Color agent or fixing agent is one of the important additives in the printing and dyeing industry. It can improve the color fastness of dyes on fabrics. A fixing agent can form insoluble colored substances with dyes on the fabric to improve the washing and perspiration fastness of the color, and sometimes the light fastness.
This passage is going to talk about the following questions of fixing agent:
(1) What is fixing agent?
(2) What is the principle or mechanism of fixing agent?
(3) History of the fixing agent:
After dyeing, the dye on the surface of the fabric is not fixed, if it becomes the final product, it will cause color migration during wet or washing. The fixing agent is applied to the dyed fabric to fix the unfixed dye on the fabric. It improves wet color fastness and fabric quality.
The mechanism of the fixing agent is to make the dye insoluble (forming a complex) through the ionic bond between the dye and the fixing agent, and the fixing agent forms a film on the fabric (film-forming effect).
Fixing agent is one of the important additives in the printing and dyeing industry. With the development of science and technology, dyeing and finishing technology has also been significantly improved. Due to the expansion of international textile trade and the improvement of people's living standards and environmental protection awareness, textiles are required to be comfortable, Clean and safe. Since Germany first launched the "Blue Angel" program in the 1970s, some developed countries in the world (Japan, the United States, etc.) have successively passed and implemented relevant laws and regulations, stipulating various indicators for textiles. Green textiles are required to prohibit the use of carcinogenic, teratogenic, and poorly biodegradable dyes and dyes produced by certain aromatic amine intermediates as specified in the regulations in printing and dyeing. At the same time, it also requires that the additives used do not contain heavy metal ions and do not produce Free formaldehyde, that is, the use of "green additives", the development and application of aldehyde-free fixing agent KS meets this requirement. Fixing agent KS is through the polymerization reaction of organic amine and epichlorohydrin, and then acidified with hydrochloric acid to obtain fixing agent KS, which is used for the fixation of reactive, direct, and sulfur dyes after dyeing cotton. It can "bridging" between the dye and the fiber to form a compound, that is, it reacts with the dye molecules at the same time and cross-links with the cellulose fiber to form a highly diverse the cross-linking system enables the dye to be more firmly combined with the fiber, prevents the dye from falling off the fiber, and improves the color fastness. The active substances in the fixing agent can condense with each other to form a three-dimensional network film on the surface of the fiber, which seals the dye, increases the smoothness of the cloth surface, reduces the friction coefficient and is not easy to wear, and further prevents the occurrence of wet friction. The dye swells, dissolves, and falls off, improving the wet fastness.
In addition to the clothing industry, in the production of pulp and paper, fixatives are also used to fix asphalt or adhesives to paper fibers to transfer problems outside of the production process and have clean production equipment. As a fixing agent used in pulp and paper production, there are minerals such as talc and bentonite, or different cationic polymers such as poly-DADMAC. Polymer-based fixatives are often referred to as release agents because they reduce the viscosity of asphalt and adhesives.