Formulation of Latexes

Emulsion polymers (latexes) are the most commonly used film formers in the coating industry. This is particularly the case with aqueous emulsion paints that are used for home decoration. These aqueous emulsion paints are apphed at room temperature, and the latexes coalesce on the substrate to form a thermoplastic film. Occasionally, functional polymers are used for crosslinking in the coating system. The polymer particles are typically sub micron (0.1-0.5 pm). 

Generally speaking, three methods are available for the preparation of polymer dispersions, namely emulsion, dispersion, and suspension polymerisation  

Descriptions of both emulsion and dispersion polymerisation are given below, with particular reference to the control of their particle size and colloid stabiHty, which is greatly influenced by the emulsifier or dispersant used. Particular emphasis will be placed on the effects of polymeric surfactants that have been recently appHed to the preparation of emulsion polymers. 

Formulation of Disperse Systems Science and Technology, First Edition. Tharwat F. Tadros. 

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Close to half of the ethylene oxide produced is directly converted to ethylene glycol (1,2-ethanediol) by acid-catalyzed or pressure hydration. Roughly half the ethylene glycol is as an automotive coolant antifreeze and half in polyester (poly(ethylene terephthalate)) fiber production (Chap. 21). Smaller amounts are consumed for alkyd resins production and for the formulation of latex paints. 

BASF, Performance Chemicals Brochure — Products for the Manirfacture, Stabilization. and Formulation of Latex Polymers 1989... 

Virtually all end-use formulations of latex polymers of MFT much above 5 °C (40 °F) contain a moderately low volatility solvent for the polymer. These act as temporary plasticizers to ensure low MFT and enhance polymer interdiffusion. The solvent should diffuse and evaporate as quickly as possible for film hardness development, but not at the expense of completeness of film strength development A complication is that compositions of high Tg which contain solvent... 

The surfactants (and colloids) control many of the properties of emulsion polymers and some knowledge of their nature and characteristics is a necessary pre-requisite for successful formulation of latex systems. 

Effect of silanes on adhesion strength of latex formulations... 

While most studies of particle swelling have dealt with emulsion polymers containing high acid levels, we have restricted our attention to latexes containing relatively low incorporated acid (ca.2-3%) to avoid substantial solubilization of the particles. Questions under current consideration are related to the location of incorporated carboxyl groups within the latex particles, the morphology of expanded particles, and the detailed mechanism of expansion. Information of this type is valuable not only from a fundamental standpoint but is essential in the investigation of very practical problems such as the viscosity stability of latex formulations. 

A wide range of thermoplastic starch compounds have been claimed in recent years. Formulations of thermoplastic starch with linear, biodegradable polyesters, including polycaprolactone and PHBV,174 176 and with polyamides175 have been reported. Laminated structures have been claimed using thermoplastic starch or starch blends as one or more of the layers.175,177,178 The use of polymers latexes as components of thermoplastic starch blends has also been claimed.179 181 Blends with natural polymers are also claimed, including cellulose esters182,183 and pectin.184 A crosslinked thermoplastic material of dialdehyde starch and protein has been reported.185... 

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