JP6734694B2 - Hard coat film, method for producing the same, and transparent conductive film - Google Patents

Description

The present invention relates to a hard coat film, a method for producing the same, and a transparent conductive film, more specifically, a hard coat film, a transparent conductive film having the same, and a method for producing a hard coat film.

In an image display device such as a liquid crystal display, a plasma display, an electroluminescence display, a field emission display, a touch panel, and an electronic paper, it is known to dispose an optical laminate including a light-transmitting substrate on the viewing side of a polarizer. There is.

However, when the display screen of the image display device is viewed from an angle, unevenness of different colors (hereinafter, referred to as “smooth spots”) occurs in the image display device, and there is a problem that the display quality of the liquid crystal display device is impaired.

Therefore, it is known that the use of a light-transmitting base material having a high retardation value as the light-transmitting base material can suppress the occurrence of the above-mentioned rainbow trout.

On the other hand, when a light transmissive substrate having a high retardation value is used, it is necessary to dispose a primer layer between the light transmissive substrate and the hard coat layer in order to ensure the adhesion between them.

However, in the optical laminate having the above-described structure, the reflected light at the interface between the air and the hard coat layer, the reflected light at the interface between the hard coat layer and the primer layer, and further, the primer layer and the light transmitting substrate. And the reflected light at the interface of (3) interfere with each other, resulting in fringes (interference fringes or interference unevenness).

In order to suppress the above-mentioned interference unevenness, for example, an optical layered body in which a primer layer is formed on a polyester substrate and a hard coat layer is formed on the primer layer has been proposed (for example, refer to Patent Document 1). .. In the optical layered body of Patent Document 1, the refractive index (np) of the primer layer and the refractive index (nx) of the polyester substrate in the slow axis direction and the refractive index (ny) of the fast axis direction are ny<np< nx, and the refractive index (nh) of the hard coat layer and the refractive index (nx) in the slow axis direction and the refractive index (ny) in the fast axis direction of the polyester substrate are ny<nh<nx. Have a relationship.

JP, 2013-174852, A

In recent years, there is a demand for the optical laminated body to more sufficiently suppress the interference unevenness.

An object of the present invention is to provide a hard coat film capable of sufficiently suppressing unevenness of interference, a method for producing the same, and a transparent conductive film.

The present invention (1) comprises a transparent base material having birefringence, an intermediate layer having birefringence, and a hard coat layer in order, and the transparent base material has a retardation of 8000 nm or more, The value (nsx-nsy) obtained by subtracting the refractive index nsy in the fast axis direction from the refractive index nsx in the slow axis direction of the base material exceeds 0.05, and the slow axis direction of the intermediate layer, and The slow axis direction of the transparent substrate is substantially the same direction, the fast axis direction of the intermediate layer and the fast axis direction of the transparent substrate are substantially the same direction, and , A hard coat film satisfying the following formulas [1] and [2].

nsx>nmx [1]
nsy>nmy>nh [2]
(In the formula, nsx represents the refractive index in the slow axis direction of the transparent substrate, nmx represents the refractive index in the slow axis direction of the intermediate layer, and nsy represents the fast axis of the transparent substrate. Direction, the refractive index in the fast axis direction of the intermediate layer is indicated by nmy, and the refractive index of the hard coat layer is indicated by nh.)
According to this hard coat film, the intermediate layer has birefringence, the slow axis direction of the intermediate layer and the slow axis direction of the transparent substrate are substantially the same direction, and the progress of the intermediate layer is The phase axis direction and the fast axis direction of the transparent base material are substantially the same direction and satisfy the above-described expressions [1] and [2], so that the interference unevenness can be sufficiently suppressed.

The present invention (2) includes the hard coat film according to (1), wherein the transparent substrate has a refractive index nsx in the slow axis direction of 1.80 or more.

According to this hard coat film, since the transparent substrate has the refractive index nsx in the slow axis direction which is equal to or more than the above lower limit, it is possible to effectively suppress rainbow streaks.

The present invention (3) includes the hard coat film according to (1) or (2), wherein the intermediate layer is a primer layer, and the intermediate layer has a thickness of 10 nm or more.

According to this hard coat film, since the intermediate layer is the primer layer and has a thickness not less than the above lower limit, the adhesion of the hard coat layer to the transparent substrate can be secured.

The present invention (4) includes a transparent conductive film, which is sequentially provided with the hard coat film according to any one of (1) to (3), an optical adjustment layer, and a transparent conductive layer.

Since this transparent conductive film includes the above-mentioned hard coat film, interference unevenness can be sufficiently suppressed.

In the present invention (5), a step of arranging an isotropic intermediate layer on one surface in the thickness direction of an isotropic transparent substrate to prepare a laminated substrate including the transparent substrate and the intermediate layer (1 ), a step (2) of stretching the laminated base material so as to satisfy the following condition A, and a hard coat layer on one side in the thickness direction of the intermediate layer in the laminated base material under the following conditions. A method for producing a hard coat film, which comprises sequentially arranging so as to satisfy B (3).

Condition A: The transparent substrate after stretching has a retardation of 8000 nm or more, and a value obtained by subtracting the refractive index nsy in the fast axis direction from the refractive index nsx in the slow axis direction of the transparent substrate ( nsx-nsy) exceeds 0.05.

Condition B: The refractive index nh of the hard coat layer is smaller than the refractive index nmy of the intermediate layer after stretching in the fast axis direction.

According to this method for producing a hard coat film, the simple step (2) of stretching the laminated base material imparts birefringence to both the transparent base material and the intermediate layer, and interference unevenness is sufficiently suppressed. A hard coat film can be manufactured.

The present invention (6) includes the method for producing a hard coat film according to (5), wherein in the step (2), the laminated base material is stretched three times or more.

According to this method for producing a hard coat film, in step (2), the laminated base material is stretched at a high ratio, so that high birefringence can be imparted to both the transparent base material and the intermediate layer.

The present invention (7) includes the method for producing a hard coat film according to (5) or (6), which satisfies both of the following conditions C and D in the step (2).

Condition C: The refractive index nmx in the slow axis direction of the intermediate layer after stretching is smaller than the refractive index nsx in the slow axis direction of the transparent substrate after stretching.

Condition D: The refractive index nmy in the fast axis direction of the intermediate layer after stretching is smaller than the refractive index nsy in the fast axis direction of the transparent substrate after stretching.

According to this method for producing a hard coat film, in the step (2), both the above conditions C and D are satisfied, so that it is possible to produce a hard coat film in which interference unevenness is sufficiently suppressed.

The present invention (8) includes the method for producing a hard coat film according to any one of (5) to (7), wherein the laminated base material is uniaxially stretched in the step (2).

