Color photothermographic element containing a mixture of blocked developers for balancing imaging layers

A photothermographic color element comprising at least three light-sensitive units that have their individual sensitivities in different wavelength regions comprising a silver halide imaging layer having associated therewith a first imaging layer or color unit, referred to as Layer 1 or Color Unit 1, having a mixture of at least two blocked developing agents comprising Blocked Developer A and Blocked Developer B and a second imaging layer or color unit, referred to as Layer 2 or Color Unit 2, having at least one blocked developer C, wherein blocked developers A, B, and C are independently represented by the following Structure:

• DEV—(LINK 1)l—(TIME)m—(LINK 2)n—M
• wherein:
• DBV is a silver halide color developing agent;
• LINK 1 and LINK 2 are linking groups,
• TIME is a timing group;
• l is 0 or 1;
• m is 0, 1, or 2;
• n is 0 or 1;
• l+n is 1 or 2;
• M is a blocking group or M is:
• —M′—(LINK 2 )n—(TIME)m—(LINK 1)1—l DEV
• wherein M′ is blocking group for a second developing agent DEV;
• and
• wherein LINK I and LINK 2 have the following structure
• wherein
• X represents carbon or sulfur;
• Y represents oxygen, sulfur or N—R1, where R1 is substituted or unsubstituted alkyl or substituted or unsubstituted aryl;
• p is 1 or 2;
• Z represents carbon, oxygen or sulfur;
• r is 0 or 1;
• with the proviso that when X is carbon, both p and r are 1, when X is sulfur, Y is oxygen, p is 2 and r is 0;
• # denotes the bond to PUG (for LINK 1) or TIME (for LINK 2):
• $ denotes the bond to TIME (for LINK 1) or T(t) substituted carbon (for LINK 2);
• and
• wherein the onset temperature of Developer B is less than the onset temperature of Developer A, the onset temperature of Developer B is in the range of 110 to 160° C. and the onset temperature of Developer A is 130 to 170° C. and the difference in the onset temperatures of the two developing agents are 5 to 50° C., and
• wherein the Gamma Ratio at the process temperature of the Gamma in Layer 1 to the Gamma in Layer 2 is between 0.8 and 1.2 and wherein this Gamma Ratio is at least 10% closer to 1.0 than if only one of Blocked Developers A, B, and C are independently used in each of Layer 1 and Layer 2;
• and/or
• wherein the Dmin Ratio at the process temperature of the Dmin in Layer 1 to the Dmin in Layer 2 is between 0.8 and 1.2, and wherein this Dmin ratio is at least 10% closer to 1.0 than if only one of Blocked Developers A, B, and C are independently used in each of Layer 1 and Layer 2;
• and/or
• wherein the Latitude Ratio at the process temperature of the Latitude in Layer 1 to the Latitude in Layer 2 is between 0.8 and 1.2 and wherein this Latitude Ratio is at least 10% closer to 1.0 than if only one of Blocked Developers A, B, and C are independently used in each of Layer 1 and Layer 2,
• wherein the Blocked Developer A or both Blocked Developer A and B is of the following structure:
• wherein:
• DEV is a developing agent;
• LINK is a linking group;
• TIME is a timing group;
• n is 0, 1, or 2;
• t is 0, 1, or 2, and when t is not 2, the necessary number of hydrogens (2-t) are present in the structure;
• C* is tetrahedral (sp3 hybridized) carbon;
• p is 0 or 1;
• q is 0 or 1;
• w is 0 or 1;
• p+q=1 and when p is 1, q and w are both 0;
• when q is 1, then w is 1;
• R12 is hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, aryl or heterocyclic group or R12 can combine with W to form a ring;
• T is independently selected from a substituted or unsubstituted (referring to the following T groups) alkyl group, cycloalkyl group, aryl, or heterocyclic group, an inorganic monovalent electron withdrawing group, or an inorganic divalent electron withdrawing group capped with at least one C1 to C10 organic group (either an R13 or an R13 and R14 group);
• or T is joined with W or R12 to form a ring;
• or two T groups can combine to form a ring;
• D is a first activating group selected from substituted or unsubstituted (referring to the following D groups) heteroaromatic group or aryl group or monovalent electron withdrawing group, wherein the heteroaromatic can optionally form a ring with T or R12;
• X is a second activating group and is a divalent electron withdrawing group;
• W is W′ or a group represented by the following structure:
• wherein W′ is independently selected from a substituted or unsubstituted (referring to the following W′ groups) alkyl , cycloalkyl, aryl or heterocyclic group;
• and wherein W′ in combination on with T or R12 can form a ring;
• R13, R14, R15, ad R16 can independently be selected from substituted or unsubstituted alkyl, aryl, or heterocyclic group;
• and
• any two members of the following set:
• R12, T, and either D or W, that are not directly linked may be joined to form a ring, provided that creation of the ring will not interfere with the functioning of the blocking group.