Waterborne

L. Johnson and W. Sade, Proceedings of the 18th Waterborne, Higher Solids, Powder Coating Symposium, pp. 65—77. 

Trees originating at a shield—insulation interface are mosdy due to the existence of protmsion from the shields. They are referred to as vented trees if moisture is present, they are called vented water trees. Particulate contaminants present in the insulation, and waterborne ionizable materials that find their way into the insulation, are also causes of tree formation. 

Prior to the 1990s phenyhnercuric acetate was the primary bactericide and fungicide in latex and waterborne paints. Because of the increasing concerns of mercury toxicity and the potential for high consumer and occupational exposures to mercury when present in paints, the U.S. Environmental Protection Agency (EPA) induced U.S. manufacturers of PMA and other mercury compounds to withdraw their registrations for use of these substances as biocides in paints (see AIercury). Mercury compounds are used only for very limited, specific purposes, such as the use of phenyhnercuric mXx.2LX.e[55-68-5] as a bactericide in cosmetic eye preparations (see Cosmetics). 

Chemical binders are appHed to webs in amounts ranging from about 5 to 60 wt %. In some instances when clays (qv) or other weight additives ate included, add-on levels can approach or even exceed the weight of the web. Waterborne binders ate appHed by spray, saturation, print, and foam methods. A general objective of each method is to apply the binder material in a manner sufficient to interlock the fibers and provide chemical and mechanical properties sufficient for the intended use of the fabfic. 

Waterborne contact adhesives contain an elastomer in latex form, usually an acryflc or neoprene-based latex, and a heat-reactive, cross-linkable phenohc resin in the form of an aqueous dispersion. The phenoHc resin improves metal adhesion, green strength, and peel strength at elevated temperature. A typical formulation contains three parts latex and one part phenohc dispersion (dry weight bases). Although metal oxides may be added, reaction of the oxide with the phenohc resin does not occur readily. 

This is a particularly troublesome competing reaction when the olefin oxide, eg, ethylene oxide, produces the more reactive terminal primary hydroxy group. Glycol ethers are used as solvents ia lacquers, enamels, and waterborne coatings to improve gloss and flow. 

D. T. Liles and H. V. Lefler, Eroc. Waterborne, Higher Solids andEowder Coatings Sjmp. 18, 161 (1991). 

Waterborne Transport. Despite natural limitations, the transportation of chemicals by water has enjoyed substantial growth, especially siace the ead of World War 11. Assisted by governmental developmeat of the inland waterways system, including locks and other navigational aids, water carriers transport large quantities of bulk chemicals in barges between inland ports or between such ports and coastal ports. In addition, bulk chemicals ate transported by self-propelled tank vessels between U.S. coastal points, and between U.S. ports and overseas destinations. In 1989, 56.1 million metric tons (61.9 million short tons) of chemicals were transported in the U.S. domestic waterborne commerce (16). 

Water-repeUent fabrics resist wetting or repel waterborne stains they pass AATCC Test Method 22 (Spray Test). 

The best protection for wood against the attack of decay fungi, insects, or marine borers is obtained by applying preservatives under pressure before installation (61,62). Both oil-type preservatives, such as creosote or petroleum solutions of pentachlorophenol, and waterborne preservatives, such as copper-chrome arsenate and ammoniacal-copper arsenate, are used when wood is to be in direct contact with the ground or in the marine environments. 

J. E. Wiaandy, "Effects of Waterborne Preservative Treatment on Mechanical Properties A Review," ia Proceedings of the 91 st Annual Meeting of the American Wood-Preservers Association, New York, May 21—24, 1995, Vol. 91, AWPA, Woodstock, Md., 1995, pp. 17—33. 

Cellulose esters of aromatic acids, aUphatic acids containing more than four carbon atoms and aUphatic diacids are difficult and expensive to prepare because of the poor reactivity of the corresponding anhydrides with cellulose Httle commercial interest has been shown in these esters. Of notable exception, however, is the recent interest in the mixed esters of cellulose succinates, prepared by the sodium acetate catalyzed reaction of cellulose with succinic anhydride. The additional expense incurred in manufacturing succinate esters is compensated by the improved film properties observed in waterborne coatings (5). 

Waterborne Costing s. These coatings utilize either Hquid or soHd epoxy resins that have been modified to allow their use with water. They are usually in the form of emulsions, suspensions, dispersions, or water-dilutable resins that can be heat- or RT-cured. They are appHed by convenient methods such as roUer-coating, dipping, spray, or electro deposition. 

Owing to governmental regulations, considerable research has been expended to develop systems suitable for substitution of solvent-based systems, particularly for automobile and container appHcations. In the switch from solvent-based to waterborne systems, epoxies are successfully bridging the gap largely by adaptation of conventional resins. 

Significant advances in waterborne coatings have been made by PPG Industries utilizing epoxies as co-resins. These coatings are used in cathodic electrodeposited systems, widely accepted for automobile primers. Many patents have been issued for this important technology (50,51). 

A waterborne system for container coatings was developed based on a graft copolymerization of an advanced epoxy resin and an acryHc (52). The acryhc-vinyl monomers are grafted onto preformed epoxy resins in the presence of a free-radical initiator grafting occurs mainly at the methylene group of the aHphatic backbone on the epoxy resin. The polymeric product is a mixture of methacrylic acid—styrene copolymer, soHd epoxy resin, and graft copolymer of the unsaturated monomers onto the epoxy resin backbone. It is dispersible in water upon neutralization with an amine before cure with an amino—formaldehyde resin. 

Almost all cooling water system deposits are waterborne. It would be impossible to list each deposit specifically, but general categorization is possible. Deposits are precipitates, transported particulate, biological materials, and a variety of contaminants such as grease, oil, process chemicals, and silt. Associated corrosion is fundamentally related to whether deposits are innately aggressive or simply serve as an occluding medium beneath which concentration cells develop. An American... 

Monte, S.J., Proc. 25th Int. Symp. Waterborne, High-Solids, Powder Coating, 190 (1998). 

Although waterborne systems were developed in the 1960s, the form of this chemistry that dominates the industry utilizes end-functional, high molecular weight base polymers dissolved in organic solvents. Work on solventless condensation systems continues, but has not yet become commonplace [45,47]. Solvent-borne condensation cure systems are convenient for their ease of pro-... 

Addition cure silicones can be delivered from solvent, waterborne emulsions, or 100% solids systems. The solvent free versions employ base polymers of intermediate molecular weight to achieve processable viscosity. These base polymers can have reactive moieties in terminal and/or pendant positions. These lower molecular weight, more functional systems result in a tighter crosslink network which feels rubbery to the hand. Low amounts of high molecular weight additives are included in some formulations to provide a more slippery feel [51,52]. 

Because most latices have low viscosities by compounding, most of the waterborne rubber adhesives are sprayable. Thickeners such as fumed silicas can be added to increase viscosity and thixotropy. This means that even at relatively large viscosities (over 10 Pas) many water-based rubber adhesives can be sprayed. Dip and curtain applications require viscosities between 0.05 and 0.3 Pas, whereas brush application works with viscosities between 1 and 50 Pa s. 

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