Low refractive index coating composition

1 . A radiation curable composition, comprising:

a) reactive nanoparticles absent a fluorinated group;

b) reactive nanoparticles having at least one fluorinated group; and

c) one or more ethylenically unsaturated urethane fluorinated components.

2 . The composition according to claim 1 , wherein both said reactive nanoparticles comprise metal oxide.

3 . The radiation curable composition according to claim 2 , wherein said reactive nanoparticles having at least one fluorinated group comprise an organic component bound to said metal oxide.

4 . The radiation curable composition according to claim 3 , wherein said organic component comprises unsaturated polymerizable group.

5 . The composition according to claim 4 , wherein said unsaturated polymerizable group is acrylate, methacrylate, propenyl, vinyl, butadienyl, styryl, ethynyl, cinnamoyl, vinyl ether, maleate, acrylamide, epoxy, oxetane, amine-ene or thiol-ene.

6 . The radiation curable composition according to claim 4 , wherein said fluorinated group is located in the organic component comprising unsaturated polymerizable group.

7 . The radiation curable composition according to claim 4 , wherein said fluorinated group is not located in the organic component comprising unsaturated polymerizable group.

8 . The composition according to claim 1 , wherein both said reactive nanoparticles comprise oxide of silicon.

9 . The composition according to claim 1 , wherein the ratio of said reactive nanoparticles absent a fluorinated group to said reactive nanoparticles having at least one fluorinated group is 1:9 to 9:1.

10 . The composition according to claim 1 , wherein said fluorinated group of said reactive particles is a fluoroalkyl group.

11 . The composition according to claim 1 , wherein said composition, when cured, has a refractive index of less than 1.50.

12 . The composition according to claim 1 , wherein said composition, when cured, has a pencil hardness no lower than F.

13 . The composition according to claim 1 , wherein said composition has a % RAU of at least 40%.

14 . The composition according to claim 1 , wherein said composition, when cured, when tested by abrasion test displays no damage.

15 . A radiation curable composition, comprising:

a) 50 wt % to 90 wt % of reactive nanoparticles free of fluorinated group, relative to the total weight of said components (a), (b), and (c);

b) 5 wt % to 20 wt % of reactive nanoparticles having at least one fluorinated group, relative to the total weight of said components (a), (b), and (c); and

c) 1 wt % to 10 wt % of one or more ethylenically unsaturated urethane fluorinated components, relative to the total weight of said components (a), (b), and (c).

16 . A radiation curable composition comprising:

a) reactive nanoparticles free of fluorinated group;

b) reactive nanoparticles having at least one fluorinated group;

c) ethylenically unsaturated urethane fluorinated component; and

d) one or more photoinitiators, wherein said composition has a RI lower than 1.50, a pencil hardness higher than F when cured, and a % RAU of 55% to 70%.

17 . A radiation curable composition comprising:

a) reactive nanoparticles comprising an organic component bound to said reactive particles, wherein said organic component comprises an unsaturated polymerizable group and a fluorinated group in its structure; and

b) an ethylenically unsaturated urethane fluorinated component.

18 . The radiation curable composition according to claim 17 , wherein said reactive particles further comprise an organic component absent a fluorinated group.

19 . The composition according claim 17 , wherein said composition is formulated to provide, after cure, an optical fiber primary coating, an optical fiber secondary coating, a matrix coating, a bundling material, an ink coating a photonics crystal fiber coating, an adhesive for optical disc, a hard coat coating, a display coating or a lens coating.

20 . A process for preparing a low refractive index coating, comprising:

a) reactive nanoparticles absent a fluorinated group;

b) reactive nanoparticles having at least one fluorinated group; and

c) an ethylenically unsaturated urethane fluorinated component.

21 . A process for preparing an article with a low refractive index coating comprising: applying the composition according to claim 1 to a surface of a coated substrate.

22 . A process of making a coating for an article comprising:

a) preparing a radiation curable composition comprising:

i) reactive nanoparticles absent a fluorinated group;

ii) reactive nanoparticles having at least one fluorinated group; and

iii) an ethylenically unsaturated urethane fluorinated component; and

b) coating said radiation curable composition on said article.

23 . The process according to claim 22 , wherein said article is an optical fiber, a photonics crystal fiber, an optical disc, an optical fiber ribbon, a hardcoat layer, an antireflective layer for display or lens.

24 . A low refractive index coating prepared by curing a radiation curable composition according to claim 1 .

25 . A display monitor comprising a plastic substrate coated at least in part with a coating obtained by curing the composition according to claim 1 .

26 . An antireflective system comprising a coating obtained by curing the composition of claim 1 .

27 . An article comprising:

a) a substrate;

b) a hardcoat layer;

c) a high refractive index coating on said hardcoat layer; and

d) a low refractive index coating, said low refractive index coating obtained by curing the composition comprising:

i) reactive nanoparticles free of fluorinated group;

ii) reactive nanoparticles having at least one fluorinated group; and

iii) an ethylenically unsaturated urethane fluorinated component.

28 . The article according to claim 27 , wherein said article is an antireflective display.

29 . The article according to claim 28 , wherein said substrate is polynorbonene, polyethyleneterephtalate, polymethylmethacrylate, polycarbonate, polyethersulphone, polyimide, cellulose, cellulose triacetate, fluorene polyester or polyethernaphtalene.

30 . A composition comprising:

a) reactive nanoparticles absent a fluorinated group; and

b) reactive nanoparticles having at least one fluorinated group;

wherein the ratio of particles (a) to particles (b) is at least 1:1.

31 . A radiation curable composition, comprising:

a) reactive nanoparticles; and

b) one or more ethylenically unsaturated urethane fluorinated components;

wherein the ratio of said reactive nanoparticles to said ethylenically unsaturated urethane fluorinated components is at least 6:1.

32 . A radiation curable composition wherein said composition, when cured, has

a) a refractive index of less than 1.5; and

b) a pencil hardness no lower than F.

33 . The radiation curable composition of claim 32 , wherein said composition, when cured has a % RAU of at least 40.

34 . A display panel comprising a radiation curable coating composition wherein said composition, when cured, has

a) a refractive index of less than 1.5; and

b) a pencil hardness no lower than F.