The present invention relates to a stimuli-responsive composition that contains a polymer, a solvent and a substance having a predetermined function. One embodiment of the composition contains a block polymer, a solvent and a substance having a predetermined function. Preferably, the solvent in the composition is water; and the polymer in the composition has a polyvinyl ether structure. The composition has superior dispersion stability. The present invention also relates to an ink composition containing the composition, an image-forming method and an image-forming apparatus using the ink composition, and a recording medium having the composition.
A block polymer comprised of a polyalkenyl ether main chain comprises a first block segment having hydrophobicity; a second block segment having an upper limit hydration temperature exceeding 70.degree. C.; and a third block segment having an ionic property. A polymer-containing composition comprises the block polymer, a solvent or a dispersing medium, and a functional substance. An ink composition comprises the polymer-containing composition wherein the functional substance is colorant. A liquid application method comprises the steps of preparing the polymer-containing composition; and applying the polymer-containing composition to a medium. A liquid application apparatus comprises a liquid application means which makes energy act on the polymer-containing composition to apply the composition; and a drive means which drives the liquid application means. The polymer compound is capable of satisfactorily dispersing a functional substance in a solvent.
An inkjet ink set includes a red ink and an other ink. The red ink consists essentially of an ink vehicle and an effective amount of pigment red 168. The other ink includes an ink vehicle and an effective amount of at least one other pigment.
A process for producing a colorant comprises the step of mixing a coloring material and a block copolymer in a flow channel of a microreactor to obtain a dispersion comprising a colorant as a dispersoid. The flow-mixing channel may have a cross-sectional area of not less than 0.5 mm.sup.2, and the ratio of the total cross-sectional areas of flow channels connected with the flow-mixing channel to the cross-sectional area of the flow-mixing channel ranges from 0.01 to 0.1, and a rectangular cross-section having a ratio of a flow channel depth to a flow channel width of not less than 0.5.
