PS version usage introduction

PS version has the advantages of high resolution, good dot recovery, high printing rate, etc. There are four types of proofing, color printing, text, and newspaper printing to meet the different needs of customers. Each kind of PS plate is used in production Different technologies, process parameters, and raw materials determine their unique technical performance. Correctly mastering reasonable use can bring great help to printing production, and some explanations are given below on their use.

1 printing principle

1.1 Multiple exposures Less visible light has an effect on the network due to its refraction effect. First, the photosensitive layer around the dots becomes thinner and then lost, causing the dot to shrink. However, the appropriate reduction is necessary for printing, and it can be compensated. The loss to the text and the field is insignificant.
The developer exhibits a certain degree of alkalinity and dissolves in the photosensitive layer of the plate, and it occurs on all surfaces of the dots, lines, and solid surfaces. A slight loss will cause a slow ink-on phenomenon, and if the loss is too large, it will be difficult to apply ink. The color becomes lighter, uneven, and the resistance to printing is extremely low, seriously affecting normal production.

L.2 Data control The photographic performance of the PS version is affected by many factors such as the base, production process, raw materials, storage conditions, etc. The difference in the same batch of products can be controlled to be basically the same, but there are certain differences in the products of different batches. Therefore, each batch of products should be tested and confirmed.
The aging of the light source of the printing machine, the fluctuation of the voltage in the morning and evening, and the change of the developing conditions all affect the performance of the sensitization performance of the PS plate. Therefore, when certain factors change, the conditions for use should be adjusted appropriately to achieve the best use effect. .

1.3 change with the printing content When the printed matter has a large area of ​​network cable composition and the number is not large, you can use color printing plate and appropriately shorten the exposure time to ensure a good network of points; if the basic printed matter consists of text, field block, the required number of printing When larger, the text version can be selected and the exposure time can be appropriately extended to reduce the dirty condition and ensure smooth delivery.

2 actual operation control

2.1 pumping PS version of the main features are a good dot reduction and high resistance to printing, due to the use of imported PS plate base, flatness is very good, if the printing plate suction effect is not enough or air humidity is too large, the customer is easy The film was brought into close contact with the layout, so that the residual air could not be completely removed. In the case of large size, it is more likely to occur. The typical symptom is that the unexposed PS plate layout is even, and the pattern of different shades can be observed at the end of the pumping process. As the exposure progresses, the pattern gradually deepens, and after a certain degree, it gradually becomes shallower. After the development, you can feel the depth of the layout. The methods to overcome are mainly the following:
a. The film is placed on the PS plate and the air is first expelled from the center to the surroundings by hand, reducing the possibility of forming a local air layer.
b. Extend the evacuation time, if there are obvious patterns after the end of the pumping. The explosion should be stopped immediately and a second evacuation should be performed.
c. Keep the air humidity in the printing room in the proper range.

2.2 The Exposure Exposure and the Development The effects on the PS layout are very similar, so we are now discussing the impact of the exposure on the layout under fixed development conditions (according to product recommendation conditions).
The general principle of exposure: to ensure that the loss of outlets within the scope of the requirements, but also to minimize the amount of residual photosensitive emulsion on the layout, reduce the possibility of upper organs. The proofing version has high requirements for the restoration of outlets. It must ensure that 2% of the outlets are complete and complete, but the requirements for the upper scum are low and the number is small. Each clean layout can be done. Therefore, the exposure only needs to reach 0.45, that is, two steps in the exit.
Color printing plate, not only to ensure the necessary network point reduction and resolution, but also to ensure the smooth progress of the entire printing process, do not allow frequent visits to the dirty shutdown, so the exposure needs to reach 0.60, that is, three steps back.
Newspaper edition has a very high timeliness requirement, but it has lower requirements for the reproducibility and resolution of outlets, so the exposure can reach 0.75, that is, four steps for exit.
The amount of exposure to a user or a batch of products is not entirely irrelevant; it is set based on comprehensive consideration of factors such as film, network conditions, printing quantity, and quality requirements. The general situation is to do under the basic principle conditions. Half-grid adjustments.
Different brand printers with the same power and lamp pitch, or two sets of printers of the same brand, although they may use the same lamp, their exposure efficiencies are quite different. Therefore, there is a big difference in exposure time. The method of establishing the correct exposure time can only be through the actual measurement of the test strip, which is based on data rather than experience. There have been customers who reflected that our exposure time has never changed. Why it is getting worse and worse, but in fact it will never change is the biggest mistake.

