Research and development of the most popular water

Research and development of anhydrous offset printing inks

anhydrous offset printing plates have a history of 25 years from the publication of Driography by 3M company in the United States to the launch of "Toray levelless version" by Toray company in Japan

I. Development Status of anhydrous offset inks

compared with the first and second generation, the third generation of anhydrous offset printing has used low viscosity anhydrous offset printing inks. In addition, printed matter is no longer thick ink film printing, but thin ink film printing like ordinary offset printing. Other printing operability and stackability are also basically the same as ordinary offset printing. The improvement of sheet fed and web printing machines in improving printing speed and automation is endless, but the impact of printing speed on Printing suitability is far beyond the expectation of printing machine designers, especially on ink transfer

1. sheet fed waterless offset printing ink "Dry-O-Color artis"

on the basis of maintaining the gloss and dirt resistance of the product, the "Dry-O-Color artis" introduced five years ago has improved the ink's transferability, inking, fixation and post-processing adaptability, and is more suitable for the requirements of high-speed, multi-color sheet fed waterless offset printing machines

(1) design idea. After reaching the low viscosity and low viscosity required by high-speed printing, special additives must be used to further control the dirt resistance; To maintain viscosity and viscosity, we can only further improve the fluidity of the ink to improve the transferability of the ink. The specific methods are:

① in order to improve the dispersion of pigments, high solubility resin binder should be used

② in order to maintain the dirt resistance, non aromatic solvents that can quickly diffuse the lipophilic resin of the printing plate and the silicon layer of the non image part should be used to develop new binders

(2) ink characteristics. Under the condition that the viscosity and viscosity of the ink are almost the same as that of the original product, the fluidity of the ink is increased by about 15%, and the transferability of the ink is increased by about 10%

(3) market evaluation. Good gloss and fast fixation; Close to the quality of water offset printing; It has the printability equivalent to that of ordinary offset ink; Ink coverage has also been improved. A few users put forward their opinions: the overprint of ink is about 5% lower; Color reproducibility is not completely consistent with water printing; The field density is slightly worse than that with water offset printing

2. Thermosetting anhydrous offset printing ink for high-speed rotary offset printing machine

compared with sheet fed printing, web rotary offset printing increases the printing speed by about 2 times, and has higher requirements for ink fluidity and slightly lower requirements for viscosity. Using the same resin design method as Dry-O-Color artis, it is also suitable for rotating anhydrous offset printing ink, that is, without reducing CT (paste generation index), using binder to improve ink fluidity, so that the ink can obtain good transferability during high-speed printing

II. Research on anhydrous offset printing inks

anhydrous offset printing plates are composed of an oleophilic resin layer and an oil repellent silicone layer. For anhydrous offset printing inks, the most important properties are dirt resistance, ink transfer and ink inkability

1. development points of anhydrous offset printing ink

(1) development towards low viscosity and high fluidity

due to the improvement of matte coated paper and recycled paper and the increase in the amount of paper, in order to improve production efficiency, the printing speed continues to increase, followed by the occurrence of paper roughening and printing plate ink stacking. Waterless offset printing does not use fountain solution. Compared with water offset printing, the viscosity of ink on the paper is higher, which is more prone to galling and ink stacking failures. Therefore, the low viscosity and high fluidity of ink are the key to ink technology innovation

the use of high polymer and highly soluble new resins plays an effective role in obtaining low viscosity and high fluidity inks, which can be crosslinked by low viscosity resins without damaging fluidity. In the process of resin crosslinking, the polymer will have a like structure, and the internal cohesion will increase, resulting in the increase of viscosity. If aluminum chelate gelling agent, it will lead to the loss of ink fluidity. Therefore, a heating polymerization resin composed of rosin modified phenolic resin and oligomer with long molecular chain is proposed to make the resin quantitative and plastic, so as to obtain a resin binder with low viscosity

(2) improve the ability to wash hands frequently, exercise more, go out less, and do a good job of self dirtiness

the ability to resist dirtiness is expressed in CT, which is related to the viscosity, viscosity and fluidity of the ink, which is directly proportional to the viscosity, viscosity, and inversely proportional to the fluidity. Therefore, it is not easy to design high CT ink with low viscosity, low viscosity and good fluidity (high-speed printing). Waterless offset printing should not only achieve low viscosity, but also have dirt resistance. Therefore, the key problem in the formulation design of waterless offset printing ink is how to prevent the printing plate from dirt. Generally speaking, dirt resistance is closely related to ink viscosity, solvent used, printing field density, printer structure, printing speed and other conditions

