Synthetic Fillers

Silicate paints/prod-ucts, emulsion paints DIN 18363 (M-SKOl) potash-waterglass (binder), inorganic/organic pigments, mineral fillers, synthetic resins (dispersions, stabilizers), water (dispersing agent) wall p unts, outside house paints... 

Phenol—formaldehyde (PF) was the first of the synthetic adhesives developed. By combining phenol with formaldehyde, which has exceptional cross-linking abiHties with many chemicals and materials, and a small amount of sodium hydroxide, a resin was obtained. The first resins soHdified as they cooled, and it was discovered that if it was ground to a powder with a small amount of additional formaldehyde and the appHcation of more heat, the mixture would Hquify and then convert to a permanently hard material. Upon combination of the powdered resin mixture with a filler material such as wood flour, the result then being placed in a mold and pressed under heat and pressure, a hard, durable, black plastic material was found to result. For many years these resulting products were called BakeHte, the trade name of the inventor. BakeHte products are still produced today, but this use accounts for only a small portion of the PF resins used. 

Synthetic Marble. Synthetic marble-like resin products are prepared by casting or molding a highly filled monomer mixture or monomer—polymer symp. When only one smooth surface is required, a continuous casting process using only one endless stainless steel belt can be used (52,53). Typically on the order of 60 wt % inorganic filler is used. The inorganic fillers, such as aluminum hydroxide, calcium carbonate, etc, are selected on the basis of cost, and such properties as the translucence, chemical and water resistance, and ease of subsequent fabrication (54,55). 

In recent years, synthetic polymeric pigments have been promoted as fillers for paper. Pigments that ate based on polystyrene [9003-53-6] latexes and on highly cross-linked urea—formaldehyde resins have been evaluated for this appHcation. These synthetic pigments are less dense than mineral fillers and could be used to produce lightweight grades of paper, but their use has been limited in the United States. 

Eatty bisamides are used primarily to kicrease sHp, reduce blocking, and reduce static ki polymeric systems. Other specialty appHcations kiclude cosolvents or coupling agents for polyamide reskis, fillers for electrical kisulation coatings, additives for asphalt to reduce cold flow, and synthetic waxes for textile treatments (68). Bisamides have been used ki all the traditional primary amide appHcations to kicrease lubricity and have become the amide of choice because of thek better efficiency. Bisamides have the highest commercial value ki the amide market. 

The mbber compound usually requires an inert inorganic filler and small particle sise carbon particle for reinforcement. The mbber polymers vary in inherent tensile strength from very high in the case of natural mbber to almost nonexistent for some synthetic polymers, eg, SBR. The fillers most commonly used for mbber compounds include carbon black, clay, calcium carbonate, siUca, talc (qv), and several other inorganic fillers. 

Graphites (natural or synthetic) are black semireinforcing fillers used almost exclusively in rotary shaft seal applications where surface lubricity and abrasion resistance must be enhanced (see Carbon, natural graphite). 

Mechanical properties depend considerably on the stmctural characteristics of the EPM/EPDM and the type and amount of fillers in the compound. A wide range of hardnesses can be obtained with EPM/EPDM vulcanisates. The elastic properties are by far superior to those of many other synthetic mbber vulcanizates, particularly of butyl mbber, but they do not reach the level obtained with NR or SBR vulcanizates. The resistance to compression set is surprisingly good, in particular for EPDM with a high ENB content. 

Some rubber base adhesives need vulcanization to produce adequate ultimate strength. The adhesion is mainly due to chemical interactions at the interface. Other rubber base adhesives (contact adhesives) do not necessarily need vulcanization but rather adequate formulation to produce adhesive joints, mainly with porous substrates. In this case, the mechanism of diffusion dominates their adhesion properties. Consequently, the properties of the elastomeric adhesives depend on both the variety of intrinsic properties in natural and synthetic elastomers, and the modifying additives which may be incorporated into the adhesive formulation (tackifiers, reinforcing resins, fillers, plasticizers, curing agents, etc.). 

Although natural quartz, cristobalite and opal are used as fillers, only synthetic products (fumed and precipitated silicas) find use as fillers in rubber base adhesives. 

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