Printing and dyeing auxiliaries are used in the process of fabric printing and dyeing, which can improve the printing and dyeing effects. They include printing auxiliaries and dyeing auxiliaries. Printing auxiliaries include thickeners, adhesives, cross-linking agents, emulsifiers, dispersants and other printing auxiliaries.

Printing and dyeing auxiliaries can be divided into printing auxiliaries and dyeing auxiliaries. Printing and dyeing auxiliaries can be divided into printing auxiliaries and dyeing auxiliaries. Printing auxiliaries include adhesives, thickeners, crosslinking agents, emulsifiers, softeners, diffusers and defoamers, while dyeing auxiliaries include leveling agents, fixing agents, dispersants, fluorescent brighteners and softeners.。

Introduction to printing and dyeing auxiliaries

In spinning, spinning, weaving, printing and dyeing to finished products, the textile industry needs to use different auxiliary chemicals according to the properties of various fibers, so as to improve textile quality, processing effect, production efficiency, simplify technological process, reduce production cost and endow textiles with various excellent application properties. This auxiliary chemical is commonly called textile dyeing and finishing assistant.

Dyeing and finishing auxiliaries are often divided into three categories: pre-treatment agents, dyeing and finishing auxiliaries and finishing agents according to the steps and uses of dyeing and finishing.

The pretreatment process of printing and dyeing includes fiber singeing, desizing, boiling, bleaching, mercerizing, etc. It is necessary to add penetrant, emulsifier, cleaning agent and other surfactants, mainly organic sulfate, sulfonate and polyoxyethylene ether.

Penetrant, wetting agent, penetrant commonly used in textile industry include butyl ricinoleate sulfate, sodium butyl naphthalene sulfonate, etc.

In neutral solution, the permeability of sodium dioctyl succinate sulfonate is particularly strong; In addition to the above varieties, fatty alcohol polyoxyethylene ether or alkyl phenol polyoxyethylene ether is commonly used in acidic solution; In strong alkaline solution, such as mercerization, shorter carbon chain sulfate such as octanol sulfate should be used

Emulsifiers are often oiled in order to improve the lubricity of silk and yarn in the textile process. However, oil should be removed before printing and dyeing to avoid affecting dyeing. Therefore, emulsifiers should be added in advance to these textile finishes, or emulsifiers should be added in the cleaning bath to ensure the removal of oil spots, generally using nonionic surfactants.

Cleaning agents, i.e., detergents and detergents, remove oil stains on textile articles. In the past, soap was the main detergent, but now various synthetic detergents and nonionic surfactants are used, including oleamide derivatives with slightly higher prices.

In addition, there are enzymes used to promote starch hydrolysis during desizing; Activator and corrosion inhibitor added during bleaching speed up bleaching process and increase whiteness without corroding equipment. At present, desizing, boiling and bleaching have been completed in one bath, and new and strong cleaning additives are used.

There are many varieties of textile dyes and different dyeing processes, which require corresponding auxiliary agents. Therefore, there are many kinds of auxiliary agents, mainly including the following:

Water softener: metal ion chelating agent

Heavy metal ions in water often affect the color or solubility of dyes, and we can remedy them with water-softening agents, such as sodium hexametaphosphate, sodium aminotriacetate and sodium ethylenediaminetetraacetate.

Solvents and cosolvents

When using or preparing liquid dyes, some dyes need solvent to help them dissolve, such as ethylene glycol, diethylene glycol, ethylene glycol ethers, formamide, thiodiethanol, etc. can be used as dye solvents; When dyeing with phthalocyanine blue, the auxiliary solvent and copper salt should be used, and the auxiliary solvent sodium benzylaminobenzene sulfonate should be used for vat dyes.

Reducing agent and oxidant

When using vat dyes, it is necessary to dissolve vat dyes with reducing agents, such as sodium hydrosulfite, sodium formaldehyde sulfoxylate and thiourea dioxide. Mild oxidant sodium m-nitrophenylsulfonate can be used for dye protection of vat dyes. This product can also be used in printing paste to protect dyes from the possible reducing components in the paste.

Color fixing agent and color developing assistant

When dyeing with direct dyes, acid dyes and reactive dyes, fixing agents before and after dyeing can improve the color yield and color fastness. The fixing agent mainly uses amine salt and polymer quaternary ammonium salt. Dyes used for printing sometimes use color development aids, such as diethylethanolamine when steaming fast amine.

Dispersant, also known as diffusion agent

Dispersants and protective colloids should be added when dyeing with disperse dyes and vat dyes to ensure uniform dyeing and prevent color spots. Commonly used dispersants include sulfonated oil (Taikoo oil, Turkish oil), alkyl or long chain amidobenzene sulfonate, alkyl polyoxyethylene ether, sodium lignosulfonate, naphthalene sulfonic acid formaldehyde condensate, oleoyl polyamine carboxylate, etc.

Leveling agent, that is, leveling agent

Polyoxyethylene ether surfactants are commonly used as leveling agents for dyes, cationic surfactants for cationic dyes and anionic surfactants for acidic dyes.

flatting agent

Compared with natural fiber, synthetic fiber has too smooth surface and too high reflectivity, so titanium dioxide and zinc sulfide should be added to improve it.

defoamer

Used for removing foam caused by surfactant in printing and dyeing process. Tributyl phosphate, octanol, etc. were generally used in the past, but now they all use organic shikui compound.

