Antistatic hardcoat film, process for producing same, polarizer, and image display device

Abstract

The claimed invention provides an antistatic hard coat film that is extremely excellent in white muddiness resistance and antistatic properties and sufficiently prevents an interference fringe pattern. The claimed invention provides an antistatic hard coat film including a triacetyl cellulose substrate and a hard coat layer formed on the triacetyl cellulose substrate, the hard coat layer including an antistatic agent, a (meth)acrylate resin, and a polymer of a (meth)acrylate monomer, the triacetyl cellulose substrate including a permeation layer formed by permeation of the (meth)acrylate monomer from the hard coat layer side of the interface toward the opposite side of the hard coat layer, the antistatic hard coat film satisfying Formulas (1), (2), and (3):
3 mT18 mFormula (1)
0.3Tt0.9TFormula (2)
2 mTt11 mFormula (3)
where T denotes the total thickness (m) of the permeation layer and the hard coat layer, and t denotes the thickness (m) of the permeation layer.

Claims

1. An antistatic hard coat film comprising a triacetyl cellulose substrate, and a hard coat layer formed on the triacetyl cellulose substrate, wherein the hard coat layer comprises an antistatic agent, a (meth)acrylate resin, and a polymer of a (meth)acrylate monomer, wherein the hard coat layer is a cured product of a film formed by applying a composition for producing the hard coat layer on the triacetyl cellulose substrate, the composition comprising the antistatic agent, the (meth)acrylate resin, and the (meth)acrylate monomer, the triacetyl cellulose substrate comprises a permeation layer formed by permeation of the (meth)acrylate monomer from the hard coat layer side of an interface toward the side opposite from the hard coat layer, the antistatic hard coat film satisfies Formulas (1), (2), and (3):
3 mT18 mFormula (1)
0.3Tt0.9TFormula (2)
2 mTt11 mFormula (3) where T denotes the total thickness (m) of the permeation layer and the hard coat layer, and t denotes the thickness (m) of the permeation layer, the antistatic hard coat film exhibits a haze of less than 0.5%, and the antistatic hard coat film exhibits good white muddiness resistance the antistatic hard coat film being prepared by drying the film under the drying conditions below, the drying of the film starting within 20 seconds from completion of the application of the composition; the drying conditions being: Drying temperature: 40 to 80 C.; Drying time: 20 to 70 seconds; and Air velocity for drying: 5 to 20 m/min.

2. The antistatic hard coat film according to claim 1, wherein the thickness of the permeation layer (t) is 2 to 8 m.

3. The antistatic hard coat film according to claim 2, wherein the permeation layer is formed by permeation of the (meth)acrylate monomer in the composition into the triacetyl cellulose substrate.

4. The antistatic hard coat film according to claim 2, wherein the antistatic agent contains a quaternary ammonium salt oligomer.

5. The antistatic hard coat film according to claim 2, wherein the (meth)acrylate monomer has a weight-average molecular weight of less than 1,000.

6. The antistatic hard coat film according to claim 2, wherein the (meth)acrylate monomer is at least one selected from the group consisting of pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid EO-modified tri(meth)acrylate.

7. A polarizer comprising a polarizing element, wherein said polarizer has the antistatic hard coat film according to claim 2 on a surface of the polarizing element.

8. The antistatic hard coat film according to claim 1, wherein the antistatic agent contains a quaternary ammonium salt oligomer.

9. The antistatic hard coat film according to claim 8, wherein the (meth)acrylate monomer has a weight-average molecular weight of less than 1,000.

10. The antistatic hard coat film according to claim 8, wherein the (meth)acrylate monomer is at least one selected from the group consisting of pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid EO-modified tri(meth)acrylate.

11. The antistatic hard coat film according to claim 1, wherein the (meth)acrylate monomer has a weight-average molecular weight of less than 1,000.

12. The antistatic hard coat film according to claim 11, wherein the (meth)acrylate monomer is at least one selected from the group consisting of pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid EO-modified tri(meth)acrylate.

