| 摘要 |
<p>1528937 Powder coating TAKIRON CO Ltd 9 Dec 1975 [28 Dec 1974] 50323/75 Heading B2L [Also in Division B5] A plastics sheet having patterned regions of contrasting visual texture or colour is formed by depositing discrete areas of powdered material onto an intermittently forwarded conveyor, or a sheet carried by the conveyor through successive pattern screens, at least one having a guide member extending from the periphery of the aperture to the surface of the conveyor or sheet at an angle of 60‹-85‹ to the conveyor or sheet. The sheet thus formed is then heated to sinter and fuse it and may be coated with a protective plastics covering. In the described embodiment, a belt, passes below a series of screens 2, 3, 4, 5, fed with powdered resin, with or without a wetting agent such as oil, from associated hoppers, and then through a sintering oven 6, between embossing rollers 7 and through a fusing oven 8. Each screen comprises a plate 31 having an aperture 10 provided with a guide member 15, and powder is forced through the aperture with the help of at least one blade 30 reciprocable across the screen. The guide member may comprise a rubber, plastics or metal ring of wedge shaped crosssection (see Figs. 8 and 9, not shown) or of frusto-conical shape, or may comprise a bent down lip 37 of the plate 36 of the screen. It is preferred for the screens to include a metal mesh 32a or an array of parallel wires extending over the apertures. In operation discrete areas 32 are produced by the first three screens 2-4 and the fourth screen 5 fills in the spaces between these areas to form pattern sections which join under the flow caused in the subsequent heating ovens and embossing step. The powder may be PVC, PVA or PVF based, may be polythene or polypropylene, or may be a butadiene-styrene copolymer. If a backing sheet is used it may be of asbestos paper, glass fibre, or a plastics such as PVC. The finished sheet may be roll coated or sprayed with an acrylic or vinyl based plastisol.</p> |
