Photopolymerizable compositions and elements and processes of using same

Claim 1

A PHOTOPOLYMERIZABLE ELEMENT COMPRISING A SUPPORT AND A PHOTOSENSITIVE LAYER COMPRISING (1) A SMALL AMOUNT OF A COMPATIBLE ADDITION POLYMERIZATION INITIAFOR ACTIVATABLE BY ACTINIC LIGHT AND NOT ACTIVE THERMALLY BELOW 85*C., (2) A COMPATIBLE ADDITION POLYMERIZABLE ETHYLENICALLY UNSATURATED COMPOUND HAVING A BOILING POINT AT NORMAL PRESSURE OVER 100*C., A MOLECULAR WEIGHT LESS THAN 1500 AND CONTAINING AT LEAST ONE POLYMERIZABLE ETHYLENIC GROUP FOR EVERY 300 UNITS OF MOLECULAR WEIGHT AND CAPABLE OF FORMING A HIGH POLYMER BY PHOTOINITIATED ADDITION POLYMERIZATION IN THE PRESENCE OF AN ADDITION POLYMERIZATION INITIATOR THEREFOR ACTIVATABLE BY ACTINIC LIGHT, AND (3) AN ESSENTIALLY LINEAR CELLULOSE DERIVATIVE OF HIGH MOLECULAR WEIGHT HAVING THE CELLULOSE STRUCTURE AND CONTAINING AT LEAST 50 COMBINED GLUCOSE UNITS IN THE POLYMER CHAIN OF ATOMS, TAKEN FROM THE GROUP CONSISTING OF CELLULOSE PHOSPHATES, CELLULOSE SULFATES, AND CELLULOSE ETHERS AND CELLULOSE CARBOXYIC ACID ESTERS CONTAINING A FREE ACID GROUP TAKEN FROM THE CLASS CONSISTING OF CARBOXYLIC AND SULFONIC ACID GROUPS, AND THE ALKALI METAL AND AMMONIUM SALTS OF SAID CELLULOSE COMPOUNDS, SAID DERIVATIVES HAVING A TOTAL DEGREE OF SUBSTITUTION IN THE RANGE 2.0 TO 3.0 PER GLUCOSE UNIT, THE TOTAL NUMBER OF HYDROXYL GROUPS IN SAID DERIVATIVE, INCLUDING ANY ACID HYDROXYL GROUPS, BEING IN THE RANGE 0.5 TO 2.5 PER GLUCOSE UNIT, THERE BEING SUFFICIENT LATERAL SUCH GROUPS SO THAT SAID DERIVATIVE WHEN IN ACID FORM HAS A NEUTRAL EQUIVALENT IN THE RANGE 200 TO 700, SAID CELLULOSE DERIVATIVE BEING SOLUBLE TO THE EXTENT OF AT LEAST 10% BY WEIGHT IN 1% AQUEOUS AMMONIA SOLUTION, AND SAID INITIATOR BEING PRESENT IN AN AMOUNT FROM ABOUT 0.01 TO ABOUT 5.0% BY WEIGHT OF THE TOTAL COMPOSITION, SAID UNSATURATED COMPOUND CONSTITUTING ABOUT 10% TO ABOUT 60% BY WEIGHT AND SAID CELLULOSE DERIVATIVE CONSTITUTING ABOUT 40% TO ABOUT 90% BY WEIGHT OF THE TOTAL COMPOSITION EXCLUSIVE OF INITIATOR.