Brass adhesion additives

Diffusion of metallic copper domains to the surface following oxidation by R—S c is not affected, as Cu + ions migrate along grain boundaries of the ZnO layer. Thus if a cobalt salt is used, formation of copper sulfide at the cord surface will be accelerated, whereas ZnS generation will be hindered (Figure 14.18). This review is necessarily brief, and the reader is encouraged to consult additional references for further detail on the chemistry of rubber-brass adhesion (Bekaert Corporation, 2004 van Ooij, 1984). 

Reviews on the subject of brass-plated steel cord-natural rubber adhesion have been written by van Ooij who has done much of the work in the field. Van Ooij [46] has given a model for rubber-brass adhesion, in which a copper sulfide layer forms on the brass before the onset of crosslink formation. The thin film of copper sulfide has good adhesion and cohesion. In addition, the film is so porous that rubber molecules can become entangled with it. It is not required that the film forms simultaneously with the formation of crosslinks during vulcanization but, rather, it is required that the copper sulfide film be completely formed before crosshnking starts. Indeed, adhesion between brass-plated steel and natural rubber can frequently be improved by the use of the retarder, CTP [4] or by using a more delayed action accelerator such as N-dicyclohexylbenzothiazole-2-sulfenamide (DCBS) [47]. 

It has been demonstrated previously that such additions can increase the strength of rubber-brass adhesion considerably. In this research it was established that polysulphides are only weak crosslinking agents for unsaturated rubber by themselves. In the presence of sulphenamide accelerators, such as OBTS, polysulphides, in amounts of 0.5 - 1 phr, activate the sulphur vulcanisation. However, the reversion process (crosslink breakdown) is not accelerated. A favourable effect on the physicomechanical properties of the vulcanisate was also reported. 

Soft-soldering of copper, iron, steel, and brass objects of large size is usually accomplished by the use of a burner or hand torch, with an acid flux—frequently a concentrated aqueous solution of zinc chloride and ammonium chloride (2 1 ratio)—brushed onto the hot metal concurrently with the addition of solder. Initially, heat should be applied around the area to be soldered but not directly on the region to be soldered. If the region to be soldered is heated too much without the application of flux, an oxide coating will form that can make proper surface adhesion impossible. The surfaces to be joined should be pretinned if possible, and excess solder is shaken off or wiped off with a cloth. The two surfaces to be joined are then placed in contact and heated with the torch until the solder begins to flow more solder is then added as required, and the pieces are allowed to cool undisturbed. The finished work should be washed thoroughly with water to remove the flux. 

Phenolic novolak resins and high styrene SBR resins are used for reinforcing and increasing the hardness and modulus of rubber compounds. Resorcinol novolak resins are used as a part of the adhesion system between rubber and brass plated steel cord or organic fibers. Both phenolic novolak and resorcinol novolak resins require the addition of a methylene donor such as hexamethoxymethylmelamine (HMMM) or hexamethylenetetramine (HMTA) to fully crosslink and become a thermoset. Phenol, alkyl phenols, and resorcinol can be reacted in bulk or in a polymeric formulation with methylene donors. Typical donors are 2-nitro-2methylpropanol (NMP), HMTA, and HMMM, used to produce a thermoset resin network in the... 

Silicas, which are in competition with carbon blacks as functional fillers for plastics and rubbers, have one significant advantage their white color [62]. The most important role of silicas is as elastomer reinforcements, inducing an increase in the mechanical properties. Other functions, in addition to their use as antiblocks for PE, PP, and other films, are (a) to promote adhesion of rubber to brass-coated wires and textiles, (b) to enhance the thermal and electrical properties of plastics, (c) in accumulator separators, and (d) as rubber chemical carriers. 

Many rubber composites require that the rubber adheres permanently to a substrate such as steel, brass, textiles or other media. There are a number of established proprietary additives, which may be added to the rubber compound, which function in this capacity. The resorcinol-formaldehyde-silica (RFS) system is commonly used to achieve adhesion to metals. This system relies on the interaction of resorcinol (or a resorcinol donor), a methylene donor snch as hexamethylene tetramine and precipitated silica. Other systems that may rely on cobalt complexes or blocked isocyanates may also be used. 

If the compound contains an active cobalt-containing adhesion promoter, metallic cobalt precipitates onto the brass surface and also forms the Me-S bond, in addition to copper. Zinc can also form this bond, but does not bond to rubber, as the zinc sulphide growth rate is low (see stage IV). The role of cobalt in NR skim stocks is thus to activate (or... 

The Saret 633/peroxide-cure system also promotes good adhesion to other untreated metals, including aluminium, zinc, brass, and stainless steel. This is illustrated in Figure 8.9 for EPDM containing 10 phr Saret 633. In each case, shear adhesion increased with the addition of Saret 633, compared with peroxide alone. 

Nitrile rubber Bonding plastic films to metals, and fibrous materials such as wood and fabrics to aluminum, brass, and steel also, bonding nylon to nylon and other materials Most stable synthetic-rubber adhesive, excellent oil resistance, easily modified by addition of thermosetting resins Does not bond well to natural rubber or butyl rubber... 

The influence of polymers and additives on the service life of non-tread tyre components is discussed on the basis of results obtained from studies of inner liner, belt and sidewall compounds. The effects of the bromine content of bromobutyl rubbers on the performance of inner hners, and of sulphenamide accelerators on the adhesion of NR belt compounds to brass coated steel cords were investigated. The mechanical properties and ageing and ozone resistance of black sidewall compounds consisting of NR blends with neodymium catalysed polybutadiene protected with different antioxidants and antiozonants were also evaluated. 5 refs. 

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. 

Cobalt salts such as cobalt stearate are commonly used as rubber compound additives to supplement the HRH components for better rubber-to-brass-plated steel tire cord adhesion. 

HRH Systems. A review of currently available bonding agents such as HRH and modifications thereof, is given by Weaver." HRH designates the use of hexamethylenetetramine (hexa), resorcinol, and a hydrated silica as additives to rubber in order to improve adhesion to brass coated wire. Normally about 1.5 phr hexa, 2.5 phr resorcinol, and 15 parts of silica are added to a wire skim stock. Pre-... 

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