JPH0912888A - Fireproof, fire-retardant silicone rubber composition - Google Patents

Abstract

PURPOSE: To prepare a fireproof, fire-retardant joint compd. which has satisfactory flame retardancy and strength and is free from a toxic gas by incorporating a silica powder, mica, a crystallite, aluminum hydroxide, magnesium hydroxide, and a platinum catalyst into an organopolysiloxane. CONSTITUTION: 10 to 100 pts.wt. (hereinafter referred to as 'pts.') silica powder (B), 50 to 100 pts. mica (C), 10 to 50 pts. crystallite (D), 1 to 80 pts. aluminum hydroxide (E), 6 to 0 pts. magnesium hydroxide (F), platinum or a platinum compd. in an amt. of 5 to 500ppm in terms of platinum based on the component (A), the component (E) to component (F) ratio being (1:9) to (4:6) with the total amt. of the components (E) and (F) being 10 to 80 pts., are incorporated into 100 pts. organopolysiloxane having an average unit of RaSiO(4-a)/2 (W R represents a hydrocarbon; (a) is an average number of 1.9 to 2.1) to prepare a fireproof, fire-retardant silicone rubber compsn. The components (E) and (F) release water at a high temp. to lower the combustion temp., and, together with the components (C) and (D), combine with the component (A) to form a ceramic-like material to hold a supporting structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant flame-retardant silicone rubber composition which, when sintered at high temperature, becomes a ceramic and remains in joints and glass fitting grooves.
It is foamed and used as a fire-resistant joint material or as a glass press packing material for class A and class B fire doors.

[0002]

2. Description of the Related Art Hitherto, fire-resistant foam joint materials for PC boards have been made by foaming chloroprene rubber and combining it with ceramic fibers, or using silicone rubber foam with a fire-resistant material added. Since the work of sticking to the is complicated, and in the latter case, there are those in which platinum catalyst and refractory materials such as mica (mica) and crystallite (quartz powder) are added to silicone rubber, but this is not enough for fire resistance. It was In addition, the fire-retardant flame-retardant sealing members of the standard gasket for fire doors include chloroprene rubber containing a large amount of chlorine-based flame retardant, or silicone rubber containing a platinum catalyst and a refractory material such as mica or crystallite. However, the former generates a large amount of toxic hydrogen chloride gas during combustion, and the latter silicone rubber gasket for fire doors does not provide sufficient strength after combustion, and it cannot be said to have sufficient fire resistance due to falling off. It was

[0003]

DISCLOSURE OF THE INVENTION The present invention has the disadvantages of these conventional refractory compositions, namely, complicated workability, insufficient fire resistance, insufficient strength, generation of toxic gas during combustion, etc. A flame-retardant flame-retardant silicone rubber composition capable of solving the above problems.

[0004]

Means for Solving the Problems That is, the present invention provides (a) an average unit formula R _a SiO _{(4-a) / 2} (where R is an unsubstituted or substituted monovalent hydrocarbon group of the same or different type). , A is an average number of 1.9 to 2.1) 100 parts by weight of organopolysiloxane, (b) 10 to 100 parts by weight of silica powder, (c) 50 to 100 parts by weight of mica, (d) 10 to 50 parts by weight of crystallite, e) 1 to 80 parts by weight of aluminum hydroxide, (f) 6 to 80 parts by weight of magnesium hydroxide, (g) Platinum or a platinum compound containing the same amount of platinum from 5 to 500 ppm based on (a) in terms of platinum. The ratio of aluminum hydroxide / magnesium hydroxide is 1/9 to 4/6 and the total amount of both is 10 to 80.
It is a flame-retardant flame-retardant silicone rubber composition in parts by weight.

The present invention will be described in detail below. The present invention has been made to solve the problems described above, (a) represents represented by average unit formula _{R a SiO (4-a)} / 2, the average number of wherein a is 1.9 to 2.1, R is methyl Groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, heptyl groups and other alkyl groups; cyclohexyl and other cycloalkyl groups; phenyl, tolyl and other aryl groups; vinyl, allyl and other alkenyl A group or a group in which some or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with an organic group including a halogen atom, an amino group, a cyano group, an epoxy group, a carboxyl group, etc., and they are the same or different from each other. Is an unsubstituted or substituted monovalent hydrocarbon group, preferably 80 mol% or more of which is a methyl group and 0.1 to 0.5 mol% of a vinyl group, an organopolysiloxane having a viscosity at 25 ° C. of 1,000 cSt or more, It is preferably 10,000 cSt or more. The end of this organopolysiloxane is preferably blocked with a silanol group, a methyl group, a vinyl group or the like, and particularly preferably blocked with a vinyl group.

