JPH01108258A - Flame-retarding composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give easily and effectively a cured molding suitable for forming an insulation coating layer of a wire or the like, excellent in flame retardancy and low in a toxicity index, by mixing a silicone rubber with a platinum-containing flame retardant, optimally together with a metal oxide, and a silane coupling agent in specified amounts. CONSTITUTION:100pts.wt. silicone rubber (A) of, e.g., addition reaction or peroxide curing type is mixed with 0.002-0.03pts.wt. platinum-containing flame retardant (B) such as PtCl2 or PtCl4, alone or together with 0.01-10pts.wt. metal oxide such as TiO2, CuO or Fe2O3, and 0.1-30pts.wt. silane coupling agent (C) such as trimethoxysilane or aminosilane.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a flame-retardant composition of silicone rubber suitable for forming an insulating coating layer of electric wires, etc. The present invention relates to a silicone rubber composition that can provide a cured molded product.

[Conventional technology and its problems]

Conventionally, as flame retardant formulations for silicone rubber, platinum-based flame retardants (platinum chloride and its derivatives) were used alone or mixed with metal oxides such as TiO□ and CuO into silicone rubber. There are known ways to do this. but,
Compositions made by adding and mixing platinum-based flame retardants to silicone rubber are combustible in air.

Incomplete oxides of hydrocarbons are likely to occur, and in particular, a large amount of formaldehyde MCll0, which is highly toxic to the human body, is generated, and the toxicity of the combustion gas is extremely strong. In addition, platinum-based flame retardants such as those mentioned above, which are added to increase the oxygen index, or a combination thereof with total oxides,
Silicone rubber is an addition reaction type (SL-H group and 5i-CH
In the case of a silicone rubber having a =CH group, it acts as a catalyst and causes an addition reaction even at room temperature, so there is a disadvantage that the pot life of the rubber is shortened.

In order to retard this reaction, one method is to incorporate a retarder, such as an alcohol with double bonds, but in this case, the curing (vulcanization) rate is reduced in the production of products by thermoforming. I am reluctant to adopt it because I cannot avoid the disadvantage of lower productivity.

Therefore, an object of the present invention is to provide a silicone rubber composition which can be easily and effectively produced into a cured product by thermoforming, and which has excellent flame retardancy and a low toxicity index.

[Means for solving problems]

In order to achieve the above object, the present inventors have repeatedly produced and studied many compositions for flame retardant formulations of silicone rubber compositions with a low toxicity index. It was discovered that a silicone rubber composition containing a combination of metal oxides such as Tie, CuO, etc. and a silane coupling agent can provide molded products with excellent oxygen index, toxicity index, electrical resistance, etc. I came up with an invention.

That is, the present invention includes 100 parts by weight of silicone rubber, 0.002 to 0.03 parts by weight of a platinum-based layer refueling agent or 0.01 to 10 parts by weight of a metal oxide, and 0.1 to 30 parts by weight of a silane coupling agent. The present invention provides a silicone rubber flame retardant composition comprising:

The silicone rubber used in the composition of the present invention is:

It includes various types of commonly known silicone rubbers such as addition reaction type and peroxide curing type. Further, the platinum-based flame retardant used in the composition of the present invention is, for example, platinum chloride or platinum chloride, and although this platinum-based flame retardant may be added alone, other metal oxides may be added. It can be added in combination with other substances. The amount of these platinum-based layer fuel agents added is the amount conventionally adopted, for example, silicone rubber 10
0.002 to 0.03 parts by weight are used per 0 parts by weight. If the amount added is less than 0.002 parts by weight, the flame retardant effect of silicone rubber will be insufficient;
Even if more than 3 parts by weight is added, it is not only industrially disadvantageous because a commensurate improvement in flame retardance cannot be obtained.
If the silicone rubber is an addition reaction type.

This is not preferable because it accelerates the curing reaction. The preferred addition amount is 0.003 to 0.00 parts by weight, and the particularly preferred practical range is 0.003 to 0.011 parts by weight.

