Ink is a colorant for printing and the main raw material for printing. Ink has a great relationship with the quality of printing, especially when the performance of the ink is not suitable for printing, it will cause a series of failures in the process, seriously affecting the normal production and product quality. The printer must change the ink Some performances can meet the needs of printing, but some process failures are not only caused by ink, but also related to other factors, so the printing operator must carefully analyze and handle it correctly.

This article first discusses the faults and processing methods caused by the ink in the printing process, hoping to help.

1. Ink stacking

Phenomenon and reason: In the printing process, the ink from the ink fountain cannot be transferred to the paper through the ink roller, printing plate and blanket, but it is piled up and lost good transmission. When this happens, in addition to the inappropriate pressure of the machine and the excessively strong rubber blanket, the following reasons are also common:

(1) The viscosity of the bonding material is not suitable, and there is not enough adhesion to transfer the pigment, so that some pigment particles are accumulated on the ink roller, printing plate and blanket.

(2) The thicker the pigment particles or the larger the specific gravity, the worse the transfer ability of the binder to it, and the less it has the ability to transfer it, so that the ink is deposited on the ink roller, printing plate and blanket. This situation is common when printing yellow ink. Because the proportion of yellow pigment in the ink is large, which can account for 75%, the heavier the pigment, the more important the connecting force of the connecting material becomes.

Yellow ink is very prone to pile up when printing

(3) The oil content in the ink is too small, and the pigment particles do not have enough binder to accumulate.

(4) The viscosity of the ink is too high or too hard, the fluidity is small, and the ink in the printing ink fountain is not easy to drop onto the ink roller. If the adsorption adhesion between the inks is greater than that of the printing plates, blankets, and paper, Then the ink will still accumulate on the ink roller, printing plate and blanket.

(5) Too much dry oil in the ink will make the ink dry on the ink roller or make the ink sticky, especially in summer or when the down time is too long, once the ink is dried on the ink roller, it will lose the transfer performance, The ink from the ink fountain accumulates on the ink roller.

(6) The texture of the paper is loose or "pulverized", so that the paper wool and powder are mixed into the ink, and stacking and rubber blankets will also be generated. Approach:

(1) Because the viscosity of the binder is poor or the pigment particles are coarse and heavy, you can add No. 0 ink or resin oil to increase the viscosity and improve the transfer performance.

(2) Because the viscosity of the ink is too high, too hard, the paper texture is loose, de-powdered, or the oil content is insufficient, you can add No. 6 ink, Kangbang, Vaseline, and Villi oil to change the ink viscosity and increase the wetting performance.

(3) Reduce the amount of dry oil (add new ink) or add some non-drying auxiliary materials appropriately.

(4) The ink pigment particles are coarse and heavy, and increasing the viscosity still cannot be solved. The ink can be rolled in the ink mill before use.

(5) After changing some properties, the ink stacking phenomenon can not be completely resolved, and it can be combined with multiple rubber wash rollers, printing plates, blankets and other methods for processing.

2. Flower board

Phenomenon and reason: The flower plate is that the dots gradually become smaller and fall off. The printing plate loses its good fat-sensing ability, which reduces the level of the printed matter and the ink color. There are many reasons for the pattern, for example, the pressure of the roller, water roller, and ink roller is too large, the water in the water bucket is too large or the water is too large, the paper sand is too large or the blanket is too hard, etc. The common pattern caused by ink is The reasons are as follows:

(1) The ink pigment particles are too coarse and too hard, and the friction on the plate surface is large. Especially at the small dots, the friction destroys the pattern ink absorption foundation and causes the flower plate. Some pigments have a slight corrosion on the plate surface, destroying the ink absorption foundation of the plate pattern, and also causing flower plates.

(2) Insufficient oiliness of the ink, weak resistance to acidic syrup, the ink layer on the basis of the pattern of the layout is invaded by the acidic syrup and causes the flower plate.

(3) The viscosity of the ink is not suitable, and the viscosity is too large. The cohesion of the ink is also large. During the transfer process, the ink layer is not easy to break, causing the remaining ink layer on the basis of the layout pattern to be insufficient and the pattern; the viscosity is too small, the ink is against the layout The adhesion of the pattern is not strong. The pattern base of the layout cannot be protected by the remaining ink layer. The pattern base is directly affected by the invasion and friction of the acidic potion to cause the pattern.

Approach:

(1) The ink has low oiliness, low viscosity, and low adhesion. It is commonly used in black ink and 915 dilute ink. You can add some 05-90 or 05-93 gloss paste to improve performance (black ink should not exceed 10%) .

