Phenylenediamine derivative, production method thereof and antioxidant for rubber using it as effective constituent

Abstract

A phenylenediamine derivative represented by following formula (I) or (II): wherein R1 and R2 each represents a hydrogen atom, a lower alkyl group, or a lower alkoxy group; R3 represents a hydrogen atom or a methyl group; R4 represents a methyl group or an ethyl group; and n and m each is 1, 2, or 3; wherein R1 and R2 each represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a cyano group; and n and m each is 1, 2, or 3, is disclosed. These phenylenediamine derivatives are effectively used as antioxidants for rubbers, which scarcely cause vanishing by evaporation or a thermal denaturation even under a high-temperature condition of 150° C. or higher.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a phenylenediamine derivative, a production method thereof, and an antioxidant for rubber using the phenylenediamine derivative as the effective constituent. More specifically, the present invention relates to a phenylenediamine derivative which is stable at a high temperature of 150° C. or higher, a production method thereof, and an antioxidant for rubber using the phenylenediamine derivative as the effective constituent. [0002] Also, the present invention relates to an antioxidant for acrylic rubbers. More specifically, the present invention relates to an antioxidant for acrylic rubbers capable of giving an excellent heat aging resistance to an acrylic rubber vulcanization product by using two kinds of antioxidant compounds. BACKGROUND OF THE INVENTION [0003] In particular, requirements for high temperature resistant materials or for longer life materials has been desired in an automobile industry. In rubber-made mater...

AI Technical Summary

Benefits of technology

[0046] According the present invention, the phenylenediamine derivatives (I) and (II) have an excellent in the dispersability into rubbers and in the thermal stability even in the case of being used under a high-temperature condition. So the antioxidants of the present invention can be effectively used as antioxidants for rubbers, etc.

[0047] The phenylenediamine derivatives (I) and (II) have also an excellent property in the point of the oil-extraction resistance even in the case of being added to a sealing material which is brought into contact with an engine oil, so these phenylenediamine derivatives can be effectively used in sealing materials such as oil seals, O-rings, packings, etc.

[0048] Also, when the antioxidant made up of a combination of the same kinds of the antioxidants, namely (A) and (B), of the present invention is added to an acrylic rubber and vulcanized, due to the synergetic action of the combined antioxidants, the excellent heat aging resistance can be imparted to vulcanized acrylic rubber products, which is used at a high temperature, such as oil seals, O-rings, etc., for a long period of time.

[0049] The following Examples are intended to illustrate the present invention more practically but not to limit the invention in any way.

Problems solved by technology

These materials are usually used at a temperature of from about 100 to 150° C., so it is sufficient that the antioxidants used in these materials have a temperature resistance of up to about 150° C., and there have been almost no antioxidant that is assumed to be used at a temperature higher than 150° C. Accordingly, when these antioxidants are used at a temperature higher than 150° C., these antioxidants are apt to volatile from the surface of the materials making it difficult to prolong the life of the materials.

Also, to realize the low volatility of an antioxidant, an attempt of chemically bonding the antioxidant molecule to a polymer and an attempt of holding the antioxidant to a porous substance have been carried out, but there have been many problems in practical use of these methods and the above-described attempts have not yet been practically used at present.

In particular, in the case of an acrylic rubber, an antioxidant is incorporated into the rubber for the purpose of prolonging the life thereof but the antioxidants proposed until now are yet insufficient and a more improvement has been desired.

To hold an antioxidant in a rubber for a long period of time, an attempt of increasing the molecular weight of the antioxidant, an attempt of bonding the antioxidant to a polymer, etc., have been practiced until now as described above, but in the case of using an antioxidant for an acrylic rubber, in particular for an acrylic rubber as a sealing material, such attempts have not sufficiently been able to give a good result and as the case may be, on the contrary, hasten aging.

However, with increasing the molecular weight of an antioxidant and by bonding an antioxidant to a polymer, the mobility of the antioxidant in the rubber becomes small, which is considered to be the reason that the desired effect is not obtained.

On the contrary, when an antioxidant having a relatively low molecular weight and a high mobility in the rubber is used, although the antioxidant has a sufficient mobility in the system and a high radical-trapping capacity per weight parts of the antioxidant, the volatile loss of the antioxidant from the surface of the system or the extraction of the antioxidant from the surface of the system into a contact medium, etc., is large, whereby the sufficient effect cannot be obtained.

In a chloroprene rubber and NBR, as the case may be, the synergistic effect is obtained by combination of amine based antioxidants, but the combination of the amine based antioxidants in the above-described case is not effective in the case of acrylic rubbers.

That is, because the acrylic rubbers are required to be used at a higher temperature (about 150° C.) than the temperature at which the chloroprene rubbers and NBR are used, and also become hard when heat degradation occurs, there is a fact that conventional antioxidants cannot endure the practical use at such a high temperature.

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