The Dyeing Of Soybean Fiber/Tencel Blends

The soybean fiber/Tencel blend is one of the important blends containing soybean fiber. In practical dyeing, there are disadvantages such as poor color fastness and great color difference between soybean fiber and Tencel. Therefore it is necessary to study the dyeing properties of the soybean fiber/Tencel blend for practical dyeing purposes. In this work, the dyeing effects of various dyes for the soybean fiber/Tencel blend were preliminarily tested, and then the influence of acetic acid addition and cationic modification on the solid dyeing effects of soybean fiber and Tencel components dyed with direct and reactive dyes was discussed in detail.The tests about the dyeing effects of various dyes for the imitated soybean fiber/ Tencel blend showed that dimonochloro-triazaine reactive dyes mainly reacted with Tencel with low uptake by soybean fiber, while vinylsulphone/monochlorotriazaine and vinylsulphone reactive dyes as well as direct dyes were more absorbed on Tencel than on soybean fiber. In addition, acid and metal-complex dyes were almost completely absorbed by soybean fiber with less staining on Tencel. The tests indicated that the soybean fiber/Tencel blend could be dyed in the two-baths-two-steps method including the dyeing of dimonochloro-triazaine reactive dyes followed by acidic dyeing, and dyed in the one-bath-one-step method using direct dyes and reactive dyes containing vinylsulphone reactive groups in the case of the dyeing conditions being adjusted.In terms of the dyeing of the soybean fiber/Tencel blend with direct dyes, the addition of acetic acid into the dye-bath could improve the solid dyeing effects of soybean fiber and Tencel. In order to obtain good solid dyeing effects, it was recommended that the dyeing was performed under low salts and weak acid medium. This dyeing method had the merits such as short dyeing procedure and time but was subjected to the demerits such as low fastness to wet rubbing and poor color fastness (cotton staining) to washing. It was interestingly found that Glauber's salt exhibited the blocking effect on the uptake of direct dyes by soybean fiber and the accelerating effect on that by Tencel.In terms of the dyeing of the soybean fiber/Tencel blend with reactive dyes containing vinylsulphone reactive groups, the pretreatment of cationic modification could obviously improve the solid dyeing effects of soybean fiber and Tencel. The dosage of soda ash used during cationic modification had great influence on the solid dyeing effect. In order to obtain good solid dyeing effects, it was recommended that the low dosage of soda ash used during cationic modification should be controlled. This dyeing method had the merits such as short dyeing procedure, high fixation and high color fastness but showed low color fastness (color change) to washing for some reactive dyes.