JP2000281837A - Vulcanizable rubber composition having flame retardancy and generating toxic gas in reduced quantity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vulcanizable rubber composition using an inorganic hydrate without using a halogen-based flame retardant together, and capable of producing a halogen-free rubber product hardly causing degradation in the physical property of vulcanizate, having flame retardancy and generating toxic gas in a reduced quantity. SOLUTION: This flame retardant vulcanizable rubber composition generating toxic gas a reduced quantity is prepared by formulating 100 pts.wt. halogen-free rubber ingredient with 10-200 pts.wt. inorganic hydrate and a halogen-free phosphate-based compound and/or red phosphorus in an amount of 1-30 pts.wt. as phosphorus (P).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanizable rubber composition suitable for producing a rubber product having reduced flame retardancy and reduced toxic gas generation.

[0002]

2. Description of the Related Art Rubber products are widely used in various fields, but rubber products used in various transportation means, housing-related products, home electric appliances and the like are required to have particularly strict flame retardancy. . Conventionally, various halogen-based flame retardants, phosphorus-based flame retardants such as phosphate esters and halogen-containing phosphate esters, aluminum hydroxide (alumina hydrate), magnesium hydroxide have been used to impart flame retardancy to rubber products. Hydrated inorganic compounds such as antimony oxide and the like.

[0003] Since rubber products used in the above applications are used in places where humans are present, in recent years, it has been required that rubber products have flame retardancy and do not generate toxic gas, or the amount of toxic gas generated is small. It is becoming. Among the above-mentioned conventional flame retardants, halogen-based flame retardants and hydrous inorganic compounds are frequently used. In order to increase the flame retardancy, it is necessary to increase the amount used, and as the amount used increases, the physical properties such as the strength characteristics decrease. The halogen-based flame retardant is usually used in combination with a water-containing inorganic compound or the like in order to reduce the amount used and increase the flame retardancy. However, since halogen-based flame retardants tend to generate toxic gases, their use is being restricted depending on the type. Similarly, the production of flame-retardant rubber products may limit the use of halogen-containing rubbers that produce hydrogen halide upon combustion.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to use an inorganic water-containing compound without using a halogen-based flame retardant in combination, to reduce the deterioration in vulcanization properties and to have flame retardancy,
An object of the present invention is to provide a vulcanizable rubber composition capable of producing a non-halogen-containing rubber product with a reduced amount of toxic gas.

[0005]

According to the present invention,
10 to 200 parts by weight of an inorganic water-containing compound and 1 to 3 parts by weight of a halogen-free phosphate compound and / or red phosphorus as phosphorus (P) per 100 parts by weight of a halogen-free rubber component.
Vulcanizable rubber composition characterized by being mixed with 0 parts by weight and having reduced flame-retardant and toxic gas generation.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments. Rubber component used in the present invention,
The rubber is not particularly limited as long as it does not contain halogen. For example, natural rubber, polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR) , Ethylene-propylene-diene monomer terpolymer rubber (EPDM), ethylene-propylene copolymer rubber (EPR), acrylic rubber (ACM), ethylene-acrylate copolymer rubber, and the like. In consideration of vulcanization properties such as strength characteristics and ozone resistance, EPDM and EPR are preferable among these rubbers.

The inorganic hydrous compound used in the present invention includes alumina hydrate known as aluminum hydroxide,
Magnesium hydroxide, calcium hydroxide, barium hydroxide, calcium aluminate (Ca ₃ Al ₂ (O
H) ₁₂ ), basic magnesium carbonate (Mg ₄ (CO)
₃ (OH) ₂ .4H ₂ O). Of these, aluminum hydroxide and / or magnesium hydroxide are preferred. These metal hydroxides are usually used as particles of 100 μm or less, preferably 50 μm or less, more preferably 0.1 to 20 μm.

The halogen-free phosphate compound used in the present invention includes triethyl phosphate, tributyl phosphate, tri- (2-ethylhexyl phosphate), trioctyl phosphate, tributoxy phosphate, triphenyl phosphate and tricresyl phosphate. , Cresyl diphenyl phosphate,
Examples of the plasticizers such as octyl diphenyl phosphate include phosphoric esters conventionally used, and phosphites such as diphenyl phosphite and triphenyl phosphite. These are used alone or in combination of two or more.

