JP6889042B2 - Rubber composition for cushioning rubber for railway vehicles - Google Patents

Description

The present invention relates to a rubber composition for cushioning rubber for railroad vehicles, which contains polychloroprene rubber and natural rubber as rubber components.

Generally, in railway vehicles, cushioning rubber having various shapes and anti-vibration performance is used. For example, the bush-type cushioning rubber is a part of the force transmission link device installed between the car body and the bogie, and the cushioning rubber absorbs the force generated by the vertical and horizontal movements and provides the restoring force against the movements. generate. In recent years, in consideration of the occurrence of fire, it has been required to improve the flame retardancy of such cushioning rubber for railway vehicles.

When improving the flame retardancy of rubber, a technique of blending a flame retardant in a rubber composition as a raw material is known. Phosphorus-based flame retardants, halogen-based flame retardants, antimony-based flame retardants, etc. are known as flame retardants, and in particular, excellent flame retardant effects can be generally obtained by using a halogen-based flame retardant and antimony trioxide in combination. Are known. However, in recent years, due to heightened environmental awareness, it has been required to improve flame retardancy, have low smoke emission during combustion (low smoke emission), and further reduce the generation of toxic gas during combustion. , The technology of using a halogen-based flame retardant and antimony trioxide in combination has an environmental problem.

From the viewpoint of the environment, there is a technique for blending a non-halogen flame retardant in a rubber composition. For example, Patent Document 1 below reports a flame-retardant rubber in which magnesium hydroxide and red phosphorus are mixed with polychloroprene rubber. Further, Patent Document 2 below reports a flame-retardant rubber in which a metal hydrate, red phosphorus and a silane coupling agent are blended with polychloroprene rubber.

Japanese Unexamined Patent Publication No. 2005-146256 JP-A-2007-0231102

By the way, in addition to improving flame retardancy, cushioning rubber for railway vehicles is required to improve normal rubber physical properties such as modulus and tensile strength. However, as a result of the examination by the present inventor, it has been found that the rubber described in the patent document cannot achieve both the improvement of flame retardancy and the maintenance and improvement of the normal physical characteristics of the rubber.

The present invention has been developed to solve the above problems, and is a cushioning rubber for railroad vehicles, which is a raw material for cushioning rubber for railroad vehicles, which has improved flame retardancy and normal rubber physical properties such as modulus and tensile strength in a well-balanced manner. It is an object of the present invention to provide a rubber composition for use.

As a result of diligent studies to solve the above problems, the present inventor has found that the above object can be achieved by the following rubber composition for cushioning rubber for railroad vehicles, and has completed the present invention.

That is, the present invention relates to a rubber composition for a cushioning rubber for railroad vehicles, which comprises polychloroprene rubber and natural rubber as a rubber component, and further contains an intomescent-based phosphate as a flame retardant.

Generally, in the combustion of a polymer, the type of polymer is such that degradable products of the polymer accumulate on the surface of the polymer, and the molten polymer drips or pops from the material, especially when the combustion continues. The appearance differs greatly depending on the type. As a result of diligent studies on the combustion behavior of the combined system of polychloroprene rubber and natural rubber selected by the present inventor as the rubber component of the buffer rubber for railway vehicles, the intomescent-based phosphorus as a flame retardant was applied to these rubber components. When the acid salt is blended, an intomesent (foam expansion layer) is formed on the rubber surface when the combined rubber of polychloroprene rubber and natural rubber is burned, and this acts as a protective barrier when the polychloroprene rubber and natural rubber are burned. , It was found that it exerts the effect of suppressing combustion.

As described above, in the present invention, by combining the combined rubber of polychloroprene rubber and natural rubber with the intomescent-based phosphate, combustion during rubber combustion is effectively inhibited and flame retardancy is improved. can do. Furthermore, by constructing such an effective combustion suppression mechanism, it is possible to suppress the amount of the flame retardant, which generally leads to deterioration of the normal physical properties of rubber such as modulus and tensile strength, as the amount of the compound is increased. Deterioration of rubber normal physical properties can be suppressed. As a result, the present invention can provide a rubber composition as a raw material for cushioning rubber for railway vehicles, which has improved flame retardancy and normal rubber physical characteristics such as modulus and tensile strength in a well-balanced manner.