Printing size and thickener

In the past, natural pulp was used, but now it has become a trend to use semi-synthetic or synthetic pulp, such as starch ether, sodium alginate, etherified locust bean powder, cellulose ester, polyvinyl alcohol and polyacrylate, etc. The synthetic sizing agent has high consistency and small dosage, which can make the printing color deep. The chemical structure of thickener is polyethylene glycol diether or diester or polyacrylate copolymerized by acrylate.

Adhesive for printing and dyeing

Various synthetic latexes such as copolymers of butadiene, styrene, acrylonitrile, vinyl acetate, vinyl chloride and acrylate can be used. Strong adhesion is required, that is, good abrasion resistance and rubbing fastness, soft hand feeling, and difficult yellowing under high temperature and illumination. At present, the common adhesives with high quality are polyacrylate copolymers with self-crosslinking groups and polyurethanes.

After the printing and dyeing process is completed, the fabric is usually washed to remove floating color to improve the dyeing fastness. The synthetic cleaning agent used varies with dyes and printing and dyeing methods. For example, after dyeing polyester-cotton fabric with disperse dyes, it is necessary to remove floating color on polyester and prevent cotton fiber from being dirty, and special nonionic cleaning agent must be used.

finishing agent

Chemicals used for improving the appearance, hand feeling and shrinkage of fabrics, stabilizing the appearance, prolonging the service life, and preventing water, fire, dirt and mildew. Resin finishing agent, as the most important finishing agent, is a kind of polymer compound, which can bond with the hydroxyl group of cellulose, so as to achieve a lasting anti-wrinkle and non-iron effect. When mixed with appropriate softening agent, it can improve the hand feeling of fabric.

Commonly used resins include urea-formaldehyde resin, melamine-formaldehyde resin, dimethylol ethylene urea resin, dimethylol dihydroxy ethylene urea resin and dihydroxyethyl sulfone. Among them, dimethylol dihydroxy ethylene urea resin is widely used, which is formed by condensation of glyoxal, urea and formaldehyde.

Penetrant, catalyst (commonly used metal salt, ammonium salt or organic amine salt) and hand feeling regulator, the latter is usually softening agent, should be added into the resin finishing working fluid. The newly developed resin finishing agent polyurethane has slightly higher price, but high setting performance, no residual formaldehyde and no skin allergy.

Softening agent

Cationic finishing agents are mainly cationic long-chain fatty groups. Because cationic finishing agents have affinity for fibers, the dosage can be reduced, and the adhesive force is strong, which can show long-lasting softness, and its softness and lubrication performance mainly come from its long-chain fatty groups. Emulsified mineral oil and wax can increase lubricity in this softener.

Some softeners react with hydroxyl or amine groups in the fiber, which enhances the washing resistance of the fiber and has lasting softness. Recently, a silicone oil dispersion softener has appeared, and its ionic properties vary according to the emulsifier used. The treated fabric has a particularly soft and smooth feeling, which is suitable for high-speed sewing. If cross-linking silicon compound is added, the elasticity of fabric can also be enhanced.

waterproofing agent

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

fire retardant

Temporarily, there are amine salts, sodium tungstate, borax, water glass, etc. Diammonium hydrogen phosphate and urea can be used to treat cotton cloth, which has certain durability. Organic substances are mainly compounds containing bromine, phosphorus, nitrogen and chlorine, which can inhibit combustion. If it can be combined with fibers, it can play a lasting role.

The main varieties of flame retardant for cotton have the following structure: there is no effective durable flame retardant for synthetic fibers. Polyester used tris (2,3- dibromopropyl) phosphate, which is effective in flame retardant, but it was banned in 1977 because of its toxicity. At present, tetrahydroxy phosphorus chloride compounds, sulfides or hydroxyl compounds and resins are used, which have better durability. There are also flame retardants added before spinning synthetic fibers, but they have certain influence on fiber properties and strength. At present, new polybromides are being developed as flame retardants for synthetic fibers.

Electrostatic inhibitor, i.e. antistatic agent

Mainly used for synthetic fibers, which can prevent static electricity and make fabrics easy to decontaminate. There are mainly polyacrylic acid, polyethylene glycol ester and macromolecular amphoteric compounds.

Mildew inhibitor

In the presence of microorganisms, cotton fabrics are prone to mildew, especially in the presence of slurry and proper temperature and humidity. Various copper salts and derivatives of organic phenols, such as copper pentachlorophenol, copper naphthenate, copper 8- hydroxyquinoline, dihydroxydichlorodiphenylmethane, salicylanilide and so on, are used as mildew inhibitors.

Anti-grease agent

It is mainly a variety of derivatives of organic fluorine, which have very low surface energy, do not touch oil, and combine with fibers in a resin-like structure.

Coating agent

It is a new finishing agent, including polyacrylate, polyurethane, etc., which endows fabrics with various additional properties, such as waterproof, flame retardant, light-proof, elasticity, and makes cheap fabrics have properties like leather.

Functional finishing assistant

There are also many finishing AIDS that give special functions to fibers, such as far infrared thermal care finishing agents, anti-ultraviolet emulsion finishing agents, antibacterial sanitary finishing agents, ceramic powder far infrared finishing agents, aromatic finishing agents and so on