JP7395244B2 - Hard coat film and transparent conductive film - Google Patents

Description

The present invention relates to a hard coat film and a transparent conductive film, and specifically relates to a hard coat film and a transparent conductive film including the hard coat film.

Conventionally, hard coat films having a hard coat layer on one side of a transparent resin substrate are known.

For example, a hard coat film including a hard coat layer having an elastic modulus of 2.1 to 5.0 GPa has been proposed (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2014-25061

However, the hard coat layer is required to have excellent bending resistance, but in the hard coat film described in Patent Document 1, the elastic modulus of the hard coat layer is as high as 2.1 to 5.0 GPa. Unable to fully satisfy requirements.

On the other hand, hard coat films are also required to have excellent scratch resistance.

Furthermore, the hard coat film is required to be flexible while having excellent bending resistance and scratch resistance.

The present invention provides a hard coat film that has both excellent bending resistance and scratch resistance, and excellent flexibility, and a transparent conductive film equipped with the same.

The present invention (1) comprises a transparent base material and a hard coat layer in order in the thickness direction, the hard coat layer includes a resin matrix and particles, and the hard coat layer has a hardness measured by a nanoindentation method. The hard coat film includes a hard coat film having a hardness of 0.320 GPa or more and 0.520 GPa or less, and a pencil hardness of the hard coat layer of B or less.

The present invention (2) includes the hard coat film according to (1), wherein the hard coat layer has a thickness of 3 μm or less.

The present invention (3) includes the hard coat film according to (1) or (2), wherein the hard coat layer has an arithmetic mean roughness Ra of 3 nm or more and 14 nm or less.

The present invention (4) includes the hard coat film according to any one of (1) to (3), wherein the material of the transparent base material is a cycloolefin polymer.

The present invention (5) includes a transparent conductive film comprising the hard coat film according to any one of (1) to (4), an optical adjustment layer, and a transparent conductive layer in this order in the thickness direction.

The hard coat film and transparent conductive film of the present invention have excellent durability because the hard coat layer has a hardness of 0.320 GPa or more and 0.520 GPa or less and a pencil hardness of B or less. It combines flexibility, scratch resistance, and excellent flexibility.

FIG. 1 shows a cross-sectional view of one embodiment of the hard coat film of the present invention. FIG. 2 shows a cross-sectional view of a transparent conductive film including the hard coat film shown in FIG.

One embodiment of the hard coat film of the present invention will be described with reference to FIG.

The hard coat film 1 has one surface and the other surface (two main surfaces) that are spaced apart from each other in the thickness direction and are opposed to each other. One side and the other side of the hard coat film 1 are flat surfaces parallel to each other. The hard coat film 1 has a substantially film shape extending in a plane direction perpendicular to the thickness direction.

The hard coat film 1 is, for example, one component included in a transparent conductive film 6 (see FIG. 2), which will be described later, and is therefore not the transparent conductive film 6. That is, the hard coat film 1 is a component for producing the transparent conductive film 6, does not include the optical adjustment layer 4 and the transparent conductive layer 5, is distributed as a component alone, and is an industrially usable device.

The hard coat film 1 includes a transparent base material 2 and a hard coat layer 3 in this order toward one side in the thickness direction. That is, the hard coat film 1 includes the transparent base material 2 and the hard coat layer 3 disposed on one side of the transparent base material 2 in the thickness direction. Moreover, preferably, the hard coat film 1 consists of only the transparent base material 2 and the hard coat layer 3.

Transparent base material 2 forms the other surface of hard coat film 1 . Specifically, the transparent base material 2 is a support material that ensures the mechanical strength of the hard coat film 1. The transparent base material 2 has a film shape extending in the plane direction. The transparent base material 2 has one side and the other side that are arranged to face each other at intervals in the thickness direction. One side and the other side of the transparent base material 2 are flat surfaces parallel to each other. The other surface of the transparent base material 2 in the thickness direction is exposed on the other side in the thickness direction.