In the rubber composition for cushioning rubber for railroad vehicles, when the total amount of the rubber component is 100 parts by weight, the content X of the polychloroprene rubber is 50 <X < 100 parts by weight and the content Y of the natural rubber is 50 parts by weight. It is preferably contained in an amount of 0 <Y <50 parts by weight. By blending an intomescent-based phosphate while setting the ratio of polychloroprene rubber and natural rubber to such a blending ratio, an intomesent (expanded foam layer) is effectively formed on the rubber surface during combustion. be able to. As a result, the flame retardancy of the cushioning rubber for railway vehicles finally obtained and the normal rubber physical properties such as modulus and tensile strength can be further improved in a well-balanced manner.

The rubber composition for cushioning rubber for railway vehicles preferably contains 5 to 100 parts by weight of the phosphate. According to such a configuration, an intomesent (expanded foam layer) can be effectively formed on the rubber surface when the polychloroprene rubber and the natural rubber are burned. As a result, the flame retardancy of the cushioning rubber for railway vehicles finally obtained and the normal rubber physical properties such as modulus and tensile strength can be further improved in a well-balanced manner.

The rubber composition for cushioning rubber for railroad vehicles according to the present invention contains polychloroprene rubber and natural rubber as rubber components, and further contains an intomescent phosphate as a flame retardant.

In the present invention, polychloroprene rubber and natural rubber are used as rubber components in order to further improve the flame retardancy of the finally obtained cushioning rubber for railroad vehicles and the normal rubber physical properties such as modulus and tensile strength in a well-balanced manner. Combined. In the present invention, diene rubbers other than polychloroprene rubber and natural rubber, for example, polyisoprene rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR), butyl rubber (IIR), acrylonitrile butadiene rubber ( NBR) or the like may be contained in the rubber component.

When the total amount of the rubber component is 100 parts by weight, it is preferable that the content X of the polychloroprene rubber is 50 <X < 100 parts by weight and the content Y of the natural rubber is 0 <Y <50 parts by weight. It is more preferable that the content X of the chloroprene rubber is 60 <X < 100 parts by weight and the content Y of the natural rubber is 0 <Y <40 parts by weight. By blending an intomescent-based phosphate while setting the ratio of polychloroprene rubber and natural rubber to such a blending ratio, an intomesent (expanded foam layer) is effectively formed on the rubber surface during combustion. be able to.

In the present invention, as a flame retardant, an intomescent-based phosphate that is particularly effective for a combination system of polychloroprene rubber and natural rubber is used. As the phosphate, a phosphate known to those skilled in the art can be used, but it is particularly preferable to use magnesium phosphate or ammonium phosphate. As a flame retardant containing magnesium phosphate, ammonium phosphate, etc., a commercially available product can also be preferably used, and examples thereof include "FP-2200" manufactured by ADEKA Corporation.

By effectively forming an intomescent (foam expansion layer) on the rubber surface when polychloroprene rubber and natural rubber are burned, the modulus is improved while improving the flame retardancy of the finally obtained cushioning rubber for railway vehicles. In order to maintain and improve the normal physical properties of rubber such as and tensile strength, it is preferable to contain 5 to 100 parts by weight of phosphate, preferably 5 to 50 parts by weight, when the total amount of rubber components is 100 parts by weight. It is more preferable to do so.

In addition to the rubber component and phosphate, the rubber composition for cushioning rubber for railway vehicles according to the present invention includes fillers such as carbon black and silica, vulcanization agents, vulcanization accelerators, silane coupling agents, and zinc oxide. , Stearic acid, vulcanization accelerator, vulcanization retarder, anti-aging agent, softeners such as wax and oil, processing aids and other compounding agents normally used in the rubber industry do not impair the effects of the present invention. It can be appropriately mixed and used in the range.

