JPH0155722B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a conductive rubber composition with excellent electrical conductivity. Conventionally, carbon black,
Fillers such as graphite powder and metal powder are dispersed and mixed into the rubber, and the good conductivity that these fillers basically have is combined in the rubber to improve conductivity. . However, the electrical conductivity of such composites fluctuates depending on the dispersion state of the filler, so there is a problem in principle in controlling it to a constant value. There were drawbacks such as a high specific gravity due to the high content. By the way, recently, research has been conducted on improving the electrical conductivity of polymeric substances having conjugated double bonds, such as polyacetylene, polythiazyl ((-S-N) _-o ), and polyparaphenylene. It has been reported that conductivity can be increased by adding an electron acceptor or electron donor to a material by diffusion, that is, doping. Also, poly-p
-Although there are no conjugated double bonds like in phenylene sulfide, even in polymeric substances in which phenyl groups are bonded through sulfur, which has high electronegativity, doping can improve electrical conductivity. It has also been found that there is a significant increase in The present invention was made with attention paid to this doping effect, and an object of the present invention is to provide a conductive rubber composition that does not have the above-mentioned problems. Therefore, the conductive rubber composition of the present invention includes (a) an electron acceptor or an electron donor and (b) an aryl group, an alkyl group, a naphthyl group, or a derivative thereof, in a composition having rubber elasticity. N, N′- in N′ part
It is characterized by containing paraphenylene diamine and/or phenylnaphthylamine. Hereinafter, the configuration of the present invention will be explained in detail. The composition having rubber elasticity used in the present invention includes rubber and fillers commonly used in rubber compositions, such as carbon black, calcium carbonate,
Zinc white, magnesium oxide, silica, and extender oil, anti-aging agent, vulcanizing agent (sulfur, sulfur donor),
It consists of a vulcanization aid (stearic acid), a vulcanization accelerator, peroxide, etc. The rubber in this case may be rubber containing or not containing double bonds in the main chain, such as natural rubber,
Polyisoprene rubber, styrene-butadiene copolymer rubber, isobutylene-isoprene copolymer rubber, polybutadiene rubber, ethylene-propylene copolymer rubber, copolymer rubber containing ethylene-propylene and other third component, polychloroprene rubber, Acrylonitrile-butadiene copolymer rubber, silicone rubber, acrylic rubber, fluoro rubber,
Examples include plain rubbers such as hydrin rubber, and blended rubbers that are a mixture of these rubbers.
It is well known that rubber compositions generally bond rubber molecular chains to form crosslinks and maintain a constant shape for a long period of time through this chemical reaction operation, but the composition used in the present invention includes both crosslinked compositions having rubber elasticity and uncrosslinked flowable and soft rubber compositions. The doping agent used in the present invention, that is, the electron acceptor or electron donor, has extremely low conductivity when used alone, and can be described as an insulator. Electron acceptors are generally oxidizing agents, including, for example, iodine, bromine, sulfur trioxide, nitrogen dioxide, arsenic pentafluoride, iron chloride ( _FeCl3 ), Lewis acids, and the like. Examples of the electron donor include reducing agents such as sodium, ammonia, and Lewis bases. The concentration of doping agent is
It is sufficient if the amount is 0.1% by weight or more based on the raw material rubber in the composition. This is because if it is less than 0.1% by weight, conductivity cannot be improved. The upper limit of the concentration of the doping agent is not specified, but if it exceeds 15% by weight, the conductivity will reach the saturated value, and adding more will not increase the doping effect, so 15% by weight or more will not increase the doping effect. % is appropriate. Furthermore, the aryl group, alkyl group, naphthyl group, or a derivative thereof used in the present invention may be N,
N,N'-paraphenylenediamine and phenylnaphthylamine in the N' part are compounds in which the diamine or monoamine moiety is substituted, such as N,N'-diphenyl-p-phenylenediamine, N-phenyl- N'-isopropyl-p-
Phenylene diamine, N,N'-di-2-naphthyl-p-phenylene diamine, N-phenyl-
These include paraphenylenediamine derivatives such as N'-1,3-dimethylbutyl-p-phenylenediamine, N-phenyl-N'-naphthylamine, and N-phenyl-2-naphthylamine. In addition,
Paraphenylenediamine derivatives are generally used as anti-aging agents to prevent oxidation or ozone deterioration of rubber compositions containing a large number of double bonds, but in such usage methods that do not use doping agents, The electrical conductivity does not change depending on whether an anti-aging agent is added, and basically paraphenylenediamine derivatives alone do not have the effect of increasing electrical conductivity in a rubber matrix. The conductive rubber composition of the present invention is obtained by incorporating the above-mentioned doping agent and the above-mentioned paraphenylenediamine derivative and/or phenylnaphthylamine into the above-mentioned composition having rubber elasticity. The paraphenylene diamine derivative and/or phenylnaphthylamine may be incorporated by a conventional method, for example, a mixing method. In addition,
These paraphenylenediamine derivatives and/or
Alternatively, the phenylnaphthylamine may be a compound chemically bonded to the matrix rubber in advance. The concentration of the paraphenylenediamine derivative and/or phenylnaphthylamine is 0.5 to 20% by weight, preferably 1 to 10% by weight, based on the raw rubber in the composition. If it is less than 0.5% by weight, the effects of the present invention cannot be obtained. On the other hand, if the amount is more than 20% by weight, blooming occurs and the concentration differs between the surface and the inside, making it impossible to obtain a rubber composition with a uniform concentration. Various methods can be used to incorporate the doping agent into the composition, that is, to dope the composition, but in any case, it is necessary to ensure that the doping agent is uniformly dispersed in molecular form within the rubber matrix. is important. For example, if the doping agent is a substance that evaporates easily, a rubber composition containing a paraphenylenediamine derivative and/or phenylnaphthylamine is left in a sealed container, and the rubber composition is vacuum-evaporated. A method is used in which the pressure is reduced using a pump and the doping agent is introduced into the vacuum. In this case, the higher the ambient temperature and the longer the standing time, the more the doping agent will diffuse into the rubber composition and the concentration will increase. Furthermore, it appears that conductivity increases and stable conductivity is exhibited when the doping agent is not diffused at a rapid rate. Therefore, it is desirable to make the atmosphere as uniform as possible. When the doping agent is difficult to vaporize, the doping agent is dissolved in an organic solvent, and a rubber composition containing a paraphenylenediamine derivative and/or phenylnaphthylamine is immersed or applied therein. and gradually diffuse it into the rubber,
The concentration can be increased. When using sodium as an electron donor,
A 1:1 molar complex of sodium and naphthalene is first prepared in tetrahydrofuran (THF).
It is prepared in a solvent, immersed in a concentration of about 0.1 to 0.01 mol%, and doped to about 10% by weight. In the case of sodium, care must be taken to prevent it from becoming sodium ions due to moisture in the atmosphere. Among these various methods, a method suitable for the type of doping agent is selected, but if the doping agent has the effect of increasing electrical conductivity, the addition method, that is, the doping method, is limited to the methods described here. It's not a thing. Furthermore, after the doping treatment, the characteristic properties of supple rubber compositions were not lost, and at the same time, the electrical conductivity increased, indicating that the doping agent was not reacting with the rubber, but was reacting with the rubber. It is presumed that a complex is formed with the paraphenylene diamine derivative and/or phenylnaphthylamine in the matrix, and the effects of the present invention are exerted through the interaction. In addition, depending on the type of doping agent, there are cases where it chemically bonds with the double bonds of some rubbers and gradually causes curing, but even in such cases, sufficient paraffinization is required. If the enylenediamine derivative and/or phenylnaphthylamine and the doping agent are independently present and contained, the effect of increasing electrical conductivity is not lost. Furthermore, the lower the concentration of fillers such as carbon black, the lower the electrical conductivity of the rubber composition, but in the conductive rubber composition of the present invention,
The effect was observed that the increase in electrical conductivity was particularly significant when the filler concentration was low. The conductive rubber composition of the present invention is used not only as a normal conductive rubber but also as an antistatic rubber. Examples are illustrated below. Example 1 The rubber compositions shown in Table 1 below were doped. Table 1 Polyisoprene rubber ⁽¹⁾ 100 parts by weight Zinc white 3 parts by weight Stearic acid 2 parts by weight Paraphenylenediamine derivative ⁽²⁾
Variables (0 and 1 part by weight) Carbon black ⁽³⁾ Variables (0 to 70 parts by weight) Extension oil 5 parts by weight Vulcanization accelerator ⁽⁴⁾ 0.8 parts by weight Sulfur Yellow 2.0 parts by weight Note: (1) Made by Nippon Zeon Co., Ltd. Nipol IR-2200 (2) N-phenyl-N'-isopropyl-p-
Phenylenediamine (3) ASTM marking N330, iodine adsorption amount 90mg/
g, DBP oil absorption 120 c.c./100 g (4) N-oxydiethylene-2-benzothiazolyl sulfenamide The vulcanization accelerator shown in Table 1 and compounding agents other than sulfur are used as usual in the rubber industry. Using a Banbury type mixer (1.8), each compounding agent was mixed until uniformly dispersed. Next, a vulcanization accelerator and sulfur were added and kneaded using a roll to prepare a crosslinkable unvulcanized rubber composition. This rubber composition is heated at 148°C.
Press crosslinking was carried out in 30 minutes to create a 2 mm thick rubber sheet. A rectangular sample of 40 mm x 8 mm was cut out from this sample, and doped with iodine for 10 to 30 minutes. The results are shown in Table 2 below.

