance of objects decrease.

The platinum-based catalyst as component (C) used in the present invention is (A)
It promotes the addition reaction between the alkenyl group of the component and the hydrosilyl group of the component (B), and is suitable for simple platinum, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum-phosphorus complexes, platinum coordination. Examples include compounds. (C
> The amount of the component used is (A> component, 1 platinum atom)
~1100pp. If it is less than lppm, the effect of the present invention cannot be achieved, and if it exceeds tooppm, no improvement in the curing speed can be expected.

Component (D) polymethylsilsesquioxane used in the present invention is a reinforcing agent and/or a mold release improving agent for silicone rubber. This filler has a lower specific gravity when compounded than other silica-based fillers with similar average particle sizes, such as crushed quartz and diatomaceous earth, so even when filled in large quantities, the specific gravity of the system is low. It does not become very high, and the system has little increase in viscosity and is highly fluid. Polymethylsilsesquioxane is obtained by hydrolyzing and condensing methyltrialkoxysilane or its hydrolyzed and condensed products in an aqueous solution of ammonia or amines, and contains chlorine atoms, alkaline earth metals, and alkali metals. It is preferable because it has almost no impurities such as, is spherical, and has excellent free-flowing properties. The average particle diameter of polymethylsilsesquioxane is 0.1 to 100 μm, preferably 0.1 to 20 μm. If the thickness is less than 0.1 μm, it is difficult to manufacture and it is difficult to fill it with more than necessary. If it exceeds 100 μm, the necessary reinforcing effect cannot be obtained and the function necessary for the present invention cannot be obtained.

In addition, the blending amount is 0.5 to 300 parts by weight, preferably 0.5 to 200 parts by weight, based on 100 parts by weight of polyorganosiloxane (A> component. If it is less than 0.5 parts by weight, mold release No effect can be obtained, and if it exceeds 300 parts by weight, it will be difficult to incorporate into the system, and the elasticity of the rubber after curing will be poor, not only will the reinforcing effect be lost, but the mechanical properties will deteriorate.

The composition of the present invention may optionally contain fillers other than polymethylsilsesquioxane, pigments, heat resistance improvers, adhesion aids,
Flame retardants, fungicides, etc. may be added as needed, and depending on the purpose, a solvent may be used in combination, or other polyorganosiloxanes may be used in combination without impairing the effects of the present invention. . Such additives typically include fumed silica, precipitated silica, quartz powder, diatomaceous earth, titanium oxide, aluminum oxide, zinc oxide, iron oxide, cerium oxide, mica, clay, carbon black, and graphite. , calcium carbonate, zinc carbonate, manganese carbonate, cerium hydroxide, glass peas, metal powder, toluene, hexane,
Examples include polydimethylsiloxane and alkenyl group-containing polysiloxane.

[Examples of the Invention] The present invention will be described below with reference to Examples. In the examples, all parts indicate parts by weight. Note that these Examples do not limit the present invention.

First, polymethylsilsesquioxane was synthesized by the method shown below.

Reference Example 1 Polymethylsilsesquioxane was synthesized by hydrolyzing and condensing 100 parts of methyltrimethoxysilane in 400 parts of a 5% ammonia aqueous solution. The obtained polymethylsilsesquioxane was dried and further pulverized to an average particle size of 3 μm.
Powder P-1 was obtained.

Example 1 Viscosity at 25°C 3,0OOc 100 parts of polydimethylsiloxane base oil with dimethylvinylsilyl groups blocked at both ends of P, 154 parts of powder P-, (CH3)2H3i
o < unit and 8102 units, containing 1.02% by weight of hydrogen atoms bonded to silicon atoms, and having a viscosity of 21 cP at 25°C, a base oil containing 2 parts of polyorganohydrodiene siloxane and an isopropyl alcohol solution of chloroplatinic acid as platinum atoms. Composition 1 was prepared by mixing and uniformly dispersing 10 ppm.

Example 2 Composition 2 was prepared under the same conditions as in Example 1 except that the amount of powder P-1 was changed to 100 parts.

Example 3 Composition 3 was prepared under the same conditions as in Example 1 except that the amount of powder P-1 was changed to 150 parts.

Comparative Example 1 Comparative composition 1 was prepared under the same conditions as in Example 1 except that 35 parts of fumed silica Aerosil 200 (manufactured by Degussa Corporation, trade name) was used instead of powder P-1.

Comparative Example 2 Crystallite V was used instead of powder P-1 in Example 1.
Comparative composition 2 was obtained in the same manner except that 100 g of X-8 (manufactured by Iimori Co., Ltd., li product name) was used.

