Several factors that cause the screen to block

Several factors that cause the screen to block

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The so-called screen jam is the mesh at the edge of the pattern on the screen after development. A layer of transparency is difficult to distinguish from the water film. It is difficult to block the mesh with the residual film layer found by the naked eye, so that the slurry cannot penetrate to the mesh. On the cloth, there are several factors that cause this situation.

(1) Photosensitive emulsion: The diazo photosensitive agent in the diazo photosensitive adhesive is greatly affected by temperature and humidity after being formulated into an emulsion. It is easy to cause a dark reaction after a long time, and it is difficult to rinse due to coating on the screen. The hole is blocked. Therefore, the photosensitive glue should be prepared in an appropriate amount, especially in the high temperature quarter, it should be used up in a short time.

(2) Insufficient exposure: insufficient exposure of the screen causes the residual photographic slurry to smash into the empty grid; when the printing surface is parallel to the parallel drying, the plugging is less, and the vertical drying of the plug is more. The screen surface of the screen is recommended not to be flushed with pressurized water, but rinsed with a water pipe and the excess water in the middle of the net is sucked up by a water absorbing device.

(3) The film is not dense enough to black density: When exposure is caused, light leaks through the light-shielding layer onto the adhesive layer, causing photo-crosslinking, causing clogging during development, and the density of the base sheet is increased.

(4) Excessive photosensitizer: the increase of diazo photosensitizer, the slowing of the photosensitive speed, causing insufficient exposure, causing insufficient photosensitization and crosslinking of the glue, resulting in too tender glue during development, and the photosensitive dose should be prepared according to the specified requirements.