| abstract |
A PHOTOSENSITIVE COMPOSITION COMPRISING (A) ABOUT 100 PARTS BY WEIGHT OF AN UNSATURATED POLYESTER PRODUCED FROM AN ALCOHOLIC COMPONENT COMPRISING AT LEAST ONE POLYOL AND AN ACIDIC COMPONENT COMPRISING AT LEAST ONE UNSATURATED DISCARBOXYLIC ACID, ITS ANHYDRIDE OR ITS METHYL OR ETHYL ESTER AND HAVING AN AVERAGE MOLECULAR WEIGHT OF ABOUT 400 TO 30,000 AND ETHYLENIC DOUBLE BOND EQUIVALENT OF ABOUT 160 TO 3,200, (B) ABOUT 1 TO 50 PARTS BY WEIGHT OF AN ETHYLENICALLY UNSATURATED COMPOUND (I) OF THE FORMULA CH2=C(-R2)-CO-NH-C(-R3)(-R4)-CH(-R5)-CO-R6 WHEREIN R2 REPRESENTS A HYDROGEN ATOM OR MELTHYL GROUP; AND R3, R4, R5 AND R6 REPRESENT A HYDROGEN ATOM, AN ALKYL GROUP OR CYCLOALKYL GROUP HAVING AT MOST 10 CARBON ATOMS, AND ABOUT 10 TO 100 PARTS BY WEIGHT OF A COMPOUND (II) OF THE FORMULA (CH2=C(-R1)-COO)M-X WHEREIN R1 REPRESENTS A HYDROGEN ATOM OR METHYL GROUP; M IS AN INTEGER FROM 2 TO 4; AND X REPRESENTS A RADICAL OF A POLYOL HAVING A MOLECULAR WEIGHT OF AT MOST 1,000 AND M TERMINAL HYDROXY GROUPS FROM WHICH THE TERMINAL HYDROXY GROUPS ARE EXCLUDED, AND, (C) ABOUT 0.0001 TO 10 PARTS BY WEIGHT OF A PHOTOPOLYMERIZATION INITIATOR. THE COMPOSITIONS ARE EXPOSED TO A LIGHT SOURCE THROUGH AN IMAGE-BEARING TRANSPARENCY TO EFFECT POLYMERIZATION, AND UNPOLYMERIZED UNEXPOSED MONOMER IS WASHED AWAY, LEAVING A RELIEF STRUCTURE SUITABLE FOR PRINTING PLATES. THE PLATES ARE CHARACTERIZED BY GOOD FLEXIBILITY, HARDNESS AND WATER RESISTANCE. |