Causes of Printing Failure Caused by Ink and Its Treatment

Abstract: The author analyzes the ink-induced failure during the printing process and provides corresponding solutions.

Ink is a colorant for printing and is the main raw material for printing. The ink has a great relationship with the quality of the printing, especially when the ink properties are not suitable for printing, it will cause a series of failures in the process, seriously affecting the normal production and the quality of the product. The printer must change the ink. Certain properties are suitable for printing needs, but some process failures are not only caused by ink, but also related to other factors, so the printing operator must carefully analyze and properly handle. This article first discusses the problems caused by the ink during the printing process and how to deal with it. Hopefully, it will help.

1. Ink pile

Phenomenon and reason: In the printing process, the ink from the ink fountain cannot be balanced and transferred to the paper through the ink roller, printing plate and blanket, but piled up and lost good transmission. This happens, in addition to the pressure of the machine is not appropriate and the rubber blanket and other factors, the common are the following reasons:
(1) The viscosity of the binder is not suitable, and there is insufficient adhesion to transfer the pigment, so that some pigment particles are accumulated on the ink roller, plate, and blanket.
(2) The thicker or specific gravity of the pigment particles, the poorer the transfer ability of the linking material, and the less ability to transfer it, so that the ink is deposited on the ink roller, plate, and blanket. This situation is common when printing yellow ink. Due to the large proportion of yellow pigment in the ink, it can account for 75%. The heavier the pigment, the more important the connection force of the binder.

Yellow ink printing is prone to stacking

(3) The amount of oil 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, its fluidity is small, and the ink in the printing ink fountain is not easy to get down to the ink roller. If the ink adhesion strength is greater than the printing plate, blanket, and the paper's ink absorption force, The ink will still accumulate on the rollers, plates, and blankets.
(5) Adding too much dry oil in the ink will make the ink dry on the ink roller or make the ink sticky, especially in the summer or when the downtime is too long, once the ink is dry on the ink roller, it will lose its transmission performance. The ink from the ink fountain accumulates on the ink roller.
(6) The paper texture is loose or "powder removal", resulting in the mixing of paper wool and silt into the ink, as well as stacking and stacking blankets.

Approach:

(1) Due to the poor adhesion of the binder or the coarseness and specific gravity of the pigment particles, an additive varnish or oil can be added to increase the viscosity and transfer performance.
(2) As the viscosity of the ink is too high and too hard, the texture of the paper is loose, the powder is removed, or the oil content is insufficient, and No. 6 varnish, Cambon, Vaseline, Willy oil, etc. can be used to change the ink viscosity and increase the wetting property.
(3) reduce the amount of dry oil (plus new ink) or add some non-dry accessories.
(4) Ink pigment particles are coarse, with a large specific gravity, and it is still not possible to increase the viscosity. The ink can be rolled before being used in the ink mill.
(5) If certain properties are changed, the phenomenon of stacking ink cannot be thoroughly solved. It can be processed in combination with multiple washing rollers, printing plates, and blankets.

2. Flower board

Phenomenon and reason: The flower pattern is gradually getting smaller and falling off. The printing plate loses its good fat-sensing ability, which reduces the level of printed matter and reduces the ink color. There are many reasons for floral patterns. For example, the pressure of rollers, water rollers, and ink rollers is too high. The water of the bucket is too large or the water is too large. There are too many paper sands or the blanket is too hard. Commonly caused by the ink The following reasons:

(1) The ink pigment particles are too thick and too hard, and the friction on the plate surface is large. Especially for the fine dots, the scratches damage the pattern ink-absorbing foundation and cause a flower pattern. Some pigments have slight corrosion to the layout, and the ink-absorbing foundation that damages the pattern of the layout will also cause floral patterns.
(2) Insufficient oiliness of the ink, weak ability to resist the acidic liquid, and the ink layer on the basis of the layout pattern is soaked by the acid network.
(3) The viscosity of the ink is not suitable, and the viscosity of the ink is too large. The cohesion of the ink is also large. During the transfer process, the ink layer is not easily broken, resulting in insufficient ink layer on the basis of the layout pattern and the flower pattern; the viscosity is too small, the ink is on the layout The adhesion is not strong, the layout of the layout of the foundation can not be protected by the remaining ink layer, the pattern of the foundation is directly invaded and friction caused by the acidic version of the flower.

Approach:

(1) The ink has low oiliness, low viscosity, low adhesion, common in black ink and 915 dilute ink, can add some 05-90 or 05-93 bright light to improve performance (black ink should not exceed 10%) .
(2) The viscosity of the ink is too large, resulting in the lack of residual ink layer on the plate and the flower pattern. Adding No. 6 varnish or Kangbang can be used to improve.
(3) Ink pigment particles are too coarse and corrosive (eg chrome yellow ink). Replace the ink or grind the ink before use.

3 paste version

Phenomenon and reason: When the paste version is unclear, the dot lines are enlarged, and the neighboring dots are merged with each other, so that the printed ink is dark and thick and the layers are reduced. The reasons for stencil are: In addition to the fact that the syrup is too hot, the pressure of the roller is too large, and the blanket is too loose, the following reasons are commonly caused by the ink:

(1) The ink is adjusted too thinly and the texture is too loose. The cohesion is small, and it is easy to spread outwards, resulting in the expansion of dots and lines.
(2) When the amount of ink under the ink is large, and it exceeds the amount of ink that can be accommodated in the layout pattern, it spreads out to cause a paste.
The fine mesh printing should strictly control the ink quality, otherwise it is very easy to paste. (3) The ink pigments are too thick or too heavy, and the transfer performance of the linking material is reduced, resulting in deposition on the plate surface blocking outlets. On the other hand, because the particles are too thick, the fine mesh can not accommodate and expand outwards, and at the same time, the friction on the plate increases, destroying the hydrophilic properties of the blank parts and making them feel fat, causing the adjacent dots to merge and paste.
(4) The weight of the ink makes the blank part of the plate feel fat and produces a paste plate. If too much auxiliary material is added to the ink, the viscosity of the ink may be reduced, the ink may become loose, and the oiliness of the ink may increase.
(5) The ink accumulates on the plate, blocking the gaps in the dots, expanding the lines, and causing stencils.

