Patent ID: 8919948

Claim:
An ink for an ink jet recording apparatus, wherein the ink contains at least water, a pigment dispersion, a penetrant, a non-ionic water-soluble acrylic resin and a surfactant of a compound represented by general formula (I), (II) or (III), the penetrant contains an alkane diol having 8 or 9 carbon atoms, the content of the alkane diol is 0.3 to 1.0 mass % relative to the total mass of the ink, the content of the surfactant is 0.05 to 0.5 mass % relative to the total mass of the ink, the content of the non-ionic water-soluble acrylic resin is 0.05 to 0.5 mass % relative to the total mass of the ink, the non-ionic water-soluble acrylic resin has an average molecular weight of 3000 to 8000 and has a hydrophobic segment, and when the non-ionic water-soluble acrylic resin is added to water at a quantity of 0.1 mass % relative to 100 mass % of the water, the surface tension of the water is 29 to 33 mN/m: (in general formula (I), R 1 is C N H 2N+1 and may be straight chain or branched chain, N is an integer whereby 7≦N≦13, -E-O— is —CH 2 CH 2 —O—, —P—O— is —CH 2 CH(CH 3 )—O—, n and m are numbers whereby 5≦n+m≦12 and n>m, and repeating sequences consisting of (-E-O—) and (—P—O—) may be in a random pattern or a block pattern) (in general formula (II), R 1 is C N H 2N+1 and may be straight chain or branched chain, N is an integer whereby 7≦N≦13, -E-O— is —CH 2 CH 2 —O—, —P—O— is —CH 2 CH(CH 3 )—O—, X and Y are integers whereby 5≦X+Y≦12 and X>Y (provided that X=X 1 +X 2 + . . . Xn, and Y=Y 1 +Y 2 + . . . Ym), repeating sequences consisting of (-E-O—) and (—P—O—) may be in a random pattern or a block pattern, and n and m are numbers whereby (-E-O—): (—P—O—) is between 10:3 and 5:1, and are such that 11>n>2 and 6>m>1) (in general formula (III), R 1 is C N1 H 2N1+1 and may be straight chain or branched chain, R 2 is C N2 H 2N2+1 and may be straight chain or branched chain, N1 and N2 are integers whereby 7≦N1+N2≦10, -E-O— is —CH 2 CH 2 —O—, and n is a integers whereby 4≦n≦12).