1 Introduction
Screen printing plate technology, printing technology is one aspect of the application. Now, after a variety of signs have been added on electronics and home appliance products are widely used, especially in the surface of a variety of signs using a new decoration process, it refined and elegant form, many colorful decorative effect demonstrated in front of people, increase the value and competitiveness of commodities. Signs in the production process, play a decisive role is screen printing plate and substrate pre-treatment technology and screen printing inks and printing elements of choice.
Screen printing plate making
1, the film engraving: the plate is a manual method, relatively simple. Printable generally less sophisticated monochrome patterns and text.
(1) Vintage sprayed paint paper: the tracing paper with glue stick on a flat board, with a row of pens rubber water to 1 part (by volume), good gasoline 1 tone, evenly coated on paper after a soft dry spray varnish 3-5 times, after each spraying in an oven by 40 degrees to 50 degrees drying, spray paint film thickness to 5 to 6 mm is appropriate, the film should be bright, uniform, no bubbles , without blemish.
(2) engraving Graphics: The graphics on the paper attached to the film, with a knife, compass knife, ruler graphic engraving by gently removing the film.
(3) Posted: After carving patterns in the past can be posted well in advance on the screen frame. The method is to cut a good film on the frame below the pressing, with cotton dipped a little thinner on top and gently rub the complex to screen the film and the cement up. After drying for several minutes, the tracing paper torn off. If the paper is not fully out, the available cotton wet wipe. Blank part coated with lacquer, the screen mesh blocked. To dry after printing.
2, carbon paper copy method: also a relatively simple manual plate method.
(1) cut sheet paper: photographic paper is coated with a thick mixture of barium on oxygen who made the original paper, carbon paper, according to the size of the graphic cut a good backup. (2) sensitization: immersed in 500 ml and 20 g of ammonium dichromate prepared solution for 3-5 minutes, remove the carbon paper, the water diversion dry.
(3) Exposure: The carbon paper flat on a clean glass, film upward, positive image in the top cover polyester film negatives with Shai Banji exposure, exposure time 8-12 minutes.
(4) development: after exposure at 40 to 50 degrees warm water soak a few minutes, so that film and positive plates and zinc oxide paper naturally out with warm water to force the developing carefully shaped text is clear.
(5) Posted: good version on the system to be a good stretch mesh screen frame below the screen covered in several layers of newspaper, the pressure on the glass to 1-2 kg / cm of pressure, this when the film and screen firmly affixed, remove the weight and newspapers, dry film with an electric furnace, and then remove the paper, film graphic you go to the wire-line. Carefully check whether the graphic defects, after passing the wire around the graphic medium coated with nitro enamel protection, the silk screen printing plate mounted on the carriage is to prepare for printing. Scope of this same film engraving plate method.
3, the photographic plate method: printing brand precision screen printing plate used in high, generally have adopted advanced direct, indirect, direct between the three photographic plate method. A, CTP method:
(1) post boxes use aluminum frame, you do not need stretching flexibility Stretching, pressure at 5-6 kg / cm, using acetal adhesive net, stretched with tension measurement tightness, tension 5-7 kg, sink size should be less than 2 mm.
(2) Cleaning Screen: Use washing powder, detergent, ethanol and the like as clean lotion, wash both sides of the screen, and rinse with water. After air drying stand. Purpose is to make the network better with photoresist adhesion.
(3) scraping bucket (hopper coating, coater): scraped fighting photoresist coating may be made of stainless steel, it can also be made of plexiglass plate scraper. Its length is generally slightly smaller then the inner diameter of the screen frame (the length of several different scraping bucket dubbed a spare set) B. Must scraping the thin edge of the bucket without edge, straight and smooth, not allowed to have irregularities, burrs, scratches and other defects, heart to affect the quality of the plate. When the light-sensitive adhesive coated wire mesh, each coated with three drying again, the need for a continuous 3-4 times, until the film reaches the desired thickness is reached, then the exposure.
(4) the temperature of the oven, it is preferable to use an adjustable temperature oven. The drying temperature sensitive adhesive, generally controlled at about 40 degrees, the baking time is too long or the temperature is too high, will affect the quality of the photosensitive layer.
(5) security lighting: studio lighting, generally used orange, yellow or red light as security lighting, but visually, the orange-yellow light comfortable. Its brightness to be able to clearly see all the articles is appropriate.
(6) Test negatives: on the bottom plate must be carefully checked before the copy, including the layout of dust, backplanes blackness broken lines missing, sand hole defects and other items of positive and negative images of text to meet the requirements.