Further, in the composition of the present invention, it is more preferable to use metal oxides in combination with a platinum-based flame retardant. Examples of metal oxides used in such formulations include titanium oxide, cupric oxide, iron sesquioxide, cobalt oxide, and nickel oxide. These can be used alone or in combination of two or more, and the amount added is usually in the range of 0.01 to 5 parts by weight per 100 parts by weight of silicone rubber.

The composition of the present invention is characterized in that it further contains a silane coupling agent in combination with such a combination of silicone rubber and platinum-based layer fuel agent, and the present invention provides that such a characteristic combination composition includes the following: It is based on the discovery that, in addition to good flame retardancy, the toxicity index can be dramatically reduced.

Typical examples of the silane coupling agent used in the present invention include trimethoxyvinylsilane, ethoxymethoxyvinylsilane, and aminosilane. These coupling agents.

One kind may be used, or two or more kinds can be used in combination. The amount to be added can be in a wide range of 0.1 to 30 parts by weight per 100 parts by weight of silicone rubber.

If it is less than 0.1 part by weight, the effect of reducing the toxicity index of the composition (molded product) is insufficient, and if it exceeds 30 parts by weight, the toxicity index cannot be reduced commensurate with the amount added, so it is not suitable for industrial use. It is disadvantageous. This reduction in the toxicity index can be achieved by, for example, a toxicity index of 2.1 to 2.
By simply mixing 0.5 parts by weight of a silane coupling agent into the composition of No. 3, the index decreases to 1.0 to 1.3.
Furthermore, the oxygen index also increased by about 1 to 5 points, which was extremely significant, and despite the flame retardant effect, virtually no adverse effect on the bot life of the composition was observed. The practically preferred amount of the silane coupling agent added is 0.65 to 20 parts by weight.

Here, the toxicity index can be determined by the method described in ASTM E-662, and is given by the following formula.

The symbols in the above formula are as follows.

C: Measured concentration of gas in the test chamber (pp-)m
: Weight of the burned sample (g) V: Volume of the test chamber (I'11') Cf: Fatality when a human being is exposed to the gas for 30 minutes (ppm) The toxicity index calculated above is calculated from the formula As is clearly understood, the smaller the number, the higher the safety.

It goes without saying that the composition of the present invention may contain platinum-based catalysts and peroxide catalysts that are commonly known for curing silicone rubber.

For example, a plurality of electric wires on which a coating layer is formed by extruding the composition of the present invention onto a conductor can be made into a bundle.

It is wrapped in a solid intervening layer made flame retardant with metal hydroxide, etc., and the outside is made of acrylic rubber, nitrile rubber, hydrogenated nitrile rubber, urethane rubber, polyolefin elastomer, etc., which is also made flame retardant with metal hydroxide etc. By covering with a sheath layer, a flame-retardant cable with excellent short circuit resistance can be easily provided.

〔Example〕

Next, the composition of the present invention will be explained in more detail using specific examples.

Examples 1 to 2 and Comparative Examples 1 to 4 As silicone rubber, the following formulas (where S+y = 10,000 to 20,000), (where, n = 10,000 to 20,000), and (where, P = 0.2 to 0. 3. q=0.7~0.8
゜p+-q=1, n=10000-20000
), V (vinyl group)
A mixture of 1.5 mol of Me (methyl js) per 1 mol was used as an addition reaction silicone rubber, and KE-5500 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a peroxide-curing silicone rubber. ) was used. In addition, peroxide-curable silicone rubber is separately prepared with a platinum-based layer refueling agent of 0.006 parts per 100 parts by weight of the rubber.
A flame retardant composition containing 0.5 parts by weight of titanium oxide and 0.5 parts by weight of titanium oxide was prepared and compared with a composition that was not flame retardant.

As the silane coupling agent, Toshi Silicone Co., Ltd. 12(7) UNCA-172,5Z-6300 was used, and as the curing catalyst, a platinum-based catalyst and 2,4-dichlorobenzoyl peroxide (manufactured by Shin-Etsu Chemical Co., Ltd.) were used. C-2,2
5% paste), conventional flame retardant formulations and various compositions of the present invention as shown in Table 1 (numbers are parts by weight).
were prepared, and various performances were measured for each cured product. The measurement results are summarized in Table 2.

