Natural rubber latex consumption

The current world consumption of examination gloves is about 12 X 10 of which some 8 X 10 are used in USA. This product is therefore the largest single item, in tonage terms, made from natural rubber latex (1). 

In 1994, the worldwide consumption of rubber was approximately 14.5 million tons a year, of which about 40% consisted of natural rubber. Natural rubber is produced as latex by tropical rubber trees (Hevea brasiliensis). It is processed locally and therefore the quality of natural rubber fluctuates remarkably [ 140]. Due to increasing demand for rubbers, combined with a decreasing production capacity in Asia and a vast increase in labor costs, the price of natural rubber is still rising sharply. In 1990-1994, the average price of natural rubber was about 0.38 /lb, while in 1996 it was already over 0.80 /lb. The remaining 60% of the articles were manufactured from synthetic petroleum-based rubbers such as isoprene rubber, styrene-butadiene rubber, chloroprene rubber and polyurethanes. The quality of synthetic rubbers is constant, and their price varies between 2 and 5 US per kilogram [137-140]. 

The largest use of natural rubber is in the manufacture of tires. Over 70 percent of its consumption is in this area. The next largest use is as latex in dipped goods, adhesives, rubber thread, and foam. These uses account for approximately another 10 percent. The remainder is used in a variety of applications such as conveyor belts, hoses, gaskets, footwear, and antivibration devices such as engine mounts. 

Natural rubber accounts for about 25% of total rubber consumption. It is produced from the Hevea brasiliensis tree, being formed by isoprene units with cis-1,4 links. Natural rubber is used in tyres and for retreading, latex, mechanical goods, etc. 

In a broad sense, polymer dispersions include both synthetic polymer dispersions and natural rubber (Table 6.1 ).The yearly production of synthetic polymer dispersions is about 10% of the overall polymer consumption [1]. Synthetic polymer dispersions are produced by emulsion polymerization. About half of these polymers are commercialized as waterborne dispersions. Carboxylated styrene-butadiene copolymers, acrylic and styrene-acrylic latexes and vinyl acetate homopolymer and copolymers are the main polymer classes (Table 6.2). The main markets for these dispersions are paints and coatings (26%), paper coating (23%), adhesives (22%) and carpet backing (11%) [2]. Polymer dispersions have also found an interesting market niche in biomedical applications (diagnosis, drug delivery and treatment [3]). 

NR belongs to a class of compounds known as elastomers [5]. NR was used for centuries by the Mayans in the Western hemisphere before it was introduced into Europe by Columbus. The term rubber was, however, coined by Joseph Priestly. NR is indispensable in our daily lives. The main uses of NR are concentrated in four key areas, namely medical devices, industrial products, domestic and recreational goods, and foremost automobile products. The current elastomer consumption in the world is 18 million t per year [6]. NR supplies about one-third of the world demand for elastomers. It is also used as an industrial raw material. NR is a naturally occurring elastomeric polymer of isoprene (2-methyl-l,3-butadiene). It can be extracted from latex of only one kind of tree, Hevea braziliensis. Hevea rubber is produced in many tropical regions of Southeast Asia, Africa and Central and South America. There is practically only one other potential source of NR, that is the guayule shrub (Parthenium argentatum). 

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