Screen printing belongs to stencil printing, and it is called four printing methods together with lithography, gravure printing and gravure printing. Stencil printing includes copying stencil, engraving stencil, stencil printing and screen printing. The principle of stencil printing is that when printing, the ink is transferred to the substrate (paper, ceramics, etc.). ) pass through the perforation of the template with a certain pressure to form an image or text. Transcription printing is the simplest stencil printing, which started at the end of19th century. This kind of printing is made of special wax paper with typewriter or iron pen, and printed on the wax paper with ink roller, and the ideal printing effect can be obtained on the substrate. Screen printing is widely used in stencil printing.

Screen printing is to stretch silk fabric, synthetic fiber fabric or metal screen on a screen frame, and make a screen printing plate by hand carving paint film or photochemical plate making. Modern screen printing technology is to make a screen printing plate by photographic plate making with photosensitive materials (making the screen holes in the graphic part of the screen printing plate as through holes, but not blocking the screen holes in the graphic part). When printing, the ink is squeezed by the scraper and transferred to the substrate through the mesh of the graphic part to form the same graphic as the original. Screen printing equipment is simple, easy to operate, simple in printing and plate making, low in cost and strong in adaptability. Screen printing is widely used. Common printed matter includes: color oil paintings, posters, business cards, binding covers, commodity signs and printed textiles.

[Edit this paragraph] ▼ 2. When was screen printing invented?

Screen printing originated in China and has a history of more than two thousand years. As early as the Qin and Han Dynasties in ancient China, the method of sandwiched printing appeared. By the Eastern Han Dynasty, batik printing was popular, and the level of printed products also improved. During the great cause of Sui Dynasty, people began to use silk screen to stretch the frame printing, which made the clip printing process develop into screen printing. According to historical records, the fine clothes worn in the court of the Tang Dynasty were printed in this way. In the Song Dynasty, screen printing developed again, and the original oil painting was improved. Starch rubber powder is added to the dye to make it become the size of screen printing, which makes the screen printing products more colorful.

Screen printing is a great invention of China. American Screen Printing magazine once commented on China's screen printing technology: "There is evidence that people in China used horse bristles and templates two thousand years ago. The clothes in the early Ming Dynasty proved their competitive spirit and processing technology? Quot The invention of screen printing promoted the development of human material civilization in the world. Today, two thousand years later, screen printing technology has been continuously developed and perfected, and now it has become an indispensable part of human life.

[Edit this paragraph] ▼ 3. What is the principle of screen printing?

Screen printing consists of five elements, namely screen printing plate, scraper, ink, printing table and substrate. The basic principle of screen printing is to use the basic principle that the mesh of graphic part of screen printing plate is permeable to ink and the mesh of non-graphic part is not permeable to ink. When printing, the ink is poured into one end of the screen printing plate, and the ink part of the screen printing plate is pressed with a scraper, while moving to the other end of the screen printing plate. During the movement, the scraper squeezes the ink from the grid of the graphic part onto the substrate. Because of the viscosity of ink, the imprint is fixed in a certain range. In the printing process, the scraper always contacts the screen printing plate and the substrate line, and the contact line moves with the movement of the scraper. Because there is a certain gap between the screen printing plate and the substrate, the screen printing plate generates a reaction force on the scraper through its own tension, which is called resilience. Due to the resilience, the screen printing plate is only in movable line contact with the substrate, while other parts of the screen printing plate are not in contact with the substrate. Make the ink and screen break, ensure the printing size accuracy and avoid rubbing the substrate. When the scraper is lifted after scraping the whole page, the screen printing plate is also lifted, and the ink is gently scraped back to the original position. This is a printed stroke.

[Edit this paragraph] ▼ 4. The difference between screen printing and other printing methods

Compared with other printing methods, screen printing has the following main differences:

① Strong printing adaptability: Lithographic printing, letterpress printing and gravure printing can only be printed on a flat substrate. Screen printing can be printed not only on the plane, but also on the substrate with curved surface, spherical surface and concave-convex surface. On the other hand, screen printing can be printed not only on hard objects, but also on soft objects, which is not limited by the texture of the substrate. In addition, in addition to direct printing, screen printing can also be printed by indirect printing as needed, that is, screen printing is carried out on gelatin or silica gel board first, and then transferred to the substrate. Therefore, it can be said that screen printing has strong adaptability and wide application range.

