Building tack

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. 

In the same way that natural mbber is predominandy used in blends, it is also predominandy used in tire manufacture. Its excellent building tack, low heat buildup, low rolling resistance, and good low temperature performance make it the polymer of choice for many parts of tire constmction, for both passenger and tmck vehicles. The effects of radiali2ation and demand for low rolling resistance and good low temperature performance have all tended to benefit natural mbber, especially in tmck tire constmction, as shown in Table 9. 

High initial tack. The adequate choice of butyl or PIB provides excellent building tack (ability to produce quick adhesion by applying low pressure). 

Their crystallization behavior compares with natural rubber, as follows (1) their rate of crystallization is more rapid and (2) their amount of crystallinity is temperature dependent, but considerably less strain dependent. These experimental rubbers have excellent green strength and building tack. 

Two additional properties that may depend on the strain induced crystallization behavior of NR are green strength and building tack. A comparison of the performance of the experimental high trans SBR s with NR was, therefore, carried out. 

Cross section of a tire body ply with controlled depth of partial cross-linking. 1, reinforcing cord fabric 2, skim coat 3, partially cross-linked skim coat by electron beam 4, building tack preserved 5, bleed cord. 

Tack (or building tack) A property of an elastomer or rubber compounds that causes two layers of compound that have been pressed together to adhere firmly in the areas of contact. It is very important for building tires or other laminated structures. 

Heat resistance of up to 200°C is achievable for special applications with proper compounding. Processing of this rubber is generally good except for the lack of building tack. This severely limits the use of EPDM in hand lay-up applications such as liners. However, with the use of proper solvents and adhesives this can be alleviated. 

Stickiness of a rubber to other rubbers. The building tack is important in tire production where layers of different rubber compounds are manually stuck together. 

Before World War II (1939-1945) natural rubber was used for practically all rubber applications. Natural rubber is preferred in many products because of its superior building tack, green stock strength, better processability, high strength in non-black formulations, hot tear resistance, retention of strength at elevated temperatures, better resilience, low heat build-up, fatigue resistance, and better dynamic properties. Rubber products are broadly classified as dry rubber products and latex based products [60]. 

Building tack Green strength Second step blow outs... 

Low building tack Even though used as a contact adhesive for many applications, the adhesive must be freshened with solvent before mating to assure good wet-out otherwise high contact pressure or the addition of tackifying resins to the formula is required. 

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