The correct choice of wire mesh is the guarantee of high quality silk screen printing
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
The materials used for the preparation of the screen are cotton yarn, silk, nylon, polyester, stainless steel wire, copper wire and other metals. When making screen printing plates, you should have a comprehensive understanding of the wire mesh materials in order to lay the foundation for the correct selection and production of high quality printing plates.
First, the characteristics of the wire mesh material
Cotton yarn screen: Due to the poor uniformity of warp and weft, the mesh size is inconsistent and the shape is different; the cotton yarn has poor surface smoothness, low tensile strength and low pressure resistance; cotton yarn mesh production The quality of the printing plate is not ideal, the solution is poor, and the printing effect is not satisfactory, so it is rarely used.
Silk wire mesh: its warp and weft uniformity, tensile strength and surface finish are higher than cotton gauze. The disadvantage is that the elongation is too large, it is easy to age and deteriorate, the light resistance is not good, and it is easy to become brittle after long-term exposure to light. .
Nylon mesh: It is woven from a synthetic fiber - polyamine fiber. There are multiple strands and monofilaments on the weave. The thickness of the warp and weft can be processed according to different requirements. The area density of the mesh is relatively uniform, the wear resistance is good, the elongation is lower than that of the silk screen, and the printing plate made of nylon mesh is less static when used. The disadvantage is that the acid resistance is slightly worse.
Polyacetal mesh: Also known as polyester mesh, it is also woven from a synthetic fiber. The thickness of warp and weft threads can also be made according to requirements. The mesh area and density are also relatively uniform. Its chemical resistance is stronger than that of nylon mesh, and its elongation is lower than that of nylon mesh. The disadvantage is that static electricity is produced during printing, and the water content is inferior to nylon mesh.
Wire mesh: refers to a wire mesh woven with stainless steel wire or steel wire, and also a wire mesh made of electroplated metal nickel. It is characterized by high strength, good wear resistance, excellent chemical resistance, high surface finish, and excellent electrical conductivity. It is easy to heat during printing, and is suitable for screen printing inks or pastes that require heating. The disadvantage of the wire mesh is that the elasticity is small, the mesh has a crease and the elasticity cannot be restored, and it can only be disposed of.
In the current screen printing, nylon mesh is generally used as the substrate of the printing plate, but in the production of very precise image plates, polyester mesh and wire mesh are often used as the printing plate substrate.
Second, the weaving of wire mesh materials
There are many kinds of screens on 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 weaving: It is the most popular form of weaving. This kind of weaving form has better tensile strength and uniformity. The disadvantage is that after the screen is subjected to the pressure of the squeegee, the weft is easily displaced, causing the image to stretch. Because of the unstable structure, the mesh of this kind of weaving form is not easy to be printed, and the excessive printing number will cause great errors in the front and back printed products.
Braided weaving: This kind of weaving form of the screen has greatly improved printing durability, can ensure the precision of the image, better avoid the movement of the weft caused by the pressure of the squeegee, and the thickness of the woven fabric of the braid is obviously increased. The thickness of the ink layer will also increase.
Half-tweezer weaving: This type of weave combines the advantages of corrugated weave and braided weave. This kind of screen is suitable for printing with large print volume but low image precision.
Third, the specifications of the wire mesh
The specifications of the wire mesh are generally indicated by "mesh". Refers to the number of meshes contained in the length of each inch of wire mesh.
In the length of each inch of the screen, the larger the number of meshes, the smaller the aperture of the same hole. For example, 120 mesh refers to 120 meshes in a one inch length of wire mesh; 250 mesh refers to 250 meshes in a one inch length wire mesh. So on and so forth.
The number of meshes per inch of wire mesh is less than 180 mesh, which can be distinguished by the human eye. If it is more than 180 mesh, it is not easy for the human eye to see the mesh.
The screen is also represented by the "model" on the market. For example, the true mesh SP56 is indicated as a 150 mesh single yarn mesh, and the true mesh XX15 is represented as a 50 mesh double yarn mesh.
The correspondence between the commonly used screen "mesh" and "model" is as follows:
Silk single yarn mesh (SP)
No. 38 = 102 mesh No. 40 = 107 mesh No. 42 = 1212 mesh
45#=121 mesh 48#=129 mesh 50#=134 mesh
52 = 139 mesh 54 = 144 mesh 56 = 150 mesh
No. 58 = 156 mesh
Silk double yarn mesh (××)
No. 6 = 74 mesh No. 7 = 82 mesh No. 8 = 90 mesh
No. 9 = 97 mesh No. 10 = 109 mesh No. 11 = 116 mesh
No. 12 = 125 mesh No. 13 = 129 mesh No. 14 = 139 mesh
No. 15 = 150 mesh No. 16 = 160 mesh
Nylon mesh
109 = 109 mesh 125 = 125 mesh 150 = 150 mesh
175 = 175 mesh 200 = 200 mesh 225 = 225 mesh
250 = 250 mesh 270 = 270 mesh 300 = 300 mesh
330 = 330 mesh 350 = 350 mesh 380 = 380 mesh
Polyester monofilament
120#=47 mesh 135#=53 mesh 150#=59 mesh
175 = 69 mesh 220 = 79 mesh 225 = 90 mesh
250#=100 mesh 270#=110 mesh 300#=120 mesh
330 = 130 mesh 350 = 140 mesh
In the printing process, the printing plate made of 160 mesh nylon mesh often shows that the bonding of the photosensitive film and the screen is not good enough, the printed lines are easy to be thick and burr, and the squeegee is also laborious. The printing plate made of 250 mesh nylon mesh can improve the printing precision, save labor and burr when the squeegee is printed, and the printing plate made of 360 mesh nylon mesh, the photosensitive film and the wire mesh are firmly bonded. Squeegee scraping labor saving, printing precision is obviously improved, lines and text edges are neat, and the lines and spacing can reach 0.2~0.15mm. Half-tone four-color printing products, often use 80 mesh, 100 mesh, 130 mesh screen to plate to meet the printing requirements.
