Classification of additives for ink

In printing or ink formulations to improve the performance of some additional materials. Also known as adjuvants and additives. Commonly used ink additives include driers, thinners, viscosity reducers, thinners, antioxidants, degelling agents, defoamers, surfactants, anti-pinhole agents, slip agents, plasticizers, and antiseptics Agents and spices etc.

Drier, an auxiliary agent that is added to the ink made of dry vegetable oil to accelerate the drying of the ink film. Also known as desiccant. Referred to as dry oil, dry oil. It is a metal soap or salt composed of metal and organic acid or inorganic acid. Commonly used metals are cobalt, manganese, lead, zinc, calcium, cerium, zirconium and lithium. Commonly used organic acids are linoleic acid, naphthenic acid, 2-ethylhexanoic acid (abbreviated as caprylic acid or octacarbonic acid). Commonly used inorganic acids are boric acid. Various metal driers have their own unique effects.

①Cobalt drier: It is an oxidizing drier. The drying capacity is the strongest, and the surface dries quickly. The commonly used cobalt drier is cobalt naphthenate, which contains 7.3% cobalt. For ease of use, it is often diluted with No. 200 gasoline into a solution containing 3% of cobalt, and its amount is usually 0.05 to 0.10% of the ink based on metallic cobalt.

②Manganese drier: It is an oxidizing drier. However, it is far less rapid than cobalt driers in promoting the surface drying of the oil film, so it is beneficial to the drying of the bottom layer. The conjunctiva of manganese drier tends to become brittle and tend to turn yellow. Commonly used varieties are manganese naphthenate (containing 3% manganese) and manganese borate, which often need to be combined with lead driers as activators.

③Lead drier: It is a polymeric drier. It can promote the drying of the bottom layer of the oil film to form a tough dry film with good adhesion. However, its oxidation drying ability is extremely poor. If used alone, the surface will not dry for a long time, so it should be combined with cobalt and manganese driers to make the surface and the inside dry. Commonly used lead driers are lead naphthenate (diluted with 200# gasoline to 15% lead) and lead borate.

Lead driers are not suitable for inks containing alkyd resins, otherwise lead phthalate is likely to be precipitated. In this case, cerium, zirconium, and lithium driers can be substituted.

In order to prevent lead poisoning, lead-free driers are strongly recommended internationally in 2018, such as cobalt and zirconium driers with relatively high metal content.

When using driers, the ratio of lead to manganese is usually 7.5:1, the ratio of lead to cobalt is 10:1, the ratio of lead, manganese, and cobalt is 0.5:0.05:0.01, and the ratio of cobalt, zirconium, and calcium is 0.05:0.3 :0.1.

Thinner is used to dilute the color of the ink, but basically does not change the viscosity, rheology and printability of the ink. As four-color plate inks are not yet popular, lithographic inks still use six colors, namely red, yellow, blue, and black. In addition to red, yellow, blue, and black, "little red" and "little blue" must be printed to adjust the gradation tone. It is made up of red and blue original inks with diluent, so diluent is a relatively large amount of additives in ink in 2018.

The lightening agent of oil type ink is generally transparent oil and white oil, while the lightening agent of resin type ink is different from the above.

①Transparent oil: also known as Weili oil. It is prepared and dispersed by aluminum hydroxide and polymer oil.

②White oil: There are oil type and water type. Oil-type white oil is prepared and dispersed with ceresin, aluminum hydroxide, barium sulfate, a small amount of titanium dioxide and polymer oil; water-type white oil is vegetable oil emulsion (saponified) with lye and then added with magnesium carbonate and hydroxide Aluminum and ozokerite are prepared and dispersed. The latter is low in cost but not very stable and has poor performance.

③Resin-type diluent: It is refined from rosin-modified diphenol-based propane resin, dry vegetable oil, high-boiling kerosene, aluminum stearate, beeswax and cobalt naphthenate.