The material of the transparent base material 2 is not particularly limited as long as it is transparent. Examples of the material for the transparent base material 2 include resins (including polymers). Examples of resins include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; (meth)acrylic resins (acrylic resins and/or methacrylic resins) such as polymethacrylate; for example, polyethylene, polypropylene, and cycloolefins. Olefin resins such as polymers (COP), e.g. polycarbonate resins, e.g. polyethersulfone resins, e.g. polyarylate resins, e.g. melamine resins, e.g. polyamide resins, e.g. polyimide resins, e.g. cellulose resins, e.g. polystyrene. Examples include resins such as norbornene resins. These resins can be used alone or in combination of two or more. From the viewpoint of ensuring excellent optical properties (including transparency), olefin resins are preferably used, and COP is more preferably used.

COP has excellent optical properties (isotropy) compared to polyester resin. On the other hand, COP has lower mechanical strength (easier to break) than polyester resin. However, since this hard coat film 1 includes a hard coat layer 3 having desired hardness and pencil hardness, even if the mechanical strength of the transparent substrate 2 is low, the hard coat film 1 has a large decrease in mechanical strength. (occurrence of cracks) can be suppressed.

The total light transmittance (JIS K 7375-2008) of the transparent base material 2 is, for example, 80% or more, preferably 85% or more.

The thickness of the transparent base material 2 is the length between one side and the other side (the same applies to each layer below), and specifically, for example, 2 μm or more, preferably 20 μm or more, and, for example, It is 300 μm or less, preferably 200 μm or less.

Hard coat layer 3 forms one side of hard coat film 1 . Specifically, the hard coat layer 3 is a hard layer that provides the hard coat film 1 with excellent bending resistance and also ensures excellent scratch resistance. Further, the hard coat layer 3 is also an anti-blocking layer that provides blocking resistance to the hard coat film 1. The hard coat layer 3 has a film shape extending in the surface direction. The hard coat layer 3 has one side and the other side that are spaced apart from each other in the thickness direction and are opposed to each other. The other surface of the hard coat layer 3 is in contact with one surface of the transparent base material 2. One surface of the hard coat layer 3 is exposed, for example, on one side in the thickness direction of the hard coat film 1, and has a fine uneven shape (not shown in FIG. 1).

Hard coat layer 3 contains resin and particles. Hard coat layer 3 preferably contains only resin and particles. Specifically, the material of the hard coat layer 3 is a composition containing resin and particles.

The resin is not particularly limited as long as it is a transparent resin, and examples include curable resins and thermoplastic resins, preferably curable resins, and more preferably photocurable resins. Examples of the photocurable resin include acrylic resin, epoxy resin, silicone resin, etc., and preferably acrylic resin from the viewpoint of ensuring excellent optical properties and excellent mechanical strength. These resins can be used alone or in combination of two or more.

The material of the particles is not particularly limited as long as it is transparent, and examples thereof include organic materials and inorganic materials. Examples of the organic material include polymers such as acrylic polymers and polystyrene, and preferably acrylic polymers. Examples of inorganic materials include silica, metal oxides such as zirconium oxide, titanium oxide, zinc oxide, and tin oxide, and carbonates such as calcium carbonate. Preferably, silica is used. These materials can be used alone or in combination of two or more.

The shape of the particles is not particularly limited, and includes, for example, a substantially spherical shape, a substantially needle shape, a substantially plate shape, an irregular shape, etc., and preferably a substantially spherical shape.

The average value of the maximum length of the particles (in the case of a substantially spherical shape, the average particle diameter) is preferably relatively small, and more preferably nano-sized. Specifically, the average value of the maximum length of the particles is, for example, 100 nm or less, preferably 80 nm or less, more preferably 60 nm or less, and also, for example, 1 nm or more, preferably 5 nm or more, more preferably is 10 nm or more.

If the average value of the maximum length of the particles is below the above-mentioned upper limit, the arithmetic mean roughness Ra of one side of the hard coat layer 3, which will be described later, can be easily and reliably set within a desired range.

