Liquid Paraffin - An Improved External Lubricant For Rigid PVC

摘要

The exact timeframe of the initial use of paraffin wax as an external lubricant in rigid PVC compounding is difficult to clearly identify; it appears that it was a trade secret that leaked out into industry and was rapidly accepted as common practice. Paraffin wax with a melt point of 165deg F made its commercial appearance on the PVC scene during the late 1950s or early 1960s. During the early 1980s prilled paraffin wax was introduced to help alleviate poor distribution of wax in the mixer caused by clumped flakes. Prior to the use of prilled wax it was common to find clumps of wax in compounds including those mixed at 240 deg F. If waxes are improperly mixed it can cause wall thickness and flow control problems. The compounding of wax into PVC formulations must be controlled precisely or the extrudate can be significantly affected by only a 10% weighing error. This paper will discuss a patented liquid paraffin that is approved by the Plastic Pipe Institute and National Sanitation Foundation and has proven commercial success at five different PVC pipe manufacturers. The trade name for this product is Hydrobrite~R PVC Oil.