Ink Printing Full Analysis Of Plastic Packaging Bags
Author : wing Update Time：June 18, 2024
【 Abstract 】 :
Ink ink is water-based ink, also known as water-based ink. The fundamental difference between typical ink and traditional solvent-based inks is the use of water (or water and very little co-solvent - alcohol substances) to replace the organic solvent in solvent-based inks to prepare water-based linker, the linker and color (pigment or dye) and specific additives to prepare the ink can be called ink. Today, Goolien Packaging, a professional flexible packaging manufacturer, will analyze for you what is ink printing of plastic bags.
Ink ink is water-based ink, also known as water-based ink. The fundamental difference between typical ink and traditional solvent-based inks is the use of water (or water and very little co-solvent - alcohol substances) to replace the organic solvent in solvent-based inks to prepare water-based linker, the linker and color (pigment or dye) and specific additives to prepare the ink can be called ink. Today, Goolien Packaging, a professional flexible packaging manufacturer, will analyze for you what is ink printing of plastic bags.
1. Advantages of water-based ink
Compared with traditional printing inks, ink linking materials should contain only water and no volatile organic compounds. Therefore, compared with traditional solvent-based inks, ink painting shows a series of advantages, which can be summarized as follows:
① Good environmental protection
During the printing process, ink only emits water vapor and does not emit any volatile organic compounds. The printing site and the surrounding environment are not polluted by toxic and harmful organic solvents, and the environmental protection performance is superior.
② Good health and safety
There is only water in the ink connection material without toxic and harmful organic solvents. In the printed product, there is no residual organic solvent. Therefore, compared with traditional solvent-based inks, ink printing has better health and safety;
③ Production safety is improved
There is only water in the ink connection material without flammable and explosive organic solvents, and the storage of ink warehouses and production workshops will not cause combustion, explosion and other accidents because of the existence of flammable and explosive organic solvents.
④ Save resources
Ink printing is different from solvent-based inks. In the drying process of printing, the emission to the atmosphere is only a rich source of cheap water vapor, rather than a precious resource in the lack of industrial sources - organic solvents. Therefore, from the perspective of saving resources and conducive to sustainable human development, the use of ink printing instead of solvent-based ink printing is also very beneficial.
Typical examples:
A gravure printing machine with a width of 1m and a printing speed of 300m/min, printing plastic film, the effective running time is 20h per day, and the printing film is 360,000 square meters; The average ink consumption of gravure printing process is 7gsm (wet ink), and the ink consumption is 25200g, that is, 2.52t; In the gravure process, solvents need to be added to adjust the viscosity of the ink, and the conventional ratio is 1.5 to 2.0 of the ink (that is, 1kg of ink needs to add 1.5-2.0kg of solvent).
If we calculate according to the standard of the management level of the enterprise (that is, adding 1.5 times the solvent of the ink), in the printing process, it is also necessary to add 3.78t of solvent, plus the solvent contained in the ink itself, accounting for about 70% of the ink (1.764t), and the amount of solvent emitted by a concave printing machine in 1 day is as high as 5.544t.
The large amount of solvent emission not only wastes valuable resources, but also brings great harm to the environment, which has been considered by experts and scholars as one of the important reasons for the formation of haze weather. Therefore, the Chinese government has adopted a mandatory charging policy for volatile organic matter emissions. In addition, for food and pharmaceutical packaging materials, if the printing process, the organic solvent volatilization is imperfect, the residual organic solvent will also make the health and safety decline, endangering human health. Therefore, solvent-based ink printing does not conform to the concept of green packaging, which is not conducive to the sustainable development of human beings, and with the development of the packaging industry and the increase of production, this negative impact is also increasing.
2. Two difficulties in ink printing
①The surface tension of water is large and it is not easy to spread on the surface of the substrate
The spread of ink on the surface of the substrate is the basis for realizing printing processing and ensuring printing quality. As we all know, the surface tension of water is very large (up to 70mN/m or more), and the wettability of substrates such as plastic films with low surface tension (surface tension is only about 40mN/m or lower) is very poor, and the surface tension of the ink system must be greatly reduced to facilitate the spread of ink on the surface of the substrate. To this end, specific additives need to be selected to modify the ink and wash system, so that the surface tension of the ink and wash system is greatly reduced to a level lower than the surface tension of the substrate, in order to facilitate the spread of ink and wash on the surface of the printing substrate, and create conditions for obtaining exquisite printing effects.
The advent of a large number of high-quality surfactants has created a good condition for ink and wash manufacturers to reduce the research work of ink and wash systems. The vast number of scientific and technological workers in the development of ink painting, in order to seek ways to reduce the surface tension of ink painting, carried out long-term hard work, and finally achieved fruitful results, better solve the problem of reducing the surface tension of ink painting system, and laid a good foundation for the exquisite printing of ink painting.
② facing the problem of large latent heat of water, not easy to volatilize and dry
Under the condition that the latent heat of water evaporation is very large, the problem of how to improve the printing speed of ink painting is faced. In industrial production, the production speed directly restricts the production cost, so the level of production speed is often one of the decisive factors to determine whether a process has market competitiveness.
Comparison Of Boiling Point And Heat Of Evaporation Between Water And Partial Organic Solvents
From the data listed in the table, it is not difficult to see that the latent heat of evaporation of water is significantly higher than the latent heat of evaporation of organic solvents, and is 3 to 8 times the latent heat of evaporation of organic solvents such as alcohols and esters. Due to the high latent heat of water evaporation, the drying of ink is naturally much more difficult than the drying of solvent-based ink, and it is facing great challenges to achieve high-speed printing.
Practice has shown that only relying on ink and wash manufacturers to improve the formula of ink and wash to improve the drying speed of ink and wash, its effect is quite limited, to improve the printing speed of ink and wash, printing equipment, plate roller units and printing enterprises and other units of full cooperation. At present, although considerable progress has been made in improving the speed of ink printing, there is still a lot of work to be done to obtain the desired results.
3. Development and application status of ink painting
Since the 1960s and 1970s, some people with insight who were concerned about environmental protection and material resource conservation began to devote themselves to the research of ink painting. After years of hard work, ink printing has made great progress: many ink research and development, production enterprises of ink, its VOCs content has been reduced to less than 5%. There are high level of ink production units, the actual content of ink VOCs produced can even be lower than 1%, close to zero level; The content of benzene substances and heavy metals in ink is close to zero, reaching the undetectable level. At the same time, ink products have gradually been successfully applied in the production practice of plastic flexible packaging.
At present, in foreign industrial developed countries, ink printing packaging products are said to have reached more than 80% of printed packaging products; In contrast, domestic ink applications are still quite limited, especially ink printing such as plastic film, which is still in its infancy, and there is still a long way to go to promote ink printing.
