Printing ink printing failure and processing method

First, the whitening of printing ink film

1 point whitening. The main reason is that the ink feeding system causes poor mutual solubility of wax surfactants, and the second reason is that the printing process is not reconstituted after the ink crust is transferred to the graphic.

Treatment method: Aromatic hydrocarbons or ester solvents should be added to promote re-dissolution. Or install a stirrer in the ink fountain (such as using plastic pipe, cover it with unprinted plastic film on the outside, and then turn the two heads tightly in the ink head to randomly stir the ink), or add resistance when the ink is made Oxygen treatment.

2-point white point. The main cause is the static electricity of the ink or the static electricity of the substrate. Or due to the dilution of solvent generated static electricity (due to different solvents have different resistance). Usually occurs when the temperature is high or the printing speed is high. Secondly, when the film is tight, it is loosened or loosened before it is tight, and the static electricity is often caused by high humidity.

Treatment method: In the ink can increase the amount of antistatic agent (excess will affect the composite fastness), select the solvent resistance of the solvent dilution ink, adjust the release, take the ground wire (general depth of 700 ~ 1500 mm) to deal with it.

3 Cracked Albino. One of the main reasons is that the ink transfer performance is poor, and the second is that the plate pattern is too shallow and it is very easy to volatilize the solvent in the ink system too quickly.

Roughness of the general imprinting results in poor film formation, especially when the ink system or the ink fountain thinner is added to inhale moisture and whitening occurs, mostly in an environment where the humidity of the summer workshop is too high.

Treatment method: Replace the ink with good transferability or replace the deeper plate, and add the slow-drying solvent to it.

4 Bleaching of the whole block. One of the main reasons is that when the continuous printing time is too long, the operator repeatedly adds a single solvent when it is found that the viscosity of the ink becomes sticky or thickens, thereby breaking the balance of volatilization of the mixed solvent in the original ink system, resulting in printing ink. The ink layer is rough and white when forming a film. The second is that the operator has added the mixed solvent even if it is added in excess, but the amount of the synthetic resin contained in the ink is relatively reduced, and the above whitening phenomenon may also occur. Treatment methods: First, add 3% to 7% of slow-drying solvents, especially the real solvents that can increase the resistance of the ink to the invasion of water molecules; the second is to use a special diluent containing resin; the third is to add 5 to the ink. % ~ 15% of the oil varnish to overcome the whitening caused by the lack of resin content, the fourth is installed in the workshop can regulate the temperature and humidity of the central air conditioner or eliminate it with a moisture absorber.

Second, graphic brightness is insufficient (ie, poor gloss)

The whitening phenomenon listed above will be dull. Sometimes it does not reach whitening, but also affects the gloss of the ink film after printing.

Ink thick and no light

Cause: The ink is excessively dispersed during grinding or mixing of paper or plastic crumbs and environmental dust during storage or printing. Second, the diameter of the binder or pigment particles in the ink system is larger than 0.1 μm, resulting in insufficient brightness of the printed graphic, followed by the ink system. Low gloss or poor gloss due to excessive resin content or additional dilution solvents (but not true solvents) during printing.

Processing method: When the ink reaches a certain degree of fineness, it will not be ground again. It should be stored in a warehouse or workshop at a room temperature of 15 to 30°C. The second is to improve the printing shop environment to ensure clean, bright and dust-free, fixed-point removal of paper or plastic shavings at regular intervals; The third is to re-grind or filter the ink or change the new ink; the fourth is to add gold transfer ink, true solvent or plasticizer in the ink fountain to reduce the viscosity of the ink.

Third, the imprint is blurred and trailing

The main reason is: the ink contains coarse particles or mixed with dust, paper dust, plastic shavings, etc. The second is the smear caused by a small defect in the blade and the ink film is too soft.

Treatment method: First, exchange the ink with high softening point or filter ink; Second, clean the ink ink bucket or barrel mixed with dust, paper scraps or plastic crumbs; Third, cover the ink immediately after use, or install a new one on the ink bucket. Top cover; four is to replace the scraper or scraper blade behind a piece of 1 ~ 3mm thick rubber or plastic foam sheet to improve its squeegee elasticity.

