| 摘要 |
There is provided a random mat for obtaining a fiber-reinforced composite material excellent in tensile strength. A random mat including carbon fibers and a matrix resin, wherein the carbon fibers in the random mat have an average fiber length in a range of 3 mm to 100 mm, a fiber areal weight of the carbon fibers is 25 to 10,000 g/m 2 , at least one of fiber bundles including the carbon fibers less than a critical number of single fiber being defined by the following formula (1) and a single fiber, and carbon fiber bundles (A) constituted by the carbon fibers of the critical number of single fiber or more are present in the random mat, a ratio of the carbon fiber bundles (A) to a total amount of the carbon fibers in the random mat is a range of 20 Vol% to 99 Vol%, an average number (N) of fibers in the carbon fiber bundles (A) satisfies the following formula (2), and a ratio of carbon fiber bundles having a thickness of 100 µm or more of the carbon fiber bundles (A) is less than 3% of the number of whole carbon fiber bundles (A): Critical number of single fiber = 600 / D 0.6 × 10 4 / D 2 < N < 1 × 10 5 / D 2
wherein D is an average fiber diameter (µm) of single carbon fibers. |