According to this method for producing a hard coat film, the laminated base material is uniaxially stretched in the step (2), so that the step (2) can be easily carried out, but high birefringence is imparted to both the transparent base material and the intermediate layer. Can be granted.

The hard coat film of the present invention can sufficiently suppress uneven interference.

The transparent conductive film of the present invention can sufficiently suppress interference unevenness.

The method for producing a hard coat film of the present invention can produce a hard coat film in which interference unevenness is sufficiently suppressed.

FIG. 1 shows a cross-sectional view of one embodiment of the hard coat film of the present invention (a mode in which a primer layer and a hard coat layer are sequentially arranged on one side in the thickness direction of a transparent substrate). FIG. 2 is a manufacturing process diagram for manufacturing the hard coat film shown in FIG. 1, FIG. 2A is a step of preparing a transparent base material in the step (1), and FIG. 2B is a step of preparing the transparent base material in the step (1). 2C shows a step of disposing a primer layer to prepare a laminated base material, FIG. 2C shows a step (2) of stretching the laminated base material, and FIG. 2D shows a step of disposing a hard coat layer. FIG. 3 shows a transparent conductive film including the hard coat film shown in FIG. 1 (a mode in which a primer layer, a hard coat layer, an optical adjustment layer and a transparent conductive layer are sequentially arranged on one side in the thickness direction of a transparent substrate). A sectional view is shown. FIG. 4 shows a cross-sectional view of a modified example of the hard coat film shown in FIG. 1 (a mode in which a primer layer and a hard coat layer are sequentially arranged on both sides in the thickness direction of a transparent substrate). FIG. 5 is a cross section of a transparent conductive film including the hard coat film shown in FIG. 4 (a mode in which a primer layer, a hard coat layer, an optical adjustment layer and a transparent conductive layer are sequentially arranged on both sides in the thickness direction of a transparent substrate). The figure is shown. FIG. 6 is a process diagram of a modified example of the method for manufacturing the hard coat film shown in FIG. 2, FIG. 6A is a process of preparing an isotropic transparent substrate, and FIG. 6B is a process of stretching the transparent substrate. 6C shows the step of disposing the primer layer, and FIG. 6D shows the step of disposing the hard coat layer. FIG. 7 is a graph showing the refractive indexes of the transparent substrate, primer layer and hard coat layer of each example and each comparative example.

One embodiment of the method for producing the hard coat film, the transparent conductive film and the hard coat film of the present invention will be described with reference to FIGS. 1 to 3.

In FIG. 1, the vertical direction of the paper surface is the Z-axis direction (thickness direction, first direction). The upper side of the paper surface is one side in the Z-axis direction (one side in the thickness direction, one side in the first direction). The lower side of the paper is the other side in the Z-axis direction (the other side in the thickness direction, the other side in the first direction).

In FIG. 1, the left-right direction on the paper surface is the X-axis direction (the second direction orthogonal to the first direction).

In FIG. 1, the paper thickness direction is the Y-axis direction (the third direction orthogonal to the first direction and the second direction).

Specifically, it is based on the directional arrow in each figure.

1. Hard Coat Film As shown in FIG. 1, the hard coat film 1 has a film shape (including a sheet shape) having a predetermined thickness, extends in the X-axis direction and the Y-axis direction (plane direction), and has a flat thickness. It has one surface in the direction and the other surface (two main surfaces) in the flat thickness direction.

The hard coat film 1 is, for example, one component provided in a transparent conductive film 7 (see FIG. 3) described later, that is, not the transparent conductive film 7. That is, the hard coat film 1 is a component for producing the transparent conductive film 7, does not include a functional layer such as the optical adjustment layer 5 and the transparent conductive layer 6, is distributed as a component alone, and is industrially usable. Is a device.

Specifically, the hard coat film 1 sequentially includes a transparent substrate 2, a primer layer 3 as an example of an intermediate layer, and a hard coat layer 4. That is, the hard coat film 1 includes the transparent base material 2, the primer layer 3 arranged on one side in the thickness direction of the transparent base material 2, and the hard coat layer 4 arranged on one side in the thickness direction of the primer layer 3. Prepare Further, preferably, the hard coat film 1 is composed of only the transparent substrate 2, the primer layer 3, and the hard coat layer 4. Hereinafter, each layer will be described in detail.

2. Transparent Substrate The transparent substrate 2 is a layer on the other side in the thickness direction of the hard coat film 1 and is a support material that secures the mechanical strength of the hard coat film 1. In addition, the transparent substrate 2 is also a member for suppressing unevenness when the hard coat film 1 is provided in an image display device, for example. Nijimura is a phenomenon in which a plurality of different colors are observed in a place where the same color should be originally displayed in the image display device.

The transparent base material 2 has a film shape extending in the surface direction and has a flat thickness direction one surface and a flat thickness direction other surface (two main surfaces).

The transparent substrate 2 is made of a polymer having transparency. Examples of the polymer include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate (PEN), and (meth)acrylic resins (acrylic resin and/or methacrylic resin) such as polymethacrylate, for example, , Olefin resins such as polyethylene, polypropylene, cycloolefin polymers, for example, polycarbonate resins, for example, polyether sulfone resins, for example, polyarylate resins, for example, melamine resins, for example, polyamide resins, for example, polyimide resins, for example, cellulose resins Examples include polystyrene resins such as norbornene resins. These polymer films can be used alone or in combination of two or more kinds. From the viewpoint of birefringence and the like, preferably, a polyester resin is used, and more preferably, PEN is used.

The total light transmittance of the transparent substrate 2 is, for example, 90% or more, preferably 95% or more, more preferably 99% or more.

The transparent substrate 2 has birefringence.

Specifically, a value (nsx-nsy) (Δns) obtained by subtracting the refractive index nsy in the fast axis direction sy from the refractive index nsx in the slow axis direction sx (X axis direction in FIG. 1) of the transparent substrate 2 is It exceeds 0.05.

The slow axis direction sx is the direction with the largest refractive index in the surface direction of the transparent substrate 2, and the fast axis direction sy is the direction with the smallest refractive index. The definitions of the slow axis direction and the fast axis direction are the same for those in the primer layer 3 described later.

Δns is preferably 0.10 or more, more preferably 0.15 or more, and for example, less than 0.50. When Δns exceeds the above lower limit, the transparent base material 2 can have high birefringence, and therefore rainbow trout can be effectively suppressed.

Specifically, the refractive index nsx of the transparent substrate 2 in the slow axis direction sx is, for example, 1.70 or more, preferably 1.75 or more, more preferably 1.80 or more, and, for example, , 2.00 or less. When the refractive index nsx exceeds the above lower limit, the thickness of the transparent base material 2 can be reduced.

