| 摘要 |
Apparatus and methods for producing intermittent, discrete patterns of coating material, such as hot melt adhesive, onto discrete substrates or substrate areas, where the patterns have sharp, square leading and trailing edges, as well as side edges. A slot nozzle die has elongated air slots along the slot extrusion opening. In the operation of the apparatus, the air flow is initiated from both air slots prior to the initiation of the hot melt flow. Also, the air flow is continued beyond that point in time, when the hot melt flow ceases. The delays between the operations of the air flow and the hot melt flow are on the order of micro seconds. Coating weights down to 1 gram per square meter at about 350 meters per minute substrate speed are provided. Alternatively, the lead and lag air start and stop times on each side of the coating material are different to control the exact disposition of the square cut-on and square cut-off coating edge on the substrate.
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