In order to allow readers to perceive the first-line issues of the PS version emotionally, we uphold the practical principles of the first-line attack and conducted a questionnaire interview with the first-line practitioners in the industry. They are all technical personnel who are active in the production of the frontline. The problem is more familiar. At the same time, we also interviewed several experts who have been engaged in photocopying for many years, hoping that their experience will bring some inspiration to the readers. The guests who participated in this front-line survey were: Mr. He Jianchuan of Beijing Hualian Printing Co., Ltd., Mr. Yang Yong of Suzhou Daming Color Printing Factory, Mr. Zhang Bo of Beijing Yuhai Printing Factory. At the same time, we also visited the printing experts Ning Chengzong and Tong Wenfu.
First-line realism
Author: PS version is a kind of main plate material in printing, what problems should be paid attention to in purchasing? 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 fundamentally affects the quality of the plate making. Mr. Zhang Bo believes that the PS version should use a brand product with a certain reputation. In the purchase, it is necessary to check whether the PS version of the sand mesh treatment is ideal, and also pay attention to whether the dot reproduction and printing resistance can meet the requirements. It is generally believed that when purchasing a PS version, you should pay attention to selecting the PS version that requires good printing, good development performance, accurate cutting size, good dot reduction, high printing resistance, good ink and water balance during printing, and not easy to get dirty.
Author: What issues should be paid attention to in the handling and storage of PS version?
Mr. He Jianchuan said that the PS version must not be loaded and unloaded, and should not be stepped on the PS version. The stacking layer should not be too many. It should not be bent with force. When holding it (especially the single version), both hands should hold the two sides of the PS version. , Be careful not to bend the plate, do not let the PS version collide with the machine or other hard objects to avoid scratching the photosensitive sand surface of the PS version.
The author: The printing quality of the PS version is very much related to the printing and developing operations. What should be paid attention to during the printing and developing process?
When printing, we must master the best photosensitive time of the PS version, and at the same time fully understand the various performance indicators of the PS version. When developing, the concentration of the developing solution should be moderate, and it must not be too thick, causing the loss of graphics and text; or too light, the development is opaque, and the background is black when printing; the development speed should also be moderate.
The author: Why does the PS version of the dots often appear in the printing process, which can not truly reflect the subtle parts of the image, and the blank parts are not clean? How to solve?
There are probably three reasons for the false dots: the PS version has no vacuum layer; there is dust and dirt between the plate-making film and the PS version; there is a problem with the plate-making film collage.
The main reason for the loss of fine parts of the image is that the exposure time is too long, and the reason for the blank part is not clean is mainly caused by the lack of exposure time.
To solve the problem of false dots, Mr. Yang Yong believes that the first step is to check the quality of the film. The dots on the printed film must have sufficient blackness. The dots on the printed film must be transferred to the printing plate. The covered part (dot) transmits light, causing the photosensitive layer of the printing plate to become photosensitive.
Author: What is the reason for the false layout? What is the solution?
Mr. He Jianchuan summarized the main reasons for the lack of layout after sun exposure:
1) Insufficiency caused by poor ventilation. The solution is to overhaul the vacuum pump and related parts of the plate-making machine to ensure that the vacuum degree meets the requirements of the plate-making;
2) During imposition, the edges of two adjacent films must not overlap with each other to avoid false drawing, which may cause the layout to be false. The solution is to check whether the film overlaps before sun exposure, and whether there is foreign matter between the film and the PS version;
3) The film medicine film is reversed, or artificial misspelling causes the layout to be false. The solution is to check whether the film surface is correct before drying and whether the film surface is reversed during imposition.
Since different PS versions have different development times and conditions, users are advised to use the formula provided by the manufacturer. When choosing the printing plate, pay attention to the surface quality. When developing, you should understand the type of developer, the method of use, the temperature conditions, and other factors. If the temperature of the printing plate is low in winter, the temperature of the developer is likely to drop; if the quality of the printing plate is poor, the printing plate should be replaced, and not remedyed with the developer.
The author: During the printing process of the PS version, the non-graphic part of the layout is dirty and the graphic part is worn. What is the cause of the scratches on the printing plate? How to avoid these problems?
