1,000 offset printing (272-284)

272.How to classify the PS version?
A: 1 According to the different materials of the plate, the PS version is divided into paper-based, film-based, aluminum-based and other types;
2 According to the type of photosensitive reaction of photosensitive resin, PS version is divided into photopolymerization type, photolysis type, light-sensitive peeling type, and photocrosslinking type;
3 According to the original image used in the printing process, the PS version is divided into two types: positive and negative.

273. What is the advantage of the PS version?
A: 1 version of the base surface fine mesh, uniform, good moisture, the layout of the oxide film hard and wear-resistant, high sensitivity of the photosensitive layer, dot reducibility is good, excellent ink absorption and transfer ink, can accurately reproduce the original tone and color;
2 The plate making process is simple, the plate making speed is fast, and it is easy to use and can be prepared in advance;
3 layout with small water consumption, stable performance, strong printability, high printing plate resistance, suitable for high-speed printing;
4 Rich printing layers, good dot reproduction, accurate reproduction of the tone and color of the original, especially suitable for printing fine products;
5 The cost is low and the storage time is long.

274. What are the contents of the PS version quality evaluation?
A: The quality evaluation of the PS plate includes requirements for appearance, mechanical and chemical properties. Among them, appearance properties include flatness, roughness, etc.; physical properties include specific gravity, hardness, tensile strength, elongation, and bending strength; chemical properties including oxygen resistance, acid resistance, alkali resistance, and solvent resistance, etc. .

275. What are the requirements for PS appearance performance?
A: PS version should have a good surface flatness, especially in the effective work surface, must be smooth, smooth, there should be no impurities, pits, holes, markings or rubbing marks, mechanical damage and other influence plate making and printing operations and Quality appearance quality issues.

276. What are the requirements for PS physical performance?
A: During the printing process, the plate will be periodically squeezed and rubbed. Therefore, the printing plate should have good compression resistance, bending resistance, tensile strength, and minimum elongation and friction resistance, so that the printing plate has a higher resistance to printing.

277. What are the requirements for the chemical properties of the PS plate?
A: In the process of plate making, the printing plate is subject to the treatment of chemical solutions such as developing and fixing. In the printing process, the surface of the printing plate graphic surface must absorb ink for a long time, and the ink contains chemical substances such as vegetable oil, resin and organic solvent. In the cleaning of the layout to contact with gasoline, kerosene and other chemical solvents; printing plate in contact with the fountain solution. All of these chemicals will affect the plate. Therefore, the graphic part and the non-graphic part of the surface of the printing plate, as well as the printing plate base, must have strong resistance performance and maintain its chemical stability during printing.

278. What is offset printing?
A: Offset printing is the process of using contact exposure to transfer the graphic information on the original plate to the photosensitive plate, and after a certain processing and processing to make the plate.
279. What are the preparations before offset printing?
A: Before offset printing, the following preparations must be done: 1 Reading the process list; 2 Checking and debugging the working status of the equipment; 3 Checking and testing the performance of the plate; 4 Preparing or preparing the printing plate drug; 5 Checking and testing Original quality.

280. What is included in the reading list?
A: The printing process sheet is an important basis for the workshop to arrange production and organize the implementation of the printing operation. The format and type of the printing process sheet vary from unit to unit. Generally include the product name, the original type and quantity, plate types and specifications, layout format, type of printing machine, binding method and set of drying methods, number of printing plates and completion date, and quality requirements for printing plates. Not only must the craft book be carefully read prior to sunning, but also when accepting the printing task, the items, technical parameters, and quality requirements stipulated in the craft book must be confirmed according to the production conditions, and the original quality must be received and checked on this basis.

281. What are the contents of checking and debugging equipment?
Answer: The necessary checking and debugging of printing equipment before printing is the basic guarantee for safety and quality production. Including the necessary cleaning process, the detection of the brightness and uniformity of the printing plate, the checking of the pumping degree of the printing plate, and the testing of the developing machine.

282. What are the contents of the inspection and test media?
Answer: Before printing, it is necessary to accurately understand and master the photochemical imaging performance of the plate, and carefully examine the main appearance quality of the flatness, coating thickness, and evenness. Under conditions permitting, the imaging performance such as the sensitivity and development performance of each plate of each grade and each batch should be tested to make sure that there is a good understanding of the actual printing.

283. What are the contents of formulating or preparing the printing medicine?
A: The printing process is a chemical processing process. In this process, various processing rinsing agents such as developer solution, etching solution, plate-preserving adhesive, and baking solution are used.

Liquid, so before the printing must be based on the type of plate and printing process requirements, in strict accordance with the preparation and use of printing plate liquid preparation, preparation or preparation of suitable printing solution.

284. What are the contents of checking and testing the original quality?
A: Before the printing version, it is necessary to conduct a thorough and comprehensive inspection and necessary testing of the original printing version to strictly control the quality of the original version. The basic contents of the original check are:
1 check whether the original name and contents are in line with the craft list;
2 inventory the original number of sheets, color number, can not appear missing, heavy phenomenon;
3 Using the manuscript as a reference standard, check whether the positive and negative images of the original picture and text comply with the printing requirements;
4 Check whether the necessary rules and markings on the original are complete and standardized;
(5) Check whether the original printing and overprinting relationships are correct, based on the relevant size and textual position of the original version, based on the process sheet and layout;
6 Check whether the graphic elements such as dot, text, and line on the original are clear, whether the density of the cable is large enough and the edge is smooth;
7 check whether the multi-color version is accurate;
8 Check whether the layout is clean, clean, with creases, scratches, waste tape, or other contaminants.

---From "Printing Technology"