PS version of a three-dimensional perspective

In order to allow readers to perceive the first-line issue of the PS version sensibly, we adhere to the practical principle of first-line attack and conducted a questionnaire interview with the industry's first-line practitioners. They are all technical personnel active in the production line and they exist in the PS version. The problems are more familiar with. At the same time, they also interviewed several experts who have been engaged in printing for many years and hope that their experience can give some readers some inspiration. The guests who participated in this first-line survey were: Mr. He Jianchuan of Beijing Hualian Printing Co., Ltd., Mr. Yang Yong of Suzhou Daming Color Printing Factory, and Mr. Zhang Bo of Beijing Yuhai Printing Factory. At the same time, we also visited the printing experts Ning Chengzong and Ms. Wenyu Wu.

One-line realism

PS version as a major printing plate, in the purchase should pay attention to what the problem? What basic performance should the PS version meet?

The purchase of the PS version is a key link because the quality of the PS version itself fundamentally affects the quality of the plate. Mr. Zhang Bo believes that the PS version should use brand products with a certain reputation. In the purchase, it is necessary to check whether the sand grain processing of the PS version is satisfactory. It should also pay attention to whether the dot reproduction and the resistance force can meet the requirements. It is generally believed that when purchasing the PS version, attention should be paid to selecting the PS version that requires printing, good developing performance, accurate cutting size, good dot reducibility, high printing resistance, good ink balance during printing, and difficulty in getting dirty.

PS version in the handling and storage and transportation should pay attention to what the problem?

Mr. He Jianchuan mentioned that the PS version should not be handled rough, and should not be stamped on the PS version. The number of stacking layers should not be too large. It cannot be flexed. When holding (especially a single version), both hands must hold the two corners of the PS plate. , Be careful not to bend the plate, do not allow the PS plate to collide with the machine or other hard objects to avoid scratching the photosensitive sand surface of the PS plate.

The printing quality of the PS plate has a lot to do with the printing and developing operations. What should you pay attention to during the printing and developing process?

When printing, it is necessary to master the best photosensitive time of the PS version, and to fully understand the PS version of the performance indicators. When developing, the developer concentration should be moderate, must not be too strong, resulting in the loss of graphic and text; or too light, the development is not transparent, the bottom black when printing; the development speed should also be moderate.

Why does the PS version dot often appear in the printing process that is not true, does not reflect the subtle part of the image, and the blank is not clean? How to solve?

There are three reasons why the dots are not true: the PS plate has no vacuum gas-guiding layer; there is dust, dirt, etc. between the plate-making film and the PS plate; there are problems with the plate-making film.

The main reason for the loss of the subtle part of the image is that the exposure time is too long, and the reason that the blank part is not clean is mainly due to insufficient exposure time.

To solve the problem of unrealistic outlets, Mr. Yang believes that starting from checking the quality of the film, the outlets on the printing film should have sufficient blackness, and the outlets on the printing film should be transferred to the printing plate. The covered parts (nets) transmit light, causing the photosensitive layer of the plate to be sensitized.

What is the cause of the layout? What is the solution?

Mr. He Jianchuan summed up several main reasons for the lack of post-printing layout:

1) Insufficient exhaustion causes hair loss. The solution is: to repair the vacuum pump and related parts and components of the printing machine, so as to ensure that the vacuum degree reaches the printing requirements;

2) The edges of two adjacent films cannot be overlapped when they are impositioned, so as not to cause the layout to be false. The solution is: before the sun, check whether the film overlaps, and whether there is any foreign matter between the film and the PS plate.

3) The film film is reversed, or the human misspelling causes the layout to become imaginary. The solution is: before the sun, check whether the film surface of the film is correct, and whether the film film is reversed during the imposition.

Since different PS versions have different development times and conditions, it is best for the user to use the manufacturer's recipe. When selecting a plate, pay attention to the surface quality. When developing, you should understand the type of developer, how to use it, temperature conditions, and other factors. If the temperature of the plate in winter is low, the temperature of the developer is liable to decrease. If the quality of the plate is poor, the plate should be replaced, and the developer should not be used to remedy the problem.

