3, bite color
In overprinting, the second color ink sticks off the first color ink. The main reasons for this phenomenon are:
(1) Insufficient drying of the base color (first color) ink or too fast drying of the second color ink causes excessive tackiness at the moment of printing;
(2) The second color printing pressure is too large and the printing speed is large;
(3) The ink has poor adhesion to the substrate;
(4) The compatibility of adjacent two color inks is poor;
(5) Improper use of thinner.
Solution:
Reduce the pressure;
Hair to the second color layout;
Improve the primary dryness of the first color and increase the drying speed (using a fast drying solvent);
Reduce the drying speed of the second color ink (and enhance heat drying), slow down the drying speed of the second color;
Changing the diluent of the second color to a component that does not dissolve the first color;
Replace the ink.
4, pinhole
Pinholes are tiny holes that appear on the prints, especially in the larger areas of the pattern.
The pinhole phenomenon is caused by the following: First, when the ink is transferred instantaneously, the ink becomes a very thin transparent layer, and the roller can be seen on the Internet. The printed product is a pinhole (blister) with the same size and is evenly spread over the printed product. This is called machinery. Pinhole. Second, due to the leveling nature of the ink and the poor wettability of the substrate, a disorganized pinhole, called a chemical pinhole, is formed on the print.
Treatment method: The mechanical pinhole can be solved by appropriately increasing the ink viscosity or making the ink dry slowly. For chemical pinholes, it is required that when adjusting the ink, do not pull it out too short to ensure the required leveling of the adhesion of the ink. Therefore, it can be corrected by adding the polyamide resin oil or other substances that increase the humidity while diluting.
5, overflow ink
Over ink refers to the occurrence of spots in the full-print portion of the ink, and the ink overflows from the portion of the drawing line, and the reason why ink is generated is that the viscosity of the ink is too low.
The processing method is: when the viscosity is too low, add a new ink or add a modifier with a resin to increase the viscosity; improve the printing speed; change the angle of the blade, use an acute angle to scrape the ink; adjust the position angle of the blade, and the near imprint area is better .
6, from the orange peel markings
From the orange peel mark is imprinted on the print is not level, the ink film was orange peel, especially the full version of the part.
The reason for this phenomenon is that the drying speed is too fast, the ink concentration is too light, the leveling property of the ink is bad, the thixotropy of the ink is large, the affinity between the printing plate cylinder and the paper in the aqueous ink is not good, and the effect of static electricity is slow.
Treatment method: Improve the fluidity of the ink, adjust the drying speed, increase the leveling, do not dilute the color too lightly, reduce the static electricity.
7, print residue odor
When prints are used to package items such as foods, odors become a big problem, and sometimes these odors are even absorbed by the contents. In this way, the problem will become more serious. In particular, since cellophane, polyolefin films, and the like have the property of easily absorbing a solvent, special care must be taken when printing. When packaging foods, people are most sensitive to the smell of toluene. This odor is not only caused by the residual solvent and sometimes mixed with the odor of the packaging material itself, such as oxidation odor of polyolefin, etc., and it is difficult to solve the problem. National standards have also made corresponding provisions for this. Even if it is not used for food packaging, it should be produced from the perspective of environmental protection in line with national standards.
Solution:
Do not use odor-rich colorants and additives;
Adjust the drying speed, reduce the residual solvent; use the solvent with less residual odor (it will easily cause residual odor when mixed with impure solvent such as high boiling point);
Reduce the printing speed and fully ventilate to reduce the solvent concentration.
In short, the emergence of version failures involves many aspects. In order to avoid failures in production, attention should be paid to the following changes:
(1) Change of Ink Drying of printing ink Main solvent evaporates and dries. The volatilization rate of the ink is proportional to the printing speed. When the two are adapted, the printing will be normal; if not, the stickiness will appear. Deinking, incomplete image, knife line and other faults. Therefore, it is necessary to observe the printing situation at any time to supplement the diluent and change with the temperature. Correct use of various solvents, according to the type of ink to control the volatilization rate of ink, drying is too slow, in the printing of a color when easily stick out; too fast, it will produce crystallization phenomenon. Secondly, we should carefully examine the viscosity and color difference in printing.
Inspection scope and requirements Inspection items Inspection requirements Printing viscosity Testing method: Use the 3rd Thun Cup to test the relative viscosity. Frequency: 30 minutes, no less than 2 times in each group. Color detection method: Use a stick to scrape ink (see Ink samples when signing)
Detection frequency: 30 minutes to detect once, each group of not less than 2 times the color difference control position detection method: use the color difference meter to measure the same main parts detection frequency: 60 minutes, not less than 2 times process discipline detection range: ambient temperature, humidity, printing Pressure, drying temperature, speed, static ink leveling system inspection frequency: no less than 2 inspections within 60 minutes
In overprinting, the second color ink sticks off the first color ink. The main reasons for this phenomenon are:
(1) Insufficient drying of the base color (first color) ink or too fast drying of the second color ink causes excessive tackiness at the moment of printing;
(2) The second color printing pressure is too large and the printing speed is large;
(3) The ink has poor adhesion to the substrate;
(4) The compatibility of adjacent two color inks is poor;
(5) Improper use of thinner.
