Use water-based oil black to reduce costs

Recently, the environment around the packaging industry is rapidly changing. Although there are various issues such as the container packaging and recycling method and the problem of dioxide, as well as the reduction of packaging materials, it is a bit advanced. If we do not consider the global environment, we cannot achieve the development of the gravure printing industry. According to this view, , Let's talk about the effect of water-based ink on gravure printing.

The difference between oil ink and water ink

The types of inks currently used for gravure printing can be roughly classified into oil inks and water-based inks. The difference lies in the solvent used. Oily ink means that the solvent is an organic solvent, while the water-based ink uses water and alcohol. The so-called organic solvent is a generic term for solvents using nine chemical substances such as toluene and ethyl acetate. In other words, the difference between an oil ink and an aqueous ink is the difference in the chemicals used in the solvent (see the attached table).

Scheduled oils and water-based ink chemicals

Oily ink
Water-based ink
Toluene, Xylene, Ethyl acetate, n-propyl acetate, Methyl ketone, Methyl isobutyl ketone, Isopropanol, Ethanol, N-propanol Ethanol, n-Propanol

So what are the differences in chemical substances that will affect the printing process and flexible packaging? In appearance, due to the water-based use of water-based inks, apart from the overall clarity, it seems that there is no other difference. In addition, in terms of flexible packaging, the printing surface is a three-layer structure that is made of a plastic film and is like a sandwich.
The printing part does not directly touch the contents. Therefore, printing with oil-based ink does not seem to be a problem. However, the organic solvent is composed of a very fast-selecting chemical substance. The little solvent in the ink penetrates through the film and penetrates. Out of the bag or inside the bag. When we open the snack bag, we often smell the unique odor, which is the odor of the organic solvent (chemical substance) that has penetrated. The chemical substances used in oil-based inks almost all have special irritating odors. Today, the solvent that fills the bag is called residual solvent. And the presence of this residual solvent is a very big headache for oily inks.

In addition, in the aspect of gravure printing, in order to dry the ink, it is necessary to promote the volatilization of the solvent, and this volatilized solvent is discharged outside the factory through a pipe. That is, chemicals are dispersed into the atmosphere. This discharged solvent is much larger in amount than the remaining solvent.

In water-based inks, the solvent basically uses only water and alcohol, and it has attracted attention as a means to solve the above-mentioned various problems.

Water-based ink features

When oily ink is used, the depth of the recessed hole of the roller is about 30 μm, but the depth of the recessed hole can be 12 to 15 μm for the shallow version of the roller for aqueous ink. Therefore, as long as the water-based ink is successful, it is equivalent to reducing the coating amount of the ink. After testing, the coating amount was reduced by about 10% as compared with the oil ink. In addition, the printing plate for the aqueous ink was lighter in color and used darker ink, and the reproducibility of the ink color was better than that of the oil ink. The faint tone is also clearly visible, so the interspersed colors present a subtle color reproduction. However, depending on the process design, depending on the process design, it is also feasible to rely on the CMYK for color development. However, the occasion of gravure printing is easy. Caused by mistakes, there will be a special phenomenon of edge halo. Therefore, it is difficult to solve everything in the platemaking process. The amount of alcohol in the solvent is preferably up to 40%.

With regard to the price of water-based inks, the price has decreased due to the recent increase in usage. Manufacturers of water-based inks have also increased, and prices will be reduced in the future.

Of course, water-based inks also have drawbacks. Compared to oil-based inks, solvents require slower drying of the solvent itself and require longer drying times. Extended drying time is equivalent to slowing the printing speed. In addition, when using water-based ink, it is necessary to improve the original equipment or cause a new corresponding model. In addition, the use of water-based ink for gravure printing, the abrasion of the squeegee and the surface of the roller is the biggest topic, and therefore, electrical power is the key. For the roller used in flexible packaging, it is preferable to connect the electroplating line with a robotic engraving machine. In this way, the productivity of the printing plate can be increased by a factor of 2, and since the production system can accomplish the plate making task of the water-based ink and the oil-based ink, the plate-making cost can be reduced. Regarding the number of lines, in the case of water-based inks, spot colors are 225 lines and colors are based on 250 lines. With regard to the reproducibility of photography and text, mechanical engraving is not as good as laser. Engraving can make the realm between the pits carved out clearly, so the image gets a vivid reproduction; the laser is etched by chemical technology. The laser seems a bit blurry compared to the two, but it's all about personal preference.

Laminated water based

Whether the ink is merely water-based or if the solvent is used when laminating, it goes without saying that laminating organic solvation is currently being investigated. As a matter of fact, three types can be considered: heat-sensitive, water-based dry, and solvent-free drying. No result has been approved yet, but many manufacturers pay attention to dry heat. It is believed that efforts in machinery and resin can be synchronized with gravure printing machines, which will undoubtedly greatly increase productivity.

However, water-based inks are more difficult to achieve the desired lamination strength. The principle of printing layer and plastic film bonding, simply put,
That is, mutual molecular bonding. The film is made of petroleum, ie, "oil," while the aqueous ink is "water." Water and oil and can not be mixed. In other words, when water-based inks are used, they are laminated by adhesive force, but their strength is weaker than that of oil-based inks. Sometimes there is a partial unsealing in the sealing part of the bag, like a jelly lid, etc. The transparent cover still remains on when opened. In addition, things that require high temperatures, things that require tear resistance, and the like are also more difficult to adapt to aqueous inks.

In summary, the use of water-based ink gravure printing is not only a matter of printing, but also takes into account plate-making factors can be established, some Japanese printing plants to change the use of water-based ink as an opportunity to take technical transformation results, so that all Processes have been effective in reducing costs.

Water-based inks are no worse than oil-based inks in printed products and finished products. At present, there are still funds that need to be invested in retrofitting technology. Therefore, it is not always possible to require the use of water-based ink in an environment. However, from the perspective of environmental protection, it is necessary to gradually increase the water-based ratio.