What are the common problems and solutions of printing Ⅰ

1. The problem of sticky hands after printing glue

After the printing paste is printed and dried, there is a sticky phenomenon, which becomes more serious with the increase of temperature.

Reason: The main raw material of printing glue is acrylic resin, which is determined by the characteristics of the resin. If a harder resin is used, the problem of stickiness can be solved, but the adhesion force is seriously reduced. If the adhesion force is increased, a softer resin must be selected. , but the soft resin is easy to stick back.

Solution:

Use the printing glue anti-adhesive agent, add it into the printing glue and mix it evenly. After printing, the printing glue anti-adhesive agent can form a film on the surface, which does not affect the adhesion of the printing glue, and solves the problem of stickiness. question.

2. The solution to the phenomenon of jamming in the printing of flat screen fabrics

Reasons: The density of the bottom draft is not enough; the flat screen plate making operation process is improper; the quality of the printing paste is wrong.

Solution:

The manuscripts are currently produced by computer. The higher the black density, the better the shading effect of the graphic pattern of the negative. If the blackness is not enough, the shading effect will be worse, and the ultraviolet light will easily pass through, which will cause the mesh; the haze of the negative should be low. Completed, it is easy to cause excessive exposure time and cause blocking.

Improper development and curing process of flat screen plate making will lead to jamming. When developing, it should be taken into account that the ultraviolet light is transmitted from the printing surface of the screen to the squeegee surface, the printing surface is fully illuminated, and can be rinsed with high-pressure water; and the degree of cross-linking of the squeegee surface is smaller than that of the printing surface, and the adhesive film is not visible. When rinsing, it should be rinsed with the residual slurry of non-pressure water slurry to avoid the residual slurry from clogging the mesh. Before curing, a second exposure should be carried out to make the adhesive layer fully photosensitive and then apply the curing agent.

When printing, the slurry used contains impurities or undissolved particles that block the mesh, so that the color paste cannot be scraped out of the mesh during printing, so the slurry should be filtered to remove impurities before use. When making the coating adhesive, choose a good quality adhesive and a thickener with good compatibility, and the conjunctiva should not be too fast when scratching.

3. The process of generating pattern edges from clear to fuzzy

At the beginning of printing, because the fluidity of the paste is good, the doctor blade does not need a lot of force to cut the paste clean. With the continuous evaporation of the water in the glue, the slurry gradually thickens and the viscosity becomes larger. It is necessary to increase the particle size of the squeegee to cut off the excess slurry. Due to the increase in strength, the elastic deformation of the screen produces pattern displacement. With the disappearance of the force of the squeegee, the edge of the pattern on the screen printing surface will stick to the paste after the screen rebounds. During the second printing, These pastes migrate to the edges of the pattern, resulting in blurring of the pattern edges.

Solution:

(1) Use wire mesh with small elasticity, such as polyester mesh;

(2) Increase the tension of the wire mesh;

(3) Reduce the resilience of the wire mesh;

(4) Adjust the viscosity of the slurry at any time.

4. The reasons for the sharp corners of the pattern to become rounded and the loss of small dots

Since the slurry gradually thickens during the printing process, its fluidity becomes smaller. When passing through the mesh, the pressure of the squeegee must be increased to pass through the mesh. However, at the edge of the screen pattern, due to the cushioning effect of the photosensitive adhesive, the The squeegee cannot squeeze the slurry out of the mesh at any time, so that the slurry particles stay in the mesh to form a film, causing the mesh on the edge of the photosensitive adhesive to block.

Solution:

(1) Choose low mesh, single wire, thin wire mesh;

(2) The photosensitive glue should not be too thick;

(3) The slurry should maintain a certain fluidity at all times.