Optical film including functional coating layer and polarizing plate and image display device including same

Abstract

The present invention relates to an optical film including an acryl-based film; and a functional coating layer formed on at least one surface of the acryl-based film, containing a conductive material and a water-dispersible resin and having surface resistance of 10.sup.9 W/Sq to 10.sup.13 W/Sq.

Claims

1. An optical film comprising: an acryl-based film; and a functional coating layer formed on at least one surface of the acryl-based film, containing a conductive material and a water-dispersible resin, and having surface resistance of 10.sup.9 W/Sq to 10.sup.13 W/Sq, wherein the water-dispersible resin is a water-dispersible polyurethane-based resin, a water-dispersible acryl-based resin or a combination thereof.

2. The optical film of claim 1, wherein the conductive material is a conductive polymer; an ionic liquid; a metal oxide; or a mixture thereof.

3. The optical film of claim 2, wherein the conductive polymer is a polythiophene-based, a polypyrrole-based, a polyaniline-based polymer compound or a mixture thereof.

4. The optical film of claim 2, wherein the metal oxide is doped zinc oxide (ZnO), doped tin oxide (ATO) or doped indium oxide (ITO).

5. The optical film of claim 2, wherein the ionic liquid includes one or more types selected from the group consisting of a cation formed with alkylimidazolium, alkylphosphonium, N-alkylpyridinium, N,N-dialkylimidazolium or a derivative thereof; an anion formed with bromide, hexafluorophosphate, hexafluoroantimonite, tetrafluoroborate, difluoromethane sulfate, methane sulfate, tosylate, chloride or a derivative thereof; and a mixture thereof.

6. The optical film of claim 2, wherein the functional coating layer includes the conductive polymer in 1 to 10 parts by weight with respect to 100 parts by weight of the water-dispersible resin.

7. The optical film of claim 2, wherein the functional coating layer includes the ionic liquid in 5 to 25 parts by weight with respect to 100 parts by weight of the water-dispersible resin.

8. The optical film of claim 2, wherein the functional coating layer includes the metal oxide in 0.1 to 10 parts by weight with respect to 100 parts by weight of the water-dispersible resin.

9. The optical film of claim 1, wherein a weight average molecular weight of the polyurethane-based resin is 10,000 to 100,000.

10. The optical film of claim 1, wherein the polyurethane-based resin includes a carboxyl group.

11. The optical film of claim 1, which is a protective film for a polarizing plate.

12. A polarizing plate comprising the optical film of claim 11.

13. An image display device comprising the polarizing plate of claim 12.

Description

EXAMPLE 1

(1) After an unoriented film having a width of 800 mm was prepared with a poly(cyclohexylmaleimide-co-methyl methacrylate) (LG MMA PMMA830HR) resin using a T-die film-forming apparatus under a condition of 250 C. and 250 rpm, the film was oriented by 1.8 times in an MD direction at a temperature of 135 C.

(2) An anti-static functional coating solution was prepared by mixing 4.67 g of a water-dispersible polyurethane-based resin (Chokwang Paint Ltd., CK-PUD-PF: aqueous solution having 30% solid content), 2 g of a conductive material (PEDOT/PSS, aqueous solution having 1.4% solid content) and 13.33 g of pure water.

(3) An optical film was prepared by coating the functional coating solution prepared above on the acryl-based film oriented in an MD direction using a #5 Mayer bar, and then orienting the result by 2.0 times in a TD direction for 1 min at a temperature of 135 C.

EXAMPLE 2

(4) An optical film was prepared in the same manner as in Example 1 except that 3 g of the conductive material (PEDOT/PSS, aqueous solution having 1.4% solid content) was used when preparing the functional coating solution.

EXAMPLE 3

(5) An optical film was prepared in the same manner as in Example 1 except that 1.40 g of polyaniline sulfonic acid (PAS, Mitsubishi Rayon, Co., Ltd., aqueous solution having 3.0% solid content) was used as the conductive material instead of PEDOT/PSS (aqueous solution having 1.4% solid content) when preparing the functional coating solution.