(2) If the viscosity of the ink is too large, the remaining ink layer on the plate surface is insufficient and the pattern can be improved by adding No. 6 ink or Kangbang and other tack removers.

(3) Ink pigment particles are too coarse and too corrosive (such as chrome yellow ink), change the ink or crush the ink before use.

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3. Paste version

Phenomenon and reason: The layout of the layout is unclear during paste-up, the dot lines are enlarged, and the adjacent dots merge with each other, so that the ink color of the printed product is very dark and thick, and the level is reduced. The reasons for gluing are in addition to factors such as too much potion, excessive pressure of the roller, and excessive stretch of the blanket, the common reasons caused by ink are as follows:

(1) The ink is adjusted too thin, the texture is too loose, its cohesion is small, it is easy to spread outward, resulting in the expansion of dots and lines.

(2) When the ink volume is large and exceeds the amount of ink that can be accommodated in the layout, it will spread outwards and cause paste.

Fine screen printing must strictly control the ink quality, otherwise it is easy to paste

(3) The ink pigment is too coarse or the powder is too heavy, and the transfer performance of the link material is reduced, causing the dots to be deposited on the plate surface. On the other hand, because the particles are too thick, the fine mesh cannot be accommodated and expand outwards, and at the same time, the friction on the plate surface is increased, which destroys the hydrophilic property of the blank part and makes it feel fat, so that adjacent dots merge with each other and paste the plate.

(4) The weight of the ink makes the blank part of the plate feel fat and produce paste. If too much auxiliary material is added to the ink, the viscosity of the ink can be reduced, the ink quality becomes loose and the oiliness of the ink is increased, which can also cause paste.

(5) The ink accumulates on the printing plate, blocks the gaps of the dots, expands the lines, and causes paste.

Approach:

(1) The paste version of the ink is commonly found in gold and red ink, and some gum arabic can be added to the water bucket. It can also be diluted with half of each of 915 velvet oil and 05-93 brightening paste, which has good effect. Most of the paste plates that are produced because the ink is adjusted too thin and the ink is too thin can be replaced with new ink or added with some thick ink.

(2) When the ink is large, you can adjust the color of the ink to reduce the amount of ink.

(3) Reduce the amount of Kangbang and other auxiliary materials to control paste.

(4) The root cause caused by stacking should be solved from the root cause of stacking.

4. Deinking

Reasons for deinking: Deinking refers to the fact that the ink does not rotate with the ink fountain in the ink fountain, but separates from the ink fountain shaft, so that the ink inking roller and the ink leveling roller are not inked. After the ink is said, it will affect the normal ink transfer of the ink roller, so that the printing plate can not get the required ink and become lighter, resulting in different shades of ink. Common causes of deinking are as follows:

(1) The ink has insufficient oiliness and low viscosity, which cannot drive the ink to move with the rotation of the ink fountain shaft, causing deinking.

(2) The fluidity of the ink is poor, and it is not easy to flow between the ink knife shaft and the blade, which affects the ink and causes ink to be said.

(3) The ink is gelled into a jelly state, which reduces the viscosity and fluidity, and loses the printing performance, while still standing on the ink fountain causes deinking.

(4) The ink has too little oil content and too much powder, and can not transfer the pigment particles well and stay in the ink fountain to form deinking.

(5) The ink dries too fast, causes the ink fountain shaft to dry and solidify, loses the ink transfer performance, and blocks the gap between the ink fountain roller and the blade to form deinking.

(6) There are too many impurities such as ink skin and residue in the ink, blocking the gap between the ink fountain and the blade, which affects the formation of ink deinking.

(7) The acidity of the water syrup is too strong or the gum arabic uses too much ink.

(8) The page moisture is too large.

Approach:

(1) Ink roller deinking caused by ink problems, black ink is more common. The ink made from ash in oil fume is oily and will not cause deinking. The black ink with carbon powder as raw material is poor, and the deinking phenomenon occurs sometimes. You can use thinner ink to adjust the thinner. If the product image has a large contrast and the ink cannot be thinned, you can drop some oleic acid in the ink to solve .

(2) The viscosity of the ink is small and the ink filament is short. It is commonly used in light-colored ink formulated with a desalting agent. This ink is very easy to emulsify. The acid in the water hopper intrudes into the ink, corrodes the surface of the ink roller, and makes the surface of the ink roller prone The water layer, so as to drain the oil and deink, at this time, it is appropriate to add thick ink to the ink to increase the viscosity.

