Method for producing optical film, and optical film

1. A method for producing an optical film having on a surface thereof an uneven structure provided with projections at a pitch equal to or shorter than the wavelength of visible light,

the method comprising the steps of:

(1) supplying a lower layer resin and an upper layer resin;

(2) forming a resin layer having the uneven structure on a surface thereof while mixing the lower resin and the upper resin by pressing a mold against the lower layer resin and the upper layer resin from the upper layer resin side in the state where the supplied lower layer resin and upper layer resin are stacked; and

(3) curing the resin layer in which the lower layer resin and the upper layer resin are mixed,

the upper layer resin containing a fluorine-containing monomer,

at least one of the lower layer resin and the upper layer resin containing a compatible monomer that contains no fluorine atoms and is compatible with the fluorine-containing monomer,

the compatible monomer being dissolved in the lower layer resin and the upper layer resin.

2. The method for producing an optical film according to claim 1 ,

wherein the step (1) is performed by sequentially applying the lower layer resin and the upper layer resin to a base film.

3. The method for producing an optical film according to claim 1 ,

wherein the step (1) is performed by simultaneously applying the lower layer resin and the upper layer resin to a base film.

4. The method for producing an optical film according to claim 1 ,

wherein the step (1) is performed by applying the lower layer resin to a base film and the upper layer resin to the mold, and

the step (2) is performed by pressing, from the upper layer resin side, the mold to which the upper layer resin has been applied against the lower layer resin applied to the base film.

5. The method for producing an optical film according to claim 2 ,

wherein the upper layer resin is applied by a spray method.

6. The method for producing an optical film according to claim 1 ,

wherein the mold has been subjected to a release treatment.

7. The method for producing an optical film according to claim 1 ,

wherein the lower layer resin has a viscosity of higher than 10 cp and lower than 10000 cp at 25° C.

8. The method for producing an optical film according to claim 1 ,

wherein the upper layer resin has a viscosity of higher than 0.1 cp and lower than 100 cp at 25° C.

9. The method for producing an optical film according to claim 1 ,

wherein the fluorine-containing monomer is curable by ultraviolet rays.

10. The method for producing an optical film according to claim 1 ,

wherein the upper layer resin has a concentration of the fluorine-containing monomer of higher than 0% by weight and lower than 20% by weight.

11. The method for producing an optical film according to claim 1 ,

wherein the upper layer resin contains no solvent.

12. The method for producing an optical film according to claim 1 ,

wherein the compatible monomer includes an acid amide bond in the molecule.

13. The method for producing an optical film according to claim 1 ,

wherein a difference between the solubility parameter of the compatible monomer and the solubility parameter of the fluorine-containing monomer is in the range of 0 (cal/cm 3 ) 1/2 to 4.0 (cal/cm 3 ) 1/2 .

14. The method for producing an optical film according to claim 1 ,

wherein a difference between the solubility parameter of the compatible monomer and the solubility parameter of a monomer component other than the compatible monomer in the lower layer resin is in the range of 0 (cal/cm 3 ) 1/2 to 3.0 (cal/cm 3 ) 1/2 .

15. The method for producing an optical film according to claim 1 ,

wherein a difference between the solubility parameter of the compatible monomer and the solubility parameter of a monomer component other than the compatible monomer in the upper layer resin is in the range of 0 (cal/cm 3 ) 1/2 to 3.0 (cal/cm 3 ) 1/2 .

16. The method for producing an optical film according to claim 4 ,

wherein the upper layer resin is applied by a spray method.

17. The method for producing an optical film according to claim 1 ,

wherein a surface of the optical film has a contact angle with water of 100° or greater and a contact angle with hexadecane of 40° or greater.

18. The method for producing an optical film according to claim 1 ,

wherein the fluorine-containing monomer includes a moiety containing at least one selected from the group consisting of fluoroalkyl groups, fluorooxyalkyl groups, fluoroalkenyl groups, fluoroalkanediyl groups, and fluorooxyalkanediyl groups, and a reactive moiety.

19. The method for producing an optical film according to claim 18 ,

wherein the fluorine-containing monomer is represented by the following formula (A):

R f1 —R f2 -D 1   (A)

wherein R f1 represents a moiety containing at least one selected from the group consisting of fluoroalkyl groups, fluorooxyalkyl groups, fluoroalkenyl groups, fluoroalkanediyl groups, and fluorooxyalkanediyl groups; R 2 represents an alkanediyl group, an alkanetriyl group, or the ester, urethane, ether, or triazine structure derived from any of these groups; and D 1 represents a reactive moiety.

20. The method for producing an optical film according to claim 1 ,

wherein the fluorine-containing monomer includes a fluoropolyether moiety represented by the following formula (B) or (C):

CF n1 H (3-n1) —(CF n2 H (2-n2) ) k O—(CF n3 H (2-n3) ) m O—  (B)

—(CF n4 H (2-n4) ) p O—(CF n5 H (2-n5) ) s O—  (C)

wherein n1 is an integer of 1 to 3, n2 to n5 each are 1 or 2, and k, m, p, and s each are an integer of 0 or greater.

21. The method for producing an optical film according to claim 1 ,

wherein the pitch is in the range of 100 nm to 400 nm.