DE423971C - Process for vulcanizing rubber - Google Patents

Description

The invention relates to a method for vulcanizing rubber or pre-rubber mixtures. It is known that the derivatives of benzothiazole accelerate vulcanization. The substances that mercaptobenzothiazoles, of which were previously used or whose accelerating power was known, for this purpose the mercaptobenzothiazole

C ₆ H,

4 \

SC- SH

the simplest representative is to like their salts or disulfides

The literature on this question is particularly complete in the book Systematic Survey of the Rubber Chemistry "by C. W. Bedford and H. W. Winkelmann (published by the Chemical Catalog Co. New York, 1923, see especially pages 31, 38, 46, 49, 96, 104, 184, 191, 316).

The substances listed above, namely the Mercaptobenzothiazoles, its salts and disulfides but so far have not found an extensive use in industrial practice and it foresees ^r Hch not find, mostly because they act strongly. They are capable of causing vulcanization even at low or moderate temperatures, as often occur during the previous treatment of the rubber compounds, so that the compounds are easily spoiled by pre-vulcanization.

It has now been found that other derivatives of the benzothiazole group are accelerators which are sufficiently powerful for practical purposes, but not the harmful premature vulcanization of the Have mixture because their acceleration force is only noticeable at temperatures which are above those which can usually be achieved during the mechanical pretreatment of the rubber compounds.

These derivatives contain neither the mercaptan nor the disulfide group which the Carriers of the strong acceleration and drying effect described above are, but instead, they contain an arylamine radical.

A prototype of this class of accelerators is 2-anilidobenzothiazole

C ₆ H ₄ /

C-NH-C ₆ H ₅ ,

42S971

however, its homologues, which side chains or groups in one or contain both benzene nuclei can be used with good results.

As is well known, these substances can easily be caused by the action of oxidizing agents, such as bromine or chlorine, on which substituted thioureas are generated. For example the anilidobenzothiazole is obtained by the action of bromine on thiocarbanilide:

C ₆ H ₅ • NH-C-HN • C ₆ H ₅ -f Br ₂ = 2HBr + C ₆ H ₄ .

Il
S.

-NH-C ₆ H ₅ .

Example: A mixture of. 100 parts of rubber, 8 parts of sulfur, 10 parts of zinc oxide and 1 part Anilidobenzothiazol is cured by heating them for 45 minutes at a temperature of 144 ^0th It must also be emphasized that it is not necessary to isolate and purify the resulting oxidation products, but rather that the crude reaction products of the substituted thioureas with oxidizing agents such as chlorine, bromine, hydrogen peroxide etc. are simply dried and introduced directly into the rubber mixture and can be used as an accelerator.

Claims (1)

Patent claim: Process for vulcanizing rubber, characterized by the Use of the crude or purified 2-anilidobenzothiazole or its homologues as a vulcanization accelerator. :. TO DO. GEBRUCKr IN THE REICHSDBfCKEREt.