As a printing with a wide application range, screen printing can be divided into fabric printing, plastic printing, metal printing, ceramic printing, glass printing, electronic product printing, lottery screen printing, electric decorative advertising board screen printing, metal advertising board screen printing, stainless steel product screen printing, light reflector screen printing, and so on. Fabric printing
Fabric printing refers to the process of forming patterns on fabrics by printing. Printing methods include stencil printing, screen printing, rotary screen printing, transfer printing and multi-color shower printing, among which screen printing originated from stencil printing (including stencil printing and zinc printing), and 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. Pigment direct printing is to directly print the prepared printing paste on the fabric, which is the simplest and commonly used process in the printing process. Pigment direct printing technology generally refers to printing on white or light-colored fabrics, which is convenient for color matching and simple in process, and can be baked after printing, and is suitable for textiles of various fibers. The direct printing process of paint can be divided into Akramine F adhesive according to the adhesives often used at present. Three direct printing processes: acrylate adhesive, styrene-butadiene emulsion and chitin adhesive.
2. The main methods of silk 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 penetration printing method will be introduced separately in the following sections. Here, the dye-proof printing method is mainly introduced.
3. The printing of knitted underwear mainly uses the direct printing process of paint, and the fabric can be printed by double drying or natural drying, which avoids the problems of easy deformation of knitted fabrics and difficulty in wet processing of agricultural sheets. 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 with various forms and structures, and is suitable for the production needs of small batches and multiple colors.
4. discharge printing discharge printing, also known as engraving, refers to the printing method of printing on colored fabrics with discharge agent to destroy some dyed pigments, thus obtaining various patterns and patterns. Discharge agent is a chemical that can make the dyeing base fade. Such as: hanging white, stannous chloride, etc. This method can be divided into two types: white pattern (white drawing) and colored pattern (printing). The latter dyeing method makes the fabric pattern fine, but the process is complicated and the cost is high.
5. The silk-screen burnt-out burnt-out system uses two kinds of fiber blended fabrics with different acid resistance. After acid burnt-out pulp printing and chemical processing, the non-acid-resistant natural fibers are rotted away, and the acid-resistant chemical fibers are exposed, forming a crystal-clear flower pattern. Its special style makes the burnt-out products have a high-grade and gorgeous feeling. Burnt-out products are not only gorgeous in appearance, excellent in internal quality, but also have the properties of wear resistance, high strength, easy washing, quick drying and non-ironing, which are welcomed by domestic and foreign markets. The research and application of burnt-out technology has prevailed in textile printing and dyeing industry in recent years.
6. Wool fabric printing At present, printed wool fabrics are mainly thin plain fabrics or tulle fabrics, which are mostly used to make women's shirts, dresses, quilts and skirts. In addition to direct printing, wool fabric printing also includes pull printing, resist printing and transfer printing. Wool blended fabric printing also accounts for a certain proportion. At present, the relief finishing of wool fabric is also quite popular, mainly used for woolen sweaters.
7. velveteen 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 under sunlight.
8. There are many kinds of special printing for foam printed fabrics, and foam printing is one of them. Foam printing is characterized by strong three-dimensional sense, similar to manual embroidery, soft hand feeling, wear resistance, washing resistance, good fastness and elasticity, and can be widely used in tablecloths, curtains, tea towels, handkerchiefs, pillow towels, clothing, tourist souvenirs and so on. It can be applied not only to cotton, hemp, silk and other natural fiber fabrics, but also to rayon fabric.
9. flocking printing electrostatic flocking is a new technology emerging in the textile industry. 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 for 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 costumes will make them unique.
1. 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 deformation of paper is small, so it can print fine multi-level patterns and photographic pictures. Transfer the pattern picture to the cloth truly. Its effect is sometimes better than general resist and discharge printing.
in addition to the above ten common printing methods, there are some special printing methods, such as anodized transfer printing, photoluminescence printing, fluorescent printing, gold and silver powder printing, pigment foam printing, color-changing printing, fragrance printing, diamond printing and pearlescent printing, etc.
plastic screen printing
screen printing of plastic parts is one of the secondary machining (or reprocessing) of plastic products. The so-called secondary processing is to carry out a decorative treatment on the surface of plastic products after injection molding, such as plastic electroplating, plastic spraying, plastic hot stamping, plastic screen printing and so on. The secondary processing of plastic products is mainly determined by the properties of plastic itself, such as its single dyeability and poor light fastness. In order to make up for these shortcomings and improve the appearance decoration of plastic products, secondary processing is needed.