If the average value of the maximum length of the particles is at least the above-described lower limit, excellent anti-blocking properties can be imparted to the hard coat film 1.

Note that the hard coat layer 3 is formed from the above-mentioned composition and includes a resin matrix and particles dispersed therein.

The number of parts by mass of the particles is, for example, 0.1 parts by mass or more, preferably 1 part by mass or more, and, for example, 75 parts by mass or less, preferably 55 parts by mass or less, based on 100 parts by mass of the resin. be.

The hardness of the hard coat layer 3 is 0.320 GPa or more, preferably 0.350 GPa or more, more preferably 0.360 GPa or more. If the hardness of the hard coat layer 3 is below the above-mentioned lower limit, the hard coat film 1 will not be able to ensure excellent scratch resistance.

The hardness of the hard coat layer 3 is 0.520 GPa or less, preferably 0.500 GPa or less, more preferably 0.450 GPa or less, still more preferably 0.400 GPa or less, particularly preferably 0.370 GPa or less. It is. When the hardness of the hard coat layer 3 exceeds the above-mentioned upper limit, the hard coat film 1 cannot ensure excellent bending resistance.

The hardness of the hard coat layer 3 is the indentation hardness at 23°C measured by the nanoindentation method, and specifically, it is obtained by pushing a nanoindenter (indenter) into the hard coat layer 3 at 23°C. It is the indentation hardness. Details of the hardness measurement method will be described in later examples.

Further, the pencil hardness of the hard coat layer 3 is B or less, preferably 2B or less, more preferably 3B or less, still more preferably 4B or less, particularly preferably 5B or less.
Note that the pencil hardness of the hard coat layer 3 is, for example, 10B or more, and further, 9B or more.

When the pencil hardness of the hard coat layer 3 exceeds the upper limit (B) described above (exceeds B), excellent flexibility of the hard coat layer 3 cannot be ensured.

The pencil hardness of the hard coat layer 3 is measured according to JIS K5600-5-4 "Scratch hardness (pencil method)" (1999).

The arithmetic mean roughness Ra of one side of the hard coat layer 3 is, for example, 1 nm or more, preferably 3 nm or more, more preferably 5 nm or more, and is, for example, 20 nm or less, preferably 14 nm or less, more preferably is 12 nm or less.

If the arithmetic mean roughness Ra of one side of the hard coat layer 3 is at least the above-mentioned lower limit, excellent anti-blocking properties can be imparted to the hard coat film 1.

If the arithmetic mean roughness Ra of one side of the hard coat layer 3 is below the above-mentioned upper limit, an increase in haze of the hard coat film 1 can be suppressed and excellent transparency can be ensured.

The arithmetic mean roughness Ra of the hard coat layer 3 is measured according to JIS B 0601 (2013).

Hard coat layer 3 is preferably relatively thin. Specifically, the thickness of the hard coat layer 3 is, for example, less than 10 μm, preferably 9 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, particularly preferably 3 μm or less, and most preferably 2 μm. It is as follows. If the thickness of the hard coat layer 3 is equal to or less than the above-mentioned upper limit, excellent bending resistance can be ensured.

Further, the thickness of the hard coat layer 3 is, for example, 0.001 μm or more, preferably 0.01 μm or more, more preferably 0.1 μm or more, and still more preferably 0.5 μm or more. If the thickness of the hard coat layer 3 is at least the above-mentioned lower limit, the scratch resistance of the hard coat layer 3 can be improved.

The thickness of the hard coat layer 3 is measured using an instantaneous multi-photometry system "MCPD2000" (trade name) manufactured by Otsuka Electronics.

When the hard coat film 1 has a thickness of 101 μm, the haze is, for example, less than 0.5, preferably 0.40 or less, more preferably 0.30 or less, still more preferably 0.20 or less, particularly preferably , 0.15 or less, and usually 0.01 or more.

