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Screen Printing
2019-04-20

Screen printing is a stencil printing method, which is called four printing methods together with lithography, embossing, and gravure printing. The stencil printing includes a stencil, a stencil, a spray, and a screen printing. The principle of stencil printing is: the printing plate (the aperture of the paper plate or other plate is made through the ink). At the time of printing, the ink is transferred to the substrate through the hole of the stencil through a certain pressure (paper, ceramics, etc.) ), forming an image or text.

During printing, the ink is transferred to the substrate through the mesh of the graphic portion by the extrusion of the squeegee to form the same graphic as the original. The screen printing equipment is simple, easy to operate, simple in printing and plate making, low in cost, and strong in adaptability. Screen printing applications are widely used in common prints: color oil paintings, posters, business cards, binding covers, merchandise signs, and printing and dyeing textiles.

 

Plate Making Method

Direct plate making

Method: The method of direct plate making is to first place the photosensitive film-coated photosensitive film face up on the work surface when making the plate, put the stretched wrist frame flat on the base, and then put it in the frame. The photosensitive paste is applied by pressure coating with a soft scraper, and after drying, the plastic film base is removed, and the photosensitive film wrist wire mesh is attached to the printing plate, and after development and drying, a screen printing screen is produced.

Process: stretched net - degreasing - drying - peeling base - exposure - development - drying - revision - closing

Indirect plate making

Method: The indirect plate making method is to expose the indirect film first, harden it with 1.2% H2O2, develop it with warm water, and dry it to make a peelable graphic film. When making the plate, the film film surface is tightly attached to the stretched wire mesh. The film is adhered to the wet wire mesh by extrusion, the film base is peeled off, and the screen printing screen is made by drying with the wind.

Process flow:

1) Stretched net - skim - drying

2) Indirect film-exposure--hardening--development

1 and 2--fit--drying--revision--sealing

3) Straight intermixing method

First, the photosensitive adhesive layer is pasted on the screen frame with water, alcohol or photosensitive glue, and after drying by hot air, the base of the photosensitive film is removed, and then the plate is printed, and the screen plate is formed after development processing.

 

Working Principle:

Screen printing consists of five major components, namely screen plates, squeegees, inks, printing stations, and substrates. The basic principle of screen printing is to use the basic principle of the screen printing part of the mesh to penetrate the ink, the non-image part of the mesh is not transparent to the printing. The ink is poured on one end of the screen printing plate during printing, and a certain pressure is applied to the ink portion on the screen printing plate by the squeegee blade while moving toward the other end of the screen printing plate. The ink is squeezed from the mesh of the graphic portion onto the substrate by the squeegee during movement. Due to the viscous action of the ink, the print is fixed within a certain range. During the printing process, the squeegee is always in line contact with the screen printing plate and the substrate, and the contact line moves with the movement of the squeegee due to the screen printing plate and the substrate. A certain gap is maintained between them, so that the screen printing plate at the time of printing generates a reaction force against the squeegee by its own tension, and this reaction force is called a resilience force. Due to the resilience, the screen printing plate and the substrate are only in a moving line contact, and the other portions of the screen printing plate are separated from the substrate. The ink and the screen are broken and the printing is ensured to ensure the dimensional accuracy and avoid the dirty substrate. When the squeegee scrapes across the entire layout, it is lifted, and the screen plate is lifted, and the ink is gently scraped back to the original position. This is a printing trip.

 

Advantages:

(1) Not limited by the size and shape of the substrate

Generally, printing can only be carried out on a flat surface, and the screen printing can be printed not only on a flat surface but also on a specially shaped molded object such as a spherical curved surface, and the shaped object can be screen printed.

(2) The layout is soft and small

The screen is soft and flexible.

(3) Strong ink coverage

It can be printed on pure black paper with a strong white effect.

(4) Suitable for all types of inks

(5) Strong resistance to optical rotation

The gloss of the print can be made unchanged. (No effect on temperature or daylight). This allows for the printing of some stickers without the need for additional filming and other processes.

(6) Flexible printing methods

(7) Easy to make, cheap, and easy to master

(8) Strong adhesion

(9) Can be hand-printed silk screen or machine-printed

(10) Suitable for long-term display, outdoor advertising is expressive

 

Printing Method:

There are usually two types of screen printing, manual printing and mechanical printing.

Manual printing refers to the movement from the continuous feeding to the delivery, the upper and lower movement of the printing plate, and the scraping and squeegeing are all manual operations.

