Anti-frictional fillers

Another group of compositions of this type is used to protect metal friction joints during transportation and preservation. They represent compositions thickened by polymers of soap, silica gel and soap-hydrocarbon lubricants impregnated with anti-frictional fillers (molybdenum or graphite disulfide), oil-soluble Cl, anti-seizure additives and surfactants. To this type of Fluids belong such compositions as Tenox Film 30 (Sophes Co., France), Koral 530 (Hungary), SACI 500 and Shell Ensis Fluid 256 (Shell, GB). 

For hundreds of years sticky surfaces have been dusted with powder (e.g., talc) to keep them separated. Talc is broadly used in cable and profile extrusion to obtain a smooth surface. Similarly, in injection molding, the application of aluminum trihydroxide gives a better surface finish. Talc, CaCOs, and diatomite provide anti-blocking properties. Graphite and other fillers decrease the coefficient of friction of materials. PTFE, graphite and M0S2 allow the production of self-lubricating parts. Here, PTFE, a polymer in powder form, acts as a filler in other polymers. Matte surfaced paint is obtained by the addition of silica fillers. 

Generally, the friction coefficient decreases as the load of filler increases but there is a critical quantity above which the friction coefficient decreases. The correct amount of anti-wear additive for a particular material and a particular applied load can be determined by simple morphological observation of the surface. The expected wear pattern forms surface debris whereas if the part is not wearing well its surface will melt and become shiny. 

Additives are used for a wide variety of purposes, and may be classified as fillers, anti-oxidants, stabilisers, plasticisers, fire retardants, pigments and lubricants. Anti-oxidants and stabilisers are usually used in rather small quantities in order to prevent degradation of the polymer when it is exposed to air, light and heat the intention here is to maintain the properties of the polymer rather than to modify them. Fillers may be used either simply to produce a cheaper product or to improve the properties, in particular the mechanical properties. Lubricants may be used externally, to prevent adhesion of the polymer to the processing equipment, or internally, either to aid flow during processing or to reduce friction between the product and other materials. 

Cost is naturally very important, but the filler does play an important role in several film properties [161]. For example, in LLDPE extruded film, ground calcium carbonate improves efficiency by both increasing the cooling rate of the bubble and the level of fusion it improves printability primary pigment dispersion can be improved it reduces the coefficient of friction by increasing the surface hardness of the film and it acts as an anti-blocking agent. 

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