RU2482963C2 - Method of producing recycled rubber mix - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to recycling rubber wastes to new uncured rubber for making high-quality products. Proposed method comprises feeding the mix of digestion ingredients to be homogenised at mixing rolls and mixed with rubber grit for mix to be sheeted. Note here that digestion mix is brought to tubular shape to envelope said rolls. Then, rubber grit is dispensed to rolls by conveyor and dispensed for preset time defined experimentally. Now, obtained mix is discharged on reversing feed conveyor to carry it in opposite direction to overload the mix to sheeting rolls wherefrom finished products in the form of uncured recycled rubber product sheets.

EFFECT: decreased labour input, higher mechanical proiperties.

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Description

The invention relates to methods for recovering rubber waste into a new crude rubber suitable for the production of quality products. It can be most widely used in enterprises for the processing of worn tires.

In the world in one year accumulates 20 million tons of worn tires from one billion cars. Only 5 million tons of them are disposed of: crumb rubber is burned at power plants and in cement kilns, and rubber powder with particles smaller than 200 micrometers is added to the new rubber compound. The remaining 15 million tons of tires are dumped.

The original rubber mixture for tires consists of many scarce and expensive components, so the cost of 1 ton of such a mixture is more than 3000 euros.

The task of rubber recycling has existed for as many years as there are tires, however, it is not possible to restore the rubber mixture 100% suitable for the production of new tires from crushed tire tires. While the return of worn rubber to a new cycle is carried out in the form of additives in a mixture of rubber powder with particles smaller than 0.2 mm.

Attempts by mechanochemical method to restore the properties of rubber from crumbs are gradually improving, and there are already single results of obtaining recyclizate with tensile strength approaching half of the mentioned rubber strength of tires. Moreover, the restoration of the quality of rubber depends not only on the composition of the devulcanizing mixture, but also on the method of mixing it with crumbs in order to achieve maximum homogenization.

There is a method of recycling rubber waste (AS USSR No. 1016202, class B29H 19/00, publ. 05/07/1983), including mixing rubber crumb with a mixture of devulcanizer components in a rotary mixer, followed by leafing the mixture and obtaining sheets of rubber recyclate .

The rotary mixer does not impregnate the devulcanizer into crumb particles, which does not provide the necessary homogenization and reduces the efficiency of the devulcanizer. This in turn leads to a deterioration in the physical and mechanical properties of the recyclizate.

Known for the prototype method for recycling rubber waste (US patent No. 5770632, class C08J 11/04, publ. 06/23/1998), including mixing the ingredients of the devulcanizing mixture on rollers, followed by mixing it with rubber crumb to obtain rubber recyclate.

The disadvantage of this method is the lack of homogenization of the final mixture and, as a consequence, a 10-15% reduction in the physico-mechanical properties of the recyclizate. Another disadvantage of this method is the large amount of manual labor.

The objective of the present invention is to reduce the amount of manual labor.

Another objective is to increase the physical and mechanical properties of the recyclizate.

Both tasks are accomplished in a method for producing a rubber recyclate, comprising feeding a mixture of devulcanizer ingredients and homogenizing it on a mixing roller, followed by mixing the devulcanizer with rubber crumb and leafing the resulting mixture, in which, in accordance with the present invention, the devulcanizing mixture is brought to a tubular shape, covering the rolls, then rubber chips are fed to the rolls in a dosed feed conveyor and continuously mixed for an experimentally determined time , after this, the resulting mixture is discharged onto a feed reversing conveyor and its movement is directed in the opposite direction, overloading the mixture onto leaf rollers, from which the finished product leaves in the form of sheets of crude rubber recyclate.

To implement the method, a devulcanizer is used, consisting of carbon chain rubber - 1.5 wt. parts, altax - 4.5 wt. parts and zinc stearate - 2.2 wt. parts. Such a composition has established itself as the best known to date.

For devulcanization use rubber crumb tires less than 3 mm, cleaned of textile and metal cord. Devulcanizer is introduced into the crumb in an amount of 5%.

To implement the method, the technological scheme shown in Fig. 1 is used.

The scheme includes the following devices: a reversible feeding L-shaped conveyor 1, an auxiliary pressure conveyor-feeder 2, mixing rollers 3, an inclined feeding conveyor 4 for leaf rollers 5.

The operations of the method are carried out in the following sequence.

The above-mentioned mixture of devulcanizer ingredients is sent by conveyors 1 and 2 to the mixing rollers 3, with the help of which homogenization of the devulcanizer and its mass transformation into a tubular form on the rollers are achieved. Then, using the same conveyors 1 and 2, rubber crumb is dosed to the mixing rollers on the surface of the mixed devulcanizer. The feed rate is set experimentally to achieve high-quality devulcanization of rubber crumb. Mixing is also carried out for a pre-experimentally determined time. Then the conveyor 1 is turned on reversely (in the opposite direction), the feed conveyor 4 and the leaf rollers 5 are also turned on. The already devulcanized rubber is cut from the mixing rollers, which falls on the conveyor 1 and enters the leaf rollers, where it is formed into sheets of a given thickness and width. In this form, the recyclate obtained is ready for molding into products with subsequent vulcanization.

The operations and their sequence in the claimed method minimize manual labor and provide very high quality homogenization of both the devulcanizer and the recyclization. Due to this, the chemical properties of the devulcanizer are used almost 100%, while products from new rubber receive high physical and mechanical properties.

Claims (1)

A method of producing a rubber recyclate, comprising feeding a mixture of devulcanizer ingredients and homogenizing it on a mixing roller, followed by mixing the devulcanizer with rubber crumb and leafing the resulting mixture, characterized in that the devulcanizing mixture is brought to a tubular shape, covering the rollers, and then fed to the rollers with a dosed feed conveyor crumb and are continuously mixed for an experimentally determined time, after which the resulting mixture is discharged to a feed second reversible conveyor and guide its motion in the opposite direction, on overloading mixture listovalnye rolls from which descends finished products in the form of a crude rubber sheet retsiklizata.

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