>>> Water Softener — Metal Ion Chelating Agent
Heavy metal ions in the water often affect the color of the dye or its solubility. Water softeners can be used to remedy them. Sodium hexametaphosphate shmp is one of the commonly used water softeners. Sodium hexametaphosphate is easy to dissolve in water and the solubility in water is relatively large with relatively warm dissolution rate. It also has the ability to form soluble complexes for some metal ions. So it can be sued to soften water and can also form complexes with lead, silver and barium salts.
>>> Solvents and Cosolvents
When certain dyes are used or formulated as liquid dyes, solvents need to be added to help them dissolve, such as ethylene glycol, diethylene glycol, glycol ethers, formamide, thiodiethanol, etc… They can all be used as dye solvents. When dyeing with phthalocyanine blue, use the auxiliary solvent and copper salt, and use the auxiliary solvent sodium benzylaminobenzene sulfonate for the vat dye.
>>> Reducing Agent and Oxidizing Agent
When using vat dyes, it is necessary to use a reducing agent to dissolve vat dyes. Commonly used are sodium dithionite, sodium formaldehyde sulfoxylate and sulfur dioxide. When vat dyes are used for anti-dyeing, a mild oxidizing agent, sodium m-nitrobenzene sulfonate, can also be used in printing pastes to protect the dyes from possible reducing components in the paste.
>>> Fixing Agent and Color Development Aid
When dyeing with direct dyes, acid dyes and reactive dyes, fixing agent is used before and after dyeing to increase the amount of color and fastness. Fixing agent mainly uses colloidal salt and polymer quaternary ammonium salt. Dyes for printing sometimes use color-developing additives, such as diethylethanolamine when steaming and color-developing fastamine.
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, sodium alkyl or long-chain amido benzene sulfonate, alkyl polyoxyethylene ester, sodium lignosulfonate, tea sulfonic acid formaldehyde compound, oleoyl polygum carboxylate and so on.
Sodium hexametaphosphate can also have a good dispersion effect. Hexametaphosphoric acid can connect to each other and polymerize into a long spiral chain, which can be adsorbed on the surface of the particles to enhance the hydrophilicity of the particles, and significantly increase the negative potential on the surface of the particles, so that the electric double layer is more stable and the dispersion effect is better. Sodium hexametaphosphate dispersant is a surfactant with two opposite properties, lipophilicity and hydrophilicity in the molecule, which can uniformly disperse the solid particles of inorganic and organic pigments that are difficult to dissolve in liquids. At the same time, it can also prevent the sedimentation and agglomeration of solid particles to form the medicine needed for stable suspension.
>>> Levelling Agent
Polyoxyethylene ether surfactants are commonly used as leveling agents, cationic dyes should use cationic surfactants, acid dyes should use anionic surfactants.
>>> Matting Agent
Compared with natural fiber, the surface of synthetic fiber is too smooth and the reflectivity is too high, so titanium dioxide, zinc sulfide, etc. must be added to improve it.
It is used to remove foam caused by surfactants in the printing and dyeing process. In the past, tributyl phosphate, octanol were generally used, but now organic stone compounds have been used.
Adhesives for printing and dyeing can use various synthetic latexes such as copolymers of butadiene, styrene, acrylonitrile, vinyl acetate, vinyl chloride, and acrylate. It is required to have strong adhesion, that is, good fastness to abrasion, soft hand feeling, and not easy to yellow under high temperature and light.
>>> Dyeing 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 two enolates.