(2) Thick ink layer, strong stereoscopic impression and rich texture. The ink thickness of offset printing and relief printing is generally 5 microns, gravure printing is about 12 microns, and flexographic printing is about 10 microns. The ink thickness of screen printing far exceeds the above ink thickness, generally reaching about 30 microns. Used for thick screen printing of printed circuit boards, the thickness of ink layer can reach 1000 micron. Braille dots are printed with foam ink, and the thickness of the foam ink layer can reach 1300 micron. Screen printing has thick ink layer, rich texture and strong three-dimensional sense, which is incomparable to other printing methods. Screen printing can be not only monochrome printing, but also color printing and screen printing.

(3) Strong light resistance and bright color. Because screen printing has the characteristic of missing printing, various inks and coatings can be used, not only pastes, adhesives and pigments, but also coarse-grained pigments. In addition, the preparation method of screen printing ink is simple, for example, light-resistant pigments can be directly put into the ink for preparation, which is another major feature of screen printing. Silk screen printing products have great advantages, that is, strong light resistance. Practice shows that the maximum density range of screen printing is offset printing 1.4, relief printing 1.6 and gravure printing 1.8, while the maximum density range of screen printing can reach 2.0. Therefore, screen printing products have stronger light resistance than other types of printing products and are more suitable for outdoor use.

(4) Large printing area. At present, the area size printed by general offset printing, relief printing and other printing methods is full size. If it exceeds the full size, it will be limited by mechanical equipment. Screen printing can be used for large-area printing, and the maximum range of screen printing products today can reach 3 meters ×4 meters, or even more.

The above four points are the differences between screen printing and other printing, and also the characteristics and advantages of screen printing. Knowing the characteristics of screen printing, we can develop our strengths and avoid weaknesses when choosing printing methods, and highlight the advantages of screen printing, thus achieving more ideal printing results.

[Edit this paragraph] ▼ 5. What kind of manuscript is suitable for screen printing?

Screen printing, like other printing, needs to accurately reproduce the original text and tone. In principle, the manuscript used in screen printing is not much different from that used in other printing methods, but in the specific plate-making printing practice, its requirements are different, which is mainly determined by the characteristics of screen printing. In particular, due to the thick ink layer and bright colors of screen printing, the special effects of screen printing should be fully considered when selecting manuscripts for plate making.

In addition, the accuracy requirements of the original lines and dots used in screen printing are different from those used in ordinary printing methods. If the lines and dots of the manuscript are very fine, it is very difficult to make a plate by screen printing. Therefore, screen printing technology is not suitable for copying manuscripts with fine lines and dots. When choosing printing methods, we should fully consider the characteristics of various printing. Even in screen printing, attention should be paid to selecting the appropriate number of screen lines in order to fully reproduce the manuscript.

Screen printing is more suitable for monochrome full-color manuscripts with bright lines, and also for color manuscripts with large contrast and clear layers. Through the special effect of screen printing, the replica has rich expressive force, and through the rich and thick ink layer and the contrast between light and shade of tone, the texture and three-dimensional sense of the original content are fully expressed.

There are two kinds of screen printing photographic plate-making manuscripts: reflective manuscripts and transmissive manuscripts. It is usually based on reflective manuscripts. Color photography mostly uses transmission manuscripts.

Screen printing mainly uses positive images to make screen plates. Different plate-making methods have different requirements for manuscripts.

[Edit this paragraph] ▼ 6. What are the main features of screen printing?

The characteristics of screen printing can be summarized as follows:

① Screen printing can use many types of inks. Namely: oily, water-based, synthetic resin emulsion, powder and other inks.