The refractive index nsy of the transparent substrate 2 in the fast axis direction is, for example, 1.55 or more, preferably 1.6 or more, and for example, 1.75 or less, preferably 1.70 or less. Is. If the refractive index nsy of the transparent substrate 2 in the fast axis direction is within the above range, the thickness of the transparent substrate 2 can be reduced.

In addition, even if Δns of the transparent substrate 2 is as small as 0.05 or less, if the thickness Ts of the transparent substrate 2 described below is sufficiently thick, the retardation described below satisfies the requirement of 8000 nm or more. .. However, in that case, the thickness of the transparent substrate 2 becomes excessively thick, and rainbow-like unevenness occurs.

The thickness Ts of the transparent substrate 2 is, for example, 2 μm or more, preferably 20 μm or more, and for example, 300 μm or less, preferably 200 μm or less. When the thickness Ts of the transparent base material 2 is at least the above lower limit, the strength of the hard coat film 1 can be sufficiently secured, and the transparent base material 2 can have a high retardation described below. Therefore, the rainbow trout can be effectively suppressed. On the other hand, if the thickness Ts of the transparent substrate 2 is equal to or less than the above upper limit, high transparency can be secured.

The transparent substrate 2 has a retardation of 8000 nm or more. The transparent substrate 2 preferably has a retardation of 10000 nm or more, preferably 12000 nm or less. If the retardation of the transparent substrate 2 exceeds the above lower limit, it is possible to sufficiently suppress rainbow trout.

The retardation is a value obtained by multiplying Δns by the thickness Ts. Further, the retardation is obtained by directly measuring the transparent base material 2.

On the other hand, if the retardation of the transparent base material 2 is less than 8000 nm, even if Δns of the transparent base material 2 exceeds 0.05, rainbow streaks cannot be sufficiently suppressed.

The glass transition temperature of the transparent substrate 2 is, for example, 100° C. or higher and 150° C. or lower.

3. Primer Layer The primer layer 3 is an intermediate layer in the hard coat film 1. The primer layer 3 is arranged between the transparent substrate 2 and the hard coat layer 4. Specifically, the primer layer 3 is arranged so as to come into contact with the entire one surface of the transparent substrate 2 in the thickness direction. The primer layer 3 has a film shape extending in the surface direction. The primer layer 3 is an easy-adhesion layer that improves the adhesion (adhesiveness) of the hard coat layer 4 to the transparent substrate 2. The primer layer 3 has a film shape extending in the surface direction and has a flat one surface in the thickness direction and another flat surface in the thickness direction (two main surfaces).

The primer layer 3 is made of a material having physical properties (specifically, mechanical strength, elasticity, etc.) similar to the polymer exemplified in the transparent substrate 2, and specifically, the polymer exemplified in the transparent substrate 2. And preferably PET from the viewpoint of polyester resin and birefringence.

The primer layer 3 has birefringence.

Specifically, the slow axis direction mx of the primer layer 3 and the slow axis direction sx of the transparent substrate 2 are the same direction, and both are X axis directions (left and right directions in FIG. 1 ). Further, the fast axis direction my of the primer layer 3 and the fast axis direction sy of the transparent substrate are the same direction, and both are the Y axis direction (paper thickness direction in FIG. 1). The X-axis direction and the Y-axis direction are orthogonal to each other on the same plane. The X-axis direction and the Y-axis direction are orthogonal to the Z-axis direction (thickness direction).

The refractive index nmx of the primer layer 3 in the slow axis direction mx is smaller than the refractive index nsx of the transparent substrate 2 in the slow axis direction sx. That is, the following expression [1] is satisfied.

nsx>nmx [1]
(In the formula, nsx represents the refractive index of the transparent substrate 2 in the slow axis direction sx, and nmx represents the refractive index of the primer layer 3 in the slow axis direction my.)
The ratio (nmx/nsx) of the refractive index nmx to the refractive index nsx is less than 1.00, and is, for example, 0.99 or less, preferably 0.97 or less, more preferably 0.95 or less, Further, for example, it is 0.70 or more. A value (nsx-nmx) obtained by subtracting the refractive index nmx of the transparent base material 2 in the slow axis direction sx from the refractive index nsx in the slow axis direction mx is, for example, 0.05 or more, preferably Is 0.10 or more, more preferably 0.15 or more, and, for example, 0.30 or less. If nmx/nsx is below the above-mentioned upper limit or if nsx-nmx is above the above-mentioned lower limit, it is possible to suppress interference unevenness when the hard coat layer 4 is laminated.

Further, the refractive index nmy of the primer layer 3 in the fast axis direction my is smaller than the refractive index nsy of the transparent substrate 2 in the fast axis direction sy. That is, the following expression [2-1] is satisfied.

nsy>nmy [2-1]
(In the formula, nsy represents the refractive index of the transparent substrate 2 in the fast axis direction sy, and nmy represents the refractive index of the primer layer 3 in the fast axis direction my.)
The ratio (nmy/nsy) of the refractive index nmy of the primer layer 3 in the slow axis direction my to the refractive index nsy of the transparent substrate 2 in the slow axis direction sy is less than 1.00, for example, 0.99. Hereafter, it is preferably 0.98 or less, and for example, 0.90 or more. Further, the value (nsy-nmy) obtained by subtracting the refractive index nmy of the primer layer 3 in the slow axis direction my from the refractive index nsy of the transparent substrate 2 in the slow axis direction sy is, for example, 0.01 or more, preferably Is 0.03 or more and is, for example, 0.25 or less. When nsy-nmy is less than the above upper limit, it is possible to suppress interference unevenness when the hard coat layer 4 is laminated.

Further, (nsx-nmx)/(nsy-nmy) is, for example, 0.1 or more, preferably 1 or more, more preferably more than 1, further preferably 1.5 or more, and particularly preferably 2 or more. And, for example, 10 or less, preferably 5 or less. When (nsx-nmx)/(nsy-nmy) exceeds the above lower limit, it is possible to suppress interference unevenness when the hard coat layer 4 is laminated.

The thickness Tm of the primer layer 3 is, for example, 10 nm or more, preferably 50 nm or more, more preferably 70 nm or more, and for example, 300 nm or less, preferably 200 nm or less.

When the thickness Tm of the primer layer 3 is at least the above lower limit, the adhesion of the hard coat layer 4 to the primer layer 3 can be secured. On the other hand, if the thickness Tm of the primer layer 3 is equal to or less than the above upper limit, it is possible to more sufficiently suppress the interference unevenness.

