JP2012068473A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device exerting a superior antiglare property, expressing favorable contrast and wide viewing angle characteristics, and eliminating the lowering of visibility.SOLUTION: The liquid crystal display device includes a liquid crystal cell, a front-side polarizing film in the viewing side of the liquid crystal cell, a back-side polarizing film in the opposite side thereof, an optical anisotropic layer disposed between the back-side or front-side polarizing film and the liquid crystal cell, and an antiglare film 1 including a transparent support body and an antiglare layer formed on the transparent support body and having a fine rugged surface. The antiglare film is disposed to position the antiglare layer at a part closest to the viewing side. As for a plane wave with the wavelength of 550 nm that enters from a main normal direction, a complex amplitude on a highest elevation surface 21 is calculated from the elevation of the fine rugged surface and the refractive index of the antiglare layer and, when a primary power spectrum of the complex amplitude is expressed as an intensity to the spatial frequency, a graph includes two inflection points within a range of the spatial frequency of not less than 0.032 μmbut nor more than 0.064 μm.

Description

  The present invention relates to a liquid crystal display device having an antiglare (antiglare) film having excellent antiglare properties.

  Liquid crystal display devices are increasingly used for televisions, personal computers, portable terminals, and the like because of their features such as light weight, thinness, and low power consumption. In a liquid crystal display device used for the purpose of displaying an image such as a television, the visibility, particularly the contrast ratio when observed from the front and the contrast ratio when observed from an oblique direction, that is, viewing angle characteristics are regarded as important.

  Further, the visibility of the liquid crystal display device is significantly impaired when diplomacy is reflected on the display surface. To prevent the transfer of external light, TVs and personal computers that emphasize image quality, video cameras and digital cameras used outdoors with strong external light, mobile phones that display using reflected light, etc. In the conventional art, an antiglare film for preventing external light from being reflected on the surface of a liquid crystal display device has been used.

  Anti-glare films are required to have anti-glare properties, exhibit good contrast when placed on the surface of an image display device, and the entire display surface becomes whitish due to scattered light when placed on the surface of a liquid crystal display device. Inhibits the occurrence of so-called “whitening”, which causes the display to become cloudy, and the liquid crystal display pixels interfere with the uneven surface shape of the antiglare film when placed on the surface of the liquid crystal display device. However, as a result, it is desired to suppress the occurrence of a so-called “glare” phenomenon in which a luminance distribution is generated and is difficult to see.

  As liquid crystal display devices with improved contrast ratio, viewing angle characteristics, and antiglare properties, Patent Document 1 and Patent Document 2 disclose a twisted nematic liquid crystal display device with a predetermined optical anisotropic layer and an antiglare film. There is disclosed a liquid crystal display device in which a polarizing plate having s is arranged. More specifically, Patent Document 1 discloses a liquid crystal cell in which a twisted nematic liquid crystal is sandwiched between two electrode substrates, a linear polarizer, an optically negative or positive uniaxial optical axis of which is a film. A liquid crystal display device having improved visibility by applying an anti-glare layer divided into a predetermined domain area together with an optically anisotropic layer inclined by 5 to 50 ° from the normal direction of . Patent Document 2 discloses a liquid crystal cell in which a twisted nematic liquid crystal is sandwiched between two electrode substrates, a linear polarizer, optically negative or positive uniaxial, and its optical axis is the normal direction of the film. Disclosed is a liquid crystal display device with improved visibility by disposing an anti-glare layer that gives specific optical characteristics and has a specific surface shape together with an optically anisotropic layer tilted 5 to 50 ° from Yes.

  However, since the antiglare films described in Patent Documents 1 and 2 are produced using an emboss mold in which a concavo-convex shape is formed by blasting, the accuracy of the concavo-convex shape is not sufficient, and in particular, has a period of 50 μm or more. Since it may have a relatively large uneven shape, there is a problem that “glare” tends to occur.

JP 2006-053511 A JP 2007-256765 A

  An object of the present invention is to provide a liquid crystal display device that exhibits excellent anti-glare properties, exhibits good contrast and wide viewing angle characteristics, and does not cause a decrease in visibility due to the occurrence of “blink” or “glare”. It is to provide.

