“…We expect that the overexposed white snow-like appearance can be utilized in interior decorative design. In addition to decorative design applications, the ET method is also expected to be applicable to products frequently used in embossing technology, e.g., light diffusion 50 – 52 ; the fabrication of anisotropic light reflection 53 films and sheets, and microfluidics such as microwells 54 – 57 and microchannel 58 , 59 parts; and braille 60 , 61 formation. Figure 10 Examples of patterns formed on plastic film.…”
Forming large pitch and depth patterns spontaneously based on a bottom–up approach is a challenging task but with great industrial value. It is possible to spontaneously form an uneven (concave–convex) patterns with submillimeter-to-millimeter-scale pitches and depths by the direct pattern exposure of a UV-curable oil-in-water (O/W) emulsion liquid film. UV irradiation generates a latent pattern of a cured particle aggregation in the liquid film, and an uneven structure is spontaneously formed during the subsequent drying process. This process does not require any printing and embossing plates or development process. In this report, we presented an example of unevenness formation with a maximum pattern depth of approximately 0.4 mm and a maximum pitch width of 5 mm. The patterns formed by this method have raised edges in the exposed areas and fogging in unexposed areas. The pattern shapes become conspicuous under overexposure conditions, but the formation mechanism has not yet been understood in detail and needs to be investigated. In this study, we focused on the exposure process and clarified the mechanism of pattern formation by analyzing the dynamics of emulsion droplets in the medium by an in situ microscopy observation method. As a result, we found that the fogging was mainly caused by light leakage from the exposed area, and the raised pattern edges were caused by droplets transported from the unexposed area to the exposed area. Furthermore, the convection caused by the heat generated from polymerization is a determining factor affecting all these phenomena. By controlling the pattern shape related to convection utilizing direct projection exposure, we showed an example of eliminating raised pattern edges with a height difference of approximately 0.1 mm. By devising and selecting exposure methods, we can expand the range of design applications such as interior decorative patterns.
“…We expect that the overexposed white snow-like appearance can be utilized in interior decorative design. In addition to decorative design applications, the ET method is also expected to be applicable to products frequently used in embossing technology, e.g., light diffusion 50 – 52 ; the fabrication of anisotropic light reflection 53 films and sheets, and microfluidics such as microwells 54 – 57 and microchannel 58 , 59 parts; and braille 60 , 61 formation. Figure 10 Examples of patterns formed on plastic film.…”
Forming large pitch and depth patterns spontaneously based on a bottom–up approach is a challenging task but with great industrial value. It is possible to spontaneously form an uneven (concave–convex) patterns with submillimeter-to-millimeter-scale pitches and depths by the direct pattern exposure of a UV-curable oil-in-water (O/W) emulsion liquid film. UV irradiation generates a latent pattern of a cured particle aggregation in the liquid film, and an uneven structure is spontaneously formed during the subsequent drying process. This process does not require any printing and embossing plates or development process. In this report, we presented an example of unevenness formation with a maximum pattern depth of approximately 0.4 mm and a maximum pitch width of 5 mm. The patterns formed by this method have raised edges in the exposed areas and fogging in unexposed areas. The pattern shapes become conspicuous under overexposure conditions, but the formation mechanism has not yet been understood in detail and needs to be investigated. In this study, we focused on the exposure process and clarified the mechanism of pattern formation by analyzing the dynamics of emulsion droplets in the medium by an in situ microscopy observation method. As a result, we found that the fogging was mainly caused by light leakage from the exposed area, and the raised pattern edges were caused by droplets transported from the unexposed area to the exposed area. Furthermore, the convection caused by the heat generated from polymerization is a determining factor affecting all these phenomena. By controlling the pattern shape related to convection utilizing direct projection exposure, we showed an example of eliminating raised pattern edges with a height difference of approximately 0.1 mm. By devising and selecting exposure methods, we can expand the range of design applications such as interior decorative patterns.
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