Synthesis of latexes with low concentration of volatile organic compounds (VOCs): effect of reduction techniques of VOCs on the properties of latexes and paints

The reduction of volatile organic compounds (VOCs) in the latexes produced by emulsion polymerization is a viable option, but it may compromise the performance of the latex in some situations. Different techniques for reduction of residual monomers and VOCs concentrations were studied for understanding the effect of these techniques and VOCs concentrations on the application properties of latexes and paints. Styrene/2-ethylhexyl acrylate latices functionalized with acrylic acid and acrylamide were produced by emulsion polymerization, followed by removal of residues and other VOCs with a chemical or physical technique, or with the combination of both. The effect of various parameters related to reduction techniques of VOCs, type of initiator, reducing agent and nitrogen stripping with steam were studied and correlated with the properties of latexes and paints. The combination of chemical and physical techniques was more effective for reducing the monomers and VOCs to latexes. The techniques employed for reduction of VOCs had a negative effect on the end-use properties of latex and paints. The abrasion resistance of the paint film was dependent on the technique employed and on VOCs concentration.A redução dos compostos orgânicos voláteis (COVs) nos látices produzidos via polimerização em emulsão é uma opção viável, mas em algumas situações pode comprometer a qualidade do látex. Diferentes técnicas de redução da concentração dos monômeros e dos COVs foram estudadas com o objetivo de entender o efeito destas técnicas e da concentração dos COVs nas propriedades de aplicação dos látices e das tintas. Os látices de estireno com acrilato de 2-etil hexila funcionalizados com ácido acrílico e acrilamida foram produzidos via polimerização em emulsão, seguido por remoção química, física e a combinação de ambas as técnicas de redução dos monômeros e dos COVs. Os parâmetros relacionados à técnica de redução dos COVs, ao tipo de iniciador, ao agente de redução e à introdução de nitrogênio saturado com vapor de água foram estudados e correlacionados com as propriedades de aplicação das tintas. A combinação da técnica química com a técnica física foi mais eficiente na redução dos monômeros e dos COVs nos látices. As técnicas utilizadas na redução dos COVs tiveram influência negativa nas propriedades de aplicação dos látices. A resistência à abrasão dos filmes de tinta foi dependente da técnica empregada e da concentração dos COVs.Universidade Federal de São Paulo (UNIFESP) Instituto de Ciência e TecnologiaBASF S.A. Laboratório de Aplicações TécnicasUNIFESP, Instituto de Ciência e TecnologiaSciEL

Effect of itaconic acid on the wet scrub resistance of highly pigmented paints for architectural coatings

This study investigates the influence of carboxylic monomers, such as itaconic acid (IA), on the colloidal properties of the latexes made by semi-continuous emulsion copolymerization of styrene (STy) with n-butyl acrylate (BA). A number of copolymerization runs were carried out with different IA concentrations. the effect of functional monomer on the overall conversion, the colloidal properties of the latexes, and the distribution of the carboxylic groups (buried, particle surface and aqueous phase) were examined. the carboxylic groups present in the latexes were analyzed using conductimetric and potentiometric titrations. the behavior of the IA on the wet scrub resistance of highly pigmented paints for architectural coatings was examined and correlated with the distribution of the carboxylic groups. the results obtained showed that the properties of highly pigmented paints are greatly dependent on the amount and distribution of the carboxylic groups. the carboxylic acid distributed in the aqueous phase has a strong influence on the wet scrub resistance and on the characteristics of the final products.BASF SA R&D, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Mat Engn, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Mat Engn, São Paulo, BrazilWeb of Scienc