| 摘要 |
1,095,307. Wax coatings. SUN OIL CO. Oct. 29, 1965 [Nov. 23, 1964], No. 45915/65. Heading B2E. [Also in division G1 A method of impregnating and coating fibrous sheet material, e.g. paper, comprises (1) applying to the sheet material a surface coating of a mixture of paraffin wax and microcrystalline wax, the difference in melting points between the two waxes being at least 15‹F and the impregnation of the sheet by either of the waxes being less than 50%, (2) bringing the surface coating to a temperature between the melting points of the waxes, at which the paraffin wax is molten and the solubility of the microcrystalline wax therein is less than 10%, (3) holding the surface coating at this temperature until the resulting molten paraffin wax impregnates the fibrous sheet material, and (4) cooling the waxes to below the melting points of both of the waxes whereby there is obtained fibrous sheet material impregnated with solid paraffin wax and surface coated with a solid wax composition which is richer in microcrystalline wax than the surface coating applied in (1). The coating applied in (1) may be applied by curtain coating or by reverse roll coating. This coating may be cooled to solidify the waxes before heating to a temperature suitable for stage two or it may be cooled directly to such a temperature. The surface coating obtained in (4) may contain from 1-50% of microcrystalline wax. |