② The layout is soft. Screen printing is soft and elastic, which is not only suitable for printing on soft objects such as paper and cloth, but also suitable for printing on hard objects such as glass and ceramics.

③ Screen printing has small impression force. Because the pressure for printing is small, it is also suitable for printing on fragile shopping items.

④ Thick ink layer and strong coverage.

⑤ Not limited by the surface shape and area of the substrate. As can be seen from the above, screen printing can be printed not only on a plane, but also on a curved surface or a spherical surface; It is not only suitable for printing on small objects, but also suitable for printing on larger objects. This printing method has great flexibility and wide applicability.

[Edit this paragraph] ▼ 7. How many methods are there for screen printing?

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

Manual printing refers to the manual operation from paper receiving to paper delivery, printing plate moving up and down and scraping printing.

Mechanical printing means that the printing process is completed by mechanical action. Among them, it is divided into semi-automatic and full-automatic printing. Semi-automatic means that the substrate is put in and taken out by manual operation, and printing is done by machinery. Fully automatic means that the whole printing process is completed by machinery.

There is also a fast and simple curved screen printing method-live screen printing, that is, the screen layout is removed and printed directly on the surface of the substrate. A large number of processed products, such as latex plastic buckets, cleaning buckets, washbasins, thermos bottles, cups, bowls and plates, can be printed by using the live screen printing method. At the same time, this method can be used to print signboards on cars and special-shaped planes.

Manufacture of screen printing plate with movable surface;

First, dry and repair the photosensitive text and graphic plates, then take them down and cut them according to the size. At the two ends of the screen, wood chips or aluminum sheets are used as the skeleton, which can be closely bonded with adhesive tape or directly bonded with adhesive to make the required movable screen.

Operation method of movable surface net:

According to the substrate, different printing materials are selected for blending: firstly, flat plate and flat plate are selected for ink blending; Then, a person holds the movable screen in both hands and sticks the printed part tightly to the surface of the substrate; Another person uses a scraper to dip the ink on the ink mixing board evenly; Then the scraper is evenly placed on the layout of the ink adjustment board for scraping and printing.

If the printed graphic area is too large, you can pour the ink on the layout according to the situation, but don't let the ink flow out of the substrate. Pay attention to the preparation of ink not too thin, not too dry, dry or wet. Printing words and pictures in a small area can be operated by one person. The method is to stick one end of the movable plate to the required position of the substrate machine with the packaging tape, and then stick the printing plate tightly to the substrate with the other hand for printing. Note: The board must be gently lifted in the direction of the end of the adhesive tape. The same is true if two people operate the advertisement. Printing by this method has the advantages of convenient operation, flexible requirements for substrates, large capacity, small quantity, low cost and energy saving.

[Edit this paragraph] ▼ 8. How is screen printing classified?

Screen printing not only adapts to ordinary paper printing, but also has wide adaptability. For example: ceramics, glass, printed circuit boards, etc. Printing is different according to the texture of the substrate. Although there is an inseparable internal relationship between the series, each series has its own particularity because of the different texture of the matrix (that is, different chemical and physical properties). Therefore, people usually divide it into paper printing, plastic printing, ceramic printing, glass printing, circuit board printing, metal printing, textile printing and so on according to the different substrates. In this way, a relatively independent printing system is formed.

[Edit this paragraph] ▼ 9. What are the main applications of screen printing?

Screen printing is widely used. Any object can be used as a substrate except water and air (including other liquids and gases). Someone once said when evaluating screen printing: If you want to find an ideal printing method on the earth and achieve the printing purpose, it is probably screen printing.

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

① Paper printing

Art printing-advertising, pictorial, calendar, lantern paper, etc.

Label printing

Transfer printing

Packaging and printing

Building materials printing-wallpaper pasting, etc.

② Plastic printing

Plastic film-vinyl toys, schoolbags, plastic bags, etc.

Plastic target-pseudometal composite material and various targets.

Production parts-instrument parts.

③ Woodworking printing

Crafts-lacquerware, wooden crafts, toys.

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

④ Printing of metal products.

Metal cylinder, metal container, metal product.