13. The antistatic hard coat film according to claim 1, wherein the (meth)acrylate monomer is at least one selected from the group consisting of pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid EO-modified tri(meth)acrylate.

14. A polarizer comprising a polarizing element, wherein said polarizer has the antistatic hard coat film according to claim 1 on a surface of the polarizing element.

15. An image display device comprising the polarizer according to claim 14 or an antistatic hard coat film comprising a triacetyl cellulose substrate, and a hard coat layer formed on the triacetyl cellulose substrate, wherein the hard coat layer comprises an antistatic agent, a (meth)acrylate resin, and a polymer of a (meth)acrylate monomer, wherein the hard coat layer is a cured product of a film formed by applying a composition for producing the hard coat layer on the triacetyl cellulose substrate, the composition comprising the antistatic agent, the (meth)acrylate resin, and the (meth)acrylate monomer, the triacetyl cellulose substrate comprises a permeation layer formed by permeation of the (meth)acrylate monomer from the hard coat layer side of an interface toward the side opposite from the hard coat layer, the antistatic hard coat film satisfies Formulas (1), (2), and (3):
3 mT18 mFormula (1)
0.3Tt0.9TFormula (2)
2 mTt11 mFormula (3) where T denotes the total thickness (m) of the permeation layer and the hard coat layer, and t denotes the thickness (m) of the permeation layer on an outermost surface of the image display device, the antistatic hard coat film exhibits a haze of less than 0.5%, and the antistatic hard coat film exhibits good white muddiness resistance the antistatic hard coat film being prepared by drying the film under the drying conditions below, the drying of the film starting within 20 seconds from completion of the application of the composition; the drying conditions being: Drying temperature: 40 to 80 C.; Drying time: 20 to 70 seconds; and Air velocity for drying: 5 to 20 m/min.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a graph of Formulas (1) and (2) drawn on the coordinate plane where the horizontal axis reflects the total thickness (T) of the permeation layer and the hard coat layer of the triacetyl cellulose substrate of the antistatic hard coat film of the claimed invention and the vertical axis reflects the thickness (t) of the permeation layer.

DESCRIPTION OF EMBODIMENTS

(2) The claimed invention will be described with reference to the examples below. However, the below embodiments do not limit the interpretation of the claimed invention. Unless specifically stated otherwise, part and % are described based on mass. The amount of each material is shown in solid content, unless specifically stated otherwise.

Example 1

(3) The materials shown below were mixed to prepare a composition for producing a hard coat layer.

(4) Antistatic agent (UV-ASHC-01, Nippon Kasei Chemical Co., Ltd., weight-average molecular weight: 10,000, solids content: 50%, quaternary ammonium salt content: about 15% in the solids content, about 90% of the antistatic agent is composed of DPHA, solvent MEK, and alcohol): 3 parts by mass

(5) Dipentaerythritolhexaacrylate (DPHA, Nippon Kayaku Co., Ltd.): 87 parts by mass

(6) Urethane acrylate (UV1700B, the Nippon Synthetic Chemical Industry Co., Ltd., number of functional groups: 10, weight-average molecular weight: 2,000): 10 parts by mass

(7) Irgacure 184 (BASF): 4 parts by mass

(8) MEK (methyl ethyl ketone): 88 parts by mass

(9) IPAC (isopropyl acetate): 12 parts by mass

(10) Next, a triacetyl cellulose substrate with a thickness of 80 m (Fujifilm Corporation, TD80UL) was prepared. The obtained composition for producing a hard coat layer was applied on one surface of the triacetyl cellulose substrate to form a coating. After 8 seconds after the formation of the coating, the film was dried in a heat oven at a temperature of 50 C. and a wind velocity of 10 m/min for 60 seconds to evaporate the solvent in the coating. The coating was then irradiated with ultraviolet rays such that the accumulated light amount was 50 mJ to cure the coating. Thereby, an antistatic hard coat film was produced.

