INK COMPOSITION AND METHOD FOR PRODUCING THE SAME AS WELL AS INKJET INK SET AND INKJET PRINTING SYSTEM USING INK COMPOSITION

To provide an ink composition having excellent storage stability, dischargeability and curability.SOLUTION: There is provided an ink composition comprising a polymerizable compound and a photopolymerization initiator, wherein the polymerizable compound has one or a plurality of (meth)acrylates in the molecule and has an organic sulfonic acid content of 1 ppm or more and 50 ppm or less as measured by the water extraction method at 25°C, the water extraction method is a chromatographic method to measure the content of an organic sulfonic acid in a measuring liquid prepared by mixing the ink composition and water, and the water content is 0.01 mass% or more and 0.50 mass% or less based on the total mass of the ink composition as measured by the Karl Fischer method.SELECTED DRAWING: None 【課題】保存安定性、ＩＪ吐出性及び硬化性に優れたインク組成物を提供する。【解決手段】本願で開示するインク組成物は、重合性化合物と光重合開始剤とを含み、前記重合性化合物は、分子内に（メタ）アクリレートを１個又は複数有し、温度２５℃における水抽出法で測定した有機スルホン酸の含有量が、１ｐｐｍ以上５０ｐｐｍ以下であり、前記水抽出法は、前記インク組成物と水とを混合して作製した測定液中の有機スルホン酸の含有量をクロマトグラフィ法で測定するものであり、カール・フィッシャー法で測定した水の含有量が、前記インク組成物の全質量に対して０．０１質量％以上０．５０質量％以下である。【選択図】なし