Nonwoven fabric separator for lead storage battery, and lead storage battery using same

1. A nonwoven fabric separator for a lead storage battery, comprising a nonwoven fabric composed of a recycled fiber or synthetic fiber, wherein a relationship between the average pore diameter (D) of the nonwoven fabric separator and the number of pores (N) satisfies the following equation:

1.0×10 2 <D*N< 1.0×10 4

and the nonwoven fabric separator includes at least two layers which are integrated by a calender roll at a line pressure of 100 N/cm to 1000 N/cm, wherein the nonwoven fabric separator has a tensile strength of from 15 N/15 mm to 300 N/15 mm, and wherein the nonwoven fabric separator has a specific surface area of from 0.1 m 2 /g to 50 m 2 /g.

2. The separator according to claim 1 , wherein the nonwoven fabric separator has an average pore diameter of from 0.1 μm to 50 μm.

3. The separator according to claim 1 , wherein the nonwoven fabric separator has a thickness of from 30 μm to 1000 μm and a weight per unit area of from 5 g/m 2 to 300 g/m 2 .

4. The separator according to claim 1 , wherein the nonwoven fabric separator has a porosity of from 30% to 95%.

5. The separator according to claim 1 , wherein the nonwoven fabric is composed of a continuous long fiber as defined by JIS-L0222.

6. The separator according to claim 1 , wherein the nonwoven fabric includes an ultrafine fiber having a fiber diameter of from 0.1 μm to 5 μm.

7. The separator according to claim 6 , wherein the nonwoven fabric separator includes at least two layers including a nonwoven fabric layer (layer I) composed of the ultrafine fiber and a nonwoven fabric layer (layer II) composed of a fiber having a fiber diameter of from 5 μm to 30 μm.

8. The separator according to claim 7 , wherein the nonwoven fabric separator includes three layers in which the layer I is arranged as an intermediate layer between the layer II and the layer II.

9. The separator according to claim 1 , wherein the nonwoven fabric separator is composed of the synthetic fiber.

10. The separator according to claim 1 , wherein the nonwoven fabric separator is composed of a polyester fiber.

11. The separator according to claim 1 , wherein the nonwoven fabric separator is composed of a polyolefin fiber.

12. The separator according to claim 1 , wherein the nonwoven fabric separator has a gas permeability of from 0.01 seconds/100 cc to 10 seconds/100 cc.

13. The separator according to claim 1 , wherein the nonwoven fabric separator is a hydrophilized nonwoven fabric.

14. The separator according to claim 1 , wherein the nonwoven fabric separator is a nonwoven fabric integrated by thermal bonding.

15. The separator according to claim 1 , wherein the nonwoven fabric separator includes a nonwoven fabric substrate having a void space structure and inorganic particles present on a surface portion of the nonwoven fabric substrate or on a fiber surface inside the nonwoven fabric substrate.

16. The separator according to claim 15 , wherein the inorganic particles include a silicon component.

17. The separator according to claim 15 , wherein the inorganic particles have an average particle diameter of from 1 nm to 5000 nm.

18. The separator according to claim 15 , wherein the inorganic particles have a specific surface area of from 0.1 m 2 /g to 1000 m 2 /g.

19. The separator according to claim 15 , wherein the nonwoven fabric separator includes a binder present inside the nonwoven fabric substrate in an amount of from 1 to 500 parts by weight with respect to 100 parts by weight of the inorganic particles.

20. The separator according to claim 1 , wherein the nonwoven fabric separator is heat-sealable.

21. The separator according to claim 1 , wherein the nonwoven fabric separator is composed of the synthetic fiber, and the synthetic fiber is one or more kinds selected from a polyester fiber and a polyolefin fiber.