Analysis on the principle and characteristics of stencil printing

Key: The printing part of orifice printing plate is composed of holes. In the printing process, the ink passes through the holes to form pictures and texts on the substrate, while the ink in the non-hole part cannot pass through.
Features: Compared with printing methods such as embossing and flat printing, screen printing has the unique advantages of fast plate making, simple printing method, less equipment investment, low cost and wide printing range.

2. What are the screen-making equipment?
Key: At present, the screen-making equipment used in China includes:
① Screen stretching machine —— The screen stretching machine is an important equipment that tightens and fixes the screen with a certain tension as a printing plate carrier. Screen stretching is the primary process to realize screen printing and plate making, and the quality of screen stretching is related to the quality of plate making and printing.
② Printing machine-Printing machine is the main equipment for drying high-quality screen printing plates.
③ Screen plate drying box-Screen plate drying box is a special equipment for plate making, which is used to clean the screen and dry it at low temperature after coating with photosensitive adhesive.
④ Tension meter-Tension meter is an instrument for measuring tension of tension net.
3. Briefly describe the screen making method.
Key: the main methods of screen plate making are: manual plate making method (including drawing plate making method and cutting plate making method); Photosensitive plate making method (including direct plate making method, indirect duty method and straight plate making method). There are also uncommon projection amplification plate making methods, inkjet scanning exposure direct plate making methods, infrared plate making methods, metal plate making methods, photo etching plate making methods, electroplating plate making methods, copper (zinc) photosensitive plate making methods, electronic plate making methods, laser manufacturing metal film plate making methods, composite screen plate making methods, etc.
4. Briefly describe the advantages and disadvantages of screen printing.
Key: Advantages: Compared with printing methods such as embossing and flat printing, screen printing has the unique advantages of fast plate making, simple printing method, less equipment investment, low cost and wide printing range.
Disadvantages: Screen printing is not suitable for printing fine products. Because the carrier of screen printing image is screen, no matter how fine the screen is, it will print the resolution to a certain extent. Therefore, screen printing is not suitable for printing fine products. Therefore, when screen printing is carried out, it is more important to highlight the characteristics of strong stereoscopic impression and ink thickness, and to make full use of strengths and circumvent weaknesses in design, so as to obtain better printing effect.
Orifice printing includes,,, and.
Key: Screen printing, copying printing, stencil printing, thermal stencil printing of printing machine Screen printing is the principle and characteristic?
Key: Screen printing means that the screen made of silk, nylon, polyester or stainless steel wire is tensioned and firmly adhered to the screen frame (usually wooden frame or alloy aluminum frame) by a screen stretching machine. By manual or photochemical methods (coating photosensitive adhesive film, exposure and development), only the printing inking part needed for graphics and text is left on the screen, and other screen eyes are blocked to make a screen plate, then ink is coated and the screen plate is processed with a scraper Features: (1) thick ink layer, strong coverage, rich graphics and text layers, and strong three-dimensional sense; (2) Applicable to various types of inks; (3) Flexible and diverse printing methods; (4) The layout is soft and the printing pressure is small, and the material application range is wide; (5) It is not limited by the size and shape of the substrate and has strong adaptability to the shape of the substrate; (6) Screen printing has the advantages of fast plate making, simple printing method, less equipment investment and low cost.
The main types of screens are:,,,,, and.
Key: silk screen, nylon screen, polyester screen, stainless steel screen, nickel-plated polyester screen, calendering screen (UV screen), antistatic screen, etc.
8 Briefly describe the principle of electrostatic screen printing.
Key: Electrostatic screen printing is a pressureless printing. The substrate is placed between the positive electrode composed of the metal screen printing plate and the negative electrode composed of the metal plate parallel to it. When the scraping knife extrudes the powdery ink particles on the screen plate from the transparent part of the plate, it is positively charged and immediately attracted by the negative electrode, thus being attracted by the substrate and attached to the surface of the substrate to form a picture and text.