If the haze of the hard coat film 1 is below the above-mentioned upper limit, the hard coat film 1 will have excellent transparency.

The thickness of the hard coat film 1 is, for example, 150 μm or less, preferably 125 μm or less, and is, for example, 5 μm or more, preferably 10 μm or more.

To manufacture this hard coat film 1, for example, first, a transparent base material 2 is prepared, and then a composition is placed on one side of the transparent base material 2 in the thickness direction, for example, by a wet method.

Specifically, first, a coating liquid (varnish) is prepared by diluting the composition with a solvent. A mixture (commercially available) in which particles are dispersed in a resin can be prepared directly as a coating liquid, or it can also be prepared by mixing particles and a resin and dispersing the particles in the resin. can. Note that an initiator can be added to the coating liquid, if necessary, or a resin to which an initiator has been added in advance can also be used.

Subsequently, a coating liquid (varnish) is applied to one side of the transparent base material 2 in the thickness direction. Thereafter, the solvent is removed by heating, and then, if the composition contains a curable resin, the curable resin is cured. This forms a hard coat layer 3 in which the particles are dispersed in the resin matrix.

As a result, the hard coat layer 3 is formed on one side of the transparent base material 2 in the thickness direction.

In this way, a hard coat film 1 including a transparent base material 2 and a hard coat layer 3 is manufactured.

This hard coat film 1 is used in various industrial applications, such as optical applications such as transparent conductive films and light control films, and furthermore, electromagnetic shielding applications. Preferably, it is used for optical applications, more preferably for transparent conductive films.

Next, the transparent conductive film 6 including the hard coat film 1 will be explained with reference to FIG. 2.

The transparent conductive film 6 has one surface and the other surface (two main surfaces) that are spaced apart from each other in the thickness direction and are opposed to each other. One side and the other side of the transparent conductive film 6 are flat surfaces parallel to each other. The transparent conductive film 6 has a substantially film shape extending in the plane direction. The transparent conductive film 6 is, for example, a part of a touch panel base material or a light control panel included in an optical device (for example, an image display device, a light control device), and is not an optical device. That is, the transparent conductive film 6 is a component for producing an optical device, etc., and does not include an image display element such as an LCD module or a light source such as an LED, and is distributed as a component alone and is an industrially usable device. It is.

This transparent conductive film 6 includes a hard coat film 1, an optical adjustment layer 4, and a transparent conductive layer 5 in this order toward one side in the thickness direction. Specifically, the transparent conductive film 6 includes a transparent base material 2, a hard coat layer 3, an optical adjustment layer 4, and a transparent conductive layer 5 in this order toward one side in the thickness direction. Preferably, the transparent conductive film 6 consists of only the transparent base material 2, the hard coat layer 3, the optical adjustment layer 4, and the transparent conductive layer 5.

The optical adjustment layer 4 is formed so that the difference between the non-patterned part and the patterned part will not be recognized after the transparent conductive layer 5 is formed into a wiring pattern in a later process (that is, so as to suppress the visibility of the wiring pattern). , a layer (index matching layer) that adjusts the optical properties of the transparent conductive film 6. The optical adjustment layer 4 has a film shape extending in the plane direction, and has one side and the other side facing each other with an interval in the thickness direction. Examples of the material of the optical adjustment layer 4 include the above-described resins (not containing particles), the above-described compositions (containing particles), and the like. The thickness of the optical adjustment layer 4 is, for example, 30 nm or more, preferably 80 nm or more, and is, for example, 150 nm or less, preferably 130 nm or less.

The transparent conductive layer 5 is a conductive layer that will be formed into a wiring pattern in a later step to form a pattern portion. The transparent conductive layer 5 forms one surface of the transparent conductive film 6 in the thickness direction. The transparent conductive layer 5 has a film shape (including a sheet shape) extending in the plane direction, and has one side and the other side facing each other with an interval in the thickness direction.

