MXPA05000282A

MXPA05000282A - Method of recapping tires .

Info

Publication number: MXPA05000282A
Authority: MX
Inventors: Peter Hetzel
Original assignee: Michelin Rech Tech
Priority date: 2004-01-06
Filing date: 2005-01-04
Publication date: 2005-08-19
Also published as: CA2490982A1

Abstract

The present invention is a method for retreading a tire comprising a carcass comprising the step of spraying on the radially outermost surface of the carcass rubber comprising a curing accelerator in a thermoplastic matrix.

Description

RECOUCHING METHOD OF TIRES Field of the Invention The invention is in the field of retreaded tires.

BACKGROUND OF THE INVENTION The market for retreaded pneumatic tires is almost entirely a transportation market. In the transport market, the frame or helmet of a tire is expected to last several hundred thousand miles, be favorable to have a new running surface adhered to it several times. New truck tires are very expensive, and therefore are purchased with the expectation that their high initial costs will be compensated by a long service life of the frame, and by the comparative cost of retreading. A variety of procedures and various types of equipment are available for use in the retreading or retreading of pneumatic tires. One of the first stages of retreading a worn tire is to remove the existing tread surface material from the tire frame by a gritty procedure known as polish. Then, a layer that is known as "cushion rubber" is applied to the frame. This fresh or uncured extruded rubber layer REF.161067 can be stapled or bonded to the frame with adhesive. Then, a layer of rolling surface is applied on top of the rubber cushion layer. In the cold retreading process, the running surface is cured rubber, and has a tread pattern already printed on its outer surface. The tire is then placed in an autoclave, and heated under pressure for an appropriate time to induce curing of the rubber layer, and bonding of the rubber layer to the tread surface and to the frame. In the hot retreading process, the tread surface is uncured rubber, and has no rolling surface pattern. The tire is then placed in a tire mold and heated under pressure for an appropriate time to cure the rubber layer and the tread surface, and cause the rubber layer to bond with the tread surface and the frame. [The term "curing" refers to the formation of crosslinks between the elastomeric molecules in the rubber compound].

However, there is currently a need to refrigerate the rubber buffer to store it, due to the presence of vulcanization accelerators. Therefore, there is a need for an improved cushion rubber, and an improved retreading process.

Brief Description of the Invention The present invention is a method for retreading a tire comprising a frame comprising the step of spraying on the radially outer surface of the rubber of the frame comprising a curing accelerator in a thermoplastic matrix.

Detailed Description of the Invention The present invention is a method for retreading a tire comprising a frame comprising the spraying step on the radially outer surface of the frame rubber comprising a curing accelerator in a thermoplastic matrix. In one embodiment of the invention, the thermoplastic matrix is selected from the group consisting of polymethylmethacrylate and polycarbonate. In one embodiment of the invention, the accelerators are selected from the group consisting of zinc dibenzyldithiocarbamate and diphenyl guanidine. Currently, the rubber buffer must be sent and stored in refrigerated containers, since it contains accelerators. vulcanization. The present invention allows for a longer storage life, and a quick curing at low curing temperatures, for example, 125 degrees centigrade. The invention can be further understood by means of the following non-limiting example.

Example 1 Three microencapsulated materials were prepared using a single emulsion evaporation process.

Material Final weight (wrapped + center) Percent of Material Central DPG / PC 44.7g 18.2% ZBEC / PMMA 37.8g 13.4% DPG / PMMA 46.5g 16.2% The impact of the encapsulated accelerators was studied at temperatures ranging from 22 to 170 degrees Celsius. In all cases, an increase in t90 was observed. The decomposition of ZBEC was measured by measuring the production of carbon disulfide, one of the products of decomposition. The results indicated that the encapsulation of DPG was effective in reducing the degree of decomposition of ZBEC. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims

REI INDICATIONS

Having described the invention as above, the claim contained in the following claims is claimed as property: 1. Method for retreading a tire, characterized in that it comprises a frame covering the spraying step on the radially external surface of the rubber of the frame comprising an accelerator of curing in a thermoplastic matrix.
2. Method according to claim 1, characterized in that the matrix is selected from the group consisting of polymethylmethacrylate and polyalcarbonate. Method according to claim 1, characterized in that the accelerators are selected from the group consisting of zinc dibenzyldithiocarbamate and diphenyl guanidine.