Cochineal Dyeing Of Cotton Fabrics In Ethanol-water System

Cochineal also known as cochineal acid and magenta acid,is a natural anthraquinones pigment extracted from the female cochineal on cactus.It has stable physical and chemical properties,and is safe and non-toxic.It has been widely used in different fields such as food,cosmetics,pharmaceuticals and textiles and so on.If cotton fabric is dyed with cochineal directly,the dyeuptake is low and color fastness of the dyed fabric is poor.To solve these problems,this paper focused on the study of the dyeing of cotton fabrics with cochineal in ethanol water systems,improving the dyeing performance of cotton fabrics through oxidation treatment and chitosan grafting.A mixed solution of ethanol and water was used as a solvent for the cochineal.The modified cotton fabric was dyed in a closed system,the dyeing rate and color fastness of cochineal to modified cotton fabric was evaluated,and the modification treatment and dyeing process were optimized.The kinetics and thermodynamic properties of the modificated cotton fabrics dyeing with cochineal in the ethanol-water system were analyzed.The color fastness and other properties of the dyed cotton fabrics were also measured.Cotton fabric was treated with hydrogen peroxide and sodium periodate,and fabric whiteness and strength,aldehyde content and K/S value were analyzed and compared.Accordingly oxidant type and concentration were selected.Then chitosan modification process of cotton fabric was selected through the discussion of the effects of chitosan content?citric acid concentration and baking temperature on dyeing rate and K/S value As a result,hydrogen peroxide concentration was 2g/L,chitosan concentration was 15g/L,citric acid concentration was 30g/L,and baking temperature was 130?.The effects of the proportion of ethanol and water,bath ratio,and mordant type on the dyeing of cotton fabrics with cochineal were studied further.The results showed that the proportion of ethanol and water was 9:1,the bath ratio was 1:30 and the pH value of the dyeing solution was 7.The results of dyeing thermodynamics showed that in the ethanol-water system the thermodynamics curve of cochineal dyeing with modified cotton fabric was a Langmuir type.And dyeing kinetics results showed that with the increase of the dyeing temperature,dye diffusion coefficient increased and half dyeing time decreased.The results of the color fastness test showed that the washing resistance and rubbing fastness of chitosan-treated oxidized cotton fabrics were all improved.The tearing strength of the modified cotton fabric decreased,however,the water repellent and anti-ultraviolet properties were improved.