Process for the preparation of high chloride tabular grain emulsions (iv)

Claim 2

A process of preparing a radiation sensitive high aspect ratio tabular grain emulsion, wherein tabular grains of less than 0.3 μm in thickness and an average aspect ratio of greater than 8:1 account for greater than 50 percent of the total grain projected area, said tabular grains containing at least 50 mole percent chloride, based on silver, comprising introducing silver ion into a gelatino-peptizer dispersing medium containing a stoichiometric excess of chloride ions with respect to the silver ions further characterized by a chloride ion concentration of less than 0.5 molar, a pH of from 4.6 to 9.0, and a triaminopyrimidine grain growth modifier containing mutually independent 4, 5 and 6 ring position amino substituents, the 4 and 6 ring position substituents being hydroamino substituents.

Claim 3

A process according to claim 1 further characterized in that the concentration of chloride ion is less than 0.2 molar.

Claim 4

A process according to claim 1 further characterized in that the pH is in the range of from 5.0 to 8.

Claim 5

A process according to claim 1 further characterized in that the triaminopyrimidine grain growth modifier satisfies the formula: ##STR10## where N 4 , N 5 and N 6 are independent amino moieties.

Claim 6

A process according to claim 4 further characterized in that N 4 and N 6 represent primary or secondary amino groups and N 5 represents a primary, secondary or tertiary amino group.

Claim 7

A process according to claim 5 further characterized in that the triaminopyrimidine satisfies the formula: ##STR11## where R i is independently in each occurrence hydrogen or alkyl of from 1 to 7 carbon atoms.

Claim 8

A process according to claim 6 further characterized in that R i is in each occurrence hydrogen.

Claim 9

A process according to claim 1 further characterized in that the 4,6-di(hydroamino)-5-aminopyrimidine is selected from among 4,5,6-triaminopyrimidine; 5,6-diamino-4-(N-methylamino)pyrimidine; 4,5,6-tri(N-methylamino)pyrimidine; 4,6-diamino-5-(N,N-dimethylamino)pyrimidine; and 4,6-diamino-5-(N-hexylamino)pyrimidine.

Claim 10

A process according to claim 1 further characterized in that the triaminopyrimidine is present in at least a 2×10 -4 molar concentration.

Claim 11

A process according to claim 1 further characterized in that the tabular grains contain less than 2 mole percent iodide, based on silver.

Claim 12

A process according to claim 1 further characterized in that the tabular grains consist essentially of silver chloride.

Claim 13

A process according to claim 1 further characterized in that during tabular grain growth following twinning at least one grain growth modifier is present selected from the group consisting of (a) iodide ions; (b) thiocyanate ions; (c) a compound of the formula: ##STR12## wherein Z is C or N; R 1 , R 2 and R 3 , which may be the same or different, are H or alkyl of 1 to 5 carbon atoms; when Z is C, R 2 and R 3 when taken together can be --CR 4 ═CR 5 -- or --CR 4 ═N--, wherein R 4 and R 5 , which may be the same or different are H or alkyl of 1 to 5 carbon atoms, with the proviso that when R 2 and R 3 taken together form the --CR 4 ═N-- linkage, --CR 4 ═ must be joined to Z; (d) a compound of the formula: ##STR13## where Z 2 is --C(R 2 )═ or --N═; Z 3 is --C(R 3 )═ or --N═; Z 4 is --C(R 4 )═ or --N═; Z 5 is --C(R 5 )═ or --N═; Z 6 is --C(R 6 )═ or --N═; with the proviso that no more than one of Z 4 , Z 5 and Z 6 is --N═; R 2 is H, NH 2 or CH 3 ; R 3 , R 4 and R 5 are independently selected, R 3 and R 5 being hydrogen, hydroxy, halogen, amino or hydrocarbon and R 4 being hydrogen, halogen or hydrocarbon, each hydrocarbon moiety containing from 1 to 7 carbon atoms; and R 6 is H or NH 2 ; and (e) a compound of the formula: ##STR14## where Z 8 is --C(R 8 )═ or --N═; R 8 is H, NH 2 or CH 3 ; and R 1 is hydrogen or a hydrocarbon containing from 1 to 7 carbon atoms.

Claim 14

A process of preparing a radiation sensitive high aspect ratio tabular grain emulsion, wherein tabular grains of less than 0.2 μm in thickness and an average aspect ration of greater than 8:1 account for greater than 70 percent of the total grain projected area, said tabular grains containing at least 50 mole percent chloride and less than 2 mole percent iodide, based on silver, comprising introducing silver ion into a gelatino-peptizer dispersing medium containing a stoichiometric excess of chloride ions with respect to the silver ions further characterized by a chloride ion concentration of less than 0.2 molar, a pH of from 5.0 to 8, and 4,5,6-triaminopyrimidine in a concentration of from 7×10 -4 to 0.01 molar.

Claim 15

A process of preparing a radiation sensitive high aspect ratio tabular grain emulsion, wherein tabular grains of less than 0.2 μm in thickness and an average aspect ration of greater than 8:1 account for greater than 70 percent of the total grain projected area, said tabular grains containing at least 50 mole percent chloride and less than 2 mole percent iodide, based on silver, comprising introducing silver ion into a gelatino-peptizer dispersing medium containing a stoichiometric excess of chloride ions with respect to the silver ions further characterized by a chloride ion concentration of less than 0.2 molar, a pH of from 5.0 to 8, and 4,5,6-triaminopyrimidine in a concentration of from 7×10 -4 to 0.01 molar.

Claim 16

A process according to claim 13 further characterized in that the 4,5,6-triaminopyrimidine is present during twin plane formation in the tabular grains.