⑤ Printing of glass and ceramic products.

Glass mirror, glass plate, cup, bottle, etc.

Ceramics-utensils, handicrafts.

6 signs

Word board, dial, special-shaped article.

⑦ circuit board printing

Printed circuit board, civil or industrial substrate, thick film integrated circuit board.

8 printing and dyeing

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

Other printing-pockets, shoes, numbered cloth and various bags, backpacks, handbags, schoolbags, etc.

Pet-name ruby leather products printing

[Edit this paragraph] ▼ 10. Detailed description of several screen printing types and their application methods

As a widely used printing, screen printing can be divided into fabric printing, plastic printing, metal printing, ceramic printing, glass printing, electronic product printing, lottery screen printing, electronic decorative billboard screen printing, metal billboard screen printing, stainless steel product screen printing, reflective screen printing, screen transfer anodizing, screen printing printed matter and lacquer screen printing.

Fabric printing

Fabric printing refers to the process of forming patterns on fabrics through printing. Printing methods include stencil printing, screen printing, rotary screen printing, transfer printing and multicolor spray printing. Among them, screen printing originated from stencil printing (including stencil printing and zinc printing), gradually moved from manual operation to semi-automation and full automation, and later developed from flat screen printing to rotary screen printing.

There are generally several printing methods for fabric printing:

1. Paint direct printing

Pigment direct printing is to directly print the prepared printing paste on the fabric, which is the simplest and most commonly used printing process. Pigment direct printing technology generally refers to printing on white or light-colored fabrics, which is convenient in color matching, simple in process, and can be dried after printing, and is suitable for textiles with various fibers. The direct printing process of coatings can be divided into Akramine F adhesive according to the adhesives commonly used at present. Three direct printing processes: acrylate glue, styrene-butadiene emulsion and chitin glue.

2. Silk printing

The main methods of screen printing are direct printing, discharge printing and resist printing. The direct printing method has been introduced before, and the discharge printing method, transfer printing method and infiltration printing method will be introduced respectively below. This paper mainly introduces the dye-proof printing method.

3. Knitted underwear printing

Knitted underwear printing mainly adopts pigment direct printing process, and the fabric can be dried twice or naturally after printing, thus avoiding the problems of easy deformation of knitted fabric and difficult wet treatment of agricultural film. The printing method is mainly flat screen screen printing, which is divided into two ways: manual scraping and machine operation. This printing method can adapt to various flower patterns of various forms and structures, and is suitable for small batch and multi-color production.

4. Discharge printing

Discharge printing, also known as block printing, refers to the printing method of printing colored fabrics with discharge agents, which destroys some dyed pigments and thus prints various patterns and patterns. Discharge agent is a chemical that can make the dye base fade. Hanging white, stannous chloride, etc. This method can be divided into two types: white pattern (white drawing) and color pattern (printing). The latter dyeing method makes the fabric pattern fine, but the process is complicated and the cost is high.

5. Screen printing and burning

Burnout refers to the use of two kinds of fiber blended fabrics with different acid resistance. After acid rotten flower paste printing and chemical treatment, acid-resistant natural fibers partially rot, and acid-resistant chemical fibers are exposed, forming crystal clear flower patterns. Its special style makes the burned products have a high-grade and gorgeous feeling. Burnt-out products are not only gorgeous in appearance and excellent in internal quality, but also have the properties of wear resistance, high strength, easy washing, quick drying and non-ironing, which are well received by domestic and foreign markets. The research and application of burnt-out technology is popular in textile printing and dyeing industry in recent years.

6. Wool printing

At present, printed woolen fabrics are mainly thin plain fabrics or tulle fabrics, which are mostly used to make women's shirts, dresses, quilts and skirts. Wool fabric printing includes not only direct printing, but also pull printing, dye-proof printing and transfer printing. Wool blended fabric printing also accounts for a certain proportion. At present, the relief finishing of wool fabrics is also quite popular, mainly used for sweaters.

