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Title:
METHOD FOR DEVULCANIZATION OF RUBBER AND DEVULCANIZATION CATALYST FOR SUCH PURPOSE
Document Type and Number:
WIPO Patent Application WO/2015/083109
Kind Code:
A1
Abstract:
The present invention relates to a method for devulcanization of rubber, mechanically and chemically acting on the rubber products to be processed. In addition, the invention relates to a devulcanization catalyst used in said method.

Inventors:
JEVMENOVS, Igors (Jurkalnes 15/25 - 111, Riga, LV-1046, LV)
Application Number:
IB2014/066580
Publication Date:
June 11, 2015
Filing Date:
December 04, 2014
Export Citation:
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Assignee:
JEVMENOVS, Igors (Jurkalnes 15/25 - 111, Riga, LV-1046, LV)
OZERNOVS, Olegs (Dammes 38/22, Riga, LV-1067, LV)
International Classes:
C08J11/00; B29B13/02; B29B13/10; B29B17/04
Domestic Patent References:
WO2013121243A22013-08-22
Foreign References:
US6590042B12003-07-08
RU2129776C11999-05-10
SU124411A11959-11-30
Other References:
See also references of EP 3077452A4
Attorney, Agent or Firm:
KROMANIS, Artis (PETERSONA PATENTS, Ausekla 2-2, Riga, LV-1010, LV)
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Claims:
CLAIMS

1. Method for devulcanization of rubber products, especially rubber tires, said method includes feeding of rubber products in mechanical processing station for mechanical processing of rubber products, and processing of rubber products by devulcanizing agent, wherein mechanical treatment, where mechanical processing of rubber products are performed simultaneously with the feed devulcanizing agent on said rubber products, characterized in that during the processing the rubber products are heated up in the range of 30 to 70 °C and devulcanizing agent is feed onto the rubber products in cyclic manner.

2. Method for devulcanization of rubber products according to Claim 1, characterized in that in the mechanical processing station the rubber products are fed through pair of rollers arranged in the form of cascade, where gap between the pairs of different rollers is configured to provide gaps with different sizes.

3. Method for devulcanization of rubber products according to Claim 1 or 2, characterized in that rotation speed for said rollers is adjustable from 50 to 2000 Hz.

4. A devulcanizing agent for use in method for devulcanization of rubber products according to any preceding Claim, comprising a compound, which contains nitrogenous substance in the range of 30 to 60 vol%, tension-providing substance in the range of 5 to 20 vol%, and concentration-providing substance in the range of 10 to 40 vol%.

5. The devulcanizing agent according to Claim 4, characterized in that nitrogenous substance is selected from the group comprising carbamide and/or urea.

6. The devulcanizing agent according to Claim 4, characterized in that tension-providing substance is zinc stearate.

7. The devulcanizing agent according to Claim 4, characterized in that concentration- providing substance is selected from the group comprising steatite or talc.

Description:
Method for devulcanization of rubber and devulcanization catalyst for such purpose

The present invention relates to a method for devulcanization of rubber, mechanically and chemically acting on the rubber products to be processed. In addition, the invention relates to a devulcanization catalyst used in said method. Rubber products used in devulcanization are vehicle rubber tires.

Devulcanization of rubber products and catalysts used in this process are described in several patent documents, such as USA patents No. US7166658, US6956065, US6831109, US6387965, US5891926, US5798394, US4161464, US5602186, US5284625, US4104205, US4052344, US4384151, US4544675, US5236352, US6924319, US5602186, US5264640, US6590042, US5492657, US6579950 and US7250451. USA patent No. US2891926 describes processed rubber devulcanization including processed rubber heating and exposure to a pressure of up to 3.4x10 6 Pascals.

While in USA patent No. US6590042 describes a processing of rubber products and specific catalyst, which raises the price of rubber product processing, therefore making process economically unfeasible. Prior art tries to solve the problems connected with intensification of rubber product devulcanization process. Various mechanical rubber product processing methods and usage of various additional chemical substances that could possibly intensify the process are presented. In addition, process intensification must be balanced with its economical feasibility. Aim of invention is to create a method of devulcanization process and a devulcanization catalyst, that would increase the speed of process preserving the necessary quality.

Said aim of invention is reached by creating a devulcanization method for rubber products, especially rubber tires of vehicles. Said method includes a feeding of rubber products in mechanical processing station for mechanical processing of rubber products. Additionally to the mechanical processing chemical processing is performed, where devulcanizing catalyst processes rubber products. Furthermore, mechanical treatment of rubber products is performed simultaneously with the feed of devulcanizing agent on said rubber products. During processing of the rubber products said products are heated up in the range of 30 to 70°C. Size of a rubber crumb in a result of mechanical processing can be in the range from 0.5 to 10 mm. Accordingly, said crumbs easily mixes with fed devulcanizing catalyst. Method for devulcanization allows to perform mechanical treatment simultaneously with the chemical treatment or processing. Both processes can be performed sequentially, i.e., firstly, mechanical treatment of rubber products is performed and, secondly, a chemical treatment is performed. Feed of devulcanizing agent onto the rubber products is cyclic.

In the mechanical processing station the rubber products are fed through the pairs of rollers arranged in the form of cascade, i.e., pairs of rollers are placed vertically one on the top of each other. The gap between the pairs of different rollers is configured to provide the gaps with different sizes. Force for compressing the pairs of rollers can be adjustable during the processing, thereby partly adjusting the devulcanizing process itself. The gap between the rollers in the pairs is in the range of 0.25 to 5 mm. Fragmented rubber products or rubber flakes, or crumbs move between the pairs of rollers, where the pairs of rollers are placed in two vertical units. Furthermore, there are at least 2 to 4 pairs of rollers in every roller unit. Between the said roller units a conveyor, for example a screw conveyour, is placed for transportation of the rubber products to be processed and already processed rubber products.

Rotation speed of said rollers is adjustable to ensure an optimal processing speed. In regard of feed of devulcanizing catalyst and number of the pairs of rollers, the rotation speed for said rollers is adjustable from 50 to 2000 Hz.

For providing the devulcanization method as described in the invention a novel devulcanizing catalyst is used, said catalyst comprises a compound, that contains nitrogenous substance in the range of 30 to 60 vol%, tension-providing substance in the range of 5 to 20 vol%, and concentration-providing substance in the range of 10 to 40 vol%.

Compound comprising nitrogen is selected from the group comprising carbamide and/or urea. Tension-providing substance is selected from the group comprising zinc stearate. Concentration-providing substance is selected from the group comprising steatite or talc. Catalyst amount in relation to rubber product crumbs is in range of 0, 1 - 1 vol%.

Described object of invention comprise method of chemically mechanical devulcanization for rubber products as well as devulcanization catalyst for implementing the said method corresponding to the aims mentioned before.