Fourth, the picture pinhole

One of the main reasons is that the rough surface of the substrate is not smooth or the printing plate is stained; the second is that the active agent in the ink is too much or the ink is not ripe (the foam does not disappear) completely, often called chemical pinholes (different parts and different Area and different number of pinholes). In addition, faults called mechanical pinholes are pinholes in the same area and the same size and number of the same substrate, often appear repeatedly, and rarely disappear during the printing run-in period.

Treatment methods: First, exchange substrates (clean or unstained); Second, control the amount of active agent in the ink system or add about 0.2% of defoaming plasticizer in the ink for 48 hours (excessively can cause ink film The craters are difficult to level.)

To solve the mechanism pinhole fault method: First, change the printing plate or the printing machine to open and run after a period of time and then open the printing, the second is to adjust the printing pressure.

Fifth, the network is missing or missing

Under normal circumstances, the cause of the failure is: First, the viscosity of the ink is too high; Second, the ink film drying too fast; Third, there are particles in the ink; Fourth, the poor leveling of the ink; Fifth, the lack of printing pressure; Plate sleeve circumference is not smooth, not clean and so on.

Treatment method: First, the ink viscosity should be adjusted between 25 ~ 30S/25 °C · 4 cups between the coating is appropriate; Second, the ink is added in the printing when the slow-drying thinner; third is to prevent the ink from drying prematurely in the plate version of the hole (Add wetting agent); Fourth, add 1% to 3% leveling (such as ether) or adjust the pressure, so that the substrate tension control is appropriate at 0.05; Fifth, replace the printing plate or grinding India Edition surface.

VI paste version (in the non-graphic area)

The main reason for the paste version is: the ink system has a low softening point or a low pH value. The second is that the viscosity of the ink is too high, the scraper does not scrape the net, the hardness of the scraper blade is too strong and the toughness is not enough, or the angle of the scraper is not correct. Third, the cold wind is insufficiently blown or the angle is not good during printing (when it is severe, the printed matter may be adhered); Rough is not smooth. Treatment methods: First, exchange the ink with a higher softening point, or choose a pH value close to neutral; second, dilute the ink or add an eraser behind the doctor blade (foam can also be used, its thickness should be 1 ~ 3mm The third is when the hot air blow (the temperature should be depending on the ambient temperature 30 °C or 35 °C or 40 range three levels) after blowing the blot, adjust the cold blowing angle (should be 25 °, 30 °, 35 °, 40, respectively) ° is good; four is to replace the printing plate.

Seven, printing products adhesion

One reason is that the high temperature and fast printing speed make the solvent in the ink film not completely evaporated (relatively speaking), or after the hot air blow, the cold air blown is insufficient and is not ripened and dried, but also due to the quickness and slowness of the ink. The volatilization rate is too high (causing the surface to dry within the wet); Fourth, the ink system invades the water molecules or mixed with substances that promote the oxidation properties (such as metal lead, cobalt, manganese salts), so that the printing ink layer after storage Gradually oxidize (release) due to stickiness.

In addition, when the ink is stored in the factory, it is stored in poorly ventilated warehouses, especially if the softening point of the linking material is low or the anti-skid anti-slip agent component is too small, followed by the gravure pattern of the gravure plate being too deep and the ink film thickness of the printing ink will appear after transfer. Stick back. Processing method: In the season of gas temperature, the printing speed is slowed down or anti-adhesion aids are added in the ink; the second is to use the fast, medium, and slow mixed solvents and use as little solvent as possible to adjust the ink; third is when the heat After blowing, increase the cold air blow or adjust the air blow angle; fourth is to measure the thoroughly dried ink film and re-adjust the printing machine speed according to the drying time; cap the ink fountain or bucket or cover the ink at any time to prevent water molecules Invade and prevent the oxidation of metal salts; Fifth, the ink is stored in a ventilated, dry, no-moisture, low-temperature warehouse; Sixth, re-plate (print depth is 25 ~ 45cm is better, replace the printing ink with a higher softening point. $Page break $