7. velvet printing

Diamond printing uses the characteristics of silk screen printing to print on velveteen, which can obtain a special flash effect and shine like a natural diamond in the sun.

8. Foam printing

There are many kinds of fabric special printing, and foam printing is one of them. Foam printing is characterized by strong three-dimensional sense, similar to hand embroidery, soft to the touch, wear-resistant, washable, good in fastness and elasticity, and can be widely used in tablecloths, curtains, tea towels, handkerchiefs, pillow towels, clothing, tourist souvenirs and so on. It is not only suitable for cotton, linen, silk and other natural fiber fabrics, but also suitable for rayon fabrics.

9. Flocking printing

Electrostatic flocking is a new technology in textile industry at present. It is a product that uses high-voltage electrostatic field to plant short fibers on grey cloth. Flocking products are widely used in rubber, plastic, artificial leather and decorative products, especially small quantities of tourism products, because of their simple technology, strong three-dimensional sense and low cost. Flocking patterns on shoes, hats, children's clothes, trademarks and clothing will make them different.

10 transfer printing transfer printing is a printing process that relies on the sublimation of dyes and the diffusion and affinity of dye vapor to fibers to complete the coloring effect. Transfer printing is a practical printing and dyeing production method in waterless processing. In addition to not using water, there is also a main feature that the paper has small deformation and can print fine multi-level patterns and photographic pictures. Transfer the pattern picture to the cloth truly. Its effect is sometimes better than the general anti-corrosion discharge.

In addition to the above ten common printing methods, there are some special printing methods, such as anode transfer printing, photoluminescence printing, fluorescent printing, gold and silver powder printing, pigment foam printing, color-changing printing, fragrance printing, diamond printing, pearl printing and so on.

[Edit this paragraph] Screen printing of glass

According to the principle of screen printing, ink is printed on the surface of flat glass, and then the curing measures of ink are taken to make the pattern firm and durable. The process flow is as follows:

Drawing → Sizing → Drying → Printing → Developing → Drying.

↓

Flat glass → cutting → edging → cleaning and drying → printing.

↓

sinter

Glass suitable for printing

Cut the glass according to the user's requirements, which can be regular or irregular, then edge-grinding, cleaning and drying for later use. Special attention should be paid here. There should be no water marks on the surface of flat glass.

Screen selection

Screen printing plate for flat glass printing is the same as ordinary screen printing plate. Glass screen printing plate adopts synthetic fiber mesh, stainless steel mesh and natural fiber mesh. When printing ordinary pigments, the above two kinds of screens can be used, and generally the cheap synthetic fiber screen is selected; When used as gold and silver decoration, stainless steel mesh cannot be selected. The size of the screen is generally 270 ~ 300 mesh.

Selection of grid structure

At present, the regular mesh frame with small deformation is aluminum alloy mesh frame, and its size is larger than the pattern. The specific size should be 70 ~ 100 mm from the outer edge of the pattern. In addition, the strength of the mesh frame is very important, and the key is that the horizontal stiffness is sufficient.

Stretching net

Select the mesh wire and the mesh frame, and combine them together to form the stretched mesh. There are many ways to stretch the screen, such as manual, electric and pneumatic. At present, the more advanced one that can stretch high-quality screen is pneumatic screen stretcher. The requirements for stretching the net are uniform tension, vertical screen latitude and longitude, firm glue and no looseness.

Select photosensitive adhesive

At present, there are dichromate, diazonium salt and iron salt on the market. The requirements of screen printing plate-making for photosensitive adhesive are: good plate-making performance and easy coating. The photosensitive spectrum is in the range of 340 ~ 440 nm, with good developing performance, high resolution, good stability, convenient storage, economy and sanitation, and no toxicity and pollution. The requirements of printing on photosensitive materials are: the plate film formed by photosensitive materials adapts to the performance requirements of different kinds of inks. It has considerable printing resistance and can withstand considerable scraping pressure by scraper; Good bonding force with screen, no peeling failure during printing; It is easy to peel off, which is beneficial to the recycling of mesh board.

cross band

After selecting the above materials, coating photosensitive adhesive in the darkroom; Uniform requirements, and then drying. It is generally required to brush twice. Printing needs to be exposed on a cold light printer, and the exposure time depends on the pattern, generally between 12 ~ 30 minutes. After exposure and development, the screen is made.

