How to choose net and stretch net for wire mesh version of steel drum
Liu Ying
Domestic steel drum manufacturers are no strangers to screen printing. As the contents of steel drums change, the content of steel drum surface printing is also changing. Therefore, the demand for screen printing is also increasing. The content is closely related to the content of the contents, and the requirements of each bucket customer are ever-changing. The steel drum manufacturers also start to make their own screen version. The following are the selections of the screen and the points to be noted when stretching the screen. Talk about your own experience.
First, the wire mesh is the skeleton of the silk screen plate, which is the basis for supporting the photosensitive glue. The basic requirements for the wire mesh in the plate making process are: 1 to have sufficient strength, good wear resistance and elasticity; 2 and photosensitive glue Or the photosensitive film is firmly bonded; 3 the moisture absorption is small; 4 the ink is transparent; 5 is not sensitive to the temperature change; 6 is compatible with various properties of the ink and the diluent.
Wire mesh material
Commonly used wire mesh materials are nylon and wire mesh: 1 nylon mesh is woven from synthetic fiber, has good resilience, good ink repellency, good wear resistance and tensile strength, and low static electricity when used. The price is not high, therefore, the application is wide, and the disadvantages are that the elongation rate is large, the tensile deformation is large, the size after the stretching is unstable, and it is easy to become brittle under the long-time illumination of the sunlight, and is not suitable for the product with high dimensional accuracy requirements. 2 Wire mesh: good dimensional stability, suitable for printing with high viscosity, good ink repellency, good abrasion resistance and tensile strength, excellent heat resistance and chemical resistance, and shortcomings due to external force Broken and damaged, the price is higher.
The selection of the screen material should be determined according to the accuracy of the size of the silk screen pattern, the type of screen printing ink, the number of screen printing substrates, whether the substrate is flat or curved, etc., when the printing accuracy is required and the printing quantity is not excessive. A nylon mesh with low cost, excellent ink repellency and good abrasion resistance should be selected. If the printing size and precision are high, and the printing quantity is large, and the printing is flat, the metal mesh should be selected.
2. Specifications of the screen
The specification of the wire mesh is generally expressed by the mesh number. The mesh number represents the density of the wire mesh. The higher the mesh number, the denser the wire mesh and the smaller the mesh size. In the same number of wire mesh, due to the woven wire mesh fiber line The thickness of the screen, the strength of the screen, the width, thickness and through-hole ratio of the mesh are also different, so the same number of screens can be divided into several specifications, and the screens of different materials can also have dozens. Variety.
3. Requirements for network selection during plate making
The first is to consider the size of the original pattern, the thickness of the line, the density of the film, whether it is a negative image or a positive image, followed by the performance and PH value of the photosensitive adhesive; the performance of the release agent, the pH value; the performance of the developer, and the PH value; The chemical properties of the ink, the size of the particles, the thickness of the ink, and the like. In the selection of the number of meshes, the mesh number is less than 180 mesh, and the edge of the printed pattern after the plate making has a tooth shape, which is more obvious. Above 180 mesh, the edges of the printed pattern after the plate making are relatively neat, and the shape of the teeth is not obvious. For steel drum printing screen, at least 200 mesh or more should be selected. The higher the mesh mesh number, the lower the mesh through-hole ratio, the smaller the ink passing amount, the thinner the ink layer on the substrate, so in order to obtain the best printing effect, Generally, the mesh hole area should be at least 2 times larger than the total diameter of the pigment in the ink.
Second, the correct stretch net is the most important part of making an ideal silk screen
1. Frame material
The material used to make the frame must have sufficient strength, strong, durable and light. It is obviously changed by temperature and humidity. The commonly used frame materials are wood, aluminum alloy profiles and steel profiles. For the barrels, there is also a kind of roll. The packing tape for the outer packaging, the silk screen mesh frame are mostly wooden, need to be dry, the wooden frame can be nailed, or the splicing method can be used, the four corners are fixed with right angle iron, to strengthen the stability, the wooden frame is After being stretched by the tension of the stretcher, it is easy to be deformed, causing the silk screen to be slack, which causes deviation during overprinting. Therefore, it is suitable for printing of monochrome printing and thick line patterns. Nowadays, aluminum alloy profiles are commonly used, which are light in weight, small in deformation and strong in strength. High, but the cost is high. If the steel drum is not printed much, and it can be manually operated, the steel strip used for the wrap can be used as the net frame. The advantage is that the material is easy to use, the steel strip is elastic, easy to bend, and the surface can be printed. The disadvantage is that the finished plate has large deformation after bending and poor overprinting.
2. Stretching net
The basic requirement of the screen plate for the stretcher is that the tension of the whole mesh surface is uniform, the mesh wires in all directions should be evenly stressed, the mesh wires in the same direction are parallel to each other, and the longitudinal mesh wires are perpendicular to each other.
1The screen should be torn by hand when cutting, do not use scissors;
2 When starting the stretcher, gradually increase the force, so that the screen is slowly flattened and tensioned. After pulling to the highest peak, check whether the latitude and longitude lines are parallel along the edge of the clamp. If there is serious non-parallel, re-grip the net;
3 should control the tension of the stretch net, the tension is large, the net is easy to tear; the tension is small, the printing is fuzzy, the tension applied on the four sides is as consistent as possible, and the stretcher can be tightened on all sides, in order to ensure uniform tension, requirements Tension gauges are used for stretching the net. For example, no tension gauge can be used to estimate the tension and uniformity of the stretcher. Then aging treatment, stand still for 10-15 minutes, so that the tension is further uniform;
4 After measuring the tension and aging treatment, the mesh is adhered to the frame with an adhesive. The glue should be brushed on the plane and the outside of the frame in advance, or it can be fixed by a staple gun. When the frame is attached to the wire mesh, In 15 minutes, the screen can be cut and left with a margin. After the clearing, the stretching process is completed.
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