With the steady development of China's offset printing market, offset printing ink has also developed rapidly, and the quality level is basically close to or reaches the international advanced level. According to incomplete statistics, in recent two years, the proportion of offset printing ink in China ink market has risen to 50% ~ 60%, which is still dominant at present, and this proportion will not change much in the future for a long time.
The offset printing market has put forward new requirements for ink.
At present, printing, publishing and packaging printed matter are gradually developing in the direction of personalization, diversification and high-grade. In order to adapt to the new changes in the printing market, printing plants constantly update and improve printing equipment. The emergence of high-speed, multi-color, low-pollution and high-efficiency printing equipment also puts forward new requirements for ink production enterprises. The offset printing ink produced by ink manufacturers must meet the requirements of high-speed printing, short-version moving parts and full automation.
(1) high-speed adaptability: it can adapt to the printing speed of 14000 sheets/hour or more.
(2) Quick-drying performance: Due to the short production cycle, short-version live parts need to enter the next process of four-color printing immediately after printing, such as glazing, film covering or die cutting, etc., so it is required that the ink can be dried quickly to facilitate the smooth post-processing.
(3) Good water resistance and fast ink-wash balance.
(4) Stability in the printing process: the ink transfer rate and dot gain rate do not change with the change of speed, time and temperature.
(5) Printing factory with convenient packaging: vacuum tank, plunger tank, barrel and tank suitable for automatic ink supply system.
(6) Ink is universal.
Environmental protection requirements
With the development of economy, the voice of environmental protection is getting higher and higher, and the printing industry has put forward new requirements for non-toxic and pollution-free offset printing ink. Environmental-friendly offset printing ink has been widely concerned by users and has been used in packaging, newspapers, commercial printing and other fields. Environmental-friendly offset printing ink has been widely used in the United States, Japan and other countries, but its application in China is still quite small, which is due to technical factors, but the main reason is lack of understanding. Environmental protection offset printing ink is mainly non-aromatic soybean ink. PAH (Polycyclic Aromatic Hydrocarbons) contained in traditional ink components is a volatile solvent printing film, which is harmful to human body. The volatile organic compounds contained in it not only aggravate air pollution, but also cause harm to human body. The offset printing soybean ink can reduce environmental pollution and harm to human body by replacing part of petroleum solvent with soybean environmental protection materials. The current situation of domestic offset printing ink market, with the development of printing industry in China, the pace of domestic ink industry is also accelerating. With the installation and production of a large number of imported and domestic high-speed offset presses, the adoption of new printing materials, and the special requirements of new printing technology and post-press processing, ink production enterprises rely on scientific and technological progress to Hongbo printing, constantly develop marketable new products, improve old products, enrich product varieties and publish periodicals, and gradually approach the international advanced level. The updating of ink production equipment and the improvement of production technology have gradually attracted the attention of ink manufacturers. In recent 10 years, major domestic ink manufacturers in Tianjin, Shanghai, Hangzhou, Shenzhen, Taiyuan and other places have paid attention to collecting market information and printing materials, and constantly developed new offset printing ink products that meet the market demand, such as bright and quick-drying ink, cardboard ink,
In recent years, the output of matte paper ink, news rotary ink, cold-set offset rotary ink, UV ink, offset synthetic paper ink, iron printing ink and thermosetting offset rotary ink newly introduced in China has increased year by year, and the quality is close to the international advanced level of three-dimensional printing, which has been recognized by printing customers at home and abroad. In addition to replacing the high-grade offset printing ink imported in the past in the domestic market, some domestic offset printing ink products have also entered the international market. Some special offset printing inks with high added value have also been successfully developed to meet the requirements of special printing. Sheet-fed offset printing ink is growing steadily in the domestic printing market to print uv. With the innovation and improvement of printing machine, domestic sheet-fed offset printing ink has adapted to the requirements of high speed, multi-color, quick drying, high efficiency and energy saving, constantly developed new products for daily printing, expanded its application in packaging and printing fields, such as tobacco, alcohol, food, cosmetics and other industries, and met the requirements of "high brightness and high concentration" in book printing and "quick drying and friction resistance" in packaging and printing. Rotary offset printing ink also meets the needs of the rapidly developing newspaper industry and commercial printing. Printing Co., Ltd. continuously improves the quality level and output.
