Screen printing technology

Screen and screen structure

Screen plate is the skeleton of screen, used to attach photosensitive film or photosensitive adhesive basic carrier, for screen printing developers, the basic knowledge of screen, according to the requirements of printing, select the appropriate screen materials and models, is an important condition for the production of high-quality products.

There are silk screen, nylon (nylon) screen, polyester (polyester) screen, stainless steel screen screen is often used in screen printing screen materials, the following is some important parameters about the screen.(1) Mesh number, mesh number is a crucial parameter in screen printing, refers to the number of holes per square centimeter (cm’) mesh area.Hole /cm2 or line /cm2 is often used in screen products to express the size of the mesh unit.The tie/inch or line/inch is used to express the density of the screen, usually in some countries and regions where British units are used.Mesh mesh number is generally used to express the density degree between the silk mesh, mesh size is larger, mesh density is denser, pores are smaller.The smaller the mesh, the more sparse the mesh, the larger the hole.If 200 mesh per inch, that is, there are 200 mesh 13° in 1 inch *1 inch area.The denser the mesh, the more difficult it is for the dye to pass through the mesh.The more sparse the mesh, the less difficult it is for the dye to pass through the mesh.Can be based on the accuracy of substrate requirements, the selection of screen materials, choose the appropriate mesh screen.

(2) The thickness of the screen.Refers to the lines and parallel forms through weaving of wire mesh surface and the distance between the bottom surface, generally USES millimeters (mm) or 嶶 m thickness (um) as the unit.Thickness measurement should be screen in the case of no tension static, thickness is generally determined by the screen material, can be passed, & LT;D represents, among which, 8 is the screen thickness and D is the material diameter of the woven screen.Thickness will affect the screen ink, as shown in the figure below, screen materials can be divided into: fine (S), fine (M), thick (T), thick (HD).

(3) Screen opening,

The relation between the mesh width, pore size and mesh size can be expressed by the screen opening parameter.The degree of openness has a great influence on the fineness of the textile screen printing pattern.The actual width of the hole is expressed by the opening, which is generally expressed by the square root of the hole area enclosed by the two lines of warp and weft of the screen (unit: um).Therefore, hole edge length is proportional to the opening, the larger the hole edge length, the larger the screen width will be.Even if the screen has the same opening, due to the use of weaving screen materials and operating methods are not the same, the final product printing effect will be different.

(4) Screen opening rate

Screen opening rate can also be called effective screen area, mesh hole rate, mesh area percentage, etc., that is, to make a certain area of the screen, mesh area in the ratio of the area.

(5) Screen ink

In printing, in the process of actual operation by screen performance, materials, specifications, dyes, pigments, viscosity, and other ingredients, and the pressure of scraper, speed, hardness, Angle, distance (the distance of the network frame and the bedplate) category of substrates to many conditions, such as the amount of dye by silk screen, so don’t have a certain standard.

Calculate ink penetration by using the following formula:

Dye penetration (cm/m’)= screen thickness (cm)× mesh area ratio (opening rate %)×10000cm “/mR

(6) Screen structure

Silk screen can be single, double or more strands (such as silk, etc.) wound.Single strand of silk is convenient for dense weaving, up to 580 mesh/inch, high denier strength, square hole shape, good ink penetration, easy to wash, so it is used more;The knitting density of multi-rubber silk thread is limited, the densest is only 200 mesh/inch, and all kinds of properties are not as good as single gauze.Less usage.But multi – strand wire mesh price is low, so there are two kinds of wire mesh combination system, such as the warp for a single strand wire.Weft is multiply silk.Screen manufacturing process, mainly to weave.Make up as a supplement.Plain weave, twill weave, full twisted weave, half twisted weave are all used in the process of screen weaving, of which the plain weave is the most common.The use of wire mesh rarely use full stranded weave, in special occasions will use twill weave, such as nylon, polyester, stainless steel wire mesh, twill weave can be used in the requirements of more than 350 mesh screen.If the request pattern is large, the ink amount is large, then USES the nylon silk to carry on the whole twisted weave.