Method of Producing Fiber Assembly and Method of Producing Prepreg Sheet

27:

• The method of producing a fiber assembly according to claim 26, wherein the fiber assembly is composed of a fiber bundle, and the fibers present on the surface of the fiber bundle are curved and oriented along an outline of an ellipsoid.

28:

• The method for producing a fiber assembly according to claim 26, wherein the plurality of fibers are ones in which resin residues have been removed by heat treatment in an oxidizing atmosphere.

29:

• The method of producing a fiber assembly according to claim 26,
• wherein the stirring tank includes a scraper and is made to rotate.

30:

• The method of producing a fiber assembly according to claim 29,
• wherein the stirring is carried out such that a rotation direction of the stirring blade is the same as a rotation direction of the stirring tank after the stirring is carried out such that the rotation direction of the stirring blade is opposite to the rotation direction of the stirring tank.

31:

• The method of producing a fiber assembly according to claim 29, further comprising:
• rotating the stirring tank at a peripheral speed of 1.2 m/sec or less.

32:

• The method of producing a fiber assembly according to claim 26,
• wherein the fiber treatment agent has a surface tension of 120 mN/m or less at 23° C.

33:

• The method of producing a fiber assembly according to claim 26,
• wherein the fiber treatment agent has a viscosity of 10 Pa·s or less at 23° C.

34:

• The method of producing a fiber assembly according to claim 26,
• wherein positions of tips of the plurality of fibers constituting the fiber assembly are not aligned.

35:

• The method of producing a fiber assembly according to claim 26,
• wherein a length of a major axis of the fiber assembly is greater than an average fiber length of the fibers contained in the fiber assembly.

36:

• The method of producing a fiber assembly according to claim 26,
• wherein the fiber assembly has a prolate spheroidal shape or a strand shape.

37:

• The method of producing a fiber assembly according to claim 26,
• wherein a ratio (Y/X) of an average fiber length Y of the fibers in the fiber assembly to an average fiber length X of the fibers before being put into the stirring tank is 0.55 or greater.

38:

• A fiber assembly produced by the method for producing a fiber assembly according to claim 26.

39:

• A method of producing a prepreg sheet, comprising:
• accumulating a plurality of fiber assemblies obtained by the method of producing a fiber assembly according to claim 26.

41:

• The carbon fiber assembly according to claim 40, wherein the fiber assembly is composed of a fiber bundle, and the fibers present on the surface of the fiber bundle are curved and oriented along an outline of an ellipsoid.

42:

• The carbon fiber assembly according to claim 40, wherein the positions of tips of the plurality of fibers constituting the carbon fiber assembly are not aligned.

43:

• The carbon fiber assembly according to claim 40, wherein the length of major axis of the carbon fiber assembly is longer than the average fiber length of the fibers contained in the carbon fiber assembly.

45:

• The fiber assembly according to claim 44, wherein the length A of the major axis of the fiber bundle is 3 to 30 mm.

46:

• The fiber assembly according to claim 44, wherein the average fiber length of the fibers in the fiber bundle is shorter than the major axis.

47:

• The fiber assembly according to claim 44, wherein the fiber bundle has the major axis, a short axis 1, and a short axis 2, and a length B of the short axis 1 is longer than a length C of the short axis 2.

48:

• The fiber assembly according to claim 44, wherein B is 1 to 9 mm and C is 0.5 to 6 mm.

49:

• The fiber assembly according to claim 47, wherein the fiber bundle has a ratio (B/A) of the length B of the short axis 1 to the length A of the major axis of 2 to 12 and a ratio (C/A) of the length C of the short axis 2 to the length A of the major axis of 1 to 6.

50:

• The fiber assembly according to claim 44, wherein B is 1.5 times or more of C.

51:

• The fiber assembly according to claim 44, wherein the fiber bundle has a particle density represented by the following formula (2) of 0.3 to 1.8 g/cm3:
• Particle density=G/(4πabc/3) Formula (2)
• in the formula (2), G represents the mass of the fiber bundle, a represents A/2, b represents B/2, and c represents C/2.

52:

• The fiber assembly according to claim 44, wherein a proportion of the number of the fiber bundles W1 is 50% or more.