Process for the treatment of paper or board to increase the impermeability to water vapour and aromas, and paper or board treated by this process

摘要

Process for the treatment of paper or board to increase the impermeability to water vapour, the paper or the board being treated with a coating agent which contains a mixture of paraffin dispersion and an aqueous dispersion of styrene-butadiene, and also a polyacrylate (III) and, if appropriate, the usual additives, such as isopropanol, pigments and the like, characterized in that the coating agent contains 40-60 parts by weight of a dispersion (mixture A) with about 45% solids content, which consists of about 16% paraffin (wax) and about 29% carboxylated styrene-butadiene (related to the total quantity of the dispersion), the carboxylated styrene-butadiene containing about 3 mol% carboxyl groups, which are present for the most part as ammonium salt, and about 40 mol% styrene and about 57 mol% butadiene, and the macromolecule being three-dimensionally crosslinked via the second double bond of the butadiene, and contains about 25 parts by weight of a thermally crosslinkable polyacrylate which contains about 22 mol% methyl acrylate, about 52 mol% ethyl acrylate and about 26 mol% butyl acrylate, the average molecular weight being about 500,000, and contains about 40 parts be weight of water.