ESBR latex

Some ESBR plants also produce latex as a finished product. The polymerisation plants are used to produce basic latex which has a low solids content and a small particle size. For practical and economic reasons, it is necessary to increase the solids content of the latex. Straightforward evaporation of the base latex only allows a solids content of around 50 % to be reached before the viscosity becomes too high. This problem can be overcome by increasing the particle size in an agglomeration process. Subsequent evaporation of the agglomerated latex enables solids contents of more than 60 % to be achieved whilst maintaining a practical viscosity. These high solids latices are principally used to produce foam mattresses and pillows, foam-backed carpets, adhesives and sealants. 

In the case of plants that produce ESBR latex as a finished product, it could be possible use different technical parameters and different processes in addition to those described in Table 7.2 

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In converting ESBR latex to the dry mbber form, coagulating chemicals, such as sodium chloride and sulfuric acid, are used to break the latex emulsion. This solution eventually ends up as plant effluent. The polymer cmmb must also be washed with water to remove excess acid and salts, which can affect the cure properties and ash content of the polymer. The requirements for large amounts of good-quaUty fresh water and the handling of the resultant effluent are of utmost importance in the manufacture of ESBR and directly impact on the plant operating costs. 

The quahty of the water used in emulsion polymerization has long been known to affect the manufacture of ESBR. Water hardness and other ionic content can direcdy affect the chemical and mechanical stabiUty of the polymer emulsion (latex). Poor latex stabiUty results in the formation of coagulum in the polymerization stage as well as other parts of the latex handling system. 

Snap. A critical ingredient for emulsion polymerization is the soap, which performs a number of key roles, including production of oil (monomer) m water emulsion, provision of the loci for polymerization (micelle), stabilization of the latex particle, and imputation of characteristics to the finished polymer. Both fatty acid and rosin acid soaps, mamly derived from tall oil, are used in ESBR,... 

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