| 摘要 |
379,833. Mineral-coated paper; coating webs. POTTS, H. E., 12, Church Street, Liverpool.-(Champion Coated Paper Co. ; Hamilton, Ohio, U.S.A.) Aug. 10, 1931, No. 22534 [Classes 96 and 140.] Paper, postcard, cardboard in a wet condition is coated by applying an aqueous mixture of at least 2/3 clay, satin white, blanc fixe and the like and not more than 1/3 casein, starch, glue and the like to the moving paper &c. or to an intermediate moving surface and removing the excess mixture by a doctor surface which is continuously cleaned and which moves in the opposite direction and at a speed above that at which the coating is ridged and below that at which it is frothy. The paper P, which has been moistened by steam &c. or by prior application of excess coating, passes over a roller A and excess coating C is removed by a doctor roller D, which is scraped by a doctor W of rubber, soft metal, &c., the coating C being supplied by a pipe. The rollers A, D are of non-absorbent material, e.g. steel and are in clockwise rotation. At low speeds of the roller D ridges are produced in the coating, and as the speed increases relative to that of the paper the ridges become less pronounced and closer together, the coating then becomes uniform, then streaky, then wavy or rippled and finally smooth but frothy, the coated paper having a pinhole effect. Rippled coatings are thus produced for " art " papers. The nature of the effects varies with the speeds, the coating composition, the distance apart of the rollers &c., the ridges occurring when the doctor speed is 1/7 and the ripples when it about equals that of the moving surface. In examples for paper speeds of 100 and 500 ft. per min., the ranges of doctor speeds for smooth coatings are 40 to 72 feet per min. and 136 to 214 feet per min. respectively. In alternative forms the roller A or the roller D is substituted by a travelling band or the coating is applied to the surface of the roller A and wiped off by the paper web which contacts with its surface and moves in the opposite direction. |
