GB473657A - Improvements in or relating to the coating of absorbent materials - Google Patents

Abstract

In a continuous process for coating absorbent material such as paper, cardboard, textiles, and leather in long lengths with aqueous dispersions of solid water-insoluble synthetic resins, the coated material is rapidly dried at a temperature above 110 DEG C. so that the resin is deposited as a continuous film and then hot-calendered to produce a glossy surface. Suitable synthetic resins are polyvinyl chloride or acetate, polyacrylic acid esters, e.g. methyl methacrylate, polystyrene and polyhydric alcohol-polybasic acid resins. The drying temperature is above the softening point of the resin and high enough to remove all the water from the dispersion on the surface of the material in 5--10 seconds. If necessary, a further short heating at a lower temperature, e.g. 75 DEG C. may be given to remove absorbed water. Calendering may be done on a four-bowl calender at a temperature of 125 DEG C. and a pressure of 700 pounds per square inch. Wax may be incorporated in the dispersion to produce a film on the coated surface which may subsequently be removed by polishing. In the example, a dispersion is prepared by adding to methyl methyacrylate, caustic soda solution, a peroxide, dibutyl phthalate and cyclohexanone, stirring and heating to 80 DEG C. to polymerize. 10 per cent of an emulsion of white wax is then added.