US2626867A - Light-sensitive photographic element - Google Patents

Description

Jan. 27, 1953 L, J1 'WEBSTER I 2,626,5867

' LIGHT-SENSITIVE PHOOGRAPHIQELEMBNT Filed Dec. 4, 13117I GELATIN SILVER CHLOROBROMIDE EMULSION 5 coNTAlNlNc PoRous MAGNEswM sILlcATE E gaeaeeaz-re'aezg@ PARTGLES Z W BARYTA coATlNG PAPER SUPPORT GELATIN SILVER CHLOROBROMIDE EMULSION CONTAINING POROUS SILICON DIOXIDE PARTICLES PHOTOGRAPHIC PAPER BASE INVENTOR LAWRENCE J. WEBSTER ATTORNEY Patented Jan. 27, `1953 UNITED STATES PATENT GFF ICE LIGHT-'SENSITIVE PHOTOGRAPHIC ELEMENT Lawrence .L Webster, Rochester, N. Y., assigner `to E, Ldu Pont de Nemours & Company, Wilvmingtom Del., a corporation ofDelawai-e Application December 4, 1947, SerialNo. '789,769

Claims. (Cl. 95-7) This invention -relat'es 'to photographie elements which have a ldelustered or matte surface. More 'particularly it relates-to photographic elements which have -a`waterpermeable outer layer or strata which has -a matte surface.

An object of thisinve'ntion is to .providephotographicelements'whichhave vanimproved'smooth matte surface. A furtherfobjectis-to .provide such elements wherein the mattin'glagentslare not. subject to chemical decompositioncby "fungi or bacteria. A still `further object iis to provide such elements in which the matting agents v'are not readily deformable and are stable vSover -a wide range of temperature conditions. Another object is to V'provide such elementsiha 'simple and economical manner. -Stll 'other objects will b'e apparent from the following description.

The above objects 4are attained hby the novel photographic elements of this Uinvention which consist o'f Vasuppcrtye. g.,-a lm orpaperLbearing at least one water-permeable silver halide .emulsion layer having an outer surface thereof provided `With a matte surface bylm'e'ans of nely divided particles of 'a highly porous siliceous material taken from the group consisting of porous silicon dioxide and 'porous magnesium silicate.

The highly vporous silice'ous materials just described should 'have apar-ticlesizeso that they fall within'the range of 2 to 10 microns in their greatest axial dimension andfadry bulk 'density of from 2 to 13 pounds per cubic `footofsuch ne particles. They also possessia'speciflc.gravity of about 2.0 to 2.32 and a refractive index .of.1.40 to 1.45. They may be disposed `throughout the colloid silver halide vemulsion:.layeror they may be uniformly distributed throughout a thin colloid layer which -is in intimate contact Awith the emulsion layer but are preferably `distributed in the silver halide layer.

The nely divided particles of the yhighlyporous siliceous materials may be dispersedv either in the colloidvsilver halide coating'solutionor `they may be dispersed in an aqueoussolution or dispersion of the colloid binding agent or-medium which is mixed with a colloid silver halide emulsion prior to coating the latter to ifo'rm fa y(light sensitive layer. Uniform dispersion of the! novel matting agents describedab'ove maybeaccomplished by passing a mixture of -the'agent andthe vbinding agent and also the silver halides desired through a'colloiddispersion mill or -homogenlzen vThe aqueous rcolloid containing the matting vagents must be maintained at ya temperature 2 persion is made in the colloid free from silver halides it should lbe brought to a temperature above the congealing point before it is added to a silver halide emulsion.

Representative photographic papers of this invention are shown in the accompanying drawing which forms a part of this specication. Referring now to the drawing:

Fig, l is a schematical cross-section of the photographic paper described in Example II, and

Fig. 2 is a schematicalcross-section'of the photographic paper of vExample IV.

The invention will be further illustrated but is not intended to be limited by the following examples.

Eample I A gelatin solution lto be used for the `dispersion of `a highly porous Vmagnesium silicate was prepared in the following manner:

Six grams of photographic -gelatin `were suspended in 200 cubic centimeters of distilled water at about F. and agitated occasionally. After a soaking period of one hour, the temperature was raised to F. for :thirty minutes. The gelatin dissolved completely.

