Rubber steel tire cord adhesion

Originally the tire industry used straight resorcinol as the R component in the HRH compound for good steel tire cord adhesion. However, with environmental and safety concerns in handling free resorcinol in the rubber mixing operations, resorcinol is now used in the tire and rubber industry as a solid resorcinol formaldehyde resin (or RF resin), which is somewhat safer to work with. 

Resorcinol formaldehyde resin is a vital ingredient in the HRH rubber adhesion compounds (such as wire coat stock or breaker stock) in order to achieve good rubber-to-brass-coated steel tire cord adhesion. 

Resorcinol formaldehyde resin is an extremely important component of the HRH system for achieving good rubber-to-brass-plated steel tire cord adhesion. This RF resin functions as a resorcinol donor in the rubber compound that reacts with the... 

Cobalt stearate (or other cobalt salts) is sometimes used as rubber compounding ingredients to improve rubber-to-brass steel tire cord adhesion under certain circumstances. Commonly, a careful use of cobalt soap such as cobalt stearate may actually improve certain adhesion characteristics if it is used properly. Since rubber-substrate adhesion is a variable phenomenon, many technologists feel that the contribution of cobalt is to improve the reliability of the adhesion rather than the adhesion per se. Over the past three decades, this reliability of adhesion has been found to be of much importance in the manufacture of steel-wlre-reinforced tires and other rubber products. Thus the end result is a greater consistency of product quality, with fewer production rejects and subsequent failures in actual service. 

While it is possible to get some adhesion using HRH without the hydrated silica, many times insufficient adhesion is imparted. Thus hydrated precipitated silica is a very important component of the HRH system if it is used to achieve adequate rubber-to-metal adhesion. This is particularly true with rubber-to-brass-coated steel tire cord adhesion where there are very few practical alternatives. 

Resorcinol reacts with formaldehyde to produce RF resin for HRH systems in rubber compounds to achieve good rubber-to-metal steel tire cord adhesion, as well as good textile (polyester, nylon, rayon) cord adhesion. 

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). 

ASTM D2229, 2004. Standard test method for adhesion between steel tire cords and rubber. 

Diazoaminobenzene (DAAB) is used as a chemical intermediate, a complexing agent, and as a polymer additive. DAAB has been used to promote adhesion of natural rubber to steel tire cords. It has also been used as a blowing agent in the production of a foamed polymeric material. In addition, DAAB is used in the manufacture of dyes and insecticides. DAAB is present in cosmetics, pharmaceuticals, and food products, as a dye contaminant in D C Red No. 33, FD C Yellow No. 5, and FD C Yellow No. 6. 

One of the main points of debate w ith the above methods is the stress distribution due to gripping the rubber block. Nicholson ct al. [41.42] used a test with two cords embedded in the block of rubber and avoided holding the block in one grip of the testing machine. Further analysis was made by Brodsky [43], who used three cords. Ellul and Emerson [44.45] used cords embedded in steel enclosed rubber cylinders with alternatively hot and cold bonding. Ridha et al. [46] have calculated the stress fields in tire cord adhesion test pieces, and Mollet [47] has compared the various methods. 

The adhesion between rubber and brass-plated steel (e.g., steel tire cords for belted radial tires) has been the subject of much study and speculation. Brass plating is the major method of obtaining adhesion between natural rubber and the steel of tire cords. Over the years there has been much speculation about its mechanism, but there is agreement on one aspect of the adhesion of natural rubber to brass-plated steel the actual adhesion between the natural rubber and the brass-plated cord, formed in situ during the vulcanization process, is an interfacial layer of sulfides and oxides of copper (Buchan, 1959 van Ooij, 1979, 1984). 

Recently, van Ooij et al. have reviewed adhesion of steel tire cord to rubber (van Ooij et al., 2009). The authors reviewed the literature extensively and provided an updated model for adhesion to brass-plated tire cord, which incorporated observations made by many techniques. They discussed the effects of different compounding ingredients and the possible alternatives to the current brass coatings. They note that the use of cobalt compounds improves the adhesion between rubber and brass-coated cords, but new adhesion promoters have been developed as replacements for Co, or for combined use with Co. They also discussed the use of phenolic-resin adhesion promoters. They describe the various techniques that have been developed to study the rubber-brass interface and its aging mechanism. 

