JPS608361A - Condensed silicone rubber composition - Google Patents

Abstract

PURPOSE:To obtain a composition having high rate of curing and excellent reversion resistance and adhesivity, and giving a cured product having remarkably improved heat-resistance, by using an OH-containing organopolysiloxane having vinyl group bonded to Si atom. CONSTITUTION:The objective composition is obtained by compounding (A) 100pts.wt. of an alpha,omega-dihydroxydimethylpolysiloxane having a viscosity of 500- 1,000,000cs at 25 deg.C and containing 0.01-0.10mol/100g, preferably 0.03-0.07mol/ 100g of Si-bonded vinyl group in the molecule, with (B) 1-10pts.wt. of an organosilane and/or liquid low-molecular organosiloxane having >=3 alkoxy groups in the molecule, (C) 0.01-5pts.wt. of an organotin compound catalyst, and (D) 50-300pts.wt. of an inorganic filler preferably containing >=5wt% iron oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a condensation type silicone rubber composition, and particularly to a condensation type silicone rubber composition that has quick curability and excellent heat resistance after curing.

A condensation type made by adding organopolysilochitin, which has i diacid groups at both ends of the molecular chain, organosilane or organosimichitin as a crosslinking agent having at least three alkoxy groups in one molecule, and an organotin compound catalyst. The silicone rubber composition is well known and is widely used in various fields as a room temperature curable silicone rubber. This type of condensation type silicone rubber composition is produced by reacting a vinyl group-containing organoborisiloxane with an organohydrodiene polysiloxane having SiH bonds in the presence of a platinum-based catalyst.

It is widely used in the aviation and nuclear power industries because it does not have the disadvantage of poor curing unlike so-called addition reaction silicone rubbers and has excellent adhesive properties.

However, this condensation type silicone rubber composition also has a
Store in a sealed container at 50°C or higher.

200°C or higher = Heating causes depolymerization, which causes a significant decrease in the hardness of the rubber, which is a disadvantage, and in the case of thick molded products, the hardness of the surface and the inside of the product will be significantly different, which may reduce reliability. The disadvantage is that it becomes inferior,
This improvement is required.

The present invention provides a silicone rubber composition which solves these disadvantages, and which contains 0.01 to 0.10 mole (0.0 mole) of silicon-bonded vinyl groups in the molecule. Viscosity at °C is 500-1,000,00
100 parts by weight of α,ω-dihydroσ-oxydimethylpolysilochitin with 0 cs, β) 1 to 10 parts by weight of organosilane having at least 3 alkoxy groups in one molecule and/or liquid low molecular weight organosimiquitin , 0) Organotin compound catalyst O8.0 1 to 5 parts by weight, D) Preferably an inorganic filler containing 5 parts by weight or more of iron oxide.
300 parts by weight.

To explain this, the present inventors conducted various studies on methods for improving the heat resistance of molded products obtained from condensation type room temperature curable silicone rubber compositions. Cumulatively bonded vinyl group (ESi
It was discovered that the heat resistance of the molded product was improved by introducing OH=OH, a group (OH = OH group), and that the improvement in heat resistance was even more pronounced if iron oxide was mixed with this filler. After learning about this, we completed the present invention by thoroughly researching the amount of =s1oH=oa2 groups, the amount of iron oxide added, etc.

Organopolysilochitin as component A), which is the main ingredient of the silicone rubber composition of the present invention, is α,ω-dihydroxydimethylpolyi10 having hydroxyl groups at both ends of its molecular chain.
It is said to be xane, which has l2asiOH=
It is required that the following formula (%) having OB2 groups is represented by >l-m, n is a positive number), but the amount of 810H=OH2 groups is 0.01 mol/10 (17424 At the bottom, the hardness of the rubber decreases significantly due to heat resistance over time - this effect is not due to the era name.

