GB462754A - Improvements in method of coating paper - Google Patents

Abstract

462,754. Coated paper. BURGESS, A. F. (Paper Patents Co.) Oct. 15, 1935, No. 28445. [Classes 96 and 140] In coating paper with a fluid mixture containing in suspension solid particles varying in size, e.g. china clay, an excess flow of the coating mixture is maintained at the point of application of the mixture to the paper, the coarser particles being continuously removed by withdrawing the excess of the mixture at the point of application, treating it to remove coarser particles by sedimentation and returning the residue of such excess to the original stock of coating mixture. As shown, a paper web A, Fig. 1, from the wet end of a paper machine is passed over drying cylinders 10, 11, between felts 12, 13 and into the nip of press rolls 16, 17 where it is coated on one side with finishing-material; then over a heated drum 18 and roll 19 to a second coating apparatus 22, 23 from which it passes over a heated drum 24 and roll 25 to drying cylinders 26, 27, 28 associated with felts 30, 31. The coating-material passes from a supply tank 32, Fig. 2, to a head box 36 through a float-controlled valve 37 and thence to a coating doctor associated with the rolls 22, 23, via a distributing weir 40 and pipes 48. Excess coating material passes through pipes 62 to a head box 63 and is conveyed by a pump 64 to an overhead settling tank 66 wherein coarser particles, separated by sedimentation are discharged at the bottom by a driven screw, the usable residue passing back to the head box 36 via a distributing weir 67. The coating doctor comprises members 49, 50, Fig. 4, carrying a bottom rubber strip 51 engaging the lower roll 23, and end strips 53, the whole being adjustable relatively to the roll 23. The pipes 48 lead into distributing boxes 60 and the pipes 62 extend through the lower portion of the end walls of the doctor.