초록 ▼

Within an area of substantially regular hexagons arranged at regular intervals on an imaginary reference plane, a sheet material includes a concave-convex section (20) having a basic pattern in which one first region (A1) is surrounded by six second regions (A2). This basic pattern repeats in regula

Within an area of substantially regular hexagons arranged at regular intervals on an imaginary reference plane, a sheet material includes a concave-convex section (20) having a basic pattern in which one first region (A1) is surrounded by six second regions (A2). This basic pattern repeats in regular intervals in lateral and longitudinal directions of the sheet material. The concave-convex section includes first protruding portions (21) and second protruding portion (22), which protrude in opposite directions from each other in the thickness direction in the first regions and the second regions, respectively. The first and second protruding portions may have a hexagonal pyramidal shape or a truncated hexagonal pyramidal shape.

대표청구항 ▼

1. A sheet material having a stiffness-increasing concave-convex section, wherein: within an area of substantially regular hexagons arranged at regular intervals on an imaginary reference plane, the concave-convex section has a basic pattern in which one first region directly borders six second regi

1. A sheet material having a stiffness-increasing concave-convex section, wherein: within an area of substantially regular hexagons arranged at regular intervals on an imaginary reference plane, the concave-convex section has a basic pattern in which one first region directly borders six second regions and the basic pattern repeats at regular intervals in lateral and longitudinal directions of the plane,each first region is defined by a first protruding portion,each second region is defined by a second protruding portion,the first and second protruding portions protrude in opposite directions from each other in a thickness direction of the sheet material, the first protruding portions have a hexagonal pyramidal shape or a truncated hexagonal pyramidal shape, which protrudes on one side in the thickness direction and has an outer contour line on the imaginary reference plane that defines a base portion thereof, andthe second protruding portions have a hexagonal pyramidal shape or a truncated hexagonal pyramidal shape, which protrudes on the other side in the thickness direction and has an outer contour line on the imaginary reference plane that defines a base portion thereof. 2. The sheet material according to claim 1, wherein an inclination angle of side surfaces of the first protruding portions relative to the imaginary reference plane is within the range of 10° to 60° and an inclination angle of side surfaces of the second protruding portions relative to the imaginary reference plane is within the range of 10° to 60°. 3. The sheet material according to claim 1, wherein the inclination angle of the side surfaces of the first protruding portions relative to the reference plane and the inclination angle of the side surfaces of the second protruding portions relative to the reference plane are equal to each other, and the side surfaces of the first protruding portion positioned in the center of the basic pattern and the side surfaces of the second protruding portions, which are peripherally adjacent to the first protruding portion, are evenly and continuously formed without having a bent part at the reference plane. 4. The sheet material according to claim 1, wherein the inclination angle of the side surfaces of the first protruding portions relative to the reference plane is different from the inclination angle of the side surfaces of the second protruding portions relative to the reference plane, and the side surfaces of the first protruding portion positioned in the center of the basic pattern and the side surfaces of the second protruding portions, which are peripherally adjacent to the first protruding portion, are joined by a bent part at the reference plane. 5. The sheet material according to claim 1, wherein at least one of the first protruding portions and the second protruding portions has the hexagonal pyramidal shape or the truncated hexagonal pyramidal shape with a plurality of steps defining a step portion that changes the inclination angle in an intermediate portion thereof. 6. The sheet material according to claim 2, wherein the sheet material has a thickness (t) of 0.05 mm to 3.0 mm before the concave-convex section is formed in the sheet material. 7. The sheet material according to claim 6, wherein a ratio (D1/t) of an outer dimension (D1) (mm) of the base portion of the first protruding portions to the thickness (t) (mm) is 10 to 2000 and a ratio (D2/t) of an outer dimension (D2) (mm) of the base portion of the second protruding portions to the thickness (t) (mm) is 10 to 2000. 