Causes and countermeasures of common gravure failures (in)

In short, the organic solvent in the ink should be exhausted before it is rewinded. After the film is printed, it is loosely placed in a wire woven basket so that the ink layer can be continuously ventilated and dried, and then cut and bagged after solidification. The film is printed and bagged, lightly bandaged and placed upright in the carton to reduce the pressure between the film surfaces.
(2) Poor Ink of Certain Ink The connection material in this plastic gravure ink has a low melting point, and is easily adhered when the operating temperature is high and the relative humidity is high.
Countermeasures:
1 When the conditions permit, the operation shop installs air conditioners, the room temperature is controlled between 18°C ​​and 21°C, and the relative humidity is controlled below 65%;
2 Replace ink with good ink.
(3) Reasons for poor film printing film suitability:
1 Non-packaging resin processed plastic film;
2 Insufficient opening agent in resin. Countermeasure: Replace the plastic film.
(4) Static cause: The plastic film generates static electricity and forms thin films that adhere to each other. Countermeasures: Add antistatic agent to the plastic.
Second, the color registration accuracy of poor plastic film color is not allowed for the following reasons:
(1) Longitudinal direction (direction of travel) Printing register change 1 Tension variation during film pulling. Causes: The reel brake of the uncoiling device is not properly prepared; the reel material is too much, or the diameter of the reel material is too large; the three roller speeds are set incorrectly; the surface friction of the three rollers is reduced; the tension of the rewinding machine is changed. Countermeasures: Check and adjust each control device.
2 The difference in the diameter of the plate cylinder is poor. Cause: The growth of the diameter difference during the platemaking process is inaccurate. Countermeasure: Measuring the diameter difference (method: See the plate making section).
3 abnormal rules line. Cause: Insufficient density, printing offset, etc. Countermeasures: Adjust the sensitivity of photocells, and artificially eliminate defects such as plate stencils.
4 The diameter of the plate cylinder is small. Reason: The smaller roller diameter overlay accuracy is difficult to control. Countermeasures: If the length of the bag is short, the imposition method may be used, ie, two or more bags may be printed on one roller.
(2) The lateral register device is unstable.
the reason:
1 The film is loosened on one side and the guide roller is in parallel.
2 printing pressure is not uniform;
3 Plate cylinder and impression cylinder form taper;
4 Film tension changes, etc., and the film swings left and right. Countermeasures: Check and adjust each element one by one, such as when the lateral register device is loose.
Third, printing fastness bad plastic film printing fastness has the following reasons:
(1) The corona treatment of the polyolefin film was poor. Countermeasures: Check whether the surface tension of PE and PP reaches 40 dynes/cm or more.
(2) The affinity of the printed ink and the printed material is poor. This is a poor mixture ratio. Countermeasures: Replace the ink and adjust the solvent ratio.
(3) The temperature and relative humidity of the printing shop vary greatly. Countermeasures: As far as possible, the relative humidity of the workshop should be controlled between 50% and 60%, but it should not be too low. Below 40%, static electricity is easily generated. Room temperature is best controlled at 18 °C ~ 23 °C is the best, and keep the environment clean and air circulation.
(4) The printability of the plastic film itself is extremely poor, and it is still unsatisfactory after corona treatment. Countermeasure: Replace the printed material.
Fourth, the pattern size shift (1) When printing, the longitudinal pattern shrinks. Reason: Insufficient shrinkage margin. Due to the tension of the plastic film and heat drying during printing, the longitudinal dimension of the film is larger than the shrinkage of the printed image. Countermeasures: The amount of shrinkage should be properly left when making plate, and the tension of the film should be minimized.
(2) The length of the pattern in the longitudinal direction is elongated during printing. Cause: The plate size has left too much of the shrinkage margin. Countermeasures: Increase the film tension.
Fifth, poor reproducibility of printed product layer (1) high light (bright part) is too deep. Cause: The printing plate is too dark and contains too much ink.
Countermeasures:
1 increase the number of mesh lines;
2 reduce the color of the ink;
3 Properly increase the angle between the doctor blade and the plate surface.
(2) The light is too shallow. Cause: The depth of the plate is not enough.
Countermeasures:
1 Use dark color inks;
2 The angle between the squeegee and the surface of the plate should be properly reduced. (To be continued)