Effect of PS grain shape on printing

The Ps version consists of a base and a photosensitive layer, and the sand pattern on the plate base represents the processing level of the plate base. Due to the lack of a unified judging standard, people's understanding of the shape of sand spots is unclear. Then the shape of the sand spot has any influence on the printing process, and how large the influence is. This article will explain to the reader in detail through experiments.

1. Experimental preparation

The PS plates produced by different manufacturers were selected to remove the photosensitive layer and the oxide film, leaving only the original grain shape, and then re-producing the PS plate under the same conditions of oxidation and coating. The difference in the printing properties of the samples was only Determined by the different sand morphology.

Specific approach: The domestic version. The imported version 1 and the imported version 2 were cut into a sample having a size of 30 cm x 32 cm, and the photosensitive layer was removed with a solvent. The solution was put in a boiling H3P04-CrO: solution for 3 minutes to remove the oxide film. Then under the same conditions for oxidation, wash and dry with the same coating liquid coating, drying at 90-100 °C temperature for 10 minutes. The UGRA82 test strip (with 21 gray scales) was used for exposure, developed according to standard conditions, and finally tested on the machine.

2. experiment procedure

(1) Detection equipment: SEM test was conducted with BSM-25G electronic scanning microscope of Beijing Scientific Instrument Factory, and the average roughness of the sand was measured with the British Taylor Surtronic 3+ surface roughness measuring instrument, using a German one-day NOVA95 printing plate (4kW iodine lamp) Exposure experiments were conducted using a centrifugal coater from Qufu Normal University to coat the photosensitive layer and weighed using a Swiss METTLER TOLEDO AEl00 electronic analytical balance.

(2) Detection method: After the exposed and developed test sample with the test strip is placed on the same rubber roller, the printing pressure during the experiment is 3-5 times the normal printing pressure, and the printing pressure of each part is guaranteed to be the same. Since the printing conditions are exactly the same, the experimental results are the results of comparison between the tested samples.

(3) Test items

1 Best printing time: Use UGRA82 test strip for exposure, develop according to standard conditions, and adjust the exposure time to achieve 3 levels of dryness after the development; the time of exposure is the best printing time.

2 The ability to print and restore: With the minimum number of dots reproduced as the number of dots, the finest Yin and Yang lines are the number of lines, and the smaller the number, the stronger the reduction ability.

3 Ink detection: compare the number of papers that have passed from the start of the start to the printing of qualified products, and observe every 10 shots.

4 Shutdown on dirty detection: stop at 20, 30, and 40 minutes when it is printed to 5000 copies. Inspect the blank parts of each sample with ink-reducing agent and record the time when the upper-dirty phenomenon has just appeared.

5 Printing process: The tested sample can print the number of printed products with the most qualified prints.

Experimental results

Experimental data is shown in Table 1, from which we can see:

(1) There are obvious differences in the number of screen lines for the three types of plates: the finest masculine reproduction of the domestic version. The Yinxian is 15um and 6um, respectively. The finest Yang and Yin lines reproduced in the imported version 1 are 10μm and 4μm, respectively. The finest Yang and Yin lines reproduced in the imported version 2 are 12μm and 6μm, respectively, indicating that the samples of the domestically-made samples were The resolution is worse than that of imported sand. The three-base sand photographs are shown in Figure 1, Figure 2, and Figure 3. Imported version 1 has a uniform and fine grain, and imported version 2 has a richer level, while the domestic version has a poor uniformity of the grain size and a large number of platforms. The experiment also shows that the reductive ability of mesh points and network lines is related to the shape of sand grains, and the finer the sand spot, the higher the reducibility. Because the more uniform and fine the sand, the more uniform the microscopic thickness of the photosensitive layer, the coating left by the subsequent exposure reaction and development will be more consistent, and the clearer the reduction in the dots and screen lines of the printed product. .

(2) The print length of the imported version 2 sand sample is significantly longer than that of the domestic version sand sample. Imported version 2 is not only uniform, dense and rich in the level of sand, small sand eyes in the large sand head, that is, multi-layer sand, multi-layer sand structure can significantly improve the specific surface area of ​​the plate. Experiments show that. Sand pattern can significantly affect the printing process, the richer the level of sand, the longer the specific surface area printing.

(3) It can be seen from the data of the best printing time that the shape of the sand has a significant effect on the printing time. It can be seen that when there is a bright deviation in the stencil process, if the PS plate is printed at normal time, the best printing plate cannot be obtained. Therefore, for the manufacturer, stable process parameters are the key. If significant changes are made to the stencil process, the user should be informed in a timely manner or marked on the package.

(4) It can be seen from the data on the shutdown time that the imported version 2 has the longest time in the multi-layered sand, which means that the sand has the best water retention performance. This performance can greatly reduce the chance of being dirty on the shutdown. .

To sum up, the Ps version of the base of the mesh to restore the ability of outlets. Printing process, best printing time. The speed of ink on the ink, and the shutdown of dirty and other performance will have a more significant impact. The finer the sand spots, the stronger the ability to restore the dots and the faster the ink is applied. The richer the level of the sand, the longer the printing process, and the less chance of stopping the dirt. Therefore, improving the sand pattern of the PS plate can greatly improve the printing quality. Only by strengthening the research and development of the high-level plate-grinding process and the entire plate-base treatment process can we provide users with better quality. More reliable PS version products.