Temperature Optimization in the Ultrasonic Dyeing Process of Cotton Fabric Using Natural Dye Powder from Sappan Wood (Caesalpinia sappan L.)

Abstract

Sappan wood (Caesalpinia sappan L.) is one of the natural dye sources with potential for use in textile dyeing because it contains brazilin, which can be oxidized into brazilein and produce colors ranging from red to brownish-red. The use of the ultrasonic dyeing method can assist the dye absorption process into textile fibers, but the effect of temperature on the dyeing results of sappan wood still needs to be examined. This study aims to determine the effect of temperature variations of 40°C, 50°C, 60°C, and 70°C in the ultrasonic dyeing process with a frequency of 22 kHz for 20 minutes on the dyeing results of cotton fabric. The parameters observed include color strength (K/S), CIELAB values, color fastness, and functional group characteristics using FTIR. The results showed that the K/S value increased from 2.105 at 40°C to 2.627 at 60°C, then decreased to 2.146 at 70°C. This decrease is thought to be related to changes or degradation of the dye compound due to higher temperatures. Color fastness to washing was at grade 1–1–2, while color fastness to wet rubbing was at grade 4–5 at 40–50°C and decreased to grade 4 at 60–70°C. FTIR analysis results showed a relatively similar absorption band pattern across all treatments and did not indicate the formation of new bands. Based on the overall results, a temperature of 60°C produced the highest K/S value, so it can be used as the optimum condition in the ultrasonic dyeing process of cotton fabric using sappan wood dye powder. The CIELAB analysis was also conducted to examine the colorcharacteristics of the dyed fabrics, including lightness (L*), redness (a*), and yellowness (b*). The hue angle values ranged from 19°C to 21.9°C indicating relatively similar color tones across the temperature variations. The apparent exhaustion (Eapp) values were also recorded to provide additional information about the dyeing process. The results of this study provide information on the relationship between dyeing temperature and the color characteristics of cotton fabric dyed with sappan wood using ultrasonic technology. These findings may serve as a reference for further research on natural dyeing methods and efforts to improve the color fastness of naturally dyed textiles.