TW201525532A - Antiglare film - Google Patents

Abstract

This invention provides an antiglare film which exhibits excellent antiglare film which exhibits excellent antiglare properties over a wide range of view angles even with a low haze. The antiglare film is capable of sufficiently suppressing the occurrence of the phenomena of whitening and glare The antiglare film contains a transparent supporting member and an antiglare layer formed on the transparent supporting member, the antiglare layer having an surface with fine undulations, a total haze of 0.1% or more to 3% or less, a surface haze of 0.1% or more to 2% or less. The abovesaid surface undulation has a roughness Kurtosis Rku of 4.9 or less and an intensity of the power spectrum of I(0.01), I(0.02) and I(0.1) or space frequency 0.01[mu]m<SP>-1</SP> at space frequency 0.01 [mu]m<SP>-1</SP> at a set elevation within the respective predetermined range.

Description

Anti-glare film

The present invention relates to an antiglare film which is excellent in anti-glare property (a case called an anti-glare film, and "anti-glare" and "anti-glare" are common).

Image display devices such as liquid crystal display and plasma display panel, Braun tube (CRT) display, organic electroluminescence (EL) display, etc., are designed to prevent external light from forming reflected glare on its display surface. The performance deteriorates, and an anti-glare film is disposed on the display surface.

As for the anti-glare film, a transparent film having a surface uneven shape is mainly reviewed. The anti-glare film reduces the reflected glare to exhibit anti-glare property by diffusing reflection of external light (external light scattering light) by the surface uneven shape. However, when the external light scatters light strongly, the display surface of the image display device may be whitish or the display may become turbid, that is, a so-called "whitening" occurs. Further, the pixels of the image display device interfere with the surface unevenness of the anti-glare film, and a luminance distribution is generated, which is difficult to see, that is, so-called "glare" occurs. From the above, it is expected that the anti-glare film ensures excellent anti-glare properties and sufficiently prevents the occurrence of "whitening" or "glare".

In the anti-glare film, for example, Patent Document 1 discloses an anti-glare film which is not disposed when placed on a high-definition image display device. An anti-glare film that is glare-proof and sufficiently prevents the occurrence of whitening has a fine surface uneven shape formed on a transparent substrate, and an average length PSm of an arbitrary profile curve of the surface uneven shape is 12 μm or less. The ratio Pa/PSm of the arithmetic mean height Pa to the average length PSm in the contour curve is 0.005 or more and 0.012 or less, and the surface uneven shape is a ratio of a surface having an inclination angle of 2 or less of 50% or less and the inclination angle is 6 or less. The ratio of the face is 90% or more.

The anti-glare film disclosed in Patent Document 1 can effectively suppress the glare by eliminating the surface unevenness having a period of about 50 μm which is likely to cause glare, by making the average length PSm in an arbitrary profile curve extremely small. However, if the anti-glare film disclosed in Patent Document 1 is intended to have a smaller haze (if it is desired to have a low haze), the anti-glare may be observed when the display surface of the image display device in which the anti-glare film is disposed is obliquely observed. Sex will decrease. Therefore, the anti-glare film disclosed in Patent Document 1 still needs to be improved in terms of the anti-glare property of the observation angle.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-187952

An object of the present invention is to provide an anti-glare film which has excellent anti-glare properties even at a wide viewing angle even when it has a low haze, and can sufficiently suppress the occurrence of whitening and glare when disposed in an image display device.

The present inventors conducted an in-depth review to solve the above problems, and as a result, completed the present invention. That is, the present invention is as follows: an anti-glare film comprising a transparent support and an anti-glare layer having a fine surface uneven shape formed thereon, wherein the full haze is 0.1% or more and 3% Hereinafter, the surface haze is 0.1% or more and 2% or less, and the ridge degree Rku of the roughness curve is 4.9 or less, and the power spectrum of the elevation satisfies the following conditions (1) to (3).

(1) The intensity I (0.01) in the spatial frequency of 0.01 μm ^-1 is 2 μm ⁴ or more and 10 μm ⁴ or less; (2) The intensity I (0.02) in the spatial frequency of 0.02 μm ^-1 is 0.1 μm ⁴ or more and 1.5 μm ⁴ or less; and (3) of 0.1μm ^-1 spatial frequency intensity I (0.1) is not more than 0.01μm ⁴ 0.0001μm ⁴ or less.

Further, in the anti-glare film of the present invention, it is preferable to use the penetration clarity measured by five types of optical combs having a dark portion and a bright portion having widths of 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively. And Tc is 375% or more, and the sum of the reflection sharpness measured by the light incident angle of 45° is used for the four optical combs of the dark portion and the bright portion of the widths of 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively. ) is 180% or less, and the widths of the dark portion and the bright portion are 0.25 mm, 0.5 mm, and 1.0 mm, respectively. And the sum of the reflection sharpness Rc (60) measured by the four optical combs of 2.0 mm and measured at a light incident angle of 60° is 240% or less.

According to the present invention, it is possible to provide an anti-glare film which has sufficient anti-glare property even at a wide viewing angle even when it has a low haze, and can sufficiently suppress the occurrence of whitening and glare when disposed in an image display device.

1‧‧‧Anti-glare film

2‧‧‧Small bumps

3‧‧‧film projection surface

5‧‧‧Main normal direction

40‧‧‧Mold base for mold

41‧‧‧The surface of the substrate for the mold after the first plating step and the grinding step (plating layer)

46‧‧‧First surface relief shape formed by etching treatment

50‧‧‧Photosensitive resin film

51‧‧‧Exposure area

52‧‧‧Unexposed areas

60‧‧‧ mask

70‧‧‧ Surface embossed surface after chrome plating

71‧‧‧chrome plating

80‧‧‧Send rolls

81‧‧‧ Transparent support

82‧‧‧ Coating layer

82b‧‧‧End area

83‧‧‧ Coating area

84‧‧‧Drying area

85, 86‧‧‧Active energy line irradiation device

87‧‧‧Roll mold

88, 89‧‧‧ pinch roller

90‧‧‧film rewinding device

100‧‧ ‧ unit cell

101‧‧‧Chromium shade pattern

101‧‧‧ Transparent support

102‧‧‧Anti-glare layer

102‧‧‧ openings

103‧‧‧Virtual plane

110‧‧‧Anti-glare film

111‧‧‧Chromium shade pattern

113‧‧‧Photomask

115‧‧‧Lightbox

116‧‧‧Light source

117‧‧‧ glass plate

119‧‧‧ position

Fig. 1 is a view for simply explaining the elevation of the surface uneven shape of the anti-glare film.

Fig. 2 is a view for simply explaining the relationship between the elevation of the surface uneven shape of the anti-glare film and the coordinates (x, y).

Fig. 3 is a view showing a state in which the elevation of the surface uneven shape of the anti-glare film can be obtained discretely.

Fig. 4 is a view showing a state in which a one-dimensional power spectrum is calculated from a two-dimensional power spectrum of the elevation of the surface concavo-convex shape obtained as a discrete function.

Fig. 5 is a graph showing the dimension of the one-dimensional power spectrum I(f) with respect to the spatial frequency f of the surface uneven shape of the anti-glare film.

Fig. 6 (a) to (e) are schematic views showing a preferred example of a method of manufacturing a mold (first half).

Fig. 7 (a) to (c) are schematic views showing a preferred example of the method of manufacturing the mold (the latter half).

Fig. 8 is a view showing a preferred example of a manufacturing apparatus which can be used in the method for producing an anti-glare film of the present invention.

Fig. 9 is a schematic view showing a suitable preliminary hardening step in the method for producing an antiglare film of the present invention.

Figure 10 is a schematic diagram of a unit cell for glare evaluation.

Figure 11 is a schematic diagram of a glare evaluation device.

Fig. 12 is a view showing a part of the pattern A used in the first embodiment.

Fig. 13 is a view showing a part of the pattern B used in the second embodiment.

Fig. 14 is a view showing a part of the pattern C used in the third embodiment.

Fig. 15 is a view showing a part of the pattern D used in Comparative Example 1.

Fig. 16 is a view showing a part of the pattern E used in Comparative Example 2.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, and the dimensions and the like shown in the drawings are arbitrarily set for convenience of viewing.

The anti-glare film of the present invention is characterized in that the kurtosis Rku of the surface roughness curve is 4.9 or less, and the spatial frequency of the power spectrum of the surface of the fine uneven surface is 0.01 μm ^-1 , 0.02 μm ^-1 , and 0.1 μm ^{-1 .} The strengths in the above are in the foregoing ranges.

First, regarding the anti-glare film of the present invention, the method of determining the power spectrum of the kurtosis Rku of the roughness curve and the elevation of the fine uneven surface will be described.

[The kurtosis of the roughness curve Rku]

In the antiglare film of the present invention, the surface roughness of the antiglare layer is 4.9 or less by the kurtosis Rku of the thickness curve obtained by the method specified in JIS B 0601. The large kurtosis Rku means that the uneven portion of the surface uneven shape is sharp, that is, the surface uneven shape has a large number of steep inclination angles. The area. When an image display device is produced using the kurtosis-resistant Rku anti-glare film, the image display device becomes whitened. The present inventors have found that it is effective to suppress the whitening when the anti-glare film is disposed in the image display device, and to prevent the glare of the roughness curve Rku from being 4.9 or less. In order to obtain an image display device in which whitening is further suppressed, the kurtosis Rku of the thickness curve of the anti-glare film is preferably 4.5 or less, more preferably 4 or less.

The measurement conditions (cut length and evaluation length) when the kurtosis Rku of the thickness curve is measured can be appropriately set by the surface roughness Ra obtained in accordance with JIS B0633. That is, when the surface roughness Ra exceeds 0.006 μm and 0.02 μm or less, the cut length is 0.08 mm, the evaluation length is 0.4 mm, and when the surface roughness Ra exceeds 0.02 μm and 0.1 μm or less, the cut length is 0.25 mm, and the evaluation length is 1.25 mm. When the surface roughness Ra exceeds 0.1 μm and is 2 μm or less, the cut length is 0.8 mm, the evaluation length is 4 mm, and when the surface roughness Ra exceeds 2 μm and 10 μm or less, the cut length is 2.5 mm and the evaluation length is 12.5 mm.

The surface roughness Ra can be determined by measuring according to the method of JIS B0601.

[Power spectrum of the elevation of the surface irregular shape]

Hereinafter, the power spectrum of the elevation of the surface uneven shape of the anti-glare film will be described. Fig. 1 is a schematic cross-sectional view showing the surface of an anti-glare film of the present invention. As shown in Fig. 1, the anti-glare film 1 of the present invention has a transparent support 101 and an anti-glare layer 102 formed thereon, and the anti-glare layer 102 is provided with fine unevenness on the side opposite to the transparent support 101. The surface has a concave and convex shape.

Here, the term "elevation of the surface unevenness shape" as used in the present invention means an arbitrary point P on the surface of the film 1, and an average of the surface unevenness shapes. The linear distance in the main normal direction 5 (the normal direction of the imaginary plane 103) of the film having the virtual plane 103 (the elevation reference is 0 μm) of the height.

Actually, the anti-glare film is schematically shown in Fig. 2, and has an anti-glare layer on which a fine unevenness is formed on a two-dimensional plane. The elevation of the surface concavo-convex shape is shown in Fig. 2. When the orthogonal coordinates in the plane of the film are represented by (x, y), they can be expressed as a two-dimensional function h(x, y) of the coordinates (x, y).

The elevation of the surface concavo-convex shape can be obtained by three-dimensional information on the surface shape measured by a device such as a conjugate focal microscope, an interference microscope, or an atomic force microscope (AFM). The horizontal resolution required for the measuring machine is at least 5 μm or less, preferably 2 μm or less, and the vertical resolution is at least 0.1 μm or less, preferably 0.01 μm or less. The non-contact three-dimensional surface shape/coarseness measuring machine suitable for the measurement includes a New View 5000 series (manufactured by Zygo Corporation), a three-dimensional microscope PL μ 2300 (manufactured by Sensofar Co., Ltd.), and the like. Since the resolution of the power spectrum of the elevation must be 0.005 μm ^-1 or less, the measurement area is preferably at least 200 μm × 200 μm, more preferably 500 μm × 500 μm or more.