The various performances were measured using the following methods.

(1) Oxygen index: According to the method specified in JIS K7201.

A practically satisfactory value for silicone rubber is 32 or more.

(2) Toxicity index: Measured according to the method described in ASTM E-662 above.

A practically satisfactory toxicity index is 1.5 or less.

(3) Insulation resistance: resistance value (Ωas) (R, T, ) and tan δ (%) (R,
T, ) is measured. Practically desirable resistance value and tan
δ is.

hlo is 14Ω or more and 1% or less, respectively.

(4) Brittleness temperature (℃): JIS K6301 or JIS C332
Measured according to the method specified in 3 and JIS C2123.

Practically speaking, the temperature is preferably -80°C or lower.

(5) Chemical resistance: In accordance with the above-mentioned embrittlement temperature regulations, the vulcanized rubber is resistant to organic solvents (benzene, toluene, ketones, alcohols), oils (JI No. 83 oil).

Observe the resistance to silicone oil, motor oil), acids, and alkalis. 6. It is preferable that the material does not cause cracks.

(6) Origin tensile strength: JIS C2123
Measured according to the method specified in .

200%M; 0.2 kg/mm" or more is desirable.

TS; Desirably 0.8 kg/mm2 or more.

EQ: Desirably 400% or more.

(7) Tear strength (kg/ai): JIS K6301. JIS C212
According to the method described in 3.

20 kg/cm or more is desirable.

(8) Hardness: Measured by the method specified in JIS C2123.

35 or more is desirable.

(9) Amount of HCHO generated (pp): Measured according to ASTM E-662 method.

The smaller the amount generated, the better; a practically satisfactory value is 40
ppm or less.

The abbreviations in Table 1 are as follows.

5L-A: Addition reaction type silicone rubber obtained by mixing the above two types of silicone rubbers 5L-B: Peroxide curing type silicone rubber manufactured by Shin-Etsu Chemical Co., Ltd.: KE-550 (trade name) 2.4-DC
BPO: 2,4-diglolopenzoyl peroxide (2
(Added as 5% paste) ME-5i: Methoxyethoxysilane No. 1
Table 5i-A 100 100 Si-B (II combustion) 100
100Si-B (Ii no combustion) 10
0 100 Platinum catalyst 0.2
0.22.4-DCBPO2222 ME-3i 1
1 1 Table 2 Oxygen index 29.0 31.0 23.5 23
．． 0 33.5 34.0 Toxicity index 2.10
2.36 2.25 2.23 1.00 1.2
8□2,4X101″5.2×1 stitch’ 5.4# 5.
3# 3.5X10” 9.1X10”tan δ (%)
0.260.170.180.1g 0.200.1
7 Brittleness temperature ("C) -80 or less
o.

Sho v22 Fumitan 200% M (kg/mni”) 0.48 0.2
4 0.25 0.25 0.45 0.25T, S
, (lcg/mm”) O, &4 1.20 1.
19 1.21 0.85 1.21EQ (%)
530 630 625 625 5
70 630 Tear strength (kg/cm) 59 27
26.5 26.7 58 28 Hardness
65 37 38 38 65 3
7HC1+0 generation amount (ppm) 50 55 50
50 30 35 From the above table, it can be seen that the composition of the present invention is extremely desirable as an insulating coating layer for electric wires, etc.

〔effect〕

The composition of the present invention has the following characteristics and excellent effects.

■Compared to conventional products, the toxicity index is much lower and the amount of formaldehyde HCHO generated is significantly reduced.

■Oxygen index is improved by 5 to 5% compared to conventional products.

■Electrical characteristics such as insulation resistance and tan δ are 1.4~
Improved by 1.7 times.

■The excellent mechanical properties inherent to silicone rubber are not impaired.

■When making addition reaction type silicone rubber flame retardant,
Flame retardation can be achieved without substantially reducing pot life.

Claims (1)

[Claims] 1. Silicone rubber 100 parts by weight, platinum flame retardant 0.0
02 to 0.03 parts by weight or 0.01 to 0.01 parts by weight of this and metal oxide
10 parts by weight, and 0.1 to 30 parts by weight of a silane coupling agent.