JPS60155265A - Production of cured article of organopolysiloxane - Google Patents

Abstract

PURPOSE:To obtain a cured article having excellent self-extinguishing properties, compression set, heat resistance, etc., by adding a specified Ce compd. to an organopolysiloxane contg. unsaturated groups and heating the mixture to cure it. CONSTITUTION:0.5-100pts.wt. Ce compd. having a particle size of 1-50mu and a specific surface area of 50-300g/cm, selected from among Ce2O3, Ce(OH)3 and Ce2(CO3)3, is added to 100pts.wt. organopolysiloxane contg. unsaturated groups which may optionally contain additives such as reinforcing filler, heat resistance improver, colorant, etc. The mixture is cured by heating at 100-300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a cured organopolysiloxane product, and particularly to a novel method for curing organopolysiloxane using a cerium compound as a hardening agent.

Conventionally, methods for curing organopolysiloxanes include condensation reactions between organopolysiloxanes containing silanol groups and organosilicon compounds having hydrolyzable groups such as alkoxysilanes, acetoxysilanes, and aminoxysilanes; Radical reaction with oxide, platinum catalyst between hydrogen silyl group and unsaturated group such as vinyl group ≦:
In addition, recent methods include methods of curing using organopolysiloxanes containing all mercapto groups by treatment with heat, organic peroxides, or ultraviolet irradiation; infrared,
Curing methods using electron beams C2 have also been studied, but for curing thermosetting silicone compositions, curing methods using organic peroxides and methods using hydrothyrecimine (-) are most commonly used.

However, this method using organic peroxide is not safe,
In terms of toxicity, there is a problem that residual diperoxide remains in the cured product, furthermore, C2 requires post-persulfurization, and the self-extinguishing property of the resulting cured product also has drawbacks. It has the disadvantages of having a large compression set and poor heat resistance, and is also due to hydrosilation reaction.
Second, it had disadvantages such as poor storage stability, short pot life, and constant problems of catalyst poisoning.

The present invention solves these disadvantages and provides a novel method for curing organopolysiloxanes (2) in which 100 parts by weight of organopolysiloxanes containing unsaturated groups, cerium oxide, cerium hydroxide, carbonate, etc. It is characterized by adding 0.5 to 300 parts by weight of a cerium compound selected from cerium and curing by heating at 100 to 300°C.

That is, the present inventors have the above-mentioned disadvantages! A method for curing organopolysiloxane without a chemical compound (after various studies, it was found that a cerium compound such as cerium oxide was added to unsaturated group-containing organopolysiloxane and heated) to obtain a cured product of organopolysiloxane. According to C2, problems such as safety, toxicity, and pot life are solved because no peroxide is used, and there is no odor, compression set, and sealing heat resistance. It was confirmed that a cured product with excellent physical properties such as self-extinguishing could be obtained even with two Cs. .

The organopolysiloxane used as a starting material in the method of the present invention has the general formula RSiO, where Rn 4-n.

is an alkyl group such as a methyl group, ethyl group, or propyl group,
Alkenyl groups such as vinyl groups, allyl groups, butenyl groups,
An aryl group such as a phenyl group or a tolyl group, a cygloalkyl group such as a siglohexyl group, or a part or all of the hydrogen atoms bonded to a carbon atom of these groups is a herogen atom, a cyano group, etc. Same or different groups selected from unsubstituted or substituted monovalent hydrocarbon groups such as substituted chloromethyl group, trifluoropropyl group, cyanomethyl group, etc., where n is 1.98 to 2.20. However, regarding these Rt and E2 in one molecule, it is essential that at least one of them is an unsaturated group selected from the above-mentioned vinyl group, allyl group, and butynyl group. This organopolysiloxane may be linear or branched, and has an organic group (
In 8), 50 mol% of the total number of moles of organic groups is usually methyl groups, but the molecular chain terminals of this organopolysiloxane are trimethylsilyl groups, dimethylvinylsilyl groups, divinylmethylsilyl groups, trimethylsilyl groups, Examples include a triorganosilyl group such as a dimethylphenylsilyl group, a diphenylmethylsilyl group, a topunylsilyl group, or a hydroxysilyl group.

In addition, this organopolysilochitin can be used with reinforcing fillers such as finely powdered silica and glass fiber, semi-reinforcing fillers such as calcium carbonate, celite, quartz powder, talc, clay, mica, and aluminum hydroxide, alkoxysilane, and terminal Functional silanes such as silanol dimethylpolysiloxane and diphenylsilanediol, as well as carbon functional silanes as swallow resistance improvers, colorants, and adhesion aids? It may be boiled and boiled, and a predetermined amount of these may be added as necessary.