The present invention includes a liquid crystal cell in which a twisted nematic liquid crystal is sealed between a pair of parallel cell substrates,
A front-side polarizing film disposed on the viewing side of the liquid crystal cell;
A back side polarizing film disposed on the opposite side;
An optically anisotropic layer disposed between at least one of the back side polarizing film and the liquid crystal cell and between the front side polarizing film and the liquid crystal cell;
An antiglare film comprising a transparent support, and an antiglare layer formed on the transparent support and having a fine uneven surface having fine unevenness on the opposite side of the transparent support;
Furthermore, the antiglare film is a liquid crystal display device arranged so that the antiglare layer is on the most visible side on the side opposite to the surface facing the liquid crystal cell of the front side polarizing film,
The antiglare film has an internal haze of 1% or less, a surface haze of 0.4% or more and 10% or less, and an average surface obtained from an average when the altitude of the fine uneven surface is measured. Highest elevation that is incident from a main normal direction perpendicular to the average surface of the fine uneven surface, includes a point having the highest elevation among the fine uneven surface, and is a virtual plane parallel to the average surface of the fine uneven surface For a plane wave with a wavelength of 550 nm emitted from the surface, the complex amplitude at the highest altitude surface is calculated from the altitude of the fine uneven surface and the refractive index of the antiglare layer, and the one-dimensional power spectrum of the complex amplitude is expressed as an intensity with respect to the spatial frequency. And a graph having two inflection points within a spatial frequency range of 0.032 μm ^{−1 to} 0.064 μm ⁻¹ .

  The optically anisotropic layer is preferably disposed between the back side polarizing film and the liquid crystal cell and between the front side polarizing film and the liquid crystal cell.

  The optically anisotropic layer is preferably optically negative or positive uniaxial, and its optical axis is inclined by 5 to 50 ° from the normal direction of the film.

It is preferable that the second derivative with respect to the spatial frequency of the one-dimensional power spectrum of the complex amplitude is positive at the spatial frequency of 0.024 μm ⁻¹ .

  It is preferable that the ratio of the minute surfaces having an inclination angle of 5 ° or more in the fine uneven surface is less than 10%.

  The liquid crystal display device of the present invention exhibits excellent contrast and wide viewing angle characteristics while exhibiting excellent anti-glare properties, and prevents deterioration in visibility due to the occurrence of “blink” and “glare”. Become.

It is a perspective view which shows typically the surface of the glare-proof film used for this invention. It is a schematic diagram which shows the relationship between the altitude h (x, y) of a fine uneven | corrugated surface, an altitude reference surface, and the highest altitude surface. It is a schematic diagram which shows the state from which the function h (x, y) showing an altitude is obtained discretely. It is the figure which represented the altitude of the fine uneven | corrugated surface of an anti-glare film with the two-dimensional discrete function h (x, y). Two-dimensional power spectrum ^{_{Ψ 2 (f x, f y}} ) is a schematic view for explaining a method of averaging the distance f from the origin in the frequency space. FIG. 4 is a diagram illustrating a one-dimensional power spectrum Ψ ² (f) obtained by performing a discrete Fourier transform on a complex amplitude calculated from the two-dimensional function h (x, y) illustrated in FIG. 3. It is a schematic diagram which shows the state which linearly interpolates the one-dimensional power spectrum (PSI) ² (f) of a complex amplitude. One dimensional power spectrum [psi ² of the complex amplitude of the (f) by linear interpolation of FIG. 6 is a diagram showing the resulting one-dimensional power spectra [psi ² (f) as a discrete function for each 0.008 .mu.m ^-1. FIG. 9 is a diagram illustrating a second derivative d ² Ψ ² (f) / df ² of the one-dimensional power spectrum Ψ ² (f) of the complex amplitude in FIG. 8. It is a figure showing the relationship between the intensity | strength of the one-dimensional power spectrum (PSI) ² (f) of spatial frequency 0.03 micrometer < ^-1 >, and reflection sharpness. It is a top view which shows the unit cell of the pattern for glare evaluation. It is a cross-sectional schematic diagram which shows the state of glare evaluation. It is a figure showing the relationship between the intensity | strength of the one-dimensional power spectrum (PSI) ² (f) of spatial frequency 0.02 micrometer- ¹ , and the evaluation result of glare. It is a schematic diagram for demonstrating the measuring method of the inclination-angle of the fine uneven | corrugated surface. It is a graph which shows an example of the histogram of the inclination angle distribution of the micro surface of the fine uneven surface of an anti-glare film. It is a figure which shows typically the image data which is the pattern used in order to produce an anti-glare film. FIG. 17 is a diagram showing a power spectrum G ² (f) obtained by subjecting the pattern shown in FIG. 16 to discrete Fourier transform. It is a figure which shows typically a preferable example of the first half part of the manufacturing method of the metal mold | die used preferably for manufacture of an anti-glare film. It is a figure which shows typically a preferable example of the second half part of the manufacturing method of the metal mold | die preferably used for manufacture of an anti-glare film. It illustrates an embodiment 1 and the secondary Kaishirube one-dimensional power spectrum of the complex amplitudes calculated from the elevation of the antiglare film A and B used in Comparative Example 1 function ^{d 2 Ψ 2 (f) /} df 2. It is a cross-sectional schematic diagram which shows an example of the liquid crystal display device of this invention. It is a cross-sectional schematic diagram which shows another example of the liquid crystal display device of this invention. It is a cross-sectional schematic diagram which shows another example of the liquid crystal display device of this invention.

