Printing elements of Shanghai Printing Factory

(Typogra-phic Printing Press)

Characteristics of the printed matter: There are slight raised marks on the paper back of the printed matter, the edges of the lines or dots are neat, and the printed ink appears in the center. Light, the edge of the raised print is under heavy pressure, so there is a slight raised print.

Printing features: The ink color is thicker (the thickness of the ink layer is about 7μm). Can be printed on rougher substrates. Tone reproduction is average.

Application scope: trademark, packaging and decoration printing, newspaper printing, etc. Letterpress printing machines can usually be divided into three categories: flat-flat type letterpress printing machines, round flat-type letterpress printing machines, and round flat type letterpress printing machines:

⒈ Flat-flat type letterpress printing machines

The flat-flat type letterpress printing machine is a unique printing machinery in letterpress printing. The disc machines and square box machines currently used in printing plants belong to this type of machine. This type of printing machine produces large and uniform pressure during the printing process, and is suitable for printing trademarks, book covers, fine color pictures and other printed matter.

⒉ Round flat letterpress printing machine

When printing, the circular impression roller and the flat printing plate are in contact, and the printing speed is The flatbed printing press is fast and is conducive to large-format printing.

According to the movement pattern of the impression cylinder, circular flattening letterpress printing machines are divided into two types: one-turn and two-turn.

⒊ Cylindrical letterpress printing press

It is divided into sheet paper and roll paper. The printing speed is high, and it is mainly used to print large quantities of newspapers, books, periodicals, magazines, etc.

The process of letterpress printing machine

The printing process using lead plate and photosensitive resin plate is: preparation before plate mounting → plate mounting → printing → quality inspection.

Preparation before mounting

Every product printed must be carried out in accordance with the requirements of the construction order. The construction order is also called a production notice. The content includes: book title, format, number of copies, page numbers, printing and binding methods, paper specifications, quality requirements, completion date, etc.

Preparatory work can only be carried out after understanding the requirements of the construction order.

First check the printing plate, paper, and ink to see if they meet the requirements, then check whether the machine has been adjusted, replace the printing lining, and install the plate mounting equipment such as: plate frame, plate support (base plate) ) Prepare wooden strips, corks, etc., measure the size of each part, and then install the plate.

Plate mounting

The process of installing printing onto the printing press in sequence according to certain specifications, and making the printing quality and specifications meet product requirements through padding and other operations is called plate mounting. or published. The printing process of the lead plate is the most complex. The process flow is: plate dividing and pasting → plate placement → bottom pad → middle pad → nail plate → full page → top pad → proofing

⒈Plate splitting and dividing Posting

Publishing and posting refers to the reasonable arrangement of the page number sequence of the printing plate. Commonly used printing methods for books and periodicals include reprinting and overprinting.

After printing the front side with one printing plate, printing the reverse side without changing another printing plate is called replica printing. Installing a printing plate once can print products on both sides of the paper, and cut it from the middle to get two printed sheets with the same print. When using reprint printing, you only need to divide the printing plate into appropriate signatures according to the page number order of books and periodicals.

Using half of the entire printing plate to print on the front of the paper, and then using the other half of the printing plate to print on the back of the paper, is called overlay printing. When using set printing, the printing plate must first be divided into a number of full pages according to the page number, and then the full plate must be divided into two sets of front and back printing plates with the same number of blocks.

In addition, you can also divide the pages according to the binding method. For example, for a book that is saddle-stitched, the front and back pages of the book should be connected together, and the page numbers in the middle should be separated and printed into separate pages, and the pages should be stacked together during binding.

⒉Placement

According to the requirements of binding and folding, and in the order of page numbers, place the printing plates in the correct position.

⒊Padding

The process of adjusting the pressure on the surface of the printing plate is called padping. There are three ways to pad the plate: bottom pad, middle pad, and top pad.

When the pressure on more than 1/3 of the page is too light or too heavy, stick a piece of paper under the bottom plate or tear off the paper under the bottom plate, which is called underlayment.

