Water-based inks are abbreviated as water inks, and are made by compounding and grinding water-soluble resins, organic pigments, surfactants and related additives.
First, the rapid development of the ink-and-water market Environment-friendly water-based inks are currently the most important application areas for flexographic printing and gravure printing. Most of the two printing methods are packaged products, including food packaging, tobacco and wine packaging, and children's toy packaging. And so on occupies a considerable proportion. With the improvement of people’s awareness of environmental protection, the urgent need for “green†printed materials is increasing. In recent years, flexographic printing has developed rapidly around the world, and is considered to be “the best and most promising printing method on the planet†in developed countries in Europe and America. For example, in the United States, 95% of flexographic prints and 80% of gravure are printed. Prints use ink. Currently, there are nearly 200 narrow-width flexographic printing production lines in China. The annual demand for water-based inks is more than 100,000 tons. In addition, the widespread application of ink in the packaging and printing of corrugated boxes has considerable market potential.
China's water-based inks were first successfully developed and put into production by Tianjin Ink Factory. At that time, gravure printing services were mainly used. At that time, gravure printing inks were improved from benzene-based solvents to gasoline-based solvents. Although they were improved in toxicity compared to benzene-based inks, they were flammable. Sex did not improve. Therefore, it was proposed that the gravure printing ink be further improved to a non-toxic, non-flammable water-based ink, which was called water-concave ink at that time. Since the ink is made with rosin acid amine salt as the main binder, the binder is not stable in storage in an aqueous medium, so that the ink is easily lost in the storage, thinning, drying is slow, and the water resistance is poor , easy to cause paper shrinkage and other drawbacks. These drawbacks have caused China's gravure printing and flexographic printing to be limited, and they have to adopt high-priced imported high-grade water-based inks, virtually increasing the printing cost and limiting the development of China's printing industry.
Entering the 1990s, with the rapid development of China's economy, people have continuously improved their awareness of packaging aesthetics and environmental protection. From 1995 to the end of 1998, China has introduced more than 130 modular flexo production lines in just a few years. It is distributed in more than 20 provinces and cities across the country, 90% of which are narrow-format flexo presses. The number of stations around is increasing, and there are also many imported high-end tri-color and four-color water-based ink printing slot machines for color printing of corrugated paper.
In the flexo package printing, most of the current domestic and foreign use of water-based ink printing. The widespread use of flexographic water-based inks is one of the important factors for the rapid development of flexographic printing. According to statistics from relevant departments, China has an average of more than 1,000 carton factories per province. For example, if 10% of water-based ink is used to print high-grade cartons, each household uses 10 tons of ink, and each province needs 1,000 tons of water-based ink each year. This is not yet Other printing and packaging products including flexo and gravure printing (currently, 100% of domestic flexographic printing uses water-based ink, and 80% of gravure printing uses water-based ink).
Of course, flexographic printing is still in its infancy in China and currently accounts for only about 3% of the printing industry. However, with the increasing popularity of green packaging and environmentally-friendly packaging, many tobacco companies, wineries, pharmaceutical companies, cosmetics, and children's toy companies All are prepared to use flexo printing products, and the proportion of flexo printing in the printing field will gradually increase, especially in the field of packaging and printing. It is estimated that by 2010, flexographic printing will reach about 15% in the printing field, and annual demand will be over 100,000 tons of water-based ink. Therefore, it is imperative to vigorously develop, develop, and produce high-grade water-based inks with great market potential. The product can be widely used in flexographic and gravure printing fields such as gold, silver cardboard, art paper, white board, plastic film, corrugated paper, self-adhesive paper, carton, paper packaging, books and magazines.
Second, the advantages and disadvantages of ink, a huge "green" advantage of water-based ink because of the absence of volatile organic solvents, greatly reducing the VOC (organic volatiles, the same below) emissions, thereby reducing the air pollution and improving the printing operation The environment of the staff is conducive to the health of the staff. It can completely eliminate certain toxic and harmful substances in solvent-based inks, eliminate the harm to human body and the pollution of packaged goods, and improve the overall environmental quality. It is especially suitable for tobacco, wine, food, beverages, medicines, children's toys and other health Conditions require strict packaging and printing products. In addition, it can not only reduce the risk of fire caused by static electricity and flammable solvents and hidden dangers, but also can reduce the residual toxicity of the printing surface, and cleaning printing equipment is convenient.
2. Insufficient water-based ink At present, whether imported water-based ink, or domestic water-based ink is not anti-alkali, nor resistant to ethanol and water, slow drying, poor gloss, easy to cause paper shrinkage and other drawbacks. To achieve alkali resistance, ethanol resistance, water resistance, and gloss enhancement, only flexographic UV inks are used. This not only increases the printing cost but also increases the printing process. If there is an automatic beer packaging production line, the use of alkaline lubricants, the pH value of 9 to 10, water-based ink can not bear, touch it on the fade. There is also summer when the South sells beer, not only to enter the refrigerator, and some are still soaked in ice water for a long time, water-based ink can not afford it.
Other problems include: the high surface free energy of the water component in the ink makes it difficult to wet and print the ink on substrates such as polyethylene; drying time is still the most important issue in ink applications unless The printing press is equipped with enough drying equipment, otherwise the printing speed will be affected; the gloss of the ink is lower than that of the solvent ink, which greatly restricts the use of the ink in places with high gloss requirements.
III. Suggestions for future development Through the technological improvements of the last 10 to 15 years, the ink-and-water system has successfully solved most of the original difficulties, such as difficulty in use, ink storage, substrate limitations, and corona treatment and surface tension. With regard to such issues, the new generation of ink and wash ink has changed its initial disadvantage as an advantage, and has gradually grown and matured. Under the premise of environment, safety, and health, ink-ink products, how to meet the best printing and post-processing adaptability, and improve economic efficiency are issues that we consider.
1, improve the performance of ink Ink users currently require improved performance is: pH stable ink system, ink manufacturing industry must develop a stable pH value during the printing process of ink, that is no need to detect and adjust the pH value in printing; Solubility is another important area of ​​research. In the process of amine volatilization, the resin tends to solidify and even adhere to the plate. Recently, ink manufacturers have improved the performance of the resin to make it more soluble, which means that the printing system can be run longer before cleaning, ie, the production efficiency is increased; the ink application requires continuous improvement in the application performance of the polyethylene substrate. . The ink-manufacturing industry is expected to increase the surface resistance of ink-and-ink printing, especially in terms of oil resistance, grease resistance, and better heat and freezing resistance. Recently in Europe and North America, product innovation has been driven primarily by meeting user requirements. The specific requirements for ease of use come from users, which will also be the driving force for new product development.
2. Follow-up on the environmental protection situation At this stage, the pressure from various aspects shows that environmental issues will receive further attention. In order to achieve even more stringent environmental management goals, printers are always looking for new ways of solvent ink printing operations to meet government regulations. The current focus of the printing industry is to strengthen the treatment of emissions from solvent ink printing. The usual practice is to use "incinerators" to absorb and incinerate VOCS. Others are more creative in the application of VOCS-based microbes or bacterial processing systems. . All of these methods rely on the efficient absorption of VOCS for transport to systems that can be neutralized or incinerated or absorbed by microorganisms.