Development and Characteristics of Multipurpose Transparent Polyurethane Film.

In industry, recent research developments include flexible films and foldable films. The next step is the development of stretchable films, and studies are being intensively carried out. Research on the development of stretchable and transparent materials is also increasing greatly. Currently, polydimethylsiloxane (PDMS) is the most commonly used film in the industry. However, PDMS surfaces are hydrophobic, so their use is limited to making materials and compounds with hydrophilic properties. In this study, we developed a transparent polyurethane film that can be used for multiple purposes. A transparency comparison between the transparent polyurethane film and the general polyurethane film was used to verify their future application. The conventional polyurethane films showed a transmittance rate of 2.2 percent, but the transparent polyurethane films achieved a high transmittance rate of 85 percent. To determine whether the film can be realized, we produced a conductive paste using resin for the transparent polyurethane film. In addition, a conductive paste was made based on the material used in the transparent polyurethane film to verify the hardness and reliability of the adhesion of electrodes, and we confirmed this with thermogravimetric analysis (TGA). The transparent polyurethane based paste was made with stretchable electrodes through a screen printing method. The manufactured stretchable electrodes were demonstrated by mechanical and adhesion tests. Finally, a permittivity test was conducted to determine the suitability of the film for application to printed electrodes for antennas in the future. The genetic rate of transparent polyurethane films was better than that of conventional polyurethane films. Moreover, the adhesion of the transparent polyurethane film and stretchable electrodes was as good as that of conventional polyurethane film and stretchable electrodes, and observation by optical microscopy confirmed that the printing performance was also excellent. In addition, the conductive paste made based on the transparent polyurethane film material was cured for 1 hour at 120 °C, and TGA analysis confirmed that both the binders and curing agent responded well in the test for curing the developed stretchable electrodes and transparent polyurethane.