The major factors that block the screen

The so-called screen blockage is the mesh at the edge of the pattern on the screen after the development. A layer of transparent, difficult to distinguish with the water film, it is difficult to use the residual film found by the naked eye to block the mesh, so that the slurry can not penetrate to Cloth up, causing this situation has the following factors.

(1) Sensitive Emulsion: The diazo photosensitizer in diazo photosensitive adhesive is greatly affected by temperature and humidity after being formulated into an emulsion, and it is easy to cause dark reaction for a long time. Hole plugged. Therefore, the sensitive adhesive should be prepared as much as possible, especially in the high-temperature quarters, to be used up in a short time.

(2) Underexposure: Insufficient exposure of the screen causes the photosensitive slurry remaining on the squeegee surface to collapse into the empty grid; when the printing surface is dried parallel downwards, the condition of the plugging network is less, and the condition of the vertical plugging and drying plug is more, during development, The squeegee of the screen is not recommended to be flushed with pressure water, and the hose is used for rinsing, and the excess water in the middle of the screen is sucked by the suction device.

(3) The density of the manuscript to the black is not enough: when the exposure is caused, light leaks through the light-shielding layer to the adhesive layer, causing cross-linking of light, blocking during development, and the density of the manuscript film is increased.

(4) Excessive photosensitizer: Diazo photosensitizer increases, the speed of photoreduction slows down, causing insufficient exposure, resulting in insufficient photosensitized cross-linking of glue, resulting in too much development of the glue, and the photosensitizing dose should be formulated in accordance with regulations.

Reprinted from: China Printing and Dyeing Network