The hottest steel barrel screen printing and plate

Steel barrel silk printing and plate making (II)

III. plate making method of steel barrel silk printing plate making is the basis of silk printing. If the plate making quality is not good, it is difficult to print high-quality products. The faults in printing are often related to the improper plate making technology and materials used in plate making. Therefore, in order to make a high-quality silk plate, we must correctly master the plate making technology and strictly select the plate making materials according to the requirements of the plate making process. The problems involved in plate making work mainly include: how to correctly select the materials used in plate making, such as silk, frame, photosensitive materials, etc., and how to master the making, stretching, coating, printing, developing, light source, etc. （1） Silk is the skeleton of the plate and the substrate supporting the photosensitive film. The commonly used wires for steel barrel wire printing include monofilament nylon wire, thin ribbon nylon wire and stainless steel wire. 1. Nylon filament is a kind of nylon monofilament woven fabric, which is treated with heat resistance and dimensional stability after weaving. The plain weave can reach 380 mesh, and the twill weave is more than 330 mesh. Nylon has the following characteristics: ⑴ nylon has a smooth surface and good ink permeability. You can use ink with high viscosity and large particles, so you can get fine printing patterns; (2) the details woven with very fine wires are suitable for painting patterns and dot printing of very fine wires; ⑶ large elasticity, appropriate softness, good adaptability to the steel barrel surface, suitable for steel barrel surface printing; (4) good tensile strength, nodule fastness, elasticity and friction resistance, and long service life; (5) good resistance to acid, chemicals and organic solvents, easy regeneration and use, especially strong resistance to alkali. The following points should be paid attention to when using nylon: ⑴ compared with polyester and silk, nylon filament has a large elongation. In order not to cause printing failure, it is necessary to increase the tension, at this time, the shrinkage force will also become larger, so it is required to use a strong frame and tension machine; (2) due to its low heat resistance, it is difficult to operate if it is fixed on the frame by hot-melt method; ⑶ not resistant to strong acid, phenol, cresol, formic acid and other erosion; (4) poor light resistance, easy to degrade under the action of ultraviolet light, and pay attention to avoid light when storing. 2. Polyester filament polyester filament has the following characteristics: ⑴ it has small elongation and strong elasticity when bearing tension, and single thread is suitable for high-precision printing; ⑵ the tensile strength, structural strength, resilience and printing resistance are all good; (3) it has sufficient drug resistance, especially strong acid resistance and organic solvent resistance, and can be recycled as nylon; (4) low moisture absorption, hardly affected by humidity; (5) the heat resistance is higher than that of nylon, and the influence of ultraviolet light is smaller than that of nylon. The following points should be paid attention to when using polyester yarn: ⑴ compared with nylon yarn, it needs greater tension, stronger frame, stretching machine and firmer bonding method; ⑵ due to the hydrophobicity of polyester, it is difficult to bond with the plate film, so we should pay attention to the cleaning and degreasing before plate making; ⑶ the inking property is worse than that of nylon, and it is not resistant to strong alkali erosion. 3. Stainless steel wire stainless steel wire has the following characteristics: ⑴ excellent plane stability, stable production graphics size, suitable for printing high-precision steel barrel products; ⑵ excellent ink trafficability; ⑶ good alkali resistance and tensile strength, excellent chemical resistance; (4) strong heat resistance, suitable for the printing of hot-melt printing materials. The disadvantages of stainless steel wire are: (1) it is easy to be damaged by external forces; ⑵ sinusoidal vibration test is easy to occur in the printing process; Random vibration experiment; The pressure makes the silk loose, which affects the printing resistance; ⑶ high price and high cost. The thickness of the wire should match the fineness of the pattern on the surface of the steel barrel. Coarse patterns can be coarse with less than 200 mesh, general patterns can be 200~300 mesh silk, and fine patterns should be fine with more than 300 mesh. Among the commonly used silk printing materials such as nylon wire, polyester wire and stainless steel wire, nylon wire has good elasticity, good ink permeability, less static electricity than polyester wire, good wear resistance and moderate cost. It is the preferred wire for general steel barrel printing. However, due to the large elongation of nylon wire, it is not suitable for printing high-precision patterns. If you need multi-color overprint and other silk printing, it is better to choose polyester silk; When printing patterns require particularly high accuracy, stainless steel wire should be used. Due to the major shortcomings of poor elasticity and high price of stainless steel wire, it is generally less used in wire printing of steel barrel. （2） Frame and tension 1. Frame is a frame for supporting wire, which is made of metal, wood or other materials, and is divided into fixed type and adjustable type. The most commonly used frame is made of aluminum profile. The material used to make the frame meets the need of tension. It is firm, durable, light and cheap. When printing on the top plane of the steel barrel, square and rectangular frames are generally used. However, when printing on the circular arc surface of the barrel body, the frame suitable for its shape is generally used. The thickness and shape of the section of the frame material are also different due to the different fixing methods, uses and strengths of the wires. For example, when fixing wires with adhesives, angle materials and angle crutches are generally used; For physical fixation, the slotted driven frame is generally used. In the case of high strength requirements, install stiffeners on the inner side of the pipe for reinforcement, and the pipe used should have a certain thickness. In addition, some special frames are equipped with a stretching mechanism, which can be stretched without a stretching machine. Figure 2 shows the cross-section diagram of various shapes of frames. In order to ensure the requirements of plate making, printing quality and other aspects, you can select the box according to the following conditions. (1) strong tension resistance. As the material of the frame, it should have enough strength to withstand the tension of the wire, because when stretched, the wire will produce a certain tension on the frame. If the strength