PS printing plate in the printing process, the layout of the non-graphic parts from the dirty, graphic wear and tear, plate scratches on what causes it? How to avoid these problems?

It was learned from the questionnaire interview that the cause of the PS plate wear was mainly caused by the following problems: excessive use of the cleaning solution (emulsion) to wipe the plate, improper pressure of the printing plate, and protrusion of the blanket.

The reason that the non-graphic part of the layout is dirty is that the exposure time is insufficient, no protective glue is applied, the ink is not balanced, and the ink is emulsified.

Scratches in the printing plate are caused by accidental scratches due to the unprotected surface of the plate and the plate (upper plate). During the development, the photosensitive layer cannot be completely removed, and the sand spot becomes lighter and the hydrophilicity becomes weaker, which also leads to dirtiness.

The solution to plate wear is to redeploy the fountain solution and check the pH and printing pressure. If it is a web, remove a few layers of paper mixed with sand and clean the film.

In the printing process, what is the cause of the low printing resistance? How to improve the printing plate's resistance to printing force?

The strength of the PS plate is not only determined by the plate itself, but also depends on each operation in the printing and printing process. There are many factors that affect the printing plate's resistance to printing force. For example, the plate material has a light grained, thin and uneven oxide layer; before running, overexposure, over development, roasting paste deterioration, baking temperature is too high, and the baking time is too long. Etc., strong printing plate cleaner or roller cleaning agent was used in the printing, the printing pressure was too large, the pressure of the printing plate and the blanket was uneven, and the printing roller and the blanket were uneven, and the printing roller and the rubber blanket were aged; The liquid concentration is too large to corrode the printing plate; the printed paper is rough, falling powder, and hair loss; the ink ink layer is too thick and the ink particles are thick.

The front-line technicians interviewed emphasized that in order to improve the printing plate's resistance to printing, the correct exposure time, developing method and operating procedures must be mastered in order to achieve the best use of the plate. For example, under the standard conditions of development; preparation of the appropriate developer, pay attention to the development time; do not use inappropriate drugs; reduce the number of wiping; use of soft cleaning agent; adjust the printing pressure.

The printing plate is not well inked at the beginning of printing. How to deal with it? What happens when the photosensitive layer peels off and separates?

The main reason why the printing plate was badly inked at the beginning of printing was that the specified protective glue was not used, the protective glue was too thick, and the glue was not uniform; the printing plate ran out of light, and the graphic part of the oleophilicity was reduced; the protective glue was too thick, too much, etc. Caused. The bad ink in the middle of printing is mainly caused by too much of the glue in the fountain solution.

The peeling and peeling of the photosensitive layer of the PS plate is mainly caused by the problem of plate protection, poor storage, etc. If it is caused by the adhesion of chemicals (strong acids, strong alkalis, etc.), it should be adjusted. If it is a matter of plate material, it should be consistent with the manufacturer. Exchange.

How to strengthen developer management?

Mr. He Jianchuan believes that the first preparation of the developer must be reasonable, too thick or too thin will have a great impact on the development effect. In the storage of developer, attention should be paid to the effect of light, temperature, and humidity on the developer. For example, in the winter season, if heating equipment such as gas is used, the concentration of carbon dioxide in the room will increase, causing the developer to deteriorate, so it should be used as much as possible. Carbon dioxide heating equipment.

Expert point of view

The above is a preliminary discussion of front-line technicians on some of the practical problems encountered in the PS version and the printing process. In order to analyze and solve the first-line issues of the PS version from a deeper level, we also interviewed Ning Chengzong and Yu Wenxuan. As an old expert who has worked in the printing industry for decades, the understanding of the front-line issues of the plate making is undoubtedly profound and thorough. They have accumulated a wealth of theoretical and empirical printing techniques and their views through years of technical services. Has a certain representation.