When the pressure on the layout of less than 1/3 and more than 1 square centimeter is unbalanced, paper should be placed under the lead plate or the back of the lead plate should be thinned, which is called a middle pad.

The upper pad is performed after the lower pad and the middle pad. First, adjust the ink color of the printing machine to basically match the ink color during printing, and print out the pad sample. Then check the pressure on the upper pad sample word by word and line by line, and then use thin paper strips to paste on the impression roller in an orderly manner until the ink color is uniform and the pressure meets the requirements.

⒋Fixing the printing plate

There are many types of letterpress printing machines, and the forms and thicknesses of the printing plates are different, so the methods of fixing the printing plates are also different. For example: a flat lead plate is fixed on the bottom plate with small iron nails on a circular flat relief printing machine. The LP1101 sheet-fed web press uses screws to fasten the printing plate to the printing plate cylinder. The photosensitive resin plate is usually directly adhered to the printing plate cylinder with double-sided tape or to a film wrapped around the cylinder. on the base (the film can be removed and plated under the machine, reducing the downtime during plate loading).

⒌Full page

According to the requirements of the construction order, the operation of fixing the printing plate in the correct position is called full page. Through the whole page, the size is correct and the overprinting of words, lines, page numbers, etc. is accurate. There are three methods for making the entire page: scratching, punching, and red-printing. The whole page work of the flat lead plate is carried out after the bottom and middle pads are basically fixed, and the position of the printing plate is straightened or moved with a punching plate. The curved cliché can loosen the screws holding the plate in place and move it. The photosensitive resin plate is adhered with double-sided tape. You can gently lift the plate and then re-attach it.

When mounting the plate, printing marks must also be installed. There are two types of printing marks. One is the side gauge mark, which is installed at the edge of the side gauge paper to check whether the overprinting is accurate and whether there are inverted heads or white pages. The other is the binding fold mark (also called the post code), which is installed at the outermost stitching of each sticker. The purpose is to check whether there are more or less posts on the book stickers when binding books and periodicals.

Printing

After the plate mounting is completed, preparations must be made before printing.

The preparation work includes: stacking the paper to be printed, checking the layout and printing proofs, checking the text quality to prevent problems such as bad words, broken pens and missing strokes. Check whether the specifications and dimensions meet the specified requirements, check the fastening of the printing plate, and prevent the printing plate from loosening during printing.

During the printing process, it is necessary to randomly check the quality of the printed matter at any time, such as whether there is dirt, running, pasting, falling off, etc. If any problems are found, deal with them in a timely manner. During printing, you should always pay attention to the operation of the machine. If you find abnormal sounds, you should stop the machine for maintenance.

Photosensitive resin plate has a certain degree of elasticity and good ink transferability. The printing pressure and ink roller pressure should be less than that of the lead plate. Otherwise, the printing image and text will easily be deformed. The appropriate pressure will ensure that the imprint is solid but not empty. as well. The ink concentration used should be higher than that of the cliché ink, but the amount of ink can be less than that of the cliché. When removing ink stains on the page, just wipe it with a cloth dipped in kerosene or gasoline. It is not advisable to use a hard-bristled brush.

Letterpress printing

The ink feeding device of the printing press first distributes the ink evenly, and then transfers the ink to the printing plate through the ink roller.

The graphic part of the relief plate is much higher than the non-graphic part. Therefore, ink can only be transferred to the graphic part of the printing plate, while the non-graphic part has no ink.

The paper feeding mechanism transports the paper to the printing component. Under the action of printing pressure, the ink in the graphic part of the printing plate is transferred to the substrate, thereby completing the printing of a printed matter.

Common letterpress printing methods: movable type printing (including clay movable type and lead movable type), flexographic printing. Today only flexographic plates are still widely used.

Principle of flexographic printing

The ink in the ink fountain, under the action of the anilox roller in the flexographic printing component, the anilox roller cells and the surface of the anilox roller are all Printing ink applied.