Printing brush

There are several types of flat glass printing machines: manual, semi-automatic and fully automatic. Manual printing machine is suitable for small batch and small specification of flat glass. Semi-automatic and full-automatic printing machines are suitable for large-scale and large-area multi-color printing, and have the advantages of precision and speed. The largest semi-automatic printing machine can print 2000× 1500mm glass. Automatic printing machines are generally used to print automobile windshields, and several foreign companies can provide such equipment.

Oily ink

Decorative ink for flat glass can be divided into organic ink and inorganic ink. The colorant and binder of organic ink are all organic substances, and the effect of decorating flat glass with this ink is also good, but the film has poor firmness and chemical stability, which is a short-lived decoration method. Inorganic ink consists of colorant, flux and adhesive, and the colorant is inorganic colorant such as chromium oxide and cobalt oxide. Fluxes are low-melting glass, and common ones are lead oxide and borosilicate glass. The most important thing about the performance of flux is that it is not too different from the thermal expansion coefficient of printed glass. Typical flux composition: SiO2 19 182%, As2O3 21kloc-0/3%, MgO 0 146%, PBO 62 1 10%. K2O 1 183 %，B2O3 10 175 %，Al2O3 1 163 %，Na2O 1 176%。 The connecting agent scraper oil in inorganic ink is an organic substance, which burns completely in the sintering process, but it has no effect on the decorative effect.

Scraping oil consists of ethyl cellulose 3g, terpineol 100ml, turpentine 10ml and alkyd resin 5ml. The ratio of pigment to binder of inorganic ink is 10g: 8ml, and it can be stirred and ground.

aflame

Glass is an amorphous inorganic material that softens with the increase of temperature. When it is heated to the softening temperature of glass, the glass will be deformed. Glass glaze is decorated on the surface of flat glass by screen printing, which needs to be consolidated on the glass surface by high temperature sintering, but the sintering temperature must be lower than the softening temperature of decorative glass to ensure that decorative glass is not deformed. The firing temperature of glass glaze is generally not higher than 520℃, and is generally controlled at 480 ~ 520℃.

Low temperature glass glaze is produced by several domestic manufacturers, and the price is relatively low. There are several companies in the world that can provide similar products, but the price is ten or twenty times different from that of domestic products. The domestic consumption level has not reached the level of using this glaze, but the glaze provided by foreign countries is indeed much better than the domestic color and level. To improve the quality of decorative glass, it is necessary to improve the grade of glaze. Sintering equipment includes flame furnace and resistance furnace. Resistance furnaces are divided into vertical suspension type and horizontal roller type according to the suspension mode of glass.

Vertical hanging sintering furnace has the advantages of small sintering deformation and over 95% yield, but the equipment is complicated. If the horizontal roller table is not well adjusted, it will easily cause large deformation and low yield. In addition, it is feasible to produce decorative glass by using horizontal tempering furnace, which improves the grade of products and ensures safety. It is an ideal sintering method.

[Edit this paragraph] ▼ 1 1. Development direction of screen printing technology

Undoubtedly, if a rotary screen printing machine using water-based ink can be developed, if the efficiency of the screen printing machine is higher, if the parameters such as the pressure, speed and angle of the scraper can be read and programmed, if the copy can be repeatedly produced according to the procedure, and if the production data can be correctly used in the whole process from prepress preparation to printing, screen printing will certainly get greater development. China screen printing will develop in depth and breadth in the future. "Deep" means developing to a higher level. Advanced technologies such as computer design, plate making and electronic engraving have been widely used in the international screen printing industry, but these new technologies are still in the research and experimental stage in China. "Guang" refers to the development of new screen printing products, such as outdoor large-scale screen printing advertisements. Therefore, packaging and printing in China will make a leap in equipment, technology and scale.