EXAMPLE 4

(6) An optical film was prepared in the same manner as in Example 1 except that 2.33 g of polyaniline sulfonic acid (PAS, Mitsubishi Rayon, Co., Ltd., aqueous solution having 3.0% solid content) was used as the conductive material instead of PEDOT/PSS (aqueous solution having 1.4% solid content) when preparing the functional coating solution.

EXAMPLE 5

(7) An optical film was prepared in the same manner as in Example 1 except that 0.21 g of an ionic liquid (IL-OH8, KOEI Chemical Co., Ltd.) was used as the conductive material instead of PEDOT/PSS (aqueous solution having 1.4% solid content) when preparing the functional coating solution.

EXAMPLE 6

(8) An optical film was prepared in the same manner as in Example 1 except that 4.67 g of an acryl-based resin (TAKAMATSU OIL & FAT Co. Ltd., A-645: aqueous solution having 30% solid content) was used instead of the water-dispersible polyurethane-based resin (Chokwang Paint Ltd., CK-PUD-PF: aqueous solution having 30% solid content) when preparing the functional coating solution.

EXAMPLE 7

(9) An optical film was prepared in the same manner as in Example 2 except that 4.67 g of an acryl-based resin (TAKAMATSU OIL & FAT Co. Ltd., A-645: aqueous solution having 30% solid content) was used instead of the water-dispersible polyurethane-based resin (Chokwang Paint Ltd., CK-PUD-PF: aqueous solution having 30% solid content) when preparing the functional coating solution.

EXAMPLE 8

(10) An optical film was prepared in the same manner as in Example 5 except that 4.67 g of an acryl-based resin (TAKAMATSU OIL & FAT Co. Ltd., A-645: aqueous solution having 30% solid content) was used instead of the water-dispersible polyurethane-based resin (Chokwang Paint Ltd., CK-PUD-PF: aqueous solution having 30% solid content) when preparing the functional coating solution.

Comparative Example 1

(11) After an unoriented film having a width of 800 mm was prepared with a poly(cyclohexylmaleimide-co-methyl methacrylate) (LG MMA PMMA830HR) resin using a T-die film-forming apparatus under a condition of 250 C. and 250 rpm, the film was oriented by 1.8 times in an MD direction at a temperature of 135 C.

(12) An optical film was prepared by orienting the film prepared above by 2.0 times in a TD direction for 1 min at a temperature of 135 C. without a process of preparing and coating an anti-static functional coating solution as in Example 1.

Comparative Example 2

(13) An optical film was prepared in the same manner as in Example 1 except that a coating solution was prepared by mixing 4.67 g of a water-dispersible polyurethane-based resin (Chokwang Paint Ltd., CK-PUD-PF: aqueous solution having 30% solid content) and 13.33 g of pure water and coating the solution on the oriented film.

Comparative Example 3

(14) An optical film was prepared in the same manner as in Example 1 except that 15 g of a conductive material (PEDOT/PSS, aqueous solution having 1.4% solid content) was used when preparing the functional coating solution.

Comparative Example 4

(15) An optical film was prepared in the same manner as in Example 1 except that 1 g of a conductive material (PEDOT/PSS, aqueous solution having 1.4% solid content) was used when preparing the functional coating solution.

Comparative Example 5

(16) An optical film was prepared in the same manner as in Example 1 except that 0.43 g of an ionic liquid (IL-OH8, KOEI Chemical Co., Ltd.) was used as the conductive material instead of PEDOT/PSS (aqueous solution having 1.4% solid content) when preparing the functional coating solution.

Comparative Example 6

(17) An optical film was prepared in the same manner as in Example 1 except that 0.014 g of an ionic liquid (IL-OH8, KOEI Chemical Co., Ltd.) was used as the conductive material instead of PEDOT/PSS (aqueous solution having 1.4% solid content) when preparing the functional coating solution.

Test Example

(18) 1. Surface Resistance

(19) 3 points on the surface of the prepared anti-static optical film were measured for 3 times each using a surface resistance measuring device (MCP-HT450/MITSUBUSHI CHEMICAL) and Probe (URS, UR100), and the average value was calculated. The results are shown in the following Table 1.

