The Correct Selection of Screens--Guarantee for High-quality Screen Printing (Part 2)

Fourth, the quality of wire mesh materials

As a screen printing substrate - screen, it should pay attention to the following aspects:

The screen must have a certain strength and wear resistance, ensure good stretch netting and printing requirements, and can meet the printing and screen version of the large-volume product recycling and reuse.

Wire mesh requires smooth and clean mesh, uniform mesh size, squareness, density, small elongation rate, low shrinkage rate, avoid mesh deformation or mesh clogging, and facilitate the production of printing plates and the implementation of printing operations.

Wire mesh should have chemical resistance, strong acid resistance, alkali resistance and anti-aging properties. It should be minimized by the influence of various solvents, inks, and slurries. It is convenient for film cleaning and printing plates. The image can be stored without being discarded because the plate becomes brittle due to long-term storage.

The screen must have a certain degree of resilience, and the resilience cannot be too large or too small. When the screen is too large, it is easy to cause the edges of the image to be unclear; it is more difficult to scrape the ink sheet for printing. The reasonable elasticity should be determined based on the size of the image, the distance between the frame and the substrate during printing, the station scheduling of the ink and slurry, and other factors.

Fifth, the choice of screen material in plate making

Careful consideration should be given before using silk screens as printing plates. The choice of whether the screen is suitable or not is the key to the quality of the printing plate and the product printing. How can we choose the screen for making the printing plate, combining the actual operation experience of our factory, from the following aspects.

According to the original design requirements, image size, line thickness selection of different mesh screen. High design requirements, small image, small text, thin lines, the thin line width of about 0.2 millimeters can be used to make the printing plate with 250 mesh and above mesh; conversely, the design requirements are not high, the image is large, the lines are wide, most Thin lines with a width of 0.3 mm or more can be made with screens of 200 mesh or less. It should be noted that the screen mesh is less than 180 mesh, and the printed edge of the image produced by the printing plate is more obvious.

According to the thickness of the product ink layer to choose different mesh screen. The more the number of screen meshes, the smaller the mesh diameter, the smaller the amount of ink or paste that passes through, and the layer of ink that accumulates on the prints will appear to be very thin; the screen mesh is small, and the mesh diameter is large. There are many inks or slurries, and the layers of ink deposited on the prints are thickened accordingly.

According to the size of the ink or paste, pigment particle size to choose different mesh screen printing plate, choose to make the plate mesh mesh should be less than half of the pigment particles, to ensure that a mesh can pass two The above pigment particles, in order to ensure high-quality printing results.

The screen printing plate produced requires strong acid resistance. For inks and pastes, pigments that need to be heated to print must be selected from the wire mesh to make printing plates. The printing plates made of metal mesh can be used for electrification. Warm to reduce the viscosity of the ink or paste to facilitate printing. At the same time, the strong acid resistance of the wire mesh facilitates washing and recycling.

True silk screens, nylon screens, and polyester screens are available in white and yellow. When direct plate-making is used for exposure, the white screen can easily cause diffraction of light, causing errors in the produced plate and film (the photosensitive portion of the plate is larger than the film), and the edge of the image is imaginary. White silk wood should be used to make high-precision printing plates. It is best to choose yellow screens for printing high-precision printing plates to reduce the diffraction phenomenon of exposure time. The errors of the plate and film can be limited to the minimum range. The quality of the printing plate is ensured, thereby avoiding the halation caused by reflection on the white screen, the image distortion, and the problem of uneven edges.
Sixth, the advantages and disadvantages of various types of wire mesh and the use of effects

Name Mesh/inch Accuracy Print rate Resistance Economic use Ratio
Polyester mesh 70-380 Good Good Good Good 80%
Nylon Screen 70-400 Poor Good Average Good 16%
Wire Mesh 80-500 Good Good Good General 3%
Silk screen 70-200 General Average Poor 1%

In a word, silk screen is the base material of silk screen printing plate, the silk screen has very important influence on the quality of printing plate production. In order to obtain an ideal printing plate, before screen printing plates are made, the performance and variable factors of the screen must be clarified, and carefully selected so that the screen printing plates produced can achieve the desired effects.

Source: Longjiang Printing Network