Continuous vulcanisation

Report 92 Continuous Vulcanisation of Elastomer ProfUes, A. Hill, Meteor Gummiwerke. Report 119 Rubbers in Contact with Food, M.J. Forrest and J.A. Sidwell, Rapra Technology Ltd. 

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. 

A heated mixture of low melting point alloys or of chemical salts used to provide the heat for curing extrudates in one method of continuous vulcanisation. 

Trade name for an apparatus used for the continuous vulcanisation of belting, matting, etc. Rotomill... 

The red form of mercuric sulphide once popular as an inorganic colouring agent for rubber. Vertical Continuous Vulcanisation... 

Continuous vulcanisation units are of a number of types. See also the section on Cable Manufacturing. 

Conveyor systems are applied in a number of areas in the rubber industry. The types used can range from simple canvas belt conveyors used for haul-off from conventional extruders, to systems used for transport and cooling of profile products, both in and emerging from continuous vulcanisation units. The latter types have to be resistant to the temperatures used in such systems and are variously constructed from glass fibre-reinforced polytetrafluoroethylene or a silicone rubber covered belt. 

Microwave units are available for both continuous vulcanisation systems, for preheating of moulding blanks for compression and transfer moulding, and for heating large bales of frozen rubber prior to mixing. 

Continuous vulcanisation of rubber based products such as thin conveyor belting, flooring and similar can be achieved using a large rotating heated drum. Pressure is exerted to the product by means of a continuous stainless steel belt which presses the sheet to the surface of the drum. The belt is also heated from its reverse side to give optimum heat transfer to the vulcanising rubber. 

Special rotary curing units are designed for continuous vulcanisation of V-belts. This method eliminates any areas of overcure and moulded in stresses, which result from methods using presses vulcanising belts in sections. Belt and tension roller pressure release mechanisms allow for easy unloading and loading of the belts. 

Report 92 Continuous Vulcanisation of Elastomer Profiles, A. Hill, Meteor Gummiwerke. 

K-8 120UC and 10 minutes (stage I), 200°C and 6 hours (stage 45 6.0 250 From -50 to +250 °C To produce heat-resistant insulating pipes by continuous vulcanisation... 

First, the peroxide type can be determined using peak onset and peak position data for the exothermic peroxide decomposition. This information is useful for the prediction of decomposition products to be removed from the cable in subsequent process and also in the continuous vulcanisation plant used to effect the heating under pressure and to carry out cross-linking in the production process. Build-up of these decomposition products in the plant may otherwise cause a number of safety hazards. 

This gives a very fast cure rate and is used in the continuous vulcanisation of both solid and cellular profiles, particularly in the latter to obtain a sufficiently fast cure rate for good skin formation. Disadvantages arising from the use of this material are poor processing safety and a lacrimatory effect on the operator s eyes necessitating efficient ventilation on the curing unit. 

Compression set resistance can be improved considerably in all types of polychloroprene by effecting a very tight cure. Thus, long cure times, high curing temperatures and high accelerator concentrations are beneficial. While acceleration with ethylene thiourea (1 phr) or diethyl thiourea (1 phr) for fast continuous vulcanisation will meet most requirements, for the most demanding specifications it may be necessary to use trimethyl thiourea (2 phr) and epoxy resin (1 phr) or tributyl thiourea (3-4 phr). 

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