(20) 2. Evaluation on Coatability

(21) The surface of the 20 cm20 cm film prepared in Examples 1 to 8 and Comparative Examples 2 to 6 was observed, and the degree of the coated exterior defects such as overall stains, bar pattern stains, spot-type stains and Dewetting marks was evaluated. The results are shown in the following [Table 1].

(22) (favorable): defect region area was less than 1%.

(23) (moderate): defect region area was greater than or equal to 1% and less than 10%.

(24) x (poor): defect region area was 10% or greater.

(25) 3. Evaluation on Adhesive Strength

(26) A 2 cm2 cm polarizing plate prepared by laminating the film prepared in Examples 1 to 8 and Comparative Examples 1 to 6, a PVA polarizer and another protective film using an adhesive was pulled out with 0.05 N and 0.5 cm/sec for 6 seconds using a texture analyzer, and adhesive strength between the prepared acryl-based film and the PVA was determined by the degree of the destruction of the acrylic substrate film. The measurement results are shown in the following [Table 1]. (Herein, the acryl-based film being destroyed means that the PVA polarizer and the primer completely adhere.)

(27) (favorable): the destroyed area of the acrylic substrate film on the adhesion surface was 50% or greater.

(28) (moderate): the destroyed area of the acrylic substrate film on the adhesion surface was 50% or less.

(29) x (poor): the destroyed area of the acrylic substrate film on the adhesion surface was none.

(30) 4. Anti-Blocking Property

(31) A film roll was formed by slitting both ends of the prepared film, and then winding 500 m or greater of the film in a roll. Wound status of the film, and changes in the roll appearances and the like after the roll was left unattended for 1 week or longer were identified by visual observation, and an anti-blocking property was evaluated as follows. The measurement results are shown in the following [Table 1].

(32) (favorable): film was wound without wrinkles, and no changes in the appearances were observed or there was no adhesion between the films after being left attended for 1 week or longer.

(33) x (poor): wrinkles occurred when the film was wound, or changes in the appearances were observed, or there was adhesion between the films after being left attended.

(34) TABLE-US-00001 TABLE 1 Conductive Material Composition Physical Properties Water- Surface Anti- dispersible Conductive Resistance Adhesive blocking Category Film Resin Material (W/Sq) Coatability Strength Property Example 1 Acryl Polyurethane PEDOT 2 10.sup.12 to 10.sup.13 Parts by Weight Example 2 Acryl Polyurethane PEDOT 3 10.sup.11 Parts by Weight Example 3 Acryl Polyurethane PAS 3 10.sup.13 Parts by Weight Example 4 Acryl Polyurethane PAS 5 10.sup.12 Parts by Weight Example 5 Acryl Polyurethane IL-OH8 1.5 10.sup.12 15 Parts by Weight Example 6 Acryl Acryl-based PEDOT 2 10.sup.12 to 10.sup.13 Resin Parts by Weight Example 7 Acryl Acryl-based PEDOT 3 10.sup.11 Resin Parts by Weight Example 8 Acryl Acryl-based IL-OH8 10.sup.12 Resin 15 Parts by Weight Comparative Acryl >10.sup.15 x x Example 1 Comparative Acryl Polyurethane >10.sup.15 Example 2 Comparative Acryl Polyurethane PEDOT 15 10.sup.10 x x Example 3 Parts by Weight Comparative Acryl Polyurethane PEDOT 1 >10.sup.15 Example 4 Parts by Weight Comparative Acryl Polyurethane IL-OH8 10.sup.11 to 10.sup.12 x Example 5 30 Parts by Weight Comparative Acryl Polyurethane IL-OH8 1 >10.sup.15 Example 6 Parts by Weight

(35) When comparing Examples 1 to 8 and Comparative Example 1 of Table 1, it was seen that the acryl-based film including the functional coating layer according to the present invention had more superior surface resistance compared to the acryl-based film that does not include the functional coating layer, thereby had an excellent anti-static property. In addition, when examining Comparative Examples 3 to 6, it was identified that when the content of the conductive polymer was outside the proper content range described in the present invention, coatability and adhesive strength were reduced.

(36) Hereinbefore, examples of the present invention have been described in detail, however, claims of the present invention are not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes may be made without departing from the spirit of the present invention described in the claims.