Abstract A method is described for the coating of running strands or webs with a thermoplastic protective layer. The successive steps comprise the application of a primer and the hot air current drying and curing of same supplemented by inductive heating. The temperature is next raised in two successive stages by inductive type heaters, the later stage while the strand or web is vertically traversing the length of a continuously replenished dense cylindrical bed of powdered vinyl polymer or the like. The replenishment as well as cooling of the powder is accomplished through a recirculatory arrangement powered by air nozzles. Alternate coating materials are proposed including polyolefins containing compounds of metal.
The process as recited in claim 1, and additionally the step of baffling and vibrating and thereby separating said cooled portion of the excess pulverulent material from the gaseous carrying medium for said excess pulverulent material during said returning of the cooled portion of the excess pulverulent flowing material to the upper end of said compacted mass.
Claim 2
Dependent Claim
15 words
The process of claim 1 in which said moving surface of said article is metallic.
Claim 3
Dependent Claim
23 words
The process as recited in claim 3, in which said primer is a thermosetting material and said pulverulent flowing material is vinyl polymer.
Claim 4
Dependent Claim
39 words
The process as recited in claim 3 in which said primer is a weak acid solution of a base metal higher in the electromotive series than the metal of the metallic surface, and the fusible plastic powder is polyolefin.
Claim 5
Dependent Claim
26 words
The process of claim 5 in which the polyolefin contains an agent for cross-linking with said metallic surface during fusing of said polyolefin to said surface.
Claim 6
Dependent Claim
12 words
The process of claim 5 in which the polyolefin contains powdered metal.
Claim 7
Dependent Claim
24 words
The process as recited in claim 1, wherein said pulverulent flowing material is applied in the same direction of movement as said moving surface.
Claim 8
Dependent Claim
24 words
The process as recited in claim 1, wherein said pulverulent flowing material is applied in an opposite direction of movement as said moving surface.