Mechanical printing means that the printing process is done by mechanical action. It is divided into semi-automatic and fully automatic printing. Semi-automatic means that the substrate is placed and removed by manual operation, and printing is done by mechanical; fully automatic means that the entire printing process is completed by machinery.

There is also a quick and easy curved screen printing method for screen printing, which is to remove the screen layout and directly adhere to the printing surface for printing. Using the live screen printing method, a large number of processed printed products can be printed, such as latex plastic buckets, pure water buckets, washbasins, hot water bottles, cups, bowls, plates and the like. At the same time, this method can be used to print signboards on the car, or to print on the profiled plane.

The production of the live screen version: First, the photosensitive text version is dried and repaired, then removed, and cut according to the size. At the two ends of the screen, wood chips or aluminum sheets are used as the skeleton to be firmly adhered with adhesive tape, and the adhesive can be directly adhered, so that the desired screen surface can be made. Operation method of the noodle net: According to the substrate, different printing materials are used for the preparation: firstly, the flat plate and the plate are used to mix the ink, and then one person holds the live screen version with both hands, and the printed portion is closely attached to the printing plate. On the object surface, another person evenly dipped the ink on the mouth surface of the doctor blade on the ink-adjusting plate with a doctor blade, and then uniformly placed the doctor blade on the ink-adjusting plate on the plate to uniformly print the ink.

If the area of the printed graphic is too large, the ink may be poured onto the layout as appropriate, but do not let the ink flow out of the substrate. Note that the blended ink should not be too thin, not too dry, moderate dry and wet as well. Small area printing and printing can be operated by one person by attaching one end of the mask to the desired position of the substrate with the packaging tape, and then pressing the plate with the other hand to stick to the substrate. Printed. Note from the beginning: It must be lighter than the one end of the tape. If the two people operate the original version of the advertisement, it is printed by this method. It has convenient operation, flexible requirements for the substrate, and can be large and small. More or less, with the advantages of low cost and energy saving.

 

Main Application:

The range of screen printing applications is very broad. In addition to water and air (including other liquids and gases), any object can be used as a substrate. Someone once commented on screen printing: If you want to find the ideal printing method on the earth for printing purposes, it is probably screen printing.

Specifically, screen printing is mainly used in the following aspects:

1. Paper printing Art printing - advertising, art, calendar, lantern paper, etc.

Trademark printing

Transfer printing

Packaging and Printing

Building materials printing - paste wallpaper and so on.

2 plastic printing plastic film - vinyl toys, school bags, plastic bags and so on.

Plastic standard plate - fake metal composite material and various standard plates.

Production parts - instrument parts.

3 wood products printing crafts - lacquerware, wooden crafts, toys.

Processing semi-finished products - sporting goods, wood panels, ceilings, road signs, signboards, fake metal plates, billboards, etc.

4 metal products printing metal cylinders, metal utensils, metal products.

5 glass, ceramic products printing glass - mirrors, glass plates, cups, bottles and so on.

Ceramics - utensils, crafts.

6 signs Character description board, dial, shaped items.

7 circuit board printing Printed circuit boards, civil or industrial substrates, thick film integrated circuit boards, cold light sheets.

8 Printing and dyeing Printing and dyeing - flags, cloth, towels, handkerchiefs, shirts, vests, knitwear, etc. '

Other printing - pockets, shoes, bibs and a variety of bags, backpacks, bags, school bags, etc.

9 leather products printing

 

Maintenance:

With the development of technology, a variety of screen printing, pad printing machines quickly appeared. Various corporate brands that focus on the design and development of pad printing machines, screen printing, and other product areas have also emerged. Experts suggest that users must pay attention to the maintenance of screen printing machines, and the mesh is a part that cannot be ignored.

The impact of mesh on the quality and safety of screen printing is very large. Therefore, good maintenance of the mesh is necessary. Firstly, the screen-printed mesh must be cleaned and degreased when it is used. If the mesh is not cleaned in time, it will easily lead to poor screen printing and garbled when it is used next time. If the corresponding degreasing work is not carried out, it will easily lead to delamination of the screen. Secondly, marking the age and number of meshes on the mesh frame of the mesh is also an important maintenance strategy. This can provide more convenience to the use process. Finally, during the use of screen printing, contact with sharp objects should be avoided to prevent accidental damage to the mesh.

By taking the above suggestions for maintenance, I believe that in the future, the use of fully automatic screen printing can avoid many unnecessary troubles.


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