The most popular waterless offset printing ink is

2022-07-27
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Anhydrous offset printing ink: mature under the voice of environmental protection (III)

fully develop aromatic free ink. The composition of anhydrous offset printing ink is the same as that of water-based offset printing ink. It is made by dispersing rosin modified phenol resin, dry oil, petroleum solvents, pigments, etc. into the binder. After meeting various printing suitability requirements of waterless offset printing, environmental protection and safety have been taken as an important topic in the manufacturing of waterless offset printing ink for the consideration of environmental protection

the following will describe in detail the development of aromatic free petroleum solvents and 100% aromatic free waterless offset printing inks

1. stability and characteristics of non aromatic solvents

petroleum solvents contain aromatic components, which is the reason why the first two oils belong to non-destructive testing inks have bad smell and irritate the skin. For this, the inks without aromatic solvents (AF) have been greatly improved in this regard. The solvent without aromatics has narrow distillation range and high aniline point. In terms of composition, solvents without aromatics, aromatic components are mainly cyclohydrocarbons obtained by adding hydrogen, and the content of aromatic components is very small

2. development of anhydrous offset printing ink for sheet fed paper without aromatic solvent. Aniline point refers to the temperature at which white turbidity occurs when the solvent and aniline are mixed in equal volume. The solvent with low aniline point has strong ability to dissolve the resin

the aniline point has a great impact on the ink performance. For example, if the original resin is used to produce ink with a solvent that does not contain aromatics, the solvent in the ink is easy to separate, resulting in faster ink fixation, poor fluidity, poor transfer performance, and paper roughening due to the specific differentiation of hardness such as Rockwell hardness (HRC) and Brinell hardness (HB) due to the improvement of adhesion, resulting in the decline of the gloss of the printed matter

therefore, in the components of anhydrous offset printing inks without aromatic solvents, it is necessary to improve the solubility of binders made of resins, solvents and dry oils to compensate for the solubility of solvents. In order to improve the solubility of the binder, a highly soluble solvent or alkyd resin can be used to improve it. However, the balance between viscosity and viscosity is difficult to maintain, resulting in delayed solidification of the ink on the machine and reduced drying speed

therefore, it is necessary to improve the rosin modified phenolic resin in the ink composition. For the anhydrous ink without aromatic solvent, the resin with high elasticity is more suitable from the perspective of controlling the increase of viscosity and preventing dirt due to the decrease of resin solubility. Generally, once the solubility of the resin is improved, the molecular weight and elasticity are reduced. However, after repeated tests on the composition ratio of rosin and phenolic resin, the type of phenolic resin, the degree of polymerization, reaction conditions and synthesis methods, a resin with balanced viscosity and viscosity is finally developed

according to the above design, the main features of the developed 100% aromatic solvent-free sheet fed offset printing ink are:

(1) high density design, which improves the hiding power

(2) the inkability is improved, and the point reproducibility close to that of water offset printing is realized

(3) the dispersity and uniformity of pigments were improved, and the gloss was significantly improved

(4) the fixing time is shortened, which improves the stacking property of printing products:

(5) on the premise of maintaining the dirt resistance, it achieves low viscosity and improves the fluidity

after more than 20 years of development, waterless offset printing has been widely recognized by the industry with the progress of ink, plate, printing press 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 by improving production efficiency. Therefore, in order to expand this process technology, the suppliers of anhydrous offset plates, inks and equipment should work together to build a new technology development environment in order to further improve productivity, promote the unmanned and centralized management of printing

although the number of waterless offset printing machines in Japan, the United States, Europe and other countries and regions is less than that of ordinary waterless offset printing, many regions in the United States have actively recommended waterless offset printing under the situation of increasing calls for environmental protection, 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 all related best measuring 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

source: Chinese ink

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