The influence of organic diluents and solvents on the stability of PVC plastisol water dispersions

Edwin Makarewicz,Krzysztof Jan´Czak

doi:10.2478/v10026-007-0011-1

Abstract

The influence of organic diluents and solvents on the stability of PVC plastisol water dispersions The work presents the research, the aim of which is to specify the influence of organic diluents and solvents such as xylene, toluene, n-butyl acetate and butanol as well as cyclohexanone on the stability of water dispersions of the PVC plastisol containing various surface-active agents (SAA). The applied surfactants were characterised by a specific ethoxylation number, molecular mass, the Hildebrand parameter, hydrophilic-hydrophobic balance, surface activity, the limiting viscosity number, the Haller interaction constant, the limiting equivalent conductivity and the Kohlrausch-Onsager equation "b" constant. Basing on the molar refraction and the Hildebrand parameter, the interactions between the plastisol constituents and the constituents of water dispersions of the PVC plastisol were established. The sedimentation tests on the PVC plastisol water dispersions stabilized by various surface-active agents with an organic diluent or solvent added indicated that the addition resulted in the dispergation yield, a reduction in the PVC plastisol molecular size in water dispersion and the increased Huggins interaction constant, showing both surface lyophilisation and higher adsorption of surface-active agents.

Highlights

One of the main trends in the development of contemporary paint and varnish industry is a tendency to reduce or eliminate completely the polar and toxic organic solvents and diluents in the composition of a painting substance
Surface-active agents are used as stabilizers and are able to adsorb on the interface, reducing the interfacial surface free energy
That is why surface-active agents (SAA) include compounds, the molecules of which consist of two parts: polar and non-polar, called hydrophilic and hydrophobic[3,4,5]

Summary

Introduction

One of the main trends in the development of contemporary paint and varnish industry is a tendency to reduce or eliminate completely the polar and toxic organic solvents and diluents in the composition of a painting substance. The particles of the constant phase are characterised by an unsaturated surface force system on the developed interfacial separation surface, the automatic reduction of which is related to their aggregation and coagulation. In order to provide the particles with aggregative stability, it is necessary to create adsorptive layers or a double electric layer on their surface that would result in the emergence of electrostatic repulsion as well as solvation and adsorptive-solvation layers. Surface-active agents are used as stabilizers and are able to adsorb on the interface, reducing the interfacial surface free energy. A characteristic feature of the surfactants consists in the fact that its molecules in a solution are more active than the medium molecules. The surface activity of the agents reveals with respect to the medium, and moderates the solution-air interface features. That is why surface-active agents (SAA) include compounds, the molecules of which consist of two parts: polar and non-polar, called hydrophilic and hydrophobic (or lipophilic)[3,4,5]

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Conclusion