US3907570A - Photosensitive material comprising a furfurylidene, a lower haloalkane and poly-n-vinyl carbazole - Google Patents

Abstract

A heat-developable photographic plate which comprises, on a support, a layer containing: as a color former, a furfurylidene compound; as a sensitizer, a lower haloalkane; and, as a color enhancer and binder, poly-N-vinyl carbazole. The plate is capable of forming, after exposure to light, dense, black images at temperatures between about 100*-150*C.

Description

United States Patent 1191 [111 3,907,570

Robie Sept. 23, 1975 PHOTOSENSITIVE MATERIAL 3.697.276 10/1972 Lewis et al 96/90 R COMPRISING A FURFURYUDENE A 3.773515 ll/l973 Yamashita et al. 96/90 R LOWER HALOALKANE AND POLY-N-VINYL CARBAZOLE [75] Inventor: Susan P. Robie, Gorham, Maine [73] Assignee: Scott Paper Company, Philadelphia.

[22] Filed: Mar. 19, 1974 [2]] Appl. No.: 452,596

[52] US. Cl 96/90 R [51] Int. Cl. G03C 1/52 [58] Field of Search 96/90 R [56] References Cited UNITED STATES PATENTS 3,394,395 7/1968 Mattor et al, 96/90 R Primary E.raminei=-Won H. Louie, Jr. Attorney, Agent, of Firm.lohn A. Weygandt; John W. Kane, Jr.

[57] ABSTRACT A heat-developable photographic plate which comprises, on a support, a layer containingz'as a color former, a furfurylidene compound; as a sensitizer, a lower haloalkane; and. as a color enhancer and binder, poly-N-vinyl carbazole. The plate is capable of forming, after exposure to light, dense, black images at temperatures between about lOO-l50C.

1 Claim, N0 Drawings Laridon et al. 96/90 R BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to photosensitive materials.

More particularly, it relates to a negative-working, thermally-developable and fixable photographic plate comprising, on a support, a purified furfurylidene compound, a tertiary amine and a photosensitive lower haloalkane.

2. History of the Prior Art In U.S. Pat. No. 3,394,395 granted July 23, 1968, there is disclosed and claimed a photographic medium consisting essentially of a transparent to translucent plastic film containing dissolved therein a furfurylidene compound as the color forming ingredient, a primary aromatic amine enhancer, and a lower haloalkane sensitizer, e.g., iodoform. The photographic medium is negative working and is usually carried as a film on a support thereby forming a photographic plate. Permanently'black or colored images can be produced by the process disclosed therein by short exposures of the photographic medium to light directed through an image-containing transparency. An unusual feature is that no chemical treatment is required to develop the image or to desensitize the unexposed or background areas. All that is required to develop the image is to heat the medium briefly to about l()()150C. I

It is stated in U.S. Pat. No. 3,394,395 that it appears that the aldehyde groups derived from the furfurylidene react with the amine group of theenhancer. In every case tested, secondary and tertiary aromatic amines have failed to give color enhancement of the image. This indicates that one essential reaction for color formation in the present invention is the reaction of primary amine groups.... Column 2, lines l5.

SUMMARY OF THE INVENTION -vinyl carbazole replaces both the enhancer and binder components of the prior art composition.

DETAILED DESCRIPTION Poly-N-vinyl carbazole, also known as poly (9- vinylcarbazole), is commercially available and may be represented by the formula In general, the haloalkane sensitizer used in the present invention is a solid at room temperature and has a purity of at least 98%. Compounds containing 1 to 2 carbon atoms, such as iodoform and pentabromethane, are preferred. The furfurylidene color-former'is usually prepared by reacting furfural with a suitable amine, in the case of the furfurylidene imines, and with a suitable glycol or higher polyol, in the case of the cyclic acetals. Conventional organic synthesis techniques are used, as more fully described in U.S. Pat. No. 3,394,395.

The furfurylidene color-former, the haloalkane sensitizer and the poly-N-vinyl carbazole are applied to a suitable support insolvent solution. Any one of several suitable organic solvents that are volatile at room temperature or at slightly elevated temperatures can be used such as chloroform; benzene; 1,1,2 trichloroethane and methyl ethyl ketone. Mixtures of the solvents can be used to obtain improved solvation.