The adhesion between rubber and brass-plated steel (e.g., steel tire cords for belted radial tires) has been the subject of much study and speculation. 

Although this paper does not deal with the tire cord adhesives, the use of the steel belt in the newer radial tires and in truck tires has Indicated a need for better adhesive systems and methods of testing the steel cord to rubber adhesion. ... 

Zinc oxide is essential in rubber technology because it is the most commonly used activator for sulfur cure systems. Just about every rubber compound that uses sulfur as the vulcanizing agent will most likely contain a small amount of zinc oxide to activate the cure. Also zinc is alloyed with copper to form brass. Special brass-plated steel tire cord is a primary reinforcing material for producing steel-belted radial tires. The brass coating of the steel tire cord enables very good rubber-to-metal adhesion. Therefore, zinc metal and zinc oxide are very important to the rubber industry. 

Cobalt is important to the rubber industry to promote rubber-to-metal adhesion. The use of cobalt salts, such as cobalt stearate or cobalt naphthenate as compounding additives, will promote better adhesion between cured rubber and brass-coated steel tire cord. 

Steel tire cord is usually brass plated in order to achieve good rubber-to-metal adhesion. Also, tire bead wire is commonly plated with bronze to achieve rubber-to-metal adhesion. The steel cable used in rubber mining belts may also be brass or bronze plated. 

DCBS is a commonly used sulfenamide accelerator that is selected when good scorch safety is needed combined with a relatively slow cure rate. The selection of DCBS is particularly useful when a slow cure rate is needed to optimize rubber adhesion to brass-plated steel tire cord. 

Many times DCBS is selected as the primary accelerator when a slow cure rate is needed to match the slower adhesion chemistry of rubber-to-brass adhesion for steel tire cords. Other commonly used sulfenamide accelerators cure faster than DCBS. 

Ammonia reacts with carbon dioxide to form urea, which is a feedstock for the production of melamine, from which the HMMM adhesion promoter for the HRH adhesion system for rubber to steel tire cord is derived. 

Sodium carbonate reacts with natural silica at high temperatures to produce sodium silicate (water glass). An aqueous solution of sodium silicate, when treated with an acid, will precipitate silica with a fine particle size when conditions are controlled properly. This hydrated precipitated silica is commonly used in rubber compounding to achieve a more resilient (lower energy loss during flexing) cured rubber and to achieve better adhesion of rubber to steel tire cord. 

Zinc metal is also used to alloy with copper to form brass. Brass-coated steel tire cord is used to achieve good rubber-to-metal adhesion. 

The performance of steel belted tires, as with tires reinforced with other fibers, is dependent to a large extent on the adhesive bond between the tire cord and the rubber in the skim stock surrounding the cord. The use of a thin brass layer on steel tire cord is the major adhesive... 

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. 

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,... 

Other types of coupling agents include 1,2-diketones for steel,27 nitrogen heterocyclic compounds such as benzotriazole for copper,28,29 and some cobalt compounds for the adhesion of brass-plated tire cords to rubber.30... 

These copolymers have a wide range of possible applications. DHA-co-4VP and DHA-co-NVP copolymers are excellent for rubber-steel and rubber-polyester adhesive systems respectively. In addition, quaternized DHA-co-4VP copolymers promote strong adhesion of rubber to polyester tire cord in vulcanized composites. 

The thin coating of brass on the steel cord is the primary adhesive used in steel-to-rubber bonding. The quality of this bonding system built up during vulcanization of, for example, a radial tire will influence the performance of the steel ply or steel belt in the tire and, ultimately, the durability of the product. Though the mechanism of bond formation in rubber-steel cord adhesion is very complex, a brief review of the current understanding of wire to rubber adhesion is presented. 

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