# US 5,350,652 A · Method for optimizing tabular grain population of silver halide photographic emulsions

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- Number: US 5,350,652 A
- Document ID: US5350652A
- Status: Granted
- Kind: A
- Application number: 08/127,383
- Filed: 1993-09-24
- Granted: 1994-09-27
- Earliest claimed: 1993-09-24
- Assignees: Eastman Kodak Company
- Inventors: Michael G. Antoniades
- Web page: https://patentgrep.com/patent/US5350652A

## CPC

- G03C 1/015: Apparatus or processes for the preparation of emulsions (coating, drying G03C1/74 {; G03C1/07 takes precedence; special processes for tabular grains G03C1/0051})
- G03C 1/0051: {Tabular grain emulsions}
- G03C: PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES (for photomechanical purposes G03F); PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY (photographic processes characterised by the use or manipulation of apparatus classifiable per se in subclass G03B, see G03B; photomechanical production of textured or patterned surfaces G03F; electrophotography, magnetography G03G)

## Abstract

The invention provides a method of measuring to control silver halide grain formation during nucleation and ripening comprising combining a source of silver ions and a source of halide ions to form a suspension of nucleated particles, removing a portion of said suspension, measuring turbidity of said portion, determining floc size from the turbidity measurement, determining the difference between floc size and individual silver halide nuclei size.

## Claims

### Claim 1

A method of measuring to control silver halide grain formation during nucleation and ripening comprising
combining a source of silver ions and a source of halide ions to form a suspension of nucleated particles,
removing a portion of said suspension,
treating the removed portion with a defloculant to eliminate floculation, separate flocs into individual nuclei, and allow measurement of nuclei size,
measuring turbidity of said portion,
determining floc size from the turbidity measurement, and
determining the difference between floc size and individual silver halide nuclei size, wherein said difference between floc size and nuclei size is greater than 20 nm to give a high population of tabular grains.

### Claim 2 (depends on 1)

The method of claim 1 wherein after measuring turbidity, said portion is returned to said suspension.

### Claim 3 (depends on 1)

The method of claim 1 wherein said halide ions comprise bromide.

### Claim 4 (depends on 1)

The method of claim 1 wherein said determination of said floc size is made by Rayleigh scattering equation from measured suspension density.

### Claim 5 (depends on 1)

The method of claim 1 wherein said difference is greater than 50 nm.

### Claim 6 (depends on 1)

The method claim 1 wherein said combining and measuring is carried out as part of a continuous manufacturing process.

### Claim 7 (depends on 1)

The method of claim 1 wherein said difference between floc size and nuclei size is greater than 20 nm and the nucleated particles are grown to form tabular grains.

### Claim 8

A method of measuring to control silver halide grain formation during nucleation and ripening comprising
combining a source of silver ions and a source of halide ions to form a suspension of nucleated particles,
removing a portion of said suspension,
treating the removed portion with a defloculant to eliminate floculation, separate flocs into individual nuclei, and allow measurement of nuclei size,
measuring turbidity of said portion,
determining floc size from the turbidity measurement, and
determining the difference between floc size and individual silver halide nuclei size, wherein said difference between floc size and nuclei size is greater than 100 nm to give a high population of tabular grains.

### Claim 9 (depends on 8)

The method of claim 8 wherein after measuring turbidity, said portion is returned to said suspension.

### Claim 10 (depends on 8)

The method of claim 8 wherein said determination of said floc size is made by Rayleigh scattering equation from measured suspension density.

### Claim 11 (depends on 8)

The method of claim 8 wherein said combining and measuring is carried out as part of a continuous manufacturing process.

### Claim 12 (depends on 8)

The method of claim 8 wherein said difference between floc size and nuclei size is greater than 100 nm and the nucleated particles are grown to form tabular grains.