With the continuous development and expansion of the optical disc industry, in the process of optical disc production and manufacture, the printing technology of the optical disc surface has been more and more valued by people due to its full color and strong three-dimensional sense, and has been favored by consumers. In the screen printing of optical discs, to accurately reproduce the originals, not only exquisite printing techniques, but also a reasonable choice of screens to produce a good screen, which plays a decisive role in the reproduction of outlets.
First, the CD screen version of the screen requirements:
1. The mesh is woven evenly and smoothly so that meshes with the same size can be obtained in the printing area.
2. It has sufficient tensile strength and abrasion resistance to ensure that the screen plate has sufficient strength to resist the friction generated by the doctor blade, screen plate, and substrate in the printing process, and has a long service life.
3, have strong solvent resistance, low expansion rate, prevent the screen due to water, ink, solvents and other chemical reagents after the expansion, resulting in reduced screen opening area, the amount of ink in the printing process occurs Variety.
4, with a good adhesion of photosensitive materials, improve the screen printing resistance.
5, has a good internal elastic storage, so that after the printing stroke and the plate away from the original state.
Second, the physical properties of the screen:
1. The number of meshes contained in the mesh, wire diameter, and unit length of the screen, and the thickness of the mesh. Because the effective cross-section and wire diameter of the unit length wire mesh determine the relevant stability of the wire mesh, other parameters such as the thickness of the wire mesh, the opening size of the mesh mesh opening, and the open area ratio of the wire mesh are also determined. At the same time, the wire diameter is an index that determines the final imaging capability.
2, the thickness of the screen, open hole rate, theoretical ink volume and theoretical ink volume. These are very useful for comparing screens with different brands, different mesh numbers, and different wire diameters. At the same time, they can also estimate the theoretical ink layer thickness that can be achieved after printing.
3, the screen structure. That is to say, the latitude and longitude of the meshes cross each other and are divided into plain weave and oblique weaving. Plain weaving, that is, latitude and longitude l:l knitting. According to different weaving methods, weaving can be divided into 2:1, 2:2 or 3:3.
Third, a reasonable choice of wire mesh:
When selecting a screen, the resolution of the screen must meet the requirements for the number of lines of the original, and the lines and dots that the screen can eventually reproduce should meet the requirements of the fine level of the printed matter.
1, first determine the mesh size and wire diameter
From the technical parameters of the screen, it can be seen that the same brand, the number of mesh screen, due to the different diameter of the wire, the opening area is different, the amount and the printing accuracy is also different. The diameter of the finest dot or line width that can be printed by the screen is two wire diameters plus one cell width.
(1) SEFAR PETl000 is taken as an example to compare the finest lines that can be made with the same mesh number and different wire diameters.
SEFAR PETl000 150-27PW=27×2+35=89μm
150-3lPW=3l×2+29=9lμm
150-34PW=34×2+25=93μm
From this, it can be seen that the finer the wire diameter and the larger the opening of the same mesh, the more accurate the lines can be.
(2) The finest lines can be printed with different mesh numbers and different wire diameters. Take SEFAR PETl000 as an example.
SEFAR PETl000 180-27PW=27×2+29=83μm
150-31PW=31×2+29=9lμm
Different meshes, the higher the mesh number, the more highly accurate lines can be obtained. It is generally believed that the mesh number of the screen is 3.5 to 6 times the number of lines of the pattern to be printed.
2, the opening of the screen
The size of the opening of the screen will determine the maximum size of the particles that can be used in the ink. The average size of the particles in the ink must be less than 1/3 of the mesh. The opening of the screen determines the fineness of the printed lines and dots. When the screen opening is smaller than the wire diameter, it can not be used to make high-precision screens because the interface between the screen and the substrate is large, blocking the transfer and leveling of the ink. When the screen opening is equal to the wire diameter, it is only acceptable to make a high-precision screen plate. When the screen opening is larger than the wire diameter, it is recommended to make a high-precision screen.
However, a suitable screen does not only have important printing accuracy, but also takes into account other parameters: when the screen is too thin, the screen cannot withstand high tension, and the screen is easily broken during printing; at the same time, the number of screens is high. , For poor ink permeability, uneven ink printing or poor coverage, so the choice of screen is not a single factor can be determined.
Can be reasonably selected according to different printing requirements. In order to obtain thick ink and good coverage, a screen with a low mesh number and a large opening can be selected, and the thickness of the screen is increased accordingly.
Reasonable selection of screens is a point that affects the quality of printing. The production of later screens, the selection of other plate making materials, and the screen making process are equally important.
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