Extruder liquid-curing-medium

Any method of vulcanising rubber products which proceeds without interruption from start to finish as compared to the method of vulcanising separate batches of products or sections of a product. Continuous vulcanisation processes include the cold curing of proofed cloth, the vulcanisation of belting and flooring, of cables and certain extruded products by either the Liquid Curing Medium, Fluid Bed, Microwave, or Hot Air techniques. 

Extrusion with the aid of a vacuum applied to the screw. The process is applied particularly in the preparation of extrudates to be vulcanised by either the liquid curing medium or fluid bed techniques. It assists in removing the volatiles from the compound and thus improves the quality of the extrudate. 

Liquid Cure Medium (LCM) uses a eutectic mixture of salts to heat the extrudate. The molten salt bath usually has a metal conveyor to keep the rubber eompound submersed. This method has good heat transfer to the rubber. However, cleaning salt off the extrudate can be difficult and satisfactory disposal of dilute salt rinse is beeoming increasingly difficult. This method is advantageous for articles with the low compression set obtained by using peroxides. Sulfur can be used as a coagent to minimize surface tack. Deformation problems versus other atmospheric methods are sometimes minimized. 

This system involves the use of some form of heating by air or steam in a chamber in a manner such that the vulcanization occurs immediately after the rubber is formed in an extruder or calender. This is a suitable process for extruded profiles and calendered sheets and conveyor belts. Liquid curing method (LCM) is also a continuous process which involves the use of suitable hot liquid baths in which extruded profiles can be passed through and vulcanized continuously. Items can be cured rapidly at temperatures from 200°C to 300°C however the compounds must be suitably designed to prevent porosity as this is a common problem with any extrudate. Suitable materials for curing medium includes bismuth-tin alloys, an eutectic mixture of potassium nitrate and... 

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