| 摘要 |
The medium and liners of a water resistant containerboard are each essentially completely impregnated by a liquid water resistant agent which also uniformly coats the surfaces of the medium and liners with a layer sufficiently thick to cover the outer extremities of fibers protruding from such surfaces. The coating and impregnation is accomplished by feeding a flat untreated corrugated containerboard in the direction of its open flutes and in a continuous movement into and out of a hot melt bath of the water resistant agent at a controlled speed sufficient to force the liquid agent through the flutes of the containerboard, so as to assure exposure of all surface portions of the board to the hot melt for the same amount of time at the same temperature conditions. Upon removal of the board from the hot bath, the board is moved to a position with its leading edge uppermost to drain excess liquid agent from the board, which is then moved to a horizontal position to stabilize the depth of the liquid surface coating by the agent and then to a vertical position with the leading edge uppermost to reverse the direction of final drainage while the board is cooled to solidify the agent.
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