261. What is the basic composition and function of the PS version? 262. How to choose the base material? 264. Edition base surface treatment methods? 265. What is the process flow of electrolytic sand? 266. What is sand? 267. What is the role of surface treatment of the plate? 268. What are the performance requirements of sensitizers? 269. Photosensitizers can be divided into several categories? 270.PS version of commonly used sensitizers what? Fitness Home Treadmill,Electric Treadmill With Led ,Motorized Treadmill Yijian Body Exercise Equipment Co., Ltd. , http://www.electric-treadmills.com
A: The PS version consists of a plate base, an oxide layer, a hydrophilic layer, and a photosensitive layer.
1 Edition base: The carrier of the printing plate picture and text, plays the role of supporting the photosensitive layer, the plate base generally uses the aluminum plate;
2 Oxide layer: After anodizing the plate base, it will form a hard oxide film on the surface of the plate base. This layer of oxide film has strong adsorption, wear resistance and corrosion resistance, and can firmly connect the photosensitive material. Adhesive layer and aluminum plate base;
3 Hydrophilic layer: The hydrophilic film formed after anodization and sealing;
4Photosensitive layer: Photosensitive liquid composed of photosensitizer, film-forming resin, organic solvent, dye, etc. is coated on the surface of the plate base and dried. The photosensitive layer of the positive PS type has good oil-repellency, water repellency and resistance Grinding and acid resistance.
Answer: According to the principles of offset printing, the base material should have good oleophilicity, hydrophilicity, excellent bending strength, high wear resistance, and adaptability to chemical processing.
In fact, the plate base material that completely meets the above conditions does not exist. However, in combination with the oleophilic and hydrophilic requirements of offset printing plates, among copper, iron, zinc, aluminum, nickel, and chromium metals, copper has the best lipophilicity and the worst hydrophilicity; chromium has the worst lipophilicity. Hydrophilicity is the best, and zinc and aluminum are in between. Therefore, offset printing plates based on zinc and aluminum are widely used.
263. What is the surface treatment of the base?
A: The aluminum plate used in the PS plate produced by the aluminum plate plant has a very smooth surface, a low hardness, and poor adsorptivity, hydrophilicity, abrasion resistance, and corrosion resistance. Therefore, it cannot be directly used to produce a PS plate. In order to meet the need for offset printing, aluminum plates must first be surface-treated.
A: The surface treatment of the plate base includes chemical treatment, mechanical sanding, liquid honing, and electrolytic polishing. Mechanical scrubbing is divided into ball milling method, brushing method and sandblasting method, etc. There are static hanging contact method, non-contact spraying method and non-contact power supply method in electrolytic sand. Among them, electrolytic sanding and ball milling are most commonly used.
A: The process flow of electrolytic sand: degreasing → washing → pickling → washing → electrolytic roughening → washing → anodizing → washing → sealing → washing → drying.
A: The grain size refers to the micropores formed after the surface of the aluminum plate is roughened. Sand spot is the basis for the formation of layout and blank sections, and the sand appearance on the plate base can best represent the surface treatment level of the base.
Answer: The surface roughening treatment of the plate base is to form sand spots. Its role is:
1 layout pores are conducive to the printing plate to receive and store the fountain solution. The specific surface area of ​​the printing plate increases, which plays a role of better adsorption of liquid and wetting of the plate surface;
2 There is coating left on the photosensitive resin;
(3) to generate surplus surface energy to activate the layout, to create a condition for firmly and stably adsorbing substances such as oil and water with lower surface free energy;
Numerous micropores in the 4 layout have created conditions for the layout to have good oleophilic and hydrophilic properties.
5 negative effects: too fine sand, the layout is easy to dirty; coarse sand, affect the reproduction of the tone level of the print; wear of the sand, will reduce the life of the printing plate, so that the printing plate under the action of the acidic fountain solution The resistance to force drops.
A: The sensitizer is the photosensitive resin, which is the main component of the photosensitive layer of the PS plate. Performance requirements of sensitizers: Strong adhesion to the plate base, good affinity to the ink, excellent imaging sensitivity and high resolution, low pollution to the environment, high chemical stability, and convenience Save, low cost, etc.
Answer: 1 According to the photochemical reaction mechanism of photosensitizers, photosensitizers are classified into photolysis, photocrosslinking, and photopolymerization;
2 According to the photosensitizer solubility, adhesion and hydrophilic hydrophobic properties change, divided into photosensitive soluble type, photosensitive insoluble type, photosensitive release type, hydrophilic hydrophobic base change type.
A: The commonly used sensitizers for PS are o-naphthoquinones, diazonium salts, azides, and polyvinyl cinnamates. The former is used in the positive PS version, and the latter three are used in the negative PS version. Among them, o-naphthoquinone naphthalocyanine sensitizers are most widely used in PS plates, and can be used in combination with other resins, and can also be chemically bonded to molecular chains of some polymers to form various unique photosensitive resins. .
271. PS version of the photographic mechanism is what?
A: There are two ways to say about the sensitization mechanism of the diazonaphthalene sensitizers:
1 Under irradiation of ultraviolet rays, the diazonium group is decomposed, nitrogen gas is precipitated, and internal rearrangement of molecules is performed to obtain fluorenone, which is hydrolyzed to produce indole carboxylic acid. The carboxylic acid is developed in a dilute alkali developer to produce a carboxylate salt which is dissolved in water and removed.
2 Under the irradiation of ultraviolet rays, the surface molecules of the diazonaphthoquinones decompose to form fluorenone, which immediately reacts with the adjacent diazonaphthoquinone molecule that has no light in the lower layer to form lactones. The lactone is developed in a dilute alkaline developer to produce a carboxylate salt that is dissolved in water and removed.
---From "Printing Technology"