Comparative Example 3 Celite Super Floss (manufactured by John Manville, trade name) 5 was used instead of powder P-1 in Example 1.
Comparative composition 3 was obtained in the same manner except that 0 part was used.

Compositions 1 to 3 and Comparative Compositions 1 to 3 were poured into molds, and then pressed at 110°C for 10 minutes to obtain 2-thick and 6-thick sheets. This sheet was heated to 200℃ for 4
After heat treatment for a period of time, return to room temperature, JIS K2S
O3 based mechanical properties, compression set and toner release tests were conducted. The results are shown in Table 1. The compression set was measured after heating at 180°C for 22 hours.
The toner peeling test was conducted in the following manner.

(Toner peeling test) A 2ml thick sheet that had been heated and returned to room temperature was
- Garden x 130 m - Cut into two tanzak shapes and thoroughly sand the surface with sandpaper (No, 1000). Edge 301 of the polished surface of this sheet
11Ilx 10h+m, toner EP31G (manufactured by Minolta Co., Ltd., trade name) is uniformly applied to the surface. Thereafter, as shown in the drawing, the toner-coated surfaces of the two sheets are overlapped and pressed together at 180° C. for 30 minutes (with a 1000G weight placed on top). In addition, in the drawing, g l -301
1, β2-10011. Next, it is returned to room temperature and pulled in a 180° direction using a tensile tester equipped with an automatic recorder, and the force required to peel off the crimped portion is defined as the "toner peeling force." The smaller this value is, the better the releasability is.

(Hereinafter in the margin) Table 1 (hereinafter in the margin) Table 1 shows that the composition of the present invention can contain as much as 150 parts of polymethylsilsesquioxane per 100 parts of veil oil, and has excellent toner releasability. and low compression set. On the other hand, in the form of smoke, 35 parts results in a very high viscosity composition and poor toner releasability, and Crystallite X-S or Celite Super 70
Compression set will be high in systems using gas.

Example 4 Viscosity at 25°C 10.000 c 100 parts of polydimethylsilyl O xane base oil blocked with dimethylvinylsilyl groups at both ends of P, 18 parts of Aerosil 200, powder P-
11 parts, (CH3)2 H8i Consists of 0 parts unit and 5iOz unit, hydrogen atom bonded to silicon atom is 1.02
1.3 parts of polyorganohydrodiene siloxane containing 1.3 parts by weight and having a viscosity of 210P at 25°C, and 891) liters of isopropyl alcohol solution of chloroplatinic acid as platinum atoms per base oil were mixed and uniformly dispersed. Composition 4 was prepared.

Example 5 Composition 5 was prepared in the same manner as in Example 4 except that 3 parts of powder P-1 was used instead of 1 part.

Example 6 Composition 6 was prepared in the same manner as in Example 4 except that 5 parts of powder P-, 1 was used instead of 1 part.

Comparative Example 4 Comparative composition 4 was prepared in the same manner as in Example 4 except for excluding powder P-1.

Comparative Example 5 Crystallite VX was added to Comparative Composition 4 of Comparative Example 4.
-S at 5°0 per 100 parts of base oil in the composition.
Comparative Composition 5 was prepared by adding 1.0 parts and mixing to uniformly disperse the mixture.

Comparative Example 6 In addition to Comparative Composition 4 of Comparative Example 4, Celite Super Floss was added at 5.0 parts per 100 parts of base oil in the composition.
Comparative Composition 6 was prepared by adding 50% of the total amount and mixing to uniformly disperse the mixture.

Example 1 for compositions 4-6 and comparative compositions 4-6
Physical properties and toner releasability were compared in the same manner as in Comparative Examples 1 to 3 and Comparative Examples 1 to 3. The results are shown in Table 2.

(Left below) Table 2 (hereinafter referred to as Sung) Example 7 100 parts of polydimethylsiloxane base oil with dimethylvinyl groups blocked at both ends, viscosity at 25°C 100,000c St, 130 parts of powder P-2, trimethylsilyl groups at both ends The content of hydrogen atoms plugged with silicon atoms is 0.8% by weight, and the viscosity at 25°C is 20CS t.
1 part of polymethylhydrodiene siloxane, and 10 parts of chloroplatinic acid as platinum atoms based on the base oil.
Composition 7 was prepared by mixing pm.

Example 8 Powder P-1 instead of 130 parts of powder P-1 in Example 7
Composition 8 was prepared in the same manner except that 7 parts and 15 parts of Aerosil 200 were added.

Comparative Example 7 Comparative composition 7 was obtained in the same manner as in Example 7, except that 15 parts of Arco O'sil 200 was added instead of 130 parts of powder P-1.