In the present invention, since an inorganic water-containing compound is used, process oil and / or
Alternatively, the use of a plasticizer is indispensable, but since these halogen-free phosphate ester compounds are liquid, the phosphate ester compound can also be used as a plasticizer and a flame retardant. The amount of the plasticizer used can be reduced as compared with the case of another type, which is effective in reducing the amount of toxic gas generated. The halogen-free phosphate compound may be used alone or in combination with red phosphorus described below. At that time, the use ratio of both is not particularly limited.

[0010] The red phosphorus used in the present invention may have a surface modified or unmodified. Red phosphorus whose surface is modified, the surface of which is coated with an inorganic compound such as a metal hydroxide in order to enhance the stability of red phosphorus,
Examples include those coated with a resin such as a phenol resin and a melamine resin, and those coated with an electroless plating film of a metal such as nickel, cobalt, copper, and zinc.

In the present invention, the amount of the inorganic hydrous compound, the halogen-free phosphoric acid ester compound and / or red phosphorus used is 100 parts by weight of the rubber component, and the inorganic hydrous compound is 1 part by weight.
0 to 200 parts by weight, preferably 20 to 150 parts by weight, more preferably 20 to 90 parts by weight, and the halogen-free phosphoric acid ester compound and / or red phosphorus is 1 to 30 parts by weight as phosphorus (P), preferably Is 5 to 20 parts by weight. When the amount of the anhydrous hydrated compound is less than 10 parts by weight and the amount of phosphorus is less than 1 part by weight, flame retardancy is hardly obtained. On the other hand, when the amount of the inorganic water-containing compound exceeds 200 parts by weight and the amount of phosphorus exceeds 30 parts by weight, the flame retardancy and the generation of toxic gas can be further improved by increasing the amount of use. This is not preferable because the decrease is remarkable.

In the rubber composition of the present invention, a vulcanizing agent and, if necessary, a reinforcing agent and / or a filler, a process oil, a plasticizer, and a processing aid together with the flame retardant so as to satisfy required performance. A compounding agent such as an antioxidant and an antiozonant is appropriately compounded. These compounding agents are not particularly limited, and those conventionally known are selected and used so as to satisfy the required vulcanization properties. Except for carbon black, process oil and plasticizer as a reinforcing agent, the amounts of various additives are not particularly limited. In particular, process oils and / or plasticizers are indispensable to ameliorate the reduction in processability resulting from using hydrous inorganic compounds.

The following are representatives of the compounding agents. As the vulcanizing agent, a vulcanizing agent conventionally used for the rubber is used depending on the raw rubber. For example, typical vulcanizing agents include sulfur or sulfur-based vulcanizing agents using sulfur-donating compounds such as tetramethylthiuram disulfide and 4,4'-dithiomorpholine;
Dicumyl peroxide, 2,5-dimethyl-2,5-
Di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-
3,1,4-bis (t-butylperoxydiisopropyl) benzene, 1,1-di (t-butylperoxy)-
Organic peroxides such as 3,3,5-trimethylcyclohexane, diisobutyl peroxide, and n-butyl-4,4-bis (t-butylperoxy) valerate are exemplified.

The sulfur-based vulcanizing agent is usually, for example, zinc white,
Using stearic acid or the like as a vulcanization aid, various vulcanization accelerators (thiourea, guanidine, thiazole, thiuram,
Used with dithioic acids). Organic peroxides, as a crosslinking aid, for example, triallyl isocyanurate, trimethylolpropane trimethacrylate,
Polyfunctional compounds such as ethylene glycol dimethacrylate, 1,3-butylene glycol-dimethacrylate, N, N'-m-phenylenebismaleimide (PBM);
Used with 1,2-polybutadiene, p, p'-dibenzoylquinone dioxime and the like.

