Hair holder

1. A hair holder, comprising:

a flat tube having a sheet which forms a first side and a sheet which forms a second side to allow a hair bundle to be inserted from an opening at one end of the tube toward an opening at an other end thereof such that, when the hair holder is rolled up, the sheet which forms the first side is on an outside of the tube,

the sheet which forms the first side of the tube is more extensible in a length direction of the tube than the sheet which forms the second side of the tube,

the sheet which forms the second side of the tube has a Taber stiffness of 0.4 mNm or higher,

the sheet which forms the first side has an extensibility of at least 15 times an extensibility of the sheet which forms the second side under a load of 5 N,

the extensibility of the sheet which forms the first side is 10% or higher under the load of 5 N, and

the extensibility of the sheet which forms the second side is 5% or less under the load of 5 N.

2. The hair holder according to claim 1 , wherein the sheet which forms the first side has a large number of openings making the sheet extensible.

3. The hair holder according to claim 1 , wherein the sheet is permeable to a hair treating agent.

4. The hair holder according to claim 1 , wherein at least one of the sheet which forms the first side and the sheet which forms the second side has a large number of through-holes each having a smooth edge on one side thereof, and the sheet which forms the first side and the sheet which forms the second side are joined together with a side having a smooth edge facing inside the tube.

5. The hair holder according to claim 1 , wherein the tube is configured to roll itself up into a prescribed shape and to keep the rolled up state.

6. The hair holder according to claim 1 , wherein

the sheet which forms the first side has a plurality of rows, each of the rows including two horizontal openings,

the horizontal openings in alternate rows overlap one another in a vertical direction, and

the plurality of rows of the horizontal openings are configured to make the sheet extensible.

7. The hair holder according to claim 1 , wherein

the sheet which forms the first side has a plurality of rows, each of the rows including three oblique openings,

the oblique openings in alternate rows overlap one another in a vertical direction, and

the plurality of rows of the oblique openings are configured to make the sheet extensible.

8. The hair holder according to claim 1 , wherein

the sheet which forms the first side includes a plurality of rectangular pieces, and

each rectangular piece is configured to partially overlap an adjacent rectangular piece in a horizontal direction, and

the plurality of overlapping rectangular pieces are configured to make the sheet extensible.

9. The hair holder according to claim 8 , wherein each of the plurality of rectangular pieces is only bonded to the adjacent rectangular piece at side edges thereof.

10. The hair holder according to claim 1 , wherein the sheet which forms the first side has the extensibility of at least 30 times the extensibility of the sheet which forms the second side under the load of 5 N.

11. A method of treating hair, comprising:

employing a hair holder including a flat tube having a sheet which forms a first side and a sheet which forms a second side, the sheet which forms the first side of the tube is more extensible in the length direction of the tube than the sheet which forms the second side of the tube, the sheet which forms the second side of the tube has a Taber stiffness of 0.4 mNm or higher, the sheet which forms the first side has an extensibility of at least 15 times an extensibility of the sheet which forms the second side under a load of 5 N, the extensibility of the sheet which forms the first side is 10% or higher under the load of 5 N, and the extensibility of the sheet which forms the second side is 5% or less under the load of 5 N;

inserting a hair bundle through an opening at one end of the tube of the hair holder toward an opening at an other end thereof; and

rolling up the tube having the hair therein with the first side thereof facing out.

12. The method according to claim 11 , wherein the sheet which forms the first side has the extensibility of at least 30 times the extensibility of the sheet which forms the second side under the load of 5 N.

13. The method according to claim 11 , further comprising:

providing a reinforcing strip in the hair holder having a glass transition temperature at or above a room temperature.