Table 3 shows the results of comparing the physical properties and toner releasability of Compositions 7 to 8 and Comparative Composition 7.

[Effects of the Invention] The rubber-like elastic body obtained by curing the composition of the present invention has particularly excellent rebound resilience, low compression set, and good mold releasability.
It has excellent water repellency and electrical properties, and even when filled in large quantities, there is little negative effect on mechanical and electrical properties.

Due to these advantages, the composition of the present invention is suitable for conventional uses such as botting materials and coating materials for electrical and electronic parts, and is particularly suitable for low compression set and rebound resilience for molding etc. -1 It is extremely useful as a material superior to conventional materials in applications requiring mold releasability.

[Brief explanation of the drawing]

The drawings are diagrams showing the state of a sheet in a toner peeling test of an example of the present invention. Representative Patent Attorney Suyama Sa - Procedural Amendment Written on January 31, 1985, Japanese Patent Application No. 59-280858 2, Title of Invention: Polyorganosiloxane Composition 3, Relationship with the Amendment Case/Patent Application Person: 6-2-31 Roppongi, Minato-ku, Tokyo Representative - Toshio Ki 4, Agent Address: 2-1-7 Kanda Tamachi, Chiyoda-ku, Tokyo 101 Contents of amendment (1) Specification “Hydrodiene siloxane” on page 5, line 3 and page 7, line 19 is “hydrodiene siloxane”
and correct it. (2) Specification page 5, lines 18-19 and page 6, lines 17-1
In line 8, change [despite high hardness] to "even if high hardness"
and correct it. (3) "Hydrolyzed condensate" on page 6, line 8 of the specification is corrected to "hydrolyzed/condensed product." (4) "As a platinum atom" on page 8, line 4 of the specification is amended to "as a platinum atom." (5) [[
[Hydrodiene disiloxane] is corrected to "Hydrodiene siloxane". (6) “Methyl” on page 20, line 11 of the specification is “methyl”
and correct it.

Claims (8)

[Claims] (1) (A) General formula: (R^1)a(R^2)bSiO_2_-_(_a_+
_b_)_/_2 (In the formula, R^1 is an alkenyl group, R^
2 represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, a is an integer of 1 or 2, and b is an integer of 0 to 2.
(where a+b is an integer of 1 to 3) Polyorganosiloxane having at least two units represented by in the molecule: 100 parts by weight (B) General formula: (R^3)cHdSiO_2_-_(_c_+_d_)
___/_2 (wherein, R^3 represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, c is an integer of 0 to 2, d is an integer of 1 or 2, and c+d is an integer of 1 to 3) and has at least 3 silicon-bonded hydrogen atoms in the molecule: Polyorganohydrodiene siloxane (A
) in an amount such that the number of hydrogen atoms bonded to silicon atoms is 0.5 to 4.0 per R^11 in ) (C) Catalyst selected from the group consisting of platinum and platinum compounds: platinum Polymethyl silsesquioxane having an average particle diameter of 0.1 to 100 μm in an amount of 1 to 100 ppm and (D) 0.5 to 300 parts by weight based on the polyorganosiloxane (A) as atoms. Organosiloxane composition. (2) The composition according to claim 1, wherein R^1 in (A) is a vinyl group. (3) The polyorganosiloxane (A) has a general formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^2 has the same meaning as above, and n is 20 to 5,0
The composition according to claim 2, which is a compound represented by: (4) Claims in which the polyorganosiloxane of (A) is a compound represented by the general formula: ▲ Numerical formula, chemical formula, table, etc. ▼ (wherein n represents an integer from 20 to 5,000) The composition according to item 3. (5) The polyorganohydrodiene siloxane of (B) has the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R^4 represents a hydrogen atom or a methyl group, and p is 1 to 100 (however, 1 When R^4 is a methyl group, p
is 2 to 100, and when two R^4 are methyl groups, p is 3 to 100.
100), q represents an integer of 0 to 100]. (6) The polyorganohydrodiene siloxane of (B) has (CH_3)_2HSiO_1_/_2 units and Si
2. The composition according to claim 1, wherein the content of hydrogen atoms bonded to silicon atoms is 0.3 to 1.2% by weight. (7) Claims in which (D) is polymethylsilsesquioxane obtained by hydrolyzing and condensing methyltrialkoxysilane or its partially hydrolyzed and condensed product in an aqueous solution of ammonia or amines. The composition according to item 1. (8) The composition according to any one of claims 1 to 7, wherein (D) has an average particle diameter of 0.1 to 20 μm.