According to the questionnaire interview, the cause of the partial wear of the PS version is mainly caused by the following problems: excessive use of cleaning fluid (emulsion) to wipe the plate, improper pressure of the printing cylinder, and partial protrusion of the blanket.
The non-graphic part of the layout is dirty due to insufficient exposure time, unprotected glue, unbalanced ink and ink, and ink emulsification.
There are scratches on the printing plate due to the lack of protective glue on the plate surface, or accidental scratches when taking the plate (upper plate). The photosensitive layer cannot be completely removed during development, and the shallow sand and weak hydrophilicity can also cause staining.
The solution to the abrasion of the layout is to re-adjust the fountain solution and check the pH and printing pressure. For roll paper, remove several layers of paper mixed with sand and clean the film.
Author: In the printing process, what is the reason for the low durability? How to improve the durability of the printing plate?
The PS printing resistance depends not only on the plate material itself, but also on every operation in the printing and printing process. There are many factors that affect the durability of the printing plate, such as the plate has a shallow sand mesh and a thin and uneven oxide layer. In the printing, strong plate cleaning agent or cylinder cleaning agent is used. The printing pressure is too large, the pressure between the printing plate and the blanket is uneven, and the plate roller is close to the plate and not flat, and the plate rubber roller and blanket are aging; If the concentration of the liquid is too large, it will corrode the printing plate; the printing paper is rough, powdered, and fluffed; the ink layer is too thick, and the ink particles are thick.
The first-line technicians interviewed emphasized that in order to improve the durability of the printing plate, it is necessary to master the correct exposure time, development method and operating procedures in order to achieve the best use of the plate material. For example, develop under standard conditions; prepare proper developer and pay attention to developing time; do not use inappropriate drugs; reduce the number of wipes; use a mild cleaning agent; adjust printing pressure, etc.
Author: At the beginning of printing, the printing plate is not well inked, how to deal with it? What should I do if the photosensitive layer peels or detaches?
The main reason for the poor printing ink on the printing plate at the beginning of printing is that the designated protective glue is not used, the protective glue is too thick, and the rubbing is uneven; the printing plate runs out, the lipophilicity of the graphic part is reduced; the protective glue is too thick, too much, etc. Cause. Poor inking in the middle of printing is mainly caused by too much glue in the fountain solution.
The peeling and peeling of PS plate photosensitive adhesive layer is mainly caused by problems such as plate protection and poor storage. If the problem is caused by the adhesion of chemicals (strong acid, strong alkali, etc.), it should be adjusted. If it is a plate problem, it should be contacted with the manufacturer. Exchange.
Author: How to strengthen developer management?
Mr. He Jianchuan believes that, first of all, the preparation of developer must be reasonable, too thick or too thin will have a great impact on the development effect. In the storage of developer, pay attention to the influence of light, temperature and humidity on the developer. For example, in winter, if you use gas or other heating equipment, the concentration of carbon dioxide in the room will increase, resulting in aging of the developer, so it should be used as much as possible. CO2 heating equipment. [next]
Expert viewpoint
The above is a preliminary discussion of some practical problems encountered by the front-line technicians in the PS version and the printing process. In order to analyze and solve the first-line problems of the PS version at a deeper level, we interviewed two teachers, Ning Chengzong and Tong Wenfu, As veteran experts who have worked in the printing industry for decades, they have undoubtedly a deep and thorough understanding of the front-line issues of platemaking. They have accumulated rich theories and experiences of printing technology through perennial technical services, and their views Has a certain representation.
1) Procurement
The purchase of PS version is a wise move to recognize the price trap. Except for a few quality-guaranteed brand products, such as Huaguang, Fuji Star, Starlight, Jielong, Juguang, Kangda, etc., the quality of PS versions of other brands The grades are similar, but there is not much difference between the plate material and the photosensitive performance, but the quality stability is slightly different. Although the general enterprises do not have high requirements for plate materials, they do not think that the lower the price, the better the choice of plate materials. Enterprises that have special requirements for the speed of light, such as the newspaper printing house, should also pay attention to the problem that many PS plate manufacturers do not improve the speed of the light from the raw material technology, but by reducing the amount of photosensitizer to improve the sensitivity. The purpose of the degree is that although the speed of light is increased, the printing resistance is lowered and the alkali resistance is also reduced.
