United States Patent (19) (11) Patent Number: 4,859,572 Farid Et Al
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United States Patent (19) (11) Patent Number: 4,859,572 Farid et al. (45) Date of Patent: Aug. 22, 1989 54 DYE SENSTIZED PHOTOGRAPHIC IMAGING SYSTEM FOREIGN PATENT DOCUMENTS 0223587A 5/1987 European Pat. Off, . (75) Inventors: Samir Y. Farid; Roger E. Moody, 2083832A 3/1982 United Kingdom . both of Rochester, N.Y. OTHER PUBLICATIONS (73) Assignee: Eastman Kodak Company, Volman et al., Advances in Photochemistry, vol. 13, in the Rochester, N.Y. chapter titled "Dye Sensitized Photopolymerization' 21 Appl. No.: 189,002 by D. F. Eaton, pp. 427 to 488, John Wiley & Sons (1986). 22) Filed: May 2, 1988 Farid et al., U.S. Ser. Nos. 933,712, 933,658,933,660, 51 Int. Cl." ................................................ G03C 1/68 and 933,657, all filed Nov. 21, 1986, and commonly (52) U.S. Cl. ..... ... 430/281; 430/914; assigned (Now issued as Farid et al U.S. Pat. Nos. 430/915; 430/916; 522/25; 522/26; 522/27; 4,743,528; 4,743,529; 4,743,530; and 4,743,531). 522/28; 522/31 Primary Examiner-Paul R. Michl (58) Field of Search ............... 430/915, 281, 916,914; Assistant Examiner-C. D. R. Dee 522/25, 28, 63, 27, 26, 31 Attorney, Agent, or Firm-Carl O. Thomas 56) References Cited (57) ABSTRACT U.S. PATENT DOCUMENTS A photographic imaging system is disclosed comprised 4,050,934 9/1977 Turner .................................. 96/1 R of a hardenable organic component containing ethyl 4,289,842 9/1981 Tan et al. ... ... 430/270 enic unsaturation sites and an initiator system for ethyl 4,307,182 12/1981 Dalzell et al. ....................... 430/339 enic addition. The initiator system is comprised of an 4,353,787 10/1982 Alexander et al. ... 204/159.15 electron acceptor activator, an electron donor activa 4,399,209 8/1983 Sanders et al. ...................... 430/138 tor, and, acting as a photosensitizer, a dye capable of 4,440,846 4/1984 Sanders et al. .. ... 430/138 absorbing imaging radiation. The dye has a reduction 4,497,889 2/1985 Fuerniss .................. ... 430/260 potential related to that of the electron acceptor activa 4,571,377 2/1986 McGinniss et al. ................... 430/31 tor and an oxidation potential related to that of the 4,590,147 5/1986 Lindley ............... ... 430/286 electron donor activator to permit each to release a free 4,743,528 5/1988 Farid et al. .. ..., 430/281 radical upon excitation of the photosensitizer by expo 4,743,529 5/1988 Farid et al....... ... 430/281 4,743,530 5/1988 Farid et al....... ... 430/28 sure to actinic radiation. 4,743,531 5/1988 Farid et al. ...... ... 430/281 4,772,541 9/1988 Gotschalk .......................... 430/339 15 Claims, No Drawings 4,859,572 1. 2 the latter by photon capture, causing release of a free DYE SENSITIZED PHOTOGRAPHIC IMAGING radical which in turn induces immobilizing addition SYSTEM reactions at sites of ethylenic unsaturation. Imaging systems which rely on a combination of an FIELD OF THE INVENTION activator and a photosensitizer are typically exposed in This invention relates to photography. More specifi the ultraviolet or blue portion of the spectrum. The cally, this invention relates to an imaging system which necessity of using shorter imaging wavelengths places relies upon the hardening of organic component con constraints on the master or pattern employed for imag ing. For example, a master which presents a longer taining ethylenic unsaturation to produce an image 10 pattern. m wavelength visible dye image, but exhibits little vari ance in ultraviolet or blue transmittance is not well BACKGROUND OF THE INVENTION suited for imagewise exposing an imaging system which A variety of photographic imaging systems are responds only to ultraviolet or blue radiation. Further, known wherein a hardenable organic component con such imaging systems are disadvantageous and have taining ethylenic unsaturation sites is relied upon for 15 found limited acceptance in producing multicolor im image formation. The organic component undergoes ages, photoinduced addition reactions, typically either poly Activators are recognized in the art to fall into two merization or crosslinking, at the ethylenic unsaturation distinct classes. One class of activator is referred to as sites which produce hardening and allow image dis electron acceptor activators. These activators liberate a crimination to be achieved. 