Traditional disperse dye printing has been extended for many years: screen printing → steaming (color development) → washing (removing paste and floating color) → drying and setting. Among them, the sewage discharge from the washing process is the main cause of printing sewage. Since the printed products must be washed in multiple tanks after steam curing, the products with dark colors need to be restored and washed, the light and medium colors need to be soaped, and finally washed with water to ensure the color fastness of the product. Therefore, a large amount of sewage is generated during the entire production process; and the sewage has a large amount of organic pollutants, a deep color, and a large alkalinity, which is a kind of industrial wastewater that is difficult to treat. Therefore, the disperse dye-free water-washing printing process is proposed, which is a new type of printing process that combines the disperse dye direct printing process and the pigment printing process.
Disperse dyes are used to replace pigment particles in pigment printing, and polymer binders are used to carry disperse dyes to achieve fabric dyeing. At the same time, the film-forming properties of polymer binders are used to wrap and adhere the disperse dyes that cannot be dyed. On the surface of the fabric. This not only effectively solves the problems of low dye utilization in the traditional disperse dye direct printing process, which requires a lot of washing, the produced wastewater has high COD content, high color depth and alkaline, difficult treatment, low fabric color fastness, and insufficient bright color; At the same time, it also avoids the disadvantages of poor color fastness to rubbing and hard hand feeling in the paint printing process. The disperse dye washing-free printing process not only achieves the purpose of washing-free, shortens the process flow, saves costs, reduces or even avoids the generation of sewage, is environmentally friendly, and also meets the requirements of high color yield and excellent color fastness to rubbing. It is a very promising new ecological dyeing and finishing process. At present, the research in the field of disperse dye-free washing printing mainly focuses on the development and application of non-washable colorants, the modification of adhesives, and the modification of fabric pretreatment.
1. No-washing color paste
Zhu Yawei of Soochow University and others proposed a printing method of disperse dye micro-polymerization, which used the "binder/crosslinking/deepening three-in-one" vinyl monomer to polymerize in situ on the surface of the printed fabric to form a layer of functional Film, thereby improving the utilization rate of disperse dyes, and without washing after printing, can achieve excellent printing color fastness, shortening the printing process.
In addition, Ding Zhiping of Soochow University proposed to use monomers such as acrylate and acrylonitrile to prepare a non-washing emulsion, and compound disperse dyes and thickeners to obtain an environmentally friendly non-washing printing paste. The printed polyester fabric has a bright color and yields. Higher, the pattern is clear.
2. Modification process of adhesive
Liu Jingqin from South China Normal University and others used butyl acrylate (BA) as the soft monomer, methyl methacrylate (MMA) as the hard monomer, and methacrylic acid (MMA) as the functional monomer to prepare the resulting polyacrylate emulsion Adhesion, film hardness, gloss and mechanical properties are all good. The prepared emulsion has good film-forming properties, and has suitable viscosity, gloss, hardness, adhesion and water resistance. Applied to the blending of disperse dye printing paste, the printed fabric has high fastness and can achieve the effect of no washing.
Qin Yingyue et al. used MMA as the hard monomer, BA as the soft monomer, acrylic acid (AA) and vinyl triethoxysilane (A-151) as functional monomers to prepare the core, shell-type silicone acrylic emulsion, through adjustment The ratio of soft and hard monomers gives a core-shell emulsion with excellent film-forming properties. And it is used in the preparation of disperse dye printing paste without washing.
Zhang Naishu used only 2% thickener WF to formulate the color paste without any binder, and achieved the printing effect of high color, high fastness, good hand feeling and no washing.
In addition, many scholars also improve the properties of polyacrylate by adding modifiers to modify it. At present, the most commonly used modifiers for modifying polyacrylates are water-based polyurethane, silicone and organic fluorine.
3. Modification process of fabric pretreatment
In addition, the method of fabric pretreatment and modification can better combine the dye or dye with the fabric in the subsequent process, which can also effectively reduce the effect of the aqueous medium, so as to achieve the purpose of less water or even no-wash printing.
For example, Wan Jie et al. used a pretreatment agent TG-1, which is formulated with a certain proportion of weak cationic organics, small molecule crosslinking agents and anti-precipitation agents, to pre-treat polyester fabrics. The results show that the pretreatment agent The polyester fabric treated by TG-1 effectively controls the permeation of the color paste, increases the K/S value of the fabric, and can meet the requirements of color fastness to rubbing without washing after fixing, which is helpful for printing on polyester fabrics. Development and application of water washing process.