Coatings, high solids

D. C. Busby and co-workers. Supercritical Fluid Spray Application Technology A Pollution Prevention Technologyfor the Futures PP- 218—239 Proceedings of the 17th Water-Borne and High-Solid Coating Symposiums New Orleans, La., 1990. 

However, this difference would not seem to be large enough to account for the very large differences in solvent losses that have been reported. Another factor may be that high solids coatings may reach a stage where solvent loss is controUed by diffusion rate much eadier than is the case in low solids coatings (8,43). 

V.R. Kamath and J.D. Sargent, Jr., Proc. Water Borne High Solids Coatings Symp., New Orleans, LA, 5-7 Feb (1986), 12.261-28. 

The main requirements for a coating are that it is easy to apply (i.e., low viscosity) and dries to a non-tacky finish within a reasonable time. Originally, this equated to the solution and evaporation of the solvent. However, because of environmental concerns, formulations have tended to shift the concentration of solvents from 80% to less than 20% (known as high solids coatings). Many industrial processes use polymer powders (of approximately 40 pm diameter),... 

The question whether the intramolecularly crosslinked microparticles of non-aqueous polymer dispersions are really microgels is also justified, considering non-aqueous dispersions prepared from acrylic copolymers and melamine/formaldehyde crosslinker with particle sizes of about 300 nm. [45, 343]. In any case, these crosslinked polymeric microparticles are useful constituents of high-solids coatings, imparting a yield stress to those solutions which probably involves attractive forces between the microparticles. 

Chain Extendable Oligomers for High-Solids Coatings... 

Imine-lsocyanate Chemistry New Technology for Environmentally Eriendly High-solids Coatings... 

Table 7.10. Advantages and disadvantages to high solids coating formulations...

A related approach to high solids coatings is to incorporate a reactive chemical as the solvent. This allows control of the coating viscosity during application but minimizes the VOCs released because the solvent is cross-linked into the coating (Johnson, 1995 Robinson et al., 1994 Adams, 1996 Rupa Vani et al., 1993 Kuo et al., 1994 Hoffman, 1995). Reactive diluents take many forms, sometimes even as a natural oil as in the case discussed by Dirlikov et al. (1992) and Banov (1994). 

Finally, some waterborne coatings incorporated reactive diluents, as in high solids coatings. For example. Blank (1992) describes using a urethane diol as a reactive diluent to replace glycol ether cosolvents in emulsion coatings. 

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