Printing ink common faults and solutions

Ink is a printing colorant and plays a key role in the printing production process. Dairy packaging, the use of ink, has a great influence on the quality of printing. Especially when the ink properties are not suitable for printing, it will cause a series of problems in the printing process, which will seriously affect the normal production and the quality of printed products.

The role of the ink is to render the color on the surface of the paper to truly restore the color of the original. Sometimes it is to copy the original and restore the color electronic surveillance code. During the operation, some properties of the ink must be changed to meet the needs of the printed manuscript. If ink color failure occurs in the printing process, it must be carefully analyzed and handled correctly. The following is a summary of the failures caused by the ink during the printing process and the treatment methods.

1. There are dot distortion and pattern phenomenon in printed products

When the ink fluidity is too large, the ink layer can easily cause a prize on the printing plate. Therefore, the dot enlargement and deformation tends to occur during the ink transfer process, and the original cannot be correctly reproduced when reflected in the printed product. Insufficient ink fluidity will cause the ink to spread on the printing plate and the ink layer will not spread. The phenomenon of insufficient ink transfer will result in insufficient printing of the printing plate. Therefore, the ink flowability is a key factor affecting the correctness of the printing product outlets, and is an important guarantee for the quality of printed products. Heidelberg

Solution: Correctly add printing ink accessories: If the ink flow is too large, you should reduce the amount of varnish, if the ink flow is too small, you should join the ink in the ink varnish unemployment, in order to change the flow of ink .

2. The plate appears paste version phenomenon

Paste printing is also a common phenomenon in printing. In the course of operation, there is a slight carelessness, and there will be stencil printing. The reasons for this are mostly related to the balance of ink and water. The key factor is still ink. As mentioned above, if the ink viscosity is too small and the fluidity is too large, the ink spreads easily on the printing plate, resulting in a plate stencil and an increase in the geometric size of the print. At the same time, the ink with too small viscosity and excessive fluidity will slide between the ink rollers, affecting the uniformity of ink transfer. This ink is easily emulsified with the fountain solution, resulting in imprinted CTP. In China, the ink does not transfer normally, and pigment particles are gradually deposited on the ink roller, plate, and blanket. When accumulated to a certain extent, it will cause paste. CTP

In addition, during the printing process, especially when printing products with two-color or multi-color offset printing presses, it is a “wet and wet” printing process, so that the ink of the next color group can be imprinted on the ink of the previous color group well. Packaging logistics, will add the right amount of additives in the ink to improve the printing performance of the ink, making it more able to meet the printing requirements. In order to speed up the drying of the ink, it is necessary to add an appropriate amount of desiccant. If too much film is added to the desiccant, the ink will become thick and easy to emulsify, so that the ink layer spreading on the printing plate cannot be broken from the middle during the transfer process. Most of them are piled up on the printing plate, causing electronic monitoring code of the stacking phenomenon. Under the effect of printing pressure, the dots gradually increase, resulting in stencil printing.

Solution: Make appropriate adjustments to the ink to change the printing effect of the ink. For inks with low viscosity and high fluidity, appropriate amount of original ink cartons should be added in the ink tank to reduce the proportion of the original additives, or the ink in the original ink tank should be cleaned, and new inks should be redistributed. In general, as long as the ink can be supplied normally, it is preferable to pack the container so that the paper does not peel off easily and the ink flowability is small, and the ink viscosity is appropriately increased.

For the paste phenomenon caused by the excessive addition of desiccant, we can only clean the ink used in the original equipment, and replace it with an appropriate amount of desiccant, and pay special attention to the method of increasing the moisture of the plate. To solve this problem.

3. Deinking occurs in printing

Deinking, as the name implies, Océ, is the ink can not be normally transferred, can not be normally adsorbed on the transfer roller, ink roller, uniform roller, can not rotate normally with the ink fountain, can not be adsorbed on the ink roller or after adsorption is difficult to come out Ink roller separation. Metal packaging

The reason for this phenomenon, from the nature of the ink alone, is that the viscosity of the ink used and formulated is small and the ink flowability is poor, so that the ink does not adsorb well on the ink roller and deinking occurs. The second is that the ink dries too fast or the foreign matter such as the ink skin, the residue and the like is excessively colored, so that the ink on the ink roller is solidified and the gap between the ink roller and the ink blade is blocked, so that the ink cannot be transmitted. The third is that the layout is too watery, the printing plate is not inked, and at the same time, a large amount of moisture is caused by the ink roller in the ink portion of the ink, which causes the ink emulsification phenomenon, which affects the ink transfer and the under ink effect.

Solution: According to different circumstances, should be treated separately. If the ink is mixed, some thin ink may be added to dilute it. If it is caused by the small viscosity of the ink, a suitable amount of concentrated ink may be added to the ink to increase the viscosity of the ink. If the ink is poor in fluidity, it may be added properly. No. No. oil is added to increase its fluidity; if the ink is too dry, the amount of desiccant should be reduced. When deinking occurs, the moisture in the plate should be minimized and the acidity of the fountain solution should be reduced. The ink ink should be mixed and the ink, residue and other debris should be removed.

