HU185043B - Method for producing rubber granules - Google Patents

Abstract

Textile-containing waste rubber, in particular waste car tyres containing a predominant proportion of styrene-butadiene rubber, is comminuted and heated to 180 to 220 DEG C with steam treatment. In the process the textile proportion is carbonised and a textile-free regenerated material is obtained.

Description

The present invention relates to a process for the production of rubber granules from used tires containing predominantly styrene-butadiene rubber, in which the periphery of these tires is separated, mechanically crushed and subsequently cut into pieces of wire, if any.

Currently, the rubber granulate has many technical applications, but the condition for the application is that the rubber is essentially textile and iron free. In order to ensure this condition, the production of such rubber granules relies largely on non-textile rubber parts, in particular treads of used tires, almost exclusively truck tires.

The amount obtained by peeling the treads of passenger car tires is too small to economically produce rubber granules if the car body of the passenger car is not renewed at the same time. However, the increasing demand for rubber granules requires that other parts of used tires, especially whole car tires, possibly including steel cord, be coated to produce granules.

A number of mechanical and pneumatic processes are already being developed for separating the textile part of used tires, a common feature of which is to produce large volumes of textile / rubber blends which are not economically feasible. Accordingly, the cost of the rubber granulate produced by said process is also high.

SUMMARY OF THE INVENTION The object of the present invention was to provide a process which makes it possible to produce a substantially textile-free rubber granulate from textile-reinforced tire parts. This procedure avoids the generation of uneconomical by-products and thus eliminates any additional expense that would reduce the economics of the process.

The process of the present invention is characterized in that the mill is treated with steam for about 40 to about 90 g at a temperature of about 180 to about 220 ° C.

Under these conditions, the textile portion becomes carbonised, such that the textile property is completely lost. Textile properties, such as compressibility, hydrophilicity and capillary action, which are detrimental to the further processing of the rubber granulate are eliminated by the treatment according to the invention.

Methods are known for the preparation of a rubber regenerate, i.e., a re-plasticized, vulcanized rubber, which consists of a rubber powder containing predominantly natural rubber, which is mainly derived from the treads of used tires of trucks, about 10% by weight of regenerating sludge, etc. For 1/2 to 3 hours approx. They are treated with hot water steam at 150 ° C and homogenized on refineries. In this solution, the crosslinking structure of the rubber is partially depcdimerized, so that the rubber regenerates so produced can be added to a certain percentage of new rubber blends to replace the rubber component. Any textile portion that may be present is carbonised during this process.

Also known is a solution for the regeneration of rubber, in which the comminuted rubber is partially chemically degraded (depolymerized) by treatment with steam so that the regenerated product can be partially used as a raw material instead of rubber (U.S. Patent No. 2,254,472).

Also for this purpose, the comminuted rubber is regenerated by treatment at a temperature below vulcanization and at a pressure of 10-30 atm (British Patent No. 1,504,169).

However, this known process is not applicable to vulcanizates containing predominantly styrene-butadiene rubber (SBR) as it is not replastifiable but hardens during cyclization.

Surprisingly, it has been found that in the process of the present invention, the SBR does not appreciably harden, but that the rubber portion retains substantially its original properties and only the textile fibers are carbonised. Thus, the present invention provides a process for the first conversion of used passenger car tires into a resellable rubber granulate.

The treatment with water vapor is conveniently carried out in a suitable autoclave. The desired temperature can be set via the operating pressure of the water vapor. The approx. For example, a pressure of about 20 bar is required to reach a temperature of 205 ° C.

The mechanical pre-crushing of used tires, once the rim has been removed, is preferably carried out in a grinding machine to obtain granules having a particle size of about 7 to 10 mm. Subsequent fine grinding can be carried out, for example, in Condux-maJom. For this reason, after the fine grinding in the Condux mill, the wire pieces are magnetically separated from the tires whose casing also includes steel wire parts.

In order to ensure that the treatment of the present invention has sufficient depth, it is desirable to treat the meal at a particle size of from about 0.2 mm to about 1.5 mm. At this point, the path that hot water vapor has to go through the granulation granulate to carbonize the fabric is relatively small and thus the treatment duration can be kept at a reasonably short value. It is preferred to treat the powder for about 60 minutes. The textile-free rubber granulate obtained after the treatment can then be sieved, whereby larger particles can be returned to the pulverizer for fine grinding.

An important advantage of the process according to the invention is that it requires little treatment and that no by-products are formed. The present invention is applicable to all conventional textile materials used in the manufacture of tires, i.e. Rayon, polyamide, polyester and the like.

Claims (3)

A process for producing a non-depolymerized rubber granulate from a textile tire containing predominantly styrene butadiene rubber, wherein the rim of the used tire is peeled off, mechanically milled and then separated into a piece of wire, optionally It is treated with steam for 90 minutes at a temperature of 180 ° C to 220 ° C. -2185043 2. The process of claim 1, wherein the milling is carried out at a particle size of 0.2 to 1.5 mm. 3. A process according to claim 1 or 2, wherein the mill is treated for 60 minutes. without figure Published by: National Office of Inventions Responsible publisher: Zoltán Himer CODE