There are many kinds of plastic products, but as far as silk screen printing method is concerned, flat screen printing method is used for sheets and flat bodies; The curved surface screen printing method is used for the curved surface that can be expanded into a plane; Special-shaped products use indirect screen printing. Different resins, additives and molding methods of plastic products have great differences in their surface properties, especially the problems of surface smoothness, polarity and static electricity, which have become the root causes of plastic screen printing failures.
1. Screen printing of PVC plastic PVC was put into industrial production in 1931. PVC plastic has the advantages of bright color, not easy to break, acid resistance, alkali resistance and low price. However, when making PVC plastics, some auxiliary materials are often toxic, so PVC products are not suitable for holding food. There are many varieties of PVC films, and most of the colorful plastic sheets and artificial leather on the market are PVC products.
2. Screen printing of ABS plastic ABS resin plastic is an engineering plastic. In recent years, it has been widely used in TV sets, calculators and many fields of national economy. ABS plastic is a terpolymer of acrylonitrile, butadiene and styrene. Because ABS plastic is a ternary polymer, it has the same characteristics of three components, and acrylic eye can make the polymer resistant to chemical corrosion and have a certain surface hardness; Butadiene can make polymers have rubber-like toughness; Styrene can make polymers easy to process and shape. ABS plastics have various colors, and the products have glossy appearance, low water absorption, good impact strength and surface hardness in a certain temperature range, and good dimensional stability. Most ABS resins still have considerable impact strength and toughness at-4℃, and their products are used at-4 ~ 6℃. ABS plastics have high molecular weight, good physical properties, easy processing and molding, and good printability.
3. Screen printing of polyethylene and polypropylene plastics: Polyethylene plastics are widely used and can be made into various finished products by extrusion, injection and other molding processes. The molecule of polyethylene is a long chain composed of methylene, which contains a certain amount of side groups. The more and longer the side groups in the polymer chain, the lower the crystallinity of the polymer. That is to say, the higher the density of polyethylene, the more unfavorable it is to surface finishing. Polyethylene is not clear in many solvents, but it can be dissolved in toluene, amyl acetate and other solvents when the temperature exceeds 7℃. This property of polyethylene provides conditions for surface finishing. The adhesive force of ink film on plastic surface can be improved by soaking plastic in heated solvent to swell its surface and destroy some crystals. The mixed solution of fuming sulfuric acid, concentrated nitric acid, chromic acid and sulfuric acid can slowly act on polyethylene at room temperature; At 9~1℃, sulfuric acid and nitric acid can quickly destroy polyethylene; Using the mixed solution of potassium heavy lead acid, sulfuric acid and distilled water to soak polyethylene plastic at 7~75℃ is beneficial to enhance the adhesion of ink film on the plastic surface.
Polypropylene (PP) plastics: Polypropylene is one of the important varieties of plastics development for many years. Suitable for all molding methods. Can be made of various pipes, boxes, films, fibers, etc. Industrial polypropylene has a high degree of spatial regularity, high crystallinity, and the equivalent index is in the range of 89~95%. At the same time, it contains a small amount of amorphous atactic and low crystalline three-dimensional block structure macromolecular chains. The melting point is in the range of 17~175℃, the glass transition temperature of isotactic polymer is-13 ~ ℃, and that of syndiotactic polymer is O℃. Concentrated nitric acid and fuming sulfuric acid can corrode polypropylene, and can be dissolved in aromatic hydrocarbons and chlorinated hydrocarbons at high temperature, but can only expand it at room temperature. Acids and esters also have some corrosion effects on it, and the solvent resistance increases with the increase of isotactic polymer content.
Generally speaking, both polyethylene and polypropylene are nonpolar molecular structures with high crystallinity and low surface tension. There are no polar groups such as carbon, carboxyl and hydroxyl in their molecular structure. Compared with polyethylene, the surface coating of polypropylene is easier.
4. Screen printing of plastic parts of electronic products Electronic products, especially radio products such as radios, tape recorders and televisions, require high appearance. Art designers attach great importance to the appearance decoration of products, but there are few techniques for appearance decoration in China at present, which limits the thinking of art designers, so that they can only change the appearance of products through the size of products, the use of various lines and the limited color of plastic itself. After the development of plastic screen printing, it has brought convenience to the decoration of electronic products, so in recent years, plastic screen printing of various electronic products in China has been widely used.
