Formulation parameters influencing self-stratification of coatings
article
Research was carried out aimed at the development of self-stratifying paints for steel which after application during film formation spontaneously form two well established layers of primer and top coat. The parameters affecting stratification were investigated for combinations of epoxy resins and physically drying binders. Incompatibility of the binders used was shown to be a necessary, although not a sufficient condition for stratification. The degree of incompatibility of the resins could be characterised reasonably by the extent of overlap of their solubility spheres in the Hansen solubility parameter concept. Very good stratifying paints of two pigmented binders could be formulated, while the pretreatment of the pigments with particular adhesion promoters can favour stratification considerably. During film formation of good stratifying paints, processes are occurring comparable to those resulting in the formation of Bénard cells. Thus, factors affecting the floating process also affect stratification. The presence of pigments of different particle size appeared to be a necessary condition. On the other hand, additives such as surfactants and anti-floating agents which prevent the floating process have a deleterious effect on the process of stratification.
Topics
Epoxy resinsIncompatibility of resinsPhysically drying bindersSelf-stratifying coatingsSteel coatingAdhesionBindersDryingEpoxy resinsOrganic coatingsPigmentsSolubilitySurface active agentsAnti floating agentsBenard cellFloating processHansen solubility parameter conceptPhysically drying bindersResin incompatibilityPaint
TNO Identifier
233373
ISSN
03009440
Source
Progress in Organic Coatings, 28(3 (SPEC. ISS.)), pp. 173-181.
Collation
9 p.
Pages
173-181
Files
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