B, the indirect method:
(1) Prepare the frame and the photosensitive film: good to stretch the frame (nylon with 220-260 purposes) with a 10% aqueous solution of sodium phosphate cleaning to remove oil. Wire mesh photosensitive film is a film of poly alcohol gel as the main body of photoresist, film is a film on a transparent plastic sheet 0.12-0.06 mm gelatin-based photosensitive agent is applied to the body, then prior to use graphic size, width on each side out of 20 mm, with a cloth to wipe off the powder dirt film.
(2) Exposure: the film within the film and the bottom plate is pressed against the plate, with exposed carbon lamp or a xenon lamp. Distance between the screen frame and the light source is 50-60 cm, exposure time 2-6 minutes.
(3) Development: After exposure, the Philippine film on the plate, with warm water for 1-2 minutes omental infiltration, water spray nozzle with an aqueous to the non-photosensitive portion (graphic section) copy, after the development of the Philippine film, until the shape is clear.
(4) paste film membrane: the film was exposed to the membrane surface attached to wire-line, on the back of people's with a rubber membrane plates or other straight, gently scrape paste, the film is firmly in contact with the net, immediately placed in an oven at a temperature of bake 8-12 minutes under the conditions of 55 ± 2 degrees, after drying, the screen frame is fixed to the plate bench proofing.
(6) to film methods: exposure, development process, when found defective version, the film can be immediately washed off with warm water to re-create. If the version has dried or after a period of time to film production, the available industrial sodium hypochlorite and water each one, soak for 10-20 minutes. Or 5% aqueous sodium hydroxide heated halftone processing, film can be removed.
C, between straight plate method: straight between direct and indirect method is the method of mixing the plate method, which differs from that of the indirect method, the indirect method in the first film after the film do go down to the wire image posted online, and straight France is among the first film after the film posted online exposure wire manufacturing an image.
Pretreatment
Signs up to the amount of printing materials are aluminum, copper, stainless steel, aluminum. There are also plastic, polyester, paper. Aluminium Signs are signs varieties is widely used kind, with a beautiful, bright, high hardness, wear resistance, wide application, dosage and other characteristics. Used in machinery, electronics, instruments, meters, household appliances, hardware, watches, cosmetics and packaging. Pre-treatment of aluminum substrates have a variety of methods, depending on the use, mainly degreasing, sandblasting, wire drawing, polishing, oxygen grease.
1, oil: the surface of an aluminum substrate with a certain affinity Hu ink, the need to remove surface oil and oil, can wipe cotton dipped in gasoline. It can also be used for chemical degreasing alkaline solution, such as sodium sulphate 30-50 g / l, sodium 40-60 g / l, sodium 10-15 g / l, at a temperature of 60-70 degrees immersed 2-5 minutes degreasing.
2, sandblasting: sandblasting to improve the adhesion of the ink and the metal material is generally used sandblasting machine dedicated for discharging treatment, if 0.5-1 mm thick aluminum plate, sandblasting sand of 0.05 to 0.15 mm in diameter, and available river sand, sieve after use.
3, drawing: also known as twist processing is the processing method of the delicate mechanical friction straight lines in the aluminum surface. It was a relatively new decorative surface treatment process, we can overcome the defects such as scratches on the aluminum surface. Improve utilization of materials. There are two thick wire drawing lines to find ways and filaments, usually with a diameter of 0.1 mm stainless steel wire brush or scouring pad brush, nylon belt can also be processed.
4, polishing: to overcome the aluminum material surface defects and improve surface finish. Polishing and chemical mechanical polishing polishing points. It is the use of mechanical polishing cloth polishing wheel machine, multi-chemical polishing is carried out in an acidic solution, such as 15% sulfuric acid, 10% nitric acid, the temperature of 90-100 degrees, time of 2-3 minutes.
5, oxide: aluminum surface polished has a residual soap polishing, wipe application boards yarn dipped in gasoline and chemical degreasing, then immersed in a nitric acid solution (1 to 1 ratio of nitric acid and water), removed after 10 minutes, and then into the oxidation tank electrochemical oxidation. Oxidizing liquid formula: nitrate 160-200 g / ml, temperature of 10-20 degrees, 30 minutes. Good sufficiently washed with water dried aluminum oxide, formed on the surface layer of uniform porosity in the oxide layer, i.e., oxide film, to avoid dirt contamination. Good aluminum oxide immediately print the best, if not immediately printed, soft paper application septum wrapped or dried directly on the shelves, storage time should not exceed one week. The surface of the aluminum oxide layer can absorb dye, water and other salts, it is not something with greasy hands or contact surface when printing. When the ink is printed onto the oxide layer, namely the ink penetrate pores. Heating the next step is to accelerate the ink to penetrate pores until all the pores in the surface of the ink-covered been filled so far. Few printed ink surface diffusion or non-proliferation, to ensure good text, graphics precision and clarity.
