Abstract: An object of the present invention is to provide a method for producing a polysaccharide derivative in which the use of a reagent such as an acid catalyst is not needed and a reaction can be smoothly progressed without causing any side reactions. A method for producing a polysaccharide derivative of the present invention includes a step of dissolving a raw material including a polysaccharide in at least one ionic liquid having an anion which is a non-carboxylate anion and reacting the raw material with an acyl group donor, a conjugate acid of the anion having a pKa of 4 or higher in vacuum.

Abstract: Provided is a black ink composition containing a pigment, wherein the value calculated from the average particle diameter and the particle size distribution width of the pigment and the ink viscosity is regulated within a certain range, and the number of coarse particles contained in the ink composition is regulated to a certain value or less. The ink composition is excellent in ink storage stability and can give an image realized with good balance between color development, in particular, in high-speed printing and inhibition of a time-dependent change in printing density due to pigment sedimentation.

Abstract: An ink jet ink set, at least has a cyan ink, a magenta ink, and a yellow ink, in which the cyan ink contains at least either one of C.I. Acid Blue 9 or C.I. Direct Blue 199, the magenta ink contains at least either one of C.I. Acid Red 249 or C.I. Reactive Red 141, the yellow ink contains at least either one of C.I. Direct Yellow 86 or C.I. Direct Yellow 132, and the cyan ink, the magenta ink, and the yellow ink all contain an alkylene oxide adduct of acetylene glycol having 12 or more carbon atoms in the main chain, acetylene glycol having 10 or more carbon atoms in the main chain, and polyoxy alkylene alkyl ether.

Abstract: Provided is a black ink composition containing a pigment, wherein the value calculated from the average particle diameter and the particle size distribution width of the pigment and the ink viscosity is regulated within a certain range, and the number of coarse particles contained in the ink composition is regulated to a certain value or less. The ink composition is excellent in ink storage stability and can give an image realized with good balance between color development, in particular, in high-speed printing and inhibition of a time-dependent change in printing density due to pigment sedimentation.

Abstract: Provided is a black ink composition containing a pigment, wherein the value calculated from the average particle diameter and the particle size distribution width of the pigment and the ink viscosity is regulated within a certain range, and the number of coarse particles contained in the ink composition is regulated to a certain value or less. The ink composition is excellent in ink storage stability and can give an image realized with good balance between color development, in particular, in high-speed printing and inhibition of a time-dependent change in printing density due to pigment sedimentation.

Abstract: An ink jet ink set, at least has a cyan ink, a magenta ink, and a yellow ink, in which the cyan ink contains at least either one of C.I. Acid Blue 9 or C.I. Direct Blue 199, the magenta ink contains at least either one of C.I. Acid Red 249 or C.I. Reactive Red 141, the yellow ink contains at least either one of C.I. Direct Yellow 86 or C.I. Direct Yellow 132, and the cyan ink, the magenta ink, and the yellow ink all contain an alkylene oxide adduct of acetylene glycol having 12 or more carbon atoms in the main chain, acetylene glycol having 10 or more carbon atoms in the main chain, and polyoxy alkylene alkyl ether.

Abstract: An ink set includes at least a cyan ink composition containing a self-dispersible pigment, a magenta ink composition containing a self-dispersible pigment, and a yellow ink composition containing a pigment coated with a water-insoluble polymer.

Abstract: An ink composition includes at least a pigment, a humectant, and water in from 10 to 60% by weight to the total amount of ink. The humectant is a mixture of (A) at least one compound selected from glycerin, 1,2,6-hexanetriol, diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol; (B) either trimethylol propane or trimethylol ethane, or a mixture thereof; and (C) at least one compound selected from betaines, saccharides, and ureas and having a molecular weight in the range of from 100 to 200, at a content weight ratio of (A):(B):(C) of 1.0:0.1 to 1.0:1.0 to 3.5.

Abstract: An ink set includes at least a cyan ink composition containing a self-dispersible pigment, a magenta ink composition containing a self-dispersible pigment, and a yellow ink composition containing a pigment coated with a water-insoluble polymer.

Abstract: Provided is a black ink composition containing a pigment, wherein the value calculated from the average particle diameter and the particle size distribution width of the pigment and the ink viscosity is regulated within a certain range, and the number of coarse particles contained in the ink composition is regulated to a certain value or less. The ink composition is excellent in ink storage stability and can give an image realized with good balance between color development, in particular, in high-speed printing and inhibition of a time-dependent change in printing density due to pigment sedimentation.

Abstract: An ink composition includes at least a pigment, a humectant, and water in from 10 to 60% by weight to the total amount of ink. The humectant is a mixture of (A) at least one compound selected from glycerin, 1,2,6-hexanetriol, diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol; (B) either trimethylol propane or trimethylol ethane, or a mixture thereof; and (C) at least one compound selected from betaines, saccharides, and ureas and having a molecular weight in the range of from 100 to 200, at a content weight ratio of (A):(B):(C) of 1.0:0.1 to 1.0:1.0 to 3.5.