(3) improve inkability

soybean oil ink is an environmentally friendly ink that replaces organic solvent ink. Compared with high curing ink or anhydrous offset ink, its curing speed is slower. However, from the practical results, the ink has good transferability, good inkability in the field part, and even ink color in the bright part

after the ordinary offset printing ink reaches the paper, due to the fast penetration of the solvent, the ink film will be broken near the paper surface, while the soybean oil ink will be broken closer to the blanket side due to the slow penetration, which is equivalent to transferring the thicker ink film to the paper surface, so the ink transfer amount is increased

(4) improve ink transferability

there is a certain relationship between ink properties and color development, that is, the higher the viscosity and viscosity of the ink, the lower the color development; The smaller the fluidity, the lower the color development. In order to obtain high color development, it is necessary to improve the transferability of ink, so oil

ink must have low viscosity, low viscosity and high fluidity

dirt resistance and ink transfer cannot be taken into account. How to keep a balance is the key to the design of waterless offset ink

2. Developed new products and features

aiming at the problem that the time to maintain color is longer than that of wood at the same time, ink manufacturers have developed a series of products based on the actual printing conditions

(1) because the ambient temperature of waterless offset printing should be as low as possible and kept at a constant temperature. Therefore, ink manufacturers are fully committed to the development of low viscosity and non paste ink series

(2) due to the business characteristics of waterless offset printing, many kinds of inks are needed. Therefore, spot color inks, special inks, synthetic paper inks, special inks and other inks have been developed

sheet fed waterless offset printing ink has the characteristics of good fluidity, low viscosity and soft bones while maintaining the same dirt resistance as the original product. It has been tried by many companies, and Heidelberg company has also printed on quickmaster d146, proving that it has been greatly improved in inking, fluidity, dirt resistance, gloss and wear resistance of ink film

3. Anhydrous offset printing ink for web printing

in the past, due to the poor printing resistance of anhydrous offset printing plates and the covering power of printing ink, the popularity of Web anhydrous offset printing was slow. However, recently, due to the improvement of the strength of the silica gel layer in the non image part, more than 20 web offset presses have been transformed into anhydrous offset presses in Japan

in order to cooperate with the high-speed production of Web anhydrous offset printing machine, the ink needs to have low viscosity and high fluidity resistant to high-speed printing, so as to obtain good ink transfer, inking and dryness, and prevent ink pollution. Among them, the self-adhesive resin technology developed by Japan is particularly noteworthy

due to its large molecular weight and many cross-linking points between molecules, self-adhesive resin can obtain a binder with strong gelling elasticity without using metal chelate gelling agent. The ink with this kind of binder used in "street shoes" has lower viscosity than the ink with resin binder, so it can not only maintain high speed, but also avoid paper fuzzing. In addition, its viscoelasticity is less affected by temperature, which can reduce the dirty problem caused by the temperature rise of the printing machine during long plate printing, showing the advantages of high-speed printing. Aromatic free inks using this kind of resin have been used in production, which will undoubtedly promote the development of web paper waterless offset printing

4. UV anhydrous offset printing ink is developing towards low viscosity

UV anhydrous offset printing ink is characterized by fast drying and strong dry ink film. Similarly, UV curable inks are also improving from high viscosity to low viscosity. After meeting the requirements of paper printing, they are expanding to the field of film printing (PP, PC, PVC, PS, synthetic paper, cards, etc.)

III. fully develop aromatic free inks

the composition of anhydrous offset printing inks is the same as that of aqueous offset printing inks, which is made by dispersing rosin modified phenol resin, dry oil, petroleum solvents, pigments, etc. into the binder. After meeting the various printing suitability requirements of anhydrous offset printing, for the sake of environmental protection, environmental protection and safety have been taken as an important topic in the manufacturing of anhydrous offset printing ink

after more than 20 years of development, waterless offset printing has been widely recognized by the industry with the progress of inks, plates, printing presses and peripheral materials. In the 21st century, many countries with advanced industry praise it as an environmental protection technology, which has made more remarkable progress

some users said that although the price of waterless offset printing is high, it can be made up for by improving production efficiency. Therefore, in order to expand this technology, the suppliers of anhydrous offset printing plates, inks and equipment should work together to further improve productivity, promote the unmanned and centralized management of printing, and build a new technology development environment

although Japan, the United States, Europe and other countries and regions currently have no national requirements for building energy conservation and building fire prevention, the number of water offset printing machines is less than that of ordinary water offset printing, but under the situation of increasing environmental protection calls, many parts of the United States have actively recommended to try water free offset printing, which is noteworthy

at the same time, in order to obtain the same printing quality as water offset printing, the improvement of anhydrous offset printing ink and its related equipment is also inevitable: reduce the amount of waste ink caused by skinning (sheet fed ink); Reduce VOC (volatile organic compounds) in ink; Reduce the content of aromatic components in the solvent; Improve the dirt resistance, inking and hiding power of the printing plate

keyword: waterless offset/ink