Water-based offset inks overview

Water-based inks have long been used in waterborne varnish, water-based flexo inks, and gravure water-based inks, but the application of water-based inks to water-based offset inks is an important new product. Water-based offset inks are water-based inks containing acrylate linkages. They contain no mineral oil and no volatile organic solvents. They are dried by water evaporation and the conjunctiva of the binder components. The drying speed is equivalent to that of waterborne varnish. It is purely physically dry and does not require special drying equipment, but infrared dryers can be used to speed up drying.

Water-based offset printing inks are suitable for printing on all conventional offset printing presses, such as four-color printing with the fastest printing on a conventional four-color offset printing press, without smudging, and excellent print quality. Water-based offset printing inks are particularly suitable for small-size sheetfed offset and short-run imprints.

The printing industry is one of the fastest technologically advanced industries in the world in the past 20 years and has entered a new era of digital printing. According to briefings, humans have gone through about 100,000 years of printing from languages ​​to printing, 450 years from the invention of printing to printing, and from about 30 years from lead printing to color desktop systems, from color desktop systems to multimedia electronic publications ( Paperless printing lasted for 3 years and it took only 18 months from multimedia to the Internet. The international development trend is that the high-end color prints are rapidly growing, and high technologies such as computers and electronics are widely used in the printing process.

At present, the situation of China's printing industry is: traditional offset printing still dominates, flexographic printing, screen printing has developed rapidly, post-press binding automation, color desktop publishing system has been widely used, open and digital graphics processing system has been As a basic feature of the prepress system, direct plate making technology and digital printing have become the development direction of the printing and publishing industry. The development of the printing industry and the continuous improvement of environmental protection regulations have brought tremendous challenges and opportunities to the development of the printing industry, including the development of various new types of printing consumables that are in line with environmental protection; the transformation of the original processes, including the improvement of raw materials Improvements in drying methods, etc.

At present, solvent inks, which are widely used in screen printing and gravure printing processes in China, contain 50% to 60% of volatile components. If a diluent is used to adjust the viscosity of the ink, when the print is dry, The total content of volatile components emitted by the ink is 70%-80%. The gas volatilized by these organic solvents enters the workers' body through breathing, causing damage to the human liver and nervous system, and causing great harm to the environment.

The alcohol fountain solution in the offset printing process discharges organic volatiles to the air in the workshop all the time. When the ink roller and the blanket are temporarily cleaned when they are temporarily stopped or replaced, the flammable and explosive gasoline is used in large quantities ( Of course, from the point of view of the manufacturer, using gasoline as a cleaning agent is not only convenient and readily available, but also has a good cleaning effect and a fast drying speed. The most important thing is that the price is cheap and the production cost is greatly reduced. However, when seeing the benefits of gasoline, people often forget that using gasoline in this way could potentially cause an explosion that could make the printing plant empty for a moment; on the other hand, when using leaded gasoline, it will lead to The chronic lead poisoning of printing workers is even more neglected.

For a long time, the "ink flying" phenomenon in various printing processes has plagued the entire printing process. This is because when the printing press rotates at a high speed, the ink film between the ink rollers is split and elongated, resulting in a broken piece. Under the effect of the surface tension of the ink, these pieces shrink and form a large number of spherical small ink droplets scattered in the air. The so-called flying ink phenomenon. The problem of flying ink is not only a common type of printing failure that is extremely hazardous in the high-speed printing process, but also a type of problem that causes serious environmental pollution.

The major dangers that flying ink brings to the printing process are:

Contamination of the environment. The ink is scattered into the air, machinery and equipment, walls, etc. Lighter ones can affect the cleanliness and beauty of the environment. Severe ones can even cause explosions and cause safety accidents.

It has an adverse effect on product quality. The scattering of the ink on the printed product will cause a certain degree of stain on the surface of the printed product, which will affect the clarity of the printed product, etc. In severe cases, it will cause the printed product to become invalid.

Cause long-term damage to people's health. Since organic inks, organic solvents, and additives are commonly used in inks, many of them contain heavy metals. These harmful substances will be absorbed on the surface of the workers' skin through flying ink and be inhaled into the respiratory tract, which will inevitably adversely affect the health of the operators.

It can thus be seen that the emission of harmful gases, the use of hazardous liquids and solids, and the discharge of wastes in the printing industry pose a serious threat to human health and the human environment. Environmental issues not only involve the future of human civilization, but also involve the survival and development of enterprises.

When we formulate the development plan for the printing industry, we must simultaneously consider the issue of environmental protection and formulate feasible and effective measures.

In order to limit pollution in foreign countries, some countries have formulated a series of laws and regulations such as the "Labor and Health Law" and "Organic Solvent Discharge Law." These laws and regulations determine the research and development direction of printing production processes and inks.

In foreign countries such as Germany, the "Chemical Products Act" was promulgated as early as 1982. It contains three provisions: the protection of workers in the workshop; the protection of general health; and the protection of the environment. Under the pressure of environmental protection laws, foreign research departments and some manufacturers are forced to research and develop solventless inks or screen printing inks with low solvent content.

Before and after the 1990s, European and American countries passed the VOC laws related to environmental protection. The VOC law requires that printing houses and ink manufacturers meet the following requirements:

There should be no smell of solvents outside the job shop.
The concentration of volatile substances in the job shop must be lower than:
Volatile organic solvents 50 mg/m3 Carbon monoxide 100 mg/m3 Nitric oxide 100 mg/m3.
This rigorous environmental protection law will become the benchmark for environmental protection in various countries in the world sooner or later.

Reprinted from: 21st Century Fine Chemicals Network