The interference unevenness is caused by reflected light at the interface between air and the hard coat layer 4, reflected light at the interface between the hard coat layer 4 and the primer layer 3, and further at the interface between the primer layer 3 and the transparent substrate 2. The reflected light interferes with the reflected light, and stripe unevenness is observed due to the interference.

The glass transition temperature of the primer layer 3 is, for example, 50° C. or higher and, for example, 200° C. or lower.

4. Hard coat layer The hard coat layer 4 is one layer in the thickness direction of the hard coat film 1. The hard coat layer 4 is arranged so as to come into contact with the entire one surface of the primer layer 3 in the thickness direction. The hard coat layer 4 is a scratch resistant layer that enhances the scratch resistance of the hard coat film 1. The hard coat layer 4 has a film shape extending in the surface direction, and has a flat thickness direction one surface and a flat thickness direction other surface (two main surfaces). The hard coat layer 4 has a film shape (including a sheet shape).

The hard coat layer 4 is made of, for example, a resin composition containing a resin. Further, the resin composition can also contain particles in an appropriate ratio.

Examples of the resin include active energy ray curable resins such as (meth)acrylic resins.

Examples of the particles include organic particles and inorganic particles. Examples of the organic particles include crosslinked acrylic resin particles. Examples of the inorganic particles include silicon oxide particles, zirconium oxide, titanium oxide, zinc oxide, tin oxide and the like. The particles can be used alone or in combination of two or more kinds.

The hard coat layer 4 preferably contains only a resin (no particles).

The hard coat layer 4 has, for example, birefringence or isotropic property. Preferably, the hard coat layer 4 is isotropic.

The refractive index nh of the hard coat layer 4 is smaller than the refractive index nmy of the primer layer 3 in the fast axis direction my. That is, the following expression [2-2] is satisfied.

nmy>nh [2-2]
(In the formula, nmy represents the refractive index of the primer layer 3 in the fast axis direction my. nh represents the refractive index of the hard coat layer 4.)
Then, in the hard coat film 1, the transparent base material 2, the primer layer 3, and the hard coat layer 4 satisfy the following formula [2] based on the above formula [2-1] and formula [2-2]. ..

nsy>nmy>nh [2]
(In the formula, nsy represents the refractive index of the transparent substrate 2 in the fast axis direction sy. nmy represents the refractive index of the primer layer 3 in the fast axis direction my. nh represents the refractive index of the hard coat layer 4 Indicates the rate.)
The ratio (nh/nmy) of the refractive index nh of the hard coat layer 4 to the refractive index nmy of the primer layer 3 in the fast axis direction my is less than 1, for example, 0.99 or less, preferably 0.98. Hereafter, it is more preferably 0.97 or less, and, for example, 0.70 or more. A value (nmy-nh) obtained by subtracting the refractive index nh of the hard coat layer 4 from the refractive index nmy of the primer layer 3 in the fast axis direction my is, for example, 0.03 or more, preferably 0.05 or more. Further, for example, it is 0.30 or less, preferably 0.20 or less.

nmy is the same or larger (nmy≧[(nsy+nh)/2]) with respect to [(nsy+nh)/2] (see the alternate long and short dash line in FIG. 7), and preferably larger (nmy>[(nsy+nh)/2). ]). nmy-[(nsy+nh)/2] is, for example, 0.00 or more, preferably more than 0.00, more preferably 0.01 or more, further preferably 0.02 or more, and, for example, It is 0.10 or less. Further, nmy/[(nsy+nh)/2] is, for example, 1.01 or more, preferably 1.02 or more, and 1.1 or less. If the above-mentioned nmy-[(nsy+nh)/2] and/or nmy/[(nsy+nh)/2] exceeds the above-mentioned lower limit, interference unevenness can be suppressed.

On the other hand, nmx is the same as or smaller than [(nsx+nh)/2] (nmx≦[(nsx+nh)/2]), and preferably small (nmx<[(nsx+nh)/2]). nmx−[(nsx+nh)/2] is, for example, 0.00 or less, preferably less than 0.00, more preferably −0.01 or less, and −0.10 or more. Further, nmx/[(nsx+nh)/2] is, for example, 1.00 or less, preferably less than 1.00, more preferably 0.995 or less, and 0.80 or more. When nmx-[(nsx+nh)/2] and/or nmx/[(nsx+nh)/2] is below the above-mentioned upper limit, interference unevenness can be suppressed.

Further, nmx, nsx, and nh satisfy, for example, the following formula [3-1], preferably the following formula [3-2], and more preferably the following formula [3-3].
[(Nsx+nh)/2]-0.05<nmx<[(nsx+nh)/2]+0.05
[3-1]
[(Nsx+nh)/2]-0.04<nmx<[(nsx+nh)/2]+0.04
[3-2]
[(Nsx+nh)/2]-0.03<nmx<[(ns+nh)/2]+0.03
[3-3]
If nmx, nsx, and nh satisfy the above formula, interference unevenness can be effectively suppressed.

Further, nmy, nsy, and nh satisfy, for example, the following formula [4-1], preferably the following formula [4-2], more preferably the following formula [4-2], and further preferably Satisfies the following formula [4-3].
[(Nsy+nh)/2]-0.05<nmy<[(nsy+nh)/2]+0.05
[4-1]
[(Ns+nh)/2]-0.04<nmy<[(nsy+nh)/2]+0.04
[4-2]
[(Nsy+nh)/2]-0.03<nmy<[(nsy+nh)/2]+0.03
[4-3]
[(Nsy+nh)/2]-0.02<nmy<[(nsy+nh)/2]+0.02
[4-3]
If nmy, nsy, and nh satisfy the above equation, interference unevenness can be effectively suppressed.

The hard coat layer 4 has a thickness of, for example, 0.1 μm or more, preferably 0.5 μm or more, and for example, 10 μm or less, preferably 5 μm or less.

5. Method for Manufacturing Hard Coat Film Next, a method for manufacturing the hard coat film 1 will be described.

The hard coat film 1 is manufactured by, for example, a roll-to-roll method.

In this method, a step of arranging an isotropic primer layer 3 on one surface in a thickness direction of an isotropic transparent substrate 2 to prepare a laminated substrate 8 including the transparent substrate 2 and the primer layer 3 (1 ), a step (2) of stretching the laminated base material 8, and a step (3) of arranging the hard coat layer 4 on one surface of the laminated base material 8 in the thickness direction of the primer layer 3. Hereinafter, each process will be sequentially described.

5-1. Process (1)
In the step (1), as shown in FIG. 2A, first, the isotropic transparent substrate 2 is prepared. Specifically, as the transparent substrate 2, an unstretched film made of the above polymer is prepared.

Then, as shown in FIG. 2B, the primer layer 3 is arranged on one surface in the thickness direction of the transparent substrate 2.

