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How to choose textile auxiliaries

In the textile industry, in the various processing procedures from spinning, spinning, weaving, printing and dyeing to finished products, different auxiliary chemicals are required according to the performance of various fibers to improve the quality of textiles, improve processing effects, increase production efficiency, and simplify Process, reduce production costs and give textiles various excellent application properties. This auxiliary chemical is commonly known as textile dyeing and finishing auxiliaries.

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

1.Pretreatment agent for printing and dyeing

The pre-treatment process of printing and dyeing includes fiber singeing, desizing, scouring, bleaching, mercerizing and other processing processes. It is necessary to add penetrants, emulsifiers, cleaning agents and other surfactants, such as organic sulfate, sulfonate and polyoxyethylene. Mainly ether.

 

Penetrants, wetting agents, penetrants commonly used in the textile industry include butyl ricinoleate sulfate, butyl naphthalene sulfonic acid sodium salt, etc. In neutral solution, dioctyl sodium succinate sulfonate has a particularly strong penetrating ability; in acid solution, in addition to the above varieties, fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether is commonly used; and in strong alkaline In the solution, for example, the mercerizing process requires the use of shorter carbon chain sulfates such as octanol sulfate.

 

Emulsifiers are often oiled in order to improve the lubricating properties of silk and yarn in the spinning process. However, the oil must be removed before printing and dyeing, so as not to affect the dyeing. Therefore, it is necessary to add emulsifiers in these textile oils, or add emulsifiers in the cleaning bath to ensure the removal of oil spots, generally nonionic surfactants are used.

 

Cleaning agents, namely detergents and detergents, remove oily stains on textiles. In the past, soap was the mainstay, but now a variety of synthetic detergents and non-ionic surfactants are used, including slightly more expensive oleic acid amide derivatives. . In addition, there are enzymes used to promote starch hydrolysis during desizing; activators and anticorrosive agents added during bleaching speed up the bleaching process and increase the whiteness without corroding the equipment. At present, it has been developed to complete desizing, scouring and bleaching in one bath, and a new compound powerful cleaning aid is used.

 

2.Printing and dyeing auxiliaries

There are many types of textile dyes, and the dyeing process is different, and the corresponding supporting auxiliaries are needed. Therefore, there are many kinds of such auxiliaries, mainly as follows

 

2.1.Water softener: metal ion chelating agent

Heavy metal ions in water often affect the color or solubility of dyes. We can use water softeners to remedy them. Commonly used water softeners include sodium hexametaphosphate, sodium nitrilotriacetate and sodium ethylenediaminetetraacetate.

 

2.2.Solvents and co-solvents

When certain dyes are used or formulated in liquid dyes, a filling solvent is needed to help dissolve them, such as ethylene glycol, diethylene glycol, glycol ethers, formamide, thiodiethanol, etc. As a dye solvent; when dyeing with phthalocyanine blue, use the auxiliary solvent and copper salt, and use the auxiliary solvent sodium benzylaminobenzene sulfonate for the vat dye.

 

2.3.Reducing agent and oxidizing agent

 When using vat dyes, you must first use a reducing agent to dissolve vat dyes. Commonly used are sodium hydrosulfite (sodium dithionite), hanging white block (sodium formaldehyde sulfoxylate), and thiourea dioxide. When the vat dye is anti-dyeing, a mild oxidizing agent, sodium nitrobenzene sulfonate, can be used. This product can also be used in printing paste to protect the dye from the possible reducing components in the paste.

 

2.4.Fixing agent and color developing

aid When dyeing with direct dyes, acid dyes and reactive dyes, use fixing agent before and after dyeing to improve the amount of color and fastness. Fixing agent mainly uses amine salt and polymer quaternary ammonium salt. Dyes for printing sometimes use color-developing additives, such as diethylethanolamine when steaming and color-developing fastamine.

 

2.5.Dispersant, also known as diffuser

 When printing and dyeing with disperse dyes and vat dyes, dispersants and protective colloids should be added to ensure uniform dyeing and prevent stains. Commonly used dispersants are sulfonated oil (Taikoo oil, Turkish oil), sodium alkyl or long-chain amidobenzene sulfonate, alkyl polyoxyethylene ether, sodium lignin sulfonate, naphthalenesulfonic acid formaldehyde condensate, oleoyl Polyamino carboxylate and the like.

 

2.6.Leveling agent, namely leveling agent

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

 

2.7.Defoamer

Used to remove foam caused by surfactants in the printing and dyeing process. In the past, tributyl phosphate, octanol, etc. were generally used, but now they have all used organic stone compounds.

 

2.8.Defoamer

Used to remove foam caused by surfactants in the printing and dyeing process. In the past, tributyl phosphate, octanol, etc. were generally used, but now they have all used organic stone compounds.

 

2.9.Printing paste and thickener

In the past, natural slurries were used, but now they have tended to use semi-synthetic or synthetic slurries, such as starch ether, sodium alginate, etherified locust bean powder, cellulose esters, polyvinyl alcohol, and polyacrylates. The synthetic slurry has high consistency and low dosage, which can make the color of printing deep. The chemical structure of the thickener is macromolecular polyethylene glycol bisether or diester, or polyacrylate copolymerized with acrylate.

