Water-based coloring composition, coloring method, pigment dispersion liquid, and metal pigment producing method

A pigment dispersion liquid comprising:

• a metal pigment;
• water;
• and
• an organic solvent, wherein
• the metal pigment is surface-treated with a first surface treatment agent and a second surface treatment agent,
• the first surface treatment agent contains a phosphonic-acid-based compound denoted by Formula (1) below or a phosphoric-acid-based compound denoted by Formula (2) below,
• the second surface treatment agent contains a phosphonic-acid-based compound denoted by Formula (3) below or a phosphoric-acid-based compound denoted by Formula (4) below,
• (R1)PO(OH)2 (1)
• (in Formula (1), R1 represents a hydrocarbon group having a carbon number of 12 or more in which a hydrogen atom is not limited to being substituted with a substituent)
• (R2O)aPO(OH)3-a (2)
• (in Formula (2), R2 represents independently a hydrocarbon group having a carbon number of 12 or more in which a hydrogen atom is not limited to being substituted with a substituent, and a is an integer of 1 or 2)
• (R3)PO(OH)2 (3)
• (in Formula (3), R3 represents a hydrocarbon group having a carbon number of 4 or more in which a hydrogen atom is not limited to being substituted with a substituent)
• (R4O)bPO(OH)3-b (4)
• (in Formula (4), R4 represents independently a hydrocarbon group having a carbon number of 4 or more in which a hydrogen atom is not limited to being substituted with a substituent, and b is an integer of 1 or 2), and
• the carbon number of R1 or R2 of the first surface treatment agent is higher than the carbon number of R3 or R4 of the second surface treatment agent, wherein
• a content of the first surface treatment agent ranges from 0.05% by mass to 10% by mass, relative to a total amount of the coloring composition;
• and wherein
• a content of the second surface treatment agent ranges from 0.05% by mass to 10% by mass, relative to a total amount of the coloring composition.

A metal pigment producing method comprising:

• a first surface treatment step of surface-treating a metal pigment with a first surface treatment agent;
• and
• a second surface treatment step of surface-treating the metal pigment surface-treated with the first surface treatment agent with a second surface treatment agent, wherein
• the first surface treatment agent contains a phosphonic-acid-based compound denoted by Formula (1) below or a phosphoric-acid-based compound denoted by Formula (2) below,
• the second surface treatment agent contains a phosphonic-acid-based compound denoted by Formula (3) below or a phosphoric-acid-based compound denoted by Formula (4) below,
• (R1)PO(OH)2 (1)
• (in Formula (1), R1 represents a hydrocarbon group having a carbon number of 12 or more in which a hydrogen atom is not limited to being substituted with a substituent)
• (R2O)aPO(OH)3-a (2)
• (in Formula (2), R2 represents independently a hydrocarbon group having a carbon number of 12 or more in which a hydrogen atom is not limited to being substituted with a substituent, and a is an integer of 1 or 2)
• (R3)PO(OH)2 (3)
• (in Formula (3), R3 represents a hydrocarbon group having a carbon number of 4 or more in which a hydrogen atom is not limited to being substituted with a substituent)
• (R4O)bPO(OH)3-b (4)
• (in Formula (4), R4 represents independently a hydrocarbon group having a carbon number of 4 or more in which a hydrogen atom is not limited to being substituted with a substituent, and b is an integer of 1 or 2), and
• the carbon number of R1 or R2 of the first surface treatment agent is higher than the carbon number of R3 or R4 of the second surface treatment agent, wherein
• a content of the first surface treatment agent ranges from 0.05% by mass to 10% by mass, relative to a total amount of the coloring composition;
• and wherein
• a content of the second surface treatment agent ranges from 0.05% by mass to 10% by mass, relative to a total amount of the coloring composition.