Six, matching the developer and its optimal concentration

There are roughly two types of developer materials used with the PS plate: solid state developer and liquid developer concentrate. Regardless of which type of developer material is used, the developer must first be adjusted to a suitable concentration before being used for development.

Different types of positive PS plates have their associated developing materials. To obtain the best development results, try not to use other brands of developer. Otherwise, it may result in opaque or excessive development.

The development medicine has a shelf life. When it is used, its production date should be confirmed. Expired development medicine should be avoided. The shelf life provided by most manufacturers is one year, but try not to store the developer for too long.

The manufacturer will also provide the corresponding ratio of formulated developer. For example, some grades of developer powder in the instructions for use recommend that "a bottle of developing powder is dissolved with 5:1 warm water to form a concentrated solution, and when developing, the diluted solution is diluted 1:6," here said 1:6. The dilution ratio is widely used by the manufacturer after extensive experiments. For the user, it should be used in accordance with the manufacturer's recommendations, and the proportions should not be arbitrarily changed.

The solid state developing material is a mixture prepared from various components such as a developer, an inhibitor, a wetting agent and the like. For the directly compounded developing powder, the specific gravity, particle shape, and size of each component are different during transportation. Bumps, so that the small-size, high-specific components concentrated distribution in the bottom of the container. Therefore, when the developing powder developer is directly taken, the developer powder should be fully mixed.

When diluting the formulated developer with the developer concentrate, attention should also be paid to the mixing problem. After the concentrate was left standing, some of the poorly soluble components settled to the bottom of the container due to the effect of gravity, and the components in the solution were not evenly distributed. Experiments have shown that only the top solution is formulated as a proportioning developer and its development effect is not good. Therefore, when taking the concentrate to prepare the developer, the mixing problem cannot be ignored.

7. Use purified water as liquid for water

Under normal circumstances, there is no special requirement for the water used to configure the developer. The user is basically using tap water or deep well water. The developer is an alkaline solution with a pH of about 13. The scale theory tells us that sodium silicate, which is one of the components of the developer, is itself an easy-to-scale material. Together with the combined action of calcium, magnesium and other metal ions introduced by water, it is more likely to cause alkaline developer. Scale. The direct effect is to cause plugging of the developer jets, causing the developer to spray unevenly, or to make the development roller calcified, thereby affecting the development quality. Therefore, it is best to use deionized water as the dosing water to slow down the fouling process of the developer.

Eight, control the appropriate development temperature

Heat is required for hydrolysis, salt formation, and salt dissolution in the developing process. If the temperature of the developer is too low, the heat required for the development process cannot be provided, which will prevent the development from proceeding smoothly; if the temperature of the developer is too high, the unexposed image portion will be dissolved. Theory and practice show that, when the temperature exceeds 30°C, the binding force between the photosensitive resin and the film-forming resin in the photosensitive layer is weakened, and the resistance to alkalinity decreases. Therefore, an appropriate development temperature is one of the prerequisites for ensuring good development quality. Under normal circumstances, it is appropriate to control the temperature of the developer at 25°C±1°C.

Nine, determine the development time

According to the accurate exposure time measured in the front, the printing plate is exposed, the machine is displayed, and the gray scale segment is observed. When the third ladder is absent, the fourth ladder is reserved, and 3% of the outlets are guaranteed, and 97% of the outlets are not pasted. , is the appropriate development time. If it does not meet the standards, re-exposure, and adjust the display time according to the last development until it is appropriate.

Ten, maintain a suitable developer concentration

After many times of development of the developer, the active ingredients in the developer are continuously consumed. Together with the effect of the photosensitive layer that is continuously dissolved in the developer, the developing ability of the developer becomes weaker and weaker, so that the developing requirement cannot be satisfied. Aging has occurred.

In practical production, it is possible to use one piece of development and control strip tracking test for each development of five plates, and then add a suitable amount of developer according to the actual situation.

When severe aging occurs, new fluids should be replaced promptly. The number of developed plates can be changed once in two days, and the number of developed plates is larger. For example, 100 or more plates are replaced daily.

Eleven, the correct way to eliminate dirty

The elimination of a certain brand of liquid may not be suitable for all PS versions. When they do not match, it may cause the dirt to be dirty when printed.

Elimination of dirty fluid should not be too long on the PS plate, otherwise it will also lead to dirt on the printed area.

Twelve, protective adhesive coating

The function of the protective glue is to protect the blank part from oxidation, so it should be as thin and uniform as possible during coating. If the coating is not uniform, it will cause the printing to be easy to get dirty, but if the coating is too thick, it will cause the graphic part not to be inked.

To sum up, in order to achieve the ideal quality of drying, we should conduct scientific analysis and strictly control the factors that affect the various aspects of the drying process, so as to reduce the waste printing rate and improve the quality of printed products. And printing efficiency.

(author/Wang Huaming)

<China Packaging>