5. Screen printing of plastic signs In recent years, plastic signs and decorative parts that screen print graphics and characters after plastic molding have developed rapidly. For example, screen printing on PVC rigid board, polycarbonate, ABS, plexiglass and modified polystyrene has been widely used and achieved good decorative effect and economic benefits.
6. screen printing of soft and hard plastic parts ① screen printing of plastic hoses. There are several methods for printing plastic hoses, and the main method is thermal transfer printing. Thermal transfer printing method is to use sublimation dye ink or other materials to print pictures and texts on transfer paper, and then attach them to the substrate, and heat them from the back of transfer paper to sublimate the paper dyes and transfer the pictures and texts to the substrate. After surface treatment, the plastic hose was passed between the hose and a heated iron plate by Sun Gas and transfer paper, and the heated iron plate pushed transfer paper to the hose, and the transfer was completed by heating. After transfer, the hose enters the drying device, and the drying temperature is generally about 65℃. ② Screen printing of soft plastics. Soft plastics are mostly used to make toys, such as inflatable cartoon toys. When making, it is usually to screen print patterns on soft sheet plastic first, then cut and thermally synthesize. The thickness of the materials used is generally .8 ~ 3. mm. If screen printing with more than two colors is carried out, most of the plastics will expand and contract, resulting in the misregister between the second color and the first color. This kind of color registration error makes the goods lose their original value and cannot be put on the shelf as qualified products. Therefore, multi-color printing can only use a long printing machine that can fix soft plastics, and there is no other way. When printing on a long platform, the substrate should be fixed with adhesive. It is worth noting that toy printing must use non-toxic and harmless ink specified in relevant standards. ③ Screen printing of hard plastic products. There are two kinds of hard plastic products: hard board and molded products. Tickets, signboards, instrument dials and cosmetic containers are all made of hard plastic.
7. The surface materials of the screen printing panel of the instrument panel may be metal, various plastics and paint, etc. Select appropriate ink and screen print some characters and graphics on the panel to show some functions of the instrument and equipment, and beautify the panel at the same time. Screen-printed words and graphics require clarity, good adhesion and wear resistance, and also require soft and elegant colors to give people a beautiful feeling. Here we mainly discuss how to improve the quality of the panel by silk screen printing process.
8. Screen-printed polyester sign with color polyester sign is a new type of sign that has developed rapidly in China in recent years. Because it has the advantages of bright color, good decoration, convenient pasting, simple manufacturing method and low cost, it is deeply welcomed by the majority of users, and has been widely used in high, medium and low-grade electronic products, household appliances and stationery. At present, many specialized factories in China have produced this kind of sign. However, because the production technology of these factories is designed according to the needs of large-scale label processing, those polyester label products with many varieties and few quantities can not adapt to it in terms of processing technology and production cost. This paper introduces a process technology of printing color polyester signs by screen printing, which can be used as a reference for manufacturers engaged in small batch and multi-variety color polyester signs.
screen printing of metal
Screen printing of metal covers a wide range, and can be used to print all kinds of logo roots, panels, signs and metal molded products. Most of them are decorated by direct printing, and there is not much difference in screen printing skills, except that metal products are durable products, and the surface decoration requirements are higher and more durable. Therefore, before printing, more surface treatments are carried out, such as surface coating, electroplating, anodizing or mechanical roughening (streaking, wire drawing). When printing, make sure the surface is clean, so be sure to wear gloves when working. If there are stains such as grease, fingerprints and dust on the treated surface, it must be washed away with solvents such as trichloroethylene, thinner and gasoline. In addition, according to the surface properties of metals, appropriate printing inks should be selected, such as amino and epoxy thermosetting inks should be used on the coating surface of amino baking varnish and epoxy baking varnish; Solvent volatile ink or oxidation drying ink can be used on naturally drying coatings such as nitro varnish, but solvent or diluent must be used carefully to prevent damage to the paint surface, and a layer of varnish should be applied after printing to improve luster and protect the whole surface; The electroplated surface of metal can also be printed with thermosetting ink, but attention should be paid to the difference of thermal expansion coefficient between the electroplated layer and the metal to control the heating temperature and avoid cracking of the coating due to the great difference of thermal expansion coefficient. Anodic oxidation of aluminum plate will form an oxide layer with uniform gap (about 2~1μm thick), which has a large surface area and can improve the adhesion of coating (ink). In addition, it also has the performance of absorbing dyes, and dyeing signs can be made by diffusion ink or dip dyeing method.
1. silk