Hard coating film

Abstract

A hard coating film comprising a base layer including: a polymer binder resin; first inorganic particles dispersed in the polymer binder resin and having an average particle size of 5 nm or more and less than 70 nm; and second inorganic particles which are dispersed in the polymer binder resin and have an average particle size of 70 nm to 150 nm is provided.

Claims

1. A hard coating film comprising a hard coating base layer, the hard coating base layer including: a polymer binder resin; first inorganic particles dispersed in the polymer binder resin and having an average particle size of 5 nm or more and less than 70 nm; and second inorganic particles dispersed in the polymer binder resin and having an average particle size of 70 nm to 150 nm, wherein a content of the first inorganic particles is 1% by weight to 4% by weight with respect to 100% by weight of the hard coating base layer, wherein a content of the second inorganic particles having an average particle size of 70 nm to 150 nm is 4% by weight to 12% by weight with respect to 100% by weight of the hard coating base layer, wherein an average value of a distance between one surface of the hard coating base layer and the center of each of the second inorganic particles in a direction perpendicular to the one surface of the hard coating base layer is 35 nm to 5.0 m, and the second inorganic particles are adjacent to each other in a horizontal direction with respect to the one surface of the hard coating base layer and spaced apart by an average value of a distance of 0.1 m to 1.5 m, the distance being determined as an average of the distance between centers of one second inorganic particle and an adjacent second inorganic particle, wherein the second inorganic particles are dispersed in the polymer binder resin with no agglomeration, wherein the first inorganic particles and the second inorganic particles each consist of the same one or more reactive functional group on a surface thereof, and wherein the reactive functional group forms a crosslinking bond with the polymer binder resin.

2. The hard coating film of claim 1, wherein the second inorganic particles are present inside the hard coating film.

3. The hard coating film of claim 1, wherein the reactive functional group is selected from the group consisting of a (meth)acrylate group, an epoxide group, a vinyl group, and a thiol group.

4. The hard coating film of claim 1, wherein the reactive functional group is a silane compound or a hydroxide compound, each including one or more reactive functional groups selected from the group consisting of a (meth)acrylate group, an epoxide group, a vinyl group, and a thiol group.

5. The hard coating film of claim 1, further comprising a fluorine-based compound including a reactive functional group, the reactive functional group forming a crosslinking bond with the polymer binder resin.

6. The hard coating film of claim 1, wherein the first inorganic particles and the second inorganic particles are one or more selected from the group consisting of silica and a metal oxide.

7. The hard coating film of claim 1, wherein at least one surface of the hard coating base layer has at least two unevennesses, and the unevennesses have a height of 1 nm to 50 nm.

8. The hard coating film of claim 7, wherein an average distance between the unevennesses is 0.1 m to 1.5 m.

9. The hard coating film of claim 1, wherein a thickness of the hard coating base layer is 500 nm to 30 m.

10. The hard coating film of claim 1, wherein in a graph of measurement of static and kinetic friction forces with a TAC(triacetyl cellulose) film measured using a Friction Tester, by: applying a sled bearing a load of 400 g to a surface of the hard coating film, pulling the sled at a test speed of 18 cm/min for a test distance of 10 cm, measuring the static and kinetic friction forces, and, using the measurements in the section from 3 cm to 10 cm on the graph, determining an average friction force, a maximum friction force, and a minimum friction force, and determining a maximum amplitude (A) as a maximum value of the absolute values of difference between the average friction force and a maximum friction force and the difference between the average friction force and a minimum friction force, wherein the maximum amplitude (A) measured in the section from 3 cm to 10 cm on the graph is 0.15 or less.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 is a cross-sectional transmission electron microscopic image of a hard coating film according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) The present invention will be described in more detail in the following examples. However, the following examples are for illustrative purposes only, and the content of the present invention is not intended to be limited thereby.

EXAMPLES AND COMPARATIVE EXAMPLES: MANUFACTURE OF HARD COATING FILM

Example 1

(3) Solid components of 91 g of pentaerythritol triacrylate (PETA), 3 g of first silica particles having an average particle size of 23 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 4 g of second silica particles having an average particle size of 132 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.05 g of fluorine-based acrylate (RS-537, DIC), and 1.95 g of a photo-initiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent at a solid concentration of 45% by weight to prepare a composition for a base layer.

(4) A triacetyl cellulose film was coated with the composition using a #10 Mayer bar, dried at 60 C. for 1 minute, and irradiated with UV at a dose of 150 mJ/cm.sup.2 to manufacture a hard coating film having a thickness of about 5 m to about 6 m.

Example 2

(5) Solid components of 80 g of pentaerythritol triacrylate (PETA), 7 g of first silica particles having an average particle size of 15 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 11 g of second silica particles having an average particle size of 110 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.1 g of fluorine-based acrylate (RS-537, DIC), and 1.9 g of a photo-initiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent at a solid concentration of 44% by weight to prepare a composition for a base layer.