The ink on the surface of the anilox roller is scraped off under the action of the doctor blade, so that the ink only exists in the cells of the anilox roller.

The ink in the cells is transferred to the flexible printing plate under the action of pressure.

Finally, under the action of printing pressure, the ink on the printing plate is transferred to the substrate. (Lithographic PrintingPress)

Introduction to lithographic printing press

The characteristic that distinguishes lithographic printing presses from other printing methods is that it is equipped with a moistening device. Except for the lithographic press, the engraving machine and the proofing machine, they are all rotary printing presses that press the circle.

There are two types of sheet-fed and web-fed printing machines, and the printing plates are metal sheets (zinc plates, aluminum plates, etc.). Offset printing machines are mostly used for color printing.

Sheet-fed offset printing press

The arrangement of the cylinders in the printing part is based on the structural design of different machine models and the number of colors printed at one time. There are single-unit single-color, single-unit two-color and Multiple units and multiple colors. Usually a single unit monochromatic machine is a three-roller type, as shown in Figure 1. The two-color single unit is a five-cylinder type, that is, the impression roller is composed of two colors, as shown in Figure 2. A three-cylinder two-color, four-color, five-color, and six-color offset printing press with one unit and one color is shown in Figure 3. In addition, there is a single-color offset printing press that prints two sides at a time. It consists of 4 rollers. There is no impression roller. It relies on 2 blanket rollers to press the paper between them for double-sided printing, as shown in Figure 4, also It's called a counter-roller (B-B type) offset printing press. Three-cylinder machines and multi-color offset printing machines are equipped with a paper turning mechanism, which can also be used for double-sided printing. The paper feeding and delivery parts adopt a paper pile type. Sheet-fed offset printing machines are mainly used to print exquisite color pictures, book covers, posters, trademarks, packaging and decorations, etc. Double-sided offset printing machines are mainly used to print the text of books, periodicals and magazines.

Web offset printing machine

Use web paper for double-sided continuous printing. The delivery part has a cutting and folding device, and some are also equipped with automatic paper splicing and paper tension. Control, automatic ink color control, automatic registration control, glazing device, drying box, etc. Web offset printing machines have the following types according to their uses and structures: ①Four-cylinder type (B-B type). The arrangement of the rollers is similar to that of the sheet-fed paper machine. There are two types of rollers arranged up and down for horizontal paper feeding and horizontal arrangement for vertical paper feeding.

Lithographic printing machine

The horizontal paper feeding type is a unit that prints one color on each side. Several units are arranged horizontally according to the number of colors printed, as shown in Figure 5. The vertical paper feeding type has several units arranged vertically according to the printing colors, as shown in Figure 6. ②Satellite type. There is a special impression cylinder in the unit, which is surrounded by 4 pairs of plate cylinders and blanket cylinders for single-sided 4-color printing and can print general-quality color prints. As shown in Figure 7. ③Satellite B-B type. On the basis of the satellite type, a set of B-B type vertical paper feeding units is added, as shown in Figure 8. It can be used for multi-color printing on one side and single-color printing on the other side. It is mainly used for color newspapers and publications. In addition, various types can be formed according to the requirements of different printed matter, and various serial paper feeding methods can be used to achieve the requirements of printing single or double sides, single color or multi-color on each side. Web offset printing presses are mainly used in large and medium-sized printing plants to print large quantities of newspapers, books, periodicals and color prints with short cycle times.

Other categories

The number of colors in a printing process includes single color, two colors, four colors, five colors, six colors, and single-sided and double-sided printing.

Main structure

The main structure consists of five parts: paper feeding, moistening, ink feeding, printing and paper delivery. The new machine is equipped with computer-controlled ink color and registration devices. Since the 1980s, devices for controlling water volume have appeared.

