Screen printing technology basic question and answer
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1. What is screen printing?
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. The most convenient stencil printing was written in the late 19th century. This type of printing is made on a special stencil paper, which is made into a stencil graphic version by a typewriter or a stylus. The stencil printing is carried out with an ink roller, and the desired printing effect can be obtained on the substrate. In stencil printing, the most widely used is screen printing.
Screen printing is to stretch silk fabric, synthetic fiber fabric or metal mesh on the frame, and make screen printing by hand-painting or photochemical plate making. The modern screen printing technology uses a photosensitive material to make a screen printing plate by photolithography (so that the screen hole of the graphic portion on the screen printing plate is a through hole, and the mesh hole of the non-image portion is blocked. live). 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.
2. When was screen printing invented?
Screen printing originated in China and has a history of more than 2,000 years. As early as in the ancient Qin and Han dynasties in China, there appeared a method of printing. In the Eastern Han Dynasty, the method of waxing and dyeing was already popular, and the level of printed products was also improved. In the years of the dynasty, people began to use the frame with the shackles to print, so that the stencil printing process developed into a screen printing. According to historical records, the fine costumes worn in the courts of the Tang Dynasty were printed in this way. In the Song Dynasty, screen printing was developed, and the original oil-based paint was improved. The starch powder was added to the dye to make it into a paste for screen printing, which made the color of the screen printing product more beautiful.
Screen printing is a major invention in China. The US "Screen Printing" magazine has commented on China's screen printing technology: "There is evidence that Chinese people used horseshoes and templates two thousand years ago. The clothing of the early Ming Dynasty proved their competitive spirit and processing technology. The invention of screen printing has promoted the development of the world's human material civilization. Today, two thousand years later, screen printing technology has been continuously developed and perfected, and has become an indispensable part of human life.
3. What is the principle of screen printing?
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.
4. What is the main difference between screen printing and other printing methods?
The main differences between screen printing and other printing methods are as follows:
1 Printing adaptability The three printing methods of strong lithography, embossing and gravure printing can only be printed on a flat substrate. Screen printing can be printed not only on a flat surface, but also on substrates with curved, spherical and concave surfaces. On the other hand, screen printing can be printed not only on hard objects, but also on soft objects, without being limited by the texture of the substrate. In addition to this, in addition to direct printing, screen printing can also be printed by indirect printing method as needed, that is, screen printing on gelatin or silicone plate, and then transferred onto the substrate. Therefore, it can be said that screen printing is highly adaptable and has a wide range of applications.
2 The ink layer is thick and strong, the texture is strong, the texture of the rich offset and embossed ink layer is generally 5 microns, the gravure is about 12 microns, the flexographic (aniline) printed ink layer is 10 microns thick, and the screen printing is The thickness of the ink layer far exceeds the thickness of the above ink layer, and is generally up to about 30 microns. Thick screen printing for printed circuit boards with an ink layer thickness of up to 1000 microns. Braille is printed with foaming ink, and the thickness of the ink layer after foaming can reach 300 microns. The screen printing ink layer is thick, the printing quality is rich, and the three-dimensional feeling is strong, which is incomparable with other printing methods. Screen printing can be done not only in monochrome, but also in color and screen color printing.
3 strong light resistance, bright color Because screen printing has the characteristics of missing printing, it can use a variety of inks and coatings, not only can use slurry, adhesive and various pigments, but also can use coarser pigments. In addition, the screen printing ink is simple to prepare, for example, the light-resistant pigment can be directly placed in the ink, which is another major feature of screen printing. Screen printing products have great advantages in light resistance. It has been shown by practice that the range of maximum density values measured after one embossing on the coated paper using black ink is 1.4, offset printing is 1.6, gravure is 1.8, and screen printing has a maximum density value range. Up to 2.0, the lightfastness of screen printing products is stronger than that of other types of printed products, and it is more suitable for advertising and signage outdoors.