As the reinforcing agent, for example, FEF, SR
F, HAF carbon black, silica, talc, etc., calcium carbonate, clay, etc. as a filler, and carbon black as a reinforcing agent. When carbon black is used as a reinforcing agent, toxic gases (CO, CO ₂ )
The amount is preferably in the range of 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, per 100 parts by weight of the rubber component.

As the process oil, for example, paraffinic, naphthenic or aromatic mineral oils can be mentioned. Examples of the plasticizer include the above-mentioned halogen-free phosphate compound, a phthalic acid derivative such as dibutyl phthalate and di- (2-ethylhexyl) phthalate, and an adipic acid derivative with di-n-adipate and di- (2-ethylhexyl) adipate. And other conventionally known plasticizers. The amount of process oil and / or plasticizer used is toxic gas (C
O, CO ₂ ) 0.5 to 50 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of the rubber component in order to reduce the generation amount
A range of parts by weight is preferred. Also, when using the halogen-free phosphate ester compound as a flame retardant,
The compounds can function as all or part of the process oil and / or plasticizer. In this case, the amount of process oil and / or plasticizer used can be reduced, and the amount of toxic gas generated can be reduced as compared with the case where a non-halogen-containing phosphate compound is used as the plasticizer. This is effective and preferable because it can be reduced. .

The rubber composition of the present invention comprises an inorganic water-containing compound and a phosphoric acid ester compound containing no halogen and / or red phosphorus and the above-mentioned other compounding agents, which are mixed with a conventional mixer such as a roll, a Banbury or an internal mixer. It is produced by mixing and kneading using The vulcanizable rubber composition of the present invention is molded into a predetermined shape using a molding machine suitable for each purpose and vulcanized to obtain a final rubber product.

The toxic gas in the present invention described above is defined as French standard NFX-70-100 (1986).
CO, C produced by burning a vulcanized rubber specimen according to
O ₂ , HCl, HBr, HCN, HF, SO ₂ and NO ₂
Say. Further, a vulcanized product using the vulcanizable rubber composition of the present invention is used as an index of the amount of toxic gas generated in the present invention,
The sum of the relative emission amounts (R) of each toxic gas measured according to the French standard in Singapore standard SMRT C751B can be less than 1 (determined that the generation amount of toxic gas has been reduced), and vehicle,
It is particularly suitable for producing vulcanized rubber products for subway vehicles.

[0019]

The present invention will be specifically described below with reference to examples and comparative examples. The parts and percentages in the text are based on weight unless otherwise specified.

Examples 1-4, Comparative Examples 1-2 The following formulation (1) (Examples 1 and 2) and formulation (2) (Example 3: 10 parts of red phosphorus, 5 parts of naphthenic process oil) Use, Example 4: According to EPDM (Mitsui Petrochemical Co., Ltd. Mitsui EPT4) according to 5 parts of red phosphorus, 0 parts of naphthenic process oil, and 10 parts of tricresyl phosphate.
045) and each compounding agent were mixed and kneaded using a roll to prepare a rubber composition. Each of the obtained rubber compositions was press-vulcanized at 160 ° C. for 15 minutes at 160 ° C. for 30 minutes for the compounding formula (1) and vulcanized sheet for evaluation at 160 ° C. for 30 minutes. Was prepared. Flame retardancy, measurement of harmful gas, and measurement of vulcanization properties were performed by the following evaluation methods. Table 1 shows all the evaluation results, and Tables 2 and 3 show the measurement results of the toxic gases of Examples 2 and 4.

[0021]Combination method (1) EPDM 100 parts Zinc flower # 3 5 parts Stearic acid 1 part Sulfur 0.8 parts Aluminum hydroxide (* 1) Variable (See Table 1) Magnesium hydroxide (* 2) Variable (See Table 1)  Red phosphorus (* 3) Variable (see Table 1) Silica 15 parts FEF carbon black 5 parts Vulcanizing activator (* 4) 1.5 parts Naphthene-based process oil (* 5) 10 parts Noxeller DM (* 6) 2. 0 part Noxeller M (* 7) 0.5 part Noxeller TT (* 8) 0.75 part Noxeller TRA (* 9) 0.5 part Nocrack 224 (* 10) 1.0 part

