Washing agent for post-treatment of printing and dyeing


After finishing the dyeing and printing process, the fabrics usually need to be cleaned to remove the float color to improve the dyeing fastness. The synthetic detergent used varies with dyes and dyeing methods. For example, after dyeing polyester-cotton fabric with disperse dyes, special non-ionic detergents must be used to remove the float color on polyester fibers and prevent contamination of cotton fibers.


3.1 Finishing Agent


Chemicals used to improve the appearance, handle and shrinkage of fabrics, stabilize their appearance, prolong their life, waterproof, fire-proof, anti-fouling, anti-mildew, etc. Resin finishing agent, as the most important finishing agent, is a kind of macromolecule compound, which can bond with the hydroxyl group of cellulose, so as to achieve a more durable wrinkle and iron-free effect. When mixed with appropriate softener, the handle of the fabric can be improved.


The commonly used resins are urea-formaldehyde resin, melamine-formaldehyde resin, dihydroxymethylene urea resin, Dihydroxymethyl dihydroxy ethylene urea resin and dihydroxyethyl sulfone. Among them, dimethylol dihydroxyethylene urea resin is the most widely used, which is synthesized by condensation of glyoxal, urea and formaldehyde.


Permeating agents, catalysts (commonly used metal salts, ammonium salts or organic amine salts) and hand-feeling regulators are added to the resin finishing working fluid, the latter being usually softeners. Polyurethane, a newly developed resin finishing agent, has a slightly higher price, but it has high formaldehyde setting property and no residual formaldehyde, and does not cause skin allergies.


3.2 Softener


The cationic long-chain aliphatic finishing agent is mainly cationic. Because of its affinity to fibers, the dosage of cationic finishing agent can be reduced, and its adhesion is strong. It can show more durable softness. Its soft and lubricating properties mainly come from its long-chain aliphatic group. Adding emulsified mineral oil and wax to this softener can increase lubricity.


Some softeners react with hydroxyl or amino groups in the fibers to enhance the washability and durable softness of the fibers. Silicone oil disperse softener has recently emerged. Its ionicity varies according to the emulsifier used. After treatment, the fabric has a special soft and smooth feeling and is suitable for high-speed sewing. The elasticity of fabrics can also be enhanced by adding cross-linking silicone compounds.


3.3 Waterproof Agent


Although the rubber slurry coating is waterproof, it has poor air permeability when worn. Rainfall slurry is a mixture of aluminium salt and paraffin, but it is not durable. Long-chain aliphatic hydrocarbons that react with fabrics are used as breathable and durable waterproofing agents.


Acrylate coatings can also be waterproof after crosslinking. The newly developed waterproof agent is hydrogen-containing silicone oil and its derivatives.


3.4 Flame Retardant


Temporary ammonium salt, sodium tungstate, borax, sodium silicate and so on, diammonium hydrogen phosphate and urea together to treat cotton cloth, can have a certain durability. Organic compounds mainly contain bromine, phosphorus, nitrogen and chlorine, which can inhibit combustion. If it can be combined with fibers, it can play a lasting role.


The main types of flame retardants for cotton have the following structures: there is no effective durable flame retardant for synthetic fibers, and polyester was used tri (2,3-dibromopropyl) phosphate, which is flame retardant and effective, but it was banned in 1977 because of its toxicity. Now, tetrahydroxyphosphorus chloride, sulfide or hydroxyl compound and resin are used with good durability.


There are also flame retardants added before the spinning of synthetic fibers, but they have certain effects on the properties and strength of the fibers. At present, new polybromides are being developed as flame retardants for synthetic fibers.


3.5 Electrostatic Preventer, Antistatic Agent


It is mainly used for synthetic fibers, which can not only prevent the generation of static electricity, but also make the fabric easy to decontaminate. There are mainly polyacrylic acid, polyethylene glycol ester and macromolecule amphoteric compounds.


3.6 Anti-mildew Auxiliaries


Cotton fabrics are prone to mildew in the presence of microorganisms, especially in the presence of slurry and appropriate temperature and humidity. The application of anti-mildew agents includes various copper salts and derivatives of organic phenols, such as copper pentachlorophenol, copper naphthenate, 8-hydroxyquinoline, dihydroxydichlorodiphenylmethane and salicylaniline. 。


3.7 Oil Pollution Preventer


It is mainly the derivatives of organic fluorine, whose surface energy is very low and oil-free. It combines with fibers in a resin-like structure.


3.8 Coating Agent


It is a new finishing agent, including polyacrylate, polyurethane and so on. They give the fabric various additional properties, such as waterproof, flame retardant, light-proof, elasticity, and make the cheap fabric have leather-like properties.


3.9 Functional Finishing Auxiliaries


There are many finishing auxiliaries that give fiber special functions, such as far-infrared heat preservation and health care finishing agent, anti ultraviolet emulsion treatment agent, antiseptic sanitary finishing agent, ceramic powder far-infrared finishing agent, aromatic finishing agent and so on.


From Ninghe Science and Technology