December 1991
Additives for Polvmers
TECHNICAL Post-stabilizing recycled polypropylene during processing
NOTES
Although rarely categorized as stabilizers, acid neutralizers are included in the additive package of virtually every polypropylene compound. While their specific job is the neutralization of potentially corrosive acids -residual by-products of catalyst and other additive reactions -they can also contribute significantly to the melt stability of the polymer and, in the case of lacticbased neutralizers, markedly improve the colour stability. This article describes the application of a lactats/lactylate neutralizer to the processing stabilization of recycled PP, and compares its effectiveness to that of other additives. Virgin PP was processed in the laboratory to simulate recycled material and then post-stabilized. In a second testing phase, post stabilization was applied to actual post-consumer containers. Plast. Erg., 1991, XLVII,
Recycling
of pigments
(Sept.),
39-41
A unique recycling programme that reclaims lost airborne pigment particles and converts them into a black polystyrene concentrate has been developed by Spectrum Colors, Minneapolis (USA). The resulting product, Recycled Black, is comprised of numerous different-coloured pigments reclaimed during the manufacture of custom colourants. The company adds carbon black to give it a consistent, rich colour. It is designated Product 1010700. Plast. Tech., 1991, 37, (Aug.), 13
Additives adhesion
to promote
In this paper, the basic requirements of adhesion are described, followed by a consideration of those circumstances under which the use of adhesion promoters is particularly advantageous. The paper goes on to discuss adhesion promoters in terms of their chemistry, effectiveness and mode of action. Finally, some general conclusions are drawn concerning the use of adhesion promoters and the criteria for their selection. This overview has shown that a variety of compounds, mainly silanes, but also some titanates and zirconates, will function successfully as adhesion promoters. They may have some effect on the initial adhesion, but their main usefulness lies in the way they allow adhesion to be maintained in the wet and on drying out following immersion. Poly. Paint Col. J., 1991, 181, (May 15), 262, 264, 282
New additives for waterborne paints
2
Paints containing organic solvents will progressively be replaced by systems that are solvent-free or contain a considerably
01991 Elsevier Science Publishers Ltd.