Specifically, first, a coating composition containing a polymer and a solvent (a coating composition for forming a primer layer) is prepared, and then the coating composition is applied to one surface in the thickness direction of the transparent substrate 2. The coating, and then the solvent in the coating is removed.

The polymer is selected, for example, from those having a refractive index between the refractive index of the isotropic transparent substrate 2 and the refractive index nh of the hard coat layer 4.

The solvent is a solvent capable of dissolving or dispersing the polymer, and examples thereof include a fluorine-based solvent such as pentafluoropropanol and hexafluoroisopropanol (HFIP). These can be used alone or in combination. As the solvent, preferably, a fluorine-based solvent is used.

The content ratio of the polymer in the coating composition (solid content) of the solvent is, for example, 1% by mass or more, preferably 3% by mass or more, and for example, 30% by mass or less, preferably 20% by mass. It is blended with a polymer so as to be as follows.

To prepare the coating composition, the polymer and the solvent are blended in the above blending ratio, and the polymer is dissolved or dispersed in the solvent.

To apply the coating composition to one surface of the transparent substrate 2 in the thickness direction, a coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater is used.

To remove the solvent, the coating is dried. The drying temperature is, for example, the glass transition temperature of the transparent substrate 2 or lower, specifically, for example, 50° C. or higher, preferably 70° C. or higher, and, for example, 150° C. or lower, preferably 120. It is below ℃. The drying time is, for example, 10 seconds or more, preferably 30 seconds or more, and for example, 10 minutes or less, preferably 3 minutes or less.

As a result, the isotropic primer layer 3 is arranged on one surface in the thickness direction of the transparent substrate 2. The thickness T0 of the isotropic primer layer 3 is, for example, 200 nm or more, preferably 300 nm or more, and for example, 600 nm or less, preferably 500 nm or less.

Thereby, the laminated base material 8 including the transparent base material 2 and the primer layer 3 in order is obtained.

5-2. Process (2)
In step (2), as shown in FIG. 2C, the laminated base material 8 is stretched so that the transparent base material 2 has the above-described birefringence. Preferably, the laminated base material 8 is uniaxially stretched. Specifically, the laminated base material 8 is stretched so as to satisfy the following condition A.

Condition A: The stretched transparent substrate 2 has a retardation of 8000 nm or more, and the refractive index nsy in the fast axis direction ny is subtracted from the refractive index nsx in the slow axis direction nx of the transparent substrate 2. The value (nsx-nsy) exceeds 0.05.

The conditions more preferable than the above-mentioned condition A regarding the birefringence include the conditions exemplified in the above "2. Transparent base material".

Specifically, the film is stretched while being heated. Specifically, first, the film is preheated, and subsequently, the film is stretched while being heated.

The heating temperature is, for example, the glass transition temperature of the polymer or higher.

The stretching ratio is, for example, 2.5 times or more, preferably 3.0 times or more, and for example, 6.0 or less, preferably 5.5 times or less.

When the magnification is at least the above lower limit, high birefringence can be imparted to both the transparent substrate 2 and the primer layer 3. When the magnification is not more than the above upper limit, the strength of the transparent substrate 2 can be secured.

Further, the laminated base material 8 is, for example, longitudinally stretched (stretched in the longitudinal direction, stretched in the direction along the transport direction of the laminated base material 8 in the roll-to-roll method), or horizontally stretched (stretched in the lateral direction). In the roll-to-roll method, the laminated base material 8 is stretched in the conveying direction and the thickness direction (width direction).

Specifically, the transparent base material 2 and the primer layer 3 are stretched in the same direction. By this stretching, the slow axis direction mx of the primer layer 3 and the slow axis direction sx of the transparent substrate 2 become the same direction. Further, the fast axis direction my of the primer layer 3 and the fast axis direction sy of the transparent substrate 2 are the same direction.

Furthermore, by stretching the laminated base material 8 described above, both the following conditions C and D are satisfied.

Condition C: The refractive index nmx of the stretched primer layer 3 in the slow axis direction mx is smaller than the refractive index nsx of the stretched transparent substrate 2 in the slow axis direction sx.

Condition D: The refractive index nmy of the primer layer 3 after stretching in the fast axis direction my is smaller than the refractive index nsy of the transparent substrate 2 after stretching in the fast axis direction sy.

The conditions more preferable than the above-mentioned conditions C and D regarding the birefringence include the conditions exemplified in the above "3. Primer layer".

By stretching the laminated base material 8 described above, the length of the transparent base material 2 in the slow axis direction sx and the length of the primer layer 3 in the slow axis direction mx are extended at the above-described magnification.

Thereby, the primer layer 3 has the thickness Tm described above. In the primer layer 3, the ratio (T0/Tm) of the thickness T0 before stretching to the thickness Tm after stretching is substantially the same as the above-mentioned stretching ratio, and specifically, for example, 2.5 times or more, It is preferably 3.0 times or more, and for example, 6.0 times or less, preferably 5.5 times or less.

5-3. Process (3)
In step (3), as shown in FIG. 2D, the hard coat layer 4 is arranged on one surface of the laminated base material 8 in the thickness direction of the primer layer 3. Specifically, the hard coat layer 4 is arranged so as to satisfy the following condition B.

Condition B: The refractive index nh of the hard coat layer 4 is smaller than the refractive index nmy of the primer layer 3 after stretching in the fast axis direction my.

The conditions more preferable than the above-mentioned condition B regarding the birefringence include the conditions exemplified in the above "4. Hard coat layer".

The hard coat layer 4 is applied to the entire surface of one side in the thickness direction of the primer layer 3 to form a coating film, and then the coating film is irradiated with an active energy ray, if necessary. As a result, the hard coat layer 4 is arranged on one surface of the primer layer 3 in the thickness direction.

As a result, the hard coat film 1 including the transparent substrate 2, the primer layer 3, and the hard coat layer 4 is obtained.

The hard coat film 1 is used for various industrial purposes, for example, an image display device such as a liquid crystal display, a plasma display, an electroluminescence display, a field emission display, a touch panel, and electronic paper. Preferably, it is provided in a transparent conductive film used for a touch panel.

6. Transparent Conductive Film As shown in FIG. 3, the transparent conductive film 7 has a film shape (including a sheet shape) having a predetermined thickness, extends in the plane direction, is flat in the thickness direction, and is flat. It has a flat other surface in the thickness direction (two main surfaces). The transparent conductive film 7 is, for example, one component such as a touch panel base material or a light control panel provided in an optical device (for example, an image display device or a light control device), that is, it is not an optical device. That is, the transparent conductive film 7 is a component for manufacturing an optical device and the like, does not include an image display element such as an LCD module or a light source such as an LED, and is a device that is distributed as a component and industrially usable. Is.

