Coalescing aide

The monoisobutyrate ester of trimethylpentanediol is especially useful as a coalescing aid in flat and semigloss (48) latex pain formulations (see Paint). This product is commercially available from Eastman as Texanol ester alcohol. 

The increase of restrictive regulations on the use of organic solvents favoured the increasing use of latex-based adhesives. Because of the slow evaporation of water, these adhesives show less tack and can suffer bacterial attack. Infrared heaters and ovens can be used to favour the evaporation of water. Often a small amount of solvent (coalescing aid) is added to the latex system to improve wetting and coalescence of the latex particles. 

Uses. Solvent in latex paints, lacquers, and other coatings, resins, coalescing aids, and coupling solvents... 

The principal application for butyl CELLOSOLVE is as a low evaporating solvent of choice in many industrial coatinqs applications including coil coating and wood finishing. Its acetic acid ester, butyl CELLOSOLVE acetate, finds use in similar applications as a coalescing aid in latex trade... 

Butyl CARBITOL is used in trade paint formulations and, as in the case of its acetic acid ester, as a coalescing aid. Small amounts of triethylene glycol mono-n-butyl ether are used in hydraulic brake fluid systems. The butyl glycol ethers are increasing in volume at a rate of about 5 percent per year. 

Horizontal vessels are normally used as settlers in order to provide a large area of phase interface. It is generally necessary to conduct experiments to ascertain the coalescence rate. The settling area can usually be reduced by the use of coalescing aids such as mesh and metal swarf. In recent years, attempts have been made to use an electrostatic field as a coalescence aid. Mumford and Thomas (1972) and Jeffreys and Mumford (1974) have described various methods for reducing the overall size of the settlers. In many instances, differential contact (DC) packings arc used that are claimed to act as excellent coalescence aids. 

Water-polymer Silicone polymer fluid-water emulsifiers Emulsion polymer coalescence aid ... 

Jiratumnukul and Michael (37) have reported the use of different glycol esters from soybean oil, such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol, for making new coalescent aids. They investigated the properties of these coalescent aids as related to evaporation rates and Minimum Film... 

The treater is the vessel that attempts to deliver pipeline-specification crude oil as its hydrocarbon product. Heater treaters typically aid in resolving emulsions by the addition of heat, the use of electrostatic grids, or the use of mechanical coalescing aids such as hay or baffle systems. 

Use High-boiling solvent for nitrocellulose lacquers, epoxy resins, multicolor lacquers film-coalescing aid for polyvinyl acetate latex. 

Butoxyethanol acetate is primarily used as a high-boiling, retarder solvent (i.e., an active, slow-evaporating solvent which ensures smooth film formation) for nitrocellulose lacquers, acrylic enamels, epoxy resins, and multicolor lacquers (Leaf 1985 as cited in NIOSH 1990 Lewis 1993). 2-Butoxyethanol acetate is also a film-coalescing aid for polyvinyl acetate latex and is used in some ink and spot remover... 

Hoy (27) has examined some factors that influence the efficiency of coalescing aids. An important factor is the distribution of solvent between aqueous and polymer phases at the critical time during film formation. Water-soluble solvents may be lost from the coating through wicking action into the substrate. 

Jiratumnukul, N. M.R. Van De Mark. Preparation of glycol esters of soybean oil fatty acids and their potential as coalescent aids in paint formulations./. Am. Oil Chem. Soc. 2000, 77, 691-697. 

Viscosity Maxima. The low-shear-rate viscosities of both commercial and model associative thickeners below their c /, values will increase with the addition of conventional low molecular weight surfactants or coalescing aid (22). With HEUR polymers, solution viscosities are observed to increase, achieve a maximum value, and then decrease with continued increase in surfactant concentration (23). This type of behavior is illustrated (Figure 5) for four commercial HEURs with a nonionic surfactant (typical of that used in coating formulations). A similar behavior has been observed (24) with a classical anionic surfactant and hydrophobically modified (hydroxy-ethyl)cellulose (HMHEC) and is reviewed in Chapter 18. Intermicellar networks, formed by the participation of one or more hydrophobes from different polymers in the micelles of conventional surfactants, were again recently suggested (25) to affect viscous solutions. 

In a high-volume-fraction dispersion with electrosteric stabilization of the latex and an increasing dispersed-phase surface area, the high viscosity observed at low shear rates with decreasing latex size relates to electroviscous and hydration effects. Lower surface acid concentrations on some of the smaller latices may also result in partial flocculation of the latex and a higher effective volume fraction in the presence of coalescing aids (22, 26). 

In phase separators the level of the separation layer can best be achieved with internal or external syphons with free overflow. Coalescence aids can be incorpoarted in the feed zone. The material (metal, glass, PTFE) should be chose such that it is preferably wetted by the disperse phase. 

The presence of surfactants, besides altering the latex particle surface, can also interact with the water-soluble polymer. For instance, poly(ethylene oxide) homopolymer and block copolymers interact with sodium dodecyl sulfate surfactant [109], and hence alter the latex viscosity behaviour [110]. Other water-soluble polymers are also capable of interacting with specifle surfactants [111]. When pigmented latex dispersions are thickened with associative thickeners one must consider the interactions with some of the pigment stabilizers [112] and other additives, like coalescing aids [113]. 

In addition, coalescing aids and plasticiziers are often post-added to a latex. In many coating applications film formation has to be rapid, requiring low Tg polymer, and the final polymer properties must be hard and strong, representing... 

Chem. Descrip. Diethylene glycol butyl ether acetate CAS 124-174 EINECS/ELINCS 204-68 -9 Uses Solvent for high-solids coatings, NC emulsions coalescing aid for wafer-disp. coatings... 

Chem. Descrip. Diethylene glycol monobutyl ether acetate CAS 124-17-4 EINECS/ELINCS 204-685-9 Uses Solvent in cosmetics, printing inks, high-bake enamels, esp. screen inks and coil coatings selective solvent in separation of alcohols and ketone coalescing aid in low-pH latex paints Features Very slow evaporation rate limited water sol. 

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