Fourth, the quality assurance of wire mesh materials
As a substrate for screen printing, the quality of the screen should pay attention to the following aspects:
The screen has a certain strength and wear resistance, to ensure good stretch and printing requirements, and to meet the recycling and reuse of printing and screen printing of large quantities of products.
The screen requires smooth mesh, uniform mesh size, squareness, density, low elongation, low shrinkage, avoiding mesh deformation or mesh clogging, and facilitating the production of printing plates and the implementation of printing operations.
The screen should have chemical resistance, strong acid resistance, alkali resistance and aging resistance. It should be reduced to a minimum by various solvents, inks and pastes. The image can be saved without scrapping the plate due to long-term storage.
The screen should have a certain resilience, and the resilience should not be too large or too small. When the size is too large, the printing may easily cause the edges of the image to be unclear; Reasonable flexibility should be determined by various factors such as the size of the image, the distance between the frame and the substrate during printing, and the station scheduling of the ink and slurry.
Fifth, the choice of wire mesh materials in plate making
It should be considered carefully and carefully before using the screen as a printing plate. Whether the choice of screen is suitable or not is the key to the quality of plate making and product printing. How to choose the screen for making plates, combined with the experience of our factory, from the following aspects.
According to the design requirements of the original, the image size, and the thickness of the line, a mesh of different mesh numbers is selected. The design requirements are high, the image is small, the text is small, the lines are thin, and the finest line width is about 0.2 mm. The screen can be made with the mesh of 250 mesh and above; otherwise the design requirements are not high, the image is large, the line is wide, the most A screen with a fine line width of 0.3 mm or more can be made of a mesh of 200 mesh or less. It should be noted that the mesh mesh is lower than 180 mesh, and the printed edges of the printed plates are more pronounced.
Screens of different mesh sizes are selected according to the thickness of the ink layer of the product. The more mesh mesh, the smaller the mesh diameter, the less the ink or slurry throughput, and the thinner the ink layer on the printed product. The mesh mesh is small and the mesh diameter is large. The ink or slurry has a large amount of ink, and the ink layer deposited on the printed product is correspondingly thickened.
According to the thickness of the ink or slurry and the size of the pigment particles, the screen is made of different meshes, and the mesh size of the printing plate should be less than one-half of the pigment particles to ensure that one mesh can pass two. The above pigment particles, in order to ensure good printing results.
The screen printing plate produced requires strong acid resistance. For inks and pastes that need to be heated to be printed, the screen should be made of wire mesh to make the printing plate. The printing plate made of wire mesh can be energized. Warming reduces the viscosity of the ink or paste and facilitates printing. At the same time, the metal mesh is resistant to acid and is convenient for washing and recycling.
True mesh, nylon mesh, and polyester mesh are available in white and yellow. When the direct plate is used for exposure, the white screen easily causes diffraction of light, which causes errors in the produced printing plate and the negative film (the photosensitive portion of the printing plate is larger than the negative film), and the edge portion of the image is imaginary. White screen wood should be made with high-precision printing plates. It is best to choose yellow screen for high-precision printing plates to reduce the diffraction phenomenon during exposure time. The error of printing plates and negative films can be limited to the minimum range. The quality of the printing plate is ensured, thereby avoiding the problem that the light is caused by the reflection caused by the reflection on the white screen, and the image is distorted and the edges are not aligned.
Six, the advantages and disadvantages of various types of wire mesh and the use of results
Name Mesh/inch Precision Printing resistance Drug resistance Economy Use ratio
Polyester screen 70-380 General Good Good Good 80%
Nylon mesh 70-400 Poor Good Average Good 16%
Wire mesh 80-500 Good Good Good Average 3%
Silk screen 70-200 General General Difference Difference 1%
In short, the screen is the substrate for making screen printing plates, and the screen has a very important influence on the quality of the printing plate. In order to produce an ideal printing plate, before the production of the screen printing plate, the performance and variables of the screen must be clarified and carefully selected. The screen printing plate thus produced can achieve the desired effect.