Patent GB-942932-A (GB)
Title: Photographic silver halide emulsions of increased sensitivity
IPC: C08G75/045
Filed: 1959-12-11
Abstract: The Specification describes linear polymers having a molecular weight of at least 250 and containing thioether and/or ternary sulphonium salt groups in the linear chain, but being free from disulphide linkages or mercapto substituents. The polymers may comprise units of the general formula I: -R-S-wherein R is an alkylene group of 2 to 20 carbon atoms interrupted by one or more single S or O atoms, such as the group -(CH2)2-O(CH2)2-, -(CH2)3 -O-(CH2)3- or -(CH2)2-O-(CH2)2-O-(CH2)2-.  These may be prepared by refluxing a dihalide Cl-R-Cl with sodium sulphide in aqueous ethanol. The polymer with the first value of R is also prepared by heating a mixture of bis(2-mercaptoethyl) ether and bis(2-chloroethyl) ether with sodium carbonate in aqueous ethanol.  Other polymers may comprise recurring units of the general formula IV: -CH2 - NH - R1 - (NH - R2)p - NH - CH2 - S - R3 - (O - R4)m - S - where R1, R2, R3 and R4 are alkylene groups containing 2 to 20 carbon atoms, and p and m are 0 to 4. These are prepared by condensing one molecular proportion of polyamine NH2-R1-(NH-R2)p-NH2 with two molecular proportions of formaldehyde and one molecular proportion of a dithiol HS-R3-(OR4)m -SH. The diamine may be ethylene diamine or diethylenetriamine and the dithiol may be bis(2-mercaptoethyl)ethe or 1, 2-bis(2-mercaptoethoxy)ethane. A further class of polymers has recurring units of the general formula V: <FORM:0942932/C2/1> where the symbols are as defined above. These are prepared by reacting a dithiol HS-R3-(O-R4)m-SH and a dialdehyde CHO-R1-(O-R2)p-CHO in the presence of ammonia. In examples, bis(2-mercapto-ethyl) ether or 1, 10-dimercapto-decane is mixed with succindialdehyde and left at room temperature. The product is then mixed with concentrated ammonium hydroxide.  The succindialdehyde may be replaced by maleic dialdehyde. The thiopolymers may have some or all of their thioether groups converted to ternary sulphonium salt groups by reaction with dimethyl sulphate, diethyl sulphate, methyl benzene sulphonate or methyl p-toluene sulphonate. Where -NH- groups are present in the polymer chain, these may be acylated, for example with acetic anhydride.  Specifications 25,246/1911 541,589, 719,920, 791,219, 942,933, 942,934, 942,935, 942,936, 942,938, U.S.A.  Specifications 2,017,811, 2,347,182, 2,598,407 and 2,948,614 are referred to.ALSO:The Specification describes linear polymers having a molecular weight of at least 250 and containing thioether and/or ternary sulphonium salt groups in the linear chain, but being free from disulphide linkages or mercapto substituents. The polymers may comprise units of the general formula I: -R-S- wherein R is an alkylene group of 2 to 20 carbon atoms interrupted by one or more single S or O atoms, such as the group -(CH2)2-O-(CH2)2-, -(CH2)3 -O-(CH2)3- or -(CH2)2 -O-(CH2)2 -O-(CH2)2-. These may be prepared by refluxing a dihalide Cl-R-Cl with sodium sulphide in aqueous ethanol. The polymer with the first value of R is also prepared by heating a mixture of bis (2-mercaptoethyl) ether and bis (2-chloroethyl) ether with sodium carbonate in aqueous ethanol. Other polymers may comprise recurring units of the general formula IV:- <FORM:0942932/C3/1> where R1, R2, R3 and R4 are alkylene group containing 2 to 20 carbon atoms, and p and m are 0 to 4. These are prepared by condensing one molecular proportion of diamine NH2-R1-(NH-R2)p-NH2 with two molecular proportions of formaldehyde and one molecular proportion of a dithiol HS-R3 -(OR4)m-SH.  The diamine may be ethylene diamine or diethylenetriamine and the dithiol may be bis (2-mercaptoethyl) ether or 1,2,-bis (2-mercaptoethoxy) ethane. A further class of polymers has recurring units of the general formula V:- <FORM:0942932/C3/2> where the symbols are as defined above. These are prepared by reacting a dithiol HS-R3-(O-R4)m-SH and a dialdehyde CHO-R1-(O-R2)p-CHO in the presence of ammonia. In examples, bis (2-mercaptoethyl) ether or 1,10-dimercapto-decane is mixed with succindialdehyde and left at room temperature. The product is then mixed with concentrated ammonium hydroxide.  The succindialdehyde may be replaced by maleic dialdehyde. The thiopolymers may have some or all of their thioether groups converted to ternary sulphonium salt groups by reaction with dimethyl sulphate, diethyl sulphate, methyl benzene sulphonate or methyl p-toluene sulphonate. Where -NH- groups are present in the polymer chain, these may be acylated for example with acetic anhydride.  Specifications 541,589, 719,920, 791,219, 942,933, 942,934, 942,935, 942,936, 942,938 and U.S.A. Specifications 2,017,811, 2,347,182, 2,598,407, 2,948,614 are referred to.