As the carbon black, for example, SAF, ISAF, HAF, FEF, GPF and the like are used. Carbon black can be used within a range in which rubber properties such as hardness and reinforcing property of the vulcanized rubber can be adjusted. The content of carbon black in the rubber composition is preferably 10 to 50 parts by weight when the total amount of the rubber components is 100 parts by weight.

Examples of the vulcanizing agent include ordinary sulfur for rubber, and for example, powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used. Considering the mechanical properties after vulcanization, other rubber properties, etc., the blending amount of the vulcanizing agent with respect to 100 parts by weight of the rubber component is preferably 0.5 to 5 parts by weight.

As the vulcanization accelerator, a sulfenamide-based vulcanization accelerator, a thiuram-based vulcanization accelerator, a thiazole-based vulcanization accelerator, a thiourea-based vulcanization accelerator, and a guanidine-based vulcanization agent, which are usually used for rubber vulcanization, are used. Vulcanization accelerators such as accelerators and dithiocarbamate-based vulcanization accelerators may be used alone or in admixture.

As anti-aging agents, aromatic amine-based anti-aging agents, amine-ketone-based anti-aging agents, monophenol-based anti-aging agents, bisphenol-based anti-aging agents, polyphenol-based anti-aging agents, dithiocarbamic acid, which are usually used for rubber. Anti-aging agents such as salt-based anti-aging agents and thiourea-based anti-aging agents may be used alone or in admixture.

The rubber composition for cushioning rubber for railroad vehicles according to the present invention includes carbon black, silica, a vulcanizing agent, and addition in addition to the above-mentioned polychloroprene rubber, natural rubber, and intomescent phosphate as a flame retardant. Usually used in the rubber industry such as vulcanization accelerators, silane coupling agents, zinc white, stearic acid, vulcanization accelerator aids, vulcanization retarders, anti-aging agents, softeners such as wax and oil, processing aids, etc. The compounding agent is obtained by kneading the compounding agent using a kneading machine used in a normal rubber industry such as a Banbury mixer, a kneader, and a roll.

The method of blending each of the above components is not particularly limited, and a method of kneading compounding components other than vulcanization components such as sulfur and a vulcanization accelerator in advance to form a masterbatch, and adding the remaining components to further knead. , A method of kneading only rubber components and carbon black in advance, adding the remaining components and further kneading, a method of adding each component in any order and kneading, a method of adding all components at the same time and kneading, etc. Either is fine.

By molding the rubber composition according to the present invention into a desired shape, various cushioning rubbers for railway vehicles can be produced. Such cushioning rubber is excellent in flame retardancy while maintaining and improving normal rubber physical properties such as modulus and tensile strength. Specifically, it is also excellent in flame retardancy even in a heat generation test according to, for example, ISO5660-1. It shows the sex.

Hereinafter, examples of the present invention will be described and described in more detail.

(Preparation of rubber composition)
The rubber compositions of Examples 1 to 3 and Comparative Examples 1 and 2 were blended with respect to 100 parts by weight of the rubber component according to the compounding formulation shown in Table 1, and kneaded using a normal Banbury mixer to prepare the rubber composition. did. Each combination drug shown in Table 1 is shown below.