(6) A hard coating film was manufactured using the above composition in the same manner as in Example 1.

Example 3

(7) Solid components of 85 g of pentaerythritol triacrylate (PETA), 4 g of first silica particles having an average particle size of 23 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 9 g of second silica particles having an average particle size of 132 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.05 g of fluorine-based acrylate (RS-537, DIC), and 1.95 g of a photo-initiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent at a solid concentration of 44% by weight to prepare a composition for a base layer.

(8) A hard coating film was manufactured using the above composition in the same manner as in Example 1.

Example 4

(9) Solid components of 41.2 g of pentaerythritol triacrylate (PETA), 41.2 g of dipentaerythritol hexaacrylate (DPHA), 12 g of first silica particles having an average particle size of 15 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 4 g of second silica particles having an average particle size of 82 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.1 g of fluorine-based acrylate (RS-537, DIC), and 1.5 g of a photo-initiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent at a solid concentration of 45% by weight to prepare a composition for a base layer.

(10) A hard coating film was manufactured using the above composition in the same manner as in Example 1.

Example 5

(11) Solid components of 91 g of pentaerythritol triacrylate (PETA), 3 g of first silica particles having an average particle size of 23 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 4 g of second silica particles having an average particle size of 132 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.05 g of fluorine-based acrylate (RS-537, DIC), and 1.95 g of a photo-initiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent at a solid concentration of 45% by weight to prepare a composition for a base layer.

(12) A hard coating film was manufactured using the above composition in the same manner as in Example 1.

Example 6

(13) Solid components of 87 g of pentaerythritol triacrylate (PETA), 7 g of first silica particles having an average particle size of 15 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 4 g of second silica particles having an average particle size of 110 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.1 g of fluorine-based acrylate (RS-537, DIC), and 1.9 g of a photo-initiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent at a solid concentration of 44% by weight to prepare a composition for a base layer.

(14) A hard coating film was manufactured using the above composition in the same manner as in Example 1.

Example 7

(15) Solid components of 89 g of pentaerythritol triacrylate (PETA), 4 g of first silica particles having an average particle size of 23 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 5 g of second silica particles having an average particle size of 132 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.05 g of fluorine-based acrylate (RS-537, DIC), and 1.95 g of a photo-initiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent at a solid concentration of 44% by weight to prepare a composition for a hard coating film.

(16) A hard coating film was manufactured using the above composition in the same manner as in Example 1.

Comparative Example 1

(17) A composition and a hard coating film were prepared in the same manner as in Example 1, except that 1 g of the second silica particles and 93 g of pentaerythritol triacrylate (PETA) were used.

Comparative Example 2

(18) A composition and a hard coating film were prepared in the same manner as in Example 1, except that 16 g of the second silica particles and 78 g of pentaerythritol triacrylate (PETA) were used.

Comparative Example 3

(19) A composition and a hard coating film were prepared in the same manner as in Example 1, except that 13 g of the second silica particles and 81 g of pentaerythritol triacrylate (PETA) were used.

Comparative Example 4

(20) A composition and a hard coating film were prepared in the same manner as in Example 5, except that 4 g of pentaerythritol triacrylate (PETA) was used instead of the second silica particles in Example 5.

Comparative Example 5

(21) A composition and a hard coating film were prepared in the same manner as in Example 6, except that second silica particles having an average particle size of 200 nm were used instead of the second silica particles having an average particle size of 110 nm in Example 6.

Comparative Example 6

(22) A composition and a hard coating film were prepared in the same manner as in Example 6, except that non-surface treated second silica particles were used in Example 6.

Comparative Example 7

(23) A composition and a hard coating film were prepared in the same manner as in Example 6, except that second silica particles having an average particle size of 50 nm were used instead of the second silica particles having an average particle size of 110 nm in Example 6.

EXPERIMENTAL EXAMPLE: MEASUREMENT OF PHYSICAL PROPERTIES OF HARD COATING FILM

(24) Experiments of the following items were performed with respect to the hard coating films obtained in the examples and comparative examples. Further, measurement results are shown in the following Table 1.

(25) 1. Measurement of Scratch Resistance

(26) Each surface of the hard coating films obtained in the examples and comparative examples was doubly rubbed at a speed of 27 rpm 10 times with steel wool (#0000) under a load. The maximum load under which one or fewer scratches of 1 cm or less was observed with the naked eye was measured.

(27) 2. Measurement of Pencil Hardness

(28) Pencil hardness of each of the hard coating films obtained in the examples and comparative examples was evaluated with a pencil tester in accordance with ASTM D3363.

(29) 3. Measurement of Haze

(30) Haze was measured at three spots of each of the hard coating films obtained in the examples and comparative examples using HAZEMETER HM-150 of Murakami Color Research Laboratory in accordance with the JIS K7105 standard, and it was examined whether a mean value was 0.5 or less.