If it is above 0.10 mol/10 (lJa), the hardness change is too strong and the properties of the rubber cannot be maintained for the necessary time, so the n value must be in the range of 0.01S - 0.10 morph 100 g. , which is preferably between 0.03 and 0
．． 07 mol/100.5r.

This νa chitin can be produced, for example, by equilibration reaction of α,ω-dihydro-axydimethylpolysiloxane and tetramethyltetravinylsigrotetraV-loxane, or with one-ogtamethylsig-a-tetrasiloxane, tetramethyltetravinyldig-a-tetralyloxane, and water. C: Therefore, it can be easily obtained by carrying out an equilibration reaction, but the =SiOH=OH, group in this i10 chitin! is this=SiOH=O
α, ω-dihydro axydimethylbo Ij without H, group
The mixture of va chitin and the α,ω-dihydride containing it with kylydimethylbo IJ i/O xane may be controlled by the mixture. The viscosity of this stain chitin may be appropriately selected depending on the conditions of use and the physical properties required of the rubber obtained by curing C2 of this composition; 000c
A range of 8 is preferred.

The organosilane and organosilochitin as the B) component that are blended into the B) component are the 11th agent.

This is a linear formula containing at least 3 alkoxy groups in the molecule (2) (3) where R1 is a monovalent hydrocarbon group having 1 to 8 carbon atoms. Ma0H,=
OHOOO(OH2), -+ NH, ((3H2)3-
.

NH2(OH2)2NH(OH2)3- + H8(O
H2) a group selected from 2-, R2 is a methyl group, an ethyl group, a glohir group, a butyl group); or a liquid low molecular weight organosilochitin obtained by (partially) hydrolyzing these; However, it may be a mixture of organosilane and organosilochitin, and may be added in an amount of 1 to 10 parts by weight per 100 parts by weight of component fXA).

Furthermore, the organotin compound catalyst as component 0) is known, and includes tin organic acid salts such as tin ogtyrate, tin lafric acid, tin naphthenate, monobutyl-, dibutyl-, monomethyl-, dimethyl-, mono-obutyl-, Examples include organic acid salts such as ogtylic acid, acetic acid, lauric acid, maleic acid, etc. of diobutyl, triogtyls, etc., and the amount added is such that the condensation reaction between component A) and component B) is carried out. The catalyst amount may be 0.601 to 5 parts by weight.

The inorganic filler as component C and D) of the composition of the present invention may be mainly composed of silica powder or diatomaceous earth, which includes fine natural crystalline silica powder, pulverized fused silica powder, Examples include dry-processed finely powdered silica such as humid silica, silica powder such as wet-processed finely powdered silica, and soil that seems to come true.
These are A) dimethylpolyva chitin 10 as a component;
Although 50 parts by weight or more is added to 0 parts by weight, the limit is 300 parts by weight since it is necessary to maintain fluidity. In addition, it is said that this inorganic filler is mainly made of silica powder, Kaisou±.

Since this imparts heat resistance to the rubber molded article obtained from the composition of the present invention, it is preferable to include at least 5 parts by weight of iron oxide. This is because if the iron oxide content is less than 5 parts by weight, the improvement in heat resistance will be insufficient.
In addition, if it exceeds 50% of the total filler, there will be disadvantages such as delayed curing and a significant decrease in strength, so the content of iron oxide should be in the range of 5NIlcIb or more and 50% or less of the total filler. It is better to

The silicone rubber composition of the present invention can be obtained by mixing the refined components A) to D) and kneading them uniformly using a gate mixer, grade mixer, etc. Cures quickly compared to silicone rubber compositions, and molded products after curing are resistant to subsequent heating.

It has excellent heat resistance, reversion resistance, and excellent adhesive properties, so it can be used in a wide variety of applications.

Next, examples of the present invention will be given, in which the parts in C are parts by weight, and the viscosity is a value measured at 25°C.

