Method for manufacturing SMC

A manufacturing method of an SMC, comprising:

• (i) forming chopped carbon fiber bundles by chopping a continuous carbon fiber bundle having a filament number of NK with a rotary cutter;
• (ii) fragmentation-processing the chopped carbon fiber bundles by using a fragmentation-processing apparatus;
• (iii) forming a carbon fiber mat by depositing the fragmentation-processed chopped carbon fiber bundles on a carrier film traveling below the rotary cutter;
• and
• (iv) impregnating the carbon fiber mat with a thermosetting resin composition,
• wherein N is 20 or more, and
• the fragmentation-processing apparatus comprises a first pin roller and a second pin roller which are disposed side by side, each having a rotation axis parallel to a rotation axis direction of the rotary cutter,
• wherein the first pin roller is rotationally driven such that its pins move downward from above on its side facing the second pin roller, and the second pin roller is rotationally driven such that its pins move downward from above on its side facing the first pin roller, and
• wherein a sum of a maximum radius of the first pin roller and a maximum radius of the second pin roller is equal to or greater than a distance between the rotation axes of the first pin roller and the second pin roller.

A manufacturing method of an SMC, comprising:

• (i) forming chopped carbon fiber bundles by chopping a continuous carbon fiber bundle having a filament number of NK with a rotary cutter;
• (ii) fragmentation-processing the chopped carbon fiber bundles by using a fragmentation-processing apparatus;
• (iii) forming a carbon fiber mat by depositing the fragmentation-processed chopped carbon fiber bundles on a carrier film traveling below the rotary cutter;
• and
• (iv) impregnating the carbon fiber mat with a thermosetting resin composition,
• wherein N is 20 or more, and
• the fragmentation-processing apparatus comprises a first pin roller and a second pin roller which are disposed side by side, each having a rotation axis parallel to a rotation axis direction of the rotary cutter,
• wherein the first pin roller is rotationally driven such that its pins move downward from above on its side facing the second pin roller, and the second pin roller is rotationally driven such that its pins move downward from above on its side facing the first pin roller,
• wherein a sum of a maximum radius of the first pin roller and a maximum radius of the second pin roller is equal to or greater than a distance between the rotation axes of the first pin roller and the second pin roller, and
• wherein the continuous carbon fiber bundle is a continuous carbon fiber bundle partially split into n sub-bundles (where, n is an integer of 2 or more) such that N/n is 10 to 25.