6, closed: its role is firmly sealed in the ink within the pores, and never rise overflow or diffusion. No ink coverage to complement the site is closed to fill the role of the oxide film is also the gap, making it impervious to enhance corrosion resistance surface. Generally use nickel sulfate solution for blocking. Recipe: Chinese NICKEL 10-12 ml, temperature 80-90 degrees, 10-15 minutes. Hand or other things and then sealing with oil contact surface with the general cleaning agents can be washed off.
Silk screen printing ink (paint)
In today's metal plate or non-standard version of the silk screen printing ink it can be used more, but the choice of a suitable ink (paint) is not easy. Common signs screen printing inks are the following:
1 baking enamel: is a single liquid-based formulation, when heated cross-linking, preferably storage performance. It can be stored for six months to a year. Have a good finish, wear resistance, chemical and weather resistance, and therefore the most commonly used. Alkyd, acrylate, polyester and having these characteristics. Epoxy resin powder tends to fracture and generally not for outdoor use, but it dries quickly, has good chemical resistance properties. alkyd enamel with physical characteristics, such as chemical resistance and weather resistance, formability, hardness and gloss, is the most widely used.
2, air dried enamels: drunk acid commonly made, starting oxygen in the air, after the reaction to achieve cure. Drunk acid enamels performance from the use of oil type and quantity. The longer the drying time of oil, enamel drying time is long. When the speed of the drying conditions, the drying time is long paint generally have good surface durability. The paint used for outdoor metal plate.
3, melting volatile ink: solvent evaporated to rely on only in order to achieve dry. The final properties of the coating material according to formulation as liquids before performance inherent in a given polymer. Such a thermoplastic polymer containing acrylic acid. In order to play the main part of the screen printing ink is usually often subject to dissolution damage. Some gasoline and alcohol-insoluble acrylic acid, wherein the membrane surface can be in contact with, and thus, a thermoplastic acrylic, vinyl polymers, and other soluble parts of the ink they use based on a plastic substrate.
4, a two-component ink: common epoxy or polyurethane means that although there are many other species. Dual fluid systems are often in the timber is to save energy in the most sensible choice, its high quality of the coating, but mixed inconvenient. Also according to the product's use should be selected, if the product could be used in outdoor, but also note there is some flexibility, so the choice of an aliphatic hydrocarbon as the main urethane ink. Now a two-component epoxy resin ink market is almost the same as baking enamels performance, but not good enough formability.
5, ink additives: Like other inks, by screen printing metal inks may also contain additives, which is produced when the intake of a small amount of chemical agents to improve the performance of the ink film, and some can accelerate the curing or initiating curing, while others can be the bubble burst, uniform quality ink, reducing the possibility of the conjunctiva. Manufacturers pay additives mixed with the ink, depending on the recipe together, printers are required to dilute the ink suitable for printing consistency. Fourth, Printing: screen printing quality, ink layer thickness and the thickness of the screen, the ink viscosity, hard charging, angle blade plate making process are closely related.
1, the wire version and location: aluminum material three-point boundary positioning. When color printing, the first light-colored print, then printed dark.
2, the distance between the plate and the substrate is 1-2 mm from the size of the screen and select relevant, good stretch nylon mesh, stretches, generally 2-3 mm.
3, blade with urethane rubber sheet, a hardness of 70-75 degrees, a thickness of 8-9 mm, a blade angle of 70 degrees is appropriate printing, blade speed should be uniform linear motion.
4, appropriate protective films: label after printing in order to avoid cutting and trauma caused during shipment, to be affixed to the surface of the transparent pressure-sensitive adhesive protective film on the back of double-sided tape to paste.
5, cutting: cutting with a small bed, side molding can be used to locate or positioning hole punching.
2 classification edit screen printing plate
Aluminum oxide color printing plate
Anodized aluminum flat plate is a plate, its application is more extensive. High brightness, high hardness, good wear resistance characteristics. Traditional production process is roughly: mechanical polishing, chemical polishing, oxidation; indirect plate making screen version, plus lithopone paste paint alkyd varnish to protect printing, so both screen production or staining, there are many processes, with Great material, anti-Indian rate, high cost disadvantage. Existing using the latest technology, with no toxic heavy nitrogen type photoresist to plate, so you can quickly reach the plate, high resolution, high resistance to printing, using less material requirements. India will also paint, stain, one step back printed material, the use of self-printed material aqueous dyeing, direct dyeing, successive trapping. This will greatly simplify the whole process and operating procedures, the flat plate has a new oxidative dyeing process.
