| 摘要 |
PROBLEM TO BE SOLVED: To provide a fibrillated fiber suitable for improving mechanical strength in the thickness direction of wet friction material. SOLUTION: The fibrillated fiber aggregate has fibrils that are composed of an organic high-molecular polymer and has a fibril diameter of 1μm or less. The fibrillated fiber aggregate satisfies the following requirements of (a) among fibers constituting the fiber aggregate, the content of crimped fibers has one or more pairs of crimped ridges and valleys in main fibers represented by the following formula: the crimped fiber content =N<SB>c</SB>/N<SB>0.5</SB>×100 is 20% or more (wherein N<SB>c</SB>is the number of crimped fibers having one or more pairs of crimped ridges and valleys in the main stem fibers; N<SB>0.5</SB>is the number of total fibers having a fiber length of 0.5 mm or more), and (b) a specific surface area of fiber aggregate is 3-20 m<SP>2</SP>/g. COPYRIGHT: (C)2009,JPO&INPIT
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