The material of the transparent conductive layer 5 is, for example, at least one material selected from the group consisting of In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W. Examples include metal oxides containing metals. The metal oxide can be further doped with metal atoms shown in the above group, if necessary. Preferable examples of the material include indium tin composite oxide (ITO) and antimony tin composite oxide (ATO).

The thickness of the transparent conductive layer 5 is, for example, 10 nm or more, preferably 20 nm or more, and is, for example, 35 nm or less, preferably 30 nm or less.

The thickness of the transparent conductive film 6 is, for example, 150 μm or less, preferably 125 μm or less, and is, for example, 5 μm or more, preferably 10 μm or more.

To manufacture the transparent conductive film 6, the optical adjustment layer 4 and the transparent conductive layer 5 are sequentially arranged on one side in the thickness direction of the hard coat layer 3 of the hard coat film 1 described above by a known method.

In the hard coat film 1 and the transparent conductive film 6, since the hard coat layer 3 has a hardness of 0.320 GPa or more, excellent scratch resistance can be ensured.

Moreover, since the hardness of the hard coat layer 3 is 0.520 GPa or less, excellent bending resistance can be ensured.

Furthermore, since the pencil hardness of the hard coat layer 3 is B or less, flexibility can be ensured while having excellent bending resistance and scratch resistance.

Moreover, if the thickness of the hard coat layer 3 is 3 μm or less, excellent bending resistance can be ensured.

Further, if the arithmetic mean roughness Ra of the hard coat layer 3 is 3 nm or more and 14 nm or less, excellent anti-blocking properties can be imparted to the hard coat film 1 while ensuring excellent transparency of the hard coat film 1. be able to.

If the material of the transparent base material 2 is COP, the transparent base material 2 has excellent optical properties but has low mechanical strength (easily breaks). Since the hard coat layer 3 having hardness is provided, a large decrease in mechanical strength (occurrence of cracks) of the hard coat layer 3 in the hard coat film 1 can be suppressed.

Modification Examples In each modification example below, the same reference numerals are given to the same members and steps as in the above-described embodiment, and detailed explanation thereof will be omitted. Moreover, each modification can produce the same effects as the one embodiment except as otherwise specified. Furthermore, one embodiment and the modified examples can be combined as appropriate.

In one embodiment shown in FIG. 1, a hard coat film 1 includes a hard coat layer 3 disposed on only one side of a transparent base material 2. However, the arrangement of the hard coat layer 3 is not limited to the above, and for example, although not shown, the hard coat layer 3 may be provided on both one surface and the other surface (two main surfaces) of the transparent base material 2. You can also do it.

In one embodiment shown in FIG. 2, the transparent conductive film 6 includes a hard coat layer 3, an optical adjustment layer 4, and a transparent conductive layer 5 disposed only on one side in the thickness direction of the transparent base material 2. The arrangement of the layer 3, the optical adjustment layer 4, and the transparent conductive layer 5 is not limited to the above. An adjustment layer 4 and a transparent conductive layer 5 can also be provided.

Examples and Comparative Examples are shown below to further specifically explain the present invention. Note that the present invention is not limited to the Examples and Comparative Examples. In addition, the specific numerical values such as compounding ratios (ratios), physical property values, parameters, etc. used in the following descriptions are the corresponding compounding ratios (ratios) described in the above "Details of Carrying Out the Invention". ), physical property values, parameters, etc. can be replaced with the upper limit (a numerical value defined as "less than" or "less than") or the lower limit (a numerical value defined as "more than" or "exceeding").

Example 1
A COP film (ZEONOR ZF-16, manufactured by Nippon Zeon Co., Ltd.) with a thickness of 100 μm was prepared as the transparent base material 2.

Subsequently, a coating liquid (composition) prepared according to the recipe shown in Table 1 was applied to one side of the transparent substrate 2 using a wire bar #6, and then the solvent was removed by heating at 80°C for 1 minute. After removal, the hard coat layer 3 was formed by photocuring with an integrated light intensity of 230 mJ/cm ² . Note that details of each component listed in Table 1 are listed in Table 2.