4. White blots appear on imprints

This phenomenon is what we usually refer to as paper consumables. The main reasons for this phenomenon are the high ink viscosity, low fluidity, and the inappropriate amount of additives in the ink. If too much dry oil makes the ink viscosity increase, thicken, the ink under the mechanical pressure and paper peeling process, if the cohesion between the paper fibers is less than the cohesion between the ink, the paper fiber structure will be destroyed In the newspaper printing, there was a phenomenon of pulling paper and reflected white spots on the imprints of the prints, which seriously affected the quality of printed products. Printing accessories

Solution: If the ink viscosity is strong, you can add a certain amount of viscosity reducing agent in the ink to change the viscosity of the ink; if the ink is poor in fluidity and the ink layer is thick, you can add appropriate amount of No. 6 varnish to the ink to dilute the ink to improve The fluidity of the ink; if the manufacturer's information is too dry because of the ink in the ink, you can add a proper amount of new ink to stir to reduce the proportion of dry oil in the ink to achieve the purpose of changing the performance of the ink, so as to meet the printing requirements.

5. Ink emulsification phenomenon

Offset cannot be separated from water renminbi, nor can there be excessive water. After a certain mechanical pressure, ink and water are eventually mixed in a milky form. Water is divided into fine droplets and dispersed in the ink. This phenomenon is called emulsification. The emulsification of the ink is always present, as long as it is a proper amount of emulsification, the state of emulsification no longer expands the “Annual Report of the Printing Industry of China”, and the ink is balanced and should be harmless to printing. Vendor information

There are generally two types of ink emulsification, one is "water-in-oil", ie water is dispersed in the ink; the other is "oil-in-water", ie the ink is dispersed in water. The normal state of ink emulsification should be “oil-in-water” packaging anti-counterfeiting. This form does not expand, and it will not affect the performance of the ink. If this type is further expanded, the amount of water in the ink will increase, and it will develop into an “oil-in-water” form of ink emulsification. In the ink emulsified components, more water will be added to the screen, the balance between ink and water will be destroyed, and the ink will be destroyed. Performance is affected and ink failure occurs. Such phenomena as deinking, floral prints, dirty prints, and the like, the existence of this phenomenon has a great danger to printing. When it does, the prints will become light and lose luster. The strong acidity of fountain solution is the biggest cause of ink emulsification, and it is also related to the ink composition, such as ink pigment particles are coarse, poor water resistance, and insufficient viscosity. The physical structure and chemical structure of different varieties of pigments are also different, and the degree of acid resistance is not the same. Therefore, the degree of emulsification with water is not the same. However, the strong acid dampening solution easily absorbs moisture after being pressed into contact with the ink during printing, and generates an expansive ink by itself and gradually desorbs from the linking material to generate emulsification.

Solution: When the used ink has serious ink emulsification phenomenon, the original ink on the equipment should be cleaned, replace the new ink to adjust the amount of additives in the ink, reduce the greater impact on the ink emulsification additives, such as ink , diluents, dilutants, desiccants, etc. Beiren shares, reduce the amount of acid additives in the fountain solution, reduce the acidity of the fountain solution, control the amount of water when printing and so on. General packaging

6. The color of printed products changes

In the printing process, the phenomenon of changes in the color of printed products, in addition to the trade of ink and ink, has a great relationship with the use of ink. Large ink viscosity, easy to cause print imprint color darkening, drying speed slows down, increase the amount of ink; ink viscosity is too small, the color of printed products will also change the image processing, affecting the quality of printed products. In the process of dispensing ink, the ink should have a certain degree of viscosity in order to ensure the smooth transfer of ink in printing. According to the situation of not the same sheet, printing speed, model, etc., the viscosity requirements for the ink are also different. If the printing speed is lower than 6,000 rpm, the viscosity of the ink should be higher, and if the speed is higher than 6,000 rpm, the viscosity of the ink should be reduced appropriately. When printing screen printing version, the viscosity of the ink can be smaller. When printing the field version, the viscosity of the ink should be properly increased (because the demand for the ink volume and the ink layer thickness is different between the cable version and the field version); from the use of models For special printing, the ink viscosity of the monochrome machine should be higher, and the ink viscosity of the multi-color machine should be gradually reduced according to the printing sequence so as to avoid peeling of the ink layer of the previous color and to ensure the normal overprint of the color ink before and after. Digital Printing and Postpress

Solution: According to the type of printing products, printing speed, the use of models, the viscosity of the ink to adjust the printing version, and to maintain the consistency of the viscosity of the ink to ensure consistency of color reproduction of printed products.

7. The phenomenon of dot reduction in printed products

Dots are the smallest unit of a printed image and are the smallest unit of ink adsorption. We call it an image pixel and it is responsible for the task of transferring the color and tone of the original. The reducibility of ink to color is mainly expressed in terms of hue, brightness, and saturation of the ink. The color-rich print network publishes its color effects, mainly through three primary colors of ink, namely yellow, magenta, and blue. Dots are superimposed on the image processing several times. By changing dot coverage, colorful print effects can be expressed. In the ink transfer process, the viscosity of the ink is large, and the yield value is high, resulting in poor ink flowability, so that the ink layer is not spread on the printing plate. Even if the ink is spread under the effect of printing pressure, the printing plate dots The ink on the ink also shrinks toward the center due to the excessive viscosity of the ink, and it is not possible to fully restore the printing plate dots to the printing paper, resulting in the dot-reduction phenomenon. Paper packaging

Solution: Add some viscosity reducer to the ink to reduce the viscosity of the ink. Poor flow of ink e-commerce, the appropriate amount of adding No. 6 varnish to change the flow of ink.