Microporous phenolic resin separator DARAK

In the second half of the 1960s, at the same time but independently, three basically different plastic separators were developed. One was the polyethylene separator [16] already referred to in starter batteries, used only rarely in stationary batteries, but successful in traction batteries. The others were the microporous phenolic resin separator (DARAK) [18] and a microporous PVC separator [19], both of which became accepted as the standard separation for stationary batteries. They distinguish themselves by high porosity (about 70 percent) and thus very low electrical resistance and very low acid displacement, both important criteria for stationary batteries. 

In Europe, with the economic upswing after 1950, forklifts with batteries came into use - a development which met less acceptance in the U S A for various reasons, among them low fuel cost. In this appHcation rubber separators and microporous PVC (Porvic I) were finally able to replace wood veneers, until from around 1975 they again met strong competitors in the new separators aheady mentioned made of phenolic resin (DARAK), PVC, and mainly polyethylene (Daramic). Today this market is dominated by the polyethylene separator, as is shown in Table 11.4. The annual growth of this market is 2-3%, but with large fluctuation based on prevailing economic conditions. 

---