In this way, a hard coat film 1 including a transparent base material 2 and a hard coat layer 3 was manufactured.

Example 2 to Comparative Example 2
Hard coat layer 3 was formed in the same manner as in Example 1, except that the coating liquid (composition) was changed according to the formulation shown in Table 1.

<Evaluation>
The following items were evaluated and the results are listed in Table 3.

Thickness The thickness of the hard coat layer 3 was measured using MCPD2000 (manufactured by Otsuka Electronics Co., Ltd.).

Hardness The hardness of the hard coat layer 3 was measured by the nanoindentation method.

In the nanoindentation method, a nanoindenter (probe, indenter) is pushed into one side of the hard coat layer 3, and the resulting displacement-load hysteresis curve is numerically processed using software (triboscan) attached to the measuring device. The indentation hardness was obtained.

The nanoindenter device and measurement conditions are as follows.
Nanoindenter device: "Tribo Indenter", manufactured by Hysitron Inc. Measurement method: Single indentation method Indentation speed: 60μN/sec Maximum indentation force: 300μN
Maximum pushing force holding time: 2 seconds Probe: Triangular pyramid type (Berkovich type)
Temperature: 23℃
Indentation depth: 1/10 of the thickness of hard coat layer 3
Pencil hardness The pencil hardness of the hard coat layer 3 was measured according to JIS K5600-5-4 "Scratch hardness (pencil method)" (1999).

Arithmetic mean roughness Ra
The arithmetic mean roughness Ra of the hard coat layer 3 was measured according to JIS B 0601 (2013).

Anti-blocking property Another transparent base material (ZEONOR ZF-16, manufactured by Nippon Zeon Co., Ltd.) is pressed onto the surface of the hard coat layer 3 using finger pressure to ensure that the other transparent base material sticks to the hard coat layer 3 (anti-blocking property). was evaluated as follows.
Good: Sticking of another transparent base material to the hard coat layer 3 did not occur.
Δ: Another transparent base material once stuck to the hard coat layer 3, but separated from the hard coat layer 3 after 10 seconds.
×: Another transparent base material stuck to the hard coat layer 3 and did not separate from the hard coat layer 3 even after 10 seconds had passed.

Haze The haze of Hard Coat Film 1 (thickness: 101 μm) was measured using a haze meter (HM-150, manufactured by Murakami Color Research Institute).

Flexing resistance The bending resistance of the hard coat film 1 was evaluated by a 180 degree bending test. The evaluation criteria are as follows.
○: The hard coat film 1 did not break even when it was bent 180 degrees. ×: It broke when the hard coat film 1 was bent 180 degrees. Scratch resistance One side of the hard coat film 1 in the thickness direction was rubbed 10 times with 100 g of steel wool 10 times. The scratch resistance of the hard coat film 1 was evaluated by rubbing.
The evaluation criteria are as follows.
○: Less than 10 scratches were observed ×: 10 or more scratches were observed

1 Hard coat film 2 Transparent base material 3 Hard coat layer 4 Optical adjustment layer 5 Transparent conductive layer 6 Transparent conductive film

Claims (5)

A transparent base material and a hard coat layer are provided in order in the thickness direction,
The hard coat layer includes a resin matrix and particles,
The hardness of the hard coat layer measured by a nanoindentation method is 0.320 GPa or more and 0.520 GPa or less,
A hard coat film, wherein the hard coat layer has a pencil hardness of 5B . The hard coat film according to claim 1, wherein the hard coat layer has a thickness of 3 μm or less. The hard coat film according to claim 1 or 2, wherein the hard coat layer has an arithmetic mean roughness Ra of 3 nm or more and 14 nm or less. The hard coat film according to any one of claims 1 to 3, wherein the material of the transparent base material is a cycloolefin polymer. A transparent conductive film comprising the hard coat film according to any one of claims 1 to 4, an optical adjustment layer, and a transparent conductive layer in this order in the thickness direction.

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