High-tech trend of ink

As people's requirements for the quality of printed matter are getting higher and higher, this requires the quality of the ink to be improved in order to improve the quality of the printed matter. Therefore, the use of high technology to develop the ink manufacturing industry is advancing with the times. After years of development, the high-tech trend of ink has become increasingly prominent. This paper discusses the high-tech trend of ink development.

First, environmental protection ink

Ink is the largest source of pollution in the printing industry. The annual output of ink in the world has reached 3 million tons. Annual global emissions of organic volatile compounds (VOC) caused by ink have reached hundreds of thousands of tons. These organic volatiles can form a more serious greenhouse effect than carbon dioxide, and they can form oxides and photochemical smog under the irradiation of the sun, seriously polluting the atmosphere and affecting people's health. In addition, ordinary inks used in food packaging, children's toys and other packaging and printing, whose organic solvents, heavy metals and other harmful components of the human body directly harm the health of consumers and contacts. Moreover, with the rising demand for environmental protection, as the main component of green printing, the environmental protection requirements for inks are also increasing. It can be said that environmental protection inks must be the first consideration in ink development in the future.

To make inks meet environmental requirements, the composition of the ink should be changed first, that is, using environmentally friendly materials to formulate new inks. At present, environmental protection inks mainly include water-based inks, UV inks, bio-inks, soybean oil inks, and some alcohol-soluble inks.

Water-based ink

The solvent of water-based ink is water instead of organic solvent. Compared with common ink, VOC emissions are significantly reduced during use, air pollution can be prevented, combustion is not easy, ink is stable, colorful, and media is not corroded. , Cheap, good post-print adhesion, strong water resistance, fast drying, it is particularly suitable for food, beverages, pharmaceuticals and other packaging printed matter, is the world's recognized environmentally friendly printing materials, and is currently the only US printing food ink, Pharmaceutical Association approved ink. At present, 40% of U.S. plastic printing uses water-based inks, and the use of water-based inks in plastic film printing is increasing in other economically developed countries such as Japan, Germany, and France. In June 2004, the United Kingdom enacted legislation to prohibit the printing of food films using solvent-based inks. According to relevant data, in the United States, water-based inks complying with the VOC regulations must achieve a volatilization ratio of 25% or less and a moisture content of 75% or more in the use state, and a low-moisture ink with a non-volatile content of 60 in use. % of these two criteria. Water-based inks are generally used for printing paper products and paper-plastic composite products.

2. Soybean oil ink

The ink is based on 10% soybean oil, VOC component is 0, can effectively prevent air pollution, improve the printing shop environment, colorful, with excellent machine stability and good post-printing, tolerance of the paper Larger, at the same time when printing with this ink, the deinking effect of the printed matter is good, which is favorable for recycling, and has typical environmental characteristics. Initially, this type of ink was used as a plant-type material, and the drying speed was relatively slow. Today, Shanghai DIC has developed the “CLS drying system” technology [1], which can promote the rapid film formation of the ink layer and make the soybean oil ink have Compared with common inks, they have better drying and rubbing resistance, and 3- to 4-color overprinting can also show better fixation than ordinary inks, and can form a firm, abrasion-resistant ink layer.

3. UV ink

UV (ultraviolet light curing) ink refers to the use of UV light of different wavelengths and energies to polymerize the monomers in the ink binder to form a polymer, and the ink is formed into a film and dried. UV inks also belong to inks. As inks, they must have bright colors (except for special cases), good printability, and appropriate curing and drying rates. At the same time, the ink film is required to be tough, has good adhesion, and has the characteristics of wear resistance, corrosion resistance, weather resistance and the like. It is the same as traditional inks, see Table 1.

As shown in Table 1, UV ink is a kind of ink without solvent, fast drying speed, good gloss, colorful, water resistance, solvent resistance and abrasion resistance. At present, UV ink has become a more mature ink technology, and its pollutant emissions are almost zero. 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. It should be noted that water-based UV inks in UV inks are the new directions in the field of UV inks. Because the viscosity of prepolymers in general UV inks is generally very large, it needs to be diluted with a reactive diluent, and the currently used diluent acrylate compounds have different degrees of skin irritation and toxicity, so in the development of low viscosity prepolymers and At the same time as low-toxic diluents, another development direction is to study water-based UV inks, ie, water and ethanol as diluents. Fortunately, water-based UV inks have been successfully developed and have been applied in some printing companies.

