| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a recording liquid for ink jet which is excellent in dispersion stability and jetting stability, does not cause a pigment to soak into the inside of fibers of a recording paper and improves the optical density on the recording paper by dispersing or dissolving a self-dispersible pigment and a copolymer of acrylic acid with maleic acid (anhydride) in an aqueous medium. SOLUTION: In an aqueous medium, a self-dispersible pigment having a particle diameter corresponding to 50% volume accumulation of at least 80 nm, a particle diameter corresponding to 99% volume accumulation of not more than 400 nm, each measured by means of a dynamic laser scattering grain size distribution meter and an average primary particle size of 10-150 nm, and 0.01-1 wt.% of a copolymer having a number average mol.wt. of 1,000-100,000 obtained by copolymerizing acrylic acid with maleic acid (anhydride) in a molar ratio of 5/1 to 1/1 are dispersed or dissolved to obtain the recording liquid for ink jet having a viscosity (25 deg.C) of 0.8-20 mPa.s and a surface tension of 25-60 mN/m. Record is made on a plain paper of a Beck smoothness of 25-80 sec using this recording liquid for ink jet.</p> |
