Ink Industry Status and Development Trends (3)

4, water type ink

Water-based inks are mainly pigments, water-based binders and auxiliary materials. The most important feature of the water-based binder is that the resin in the binder is water-soluble and can be divided into the following three categories.

(1) Water-soluble binder

Water-soluble binders dissolve and dilute water-soluble resins such as polyvinyl alcohol, hydroxyethyl cellulose, and the like, and can be permanently dissolved in water. The range of use of the ink formulated by this linking material is limited, and it can only be applied to water-free applications.

(2) Alkali-soluble binders

The alkali-soluble binder is an alkaline solution of an acidic resin. Since the resin in the alkali-soluble binder is an acidic resin, such as adding an appropriate amount of ammonium hydroxide, the two chemically react to form a soluble resin salt, and the viscosity of the aqueous ink prepared with the binder is mainly adjusted by water to achieve printing. Suitability requirements. When the ink is transferred to the printed material, it becomes a water-insoluble ink film after drying. This ink can be used for gravure printing inks, which have poor abrasion resistance, water resistance and viscosity stability.

(3) Diffusion type material

The diffusion-type binder is an emulsion polymer, which is an emulsion of fine resin particles suspended in water. In this kind of link material usually contains fine particles (about 1um) of propylene, ethylene or styrene butadiene polymer, when the paint dries, the particles in the latex condense together to form a thin film. The latex binder has more significant advantages than the dissolving resin binder. The latex binder has high density and low viscosity and can produce a high quality thin coating. The latex can also contain larger polymer molecules and improve the wear resistance and heat resistance. , and the adhesion is also good.

Latex binders can also be mixed with alkali-soluble binders, thus retaining the advantages of latex and the printability of alkali-soluble binders. Water-based inks have been widely used for the printing of coated paper, white paper, corrugated paper, and plastic films.

In recent years, environmental regulations in European countries have become more and more stringent, and regulations have more specific restrictions on the emission of volatile organic compounds in the printing industry. Therefore, some countries began to abandon the use of solvent-based ink printing paper cups, hard plastic cups and other printed materials, change the use of ink, not only to avoid environmental pollution, but also improved the printing plant operator's working environment, reducing the operator suffering from memory loss even Personality changes mental health hazards. After the use of ink, the cleaning of the printing press has also become much easier, and the finished product does not need to adopt special fire prevention measures when it is stored.

There are still some problems in ink-jet printing. For example, ink is easily dried on the anilox roller, affecting the uniformity of the ink transfer, and the ink foam easily foams, affecting the color density and so on. To solve these problems, a closed-type squeegee ink supply system can be used, which can make the ink crater of the anilox roller completely filled with ink, the foam is also reduced, the consumption of ink is significantly reduced, and the ink is more vivid. It seems that the combination of a closed doctor blade system with a 140 thread/cm anilox roll (or higher anilox roll) and a high quality ink will give the best results.

5, UV light solid ink

UV light is also called UV ink. This type of ink is dried by ultraviolet irradiation, which causes the polymerization reaction of the ink vehicle. Because it does not require a heat source, no solvent, and no air pollution, it can be dried quickly under ultraviolet irradiation, and can be dried in a few seconds or a few seconds. Therefore, it has been rapidly developed and widely used. UV offset inks have been used in offset printing, flexographic printing, gravure printing, and screen printing.

Ultraviolet photo-curable inks are also very important pigments, binders and fine materials. Ultraviolet photo-curable ink binders are mainly photo-curable resins, and photo-curable resins are the most important components of photo-curable inks. All photo-curable resins contain a double bond that can be polymerized. The photo-curing rate of the double bond is arranged in the following order:

Acrylic base> Methacrylic group> Vinyl> Maleic acid

The photo-setting synthetic resin used in the UV ink is generally added with a photosensitizer, for example, benzoin ether. Under the irradiation of ultraviolet light, it is decomposed into two radicals. The free radical of the photosensitizer triggers the double bond of acrylic acid in the photocurable resin and the reactive diluent molecule, and the chain polymerization reaction takes place, so that the ink photocurable linking material is cross-linked and cured.