2.3 Development For a PS plate, the development conditions have been determined, that is, the alkali resistance of the photosensitive resist is not determined. Therefore, each PS plate has a theoretical optimal development condition. In use, should be in accordance with the manufacturer's recommended working conditions, in order to ensure that the PS version has a good performance.
The easiest way for the user to actually use it is to fix the developing conditions. This requires confirmation of the operating status of the developing machine:
a. Whether to prepare the correct concentration in accordance with the prescribed ratio: 14 a l6g/l
b. The developer liquid temperature control: 20 °C a 25 °C.
c. Developer speed debugging: 20 seconds - 25 seconds d. Addition of developing roller aging.
Excessive development is a relatively common phenomenon. This will directly lead to the loss of dots and the thinning of the photosensitive layer. As a result, colors appear to fade in the printing process, difficulties in inking, and the printing life are greatly reduced. Sometimes over-development results in the destruction of the hydrophilic layer of the layout. Dirty.
Through the observation of the test strip can also determine the correctness of the development conditions, just to observe the remaining ash ladder to just unrecognized number of ash ladder called the number of contrast cells. The number of contrasts in the "SINCERE" PS version should be between 5-7. If it is significantly worse than this value, such as 5-6 or 8-9, then under- or over-development will occur.

2.4 Others

2.4.1 Getting the correct picking method is to lay the PS box horizontally and take it one by one, with the top photographic adhesive facing inward. The actual use of the venue is limited by the way, are placed upright, which requires the pick must be taken together when the two positive PS version together, otherwise it is easy to cause layout scratches, the photosensitive layer is rubbed off, In severe cases, the base is scratched and the sand is damaged, which affects the normal use.

2.4.2 Temporarily save the unpacked PS plate or take out the plate that is not used or has been plated waiting for the machine. Care should be taken to avoid light preservation. Otherwise, the effect of slow exposure will make the outer layer of the plate produce a thin, naked eye. It is difficult to view the light brown coating, resulting in the loss of the Chinese version of the network, a serious reduction in the printing life, difficulty in inking and so on.

2.4.3 Rinsing Many users do not pay enough attention to this work. The amount of washed water is small, some water is not flushed or the water pressure is not completely washed. The developer that remains in the layout continues to be in the process of waiting for the printing plate to reach the machine. In the event of a serious effect, the blank part will give rise to the loss of small white point of erosion and the part of the network cable, and it will affect the use.

2.4.4 The purpose of rubbing the rubber is to protect the surface of the plate that is not on the machine or halfway down. It is because the hydrophilicity of the plate is first met that the adsorption of the ink will be rejected. Once the water is dried, the ink stains It will also absorb the layout, and it is irreversible, unless it is scraped off, so the glue should be even when there is no missing, and the amount can not be too much, otherwise it will affect the ink absorption.
The stencil should be blown dry, and it has been observed that the user did not wait for the stencil sheet to dry, that is, to overlap, and the stencil sheet was glued.

2.4.5 Bake Plate The purpose of baking plate is to make the photosensitive layer of the plate to be cured so as to increase the resistance to printing force. Therefore, besides choosing the proper baking time and humidity, there are other areas that need attention.
a. baking solution, baking solution should be close to neutral, if acidic, after 250 °C, about 10min baking, easy to make the base corrosion, replace the high-quality baking solution, you can eliminate.
b. Dirty spots, before the baking version must be completely removed dirty, otherwise the baking plate after curing, can not be ruled out, but if due to exposure, improper control of the development process, the residual thin layer of photosensitive liquid can not be identified with the naked eye, can not repair dirty Remove, directly on the machine can be used normally, but the ink absorption after baking enhanced and lead to large dirty. Therefore, the PS version to be baked can be properly increased exposure, development, to ensure that no dirt appears.

2.4.6 Environmental Printing Environment High-quality printing requirements are issues that must be considered, especially the proper temperature and humidity, which helps to maintain the layout of the water. If the temperature is too high or the humidity is too low, the layout water will evaporate quickly and there will be a large chance of scavenging. If the amount of water is increased, ink emulsification will occur and the dots will be unclear. If the temperature is too low, the ink will have poor affinity with the plate and the ink volume must be increased. Or increase the pressure, resulting in increased wear and reduced printing life.