Next, a method of obtaining the power spectrum of the elevation by the two-dimensional function h(x, y) will be described. First, the two-dimensional function H(f _x , f _y ) is obtained from the two-dimensional function h(x, y) by a two-dimensional Fourier transform defined by the equation (1).

Here, f _x and f _y are frequencies in the x direction and the y direction, respectively, and have a reciprocal dimension of length. Further, in the formula (1), the π is a pi, and i is an imaginary unit. It can be obtained by the two-dimensional function H (f _x, f _y) of the absolute value squared, and by the formula (2) is obtained by a two-dimensional power spectrum _{I (f x, f y)} .

I ( f _x , f _y )=| H ( f _x , f _y )| ² (2)

The two-dimensional power spectrum I(f _x , f _y ) represents a spatial frequency distribution of the surface uneven shape of the anti-glare film. Since the anti-glare film is isotropic, the two-dimensional function I(f _x , f _y ) representing the two-dimensional power spectrum of the surface concave-convex shape can be obtained by relying only on the distance f from the origin (0, 0). (f) to indicate. Next, a method of obtaining a one-dimensional function I(f) from the two-dimensional function I(f _x , f _y ) is disclosed. First, the two-dimensional function I(f _x , f _y ) of the two-dimensional power spectrum of the elevation is represented by a polar coordinate according to the equation (3).

I ( f _x , f _y )= I ( f cos θ, f sin θ)...(3)

Here, the angle in the θ-system Fourier space. The one-dimensional function I(f) can be obtained by calculating the rotation average of the two-dimensional function I (fcos θ, fsin θ) expressed by the polar coordinates according to the equation (4). The one-dimensional function I(f) is obtained from the rotational average of the two-dimensional function I(f _x , f _y ) of the two-dimensional power spectrum of the elevation, hereinafter also referred to as the one-dimensional power spectrum I(f).

The anti-glare film of the present invention is characterized by the intensity of one-dimensional power spectrum I(f) at a spatial frequency of 0.01 μm ^-1 (0.01) and the intensity at a spatial frequency of 0.02 μm ^-1 from the elevation of the surface relief shape. I (0.02) and the intensity I (0.1) in the spatial frequency of 0.1 μm ^-1 are within a specific range.

Hereinafter, a method of obtaining a two-dimensional power spectrum of the elevation of the surface uneven shape of the anti-glare film will be further specifically described. The three-dimensional information of the surface shape actually measured by the conjugate focal length microscope, the interference microscope, the atomic force microscope, or the like is a value of general dispersion, that is, an elevation corresponding to a plurality of measurement points. Fig. 3 is a view showing a state in which the discreteness is obtained as a function of the function h(x, y) indicating the elevation. As shown in Fig. 3, the orthogonal coordinates in the plane of the film are indicated by (x, y), and on the film projection surface 3, the line divided by Δx in the x-axis direction and the y-axis are indicated by broken lines. In the actual measurement, the elevation of the surface unevenness is obtained as the discrete elevation value of each area Δx × Δy divided by the broken lines on the film projection surface 3 in the actual measurement.

The number of the obtained elevation values is determined by the measurement range and Δx and Δy. As shown in Fig. 3, the measurement range in the x-axis direction is X=MΔx, and the measurement range in the y-axis direction is taken as Y. When =NΔy, the number of the obtained elevation values is M×N.

As shown in Fig. 3, the coordinates of the eye point A on the film projection surface 3 are (m Δx, n Δy) [here, m is 0 or more and M-1 or less, n is 0 or more and N- When 1 or less, the elevation of the point P corresponding to the film surface of the eye point A can be expressed as h (m Δx, n Δy).

Here, the measurement intervals Δx and Δy depend on the horizontal resolution of the measuring device, and in order to evaluate the surface unevenness with good precision, it is preferable that both Δx and Δy are 5 μm or less, and more preferably 2 μm or less. Further, the measurement ranges X and Y are preferably 200 μm or more, and more preferably 500 μm or more, as described above.

In such an actual measurement, the function indicating the elevation of the surface concavo-convex shape is obtained as a discrete function h(x, y) having M × N values. Here, the two-dimensional function h(x, y) of the elevation of the surface concavo-convex shape is obtained by the two-dimensional function H(f _x , f _y ) obtained by the two-dimensional Fourier transform, by calculating the discreteness of the equation (1) The discrete Fourier transform is obtained as a discrete function in the manner of equation (5).

Here, j in the formula (5) is an integer of -M/2 or more and M/2 or less, and k is an integer of -N/2 or more and N/2 or less. Further, Δf _x and Δf _y are frequency intervals in the x direction and the y direction, respectively, and are defined by the equations (6) and (7).

The two-dimensional power spectrum I(f _x , f _y ) is obtained by the square of the absolute value of the discrete function H(f _x , f _y ) obtained by the equation (5), as shown in the equation (8). .

In the equation (8), when | H(j Δf _x , k Δf _y ) | ^{2 is} divided by MN Δx Δy for actual measurement, the integration range is normalized in accordance with the measurement area.

The two-dimensional power spectrum I(f _x , f _y ) obtained as a discrete function also indicates the spatial frequency distribution of the surface uneven shape of the anti-glare film. Further, since the anti-glare film is isotropic, the two-dimensional discrete function I(f _x , f _y ) indicating the two-dimensional power spectrum of the surface uneven shape elevation may depend only on the distance f from the origin (0, 0). One dimensional discrete function I(f) is used to represent. When the one-dimensional discrete function I(f) is obtained from the two-dimensional discrete function I(f _x , f _y ), the rotation average may be calculated in the same manner as in the equation (4). The discrete rotation average of the two-dimensional discrete function I(f _x , f _y ) can be calculated by equation (9).

Here, when M≧N, l is an integer of 0 or more and N/2 or less, and when M<N, l is an integer of 0 or more and M/2 or less. Further, Δf is the interval between the distances from the origin, and Δf = (Δf _x + Δf _y )/2. Further, Θ(x) is a Heaviside function defined by the formula (10), and the distance from the origin in the f _jk system (j, k) is calculated by the formula (11).

The calculation shown in the equation (9) will be described in the fourth diagram. The function Θ(f _jk -(l-1/2)Δf) is 0 when f _{jk is} less than (l-1/2) Δf, and is 1 when (l-1/2) Δf or more. Θ(f _jk -(l+1/2) Δf) is 0 when f _{jk does} not reach (l+1/2) Δf, and is 1 when (l+1/2) Δf or more, therefore, Θ(f _jk -(l-1/2)Δf)-Θ(f _jk -(l +1/2)Δf) of equation (9) is (l-1/2)Δf only at f _jk When it is less than (l-1/2) Δf, it becomes 1 and it becomes 0 in other cases. Here, in the frequency space, f _jk is the distance from the origin O (f _x =0, f _y =0), and therefore, the denominator of the equation (9) calculates the distance f _jk from the origin O as ( L-1/2) The number of points (the black dots in Fig. 5) of Δf or more and less than (l+1/2) Δf. Further, the molecular formula of the formula (9) calculates I (f) at a point where the distance f _jk from the origin O is (l-1/2) Δf or more and does not reach (l + 1/2) Δf. The total value of _x , f _y ) (the total value of I(f _x , f _y ) in the black dot in Fig. 4).

In general, the one-dimensional power spectrum obtained by the aforementioned method contains the noise in the measurement. Here, in order to obtain the one-dimensional power spectrum, in order to remove the influence of the noise, it is preferable to measure the elevation of the surface unevenness shape at a plurality of points on the anti-glare film, and to use the elevation of the surface irregularities of the respective surfaces. The average of the one-dimensional power spectrum is taken as the one-dimensional power spectrum I(f). The number of the measurement points of the surface unevenness on the anti-glare film is preferably 3 or more, more preferably 5 or more.

Fig. 5 shows I(f) of the one-dimensional power spectrum of the elevation of the surface unevenness shape thus obtained. The one-dimensional power spectrum I(f) of Fig. 5 is obtained by averaging one-dimensional power spectra obtained from the elevations of the surface unevenness shapes at five different places on the anti-glare film.

The anti-glare film of the present invention is characterized in that the spatial frequency of one-dimensional power spectrum I(f) calculated from the elevation of the surface concavo-convex shape is 0.01 μm ^-1 and the intensity I (0.01) is 2 μm ⁴ or more and 10 μm ⁴ or less. the frequency of 0.02μm ^-1 intensity I (0.02) of 0.1μm ⁴ or more and 1.5μm ⁴ below 0.1μm ^-1 spatial frequency of the intensity I (0.1) of 0.0001μm ⁴ or more and 0.01 μm ⁴ or less. Here, since the one-dimensional power spectrum I(f) is obtained as a discrete function, in order to obtain the intensity I(f ₁ ) in the specific spatial frequency f ₁ , interpolation is performed in the manner shown in the equation (12). And the calculation can be.

In the anti-glare film of the present invention, the intensity of each of the specific spatial frequencies is set to a predetermined range, and the whitening effect is favorably prevented by the synergistic effect of the average value of the haze and the inclination angle of the surface unevenness described later. And the occurrence of glare, and at the same time, it shows excellent anti-glare. In order to further exhibit this effect, the strength I (0.01) is preferably 2.5 μm ⁴ or more and 9 μm ⁴ or less, and more preferably 3 μm ⁴ or more and 8 μm ⁴ or less. Similarly, the intensity I (0.02) is preferably 0.2 μm ⁴ or more and 1.2 μm ⁴ or less, more preferably 0.25 μm ⁴ or more and 1 μm ⁴ or less, and the strength I (0.1) is preferably 0.0003 μm ⁴ or more and 0.0075 μm ⁴ or less, more preferably based 0.0005μm ⁴ less than 0.005μm ^4.

When I (0.01) is less than the above range, the cycle fluctuation of about 100 μm (corresponding to a spatial frequency of 0.01 μm ^-1 ) which contributes to the antiglare effect when the antiglare film is observed obliquely is small, and the antiglare property is insufficient. When I (0.01) is higher than the above range, the periodic fluctuation of about 100 μm becomes excessively large, the fine unevenness of the anti-glare film becomes rough, and the haze tends to increase, which is not preferable.

When I (0.02) is less than the above range, the cycle fluctuation of about 50 μm (corresponding to a spatial frequency of 0.02 μm ^-1 ) which is excellent in the antiglare effect when the antiglare film is observed from the front is small, and the antiglare property is insufficient. . When I (0.02) is higher than the above range, the periodic fluctuation of about 50 μm becomes excessively large, and glare is generated.

When I (0.1) is less than the above range, the short-period shape of a short period of about 10 μm (corresponding to a spatial frequency of 0.1 μm ^-1 ) is extremely small, and the surface uneven shape of the anti-glare film is formed only by the long-period uneven shape, and the anti-glare is formed. The surface texture of the film becomes rough, so it is not good. When I (0.1) is higher than the above range, the dispersion due to the surface unevenness shape of a short period of about 10 μm becomes strong, and whitening is likely to occur.

[Full haze, surface haze]

The anti-glare film of the present invention exhibits anti-glare properties, and in order to prevent whitening, the total haze of normal incident light is in a range of 0.1% or more and 3% or less, and the surface haze is in a range of 0.1% or more and 2% or less. The full haze of the anti-glare film can be measured by the method shown in JIS K7136. An image display device equipped with an anti-glare film having a full haze or a surface haze of less than 0.1% does not exhibit sufficient anti-glare property, which is not preferable. Further, when the total haze is higher than 3% or the surface haze is higher than 2%, the anti-glare film is not preferable because the image display device in which the anti-glare film is disposed is whitened. Further, the image display device also has a problem that the contrast is insufficient.

The internal haze obtained by subtracting the surface haze from the full haze is preferably as low as possible, and specifically, it is preferably 2.5% or less. An image display device equipped with an anti-glare film having an internal haze of more than 2.5% has a tendency to be lowered in contrast.