a) Rubber component Polychloroprene rubber (CR); manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "Denka chloroprene DCR-36"
Natural rubber (NR); Product name "RSS # 3"
b) Flame retardant Intomescent phosphate (containing magnesium phosphate and ammonium phosphate); manufactured by ADEKA Corporation, trade name "FP-2200"
Magnesium hydroxide; manufactured by Kyowa Chemical Industry Co., Ltd., trade name "Kisuma 5A"
c) Carbon black (HAF-LS); manufactured by Tokai Carbon Co., Ltd., trade name "Seast 300"
d) Zinc oxide; manufactured by Mitsui Mining & Smelting Co., Ltd., trade name "Zinc Hana No. 3"
e) Magnesium oxide; manufactured by Kyowa Chemical Industry Co., Ltd., trade name "Kyowa Mug 150"
f) Wax; manufactured by Nippon Seiro Co., Ltd., trade name "Micro Crystallin Wax"
g) Process oil; manufactured by JX Nippon Oil Energy Co., Ltd., trade name "Process X-140"
h) Anti-aging agent 6C; manufactured by Sumitomo Chemical Co., Ltd., trade name "Antigen 6C"
i) Vulcanization accelerator DM; manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Suncellor DM-G"
TS; manufactured by Sanshin Kagaku Kogyo Co., Ltd., product name "Suncellor TS-G"
j) Sulfur; manufactured by Hosoi Chemical Industry Co., Ltd., trade name "5% oil-treated sulfur"

(Evaluation)
The evaluation was performed on the sample rubber obtained by heating and vulcanizing each rubber composition at 150 ° C. for 30 minutes using a predetermined mold.

<Rubber normal physical characteristics>
The rubber hardness was measured according to JIS K 6253. The tensile properties were measured in accordance with JIS K 6251. The results are shown in Table 1.

ｔ_ｎ＝測定時間，ｔ_ｎ−１＝ｔ_ｎ秒から２秒前の測定時間，ｔ_１＝測定開始時間（ｔ_１＝０）
ｑ_ｎ＝ｔ_ｎ秒時の発熱速度，ｑ_ｎ−１＝ｔ_ｎ−１秒時の発熱速度
２秒毎に積算値を算出し、ＡＲＨＥの最大値をＭＡＲＨＥとする。 <Flame retardant>
In accordance with ISO 5660-1 (heat generation test), a sample of 100 x 100 x 6 mm was prepared, and the heat generation rate was measured under the measurement conditions of ^{a test time of 20 minutes, a measurement interval of 2 seconds, and a radiation amount of 25 kW / m 2.} The obtained measurement result was substituted into the following formula 1 to obtain ARHE (average rate of heat measurement), and the maximum value thereof was defined as MARHE (maximum average rate of heat measurement). The lower the MARHE, the better the flame retardancy. The results are shown in Table 1.

t _n = measurement time, t _n-1 = measurement time 2 seconds before _{t n seconds, t 1} = measurement start time (t ₁ = 0)
The heat generation rate at q _n = t _n seconds, the heat generation rate at q _n-1 = t _n-1 seconds The integrated value is calculated every 2 seconds, and the maximum value of ARHE is set to MARHE.

From the results in Table 1, the vulcanized rubbers of the rubber compositions according to Examples 1 to 3 show excellent results for the flame retardancy evaluation based on ISO5660-1, and have normal rubber physical characteristics such as modulus and tensile strength. It can be seen that the deterioration of the rubber can be prevented. On the other hand, in Comparative Example 2 in which magnesium hydroxide was blended as a flame retardant in the rubber composition, it can be seen that the flame retardancy of the obtained vulcanized rubber is improved, but the normal physical properties of the rubber are deteriorated.

Claims (3)

It contains polychloroprene rubber and natural rubber as rubber components, and when the total amount of the rubber components is 100 parts by weight, it is characterized by containing 5 to 50 parts by weight of an intomescent phosphate as a flame retardant. Rubber composition for cushioning rubber for railway vehicles. Claim 1 in which the content X of the polychloroprene rubber is 50 <X < 100 parts by weight and the content Y of the natural rubber is 0 <Y < 50 parts by weight, assuming that the total amount of the rubber component is 100 parts by weight. The rubber composition for cushioning rubber for railroad vehicles according to. The rubber composition for a cushioning rubber for a railroad vehicle according to claim 1 or 2, wherein the phosphate contains magnesium phosphate and ammonium phosphate.