(3) After deinking of the ink roller occurs, the water content of the plate should be reduced as much as possible and the acidity of the hopper liquid should be reduced to remove the gum arabic liquid.

(4) The ink is too thick and too hard. Add No. 6 ink to increase its fluidity.

(5) Stir the ink fountain frequently and remove the lining and impurities in the ink fountain to prevent the ink from drying or gelling and to prevent deinking.

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5. Ink emulsification

Phenomenon and reason: Water is divided into fine droplets dispersed in the ink called emulsification. In the printing process, oil and water are not absolutely incompatible, due to the frequent contact of ink and moisture, and due to the mechanical force and other factors There will be different degrees of emulsification in participation. This phenomenon often occurs when printing yellow ink and light blue ink, and most of them occur at both ends of the ink roller. The emulsification of the ink is very harmful to the printing. It dilutes the ink color, affects the drying of the blot, produces scumming, the ink "slacks", the ink roller deinks, the blot discolors and loses its luster, the paper turns yellow or blue, which affects the quality of the product. Adverse consequences. The reason for the emulsification of the ink is mainly due to the reduced surface tension between the oil and water. In addition to factors such as excessive water content on the plate, too strong acid in the water bucket, too much resin content, and shedding of active substances on the surface of the paper, common inks The reasons for emulsification are:

(1) The acid value of the ink is too high, the surface tension at the interface between the ink and water depends on their poor polarity, the polarity of the ink is often measured by the acid value, the more free fatty acid content in the ink, the higher the acid value , The stronger the polarity, the greater the possibility of emulsification. A certain acid value can ensure the dispersion of the pigment in the ink and the adhesion of the ink during the transfer, but the excessively high acid value is the biggest reason for the ink emulsification.

(2) The water resistance of ink pigments is poor, especially the pigments for offset printing inks, which are not only insoluble in water and acids, but also have water-resistant properties, because the body materials of ordinary lake pigments are often hydrophilic powders After the dye component in the pigment meets acidic water, the dye will quickly precipitate out of the dissolved water, causing emulsification failure.

If the particles of the ink pigment are coarse, the viscosity is not enough, and the bonding with the binder during the rolling process is not strong enough, it will easily absorb moisture after contact with the acid during the printing process and swell itself, gradually detaching from the binder and causing emulsification.
(3) There are no pictures at both ends of the printing plate, and the large amount of water causes emulsification at both ends.

(4) Too much diluent is added in the ink. The commonly used auxiliary material white oil is carbonic acid, and the component of the Veli oil is aluminum hydroxide. They are all emulsifiers, so the more auxiliary materials are added, the more the ink will be emulsified. . Too much drying agent is added in the ink, and the acidity of the water bucket syrup must be increased during the printing process. If the acidity is too strong, it is easy to cause the ink to emulsify. In addition, the drying agent itself is a strong emulsifier, so the more the drying is added in the ink , The more it can cause emulsification failure of the ink.

Treatment method: It is impossible to completely solve the emulsification of ink, because oil and water will emulsify themselves under the action of machinery. A small amount of emulsification has little effect on printing.

(1) Replace the new ink.

(2) Add concentrated ink to the ink to reduce the acidity of the potion and the amount of gum arabic.

(3) Add less oleic acid, white oil and Willy oil.

(4) Reduce the amount of drier.

6. Pull paper wool

Phenomenon and reason: Pulling the paper wool means that the ink and the paper can not adapt well, and the fiber on the paper is pulled up, and the white marks appear on the pattern imprint. In addition to the slack of the paper fiber structure, the causes of brushing are as follows:

(1) The ink viscosity is too strong.

(2) The fluidity of the ink is too small.

(3) Add too much dry oil to make the ink sticky and thick. The viscosity of the ink is too large or too thick (too much dry oil, and the viscosity becomes thicker). The cohesion is greater. The tension of the ink transferred from the blanket to the paper during printing increases. (Cohesion force) Less than the cohesive force between the inks, the paper fiber structure will be destroyed and the paper wool phenomenon will appear.

Approach:

(1) The ink viscosity is too strong, you can add Kangbang, Vaseline to change the ink viscosity.

(2) The ink is too thick and poor in fluidity. It can be diluted with No. 6 ink.

(3) Too much dry oil or the ink becomes sticky and thick, it can be solved by adding new ink appropriately.

(4) After the ink has been adjusted and the paper-pulling phenomenon is still serious, it can be solved by overprinting once with white oil.

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