8. The sheet material according to claim 6, wherein a ratio (H1/t) of a protruding height (H1) (mm) of the first protruding portions to the thickness (t) (mm) satisfies 1≦(H1/t)≦−4θ1+242 in which θ1(°) is the largest inclination angle on the side surfaces of the first protruding portions, and a ratio (H2/t) of a protruding height (H2) (mm) of the second protruding portions to the thickness (t) (mm) satisfies 1≦(H2/t)≦−4θ2+242 in which θ2(°) is the largest inclination angle on the side surfaces of the second protruding portions. 9. The sheet material according to claim 1, wherein a ratio (D1/t) of an outer dimension (D1) of the base portion of the first protruding portions to the thickness (t) of the sheet material is 10 to 2000 and a ratio (D2/t) of an outer dimension (D2) of the base portion of the second protruding portions to the thickness (t) of the sheet material is 10 to 2000. 10. The sheet material according to claim 9, wherein: a ratio (H1/t) of a protruding height (H1) of the first protruding portions to the thickness (t) of the sheet material satisfies 1≦(H1/t)≦−4θ1+242, wherein θ1(°) is the largest inclination angle of the side surfaces of the first protruding portions, anda ratio (H2/t) of a protruding height (H2) of the second protruding portions to the thickness (t) of the sheet material satisfies 1≦(H2/t)≦−4θ2+242, wherein θ2(°) is the largest inclination angle of the side surfaces of the second protruding portions. 11. The sheet material according to claim 10, wherein an inclination angle of side surfaces of the first protruding portions relative to the imaginary reference plane is within the range of 10° to 60° and an inclination angle of side surfaces of the second protruding portions relative to the imaginary reference plane is within the range of 10° to 60°. 12. The sheet material according to claim 11, wherein the thickness of the sheet material is between 0.05 mm and 3.0 mm before the concave-convex section is formed in the sheet material. 13. The sheet material according to claim 11, wherein the outer dimension (D1) of the base portion of the first protruding portions is equal to the outer dimension (D2) of the base portion of the second protruding portions. 14. The sheet material according to claim 13, wherein the protruding height (H1) of the first protruding portions is equal to the protruding height (H2) of the second protruding portions. 15. The sheet material according to claim 14, wherein the inclination angles θ1(20 ) and θ2(°) are 20°. 16. The sheet material according to claim 14, wherein the inclination angles θ1(°) and θ2(°) are 30°. 17. The sheet material according to claim 14, wherein the side surfaces of the first protruding portions and the side surfaces of the second protruding portions each comprise first and second portions joined at a bent part, the first portion having a smaller inclination angle relative to the imaginary reference plane than the second portion. 18. The sheet material according to claim 14, wherein the sheet material has a cylindrical shape as a whole. 19. The sheet material according to claim 1, wherein the substantially regular hexagons form a tessellation on the imaginary reference plane. 20. A sheet material having a stiffness-increasing concave-convex section, wherein: within an area of substantially regular hexagons arranged at regular intervals on an imaginary reference plane, the concave-convex section has a basic pattern in which one first region is surrounded by six second regions and the basic pattern repeats at regular intervals in lateral and longitudinal directions of the plane,each first region is defined by a first protruding portion,each second region is defined by a second protruding portion,the first and second protruding portions protrude in opposite directions from each other in a thickness direction of the sheet material, the first protruding portions have a hexagonal pyramidal shape or a truncated hexagonal pyramidal shape, which protrudes on one side in the thickness direction and has an outer contour line on the imaginary reference plane that defines a base portion thereof, andthe second protruding portions have a hexagonal pyramidal shape or a truncated hexagonal pyramidal shape, which protrudes on the other side in the thickness direction and has an outer contour line on the imaginary reference plane that defines a base portion thereof, andwherein the outer contour line of each of the first protruding portions has six and no more than six sides and the outer contour line of each of the second protruding portions has six and no more than six sides and wherein each of the six and no more than six sides of the outer contour line of one of the first protruding portions forms one of the six and no more than six sides of the six-sided outer contour lines of six of the second protruding portions.