Viscosity reducing agent Auxiliary agent used to reduce the viscosity of the ink without affecting the ink body. Also known as adhesive removal. In the process of lithographic and letterpress printing, the paper fuzz occurs due to poor bonding of paper fibers, insufficient water resistance, poor paper surface coating, excessive ink viscosity, excessive driers, and low temperature in the printing workshop. , Leading to the emergence of ills such as pile-up and paste-up. At this time, the proper addition of viscosity reducing agent can overcome the problem of pulling paper. The dosage is generally 3-5% of the ink volume.

Viscosity reducers are mostly refined from dry vegetable oil, high boiling point kerosene, beeswax and aluminum stearate.

Thinner Used to reduce the viscosity of the ink, thereby increasing the fluidity of the ink. In the printing process, often due to the excessive viscosity of the ink and the poor quality of the paper, the phenomenon of paper fluffing and plate-off occurs. In this case, in addition to reducing the viscosity of the ink with a viscosity reducer, sometimes a thinner must be added.

Oil-based inks generally use No. 5 and No. 6 polymer oils (also known as varnishes) as thinners, solvent-based intaglio and relief inks can use toluene and xylene as thinners; water-based gravure inks can use water, ethanol, or isopropanol As a thinner. The thinner of resin-based ink is refined from dry vegetable oil, high-boiling kerosene and rosin-modified diphenol-based propane resin. The viscosity is 0.3 to 0.5 Pa·s (20°C).

Antioxidant Commonly known as anti-drying agent, anti-skinning agent, anti-drying agent. When certain drying oils and certain inorganic pigments such as lead chrome yellow, iron blue, etc. are used in the ink formulation, these materials are prone to oxidative polymerization or have a drying effect, causing the ink surface to crust during storage. , Sometimes even dry and can not be used; during the printing process, oxidized conjunctival drying inks may also crust and dry on the machine due to long downtime. In order to overcome these problems, an appropriate amount of antioxidant can be added to this type of ink to delay the oxidative polymerization of the drying oil.

Most of the antioxidants used in inks belong to the phenols of strong reducing agents, such as catechol, β-naphthol, eugenol (also known as eugenol), hydroquinone and so on. The most commonly used antioxidant is 2,6-di-tert-butyl-4-methylphenol.

Reverse Gelatinizer Ink storage, its viscosity will sometimes increase continuously, and with the increase of the surrounding temperature, it will accelerate the increase in viscosity, gradually harden, and even cannot be used. This phenomenon is called ink gelation. Adding 5-10% of degelling agent to the gelled ink can sometimes overcome the gelling phenomenon and make the ink usable immediately. Most degelling agents are made by dissolving calcium rosinate (acid value around 65) or high acid value maleic anhydride resin in linseed oil.

Defoamer is mainly used in relatively dilute inks. Most of these inks can be transported by pumps. When they are scraped off the plate during the printing process (such as photocopying ink) or flow down from a roller (such as flexographic ink), air is mixed in due to the impact between the inks and bubbles are generated. Aromatic, alcohol, and water-based inks all have this phenomenon, and water-based inks are the most serious. There are bubbles in the ink, which will reduce the quality of printing. In severe cases, the ink fountain will be full of bubbles, making printing impossible. Good defoamers have low solubility in various liquids and can significantly reduce the surface tension of the liquid. The surface tension of silicone oils, such as dimethyl silicone oil, is about 20 dynes/cm. Adding a few parts per million to the ink can have a good defoaming effect. This type of defoamer can be used directly, or it can be used as an emulsion or solution to improve the defoaming effect. For example, adjust the specific gravity of silicone oil with gasoline to 1, then add 5% emulsifier (such as Tween 80) and 1 times the water, and stir at high speed to make it fully emulsified and dispersed. It is good for use in water phase systems. Defoaming effect. Silicone oil can also be dissolved in gasoline, kerosene, toluene, xylene, dichloromethane or trichloroethylene to improve its dispersibility in non-aqueous phase systems. The effect of adding defoamer during ink making is better than adding during printing. It is easy to add spots when printing.

