Silver halide precipitation process with deletion of materials

Claim 2

In a process comprising forming a radiation-sensitive silver halide dispersion by reacting silver and halide salts in solution, wherein the silver and halide salts are reacted to form silver halide grain nuclei in the presence of a dispersing medium and silver halide grain growth is allowed to proceed in a reaction vessel in which the silver halide grain nuclei and the dispersing medium are present, the improvement comprising, while increasing the silver halide present in the dispersing medium during silver halide grain growth, reducing the volume of the dispersion by separating a portion of the dispersing medium while retaining the silver halide grains within the dispersion remaining.

Claim 3

In a double-jet batch process comprising forming a radiation-sensitive silver halide dispersion by reacting a silver salt solution and a halide salt solution within a dispersing medium to achieve silver halide grain nucleation followed by silver halide grain growth, wherein during silver halide grain growth the silver and halide salts are concurrently run into a reaction vessel containing the dispersing medium, the improvement comprising, while running the silver and halide salt solutions and during silver halide grain growth, withdrawing a portion of the dispersion from the reaction vessel, reducing the volume of the withdrawn dispersion by separating a portion of the dispersing medium while retaining the silver halide grains within the remaining withdrawn dispersion, and returning the remaining withdrawn dispersion to the reaction vessel.

Claim 4

In a double-jet batch process comprising forming a radiation-sensitive silver halide dispersion by reacting a silver salt solution and a halide salt solution within a dispersing medium to achieve silver halide grain nucleation followed by silver halide grain growth, wherein during silver halide grain growth the silver and halide salts are concurrently run into a reaction vessel containing the dispersing medium, the improvement comprising, while running the silver and halide salt solutions and during silver halide grain growth, withdrawing a portion of the dispersion from the reaction vessel, reducing the volume of the withdrawn dispersion by separating a portion of the dispersing medium while retaining the silver halide grains within the remaining withdrawn dispersion, and returning the remaining withdrawn dispersion to the reaction vessel.

Claim 5

An improved process according to claim 1 or 2 in which the dispersing medium contains a peptizer.

Claim 6

An improved process according to claim 3 in which the dispersing medium contains a hydrophilic colloid peptizer.

Claim 7

An improved process according to claim 1 or 2 in which the dispersing medium is substantially free of a hydrophilic colloid peptizer and the concentration of soluble salts present in the dispersion is maintained below 0.1 mole per liter.

Claim 8

An improved process according to claim 1 or 2 in which the silver halide grains formed in the silver halide dispersion are substantially monodispersed.

Claim 9

An improved process according to claim 1 or 2 in which the volume of the dispersion is reduced using an ultrafiltration unit containing a semipermeable membrane.

Claim 10

An improved process according to claim 1 or 2 in which a silver halide ripening agent is present in the reaction vessel during introduction of the silver and halide salt solutions.

Claim 11

An improved process according to claim 1 or 2 in which additional dispersing medium is separately run into the reaction vessel concurrently with the silver and halide salt solutions.

Claim 12

An improved process according to claim 1 or 2 in which the volume of the silver halide dispersion in the reaction vessel is maintained substantially invariant while at least a portion of the silver and halide salts are being introduced.

Claim 13

In a double-jet batch process of preparing a silver halide dispersion in the absence of a hydrophilic colloid peptizer comprising forming a dispersion of radiation-sensitive silver halide grains and a soluble salt reaction product by reacting water soluble silver and halide salts within a dispersing medium to achieve silver halide grain nucleation followed by silver halide grain growth, wherein during silver halide grain growth the silver and halide salts are separately introduced as aqueous solutions through first and second jets into a reaction vessel containing the dispersing medium, the improvement of protecting the silver halide grains from flocculation comprising, while running the first and second jets and during silver halide grain growth, separately introducing into the reaction vessel through a third jet a less than 0.01 molar aqueous halide salt solution, withdrawing a portion of the dispersion from the reaction vessel, passing the withdrawn portion of the dispersion through an ultrafiltration unit containing a semipermeable membrane, thereby separating a portion of the dispersing medium and soluble salt reaction product from the silver halide grains within the dispersion remaining, and returning the remaining withdrawn dispersion to the reaction vessel.

Claim 14

In a double-jet batch process of preparing a silver halide dispersion in the absence of a hydrophilic colloid peptizer comprising forming a dispersion of radiation-sensitive silver halide grains and a soluble salt reaction product by reacting water soluble silver and halide salts within a dispersing medium to achieve silver halide grain nucleation followed by silver halide grain growth, wherein during silver halide grain growth the silver and halide salts are separately introduced as aqueous solutions through first and second jets into a reaction vessel containing the dispersing medium, the improvement of protecting the silver halide grains from flocculation comprising, while running the first and second jets and during silver halide grain growth, separately introducing into the reaction vessel through a third jet a less than 0.01 molar aqueous halide salt solution, withdrawing a portion of the dispersion from the reaction vessel, passing the withdrawn portion of the dispersion through an ultrafiltration unit containing a semipermeable membrane, thereby separating a portion of the dispersing medium and soluble salt reaction product from the silver halide grains within the dispersion remaining, and returning the remaining withdrawn dispersion to the reaction vessel.