The arrangement of the cylinders in the printing part of the sheet-fed offset printing press is divided into single-unit single-color, single-unit two-color and multi-unit multi-color according to the structural design of different models and the number of colors printed at one time. Usually the single-unit monochromatic machine is a three-roller type. The two-color single unit is a five-cylinder type, that is, the impression roller is composed of two colors. Three-cylinder two-color, four-color, five-color, and six-color offset printing presses with one unit and one color.

In addition, there is also a single-color offset printing press that prints both sides at one time. It consists of 4 rollers. There is no impression roller. It relies on 2 blanket rollers to press the paper between them for double-sided printing. Also called counter-roller (B-B type) offset printing press. Three-cylinder machines and multi-color offset printing machines are equipped with a paper turning mechanism, which can also be used for double-sided printing. The paper feeding and delivery parts adopt a paper pile type.

Sheet-fed offset printing machines are mainly used to print exquisite color pictures, book covers, posters, trademarks, packaging and decorations, etc. Double-sided offset printing machines are mainly used to print the text of books, periodicals and magazines.

Main features

The graphic and text portions and blank portions of the printing plate surface of the offset printing machine are almost on the same plane. It uses the principle of water and oil repelling each other to make the graphic part resistant to water and lipophilic, and the blank part resistant to oil and hydrophilic without ink staining. Under the action of pressure, the ink in the inked part is transferred to the surface of the printed matter. , thereby completing the printing process.

After the indirect printing method was adopted, lithographic printing presses developed rapidly and came in many varieties, such as micro offset printing presses for office use, large, multi-color, high-speed offset printing presses for books, newspapers and magazines, used for sheet-fed paper or web-fed, single-sided or double-sided lithographic printing presses. Among them, single-color offset printing machines and web offset printing machines are representative. Lithographic printing presses have widely adopted electronic computer control devices and are becoming increasingly technologically advanced. Plate making equipment has also developed to use electronic color separation machines, and pre-coating is widely used. Intaglio Printing Press The ink in the graphic part is left, and then passed through the paper. The impression roller is used to imprint the back of the paper, so that the ink in the concave part is directly transferred to the paper surface. Finally, the printed matter is stacked or rewinded through the delivery part.

Printing method

The gravure printing machine uses a circular-pressure direct printing method. The printing plate is directly printed on the printing plate cylinder, and the ink is supplied by immersion ink or inkjet. There is no Ink leveling mechanism. Due to the thick ink layer, use of highly volatile quick-drying ink requires a drying device.

It can be mainly divided into:

1. The machine models are divided into sheet-fed and web-fed gravure printing machines according to the paper used.

2. The number of colors the unit can print at one time is divided into single color, four colors, five colors, six colors, etc., and it can be divided into single-sided printing and double-sided printing.

The main structure of the gravure printing machine:

The main structure of the gravure printing machine is composed of five parts: paper feeding, ink feeding, printing, drying and paper delivery.

1. In the paper feeding part, the sheet-fed gravure printing machine uses a paper pile type to continuously feed single sheets of paper, while the web-fed gravure printing machine uses a roll paper to continuously feed paper.

2. In the printing part, the printing plate cylinder and impression cylinder are arranged in three ways: vertical, horizontal, and inclined. The printing plate cylinder is arranged below. Generally, each unit has a plate cylinder and an impression cylinder. In order to increase the printing pressure, some are equipped with 2 impression rollers.

3. The ink supply device includes direct ink supply in which the printing plate cylinder is partially immersed in the ink tank, and indirect ink supply in which the ink is transferred to the printing plate cylinder from an ink outlet roller immersed in the ink tank. Some high-speed machines also use inkjet.

4. The drying part uses hot air heated by electricity or steam, and some use infrared or far-infrared lamps to dry the printed matter.

5. In the paper delivery part, single sheets of paper are stacked into paper piles, and roll paper is made by cutting and folding paper strips and stacking them or rewinding them into paper rolls. The structure of the printing part of the web multi-color gravure printing machine has two types: group type and satellite type. The former is to set up the unit according to the required number of colors. Each unit has 1 plate roller and 1 to 2 impression rollers, and the paper delivery part adopts the rewinding method. Satellite four-color gravure printing machine, the printing part has a large impression cylinder and 4 sets of plate cylinders. There are also combinations of gravure printing with offset printing or letterpress printing, die-cutting, etc. to adapt to different requirements of printed matter.

