(3) Surfactants Surfactants commonly used are benzene sulfonates, alkylamine oxides and amine salts, acetylene glycols, and fluorosurfactants, and are generally 0.1% to 1.0% by weight of the ink. 0.5%.
(4) Dispersing agent
For pigment-based inks, it is necessary to add a dispersant to the ink in order to ensure its dispersion stability in water. Usually water-soluble pigment dispersion resins are used, including styrene-maleic acid copolymers, styrene-maleic acid- Acrylic naphthalene-maleic acid copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, ethylene naphthalene-maleic acid copolymer, and the like. The concentration of the dispersion resin is preferably 0.05% to 2.0% with respect to the total weight of the ink.
(5) pH regulators and other regulators
pH regulators, also called buffers, can use inorganic acids or inorganic bases. Common inorganic acids include hydrochloric acid, phosphoric acid or sulfuric acid; organic acids include methanesulfonic acid, acetic acid and lactic acid; inorganic bases include alkali metal hydroxides and carbonates; common organic bases include ammonia, triethanol and tetramethylethylenediamine.
Other additives can be added according to the specific application requirements of the ink, such as UV absorbers, metal chelating agents, defoaming silicone oil, and the like. The content of these additives is generally 0.1% to 1.0%, preferably 0.5% by weight of the ink.
Example of composition of liquid water-based ink:
Dyes 4.0% Sodium benzenesulfonate 0.5%
Chelating agent 0.5% Sodium borate 0.5%
Ethylene glycol 20.0% deionized water
2. Composition and properties of solvent ink
(1) Colorant
The colorant in the solvent type ink may use a pigment or a dye, and its type and name are the same as the water-based ink.
(2) Solvent
Solvent-based inks generally use organic solvent as the main solvent, and add the appropriate amount of water. Commonly used organic solvents are diethylene glycol compounds and dipropylene glycol compounds that are liquid at normal temperature and pressure, and diethylene glycol compounds may be diethylene glycol ethers (especially alkyl ethers) such as diethylene glycol monomethyl ether; Diethylene glycol esters such as diethylene glycol monoethyl ether acetate; may also contain polyethylene glycol monoether compounds and other polar organic solvents such as alcohols (methanol, ethanol, propanol, etc.), ketones Classes (acetone, methyl ethyl ketone, cyclohexanone, etc.) and carboxylic esters.
The mixing ratio (weight ratio) of the diethylene glycol compound and the dipropylene glycol compound is from 20:80 to 80:20, and the content is preferably from 85% to 95% with respect to the total weight of the ink.
(3) Dispersing agent
When a pigment is used as a colorant, a polyester polymer compound is added as a dispersant to the ink mixture. It is preferably used in an amount of 30% to 120% by weight of the colorant (especially pigment).
(4) Other additives
Other additives include stabilizers (such as antioxidants or UV absorbers), surfactants, binder resins, and wetting agents.
Antioxidants can use BHA (2,3-butyl-4-oxyanisole) or BHT (2,6-di-tert-butyl-p-cresol); UV absorbers can use benzophenones or benzotriazole Azo compounds; Surfactants can be any of anionic, cationic, amphoteric or nonionic surfactants; adhesive resins are acrylic resin, styrene acrylic resin, rosin modified resin, polyester resin, polyamide Resin, epoxy resin, polyethylene vinyl acetate copolymer, cellulose resin, etc. In addition, the use of a wetting agent helps prevent the ink from drying or crusting within the spray head. Commonly used wetting agents include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, tetraethylene glycol, poly Ethylene glycol, glycerol and the like are used in an amount of 5.0% to 6.0% of the total weight of the ink mixture.
Example of formulation of a liquid solvent ink:
Pigments 4.0%
Polyester polymer compound (dispersant) 2.4%
Polycyclic ethylene derivatives 0.5%
Mixed organic solvents 93.1%