Brightness enhancing film and methods of surface treating inorganic nanoparticles

• US 7,547,467 B2
• Filed: 11/14/2006
• Issued: 06/16/2009
• Est. Priority Date: 11/15/2005
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Goenner, Emily S., Jones, Clinton L., Kolb, Brant U., Olson, David B., McKenzie, Taun L., Hendrickson, Mark J.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US11/559,543
• Publication Number:
  US 20070112097A1
• Time in Patent Office: 945 Days
• Field of Search: 428/1.1, 428/500, 428/1.3, 428/1.51, 428/1.54, 428/1.55, 428/147, 428/148, 524/413, 524/430, 524/437, 524/493, 524/558, 524/559, 977/773, 523/202, 523/210
• US Class Current: 428/1.3
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: C08K 5/101 of monocarboxylic acids
• CPC Class Codes: C08K 9/04 Ingredients treated with organic substances treated with macromolecular compounds C08K9/08
• CPC Class Codes: C09C 1/00 Treatment of specific inorganic materials other than fibrous fillers tenebrescent materials C09K9/00; luminescent materials C09K11/00; Preparation of carbon black
• CPC Class Codes: C09C 3/08 Treatment with low-molecular-weight non-polymer organic compounds C09C3/006, C09C3/048 take precedence
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: C09K 2323/051 Inorganic, e.g. glass or silicon oxide
• CPC Class Codes: C09K 2323/057 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• CPC Class Codes: C09K 2323/059 Unsaturated aliphatic polymer, e.g. vinyl
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: Y10S 977/773 Nanoparticle, i.e. structure having three dimensions of 100 nm or less
• CPC Class Codes: Y10T 428/24405 Polymer or resin [e.g., natural or synthetic rubber, etc.]
• CPC Class Codes: Y10T 428/24413 Metal or metal compound
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

Presently described are (e.g. brightness enhancing film) optical articles comprising the reaction product of a polymerizable resin and surface modified inorganic nanoparticles, methods of surface modifying inorganic nanoparticles, and surface modified inorganic nanoparticles. The surface treatment comprises at least one monocarboxylic acid having a refractive index of at least 1.50 and/or at least one monocarboxylic acid having a Mn of at least 200 g/mole and an ethylenically unsaturated group and/or at least one dicarboxylic acid.

Claims

1. A brightness enhancing film comprising the reaction production of a polymerizable resin composition including inorganic nanoparticles surface modified with a surface treatment comprising a monocarboxylic acid having a refractive index of at least 1.50.

2. The brightness enhancing film of claim 1 wherein the surface treatment comprises an aromatic group.

3. The brightness enhancing film of claim 2 wherein the surface treatment comprises a phthalate group.

4. The brightness enhancing film of claim 1 wherein the surface treatment further comprises at least one polyether monocarboxylic acid.

5. The brightness enhancing film of claim 4 wherein the polyether monocarboxylic acid has the general formula:

CH₃—

[O—

(CH₂)_y]_x—

X₂—

(CH₂)_n—

COOH

wherein X₂ is selected from the group consisting of —

O—

, —

S—

, —

C(O)O— and

—

C(O)NH;

n ranges from about 1-3;

x ranges from about 1-10; and

y ranges from about 1-4.

6. The brightness enhancing film of claim 5 wherein the polyether monocarboxylic acid is selected from the group consisting of 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, 2-(2-methoxyethoxy) acetic acid, succinic acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester, maleic acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester, and glutaric acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester, and mixtures thereof.

7. The brightness enhancing film of claim 1 wherein the surface treatment further comprises a compatibilizer and the compatibilizer comprises an ethylenically unsaturated group.

8. A brightness enhancing film of claim 7 wherein the compatibilizer comprises a (meth)acrylate group.

9. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles comprise adsorbed volatile acid and the adsorbed volatile acid content of the brightness enhancing film is less than 3 wt-%.

10. The brightness enhancing film of claim 9 wherein the adsorbed volatile acid is acrylic acid, methacrylic acid, acetic acid, or a mixture thereof.

11. The brightness enhancing film of claim 9 wherein the brightness enhancing film comprises non-volatile acid and the non-volatile acid content ranges up to about 15 wt-%.

12. The brightness enhancing film of claim 1 wherein the surface treatment is free of silane.

13. The brightness enhancing film of claim 1 wherein the amount of inorganic nanoparticles ranges from 40 wt-% to 60 wt-%.

14. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles are selected from the group consisting of zirconia, titania, and mixtures thereof.

15. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles have a primary particle that ranges in size from 5 nm to 75 nm.

16. An optical article comprising the reaction production of a polymerizable resin composition including inorganic nanoparticles surface modified with a surface treatment comprising at least one monocarboxylic acid compatibilizer having a polar group in combination with at least one surface treatment selected from

i) a monocarboxylic acid having a refractive index of at least 1.50;

ii) a monocarboxylic acid having a Mn of at least 200 g/mole that copolymerizes with the polymerizable resin;

iii) a dicarboxylic acid;

and mixtures of two or more of i), ii), and iii).

17. The brightness enhancing film of claim 16 wherein i) comprises an aromatic group.

18. The optical article of claim 16 wherein the optical article is a film optionally having a microstructured surface.

19. A method of surface modifying inorganic nanoparticles by combining inorganic nanoparticles with a surface treatment comprising at least one monocarboxylic acid compatibilizer having a polar group in combination with at least one surface treatment selected from

i) a monocarboxylic acid having a refractive index of at least 1.50

ii) a monocarboxylic acid having a Mn of at least 200 g/mole and (meth)acrylate group;

and mixtures of two or more of i) and ii).

20. The method of claim 19 wherein the inorganic nanoparticles comprise absorbed volatile acid and the adsorbed volatile acid content after surface modification is less than 3 wt-%.

21. Inorganic nanoparticles comprising a surface treatment comprising at least one monocarboxylic acid having a polar group in combination with at least one surface treatment selected from

i) a monocarboxylic acid having a refractive index of at least 1.50

ii) a monocarboxylic acid having a Mn of at least 200 g/mole and (meth)acrylate group;

and mixtures of two or more of i)and ii).