关键词: 荔枝核, 天然染料, 阳离子改性, 染色, 棉织物

Abstract: With the improvement of people's quality of life and the enhancement of environmental awareness, more and more attention has been paid to natural dyes. Natural dyes originate from nature, belong to nature, have good biodegradability, reasonable use of natural dyes, and can realize the real green and sustainable development of natural dyes. Studies have shown that natural dyes can not only dye a unique soft color, but also give added value to the fabric, such as endowing the dyed fabric with a unique aroma, anti-mosquito, anti-bacterial, anti-UV functions and such. However, the development of natural dyes is affected by their limitations such as the poor reproducibility of natural dyes dyed fabrics, low extraction rate, poor color fastness and incomplete chromatography, which seriously restricts the industrialization of natural dyes. Therefore, faced with the increasing demand for dyes, the development and research of natural dyes is urgent. In this paper, we extracted natural dyes from waste lychee seeds, discussed the cationic modifiers and their modification mechanism on cotton fabrics, optimized the modification process of cotton fabrics and natural dyes' dyeing process to test the color fastness and explored the effect of mordant and antioxidant on enhancing the color fastness to sun.
In order to effectively utilize the waste resources of litchi seeds, the effective components of litchi seeds were extracted and applied to dye cotton knitted fabrics. Firstly, the cationic modifier D of quaternary ammonium salt was used to modify the pure cotton knitted fabric, and the modification process was optimized. The Zeta potential and infrared spectrum of the pure cotton knitted fabric were measured before and after the modification. Then the dyeing process of the natural dyes of lychee seeds for cotton knitted fabrics was optimized. Finally, the color fastness of the natural dyes of lychee seeds was improved by post-dyeing and antioxidant treatment. In this experiment, lychee seeds were selected as the extract to achieve the reuse of waste resources. The extraction method of enzyme and soda ash was adopted to improve the extraction rate of dye. In this paper, small bath ratio is used to reduce water consumption and energy consumption, and reduce the use of chemical additives. The results showed that the pure cotton knitted fabrics dyed with lychee seeds had a high dyeing K/S value, and the color fastness to soap washing and friction was above grade 3, and the color fastness to sunlight was up to grade 4. The optimal modification process requires a modifier of D30 g/L and sodium hydroxide of 10 g/L at 80 ℃ for 30 min. The dyeing process requires a dyeing pH value of 7 and a dosage of sodium sulfate of 0 g/L at 90 ℃ for 60 min.
Cotton is one of the most important raw materials in the field of textile and has a long history of application. As early as thousands of years ago, human beings began to cultivate cotton. Because of its excellent moisture absorption, softness and air permeability, cotton has never been eliminated from the field of textile. Natural dyes are applied to cotton fabric dyeing. Nowadays, under the guidance of the concept of advocating nature, green, simplicity and comfort, cotton has been increasingly valued and loved by people. The ecological and environmental protection of cotton fabrics combined with natural dyes comes from the natural green health, which can bring the all-natural cotton fabrics, and is in line with modern people's pursuit of ecological green. Therefore, the research and development of natural vegetable dyes and cotton textile dyeing have broad market prospects.

Key words: litchi seed, natural dye, cationic modification, dyeing, cotton knitted fabric