[Transmission resolution Tc, reflection resolution Rc (45), and reflection resolution Rc (60)]

The antiglare film of the present invention preferably has a Tc of 375% or more as determined by the following measurement conditions. The sum of penetration clarity and Tc The image sharpness was measured by an optical comb of a predetermined width in accordance with the method of JIS K 7105, and the total was calculated. Specifically, five types of optical combs having a width ratio of a dark portion to a bright portion of 1:1 and widths of 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm are used to measure image sharpness, and the total is obtained as Tc. . When the anti-glare film having a Tc of less than 375% is disposed in a higher-definition image display device, glare sometimes becomes apt to occur. The upper limit of Tc is selected from the range of 500% or less of the maximum value. However, if the Tc is too high, an image display device which is easily degraded from the front side is obtained, and is preferably, for example, 450% or less.

The anti-glare film of the present invention preferably has a reflection definition Rc (45) measured by incident light having an incident angle of 45° of 180% or less. The reflection sharpness Rc (45) is the same as the above Tc, and is measured by the method according to JIS K 7105. Four types of the optical combs are 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm. The optical comb measures the image sharpness separately, and finds the total as Rc (45). When the Rc (45) is 180% or less, the image display device in which the anti-glare film is disposed is more excellent in anti-glare property when viewed from the front and the oblique direction. The lower limit of Rc (45) is not particularly limited, but is preferably 80% or more in order to satisfactorily suppress the occurrence of whitening and glare.

The anti-glare film of the present invention preferably has a reflection definition Rc (60) of 240% or less as measured by incident light having an incident angle of 60°. The reflection sharpness Rc (60) is measured by a method according to JIS K 7105 in the same manner as the reflection sharpness Rc (45) except that the incident angle is changed. When Rc (60) is 240% or less, the image display device in which the anti-glare film is disposed is preferable because the anti-glare property at the time of oblique observation is further improved. The lower limit of Rc(60) is not particularly limited, but In order to suppress whitening and glare more satisfactorily, it is preferably, for example, 150% or more.

[Method for Producing Antiglare Film of the Present Invention]

The antiglare film of the present invention is produced, for example, in the following manner. In the first method, a mold for forming a fine unevenness having a surface unevenness shape according to a predetermined pattern is formed, and the shape of the uneven surface of the mold is transferred to the transparent support, and the transparent support having the shape of the uneven surface is transferred. The method of peeling the body from the mold. In the second method, a composition containing fine particles, a resin (binder) and a solvent, and the fine particles are dispersed in a resin solution, and the composition is applied onto a transparent support, and dried as needed to make A method of hardening a formed coating film (a coating film containing fine particles). In the second method, the coating film thickness and the fine particle aggregation state are adjusted by the composition of the composition and the drying conditions of the coating film, etc., so that the fine particles are exposed on the surface of the coating film, and the transparent support is formed on the transparent support. Bump. From the viewpoint of production stability and production reproducibility of the antiglare film, it is preferred to produce the antiglare film of the present invention by the first method.

Here, a preferred first method as a method for producing an anti-glare film of the present invention will be described in detail.

In order to form the antiglare layer having the surface unevenness shape as described above with good precision, it is important to prepare a fine unevenness forming mold (hereinafter sometimes simply referred to as "mold"). More specifically, the surface uneven shape of the mold (hereinafter sometimes referred to as "mold uneven surface") is formed according to a predetermined pattern, which is preferably a spatial frequency of the one-dimensional power spectrum of 0.01 μm ^-1 The ratio Γ(0.02)/Γ(0.01) of the strength Γ(0.01) to the intensity Γ(0.02) in the spatial frequency 0.02 μm ^-1 is 0.05 or more and 1.2 or less, and the intensity in the spatial frequency of 0.01 μm ^-1 ( 0.01) The ratio Γ(0.1)/Γ(0.01) to the intensity Γ(0.1) in the spatial frequency of 0.1 μm ^-1 is 4 or more and 25 or less. Here, the "pattern" means image data for forming a surface uneven shape of the antiglare layer of the antiglare film, a mask having a light transmitting portion and a light shielding portion, and the like, and may be simply referred to as a "pattern" hereinafter.

First, a method of determining a pattern for forming the uneven shape of the surface of the antiglare layer of the antiglare film of the present invention will be described.

A method of obtaining a two-dimensional power spectrum of a pattern is disclosed, for example, when the pattern is image data. First, after converting the image data into two levels of binarized image data, the hierarchy is represented by a two-dimensional function g(x, y). The obtained two-dimensional function g(x, y) is subjected to Fourier transform in the following formula (13) to calculate a two-dimensional function G(f _x , f _y ), as shown in the following formula (14), The square of the absolute value of the two-dimensional function G(f _x , f _y ) is obtained, and the two-dimensional power spectrum Γ(f _x , f _y ) is obtained. Here, x and y represent orthogonal coordinates within the plane of the image data. Further, f _x and f _y represent frequencies in the x direction and the y direction, respectively, and have a reciprocal dimension of length.

In the formula (13), the π is a pi, and i is an imaginary unit.

Γ( f _x , f _y )=| G ( f _x , f _y )| ² (14)

The two-dimensional power spectrum f(f _x , f _y ) represents the spatial frequency distribution of the pattern. In general, since the antiglare film is required to be isotropic, the pattern for producing an antiglare film of the present invention is also isotropic. Therefore, the two-dimensional function Γ(f _x , f _y ) representing the two-dimensional power spectrum of the pattern can be expressed only by one dimensional function Γ(f) from the distance f of the origin (0, 0). Next, a method of obtaining a one-dimensional function Γ(f) from the two-dimensional function Γ(f _x , f _y ) will be described. First, the two-dimensional function Γ(f _x , f _y ) of the two-dimensional power spectrum of the layer of the pattern is expressed as a polar coordinate as in the equation (15).

Γ( f _x , f _y )=Γ( f cos θ, f sin θ)...(15)

Here, the angle in the θ-system Fourier space. The one-dimensional function Γ(f) can be obtained by calculating the rotation average of the two-dimensional function Γ (fcos θ, fsin θ) represented by the polar coordinates in the manner of the equation (16). The one-dimensional function Γ(f) is obtained from the rotational average of the two-dimensional function Γ(f _x , f _y ) of the two-dimensional power spectrum of the level of the pattern, hereinafter also referred to as the one-dimensional power spectrum Γ(f).

In order to obtain a good precision the antiglare film of the present invention, the spatial dimension of one preferred power spectral line frequency 0.01μm intensity pattern Γ (0.01) ^-1 0.02μm in the spatial frequency intensity Γ (0.02) ^-1 of the in ratio Γ (0.02) / Γ (0.01 ) is 0.05 or more and 1.2 or less, in the spatial frequency intensity Gamma] 0.01μm ^-1 (0.01) and the spatial frequency intensity Γ (0.1) of the ratio of the 0.1μm ^-1 Γ (0.1) /Γ(0.01) is 4 or more and 25 or less.

When the two-dimensional power spectrum of the pattern is obtained, the two-dimensional function g(x, y) of the hierarchy is usually obtained as a discrete function. At this time, the two-dimensional power spectrum can be calculated by the discrete Fourier transform. One dimensional power spectrum of the pattern is obtained in the same way from the two-dimensional power spectrum of the pattern.

The peak of the roughness curve of the surface of the anti-glare film The degree Rku is 4.9 or less. In order to manufacture the anti-glare film of the present invention, the average value of the two-dimensional function g(x, y) is preferably set to the maximum value of the two-dimensional function g(x, y) and the two-dimensional function g 35 to 65% of the difference between the minimum values of (x, y). When the concave-convex surface of the mold is produced by a lithography method, the two-dimensional function g(x, y) is the aperture ratio of the pattern. When the mold uneven surface is produced by the lithography method, the aperture ratio of the pattern described herein is defined. The aperture ratio of the photoresist used in the lithography method is a positive photoresist, and means the ratio of the exposed region to the total surface area of the coating film when the image data of the coating film of the positive photoresist is drawn. . On the other hand, the aperture ratio when the photoresist used in the lithography method is a negative photoresist means that the unexposed area is relative to the coating when the image film of the negative photoresist is drawn. The ratio of the total surface area of the film. The lithography method is an aperture ratio at the time of exposure, and means a ratio of a light-transmitting portion having a light-transmitting portion and a mask of the light-shielding portion. When the aperture ratio of the pattern is too small or too large, the convex portion or the concave portion of the fine uneven surface formed on the mold becomes sparse, and as a result, the unevenness of the surface uneven shape of the obtained anti-glare film becomes sparse, and the kurtosis tends to increase. . The present inventors have found that when the antiglare film is produced from a mold obtained by setting the aperture ratio of the pattern to the above range, the kurtosis Rku of the roughness curve is easily made 4.9 or less.

The anti-glare film of the present invention can be produced by setting the intensity ratios of 之一(0.02)/Γ(0.01) and Γ(0.1)/Γ(0.01) of one-dimensional power spectrum of the pattern to the above range. The mold was produced using the first method of the mold.

In order to produce a pattern having such a power ratio to one-dimensional power spectrum, a pattern made by a random dot (dot) is prepared in advance, or has A pattern (prepared pattern) of a random brightness distribution of shading is determined by a random number or a pseudo-random number generated by a computer, and components of a specific spatial frequency range are removed from the preliminary pattern. The removal of the components of the specific spatial frequency range may be performed by passing the preliminary pattern through a band pass filter.

In order to manufacture an anti-glare film having an anti-glare layer formed with a surface uneven shape according to a predetermined pattern, a mold having a surface unevenness formed by transferring the surface uneven shape formed according to a predetermined pattern onto a concave-convex surface of a transparent support is manufactured. The first method using the mold is an imprint method characterized by forming an antiglare layer on a transparent support.

The imprint method is exemplified by a photoimprint method using a photocurable resin, a thermal imprint method using a thermoplastic resin, or the like. Among them, from the viewpoint of productivity, photolithography is preferred.

In the photoimprint method, a photocurable resin layer is formed on a transparent support (the surface of the transparent support), and the photocurable resin layer is pressed while being pressed against the uneven surface of the mold of the mold, and the uneven surface of the mold of the mold is pressed. A method of transferring a shape to a photocurable resin layer. Specifically, the photocurable resin layer formed by applying a photocurable resin to a transparent support is irradiated with light from the transparent support side in a state in which the surface of the mold is adhered to the surface of the mold (this light-based resin can be used as a photocurable resin) In the case of curing, the photocurable resin (photocurable resin contained in the photocurable resin layer) is cured, and then the transparent support on which the cured photocurable resin layer is formed is peeled off from the mold. The anti-glare film obtained by such a manufacturing method has an optical anti-glare layer after curing. In addition, in view of ease of manufacture, the photocurable resin is preferably an ultraviolet curable resin, and when the ultraviolet curable resin is used, Ultraviolet rays are used for the light to be irradiated (the embossing method using an ultraviolet curable resin as a photocurable resin, hereinafter referred to as "UV imprint method"). In order to manufacture an anti-glare film integrated with a polarizing film, a polarizing film is used as a transparent support. In the imprint method described above, a transparent support may be used instead of a polarizing film.

The type of the ultraviolet curable resin used in the UV imprint method is not particularly limited, and may be suitably used from commercially available resins depending on the type of the transparent support to be used and the type of ultraviolet rays. The ultraviolet curable resin contains a concept of a monomer (polyfunctional monomer), an oligomer, a polymer, and a mixture thereof which are photopolymerized by ultraviolet irradiation. Further, by using a photoinitiator appropriately selected in accordance with the kind of the ultraviolet curable resin, a resin which can be cured even if the wavelength is longer than ultraviolet light can be used. A suitable example of the ultraviolet curable resin and the like will be described later.

For the transparent support used in the UV imprint method, for example, a glass or a plastic film or the like can be used. As far as the plastic film is concerned, it can be used as long as it has appropriate transparency and mechanical strength. Specifically, for example, an acetyl cellulose resin such as TAC (triethylene fluorene cellulose); an acrylic resin; a polycarbonate resin; a polyester resin such as polyethylene terephthalate; polyethylene, poly A transparent resin film made of a polyolefin resin such as propylene. The transparent resin film may be a solvent cast film or an extruded film.