As the silica powder as the component (b), commercially available products such as fumed silica, hydrophobic silica, wet silica, quartz powder and diatomaceous earth can be used, which are used for reinforcing and increasing the amount of silicone rubber. However, the particle size of these is (a)
Since it is necessary to uniformly disperse it in the organopolysiloxane of, it is preferably 50 μm or less. The addition amount is 10 to 100 parts by weight with respect to 100 parts by weight of the organosiloxane of (a), but if it is less than 10 parts by weight, the reinforcing effect of the rubber is insufficient, and if it exceeds 100 parts by weight, the reinforcing effect is changed. On the contrary, the original properties of rubber are diminished. The mica of the component (c) and the crystallite of the component (d) impart fire resistance and flame retardancy to the composition. The amount of the component (c) added is 100 parts by weight of the organosiloxane of (a). 50 to 10
0 parts by weight is required, and the addition amount of the component (d) is required to be 10 to 50 parts by weight based on 100 parts by weight of the organopolysiloxane of (a). If the added amounts are less than 50 parts by weight and 10 parts by weight, respectively, the ceramics are not formed at high temperature and the fire resistance becomes insufficient. On the other hand, when the amount exceeds 100 parts by weight and 50 parts by weight, respectively, the composition has a high viscosity. The particle size of mica is preferably 50 μm or less from the viewpoint of dispersibility in organopolysiloxane and strength retention. On the other hand, the particle size of crystallite is the same for the same reason.
It is preferably 50 μm or less.

Both the aluminum hydroxide as the component (e) and the magnesium hydroxide as the component (f) release water at high temperature to become aluminum oxide and magnesium oxide. At this time, the combustion temperature is changed by latent heat of vaporization of water. Lower. 2
The reason for sharing types is that aluminum hydroxide begins to release water at around 180 ° C and completes release at around 350 ° C. Also, magnesium hydroxide begins to release water at around 340 ° C.
Release continues up to about 450 ° C. Therefore, by sharing both, it is possible to release water continuously over a wide temperature range and suppress an increase in combustion temperature, but in order to exert sufficient flame retardancy and fire resistance, the total amount of both is 10- It must be 80 parts by weight. If it is less than 10 parts by weight, the effect is insufficient, and if it exceeds 80 parts by weight, moldability is poor and it becomes hard and brittle, causing problems in practicality. As a mixing ratio of aluminum hydroxide and magnesium hydroxide, which allows continuous release of water most efficiently and suppresses an increase in combustion temperature, aluminum hydroxide / magnesium hydroxide = 1/9 to It is 4/6. In addition, it also has a feature that the addition of these materials promotes the conversion of the combustion products into ceramics. Both of these can be used as usual commercial products.

Component (g), platinum and a platinum compound, functions as a flame retardant for silicone rubber and, together with the added filler, as a ceramicizing agent for silicone rubber at high temperatures. Generally, since silicone rubber has a low degree of cross-linking, the siloxane main chain decomposes at a high temperature to rapidly generate a volatile low-molecular cyclic substance and continue combustion. When a platinum catalyst is present, it promotes oxidation / deterioration on the surface of the rubber that comes into contact with air, creates a highly crosslinked structure, forms a non-combustible siloxane film with few organic groups on the surface, and shields the air inside the rubber. The rubber does not extinguish, and the rubber self-extinguishes. Various small amounts of auxiliary agents may be used to supplement the function of the platinum catalyst. As the component (g), metallic platinum such as platinum black, chloroplatinic acid, chloroplatinic acid and alcohol, ether,
A complex salt with acetaldehyde or the like is exemplified, but the metal platinum may be supported on a carrier such as alumina or silica gel, and chloroplatinic acid, a complex salt thereof or the like may be added as an alcohol solution and added thereto. Good. The amount of platinum added is 5 with respect to the organopolysiloxane of (a).
It is necessary to add in the range of ~ 500ppm, but preferably 20
It is recommended to add in the range of ~ 200ppm. This addition amount is 5pp
If it is less than m 3, the original function of the catalyst will not be exhibited, and if it exceeds 500 ppm, the effect of the catalyst will not change, so it is not economical to use it at more than 500 ppm.

