Patent GB-440368-A (GB)
Title: Improvements in the production of a protective coating of hard rubber on paper, pasteboard and the like
IPC: D21H19/22
Filed: 1934-06-29
Abstract: Rigid, non-flexible articles having a hard rubber surface are made by impregnating a dry or dried base of porous material, e.g. paper, pasteboard, papier m<\>zach<\>ae, fabric or wood with a hard resin, then applying a rubber mix containing at least 15 per cent of sulphur and vulcanizing.  Hard resins are defined as being at least as hard as ordinary colophony and include colophony which has been heated with calcium oxide, zinc oxide or glycerine and hardenable resins such as phenol-formaldehyde condensation products.  The base may be pressed before, during or after impregnation.  Metallic netting, rods or spirals may be embedded in the base or in the plastic rubber coating.  In examples: (1) pasteboard is dried and impregnated with a solution of phenol-formaldehyde resin in alcohol or acetone, e.g. under pressure or vacuum.  Solvent is removed and the resin hardened by heat.  A plastic mixture containing rubber chalk, hard rubber dust, linseed oil, powdered sulphur, calcium carbonate and thiourea is applied by spreading and subsequently vulcanized.  (2) Plywood is dried, impregnated with hardened colophony, compressed and a sheet of a plastic composition containing rubber, litharge, zinc sulphide, barytes, sulphur, linseed oil and an accelerator is applied and vulcanized under pressure.  (3) A thick textile is dried and impregnated with a lacquer comprising hardened colophony and phenol-formaldehyde resin dried and coated with a composition comprising concentrated rubber latex, powdered sulphur, zinc carbonate, kieselguhr, aqueous ammonia and zinc stearate, which is then vulcanized in two stages.ALSO:Rigid, non-flexible articles having a hard rubber surface are made by impregnating a dry or dried base of porous material, e.g. paper, pasteboard, papier m<\>zach<\>e, fabric or wood with a hard resin, then applying a rubber mix containing at least 15 per cent of sulphur and vulcanizing.  Hard resins are defined as being at least as hard as ordinary colophony and include colophony which has been heated with calcium oxide, zinc oxide or glycerine and hardenable resins such as phenol-formaldehyde condensation products.  The base may be pressed before, during or after impregnation.  Metallic netting, rods or spirals may be embedded in the base or in the plastic rubber coating.  In examples: (1) pasteboard is dried and impregnated with a solution of phenol-formaldehyde resin in alcohol or acetone, e.g. under pressure or vacuum.  Solvent is removed and the resin hardened by heat.  A plastic mixture containing rubber, chalk, hard rubber dust, linseed oil, powdered sulphur, calcium carbonate and thiourea is applied by spreading and subsequently vulcanized; (2) plywood is dried, impregnated with hardened colophony, compressed and a sheet of a plastic composition containing rubber, litharge, zinc sulphide, barytes, sulphur, linseed oil and an accelerator is applied and vulcanized under pressure; (3) a thick textile is dried and impregnated with a lacquer comprising hardened colophony and phenol-formaldehyde resin dried and coated with a composition comprising concentrated rubber latex, powdered sulphur, zinc carbonate, kieselguhr, aqueous ammonia and zinc stearate, which is then vulcanized in two stages.