[Table] As can be seen from Table 2, doping with iodine significantly increases electrical conductivity, and in the case of addition of paraphenylenediamine derivatives, electrical conductivity is even higher than in the case of no addition. sex is increasing. The increasing effect becomes more pronounced as the amount of carbon black is reduced. Example 2 Next, the effect of increasing conductivity after doping with various paraphenylene diamine derivatives and phenylnaphthylamine was confirmed. Table 3 below shows the formulation and vulcanization conditions of the polyisoprene rubber composition before doping used in the experiment. Table 3 Polyisoprene rubber ⁽¹⁾ 100 parts by weight Zinc white 6 parts by weight Stearic acid 0.5 parts by weight Paraphenylenediamine derivative or phenylnaphthylamine ⁽⁵⁾ 0 or 10 parts by weight Vulcanization accelerator ⁽⁶⁾ 0.5 parts by weight Sulfur Yellow 3.5 parts by weight Vulcanization conditions: 160°C, 30 minutes Note: (5) Paraphenylenediamine or phenylnaphthylamine derivatives include the following (A) to (D).
It was used. In addition, the following (E) was used for comparison. (A) N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (B) N,N'-diphenyl-p-phenylenediamine (C) N-isopropyl-N'-phenyl-p
-Phenylenediamine (D) N-phenyl-2-naphthylamine (E) Polymer of trityl-dihydroquinoline When a crosslinked rubber sheet was doped with iodine in the same manner as in Example 1, the following fourth
The electrical conductivity shown in the table was obtained.