Main features

Gravure printing products have the advantages of thick ink layer, rich layers, strong three-dimensional effect, and good printing quality. They are mainly used for printing exquisite color pictures, trademarks, and decorations. , securities and color newspapers, etc. Due to the complex plate making process, long cycle time and environmental pollution of benzene-containing ink of gravure printing machines, it has not been widely used in China. Therefore, measures such as improving the plate-making process, shortening the plate-making time, using non-polluting inks, reducing energy consumption, and reducing costs are being studied and improved.

The main feature of the gravure printing machine is that the picture and text part on the printing plate is concave and the blank part is raised, which is exactly the opposite of the layout structure of the letterpress printing machine.

When the machine prints a single color, it first immerses the printing plate in the ink tank and rolls it, so that the entire printing plate surface is covered with a layer of ink. Then, the ink layer that belongs to the blank part of the printing plate surface is scraped off, and the convex part forms a blank, while the recessed part is filled with ink. The deeper the recess, the thicker the ink layer. The machine transfers the ink in the recessed parts to the printed matter through pressure, thereby obtaining printed matter.

When printing multiple colors, the overprinting method or the indirect local inking method is used to distribute the inks of various colors on the relevant parts of the printing plate surface as needed. The basic printing principles and printing orders for multi-color printing Same color. There are two main types of printing plates used in gravure printing machines. One is a photogravure plate, which is a photocopying plate; the other is an engraving plate. The engraving of the engraving plate includes manual engraving, mechanical engraving and electronic engraving.

Gravure printing product failure

Fault one. Periodic ink color changes appear on printed matter with uneven ink shades. The elimination methods include: correcting the roundness of the printing plate cylinder, adjusting the angle and pressure of the squeegee or replacing the squeegee with a new one.

Fault 2. The imprint becomes mushy and fluffy. The printed image is layered and mushy, and burrs appear on the edge of the image and text. Elimination methods include: removing static electricity from the surface of the substrate, adding polar solvents to the ink, appropriately increasing the printing pressure, adjusting the position of the squeegee, etc.

Fault three. Blocking ink dries up in the cells of the printing plate, or the cells of the printing plate are filled with paper wool and paper powder, which is called plate blocking. The elimination methods include: increasing the solvent content in the ink, reducing the drying speed of the ink, and printing on paper with high surface strength.

Fault 4. The ink spills out and spots appear on the solid part of the printed matter. The elimination methods include: adding hard ink-adjusting oil to increase the viscosity of the ink. Adjust the angle of the squeegee of the gravure printing machine, increase the printing speed, replace the deep-cell printing plate with a shallow-cell printing plate, etc.

Fault five. Scratched prints have squeegee marks on them. The troubleshooting methods include: printing with clean ink without foreign matter mixed in. Adjust the viscosity, dryness and adhesion of the ink. Use a high-quality squeegee and adjust the angle between the squeegee and the printing plate. (Silk Screen Printing Press)

Introduction to stencil printing

Polish printing is also called screen printing, which is a printing method that uses silk screen as the plate material. The specific method is to produce two parts, graphics and text, and a film on the printing plate. The role of the film is to prevent the ink from passing through, while the graphics and text part leaks the ink onto the substrate through scraping and pressure from external forces, thus forming a Printed graphics. The principle is: dig holes in a flat plate, and then apply ink so that the ink leaks through the holes and onto the substrate. Hole printing has a wide range. This method can be used to produce prints, and can also be used for packaging and printing of daily necessities and industrial supplies. For example, our common printing of fonts on cars, printing of graphics and text on outer packaging boxes, etc., mostly use perforated printing methods. The perforated plate is also called the transparent plate and the template in Chinese, and it is called the pattern paper and the Kawasaki version in Japanese.

