Abstract: As one of the most important and popular fabrics in the textile industry, denim is considered to be the most widely used fabric in the fashion industry; it is popular because of its high strength, distinct texture, moisture absorption and breathability, and beauty and comfort. In recent years, with the development of the textile industry and the improvement of textile technology, the competitiveness of denim apparel has been rising. It is predicted that the market value of denim fabrics worldwide will reach RMB 620 billion in 2025, which is a very broad market prospect.
Indigo dyeing has disadvantages such as high initial dyeing rate and poor dye penetration, which leads to very poor wet rubbing fastness of indigo dyed denim fabrics, generally only level 1. This affects the quality of denim fabrics and seriously restricts the development of the industry. Therefore, the low wet rubbing fastness and poor quality of indigo denim have become a common problem in the industry, so it is of great significance to improve the quality of denim and the wet rubbing fastness of indigo denim.
In this paper, we aimed to enhance the permeability of indigo dyes and improve the wet rubbing fastness of denim by strengthening the pretreatment process and regulating the state of indigo leuco. Based on this, we further explored the mechanisms and processes related to the influence of different fixing agent types and their molecular weights on enhancing the wet rubbing fastness. The experimental results show that the wet rubbing fastness of indigo-dyed denim can be enhanced to grade 3 by selecting polyurethane color fixing agent B with relatively large molecular weight and optimizing the pretreatment and dyeing process parameters. The optimized pretreatment process requires refining agent A of 10 g/L and caustic soda of 20 g/L at 95 ℃ for 30 min; the dyeing process requires an insurance powder of 18 g/L, urea sulfur dioxide of 1 g/L, caustic soda of 10 g/L, penetrant WET of 6 g/L; color fixing process requires color fixing agent B of 60 g/L at 160 ℃ for a baking time of 120 s.

Key words: indigo denim, dyeing K/S value, fastness to wet rubbing, polyurethane color fixing agent

摘要： 针对靛蓝牛仔布湿摩擦牢度低、品质较差等行业共性问题，文章通过强化牛仔布前处理工艺、调控靛蓝隐色体状态的方式提高靛蓝染色的透染性，并在此基础上对固色剂的作用机理进行了研究。结果表明：优化前处理和染色工艺参数，并选用分子量相对较大的聚氨酯类固色剂B进行处理，可使靛蓝染色湿摩擦牢度提升至3级，达到国家标准要求。优化后的前处理工艺为：精炼剂A 10 g/L，烧碱20 g/L，95 ℃处理30 min；染色工艺为：保险粉18 g/L，二氧化硫脲1 g/L，烧碱10 g/L，渗透剂WET 6 g/L；固色工艺为：固色剂B 60 g/L，160 ℃焙烘120 s。靛蓝牛仔布湿摩擦牢度的提高，可拓宽牛仔布的应用范围，并促进牛仔服装行业的快速发展。

关键词: 靛蓝牛仔布, 染色K/S值, 耐湿摩擦牢度, 聚氨酯类固色剂