PROBLEM TO BE SOLVED: To provide a duck bill type check valve which is interposed on a liquid flow path such as infusion set and cardiopulmonary circuit and is suitable for medical application.SOLUTION: A duck bill type check valve 100 includes: a cylindrical casing part 101 which has a flange 111 on the base end side and a valve body part 102 which is a pair of symmetrical planar valve bodies inclined and extended so as to be converged into the axial center toward the tip side from the inner base end side of the casing part 101 and in which a straight slit 121 on a contact surface of the valve body tip is formed. Therein, the duck bill type check valve 100 is integrally molded with an elastic material having a Shore A hardness of 45 to 55, and is characterized in that a valve body inner surface is stretched without being bent to the inside up to the contact surface, an outer diameter of a casing part 101 cylinder is 3.5 to 4.5 mm, a cylinder thickness is 0.45 to 0.60 mm, an inclination angle of the valve body with respect to the axis is 10 to 30°, a contact length in the axial direction of the contact surface is 0.35 to 0.55 mm and the cylinder thickness≥the contact length.COPYRIGHT: (C)2014,JPO&INPIT【課題】輸液セットや心肺回路等の液体流路に介在させる医療用途に好適なダックビル形逆止弁を提供すること【解決手段】 基端側にフランジ111を有する円筒状の筐体部101と、筐体部101内部基端側から先端側に向けて軸中心で収束するように傾斜して延出した一対の対称な面状の弁体であって、弁体先端の当接面で直線状のスリット121が形成された弁体部102と、を有する、ショアA硬度が45~55の弾性素材により一体成形されたダックビル形逆止弁100であって、弁体内面は当接面まで内側に折れ曲がらずに延伸し、筐体部101円筒の外径が3.5mm~4.5mmであり円筒肉厚が0.45mm~0.60mm、軸に対する弁体の傾斜角度が10°~30°、当接面の軸方向の接触長さが0.35mm~0.55mmかつ円筒肉厚≧接触長であることを特徴とするダックビル形逆止弁100。【選択図】図2
