Screen printing methods and requirements for special products
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First, the lottery screen printing
In the past 10 years, the need to mask ink has increased year by year. The offset printing ink is used to print the thick film on the offset printing text, numbers and symbols, so that it is completely shielded, and then the card is a lottery ticket. There are various forms of lottery tickets, such as sports lottery tickets and social welfare fundraising lottery tickets. This lottery ticket, with the coin or nail scraping off the shaded ink, you can see the text, numbers, etc. printed below. In addition, by masking images, text and numbers can be combined into a variety of interesting entertainments that are very popular.
1. The composition of the lottery, because most lottery tickets are disposable, so paper printing, generally 150 ~ 200g / m 2 Paint paper. First, printing characters, numbers, images, and the like by offset printing, the printing surface of the offset printing is flat, which is advantageous for the final masking screen printing. The printing surface after offset printing must be applied with a good transparency outer layer, which not only makes the masking ink have releasability, but also makes the offset graphic stable. The final silkscreen is then applied to the coating using masking ink, which is typically only partially masked thick film printing on text and numbers.
2. Lottery performance requirements. 1 After the masking ink with stability is printed on the lottery ticket, it should be easier to strip with nails or coins. Such ink-printed lottery tickets, as commodities, must remain stable for at least one year of circulation. 2 After the masking ink is peeled off, the exposed characters, numbers, etc. cannot be contaminated by the ink. 3 masking ink should have sufficient shielding. 4 The ink film that shields the ink must have a certain degree of toughness. That is, in the operation of drying, cutting, etc. of the lottery, the surface of the ink film cannot be damaged by some external force, and the same requirements are also met as a product in circulation.
From the above points, 3 and 4 are almost determined by the performance of the masking ink, so it is very important to select a suitable ink. 1 and 2 are determined by the degree of adhesion between the coated paper and the masking ink. The faults in previous experiments were mainly 1 and 2, so this is a very critical issue.
Second, the silk screen of the electric decorative board
Electric decorative billboards generally project light from the inside of the advertising panel to make the surface more beautiful. The materials used are mainly acrylic plates and glass plates. In addition to printing, the board is decorated with cut-out text and lines. The main processes of screen printing electric decorative advertising board are surface printing, inside printing, full shading printing and so on.
The most common use is the electric decorative advertising board printed on the inside, generally screen printing on the inside of the acrylic board, and finally the white solid printing, the surface can be formed into a glossy decorative pattern. If the light inside disappears and light from other directions is reflected on the surface, various colors will appear.
In the case of surface printing, a milky white translucent plate is generally used, and since uneven printing is not required, unevenness of quality is rarely caused, but scratching is likely to occur due to surface printing.
When shading, it can be printed in two ways. If the surface wants to use full red shading, before printing all red, the same plate can be used for shading, printing a silver or gray, and then printing all red on it. When the electric decoration is performed, only the text or the pattern is partially protruded, which is very clear and beautiful, so it is often used for the printing of road signs or guide plates.
When printing with acryl, since the material itself is electrically charged and it is easy to adhere to dust, it is very important.
Since dust is attached to the electric panel, it is very obvious, so in order to eliminate dust and prevent static electricity, the substrate is rubbed with alcohol before printing. Because the light is emitted from the inside, the printed scraper marks are also very noticeable. To this end, the scraper grinding, printing pressure, printing speed, etc. are very careful, and should minimize printing unevenness. Since the ink having good light transmittance is used, the color tone gives a feeling that a completely different change occurs after printing and electric decoration. When combined with other colors, if light transmission observation is not performed, it is possible to produce a product different from the customer's request. In the four-color color printing, if the color is not observed by light transmission, a very light and blurred image may be formed.
Third, the silk screen of the metal advertising board
The metal advertising board refers to the guide board and billboard of the metal board, and its predecessor is the billboard, the melamine billboard, and the like. The metal material is mainly made of aluminum and stainless steel. The stainless steel surface has the advantage of not rusting, and after screen printing, the surface can be coated with a hardener for processing. Aluminum can be embossed by pressure method using its plasticity, and has a concave-convex pattern on its surface to enhance the three-dimensional effect and enhance the visual effect.
Metallic billboards were the first to have enamel billboards. They were made of galvanized iron sheets and used enamel to prevent rust. They were mostly used for billboards and place names. Although this brand is adaptable to the climate, but the processing time is too small, coloring is not easy. With the development of spray technology, melamine billboards have begun to appear, improving the rust-proof performance, and can be colored by screen-cutting silk screen printing. Since the billboards began to use hard plastic as the main material, the melamine advertising board gives a feeling of being outdated. Iron plate billboards are obsolete, and their processing is affected by their own weight, which is also difficult in terms of commodity circulation.