4. Bio Ink

Bio-ink is an ink made using biotechnology. It uses natural materials to exhibit complex functions that cannot be easily obtained by non-biological materials. Take bacteriorhodopsin as an example to explain its coloration principle. Bacteriorhodopsin is a protein that grows in the purple cell membrane of the halophilic bacterium Bacillus, a salt product found in salt marsh. The purple source of this cell membrane is called the bacteriorhodopsin component of the retina. The amino acid in the cell membrane channel is strongly bound to the retina, while the retina and amino acid in the dissolved state do not bind and appear pale yellow. When two sets of lasers of different wavelengths are alternately irradiated onto such a protein molecule, this can be achieved. Protein molecules switch back and forth between purple and yellow structures. Its film can also change the color according to the conversion of the external electric field. In the conventional bacteriorhodopsin, under the influence of different electric fields, it will change from blue to light yellow. By sandwiching the protein film in a transparent plate combined with a large number of electrodes, a display plate can be made. When a suitable voltage is applied to different parts of the film, it is possible to "write" a page of a document or "place" an image. Just like ink, images on the bacteriorhodopsin display can also be seen under normal light. At present, the main difficulty facing the entire development work is the need to consume hundreds of volts of electric field to stimulate its color transformation. Researchers are working hard to conduct research in this area and expect to make breakthroughs.

5. Electron beam curing ink

Electron beam curing ink is an ink that can rapidly transform from a fluid to a solid state under the irradiation of a high-energy electron beam, which is also called EB ink. This ink saves energy when used, contains no solvent, no solvent volatilizes, no pollution to the environment, substrate, small curing space, high processing speed, high yield, small dot gain, good imprinting brightness, and wear resistance And resistance to chemical erosion and other advantages, so this ink has been greatly promoted and applied in recent years.

In addition to the above-mentioned several representative environmental protection inks, there are many other new environmentally-friendly inks that are being researched and developed. I believe that in the near future, there will be more and more types of environment-friendly inks.

Second, security ink

The impact of counterfeit and shoddy goods on the current market has become a major international hazard. Adding special functional materials (such as fluorescent materials, thermochromic materials, etc.) to printing inks for general printing has the advantages of low cost and easy inspection. , The market capacity is larger. Security inks have the following security features:

The first is the use of mechanical methods (force-induced deformation, force-induced heat, force-induced vocalization, etc.), such as force-induced discoloration and anti-counterfeiting labels. The outer layer of special functional materials is microcapsules [2] and the inner layer contains dyes. Normal ink mixing, printing, testing only need to force the label surface, due to external force, the capsule rupture to release the dye, the color changes immediately, capsule dye color can be arbitrarily chosen to obtain a variety of anti-counterfeiting effect.

The second is the use of thermal methods (thermochromic, thermochromic). For example, thermochromic materials are added to the ink. If the ambient temperature changes, the color will change accordingly to achieve the anti-counterfeiting effect.

The third is the use of electrical methods (electrochromism, electroluminescence), such as electrochromic inks, which add some functional materials (such as tungsten trioxide, conductive polymers, etc.) to common inks when DC voltage is applied to them. A change in the structure of the functional material will cause the ink to change its appearance color.

The fourth is to use optical methods (photochromism, photoluminescence, invisible discoloration) to print invisible or colored anti-counterfeiting graphics on corresponding materials. For example, the fluorescent ink coated on the banknote substrate is a fluorescent material added to ordinary ink. When the ultraviolet light is irradiated, it will radiate visible light to achieve anti-counterfeiting purposes.

Fifth, according to the needs of customers, the use of anti-counterfeiting ink formulas with special merchandise brands, with the uniqueness of strong, can be characterized by security ink products to achieve the purpose of product protection.

Third, electronic ink

Electronic inks contain charged liquid ink particles, which make it possible to electronically control the position of printed particles in digital printing. It has extremely small particles (1-2 micron), allowing printing to achieve higher resolution and smoothness, making images The edges are sharpened to form an extremely thin image layer. At the same time, the electronic ink is dried instantly when it is transferred to the substrate, and no emission is caused. The pigment particles of the electronic ink are dispersed in the plastic resin, which will prevent the chemical components of the pigment from being oxidized or affected by moisture, and will not fade under light irradiation.

Fourth, the application of nanotechnology in ink

Nanotechnology is a high-tech that was born in the late 1980s and has rapidly emerged. Its basic implication is to understand and transform nature within the nanometer range, and to create new substances and changes through the direct manipulation and arrangement of the laws and characteristics of atomic and molecular movements. Technical methods to enhance the functional properties of the original material. This means that people can produce extremely pure materials and a variety of new products. At present, the use of modern science and technology, in the ink manufacturing process, adding 3% to 5% and a small proportion of nano-pigment, that can improve the ink's shading rate, saturation, anti-rotation, water resistance and other issues. Nowadays, nanometer inks have a wide range of applications, such as nano inkjet inks, coatings, and optoelectronic displays.

Source: Ink Information