Soft packaging ink development in the direction of green

In recent years, the environmental protection of commodity packaging has become a trend in the future development of packaging, and the corresponding requirements also apply to packaging printing inks without pollution. Traditional solvent inks secrete toxins during volatilization, which is particularly detrimental to food packaging. This article introduced several commonly used environmentally friendly inks: water-based inks, UV-curable inks and water-based UV inks in three categories, including water-based UV inks is a new research direction, with broad prospects.

At present, China's ink industry already has a considerable scale, with more than 300 production companies, of which more than 30 have considerable scale and production and research and development capabilities. The total production capacity of ink is approximately 220,000 tons per year, ranking fourth in the world. It accounts for 5-6% of the world's total output. Generally speaking, although China's inks can basically meet the needs of the domestic printing and packaging industry, there is still a considerable gap compared with the advanced level in foreign countries. After joining the WTO, China's ink industry needs rapid development and narrowing the gap with the world's advanced level.

The packaging industry is an important growth area for ink worldwide, because the demand for food, drink, and medication is stable regardless of economic conditions. The trend in the packaging market has confirmed that there will certainly be development after the economic downturn. For the ink-manufacturing industry, the packaging process is also an edge science that can be continuously improved, and there will be continuous improvement in new technologies and processes.

The important development trend of current packaging printing materials is to improve their environmental performance, choose energy-saving, low-cost, non-toxic, non-polluting, and easily degradable pollution-free packaging materials, and ink is a raw material that causes more serious pollution, therefore, how to reduce the ink The environmental pollution and energy consumption have become the most important development direction of the ink industry.

To fundamentally improve the impact of ink on the environment, we must start from changing the composition of the ink, that is to use environmentally friendly materials as far as possible to formulate a new type of environmentally friendly ink, in order to reduce VOC emissions and improve energy efficiency. At present, environmental protection inks mainly include water-based inks, UV-curable inks, and water-based UV inks.

The biggest difference between water-based inks and solvent-based inks is that the solvents used in water-based inks are water and ethanol. The VOC content is extremely low, and the environmental pollution is small. In the flexible packaging industry, solvent-based inks are mainly based on volatile drying. The lower the boiling point of the solvent, the more volatile it is and the more toxic gas is released to pollute the environment. After printing, there are residual toxic substances on the surface. The solvent used for the ink is water and ethanol excluded from the VOC list, which can greatly reduce VOC emissions. At present, more than 40% of American plastic film printing uses water-based ink, and other developed countries use water-based ink more and more in flexible packaging. In the United States, water-based inks complying with the VOC regulations must meet the following two standards: 1. In the ink composition of the use state, the volatile component proportion is 25%, and the moisture content is 75 or more; 2. The ink with less moisture content is not used under the condition. More than 60% of the volatile components. In recent years, China has also made some provisions for the packaging of food. The status of “green” printing is continuously improving in China. At present, China's flexible packaging of water-based inks ranks first among other printing inks at a consumption of 35%.

UV inks are inks that use ultraviolet light of different wavelengths and energies to form and dry inks under ultraviolet light. By using different UV spectra, different energy can be generated and monomers in different ink binders can be polymerized into polymers, so the UV ink film has good mechanical and chemical advantages. The main advantages of UV inks are: 1. Without solvent , fundamentally avoid the VOC pollution to the environment; 2, fast drying, low energy consumption; 3, good gloss, colorful; 4, water resistance, solvent resistance, good wear resistance. The main components of UV inks include pigments, photopolymerizable prepolymers, photopolymerization initiators and additives. The prepolymer is the main functional ingredient. The commonly used prepolymers have three major categories: epoxy acrylates, amine ester acrylates, and polyester acrylates. At present, UV ink has become a relatively mature ink technology. Its pollutant emission is almost zero, and it has a reputation as an energy-saving and environment-friendly "green" product. According to statistics, the annual output of UV inks is approximately 16,000 tons in Japan, approximately 18,000 tons in Europe, and approximately 19,000 tons in North America, of which flexo inks and offset inks are the most rapidly growing.

Water-based UV inks are a new research direction in the field of UV inks. Since the viscosity of the prepolymer in the general UV ink is generally very large, it is necessary to add a reactive diluent to dilute, and the currently used diluent acrylate compounds have different degrees of skin irritation and toxicity, so in the development of low viscosity pre While developing polymers and low-toxicity reactive diluents, another development direction is to study water-based UV inks, that is, UV inks using water and ethanol as diluents, which can achieve even lower toxicity when VOC emissions are still low. . According to reports, water-based UV solder mask inks have been developed, and the United States has also successfully developed water-based UV inks for printing.

In short, only the continuous use of advanced technology and the development of "green packaging printing inks" and other functional ink products that meet environmental protection requirements can bring new development opportunities to China's packaging industry.