The main materials of the metal advertising board have been transformed into aluminum sheets or thin zinc sheets, which are lightweight materials and have good processability, and are easy to handle even if they are large in size. In order to increase the strength of the metal sheet, a part thereof may be convex as a rib, and the amount of the material is substantially the same as that of the flat plate.
Fourth, the silk screen of stainless steel products
There are many methods for processing on the surface of stainless steel, which can be roughly divided into two types, one is to treat the stainless steel by surface treatment, and the artistic processing of forming the pattern by using the gloss contrast; the other is to impart color in the composition of the pattern. Art processing. Typical examples in which the screen printing method is used are etching processing and ink color processing.
The etching process is to screen the acid-resistant protective film on the surface of the stainless steel, and then etch it with a ferrous chloride solution to form an artistic pattern. The spray color method is to spray the color particles after screen printing to form a pear-like surface to form an artistic pattern.
In recent years, in order to adapt to the diversification of stainless steel use and higher and higher artistic requirements, the development of color-colored "color art" processing method has become the mainstream in this field. Among the methods of imparting color to stainless steel, a method of performing firing using screen printing of a color ink and a chemical coloring method are included.
The chemical coloring art processing method of stainless steel products is: stainless steel products → silk screen → oxidation coloring → alkali treatment → finished product.
The process of etching the art of stainless steel products is: stainless steel products → silk screen → etching → alkali treatment → oxidation coloring → finished product.
The process of the color art processing method of stainless steel products is: stainless steel products → silk screen → etching → alkali treatment → silk screen → oxidation coloring → alkali treatment → finished product.
The chemical coloring method of stainless steel, instead of using pigments and dyes, is to immerse the stainless steel in a heated concentrated chromium sulfate solution for chemical coloration, which is characterized by good food resistance. The ink used in this processing method requires a very strong acid resistance, and generally uses a UV-curable ink having a special property compatible with the treatment process.
Five, silk screen of light reflector
The light reflector is a silk screen printed by the headlights of the automobile or other light, and the object to be irradiated is reflected by the light source in the direction of the light source without being affected by the angle of illumination or the weather. Reflected by the hollow glass particles having a diameter of about 40 μm, the other cores have a reflective layer. Its film-like support has an adhesive layer and a release layer on its surface. Generally, a reflective layer is provided on the acryl resin plate, and the reflective layer is formed by adding a certain amount of hollow glass particles with a resin having high transparency and printing by screen printing. When printing, carefully select the mesh number, the hole width (opening) and the type of hollow glass particles, and the hollow glass particles are regularly arranged.
This type of printing is used for various signs and commercials, etc., so that it can be confirmed in darker places. In addition, printing for road signs, airway signs, life-saving appliances, security helmets, etc. can also be considered.
Six, Transfer the anodized aluminum with a screen plate
Gorgeous and beautiful, brightly colored anodized aluminum is stamped on the stamping machine and displayed on the substrate. Its beautiful color has won wide appreciation. However, sometimes the bronzing machine will encounter products that are not suitable for mechanical bronzing, and the customer stubbornly does not use screen printing gold. In the dilemma, the unique screen printing transfer of aluminum is showing its superiority. The hot stamping machine is mainly based on temperature and pressure, while the screen transfer of electrochemical aluminum relies on the role of adhesive. The reason why the adhesive can transfer the anodized aluminum is because the outermost layer of the electrochemical aluminum is composed of a rubber layer.
In the electro-aluminum transfer operation, the printed image is first made into a screen version, and the graphic on the plate is required to be clear. Then use a screen plate to print a layer of adhesive on the substrate, then attach the anodized aluminum to it, then use cotton or sponge to gently press on the image, dry, and tear off the anodized aluminum. Dry, tearing is fast), and the parts with adhesives show clear and bright anodized aluminum graphics.
Adhesive formulations are the key to transfer. The formula should be formulated separately according to the nature of the substrate and the nature of the electrochemical aluminum layer and the adaptability of the screen plate. The viscosity and concentration of the formula should be properly formulated. For example, in the case of transfer cloths and polyvinyl chloride, polystyrene plastic products and wood products, the adhesive formula is:
Perchloroethylene resin 100g
Xylene 50ml
Cyclohexanone 350ml
Perchloroethylene resins can also be used in place of or in combination with polyvinyl chloride resins. Polyvinyl chloride resins are used in low molecular weight. When transfering celluloid plastic products, the xylene in the above adhesive formulation can be changed to acetone. When transferring plexiglass products, some chloroform may be added. When transferring metal, ceramics and glass products, the adhesive formula is: epoxy resin 100%. (o) 3% to 5% of dibutyl benzoate and 12% to 15% of ethylenediamine (the concentration is too high to add a diluent).