Forty grams of porous magnesium' silicate (trade name--Magnesob havinga particle size within the 2 to 10 microns rangefaispecicgravity of 2.0 to 2.35, a refractive index of 1.40 to 1.45 and a dry lbulk density "of "8 `to 12 pounds per cubic foot were stirred into the -warm `gelatin solution and the mixture Vwas dispersed in a co1- loid dispersion mill-setatfa 0.002 inch'rotor-stator clearance and operating at a speed of 17,000 R. P. M. In passing through the colloid mill all clumps or aggregates of porous magnesium silicate particles existing in the gelatin solution were dispersed so that each individual porous magnesium silicate particle of the basic 2 to 10 micron size Was completely wetted by the gelatin suspending solution. Further, after passage through the colloid mill the porous magnesium silicate particles .not :only were uniformly dispersed in the gelatin :solution but exhibited no tendency to reformaggregatesfor clumpsiof :particles.

Twenty cubic centimeters of the magnesium silicate-gelatin matte suspension from Example I were added to'250 vcubic centimeters of molten gelatin silver chlorobromide emulsion and the latter was coated upon abar-yta coated photographic paper and dried. `Theemulsionsurface ofthe coated paper wasvuniformlyand completely delustered to a degree designated by the photographic paper industry as full-matte. The photographic paper of this example as stated above is illustrated in Fig. 1 of the drawing. Referring now to this ligure, a paper support I has `deposited thereon a baryta coating 2 which in turn carries a gelatin silver chlorobromide emulsion layer 3 which has intimately dispersed therethrough finely divided porous magnesium silicate particles.

Example III A porous magnesium silicate-gelatin matte suspension was prepared `by the same technique as employed in Example I. Six hundred grams of porous magnesium silicate having the characteristics given in Example I were dispersed in a gelatin solution composed of 90 grams of photographic gelatin dissolved in 3000 cubic centimeters of distilled water. A portion of the resulting dispersion was added to molten gelatin silver chlorobromide photographic emulsion in the proportion of 26 cubic centimeters of the dispersion for each liter of photographic emulsion. Fifteen hundred lineal feet of photographic paper base were coated with this delustered emulsion using production scale coating equipment. No sediment of magnesium silicate formed either in the coating pan or the emulsion receptacles used to continuously replenish the emulsion supply in the coating pan. The photographic paper coating was partially delustered to a degree termed semi-matte by the photographic paper industry.

Example IV A stock suspension of matting agent was prepared by stirring 150 grams of nely divided porous silicon dioxide, containing a fewlarge aggregates of particles, into 1000 cubic centimeters of 3% aqueous photographic gelatine solution. lThe suspension was ballmilled for a period of 4 hours until the particle size was from 2 to l0 microns.

Fifteen cubic centimeters of this stock matte suspension were added to 250 cubic centimeters of molten gelatin silver chloro-bromide photographic emulsion which was subsequently coated upon a photographic paper base and dried. The resulting product was uniformly delustered. The surface of the emulsion was smooth to the touch, having no rough irregular projections. The smoothness and character of the delustered surface is equal or superior to other commercial delusterants in all respects. The photographic paper of this example, as stated above, is illustrated in Fig. 2 of the drawing. Referring now to this figure, photographic paper base 4 carries a layer 5 of a gelatin silver chlorobromide emulsion which has intimately7 dispersed therethrough iinely divided porous silicon dioxide particles.

Example V Only very slight delusterant sediment formed in the coating pan and emulsion reservoirs during the coating period. The clarity and range of developed silver density on the resulting photographic paper was not impaired by the overlying delusterant or matte layer.

Various colloids can be used in place of gelatin as the binding agents for the silver halide grains and the novel matte-producing agents of this invention. Among such binding agents are albumin, agar-agar, hydrophilic acetals of polyvinyl alcohol and its lower alkyl ethers and esters, hydrophilic cellulose derivatives, e. g., cellulose acetate; etc.

