Patent GB-888367-A (GB)
Title: Methods of bonding polyurethane
Inventor: DICKEY JOHN WAKEMAN
IPC: B29C65/48
Filed: 1958-01-14
Abstract: 888,367. Laminates; stretching fabrics. REEVES BROS. Inc. Jan. 14, 1958, No. 1342/58. Classes 42 (1) and 140. [Also in Group XI] Laminates.-A body of polyurethane foam is joined to another material by exposing the surface of the body to high temperature, the temperature and time of exposure being such that the thickness of the body is reduced and the exposed surface rendered tacky without other perceptible change in the body, the other material being applied, e.g. under pressure, while the surface is tacky. The other material may be a fabric, e.g. a nylon tricot, canvas or paper, and may be applied when the tacky surface is in a " super-cooled " condition, i.e. has cooled to a temperature below its melting- point. As shown in Fig. 1, a web 3 of polyurethane foam from a supply roll 1 is led under the idler roller 3<SP>1</SP> on to the wire mesh conveyer belt 4, having a supporting-plate 4<SP>1</SP> under it. It passes under the gas-burning refractory heater 7 which heats its upper surface by radiation, and optionally also by direct impingement of the flame. The polyurethane may alternatively be heated by simple flame-impingement, or by an electrically-heated rod or blade in contact with it. The shield 26 protects the fabric sheet 24, drawn from a roll 25, from the heat of this burner, and the roller 23, which may be coated with an anti-adhesive such as polytetrafluorethylene, rolls it on to the heated surface of the polyurethane. The edges are trimmed by the motor-driven cutters 27, and the product passes under the idler roller 34 and is wound up at 33. 2 and 35 are reserve supply and take-off rolls to avoid interrupting the flow of work when the rolls 1 and 33 are empty or full respectively. As shown in Fig. 7, a piece of foamed polyurethane is stretched longitudinally, and preferably laterally also, on the stretcher 113, which is then placed on the conveyer 136. This carries it under a gas-burner 137, the flame of which impinges on the polyurethane. The layer 112 is protected from the heat by the shield 144, and applied to the tacky surface by the roller 145. The product is discharged on to the table 146. If the stretcher 113 is of open-frame construction another layer may be simultaneously or sequentially bonded to the other side of the polyurethane. As shown in Fig. 9, a web 215 of polyurethane from supply roll 219 passes over a braked roller 221 and through an edge-guiding and lateral tensioning device 233 to the drum 229. The backing web 216 from the roll 244 passes round the braked roller 246 and the idler roller 254 to the drum 229. The polyurethane is heated on its surface by impingement of a flame from the gas burner 262. The drum 229 is preferably cooled, e.g. by circulating water within it. The web 216 may be preheated by a heater 271, e.g. of the electrically operated air-blast type, and may be spread and laterally tensioned in the same way as the polyurethane layer. The laminated product travels round a substantial arc of the drum 229, and then over the guide roll 255, to the winding-up roll 256. The product is tensioned on the drum 229 by driving the roll 256 to have a higher peripheral speed than the drum. Stretching fabrics.-Part of an apparatus for stretching the layer of polyurethane is shown in Fig. 8. A board 114 is provided with pins 115 at each end. The layer is pressed on to these pins at one end, then stretched and pressed on to the pins at the other end. The board also has lateral stretcher means 116 along each edge. Each of these comprises a U-shaped member having pins 121 on its upper surface. These members 116 are adjustable by means of screws 122, with swivel feet 124, threaded through holes in the U-member. When both ends of the layer have been secured, the edges are pressed on to the pins 121. The screws 122 are then turned to tension the layer to the desired extent. Hold-down means 126 comprise an L-shaped member secured to the U-shaped member by screws 135. A layer so stretched may then be laminated in the apparatus of Fig. 7. Specifications 888,368 and 888,369 are referred to.