Analyze the quality of high and medium quality UV wrinkle ink printing

From the market division, screen printing is not a major printing process in the field of packaging and trademark anti-counterfeit printing. However, according to the recent development of the domestic and international packaging market, it can be seen that screen printing has appeared in the field of anti-counterfeiting packaging printing. With steady growth, screen printing has occupied an extremely important position in the packaging and printing market with its own characteristics. Wrinkle ink is born in this trend. The ink is printed on substrates such as gold cardboard and silver cardboard. After being wrinkled and dried by UV, it will produce a special wrinkle effect on the surface due to UV wrinkle ink. With three-dimensional strong, luxurious and elegant, ink film full and good visual effects and other characteristics, its application has expanded to print high-grade tobacco packets, wine boxes, gift boxes, health products packaging boxes and other fields. However, in the actual printing operation, due to the short time available for this ink, the widespread application and lack of research and discussion are still insufficient, so the printing quality of UV wrinkle ink will be affected by many factors, such as the number of screens, Stretching angle, printing pressure, squeegee angle, printing speed, drying speed, etc., if these factors are not well controlled, will inevitably affect the quality of the final product.

In addition, UV wrinkle inks are difficult to get the desired wrinkle effect after printing. This is the biggest problem encountered in UV wrinkle ink printing. Any change in the parameters during the printing process may lead to printing failure. This requires a lot of experiments to determine the quality The printing conditions required for the prints.

1. experimental method

In the initial analysis of the factors that affect the printing quality of UV wrinkle ink (screen mesh number, stretch tension, stretch angle, photosensitive thickness, printing pressure, printing speed, blade angle, mesh distance and drying speed), based on the Crude experiments were carried out to determine the most important influences and determine the general scope. Then the optimal design was carried out to determine 16 sets of printing solutions. The final fine test was used to obtain prints and the conclusions were reached through analysis and evaluation of prints.

2. experiment procedure

2.1 Coarse experiment

2.1.1 Specific experiment

The main purpose of the crude experiment was to screen major factors and determine the general scope of the main factors.

The mesh parameter is set to 150 mesh;

The maximum pressure of the air pump used in the experiment was 1 MPa, and the empirical value range during use was 0.6-0.8 MPa, so the experiment was selected to be 0.7 MPa;

At present, the commonly used method of coating photosensitive adhesives for screen printing companies is to apply three times on the printing surface and one on the back side. Therefore, the printing surface coating is set to 3 times.

Coarse experiment (1): Determine the speed of wrinkling

Fixed stretch net tension, scraper angle, printing pressure, printing speed, and web distance were used to determine the range of creping speed.

Coarse Experiment (2): Determine Range

Fix the stretch angle, the blade angle, the printing pressure, the printing speed and the wrinkle speed, and determine the range of the mesh distance through experiments.

Coarse Experiment (3): Testing the Effect of Printing Pressure on Printing Effect

Fixed stretch angle, blade angle, wrinkle speed, printing speed and mesh distance, and the effect of printing pressure on the printing effect was determined through experiments.

Coarse Experiment (4): Determining the Effect of Printing Speed ​​on Printing Effect

The impact of the printing speed on the printing effect was determined experimentally by fixing the stretch angle, the blade angle, the wrinkle speed, the web pitch and the printing pressure.

Coarse experiment (5): Effect of test squeegee angle on printing effect

Fix the stretch angle, printing pressure, printing speed, crease speed and mesh distance, and determine the effect of the doctor blade angle on the printed product through experiments.

Coarse Experiment (6): Effect of Testing Angle of Stretching Net on Printing Effect

Fixed printing pressure, printing speed, creping speed, mesh distance and doctor blade angle, and the influence of the stretching angle on the quality of the printed matter was determined through experiments.

Coarse experiment (7): Further testing the effect of stretch angle on print quality

From the rough experiment (6), it can be seen that when the stretch angle is 45°, the moire is the most serious; when the stretch angle is 60° and 75°, the moire is also severe; when the stretch angle is 30°, Basically no moire appears. In order to determine the further extent of the stretch angle, the experiments listed in Table 7 were performed.

2.1.2 The rough experiment conclusion

(1) Screen mesh number

The higher the precision required of the print, the higher the number of screen meshes, and vice versa. In the selection of the number of screen meshes, manufacturers recommend the use of 100, 150, 200 mesh screens. If the precision of the printing equipment is high, meshes with a higher mesh number can be selected. At the same time, taking into account the limited experimental conditions, the mesh size selected for this experiment was 150 mesh.

(2) stretch angle

The experimental results show that the stretch angle is 0°, the print does not produce moiré; the stretch angle is 30°, the moire is light; when the stretch angle reaches 45°, the moire is the most severe; the stretch angle is 60°, 75 At 0°, the print produces a lighter moiré pattern.

In a further experiment, it was confirmed that no moiré was produced when the stretch angle was 10°, 20°, and 25°.

Therefore, in the following fine experiment, the range of the stretch angle is set between 0 and 30°.

(3) Network distance

When the mesh distance is within 5mm, the image can be fully displayed on the substrate; and when the mesh distance exceeds 5mm, the image displayed on the substrate is less and less with the increase of the mesh distance.

And because the minimum value of the pitch adjustment in this experiment is about 1.5mm. Therefore, in the following fine test, the setting range of the mesh distance is 2 to 5 mm.

(4) Printing speed

The change in printing speed does not bring about a change in quality. It can only change the size of the ink wrinkle pattern. The printing speed is fast, the pattern is small; the printing speed is slow, and the pattern is large.

Because the size of the pattern is not included in the scope of the quality evaluation, the factor of the printing speed is not considered in the precision test.

(5) Scraper angle

The change of the blade angle can not change the quality of the print, just change the size of the pattern. Scraper angle is small, pattern is small, on the contrary, the pattern is large.

Also because the pattern size is not included in the scope of the quality assessment, the scraper angle is not considered in the precision test.

(6) Ink creping and drying speed

The speed of wrinkling is too slow and the print cannot wrinkle. Experimental measurement When the wrinkle speed is less than 14m/min, the ink cannot wrinkle, and when the speed reaches 14m/min and 14m/min or more, the ink will wrinkle.

Therefore, the range set in the precision test is 14 to 20 m/min.