The thickness of the transparent support is, for example, 10 to 500 μm, preferably 10 to 100 μm, more preferably 10 to 60 μm. When the thickness of the transparent support is within this range, an anti-glare film having sufficient mechanical strength tends to be obtained, and an image display device including the anti-glare film is more difficult to generate glare.

On the other hand, the hot stamping method is a method in which the transparent resin film formed of the thermoplastic resin is heated and softened, and pressed against the uneven surface of the mold to transfer the surface uneven shape of the uneven surface of the mold to the transparent resin film. The transparent resin film used in the hot stamping method may be optically transparent, and specifically, a transparent resin film which is exemplified by the UV imprint method may be mentioned.

Next, a method of manufacturing a mold for use in an imprint method will be described.

In the method of manufacturing a mold, the molding surface of the mold is capable of transferring the surface uneven shape formed by the predetermined pattern onto the transparent support (an anti-glare layer capable of forming a surface uneven shape formed according to a predetermined pattern) The range of the uneven surface of the mold is not particularly limited, and a lithography method is preferred in order to produce the anti-glare layer having the surface unevenness with good precision and reproducibility. Furthermore, the lithography method preferably comprises [1] a first plating step, [2] a polishing step, [3] a photosensitive resin film forming step, [4] an exposure step, a [5] developing step, and [ 6] an etching step, [7] a photosensitive resin film peeling step, and [8] a second plating step.

Fig. 6 is a view schematically showing an example of the first half of the method for manufacturing the mold. Figure 6 is a schematic representation of the mold profile in each step. Hereinafter, each step of the method for producing the mold for producing an anti-glare film of the present invention will be described in detail with reference to FIG.

[1] 1st plating step

First, a substrate (a substrate for a mold) used for mold production is prepared, and copper plating is applied to the surface of the substrate for the mold. Thus, by the substrate for the mold The surface is plated with copper to improve the adhesion and gloss of chrome plating in the second plating step described later. Since copper plating has high coating property and strong smoothing action, it can fill a small unevenness, a cavity, or the like of the substrate for a mold to form a flat and shiny surface. Therefore, by applying copper plating to the surface of the substrate for a mold, even if chrome plating is applied in the second plating step described later, it is considered that the chrome-plated surface roughness due to minute irregularities and voids existing in the substrate can be solved. Moreover, from the height of the copper plating coverage, the occurrence of small cracks can be reduced. Therefore, even if the surface unevenness shape (fine uneven surface shape) according to the predetermined pattern is formed on the substrate forming surface for the mold, the influence of the surface of the susceptor (substrate for the mold) such as minute irregularities, voids, and cracks can be sufficiently prevented. To the gap.

For the copper used for the copper plating in the first plating step, a pure copper metal or an alloy containing copper as a main component (copper alloy) may be used. Therefore, the "copper" used in copper plating contains the concept of copper and copper alloy. The copper plating may be electroplating or electroless plating, and the copper plating in the first plating step is preferably electroplating. Further, the preferred plating layer in the first plating step may be formed not only by a copper plating layer but also by a copper plating layer and a plating layer made of a metal other than copper.

When the plating layer formed by plating copper on the surface of the substrate for a mold is too thin, the influence of the surface of the susceptor (fine irregularities, voids, cracks, and the like) cannot be completely excluded, and therefore the thickness thereof is preferably 50 μm or more. The upper limit of the thickness of the plating layer is not limited, but it is preferably about 500 μm or less when considering the cost or the like.

The substrate for the mold is preferably a substrate made of a metal material. Furthermore, from the viewpoint of cost, in terms of the material of the metal material, it is preferably aluminum, Iron and so on. Further, from the viewpoint of the convenience of handling of the substrate for a mold, it is particularly preferable to use a substrate made of lightweight aluminum as a substrate for a mold. Further, the aluminum or iron described herein does not need a pure metal, and may be an alloy mainly composed of aluminum or iron.

The shape of the substrate for a mold may be an appropriate shape in accordance with the method for producing an anti-glare film of the present invention. Specifically, it may be selected from a flat substrate, a cylindrical substrate, or a cylindrical (roller) substrate. When the antiglare film of the present invention is continuously produced, the mold is preferably in the form of a roll. Such a mold is produced from a substrate for a roll mold.

[2] Grinding step

In the subsequent polishing step, the surface (plating layer) of the substrate for mold for copper plating is applied to the first plating step. In the method for producing a mold for use in the method for producing an anti-glare film of the present invention, it is preferred that the surface of the substrate for a mold is polished to a state close to the mirror surface through the polishing step. A commercially available product of a flat substrate or a roll-form substrate used as a substrate for a mold is often subjected to machining such as cutting or polishing in order to form desired precision, whereby fineness remains on the surface of the substrate for the mold. Processing marks. Therefore, even if a plating (preferably copper plating) layer is formed by the first plating step, the above-described processing marks remain. Moreover, even if the plating in the first plating step is applied, the surface of the substrate for a mold does not necessarily become completely smooth. In other words, for the substrate for a mold having a surface having such a deep processing mark or the like, the surface unevenness of the surface of the obtained mold and the surface according to the predetermined pattern may be obtained even if the steps [3] to [8] described later are carried out. The uneven shape may be different, or may include irregularities derived from a work mark or the like. Made with a mold that has the influence of machining marks and the like When an anti-glare film is produced, optical characteristics such as anti-glare property are not sufficiently exhibited, and there is a concern that an unexpected effect is caused.

The polishing method to be applied in the polishing step is not particularly limited, and a polishing method according to the shape/characteristic of the substrate for the mold to be polished is selected. Specific examples of the polishing method applicable to the polishing step include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method. Among these, as the mechanical polishing method, any of a super finishing method, a lapping, a fluid polishing method, and a polishing method can be used. Further, mirror surface cutting can be performed by using a cutting tool in the polishing step so that the surface of the substrate for the mold becomes a mirror surface. The material/shape of the cutting tool at this time may be a hard alloy drill, a CBN drill, a ceramic drill, a diamond drill or the like according to the type of the material (metal material) of the base material for the mold, and is preferably from the viewpoint of processing accuracy. A diamond drill bit is used. The surface roughness after the polishing is expressed by the center line average roughness Ra according to JIS B 0601, and is preferably 0.1 μm or less, more preferably 0.05 μm or less. If the center line average roughness Ra after grinding is more than 0.1 μm, there is a possibility that the surface roughness is left on the uneven surface of the mold of the finally obtained mold. Further, the lower limit of the center line average roughness Ra is not particularly limited. Therefore, from the viewpoint of the processing time (grinding time) and the processing cost in the grinding step, it is only necessary to define the lower limit.

[3] Photosensitive resin film forming step

Next, a photosensitive resin film forming step will be described with reference to Fig. 6 .

In the photosensitive resin film forming step, a solution (photosensitive resin solution) obtained by dissolving a photosensitive resin in a solvent is applied to the surface 41 of the substrate 40 for mirror polishing which has been subjected to mirror polishing obtained by the above-described polishing step. Re-enter Heating/drying is performed to form a photosensitive resin film (photoresist film). In the sixth embodiment, a state in which the photosensitive resin film 50 is formed on the surface 41 of the mold substrate 40 is schematically shown (Fig. 6(b)).

As the photosensitive resin, a conventionally known photosensitive resin can be used, and it can be used as it is, or can be used as a photoresist, or can be purified by filtration or the like as needed. For example, in the case of a negative-type photosensitive resin having a photosensitive partially hardened property, a monomer or prepolymer or a double layer for a (meth) acrylate having an acrylonitrile group or a methacryl fluorenyl group in a molecule can be used. A mixture of a nitride and a diene rubber, a polyvinyl cinnamate compound, or the like. In addition, a positive-type photosensitive resin having a property of dissolving a photosensitive portion by development and leaving only an unexposed portion may be a phenol resin-based or novolak resin-based resin. Such a positive-working or negative-type photosensitive resin can be easily obtained as a positive photoresist or a negative photoresist from the market. Further, the photosensitive resin solution may be formulated with various additives such as a sensitizer, a development accelerator, an adhesion modifier, and a coatability improver, and may be used by mixing such an additive into a commercially available photoresist. The original is used as a photosensitive resin solution.

When the photosensitive resin solution is applied to the surface 41 of the substrate 40 for a mold, it is preferred to form a smoother photosensitive resin film, and then an optimum solvent is selected, and the photosensitive resin is dissolved/diluted in the surface. A photosensitive resin solution obtained by a solvent. Such a solvent is further selected depending on the kind of the photosensitive resin and its solubility. Specifically, for example, it is selected from a ceramide solvent, a propylene glycol solvent, an ester solvent, an alcohol solvent, a ketone solvent, a highly polar solvent, and the like. When using a commercially available photoresist, select the most appropriate photoresist according to the type of solvent contained in the photoresist or by performing appropriate preliminary experiments. It can be used as a photosensitive resin solution.

The method of applying the photosensitive resin solution to the mirror-polished surface of the substrate for a mold can be applied from meniscus coating, spray coating, dip coating, spin coating, roll coating, wire coating, pneumatic Among known methods such as blade coating, blade coating, curtain coating, and ring coating, the shape of the substrate for a mold or the like is selected. The thickness of the photosensitive resin film after coating is preferably in the range of 1 to 10 μm after drying, more preferably in the range of 6 to 9 μm.

[4] Exposure step

Then, the exposure step is a step of transferring the target pattern to the photosensitive resin film 50 by exposing the photosensitive resin film 50 formed in the photosensitive resin film forming step. The light source used in the exposure step may be appropriately selected as long as it conforms to the photosensitive wavelength, sensitivity, and the like of the photosensitive resin contained in the photosensitive resin film, and for example, a g line (wavelength: 436 nm) of a high pressure mercury lamp, and an h line (wavelength: 405 nm), or i-line (wavelength: 365 nm), semiconductor laser (wavelength: 830 nm, 532 nm, 488 nm, 405 nm, etc.), YAG laser (wavelength: 1064 nm), KrF excimer laser (wavelength: 248 nm), ArF Molecular laser (wavelength: 193 nm), F2 excimer laser (wavelength: 157 nm), and the like. The exposure mode may be one of using a mask corresponding to the pattern of the purpose and the exposure mode, or may be a drawing mode. Furthermore, the pattern of the purpose is as described above, so that the intensity ratios Γ(0.02)/Γ(0.01) and Γ(0.1)/Γ(0.01) of the spatial frequency of the one-dimensional power spectrum are set to respective predetermined preferred ranges.

In the method for producing a mold, in order to form the uneven shape of the surface of the mold with higher precision, it is preferable to expose the intended pattern on the photosensitive resin film in a state of being precisely controlled. In order to be exposed in this state, The system produces the pattern of the target as image data on the computer, and draws (laser draws) on the photosensitive resin film by the laser light emitted from the computer-controlled laser head according to the pattern of the image data. on. When performing laser drawing, for example, a general-purpose laser drawing device such as a printing plate production can be used. A commercially available product of such a laser drawing device is, for example, a Laser Stream FX (Think Laboratory).

Fig. 6(c) is a view schematically showing a state in which the photosensitive resin film 50 is exposed to the pattern. When the photosensitive resin film 50 contains a negative-type photosensitive resin (for example, when a negative photoresist is used as a photosensitive resin solution), the exposed region 51 receives exposure energy and performs a crosslinking reaction of a photosensitive resin, which will be described later. The solubility of the developing solution is lowered. Therefore, the unexposed area 52 in the developing step is dissolved by the developing liquid, and only the exposed region 51 remains on the surface of the substrate to become the mask 60. On the other hand, when the photosensitive resin film 50 contains a positive-type photosensitive resin (for example, when a positive photoresist is used as the photosensitive resin solution), the exposed region 51 receives exposure energy and the combination of the photosensitive resin is cut off. This is easy to dissolve in the developing liquid described later. Therefore, in the developing step, the exposed region 51 is dissolved by the developing liquid, and only the unexposed region 52 remains on the surface of the substrate to become the mask 60.

