Types and composition of the most popular capital

2022-09-21
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The types and composition of capital digital printing inks

liquid digital printing inks are commonly used in ink-jet printing. The types of inks are related to the ink head structure of ink-jet printers. The ink head can be divided into thermal pressing type and piezoelectric type, and the piezoelectric type can be divided into high precision and low precision. For example, Epson's ink-jet head is a high-precision product, while Xaar and spectrum's ink-jet head have low precision. Most of the former use water-based inks, The latter uses mostly solvent based inks

1. Composition and performance of water-based inks

water based inks are mainly composed of solvents, colorants, surfactants, pH regulators, driers and other additives. For hot press inkjet printing systems, only water-based inks can be selected; On demand inkjet printing ink is usually water-based ink

(1) colorant

dyes are mainly used as colorants for water-based inks, because for water-based inks, dyes can be completely dissolved in solvents, and can be well fused with solvents in the form of macromolecules to show good colorability. Such as azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes and not coincident with the main needle, indigo dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes or metal phthalocyanine dyes, especially oil-soluble dyes

for water-based inks using pigments as colorants, since pigments are insoluble in solvents, other ingredients and higher technical requirements are needed to ensure their dispersion stability and color development effect in solvents. Pigments are divided into inorganic pigments and organic pigments, including carbon black, chrome red, molybdenum red, chrome yellow, titanium yellow, chromium oxide, vidian pigments, titanium cobalt green, cyan blue, cobalt blue, diketone pyrrolopyrrole, anthraquinone, benzimidazolone, anthropyrimidine, as well as azo, phthalocyanine, Shilin, perilla ketone, thioindigo, quinophthalone or metal complex pigments

pigments or dyes can be used alone, or two or more pigments or dyes can be used in combination. The average diameter of pigment particles is preferably 50 ~ 500nm, and its content is appropriately selected according to the purpose of the ink or printing characteristics, which is 1.0% ~ 10.0% of the total weight of the ink

(2) solvent

the solvent of water-based ink is generally deionized water as the main solvent, and then add an appropriate amount of organic solvent. The content of organic solvent is 0.1% - 1.0% of the total weight of the ink, mainly using the following categories

polyols: ethylene glycol, propylene glycol, butanediol, diethylene glycol, triethylene glycol, 1,2-pentanediol, 1,2,6-hexaerythritol, thiodiethylene glycol, polyethylene glycol and polypropylene glycol

glycol esters: lower alkyl esters of glycerol, polyalkanes, diols, and polyhydroxy alcohols

alcohol amines: diethanolamine, triethanolamine

amides: dimethylformamide, dimethylacetamide, dimethyl sulfoxide and Tetrahydrothiophene sulfone

ketones or ketone alcohols: acetone, cyclobutanone, N-methyl-2-pyrrolidone, n- (2-hydroxyethyl) - 2-pyrrolidone, 2-pyrrolidone

ethers: tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, especially tetraethylene glycol diethyl ether

(3) surfactants

commonly used surfactants are benzene sulfonates, oxidized alkyl amines and amine salts, alkyne diols and fluorinated surfactants, which are generally 0.1% - 1.0% of the weight of the ink, preferably 0.5%

(4) dispersant

for pigment based inks, in order to ensure the dispersion stability in water, dispersants need to be added to the inks. Usually, water-soluble pigment dispersion resins are used, including styrene maleic acid copolymer, styrene maleic acid acrylic naphthalene maleic acid copolymer, styrene maleic acid semi ester copolymer, vinyl naphthalene acrylic acid copolymer, vinyl naphthalene maleic acid copolymer, vinyl naphthalene maleic acid copolymer, etc. Relative to the total weight of the ink, the concentration of the dispersion resin is preferably 0.05% - 2 Not only for 3D printing 0%

(5) pH regulator and other regulators

pH regulator is also called buffer, and inorganic acid or inorganic base can be used. 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

conductive thermoplastic materials allow the continuous release of static electricity. Other additives can be added according to the specific use requirements of the ink, such as UV absorbers, metal chelators, defoaming silicone oil, etc. The content of these additives is generally 0.1% to 1.0% of the weight of the ink, preferably 0.5%

example of composition formula of liquid water-based ink:

dye 4.0% sodium benzenesulfonate 0.5%

chelating agent 0.5% sodium borate 0.5%

ethylene glycol 20.0% deionized water residue $page break $

2 Composition and performance of solvent based inks

(1) colorant

colorants in solvent based inks can use pigments or dyes, and their types and names are the same as those of water-based inks

(2) solvent

solvent based inks generally use organic solvents as the main solvent, and add an appropriate amount of water. Common organic solvents are diethylene glycol compounds and dipropylene glycol compounds, which are liquids at room temperature and pressure. Diethylene glycol compounds can be diethylene glycol ethers (especially alkyl ethers), such as diethylene glycol monomethyl ether; Or diethylene glycol esters, such as diethylene glycol monoethyl ether acetate; It can also contain polyethylene glycol monoether compounds and other polar organic solvents, such as alcohols (methanol, ethanol, propanol, etc.), ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.) and carboxylic esters

the mixing ratio (weight ratio) of diethylene glycol compound and dipropylene glycol compound is between 20:80 and 80:20, and the content is preferably 85% - 95% relative to the total weight of the ink

(3) dispersant

when pigments are used as colorants

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