The roll coater includes a set of cylindrical rollers having various functions. In addition to its drive roller to move the base paper through the coater, the more important features are:
Metering—Apply an appropriate amount of wax to the top coat roller. Top coat - apply wax to the base paper. The upper coating roll can be engraved or embossed so that only a portion of the base paper is applied. The second set of metering and upper coating rolls can be located below the plane of travel of the base paper so that both sides of the base paper can be coated. Sanding - smooth the wax on the base paper. The direction of rotation of the sanding roller is generally opposite to that of the base paper. If a particular base paper and wax combination is desired to have a high gloss, the surface of the waxed base paper can be remelted and rapidly hardened with cold water (about 5 ° C).
In the late 1960s and early 1970s, the development and commercialization of sprinklers was achieved. The sprinklers fully saturate the waxes of the grooved and printed corrugated box blanks. The device transports individual papers. Box blanks (each blank is vertically aligned and separated from each other by a rack system) through a wax overflow or spray point formed by a weir or nozzle. Excess molten wax from the top and leached sections is concentrated at the bottom of the unit and recycled. The entire system is closed in such a way that the incoming cardboard can be preheated with warm air, the billet is hot leached after waxing, and then cooled with cold air before being packaged, stacked and ready for shipment. The output per line is generally slightly less than the system. The amount of wax absorbed is also 40% to 50% of the weight of the original board. However, the new type of sprinkler allows the operator to obtain more adjustment control than the impregnator, and if desired, he can control the lower limit of the amount of wax used, as well as the flexibility to produce dry waxed or wet waxed articles. There was no statistically significant difference in the water resistance of the waxed carton between the products prepared by the dipping method or the spray method with the same amount of wax absorbed. The shower creates a better and more uniform surface. The individual cooling of the blank eliminates the hassle of sticking adjacent blanks.
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