Screen printing question and answer

1. What should be done before the net screen is made before the screen is stretched? What is included in pre-network processing?

A: The pre-grid treatment consists of roughening and degreasing.

A. Polyester (PET) weakly polar materials are roughened to add a porous, non-smooth surface. The treated PET web can increase the bonding area with the photosensitive material, thereby improving the adhesion of the photosensitive material on the web.

B. The degreasing of the screen on the screen is to remove oil stains, increase the affinity between the photosensitive material and the screen, and the number of screen printing, and reduce the pinhole on the photosensitive layer during the screen printing process.

2. How to reduce the average roughness (PZ value) of the surface of the photosensitive layer when making the screen?

Answer: 1) The PZ value is related to the plate making method. Simple plate-making method. Capillary plate-making method Photosensitive plate-making method. 2) The PZ value of the photoengraving process should be controlled from the following aspects:

a. After the adhesive is dried, the screen is placed flat in the drying cabinet with the printed side facing down.

b. The last time the squeegee should be on the printed surface, with the screen printing surface facing down when dry.

c. The increase in the number of times the photoresist is applied on the printing surface will help reduce the PZ value.

3, why do you have to completely dry the screen after coating the emulsion?

A: If there is slight moisture in the photosensitive layer, water vapor will refract the light during exposure, thus affecting the degree of cross-linking of the emulsion. In addition, when the photoresist is not completely dried, it will also hinder cross-linking, which will lead to defects such as pinholes, degumming, and decreased adhesion of the adhesive layer and the screen, and reduction of the resistance to printing, etc., resulting in the development of the photosensitive layer before exposure. The degree is crucial.

4, how to choose the screen exposure time?

A: Please use Ketutai special exposure ruler test. This slide rule is very simple to use. It takes only one exposure to get five exposure parameters. The correct exposure parameters must be in it.

5. What are the consequences of insufficient screen exposure and overexposure?

A: 1) Underexposure:

A, the thinning of the photosensitive layer is too easy to appear pinholes.

B, the edges of the pattern or wire are prone to sawtooth.

C. The number of screen prints dropped.

D. Screen recovery is difficult. Patterned shadows tend to appear on screens that have been removed from the film.

2) Overexposed:

A. The pattern will be distorted, the fine lines will be finer, the low-key meshes will be enlarged, and the highlights will be reduced.

B. Difficulty in unloading, and there is residue in the leaked part so that the ink does not mesh.

C. The template becomes brittle.

Therefore, before the plate-making, the exposure ruler must be used to determine the exact exposure time, so as to produce different requirements of the screen.

6. What are the quality problems caused by the pre-processed screen and the screened screen drying in the same oven? How to solve?

Answer: (1) The pre-treated screen has a high moisture content, and a large amount of moisture evaporates during the drying process, thereby reducing the degree of drying of the screen coated with the photosensitive resist and prolonging the drying time.

(2) The secondary water absorption of the photo-sensitive adhesive will make the photo-resist layer unable to dry out, so that it is difficult to ensure the accuracy of the exposure (shim) parameters, and the screen quality will fluctuate greatly.

(3) The solution is: separate drying.

7. Is a spot color ink formulated with a standard color or a standard color? why?

A: The preparation of spot color inks should be based on the reference color or the three primary colors, because this will ensure that the colors have a good hue, brightness and purity, and the formulated ink will be very bright and bright, and it will be closer to the red, green and blue in nature. The true color of the. The ink with the standard color is dark in color, inaccurate in hue, and not bright enough, because the standard color ink itself is a mixed color, so the spot color ink can not meet the three attributes of the ink.

8. What are the requirements for screen printing and printing processes in four-color dot printing?

Answer: (1) The tension of the four screens is the same (2) The screen is cut in the same direction (3) The size of the screen is the same size (4) The screen positioning is consistent. (5) The hardness of the scraper is the same (6) The angle between the scraper and the substrate is the same (7) The scraping pressure is the same (8) The scraping speed is the same.

9. How to calculate the width of the reproduced line when selecting a network?

Answer: Under normal circumstances:

Available formulas: 2d + M. or 3d (M = d) where d is the diameter of the screen mesh. M. The width of the hole for the wire mesh.

10, Please calculate, 12034 (T) wire mesh should be able to print fine lines?

Answer: 12034(T) Wire Mesh d=34 μm. = 45 microns

Formula: 2d+M 2×34+45=113 μm

Reproduce line width or dot diameter to 113 microns (ie 0.113mm) with a 12034(T) screen

When M. When >d (M+d) 2M. +d is (45+34) (2×45+34)

Dark tone point 79u High light point 124u

11. What is the composition of solvent ink? What is the role of each?

A: (1) Binder: It is a resin that mainly acts as a link to determine the smoothness, hardness, weather resistance, moisture resistance and other properties of the ink.

(2) Pigments: Determine the fineness, weather resistance, solvent resistance, and drug resistance of inks, and whether they contain heavy metals.

(3) Additives: Improve the printability of the ink.

(4) Solvent: It is used to adjust the viscosity, adjust the dry speed, increase the adhesion with the substrate, dissolve the resin as a linker and auxiliary agent, and disperse the pigment.

12. What are the five variables for screen printing?

Answer: Scraper hardness, mesh distance, printing speed, scraping pressure, ink suitability.

13, the ink is not stirred before adding the diluent right? why?

A: It is not correct to add diluent before mixing, because after the ink is subjected to external force (such as stirring), its viscosity will drop and dilute the thixotropic performance, so any ink must be thoroughly stirred after opening the jar to adjust the viscosity. .

14. What is the role of solvents in solvent-based inks?

Answer: (1) Dissolve the resin in the ink to make the adhesive. (2) Disperse pigments and solubilizers in inks to improve printability. (3) Dissolve and swell substrate, increase the adhesion of ink and substrate. (4) Adjust the viscosity to improve the printability of the ink. (5) Adjust the drying speed to meet the requirements of the screen printing environment.

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