Patent GB-544006-A (GB)
Title: Improvements in sensitive photographic elements
IPC: G03C1/825
Filed: 1940-09-16
Abstract: 544,006. Photographic light-sensitive material. KODAK, Ltd. (Eastman Kodak Co., and Simmons, N. L.). Sept. 16, 1940, Nos. 14235/40 and 10700/41. [Class 98 (ii)] Photographic material has on a support at least one light-sensitive emulsion layer and a layer, especially an anti-halation layer, consisting of carbon particles dispersed in a water-insoluble alkali- or acid-soluble binder. The carbon particles may be below 60 mÁ, preferably 30 mÁ in average diameter. The alkali-soluble binders may be synthetic resins, e.g. polyvinyl esters of dicarboxylic acids, or cellulose esters, e.g. cellulose esters of dicarboxylic acids, or mixed esters of mono- and di-carboxylic acids. Suitable resins are polyvinyl phthalate and polyvinyl acetate phthalate, and suitable cellulose esters are cellulose acetate phthalate, acetate maleate, acetate succinate, propionate phthalate, acetate propionate maleate, and acetate propionate succinate. The carbon may be dispersed in the colloid by using a mechanical disintegrator or colloid mill, or may be dispersed in a solution of the colloid using a dispersing agent such as water-insoluble metallic soap, an Aerosol (a sulphonated ester of a dicarboxylic acid), or Novonacco (a modified sodium alkyl naphthalene sulphonate). The carbon should preferably be mixed with the colloid itself, little or no solvent being present during disintegration. The carbon may be mixed with the colloid in the dry state and a small quantity of plasticizer added and after further mixing the mixture is fed between the rolls of a mill of the type used in the rubber industry. The rolls may be heated or cooled in order that the mass shall exhibit an unusually high consistency. In example (1), 500 grams of cellulose acetate phthalate, 200 grams of carbon black, and 200 grams of methyl carbitol are mixed with a paddle and fed into the rolls of a rubber mill, the rolls being water cooled to maintain a maximum temperature of 180F. After 15 minutes' milling, the sheet of material wrapped completely about the faster roll is stripped off and allowed to cool. 75 grams of the material are dissolved in 270 grams of ethylene glycol methyl ether, 160 grams of water, 10 grams of acetone, and 380 grams of ethyl alcohol, and coated on a support to form an anti-halation layer. The coatings may also be used in the preparation of leaders and anti-static layers. The methyl carbitol may be replaced by ethylene glycol methyl ether, triacetin, or dibutyl phthalate. Carbon black in the form of a paste containing as dispersing agent copper oleate, stearate, or resinate, or dry carbon black may be formed into a paste with water containing a dispersing agent and a small amount of alkali. The paste may be mixed with an organic solvent and added to the binder dissolved in organic solvents and coated. In example (2), colloidal carbon paste is dispersed in a mixture of water and ethylene glycol monomethyl ether and a solution of polyvinyl phthalate in acetone and methyl alcohol is added. The mixture is run through a colloid mill, diluted with methyl alcohol, and coated. In example (3), carbon black is mixed with " Emulphor 0" (Registered Trade Mark), which is a polyethylene glycol condensation product, in ethyl alcohol to form a paste, a solution of polyvinyl acetate phthalate in ethyl alcohol added, the mixture passed several times through a paint or colloid mill, and, after diluting, the dispersion is coated. Specification 537,081 is referred to.