Lightweight helmet shell and method for manufacturing the same

1. A lightweight helmet shell comprising an inner shell and an outer shell, wherein the outer shell includes a compressed fiber sheet having an apparent density of 0.15 to 0.7 g/cc and an impact absorbability of 50 G or more and less than 300 G, wherein the inner shell includes a porous expanded plastic layer having an apparent density of 0.005 to 0.2 g/cc.

2. The lightweight helmet shell according to claim 1 , wherein the compressed fiber sheet is a product obtained by subjecting a fiber sheet formed from a material containing any one selected from the group consisting of polyethylene, polypropylene, polyester, viscose rayon, nylon, cotton, hemp, wool and combinations thereof, to a hot pressing treatment at a compression ratio of 1.2 times to 10 times.

3. The lightweight helmet shell according to claim 2 , wherein the fiber sheet is any one selected from the group consisting of a non-woven fabric, a woven fabric, and a knitted fabric.

4. The lightweight helmet shell according to claim 2 , wherein the hot pressing treatment is conducted at a temperature of 50° C. to 200° C. and at a pressure of 10 to 3,000 atm, for 10 seconds to 30 minutes.

5. The lightweight helmet shell according to claim 1 , wherein the compressed fiber sheet includes

a high melting point fiber which forms a fiber structural layer of the compressed fiber sheet and has a melting point of 120 to 350° C., and

a low melting point fiber which binds the high melting point fiber strands and has a melting point of 50 to 200° C.

6. The lightweight helmet shell according to claim 1 , wherein the compressed fiber sheet has an air permeability of 10 to 2,000 cm 3 /min/cm 2 .

7. The lightweight helmet shell according to claim 1 , wherein the outer shell has a thickness of 0.1 mm to 6 mm.

8. The lightweight helmet shell according to claim 1 , further comprising a thermosetting resin or thermoplastic resin film layer having a thickness of 0.01 mm to 0.8 mm, formed on the outer side of the outer shell.

9. The lightweight helmet shell according to claim 1 , further comprising a coating film layer having a thickness of 0.01 mm to 0.8 mm, formed on the outer side of the outer shell by melting a thermosetting resin or thermoplastic resin.

10. The lightweight helmet shell according to claim 1 , further comprising a coating film layer formed by pretreating the outer side of the outer shell with a primer, and then coating a paint to a thickness of 0.01 mm to 0.8 mm.

11. A method for manufacturing a lightweight helmet shell according to claim 1 , the method comprising:

producing a fiber sheet;

pressing the fiber sheet in a forming mold at a pressure of 10 to 3,000 atm; and

heating the fiber sheet at 50° C. to 200° C. for 10 seconds to 30 minutes to produce a compressed fiber sheet.

12. The method for manufacturing a lightweight helmet shell according to claim 11 , wherein the compressed fiber sheet is a product obtained by subjecting the fiber sheet to a hot pressing treatment at a compression ratio of 1.2 times to 10 times.

13. The method for manufacturing a lightweight helmet shell according to claim 11 , wherein the fiber sheet is formed from a material containing any one selected from the group consisting of polyethylene, polypropylene, polyester, viscose rayon, nylon, cotton, hemp, wool and combinations thereof.

14. The method for manufacturing a lightweight helmet shell according to claim 11 , wherein the fiber sheet is any one selected from the group consisting of a non-woven fabric, a woven fabric, and a knitted fabric.

15. The method for manufacturing a lightweight helmet shell according to claim 11 , wherein the fiber sheet includes:

a high melting point fiber which forms a fiber structural layer of the compressed fiber sheet and has a melting point of 120 to 350° C., and

a low melting point fiber which binds the high melting point fiber strands and has a melting point of 50 to 200° C.