Structure material
A structure material includes a resin, reinforced fibers, and voids, a volume content of the resin being within a range of 2.5% by volume or more and 85% by volume or less, a volume content of the reinforced fibers being within a range of 0.5% by volume or more and 55% by volume or less, the voids being contained in the structure material in a rate within a range of 10% by volume or more and 97% by volume or less, a thickness St of the structure material satisfying a conditional expression: St≥Lf 2 ·(1−cos(θf)) where a length of the reinforced fibers is Lf and an oriented angle of the reinforced fibers in a sectional direction of the structure material is θf, and a compression strength in an in-plane direction at 50% compression of the structure material measured in accordance with JIS K7220 being 3 MPa or more.
1. A structure material comprising a resin, reinforced fibers, and voids,
a volume content of the resin being within a range of 2.5% by volume or more and 85% by volume or less,
a volume content of the reinforced fibers being within a range of 0.5% by volume or more and 55% by volume or less,
the voids being contained in the structure material in a rate within a range of 10% by volume or more and 97% by volume or less,
a thickness St (mm) of the structure material satisfying a conditional expression:
St≥Lf 2 ·(1−cos(θ f ))
wherein
a length of the reinforced fibers is Lf (mm),
an oriented angle θf (degrees) in the conditional expression is an arithmetic mean of oriented angles measured for reinforced fibers in a sectional direction of the structure material,
the oriented angle θf is 3° or more and 60° or less, and
a compression strength in an in-plane direction at 50% compression of the structure material measured in accordance with JIS K7220 is 3 MPa or more.
2. The structure material according to claim 1 , wherein a compression strength in an out-of-plane direction of the structure material is 10 MPa or more.
3. The structure material according to claim 1 , wherein a specific bending modulus of the structure material represented as Ec 1/3 ·ρ −1 is within a range of 3 or more and 20 or less where a bending modulus of the structure material is Ec and a specific gravity of the structure material is ρ, and the bending modulus Ec of the structure material is 3 GPa or more.
4. The structure material according to claim 1 , wherein a specific gravity ρ of the structure material is 0.9 g/cm 3 or less.
5. The structure material according to claim 1 , wherein a porosity of parts within 30% to a midpoint position in a thickness direction from surfaces of the structure material is within a range of 0% by volume or more and less than 10% by volume, and a porosity of a residual part is within a range of 10% by volume or more and 97% by volume or less.
6. The structure material according to claim 1 , wherein the reinforced fibers are coated with the resin, and a thickness of the resin is within a range of 1 μm or more and 15 μm or less.
7. The structure material according to claim 1 , wherein the reinforced fibers are discontinuous and are dispersed in a nearly monofilament form and in a random manner.
8. The structure material according to claim 1 , wherein a longer of the mass mean fiber length of the reinforced fibers is within a range of 1 mm or more and 15 mm or less.
9. The structure material according to claim 1 , wherein the reinforced fibers are carbon fibers.
10. The structure material according to claim 1 , wherein the resin contains at least one thermoplastic resin.
11. The structure material according to claim 1 , wherein the resin contains at least one thermosetting resin.
12. A structure material comprising a resin, reinforced fibers, and voids,
a volume content of the resin being within a range of 2.5% by volume or more and 85% by volume or less,
a volume content of the reinforced fibers being within a range of 0.5% by volume or more and 55% by volume or less,
the voids being contained in the structure material in a rate within a range of 10% by volume or more and 97% by volume or less,
a thickness St (mm) of the structure material satisfying a conditional expression:
St≥Lf 2 ·(1−cos(θ f ))
wherein
a length of the reinforced fibers is Lf (mm),
an oriented angle θf (degrees) in the conditional expression is an arithmetic mean of oriented angles measured for reinforced fibers in a sectional direction of the structure material,
the oriented angle θf is 3° or more and 60° or less, and
a specific impact strength of the structure material represented as Ac·ρ −1 is within a range of 4 or more and 30 or less, an Ac is the structure material impact strength which is 2 kJ/m2 or more and ρ is the structure material specific gravity.
13. The structure material according to claim 12 , wherein the specific impact strength of the structure material is within a range of 7 or more and 20 or less, and the impact strength of the structure material is 3 kJ/m 2 or more.