External Antistatic Agents

There are mainly two types of antistatic agents external and internal. External antistats are applied to the surface of the end product through... 

For antistatic modification of extruded and injected-molded articles made from unplasticized PVC, internal antistatic agents are unsuitable in the usual amounts (<2 phr). Instead, the external application of the alkanesulfonates solution mentioned above is recommended. 

Saturated hydrocarbons (waxes), fatty acids, metal soaps, fatty acid amides and esters (primarily Cig-Cis) act as internal lubricants, fluoro elastomers as external lubricants. Many other polymer additives, e.g. antistatic agents, antifogs, antioxidants, UV stabilisers, etc., act as lubricants in the barrel of the extruder once they are in the liquid form. 

There are two types of durable antistat. The first (so-called external antistatic agent) is applied at some stage after fibre manufacture whilst the second type is incorporated during manufacture. The former type exhibits varying degrees of durability and is not usually as durable as the latter. 

Poly(oxyethylene) sorbitan monolaureate is a surface active compound which is also known as an internal or external antistatic agent for a great number of plastics. It has been found that this compound provides an almost instantaneous antistatic action (14). 

Antistatic agents. Static electrical charges may build up on the surface of polymers due to their low electrical conductivity, which may cause dust accumulation and sparking problems. These charges can be dissipated through the addition of external or internal antistatic agents (phosphate and fatty acid esters, sulfated waxes, quaternary ammonium compounds, amines, etc.). 

Antistatic Agent 575. [E.F. Houghton] External antistat for plastics. 

Antistats can be appiied internally or externally. Internal antistats are compounded into the resin, and act once they migrate to the surface of the poiymer. External antistats are appiied directly on the surface by spraying, or sometimes by dipping the polymer in a solution of the antistatic. Internal antistatic agents can... 

Antistatic agents commonly used are substances that are added to plastics molding formulations or to the surface of molded articles in order to minimize the accumulation of static electricity. In general terms, antistatic agents can be divided according to the method of application into external and internal agents. 

External antistatic agents are applied to the surface of the molded article from aqueous or alcoholic solution by wetting, spraying, or soaking the plastic object in solution, followed by drying at room temperature or under hot blown air. Their concentration varies between 0.1 and 2% by weight. Almost all... 

It is supplied mainly as a 50% by weight solution in a water-propanol mixture. It is applied as an external antistatic agent at 2% by weight concentration (pH 4-6) and is recommended for phonograph records and other products made of PVC and its copolymers. 

It is necessary to be able to identify and quantify the additives in polymers and vibrational spectroscopy is a particularly useful approach to this problem. Compared with traditional chemical analyses, vibrational methods are nondestructive and are time-and cost-effective as well as more precise. A large number of examples exist in the literature. For example, antistatic agents (polyethylene glycol (PEG) in polyethylene (PE)) can be detected directly using FTIR sampling (367). An IR spectroscopic technique for the analysis of stabilisers (2, 6-di-tert-butyM-methylphenol) in PE and ethylene-vinyl acetate (EVA) copolymer has been described (368). It is possible to quantify the amount of external and internal lubricants (stearic acid in polystyrene (PS)) (371). Fillers in polymers can also be analysed (white rice husk ash (predominantly silica in polypropylene (PP)) (268). Raman spectroscopy has been used to detect residual monomer in solid polymethyl methacrylate (PMMA) samples (326). 

Antistats function to either dissipate or promote the decay of static electricity. Secondary benefits of antistat incorporation into polymer systems include improved processability and mold release, as well as better internal and external lubrication. Therefore, in certain applications, antistatic agents can also function as lubricants, slip agents, and mold release agents. 

Treating the finished product with a coating (painting) of an external antistatic agent [97,101, 102]. 

Internal antistatic agents are of interfacially active character, and via migration accumulate on the surface of the plastic product. Their molecules posses hydrophobic and hydrophilic groups the former confer a certain compatibility with the polymer and the hydrophilic groups take care of the binding and exchange of water on the surface. They are anionic, cationic or nonionic compounds [97]. External agents are applied to the surface of the plastic material in the form of aqueous or alcoholic solutions. 

PS moulding material may eontain small quantities of lubricants (internally or externally) to help process the resin for end usage. The addition of antistatic agents, UV stabilisers, glass fibres, or colourants via compounding is also common. 

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