Patent ID: 7850296

Claim:
An ink jet ink reservoir used for ink jet recording, the ink jet ink reservoir receiving a capillary force generating member constituted by an aggregate of fiber, wherein the fiber constituting the capillary force generating member is formed by drawing at least one polyolefin resin, the polyolefin resin comprising an antioxidant at least with a hindered phenol skeleton and a phosphorus antioxidant as an additive, wherein the fiber constituting the capillary force generating member comprises an oxide of the phosphorus antioxidant, the oxide being produced by oxidation of the phosphorous antioxidant with thermal energy generated during processing or production of the capillary force generating member, wherein the oxide has an elution time, measured by liquid chromatography, longer than that of an oxide of bis(2,6-di-t-butylphenyl)pentaerythritol diphosphite, and wherein the phosphorus antioxidant is at least one selected from the group consisting of 6-[3-(3-t-butyl-4-hydroxy-5-methyl)propoxy]-2,4,8,10-tetra-t-butyldibenz[d,f][1,3,2]-dioxaphosphepin and 2,2′-methylenebis(4,6-di-t-butylphenyl)octylphosphite.