DE1022786B - Process for stabilizing rubber against cracking - Google Patents

Description

GERMAN

The invention relates to the stabilization of rubber, in particular to a new method for Prevention and / or retardation of the development of cracks in rubber. Both more natural and more artificial Rubbers have a tendency to crack when used in exposure to air, ozone, heat and / or light get abandoned. This tendency to crack is considerably promoted in the presence of ozone. The invention relates to a method of delaying and / or preventing this decomposition by means of a Ν, Ν'-dialkyl derivative of p-phenylenediamine.

According to the invention, rubber is stabilized against cracking by giving it an N, N'-dialkyl-p-phenylenediamine incorporated in which each alkyl group contains at least 8 carbon atoms. This agent is incorporated into the rubber in a stabilizing amount, preferably in the range is from about 0.001 to about 5 percent by weight of the rubber.

It has already been proposed to use rubber against crack formation by adding N, N'-dialkyl-p-phenylenediamine with smaller alkyl groups as substituents, such as. B. the highly toxic Ν, Ν'-di-sec-butyl-p-phenylenediamine, to protect and also less toxic salts of such amines, z. B. the monooxolate of N, N'-di-sec-butylp-phenylenamine, to use.

It has now been found that the use of the particular, disubstituted p-phenylenediamines according to the invention offers unexpected advantages over these and other known additives. First First of all, the additives provided according to the invention seem to be the most effective preventive agents for Rubber against cracking. Second, they are apparently non-toxic and therefore can be found in rubber that comes into contact with food, and they can be used by workers without dangerous toxic effects are handled. Furthermore, the new additives according to the invention are in water insoluble and therefore do not go during the washing of the rubber or its contact with water lost. In addition, the additives of the invention are relatively non-volatile and therefore will favorably retained in the rubber. They go at high for long periods of use Temperature not lost, as is otherwise the case with volatile additives.

The additives to be used according to the invention are the N, N'-dialkyl-p-phenylenediamines with 8 carbon atoms in one or both alkyl groups, such as N, N'-diheptyl-p-phenylenediamine.

The preferred Ν, Ν'-dialkyl-p-phenylenediamines are those having from 8 to about 12 carbon atoms per alkyl group, especially those in which the two alkyl groups have the same number of carbon atoms - stabilizing processes
of rubber against cracking

Applicant:

Universal Oil Products Company,
Des Piaines, 111. (V. St. A.)

Representative: Dipl.-Ing. E. Jourdan, patent attorney,
Frankfurt / M., Kronberger Str. 46

Claimed priority:
V. St. v. America 19 August 1953

Robert Henry Rosenwald, Western Springs, 111.,

and Joseph Albert Chenicek, Bensenville, 111. (V.St. Α.),

have been named as inventors

point. The preferred group of additives includes Ν, Ν'-dioctyl-p-phenylenediamine, N, N'-dinonyl-p-phenylenediamine, Ν, Ν'-didecyl-p-phenylenediamine, N, N'-diundecyl-p-phenylenediamine and Ν, Ν'-didodecyl-p-phenylenediamine. Note that similar diamines have more than 12 carbon atoms in each alkyl group can be used, but not necessarily with equivalent results.

Instead, the alkyl substituents can also have alkyl groups of different chain lengths and / or have different chain structure. Examples include iN-octyl-N'-nonyl-p-phenylenediamine, N-octyl-N'-decyl-p-phenylenediamine, N-nonyl-N'-decyl-p-phenylenediamine and N-nonyl-N'-dodecyl-p-phenylenediamine.

The alkyl substituents can have straight or branched chains. The branched chain groups can have one or more branches in the chain such as B. in compounds such as N, N'-di-3- (5-methylheptyl) -p-phenylenediamine, by reductive alkylation of p-phenylenediamine or p-nitroaniline with ethyl isoamyl ketone has been shown. It should be noted that this compound is produced by the reductive alkylation of p-phenylenediamine or p-nitroaniline can be represented with a ketone or aldehyde.

A particularly preferred catalyst for effecting the reaction which is not protected here consists of one Mixture of oxides of chromium, copper and barium, although other catalysts are also used

709 849/425

can, such as cobalt, nickel, platinum, palladium and molybdenum. In general, the reductive alkylation reaction is used at an elevated temperature of about 100 to about 250 ° and a hydrogen pressure of about 5 to about 200 atm. performed.

The additives according to the invention can be used in rubber or incorporated into rubber products in any suitable manner and at any suitable stage of manufacture will. Generally, the additive is used in an amount of from about 0.001 to about 5 percent by weight of rubber, although higher or lower concentrations are used in some cases can be. It is. Note that the additives according to the invention together with other additives can be used, which the rubber for certain purposes, for example as an accelerator or plasticizer, be incorporated.

The additives can be used in any rubber stock that is susceptible to tearing or the like Decomposition is exposed, such as. B. for vehicle tires and tubes, other tubes, drive belts, Sheet and thread rubber, rubberized fiber materials, molded objects, boots and shoes and the like, indifferent whether in a mold, in open steam, in hot air or in the cold using the so-called acid process. In another embodiment, the invention can be used to stabilize plastic masses, adhesives and elastomers are used which tend to tear or otherwise decompose during storage or in use tend. When the additive is added to a liquid such as a rubber pigment or an oil it can be dissolved therein in the desired proportion. When added to a solid mass it can be introduced therein by grinding, mastication or other suitable treatment. The additive can be in any suitable form, e.g. B. as a solution or dispersion or as a powder or paste used will.

It should be noted that the term rubber used here is both natural and synthetic rubber including all types of the latter as well as regenerated rubber and aqueous dispersions of rubber-like raw materials with or without the addition of fillers, pigments or accelerators includes.

The following examples serve to illustrate the novelty and utility of the invention.

Example I.

2 percent by weight of N, N'-di- (2-octyl) -p-phenylenediamine are converted into a commercially available rubber-like butadiene-styrene copolymer with the usual ingredients including soot, zinc oxide and sulfur mixed in. The ingredients are on a rubber mill combined in the usual manner and the mixture then stored.

If one contains the Ν, Ν'-dioctyl-p-phenylenediamine Rubber / ozone is exposed to a concentration of 70 parts of ozone per 100 million parts of air, so it is subject to little or no cracking, in contrast to considerable cracking, such as it occurs in a similar rubber sample without the additive.

Example ii

N, N'-di-4- (2,6-dimethylheptyl) -p-phenylenediamine becomes at a concentration of 1.75 percent by weight in one similar synthetic rubber mixture, as described in Example I, mixed in and used for Retardation of the rissbikhmg of the rubber produced therefrom.

of rubber a rubber one

Claims (2)

Patent claims: 1. Method of stabilization
against cracking, in which
Ν, Ν'-dialkyl-p-phenylenediamine is added, characterized in that an N, N'-dialkyl-p-phenylenediamine, in which each alkyl group contains at least 8 carbon atoms, in an amount of about 0.001 to 5 percent by weight is added to the rubber of the rubber is mixed in. 2. The method according to claim 1, characterized in that a phenylenediamine is used in • each of the alkyl groups has no more than 12 carbon atoms contains. Considered publications:
German Patent No. 702,618;
U.S. Patent Nos. 2,605,250, 2,632,770. © 709 849/425 1.58