Method for manufacturing a flexographic printing master

Abstract

A method for manufacturing a flexographic printing master comprising the steps of: (a) providing an ink-receiver surface; (b) jetting a curable jettable fluid on the ink-receiver surface characterized in that the curable jettable fluid comprises at least one photo-initiator, at least one monofunctional monomer, at least 5 wt % of a polyfunctional monomer or oligomer and at least 5 wt % of a plasticizer both based on the total weight of the curable jettable liquid capable of realizing a layer after curing having an elongation at break of at least 5%. A storage modulus E' is smaller than 200 MPa at 30 Hz, and a volumetric shrinkage is smaller than 10%.

Description

technical field [0001] The present invention relates to digital flexography, and more particularly to a method of making flexographic masters using curable jettable liquids. Background technique [0002] Flexographic printing plates are well known for printing on soft and deformable surfaces such as packaging materials such as cardboard and plastic films. They can be prepared from printing plate precursors having a layer consisting of a photopolymerizable composition Typically includes an elastomeric binder, at least one monomer and a photoinitiator. Earlier patents on flexographic printing plates include US3960572 (ASAHICHEMICAL), US3951657 (UP JOHN), US4323637 (DU PONT) and US4427759 (DU PONT). [0003] Traditionally, an image is applied to the printing plate precursor by flood exposing the photopolymerizable layer to actinic radiation, such as ultraviolet radiation, using an image mask positioned between the radiation source and the printing plate precursor. Actinic radia...

AI Technical Summary

Problems solved by technology

[0004] The process of making flexographic printing plates is simplified by applying a layer forming an image mask directly on the printing plate precursor. In US6521390 (AGFA), an IR ablatable layer which is substantially opaque to actinic radiation On the plate precursor. US6358668 (AGFA) discloses the ink-receiving layer on the photopolymerizable layer of the flexographic printing plate The introduction of an image-mask-forming layer into the plate precursor simplifies the process of making flexographic printing plates, but the process is complex and time-consuming. In addition, the process is not suitable due to the high waste generated in the unexposed areas where the photopolymerizable layer is removed. Environmentally friendly.

[0005] US5511477 (IDANIT TECHNOLOGIES) discloses a method of producing a photopolymer letterpress printing plate, the method comprising the steps of: using a photopolymer ink composition optionally preheated to about 30-260° C. and subject the obtained printing substrate to UV radiation, thereby curing the image-forming ink composition. Suitable substrates for this method are limited to steel, polyester, and other rigid materials, limiting aniline Possibility for printing applications. Another problem is that the jetted drops of polymer inks are still mobile and tend to deform, thereby preventing the accurate reproduction of small dots and the formation of sharp edges and thus sharp images. .

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