1) Procurement

The purchase of the PS version is a smart way to recognize the price trap, except for a few quality-assured brand products such as Huaguang, Fuji Starlight, Starlight, Jielong, Momentum, and Korda. The grades are much the same, the difference between the plate itself and the photographic performance is not great, but the quality stability is slightly different. Although the general enterprises are not very demanding on media, they should not think that the lower the price, the better. For companies that have special requirements on speed, such as newspaper printing companies, they must pay attention to the problem that many PS manufacturers do not improve their raw materials, but instead use raw materials to reduce the amount of photosensitizers. The purpose of the degree is that although the speed of light is increased, the resistance to printing is low, and the alkali resistance is also reduced.

2) Keeping

The most important issue in the storage of the PS version is to avoid light, but also to pay attention to moisture, alkali. In general, the PS version is well-preserved, shelf life can reach 2 to 3 years, and resistance to India will not change greatly with time. The consensus period of the industry's printing plate warranty period is 1 year. The fundamental reason is that many domestic manufacturers do not regulate the management of the plate material, and the PS version is affected by the environment. In order to avoid the controversy, the PS plate production enterprises generally have 1 Year is the preservation period. This period is actually more reasonable.

3) Light source

The selection of the light source in the printing plate is a noteworthy issue. The iodine-deuterium lamp is a light source suitable for printing, which has high luminous efficiency and can be used continuously. The wavelength of its emission spectrum is distributed in the range of 350-450 nm to 417 nm. It is the highest peak and is effective for most printing plate photosensitive layers. The ultraviolet light emitted by this light source is strong. When using it, a protective cover or curtain is made of an opaque material such as artificial leather to prevent the direct sunlight from damaging the operator's eyes.

4) Resistance to force

There are many influencing factors concerning the resistance force of India, including the quality of the plate itself, paper, ink, and printing pressure. The PS plate manufacturing technology is more important. From the current point of view, the fundamental reason for the poor resistance of domestic PS plates is that the removal of electrolytic fogging and oxidative fogging is not very thorough. The PS plate is also a relatively large factor; in addition, the adjustment of machine pressure It is also very important that experience shows that with different pressures, the printing plate resistance is significantly different. In addition, the acidity and alkalinity of paper and ink also affect the printing plate's resistance to printing.

5) Inking performance

The experimental data show that the change of the sensitizer content in the sensitized adhesive has a great influence on the ink performance. This shows that the ink performance and the sensitized adhesive are of great concern. Excessive resin content or poor resin quality can also affect the ink performance. However, the amount of photosensitizer is not always good, but the photosensitivity is decreased when the content is high. Therefore, it is very important to realize the rationalization and scientification of the ratio of resin and photopolymer.

6) The network is not real

The two teachers analyzed that apart from the external factors that led to the misrepresentation of the network, there was also a problem with the air-guiding layer, which was crucial to eliminate the network points. If the outer periphery is very real, the remaining air in the middle will cause light refraction to occur. Newton's ring caused damage and loss to small outlets, resulting in false outlets. At present, the main method to solve this problem is to solve the problem by twice drawing a vacuum or applying a surface gas guide layer on the PS plate. There are also many ways to form a rough surface gas-guiding layer. Generally, a small layer of transparent particles is sprayed on the surface of the PS plate. These small particles are insoluble in water but soluble in an alkaline liquid and have no effect on the development. The purpose of adding a wool surface gas-guiding layer is mainly to solve the Newton ring problem, which is not only fast but also very effective.

7) Dirty layout

The dirt on the layout mainly occurs in the process of exposure and development, that is, the photosensitive adhesive is not completely removed, in addition, the photosensitive adhesive itself can also cause the layout on the surface dirty, such as the problem of returning blue, traces of insoluble material in the photosensitive adhesive deposited on the layout caused by blue Seriously, it will cause viscera. Off-page is generally caused by the PS version body performance, but uneven or excessive machine pressure will result in off-page generation.

At present, relevant domestic standards have been issued, and experts recommend that each factory should develop the corresponding plate-making process according to its own situation.