The transparent conductive film 7 includes the hard coat film 1, the optical adjustment layer 5, and the transparent conductive layer 6 in order. Specifically, the transparent conductive film 7 includes a transparent base material 2, a primer layer 3, a hard coat layer 4, an optical adjustment layer 5, and a transparent conductive layer 6 in order. Preferably, the transparent conductive film 7 is composed only of the transparent substrate 2, the primer layer 3, the hard coat layer 4, the optical adjustment layer 5, and the transparent conductive layer 6.

The optical adjustment layer 5 prevents the difference between the non-patterned portion and the patterned portion from being recognized after the transparent conductive layer 6 is formed in the wiring pattern in a later step (that is, to suppress the visual recognition of the wiring pattern). Is a layer for adjusting the optical physical properties of the transparent conductive film 7.

The optical adjustment layer 5 is arranged on the entire one surface of the hard coat layer 4 in the thickness direction. The optical adjustment layer 5 has a film shape extending in the surface direction, and has a flat thickness direction one surface and a flat thickness direction other surface (not shown) (two main surfaces).

The optical adjustment layer 5 is prepared from a resin composition. The resin composition contains, for example, a resin and particles. The resin composition preferably contains only the resin, and more preferably consists only of the resin.

The refractive index of the optical adjustment layer 5 is adjusted between the refractive index of the hard coat layer 4 and the refractive index of the transparent conductive layer 6.

The thickness of the optical adjustment layer 5 is, for example, 30 nm or more, preferably 50 nm or more, and for example, 150 nm or less, preferably 130 nm or less.

The transparent conductive layer 6 is a conductive layer for forming a pattern portion, which will be formed in a wiring pattern in a later step. The transparent conductive layer 6 is the most one side layer in the thickness direction of the transparent conductive film 7, has a film shape (including a sheet shape) extending in the plane direction, and has a flat one side in the thickness direction, and It has a flat thickness direction other surface.

Examples of the material forming the transparent conductive layer 6 include indium tin composite oxide (ITO) and antimony tin composite oxide (ATO).

The thickness of the transparent conductive layer 6 is, for example, 10 nm or more, preferably 20 nm or more, and for example, 35 nm or less, preferably 30 nm or less.

The transparent conductive film 7 is obtained by sequentially arranging the optical adjustment layer 5 and the transparent conductive layer 6 on one surface in the thickness direction of the hard coat layer 4 of the hard coat film 1.

7. Effect According to this hard coat film 1, the primer layer 3 has birefringence, and the slow axis direction mx of the primer layer 3 and the slow axis direction sx of the transparent substrate 2 are in the same direction. The fast axis direction sy of the transparent base material 2 and the fast axis direction my of the primer layer 3 are in the same direction, and satisfy the above-described formulas [1] and [2], so that the interference unevenness is sufficient. Can be suppressed.

Further, according to this hard coat film 1, since the primer layer 3 has the thickness Tm equal to or less than the above-mentioned upper limit, it is possible to more sufficiently suppress the interference unevenness.

According to this hard coat film 1, since the transparent substrate 2 has the refractive index nsx in the slow axis direction sx which is equal to or more than the above lower limit, it is possible to effectively suppress rainbow streaks.

According to this hard coat film 1, since the primer layer 3 has the thickness Tm equal to or more than the above lower limit, the adhesion of the hard coat layer 4 to the transparent substrate 2 can be secured.

Further, since the transparent conductive film 7 includes the hard coat film 1 described above, it is possible to sufficiently suppress the interference unevenness.

According to the method for producing the hard coat film 1, the simple step (2) of stretching the laminated base material 8 imparts birefringence to both the transparent base material 2 and the primer layer 3 to suppress uneven interference. The hard coat film 1 can be manufactured.

According to the method for producing the hard coat film 1, in the step (2), the optical adjustment layer 5 is stretched at a high magnification, so that high birefringence is imparted to both the transparent substrate 2 and the primer layer 3. You can

According to the method for manufacturing the hard coat film 1, in the step (2), both of the above conditions C and D are satisfied, so that it is possible to manufacture a hard coat film in which interference unevenness is sufficiently suppressed.

According to the method for producing the hard coat film 1, the laminated base material 8 is uniaxially stretched in the step (2), so that the step (2) can be performed easily, but both the transparent base material 2 and the primer layer 3 are expensive. Birefringence can be imparted.

8. Modified Example In the embodiment shown in FIG. 1, the hard coat film 1 includes a primer layer 3 and a hard coat layer 4 which are sequentially arranged only on one side in the thickness direction of the transparent substrate 2.

However, the arrangement of the primer layer 3 and the hard coat layer 4 is not limited to the above, and for example, as shown in FIG. 4, they are sequentially arranged on both sides (one side and the other side) in the thickness direction of the transparent substrate 2. The primer layer 3 and the hard coat layer 4 can also be provided.

The hard coat film 1 shown in FIG. 4 can also achieve the same effect as the hard coat film 1 of one embodiment.

In the embodiment shown in FIG. 3, the transparent conductive film 7 includes a primer layer 3, a hard coat layer 4, an optical adjustment layer 5 and a transparent conductive layer 6 which are sequentially arranged only on one side in the thickness direction of the transparent substrate 2. Prepare

However, the arrangement of the primer layer 3, the hard coat layer 4, the optical adjustment layer 5, and the transparent conductive layer 6 is not limited to the above. For example, as shown in FIG. 5, the primer layer 3, the hard coat layer 4, the optical adjustment layer 5, and the transparent layer which are sequentially arranged on both sides (one side and the other side) in the thickness direction of the transparent substrate 2. A conductive layer 6 can also be provided.

The transparent conductive film 7 of this modified example can also achieve the same effects as the transparent conductive film 7 of the embodiment.

Further, in one embodiment, the primer layer 3 is illustrated as the intermediate layer of the present invention, but the present invention is not limited to this. Examples of the intermediate layer of the present invention include an undercoat layer and an index matching layer.

In addition, in step (2) in one embodiment, uniaxial stretching is cited as a suitable example. However, the laminated base material 8 may be stretched so as to satisfy the above condition A, and for example, the laminated base material 8 can be biaxially stretched. In this case, the stretching ratio of the stretching ratio in the longitudinal direction to the stretching ratio in the lateral direction (stretching ratio in the longitudinal direction/stretching ratio to the stretching ratio in the lateral direction) or the stretching ratio in the lateral direction in the longitudinal direction. The stretch ratio (stretch ratio in the transverse direction/stretch ratio relative to the stretch ratio in the longitudinal direction) relative to the ratio is set to, for example, 2.5 times or more, preferably 3 times or more. This imparts birefringence to the transparent substrate 2 and the primer layer 3.

