Gravure printing uses more VOC as solvent in the ink, causing more air pollution, which will cause great damage to the human body, especially the nervous system. VOC will also react photochemically with nitrogen oxides in the air to produce ozone. And smoke. Therefore, it is imperative to develop a gravure printing ink with environmental protection requirements. How to realize the environmental protection of the film gravure printing ink? The so-called compliance with environmental requirements is to change the ink composition, using environmentally friendly materials to formulate new inks.
First, no benzene solvent ink and water-based ink
The fundamental difference between water-based inks and solvent-based inks is that water-based inks use water as the solvent instead of organic solvent, which significantly reduces VOC emissions, prevents air pollution, does not affect human health, is not easy to burn, and is stable in ink, colorful, and does not corrode. Plate material, simple operation, low price, good adhesion after printing, strong water resistance, rapid drying, it is especially suitable for food, beverages, pharmaceuticals and other packaging printed matter, is the world recognized environmental protection printing material, is also the current all printing ink The only ink approved by the U.S. Food and Drug Association. At present, 40% of U.S. plastic printing uses water-based ink, and other economically developed countries (such as Japan, Germany, France, etc.) use water-based ink in plastic film printing. The United Kingdom has enacted legislation to prohibit the printing of food films using solvent-based inks. According to relevant data, in the United States, water-based inks conforming to the VOC regulations have a volatile content of less than 25% and a moisture content of more than 75%, while those with less moisture use more than 60% of the non-volatile components. Two standards. Water-based inks are usually used for printing paper products including paper-plastic composite products. The feature is to meet the ink absorption of paper printing, so that the printed material is full and full of color. What is more rare is that the solvent is water and ethanol, and it is an environmentally friendly green ink.
At present, there are still many companies that use gravure printing inks that are generally made of chlorinated polymers. In the ink production process, the chlorinated polymer needs to be dissolved using a strong solvent (such as toluene and other aromatic solvents), and the viscosity of the ink needs to be adjusted during the printing process using toluene. Chlorinated polymer ink systems are now considered unsuitable for environmental protection. This is because the chlorofluorocarbons that are volatilized during production can damage the ozone layer. The use of aromatic solvents (toluene) can cause injury to the health and safety of workers during ink production and printing. In addition, the solvent residue in the packaging ink is another important issue to pay attention to. Since toluene is a slow-drying solvent, it easily remains in the dried ink film layer, corrodes the food in the package, and produces harmful odors.
The production of plastic gravure inks is subject to laws and regulations such as Fire Protection Law, Labor Safety Law, and Health Law. Therefore, it is an inevitable trend to actively develop and apply green gravure inks and water-based inks that meet the requirements of environmental protection.
Second, film packaging material gravure water based
Although water-based gravure inks have attracted much attention as an alternative to toluene-based inks, the inks in packaging film printing are still water-based and have not yet reached a truly practical stage. On the whole, the important reason why water-based gravure inks have not been popularized further is that the printing performance and quality are still not up to the standard for solvent-based gravure inks. This is mainly due to the higher surface tension of water, which makes it difficult for the ink to wet. If the printing speed and printing quality of the gravure solvent ink are to be obtained, not only the aqueous ink itself requires advanced technology, but also the gravure printing apparatus and the printing plate roller need to be improved. For example, changing a corrugated or engraved roll with a groove depth of about 38 to 42 μm to a laser-made plate roll with a groove depth of about 24 to 28 μm requires a more effective and powerful drying apparatus and a printing plate roll that must be made of a corrosion-resistant material. , ink pump and scraper and other components. These improvements require considerable investment.
Third, gravure alcohol-soluble composite plastic ink
Since water-based gravure inks are not yet fully capable of replacing toluene inks, the ink industry has been working hard to develop alcohol-soluble inks that can be accepted by the environment. Alcohol-soluble ink can effectively solve the health problems caused by toluene ink and solvent residue affect the quality of packaged food and other issues. In Europe and the United States, this development has become a trend. In Asia, such as Singapore, South Korea and other countries, toluene ink is being eliminated, will be replaced by alcohol-soluble gravure ink. Alcohol-soluble inks are now widely used in the domestic gravure printing industry. It can be predicted that in the near future, alcohol-soluble inks will occupy a major share of the high-grade food and pharmaceutical flexible packaging ink market in China.
The gravure alcohol-soluble composite plastic ink has the characteristics of low odor, no benzene, etc. The use of such environmentally friendly inks will certainly increase the competitiveness of gravure in the field of packaging and printing.
IV. Trends in the development of traditional inks in the Asia Pacific region to environmentally friendly inks
Green ink is an important area of ​​concern. In many countries in the Asia Pacific region, environmental regulations will become increasingly stringent, and some printers will find it difficult to adapt to this change in the current difficult economic situation, while ink manufacturers work hard to meet the requirements of these new standards.
The Asia-Pacific ink industry has seen a trend toward the development of environmentally friendly inks such as water-based flexo inks, soybean oil inks, and UV inks from traditional solvent inks. The development and production capacity of environmental inks has become one of the key factors for ink manufacturers to win in the Asia Pacific region in the future.
The current demand for toluene-based gravure inks is still growing. Toluene-nitrocellulose-based inks also have a certain market share in some large multinational packaging companies, but not so much. In Southeast Asia, UV-curable inks are increasingly popular, but so far a large number of such inks are still dependent on imports. In the end, these strict environmental protection regulations will be implemented. When environmental regulations come into effect, ink manufacturers must consider environmental issues, whether produced in-house or indirectly in the country. At present, there is no strict or indirect regulation on ink in China, but just as in the Chinese paint industry, ink-related environmental laws and regulations will be introduced sooner or later. Non-volatile organic (VOC) inks and water-based inks have been tested in the minds of each ink manufacturer or in the laboratory, so that they can be put on the market quickly when environmental regulations are introduced.