Examples 2 to 10, Comparative Examples 1 to 14

(11) An antistatic hard coat film was produced in the same manner as in Example 1 except that the materials and the blending amount thereof were changed according to Table 1. The ingredients of the materials shown in Table 1 are as follows.

(12) M-8030: polyfunctional polyester acrylate

(13) MT3506: polyfunctional polyester acrylate, Toagosei Co., Ltd.

(14) BS577: urethane acrylate, Arakawa Chemical Industries, Ltd., number of functional groups: 6, weight-average molecular weight: 1,000 (PETA occupies 60% of the solids content)

(15) IPA: isopropyl alcohol

(16) n-BuOH: n-butanol

(17) MIBK: methyl isobutyl ketone

Example 11

(18) A triacetyl cellulose substrate with a thickness of 80 m (Fujifilm Corporation, TD80UL) was prepared. The composition for producing a hard coat layer having the formulation shown in Table 1 was applied on one surface of the triacetyl cellulose substrate to form a coating.

(19) After 8 seconds after the formation of the coating, the film was dried in a heat oven at a temperature of 70 C. and a wind velocity of 10 m/min for 60 seconds to evaporate the solvent in the coating. Then, the coating was irradiated with ultraviolet rays such that the accumulated light amount was 50 mJ to cure the coating. Thereby, an antistatic hard coat film was produced.

(20) The obtained antistatic hard coat films were evaluated by the following methods. Table 1 shows the results.

(21) (Evaluation 1: Surface Resistivity)

(22) The surface resistivity (/) of each film was measured with an applied voltage of 500 V using a surface resistivity meter (Mitsubishi Chemical Corporation, product number: Hiresta IP MCP-HT260).

(23) (Evaluation 2: Occurrence of White Muddiness)

(24) Occurrence of white muddiness was evaluated for each film by irradiating light from the opposite side of the hard coat layer side of each antistatic hard coat film and visually observing the occurrence of white muddiness from the hard coat layer side by the transmitted light. The antistatic hard coat film was evaluated as good when it had no white muddiness and was in good state; and was evaluated as poor when it had white muddiness.

(25) (Evaluation 3: Occurrence of Interference Fringe Pattern)

(26) A black tape was attached on the opposite side of the hard coat layer side of each antistatic hard coat film to prevent back reflection. The antistatic hard coat film was visually observed from the hard coat layer side, to evaluate the occurrence of an interference fringe pattern. The antistatic hard coat film was evaluated as good when it had no interference fringe pattern and was in good state; and was evaluated as poor when it had an interference fringe pattern.

(27) (Evaluation 4: Thickness (t) of Permeation Layer)

(28) Each antistatic hard coat film was cut in the thickness direction and the cut section was observed with a scanning electron microscope (SEM) to measure the thickness (t) of the permeation layer.

(29) In addition, the total thickness T (m) of the hard coat layer and the permeation layer was also measured.

(30) Specifically, the antistatic hard coat film was embedded in a thermosetting resin and then an extremely thin slice was prepared with a microtome. The extremely thin slice was dyed in OsO.sub.4 (osmium oxide) for a couple of minutes, and then carbon was deposited thereon to produce a sample for measurement of the permeation layer.

(31) The sample was measured using a scanning electron microscope (SEM) under the conditions of accelerating voltage: 30 kV, emission current: 10 A, and magnification: 50 k, to determine the thickness of the permeation layer.

(32) (Evaluation 5: Pencil Hardness Test)

(33) After each antistatic hard coat film was conditioned at a temperature of 25 C. and a relative humidity of 60% for 2 hours, the test was performed at a load of 4.9 N using test pencils specified by JIS-S-6006 (hardness: H to 3 H) according to the pencil hardness evaluation method prescribed in JIS K5600-5-4 (1999). A hardness of 2 H or more was evaluated as good.

(34) (Evaluation 6: Total Light Transmittance)

(35) The total light transmittance (%) was measured for each film using a haze meter (Murakami Color Research Laboratory Co., Ltd., product number: HM-150) according to JIS K-7361.

