The hottest printing ink and green printing

2022-09-23
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Printing ink and green printing

with the vigorous development of industrial production in various countries and the general improvement of people's living standards, the earth environment and atmospheric environment on which human beings live have been increasingly polluted, which is threatening the quality of human life and even the survival of human beings themselves. The printing industry plays an important role in the national economy. Colorful printing materials not only bring civilization to mankind, but also cause environmental pollution. Reducing or completely eliminating the environmental pollution caused by e-mouth brush and turning printing into green printing will become the historical mission of future generations or even generations of printers

The development of printing industry is closely related to the development of printing ink. The pollution of traditional solvent based inks to the environment is obvious to all. Therefore, countries all over the world attach great importance to the development and research of environmental friendly inks, and China is no exception. New printing inks, printing materials and auxiliary materials with no pollution and less pollution are increasingly developed and applied. Green printing is increasingly becoming a consensus and common action in the printing industry

I. composition and classification of inks

as we all know, printing is the process of transferring pictures and texts on the printing plate to the substrate through ink, so the role of ink is extremely important. The main components of ink are pigments and binders. In addition, there are additives

pigments play a role in color development, and their main properties such as dispersion, coloring power and covering power have a direct impact on the performance of inks. Ink pigments are divided into organic pigments, inorganic pigments and special pigments C for special printing, such as gold powder, silver powder fluorescent pigments, phosphorescent pigments), etc. at present, the use of special pigments in packaging and printing is on the rise

binder composition is complex, which plays a key role in ink, including oil binder and resin binder. The oil-based binder has good adhesion and certain resistance, forming an ink film with good gloss. Resin type binder is made of synthetic resin or modified resin dissolved in mineral oil, vegetable oil or volatile agent. Organic solvent is one of the main components of binders, and its function is to make the ink have a certain fluidity. After the ink is transferred to the substrate, the solvent with high volatility volatilizes rapidly, while the solvent with low volatility seeps into the substrate, so that the pigment particles and binder are fixed on the surface of the substrate and dried. The commonly used ink solvents are petroleum solvents, alcohol solvents and ester solvents. Additives, namely additives, are the auxiliary components of inks. They are used to adjust the printability of inks. Additives are divided into tone adjusters, fluidity adjusters, dryness adjusters, etc., which are used to adjust the tone, fluidity and drying speed of ink respectively

there are various classification methods of inks, and classification by use is one of the main classification methods, which can be divided into relief (including flexo), offset gravure, special inks and new inks

relief printing ink shows a significant reduction trend with the change of relief printing share, but flexographic relief printing ink is outstanding, and the share of flexographic printing is gradually rising. Flexo printing is divided into solvent ink, water ink and UV ink. The latter two inks are becoming the focus of development because of their excellent environmental performance

offset printing inks should have strong coloring power and certain anti nature. Most of them use resin binders. Offset printing inks include fast drying bright offset printing inks and rotary offset printing inks. The former is suitable for high-speed color e-mouth brush of sheet fed paper, while the latter is used for web glue e-mouth rotary transfer brush machines with a speed of 25 ~ 30 million rpm, which are divided into two types: Hot set and cold set. Thermosetting offset ink is suitable for color printing. Cold set offset printing ink has low viscosity and is suitable for printing paper and offset paper

block printing inks are divided into engraving gravure and photographic gravure. Engraving intaglio ink is mainly used for Securities printing. Its binder is oil binder with low viscosity. Photographic intaglio ink depends on solvent evaporation and drying. It is low viscosity ink. It is divided into benzene type, gasoline type, mixed type, alcohol type and water-based type. Benzene type gravure printing ink B. toluene and xylene are used as solvents. The cosolvent benzene is added during printing to adjust the drying speed. Its advantages are strong adhesion, good film formation, high gloss of ink film, but it is toxic and has great pollution to people and the atmospheric environment. Gasoline type gravure printing ink B 'gasoline is used as solvent and is a low toxic ink. Hybrid gravure printing ink and alcohol gravure printing ink are less toxic or very small, and have little environmental pollution. The dosage is rising sharply. The solvent of water-based gravure ink is water and a small amount of alcohol. The quality of printing is gradually improving. It is generally optimistic by people and has broad development prospects

special ink refers to the ink specially prepared for special printing. New ink refers to the ink newly developed according to the market demand. At present, UV ink is recognized as an ideal green ink because of its very good environmental protection

II. Composition and properties of environmental friendly inks

environmental friendly inks are also called green inks. They refer to the UV weft curing inks and water inks of rongdaizhai products with good environmental protection.