According to the different screen forms and substrates of screen printing, what kinds of screen printing can be usually divided into?
Key: According to the different screen forms and substrates of screen printing, it can be divided into the following four categories: (1) plane screen printing, (2) curved screen printing, (3) rotary screen printing, (4) electrostatic screen printing, etc.
The clarity of screen-printed products has been achieved, and plate-making and printing are developing in the direction of,, and.
Key ：150 lines per inch, multi-color, high-speed automation and digitalization In order to ensure the quality of screen printing, what are the main requirements for screen performance?
Key: (1) high tensile strength; (2) Small elongation; (3) Appropriate resilience; (4) Good stability to temperature and humidity changes; (5) Good ink passability; (6) Resistance to friction; (7) Good resistance to chemicals Briefly describe the definition of rotary screen printing.
Key: Rotary (circular screen printing) screen printing, that is, cylindrical nickel-plated stainless steel screen printing, continuously prints rolled substrates. A fixed ink scraper is installed inside the cylinder, the cylinder screen plate rotates at a constant speed, the printed part and the screen plate move synchronously in the tangential direction, and the ink scraper forcibly scrapes and presses the ink from the holes of the printing plate to the surface of the substrate at the tangential position to print the finished product.
Briefly describe the definition of electrostatic screen printing.
Key: Electrostatic screen printing is a pressureless printing. The substrate is placed between the positive electrode composed of the metal screen printing plate and the negative electrode composed of the metal plate parallel to it. When the scraping knife extrudes the powdery ink particles on the screen plate from the transparent part of the plate, it is positively charged and immediately attracted by the negative electrode, thus being attracted by the substrate and attached to the surface of the substrate to form a picture and text.
Generally, the ink layer thickness of letterpress printing is 0, while that of intaglio printing is only 0, while that of screen printing can reach 0. The methods of thinning ink in screen printing are,,, and etc.
Key：5μm、1.6μm、12～15? m、30～100? M, shape of ink scraper, printing pressure, inking angle, thickness of screen diameter and ink viscosity

The clarity of printed products with mesh tone has been achieved, and plate making and printing are oriented towards,,,.
Key：150 lines per inch, multi-color, high-speed automation and digital development Hole plate making methods can be roughly divided into,,, and so on.
Key: manual plate making method, metal plate making method, photosensitive plate making method and infrared plate making method As the matrix supporting the printing film and ink, the silk screen determines the printing plate’s,,, And so on, have a direct impact on the printing performance and the quality of printed products.
Key: surface performance, ink leakage performance, position accuracy and printing resistance In order to ensure the quality of screen printing, what are the main requirements for screen performance?
Key: (1) High tensile strength-in screen printing, it mainly shows the ability to resist damage or fracture when the screen is under tension. (2) Low elongation-because of the high elongation, the plane stability of the printing plate is poor. (3) Appropriate resilience-good resilience, and clear edge of imprint. (4) Good stability to temperature and humidity changes. (5) The ink has good passability-this can ensure that the ink can leak from the mesh to the printing surface smoothly. (6) Anti-friction-Screen printing is a printing method in which the printing ink on the layout is scraped and pressed onto the printing surface by a scraper. Therefore, the screen is required to resist friction, so as to improve the printing resistance of the printing plate. (7) Good resistance to chemicals-In the process of operation, the screen printing plate often encounters acid, alkali and organic solvents related to ink, so the screen should have enough resistance.
Advantages and disadvantages of silk net.
Key: Silk screen has strong water resistance, certain hygroscopicity, strong combination with photosensitive adhesive film and easy plate making. However, the wear resistance and chemical resistance of silk mesh are poor, which is easy to age and brittle, and the tension value of silk mesh is small.
Advantages and disadvantages of nylon mesh.
Key: Advantages: Nylon mesh has high strength and wear resistance; The alkali resistance is very good, and the acid resistance is slightly worse than that of polyester net; Nylon silk has smooth surface and good ink passing performance; Thinner than polyester net, easy to print fine marks; Resilience is the biggest among these kinds of screens, so the printed products are colorful, which is also suitable for screen printing on irregular surfaces.