(31) 4. Measurement of Friction Force

(32) A TAC (triacetyl cellulose) film was placed on the surface of each of the hard coating films obtained in the examples and comparative examples, and a friction force was measured for a total test distance of 10 cm at a test speed of 18 cm/min while applying a load of 400 g thereto. A graph for the friction force was obtained. Specifically, the friction force measurement graph was obtained by contacting the TAC film with the surface of the hard coating film, putting a sled with a load of 400 g thereon, and then measuring a friction force while pulling the sled for a total test distance of 10 cm at a test speed of 18 cm/min using a friction tester (FP-2260, manufactured by Thwing-Albert Instrument Company). Thereafter, an average friction force, a maximum friction force, and a minimum friction force were obtained in a kinetic test distance section in the obtained friction force measurement graph, and then a maximum value of the absolute values of the differences between the average friction force and the maximum friction force or the minimum friction force was defined as a maximum amplitude (A). In this regard, the static test distance is a section up to a test distance of 3 cm, and the kinetic test distance is a section from a test distance of 3 cm to a test distance of 10 cm.

(33) 5. Evaluation of Presence or Absence of Blocking Generation

(34) A TAC film was placed on the surface of each of the hard coating films obtained in the examples and comparative examples, a weight of 3 kg was put thereon, and then left for 24 hours. Thereafter, it was examined whether the hard coating film and the TAC film adhered to each other.

(35) 6. Measurement of Average Distance between Second Inorganic Particles

(36) The hard coating films obtained in the examples and comparative examples were photographed under a transmission electron microscope (TEM) at 2500 magnification, and based on the photographed image, a distance between the centers of the second inorganic particles which were placed close to the surface of the hard coating film (a distance between one surface of the base layer and the center of the second inorganic particle in a direction perpendicular to one surface of the base layer was 35 nm to 5.0 m) was measured and an average value of the distances was calculated.

(37) FIG. 1 is a cross-sectional TEM (transmission electron microscope) image of the hard coating film of the present invention at 2500 magnification. According to this image, at least three second inorganic particles showed that the distance between one surface of the base layer and the center of the second inorganic particle in a direction perpendicular to one surface of the hard coating film was 35 nm to 5.0 m, and a length of an arrow which indicates the distance between the centers of the second inorganic particles was measured to determine the distance between the second inorganic particles. An average value of respective measurement values was calculated to determine an average distance between the second inorganic particles.

(38) TABLE-US-00001 TABLE 1 Scratch Pencil Maximum Blocking Average distance resistance (g) hardness Haze amplitude (A) generation between particles Example 1 1000 3H 0.1 0.04 X 1 m Example 2 1000 3H 0.2 0.03 X 0.2 m Example 3 1000 3H 0.3 0.04 X 0.35 m Example 4 1000 3H 0.2 0.05 X 1 m Example 5 1000 3H 0.2 0.03 X 1 m Example 6 1000 3H 0.2 0.04 X 1 m Example 7 1000 3H 0.4 0.1 X 0.9 m Comparative 1000 3H 0.2 0.25 2 m Example 1 Comparative 1000 3H 0.7 0.1 X 10 nm Example 2 Comparative 1000 3H 0.6 0.11 X 200 nm Example 3 Comparative 1000 3H 0.2 0.48 Example 4 Comparative 1000 3H 0.7 0.15 X Example 5 Comparative 1000 3H 0.6 0.17 Example 6 Comparative 1000 3H 0.2 0.3 Example 7

(39) According to Table 1, the hard coating films of Examples 1 to satisfied that the average distance between the second inorganic particles was 500 nm to 1.5 m, and thus they were found to have low haze and an excellent anti-blocking effect.

(40) 7. XPS (X-Ray Photoelectron Spectroscopy) Analysis

(41) The surface of the hard coating film of Example 1 was analyzed by XPS, and the results are shown in the following Table 2.

(42) TABLE-US-00002 TABLE 2 Component F O C Si Content (at %) 12.0 30.9 49.5 7.6

(43) According to Table 2, it was confirmed that carbon (C) and oxygen (O) which are components of the polymer binder were mainly detected on the surface of the hard coating film of Example 1, suggesting that the inorganic particles were not exposed to the outside of the hard coating film.

(44) 8. Measurement of Diameter of Inorganic Particles Using Transmission Electron Microscope (TEM)

(45) Diameter of inorganic nanoparticles in the hardcoating film was measured by using Transmission Electron Microscopy (TEM) in the magnitude of 100,000. The hard coating film was embedded into the epoxy resin, and sliced with an ultramicrotome (thickness of 150 nm). After transferred onto a Cu grid, five images of inorganic nanoparticles were captured. The diameter of each inorganic nanoparticle of five images was measured and the average value was calculated.