Further, in the method for manufacturing the hard coat film 1 in one embodiment, the step (2) of stretching the laminated base material 8 is performed. However, for example, the step (2) is not performed, and the birefringence is applied to the intermediate layer. It is also possible to impart sex.

For example, as shown in FIG. 6A, first, an isotropic transparent substrate 2 is prepared, then, as shown in FIG. 6B, the transparent substrate 2 is stretched, and then, although not shown, the transparent substrate 2 Of the alignment film is disposed on one surface in the thickness direction of the alignment film, and then one surface in the thickness direction of the alignment film is rubbed. To place. Then, the liquid crystal material is aligned along the rubbing direction of the alignment film (that is, the extending direction of the transparent substrate 2). As a result, the primer layer 3 made of a liquid crystal material has birefringence.

Alternatively, as shown in FIG. 6C, when the coating composition is applied to one surface in the thickness direction of the transparent substrate 2, the coating composition is applied by a coating machine such as a doctor blade capable of applying shearing force to the coating composition. It is also possible to orient the primer layer 3 by applying a shearing force to the transparent substrate 2 along the stretching direction.

Further, the slow axis direction mx of the primer layer 3 and the slow axis direction sx of the transparent substrate 2 are the same direction, but in the present invention, it is sufficient that they are substantially the same direction. In addition, it is allowed that they are deviated (crossed) to the extent that the effects of the present invention can be exhibited. For example, the slow axis direction mx of the primer layer 3 and the slow axis direction sx of the transparent substrate 2 intersect at 3 degrees or less, preferably 1 degree or less, more preferably 0.1 degrees or less. Is acceptable.

Further, the fast axis direction sy of the transparent base material 2 and the fast axis direction my of the primer layer 3 are the same direction, but in the present invention, it is sufficient that they are substantially the same direction. In addition, it is allowed that they are deviated (crossed) to the extent that the effects of the present invention can be exhibited. For example, the fast axis direction sy of the transparent substrate 2 and the fast axis direction my of the primer layer 3 intersect at 3 degrees or less, preferably 1 degree or less, and more preferably 0.1 degrees or less. Is acceptable.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the examples and comparative examples. In addition, specific numerical values such as a blending ratio (content ratio), physical property values, and parameters used in the following description are described in the above-mentioned "Description of Embodiments", and a corresponding blending ratio ( Content ratio), physical property value, parameter, etc. are replaced by the upper limit (numerical value defined as “below” or “less than”) or lower limit value (numerical value defined as “greater than or equal to” or “exceeded”) be able to.

(Preparation of coating composition for forming primer layer)
Preparation example 1
Polyethylene terephthalate (PET) (glass transition temperature: 80° C.) was dissolved in hexafluoroisopropanol (HFIP) so that the solid content was 5% by mass to prepare a primer layer-forming coating composition.

Preparation example 2
A coating composition for forming a primer layer was prepared using butyl acetate using an inorganic material-dispersed polyfunctional acrylate “Z7412” (manufactured by JSR Corporation) so that the solid content was 5% by mass.

(Preparation of coating composition for forming hard coat layer)
Preparation Example 3
A coating composition for forming a hard coat layer using ethyl acetate so that the solid content is 16% by mass, using 100 parts by mass of pentaerythritol triacrylate (PETA) and 0.1 parts by mass of the photopolymerization initiator Irgacure 184. Was prepared.

Example 1
1. Process (1)
First, as shown in FIG. 2A, as the isotropic transparent substrate 2, an unstretched polyethylene naphthalate film (PEN film) having a thickness of 200 μm (glass transition temperature 120° C.) was prepared.

Then, the primer layer-forming coating composition of Preparation Example 1 was applied to the entire surface of one side in the thickness direction of the transparent substrate 2 with a bar coater so that the thickness after drying was 360 nm, and then the coating film was dried in a drying oven. Was dried under an atmosphere of 120° C. for 1 minute to volatilize HFIP. Thereby, as shown in FIG. 2B, the isotropic primer layer 3 was arranged on one side of the isotropic transparent substrate 2 in the thickness direction. That is, the laminated base material 8 including the isotropic transparent base material 2 and the primer layer 3 was obtained.

2. Process (2)
As shown in FIG. 2C, the laminated base material 8 was uniaxially stretched 4 times using a batch type stretching machine (KARO IV: manufactured by BRUCKNER). The detailed conditions are as follows.
Preheating (pre-annealing) conditions: 120°C, 40 seconds Stretching temperature: 120°C
Stretching speed: 5%/sec

3. Process (3)
The coating composition for forming a hard coat layer of Preparation Example 3 was applied to the entire one surface in the thickness direction of the primer layer 3 in the stretched laminated base material 8 using a wire bar, and then in a drying oven in an atmosphere of 80°C. It was dried for 1 minute underneath and the solvent was volatilized to obtain a coating film. Thereafter, the coating film by using an oxygen concentration 2500ppm atmosphere at 160 W / cm ² of air-cooled mercury lamp (manufactured by Eye Graphics Co., Ltd.), illuminance 60 mW / cm ² and an irradiation dose of 280 mJ / cm ² Hard The coat layer 4 was formed.

As a result, a hard coat film 1 including the transparent substrate 2, the primer layer 3 and the hard coat layer 4 was obtained.

Example 2
As shown in Table 1, a hard coat film 1 was obtained by the same treatment as in Example 1 except that the thickness of the primer layer 3 after stretching was changed.

Comparative Example 1
1. Process (1)
As the isotropic transparent substrate 2, an unstretched polyethylene naphthalate film (PEN film) having a thickness of 200 μm (glass transition temperature 120° C.) was prepared.

Next, the isotropic transparent substrate 2 was uniaxially stretched 4 times using a batch type stretching machine (KARO IV: manufactured by BRUCKNER). The detailed conditions are as follows.
Preheating (pre-annealing) conditions: 120°C, 40 seconds Stretching temperature: 120°C
Stretching speed: 5%/sec. Thereafter, the coating composition for forming a primer layer of Preparation Example 2 was coated on a stretched transparent substrate 2 using a spin coater, and then dried in an oven at 60°C for 1 minute. after drying and evaporation of the solvent, using an oxygen concentration 2500ppm atmosphere at 160 W / cm ² of air-cooled mercury lamp (manufactured by eye graphics Co.), illuminance 60 mW / cm ^2, irradiation amount 280 mJ / cm ² Ultraviolet rays were irradiated to cure the coating film.

Thereby, the laminated base material 8 including the transparent base material 2 and the primer layer 3 was obtained.

