Waterless Offset Printing Ink: Going to be Mature under the Call of Environmental Protection (III)

The composition of the waterless offset ink is the same as that of a water-based offset ink, which is produced by dispersing rosin-modified phenol resin, dry oil, petroleum solvents, pigments, etc. into a binder. After satisfying various printability requirements for waterless offset printing, environmental protection safety has been an important issue in the manufacture of waterless offset inks for the sake of environmental protection.

The following will describe in detail the research and development of aromatic-free petroleum solvents and 100% non-aromatic anhydrous offset inks.

1. Aromatic solvent-free stability and characteristics

Petroleum solvents contain aromatic components, which are the cause of odors and irritations to the skin. In this regard, inks containing no aromatic solvents (AF) have greatly improved in this respect. Aromatic hydrocarbon-free solvent distillation has a narrow range and high aniline point. From the standpoint of components, aromatic hydrocarbon-free solvents, aromatic components obtained by adding hydrogen as the main component of the cyclic hydrocarbon, the content of aromatic components is minimal.

2. Develops sheet-free waterless offset inks that do not contain aromatic solvents

Although the ink containing no aromatic hydrocarbon solvent has higher safety than the ink using petroleum solvent, the aniline point is also high, and the solubility to the resin is deteriorated. The aniline point is the temperature at which white turbidity occurs when the solvent and the aniline are mixed in an equal volume, and the solvent having a low aniline point has a strong ability to dissolve the resin.

The aniline point has a great influence on the performance of the ink. For example, when the ink is produced from the original resin using an aromatic-free solvent, the solvent in the ink is easily separated, resulting in faster ink fixation speed, poor fluidity, poor transferability, and adhesion. Sexuality raises problems such as paper pulling, which leads to a decrease in the gloss of the printed material.

Therefore, in an anhydrous offset ink component containing no aromatic solvent, it is necessary to increase the solubility of a binder made of a resin, a solvent, a drying oil, etc. to compensate for the solubility of the solvent. In order to improve the solubility of the binder, it can be improved with a high solubility solvent or alkyd resin, but it is difficult to maintain the balance of viscosity and viscosity, resulting in delayed solidification of the ink on the machine, reducing the drying speed.

For this reason, it is necessary to improve the rosin-modified phenolic resin in the ink composition. In the case of a waterless ink using an aromatic hydrocarbon-free solvent, since the solubility of the resin is lowered, a resin having a high elasticity is suitable from the standpoint of controlling the increase in the viscosity and preventing the occurrence of dirt. In general, once the solubility of the resin is increased, the molecular weight decreases, and the elasticity also decreases. However, after repeated tests on the constituent ratios of rosin and phenolic, the type of phenolic aldehyde, the polymerization degree, the reaction conditions, and the synthesis method, the viscosity was finally developed. Resin with a balanced viscosity.

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

(1) High density design improves hiding power;

(2) Improved ink repellency, achieving reproducibility of dots close to water offset;

(3) The dispersibility and uniformity of the pigment are improved, and the gloss is significantly improved;

(4) The fixation time is shortened and the accumulation of printed materials is improved:

(5) Under the premise of maintaining anti-compaction, low viscosity is achieved and fluidity is improved.

After more than 20 years of development, waterless offset printing has been widely recognized by the industry for its advancement in inks, plates, printing presses and peripheral materials. In the 21st century, many industrially advanced countries have promoted it as an environmentally friendly technology and have made more remarkable progress.

Some users have indicated that waterless offset printing, though with high labor prices, can be compensated for in terms of increasing production efficiency. Therefore, in order to expand this process technology, waterless offset printing plates, inks and equipment providers should work together to further increase productivity, promote unattended and centralized management of printing, and build a new technology development environment.

Although the number of waterless offset presses in Japan, the United States, Europe, and other countries and regions is not as large as that of ordinary offset presses, the environmental protection calls have become increasingly high. Many regions in the United States have actively recommended waterless offset printing. This is It is noteworthy.

At the same time, in order to obtain the same printing quality as offset printing, the improvement of waterless offset inks and related equipment is inevitable: reduce the amount of waste ink due to the crust (sheetfed ink); reduce the VOC in the ink (Volatile organic compounds); Reduces the content of aromatics in solvents; Improves offset resistance, ink repellency, and hiding power of printing plates.