Stencil Printing

The principle of stencil printing is that under the action of the scraper, the screen printing ink in the screen frame passes from the mesh of the screen (the graphic part) The ink leaks to the printing substrate. Since the ink in the non-graphic part of the printing plate is blocked by the screen mesh, the ink cannot leak to the printing substrate, thereby completing the printing of the printed matter.

Any printed matter with a three-dimensional ink layer, such as bottles, cans, curved surfaces and general circuit board printing, usually uses stencil printing.

The layout is a mesh or a thin layer with certain elasticity. The graphics and text are partially transparent, and the ink or color material leaks through the printing plate onto the substrate. It is the same as the three major printing methods of lithography, letterpress and gravure. The fourth printing method of juxtaposition. But it is still customary for some people to classify it into the category of special printing.

There are four types of hole printing: parting plate, transcription hole plate, typing hole plate and screen printing, and each has several different plate making methods. They all have the characteristics of lightweight equipment, simple process, easy operation, and are widely used.

①Type version. Carve text or graphics on wood chips, cardboard, metal or plastic sheets to make a hollow printing plate, and use brushing or spraying to make the color material pass through the printing plate and print onto the substrate.

This is one of the oldest techniques. Judging from the unearthed ancient printed fabrics, patterns were already used in China during the Spring and Autumn Period. Because the method is simple, it was still used among the people in the 1980s.

②Transcription hole version. To make plates by handwriting, the earliest method was to use a brush dipped in dilute acid (such as sulfuric acid) to draw graphics on porous paper coated with gelatin. The dilute acid dissolved the gelatin film and exposed the porous fibers to form a hole plate, which was called a brush writing plate. Since the edges of the graphics are easily corroded by acid and the printing accuracy is poor, this method has been rarely used since the emergence of stylus transcription plates. A stylus transcription plate is a printing plate made of wax paper that is written on a textured steel plate with a stylus. The scored part of the wax paper can allow ink to pass through. This method is said to have been invented by T.A. Edison in 1886. Since transcribed handwriting differs from person to person and is far less clear than the typing punch plate invented later, its use has been gradually reduced. The water-washable transcription plate is made by dipping a pen into water-soluble glue to write on porous paper, and then coating a layer of water-insoluble glue film on the paper. After drying, it is washed with water to dissolve the writing part to form a hole plate.

③Typing hole plate. A typewriter is used to print movable type on wax paper. The impact of the movable type causes the wax paper to form a perforated text plate that is permeable to ink. The first practical English typewriter model was produced in the United States in the 1880s. The Chinese character typewriter was first invented in Japan during the Taisho period (1912-1926) and became popular rapidly after World War II. The development of computer word processing technology and office automation systems has gradually replaced typing and hole printing.

④Silk screen printing. It has become the mainstream of stencil printing since the 1950s.

Basic Principles

In addition to the three major formats of letterpress, lithography, and gravure, another kind of handicraft-like stencil printing also occupies a unique segment of the modern printing industry. Due to the modern The business world is deeply affected, and it is also highly valued in the design world. Due to its unique expressive power, stencil printing has a wide range of applications. Designers or ordinary people must understand some concepts. Any printing part that looks like a hole and is printed in this way is called "hole printing".

For example, generally using a steel needle to engrave on wax paper or printing with an electronic etching mimeograph machine, this is the more basic stencil printing, and what is used in design or industry is screen printing. Printing), silk screen printing was used in handicrafts and the like in the early days. Now it has developed into automated printing. In terms of plate making, photographic plate making has been used to form the layout. Because of its thick ink color and a special feeling, it is best used for special printing. Effect print. It can also be printed on three-dimensional surfaces such as boxes, circles, cans, etc. In addition to printing paper, it can also be printed on cloth, handles, plastic sheets, metal sheets, glass and other materials.

