关键词: 腰果酚, 酸性固色剂, 锦纶织物, 色牢度, 酚醛树脂

Abstract: Nylon is a type of synthetic fiber widely used in the fields of clothing industry and daily necessities due to its lightweight nature, high strength, wear resistance and good elasticity. Common dyes used for nylon fabrics include acid dyes and disperse dyes. Among these, acid dyes offer advantages over disperse dyes such as a complete color spectrum, vibrant hues and a simple dyeing process. Therefore, acid dyes are predominantly employed for dyeing nylon fabrics. Under acidic conditions, the protonated amino groups (—NH₃⁺) in nylon fibers form ionic bonds with the sulfonic acid groups (—SO₃⁻) in acid dyes, resulting in the formation of a stable dye-fiber complex. In addition to binding with the fiber through ionic bonds, acid dyes also interact with nylon fibers via hydrogen bonds, van der Waals forces and electrostatic attractions, although these interactions are relatively weak. Furthermore, the molecular structure of acid dyes contains strongly hydrophilic sulfonic acid groups and carboxyl groups, which contribute to poor wet fastness of the dyed fabric after treatment. To improve the wet fastness of fabrics dyed with acid dyes, color fixing agents are commonly used during the dyeing process. However, the acid color fixing agents currently prevalent in the market are predominantly bisphenol-based color fixing agents. The use of such color fixing agents can pose certain hazards to human health and the environment during application, leading many countries and brands to prohibit their use. Cardanol, extracted from cashew nut shell liquid, features an unsaturated long alkyl chain with 1 to 3 C=C double bonds and a phenolic hydroxyl group in its structure, making it amenable to chemical modification. Therefore, in this study, cardanol was utilized to replace traditional substances such as bisphenol A and bisphenol S for the synthesis of acid dye color fixing agents. However, cardanol has poor water solubility. Hence, it was first sulfonated using chlorosulfonic acid to introduce sulfonic acid groups, thereby enhancing its water solubility. The effects of reaction solvent, the molar feed ratio of chlorosulfonic acid to cardanol, sulfonation temperature and sulfonation time on the sulfonation rate were investigated during this process. Subsequently, the sulfonated product was condensed with formaldehyde. The influence of the feed ratio between cardanol sulfonic acid and formaldehyde, condensation temperature and condensation time on the viscosity of the product and its color fixing effect were examined. The results showed that when dichloromethane was selected as the reaction solvent, with a molar feed ratio of chlorosulfonic acid to cardanol of 1.2:1, a sulfonation temperature of 20 ℃ and a sulfonation time of 4 h, the highest sulfonation rate of cardanol reaching 98.7% was achieved. When the mass feed ratio between cardanol sulfonic acid and formaldehyde was 1:1.2, with a condensation temperature of 90 ℃ and a condensation time of 5 h, the condensation product demonstrated the best color fixing performance. The color fastness of medium to dark-colored nylon fabrics fixed with this product was significantly improved, showing comparable color fixing effects to commercially available acid color fixing agents with minimal color difference. The findings of this study can provide reference for the synthesis of biomass-based acid dye color fixing agents.

Key words: cardanol, acid color fixing agent, nylon fabric, color fastness, phenolic resin