| 摘要 |
1,059,553. Stencils. RISO KAGAKU COR PORATION. Aug. 4, 1964 [Aug. 3, 1963 (2); Aug. 19, 1963], No. 31686/64. Heading B6C. A stencil is formed from a stencil blank having designs represented thereon or placed in contact with an original by subjecting it to radiation, e.g. infra-red. A source of radiation is moved across within a container beneath an assembly comprising a glass plate, a shielding grid screen, the stencil blank, the original, and a reflecting cover disc of elastic material, the screen producing an untreated grid structure on the stencil to prevent breakage in the area of large design portions. The blank may comprise a single layer of heat-shrinkable film, e.g. stretched polypropylene resin or copolymer of vinylidene chloride and vinyl chloride; or a heat-shrinkable film bonded to a non-shrinkable porous base sheet of coarse tissue paper, pulp, fabric or fine meshed screen, the shrinkable layer being polyethylene and polyester resin; or a sheet containing shrinkable resin fibres such as nylon, polyethylene resin, polypropylene or, vinylidene chloride-vinyl chloride copolymer and non-shrinkable base fibres such as hemp, asbestos or glass. The blank is pre-treated with heat to cause an adjustable amount of pre-shrinking, the amount of shrinking under radiation depending on the remaining shrinkability. |