China's offset printing ink products are mainly printed with offset printing bright and quick-drying ink and non-thermosetting offset printing rotary ink, followed by thermosetting offset printing rotary ink, UV offset printing ink, synthetic paper offset printing ink, offset printing iron ink, anhydrous offset printing ink, offset printing metallic ink and various special offset printing inks. Moreover, domestic thermosetting offset printing rotary ink and UV offset printing ink have developed rapidly in recent two years. The gap between domestic offset printing ink and similar foreign ink products, there are still many shortcomings in domestic offset printing ink, which can not fully meet the needs of today's packaging, publishing and printing market.
(1) Production technology of offset printing ink. The automation degree of ink production process is low, and the automation degree of ink detection method is low. Human factors affect many printing industry publishers, and the stability of raw materials is poor, which leads to the gap between the consistency and stability of ink products.
(2) Color standardization of offset printing ink. There are several South China printing standards in the world, such as European standard, Japanese standard and American Pan Tong standard, but China offset printing ink does not have its own color standard.
(3) Wide color gamut ink. Printing with four-color ink with wide color gamut instead of six-color or seven-color ink can improve the quality and production efficiency at the same time, but the field of wide color gamut offset printing ink in China needs to be developed.
(4) Four-color ink suitable for high-speed overprinting. Domestic four-color overprint ink still needs to be further improved in terms of high concentration, high transparency and vividness, and excellent overprint performance.
(5) Environment-friendly offset printing ink. Printers, the printing industry in China is facing great environmental pressure. Because most of the inks used in printing contain organic solvents (compared with solvent-based inks, there are few organic solvents in offset printing inks), the volatilization and emission of organic solvents will cause environmental pollution. In addition, ink contains harmful heavy metal elements such as lead, chromium, cadmium, mercury, arsenic and barium, which is very harmful to human body and environment. From the perspective of environmental protection and health, more and more users regard low toxicity, environmental protection and pollution-free as important conditions when purchasing ink. In China, the research and development of environmentally friendly offset printing ink is still restricted by many factors, but for the ink industry in China, the ultimate goal and ultimate pursuit is to realize and popularize green ink.
(6) waterless offset printing ink. Waterless offset printing does not use fountain solution, which can be said to have made great contributions to environmental protection. It is predicted that waterless offset printing will have a good development space in light paper printing in recent two years. However, in the actual printing process, waterless offset printing ink is greatly affected by the environmental temperature and is easy to get dirty, and special waterless offset printing equipment is needed. In addition, because waterless offset printing plate is expensive for notebook printing, its application and promotion in China are limited and its development is slow.
The direction of future efforts
(1) Shorten the distance. With the increasing output of offset printing ink, the production process of offset printing ink is gradually developing towards automation. By introducing advanced equipment, the control level of ink production process in China has been improved. By increasing the single batch output of ink, the consistency and stability of ink quality are improved.
(2) Establish China's own color standard for offset printing ink. The National Printing Standardization Technical Committee has made a preliminary plan for the formulation and working route of "China Offset Printing Ink Color Standard" and related "China Printing Paper Color Standard" and "China Printing Color Standard". From now on, sample collection and experimental verification of relevant standards drafting will be carried out. Printing production, standardization work in China is in full swing. In short, offset printing ink, as one of the raw materials for offset printing, should maintain its own advantages in a4 printing, absorb and learn from foreign advanced experience, improve the quality of offset printing ink by introducing advanced technology and equipment, establish color standardization of ink products, and make efforts for the rapid development of China's ink industry.