4 Large printing area At present, the printing area of general offset printing, embossing and other printing methods can be up to the full size of the sheet. If it exceeds the full sheet size, it is limited by mechanical equipment. Screen printing can be used for large-area printing. Today's screen printing products can reach a maximum of 3 meters x 4 meters or even larger.
The above four points are the difference between screen printing and other printing, and also the characteristics and advantages of screen printing. Understand the characteristics of screen printing, in the selection of printing methods, you can develop strengths and avoid weaknesses, highlight the advantages of screen printing, in order to achieve a more ideal printing effect.
5. What type of manuscript is suitable for screen printing?
Screen printing, like other printing, requires accurate reproduction of the text and color of the original. The original used in screen printing is in principle not very different from the original used in other printing methods, but in specific plate making and printing practice, the requirements are different, which is mainly determined by the screen printing characteristics. In particular, since the screen printing ink layer is thick and bright, it is necessary to fully consider the special effects of screen printing when selecting the original and plate making.
In addition, the accuracy of the lines and dot requirements of the original used in screen printing is also different from that required for the ordinary printing method. If the lines and dots of the original are very fine, it is very difficult to use screen printing. Therefore, the screen printing technique is not suitable for reproducing originals of fine lines and dots. In the selection of the printing method, it is necessary to fully consider the characteristics of various printing. Even in the screen printing plate making, it is also necessary to pay attention to selecting a suitable network cable in order to achieve the purpose of sufficiently reproducing the original.
Screen printing is more suitable for monochrome original color originals with bright text and lines. It is also suitable for color originals with large contrast and clear levels. Through the special effects of screen printing, the replica has a rich expressive power, and the texture and the stereoscopic effect of the original content are fully expressed by enriching the contrast between the thick ink layer and the hue.
Screen-printed photo-imprinted originals are available in both reflective and transmissive originals, usually using a reflective original. Most of the color photography uses a transmissive original.
Screen printing mainly uses a positive picture to make a screen. Different plate making methods have different requirements for originals.
6. What are the main features of screen printing?
The characteristics of screen printing are summarized as follows:
1 Screen printing can use a variety of types of ink. Namely: various types of inks such as oily, water-based, synthetic resin emulsion type, and powder.
2 layout is soft. The screen printing plate is soft and has a certain elasticity, which is not only suitable for printing on soft articles such as paper and cloth, but also suitable for printing on hard articles such as glass, ceramics and the like.
3 screen printing embossing force is small. Since the pressure used in printing is small, it is also suitable for printing on a fragile shopping body.
4 The ink layer is thick and has strong coverage.
5 is not limited by the shape of the surface of the substrate and the size of the area. As can be seen from the foregoing, screen printing can be printed not only on a flat surface but also on a curved surface or a spherical surface; it is suitable not only for printing on small objects but also for printing on large objects. This printing method has great flexibility and wide applicability.
7. How many screen printing methods are there?
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.
8. How is screen printing classified?
Screen printing not only adapts to general paper printing, but also has a wide range of adaptability. For example: ceramics, glass, printed circuit boards, etc. Depending on the texture of the substrate, the printing is not the same. Although the series are inextricably linked, each has its own particularity because of the different materials (ie, chemical and physical properties). Therefore, people usually divide into different categories according to the substrate: paper printing, plastic printing, ceramic printing, glass printing, circuit board printing, metal printing, textile printing and so on. This results in their respective relatively independent printing systems.
9. What are the main applications of screen printing?
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, etc.
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, metalware, metal products.
5 glass, ceramic products printing
Glass - mirrors, glass plates, cups, bottles, etc.
Ceramics - utensils, crafts.
6 signage
Text description board, dial, shaped items.
7 circuit board printing
Printed circuit boards, substrates for civil or industrial use, and thick film integrated circuit boards.
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
10. What is the main process of screen printing? Is the process flow?
The main processes of screen printing are: making originals, making screen plates, printing, ink drying, and the like.