Two specific problems that may be lessened or corrected by the use of antistatic materials are found in the blow molding industry. The first deals with the presence of contaminating chips within blow-molded containers, and the second deals with unsightly dust collection on blown polyethylene parts on store shelves.
Particles of polyethylene that are forced into a container by such operations as reaming pose a rather serious problem in some container operations. Removal of the chips is costly and even the use of high pressure air does not always do the job. Due to the presence of
static in a material such as polyethylene, these particles cling tenaciously to the blown part. The presence of these chips will cause plugging of nozzles in the bottle filling line. The smaller the filling nozzle the more serious the problem. The presence of an antistatic additive in the raw material will lessen the grip of the contaminate.
Dust collection on such plastics as polystyrene and polyethylene due to static attraction is much more pronounced than on materials that absorb moisture, such as cellulosics, and dissipate static electrical charges. Patterns are actually formed from dust that is pulled to the container or part from the surrounding air. The proper use of antistatic materials to overcome this problem is based on the incorporation of the product in the raw material. The additives are used in low concentration and therefore, must be uniformly dispersed through the plastic.
It is recommended that thorough testing be conducted on critical blow-molded parts applications before a final decision to use antistatic materials is made. The degree of exudation of the additive may alter treatment and decoration techniques of the part. The effect of the additive on stress-crack resistance must also be investigated.
The following antistatic agents are in use today: An-stac M and 2M； Armid O； Nopco 1009-C; Slip-Eze； Sequestrene NA4； “Zelec” NK；Glyceryl Monosterate E； Nalquat G-9-12 and G-8-12. In general it is suggested that the antistats be added at the 1 part or 1 per cent level.