The flame-retardant flame-retardant silicone rubber composition of the present invention can be easily obtained by mixing predetermined amounts of the above-mentioned components (a) to (g), but if necessary (b) ) Silica or a low molecular weight siloxane containing an alkoxy group, a silanol group, etc. may be blended as a dispersing agent in the rubber, but the type and amount depend on the physical properties required depending on the end rubber application. To be selected.
Further, in order to improve the adhesive strength between the matrix of the refractory filler and the organopolysiloxane, it may be treated with a silane coupling agent or the like. Furthermore, a heat resistance improver,
An inorganic pigment such as titanium white, titanium yellow, red iron oxide, chrome green, or yellow lead may be added as a colorant.

When the composition of the present invention is heated and cured, it becomes a silicone rubber having excellent physical properties. The cured product suppresses the decomposition of the silicone rubber by the platinum catalyst even when exposed to a high temperature of, for example, 800 ° C. or higher. However, at the same time as suppressing the generation of combustible gas, the combustion temperature is lowered by the latent heat of vaporization due to the release of water from aluminum hydroxide and magnesium hydroxide. In addition, the action of diluting the combustible gas with the generated steam makes it extremely difficult to burn, and the minute expansion caused by volatile water causes the volume expansion (1.1 to 1.5 times). Further, since aluminum hydroxide, magnesium hydroxide, mica, crystallite and the like and silicone rubber are tightly bonded to each other to form a ceramic, it is possible to firmly hold the glass fixed to the sash.

[0011]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. (Preparation of Silicone Rubber Composition) Methyl vinyl polysiloxane with a vinyl group content of 0.15 mol% with both ends blocked with vinyl groups ・ KE78VBS (trade name of Shin-Etsu Chemical Co., Ltd.) 100 parts by weight of a specific surface area of 100 m ² / g Dry silica 50 parts by weight, mica with an average particle size of 13 μm (muscovite) 40 parts by weight, average particle size 4 μm
Crystallite (quartz powder) 20 parts by weight, platinum catalyst / CAT
PC-2 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was added at 50 ppm in terms of platinum based on methylvinylpolysiloxane. Aluminum hydroxide (average particle size: 1 μm) and magnesium hydroxide (average particle size: 0.6 μm) were added to the above standard composition at different amounts, and 1.5 parts by weight of monomethylsilane as a cross-linking agent was added (Table 1). Eight types of fire resistant flame retardant compositions were prepared as shown.

(Examples 1 to 3 and Comparative Examples 1 to 5) These were put in a heating furnace and heated according to the heating temperature curve defined by JIS A1311 and burned.

[0013]

[Table 1]

About the obtained sintered body, hardness, tensile strength,
The elongation rate, volume increase rate, and oxygen index (JIS K7201) were measured. The hardness and shape retention were evaluated according to the following criteria and shown in Table 1. Hardness of sintered body ◎: Hard, making a metallic sound when tapped ◯: Relatively hard, making a metallic sound when hit Δ: Relatively hard, but not metallic sound ×: Not hard, Brittleness Shape retention ◎: It does not collapse even if it is gripped comparatively ◯: It collapses when it is gripped somewhat strongly △: Brittle than the above ×: Brittle

From the above examples, the fire-retardant flame-retardant silicone rubber composition of the present invention is a useful fire-retardant flame-retardant composition because it is difficult to burn and the shape retention of the sintered body is sufficient. Was confirmed.

[0016]

INDUSTRIAL APPLICABILITY The fire-retardant and flame-retardant silicone rubber composition of the present invention has a simple workability as a fire-resistant joint material or a glass-pressing packing material for fire doors, has sufficient fire resistance, has sufficient strength, and is toxic gas-resistant. Since it does not occur and is safe, it can solve the problems of conventional products.

Claims (1)

[Claims] 1. (a) An average unit formula represented by R _a SiO _{(4-a) / 2} (R is an unsubstituted or substituted monovalent hydrocarbon group of the same or different type, and a is an average number of 1.9 to 2.1. ) 100 parts by weight of organopolysiloxane, (b) 10 to 100 parts by weight of silica powder, (c) 50 to 100 parts by weight of mica, (d) 10 to 50 parts by weight of crystallite, (e) 1 to 80 parts by weight of aluminum hydroxide. Parts, (f) 6 to 80 parts by weight of magnesium hydroxide, (g) platinum or a platinum compound containing the same amount of platinum as 5 to 500 ppm in terms of platinum based on (a), aluminum hydroxide / magnesium hydroxide Is 1/9 to 4/6 and the total amount of both is 10 to 80
A flame-retardant flame-retardant silicone rubber composition in parts by weight.