Crepe rubber is coagulated

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature, but synthetic latices are common as well. In nature, latex is found as a wikt:milky, milky fluid, which is present in 10% of all floweri ...

that is rolled out in crinkled sheets and commonly used to make soles for shoes and boots but also a raw material for further processed

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...

products.

Processing

After the collection of the latex milk, sodium sulphite (Na₂SO₃) or

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

is added to prevent

coagulation Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a thrombus, blood clot. It results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The process of co ...

.''Manufacture of latex crepe rubber''
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, Raw Rubber Process Development & Chemical Engineering Dept., Rubber Research Institute of

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, January 2016 When the latex arrives in the factory,

sodium bisulphite Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO3. Sodium bisulfite is not a real compound, but a mixture of salts that dissolve in water to give solutions compose ...

(NaHSO₃) or sodium metabisulphite (Na₂S2O₃) are added to prevent enzymatic reactions and discoloring. Sodium para toluene thiophenate (an aromatic

mercaptan In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl grou ...

) is often added as a

bleach Bleach is the generic name for any chemical product that is used industrially or domestically to remove color from (i.e. to whiten) fabric or fiber (in a process called bleaching) or to disinfect after cleaning. It often refers specifically t ...

ing agent.

Colloidal A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others exten ...

latex is then mixed with

formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid. It has the chemical formula HCOOH and structure . This acid is an important intermediate in chemical synthesis and occurs naturally, most notably in some an ...

to cause it to coagulate. The coagulum is processed in a "creping battery", a series of machines that crush, press, and roll the coagula. The sheets are then hung in a heated drying shed and, after drying, sorted by grade and packed for shipping.

Types

There are several types and grades of rubber crepe, mainly distinguished by the grade and pre-processing of the latex used in their manufacture. *Pale latex crepe (PLC) is a premium grade, made from raw field latex. *Estate brown crepe (EBC) is made from "cup lump" (raw, naturally coagulated rubber from the collection cup) and other coagula. *Re-milled crepe is made from "wet slab coagulum" (cured latex, still wet from the coagulation tanks), latex sheets (unsmoked) and cup lump. *Smoked blanket crepe is made from thick sheets of latex that have been processed in a smoker. *Flat bark crepe is made from scraps and other poor quality raw product.

Gallery

File:YosriMesinGetahBunga.jpg, Hand-powered latex creping machines File:RemovingCoagulumFromCoagulatingTroughs.jpg, Removing coagulum from coagulating troughs File:CrepingBattery.jpg, Creping battery File:MillingHoneyColoredCrepe.jpg, Milling honey-colored crepe File:MillingWhiteCrepe.jpg, Milling white crepe File:SpoolingCrepeFromLastFinishingMill.jpg, Spooling crepe from last finishing mill File:SmoothCrepeSpooledForTransferToDryers.jpg, Smooth crepe spooled for transfer to the drying shed File:LowQualityWetColagulumCrepeBlanket.jpg, Wet coagulum crepe blanket File:SmallholdersSheetinDryingShed.jpg, Smallholder's sheet in a drying shed File:WhiteCrepeHangingInDryingShed.jpg, White crepe hanging in a drying shed File:LaminatingWhiteCrepeForSoleCrepe.jpg, Laminating white crepe for sole crepe File:LaminatingHoneyColoredCrepe.jpg, Laminating honey-coloured crepe for sole crepe File:SoleCrepeInspectionAndPacking.jpg, Sole crepe inspection and packing

References

{{reflist Rubber