Photohardenable compositions containing a dye-borate complex and photosensitive materials employing the same

DETAILED DESCRIPTION OF THE INVENTION U.
S.
Pat.
Nos.
4,399,209 and 4,440,846 and U.
S.
application Ser.
Nos.
339,917, filed Jan.
18, 1982, and 620,994, filed June 15, 1984, are incorporated herein by reference to the extent that reference thereto may be necessary to complete this disclosure.
Cationic dye-borate anion complexes are known in the art.
Their preparation and use in imaging systems is described in U.
S.
Pat.
Nos.
3,567,453; 4,307,182; 4,343,891; 4,447,521; and 4,450,227.
The complexes used in the present invention can be represented by the general formula (I): ##STR1## where D.
sup.
+ is a cationic dye; and R.
sup.
1, R.
sup.
2, R.
sup.
3, and R.
sup.
4 are independently selected from the group consisting of alkyl, aryl, alkaryl, allyl, aralkyl, alkenyl, alkynyl, alicyclic and saturated or unsaturated heterocyclic groups.
Useful dyes form photoreducible but dark stable complexes with borate anions and can be cationic methine, polymethine, triarylmethane, indoline, thiazine, xanthene, oxazine and acridine dyes.
More specifically, the dyes may be cationic cyanine, carbocyanine, hemicyanine, rhodamine and azomethine dyes.
In addition to being cationic, the dyes should not contain groups which would neutralize or desensitize the complex or render the complex poorly dark stable.
Examples of groups which generally should not be present in the dye are acid groups such as free carboxylic or sulphonic acid groups.
Specific examples of useful cationic dyes are Methylene Blue, Safranine O, Malachite Green, cyanine dyes of the general formula (II) and rhodamine dyes of the formula (III): ##STR2## R', R=alkyl, aryl, and any combination thereof While they have not been tested, the cationic cyanine dyes disclosed in U.
S.
Pat.
No.
3,495,987 should be useful in the present invention.
The borate anion is designed such that the borate radical generated upon exposure to light and after electron transfer to the dye (Eq.
1) readily dissociates with the formation of a radical as follows: BR.
.
sub.
4 .
fwdarw.
BR.
sub