High-gloss aluminum plate three-dimensional relief
With the production technology continues to improve, people material and spiritual life of the increasingly high demand. It is not only the product features have become increasingly demanding, and the appearance of the product shape, decoration demands higher and higher. Especially with the expanding foreign trade market, in order to improve the market competitiveness of products, high-end products, high-light signs three-dimensional relief has been widely used.
Silk screen electroplating plaque
Plaque plate factory is one of the main products, mainly for corporate signs. Metal plaque material mainly based, it requires serious, highlighting the image, decorative and strong. Traditional metal mainly brass plaque, the corrosion of the word, note black plaque main square. But as people changing aesthetic point of view, the progressive development of the commodity economy, the quality and appearance of plaque shape also with the new requirements. Signs silk screen processing industry to introduce technology, not only promoted the development of printing technology, but also to the sign industry to develop new products and provide technical support. Plated plaque is to label printing and silk screen electroplating process of combining the product under. The basic method of silk screen plating plaque is: the first with copper silk screen graphic art made expressly with the protection of non-graphic part of the ink layer, and then graphic portion of copper, nickel, chrome plating, mechanical final shaping, machining and protection to make.
Conical screen dial
Conical screen dial methods: first with silk screen printed graphic will turn to rubber top, and then the conical part attached to the jig, and then rolled over from the transfer of rubber, so you can print the graphic to the surface of the conical part.
Melamine oxidation signs
Anodic oxidation showed signs of melamine enamel-like surface, soft colors, has good resistance to resistance, high hardness, you wear resistance, heat insulation insulation, etc., it is decorated instrumentation share. Making process will be contaminated exhaust emissions, and therefore the device must be equipped with exhaust ventilation to avoid poisoning. Melamine surface treatment of the signs and silk screen sandblasting paint signs embedded substantially the same, but do not need to enter through the chemical polishing, a direct oxidation. Melamine signs of oxidative dyeing and silk screen signs aluminum oxide colored different.
Silk screen signs aluminum oxide
Alumina signs, panels after oxidation, the surface will be accompanied by an oxide film, the surface is hard and smooth. By conventional screen printing ink adhesion is poor, which is the most important issue. To solve this problem, we must first solve the silk screen printing ink and operational problems. Screen printing inks must be used aluminum oxide, aluminum oxide which is silk screen signs the key to success lies. Such inks and different from the general ink is that it will firmly adhere to the aluminum surface, but also has good lightfastness, this is the best screen printing ink aluminum plate.
Corrosion signs silk screen
Corrosion signs belonging to a traditional signs, a common sandblasting fill paint signs, such as: travel license number equipment, machine tools electrical nameplate; harsh operating environment of mechanical and electrical products plated brass front plate; for instruments, electronic equipment porcelain surface decoration paint sign and oxidation extremely high light signs. Such graphic signs on the past through a liquid photoresist through photochemical effects. This method has produced many processes, low productivity, labor-intensive and other shortcomings. Two using silk screen printing graphic processing technology, greatly improving production efficiency, but also save a lot of raw materials.
Bump color printing aluminum plate
Features punch signs are painted in recess, good abrasion resistance, but also has three-dimensional effect, generally used for mechanical and company nameplate plaque like. The traditional production method is described recess artificial corrosion paint, then use the manual trimming to remove residual paint the edges of this method is not only time-consuming, inefficient and requires very skilled operator, the word and produced signs becomes clear, the quality is not stable. Only suitable for small batch production of some of the less number of color, low-quality requirements of simple signs.
Silk inlay lacquer aluminum plate
Silk screen sandblasting paint signs embedded technology, it is a traditional plate production process. These products look silvery white, high surface hardness, good wear resistance.
White aluminum signs silk screen water
Water white matt aluminum plate is a new sub-surface signs emerged in recent years, China. Such signs milky white appearance, smooth surface, resistant to heat, salt spray, mold-resistant, but also has a very strong light fastness, abrasion resistance, organic-soluble, suitable for machine tools need regular cleaning and working environment machine under relatively harsh conditions. The most important thing is the water white aluminum signs wanton little step, step height, almost no waste generated.