Medical material and hollow fiber membrane module

A hollow fiber membrane module comprising:

• a hollow fiber membrane bundle which is composed of hollow fiber membranes, each hollow fiber membrane having, on a surface thereof which is to be in contact with blood, a hydrophilic copolymer having a relaxation time of adsorbed water of 2.5×10−8 seconds or shorter and 5.0×10−10 seconds or longer at −40° C.;
• a main body case in which the hollow fiber membrane bundle is stored;
• partitioning walls which enable the hollow fiber membrane bundle to be held in a liquid-tight state at both ends of the main body case while keeping hollow fiber membranes in an opened state;
• and
• headers which are respectively attached to both ends of the main body case and through which blood can be introduced and led out;
• and
• zones A to H, which are produced by dividing a region lying between a position corresponding to the inner diameter (D0) of each of the headers and a position 1 mm apart from the aforementioned position toward the inner periphery into equal 8 parts equiangular with the center of axis of the main body case as its center in an edge face of each of the partitioning walls on a side facing each of the headers;
• wherein each of zones A to H are configured to have a hollow fiber membrane packing density within the range from 13 to 40%, and the overall packing density of the edge face of each of the partitioning walls is within the range of 53 to 64%;
• wherein the partitioning wall edge faces contain dispersed hollow fiber membranes,
• wherein a flexible layer is present on the surface which is to be in contact with blood in each of the hollow fiber membranes when the hydrophilic copolymer is in a moistened state and the flexible layer has a thickness of 7 nm or more;
• and
• wherein particulate protuberances each having a particle diameter of 50 nm or more are present on the surface which is to be in contact with blood in each of the hollow fiber membranes within a density range of from 0.1 particles/μm2 to 3 particles/μm2.