WATER-BORNE

L. L. Xing, J. E. Glass, andR. H. Fernando, "Technology for Water-Borne Coatings," iaj. E. Glass, ed., C3 Symposium, Series 663, American Chemical Society, Washiagton, D.C., 1997, Chapt. 15. 

This may also have been a factor in the conquering of the known world by the Roman Legions. Expeditionary and seige forces, even today but much more so then, are at risk for water-borne diseases. The practice of the Roman army to carry with it substantial wine suppHes is seen as sound militarily for health reasons, rather than just from the standpoint of the enjoyment of the soldiers. Recent study indicates that tourist-type diarrheas are less frequently encountered if wine is consumed rather than water, even bottled water (20). 

Other Uses. Large quantities of hydrocarbon resins are used in mastics, caulks, and sealants (qv). Polymers for these adhesive products include neoprene, butyl mbber, polyisoprene, NR, SBR, polyisobutylene, acryHcs, polyesters, polyamides, amorphous polypropylene, and block copolymers. These adhesives may be solvent or water-borne and usually contain inorganic fillers. 

P. A. CaUais, V. R. Kamath, and M. G. Moskal, Proc. Water-Borne, Higher-Solids, Powder Coat. Symp. 19, 156 (1992). 

Fig. 4. Dose response for blood glucose measurement using a dry chemistry system having a water-borne, tough coating film. The numbers represent...

Excellent correlation was found when results at 660 nm and 749 nm were compared using a reference hexokinase glucose method (27). The dose response was excellent up to 300 mg/dL glucose. In general, water-borne coatings do not lend themselves to ranging by antioxidants (qv). 

S. Didikov and co-workers, Water-Borne, Higher-Solids, andTowder Coatings Symposium, University of Southern Mississippi and Southern Society for... 

Water-borne polyurethane coatings are formulated by incorporating ionic groups into the polymer backbone. These ionomers are dispersed in water through neutrali2ation. The experimental 1,12-dodecane diisocyanate (C12DI Du Pont) is especially well suited for the formation of water-borne polyurethanes because of its hydrophobicity (39). Cationomers are formed from IPDI, /V-methyIdiethan olamine, and poly(tetramethylene adipate diol)... 

Water-borne adhesives are preferred because of restrictions on the use of solvents. Low viscosity prepolymers are emulsified in water, followed by chain extension with water-soluble glycols or diamines. As cross-linker PMDI can be used, which has a shelf life of 5 to 6 h in water. Water-borne polyurethane coatings are used for vacuum forming of PVC sheeting to ABS shells in automotive interior door panels, for the lamination of ABS/PVC film to treated polypropylene foam for use in automotive instmment panels, as metal primers for steering wheels, in flexible packaging lamination, as shoe sole adhesive, and as tie coats for polyurethane-coated fabrics. PMDI is also used as a binder for reconstituted wood products and as a foundry core binder. 

The principal markets for neopentyl glycol (NPG), the hydrogenated, crossed aldol condensation product of isobutyraldehyde and formaldehyde, are in water-borne and alkyd-surface coatings. 

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. 

Such polyurethanes have excellent hydrolytic stability compared to water-reducible polyesters and superior abrasion resistance. In view of the importance of developing low solvent emission coatings, considerable effort is being devoted to new types of water-borne urethane resins (62,63). 

D. E. Eiori and R. W. Dexter, Proceedings of the Water-Borne Higher-Solids Coatings Symposium New Orleans, 1986, p. 186. 

Scotts technology (17) uses fluid-bed (Wurster column) technology to apply polymeric coatings to a number of fertilizer substrates including urea, potassium nitrate, potassium sulfate, and monoammonium phosphate (MAP). The coating material is appHed as a water-borne latex onto the fluidized substrate. As the substrate is fluidized with warm air (40—50°C), water is driven off and the latex coalesces into a continuous film around the fertilizer particle. The particular latex compositions used have selected glass-transition and blocking temperatures, which enable quick removal of the water before the soluble fertilizer core dissolves. This obviates the need to use precoats prior to the latex appHcation. 

Besides the solvent composition, the vehicle system is responsible for various drying deficiencies associated with water-borne coatings, such as slow initial dry time, loss of dry, poor through drying, and hardness (see Coatings). 

The vehicle system of water-borne coatings can be divided into two categories water-emulsifiable vehicles and water-soluble vehicles. 

The differences in composition between water-borne and solvent-bome air-drying paints necessitate change in driers and drier combinations. Since traditional driers are dissolved in mineral spirits, xylene, or other aUphatic/aromatic solvents, they are not readily dispersed in an aqueous system. If traditional driers are used, they must be dissolved in the vehicle before neutralization, which may result in a severe viscosity increase and processing problems. 

The main reason for loss of dry in water-borne paints is the hydrolysis of the metal soap. In the presence of water the drier is first hydrated. These hydrates are unstable and result in hydrolysis of the metal soap and subsequently the insolubiUty of the basic metal soap. 

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