In recent years, due to the improvement of environmental awareness, people have increasingly attached importance to changes in the social ecological environment in production and consumption activities. Examples include gravure and flexographic printing associated with packaging. The issue of the public’s use of organic solvents for the emission of hydrocarbons that pollute the atmosphere. The response was very strong, and the call for reduction to the point where no organic solvents were used at all was one after another. Soft-packed gravure ink water as an ideal means to prevent pollution of the atmosphere. It was mentioned on a higher agenda.
It is estimated that Japan uses paper as the printing material for printing. At present, 30% of inks have been made aqueous. Non-absorbent plastic film and aluminum foil. The water-based rate is less than 5%.
In order to replace the current solvent-based ink. It is necessary to develop excellent quality water-based inks, but also to develop a printing system adapted to water-based inks. In the printing machine, dry coal way, squeegee, printing plate and printing film and its lamination methods and other efforts.
the following. First of all, I will introduce the development and technical trends of water-based gravure inks for plastic films in Japan. Secondly, we will talk about environmental counterparts in the field of offset printing inks – soybean oil inks.
Gravure ink water-based
In the early 70s of the last century, Japan started the development of gravure inks and was used in part for the printing of paper and paper products. From 1973 to 1979. The world had two oil crises. In order to save resources, it also objectively promoted the development of this work. Water-based inks are used in plastic films. Due to poor dry coal. The problem of wetting and stickiness was greater, so it was in the flexible packaging field at that time. Just stay in the exploration phase.
In the second half of the 80's, Chiba Prefecture and Saitama Prefecture issued guidelines for hydrocarbon measures and new fire regulations. Further accelerated the development of water-based inks. ]In 990 under the leadership of the Ministry of Industry. The development of high-quality water-based inks and gravure printing systems was culminated.
The ideal water-based ink, completely water-based without organic solvents. However, in order to deal with the wettability of plastic films, printing effects and drying problems. Solvent alcohol can be considered and used, but when using an aqueous alcohol solution as an ink diluent, the alcohol content should be less than 30%. The so-called water-based ink, containing less than 30% of the solvent. More than 70% water and non-volatile components.
The value of ink watering
From a comprehensive point of view, gravure ink watering can be said to be the most ideal, the use of water-based ink can get rid of organic solvents other than alcohol. Table 1 lists its value from the aspects of environmental safety, hygiene, and print quality.
According to the investigation report of the Japanese Printing Industry Association's investigation of the problem of water repellency of gravure inks, the following three main factors contributing to the realization of water repellency:
1. Poor quality of water-based ink 1 Adhesion and abrasion resistance of plastics are not strong 2 Fog of printing plates means poor printability;
3 Not as good as the printing effect of solvent ink.
2. Poor dryness 1 Low print speed, increased energy consumption and costs:
2 The original drying equipment must be modified. More space is occupied and additional noise protection facilities are needed. Correspondingly increased costs.
3. The printing plate 1 must be modified to improve the dryness. Strengthen the printing effect, printing plates should be shallow version.
2 The saved plates cannot be used and the expenses increase.
To advance water, we must overcome the above problems. At the same time, it is necessary to pay attention to the development of four technologies, namely printing machines and printing plates led by water-based inks, and plastic films, which are printed bodies, and coordinate development and advance together. An excerpt of technical elements in each related field is shown in Figure 2.
Let us first talk about the first element - ink. The requirements for the quality of aqueous inks for flexible packaging are listed in Table 2.
As a reverse printing laminated ink. It is necessary to have post-processing and post-potting sterilizing treatment suitability as a front printing ink. The ink film itself is required to have durability. Water-based inks generally consist of the components shown in Figure 2. Among these ingredients. The success of the connection material development is the key to the development of water-based ink. It can be said that it determines the basic performance of ink. Therefore, there are several requirements for the function of the waterborne resin binder:
1. Adhesion with printing plastic film;
2. Resolubility and printability
3. Non-stick pages. The formed ink film has good performance. Resistance to friction.
4. The pigment dispersion. The color of the formed ink is bright. Good gloss and high density.
In the resin. In addition to acrylic copolymers, polyesters, polyurethanes, polyamides. There are also natural resins and their derivatives with acid groups. Of course, they have their own advantages and disadvantages, and there are many problems that need to be solved.
Source: China Polymer Network
