Patent GB-1054795-A (GB)
Filed: 1963-08-09
Abstract: 1,054,795. Laminates and laminating. ROGERS CORPORATION. Aug. 9, 1963, No. 31567/63. Heading B5N. [Also in Divisions Dl and F4] At least one web 44 (Figs. 1 and 2, not shown) of porous sheet material (e.g. a non-woven fabric of fibres known under the Trade Mark of Dacron; a woven fabric of glass fibres; tightly bonded blends of glass fibres and organic synthetic fibres; lightly bonded glass fibre papers; other synthetic organic or inorganic film structures or open cell foamed sheeting) is impregnated with a resin (e.g. an epoxy resin with curing agent, accelerator, flow controlling filler and solvent; a polyester resin solution or phenol formaldehyde resin saturant) by being passed between a pair of adjustable squeeze rollers 20, 22 in the nip of which is contained the impregnant 60. In Figs. 1 and 2, two webs 44 are provided and brought together with a carrier sheet 36, e.g. of a silicone treated sulphite release paper at the roller pair. Roller 20 is mounted on an adjustable arm 26 so that the roller gap may be adjusted. After impregnation the combined sheet is stripped from roller 22 by a blade 64 against which the sheet is pressed by a spring urged adjustably positioned shoe 62. The combined sheet 68 is then drawn through a dryer 12 by tension rollers 45, 47 driven, e.g. through a slipping clutch. At the rollers 45, 47 at least one additional web 44a (similar to webs 44) is laid on the combined sheet 68 and an upper carrier sheet 36a is subsequently laid on the assembly before it is passed to a heated press 16 wherein the saturated material is compressed and set. The top and bottom carrier sheets and the impregnated web are wound up on mandrels 86, 90, 88 which are driven via clutches or slip belts to provide a constant tension. The press 16 is operated with a frequency such that each section of the web receives five or six pressings on its passage through the press. Clamping members 87, 89 intermittently clamp the combined sheet to prevent the tension created by the wind up mandrels running back to the rollers 45, 47. The carrier sheets may be left on the impregnated web to become part of the final product, or the addition of the webs 44a and the carrier web 36a may be dispensed with. The carrier sheets may comprise copper foil, allowed to remain on the final product so that a copper clad electrical insulating sheet is formed. Dryer.-The impregnated sheet of non- woven fabric 68 (Fig. 1, not shown) has solvent driven therefrom by being passed through a dryer 12 in which air is drawn in through steam heated coils 76, is diffused against the sheet 68 by air flow diffusers 78 and is exhausted by a blower 74. Press.-A heated press for compressing and thermosetting a non-woven fabric 68 (Fig. 3, not shown) impregnated with an epoxy resin comprises a lower heated platen 84 covered with a reinforced thermoset plastic shim plate 92, a thin stainless steel plate 94 and one or more thin plies of rag or kraft paper board 96. The platen 82 has several plies of thin kraft or rag board 100, a stainless steel plate 102 and one or more plies of heat resistant, rubberized glass fabric 104. Upper and lower webs 98a, 98, e.g. of a silicone treated sulphite release paper are slowly and intermittently drawn across the plates to prevent an accumulation of dirt or resin thereon.