Printing ink VS green printing

With the vigorous development of industrial production in various countries and the general improvement of people’s living standards, the increasingly polluted environment of the Earth and the atmosphere that mankind lives on is threatening the quality of human life and even the survival of mankind itself. The printing industry occupies an important position in the national economy. Brilliant and colorful prints bring civilization to humanity, but also cause environmental pollution, reduce or completely eliminate the pollution of the E-brush to the environment, and make printing into green printing, and will become The historical mission of future generations or even generations of printers.

The development of the printing industry is closely related to the development of printing inks. The environmental pollution of traditional solvent inks is obvious to all. Therefore, all countries in the world have paid great attention to the development of environmentally friendly inks. China is no exception. New printing ink printing materials and accessories without pollution and pollution are increasingly being developed and applied. Green printing is increasingly becoming the consensus and joint action of the printing industry.

First, the composition and classification of ink

It is well known that printing is the process of transferring graphics on a printing plate to a substrate via ink, so the role of the ink is extremely important. The main components of inks are pigments and binders. There are also additives.

The pigment plays a role in color development. Its main properties such as the degree of dispersion and the hiding power of the tinctorial force have a direct influence on the performance of the ink. Ink pigments are divided into organic pigment inorganic pigments and special pigments (such as gold powder, silver fluorescent pigments, phosphorescent pigments) used in special printing, etc., and the use of special pigments in packaging and printing is currently on a linear upward trend.

The complex composition of the binders plays a key role in the inks, and there is an oil type binder resin type binder. The oil type binder has good adhesion and certain resistance properties to form a good gloss ink film. The resin type binder is made by dissolving synthetic resin or modified resin in mineral oil vegetable oil or volatile agent. The organic solvent is one of the main components in the binder, and its role is to make the ink have a certain degree of fluidity. After the ink is transferred to the substrate, the volatile solvent quickly evaporates and the less volatile solvent penetrates the interior of the substrate so that the pigment particles and the binder are fixed on the surface of the substrate and dried. Commonly used ink solvents are petroleum solvents. Alcohol solvents and ester solvents. Additives that are additives are auxiliary components of the ink. Used to adjust the printability of the ink. Auxiliaries are divided into color adjustment agents, fluidity modifiers, drying modifiers, etc.

The ink classification method is various and one of the main classification methods according to the use classification can be divided into letterpress (including flexography) offset gravure, special ink and new ink.

Toppan inks have dramatically decreased with changes in the proportion of letterpress prints, but Flexo Toppan inks have stood out, and the share of flexographic printing is gradually increasing. Flexo printing ink is divided into solvent type ink, ink and UV ink. The two inks are becoming the focus of development due to their excellent environmental performance.

2. Offset printing inks must have strong coloring strength and a certain degree of resistance to nature. Most of the use of resin-based materials. Offset inks have quick-drying bright offset inks and web offset inks. The former is suitable for sheet-fed high-speed color E-brushes, and the latter is used for E-rotary web presses with a speed of 25 to 30 thousand rotations per hour, divided into two types, thermosetting and cold-setting. Thermosetting offset inks are suitable for color printing. Coldset offset inks have low viscosity and are suitable for printing newsprint and offset paper.

Block printing inks are divided into engraved azole plate and gravure plates. Engraving gravure printing ink is mainly used for the printing of valuable securities, its link material uses the oil viscosity material with lower viscosity, gravure printing ink relies on solvent evaporation to dry. For low viscosity inks. Divided into benzene type. Gasoline-type hybrid. Alcohol type and water-based five kinds. Benzene gravure ink b. Toluene, xylene solvent. Add solvent benzene when printing to adjust the drying speed. Its advantage is strong adhesion. Film formation of a good ink film gloss, but toxic, great pollution to people and the atmosphere. Gasoline gravure ink b' gasoline as a solvent. For low toxicity ink. Mixed gravure inks and alcohol gravure inks are less toxic or less toxic. Little pollution to the environment. The amount is rising sharply. Water-based gravure ink solvent is water and a small amount of alcohol. The quality of printed products is gradually improving. People are generally optimistic and have broad prospects for development.

Special ink refers to ink specially formulated for special printing. New ink refers to the newly developed ink according to market demand. Currently. UV ink has a very good environmental protection. It is recognized as an ideal green ink.

Second, the composition and nature of environmentally friendly ink

    Eco-friendly ink is also called green ink. Refers to UV-filling inks and inks that have good environmental protection properties.