Disadvantages: The disadvantage of nylon mesh is its high elongation, which is not suitable for printing products with high dimensional accuracy requirements.
Advantages and disadvantages of polyester mesh.
Key: The outstanding advantages of polyester mesh are small elongation, better weather resistance than nylon mesh, small hygroscopicity and good resistance, especially acid resistance and organic solvent resistance, but not strong alkali erosion. Because of its good plane stability, it can be used for high-precision printing. Because polyester is hydrophobic, it is difficult to combine with printing film, its ink permeability is worse than nylon net, and static electricity is easy to be generated during printing.
Advantages and disadvantages of wire mesh.
Key: Advantages: The metal screen has the highest strength, small elongation and excellent plane stability among the existing screens, and is suitable for high-precision printing, such as printing high-precision images such as circuit boards and integrated circuits. Fine silk diameter, good ink permeability, and fine printing. High softening temperature, electrical conductivity, and can be used for hot printing and electrostatic screen printing.
Disadvantages: The disadvantages of stainless steel wire mesh are poor resistance to chemicals and zero resilience. Once stretched or creased in operation, it cannot be recovered and discarded. In addition, it is expensive and costly.
Advantages and disadvantages of calendering screen.
Key: The thickness of calendering screen is thin. When printing, the printing ink layer is thin, the ink transfer amount is small, and the ink is saved. It is often used for UV curable ink, that is, UV ink, so it is called UV screen. Another advantage is that, in most cases, the screen is relatively stable, the squeegee runs relatively smoothly during printing, and the impact resistance of the printing plate is strong. In color gradation screen printing, the overprinted ink layer can not be too thick, thus reducing the enlargement of dot and improving the tone reproducibility of printed products.
Technical parameters of screen are mainly used to express, and the main technical parameters are:,,,, and so on, which are indispensable for designing screen printing process scheme.
Key: screen performance, mesh number, aperture, wire diameter, screen thickness and mesh area ratio Definition and significance of the number of items.
Key: the mesh number refers to the number of meshes or meshes per unit (1cm, Lin, lin,lin=2．54cm). It indicates the density of the screen. The higher the mesh number, the denser the screen and the higher the fineness of printing. Fine lines and small dots can be reproduced, which makes the printed image rich in layers. Of course, the mesh number of screen is not as high as possible, but must be determined according to specific printing conditions.
Screen with the same mesh number can be divided into five grades:,,, and. The size of wire diameter is closely related to the life of screen. The thinner the wire diameter, the longer the life of screen, the better the printing resistance of printing plate, but the higher the resolution of image.
Key: fine (S), medium thickness (M), thick (T), extra fine (SS), extra thick (HD), short, low and high The main weaving forms of silk screen are:,,,, and so on Key: plain weave, twill weave, full twist weave (full braid weave), half twist weave (half braid weave) Causes and solutions of halo.
Key: The color of the screen is a screen printing plate made of white screen. During plate making, the white screen will scatter the ultraviolet light irradiated on it, which enlarges the photosensitive range, produces halo phenomenon, makes the image edge blurred or deformed, and affects the image reproduction accuracy. In order to avoid this phenomenon, colored screens are generally used. Color can act as a color filter. During exposure, the light scattered by the colored screen loses its exposure efficiency, and part of the irradiation light is absorbed, thus eliminating the disadvantages caused by light scattering.
There are two main aspects in the selection of screen, one is; The second is.
Key: the type of screen; Technical parameters of wire mesh (mainly mesh number and wire diameter and thickness grade, etc.).
30. In order to ensure the quality of screen printing, what are the main requirements for the performance of the screen frame?