There are many kinds of inks with different physical properties, some are very thick and sticky, and some are very thin. Its composition can be divided into three parts: liquid component is called adhesive; The solid components are pigments (pigments or dyes) and various additives. Different inks have different drying methods; Different printing processes use different inks; Different substrates use different inks. The following inks are classified according to drying methods, different printing processes and substrate materials.
Printing ink is a paste-like colloid, which is composed of pigments, binders, fillers and other materials. Pigment endows printed matter with colorful tones; Adhesives are used as carriers of pigments and also as adhesives for fixing pigments on the surface of substrates; The filler endows the ink with proper properties, so that the ink can meet the printability of various printing processes.
Ink should have certain fluidity, meet the performance required by various printing processes, and can be quickly dried on printed matter. The dried ink film should have various corresponding resistances, such as water resistance, acid resistance, alkali resistance, light resistance, friction resistance and wear resistance.
The liquid component in the ink component is called adhesive; The solid components are pigments (pigments or dyes) and various additives.
For ink, color, body bone (rheological properties of ink such as dilute consistency and fluidity are usually called body bone of ink) and drying performance are the three most important properties of ink, which should also be paid attention to when developing ink formula and technology and producing ink; The printed film on the printed matter should have a certain resistance to make the printed matter practical.
The law of color change
1, the principle of ink blending is that the three primary colors of Y, M and C can be mixed into black according to a certain proportion.
2. Three primary color inks Y, M and C can be mixed in equal proportion to produce black, and different degrees of neutral gray can be obtained with different proportions of diluents.
3. Three-color inks Y, M and C can be mixed in different proportions to obtain different tones or complex colors. The three-color inks Y, M and C are R, G and B, while Y, M and C are composite colors. Note that the prepared hue is biased towards the hue of the ink with a large proportion.
4. The inks of the two primary colors are mixed equally to obtain the standard intermediate color.
Color matching method
1, chromatographic comparison method. For example, the full-page spot color on the color manuscript, through color registration and color label, has the ink proportion matching with the color. From the chromatogram, we can find the percentage of dots of Y, M and C in halftone dot color.
2. Color three-attribute comparison method
The lightness, hue and saturation of ink prepared by color samples were compared respectively.
① If there is a difference in lightness, it can be corrected by adding thinner.
(2) If the hue is different from a certain color, it can be corrected by complementary color method, but it will increase neutral gray and reduce the brightness of black.
Requirements for mixed inks
1, the hue of ink must conform to the color draft of decoration design, try to narrow the gap and strive for the same hue.
2. The prepared ink should not be too thin and too thick, so the ink should have a certain viscosity and fluidity.
3 cigarettes, wine packaging, decoration, trademarks to add a certain amount of red, white and drying oil, not more than 5% of the amount of ink. Too much drying oil will crystallize, which will affect the dullness of ink. Drying oil adds too little, and it will stick at the back. Therefore, the amount of drying oil should be appropriate, neither too much nor too little.
4. Choose good quality ink. The nature and hue of original ink from different manufacturers are different. It is best to choose a manufacturer's ink products.
5. When mixing ink, consider the nature of printing paper. When the paper is rough, it has strong ink absorption and consumes a lot of ink when printing. Grasp the temperature difference to increase or decrease the dry oil.
6. The prepared ink should be enough at one time, and there is a little surplus, so as to avoid that the amount of ink adjustment is not enough to re-adjust, the printed hue is different, and too much ink adjustment wastes the original ink.
7. Make a detailed analysis of the color draft of packaging design, and strictly calculate and master the proportion of original ink and diluent.
8. After the ink is transferred, carefully compare the color samples and color samples printed on the machine and correct the hue error in time. When washing ink and changing color, it is required to clean Mo Dou and ink roller. Generally, it needs to be cleaned many times to avoid the problem of ink color deviation caused by discoloration due to unclean washing.
9. Record the composition and quantity of the blended ink in detail, so that the stub can be archived as a reference for the next repeated printing.