Water-soluble naphthalocyanine coloring matter and water-based ink containing the same

A water-soluble naphthalocyanine coloring matter represented by the following formula (1) or a salt thereof:

• wherein,
• M represents a hydrogen atom, a metal atom, a metal oxide, a metal hydroxide or a metal halide,
• X represents a carbonyl group or a sulfonyl group,
• W1 and W4 are hydrogen atoms,
• at least either W2 or W3 is a group represented by the following formula (2):
• wherein, L represents an unsubstituted alkylene group having a total carbon number of C2 to C6, and R represents an ionic hydrophilic group, respectively;
• and the rest of W2 or W3 is a hydrogen atom,
• n represents an integer number of 1 to 24, respectively.

A water-soluble naphthalocyanine coloring matter represented by the following formula (1) or a salt thereof:

• wherein,
• M represents a hydrogen atom, a metal atom, a metal oxide, a metal hydroxide or a metal halide,
• X represents a carbonyl group or a sulfonyl group,
• W1, W3 and W4 are hydrogen atoms,
• W2 is the following formula (2):
• wherein, L represents linear C2 to C6 alkylene and R represents a sulfo group, and
• n represents an integer number of 5 to 12.

A near-infrared ray absorbent comprising a water-soluble naphthalocyanine coloring matter represented by the following formula (1) or a salt thereof:

• wherein,
• M represents a hydrogen atom, a metal atom, a metal oxide, a metal hydroxide or a metal halide,
• X represents a carbonyl group or a sulfonyl group,
• W1, W3 and W4 are hydrogen atoms,
• W2 is the following formula (2):
• wherein, L represents linear C2 to C6 alkylene, and R represents a sulfo group, and n represents an integer number of 5 to 12.