US2090016A - Sensitive photographic element - Google Patents

Description

Aug. 17,1937. A. A. YOUNG ET AL 5 01 SENSITIVE PHOTOGRAPHIC ELEMENT- Filed Jan. 50, 1935 dbbomqyt Patented Aug, 17, 1937 PATENT OFFICE 2,090,010 ssnsmva rno'roenarnro nnnmm'r Albert A. Young andAll'red D. Slack, Rochester,

N. Y., assignors, by, meme assignments, to East,- man Kodak Company, Jersey City, N. 1. a corporation of'New Jersey Application January 30,

1935, Serial No. mic

3 Claims. (or. 9H)

' This invention relates to a photographic film having upon its emulsion or sensitized surface a protective layer which protects it, while sensitive, from abrasion and from the eflects of moisture, and which is permeable to and incompletely removed in an alkaline developing bath, a sufflcient quantity of the coating remaining after ordinary photographic processing to give a high degree of resistance to scratching to the finished film. This 10 is useful in all photographic film,'particularly in motion picture film and is especially desirable in film bearing sound'records'.

Efforts have been made to lubricate the picture surface of motion picture film after exposure and development, but this leaves the emulsion layer exposed to abrasion while it is being run through the camera and while it is being processed. It has also been proposed to coat sensitive .films, for the purpose of waterproofing them, with substances which will be removed during development. Plainly, such coatings can give no protection of any kind after the development of the film, since they are no longer present. Our invention is an' improvement over both -these processes inasmuchas it provides a means for protecting films from abrasion both before and after development.

We have found that natural waxes, such as Montan wax, carnauba wax, ceresin wax, paraf- 30 fin, beeswax, candelilla wax, and the like. meet our requirements, although we alsoinclude in the term "wax synthetic compounds having the physical properties of wax, such as the chlorinated naphthalenes and other "synthetic waxes, a number of which are omthe market which are only incompletely removedin ordinary developing baths. I Reference is made to the accompanying drawing, the single fi gure of which shows a section on 40 an exaggerated'scale of a film embodying our in'-- vention. In this figure, l indicates a support of a suitable composition, customarily a cellulose ester composition, but which may be of any type useful as a photographic support; 2 indicates the 45 sensitive layer, ordinarily a gelatino silver halide emulsion and 3 is the protective layer. i The wax is ordinarily applied from solution in a solvent which does not attack layers l or 2. It is applied by ordinary coating methods either be- 50 fore or after the emulsion layer is thoroughly dry. preferably the latter. The dilution may vary within wide limits depending on the method of to and incompletely coating used and the desired thickness of the coating. The following is a suitable formula:

Grams Chloroform 100 Carnauba w 05 Ethylene dichloride may be substituted for chloroform as a solvent, and any of the natural or synthetic waxes not entirely removed in the developing baths may be used to replace carnauba.

After the solvent has evaporated, there is left a coating 3 which protects the layer 2 while sensitive. Even though the wax is largely removed in the developer, there is'enough left to have a v markedly beneficial efiect in the protection of the 15 finished fl1m,-thereby rendering a later waxing unnecessary. e

We consider as included within our invention all modifications and equivalents falling within the scope of the appendedclaims. m

Having thus described our invention, what we claim'as' new and desire to be secured by Letters Patent of the United States is:

1. A photographic element comprising a support, alight-sensitive silver halide photographic emulsion layer thereon, and a thin, adherent, abrasion-resistant coating over the sensitive emulsion layer and forming the surface of the photographic element, the abrasion-resistant layer comprising a wax which ispermeable to and incompletely removable in an alkaline developing bath.

2. A photographic element comprising a. support, a light-sensitive silver halide photographic emulsion layer thereon, .and a thin, adherent, abrasion-resistant coating over the sensitive emulsion layer and forming the surface of the photographic element, the abrasion-resistant lay er comprising a'natural wax which is permeable removable inan alkaline de- 40 veloping bath.

3. A photographic element comprising a sup-- port, a light-sensitive silver halide photographic

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