Talking about environmental protection ink technology
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At present, the understanding of green ink is mainly divided into the following two aspects: From a narrow point of view, green ink refers to the use of raw materials that have little harm to the human body. There is almost no pollution in the production and printing process of ink, and it does not constitute a living environment. Threatening ink varieties; In a broad sense, green ink refers to reducing environmentally and harmful components in raw materials; reducing environmental and human harmful components during ink production and use; easy to recycle, reducing “secondary pollution”.
Green inks have injected new vitality into the printing and packaging industry. Whether water-based inks, degradable inks or UV-curable inks, these environmentally friendly inks have contributed greatly to the sustainable development of the printing and packaging industry. At present, there are mainly the following types of green inks on the market: energy-curable inks; alcohol-soluble inks; environmentally-friendly offset inks. The advantages and disadvantages of the above inks are described in detail below.
First, energy curing ink
Energy-curable inks are mainly classified into UV-type curing inks and EB-type curing inks. UV-based curing inks use a certain wavelength of ultraviolet radiation to complete ink drying through an instantaneous photochemical reaction; EB-type inks use a high-energy electron beam to accelerate monomers. Polymerized into a polymer.
1. U V type ink has the following advantages
① U V ink is safe and reliable, solvent-free, non-flammable, non-polluting, suitable for food, beverage, tobacco, alcohol, medicine and other packaging conditions with high hygienic conditions.
② UV ink printing has good adaptability, high quality inkjet printing, no change in physical properties, non-volatile solvent, stable viscosity, strong inking power, high dot resolution, good tone reproducibility, bright and bright ink, strong adhesion, suitable for fine products. Inkjet.
③ U V ink can be dried instantaneously, with high production efficiency and wide adaptability. It has good adhesion on different printing carriers such as paper, aluminum foil and plastic. After the product is printed, it can be stacked immediately without blocking.
④ U V ink has excellent physical and chemical properties. The process of UV curing and drying is a photochemical reaction of UV ink, that is, a process from a linear structure to a network structure, so it has many excellent physical and chemical properties such as water resistance, alcohol resistance, acid and alkali resistance, abrasion resistance, and aging resistance. Not all kinds of inks.
⑤ U V ink usage is saved. Since there is no solvent volatilization, the active ingredient is high, and nearly 100% can be converted into an ink film, which is less than half of the ink or solvent ink, so the cost is relatively low.
Of course, U V ink also has certain disadvantages: UV has certain damage to the human body; after curing, the ink is difficult to degrade, which is easy to cause "secondary pollution".
2. The main advantages of E B ink are as follows
① Contains no volatile substances V O C , no odor or only a small odor, reducing the health hazard to workers, no environmental pollution.
② Good resistance, because the chemical substances in the ink form a polymer three-dimensional network polymer through cross-linking reaction, and the ink film has good chemical resistance and abrasion resistance.
③ The curing time is short, generally only 0.1 seconds to dry thoroughly, compared with the traditional printing takes a few minutes or even a few days to completely dry, greatly improving the production efficiency, and is conducive to mass production.
④ The pigment has a high base and the printed product has a beautiful appearance and a strong gloss and three-dimensional effect.
⑤ Reduce the cleaning time of the printing press. Even if the E B ink in the ink fountain is stored for one night, it will not crust or harden and reduce waste. Of course, as a new type of curing technology in development, E B curing technology also has some shortcomings:
For example, in recent years, although the price of EB curing equipment has been greatly reduced, the one-time investment of equipment is still large; the price of EB ink is still higher than that of ordinary ink; EB curing is only suitable for flat coating curing. Therefore, the geometry of the cured product is limited; an important characteristic of EB ink is that it has good resistance, but this is a factor that is difficult to deink and hinder recycling when the waste printed matter is recycled, so it is also used in the recovery of printed matter. New research must be done.
Second, alcohol soluble ink
The solvent of the alcohol-soluble ink is alcohol, and the alcohol is brewed from grain, and the grain is a renewable product. Therefore, the new alcohol-alcohol-soluble ink has a strong market competitiveness and a broad market prospect. The main advantages are as follows:
① Suitable for a variety of printing substrates, with a stable adhesion and complex suitability.
② There are no benzene and ketone solvents, and the residual solvent of the print is extremely low.
③ Excellent printability, suitable for all kinds of low-speed to high-speed gravure composite plastic printing.
④ Low solvent residue, safe, non-toxic, environmentally and hygienic.
⑤ It has high gloss, freeze resistance, high printing color and good adhesion, and bright colors such as printed products.
There are still some shortcomings in the quality of domestic alcohol-soluble inks, such as darker color, poor transparency, low gloss, and serious gel tendency.
Third, environmentally friendly offset printing ink
Offset inks account for 50% of the market share in China, and environmentally friendly offset inks are mainly of the following types:
1. Vegetable oil based offset ink
Because the emission of V O C will seriously pollute the environment, vegetable oil-based offset printing ink is more and more popular. Soy ink is the main variety of vegetable oil-based offset printing ink, which gradually replaces ordinary offset printing ink and is widely used in commercial fields. Its main advantages are:
① Environmental protection. Soybean ink is a mildly purified soybean oil mixed with additives such as pigments and resins. Replacing petroleum with vegetable oil reduces the use of fossil raw materials and alleviates the strain on the earth's resources. Moreover, the volatile organic substances required for soy inks are not as good as petroleum inks, reducing air pollution. Its pigment degradation rate is also four times that of standard gasoline inks.
