Production of Latex Concentrate

Whole field latex contains 30% to 40% total solids by weight. Roughly 10% of whole field latex is concentrated rather than made into dry rubber. Concentration avoids the cost of shipping water. The largest proportion of concentrate is exported to consumer industries for conversion into such products as adhesives, gloves, elastic thread, and prophylactics. 

Latex is concentrated to 60% to 68% dry rubber content. This is done by either centrifuging, evaporating, or creaming. By far, the most popular method 

Creamed latex is made by the use of a creaming agent such as ammonium alginate. The creaming agent helps form a rubber-rich layer at the top of the holding tank. This is a slow process several weeks may be required before the desired concentration is reached in the top layer, which is drawn off for shipment. Creamed latex has a minimum dry rubber content of 62% and is preferred by rubber thread manufacturers because of its good filterability. 

Most latex concentrate produced today would fall into one of the four types specified by ASTM specification D 1076 (1) centrifuged latex with normal ammonia, centrifuged with low ammonia, creamed latex with normal ammonia, and creamed with low ammonia. The minimum content for latex solids varies from 61.5% to 64.0% and dry rubber content minima from 60.0% to 62.0%. Total alkalinity is calculated as NH3 based on the water phase of the latex and is 1.6% minimum for normal ammonia latex, 1.0% for the minimum ammonia type. Lx)w-ammonia latex (often made with a second stabilizer) has less odor and requires less neutralization in subsequent processing, but other factors hinder its use. A very small amount of latex is vulcanized in the liquid state and sold for special compounding. 

---