[5] imaging steps

In the development step, when the photosensitive resin film 50 contains a negative-type photosensitive resin, the unexposed region 52 is dissolved by the developing solution, and the exposed region 51 remains on the substrate for the mold to form the mask 60. On the other hand, when the photosensitive resin film 50 contains a positive-type photosensitive resin, only the exposed region 51 is dissolved by the developing solution, and the unexposed region 52 remains in the mold base. On the material, it becomes a mask 60. The base material for a mold which is formed by using a predetermined pattern as a photosensitive resin film is a masking action in an etching step to be described later in the etching step in the photosensitive resin film remaining on the substrate for a mold.

The developing liquid used in the developing step can be selected from conventionally known ones depending on the type of photosensitive resin to be used. For example, examples of the developing liquid include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium citrate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine; a secondary amine such as a base amine or a di-n-butylamine; a tertiary amine such as triethylamine or methyldiethylamine; an alcohol amine such as dimethylethanolamine or triethanolamine; and tetramethylammonium hydroxide. a tetrabasic ammonium compound such as tetraethylammonium hydroxide or trimethylhydroxyethylammonium hydroxide; an aqueous alkaline solution such as a cyclic amine such as pyrrole or piperidine; or an organic solvent such as xylene or toluene.

The developing method in the developing step is not particularly limited, and immersion development, spray development, brush development, ultrasonic imaging, or the like can be used.

Fig. 6(d) is a view schematically showing a state in which a negative film type is used as a photosensitive resin and a developing step is performed. In Fig. 6(d), the unexposed region 52 is dissolved by the developing solution, and only the exposed region 51 remains on the surface of the substrate, and the photosensitive resin film in this region serves as the mask 60. Fig. 6(e) is a view schematically showing a state in which a positive type is used as a photosensitive resin and a developing step is performed. In Fig. 6(e), the exposed region 51 is dissolved by the developing solution, and only the unexposed region 52 remains on the surface of the substrate, and the photosensitive resin film in this region serves as the mask 60.

[6] Etching step

The etching step is performed on the substrate for mold after using the above development step The photosensitive resin film on the surface is used as a mask, and the surface of the substrate for a mold is mainly etched in the plating layer in the unmasked region.

Fig. 7 is a view schematically showing a preferred example of the latter half of the method of manufacturing the mold. Fig. 7(a) is a view schematically showing a state in which the plating layer of the maskless region is mainly etched by the etching step. The plating layer on the lower portion of the mask 60, the photosensitive resin film acts as a mask 60 and is not etched, but is etched from the maskless region 45 as the etching progresses. Thus, in the vicinity of the boundary between the region having the mask 60 and the unmasked region 45, the plating layer under the mask 60 is also etched. Thus, in the vicinity of the boundary between the region having the mask 60 and the unmasked region 45, the case where the plating layer under the mask 60 is also etched is referred to as side etching.

The etching treatment in the etching step is usually performed by using an iron (III) (FeCl ₃ ) solution, a copper (II) chloride (CuCl ₂ ) solution, or an alkali etching solution (Cu(NH ₃ ) ₄ Cl ₂ ). In the surface of the substrate for the mold, the plating layer (metal surface) of the region without the mask 60 is mainly etched. In the etching treatment, a strong acid such as hydrochloric acid or sulfuric acid may be used as the etching liquid. When the plating layer is formed by plating, etching treatment may be performed by reverse electrolytic etching by applying a potential opposite to that during plating. The surface unevenness shape formed by the base material for the mold during the etching treatment is based on the constituent material (metal material) of the base material for the mold, the type of the plating layer, the type of the photosensitive resin film, and the etching step. The type of the etching treatment varies depending on the type of the etching treatment, and when the etching amount is 10 μm or less, the surface of the substrate for the mold which is in contact with the etching liquid is slightly isotropically etched. The amount of etching referred to herein is the thickness of the plating layer which is removed by etching.

The etching amount in the etching step is preferably 1 to 10 μm, more preferably 3 to 6 μm. When the etching amount exceeds 10 μm, the surface unevenness formed on the mold becomes a large difference in unevenness. As a result, when the antiglare film is produced using the mold, whitening sometimes occurs. On the other hand, when the etching amount is less than 1 μm, the surface irregularities are hardly formed in the mold, and the mold has a nearly flat surface. Therefore, even if the mold is used to manufacture an anti-glare film, the anti-glare film has almost no surface unevenness. Therefore, an anti-glare film having sufficient anti-glare property cannot be obtained. Further, the etching treatment in the first etching step may be performed by one etching treatment, or may be performed by dividing the etching treatment into two or more times. Here, when the etching treatment is carried out in two or more steps, the total amount of etching in the etching treatment of two or more times is preferably 1 to 10 μm.

[7] Photosensitive resin film peeling step

Next, the photosensitive resin film peeling step is a step of acting as a mask 60 in the etching step and removing the photosensitive resin film remaining on the substrate for a mold, and it is preferable to completely remove the substrate for the mold by this step. The photosensitive resin film remaining. In the photosensitive resin film peeling step, it is preferred to use a peeling liquid to dissolve the photosensitive resin film. The peeling liquid system can be prepared by changing the concentration, pH, and the like of the developer as a developing solution. Alternatively, the photosensitive resin film may be peeled off by changing the temperature of the development step, the immersion time, or the like, in the same manner as the development liquid used in the development step. In the photosensitive resin film peeling step, the contact method (peeling method) of the peeling liquid and the substrate for a mold is not particularly limited, and immersion peeling, spray peeling, brush peeling, ultrasonic peeling, or the like can be used.

Fig. 7(b) is a view schematically showing a photosensitive resin film peeling step used in the etching step to completely dissolve the photosensitive resin film used as the mask 60 in the etching step. The state of the solution is removed. The first surface uneven shape 46 is formed on the surface of the substrate for a mold by the mask 60 by the photosensitive resin film and the etching treatment.

[8] 2nd plating step

The final step of the mold manufacturing is a second plating step of plating (preferably chrome plating described later) on the surface of the substrate for a mold which has been subjected to the above steps [6] and [7]. By performing the second plating step, the surface uneven shape 46 of the substrate for a mold can be made gentle, and the surface of the mold can be protected by the plating. Hereinafter, the case where the surface unevenness of the base material for a mold is gentle is referred to as "shape passivation". Fig. 7(c) shows a state in which the chrome plating layer 71 is formed on the first surface uneven shape 46 formed by the etching treatment, and the surface uneven shape is passivated (the mold uneven surface 70) as described above.

The plating layer formed by the second plating step is preferably chrome-plated from the viewpoint of high gloss, high hardness, small friction coefficient, and good release property. Among the chrome plating, the special type is called chrome plating which exhibits good gloss such as gloss chrome plating and decorative chrome plating. The chrome plating is usually carried out by electrolysis, and in the case of the plating bath, an aqueous solution containing chromic anhydride (CrO ₃ ) and a small amount of sulfuric acid can be used as the plating solution. The thickness of the chrome plating layer can be controlled by adjusting the current density and the electrolysis time.

Thus, by applying the plating (preferably chrome plating) in the second plating step, the mold for producing an anti-glare film of the present invention can be obtained. By chrome plating, the surface irregularities of the surface of the substrate for the mold after the etching treatment can be passivated, and a mold whose surface hardness is improved can be obtained. To the extent that the shape passivation at this time is controlled, the largest factor is the thickness of the chrome layer. If the thickness is thin, the degree of shape passivation becomes insufficient, and the result of using such a mold is obtained. The anti-glare film has a whitening effect. On the other hand, when the thickness of the chrome plating layer is too thick, the degree of shape passivation becomes too large, and the antiglare film obtained by using such a mold tends to have insufficient antiglare properties. The present inventors have found that an anti-glare film for an image display device which is excellent in preventing the occurrence of whitening and which has excellent anti-glare properties is effective in producing a mold so that the thickness of the chromium plating layer becomes a predetermined range. That is, the thickness of the chrome plating layer is preferably in the range of 10 to 20 μm, more preferably in the range of 12 to 16 μm.

The chrome plating layer formed in the second plating step is preferably formed so that the Vickers hardness is 800 or more. More preferably, it is formed in a manner of becoming 1000 or more. When the Vickers hardness of the chrome plating layer is less than 800, when the antiglare film is produced using a mold, the durability of the mold tends to be lowered.

The above-described photoimprint method which is preferable as a method for producing the antiglare film of the present invention will be described below. As described above, as a photoimprinting method, a UV imprint method is particularly preferred. Here, an imprint method using an active energy ray-curable resin will be specifically described.

In order to continuously produce the anti-glare film of the present invention, when the anti-glare film of the present invention is produced by photoimprinting, it is preferred to have the following steps: [P1] coating a coating liquid containing an active energy ray-curable resin a coating step of forming a coating layer on a transparent support continuously transported; and [P2] mainly hardening the surface of the coating layer from the side of the transparent support by irradiating the active energy line in a state of pressing against the surface of the mold step.

Further, when the antiglare film of the present invention is produced by photoimprinting, it is more preferable to further include the following steps: [P3] The preliminary hardening step of irradiating the active energy ray in the end region of both of the width directions of the coating layer after the coating step [P1] and before the hardening step [P2].

Hereinafter, each step will be described in detail with reference to the drawings. Fig. 8 is a view schematically showing a preferred example of a manufacturing apparatus used in the method for producing an anti-glare film of the present invention. The arrows in Fig. 8 indicate the transport direction of the film or the direction of rotation of the rolls.

[P1] Coating step

In the coating step, a coating liquid containing an active energy ray-curable resin is applied onto a transparent support to form a coating layer. In the coating step, for example, as shown in FIG. 8, the coating liquid containing the active energy ray-curable resin composition is applied to the transparent support 81 discharged from the delivery roller 80 in the application zone 83.

The application of the coating liquid to the transparent support 81 can be performed by, for example, a gravure coating method, a micro gravure coating method, a rod coating method, a knife coating method, a pneumatic blade coating method, or an anastomosis coating method (kiss Coating), mold coating method, etc. are carried out.

(transparent support)

As long as the transparent support 81 is translucent, for example, glass, a plastic film, or the like can be used. As far as the plastic film is concerned, it is only necessary to have moderate transparency and mechanical strength. Specifically, any of the transparent supports used as the UV imprint method can be used, and in order to further continuously manufacture the anti-glare film of the present invention by photoimprinting, it is selected to have moderate flexibility. By.

To improve the applicability of the coating liquid, the transparent support and the coating layer For the purpose, the surface of the transparent support 81 (coating layer side surface) can be subjected to various surface treatments. Examples of the surface treatment include corona discharge treatment, glow discharge treatment, acid surface treatment, alkali surface treatment, ultraviolet irradiation treatment, and the like. Further, another layer such as a primer layer may be formed on the transparent support 81, and a coating liquid may be applied to the other layer.

Further, when the antiglare film of the present invention is produced by integrating with a polarizing film, in order to improve the adhesion between the transparent support and the polarizing film, it is preferred to first surface (and coat) the transparent support by various surface treatments. The surface on the opposite side of the layer is hydrophilized. This surface treatment can also be carried out after the production of the anti-glare film.

(coating liquid)

The coating liquid contains an active energy ray-curable resin, and usually contains a photopolymerization initiator (radical polymerization initiator). Various additives such as a solvent such as a light-transmitting fine particle or an organic solvent, a leveling agent, a dispersing agent, an antistatic agent, an antifouling agent, and a surfactant may be contained as needed.

(1) Active energy ray-curable resin

As the active energy ray-curable resin, for example, a compound containing a polyfunctional (meth) acrylate compound can be suitably used. The polyfunctional (meth) acrylate compound refers to a compound having at least two (meth) acryloxy groups in the molecule. Specific examples of the polyfunctional (meth) acrylate compound include, for example, an ester compound of a polyhydric alcohol and a (meth) acrylate, a urethane (meth) acrylate compound, and a polyester (meth) acrylate compound. A polyfunctional polymerizable compound containing two or more (meth)acryl fluorenyl groups, such as an epoxy group (meth) acrylate compound.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, and propanediol. Butane diol, pentane diol, hexane diol, neopentyl glycol, 2-ethyl-1,3-hexane diol, 2,2'-thiodiethanol, 1,4-two A dihydric alcohol such as methanol; an alcohol having 3 or more yuan such as trimethylolpropane, glycerin, neopentyl alcohol, diglycerin, dipentaerythritol or trimethylolpropane.

