| 摘要 |
Photosensitive urethane resin compositions containing a) at least one urethane prepolymer which contains, in the centre of its molecule, at least two polyol monomer units which are connected via a diisocyanate monomer unit, and, only at the molecule ends, on average at least 1.6 carboxyl groups per molecule and acrylic radicals containing a vinyl group, essentially one of the acrylic radicals being present at each end of the urethane prepolymer molecule; b) at least one ethylenically unsaturated compound, and c) at least one photopolymerisation initiator. If desired, the compositions can also contain at least one thermal polymerisation inhibitor. The compositions can be developed by means of aqueous developers to give printing plates which, after post-exposure, even with small amounts of light and even in the presence of air, have sufficient mechanical strength, are virtually tack-free and exhibit high water, moisture, wear and abrasion resistance and thus have great durability.
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