Design,Synthesis And Mannich Dyeing Properties Of H Acid-containing Aromatic Primary Amine Dyes

Silk is one of the first natural fibers used in textile.It has soft and smooth texture,good moisture absorption and air permeability,and is loved by consumers.At present,the commonly used dyes for silk mainly include acid dyes and reactive dyes.Acidic dyes and silk through ionic bond interaction,wet treatment fastness is generally poor;reactive dyes can react with silk to form covalent bond,wet treatment fastness is high,but in the dyeing process need to be fixed in alkaline,high temperature conditions,fiber damage,it is difficult to meet the quality requirements of highquality silk products.In addition,the fixation rate of most reactive dyes is between 50% and 80%,which leads to the concentration of hydrolyzed dyes in dyeing wastewater and is difficult to treat.Aiming at the shortcomings of existing commercial dyes in silk dyeing and the appeal of energy conservation and environmental protection in the production process of relevant printing and dyeing enterprises,it is of positive significance to develop a new type of reactive dyes suitable for silk and establish an energy conservation and emission reduction dyeing process for silk printing and dyeing.Our group has developed a number of monoaromatic amine dyes of different colors and established an energy-saving low-loss Mannich reaction staining method(referred to as Mannich staining)suitable for silk,with a staining process of: 30 ?,weak acid bath,10 h.The silk fabric dyed with Mannich,a monoaromatic amine dye,has a high wet fastness,but the dyeing time is high,and the relative fixation rate is between 70% and 80%.In order to improve the dyeing efficiency,three commercial aromatics(C.I.acid brown 4,C.I.acid green 20,C.I.acid black 210)were selected to accelerate the dyeing speed by increasing the temperature.The results showed that in the weak acid dyeing bath at 90?,the aromatic amine dye could rapidly undergo Mannich staining with silk,the dyeing equilibrium time could be shortened to 130 min,and the soap-washing and rubbing fastness of the dyed fabric reached grade 4 and above.However,the fixation rate and fiber breaking strength loss rate of silk fabrics stained with high temperature Mannich(90?)were inferior to those stained with room temperature Mannich(30?),indicating that increasing the staining temperature is not an ideal solution to improve the efficiency and quality of Mannich staining.In this paper,7 dyes containing H acid aromatic amines with the same chromogenic parent were further screened and synthesized,and the effects of the type,location,and number of amino groups in the dye structure on the dye color and Mannich staining efficiency at room temperature were systematically studied.It has been shown that the dye color is able to cover the chromatographic range from orange-red to blue-purple(505-567 nm)by changing the electron absorption properties of substituents in H-acid-containing arylamine dye structures.By studying the conformational relationship between the structure of aromatic amine dyes and Mannich staining efficiency at room temperature,the results showed that aromatic amine dyes without primary amine groups had no Mannich reaction activity on silk,the dyes could adsorb fibers,but the relative fixation rate was close to zero;the relative fixation rate of monoaromatic amine dyes to silk was related to the aromatic ring structure where the amino group was located and the electron cloud density,and the relative fixation rate of aniline dyes was higher than that of naphthylamine dyes.In the same type of naphthylamine dyes,the electron cloud density on the amino group was higher,and the relative fixation rate was higher.Under the condition of Mannich staining at room temperature,the relative fixation rate of diaromatic amine dye D7 was more than 95%,which was superior to that of monoaromatic amine dye,and the staining equilibrium time of D7 was shortened to 8 h,indicating that the Mannich reaction efficiency of the dye was related to the number of primary amines,and the higher the number of primary amines,the faster the reaction rate,and the higher the fixation rate.After Mannich staining,the primary amine group in the dye forms a C-C-N bond connection with the silk tyrosine residue,which improves the electron donation ability of the amino group and causes the red shift phenomenon of ?max of Mannich stained silk fabrics compared with the results of acid dye staining.The color of the dyed fabrics covers the chromatographic range from red to blue(520-580 nm),with the red shift effect of diaromethylamine dye D7 being the most obvious.