Sun Photo Quality Control for PS Plate (1)

Shaiban is the link between prepress technology and proofing, printing process. It needs to faithfully transfer the original graphic information to the PS plate; at the same time, it should make the graphic part hydrophilic and blank part hydrophilic, and make the printing The plate can withstand the enormous long-term pressure between the rollers without changing its hydrophilic properties.

At present, although some printing plants have CTP plates, the utilization rate is still not high, and most printing plants still use the traditional printing methods. Due to the more traditional printing methods, the quality control is more difficult, and many printing The factory often neglects the quality control of the printing section, which leads to the impact on the printing quality and reduces the printing efficiency.

When we manufacture the PS version, we always hope that the sun-dried outlets will be strong and smooth, and the blank part of the printing plate will be clean and free of dirt, and the graphics and text will have a good lipophilicity.

In production, we often encounter the following problems:
1, PS version outlet virtual halo, false, printing color instability.
2. The loss of high-gloss small dots is serious, the printed image is not smooth, and the flat screen is uneven.
3, blank parts more than dirty, eliminate long dirty time.
4, 10% of the following flat-screen drying.
5. The graphic part is not inked.
6, printing plate printing rate is low, can not reach the PS version should be printed.
7, printing plate easy to dirty.

Although the above problems are related to the printing pressure, the use of fountain solution, and the performance of the blanket, most of the troubles are caused by the drying of the PS plate.
Since the occurrence of any failure in printing is not caused by a fixed reason, the operation specification and data standard for each process will help reduce the occurrence of failures.

When you already have a good PS version, if you want to make a PS version that meets quality requirements, you need to have the following conditions:
1, constant light efficiency, uniform illumination.
2. Shaiky glass has no scratches, cleanness and transparency.
3, suitable suction time, vacuum degree is good.
4. The density of the original film meets the standard.
5, the exact exposure time 6, the matching developer, the appropriate development concentration, the development temperature.
7, the appropriate development time.
8, the matching elimination of dirty fluid, the correct way to eliminate dirty.
9, the protective glue coating is uniform, thick and thin.

If we can control each of the above steps one by one and develop good operating practices, we will greatly improve the quality of the PS version.

First, the appropriate form of light

For the same brand of PS version, you must ensure that the total exposure is constant, when the lamp is used for too long, the light efficiency will be reduced, the exposure will be insufficient, need to pass the test to increase the exposure time, in order to stabilize the total exposure, Or replace the lamp.

Different brands of printing machine, the light uniformity is not the same, when the light uniformity is poor, it is easy to lead to different shades of printing plates, especially when drying flat network is very obvious.

Second, the appropriate original film.

The printing plate is usually a violet light source or ultraviolet light source with a wavelength of 400 μm. The penetrating power is strong. In order to completely transfer the original negative film web point to the printing plate, it does not generate the photosensitive layer in the future graphic part. Photochemical reactions require:

1, the original film density in the field to reach 3.5 or more, otherwise it will easily lead to 5% of the following points lost, the network is not clean

2. The fog level of the original film should be low and should be less than 0.05, otherwise it will affect the density contrast on the printing plate.

3, the original film should be clean and dirty, otherwise it will give the printing plate dirty.

The original film does not use the collage tape as much as possible. For stitching, it is recommended to use glue, especially the dot film. At the same time, there must be no boundary phenomenon between the film and the film. In this way, the film and the PS board can be closely combined to avoid light scattering. Caused by the phenomenon of network points, if you use the tape collage, the distance between the tape should be greater than or equal to 7mm. Otherwise, it will cause the network to dry up.

(to be continued)