Selection of printing ink for the hottest heat shr

2022-09-22
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Selection of heat shrinkable film printing ink

type of heat shrinkable film printing ink

heat shrinkable ink needs to have strong adhesion, flexibility, considerable heat resistance, and the pigment in the ink cannot change color or fade under high temperature. This kind of ink requires better performance than other inks in all aspects

the market development director of Nobel ink company believes that at present, there are four kinds of inks that can be used for printing heat shrinkable materials: solvent based inks, water-based inks, cationic UV inks and free radical UV inks. Solvent based inks currently account for the largest market share, followed by water-based inks

it needs to be added that the reason why cationic UV ink cannot be widely used in the field of heat shrinkable film printing is mainly because its price is too high. Moreover, compared with free radical UV ink, cationic UV ink is more "difficult" to print. Free radical UV ink is not only relatively cheap, but also simple to use, eliminating the cumbersome preparation work like cationic UV ink

solvent based inks are still the most used in the heat shrinkable label market. At present, large companies are still the main customers in the heat shrinkable film market, and large companies often require large quantities and long version live printing. Now, solvent based gravure ink is the most suitable for long-term printing, which makes solvent based ink the best choice in the heat shrinkable film market. Kingsmoor packaging (KPL), a British thermoforming container manufacturer, is the best choice. However, with the development of the heat shrinkable film market, small brands and customers gradually show great interest in heat shrinkable materials, which is bound to drive the growth of inks suitable for short version live printing. At that time, suppliers and middlemen will invest in the necessary equipment to make a difference in water-based inks and free radical UV inks

how to choose

like other packaging printing, in the heat shrinkable film printing market, it is important to choose the most suitable ink for printing. First, judge the performance of printed matter in some aspects. Is it flexographic printing or gravure printing? Does the shape of the container require high shrinkage of the material? What will happen to containers during the production, transportation and sales of products? How much friction coefficient is needed? While answering these questions for customers, ink manufacturers can also better assist printers in finding the most suitable ink for product requirements

ink suppliers and agents should first consider three factors: shrinkage, adhesion and the ability to release residual solvents - the ability to dry quickly at a lower temperature

shrinkage - when selecting ink for heat shrinkable labels, the most important factor to consider is the shrinkage performance of the ink. The requirements for shrinkage vary greatly in different applications. High shrinkage requires a shrinkage of 60% - 70%, while low shrinkage requires only 10% - 20%

environmental friendly water-based ink has a shrinkage of more than 40%, great elasticity and lower cost than UV ink. Moreover, the ink surface is less affected by the movement of atoms in molecules. Free radical UV ink can cure in real time, which is inhibited by oxygen rather than moisture. Generally speaking, its shrinkage is less than 20%. In some printing materials, the adhesion is limited, and the atoms in chemical molecules may move on the ink surface. Water based inks and free radical UV inks are more suitable for materials with medium and low shrinkage

solvent based ink is similar to water-based ink, with great elasticity and shrinkage of more than 40%. The drying time of solvent based inks is less affected by moisture, but it is slightly more affected by the movement of atoms in chemical molecules. Cationic UV ink can produce good adhesion on many kinds of substrate materials, and its shrinkage is more than 40%. In addition, this ink can be cured almost in real time, and the atoms in the chemical molecules move less, but the price is also more expensive than free radical UV ink. The maximum shrinkage of cationic UV ink and solvent based ink can reach 70% - 75%, which is more suitable for applications with high probability of safety test of shrinkage scaffold fasteners

adhesion - the contact between ink layers is often encountered during printing and winding. If the ink with poor adhesion is used, the contact of the ink layer of the product 'will occur when it is piled up. The most common problem is adhesion. The ink layer adheres from one side of the material to the back of another material. Generally, if the ink cannot adhere well, the method of raising the temperature of the drying oven can be adopted. However, heat shrinkable materials are sensitive to temperature. Without the rapid growth of express industry and fast food industry, we can rely on increasing temperature to improve ink adhesion. At present, the inks with the best adhesion are solvent based inks and cationic UV inks. Due to the limitations of their raw materials, the adhesion of water-based inks and free radical UV inks has not been ideal, and improving their adhesion is also the direction of many manufacturers

residual solvent - now there are quite strict national standards for residual solvent, especially the products of some large companies. If the drying temperature is adjusted higher during the ink drying process, the solvent will volatilize faster, but too high a temperature will lead to pre shrinkage of the material. Therefore, excessive heat should not be applied to the shrink film in printing. This requires finding a balance between printing conditions and drying conditions

before printers choose the appropriate ink for a specific heat shrinkable film, they must also strictly test the compatibility between the heat shrinkable film and the ink. Generally, the lead screw column should also be oiled. The test items include adhesion, water resistance, adhesion, friction coefficient, residual solvent, etc

no matter which kind of ink sells best, and no matter how often ink dealers test the compatibility between ink and heat shrinkable materials, one thing is certain: the market share of heat shrinkable ink in the whole industry has been growing. Although the proportion is still relatively small at present, its growth rate will be very considerable in the next few years

Author: Hao Fayi, Shanghai University of technology

source: printing technology 2005, 10 (packaging and decoration printing)

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