Natural rubber ribbed smoked sheet

In solid form, the natural rubber is graded according to the content of dirt remaining from the precipitation of latex at the plantation. Eight basic NR types have been traditionally recognized internationally. Only the so-called ribbed smoked sheets and the pale crepes are normally used for adhesives. The predominant grade system, the Standard Malaysian Rubber system, has been used since 1965. 

RSS Ribbed Smoked Sheet DPNR Deproteinized Natural Rubber. 

A major dry natural rubber type is ribbed smoked sheet. For this the coagulum is passed between pairs of even-speed steel rollers that squeeze the water out. The final set of rollers has channels cut in them so that the sheet emerging from them has a ribbed surface. The ribbed surface facilitates drying. This rubber is dried in smokehouses. The ribbed sheets are hung over poles mounted on trolleys. Rubber tree wood fires produce the smoke, which dries the rubber and gives the rubber some age resistance from its components such as cresols. Drying takes 48 to 96 hours, with entrance temperatures at about 40 °C and exit temperatures at about 60 °C. Some ribbed sheet rubber is dried in hot air out of contact with smoke. This produces a lighter colored rubber, which commands a premium and is referred to as air-dried sheets. 

Natural Rubber. Natural rubber (NR), all cw-1,4-polyisoprene, is available as the natural latex, but the major raw material for PSAs is the recovered solid, or baled gum rubber. The principal types of NR used for PSAs are pale crepe or ribbed smoked sheet, which is less expensive but of darker color. The baled rubber must be masticated to lower its molecular weight before use. 

Creep rubber n. Natural rubber of a pale- to dark amber color prepared by coagulating natural-rubber latex with acid, then milling this coagulum into sheets. The other basic form of solid natural rubber (i.e., ribbed sheet) is prepared by drying the latex on rolls in the presence of smoke. 

The process used to make rubber separators involves mixing precipitated silica, water, and natural rubber to create a thin film. The natural rubber is received in smoked sheets or slabs, and it is normally worked in various pieces of equipment so that the silica, laden with water, can be incorporated. This rubber, silica, and water mixture is then fed to an extruder to create a thin, uniform layer that is sufficiently malleable to be fed into a calendar stack, which has grooved voids in the roll that will create the rib structure. 

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