UV curing ink, also known as uV ink. UV inks consist of binders, pigments, reactive diluents, photoinitiators, and auxiliaries. The content of the main component of the binder is about 30% to 50%, which is the main ink film forming material. The nature of the ink is determined by the use of saturated or unsaturated dibasic acid esters and acrylic resins. Reactive diluent is a relatively high molecular weight active monomerized substrate. Content of 40% to 60% is mainly used to adjust the ink viscosity. Photoinitiators are organic compounds that excite the cross-linking reaction of photocurable resins. The content is only 1% to 5%. It absorbs ultraviolet light energy and generates free radicals or ions. So that the molecules crosslinked and converged to solidify.

Currently. uV ink is mainly used for offset flexo printing. Gravure printing and screen printing have different printing methods for different substrates. The performance requirements for uV ink are also different. Therefore, the specific distribution ratio of uV ink is also different. The main features of uV ink are: no solvent evaporation and no pollution. Futai environmental protection requirements. Widely used in food packaging and printing. Good printability suitable for paper jams and plastic products. metal. Printing and curing materials such as textiles have a short curing time, consume less energy, and have good print quality.

Ink is composed of color materials, additives, and the like. The colorant is the coloring agent, which is the coloring material of the ink. The linking material of the ink is mainly composed of an aqueous polymer emulsion or a water-dispersible resin amine class substrate and other organic detergents (a very small amount of ethanol). Resin is the most important component of the binder. Water-soluble acrylic copolymer resin is commonly used. It directly affects the gloss chemical stability, water resistance, heat resistance and so on. Amine-type mesogenic substances make the inks weakly alkaline while water and a small amount of ethanol are used to dissolve the resin to adjust the viscosity and drying speed of the ink. Auxiliaries are regulators. Including stabilizer defoamers, dilute agents and so on. To adjust the PH value of the ink viscosity drying speed, eliminating the bubble to reduce the ink color.

Ink-free volatile organic compounds have no pollution to the environment and per capita. Non-toxic ink has good stability and high brightness. Adhesion strong dry speed adjustable water resistance. Excellent printing performance. Does not corrode media.

The use of ink in flexo printing is also used in gravure printing.

Third, the development of green ink is a prerequisite for achieving green printing

To reduce environmental pollution. The development of green inks to develop green prints is gradually becoming known.

Legal regulations also encourage people to buy green ink. The environmental protection regulations in Europe have added printing-related provisions that have a clear restriction on the emission of volatile organic compounds in the printing industry. Not only adds waste processing content. Also provides a way to reduce the loss of ink, the United Kingdom as early as in June 2000 to ban the use of solvent-based ink printing food packaging film. According to the statistics. 60% of prints in the UK are printed using alcohol-free or light alcohol inks. The United States Environmental Protection Administration (EPA) strongly opposes the use of solvent-based ink flexo inks as the only type of non-toxic parking ink approved by the US Food and Drug Association for packaging printing of foods and pharmaceuticals. In Europe and the United States and Japan and other developed countries in addition to offset printing. Ink is gradually replacing the traditional solvent-based ink. In the United States, for example, 95% of flexo and 80% of gravure prints are printed in ink.

Among all kinds of printing methods, offset printing is the main force of offset printing inks as printing inks. In recent years, the mainstay of printing inks has developed very rapidly. Its varieties, specifications and quality have reached a very high level. There have been many improvements in terms of low toxicity or non-toxic pollution. The development speed of UV ink is even more alarming. China's domestic amine printing ink has also made considerable progress. Some ink production enterprises have passed the ISO 9000 series quality system certification, and some have also passed the ISO 9001 series of environmental management system certification. Compared with foreign countries, we have the stability of ink quality. There is a certain gap between the development of new product series (especially the development of environment-friendly offset printing inks).

Flexo can use ink and ink, which has great advantages in environmental protection. It is called the best and most promising printing method in the world. In recent years, it has developed very rapidly. The quality of ink produced by developed countries in the world has reached a fairly high level. The quality of Yongping's domestic ink and wash inks can basically meet the needs of the domestic market. However, domestic ink and wash inks are still not as good as foreign high-grade inks in terms of color saturation, gloss, and stability. Small gaps, especially in the high-line cable printing gap.

With the increase of people's awareness of environmental protection, green printing is an inevitable trend in the development of the printing industry. It is a prerequisite for green environmental protection printing to use green ink. At present, green ink mainly refers to UV ink and ink. We have reason to believe that more and better green ink will be continuously developed in the future. Green environmental printing will certainly be realized and will surely be realized.

Reprinted from: China Ink Web