Market Expansion and Technical Development of Water-based Ink (Part 2)

Water-based inks fall into two categories: one is a rosin-maleic acid modified resin series (low-grade) and the other is an acrylic resin (high-grade). Water-based inks have been used in corrugated paper printing for a long period of time abroad and have been used in China for more than 20 years. Corrugated paper printing is printed by letterpress (embossing), offset (flatprinting), and rubber-based water-washable printing. It has been developed as a flexible letterpress water-based ink. Flexopress water-based inks also evolved from rosin-maleic acid modified resin series (low grade) to acrylic resin series (high grade). Printing plates also transition from rubber plates to resin plates. Printing presses have also evolved from single- or dual-color machines with large rollers to 3- or 4-color FLEXO machines. The anilox roller also progresses from a 150-200 mesh metal roller to a ceramic roller between 180-250 mesh.

With the ever-changing printing technology, the quality of water-based inks has become more and more important. With the continuous development of society and the improvement of people’s consumption level, the printing of corrugated boxes must gradually develop in the direction of high quality, high quality, multi-color, and strong visual effects. In the direction of multi-color printing of colored noodles, it is also based on commodity packaging instead of transport packaging. The use of whiteboard cattle card to replace the box board cattle card, to achieve bright colors, good gloss, beautiful and so on. To achieve the above standards, high requirements are made for plate making and printing inks. In the high-end carton printing plate making, flexible plates must be used instead of rubber plates. High-quality aqueous ink must also be used to achieve the requirements of bright, fast-drying and high-speed production.

In order to eliminate the VOCS released by solvent-based systems, that is, to achieve the EPA (the US Environmental Protection Agency) to reduce or eliminate VOCS requirements, printers began to seek new technologies. For ink formulators, one possibility is to develop a water-based system that can reduce VOCS. EPA has always demanded that VOCS will eventually promote the use of ink. At this stage there are pressures from various sources that the environmental issue will be further noticed. In order to achieve increasingly 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.

At present, users of ink and wash require improved performance: a stable PH ink system, the ink-manufacturing industry must develop inks with stable PH values ​​during the printing process, that is, no need to detect and adjust the PH value in printing; re-dissolvability is another important factor. In the research field, the resin tends to cure during the volatilization of amines and even cures on the plate. Recently, ink manufacturers have improved the properties of the resin to make it easier to dissolve, which means that the printing system can be operated for a longer period of time, ie, the throughput is increased; ink applications require continuous improvement of the application performance of the polyethylene substrate; ink printing Alkaline resistance of packaging, and application in frozen food packaging. The ink-and-wash manufacturing industry is expected to increase the surface resistance of ink-and-ink printing products to make more products water-based, especially in terms of oil resistance, grease resistance, and better heat and freezing resistance.

Waterborne acrylic resin is one of the important raw materials for the manufacture of water-based inks. In order to meet the requirements of the printing process for inks, water-based acrylic resins are evolving to a higher level. In general, aqueous ammonia is used to dissolve acrylic resin and other water-soluble resins. Ammonia has a large odor. In order to reduce the ammonia odor, ammonia-free/amine-based inks that do not use ammonia or amines are now available. This ink has no special odor and is unique in that it consists of a sulfonated polyester resin and a water-soluble acrylic resin. system. To make more environmentally friendly inks, polymerized acrylic resins can be used instead of the commonly used low molecular weight polymers. Because low-molecular polymers produce a certain degree of molecular migration, some of the resin will enter the substrate and package from the ink film after the ink is printed on the substrate. The use of 50% polymerized acrylic resin not only achieves the same plasticizing effect, but also does not destroy the performance of the ink, and no molecular migration occurs after printing.

The new water-based inks use a mixture of alkyd and acrylic resins. This mixed resin is made by adding a special water-dispersible long oil-based alkyd resin to the acrylic suspension to provide good fast-drying properties. Adhesion, low VOC, acid resistance, good alkali resistance, can be used to make composite paper gravure and flexo inks, varnish and primer.