A method for producing a digital screen printing blank usable in a screen printing
process, directly from digital information in the computer, in an economical fashion.
In a preferred embodiment, a screen (28) is provided with a photosensitive
layer (38), and a digitally determined image from a computer is printed
on the screen by means of an inkjet printer. Preferably, a flat bed ink-jet imaging
system is used so that the screen can be stretched in a frame and directly placed
under the ink-jet head (44). The ink (46) used need not have strong
colorant, but functions as a UV mask and thus must contain a UV absorbing pigment.
The ink is not absorbed into the photosensitive layer, but remains as an undried
image (56) on the surface. The ink must remain wet so that it does not spread
and therefore gives a sharp image, and so that the UV absorbent material remains
concentrated. The solvent of the ink must be chosen so as to assure that it will
not affect the screen. The screen is then irradiated with UV, and the areas which
have been printed with ink serve to mask the photosensitive layer from the UV light,
while those areas having no ink are exposed so that the photosensitive layer is
polymerized by the UV. After the UV irradiation stage, the screen is washed so
as to remove the ink and the unpolymerized photosensitive layer. Any liquid that
is suitable for washing out the unpolymerized photosensitive layer will also wash
away the ink. This leaves the screen with only the polymerized areas of the photosensitive
layer that create the blocked areas through which the ink will not pass. Thus,
the inventive method provides a digitally imaged screen, directly from a digital
image in the computer, which can then be used in any conventional screen printing process.