The amount of the matte-producing agents may vary depending upon the particular colloid binding agent and the effect desired. In general from 0.005 to 0.6 parts of the porous siliceous particles should be used per part of colloid binding agent.

The porous silicon dioxides and magnesium silicates when used in accordance with this invention result in products which have numerous advantages. rIhe particles are white in appearance and have a density very close to that of fluid gelatin and hence do not tend to settle but on the contrary form stable suspensions or dispersions in colloid solutions. They do not separate out in the coated layers and thus the layers have good uniformity, especially near the surface.

A further advantage of the use of the porous silicon dioxides and magnesium silicates is that much less milling time is necessary to reduce the particle size of outsize particles to the desired limits and to break up any aggregates. The highly porous siliceous materials just described result in a greater degree of transparency of the delusterant so that the photographic likeness of an object can be reproduced on the photographic paper with greater clarity and with a greater range of reduced silver density. They may be successfully used in thin anti-abrasion layers without any subsequent opaquing or graying effeet on the gelatin silver halide under-layer. Dense silica particles do not produce similar results.

As many widely diiferent embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by the claims.

What is claimed is:

1. A photographic element comprising a support bearing a gelatino silver halide emulsion layer containing finely divided particles of porous magnesium silicate having a particle size of 2 to 10 microns, a dry bulk density of 2 to 13 pounds per cubic foot and a specific gravity of 2.00 to 2.35, said particles being present in an amount of 0.005 to 0.6 part per part of gelatin by weight.

2. A photograph element comprising a paper support bearing a gelatine silver halide layer containing nely divided particles of a highly porous magnesium silicate having a particle size of 2 to 10 microns, a dry bulk density of 2 to 13 pounds per cubic foot and a speciiic gravity of 2.00 to 2.35, said particles being present in an amount of 0.005 to 0.6 part per part of gelatin by Weight.

3. A photographic element comprising a paper support bearing a Water-permeable silver halide emulsion layer on which is deposited a thin waterpermeable colloid layer containing finely divided particles of a highly porous magnesium silicate having a particle size of 2 to 10 microns, a dry bulk density of 2 to 13 pounds per cubic foot and a specific gravity of 2.00 to 2.35, said particles .5 being present in an amount of 0.005 to 0.6 part per part of colloid by weight.

4. A photographic element comprising a paper support bearing a gelatin silver halide emulsion layer on which is deposited a thin gelatin colloid layer containing nely divided particles of a highly porous magnesium silicate having a particle size of 2 to 10 microns, a dry bulk density of 2 to 13 pounds per cubic foot and a specic gravity of 2.00 to 2.35, said particles being present in an amount of 0.005 to 0.6 part per part of gelatin by weight.

5. A photographic element comprising a flexible sheet support and at least one gelatin-containing layer on the support, said element having lightsensitive silver halide grains dispersed in the gelatin binding agent and nely divided particles of yporous magnesium silicate having a particle size from 2 to 10 microns, a dry bulk density of 2 to 13 pounds per cubic foot and a specific gravity of 2.00 to 2.35 dispersed in the gelatin binding agent, said particles being present in an amount of 0.005 to 0.6 parts per part of gelatin and in intimate association with the silver halide grains and in the outer stratum of gelatin.

LAWRENCE J. WEBSTER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,989,879 Murck Feb. 5, 1935 2,322,037 Lindquist June 15, 1943 2,384,093 Holmen et al Sept. 4, 1945 2,433,515 Jahoda Dec. 30, 1947 FOREIGN PATENTS Number Country Date 3,736 Great Britain 1900

Claims (1)

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT BEARING A GELATINO SILVER HALIDE EMULSION LAYER CONTAINING FINELY DIVIDED PARTICLES OF POROUS MAGNESIUM SILICATE HAVING A PARTICLE SIZE OF 2 TO 10 MICRONS, A DRY BULK DENSITY OF 2 TO 13 POUNDS PER CUBIC FOOT AND A SPECIFIC GRAVITY OF 2.00 TO 2.35, SAID PARTICLES BEING PRESENT IN AN AMOUNT OF 0.005 TO 0.6 PART PER PART OF GELATIN BY WEIGHT.

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