The Trend of Toluene-free Printing of Gravure Ink (2)

3.3 The advantages of no toluene

The measured values ​​of the residual solvent when printing on a film using a toluene type ink and a non-toluene type ink are shown in Table 3. As can be seen from Table 3, the non-toluene type ink has a much lower residual amount of ink solvent than the toluene type ink. In particular, toluene that does not have problems in terms of safety and hygienic properties is not used. In addition, the work environment can be improved by converting from a toluene type ink to a non-toluene type ink. In the month of 1995, the operating environment was classified into the first type or the second type of management, and when it was measured in November 1995, it was managed according to the third type of management method. In order to improve the working environment, necessary measures were taken. Later, due to adoption, With no toluene-based inks, management of workplaces is back to being managed according to Category 1 or Category 2 management methods, and the improvement of the operating environment is obvious.

The health effects are also outstanding. The medical examination data obtained during the use of the toluene-type ink (November 1995) and the use of the non-toluene-type ink (March 1996) proved that the health status of the operator has greatly improved.

The above results show that non-toluene inks play a significant role in safety and hygiene as well as improvement in the operating environment.

3.4 The disadvantages of non-toluene ink

Non-toluene inks have a variety of problems at the initial stage of their listing, such as plate fog, embossing roller scumming, poor tone reproduction, and so on. Through the improvement of the ink and the exploration and improvement of the squeegee used, it has now reached the same level as the use of toluene-based ink, and the quality has been improved. However, because toluene is the cheapest solvent in gravure ink solvents, non-toluene inks cost more than toluene inks. The cost of the ink and the dilution solvent also increases when the solvent of the ink is changed to other solvents. Today's development of printed material products is to meet low-cost requirements, but it is difficult to achieve the same low cost as toluene-based inks for non-toluene inks. As such, the use of non-toluene inks does not solve all the problems.

Compared with previous inks, there is great hope for non-toluene inks in terms of safety, hygiene and working environment. With the implementation of the PRTR method, it can be said that the non-tolueneization of gravure inks will continue to progress in the future.

3.5 Water-based Gravure Printing

Water-based gravure ink is not the latest topic, but a topic that has continued from the past. The use of water-based inks for papers, cartons, and other permeable substrates has begun to enter the practical stage. Water-based inks have indeed made progress in this area; and for water-based inks and solvent-based applications in the flexible packaging field where plastic films are used as substrates for printing. Compared with ink, the quality is not the best due to the higher cost, so the promotion progress is slow.

No organic solvent is used at all, and it is of course ideal to use inks that use water as the main solvent to print products that meet the requirements. However, in consideration of the permeability of the plastic film and the drying problem, the actual use is made by adding alcoholic organic solvents. The method to meet the practical requirements of the water-based ink.

The regulations for the use of aqueous solvent inks containing alcoholic organic solvents can be found in the guidelines for the use of gravure printing materials in Chiba Prefecture and Saitama Prefecture, as well as the regulations concerning gravure printing in Osaka Prefecture. These regulations stipulate the use of low-pollution materials and set standards accordingly.

Although in the past reference to the solvent-based ink standard, a lot of research and improvement was made on the quality of soft-packaged water-based inks, there is still a gap between solvent-based inks in terms of printability, printing effects, and material property standards.

In addition, the use of water-based inks on existing printing equipment makes it difficult to ensure the same quality and the same cost as the use of solvent-based inks. In order to realize the practical use of water-based inks, it is necessary to reform the printing presses, in particular to expand the drying equipment, and to realize the shallow version of printing plates, and investment in waste water collection and treatment facilities is indispensable. However, as a response to reduce the residual organic solvents in food packaging and meet various gravure printing regulations, water-based is a very effective means. In the field of flexible packaging, all products use water-based inks, which is difficult for now. However, it is very useful for printing on some products. The current evaluation of the practical application of water-based inks for flexible packaging is positive and is being applied to some products. Not only Japan but also Europe and the United States have included water-based inks in their development plans.