Seven, silk screen prints
In recent years, silk screen prints have been promoted and popularized in China, and many high-level works have appeared. The art level of silkscreen prints is close to woodblock prints, but the production of silkscreen prints is much simpler than the production of woodblock prints. In addition to the commonly used paper, the screen printing of silk screen printing also includes cloth, plexiglass, wood board, porcelain board, metal board and the like. This broadens the way for the development of silk-screen prints in practical art, such as the use of silk screen prints to produce posters, decorative paintings, clothing, headscarves and so on. The printmaker can fully design and produce practical art, and improve his artistic level. Wall mounts, screens, curtains, sofa covers, cushions, etc. are all areas where silk screen prints can work. It is very meaningful to make pure artistic prints on the one hand, and to develop a position in practical art on the one hand, and to play a role in beautifying people's lives.
Eight, lacquer silk screen
Screen printing has been introduced into the traditional industry, one of which is the lacquer industry. Representative lacquerware such as bowls, drawers and boxes can also be adapted to modern lifestyles. Nowadays, lacquerware products have been developed to meet various purposes. The implementation of a printing method increases the value of the product. Among these decorative methods, the application of more is to screen gold powder and silver powder on the lacquer.
1. Screen printing and lacquer ware gold technology. The lacquer lacquer gold technology is to spray black lacquer and lacquer on the wood and plastic bottom, then paint the pattern on the surface, and then apply gold and silver before the paint is dried and hardened. The class is flat mud gold painting and high mud gold. Painted, lacquered mud gold painted.
The mud gold process, when printed with a screen, is available in both manual and automatic modes, and is generally manual. The first process of the mud gold is to make the design pattern outline into a printing plate. In the screen printing, this process belongs to the plate making, so it is omitted. The following is explained in order.
2. Printing Equipment. For the flat printing equipment of the basin, drawer and box. First place the plate on the table, then place the lacquer ware on the table and position it, and fix the lacquer ware after positioning. When printing in large quantities, there must be positioning and fixing devices (for example, a convex wood type table into which the substrate can be inserted), and the gap between the layout and the printing surface is 1 to 2 mm. The curved surface printing of the cans and bowls is centered on the circular screen plate, the blade is downward, and the substrate is run upwards. When the squeegee, the screen and the substrate are in contact, the rotary force of the screen plate causes the pressure to be printed. The object is rotated and printed.
3. Modulation of printing lacquer. Here is a brief introduction to the paint adjustment method. The paint itself cannot be printed as an ink. The viscosity of the paint is low, and it is easy to mix bubbles, which causes the printed surface to foam, failing to meet the requirements of precise printing. Therefore, in order to achieve a good ink state of the paint, modulation is required. Compared with other coatings, the drying conditions of the paint are completely different, and it is dried by oxidation. Therefore, it is necessary to control the temperature and humidity. Viscosity adjustment of printing varnish: Mixing iron oxide, titanium oxide, protein, anhydrous silicic acid, etc. with lacquer, thoroughly mix thoroughly, sealing for 4 to 5 days, the viscosity can be adjusted to about 500 poise, which can be used for printing. Ink.
4. Paint (ink) drying and mud gold time. The drying of the paint is greatly affected by temperature and humidity. The optimum drying conditions are 30 to 35 ° C and the humidity is 75% to 80%. The mud gold time is proportional to the drying time, and the viscosity of the paint (ink) is larger and the drying is faster.
5. The precision of printing. When the paint (ink) paint is adjusted to be 65% or more or 40% or less, it is not preferable as a printing condition. That is to say, when the paint liquid is used for a long time, the off-plate is poor, and the trace of the paint is left. Especially on the curved surface of the substrate, it can be clearly seen in the direction of printing. In addition, when the paint liquid is small, the flowability of the paint is poor, the printed pattern surface is unstable, and traces of the wire are left, especially when printing gold and silver powder, the mesh is very obvious. The screen making screen generally uses a nylon mesh of 250 to 300 mesh, and the precision is good. Since the paint requires special drying conditions, the phenomenon of plugging the screen is not easy to occur, and the printing workability is good.