is not enough, the frame will deflect and deform, so it can't print a good print. (2) prestress treatment shall be carried out. After stretching, the bending deformation of the frame will affect the stability of wire tension. To reduce this effect, the frame can be pretreated. There are two ways to deal with it: first, according to the strength principle of the arch structure, the frame is made into a convex shape, with a deflection of about 4 mm/m, and each internal angle is slightly greater than 90; Or stretch the made metal frame into this shape with special tools, and this pre deformation treatment can resist the influence of wire tension. Another method is to do prestress treatment while doing pneumatic tension, that is, the front end of the puller is tightly against the outside of the frame, and the frame is bent by the jacking force. When it is fixed, although the stress surface of the frame moves from the outside to the top, the stress direction and size are basically the same, so there is no additional bending. Because of these advantages, pneumatic stretching machine has become the most popular stretching equipment at home and abroad. (3) the size is appropriate. Frames of different specifications should be configured in production. When using, determine the appropriate frame according to the size of the printing size, which can reduce waste and facilitate operation. The inside size of the frame should be larger than the graphic part of the printing plate. If the printing plate pattern is a B, the inside size of the frame is 2A 2B, which can be fully printed. The sampling basis of frame size is not only the printing area, but also the needs of the starting and ending parts of the ink scraper and ink return plate during printing; The need to accumulate ink on the plate; The need to ensure that the silk tension at the film part of the printing plate is uniform; The need for the rebound of the screen printing plate in the printing stroke of the ink scraper. 2. Stretching means stretching the wire to the frame, so the "physical examination" of the thermometer is particularly important, both manual and mechanical. Manual stretching is simple and easy, which is a commonly used method, while mechanical stretching has better quality. Pay attention to the tension of the wire whether it is manual tension or mechanical tension. If the tension of the wire is too large or too small, it is not good. If it is too small, the wire is easy to relax (stainless steel wire will also relax prematurely); If it is too large, the silk is easy to crack. In the actual stretching operation, the stretching tension can be determined by experience. While tightening the wire, press the wire with your fingers until the wire feels elastic. Common stretching methods are: (1) manual stretching? The operation steps of manual stretching are as follows: ① cut a piece of silk larger than the size of the outer frame. Generally, the length and width of the silk are 40~60mm larger than the size of the outer frame. ② Soak the silk in water. ③ Put the silk on the frame. Generally, the warp (weft) line of the silk is parallel (vertical) to the frame, but when it is used for high printing precision or hierarchical printing, the warp (weft) line is at an angle to the frame, which is generally 20 ~ 45. ④ Put the moulding a on, nail the frame a, and then pull the wire in the direction of E (see Figure 3). Then nail all the fillets A and fix the AB side. ⑤ Tighten the wire in the direction of F, place the strip C, and then nail the C end. Then tighten the wire in the direction of G while nailing the strip C to fix the CD edge. ⑥ Using the same method, nail the fillets B and D, fix the BC and ad edges, and the stretching operation is completed. (2) instrument tension? Instrument tension is also called self tension. This kind of stretching method mostly adopts relatively simple instruments to assist manual stretching, and its frame is called self stretching frame. This kind of frame is mostly made of metal, and its outstanding feature is that it can be pulled at any time. After the plate is loosened, it does not need to be replaced, and it can be used after being tensioned again. In recent years, roll self stretching has been successfully used in precision printing, and the market has expanded rapidly. Among them, the roll frame has the best performance. It is composed of four aluminum tubes. There is a simple buckle device in the tube to clamp the wire. The two ends of each frame tube can be screwed with a wrench to complete the stretching. (3) mechanical tension? The mechanical stretching machine is used in the mechanical stretching machine. Mechanical stretching machines include screw type, lead screw type and gear strip type. Large stretching machines are generally mobile, while medium and small stretching machines are mainly manual. The biggest feature of the manual mechanical stretching machine is that it does not need electricity and gas source, and its stretching quality is significantly higher than that of the manual stretching, which is close to the pneumatic stretching quality. (4) pneumatic tension? The pneumatic stretching machine uses compressed air as the air source to drive multiple cylinder pistons, synchronously push the clamp to make relative contraction movement in the vertical and horizontal directions, and produce uniform tension on the wire. Generally, the tension pressure of nylon wire can be controlled at 0.8~1.0mpa; The tension pressure of polyester fiber can be controlled at 0.8~1.0mpa; The tension pressure of stainless steel wire can be controlled at 1.0~1.3mpa. When using pneumatic stretching method, first place the frame on the stretching table, and then place the wire horizontally close to the frame. After that, fix the wire around. The development of metal air battery industry still faces many technical bottlenecks in the chuck. Tighten according to the required tension, and then apply adhesive on the contact surface between the frame and the wire. This method can obtain uniform tension. 3. There are two methods to fix the wire on the frame, namely, clamping method and bonding method. (1) clamping method? The clamping method is to clamp the wire between two objects and fix it with friction. The wire of this fixation method is not easy to loose, but the tension is not easy to control, and it is often stretched manually. ⑵ bonding method? The bonding method is to fix the wire with adhesive. The wire tension of this fixation method is easy to control, but after a period of time, the wire will loosen. Following the establishment of the new Darmstadt production base two years ago, the following types of adhesives are commonly used. ① Photosensitive adhesive the formula of photosensitive adhesive is as follows: 300ml epoxy phenolic methacrylic resin; Sabbath butyl ether 10~12ml; Anhydrous ethanol 150ml. Usage: apply the adhesive to the bonding surface of the frame, make the tight wire close to the bonding surface, and stick the wire to the frame