GB1131571A - Multi-color screen printing - Google Patents

Abstract

1,131,571. Screen printing processes. ADVANCE PROCESS SUPPLY CO. 6 June, 1966 [28 July, 1965; 21 Oct., 1965], No. 25025/66. Heading B6C. In a multi-colour screen printing process a thixotropic ink is used at each printing station and no provision is made for intermediate drying, the inks subsequent to the first being applied to the still wet imprinted object through stencils each of which incorporates a spacing screen the function of which is to prevent the already applied ink from contacting the associated stencil. The spacing screen is of such a size, mesh and material that the inks used do not adhere. Suitable materials are said to be nylon, stainless steel, polyesters and polytetrafluoroethylene. In the two-colour sheet-fed stencilling machine shown in Fig. 10 pivotally mounted screens and associated equipment 43, 44 are operatively engageable with printing frames 37, 38 respectively. Each frame includes a vacuum table for holding each paper copy sheet 7 during the printing stroke of the relevant squeegee. The machine is automatically driven by a motor 50, the sheets 7 being intermittently fed to and from the two printing stations by a chain drive 40 carrying sheet gripper means 41, 42. The movement of the chain drive 40 derives from the reciprocating motion of a carriage 67 which has pusher members 69 engageable with the parts 41 of the gripper means. Registration of the sheets at the printing stations is effected by interengaging pins and holes associated with the printing frames 37, 38 and the gripper means. The screen assembly 44 incorporates a spacing screen 14, Fig. 6. Three or more printing stations may be provided and Fig. 14 shows a machine in which sheets 218 are carried by grippers 217 along an endless band 201 through three such stations, each comprising a reciprocable screen arrangement and an impression member in the form of a cylinder. In a further construction of screen arrangement at each printing station subsequent to the first the spacer screen is in the form of an endless band which is caused to intermittently move across the face of the printing stencil' so that a clean spacer screen surface is provided for each impression. The arrangement also incorporates means by which the used part of the band may be cleaned before re-use.