RETREAD

In 1995, about 28-30 x 10 tires were retreaded (54). Retreading has been the most cost-effective alternative to recycling mbber. However, worn retreaded tires usually are discarded in a landfill. Approximately 10% of discarded automobile tires and 55—70% of tmck and bus tires are retreaded (55). 

Tire disposal costs are 0.10—3.00 per tire. Cost for incineration without heat recovery is 0.35—0.70 per tire. Transportation of discarded tires can cost 0.04/kg, and size reduction can cost 0.20—0.60/kg. Distribution of passenger car tires is landfill, 85% retreaded, 10% and reclaimed, burned for fuel, and spht, 5%. 

In addition to the soHd form of natural mbber it is available as a soHd suspended in water, known as latex. Synthetic mbbers are also available in latex form. Latex has become an important commodity used in the manufacture of dipped goods for health and disease protection. The principal uses of natural mbber are as follows tires and retreading, 70% latex (gloves, balloons), 12% mechanical goods, 9% load-bearing components, 4% and other, 5%. 

Development of Natural Rubber-Based Tmck Tyre Retreading Compounds," in M. E. Cain and Sifi Zubaidah bte Mohd Rashid, eds.. Proceedings of a UNIDO-sponsored Workshop, Kuala Eumpur, Malaysia, Malaysian Rubber Pioduceis Research Association, Heitfoid, U.K, 1992. 

Automotive Exhaust System Repair Tire Retreading and Repair Paint... 

FIGURE 26.75 Comparing the rate of wear of a retread bias tire with a commercial radial ply tire (a) one tire each mounted on the trailer axle (equal force comparison) and (b) two tires of each group mounted and run consecutively (equal slip). 

Reversion characteristics of NR are of great concern. Lot of novel chemicals have been introduced to increase the reversion resistance of NR. Examples of these are zinc soap activator (Structol-A73), silane couphng agent (Si-69), anti-reversion agent (Perkalink 900), and post-vulcanization stabilizer (Durahnk HTS and Vulcuren KA 9188 Figure 32.7). These materials will enhance the life of the tire, enable the users for more retreading, and thereby reduce the material demand. " ... 

This method involves the removal of mbber particles from tire tread by abrasion and is confined to the preparation of tire buffings, which is obtained as a by-product of retreading. It is a normal practice in industries to reuse tire buffings to make low-technical products by the revulcanization of the powder or by using the powder-sintering process. 

A tyre retreading process in which new rubber is apphed as tread, on the tyre shoulders and on the tyre sidewalls. 

Worn tyres are prepared for retreading by a buffing/grinding process to provide a fresh rubber surface. 

Tread-type rubber compound extruded in a variety of thicknesses and widths for use in tyre retreading. The standard section is in the shape of a regular trapezium, but variations are made to suit particular types of tyre and different makes of moulding equipment. 

A mould or removable section of a mould used in the repair or retreading of pneumatic tyres. Derived from the printing industry where it refers to the mould used for casting type. 

A process used in the retreading of pneumatic tyres, whereby the new tread rubber is applied by extruding and winding a ribbon of uncured rubber (approximately 35 mm wide and 2.5 mm thick) on to the buffed and solutioned tyre casing. Organic Chemistry... 

A thin rubber sheet applied in the replacement of the sidewall pattern details in the retreading of pneumatic tyres. A similar film of rubber specially compounded to resist oxygen or ozone or to prevent the migration of carbon black into a lighter rubber, e.g., a tyre white sidewall. 

Retreading by Smooth Tread Extrusion and Pattern Cutting.197... 

Retreading of tyres may be undertaken in a variety of ways. Unvulcanised material can be applied and then cured at 150-180 °C ( hot retreading), or prevulcanised tread can be applied at temperatures of around 100 °C ( cold retreading). Vulcanisation may take place with or without moulds, or in an autoclave. 

The retreading compound is in the form of an extruded section. It can be supplied at a width to cover the whole area to be retreaded, when it is called Camelback , or it may be in a narrower strip for winding. The extruded material is then vulcanised to the casing in a patterned mould. 

A layer of retreaded rubber is formed on the casing and consolidated by pressure. The tread pattern is cut out of the applied rubber either in the same operation or subsequently. Vulcanisation takes place in an autoclave. 

A pre-cured tread with pattern is prepared by moulding. A thin strip of unvulcanised cushion rubber compound is inserted between the casing and the tread rubber to form the bonding agent between the new and old components. The tread is then applied to the casing and consolidated by pressure. The cushion rubber is then vulcanised. This is also known as cold retreading . 

Autoclaves can be specifically designed to accept moulds for tyre retreading. 

Drum wheel test rigs are available to check the performance of tyres with retreads. 

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