JP2019119890A5 - - Google Patents

Claims (12)

A method for producing an aqueous pigment dispersion, which comprises the following steps 1 and 2.
Step 1: A pigment mixture containing a pigment, a (meth) acrylic resin (A) having an acid group, and a polyester resin (B) is subjected to shear stress and dispersed to obtain a dispersion. Step 2 : A step of cross-linking the dispersion obtained in step 1 with a cross-linking agent (C). The amount of the cross-linking agent (C) used in step 2 is the ratio of the molar equivalents of the crosslinkable functional groups of the cross-linking agent (C) to the molar equivalents of the acid groups of the (meth) acrylic resin (A). 12 or more 0.65 or less, the production method of the aqueous pigment dispersion of claim 1. The mass ratio of the polyester resin (B) to the (meth) acrylic resin (A) in the pigment mixture in step 1 [polyester resin (B) / (meth) acrylic resin (A)] is 0.15 or more and 15 or less. The method for producing an aqueous pigment dispersion according to claim 1 or 2. The method for producing an aqueous pigment dispersion according to any one of claims 1 to 3, wherein a high-pressure homogenizer is used as a means for applying shear stress. The method for producing an aqueous pigment dispersion according to claim 4, wherein the processing pressure when performing the dispersion treatment using a high-pressure homogenizer is 60 MPa or more and 300 MPa or less. The method for producing an aqueous pigment dispersion according to claim 4 or 5, wherein the number of passes when performing the dispersion treatment using a high-pressure homogenizer is 3 or more and 30 or less. The method for producing an aqueous pigment dispersion according to any one of claims 1 to 6, further comprising the following steps 1-1 and 1-2 before step 1.
Step 1-1: A step of dispersing the pigment with a (meth) acrylic resin (A) having an acid group to obtain a pre-dispersion.
Step 1-2: An emulsion of the polyester resin (B) is added to the pre-dispersion obtained in the step 1-1 to add a pigment, a (meth) acrylic resin (A) having an acid group, and a polyester resin (A). B) Step of obtaining a pigment mixture containing and The method for producing an aqueous pigment dispersion according to any one of claims 1 to 7, wherein both the (meth) acrylic resin (A) and the polyester resin (B) have an acid group. The method for producing an aqueous pigment dispersion according to any one of claims 1 to 8, wherein the cross-linking agent (C) is a polyglycidyl ether compound of a polyhydric alcohol having a hydrocarbon group having 3 or more and 8 or less carbon atoms. 7. Method for producing an aqueous pigment dispersion. The mass ratio of the pigment to the total amount of the pigment in the aqueous pigment dispersion and the (meth) acrylic resin (A) [pigment / (pigment + (meth) acrylic resin (A))] is 0.3 or more and 0. The method for producing an aqueous pigment dispersion according to any one of claims 1 to 10, which is 95 or less. A method for producing an aqueous ink, which comprises mixing the aqueous pigment dispersion according to any one of claims 1 to 11 with an organic solvent.