The blurring of images and texts is due to these several reasons
Unclear graphics and text is one of the most common failures in gravure printing, which is generally caused by human, machine, material, method, and environmental factors. Human factors
Unclear graphics and text is one of the most common failures in gravure printing, which is generally caused by human, machine, material, method, and environmental factors.
Employees' lack of good professional ethics and sense of responsibility is one of the reasons for many major quality accidents. In order to ensure the quality of intaglio printing, it is necessary to strengthen the professional ethics education for employees and strengthen their job awareness; Employees are required to be proficient in the use and operating procedures of the equipment.
2. Machine Factors
In intaglio printing, the main equipment problem that causes unclear graphics and text is that some related devices are not fully equipped or, even if equipped, are not well utilized. These devices mainly include the following types.
A. Ink circulation device. Many printing equipment in enterprises are not equipped with an ink circulation device, which directly adds ink to the ink tray. This results in insufficient ink circulation and poor liquidity, resulting in unclear paste and printing graphics. The ink circulation device includes two types: an electric ink circulation device and a pneumatic pump ink circulation device. The motor type has a lower price, but it can block the filter screen at the ink outlet and prevent the ink from hanging onto the tray, resulting in deinking. Its initial ink mixing amount is large, which is easy to cause waste of ink. The pneumatic pump type initial ink dispensing has a small amount of ink, which can reduce ink waste, and rarely occurs when foreign matters in the ink block the filter screen and cause fires due to overheating of the motor, with high safety.
B. Left and right swing device of ink scraper. In order to extend the service life of the scraper, some enterprises often remove the left and right swing devices of the scraper. This not only causes problems such as unclear graphics and text, but also shortens the service life of the printing plate cylinder.
C. Circulating water cooling device. The main function of the circulating water cooling device is to quickly cool the printed matter after it exits the oven, so as not to cause anti adhesion and mutual adhesion between the front and back sides of the printed matter after winding. Due to its high cost, many printing enterprises often do not have equipment when introducing equipment, which has two direct consequences.
One is that with the prolonged operation of the equipment, the temperature of the first guide roller that the printed matter passes through after exiting the oven quickly rises. When the temperature rises to a certain degree, the resin in the ink is burned, causing a reverse adhesion phenomenon, and the printed image and text are not clear.
The second is that the ink or varnish on the printed matter does not completely dry and enters the winding device. When it is unfolded again, it will cause the front and back sides to adhere to each other, which also causes unclear printing images and texts. In order to reduce the illegibility of printed images and texts, it is recommended that the above devices be equipped in a timely manner.
3. Material factors
The main materials that affect the quality of printed matter include: printing materials, ink, solvents, and rubber rollers.
A. Printing material. Printing materials include plastic, paper, aluminum plated paper, and aluminum foil. Our company mainly prints aluminum foil and aluminum plated paper. Poor surface treatment of aluminum foil and excessive oil contamination can lead to poor ink transfer performance, resulting in unclear printing images and texts; The aluminum plating effect of aluminum plated paper is not good, and the surface is uneven. The printed matter will produce many bright spots, and the graphics and text are naturally not clear.
B. Ink. Any of the quality indicators such as viscosity, fineness, yield value, thixotropy, fluidity, and adhesion of the ink that do not meet the printing requirements will affect the transfer of the ink on the printing material, resulting in unclear graphics and text of the printed product. In addition, excessive impurity content in ink can also affect the clarity of printed images and texts. When using old ink, filter it, add a certain amount of new ink, and replace it with new ink if necessary.
C. Solvent. "The low purity of the solvent, which contains too much fat or moisture, is bound to be detrimental to the full dissolution of the ink, resulting in an impure printing quality, unclear and insufficient printing graphics and text.".
D. Plate cylinder. For gravure printing, the number of screen lines on the printing plate cylinder, the shape and depth of the screen holes, the quality of the chrome plating layer, and the quality of the surface polishing treatment will directly affect the transfer rate of ink within the screen holes. The ink transfer rate is low, and the printed image and text are not clear.
4. Methodological factors
The proficiency of operating skills, the correctness of operating methods, and the strict compliance with operating procedures have an important impact on the quality of printed matter. In summer, when the temperature is high and the solvent volatilizes quickly, it is necessary to minimize the blade angle, shorten the distance between the ink scraping point and the imprint point, and reduce the evaporation of ink solvent on the plate to reduce the occurrence of plate blocking. In winter, when the solvent volatilization rate is relatively slow, the opposite adjustment method is used to promote the volatilization of the solvent and reduce the occurrence of paste phenomenon. Another example is that aluminum foil and aluminum coated paper have different adsorption properties for ink, and different scraper adjustment methods should also be used. In addition, the blade pressure. The pressure of the imprinting roller, the tension of the printing material, and the volatility of the solvent should also be adjusted using different methods depending on the season and the raw material.
5. Environmental factors
Due to poor environmental hygiene, flying dust and other debris can fall into the ink, resulting in quality issues such as knife threads and plate blocking, resulting in unclear printed graphics and text. If the ambient temperature is too high and the solvent volatilizes too quickly, plate blocking can also occur, resulting in unclear printing images and texts. If the ambient humidity is too high, excessive water will seep into the ink, which not only reduces the purity of the ink, but also causes atomization on the ink surface, resulting in dull and unclear printing images and texts. Therefore, it is necessary to ensure that the environment of the printing workshop is clear and clean, and to ensure as much as possible the constant temperature and humidity of the environment.