Tire cord, steel

World production of resorcinol in 1985 was around 25,000t. Resorcinol resins, obtained from resorcinol and formaldehyde, are used as special adhesives in the timber industry and as tackifiers, usually in combination with vinylpyridine latex for steel cord tires. 

Another market appHcation for naphthenic acid is the tire industry, where cobalt naphthenate is used as an adhesion promoter (see Adhesives Tire cords). Cobalt naphthenate improves the bonding of brass-plated steel cords to mbber, presumably by suppressing the de-zincification of brass (50). Its first reported use was in 1970 and the first patent for its use was issued in 1975 (51). About 900 t of cobalt naphthenate is used worldwide as an adhesion promoter, half of it in North America. The unit value fluctuates between 8.75—13.25 /kg because of the volatility of cobalt prices. Although it is the industry standard, the use of cobalt naphthenate is declining with the advent of more economical high metal-containing substitutes. 

Tire Cord. Melamine resins are also used to improve the adhesion of mbber to reinforcing cord in tires. Textile cord is normally coated with a latex dip solution composed of a vinylpyridine—styrene—butadiene latex mbber containing resorcinol—formaldehyde resin.. The dip coat is cured prior to use. The dip coat improves the adhesion of the textile cord to mbber. Further improvement in adhesion is provided by adding resorcinol and hexa(methoxymethyl) melamine [3089-11 -0] (HMMM) to the mbber compound which is in contact with the textile cord. The HMMM resin and resorcinol cross-link during mbber vulcanization and cure to form an interpenetrating polymer within the mbber matrix which strengthens or reinforces the mbber and increases adhesion to the textile cord. Brass-coated steel cord is also widely used in tires for reinforcement. Steel belts and bead wire are common apphcations. Again, HMMM resins and resorcinol [108-46-3] are used in the mbber compound which is in contact with the steel cord to reinforce the mbber and increase the adhesion of the mbber to the steel cord. This use of melamine resins is described in the patent Hterature (49). 

Insoluble Sulfur. In natural mbber compounds, insoluble sulfur is used for adhesion to brass-coated wire, a necessary component in steel-belted radial tires. The adhesion of mbber to the brass-plated steel cord during vulcanization improves with high sulfur levels ( 3.5%). Ordinary rhombic sulfur blooms at this dose level. Crystals of sulfur on the surface to be bonded destroy building tack and lead to premature failure of the tire. Rubber mixtures containing insoluble sulfur must be kept cool (<100°C) or the amorphous polymeric form converts to rhombic crystals. 

Silica. The main uses of siUca are in the treads of off-the-road tines for improved chunking and tear resistance and as a component of the bonding system for brass and 2inc-plated steel cord. These are commonly used in radial passenger and tmck tire belt skim stock. In addition the body pHes of steel radial tmck tires, hoses and belts, and footwear use significant volumes of siUca as a reinforcing filler. 

The carcass ply/pHes coat compouad fuactioas are basically the same as the steel breaker compouad. Normally ia the steel belted PCT the ply is textile cord of polyester or rayoa fabrics which are soft and flexible. The tmck radial steel tire normally uses a steel cord ply. Earthmover tires are of two basic constmctions, ie, radial usiag steel and bias usiag textiles (see Tire cords). 

Steel tire cord provides a unique combination of strength, ductihty, dimensional stabiUty, resistance to fatigue, mbber adhesion, and consumer value that led to a dramatic increase in steel cord consumption for the last decade (46,47). 

Standard Test Methods for Steel Tire Cord. ASTM standard D2969-92 includes test methods for steel cords that are specifically designed for use in the reinforcement of pneumatic tires. It describes test methods determining steel cord constmction, break strength, elongation at break. 

Standard Test Method for Adhesion Between Steel Tire Cords and Rubber. Steel cords are vulcanised into a block of mbber and the force necessary to pull the cords linearly out of the mbber is measured as adhesive force. ASTM method D2229-93a can be used for evaluating mbber compound performance with respect to adhesion to steel cord. The property measured by this test method indicates whether the adhesion of the steel cord to the mbber is greater than the cohesion of the mbber, ie, complete mbber coverage of the steel cord or less than the cohesion of mbber (lack of mbber coverage). 

Adhesives in the Tire Industry. Cobalt salts are used to improve the adhesion of mbber to steel. The steel cord must be coated with a layer of brass. During the vulcanization of the mbber, sulfur species react with the copper and zinc in the brass and the process of copper sulfide formation helps to bond the steel to the mbber. This adhesion may be further improved by the incorporation of cobalt soaps into the mbber prior to vulcanization (53,54) (see Tire cords). 

Typical requirement figures of coated steel cord or fabric cord sheets as applied in the tire industry are ... 

The tires account for two-thirds by mass of the elastomer used in an automobile [1]. However, the usage of lightweight steel cord and technical improvements in elastomeric materials have reduced their weight by -20% and this in turn has led to an overall reduction in vehicle weight, concomitant fuel savings, and better road holding property. 

N326 82 72 Tire carcasses, steel cord adhesion compounds, mechanical rubber goods... 

Vinylpyridine is used in the terpolymer latex component of tire cord dips to improve the bonding of textile to rubber. Rubber hres built with steel cord, however, do not require vinylpyridine latex-based adhesives for the steel belt, Therefore, the consumption of vinylpvridines may be affected in the future,... 

Figure 17.5 Scheme of the pilot plant for the pyrolysis of whole scrap tires. 1 steel wall with fireproof walling 2 fluidized bed 3 tiltable grate 4 radiation fire tubes, two layers, third layer inlet tubes for fluidizing gas 5 nozzles to remove sand and metal 6,8, and 9 flanges for observation and repairs 7 gas-tight lock 10 shaft for steel cord... 

The pyrolysis zone itself, i.e. the fluidized sand bed, indirectly heated by seven fire tubes in two layers, has a fireproof wall. The whole tires roll through a gas-tight lock into the reactor. A tiltable grate is extended into the fluidized sand to remove the steel cord... 

It can be seen that under these conditions high amounts of aromatics are produced. The benzene content is 12.2 wt% at a pyrolysis temperature of 740°C and 24.75 at 780°C. Other main components of the PE pyrolysis (780°C) are methane, ethylene, and propene as gas and toluene, naphthalene as aromatics. The amount of carbon soot is low. Tire pyrolysis produces mainly carbon black (filler), gas, and aromatics. Steel cord is one of the other main products if whole tires are fed. 

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