Improvement of cross-machine directional thickness deviation for uniform pressure-sensitive adhesive layer in roll-to-roll slot-die coating process

In this study, a roll-to-roll (R2R) slot-die coating process for producing pressure-sensitive adhesive (PSA) layers was developed. PSAs are used for display applications and the production of various types of films based on lamination processes. The slot-die coating process has been adapted to uniform large-area deposition. However, in actual adhesive coating using a large-area R2R system, a cross machine directional difference in coated thickness is observed. Based on a previous study, the coating speed and coating gap were selected as the main controllable coating parameters that influence the adhesive layer thickness. An experimental study was performed to optimize the coating condition. By using statistical and mathematical approaches, an excellent coating layer was obtained with 50-nm roughness, 5-μm thickness, and 1.6-μm waviness at a high coating speed of 10 m/min and coating gap of 300 µm. The proposed process logic and guideline could be applied to mass production in the industry.

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