<Liquid crystal display device>
The liquid crystal display device of the present invention includes a liquid crystal cell in which a twisted nematic liquid crystal is sealed between a pair of cell substrates parallel to each other,
A front-side polarizing film disposed on the viewing side of the liquid crystal cell;
A back side polarizing film disposed on the opposite side;
An optically anisotropic layer disposed between at least one of the back side polarizing film and the liquid crystal cell and between the front side polarizing film and the liquid crystal cell;
An antiglare film comprising a transparent support, and an antiglare layer formed on the transparent support and having a fine uneven surface having fine unevenness on the opposite side of the transparent support;
Further, the antiglare film is disposed on the side opposite to the surface facing the liquid crystal cell of the front side polarizing film so that the antiglare layer is on the most visible side.

  Specific examples of the liquid crystal display device of the present invention are shown in FIGS. The liquid crystal display device shown in FIG. 21 to FIG. 23 is disposed between the liquid crystal cell 110, a pair of polarizing films 120 and 121 disposed therebetween, and one or both of the polarizing films and the liquid crystal cell 110. Optically anisotropic layers 130 and 131.

  The liquid crystal cell 110 includes two cell substrates 111 and 112 that are parallel to each other and a liquid crystal layer 115 in which liquid crystal is sealed (sandwiched) between them. Electrodes 113 and 114 are provided. The liquid crystal in the liquid crystal layer 115 of the liquid crystal cell 110 is a so-called twisted nematic liquid crystal.

  In the liquid crystal display device shown in FIG. 21, a first optical anisotropic layer 130 is disposed between the cell substrate 111 and the polarizing film 120. A second optical anisotropic layer 131 is disposed between the cell substrate 112 on the opposite side of the first optical anisotropic layer 130 and the polarizing film 121.

  Furthermore, in the liquid crystal display device shown in FIG. 21, given optical characteristics are given to the surface opposite to the side facing the liquid crystal cell 110 of one polarizing film 120, that is, the surface on the display surface (viewing) side, An antiglare film 1 having a predetermined surface shape is disposed. The antiglare film 1 includes a transparent support 101 and an antiglare layer 100 having a fine uneven surface formed on the transparent support and having fine unevenness on the side opposite to the transparent support. The antiglare film 1 is disposed on the side opposite to the surface facing the liquid crystal cell 110 of the front side polarizing film 120 so that the antiglare layer 100 is on the most visible side. The liquid crystal display device of the present invention is characterized by the shape of the fine uneven surface of the antiglare film 1. The antiglare film 1 will be described in detail later.

(Twisted nematic liquid crystal)
The twisted nematic (hereinafter abbreviated as “TN”) type liquid crystal used in the liquid crystal display device of the present invention changes the alignment state of liquid crystal molecules by a vertical electric field that applies a voltage perpendicular to the substrate surface. In the TN mode, when the liquid crystal molecules are traced from one substrate to the other, the liquid crystal alignment in a state in which no voltage is applied is twisted 90 degrees between the upper and lower substrates while facing in a plane parallel to the substrate in each portion. It is oriented parallel to the substrate surface so as to be in a (twisted) state.

  In the conventional TN type liquid crystal display device, the viewing angle characteristics are not sufficient due to the anisotropy of the refractive index caused by the pretilt of the liquid crystal substance in the liquid crystal cell. Japanese Patent Laid-Open No. Hei 6-214116 discloses an optically anisotropic layer which exhibits negative uniaxiality and whose optical axis is inclined with respect to the film surface, in a TN liquid crystal display device. Disposing between the liquid crystal cell and the polarizing plate is disclosed. Japanese Patent Application Laid-Open No. 10-186356 discloses an optical compensation film in which a nematic hybrid alignment formed by a liquid crystalline polymer exhibiting positive uniaxiality in a liquid crystal state is fixed. It is also disclosed that the viewing angle is expanded by applying to a TN type liquid crystal display device. By using such an optically anisotropic layer having an optical axis oblique to the film surface as an optical compensation film (retardation plate), the viewing angle in a TN liquid crystal display device is improved.

(Optically anisotropic layer)
In the present invention, the optically anisotropic layer may be disposed between at least one of the back side polarizing film and the liquid crystal cell and between the front side polarizing film and the liquid crystal cell. It is preferable to arrange between the side polarizing film and the liquid crystal cell and between the front side polarizing film and the liquid crystal cell.

