The beginning of
Natural Rubber
Introduction
National Rubber (NR) is a produce from the crop harvested from rubber tree both in the latex form as well as in latex coagulum form. Latex is a creamy milky white dispersion of rubber in water and latex coagulum is the natural coagulated of latex from the tapping tree panel collecting in a cup as we normal called it cup lumps and shell scrap.
The most important forms in which NR is processed and marketed in the world are as followings:
- Sheets
- Block rubber, Technically Specified Rubber
- Latex Concentration
- Crepes
Thailand is the biggest producer and exporter of NR in the world. Currently, the first 3 types of NR processed are accountable of almost 97% of the total NR produced in Thailand and remained around 3% in the crepes form. Among the 3 types, Sheet and block rubber are dominant type of dry NR available in the world market.
Natural rubber was collected from the small holders in various forms and separated into specific grades based on a visual inspection. One of which is called unsmoked sheet. Once these sheets went to the factory and gone through the smoking process, the smoked sheet were then compressed into various sized bales. These grades are still best for certain applications and are now available in a smaller packed similar to TSR type packaging.
This material consists of deliberately coagulated rubber sheets, completely dried using smoke. These sheets are then graded into 5 grades according to their colors, consistency and observed impurities. However currently the grading have reduced to 4 types. The pureness is RSS1 then RSS3 then RSS4 and RSS5. RSS is sold in standard pack of 111.11 kgs or designated for small bales of 33.33 kgs or 35 kgs. wrapped in dispersible polyethylene bag. Crate size is 1,200 kgs or 1,260 kgs.
RSS are used when extra tough though rubber is needed (due to extensive cross linking). Some applications are tires, tank liners, industrial products, etc. RSS is generally more difficult to process than TSR.
Standard grade is 60 % concentrated latex- specification for general purpose requirement. They have been technically specified for many years in certain countries and the establishment of international standards arrived from the measure of agreement that has been achieved. The national and international standards are substantially identical or slightly different in their requirement.
The TSR are mostly the block types made by adopting to the new methods of processing.
Most natural rubber produce today conforms to the TSR scheme. This scheme requires standardized technical tests to be performed on every grade of rubber when compared to other type of NR as visually graded. This block rubber also have a standard packing in either 33.33 kgs or 35 kgs per bale. And all the block rubber must also conform to their national technical specification.
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