 

2.10.Adhesives for printing and dyeing

Various synthetic latexes such as copolymers of butadiene, styrene, acrylonitrile, vinyl acetate, vinyl chloride and acrylic esters can be used. It is required to have strong adhesion, that is, good abrasion fastness, soft hand feeling, and not easy to yellow under high temperature and light. At present, high-quality general-purpose adhesives are polyacrylate copolymers with self-crosslinking groups and polyurethanes.

 

3.Cleaning agent after printing and dyeing

After the printing and dyeing process is completed, the fabric is generally washed to remove the floating color to improve the color fastness. The synthetic cleaning agent used varies with the dye and the printing and dyeing processing method. For example, after the disperse dye dyes the polyester-cotton fabric, it is necessary to remove the floating color on the polyester. , And to prevent the cotton fiber from being polluted, special non-ionic cleaning agents must be used.

 

3.1.Finishing agent Chemicals

used to improve the appearance, feel, shrinkage rate of fabrics, stabilize appearance, prolong life, waterproof, fireproof, antifouling, mildew and other chemicals. Resin finishing agent, the most important finishing agent, is a polymer compound that can bond with the hydroxyl group of cellulose to achieve a longer-lasting anti-wrinkle and non-ironing effect. When mixed with an appropriate softener, it can improve the feel of the fabric. Commonly used resins are urea-formaldehyde resin, melamine-formaldehyde resin, dimethylol ethylene urea resin, dimethylol dihydroxy ethylene urea resin and bishydroxy ethyl sulfone. Among them, dimethylol dihydroxy ethylene urea resin is the most widely used, which is formed by the condensation of glyoxal, urea and formaldehyde. Penetrants, catalysts (commonly used metal salts, ammonium salts or organic amine salts) and feel modifiers should be added to the resin finishing fluid. The latter is usually a softener. The newly developed resin finishing agent, polyurethane, has a slightly higher price, but has high styling performance, no residual formaldehyde, and does not cause skin allergies.

 3.2.Softener

It is mainly cationic long-chain fat-based finishing agent. Because cationic finishing agent has affinity for fibers, the dosage can be reduced, and its adhesion is strong, which can show longer-lasting softness. Its soft and lubricating performance mainly comes from its long-chain fat-based . Adding emulsified mineral oil and wax to this softener can increase lubricity. Some softeners react with the hydroxyl or amine groups in the fiber to enhance the washing resistance of the fiber and have long-lasting softness. Recently, silicone oil dispersion softeners have appeared, and their ionic properties vary depending on the emulsifier used. After treatment, the fabric has a particularly soft and smooth feel and is suitable for high-speed sewing. If adding a crosslinkable silicon compound, it can also enhance the elasticity of the fabric.

3.3.Waterproofing agent

 Although the rubber paste coating is waterproof, it has poor air permeability when worn. Rainproof slurry is a mixture of aluminum salt and paraffin, but it is not durable. Long-chain aliphatic hydrocarbon compounds that react with fabrics are used for durable waterproofing agents with breathability. The acrylate coating can also be waterproof after cross-linking. The newly developed waterproofing agent is hydrogen-containing silicone oil and its derivatives.

 

3.4.Flame retardant

Temporary ones include amine salt, sodium tungstate, borax, water glass, etc. The cotton cloth treated with diammonium hydrogen phosphate and urea can have a certain degree of durability. Organic matter is mainly compounds containing bromine, phosphorus, nitrogen, and chlorine, which can inhibit combustion. If it can be combined with fiber, it can have a lasting effect. The main varieties of flame retardants for cotton have the following structure: there is still a lack of effective durable flame retardants for synthetic fibers. Tris (2,3-bis-bromopropyl) phosphate has been used for polyester, which is effective in flame retardancy. Because of its toxicity, it was banned in 1977. The tetrahydroxy phosphonium chloride compound, sulfide or hydroxy compound and resin are used now, which have better durability. There are also flame retardants added before the spinning of synthetic fibers, but they have a certain impact on fiber performance and strength. Currently, new polybrominated compounds are being developed as flame retardants for synthetic fibers.

 

3.5.Antistatic agent, namely antistatic agent

It is mainly used for synthetic fibers, which can prevent static electricity and make the fabric easy to decontaminate. Mainly include polyacrylic acid, polyethylene glycol ester and polymer amphoteric compounds.

 

3.6.Anti-mold auxiliaries 

Cotton fabrics are prone to mildew in the presence of microorganisms, especially in the presence of slurry and appropriate temperature and humidity conditions, they are more prone to mildew. The antifungal agents used include various copper salts and organic phenol derivatives, such as Copper pentachlorophenate, copper naphthenate, copper 8-hydroxyquinoline, dihydroxydichlorodiphenylmethane, salicylanilide, etc.

 

3.7.Anti-greasy agent

 Mainly various derivatives of organic fluorine, their surface energy is particularly low, oil-free, and resin-like structure combined with fibers.

 

3.8 Coating agent

It is a new type of finishing agent, including polyacrylate, polyurethane, etc., which give the fabric various additional properties, such as waterproof, flame retardant, light-proof, elasticity, and make inexpensive fabrics have properties like leather.

 

3.9 Functional finishing auxiliaries

There are also many finishing auxiliaries that give fibers special functions, such as far-infrared heat preservation and health care finishing agents, anti-ultraviolet emulsion treatment agents, antibacterial sanitary finishing agents, ceramic powder far-infrared finishing agents, fragrance finishing agents, etc.

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