The cerium compound for curing this organopolysiloxane is selected from cerium oxide, cerium hydroxide, and cerium carbonate, but it should not be added in an amount of 0.5 parts by weight or less per 100 parts by weight of the above-mentioned organopolysiloxane. The organopolysiloxane was not cured sufficiently and it was
If the amount exceeds 0.00 parts by weight, the physical properties of the organopolysiloxane obtained will deteriorate, and for example, the compression set and mechanical properties of the rubber elastic body C will decrease.
Also from the economic point of view, it is preferable to set the amount in the range of 0.5 to 100 parts by weight. However, from the viewpoint of contact with the organopolysiloxane, it is preferable that this cerium compound has a particle size as small as possible and a specific surface area as large as possible.
It is better to use the same.

Such a cerium compound can be obtained, for example, by washing a finely powdered basic cerium carbonate obtained by dropping an aqueous solution of cerium chloride C and an aqueous ammonium dicarbonate solution with water, and then drying the mixture at a temperature of 300° C. or lower. This particle size can be adjusted by selecting the precipitation conditions.

The method of the present invention is based on the basic C: the above-described cerium compound 1 is added to the above-described unsaturated group-containing organopolysiloxane.
yr: This is done by heating after addition, but this heating is in the range of 100 to 300°C, as the organopolysiloxane will not harden at temperatures below 100°C and may deteriorate at temperatures above 300°C. However, it is preferable that the practical ζ2 is 150 to 200°C, and according to this, Jl, I, If/I
? T Tsume, 1117! Various cured silicone products ranging from resin-like to elastic bodies can be easily formed.

Next, examples of the method of the present invention will be given. In the examples, parts in C2 are parts by weight, and viscosity is a measured value at 25°C.

Example 1゜Both ends of the molecular chain were blocked with dimethylvinylsilyl groups,
100 parts of memethylborisiloxane oil with an average degree of polymerization of 1,500, an average particle size of 10 μ and a specific surface area of 160 g
After adding all 5 parts of cerium dioxide and thoroughly kneading, the mixture was pressurized and heated at 165°C and 30K9/7 to obtain a silicone elastic body, and this elastic body had the following physical properties. Indicated.

Hardness JIS) 14 Elongation (%) 168 Tensile strength Ky/cii> 3 Examples 2 to 7, Comparative Example 1 (OH3-2sio unit 99.80 mol%, (,0H
Consists of 0.20 mol% of 2=OH)OH3SiO units,
40 parts of fumed silica was added to 100 parts of a diorganopolysiloxane with a viscosity of 10, OOO, OOOos, in which both ends of the molecular chain were blocked with trimethylsilyl groups, and the mixture was kneaded evenly in a mixer at 15'0°C. Heat treated for 2 hours to remove all volatile components and water and prepare the base compound.

Two qt two, this base compound C two at room temperature $1 Table C
When we investigated the hardening properties of cerium oxide or hydroxide (manufactured by Yoh Seiki Co., Ltd.) in the indicated amounts, we found that Fig. 1 (
＝A result of 100% was obtained.

This cerium compound-added compound was pressurized for 10 minutes at a pressure of 30 Kf/d and 165°C for 10 minutes and immediately heated to make test sheets and molded products for compression set measurement in accordance with JIS K-6301. When two strainers were used and their physical properties were measured, the results shown in Table 1 (both listed in Table 1) were obtained.

Example 8, Comparative Example 2 100 parts of dimethylpolysiloxane containing 70.2 mol% of vinyl groups and end-capped with trimethylsilyl groups 6
2. Knead 30 parts of atomized silica with a specific surface area of 200 d1g and 5 parts of low-molecular-weight dimethylpolysilochitin whose ends are blocked with silanol groups, heat-treat at 150°C for 1 hour, and then use a mixing roll Y to powder quartz. 50 parts, titanium oxide 5 parts, platinum compound total platinum is 20 ppm based on the total C2
C2 was added so that

Next, the base compound obtained by doing this is 100
For part C, average particle diameter 10μ, specific surface area 160n11/g
Add 5 parts of cerium dioxide and heat at 165℃, 30KP/
When heating and pressurizing for 10 minutes with cI & to make a sheet-like molded product, the above base compound wand 100 was used for comparison.
Add 0.5 part of chitin to 2,5-dimethyl-2,5 (di-butylperoxy), heat and pressurize under the same conditions as above to make a sheet-like molded product, and then make these sheets. were each made into a strip with a width of 10 mm and a thickness of 21 LIl, and a double test was conducted using the UL94 flame retardant test method (: for the example, it was 5 seconds, and for the comparative example, it was 25 seconds). It was seconds.

[Brief explanation of the drawing]

Figure 1 shows the Q of the cured products obtained in Examples 2 to 7 and Comparative Example 1.
It is a graph showing the curing characteristics according to D and R. Patent applicant Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. Organopolysilochitin 100 containing unsaturated groups
Coulometric part f2, 0.5 to 100 parts by weight of a cesium compound selected from cesium oxide, cerium hydroxide, and cerium carbonate' vs. 1oo to 3o. A method for producing a cured organopolysilochitin product characterized by curing by heating twice.