DE2431952

1515541 Coating glass receptacles with thermosetting resin RESICOAT GmbH BESCHICHTUNGSPULVER 23 May 1975 [3 July 1974] 22998/75 Heading B2E Glass receptacles are coated with a thermosetting resin which has been softened prior to application either by addition of a softening agent or by internal softening, in order to provide a scratch-resistant, shatter-proof, alkali-stable article of low frictional resistance. The resin may be applied as granules of size less than 125Ám by electrostatic spraying or by immersion in a vortex bed or an electrostatic vortex bed. The receptacle may be pretreated with an adhesion promoter and may be preheated to at least 50‹C. The coating may be hardened in a convection or infrared oven at 150-250‹C, unless the preheating renders this unneccessary and may be at least 50Ám thick. Specified resins: epoxy, acrylate, polyester and polyurethane. Softening agents for addition to resins include epoxide esters, epoxidised oils, thermoplastic polyesters and polyvinyl butyrals. Internal softening may be achieved by including a softening substance which reacts to form part of the resin, e.g. as follows. Epoxy resins: by condensing bisphenol A and epichlorohydrin in a molar ratio of 0.80-0.95, or by partial esterification. Polyesters: by including at least 10 wt.% of certain glycols and aliphatic acids. Acrylates: by including at least 10 wt.% of certain acrylic acid esters. Polyurethanes: by rising blocked isocyanates as a cross-linking agent.