20 free radical capable of initiating ethylenic addition by A simple illustration of such an imaging system is a negative working photoresist which contains an imag accepting an electron from a photosensitizer in its ex ing dye. Imagewise exposure of the photoresist fol cited state. The reactions can be diagrammed as fol lowed by development leaves a dye image in exposed lows: areas. While there are a plethora of known negative 25 working photoresists which might be cited, Tan et al (I) U.S. Pat. No. 4,289,842 illustrates photoresist employ Sens - A seSens' (a) ing crosslinkable copolymers containing ethylenic un saturation in pendant groups, Lindley U.S. Pat. No. b 4,590,147 illustrates photoresists including vinyl oligo 30 Sens* -- A+-R-G-Senst + A-R (b) mers, and Fuerniss U.S. Pat. NO. 4,497,889 illustrates photoresists containing vinyl monomers. (c) Illustrative of more elaborate imaging systems capa ble of producing transferred dye images are Sanders et al. U.S. Pat. Nos. 4,399,209 and 4,440,846. A dye pre 35 where cursor and a hardenable organic component containing Sens represents a photosensitizer, ethylenic unsaturation sites are coated together on a N represents exposure to actinic radiation, support in rupturable microcapsules. Imagewise expo * indicates the excited state produced by light absorp sure to actinic radiation hardens the organic component tion on exposure, by inducing addition at its ethylenic unsaturation sites. At-R represents the electron acceptor activator, Upon subsequent rupture of the microcapsules only the At represents the electron accepting moiety of the dye precursor in unexposed microcapsules have the activator before an electron is accepted, mobility to transfer to a receiving sheet where a view A represents the electron accepting moiety of the able dye image is formed. activator after an electron is accepted, R represents the Since the hardenable organic components containing 45 moiety that is ultimately cleaved as a free radical, ethylenic unsaturation exhibit only limited direct re Sens shows the photosensitizer converted to a cat sponse to exposing radiation, it is common practice to ion radical by loss of an electron, and include an initiator of the ethylenic addition reaction. In denotes a radical. practice negative working photoresists are typically The reaction sequence described above is an ideal one imagewise exposed using radiation wavelengths in the 50 in which the electron acceptor activator radical pro near ultraviolet region of the spectrum. While Sanders duced by step (b) reacts further as indicated in step (c) et all recognize that imaging exposures are possible with to provide a free radical. ignored in this reaction se various forms and wavelengthss of radiation, the pre quence is a possible recombination of the photosensi ferred wavelengths of exposure are limited to the ultra tizer cation radical with the electron acceptor activator violet and the blue, up to about 480 nm, with the initia 55 radical to regenerate the electron acceptor activator in tors for the ethylenic addition reaction disclosed being its initial form and to transform the photosensitizer those which are responsive at these wavelengths of cation radical into an unexcited dye molecule. This exposure. reaction sequence can be diagrammed as follows: In order to achieve higher levels of sensitivity (i.e., higher imaging speeds) than can be achieved with a 60 single initiator, it is common practice in preparing imag a. ing compositions to employ coinitiators. One of the Sens - As Sens' (a) coinitiators is a photosensitizer. Photosensitizers are relied upon to capture photons of exposing radiation. Sens* + A*-R-G-Senst + A-R (b)b The remaining coinitiator is referred to as an activator. 65 The activator is not relied upon to respond directly to d exposing radiation, but rather adjacent activator and Senst + A-R-G-Sens + At-R (d) photosensitizer molecules react, following excitation of 4,859,572 3 w 4 Photon6. energy is internally dissipated in this reaction cationic dyes include Methylene Blue, Safranine O, sequence, since no free radical is produced and the Malachite Green, and various cyanine and rhodamine photosensitizer produced is no longer in an excited dyes. state. More efficient imaging systems are those in which reaction step (c) is favored over reaction step (d). Related Patent Applications Another class of activator is referred to as electron Farid et al U.S. Ser. Nos. 933,712, 933,658,933,660, donor activators. These activators liberate a free radical and 933,657, all filed Nov. 21, 1986, and commonly capable of initiating ethylenic addition by donating an assigned, disclose hardenable compositions comprised electron to a photosensitizer in its excited state. The of an organic compound containing ethylenic unsatura reactions can be diagrammed as follows: O tion, an azinium salt activator, and, acting as a photosen sitizer, a dye having a reduction potential which is at III most 0.1 volt more positive than the reduction potential of the azinium salt activator. Sens - A seSens' Farid et al U.S. Ser. No. 933,657 discloses the combi 15 (f) nation of a photosensitizer, an alkoxy azinium electron Sens" + D--R-G-Sens + D-R' acceptor activator, and benzene substituted with an electron donating amino group, acting as an imaging D-R -GD + R' (g) enhancer. Although amines are known to be electron donor acceptors, the aminobenzene enhancers require 20 where one or more benzene ring substituents having a Ham D-R' represents the electron donor activator, mett sigma value electron withdrawing characteristic of D- represents the electron donating moiety of the at least -0.20 volt.