Latex technology

Latex polymers Latex resins Latex technology... 

Vinyl, alkyd, and styrene—butadiene latexes are used as film formers in most architectural coatings. Because alkyd resins (qv) require organic solvents, their use has decreased substantially for architectural coatings, but is stiU holding up in industrial appHcations, where their greater durability justifies the added expense (see Latex technology). 

Latex technology encompasses coUoidal and polymer chemistry ia the preparation, processing, and conversion of natural and synthetic latices into useful products. 

Almost all synthetic binders are prepared by an emulsion polymerization process and are suppHed as latexes which consist of 48—52 wt % polymer dispersed in water (101). The largest-volume binder is styrene—butadiene copolymer [9003-55-8] (SBR) latex. Most SBRlatexes are carboxylated, ie, they contain copolymerized acidic monomers. Other latex binders are based on poly(vinyl acetate) [9003-20-7] and on polymers of acrylate esters. Poly(vinyl alcohol) is a water-soluble, synthetic biader which is prepared by the hydrolysis of poly(viayl acetate) (see Latex technology Vinyl polymers). 

The product of an emulsion polymerization is a latex ie, polymer particles on the order of 0.5—0.15 p.m stabilized by the soap. These form the basis for the popular latex paints. SoHd mbber is recovered by coagulating the latex with ionic salts and acids (see Latex technology). 

Latex Mixes. The first step in latex fabrication is to bring compounding ingredients into solution or suitable dispersion form. Most ingredients are not water soluble and it is necessary to emulsify Hquids and microdisperse soHds in water (see Latex technology). 

Styrene—Butadiene Rubber (SBR). This is the most important synthetic mbber and represents more than half of all synthetic mbber production (Table 3) (see Styrene-butadiene rubber). It is a copolymer of 1,3-butadiene, CH2=CH—CH=CH2, and styrene, CgH5CH=CH2, and is a descendant of the original Buna S first produced in Germany during the 1930s. The polymerization is carried out in an emulsion system where a mixture of the two monomers is mixed with a soap solution containing the necessary catalysts (initiators). The final product is an emulsion of the copolymer, ie, a fluid latex (see Latex technology). 

The term electrophoresis refers to the movement of a soHd particle through a stationary fluid under the influence of an electric field. The study of electrophoresis has included the movement of large molecules, coUoids (qv), fibers (qv), clay particles (see Clays), latex spheres (see Latex technology), basically anything that can be said to be distinct from the fluid in which the substance is suspended. This diversity in particle size makes electrophoresis theory very general. 

L tcx Monomer Production. ARI Technologies, Inc. has introduced a catalyst system which, it is claimed, can operate at an average bed temperature of 370°C while achieving conversion efficiency in excess of 99.99% on exhaust streams from latex monomer production (see Latex technology). 

The latex may then either be concentrated to about 60% DRC, usually by centrifuging or evaporation, or alternately coagulated and dried. The two approaches lead to two quite distinct branches of rubber technology, namely latex technology and dry rubber technology. 

In latex technology, concentrated latex is first blended with the different additives required. To prevent premature destabilisation the powders are added as dispersions and non-aqueous liquids are generally added as emulsions. Care must be taken to avoid destabilisation, which can be brought about in different ways such as... 

M. S. El-Aasser, Advances in Emulsion Polymerization and Latex Technology (21st Annual Short Course), Vol. 1, Emulsion Polymers Institute, Lehigh University, Bethlehem, PA, 1990. 

Anionic emulsifiers, such as alkali salts of fatty acids, can be applied in anionic latices. Are particularly important as wetting and foaming agents in latex technology. Poly(glycol) ethers act as nonionogenic emulsifiers. 

In latex technology, a submicro scopic aggregation of oriented molecules in polymer technology it is synonymous with crystallite. The term is also applied to the aggregates of soap molecules formed in emulsion polymerisation. Micro... 

The main path of the research employed both methods of synthesis in turn. At first, the graduate students Yenwo and Pulido explored the use of sequential IPN s based on castor oil urethanes and polystyrene (12-16). At the same time, the graduate student Devia, working in Colombia, explored an alternate synthetic route using latex technology (17). Since nothing was known about the behavior of such materials, their collective objective was to provide a map upon which further efforts could be intelligently based. This effort has now been reviewed (18). 

Regev O, ElKati PNB, Loos J, Koning CE (2004) Preparation of conductive nanotube-polymer composites using latex technology. Adv Mater 16 248-251. 

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