Claim 15

An improved process according to claim 11 in which withdrawal of soluble salt reaction product maintains its concentration in the reaction vessel at less than 0.1 mole per liter.

Claim 16

An improved process according to claim 12 in which withdrawal of soluble salt reaction product maintains its concentration in the reaction vessel at less than 0.01 mole per liter.

Claim 17

An improved process according to claim 11 in which the flow rate to the third jet is from 10 to 30 times the combined flow rates to the first and second jets.

Claim 18

An improved process according to claim 11 in which delivery from the first and second jets is interrupted while the third jet continues to deliver the aqueous halide salt solution to the reaction vessel.

Claim 19

In a process comprising forming a radiation-sensitive silver halide dispersion by reacting silver and halide salts in solution, wherein the silver and halide salts are reacted to form silver halide grain nuclei in the presence of a dispersing medium and silver halide grain growth is allowed to proceed in a reaction vessel in which the silver halide grain nuclei and the dispersing medium are present, the improvement comprising during silver halide grain growth separating a portion of the dispersing medium while retaining the silver halide grains within the dispersion remaining.

Claim 20

In a process comprising forming a radiation-sensitive silver halide dispersion by reacting silver and halide salts in solution, wherein the silver and halide salts are reacted to form silver halide grain nuclei in the presence of a dispersing medium and silver halide grain growth is allowed to proceed in a reaction vessel in which the silver halide grain nuclei and the dispersing medium are present, the improvement comprising during silver halide grain growth separating a portion of the dispersing medium while retaining the silver halide grains within the dispersion remaining.

Claim 21

In a double-jet batch process of preparing a photographic silver halide emulsion comprising forming a silver halide emulsion by reacting aqueous silver and halide salts within a dispersing medium to achieve silver halide nucleation followed by silver halide grain growth, wherein at least during silver halide grain growth the dispersing medium is present in a reaction vessel, a hydrophilic colloid peptizer is present in the dispersing medium, and the silver and halide salt solutions are concurrently run into the reaction vessel containing the dispersing medium, the improvement comprising withdrawing a portion of the silver halide emulsion from the reaction vessel during silver halide grain growth, passing the withdrawn portion of the silver halide emulsion through an ultrafiltration unit containing a semipermeable membrane to separate a portion of the dispersing medium from the silver halide grains and hydrophilic colloid and thereby reduce the volume of the silver halide emulsion withdrawn, and returning the withdrawn emulsion, reduced in volume, to the reaction vessel.

Claim 22

In a double-jet batch process of preparing a photographic silver halide emulsion comprising forming a silver halide emulsion by reacting aqueous silver and halide salts within a dispersing medium to achieve silver halide nucleation followed by silver halide grain growth, wherein at least during silver halide grain growth the dispersing medium is present in a reaction vessel, a hydrophilic colloid peptizer is present in the dispersing medium, and the silver and halide salt solutions are concurrently run into the reaction vessel containing the dispersing medium, the improvement comprising withdrawing a portion of the silver halide emulsion from the reaction vessel during silver halide grain growth, passing the withdrawn portion of the silver halide emulsion through an ultrafiltration unit containing a semipermeable membrane to separate a portion of the dispersing medium from the silver halide grains and hydrophilic colloid and thereby reduce the volume of the silver halide emulsion withdrawn, and returning the withdrawn emulsion, reduced in volume, to the reaction vessel.

Claim 23

An improved process according to claim 11, 16, or 17 in which the silver halide withdrawn from the reaction vessel is absent for less than 10 percent of the total run time.

Claim 24

An improved process according to claim 11, 16, or 17 in which the silver halide withdrawn from the reaction vessel is less than 50 percent of the total silver halide present in the reaction vessel.

Claim 25

An improved process according to claim 19 in which the silver halide withdrawn is less than 25 percent of the total silver halide present in the reaction vessel.

Claim 26

An improved process according to claim 11, 16, or 17 in which the total dispersing medium separated comprises from 10 to 90 percent of the total volume of materials introduced into the reaction vessel.

Claim 27

An improved process according to claim 21 in which the total dispersing medium separated comprises from 50 to 90 percent of the total volume of materials introduced into the reaction vessel.

Claim 28

An improved process according to claim 16 or 18 in which additional dispersing medium is run into the reaction vessel after introduction of silver and halide salt solutions has been completed.

Claim 29

An improved process according to claim 11, 16, or 17 in which a thioether or thiocyanate ripening agent is present in the reaction vessel during addition of the silver and halide salt solutions.

Claim 30

An improved process according to claim 11, 16, or 17 in which the semipermeable membrane is chosen from among polysulfone, cellulose acetate, and poly(vinyl acetate) membranes.

Claim 31

An improved process according to claim 11, 16, or 17 in which the semipermeable membrane has a molecular weight cutoff of from 500 to 50,000.

Claim 32

An improved process according to claim 12, 16, or 17 in which the silver halide formed is monodispersed.