Surfactant The ink industry only selects surfactants that can emulsify or wet. The selection can be determined according to the balance value of its hydrophilic group and lipophilic group (ie H.L.B. value). The ink is generally a water-in-oil emulsion. Because of its better printing adaptability and longer storage stability, the emulsifier with H.L.B. of 4-6 is generally used. Commonly used varieties are Span (esters synthesized from sorbitol and various fatty acids) and Tween (adducts of Span and ethylene oxide) and so on.

Pinhole prevention agent Auxiliary agent for thin ink and paint. Sometimes, there are many small penetrating holes in the conjunctiva of printed products, called pinholes. Flexographic printing inks, gravure printing inks, tube roller coating inks, internal and external coatings for printing iron, and varnishes are all prone to pinholes. The pinhole phenomenon should be dealt with and overcome according to its cause. For example, because air bubbles enter the ink oil, the air bubbles burst during drying to form small holes. The surface tension of thin inks and coatings is too large, the wettability is poor, and the pinholes caused by the incomplete wetting of the printed object can be added some trioctyl phosphate, tributyl phosphate or silicone oil to reduce the surface tension of the system. Better wetting of printed objects.

Smoothing agent It is used to increase the slippery and friction resistance of the ink conjunctiva, which is beneficial to the adhesion and hardness of the ink film. Also known as slip agent and anti-friction agent. Most of these additives are waxes. Containing 1 to 3% wax in the ink can significantly improve the smoothness and friction resistance of printed products. Fatty acid amides are the most commonly used in solvent-based inks, and low-molecular-weight polyethylene (also known as polyethylene wax) is the most commonly used in glue and lead printing inks. The low-molecular-weight polyethylene is often stirred and melted at 120~150℃. The high boiling point kerosene is then passed through a three-roller to ensure uniform dispersion. Microcrystalline wax (fine particles of low molecular weight polyethylene) can be directly used to prepare inks.

Plasticizer Auxiliary agent that can increase the plasticity of polymer materials. It can make the printing film soft, and can also improve the adhesion to the substrate surface. 3% dibutyl phthalate is added to the solvent-based ink with nitrocellulose as the binder, and the fastness of the ink film after drying is better. If you rush to use the printed product after printing, you can use dimethyl phthalate plasticizer that evaporates quickly in the ink. It is beneficial to add some plasticizers to gravure inks (especially plastic inks for gravure printing) and flexographic inks, and the amount is generally 1 to 2% of the ink.

Preservative Auxiliary agent used in water-based inks that are prone to rancidity. Adding less than 1% of phenols or chlorinated derivatives of phenol to the ink can prevent rancidity and bacterial growth, and compounds such as ketals can also be used.

Perfume is added to the ink mainly to cover the unpleasant smell of the ink. Lilac fragrance is often added to letterpress printing inks, and some glue and type printing inks are added with clove oil. These spices can not only interfere with the sense of smell, but also play an anti-counterfeiting and anti-skinning effect. When printing pictures of flowers and fruits in some high-end prints, the corresponding fragrances are added to the ink for printing, so that the shape, color, and fragrance of the picture can be similar to the real thing.

Zirconium-based coupling agent/adhesion promoter 

In plastic compounding, a plastic additive that improves the interface performance of synthetic resins and inorganic fillers or reinforcing materials. Also known as surface modifier. It can reduce the viscosity of the synthetic resin melt in the plastic processing process, improve the dispersion of the filler to improve the processing performance, and then make the product obtain good surface quality and mechanical, thermal and electrical properties.

Its dosage is generally 0.5 to 2% of the filler dosage. The coupling agent generally consists of two parts: one is an inorganic group that can interact with inorganic fillers or reinforcing materials; the other is an organic group that can interact with synthetic resins.

Paint desiccant Zirconium Acetate

Manufacturing inks Zirconium Propionate


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