Correct selection of silk
the materials used for weaving silk include cotton yarn, real silk, nylon, polyester, stainless steel wire, copper wire and other metals. When making silk screen printing plates, we should have a comprehensive understanding of silk materials in order to lay a good foundation for the correct selection and production of high-quality printing plates
1. Characteristics of silk material
cotton yarn: due to its poor uniformity of warp and weft, the hole sizes are inconsistent and the shapes are different; The surface smoothness of cotton yarn is also poor, the tensile resistance is very low, and the pressure resistance is also very low; The printing plate made of cotton yarn is of poor quality, poor image resolution and poor printing resistance, so it has been rarely used
real silk: its uniformity, tensile strength and surface finish of warp and weft are higher than those of cotton yarn. The disadvantages are that the elongation is too large, it is easy to age and deteriorate, the light resistance effect is not good, and it is very fragile after long-term exposure to light
nylon yarn: it is woven by a kind of synthetic fiber - polyamine fiber. There are many strands and monofilament in knitting. The thickness of warp and weft can be processed according to different requirements. The area density of the eye is uniform, the wear resistance is good, and the elongation is lower than that of real silk. At the same time, the electrostatic charge of the printing plate made of nylon silk is small. The disadvantage is that the acid resistance is slightly poor
poly (vinyl acetate): also known as polyester yarn, it is also woven by a kind of synthetic fiber. The thickness of warp and weft can also be made according to requirements, and the eye area and density are relatively uniform. Its chemical resistance is stronger than that of nylon yarn, and its elongation is lower than that of nylon yarn. The disadvantage is that static electricity is generated during printing, and the water content is worse than that of nylon wire
metal wire: refers to the wire woven with stainless steel wire and steel wire, and also the wire made of electroplated metal nickel. It is characterized by high strength, good wear resistance, excellent chemical resistance, and high surface finish. In addition, the electrical performance of the tensile testing machine is particularly good when testing, and it is very easy to heat when printing. It is very suitable for silk screen printing inks or slurries that need heating. The disadvantage of metal wire is that it has little elasticity. If the wire has creases, it cannot restore its elasticity and can only be scrapped
in current silk printing, nylon wire is usually used as the substrate of printing plate, but polyester wire and metal wire are also often used as the substrate of printing plate when making very precise image printing plate
second, the weaving of silk materials
there are many varieties of silk in the market, and there are many differences in the form of weaving, but in terms of the main forms of weaving, there are the following
corrugated braiding: it is the most popular form of braiding, which has good tensile strength and uniformity. The disadvantage is that the weft thread is easy to shift after the wire is under the pressure of the ink scraper, causing the image to elongate. Due to the unstable structure of this kind of woven silk, the printing volume of the product is not easy to be too large, and too large printing number will cause great errors in the front and back prints
braiding: the printing resistance of this braided form of silk is greatly improved, which can ensure the accuracy of the image and better avoid the weft movement caused by the pressure of the ink scraper. The thickness of braided silk increases significantly, and the thickness of the ink layer after printing will also increase
semi braided braiding: This braiding form combines the advantages of corrugated braiding and braided braiding. This kind of silk is very suitable for printing products with large print volume but low image precision requirements
III. specification of silk
the specification of silk is generally represented by "a wide range of medical grade particle product lines of polyvinyl chloride (PVC) and thermoplastic elastomer (TPE)". It refers to the number of holes contained in the length of each inch of wire
in the length of each inch of wire, the more the number of holes, the smaller the aperture of the same hole. For example, 120 mesh refers to 120 holes in a one inch length of wire; 250 mesh refers to 250 holes in a one inch length of wire. And so on
if the number of holes in each inch of wire is less than 180, the human eye can distinguish it. If it is more than 180, it is not easy for the human eye to see the holes
silk is also represented by "model" in the market. For example, silk sp56 represents 150 mesh single yarn, and silk xx15 represents 50 mesh double yarn.
the corresponding relationship between "mesh" and "model" of commonly used silk is listed as follows:
silk single yarn (SP)
38 =102 mesh 40 =107 mesh 42 =112 mesh
45 =121 mesh 48 =129 mesh 50 =134 mesh
52 =139 mesh 54 =144 mesh 56 =150 mesh
58 =156 mesh
silk double yarn( ××)
6 =74 mesh 7 =82 mesh 8 =90 mesh
9 =97 mesh 10 =109 mesh 11 =116 mesh
12 =125 mesh 13 =129 mesh 14 =139 mesh
15 =150 mesh 16 =160 mesh
nylon wire
109 =109 mesh 125 =125 mesh 150 mesh
175 =175 mesh 200 =200 mesh 225 mesh
250 =250 mesh 270 =270 mesh 300 =300 mesh
330 =330 mesh 350 =350 mesh 380 =380 mesh
polyester monofilament
120 No. =47 mesh 135 No. =53 mesh 150 No. =59 mesh
175 No. =69 mesh 220 No. =79 mesh 225 No. =90 mesh
250 No. =100 mesh 270 No. =110 mesh 300 No. =120 mesh
330 No. =130 mesh 350 No. =140 mesh
during the printing process, the printing plate made of 160 mesh nylon silk often has poor adhesion between the photosensitive film and the silk, and the printing lines are easy to thicken and have burrs, When scraping the printing with the doctor blade, it is also a problem that car companies use it laboriously when they can't use it; 250 mesh nylon 5 is used. The security inspection machine must have a good grounding wire to make the printing plate, which can improve the printing accuracy, save labor and reduce the burr when the ink scraper is used for printing; For the printing plate made of 360 mesh nylon wire, the photosensitive adhesive film and wire are firmly bonded, the scraping force of the ink scraper is saved, the printing accuracy is significantly improved, the lines and text edges are neat, and the lines and spacing can reach 0.2 ~ 0.15mm. For halftone four-color printing products, 80 mesh, 100 mesh and 130 mesh silk are often used to make plates, which can meet the printing requirements
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