| 摘要 |
1423027 Seaming non-metallic sheet material DYNAMIT NOBEL AG 20 June 1973 [30 June 1972] 29399/73 Heading B5K Synthetic plastics films or sheets are joined with a lop joint or butt joint together using adhesives, solvents or heat in conjunction with pressure with at least one transparent film or sheet constituting an uppermost layer at the joint, inspection of the joint being produced being made possible by making the joint visible by a chromophoric material. If a lap joint is produced between two films or sheets, the upper film or sheet at the joint serves as the transparent film or sheet. If a joint is produced by using an adhesive or a solvent, a coloured adhesive or solvent is used. The adhesive may be of the solvent type, e.g. based on nitrile rubber. Polyvinyl chloride sheets may be welded using tetrahydrofuran as a solvent. If the joint is produced by the application of heat, the transparent film or sheet has incorporated therein, or applied thereto, a substance which, when subjected to the thermal action required to join the films or sheets, undergoes colour change when the joining temperature is reached. The transparent film or sheet may be constituted by a cover strip used to produce the joint. A transparent film may be provided over the joint as an additional covering means by application of a film forming solution, e.g. soft polyvinyl chloride dissolved in tetrahydro. furan, and removal of the solvent, this film being coloured with a contrasting colour to that which is used to indicate the joint. |
