Fiber-reinforced resin molding material and production method therefor
A fiber-reinforced resin molding material containing at least bundled aggregates [A] of discontinuous reinforcing fibers and a matrix resin [M], wherein each of the bundled aggregates [A] is obtained by cutting a partially-separated fiber bundle, prepared by forming separation treatment sections separated into a plurality of bundles and non-separation treatment sections alternately along a lengthwise direction of a fiber bundle including a plurality of single fibers, at an angle θ (0°<θ<90°) with respect to the lengthwise direction of the fiber bundle.
1. A fiber-reinforced resin molding material containing at least bundled aggregates [A] of discontinuous reinforcing fibers and a matrix resin [M], wherein each of the bundled aggregates [A] is obtained by cutting a partially-separated fiber bundle, prepared by forming separation treatment sections separated into a plurality of bundles and non-separation treatment sections alternately along a lengthwise direction of a fiber bundle comprising a plurality of single fibers, at an angle θ (0°<θ<90°) with respect to the lengthwise direction of the fiber bundle.
2. The fiber-reinforced resin molding material according to claim 1 , wherein, in the partially-separated fiber bundle, an entangled part in which the plurality of single fibers are tangled with each other and/or an entanglement accumulation part in which the entangled parts are accumulated is formed in at least one end portion of at least one of the separation treatment sections.
3. The fiber-reinforced resin molding material according to claim 2 , wherein the bundled aggregate [A] contains at least one kind of aggregate selected from:
a separated bundle aggregate [a] divided into an arbitrary number of bundles by separation treatment;
a joined bundle aggregate [b] in which single fibers of the fiber bundle are joined to each other by the non-separation treatment section and/or the entangled part and/or the entanglement accumulation part; and
a joined cut aggregate [c] in which the non-separation treatment section and/or the entangled part and/or the entanglement accumulation part intersects with a cutting plane of the partially-separated fiber bundle at the time of being cut, and the joining of single fibers of the fiber bundle to each other is cut off at the intersected part.
4. The fiber-reinforced resin molding material according to claim 3 , wherein, in the bundled aggregate [A], the content of the joined bundle aggregate [b] is 0 to 15%.
5. A method of producing a fiber-reinforced resin molding material according to claim 2 , comprising cutting the partially-separated fiber bundle to satisfy equation (1) when the bundled aggregate [A] is obtained:
W ·cos θ/ D≥ 3 (1)
W: width of fiber bundle at cutting partially-separated fiber bundle
D: distance between cutting planes in bundled aggregate [A].
6. The fiber-reinforced resin molding material according to claim 1 , wherein the bundled aggregate [A] contains at least one aggregate selected from:
a separated bundle aggregate [a] divided into an arbitrary number of bundles by separation treatment;
a joined bundle aggregate [b] in which single fibers of the fiber bundle are joined to each other by the non-separation treatment section and/or the entangled part and/or the entanglement accumulation part; and
a joined cut aggregate [c] in which the non-separation treatment section and/or the entangled part and/or the entanglement accumulation part intersects with a cutting plane of the partially-separated fiber bundle at the time of being cut, and the joining of single fibers of the fiber bundle to each other is cut off at the intersected part.
7. The fiber-reinforced resin molding material according to claim 6 , wherein, in the bundled aggregate [A], the content of the joined bundle aggregate [b] is 0 to 15%.
8. A method of producing a fiber-reinforced resin molding material according to claim 7 , comprising cutting the partially-separated fiber bundle to satisfy equation (1) when the bundled aggregate [A] is obtained:
W ·cos θ/ D≥ 3 (1)
W: width of fiber bundle at cutting partially-separated fiber bundle
D: distance between cutting planes in bundled aggregate [A].
9. A method of producing a fiber-reinforced resin molding material according to claim 1 , comprising cutting the partially-separated fiber bundle to satisfy equation (1) when the bundled aggregate [A] is obtained:
W ·cos θ/ D≥ 3 (1)
W: width of fiber bundle at cutting partially-separated fiber bundle
D: distance between cutting planes in bundled aggregate [A].
10. The method according to claim 9 , further comprising subjecting the partially-separated fiber bundle to widening treatment at an arbitrary timing before cutting the partially-separated fiber bundle.