Key: (1) High strength-the screen frame must have a certain strength, that is, it can bear the tension of the screen when stretching the screen, and resist the mechanical force during plate making and printing without deformation. (2) Good resistance to water and solvent-in the process of screen printing and printing, the screen always comes into contact with water and solvent, and it is necessary to prevent the screen frame from being deformed or corroded by moisture absorption. (3) Lightweight-under the condition of ensuring strength, the lighter the net frame, the better, which is convenient for operation and use. (4) Good adhesion-the screen frame and screen should have good adhesion to ensure that the screen can be used for a long time. It is required that the bonding surface between the mesh frame and the screen has a certain roughness, which can increase the bonding force between them.
According to the material, the net frame can be divided into,, and so on.
Key: wooden frame, metal frame and plastic frame

Briefly describe the advantages and disadvantages of using wooden frame and matters needing attention.
Key: The advantages of wooden frame are lighter and cheaper; The disadvantage is that it is easy to deform due to water absorption and solvent. In order to reduce this shortcoming, the surface of wooden frame is coated with a layer of water and solvent resistant coating.
Compared with other materials, the use of wooden frame is limited due to the accuracy problem, so it is not suitable for multi-color screen printing and high-precision screen printing. The following points should be paid attention to when using wooden frames:
(1) if the net is fixed with staples, cork (such as Chinese fir) should be used as the frame material.
② mortise and tenon method should be used for frame corner structure, and glue and nail (or iron corner) should be used for reinforcement.
③ The size of the frame should not be larger than 40cm×50cm.
(4) the section size of the frame shall not be less than 4cm×5cm.
There are two common methods of manual plate making: and Key: Description plate-making method, cutting plate-making method What are the principles of yin and yang drawing in manual plate making?
Key: Shading method: overlay the screen on the manuscript, draw the outline of the figure on the screen with a pencil, and then insert two thin strips between the screen and the manuscript to make the screen slightly away from the manuscript. Dip the paint with a brush to plug the mesh outside the graphic outline, and only the mesh of the graphic part is transparent, thus forming a printing plate.
Yang drawing method: firstly, draw the positive figure directly on the screen with liquid paint or solid ink bar, and then coat a layer of screen sealing paint on the whole screen plate after the portrait is dry. The screen sealing paint should be immiscible with the painting material. After the screen sealing paint is fully dried, wash the painting material with the painting material solvent, so that the mesh of the graphic part is transparent, thus forming a printing plate.
There are three types of films commonly used in hand-carved film making:; ; .
Key: hand-carved film specially used for screen printing; Mask (tear film) for printing industry and electronic industry; Film for screen printing and sensitization Photosensitive plate making method can be divided into,,,,, and there is a special one.
Key: direct method, indirect method, straight method, projection amplification plate making method, inkjet scanning exposure direct plate making method, infrared plate making method Briefly describe the technological process of direct plate making and the functions of each operation.
Key: the process flow of direct plate making is: pretreatment of screen plate → (gluing → drying) n→ printing → developing → drying → trimming (1) Pre-treatment of screen plate-The purpose of pre-treatment of screen plate is to ensure the bonding fastness between screen and photosensitive film, and degreasing treatment is mainly carried out.
(2) Glue coating-Glue coating is to coat sensitive glue on the silk screen. (3) Drying-gluing is carried out in a liquid state. Generally, the sensitivity of photosensitive adhesive is low in the liquid stage, and increases with the drying of the coated adhesive film, and reaches the maximum when the adhesive film is completely dried, that is, the exposure hardening of most photosensitive adhesives needs to be completed in a solid state, so as to have the best strength, so drying is indispensable. (4) Printing-printing should be done as soon as possible after the photosensitive film is completely dry, and the negative film of printing should be a positive image. During printing, the film surface of the negative film and the printing surface of the screen should be exposed closely. (5) Development —— Development means that after exposure, the adhesive film on the light-sensitive film is completely dissolved, and then a screen printing plate is made. (6) Drying-After the development is completed, the plate film should be dried immediately. (7) Trimming —— The developed and dried screen should be trimmed, which mainly includes three steps: closing the screen, revising the screen and removing the film.