Specific examples of the ester of a polyhydric alcohol and (meth)acrylic acid include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and 1,6-hexane two. Alcohol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, tetrahydroxyl Methyl methane tri(meth)acrylate, 1,6-hexanediol di(meth)acrylate, tetramethylol methane tetra(meth)acrylate, pentatriol tri(meth)acrylic acid Ester, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, Dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate.

The urethane (meth) acrylate compound may, for example, be an organic isocyanate having a plurality of isocyanate groups in one molecule and an urethanation reaction product with a (meth)acrylic acid derivative having a hydroxyl group. Examples of the organic isocyanate having a plurality of isocyanate groups in one molecule include hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, and benzodimethyl group. Isocyanide An organic isocyanate having two isocyanate groups in one molecule such as an acid ester or dicyclohexylmethane diisocyanate; and the organic isocyanate is modified by an isomeric cyanurate, an addition product is modified, and a diuret is modified. An organic isocyanate having three isocyanate groups in the molecule. Examples of the (meth)acrylic acid derivative having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. 2-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, neopentyl alcohol triacrylate.

In the case of the polyester (meth) acrylate compound, a polyester (meth) acrylate obtained by reacting a hydroxyl group-containing polyester with (meth) acrylic acid is preferred. Suitable hydroxyl group-containing polyesters are hydroxyl group-containing polyesters obtained by esterification of a polyol with a carboxylic acid or a compound having a plurality of carboxyl groups and/or an anhydride thereof. The polyol is the same as the aforementioned compound. Further, examples of the phenols other than the polyhydric alcohol include bisphenol A and the like. Examples of the carboxylic acid include formic acid, acetic acid, butyric acid, benzoic acid, and the like. Examples of the compound having a plurality of carboxyl groups and/or an acid anhydride thereof include maleic acid, citric acid, fumaric acid, itaconic acid, adipic acid, p-citric acid, maleic anhydride, phthalic anhydride, and benzoic acid. Formic acid, cyclohexane dicarboxylic acid anhydride, and the like.

Among the above polyfunctional (meth) acrylate compounds, hexane diol di(meth) acrylate and neopentyl glycol are preferred from the viewpoint of improvement in strength of the cured product and ease of availability. Di(meth)acrylate, diethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol three (a) Ester ester compound such as acrylate or dipentaerythritol hexa(meth)acrylate; hexamethylene diisocyanate An adduct of an ester with 2-hydroxyethyl (meth)acrylate; an adduct of isophorone diisocyanate with 2-hydroxyethyl (meth)acrylate; toluene diisocyanate and 2-hydroxyl (meth)acrylate An adduct of ethyl ester; an adduct to modify an adduct of isophorone diisocyanate with 2-hydroxyethyl (meth)acrylate; and a biuret-modified isophorone diisocyanate and (meth)acrylic acid An adduct of 2-hydroxyethyl ester. Further, these polyfunctional (meth) acrylate compounds may be used alone or in combination of two or more.

The active energy ray-curable resin may further contain a monofunctional (meth) acrylate compound in addition to the above polyfunctional (meth) acrylate compound. The monofunctional (meth) acrylate compound may, for example, be methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate or isobutyl (meth) acrylate, ( Tert-butyl methacrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate , 2-hydroxy-3-phenoxypropyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydroanthracene (meth)acrylate Ester, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, ethionyl (meth)acrylate, benzyl (meth)acrylate , 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth) acrylate, phenoxy (meth) acrylate, ring Oxygen ethane modified phenoxy (meth) acrylate, propylene oxide (meth) acrylate, nonyl phenol (meth) acrylate, ethylene oxide modified (meth) acrylate, epoxy Propane modified nonylphenol (meth) acrylate, A Oxydiethylene glycol (meth) acrylate, 2-(methyl) propylene methoxyethyl 2-hydroxypropyl phthalate, (methyl) propyl (Meth) acrylates such as dimethyl phthalic acid ethyl acrylate and methoxy triethylene glycol (meth) acrylate. These compounds may be used alone or in combination of two or more.

Further, the active energy ray-curable resin may contain a polymerizable oligomer. The hardness of the cured product can be adjusted by containing a polymerizable oligomer. The polymerizable oligomer may be, for example, the aforementioned polyfunctional (meth) acrylate compound, that is, an ester compound of a polyhydric alcohol and a (meth) acrylate, a urethane (meth) acrylate compound, a polyester (methyl group). An oligomer such as a dimer or a trimer such as an acrylate compound or an epoxy (meth) acrylate.

The other polymerizable oligomers may be exemplified by a reaction of a polyisocyanate having at least two isocyanate groups in the molecule and a polyol having at least one (meth) acryloxy group. Ester (meth) acrylate oligomer. The polyisocyanate may, for example, be a polymer of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate or benzodimethyl diisocyanate, and has at least one (A) The propylene oxy group-containing polyol may, for example, be a hydroxyl group-containing (meth) acrylate obtained by esterification of a polyhydric alcohol with (meth)acrylic acid, and the polyhydric alcohol may, for example, be 1, 3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, neopentyl glycol, polyethylene glycol, polypropylene glycol, trihydroxyl Methylpropane, glycerol, neopentyl alcohol, dipentaerythritol, and the like. One part of the alcoholic hydroxyl group of the polyol-based polyol having at least one (meth)acryloxy group is reacted with the (meth)acrylic acid ester, and the alcoholic hydroxyl group remains in the molecule.

Furthermore, as an example of other polymerizable oligomers, A polyester (meth) acrylate oligomer obtained by reacting a compound having a plurality of carboxyl groups and/or an acid anhydride thereof with a polyol having at least one (meth) acryloxy group. The compound having a plurality of carboxyl groups and/or an acid anhydride thereof may be the same as those described for the polyester (meth) acrylate of the above polyfunctional (meth) acrylate compound. In addition, the polyol having at least one (meth) acryloxy group may be the same as those described for the urethane (meth) acrylate oligomer.

Further, not only the above polymerizable oligomers, but also examples of the urethane (meth) acrylate oligomers may be exemplified for the hydroxyl group-containing polyester, the hydroxyl group-containing polyether or the hydroxyl group ( A compound obtained by reacting a hydroxyl group of a methyl acrylate to an isocyanate. Suitable hydroxyl group-containing polyesters are hydroxyl group-containing polyesters obtained by esterification of a polyol with a carboxylic acid or a compound having a plurality of carboxyl groups and/or an anhydride thereof. The polyol or a compound having a plurality of carboxyl groups and/or an acid anhydride thereof can be exemplified by the same as those described for the polyester (meth) acrylate compound of the polyfunctional (meth) acrylate compound. The hydroxyl group-containing polyether which is suitably used is a hydroxyl group-containing polyether obtained by adding one or more kinds of alkylene oxide and/or ε-caprolactone to a polyol. The polyol may be the same as the user of the aforementioned hydroxyl group-containing polyester. The hydroxyl group-containing (meth) acrylate which is suitably used may be the same as those described for the urethane (meth) acrylate oligomer of the polymerizable oligomer. The isocyanate is preferably a compound having one or more isocyanate groups in the molecule, and particularly preferably a divalent isocyanate compound such as toluene diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate.

These polymerizable oligomer compounds may be used singly or in combination of two kinds. The above is used together.

(2) Photopolymerization initiator

The photopolymerization initiator can be appropriately selected in accordance with the kind of active energy ray which is suitable for the production of the antiglare film of the present invention. Further, when an electron beam is used as the active energy ray, a coating liquid containing no photopolymerization initiator may be used in the production of the antiglare film of the present invention.

As the photopolymerization initiator, for example, an acetophenone-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a thioxanthone system can be used. Photopolymerization initiator, three Photopolymerization initiator, A bisazole photopolymerization initiator or the like. Further, as the photopolymerization initiator, for example, 2,4,6-trimethylbenzimidyldiphenylphosphine oxide or 2,2'-bis(o-chlorophenyl)-4 can also be used. , 4',5,5'-tetraphenyl-1,2'-biimidazole, 10-butyl-2-chloroacridone, 2-ethylhydrazine, diphenylethylenedione, 9,10- Phenanthrene, camphorquinone, methyl phenylglyoxylate, titanium titanate compound, and the like. The photopolymerization initiator is usually used in an amount of from 0.5 to 20 parts by weight, preferably from 1 to 5 parts by weight, per 100 parts by weight of the active energy ray-curable resin.

In order to improve the applicability to a transparent support, the coating liquid may contain a solvent, such as an organic solvent. In terms of the organic solvent, the viscosity can be selected from the following: aliphatic hydrocarbons such as hexane, cyclohexane, and octane; aromatic hydrocarbons such as toluene and xylene; ethanol, 1-propanol, and the like. Alcohols such as propanol, 1-butanol and cyclohexanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as ethyl acetate, butyl acetate and isobutyl acetate; ; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene glycol monomethyl ether Acetate, Esterified glycol ethers such as propylene glycol monomethyl ether acetate; sirolimus such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol; 2-(2-methoxyl) An ethoxylated alcohol such as ethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol or 2-(2-butoxyethoxy)ethanol. These solvents may be used singly or in combination of several kinds as needed. The above organic solvent must be evaporated after coating. Therefore, the boiling point is preferably in the range of 60 ° C to 160 ° C. Further, the saturated vapor pressure at 20 ° C is preferably in the range of 0.1 kPa to 20 kPa.

When the coating liquid contains a solvent, it is preferred to provide a drying step of evaporating the solvent and drying it after the coating step and before the first curing step. The drying is carried out, for example, as shown in Fig. 8, by passing the transparent support 81 having the coating layer through the drying zone 84. The drying temperature is appropriately selected depending on the type of solvent or transparent support to be used. Generally, it is in the range of 20 ° C to 120 ° C, but is not limited thereto. Moreover, when there are a plurality of drying furnaces, the temperature of the drying furnace can be changed one by one. The thickness of the coated layer after drying is preferably from 1 to 30 μm.

In this way, a laminate in which a transparent support and a coating layer are laminated can be formed.

[P2] hardening step

In this step, the active energy ray is irradiated from the transparent support side to the surface of the coating layer by pressing the concave-convex surface (forming surface) of the mold having the desired surface unevenness shape, and the coating layer is hardened to be transparent. A step of forming a hardened resin layer on the support. Thereby, the coating layer is hardened, and the surface uneven shape of the uneven surface of the mold is transferred to the surface of the coating layer. The mold used herein is a roll, and is made in the mold manufacturing method described above. A manufacturer of a substrate for a roll mold.

This step is, for example, as shown in Fig. 8, by preliminary hardening which is further irradiated to the active energy ray irradiation device 86 by having passed through the application zone 83 (the dry zone 84 when drying is performed, and the preliminary hardening step described later is performed). The layered body of the coating layer of the region is irradiated with the active energy ray by using the active energy ray irradiation device 86 such as an ultraviolet ray irradiation device disposed on the side of the transparent support 81.

First, the roll-shaped mold 87 is pressed against the surface of the coating layer of the laminated body subjected to the hardening step by using a crimping device such as the nip roller 88, and the active energy ray irradiation device 86 is used in this state to illuminate from the transparent support 81 side. The coating layer 82 is hardened by the active energy ray. Here, "curing the coating layer" means that the active energy ray-curable resin contained in the coating layer receives the energy of the active energy ray to cause a curing reaction. The use of the nip rolls is effective for preventing air bubbles from entering between the coating layer of the laminate and the mold. One or a plurality of active energy ray irradiation devices can be used.

After the active energy ray irradiation, the laminated system is peeled off from the mold 87 with the nip roller 89 on the outlet side as a fulcrum. The obtained transparent support and the hardened coating layer are used as an antiglare layer to obtain an antiglare film of the present invention. The resulting anti-glare film is typically rewinded by a film rewinding device 90. In this case, for the purpose of protecting the anti-glare layer, the protective film made of polyethylene terephthalate or polyethylene may be attached to the surface of the anti-glare layer via a pressure-sensitive adhesive layer having removability. Rewind. In addition, although the case where the mold used here is a roll shape has been described, a mold other than a roll shape can also be used. Further, after being peeled off from the mold, additional active energy ray irradiation may be performed.

