What are the commonly used additives in water-based inks?

In order to improve the various properties of ink and meet the different requirements of printing operations, various additives need to be added, and the weaknesses of ink can be improved through scientific use of additives to improve the printability and stability of ink.

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Additives play an important role in the production and printing process of water-based plastic ink, and can improve some properties of water-based plastic ink. The use scope and types of additives are very wide, and each water-based plastic ink has an additive that matches it. The amount of additives used in water-based plastic inks is very small, but their role is very large.

Defoaming agent

Its function is to inhibit and eliminate the generation of ink bubbles. The dosage is generally 1% to 2% of the total ink volume. It is added during the production process of ink. During printing, if there are many bubbles, an appropriate amount can be added. Generally speaking, when the pH value of ink is too low, the viscosity is too high, or when the printing machine runs relatively fast, bubbles are likely to be generated. If the amount of bubbles generated is relatively large, uneven ink color and white leakage will occur, which will inevitably affect the quality of the ink. The quality of the print.

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PH stabilizer

It is mainly used to adjust and control the pH value of ink to stabilize it at 8.0 to 9.5. At the same time, it can also adjust the viscosity of ink and dilute the ink. Generally speaking, during the low-speed printing process, an appropriate amount of pH value stabilizer should be added at certain intervals to keep the ink in good printing condition; during the printing process, just add adjusted new ink. Generally, pH value stabilizers use polymer additives such as organic amines; ammonia or ethanolamine, etc. can also prevent ink from coalescing and molding during storage and transportation, and reduce the viscosity of ink.

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Slow drying agent

Slow-drying agents are generally used in paper inks and are rarely used in plastic inks. It can prevent ink from drying on the printing plate or anilox roller, inhibit and slow down the drying speed of ink, and reduce the incidence of printing failures such as blocking and pasting. It is generally controlled at 1% to 2% of the total ink volume. If If too much is added, the ink will not dry completely, and the printed matter will become sticky or smelly.

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Wetting and dispersing agent

It has pigment affinity groups and hydrophilic polymers, which can promote pigment dispersion, make the ink easy to grind, strengthen the binding between binder molecules and pigments, and reduce the surface tension of the ink. Its dosage is 4% to 20% of the pigment mass.

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Thickener

Thickener is a rheological additive that has three functions in ink:

①Thickening effect increases the viscosity of the ink and improves the logistics and chemical stability of the ink;

②The rheological properties of ink can be controlled during printing;

③Due to the increase in the viscosity of the ink, the pigments and fillers in the ink are not easy to precipitate, which increases the storage stability of the ink. The dosage of thickener is generally 0.5%-1%

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Anti-scratch agent/slip agent

Anti-scuff agent, also called slip agent, can improve the wear resistance and smoothness of printed products, and also has the functions of waterproofing, gloss enhancement, and anti-adhesion. The dosage is generally 2%-3%, and not too much should be added. Such additives are mainly waxes, especially low molecular weight polyethylene waxes. It can be added during the ink preparation process or transferred during printing. Suitable anti-scuff agents mainly include silicone and wax. Currently, there are mainly various wax emulsions that can be used in water-based inks, such as polyethylene wax emulsion, carnauba wax emulsion, polyamide wax emulsion, etc.

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Preservatives

It is a general bactericide that can inhibit the growth of bacteria and can be added when necessary.

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Leveling agent

It plays a leveling role during the drying process of ink.

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Anti-scratch agent

Anti-scratch agent is also a water-based ink additive. When used in water-based ink, it can improve the scratch resistance, surface hydrophobicity, anti-stick and anti-fouling properties of the coating film, making the coating smoother.

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Cross-linking agent

Multifunctional aziridine cross-linking agents are commonly used to combine the ink resin into a network structure when drying, which can improve the adhesion of the water-based system to the substrate.

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UV absorber

UV absorbers for water-based systems are used in ink, which can effectively prevent the aging and yellowing of the overlay ink layer, and prevent or delay aging phenomena such as color loss and gloss loss of the color ink.

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