Research On The Dyeing Properties Of Hemp Fabric With Vat Dyes

The dyeing process of China hemp fabrics with vat dyes was studied, which included the influence of pretreatment with alkali pretreatments or liquid ammonia, dyeing temperature, dyeing time, dosage of reducing agents, caustic soda and penetrating agents on the dyeing ability of China hemp. The dyeing process had been optimized and, on this basis, the overflow dyeing had been implemented.Results showed that Vat Scarlet GG, Vat Golden Yellow RK, Vat Brilliant Green FFB, Olive Green B, Vat Olive R and Vat Brown GS were the high temperature resistance dyes. Alkali pretreatments and the liquid ammonia treatments could both increase the dyeing depth of China hemp significantly, but the increasing degree of K/S value of liquid ammonia treatments was less than the alkali pretreatments. The pretreatments could not increase the penetrability of the dyes. The optimum condition of dyeing was listed as the followings: 5%(owf), dosage of thiourea dioxide and caustic soda was lOg/L and 16g/L, the dyeing time was 30 minutes at the temperature of 130℃.The overflow dyeing experiment of hemp55/cotton45 blended fabrics showed that the dry and wet friction resistance fastness, washing resistance fastness, perspiration resistance fastness, light fastness, chlorine bleach resistance fastness of vat dye were respectively 4,3, 4-5,4-5,4-5, and 6-7 levels, significantly better than the ones of reactive dye. The dyeing cost of fabrics with vat dyes was a little more than the one with reactive dyes.