Relationship among exposure, light intensity and lamp distance.
Key: The exposure amount (i.e. minimum curing amount) is affected by exposure time, illumination intensity and optical properties of various materials (frame glass, silk screen, negative film and film thickness); The illumination intensity depends on the type of light source and the distance between lamps. And the lamp distance is controlled by illuminance uniformity and map size.
Control principle of developing degree.
Key: The control principle of development degree is: under the precondition of transparency, the shorter the time, the better. If the time is too long, the wet expansion of the film is serious, which affects the clarity of the image; If the time is too short and the development is not complete, there will be blinding, blocking the mesh, resulting in waste plates.
The technological process of indirect plate making and the function of each operation.
Key: printing → curing → developing → printing film online → drying → trimming ↑ Pre-processing of screen printing (1) Pre-treatment of screen plate-In addition to degreasing treatment as in direct method, new synthetic fiber screen, especially polyester screen, needs coarsening treatment in order to improve the bonding fastness between screen and photosensitive film. (2) Print-out-that is, the original is transferred to the dry film to make a film, and then transferred to the silk screen. (3) Curing (hardening treatment). (4) Developing: developing the cured dry film. (5) Surfing the Internet-Surfing the Internet means transferring the developed film to the silk screen.
Direct, indirect and direct plate-making methods are the most important methods in photosensitive plate-making methods. What are their advantages and disadvantages?
Key: The direct method is economical, printing-resistant, and the plate width is unlimited. It is commonly used in general screen printing, but the image resolution is not too high, and the edge of the print is prone to sawtooth, which is not smooth and suitable for fine printing; The outstanding advantages of indirect method are high image resolution, smooth print edge, and can be used for fine printing, such as pressure-sensitive transfer materials, but the printing resistance is low; With the simplest process and good performances, the straight-room method is widely used in small-format printing in China, and it is also used in large-format printing. With the development of photosensitive materials, this method has a great tendency to replace other methods.
Briefly describe the principle of direct plate making by inkjet scanning exposure.
Key: Ink-jet scanning exposure direct plate-making method uses ink-jet scanning equipment with computer color separation system, which can directly process the graphic and text information of the original manuscript. The processed information is recorded on the screen plate coated with photosensitive glue by ink-jet output, and then the screen plate is exposed, ink-removed (developed) and developed to make a screen printing plate.
Principle of infrared plate making.
Key: The infrared plate making method uses a synthetic resin film with special properties of heat shrinkage as a photosensitive material for screen printing plate making. When making plate, first coat it on the screen, then put the black-and-white manuscript under the screen, and expose it by infrared rays. Because the graphic part of the manuscript absorbs heat, the resin coating shrinks, thus making the mesh of the graphic part transparent, thus making the screen printing plate.
This paper briefly describes the technological process of photoetching plate making and the functions of each operation.
Key: preparing metal sheet, surface treatment, coating photosensitive adhesive, printing, developing, etching, demoulding and upper frame of printing film (1) prepare metal sheet-metal sheet as the plate base. (2) Surface treatment: grinding, pickling, degreasing and cleaning the plate base. (3) Coating photosensitive adhesive-Coating photosensitive adhesive is used to make anti-corrosion film. (4) Printing-Printing is to print the image on the original version onto the metal foil. (5) Development —— Development means that the metal is exposed in the graphic part of the metal foil, and the acid-resistant and corrosion-resistant film is formed in the non-image part, that is, the photosensitive adhesive of the graphic part is removed. (6) Corrosion-Corrosion means that exposed metal, i.e., graphics and text, is corroded and penetrated. (7) Stripping-Stripping is to remove the resist film layer of the non-image part. (8) Upper frame of plate film-The upper frame of plate film is to glue the finished non-screen film or screen film and paste it on the metal frame to form a printing plate.
In screen printing, the principle of copper (zinc) plate-making method is briefly described.