Approach:

(1) Paste of ink occurs frequently in gold and red ink, and some gum arabic may be properly added in the water bucket. Can also be diluted with 915 Wei Li oil and 05-93 light pulp half, the use of better results. Most of the ink is too thin, resulting in the paste is too thin and the resulting paste, replace the new ink or add some concentrated ink.
(2) When the ink is large, the color of the ink can be adjusted to reduce the amount of ink.
(3) Reduce the use of accessories such as Kangbang to control the paste.
(4) The stencils caused by the stack are to be resolved from the root cause of the heap. $Page break $

4. Deinking

Reason for deinking: Deinking refers to 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 string roller and the uniform ink roller do not ink. Saying that ink will affect the normal ink transfer roller, so that the printing plate can not get the desired ink and fade, resulting in different shades of ink. Common deinking has the following reasons:

(1) Insufficient oiliness and low viscosity of the ink cannot drive the ink to move with the rotation of the ink fountain shaft, causing deinking.
(2) The ink has poor fluidity and does not easily flow between the ink cutter shaft and the blade, affecting the ink under the ink.
(3) The ink is gelled into a jelly state, which reduces the viscosity and fluidity and loses the printing performance, while the stationary ink causes deinking on the ink fountain.
(4) The ink contains too little oil, too much fines, and does not transfer pigment particles well and stays in the ink fountain to form deinking.
(5) The ink dries too fast, which causes the ink fountain shaft to dry and solidify, loses ink transmission performance, and blocks the gap between the ink fountain roller and the blade to form deinking.
(6) Too much impurities such as ink, residue, etc. in the ink block the gap between the ink fountain and the blade, affecting the formation of deinking under the ink.
(7) The water bucket syrup is too acidic or the gum arabic ink is too much ink.
(8) The layout is too watery.

Approach:

(1) Ink roll deinking caused by ink problems, black ink is more common. The ink produced from the soot lime has a large oiliness and does not cause deinking. The black ink with carbon powder as the raw material is poor in oil and deinking phenomenon may occur. It is possible to dilute some thin inks. If the image contrast of the product is large, when the ink cannot be thinned, some oleic acid can be added to the ink. .
(2) The ink has low viscosity and short ink. It is commonly used in light-colored inks formulated with a lighter. This type of ink is easily emulsified. The acid in the water bucket invades the ink, corrodes the surface of the ink roller, and causes the surface of the ink roller to pro The water layer can be used to remove oil from the ink. In this case, thicken ink can be added to the ink to increase the viscosity.
(3) After the occurrence of deinking of the ink roller, the moisture of the plate should be reduced as much as possible and the acidity of the water bucket should be reduced to remove the gum arabic.
(4) The ink is too thick and too hard, add No. 6 varnish to increase its fluidity.
(5) Intensively agitate the ink fountain and remove the inner skin and impurities from the ink fountain to prevent the ink from drying or gelling and prevent deinking.

5. Ink emulsion

Phenomenon and Cause: The separation of water into tiny droplets dispersed in the ink is called emulsification. In the printing process, the oil and water are not absolutely incoherent, due to the constant contact of ink and moisture, and the role of mechanical forces and other factors. There will be different degrees of emulsification involved. When printing yellow ink and pale blue ink, this phenomenon often occurs, and most of them occur on both ends of the ink roller. The emulsification of ink is very harmful to the printing, diluting the ink color, affecting the drying of the imprinting, creating a dirty surface, the ink being “slack”, the ink roller being deinked, the imprinting color discoloring, the paper becoming yellow or blue, affecting the product quality, etc. Adverse consequences. The cause of ink emulsification is mainly due to the decrease of the surface tension between oil and water. In addition to the fact that the surface water is too large, the water of the water bucket is too strong, the content of the resin is too much, and the active material on the surface of the paper is detached, the common ink The reasons for emulsification are:

(1) The acid value of the ink is too high. The surface tension at the interface between ink and water depends on their polarity. The polarity of the ink is usually measured by the acid value. The more free fatty acid 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 in the transfer process, but the high acid value is the biggest cause of ink emulsification. (2) Ink pigments have poor water resistance, especially pigments for offset inks, which are insoluble in both water and acid, but also have water-resistance properties. Since ordinary lake pigments are often hydrophilic, they are often hydrophilic powders. When the dye components in the pigment encounter acidic water, the dye will precipitate out of the dissolved water quickly, causing emulsification failure. If the pigment of the ink pigment is coarse, the viscosity is not enough, and the binding with the binder is not strong enough during the rolling process, the moisture is easily absorbed by the contact with the acid during the printing process and swells by itself and gradually separates from the binder to generate emulsification.
(3) There are no pictures on both sides of the plate, and the water content is large, which causes emulsification on both ends.
(4) To add too much diluting agent in ink, the commonly used auxiliary oil is carbonic acid, Weili oil is aluminum hydroxide, and it is an emulsifier, so the more the auxiliary material is added, the more the ink will be emulsified. . Too much dripping agent in the ink, the printing process is bound to increase the acidity of the water bucket syrup, too strong acid can easily cause ink emulsification, in addition to the driers itself is a strong emulsifier, so the ink in the dryer to increase and release more The more it can cause ink production