The active energy ray used in this step can be appropriately selected from ultraviolet rays, electron beams, near ultraviolet rays, visible rays, near infrared rays, infrared rays, X-rays, etc. depending on the type of active energy ray-curable resin contained in the coating liquid. Among these, ultraviolet rays and electron beams are preferred, and ultraviolet rays are particularly preferable from the viewpoint of easy operation and high energy (as in the above, in the case of photoimprinting, UV imprinting is preferred).

As the light source of the ultraviolet light, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, an electrodeless lamp, a metal halide lamp, a xenon arc lamp, or the like can be used. Further, an ArF excimer laser, a KrF excimer laser, an excimer lamp, or synchrotron radiation may be used. Among these, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, an electrodeless lamp, a xenon arc lamp, and a metal halide lamp can be suitably used.

Further, as for the electron beam, a Cockcroft-Walton type, a van de Graaff type, a resonance transformer type, an insulating core transformer type, and a straight type can be cited. An electron beam having an energy of 50 to 1000 keV (preferably 100 to 300 keV) emitted by various electron beam accelerators such as Dynamitron type and high frequency type.

When the active energy ray is ultraviolet ray, the cumulative amount of light in the ultraviolet ray of UVA is preferably 100 mJ/cm ² or more and 3,000 mJ/cm ² or less, more preferably 200 mJ/cm ² or more and 2000 mJ/cm ² or less. Further, since the transparent support absorbs the ultraviolet rays on the short-wavelength side, the amount of the ultraviolet light UVV (395 to 445 nm) in the wavelength region including the visible light is preferably adjusted so as to suppress the absorption. . The cumulative amount of light in the UVV is preferably 100 mJ/cm ² or more and 3000 mJ/cm ² or less, more preferably 200 mJ/cm ² or more and 2000 mJ/cm ² or less. When the cumulative amount of light is less than 100 mJ/cm ² , the hardening of the coating layer is insufficient, and the hardness of the obtained antiglare layer is lowered, or the unhardened resin adheres to the guide roller or the like, which tends to cause contamination of the step. Further, when the cumulative amount of light exceeds 3,000 mJ/cm ² , the transparent support may be shrunk from the heat radiated from the ultraviolet irradiation device to cause wrinkles.

[P3] preliminary hardening step

This step is a step of irradiating the both ends of the transparent support of the coating layer in the width direction to the active energy rays before the hardening step, and preliminarily hardening the both end regions. Figure 9 is a schematic cross-sectional view of the preliminary hardening step. In Fig. 9, the end portion 82b of the coating layer in the width direction (the direction orthogonal to the conveying direction) is a region including the end portion of the coating layer and having a predetermined width from the end portion.

In the preliminary hardening step, by hardening the end region in advance, the adhesion to the transparent support 81 is further enhanced in the end region, and in the step after the hardening step, a part of the hardened resin is prevented from peeling off. To the step of pollution. The end region 82b can be, for example, a region of 5 mm or more and 50 mm or less from the end portion of the coating layer 82.

The irradiation of the active energy ray of the end region of the coating layer is referred to in Figs. 8 and 9, for example, by coating layer 82 having passed through coating zone 83 (drying zone 84 when dried) The transparent support 81 is irradiated with an active energy ray by using an active energy ray irradiation device 85 such as an ultraviolet ray irradiation device provided in the vicinity of both end portions on the coating layer 82 side. The active energy ray irradiation device 85 may be provided on the side of the transparent support 81 as long as it can illuminate the end region 82b of the coating layer 82 with an active energy ray.

The type of active energy line and the source of the light source are the same as the main hardening step. When the active energy ray is ultraviolet ray, the cumulative amount of light in the UVA of ultraviolet light is preferably 10 mJ/cm ² or more and 400 mJ/cm ² or less, more preferably 50 mJ/cm ² or more and 400 mJ/cm ² or less. By irradiating at 50 mJ/cm ² or more, deformation in the main hardening step can be more effectively prevented. In addition, when it exceeds 400 mJ/cm ² and the hardening reaction progresses excessively, the boundary between the hardened portion and the uncured portion may be peeled off due to a difference in film thickness or strain of internal stress.

[Use of Anti-glare Film of the Present Invention]

The anti-glare film of the present invention obtained in the above manner can be used for an image display device or the like, and is usually used as a polarizing film for the identification side protective film of the identification-side polarizing plate (that is, disposed on the image display device). surface). Further, as described above, when a polarizing film is used as the transparent support, an anti-glare film of a polarizing film-integrated type can be obtained, and the anti-glare film of the polarizing film-integrated type can be used for an image display device. The image display device including the anti-glare film of the present invention has sufficient anti-glare property at a wide viewing angle, and can well prevent whitening and glare.

(Example)

Hereinafter, the present invention will be described in more detail by way of examples. In the example, the "%" and "parts" indicating the content or the amount used are based on weight unless otherwise noted.

The evaluation method of the mold or the anti-glare film in the following examples is as follows.

[1] Determination of the surface shape of an anti-glare film

(surface roughness parameter of surface uneven shape)

The surface roughness parameter of the anti-glare film was measured using a surface roughness measuring machine Surftest SJ-301 manufactured by Mitutoyo Co., Ltd. according to JIS B 0601. In order to prevent the warpage of the sample, an optically transparent adhesive is attached to the glass substrate so that the uneven surface becomes a surface, and then it is provided for measurement.

(power spectrum of the elevation of the surface relief shape)

The elevation of the surface uneven shape of the antiglare layer of the antiglare film as the measurement sample was measured using a three-dimensional microscope PL μ 2300 (manufactured by Sensofar Co., Ltd.). In order to prevent the warpage of the sample, an optically transparent adhesive is used, and the surface of the measurement sample opposite to the antiglare layer is bonded to the glass substrate, and then provided for measurement. At the time of measurement, the magnification of the objective lens was set to 10 times and the measurement was performed. The horizontal resolutions Δx and Δy were both 1.66 μm, and the measurement area was 1270 μm × 950 μm. From the central portion of the obtained measurement data, 512 × 512 (measurement area: 850 μm × 850 μm) data were sampled, and the elevation of the surface uneven shape (surface unevenness of the antiglare layer) of the antiglare film was determined as a two-dimensional The function h(x, y). Next, the two-dimensional function h(x, y) is discretely Fourier transformed to obtain a two-dimensional function H(f _x , f _y ). Calculate the two-dimensional function I(f _x , f _y ) of the two-dimensional power spectrum by square the absolute value of the two-dimensional function H(f _x , f _y ), and calculate the power spectrum of one of the functions of the distance f from the origin. One-dimensional function I(f). The elevation of the surface irregularities of each of the five samples was measured, and the average value of the one-dimensional function I(f) of the one-dimensional power spectrum calculated by the data was used as one of the dimensional functions I of the power spectrum of each sample ( f).

[2] Determination of optical properties of anti-glare film

(haze)

The full haze of the anti-glare film is bonded to the glass substrate by using an optically transparent adhesive, and the surface of the measurement sample opposite to the anti-glare layer is bonded to the glass substrate, and the anti-glare is adhered to the glass substrate. The film was incident on the glass substrate side, and the anti-glare film was measured by a haze meter "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd. according to the method of JIS K 7136. The surface haze is obtained by subtracting the internal haze from the full haze by determining the internal haze of the anti-glare film: surface haze = full haze - internal haze internal haze is The antiglare layer of the measurement sample after the measurement of the full haze was measured by attaching a propylene glycol film having a haze of almost 0 to glycerol, and measuring it in the same manner as the full haze.

(penetration clarity)

The penetration clarity of the anti-glare film was measured by the image sharpness measuring device "ICM-1DP" manufactured by Suga Tester Co., Ltd. according to the method of JIS K 7105. At this time, in order to prevent the warpage of the sample, an optically transparent adhesive was used, and the surface of the measurement sample opposite to the antiglare layer was bonded to the glass substrate, and then provided for measurement. In this state, light was incident from the side of the glass substrate, and measurement was performed. Here, the measured values are the total values of the values measured by using five types of optical combs having a width of the dark portion and the bright portion of 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively.

(reflection resolution measured at a light incident angle of 45°)

The reflection sharpness of the anti-glare film was measured by the image sharpness measuring device "ICM-1DP" manufactured by Suga Tester Co., Ltd. according to the method of JIS K 7105. At this time, in order to prevent the warpage of the sample, an optically transparent adhesive is used. The coating was applied to a black acrylic substrate after the surface of the measurement sample on the opposite side to the antiglare layer was provided for measurement. In this state, light was incident at 45° from the side of the anti-glare layer, and measurement was performed. Here, the measured value is a total value of four kinds of optical combs each having a width of a dark portion and a bright portion of 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively.

(reflection resolution measured at a light incident angle of 60°)

The reflection sharpness of the anti-glare film was measured by the image sharpness measuring device "ICM-1DP" manufactured by Suga Tester Co., Ltd. according to the method of JIS K 7105. At this time, in order to prevent the warpage of the sample, an optically transparent adhesive was used, and the surface of the measurement sample opposite to the antiglare layer was bonded to the black acrylic substrate, and then it was measured. In this state, light was incident at 60° from the side of the anti-glare layer, and measurement was performed. Here, the measured value is a total value of four kinds of optical combs each having a width of a dark portion and a bright portion of 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively.

[3] Evaluation of anti-glare performance of anti-glare film

(Reflex glare, visual assessment of whitening)

In order to prevent reflection from the back surface of the anti-glare film, the anti-glare film is bonded to the surface of the measurement sample which is opposite to the anti-glare layer and bonded to the black acrylic resin plate, and the fluorescent lamp is brightened. In the room, the degree of reflection glare and the degree of whitening of the fluorescent lamp were visually observed by visual observation from the side of the anti-glare layer. Regarding the reflected glare, the degree of the reflected glare when the antiglare film was viewed from the front side and the degree of the reflected glare when observed after the inclination of 30 ° were respectively evaluated. The reflected glare and whitening systems were evaluated in the following stages from 1 to 3, respectively.

Reflective glare:

1: No reflected glare was observed.

2: A little reflected glare was observed.

3: Reflected glare is clearly observed.

Albino:

1: No whitening was observed.

2: A little whitening was observed.

3: Clearly observed whitening.

(evaluation of glare)

Glare is evaluated in the following order. That is, first, a reticle having a pattern of unit cells as shown in plan view in Fig. 10 is prepared. In the figure, the unit cell 100 is formed on a transparent substrate, and a hook-shaped chrome-shielding pattern 101 is formed with a line width of 10 μm, and a portion where the chrome-shielding pattern 101 is not formed is the opening portion 102. Here, the size of the unit cell is 211 μm × 70 μm (length × width of the figure), and the size of the opening is 201 μm × 60 μm (length × width of the figure). The unit cells shown in the figure are arranged in a large number in the longitudinal direction to form a reticle.

Then, as shown in the schematic cross-sectional view of Fig. 11, the chrome-shielding pattern 111 of the mask 113 is placed above the light box 115, and the anti-glare film 110 is bonded to the surface of the anti-glare layer by using an adhesive. A sample formed on the glass plate 117 is placed on the mask 113. A light source 116 is disposed in the light box 115. In this state, the degree of glare was evaluated by a seven-stage function from the position 119 at a distance of about 30 cm from the sample. In Stage 1, the state of glare was not confirmed at all, the state of strong glare was observed in Stage 7, and the state of a little glare was observed in Stage 4.

