Screen Printing Screen Selection and Evaluation of Wire Mesh Parameters (Part 2)

1.2 Use PW (ie, 1:1) plain weave, high mesh (which should match the requirements), high tension, low stretch yellow screen as much as possible. Because the 1:1 plain weave mesh has lower ink volume than the same mesh and twill TW mesh with the same wire diameter (small), the printed pattern is also clear, which is more important for UV inks. The high-mesh, low-extension, and high-tension screens not only ensure the fineness, but also the leveling of the ink layer due to the small contact with the substrate during the 1:1 plain weave screen printing. Uniformity is improved, and when the yellow screen is exposed (stencil printing), the halo phenomenon is eliminated, and the fineness of the pattern is ensured.

1.2. 1 Same number, different weaving, ie PW = 1:1 and TW = twill weave (eg 2:1, 2:2, etc.) The volume of the ink through the screen is different, for example, compare Switzerland Safa polyester high-tension wire mesh:

The ink-permeation volume of 140-30Y PW is 10.3CM3/M2. The screen thickness is 53 M. Similarly, the ink-permeation volume of 140-34Y TW is 13.2CM3/M2. The screen thickness is 62 M. Another example is 150. The ink-permeation volume of the -34Y PW is 6.6 cm3/M2, and the screen thickness is 55 M.

The ink-permeating volume of 150-34Y TW is 9.6CM3/M2, and the thickness of the screen is 62M. Therefore, the TW web with the same mesh number is larger than the plain PW, but since the contact area between the web and the substrate is also larger than the plain weave, the ink leveling and uniformity are The plain weave fabric is more advantageous than the twill weave fabric, and we prefer the plain weave fabric for the thin and uniform color printing of the ink layer.

1.2.2 For tone printing, more 1:1 plain weave, high mesh, large openings, high tension, low stretch colored meshes are required. This is of sharpness to the screen pattern and flatness of the ink blot. Guaranteed benefits.

1.3 Dot printing of solvent-based inks and UV-ultraviolet curable inks

1.3.1 Solvent Ink:

For coarse lines less than 32 lines/cm, it is recommended to use 120-34Y (or W) PW network with 60 lines/cm or less. Use of 140-31YPW, PET 150-31YPW, PET 165-27YPW, PET is recommended. Web 1.3.2 UV ink:

Lightbox advertising is recommended to use 140-34Y PWPET network

Fine dot printing is recommended to use 150-34Y PWPET net

165-31Y PWPET Network

180-27Y PWPET Network

It is also possible to use a single-sided, flat UV screen because:

A. When the pressure plane of the screen is placed on the ink surface of the screen, the amount of ink under the screen is reduced by approximately 10% from that of the commonly used screen of the same number of screens.

B. When the pressure plane of the screen is placed on the printing surface of the screen, the amount of ink under the screen is reduced by approximately 20% compared with the amount of ink used for the same number of the same screen.

C. From the perspective of favoring the UV ink curing, the use of high-mesh, small-mouthed screens is less than the use of the same number of openings in the screen mesh (ie, the same number of meshes with different wire diameters, coarse wire mesh diameter Finer than the diameter of the mesh less ink); Under the same mesh with the diameter of the same, should be selected 1:1PW plain weave mesh, because the PW less than the TW twill weave mesh less ink

1.4 It must be noted that in the case of fine printing, the lack of ink on the screen may result in the incompleteness of the printed ink. Therefore, considering the screen and printing parameters in the selection process

A. The bigger the value of MO/d is, the better is the large opening, small wire diameter

B. The smaller the contact area between the screen and the product, the better. The order of the bad and the bad is plain weave, flattened net and inclined net, and the contact area with the substrate gradually increases.

C. The greater the net thickness/d value is, the better it is, and it is good for the ink, but also makes the silk screen ink even and the pattern is full of ink. A single-stranded PET web with a web thickness/A value > a multiple-stranded PET web, so that in the screen printing, a plurality of braided webs are not used.

D. Comparison of the MO/d values ​​of screens

It can be seen that although the wire diameter d=31 is equal for both screens, the amount of ink obtained is different due to the size of the openings. MO is the largest, and the amount of ink is also large and large, and the ink is blocked by the screen. Small, the ink spreads well, so that the graphics are full of ink and the print is complete. Therefore, for fine graphics or dot printing, it does not mean that the higher the number of screen meshes, the better the printed graphics. Under the condition of ensuring the completeness of the graphics, it must meet the fine requirements and should be selected appropriately. The number (using only a low number of meshes close to the required number) is correct, which saves money under the premise of quality assurance.