② Economy. Soy inks are cleaner than petroleum extracts. To achieve the same dyeing effect, the former requires less pigment and lowers ink costs. The Hazardous Waste Research and Information Center of the Illinois Department of Energy and Resources conducted a survey on soy inks in the 1990s. Many printers reported: “Soybean inks are 15% more ductile than normal inks, further reducing The amount of ink used, the printing cost is reduced. Although the average price of soy ink is 5% to 10% higher than that of gasoline ink, the former is used in various expenses such as pigment usage, volatile organic use and printing machine cleaning costs. It takes less time. What's more, with less soy ink, you can print brighter and more eye-catching prints than petroleum inks.
③ resistance to friction and heat. Often, newspaper readers are often blackened by ink when reading. This is because the ink on the substrate is easily rubbed off after printing with conventional inks. Soy ink is more resistant to friction than traditional inks, so newspaper readers are not bothered by black hands, and there is no bad odor. Soy inks have a much higher boiling point than petroleum volatiles, and when the oil is heated by a laser printer or copier, it does not volatilize and stick to the paper, nor does it contaminate machine parts.
④ Good inking. Soybean oil inks drier slower than cured or waterless offset inks. However, from the practical results, the transferability of the ink is good, the ink in the field is good, and the ink on the bright spot is even. After the ordinary offset ink reaches the paper, the ink film will break off due to the rapid penetration of the solvent, and the soybean oil ink will be separated by the slow penetration. The peeling surface of the ink is closer to the side of the blanket, which is equivalent to The thicker ink film is transferred to the paper surface, so the amount of ink transfer is increased.
⑤ Good laser resistance. Soy ink is the best choice when prints need to be resistant to lasers. Its boiling point is much higher than that of petroleum volatiles. When the ink is heated by a laser printer or copier, it will not volatilize and stick to the paper, nor will it contaminate the parts of the press.
⑥ color is good. Soybean ink raw material is edible oil such as salad oil. It is jointly developed by Japan Elitetang Printing Co., Ltd. and Toyo Ink Co., Ltd. As a refined vegetable oil, salad oil is processed through a series of strict refining processes such as decolorization, deodorization and removal of free fatty acids. It has excellent fluidity and colorability, high transparency, bright colors, and is not easy to fade, making it suitable for a wide range of color printing. UV-mixed soy ink for waterless printing has excellent performance in deinking, and recycling is not a problem; it can print high-quality printed matter without powder spraying, and can obtain excellent printed matter in post-processing such as filming and printing. , improved operating environment.
⑦ multiple effects. Compared with traditional inks, soy inks have bright color, high concentration, good gloss, good water adaptability and stability, friction resistance and drying resistance.
The main disadvantages are: It is not suitable for personal printers; because there is no volatile organic compound, soy inks are slower than normal gasoline inks; soy inks depend on a single crop, and once the threat of pests and diseases is encountered, the supply of raw materials will become a problem. .
2. Non-aromatic offset printing ink
The non-aromatic offset printing ink is directed to remove aromatic hydrocarbons in the ink, thereby reducing the environmental pollution of the ink during normal production and printing, and is widely used in Japan. Its main advantages are:
The petroleum-based mineral oil used in traditional offset printing inks causes odor and skin irritation due to the inclusion of aromatic hydrocarbon components. The use of inks containing aromatic-free (A F) mineral oils has been greatly improved in these respects. The so-called aromatic-free mineral oils control the aromatic components in the mineral oil to less than 1%. From an environmental point of view, the use of aromatic-free (A F ) mineral oil-based inks not only reduces odor and irritates the skin, but also improves the printing environment and can be considered as a highly safe ink.
Its main disadvantages are: due to the high aniline point and other properties, the solubility of the resin is very poor, the direct use of AF mineral oil in the common ink formulation will have a great adverse effect on the performance of the ink. If the use of AF mineral oil and ordinary ink resin to produce ink, due to the high aniline point of AF mineral oil, the solubility of the resin system is deteriorated, the release of mineral oil in the ink is enhanced, and the fixation speed is accelerated, and the fluidity is improved. And the transferability is deteriorated, and printing failure such as paper napping occurs due to an increase in viscosity, and the gloss of the printed product is lowered.
3. Waterless offset ink
Waterless offset printing uses a printing plate coated with an ink-repellent silicone resin. When the coating is removed from the image, the ink can be absorbed and the image transfer can be realized. Its main advantages:
① Printing costs are low. Since there is no dampening water, it does not take a lot of time to adjust the ink and water balance when printing. It speeds up the printing speed and reduces the waste of the test paper. The ink can be dried, which can reduce the drying temperature and reduce energy consumption. Balanced changes caused by downtime, increased production efficiency and economic efficiency.
② print quality is good. Waterless offset printing has a low dot enlargement rate and good dot reproducibility, especially the details of the dark tone can be reproduced very well; no dampening water will not cause the paper to be stretched and deformed, and the overprinting accuracy is improved; The ink color is evenly thick and bright, and the printing durability of the printing plate is greatly improved. The printing substrate has a wide range, which can be printed on paper or printed on plastic and metal.
③ Waterless offset printing does not contain alcohol, it can protect the environment and prevent pollution.
Its main disadvantages: the price is more expensive; the technology is not mature enough, and it is difficult to balance both the dirt resistance and the ink transferability. How to balance it is the key to the design of waterless offset ink.
At present, there are many types of environmentally friendly inks. Printing companies must consider health and safety issues when selecting inks, and try to improve energy efficiency and waste. Therefore, we must shop around and ask for the opinions of others as much as possible. Every printing company is now facing certain environmental pressures, which are determined by the needs of the market and customers. But printing companies should also be aware that ink is not the whole process of printing. Although green ink may have a little impact on the production process, only a comprehensive environmental plan can ensure the long-term stable development of a printing company.