(36) (Evaluation 7: Haze)

(37) The haze value (%) was measured for each film using a haze meter (Murakami Color Research Laboratory Co., Ltd., product number: HM-150) according to JIS K-7136.

(38) (Evaluation 8: Curl)

(39) Each antistatic hard coat film was cut into a size of 100 mm100 mm to prepare a sample. Each sample was placed on a horizontal table with the hard coat layer side up, and its curled corners were observed. The average value of the heights from the table to the respective corners was calculated. The evaluation was carried out according to the following criteria: The height of the curled corner was lower than 40 mm: good The height of the curled corner was 40 mm or higher: poor

(40) [Table 1]

(41) TABLE-US-00001 Total Thickness Permeable thickness of of hard Antistatic agent Resin Initiator solvent Nonpermeable solvent the film coat layer (parts by mass) (parts by mass) (parts by mass) (parts by mass) (parts by mass) (m) (m) Example 1 UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 6 3 87 10 4 88 12 Example 2 UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 7 3 87 10 4 80 20 Example 3 UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 3 3 87 10 4 90 10 Example 4 UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 6 4 3 87 10 4 88 12 Example 5 UV-ASHC-01 DPHA UV17OOB Irgaoure 184 MEK Butyl acetate 15 9 3 87 10 4 86 12 Example 6 UV-ASHC-01 DPHA BS577 Irgacure 184 MEK IPAC 10 6 3 87 10 4 88 12 Example 7 UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC IPA n-BuOH 10 6 3 87 10 4 82 7 3 8 Example 8 UV-ASHC-01 DPHA BS577 Irgacure 184 Methyl acetate IPAC 10 6 4 87 10 4 88 12 Example 9 UV-ASHC-01 M-8030 UV17OOB Irgacure 184 MEK Diethyl ketone 10 6 3 87 10 4 88 12 Example 10 UV-ASHC-01 M-9050 UV17OOB Irgacure 184 Cyclohexanone IPAC 10 6 3 87 10 4 88 12 Example 11 UV-ASHC-01 DPHA UV17OOB Irgacure 184 Acetone IPAC 10 6 3 87 10 4 88 12 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 0.5 Example 1 3 87 10 4 98 2 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK MIBK 10 0.5 Example 2 3 87 10 4 98 2 Comparative UV-ASHC-01 DPHA BS577 Irgacure 184 MEK MIBK 10 0.5 Example 3 3 87 10 4 98 2 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 9 Example 4 3 87 10 4 30 70 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 9 Example 5 3 87 10 4 0 100 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK Diethyl ketone 10 9 Example 6 3 87 10 4 30 70 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 6 Example 7 0 88 12 4 88 12 Comparative H6500 DPHA UV17OOB Irgacure 184 Methyl acetate IPAC 2 1 Example 8 3 87 10 4 88 12 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 2 1.5 Example 9 3 87 10 4 80 20 Comparative H6500 DPHA UV17OOB Irgacure 184 MEK Butyl acetate 19 12 Example 10 3 87 10 4 88 12 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC IPA n-BuOH 19 12 Example 11 4 88 8 4 88 7 3 2 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 6 Example 12 3 35 62 4 88 12 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 6 Example 13 3 0 97 4 88 12 Comparative UV-ASHC-01 DPHA UV17OOB Irgacure 184 MEK IPAC 10 6 Example 14 3 97 0 4 88 12 Evaluation 1 Evaluation 3 Evaluation 4 Surface Interference Thickness of Evaluation 5 Evaluation 6 resistivity Evaluation 2 fringe permeation Pencil Total light Evaluation 7 Evaluation 8 (/sq) Bleaching pattern layer (m) hardness transmittance (%) Haze (%) Curl Example 1 10.sup.9 good good 4 2 H 92 0.3 good Example 2 .sup.10.sup.10 good good 3 2 H 92 0.3 good Example 3 10.sup.9 good good 7 2 H 92 0.3 good Example 4 10.sup.9 good good 2 2 H 92 0.3 good Example 5 .sup.10.sup.10 good good 6 2 H 92 0.3 good Example 6 10.sup.9 good good 4 2 H 92 0.3 good Example 7 10.sup.9 good good 4 2 H 92 0.3 good Example 8 10.sup.8 good good 4 2 H 92 0.3 good Example 9 10.sup.9 good good 4 2 H 92 0.3 good Example 10 10.sup.9 good good 4 2 H 92 0.3 good Example 11 10.sup.9 good good 4 2 H 92 0.3 good Comparative ND poor good 9.5 2 H 92 0.5 good Example 1 Comparative ND poor good 9.5 2 H 92 0.5 good Example 2 Comparative ND poor good 9.5 2 H 92 0.5 good Example 3 Comparative Over good poor 1 2 H 92 0.3 good Example 4 Comparative Over good poor 1 2 H 92 0.3 good Example 5 Comparative Over good poor 1 2 H 92 0.3 good Example 6 Comparative Over good poor 4 2 H 92 0.3 good Example 7 Comparative ND poor good 1 H 92 0.5 gcod Example 8 Comparative 10.sup.9 good good 0.5 H 92 0.3 good Example 9 Comparative 10.sup.9 good good 7 2 H 92 0.3 poor Example 10 Comparative 10.sup.9 good good 7 2 H 92 0.3 poor Example 11 Comparative .sup.10.sup.12 good poor 1 2 H 92 0.3 good Example 12 Comparative OVER good poor 0.5 2 H 92 0.3 good Example 13 Comparative 10.sup.8 poor good 9.5 H 92 0.5 good Example 14 ND: Below the measurement limit