【table】

[Table] Example 3 As in Example 2, the effect of increasing electrical conductivity was confirmed. Table 5 below shows the formulation and vulcanization conditions of the ethylene propylene rubber composition before doping used in the experiment. Table 5 Ethylene propylene rubber ⁽⁷⁾ 100 parts by weight Zinc white 5 parts by weight Stearic acid 1 part by weight Paraphenylenediamine derivative or phenylnaphthylamine ⁽⁵⁾ 0 or 10 parts by weight Vulcanization accelerator ⁽⁶⁾ 0.6 parts by weight Sulfur accelerator ⁽⁸⁾ 1.2 parts by weight Sulfur Yellow 1.8 parts by weight Vulcanization conditions 160°C, 20 minutes Note: (7) EPT4070 (manufactured by Mitsui Petrochemicals) (8) Tetramethylthiuram disulfide Same as Example 1 When doping was carried out, the electrical conductivity shown in Table 6 below was obtained.

[Table] As is clear from Tables 4 and 6, by doping the rubber composition with iodine, electrical conductivity is achieved regardless of the rubber elastic materials with different double bond concentrations (polyisoprene rubber and ethylene propylene rubber). The effect of increasing production is remarkable, and the anti-aging agent paraphenylenediamine derivatives (A, B,
It can be seen that the rubber compositions containing C) or phenylnaphthylamine (D) doped with iodine have further increased electrical conductivity. On the other hand, paraphenylenediamine derivatives (A,
B, C), phenylnaphthylamine (D),
It is also clear that the addition of trimethyl-dihydroquinoline polymer (E), which is generally used as an anti-aging agent, has no effect on increasing electrical conductivity. As explained above, according to the present invention, an electron acceptor or an electron donor and an N,N'-
Because it contains paraphenylene diamine and/or phenylnaphthylamine, it has uniform electrical conductivity and has a lower specific gravity and excellent electrical conductivity than conventional inorganic fillers such as carbon black. This makes it possible to provide a conductive rubber composition with a high temperature.

Claims (1)

[Claims] 1. In a composition having rubber elasticity, (a) an electron acceptor or an electron donor and (b) an N,N'-paraphthalate having an aryl group, an alkyl group, a naphthyl group, or a derivative thereof in the N,N' parts. A conductive rubber composition containing enylene diamine and/or phenylnaphthylamine.