While the polymeric tertiary amine of the present invention offers the advantage of replacing both. the enhancer and binder components of the prior art composition, other filmforming resins may be included in the coating formulation if desired. Such a film-forming resin should be essentially non-reactive with the other ingredients of the solution and desirably in its pure state forms a translucent or transparent film that is colorless or substantially colorless so as not to interfere with or mask the color produced by the other ingredients in the photographic medium. Some polyester polymers have been found to be unsatisfactory presumably because the hydrogen iodide attacks the ester linkage. The polymer should be unaffected by concentrated aqueous solutions of hydrogen iodide at 25C. In most cases it is desirable for the polymer to form a non-tacky film. Preferred polymer film-formers or binders include polyphenylene oxide and polystyrene. I The weight ratio of poly-N-vinyl carbazole to the furfurylidene color-former is usually in the range of l to 1 to 5 to l, and when the poly-N-vinyl carbbazole is used as the sole binder preferably 5 to 1. The weight ratio of haloalkane sensitizer to color-former is in the range of l to 10 through 20 to 1, preferably 1 to 2 through 2 to l. The coating solids used will normally be in the range of 10 to 20 percent. A photographic plate is prepared from the coating solution by applying it to a suitable support by conventional means to produce, upon drying, a coating weight of 3 to 15 g/m or a film thickness of 1 to 10 microns. Other things being equal, the thicker the film, the more intense the image.

The support used in the preparation of a photographic plate may require a coating on its surface to prevent the penetration of organic solvents. In the case of paper, starch and potassium polyacrylate resins and similar binders will accomplish this function. In general, water soluble resins that are film-formers can be expected to give adequate solvent hold-up. In the case of transparent supports, films of polyethylene terephthalate resin (DuPonts Mylar) have proved to be excellent supports and particularly suitable for the preparation of films for microphotographic copying. In cases where transparent supports are not desired, any impermeable inert support such as aluminum, sheet steel, glass, etc. may be employed.

These and other principles, features and advantages of the present invention will become more fully understood fromv a consideration of the following examples.

EXAMPLE I A photographic plate was prepared from a coating solution comprising:

Parts by Weight dissolved in an amount of a solvent consisting of 60% by volume methylene chloride and 40% by volume trichloroethylene sufficient to form a solution having 18% solids by weight.

The solution was applied in an amount equal to 7.5

'g/m by dry weight to one side of a suitably barrier EXAMPLE ll A photographic plate was prepared from a coating solution comprising:

Parts by Weight poly-N-vinyl carhazole 3.0 difurfurylidene pemaerythritol 3.0 iodoform 4.0 poly phenylene oxide 8.0 a-methyl styrene 8.0

dissolved in an amount of the mixed solvent described in Example l to form a solution having 18% solids by weight. This solution was applied in an amount equal to 13.75 g/m by dry weight to one side of a suitably barrier coated paper sheet, and dried.

A second photographic plate was prepared from a coating solution comprising:

Parts by weight difurfurylidene pentaerythritol 3.0 iodoform 4.0 poly phenylene oxide 8.0 a-methyl styrene 8.0

This coating formulation was made up and coated in the manner described above.

Both the plate containing poly-N-vinyl carbazole and the plate containing no amine were exposed under the lamp described in Example I for one minute and heat developed as in Example .I. I

The results indicated that the plate containing poly- N-vinyl carbazole was'five times as sensitive to light as the plate containing no amine. The imaged plates were then subjected to accelerated aging-7 days at 38C. While the image formed on the plate containing the poly-N-vinyl carbazole was slightly faded, the image on the plate containing no amine had completely disappeared.

While the invention has been described with reference to preferred embodiments thereof, it is understood that various other changes and modifications thereof will occur to a person of ordinary skill in the art without departing from the spirit and scope of the invention, as defined by the appended claims.

What is claimed is:

l. A heat-developable photographic plate comprising, on a support, a layer containing: as a color former, a purified furfurylidene compound; as a sensitizer, a photosensitive lower haloalkane; and, as a color enhancer and binder, poly-N-vinyl carbazole.

Claims (1)

1. A HEAT-DEVELOPABLE PHOTOGRAPHIC PLATE COMPRISING, ON A SUPPORT, A LAYER CONTAINING: AS A COLOR FORMER A PURIFIED FURFURYLIDENE COMPOUND, AS A SENSITIZER, A PHOTOSENSITIVE LOWER HALOALKANE, AND, AS A COLOR ENHANCER AND BINDER, POLY-N-VINYL CARBAZOLE.