Light-driven coating of thin film in a non-equilibrium field

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02507
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 27010:Transport phenomena and unit operations-related
• Research Institution: Kyushu Institute of Technology
• Principal Investigator: yamamura masato 九州工業大学, 大学院工学研究院, 教授 (90284588)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: drying / thin liquid film coating / photo polymerization / diffusion / phase separation

Outline of Final Research Achievements

This study aimed at developing a non-equilibrium photo-curing coating technology, in which radical polymerization reactions via UV irradiation, spontaneous phase separation between solvent and polymerized products, and multicomponent diffusion driven by the reaction and the solvent evaporation can proceed and couple each other. The results showed some new findings: (1) the reaction promotes solvent diffusion along the direction of light, (2) the photo-driven diffusion flux depends on the drying history until photo irradiation, and (3) columnar porous polymer films can be fabricated under particular range of solvent concentrations and intensities of photo irradiation. Furthermore, a new theory was developed to predict the maximum concentration variations in photo-driven solvent transport. The theory showed a good agreement with measured values in reaction systems with high glass transition temperatures.

Free Research Field

塗布膜乾燥

Academic Significance and Societal Importance of the Research Achievements

液晶ディスプレイに欠かせない光学フィルムは、高速走行する基材上に液体を塗布したのち、紫外線照射によって液体内でラジカル重合反応を起こすことで、塗布膜を光硬化させて製造される。この工程では１s以内で重合反応を完結させる必要があり、硬化過程の正確な理解や制御が求められる。本研究では、光反応、溶媒乾燥、相構造形成が同時に進行する非平衡場を利用して、同一組成の溶液から異なる内部構造を有する薄膜を作り分ける光製膜分野の開拓を目指した。その結果、硬化中に光照射方向への溶媒移動が生じること、特定の条件で光照射方向へ伸びた柱状多孔質構造が形成することを明らかにした他、溶媒移動量を推算可能な理論式を導出した。