UV curing inks are also called UV inks. UV inks are composed of binders, pigments, active diluents, light inducers and additives. Binder is the main component, accounting for about 30% to 50%, and is the main film-forming material of ink. It determines the nature of ink. Generally, saturated or unsaturated dibasic acid esters and acrylic resins are used. Active diluent is an active monomer with large molecular weight. Its content accounts for 40% - 60%, which is mainly used to adjust the viscosity of ink. Photoinitiator is an organic platform of the characteristic group of the cross-linking reaction of the excitation light-emitting curing resin. The content is only 1% to 5%. It produces free radicals or ionic bow photosensitive resin f binder) after absorbing UV energy and polymerizes with the active diluent monomer, so that the molecules are cross-linked and polymerized for curing

at present, UV ink is mainly used in offset flexo printing, gravure printing and silk printing. Different printing methods, different substrates, and different performance requirements for UV ink. Therefore, the specific composition ratio of UV ink is also different, The main characteristics of UV ink are: no solvent volatilization, no pollution, meeting the requirements of Taiwan environmental protection. It is widely used in food packaging and printing. It has good printing suitability, suitable for Taiwan paper, cardboard, plastic products, metals, textiles and other printing materials. The printing curing time is short, energy consumption is low, and the printing quality is good

ink is composed of pigment binder, additives, etc. Colorants, namely colorants, are the color rendering substances of ink. The binder of ink is mainly composed of water-based polymer lotion or water dispersible resin amine compounds and other organic cleaning agents (a very small amount of ethanol). Resin is the most important component of binder, and water-soluble acrylic copolymer resin is widely used. It directly affects the gloss, chemical stability, water resistance, heat resistance, etc. of ink. Amine compounds make the ink 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. Auxiliary agents are modifiers, including stabilizers, defoamers, diluents, etc. to adjust the pH value, viscosity, drying speed of ink, eliminate bubbles, and dilute the color of ink

the ink does not contain volatile organic compounds, which is pollution-free and non-toxic to the environment and per capita. The ink has good color stability, high brightness, strong adhesion, adjustable drying speed, good water resistance, excellent printing performance, and does not corrode the plate

ink is most used in flexo printing and also in gravure screen printing

third, the development of green ink is a necessary condition for the realization of green printing

in order to reduce environmental pollution, the development of green ink and the development of green printing are gradually recognized by people

legal regulations also encourage people to choose green ink. European environmental protection regulations have added provisions related to printing, which clearly limits the emission of volatile organic compounds in the printing industry. It not only increases the content of waste disposal, but also provides a way to reduce the loss of ink. As early as June 2000, the UK legislated to prohibit the printing of food packaging films with solvent-based oil ink. According to statistics, 60% of the printed matter in the UK is printed with alcohol free or alcohol less ink. In the United States, the Environmental Protection Administration (EPA) strongly opposes the use of solvent based ink. Flexographic ink is the only non-toxic ink approved by the American food and Drug Association, which is widely used in the packaging and printing of food and drugs. In developed countries such as Europe, America and Japan, in addition to offset printing, ink is gradually replacing the traditional solvent based inks that are easily scattered in nature. In the United States, for example, 95% of flexographic printing and 80% of gravure printing are printed with ink

among various printing methods, offset printing plays a leading role. Offset printing ink, as the main force of printing ink, has developed very rapidly in recent years. Its variety, specification and quality have reached a very high level. There have been many improvements in low toxicity or non-toxic and pollution-free aspects, especially the development speed of UV ink is amazing. China's domestic amine ink has also made great progress. Some ink manufacturers have passed the ISO 9000 series quality system certification, and some have also passed the ISO 9001 series environmental management system certification. Compared with foreign countries, our ink quality is stable. There is a certain gap in the development of new product seriation (especially the development of environmental friendly offset printing ink)

flexo printing can use 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 ink quality produced by developed countries in the world has reached quite high. The quality of Yongping domestic ink can basically meet the domestic market demand, but there is still a big gap between domestic ink and foreign high-end ink in terms of color saturation, gloss, stability and so on, especially in terms of high-speed overprint

with the enhancement of people's awareness of environmental protection, green printing is the inevitable trend of the development of the printing industry. The operating procedures and protection precautions of the electro-hydraulic servo universal experimental machine are the trend. To realize green printing, using green ink is a necessary condition. At present, green ink mainly refers to UV ink and water ink. We have reason to believe that in the future, there will be more green ink that will have a great impact on the plastics and plastic waste recycling industry at the same time. Better green ink will continue to be developed. Green printing will be achieved, and will be achieved

information source: China printing chemicals

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