it is used in the production of external protective 2 and 3-layer polymer coating of steel pipes as a hot-melt polymer sublayer applied by the method of slot extrusion
. the adhesive composition should be made on the basis of high-pressure polyethylene with grafted functional anhydride and carboxyl groups, and provide quality indicators of the protective coating in accordance with gost 9
A basic premise made at the start of Part II was that cutting of waste carpeting into thin strips followed by mechanically feeding the strips into an extruder would be an adequate feed for the slot extrusion and backcoating process.
We concluded at the beginning of Part 11 that we would probably have to supply a mechanical feeder and a specific slot extrusion die for any extruder to be used in our extrusion backcoating trials and that the backcoating line would need to have a laminating module at the end of it to combine the substrate with the molten waste as it emerged from the slot extrusion die.
This manufacturer had 31" and 53" slot extrusion dies for use on the extruders and was willing to run extrusion backcoating trials for us.
In this trial a 31" slot extrusion die was used instead of the 53" one to economize on the use of available granulated waste.
The granulated waste was found to be too viscous to flow properly for all four possible hot melt application variations: 1) open pan with application roll, 2) spray application, 3) slot extrusion and 4) closed pan with application roll.
Trial a - Slot extrusion trial using polypropylene waste containing polyethylene fiber binder: This trial consisted of melting carpeting waste as is without granulation and extruding it through a slot-extrusion die into a backcoating film using only one extruder.
Trial b - Slot extrusion trial - polypropylene waste containing a non-crosslinked PvAc latex binder: This trial proceeded smoothly using 1 1/2" wide waste strips and the same processing conditions as those in the first trial above and essentially the same results were obtained.
Trial c - Slot extrusion trial - polypropylene waste containing a crosslinked PvAc latex binder: This trial also proceeded smoothly using 1 1/2" wide waste strips and the same processing conditions as those in the first trial above and essentially the same results were obtained as in that trial.
Trial d - Slot extrusion trial using polypropylene waste containing a crosslinked PvAc latex binder and having a pressure-sensitive adhesive on back: Polypropylene carpeting containing polyethylene fiber or crosslinked latex as a binder and having pressure-sensitive adhesive on the back for adhering it to car or car-trunk flooring is a fast-growing product line.