Solution:
Reduce the pressure;
Hair to the second color layout;
Improve the primary dryness of the first color and increase the drying speed (using a fast drying solvent);
Reduce the drying speed of the second color ink (and enhance heat drying), slow down the drying speed of the second color;
Changing the diluent of the second color to a component that does not dissolve the first color;
Replace the ink.
4, pinhole
Pinholes are tiny holes that appear on the prints, especially in the larger areas of the pattern.
The pinhole phenomenon is caused by the following: First, when the ink is transferred instantaneously, the ink becomes a very thin transparent layer, and the roller can be seen on the Internet. The printed product is a pinhole (blister) with the same size and is evenly spread over the printed product. This is called machinery. Pinhole. Second, due to the leveling nature of the ink and the poor wettability of the substrate, a disorganized pinhole, called a chemical pinhole, is formed on the print.
Treatment method: The mechanical pinhole can be solved by appropriately increasing the ink viscosity or making the ink dry slowly. For chemical pinholes, it is required that when adjusting the ink, do not pull it out too short to ensure the required leveling of the adhesion of the ink. Therefore, it can be corrected by adding the polyamide resin oil or other substances that increase the humidity while diluting.
5, overflow ink
Over ink refers to the occurrence of spots in the full-print portion of the ink, and the ink overflows from the portion of the drawing line, and the reason why ink is generated is that the viscosity of the ink is too low.
The processing method is: when the viscosity is too low, add a new ink or add a modifier with a resin to increase the viscosity; improve the printing speed; change the angle of the blade, use an acute angle to scrape the ink; adjust the position angle of the blade, and the near imprint area is better .
6, from the orange peel markings
From the orange peel mark is imprinted on the print is not level, the ink film was orange peel, especially the full version of the part.
The reason for this phenomenon is that the drying speed is too fast, the ink concentration is too light, the leveling property of the ink is bad, the thixotropy of the ink is large, the affinity between the printing plate cylinder and the paper in the aqueous ink is not good, and the effect of static electricity is slow.
Treatment method: Improve the fluidity of the ink, adjust the drying speed, increase the leveling, do not dilute the color too lightly, reduce the static electricity.
7, print residue odor
When prints are used to package items such as foods, odors become a big problem, and sometimes these odors are even absorbed by the contents. In this way, the problem will become more serious. In particular, since cellophane, polyolefin films, and the like have the property of easily absorbing a solvent, special care must be taken when printing. When packaging foods, people are most sensitive to the smell of toluene. This odor is not only caused by the residual solvent and sometimes mixed with the odor of the packaging material itself, such as oxidation odor of polyolefin, etc., and it is difficult to solve the problem. National standards have also made corresponding provisions for this. Even if it is not used for food packaging, it should be produced from the perspective of environmental protection in line with national standards.
Solution:
Do not use odor-rich colorants and additives;
Adjust the drying speed, reduce the residual solvent; use the solvent with less residual odor (it will easily cause residual odor when mixed with impure solvent such as high boiling point);
Reduce the printing speed and fully ventilate to reduce the solvent concentration.
In short, the emergence of version failures involves many aspects. In order to avoid failures in production, attention should be paid to the following changes:
(1) Change of Ink Drying of printing ink Main solvent evaporates and dries. The volatilization rate of the ink is proportional to the printing speed. When the two are adapted, the printing will be normal; if not, the stickiness will appear. Deinking, incomplete image, knife line and other faults. Therefore, it is necessary to observe the printing situation at any time to supplement the diluent and change with the temperature. Correct use of various solvents, according to the type of ink to control the volatilization rate of ink, drying is too slow, in the printing of a color when easily stick out; too fast, it will produce crystallization phenomenon. Secondly, we should carefully examine the viscosity and color difference in printing.
Inspection scope and requirements Inspection items Inspection requirements Printing viscosity Testing method: Use the 3rd Thun Cup to test the relative viscosity. Frequency: 30 minutes, no less than 2 times in each group. Color detection method: Use a stick to scrape ink (see Ink samples when signing)
Detection frequency: 30 minutes to detect once, each group of not less than 2 times the color difference control position detection method: use the color difference meter to measure the same main parts detection frequency: 60 minutes, not less than 2 times process discipline detection range: ambient temperature, humidity, printing Pressure, drying temperature, speed, static ink leveling system inspection frequency: no less than 2 inspections within 60 minutes
(2) Change of cold and hot air The cold and hot air device is an important device for accelerating ink drying. In winter, the room temperature is low and hot air must be increased. In summer, when the air temperature is high, hot air must be reduced as the temperature rises. Can use constant temperature (20) constant humidity (relative humidity between 50% - 60%).
(3) Changes in mechanical parts Due to the long-term rotational speed of the printing machine, some components have undergone changes in wear and should be replaced or repaired in time.
Source: cigarette packets ink information network
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