5TH International Congress on Technology - Engineering & Science - Kuala Lumpur - Malaysia (2018-02-01)

Color Change Analysis Study Using Thermos-chromic Pigment

Introduction: The world is filled with beautiful and diverse colors. Therefore, there are lots of opportunities to meet various colors and wide range of fields that can be applied and utilized. Fields using color changes are an indicator which is used in the acid-base reaction, photo-chromic pigment which is changing colors by sunlight or ultraviolet rays and thermo-chromic pigment which is changing colors by the temperature [1-2]. In order to estimate the color change process according to temperature changes, color changes were analyzed using RGB values of thermo-chromic pigments in this study. This analysis enables to quantify RGB values of continuously changing temperatures as objective and quantitative R, G, and B values. Methods: Thermo-chromic pigment which is used to measure color changes is a microcapsule form and has a unique color at a temperature below the reference temperature and is transparent at a temperature above the reference temperature. Therefore, various color changes can be obtained by combining thermo-chromic pigments and the temperature can be estimated by the color changes. TCS3414 (TAOS, USA) was used to obtain varying RGB values of thermo-chromic pigments. In this sensor, a white light source is partially transmitted through a sample, and then the transmitted light enters the photodiode via a color filter [2]. This is converted into a digital value and the light intensity is expressed as a numerical value. In order to examine the color changes according to temperature changes in this experiment, blue thermo-chromic pigment and yellow thermo-chromic pigment which have different reference points of temperature were mixed and used with white plain paint. At this time, the reference temperature of blue thermo-chromic pigment is about 30°C which is the body temperature, and the reference temperature of yellow thermo-chromic pigment is about 40°C which is the high temperature. When two of thermo-chromic pigments are mixed, it turns into the green color which is a mixture of two colors. Color changes according to temperature changes were measured after applying the heat to mixed pigments and making the temperature above 40°C which is the maximum reference temperature of thermo-chromic pigment and making thermo-chromic pigment become colorless. In order to block the ambient light, the experiments were carried out in the dark room. Temperature changes were measured after fixing the infrared thermometer in the experimental setup. Results & Conclusion: Figure 1 is a graph showing the change of RGB values according to temperature changes. X axis shows the temperature and Y axis represents R, G, and B values from 0 to 255. Color change process was measured as the temperature changed from low to high temperature every 20 seconds. Initially, the green color appears which is a color of mixed thermo-chromic pigment. But, at around 30°C which is the reference temperature of blue thermo-chromic pigment, blue thermo-chromic pigment reacts and changed to transparent and only yellow pigment remains. When the temperature rises above 40°C by raising the temperature, yellow thermo-chromic pigment reacts and becomes transparent, and only white color remains which is the color of ordinary paint. Therefore, it is measured close to the RGB value showing white color and the RGB value is raised. Through this, R, G, and B values about temperature changes can be quantified objectively and quantitatively.
Jin-Young BAEK, Ji-Sun KIM, Han-Byeol OH, Jae-Hoon JUN