2. Process (3)
The coating composition for forming a hard coat layer of Preparation Example 3 was applied to the entire surface of the laminated base material 8 on one side in the thickness direction of the primer layer 3 using a wire bar, and then in a drying oven under an atmosphere of 80°C. It was dried for 1 minute and the solvent was volatilized to obtain a coating film. Thereafter, the coating film by using an oxygen concentration 2500ppm atmosphere at 160 W / cm ² of air-cooled mercury lamp (manufactured by Eye Graphics Co., Ltd.), illuminance 60 mW / cm ² and an irradiation dose of 280 mJ / cm ² Hard The coat layer 4 was formed.

Thereby, as shown in FIG. 6D, a hard coat film 1 including a transparent substrate 2, a primer layer 3 and a hard coat layer 4 was obtained.

Comparative example 2
As shown in Table 1, a hard coat film 1 was obtained by the same treatment as in Comparative Example 1 except that the thickness of the primer layer 3 was changed.

(Evaluation)
The following items were evaluated. The results are shown in Table 1. Further, the respective refractive indexes of the transparent substrate, the primer layer and the hard coat layer are also shown in FIG.

1. Interference unevenness The interference unevenness of the hard coat film 1 of each Example and each Comparative Example was observed by observing the amplitude of the ripple (waveform) of the reflection spectrum obtained by U4100 (manufactured by Hitachi High-Technologies Corporation), and according to the following criteria. ,evaluated.
◯: The amplitude of ripple is extremely small (less than 2), which is a practical level.
Δ: Ripple amplitude is large (2 or more) and not at a practical level.

The formula for calculating the amplitude of the ripple is as follows.

Amplitude of ripple = | maximum value-reflected Y value |+| reflected Y value-minimum value |
Maximum value = maximum value of reflection spectrum (450 nm to 650 nm) Minimum value = minimum value of reflection spectrum (450 nm to 650 nm)

2. Thickness of transparent substrate, refractive index and retardation The thickness of the transparent substrate 2 was determined by measuring with a dial gauge.

The refractive index of the transparent base material 2 was determined from the reflection spectrum obtained by U4100 (manufactured by Hitachi High-Technologies Corporation).

Moreover, the retardation of the transparent substrate 2 (the transparent substrate 2 before the primer layer 3 was laminated) was determined using AXO SCAN (manufactured by AXOMETRIC).

In each measurement described above, only the transparent base material 2 on which the primer layer 3 is not laminated is uniaxially stretched under the condition of the step (2), and the transparent base material 2 having anisotropy (birefringence) is used. I was there.

3. Thickness and Refractive Index of Primer Layer The thickness and the refractive index of the primer layer 3 are the same as those of the primer layer 3 in the laminated base material 8 (the laminated base material 8 before the hard coat layer 4 is still arranged), U4100 (Hitachi High-Technologies Corporation). It was determined from the reflection spectrum obtained by

4. Evaluation of Thickness of Hard Coat Layer The thickness of the hard coat layer 4 was measured by MCPD2000 (manufactured by Otsuka Electronics Co., Ltd.).

DESCRIPTION OF SYMBOLS 1 hard coat film 2 transparent base material 3 primer layer 4 hard coat layer 5 optical adjustment layer 6 transparent conductive layer 7 transparent conductive film 8 laminated base material sx slow axis direction sy of transparent base material fast axis direction of transparent base material mx slow axis direction of primer layer my fast axis direction of primer layer nsx refractive index in slow axis direction of transparent substrate nsy refractive index in fast axis direction of transparent substrate nmx refraction in slow axis direction of intermediate layer Index nmy refractive index in the fast axis direction of the intermediate layer nh refractive index of the hard coat layer Tm thickness of the primer layer

Claims (8)

A transparent base material having birefringence, an intermediate layer having birefringence, and a hard coat layer are sequentially provided,
The transparent substrate has a retardation of 8000 nm or more,
A value (nsx-nsy) obtained by subtracting the refractive index nsy in the fast axis direction from the refractive index nsx in the slow axis direction of the transparent substrate is 0.24 or more and less than 0.50,
The slow axis direction of the intermediate layer and the slow axis direction of the transparent substrate are substantially the same direction,
The fast axis direction of the intermediate layer and the fast axis direction of the transparent substrate are substantially the same direction,
Furthermore, a hard coat film characterized by satisfying the following formulas [1] and [2].
nsx>nmx [1]
nsy>nmy>nh [2]
(In the formula, nsx represents the refractive index in the slow axis direction of the transparent substrate, nmx represents the refractive index in the slow axis direction of the intermediate layer, and nsy represents the fast axis of the transparent substrate. Direction, the refractive index in the fast axis direction of the intermediate layer is indicated by nmy, and the refractive index of the hard coat layer is indicated by nh.) The hard coat film according to claim 1, wherein the transparent substrate has a refractive index nsx in the slow axis direction of 1.80 or more. The intermediate layer is a primer layer,
The hard coat film according to claim 1, wherein the intermediate layer has a thickness of 10 nm or more. A transparent conductive film comprising the hard coat film according to claim 1, an optical adjustment layer, and a transparent conductive layer in order. A step (1) of disposing an isotropic intermediate layer on one side in the thickness direction of an isotropic transparent substrate to prepare a laminated substrate including the transparent substrate and the intermediate layer;
A step (2) of stretching the laminated base material so as to satisfy the following condition A, and
Step (3) of disposing a hard coat layer on one surface of the laminated base material in the thickness direction of the intermediate layer so as to satisfy the following condition B.
A method for producing a hard coat film, characterized by comprising:
Condition A: The transparent substrate after stretching has a retardation of 8000 nm or more, and a value obtained by subtracting the refractive index nsy in the fast axis direction from the refractive index nsx in the slow axis direction of the transparent substrate ( nsx-nsy) is 0.24 or more, Ru der less than 0.50.
Condition B: The refractive index nh of the hard coat layer is smaller than the refractive index nmy of the intermediate layer after stretching in the fast axis direction. The method for producing a hard coat film according to claim 5, wherein in the step (2), the laminated base material is stretched three times or more. The method for producing a hard coat film according to claim 5 or 6, wherein in the step (2), both of the following conditions C and D are satisfied.
Condition C: The refractive index nmx in the slow axis direction of the intermediate layer after stretching is smaller than the refractive index nsx in the slow axis direction of the transparent substrate after stretching.
Condition D: The refractive index nmy in the fast axis direction of the intermediate layer after stretching is smaller than the refractive index nsy in the fast axis direction of the transparent substrate after stretching. In the said process (2), the said laminated base material is uniaxially stretched, The hard coat film manufacturing method as described in any one of Claims 5-7 characterized by the above-mentioned.

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