(42) As shown in Table 1, good results were obtained in all the evaluation items for the antistatic hard coat films of the examples satisfying Formula (1): 3 mT18 m; Formula (2): 0.3 Tt0.9 T; and Formula (3): 2 mTt11 m, wherein T denotes the total thickness (m) of the permeation layer and the hard coat layer, and t denotes the thickness (m) of the permeation layer.

(43) In contrast, white muddiness was observed in the antistatic hard coat films of Comparative Examples 1 to 3 not satisfying the right-hand side of Formula (2) and the left-hand side of Formula (3). The surface resistivity was high and an interference fringe pattern was also appeared in the antistatic hard coat films of Comparative Examples 4 to 6 not satisfying the left-hand side of Formula (2) and the antistatic hard coat film of Comparative Example 7 containing no antistatic agent. The pencil hardness was poor in the antistatic hard coat films of Comparative Examples 8 and 9 not satisfying the left-hand side of Formula (1) and the left-hand side of Formula (3), and white muddiness was further observed in the antistatic hard coat film of Comparative Example 8. Large curls were observed in the antistatic hard coat films of Comparative Examples 10 and 11 not satisfying the right-hand side of Formula (1) and the right-hand side of Formula (3). An interference fringe pattern appeared in the antistatic hard coat films of Comparative Examples 12 and 13 not satisfying the left-hand side of Formula (2), and white muddiness appeared in the antistatic hard coat film of Comparative Example 14 not satisfying the right-hand side of Formula (2).

(44) Here, when an antistatic hard coat film was produced in the same manner as in Example 1, except for changing the drying conditions of the coating formed from the composition for producing a hard coat layer to: drying temperature of 100 C., drying time of 80 seconds, and wind velocity of 30 m/min, the thickness of the permeation layer did not satisfy the left-hand side of Formula (2).

INDUSTRIAL APPLICABILITY

(45) The antistatic hard coat film of the claimed invention contains a triacetyl cellulose substrate, a hard coat layer, and a permeation layer, each of which has the mentioned features. Therefore, the antistatic hard coat film is extremely excellent in white muddiness resistance and antistatic properties, and can sufficiently prevent an interference fringe pattern. Accordingly, the antistatic hard coat film of the claimed invention can be appropriately used for cathode ray tube displays (CRT), liquid crystal displays (LCD), plasma display panels (PDP), electroluminescence displays (ELD), field emission displays (FED), and the like.