Leader tape and magnetic tape cartridge using the same

1. A magnetic tape cartridge comprising:

a reel;

a magnetic tape;

a leader tape joined at a tip of the magnetic tape to be loaded into a magnetic recording and reproducing apparatus;

a cartridge case rotatably housing the reel on which the magnetic tape is wound, wherein the leader tape comprises a support and a coating layer containing powder and a binder, wherein at least one surface of the leader tape has a center line average surface roughness (Ra) of from 10 to 60 nm, and depression hardness (DH) defined by the following equation (1) of from 60 to 140 kg/mm 2 (0.588 to 1.372 GPa):

DH −3.7926×10 −2 [Pmax /( Hmax ) 2 ]kg/mm 2 )  (1)

wherein Pmax is a maximum load and Hmax is a maximum displacement amount of an indenter.

2. The leader tape according to claim 1 , wherein the depression hardness (DH) defined by the equation (1) is from 80 to 120 kg/mm 2 (0.784 to 1.176 GPa).

3. The leader tape according to claim 1 , wherein at least one surface of the leader tape has a center line average surface roughness (Ra) of from 15 to 45 nm.

4. The leader tape according to claim 1 , which comprises:

a back layer containing a carbon black;

the support;

a nonmagnetic layer containing inorganic powder and a binder; and

a magnetic layer containing ferromagnetic powder and a binder,

in this order.

5. The leader tape according to claim 4 , which the magnetic layer contains the binder in an amount of from 5 to 50 weight % based on an amount of the ferromagnetic powder contained in the magnetic layer.

6. The leader tape according to claim 4 , which the nonmagnetic layer contains the binder in an amount of from 5 to 50 weight % based on an amount of the inorganic powder contained in the nonmagnetic layer.

7. The leader tape according to claim 4 , which the magnetic layer contains polyisocyanate in an amount of from 2 to 20 weight % based on an amount of the ferromagnetic powder contained in the magnetic layer.

8. The leader tape according to claim 4 , which the nonmagnetic layer contains polyisocyanate in an amount of from 2 to 20 weight % based on an amount of the inorganic powder contained in the nonmagnetic layer.

9. The leader tape according to claim 4 , which the support has a center line average surface roughness (Ra) of from 5 to 80 nm.

10. The leader tape according to claim 4 , which the support has a center line average surface roughness (Ra) of from 10 to 65 nm.

11. The leader tape according to claim 4 , which the inorganic powder has an average particle size of from 0.02 to 1 μM.

12. The leader tape according to claim 4 , which the inorganic powder has an average particle size of from 0.05 to 0.6 μm.