Untitled record

FRENCH REPUBLIC

MINISTRY OF INDUSTRY

INDUSTRIAL PROPERTY SERVICE

PATENT D

PV n ° 1.632, Hérault N ° 1.237.993

International classification: C 08 c - C 08 d

New rubber regeneration process protected from air oxygen, intended to improve the physical characteristics of vulcanizates.

Mr. Aristide MAURIN residing in France (Hérault).

Requested September 9, 1959, at 4 p.m.^h 5^m, Montpellier.

Issued June 27, 1960.

The various methods of regeneration of vulcanized rubber existing today only use the old principles already known for a long time: initial reduction of vulcanized rubber in crumb which then undergoes a more or less long heat treatment in the presence of the most diverse plasticizers: mineral or vegetable oils, fats, etc. These ingredients are accompanied or not by special chemicals such as peptisants (most often mercaptans) playing the role of oxidation and thermo-molecular degradation catalysts.

Based on the principle that oxygen is harmful for obtaining a good regenerated, it has been developed a method of processing rubber waste (natural or synthetic) in a heated autoclave, either in free steam, superheated (8 kg / cm²) or under high pressure (15 to 45 kg / cm²), either electrically or by thermofluid at almost zero pressure. In all cases, the oxygenated atmosphere of the autoclave is replaced by a “non-active” gas: carbon dioxide or nitrogen, or else rendered inert by a very high vacuum.

Carbon dioxide is introduced into the autoclave either in the form of gas, carbon dioxide snow or solid products capable of giving off carbon dioxide under the action of heat. Example: CO₃HNa.

Nitrogen can be introduced either in the form of gas or in the form of nitrous products decomposing into nitrogen under the action of heat. Example: vulcacel BN

The scope of this patent includes, in the thermal regeneration treatment in an oxygen-free atmosphere, for a period varying from 1 h to 5 h, all waste of rubber origin in natural or synthetic, either in the form of a crumb or under shape of pieces with variable dimensions, not treated or immersed beforehand in a plasticizing solution. Example: benzol, Dutrex V / 10.

Example 1. - Reclaimed tire tread

- 41454

Price of the booklet: 1 NF in autoclave under the above conditions gave the following dynamometric results:

A%, 420;

R kg / cm², 110;

200% modulus, 38;

Shore hardness, 60.

The vulcanizing mixture had the formula:

Regenerated, 100;

Sulfur, 1.4;

ZnO, 2.8;

Stearic acid, 0.56;

Mercaptobenzothiazol, 0.44;

DPG, 0.22.

Example 2. - A white mixture which had the following formula:

Smoked leaf, 100;

Franclay A, 25;

Baryte sulfate, 25;

ZnO, 10;

Stearic acid, 1;

Antioxy. MC, 2;

Sulfur, 2.5;

Mercaptobenzothiazol, 0.5;

DPG, 0.5;

10 'at 145 °:

A%, 620; .

R kg / cm², 185;

Module 200%, 20;

Shore hardness, 50, after protected regeneration gave the following dynamometric results:

A%, 600;

R kg / cm², 95;

Module 200%, 16;

Shore hardness, 50.