Key: The copper (zinc) plate-making method is to use copper (zinc) and other metal plates to make a plate with raised graphics and text, and then fill the metal plate with nitrocellulose paint. After the paint is dry, use fine sandpaper to smooth the paint on the metal plate and expose the metal, leaving only the concave part filled with nitro varnish. Then, the metal plate is attached to the silk screen, and the nitrocellulose lacquer in the recess is dissolved and attached to the silk screen to become the ink blocking part (non-graphic part). Finally, the metal plate is taken down, and the convex part of the original metal plate is rubbed off. At this time, the screen is a transparent mesh (i.e., image characters), and the screen printing plate is made.
In offset printing, which types can be divided according to different printing materials?
Key: Pore printing can be divided into: fabric printing, plastic printing, metal printing, ceramic printing, glass printing, electronic product printing, lottery screen printing, electrical advertising board screen printing, metal advertising board screen printing, stainless steel product screen printing, light reflector screen printing, screen transfer aluminum, screen printing prints and lacquer ware screen printing, etc.
What are the other screen printing methods?
Key: ① lottery screen printing, ② electric advertising board screen printing, ③ metal advertising board screen printing, ④ stainless steel products screen printing, ⑤ light reflector screen printing, ⑥ transfer anodized with screen printing, ⑦ screen printing, and ⑧ lacquer ware screen printing Generally, there are two ways to tighten the screen on the frame. At present, there are two types of net stretching machines commonly used at home and abroad.
Key: direct net stretching, indirect net stretching, pneumatic net stretching machine and mechanical net stretching machine Advantages of pneumatic net stretching machine.
Key: the pneumatic mesh stretching machine has many advantages, including:
a。 The adjustment of net drawing size is very convenient, and the number of required net drawing devices can be determined according to the size of net frame, thus reducing the waste of screen.
b。 Because all sides of the screen are subjected to the same tensile force, and all sides are stretched at the same time, the tension of stretching the screen is relatively uniform. In addition, it can also correct the difference of warp and weft elongation caused by weaving.
C. because the air pressure is controlled by the air cylinder controller to control the tension of web stretching, it is easy to obtain more consistent tension when multiple versions are stretched repeatedly.
D, like the manual net puller, the net frame can be pre-deformed to stabilize the tension of the net.
Tension angle refers to the angle between screen and. There are two forms of tension net.
Key: longitude, latitude, edge of net frame, positive tension net, oblique tension net There are five kinds of light sources commonly used in screen printing:,,, and.
Key: carbon lamp, black light lamp, high pressure mercury lamp, xenon lamp, metal halogen lamp What factors should be comprehensively considered when selecting printing light source?
Key: The following factors should be comprehensively considered when selecting the light source for printing: ① The emission spectrum of the light source should match the absorption spectrum of the photosensitive adhesive. ② The light source has high luminous efficiency, especially high ultraviolet light conversion rate and high luminous intensity or brightness. ③ Better safety and hygiene. ④ Good image reproducibility. It is best to choose point light source. ⑤ The heat radiation of light source is small. ⑥ Uniform luminous intensity. ⑦ The light source has strong adaptability to the environment and can work normally under various temperature, airflow and voltage changes.
Grinder can be divided into grinding wheel type and abrasive belt type, and their working principles are explained respectively.
Key: (1) The working principle of the grinding wheel sharpener is to push the offset plate placed on the guide rail by hand, so that it can pass over the grinding wheel smoothly, and the grinding action of the grinding wheel rotation is used to achieve the purpose of grinding the cutting edge. When in use, put the glue scraper on the guide rail, adjust the distance between the two guide rails and the position of the positioning plate according to the thickness of the glue scraper, and determine the cutting amount through the height adjustment screw. Grinding wheel sharpener has large grinding capacity and is suitable for rough machining.
(2) The working principle of abrasive belt grinder is similar to that of grinding wheel grinder. The difference is that the special rotary abrasive belt replaces the grinding wheel for grinding, which can increase the grinding contact area, make the rubber scraping edge smooth and smooth, and has small grinding amount, which is suitable for finishing.