2) Custody
The most important issue in the storage of the PS version is to avoid light, but also pay attention to moisture and alkali. Generally speaking, the PS version is well preserved, the shelf life can reach 2 to 3 years, and the printing durability will not change greatly with time. The shelf life of the printing plate reached consensus in the industry is 1 year. The fundamental reason is that many domestic manufacturers have not standardized the management of plate materials, and the PS version is greatly affected by the environment. In order to avoid disputes, PS version production companies generally use 1 Year is the preservation period, and this period is actually quite reasonable.
3) Light source
The choice of light source in printing is a noteworthy problem. Iodine gallium lamp is a light source suitable for printing, which has high luminous efficiency and can be used continuously. Its emitted spectral wavelength is distributed in the range of 350-450nm to 417nm It is the highest peak and is effective for most photosensitive layers of printing plates. This kind of light source emits strong ultraviolet rays. When it is used, it should be made of opaque materials such as artificial leather to make a protective cover or curtain, to prevent direct ultraviolet rays from damaging the eyes of the operator.
4) Print resistance
There are many factors affecting the durability, including the quality of the plate material, paper, ink, printing pressure, etc. The more important thing is the PS plate manufacturing technology. From the current point of view, the fundamental reason for the poor printing durability of the domestic PS version is that the removal of electrolytic fog and oxidized fog is not very thorough, and the PS photoresist is also a relatively large influencing factor; in addition, the adjustment of the machine pressure It is also very important. Experience shows that with different pressures, the printing durability of the printing plate is significantly different. In addition, the acidity and alkalinity of paper and ink also affect the durability of the printing plate.
5) Inking performance
Experimental data shows that the change in the content of the sensitizer in the photoresist has a great influence on the inking performance, which shows that the inking performance is very much related to the photoresist. Too much resin content or poor resin quality will also affect the inking performance. However, the amount of sensitizer is not too good. The higher the content, the slower the photosensitive speed. Therefore, it is very important to realize the rationalization and scientification of the ratio of resin to photosensitive resin.
6) The outlet is not real
The two teachers analyzed that, in addition to external factors causing false dots, it also involves a problem with a rough air-conducting layer. This is very important to eliminate the false dots. If the outer periphery is very solid, air will remain in the middle, which will cause light refraction and produce Newton's ring causes damage and loss of small dots, resulting in unrealistic dots. At present, the main method to solve this problem is to solve the problem by evacuating twice or adding a rough air-conducting layer on the PS version. There are also many ways to form a matte air-conducting 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 alkaline liquid, and have no effect on development. The purpose of the mating surface air-conducting layer is mainly to solve the Newton ring problem, which is not only fast, but also effective.
7) Dirty layout
Dirty on the plate surface mainly occurs during the exposure and development process, that is, the photoresist is not completely removed. In addition, the photoresist itself can also cause the plate surface to be dirty, such as the problem of blue return, and a small amount of insoluble matter in the photoresist deposits on the plate surface to cause blue return , In severe cases, it will cause a dirty. Versioning is generally caused by the performance of the PS version, but uneven or excessive machine pressure will cause the versioning.
At present, relevant domestic standards have been introduced. Experts suggest that each factory should formulate corresponding enterprise standards for the plate-making process according to its own situation, take the road of standardization, ensure the quality of the PS version, and enhance the comprehensive competitiveness of the enterprise.
Interview postscript
If we look at the domestic PS plate industry from a technical point of view, we can only say that our products are still in the middle grade. Photosensitive adhesive technology and sand surface treatment technology are the main gaps between domestic PS plates and foreign PS plates. According to two experts, there is still a big gap between the multi-layer sand mesh processing technology and foreign countries. The tolerance of the photoresist also makes the domestic PS version manufacturers shame. The photoresist used in a good PS version generally does not vary with the developer concentration and The length of development time has changed greatly. In addition, the differences between different brands of domestic PS version are also relatively large, and market competition is not standardized, which is also a factor that can not be ignored.
There are actually many first-line problems in the PS version. We just conducted a preliminary discussion on some of the issues we know. I believe that the discussion on the first-line problems of the PS version will continue to deepen with the development of the PS version industry. In the fierce market competition, The solution of these problems will provide more valuable reference opinions for the development of the plate material industry.
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