Aluminum Foil Printing Difficulties (Part 2)

3. The medium-drying time is the key to the quality of the ink layer conjunctiva. The so-called medium-drying time refers to the intermediate stage of the ink layer from the fixation to the conjunctiva. The time is about 3 hours. The phenomenon is similar to the conjunctival matter state, and there is a smooth and smooth feeling, but it cannot be rubbed hard. At this level of medium-term drying, it is known that the "solvent" completely escapes from the system, and that the dry vegetable oil has undergone oxygen-absorbing polymerization and gradually changes to a gel-solidified state; finally, the dried conjunctiva is completely dried. This is the key to benign conjunctiva.
4. Obviously, in order to infiltrate, there must be substrates with absorbing properties. However, the aluminum foil on the surface of aluminum foil does not have such conditions.
Absorption of aluminum foil, whether it is the use of offset ink, or "special" ink, aluminum foil remains in the liquid solvent. Such an ink layer is not only the main factor in the stickiness of the printed product, but also the source of poor dryness. Therefore, in order to overcome the difficulties of the ink stickiness and dryness of the printed products, it is necessary to change the ink permeation method and improve the fixing conditions.
Analysis of the difficulties in printing aluminum foil At present, the difficulty in printing aluminum foil on the offset printing press is mainly due to the two major drawbacks of stickiness and dryness.
1. The stickiness and dryness of the printed product are the surface phenomena of the internal factors of the ink. The viscosity and dryness of the ink are the same as those of the maternal. The viscosity and dryness of the ink are compatible with each other in the oil structure and other properties. In the printing process, it can not only exert its adaptability and stability. Sex effects can also have adverse effects on the chain reaction.
2. It is believed that adding more desiccant (dry oil) will solve the problem and it is actually wrong. Desiccant application requirements are more complex, not only quantitative factors, species factors and application technology factors, but also the constraints of the workshop's temperature and humidity, speed, medicine, ink, substrates and printing products. It is one of them. Another important factor is the desiccant's object and role in the ink system. In short, desiccants act on dry vegetable oils, but not on ink oils. Because the dry vegetable oil has the function of oxygen absorption, it can make the resin and the resin from the liquid state to the solid state in the process of oxygen absorption. The role of the desiccant is to shorten the process. The ink oil has no such conditions, so the desiccant does not work for it, especially aluminum foil printing.
3. Offset printing machine aluminum foil products, in the oil in the appropriate and appropriate use of some desiccant can play a corresponding effect. However, if the dosage is too much, it will “reverse the product” and change to the opposite direction. It can not only achieve the purpose of increasing the speed of fixing and the timeliness of dryness, but also leads to dryness, dryness, and dryness of the oil in the printing process. Or even unable to print. In addition, even if the above phenomenon does not occur, the viscosity of the ink is increased in the printing process, and even if the aluminum foil can withstand the maximum degree of stickiness, the stickiness factor has been increased in this case.
Performance and Application of Aluminum Foil Printing Aid In order to solve the difficulty of aluminum foil printing, Zhengzhou Guancheng Printing Material Factory has developed a kind of aluminum foil printing auxiliary, named “Liquan All-Paste”. At present, after the printing factories in different regions have a good trial response, it is proved that it is an excellent additive for solving the difficulties in aluminum foil printing and has practical value, so it is introduced and promoted.
The basic properties and performance of the "print paste" are mainly designed for lithographic offset printing presses, medium and high-grade resin offset printing inks and printed aluminum foil paper. It is based on the status quo of aluminum foil printing, focusing on the application of inks, finding out its evolutionary laws from the connection of physical phenomena and chemical phenomena, and adopting corresponding measures on the physical properties and chemical properties of the printing paste, so that In the ink blending combination, an inductive factor is generated, and the ink is induced to change in a favorable manner. In the entire stroke of the printing machine, the aluminum foil paper is engraved in an instant until all drying processes, and the following effects are produced:
1. Regulates the rheological adaptability of the ink in the printer stroke, inhibits the ink from drying in the middle period, and maintains the benign transfer and transfer of the ink.
2. In the thermal action of the stroke, the ink gradually releases and volatilizes most of the low-viscosity phase “solvent”, and the ink gradually changes in viscosity and thickens, and the adhesion is enhanced until it is transferred and embossed on the aluminum foil paper. The ink at the moment has appeared larger. Quality, but due to the effect of the printing paste can still be protected ink line parts clear, imprinted edge integrity, field service, full print quality.
3. Enhance the force between the ink and aluminum foil surface molecules (secondary binding force) and accelerate the fixing speed of the ink layer.
4. Immediately at the moment when the inner layer is fastened, the paste immediately produces a stick-proof effect.
5. Because the high-speed fixing of the ink layer creates a good condition for the medium-term drying time, it has sufficient physical changes in the middle of the film formation. Therefore, after the ink layer is completely dried and filmed, there is no phenomenon of anti-adhesion and quality.
To sum up, this paste is mainly aimed at the two major difficulties existing in the printing of aluminum foil, namely, the stickiness and dryness of the printed product. In order to effectively resolve these two difficulties, the following points should be taken into account when using full-color printing paste:
1. Paste is mainly applied to offset press. Printing machine type, machine speed is not limited, from a monochrome machine to a six-color offset press can apply. In addition, it can also be used for aluminum foil products printed by letterpress printers and stickers printers.
2. Paste is mainly used for resin-based fast-setting bright offset inks and resin-based fast-drying (fast-fixing) offset inks. In addition, "special ink" can also be used.
3. Due to the quick dryness and sensitive condition of the dry functional properties of the ink paste, it is necessary to apply them according to the actual situation in each area. When using the ink as 100%, the proportion of ink added to the ink should be controlled between 8% and 9%. When you have not obtained the best data, you can start with 8% and gradually increase the amount. The best data verification standards are: first, no early drying occurs on the printing press; second, fast fixing speed and good anti-cooking effect; third, the medium-term drying of the ink layer is timely, and the subsequent drying is complete, and the quality of the conjunctiva meets the requirements.
4. To use this seal, avoid using any accessories, especially anti-adhesives, de-adhesives and varnish.
5. If the ink's song consistency is too large, and thus affects the ink's fluidity and ink repellency, it may be appropriate to add some ethyl acetate to adjust the ink, but avoid adding high boiling point kerosene.
6. The use of this paste, generally no longer add desiccant, under special circumstances can add a little dry oil, but should be mixed red and white kerosene, the ratio of: red dry oil 1% to 1.5%, white dry oil 1.5% ~ 3 % (reference volume).