Patent GB-838999-A (GB)
Title: Improvements in or relating to laminates
Inventor: BULLOUGH WILLIAM
IPC: B32B15/08
Filed: 1957-05-15
Abstract: 838,999. Laminates and laminating; cutting apparatus. BRITISH IRON & STEEL RESEARCH ASSOCIATION. May 9, 1958 [May 15, 1957; Oct. 22, 1957; March 24, 1958 (2)], Nos. 15423/57, 32915/57, 9321/58 and 9322/58. Classes 31 (1) and 140. Sheet metal is laminated on one or both sides to polyvinyl chloride or other thermoplastic synthetic resin film by coating the metal with a heat-curable adhesive such as an elastomeric composition containing a phenol-aldehyde resin, heating to effect partial curing of the adhesive, pressing the resin layer by means of rolls and without heating to the hot coated metal, and cooling rapidly with water or other fluid sprays to prevent softening of the resin on emergence from the rolls while preventing penetration of cooling fluid to the entry side of the rolls. The metal is preferably steel but may be tinplate, galvanized sheet, or aluminium, and may comprise continuous strip or separate sheets. The resin may be plane or superficially embossed. As shown, Fig. 1, steel strip 12, drawn from a roll 13 and in succession through a degreasing bath 14, water sprays 18, a hot water bath 20 and squeegee rolls 22, is coated with an adhesive solution comprising phenol - formaldehyde and nitrile rubber by a roll-assembly 23, and then passed through a drier 24 and a heating chamber in which the adhesive is partially cured. Polyvinyl chloride strip drawn from a roll 28 is then applied to the hot metal strip by rolls 26 and is cooled immediately on leaving the rolls by a water spray 29 directed towards them, a similar spray being directed on to the underside of the strip 12 and away from the rolls. The laminated strip is then air-dried in a chamber 34, overlapping edges of P.V.C. are trimmed off by a cutter 35, and the strip rolled up at 36. To prevent penetration of water past the rolls 26 the lower roll is made non-wettable, by greasing or by nickel or chromium plating and rotates in contact with a rubber or neoprene squeegee roll 58; the upper roll 26 is rubber or neoprene coated and engages a small steel roll 59 in contact with a larger steel roll 60. The rolls are mounted in a frame the components of which are spring-pressed downwardly to press the rolls tightly together. Side plates (not shown) pressed against the ends of the rolls by screws acting through springs or rubber blocks, provide a seal against lateral penetration of water. The coating roll assembly 23 comprises rolls 40, 43, 44, 45, Fig. 2, the two latter rolls being driven from the squeegee rolls 22 to have peripheral movement opposed to and in the .direction of movement of the strip 12 respectively. Roll 40 dips into adhesive 42 in a bath 41 and roll 43 is held in adjustable contact with it and roll 44 by screws 48, 49 acting on the roll bearings 47 against rubber blocks 50, 52. The bearings 46 of roll 45 are adjustable vertically and laterally by screws 54. For coating both sides of the strip a second set of rolls 40, 43, 44 beneath the strip is provided. The edgetrimming device, Fig. 4, comprises a pair of circular blades 65, 66, having annular cutting edges 67 which are pressed against the edges of the strip 12 by sponge rubber pads 70 adhesively secured to the blades and to bushes 72; the latter are secured to but are longitudinally adjustable on a shaft 68 which passes through conical bores 69 in the blades, permitting them limited rocking movement to accommodate irregularities in the strip edges. The blades are separated for insertion of the strip by discs 78, 79 moved outwardly by nuts 80, 82 and contrascrewthreads on spindles 76, 77 coupled by a chain drive 91. The strip may be supported during the cutting operation by rollers 74, 75, Fig. 1, or may be held against buckling by upper and lower rollers. Instead of continuous strip steel, sheets 83, Fig. 5, may be fed in succession on to inclined rollers 81, aligned against an abutment as at 84, and forwarded by pairs of rollers 85, 86. A device 87 comprising a pair of rotary discs mounted on a spring hinge carrying electrical contacts stops the rollers 85 when the contacts are broken by overlapping plates, thereby holding back the second plate. The rollers 85 may be operated by a time-delay switch to feed sheets in timed succession. After lamination of separate steel sheets to a continuous resin strip the latter is cut between the sheets by a pair of blades 98, Fig. 7, welded or bolted together and traversed diagonally across the strip and back by a threaded shaft 99. The shaft is driven forwardly and then in reverse by an electric motor operated through a relay circuit 104, the latter being energized by the opening, in the interval between sheets, of contacts 103 normally closed by the sheets themselves. The blades 98 are spring pivoted to dip beneath the sheets during their return stroke and engage the underside of the sheets by means of a roller on their upper edge. For coating the individual sheets with adhesive the roller 45, Fig. 2, is rubber-covered and positively driven and drives the rollers 44, 43, 40.