Patent GB-1017105-A (GB)
Title: Improvements in or relating to the production of reinforced synthetic sheet material
IPC: B29C70/50
Filed: 1962-08-07
Abstract: 1,017,105. Making re-inforced plastic sheets. USINES CHAUSSON S.A. Aug. 7, 1962 [Sept. 4. 1961], No. 30279/62. Headings B5A and B5N. Partially cured, deformable, laminated sheets of reinforced synthetic resin are made in the equipment illustrated, in which continuous strips of re-inforcing fabric (27 . . . 30) are fed from devices (37 . . . 40) and coated on at least one face with heat-setting resin at coating points (31 . . . 34), the strips passing through calendering rollers (81 . . . 84); a sandwich strip comprising all four strips then passes between endless belts (86, 87) through a resin gelling stove (85), the belts being. coated with a polymerization accelerator, the sandwich strip being cut by a device (115, Fig. 2, not shown), on leaving the stove. Continuous feed device (38) comprises a turnstile (41) carrying three reels of fabric (49, 50, 51) which are fed consecutively through a storage magazine (45). The magazine's capacity is varied by raising a carriage (70) carrying a lower set of rollers (71), over which the strip is wrapped, towards an upper set (69). This enables a continuous flow of the strip out of the magazine to be maintained while the input of strip is stopped during reel changing. A joining device (42) joins consecutive reel ends together by heat, ends of strips on each reel being gum-impregnated. Two heat-setting resins (A, B) are separately mixed in tanks (9a, 9b) fitted with automatic weighing machines, stored in tanks (20a, 20b) and delivered by ducts (26a, 26b) to the coating points, where they are mixed together and applied. Larger rollers downstream of the coating points force the resin into the fabric strips. The stove is vertically orientated and heating plates (94) are heated electrically or by infra-red rays, hot water or steam circulation or microwaves. An air-cooled tunnel may be provided downstream. The belt (87) is given a thin coat of heat-setting resin, from a box (110), which is heated in a stove (111) before being applied to the strip in stove (85). The polymerization accelerator is applied to the belts at points (114 6  and 114 7 ). Cutting device (115) may comprise a rotary saw and moves with the strip while traversing it. The reinforcing strips may. be glass fibre and previously impregnated with a polymerization " restrainer " comprising ethylene glycol or its derivatives and a salt such as a chloride, sulphate, naphthenate of tin, iron, zinc, aluminium, barium, cobalt or manganese, or a mixture of these. The resins A, B are preferably polyesters and may comprise a catalyst such as benzoyl peroxide, a polymerization inhibitor such as a solution of 4-methyl-2,6- ditertiary butyl phenol or dibutyl tertiary paracresol at 6% in styrene, and a " restrainer " as above. The polymerization accelerator applied to the belts may comprise mono or symmetrical di-alcoyled anilines, derivatives of a guanidine of the alcoyl-aryl-guanidine type, or mono or di-isocyanates. The belts may be lubricated with wax, comprising stearamid of hydrogenated castor oil or paraffin wax such as polyethylene wax combined with stearates such as zinc stearate. The net result of these chemicals is that the sandwich strip emerges from the stove in a partially polymerized state, so that it can be hot-pressed, possibly after long storage, which process completes polymerization.