Silicone liquid polymer processing system

Fabricated silicone rubber parts are traditionally made from high consistency silicone gum stock. Because of the stiffness of the gum stock, the material must be worked with rubber masticating equipment and preformed before fabrication. A new fabricating process using a low consistency liquid silicone rubber was introduced by Dow Corning Corporation recently (1, 3). This process is called liquid polymer system (LPS). 

Extrusion Coating - The use of liquid silicone rubber in coating application requires less energy than conventional dispersion coating processes. Solventless material, rapid cure time, absence of by-products and the elimination of multiple passes all contribute to the reduced energy demand of the liquid polymer system. 

Silicone adhesives are generally applied in a liquid and uncured state. It is therefore the physical and chemical properties of the polymers, or more precisely of the polymer formulation, that guide the various processes leading to the formation of the cured silicone network. The choice of the cure system can be guided by a variety of parameters that includes cure time and temperature, rheological properties in relation with the application process, substrates, the environment the adhesive joints will be subjected to and its subsequent durability, and of course, cost. 

Natural Rubber and Synthetic Polyisoprene Polybutadiene and Its Copolymers Polyisobutylene and Its Copolymers Ethylene-Propylene Copolymers and Terpolymers Polychloroprene Silicone Elastomers Fluorocarbon Elastomers Fluorosilicone Elastomers Electron Beam Processing of Liquid Systems Grafting and Other Polymer Modifications... 

Many of the polymers such as caprolactam, silicone, urethane, and polyester are multicomponent reactive liquids that may be molded by the reaction injection process which is particularly suitable for large area pieces such as auto body parts, furniture, and housing sections, because of the fast cycle and low mold clamp pressure requirement. This system greatly diminishes the capital investment requirement for such large parts. A 5000-ton conventional injection press is presently the largest and it costs 1,000,000. An automobile fender would need a 12,000 ton press costing 2,000,000 by the conventional injection process with reaction injection equipment cost might be one tenth of the machine cost for the older process. 

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