Combination method (2) EPDM 100 parts Zinc white # 5 5 parts Aluminum hydroxide (* 1) 80 parts Red phosphorus (* 3) 5 or 10 parts Tricresyl phosphate 0 or 10 parts Silica 15 parts GPF Carbon black 5 parts Naphthenic process oil (* 5) 0 or 5 parts Organic peroxide (* 11) 7 parts Barnock DGM (* 12) 1 part

(Note) * 1: Heidilite H manufactured by Showa Denko KK
42 * 2: Kisuma # 5 manufactured by Kyowa Chemical Co., Ltd. * 3: Nopared 120 manufactured by Rin Kagaku Kogyo (85% surface-coated red phosphorus content) * 4: PE-4000 manufactured by Sanyo Chemical Co., Ltd. * 5: Idemitsu Kosan Co., Ltd. Diana Process Oil PS-32 * 6 to * 9: Ouchi Shinko Chemical Co., Ltd. vulcanization accelerator * 10: Ouchi Shinko Chemical Co., Ltd. antioxidant * 11: Nippon Oil & Fat Co., Ltd. Parkmill D-40 (Jik * 12: Cross-linking aid manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[Evaluation Method] (1) Measurement of Flame Retardancy Flame Propagation in accordance with ASTM C542-94
Measured by the method. ○ indicates pass and × indicates reject. (2) Measurement of toxic gas CO, CO ₂ , HCl, HB produced by burning each vulcanizate specimen in accordance with French Standard NFX-70-100
The amounts of generated r, HCN, HF, SO ₂ and NO ₂ are measured. The standard generation amount of each of the above toxic gases specified in Singapore standard SMRT C751B (per unit area (g /
m ² )) ( _Ref : Reference Values), the actual measured value of the amount of toxic gas generated (per unit area of sample (g / m ² ) (A)
(R = A / R _ef ) (referred to as a relative toxic gas generation amount) (ΔR). If ΣR is less than 1, the amount of toxic gas generated is small, and the vulcanized rubber product is evaluated as safe with respect to toxic gas generation. The smaller the value, the higher the security. (3) Measurement of vulcanization properties Tensile strength and elongation (at break) are measured according to JIS K6251.

Table 1 (Note) (*) Formulation (2)

Table 2

Table 3

As is clear from Table 1, in the vulcanizate using the rubber composition of the present invention, the flame retardancy and the generation of toxic gas are reduced without reducing the vulcanizate properties.
It can also be seen that the amount of toxic gas generated can be further reduced by using an organic peroxide as a vulcanizing agent and reducing the amount of process oil.

[0029]

According to the present invention, there is provided a rubber composition suitable for producing a vulcanized rubber product which has a small decrease in vulcanization properties, is excellent in flame retardancy, and generates a small amount of toxic gas. . The rubber composition of the present invention is suitable for producing rubber products for buildings and railways, particularly for subways.

A preferred embodiment of the present invention is as follows. (1) The vulcanizable rubber composition according to claim 1, wherein the rubber component is EPDM or EPR. (2) Carbon black is 1 to 50 parts by weight, preferably 1 to 30 parts by weight, and process oil is 0.5 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the rubber component.
The vulcanizable rubber composition according to the above (1), which is part by weight. (3) The vulcanizable rubber composition according to claim 3, which is used for producing rubber products for railroad or subway vehicles.

Claims (3)

[Claims] 1 to 100 parts by weight of a halogen-free rubber component, 10 to 200 parts by weight of an inorganic water-containing compound, and 1 to 30 parts by weight of a halogen-free phosphate ester compound and / or red phosphorus as phosphorus (P). A vulcanizable rubber composition having reduced flame-retardant and toxic gas generation, characterized by being blended with. 2. The vulcanizable rubber composition according to claim 1, wherein the inorganic water-containing compound is aluminum hydroxide and / or magnesium hydroxide. 3. The flame-retardant and toxic gas generation amount according to claim 1, wherein the sum of the flame retardancy of ASTM C542 and the relative generation amount (R) of each toxic gas according to Singapore Standard SMRT C751B is less than 1. Reduced vulcanizable rubber composition.