Printing method

Because the stencil plate is a transmission printing, the ink supply device is above the layout, and the paper is placed below the layout. The printing method is that the layout is positive and transparent. style, the pattern will still be correct after printing. Due to different printing purposes, the layout can be made into a curved version according to the surface of the printed matter. Anything outside the limitations of the three major printing formats can generally be achieved by stencil printing. As for the pressure method, it is not flat plate pressing or round plate pressing, but an extension of the Chinese printing method during the early invention of printing, which is the "horizontal imprinting method". Of course, the pressure is also reduced to a minimum.

Advantages and disadvantages of stencil printing:

①Advantages: Thick ink, bright colors, can be printed on any material, and curved surface printing is possible.

②Disadvantages: slow printing speed, low production volume, difficult color printing performance, not suitable for mass printing.

Features

Due to the need for stencil printing to drop ink through mesh-shaped holes, the surface of the printed matter will have a cloth pattern. Most of them are printed on silk cloth, so the texture of silk cloth is produced. Others, such as copper mesh or plastic mesh, etc., also produce this phenomenon. At the same time, because the ink reaches the paper surface through the mesh, the printing ink is extremely thick, and the thickness can be seen with the naked eye. One of its characteristics is that the printing ink does not shine.

Polish printing process

Screen printing can be done manually or mechanically. The printing principle is generally based on manual printing. The process flow is:

Printing preparation→Squeegee adjustment→Printing→Print drying

Printing preparation, including installing the screen printing plate on the printing press, adjusting the printing gap, determining the position of the substrate, and preparing printing ink, etc. .

For screen printing, inks with lower yield values ??should be used. The viscosity of the ink cannot be too high.

The screen printing ink is scraped onto the substrate with a rubber squeegee. The squeegee must have good elasticity, solvent resistance and wear resistance. The shape of the squeegee includes right angle, rounded angle, bevel, etc. The smaller the angle between the squeegee and the screen plate, the slower the squeegee speed, and the greater the amount of ink on the printed matter. When printing, select the shape of the squeegee according to the material of the substrate, and adjust the angle of the squeegee according to the required thickness of the ink layer.

For screen printing, the ink layer is thick and the ink dries slowly. You need to use a drying rack to dry it, dry it with a rotary mobile dryer, or use infrared or ultraviolet ink printing and dry it with an infrared or ultraviolet dryer. Some screen printing products require special treatment after the ink is solidified on the printed matter. For example, a glass cup printed with hot-melt glass ink needs to be placed in a 400°C sintering furnace for printing and sintering.

Printing faults

Faults in screen printing are generally caused by printing plates, scrapers, inks, etc.

(1) Poor inking of the printed matter

On the printed matter, the ink color is light and uneven. The elimination methods are: replace the ink that matches the substrate and has good adhesion performance. Add additives that slow down ink drying to reduce the drying speed of ink. Increase scraper pressure.

(2) Ink-rich

The phenomenon of uneven printing layers and dead dots. The elimination methods include: adding original ink and increasing the concentration of ink. Increase printing speed. In addition to reducing the scraping pressure. Reduce the amount of ink supply to the printing plate and appropriately increase the angle between the scraper and the printing plate.

(3) Show-through

The back of the printed matter has ink or solvent-expanded stains on it. The elimination methods are: replace the ink printing with small penetration and reduce the squeegee pressure.

(4) The printed products stick to each other without drying for a long time

The elimination method is: use quick-drying diluent to increase the dryness of the ink.

(5) Screen blocking

The ink blocks the mesh of the screen printing plate and the ink does not flow. The elimination methods include: adding slow-drying thinner to reduce the drying speed of the ink. Use the specified solvent to appropriately reduce the viscosity of the ink.

(6) The printing plate is degummed and leaking ink

A large area of ??ink stain appears in the blank part of the printed product. The troubleshooting methods are: use photosensitive adhesive plate that is resistant to ink corrosion. Use a soft rubber scraper for scraping. When the degumming is very serious, the plate needs to be remade.

Device, check and maintain frequently to avoid fire.

And Special Print-ing Press.