Eight, ink film crystallization and difficult to overprint

The general performance is that it is difficult to print the second or third color ink after the previous ink is formed, and the surface thereof has been crystallized (ie, vitrified). This is mainly due to the difference in the properties of the two inks or their composition. , resolving (that is poor affinity) bad; second is to add too much silicone lubricant in the ink system, especially in hot weather operation; Third, the surface of the composite ink lacks the matt or anti-adhesive surface that can form a rough surface. The antistatic agent causes the surface to be too smooth. The fourth problem is that the printing plate hole (graphic pattern depth) is too shallow or the ink flow is too high or the viscosity is high.

Treatment method: In the ink system, increase the amount of true solvent to increase its re-dissolving affinity, replace the ink with the same color as the previous color (the same brand and manufacturer), and secondly, use the ink containing silicone lubricant as much as possible. In one color, the second or third ink is printed when it is slightly tacky. Add appropriate amount of matte powder (does not affect its surface gloss as standard) in compound ink or subtract anti-stick and anti-static dose, replace printing plate or re-manufacture the shade plate with depth of 25 ~ 45 μm, optional content High viscosity and low viscosity inks regularly eliminate plate ink knots.

Nine, poor composite fastness

The Indian-Indian compound is not strong, mostly due to dilution of the ink system or the printing process, the resin content in the ink system is too small or the viscosity of the ink is too large, and there are unselected detachments caused by the special ink and the composite adhesive. On the other hand, the surface tension difference between the ink and the substrate is too large and the ink is uncured after printing (cooling), or the solvent is completely evaporated and the ink hardness is too small (the film is too brittle, too thick, or the plate is too deep ). In particular, the printing materials were not handled well, and the imprinting pressure was small and there was no resistance to rubbing and tearing. Note: The control of surface tension is mainly for the corona discharge treatment of printing materials.

Processing method: use printing compound ink with high resin content but small viscosity, use the ink and adhesive with the same properties as the printing material according to the type and model provided by the ink factory; second, adjust the surface tension controller of the printing machine (make it In the range of 38dyn/cm2, due to the different dry or dry time of different solvent type inks, the adhesion fastness should be re-examined after 48h aging (eg due to the viscosity, the dry speed and adhesion will not be strong. When using 175-line printing gradation printing, the technical parameters are: white ink / viscosity 25 ~ 30S/25 °C · coated 4 cups (40 ~ 100 m/min printing speed); and color ink viscosity should be controlled at 28 ~ 33S/25 °C·coating 4 cups (100～140m/min printing speed) range, while the actual application is lower by an average of about 5 S. The fifth is a short-time relaminated printing, the viscosity of the diluted ink is lower by about 3S or quick-drying The main solvent is the slow solvent, supplemented by the slow-drying solvent, which promotes the tight binding of the hydrogen bonding force.7 The printing roller is replaced with a depth of 15 to 35 μm. The ink appears water-like and should be temporarily added with gold transfer oil or special thinner, and it is best to use the thinner specifically produced by the ink factory, or TM3, etc. Ninth, in accordance with the "two-dimensional method" design, the diluent is formulated to avoid adhesion. bad.

Ten, intolerant cooking or odor

After the printing and compounding, the packaging is not resistant to cooking, and most of the images are blurred, faded, faded, or residual solvent odor due to the imprinted (dyed) blot or the migration of the amide-based resin with a lower softening point after sterilization. Slowly moving inwards or outwards Generally, this phenomenon is caused by the fact that the ink itself is not heat-resistant, and the heat and pressure become more pronounced. Odor is caused by the addition of butanone or toluene solvent in the printing process or the use of polyisocyanate compound glue. After the hot air and cold air are blown, the printing and compounding process is completed, but the free cyano group remaining in the rubber compound is inevitably generated again when the package is used in the secondary and tertiary sterilization processes. The same reason. If the above materials are used, the fault will also repeat itself. It is very difficult for the solvent compound to completely evaporate and the ink film and the compound to dry out completely because the printing compound is compounded for a moment. Especially in detecting control instruments