Examples 1-4. Comparative Examples 1 and 2 α,ω-dihydroσ-kyridimethylpolysiloxane (base oil-■) having a viscosity of 8,000 cS.

Viscosity is 700cS and 0.13mol/100g in the molecular chain
3 parts of polysilicate 40 (manufactured by Union, Carbide Co., trade name: tetramethinosilicate) to 100 parts of a mixture with α,ω-dihydrokylidimethylpolysiloxane (Pace Oil-II) containing 5iOH=OH2 groups, 80 parts crystalline quartz powder.

Add 3 parts of wet silica fine powder and 0.3 fffl of dibutyltin dioctoate, knead them uniformly, inject C into the mold, and leave at room temperature for 144 hours to form a silicone rubber molded product at 260°C. The hardness was measured before and after heating.

The results shown in the following 13th example were obtained.

Examples 5-9 The viscosity is 500aS and the =S 1OH=OH2 group is 0.04
Polysilicate 40 (
above) 3 parts and 0.3 parts of dibutyltin dibenzyl maleate
Part-oh! Silicone obtained by adding diatomaceous earth, wet silica fine powder, and iron oxide (red iron oxide) as shown in Table 2, homogeneously kneading these two times, and leaving the mixture at the temperature of a silicone rubber molded product for 72 hours. 26 rubber molded products
When the hardness was measured before and after heating at 0°C (2 degrees), the results shown in Table 2 were obtained.

Example IO 80 parts α,ω-dihydroxydimethylpolysiloxane with a viscosity of 8,000 cS C=S with a viscosity of 1,000 as
α containing 0.13 mol/100g of 10H=OR2 group
, 20 parts of ω-dihydroxydimethylborisaxane - 1.5 parts of liquid silicone resin consisting of 3SiO□/2 units and SiO units - 30 parts of wet silica fine powder, 70 parts of quartz powder and 15 parts of red iron. Mixed one 150
Heat and stir at ℃ for 2 hours, and after cooling, the viscosity is ℃ 10cS.
α,ω-dihydroxydimethylboryrilloxane of 2.
A red paste with a viscosity of 290% was prepared by adding 0 parts.

90 parts of Tsuxinyi Polysilicate 40 (mentioned above) (add 10 parts of nidibutyltin dilaurate and dissolve homogeneously for 2 m to make a transparent catalyst liquid, which is then mixed with the red haze described above).
After mixing, the mixture was poured into a 5001L glass beaker to a depth of 50III+, and left at room temperature for 7 days, which cured and turned into silicone rubber.Next, it was heated to 260°C and left for 7 days, and then left at room temperature for 7 days. When the hardness was measured, the results shown in Table 3 were obtained.

Furthermore, an adhesion test was conducted on a corrosion-resistant steel panel of MIL-8-25043 using the above-mentioned mixture of red paste and catalyst liquid, and the results were as shown in Table 1.

In addition, one example is described above for comparison: S
i 0H=OH group-containing α,ω-dihydroxydimethylpolysilochitin is not used at all, and this is “:5iOH=
A similar test was conducted on a product in which the resin was substituted with α,ω-dihydroxydimethylborylyloxane that does not contain an OH group (2. without using red iron, but instead with the above-mentioned liquid silicone resin), and the results were (As listed in Table 3).

Claims (1)

[Claims] 1.A) 0.01 silicon atom-bonded vinyl group in the molecule
~0.10 mol/100. ! i'contains - 3゜25
100 parts by weight of α, ω-i;r hydroxydimethylpolysiloxane having a viscosity of 500 to 1.000,000 cs at °C; Condensation type silicone rubber composition 2 characterized by comprising: molecular weight organosilochitin 1 to 10 parts by weight O) organotin compound catalyst 0, O1 to 5 M parts D) inorganic filler 50 to 300 parts by weight, an inorganic The condensation type silicone rubber composition according to claim 1, wherein the filler contains 5% by weight or more of iron oxide.