(evaluation of comparison)

The polarizing plate on both sides of the front and back sides was peeled off from a commercially available liquid crystal television ["KY-32EX550" manufactured by SONY Co., Ltd.]. In place of the original polarizing plates, a polarizing plate "SUMIKALAN SRDB831E" manufactured by Sumitomo Chemical Co., Ltd. is attached to the back side and displayed by an adhesive so that the absorption axes thereof coincide with the absorption axes of the original polarizing plates. On the surface side, the antiglare film shown in each of the following examples was bonded to the display surface side polarizing plate with an uneven surface as a surface via an adhesive. The thus obtained liquid crystal television was started in a dark room, and the brightness in the black display state and the white display state was measured using a TOPCON (Brightness) brightness meter "BM5A" type, and the contrast was calculated. Here, the contrast is expressed by the ratio of the brightness of the white display state to the brightness of the black display state. As a result, the contrast measured in the state in which the anti-glare film was bonded was expressed as the ratio of the contrast measured in the state in which the anti-glare film was not attached.

[4] Evaluation of patterns used in the manufacture of anti-glare films

The created pattern data is used as two-level binary image data, and the hierarchy is represented by a two-dimensional discrete function g(x, y). The horizontal resolutions Δx and Δy of the discrete function g(x, y) are set to 2 μm together. The obtained two-dimensional function g(x, y) is subjected to discrete Fourier transform to obtain a two-dimensional function G(f _x , f _y ). The square of the absolute value of the two-dimensional function G(f _x ,f _y ) is calculated, and the two-dimensional function Γ(f _x ,f _y ) of the two-dimensional power spectrum is calculated, and one of the functions of the distance f from the origin is calculated. One-dimensional function Γ(f).

<Example 1>

(Production of mold for manufacturing anti-glare film)

A Ballard copper-plated person was prepared on the surface of an aluminum roll (JIS A6063) having a diameter of 300 mm. The Ballard copper plating system includes a copper plating layer/a thin silver plating layer/a surface copper plating layer, and the entire thickness of the plating layer is set to be about 200 μm. The copper plating surface is mirror-polished, and a photosensitive resin is applied onto the surface of the copper plating which has been polished, and dried to form a photosensitive resin film. Next, the pattern in which the pattern A shown in FIG. 12 is repeatedly arranged is exposed on the photosensitive resin film by laser light, and development is performed. This was carried out by using Laser Stream FX (manufactured by Think Laboratory) by exposure and development of laser light. As the photosensitive resin film, those containing a positive-type photosensitive resin are used. Here, the pattern A is produced by a plurality of Gaussian function type band pass filters having a pattern of random brightness distribution, the aperture ratio is 45%, and the spatial frequency of the one-dimensional power spectrum is 0.01 μm ^-1 (intensity Γ ( 0.01) 0.02μm spatial frequency intensity Γ (0.02) in a ratio of ^-1 Γ (0.02) / Γ (0.01 ) 0.13 based spatial frequency intensity 0.01μm Gamma] (0.01) of the spatial frequency ^{-1 -1} 0.1 m The ratio Γ(0.1)/Γ(0.01) of the strength Γ(0.1) is 11.94.

Then, etching treatment is performed with a copper (II) chloride solution. The amount of etching at this time was set to be 4.5 μm. The photosensitive resin film was removed from the roll after the etching treatment, and chrome-plated processing was performed to prepare a mold A. At this time, the chrome plating thickness was set to be 11 μm.

(production of anti-glare film)

The following components were prepared by dissolving in ethyl acetate at a solid concentration of 60%, and after curing, an ultraviolet curable resin composition A having a film exhibiting a refractive index of 1.53 was formed.

(Reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate)

Diphenyl (2,4,6-trimethoxybenzylidene)phosphine oxide 5 parts

The ultraviolet curable resin composition A was applied onto a triacetonitrile cellulose (TAC) film having a thickness of 60 μm so that the thickness of the dried coating layer was 5 μm, and it was set in a dryer set at 60 ° C. Dry for 3 minutes. The dried film was pressed against the molding surface (surface having the surface uneven shape) of the previously obtained mold A by using a rubber roller so that the dried coating layer became the mold side. In this state, light from a high-pressure mercury lamp having a strength of 20 mW/cm ² was irradiated to an amount of 200 mJ/cm ² from the TAC film side, and the coating layer was cured to produce an anti-glare film. Then, the obtained antiglare film was peeled off from the mold to prepare a transparent antiglare film A having an antiglare layer on the TAC film.

<Example 2>

A mold B was produced in the same manner as in the mold A of Example 1, except that the pattern in which the pattern B shown in Fig. 13 was repeatedly arranged was exposed to laser light on the photosensitive resin film, except that the mold A was replaced. An anti-glare film was produced in the same manner as in Example 1 except for the mold B. This anti-glare film is used as the anti-glare film B. Here, the pattern B is produced by a plurality of Gaussian function type band pass filters having a pattern having a random brightness distribution, and the aperture ratio is 50%, and the spatial frequency of the one-dimensional power spectrum is 0.01 μm ^-1 . 0.01) The ratio of the intensity Γ(0.02) in the spatial frequency 0.02μm ^-1 Γ(0.02)/Γ(0.01) is 0.12, the intensity Γ(0.01) in the spatial frequency 0.01μm ^-1 and the spatial frequency 0.1μm ^-1 The ratio Γ(0.1)/Γ(0.01) of the strength Γ(0.1) is 11.85.

<Example 3>

A mold C was produced in the same manner as in the mold A of Example 1, except that the pattern in which the pattern C shown in FIG. 14 was repeatedly arranged was exposed to laser light on the photosensitive resin film, except that the mold A was replaced. An anti-glare film was produced in the same manner as in Example 1 except for the mold C. This anti-glare film is used as the anti-glare film C. Here, the pattern C is produced by a plurality of Gaussian function type band pass filters having a pattern having a random brightness distribution, and the aperture ratio is 40%, and the spatial frequency of the one-dimensional power spectrum is 0.01 μm ^-1 . 0.01) 0.02μm spatial frequency intensity Γ (0.02) in a ratio of ^-1 Γ (0.02) / Γ (0.01 ) 0.11 based spatial frequency intensity 0.01μm Gamma] (0.01) of the spatial frequency ^{-1 -1} 0.1 m The ratio Γ(0.1)/Γ(0.01) of the strength Γ(0.1) is 11.43.

<Comparative Example 1>

A mold D was produced in the same manner as in the mold A of Example 1, except that the pattern in which the pattern D shown in Fig. 15 was repeatedly arranged was exposed to laser light on the photosensitive resin film, except that the mold A was replaced. An anti-glare film was produced in the same manner as in Example 1 except for the mold D. This anti-glare film is used as the anti-glare film D. Here, the pattern D is produced by a plurality of Gaussian function type band pass filters having a pattern having a random brightness distribution, and the aperture ratio is 35%, and the spatial frequency of the one-dimensional power spectrum is 0.01 μm ^-1 . 0.01) 0.02μm spatial frequency intensity Γ (0.02) in a ratio of ^-1 Γ (0.02) / Γ (0.01 ) 0.13 based spatial frequency intensity 0.01μm Gamma] (0.01) of the spatial frequency ^{-1 -1} 0.1 m The ratio Γ(0.1)/Γ(0.01) of the strength Γ(0.1) is 11.40.

<Comparative Example 2>

A mold E was produced in the same manner as in the mold A of Example 1, except that the pattern in which the pattern E shown in FIG. 16 was repeatedly arranged was exposed to laser light on the photosensitive resin film, except that the mold A was replaced. An anti-glare film was produced in the same manner as in Example 1 except for the mold E. This anti-glare film was used as the anti-glare film E. Here, the pattern E is produced by a plurality of Gaussian function type band pass filters having a pattern of random brightness distribution, the aperture ratio is 45.0%, and the spatial frequency of the one-dimensional power spectrum is 0.01 μm ^-1 (intensity Γ ( 0.01) The ratio of the intensity Γ(0.02) in the spatial frequency 0.02μm ^-1 Γ(0.02)/Γ(0.01) is 2.69, the intensity in the spatial frequency 0.01μm ^-1 is Γ(0.01) and the spatial frequency is 0.1μm ^-1 The ratio Γ(0.1)/Γ(0.01) of the strength Γ(0.1) is 278.67.

<Comparative Example 3>

The surface of a 300 mm diameter aluminum roll (JIS A5056) was mirror-polished, and the zirconia beads TZ-SX-17 were placed on the ground aluminum surface using a blast apparatus (manufactured by Fujia Co., Ltd.). (TOSOH (manufactured by TOSOH), average particle diameter: 20 μm) at a spray pressure of 0.1 MPa (gauge pressure, hereinafter synonymous), and the amount of beads used was 8 g/cm ² (the amount used per 1 cm ² of the surface area of the roll, the following is synonymous) Blowing, causing irregularities on the surface of the aluminum roll. The obtained aluminum foil with irregularities was subjected to electroless nickel plating to prepare a mold F. At this time, the thickness of the electroless nickel plating was set to be 15 μm. An anti-glare film was produced in the same manner as in Example 1 except that the mold A was replaced with the mold F. This anti-glare film is used as the anti-glare film F.

<Comparative Example 4>

A Ballard copper-plated person was prepared on the surface of an aluminum roll (JIS A5056) having a diameter of 200 mm. Ballard copper plating includes a copper plating layer/thin silver plating layer/surface copper plating layer, and the entire thickness of the plating layer is about 200 μm. The copper-plated surface was mirror-polished, and the zirconia beads "TZ-SX-17" (TOSOH) was used for the polishing surface by using a blowing device (manufactured by Fujitsu Co., Ltd.). : 20 μm), blowing at a pressure of 0.05 MPa (gauge pressure, hereinafter synonymous), and a bead usage amount of 6 g/cm ^{2 to} cause irregularities on the surface of the aluminum roll. The obtained copper-plated aluminum roll with irregularities was subjected to chrome plating to prepare a mold G. At this time, the chrome plating thickness was set to be 6 μm. An anti-glare film was produced in the same manner as in Example 1 except that the mold A was replaced with the mold G. This anti-glare film is used as the anti-glare film G.

[evaluation result]

The results of the evaluation of the above antiglare film for the above examples and comparative examples are shown in Table 1.

The anti-glare films A to C (Examples 1 to 3) satisfying the requirements of the present invention have an excellent anti-glare property regardless of the front or the tilt even if the haze is low in haze, and the whitening and glare suppressing effects are sufficient. By. On the other hand, the anti-glare film D (Comparative Example 1) was whitened. The antiglare film E (Comparative Example 2) was insufficient in antiglare property when observed obliquely. The anti-glare film F (Comparative Example 3) is susceptible to glare. The anti-glare film G (Comparative Example 4) had insufficient anti-glare property when observed obliquely.

(industrial availability)

The anti-glare film of the present invention can be used for an image display device such as a liquid crystal display.

1‧‧‧Anti-glare film

2‧‧‧Small bumps

5‧‧‧Main normal direction

101‧‧‧ Transparent support

102‧‧‧Anti-glare layer

103‧‧‧Virtual plane

Claims (2)

An anti-glare film comprising a transparent support and an anti-glare layer having a fine surface concavo-convex shape formed thereon, wherein the anti-glare film has a full haze of 0.1% or more and 3% or less, and the surface haze system is 0.1% or more and 2% or less, the surface unevenness is such that the kurtosis Rku of the roughness curve is 4.9 or less, and the power spectrum of the elevation satisfies the following conditions (1) to (3): (1) The spatial frequency is 0.01 μm. ^-1 intensity I (0.01) is 2 μm ⁴ or more and 10 μm ⁴ or less; (2) spatial frequency 0.02 μm ^-1 intensity I (0.02) is 0.1 μm ⁴ or more and 1.5 μm ⁴ or less; and (3) space the frequency of 0.1μm ^-1 intensity I (0.1) based 0.0001μm ⁴ or more and 0.01μm ⁴ or less. The anti-glare film according to claim 1, wherein the penetration clarity measured by using five kinds of optical combs having a width of 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm in the dark portion and the bright portion is used. And the Tc is more than 375%, and the sum of the reflection resolutions measured by the light incident angle of 45° is used for the four types of optical combs having the width of the dark portion and the bright portion of 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm. The system is 180% or less, and the sum of the reflection resolutions measured by the four kinds of optical combs of the dark portion and the bright portion having the widths of 0.25 mm, 0.5 mm, 1.0 mm, and 2.0 mm and the light incident angle of 60° is Rc (60). 240% or less.