  As an optically anisotropic layer, an optically anisotropic uniaxial optically anisotropic layer whose optical axis is inclined 5 to 50 ° from the normal direction of the film, or an optically positive uniaxially layered optically anisotropic layer. An optically anisotropic layer whose optical axis is inclined by 5 to 50 ° from the normal direction of the film is preferable.

  As an optically anisotropic layer that is optically negative uniaxial and whose optical axis is inclined 5 to 50 ° from the normal direction of the film, for example, as described in JP-A-6-214116 Organic compounds, particularly those having liquid crystallinity and having a discotic molecular structure, and compounds that do not exhibit liquid crystallinity but develop negative refractive index anisotropy by electric or magnetic fields are derived from triacetylcellulose and the like. The film etc. which are apply | coated on the transparent resin film which become and are orientated so that an optical axis may incline between 5-50 degrees from a film normal line direction etc. are used preferably. The orientation may be not only one direction but also, for example, a so-called hybrid orientation in which the inclination gradually increases from one side of the film to the other side.

  Examples of organic compounds having a discotic molecular structure exhibiting liquid crystallinity include low molecular or high molecular discotic liquid crystals, such as alkyl groups, alkoxy groups, alkyls, etc., on a mother nucleus having a planar structure such as triphenylene, torquesen, and benzene. Examples include those in which linear substituents such as substituted benzoyloxy groups and alkoxy-substituted benzoyloxy groups are bonded in a radial manner. Among them, those that do not absorb in the visible light region are preferable.

  As for the organic compound having a discotic molecular structure, not only one kind is used alone, but also other organic compounds such as a polymer matrix may be used in combination with plural kinds as necessary in order to obtain a desired orientation. Can be used as a mixture. The organic compound used as a mixture is compatible with an organic compound having a discotic molecular structure or can disperse an organic compound having a discotic molecular structure in a particle size that does not scatter light. If it does not specifically limit. For example, a WV film (Fuji Photo Film Co., Ltd.) can be used as a film in which a layer made of a liquid crystal compound is provided on a transparent base film made of a cellulose resin and the optical axis is inclined with respect to the film normal. Can be suitably used.

  An optically anisotropic layer that is optically positive uniaxial and whose optical axis is inclined by 5 to 50 ° from the normal direction of the film is described in, for example, JP-A-10-186356. Organic compounds having an elongated rod-like structure, especially those having a nematic liquid crystal property and a molecular structure that gives positive optical anisotropy, and those having no liquid crystallinity but having a positive refractive index difference due to an electric or magnetic field. Examples include a film in which a compound exhibiting anisotropy is formed on a transparent substrate film made of a cellulose-based resin and the like, and the optical axis is oriented so as to be inclined at 5 to 50 ° from the film normal direction. . The orientation may be not only one direction but also, for example, a so-called hybrid orientation in which the inclination gradually increases from one side of the film to the other side. As a film in which a layer made of a nematic liquid crystal compound is provided on a transparent substrate film and the optical axis is inclined with respect to the film normal, for example, an NH film (manufactured by Nippon Oil Corporation) is preferably used. Can do.

Moreover, a thin film can be formed by vacuum deposition, and a dielectric that exhibits positive refractive index anisotropy when deposited is deposited on a transparent substrate film from a direction inclined with respect to the normal line. By doing so, it is also possible to obtain an optically anisotropic layer that is optically positive uniaxial and whose optical axis is inclined 5 to 50 ° from the normal direction of the film. The dielectric used for this purpose may be either a dielectric made of an inorganic compound or a dielectric made of an organic compound, but an inorganic dielectric is preferably used from the viewpoint of stability against heat acting during vacuum deposition. Examples of the inorganic dielectric include tantalum oxide (Ta ₂ O ₅ ), tungsten oxide (WO ₃ ), silicon dioxide (SiO ₂ ), silicon monoxide (SiO), bismuth oxide (Bi ₂ O ₅ ), neodymium oxide (Nd ₂ ). A metal oxide such as O ₃ ) is preferably used in terms of excellent transparency. Among metal oxides, those having a refractive index anisotropy and a hard film quality such as tantalum oxide, tungsten oxide, and bismuth oxide are more preferably used.

  When using an optically anisotropic layer in which a dielectric layer exhibiting refractive index anisotropy is laminated on such a transparent substrate film, the optically anisotropic layer has a polarizing film on the transparent substrate film side. Or it laminates | stacks on a polarizing film or a transparent protective film so that the transparent protective film bonded to this may be opposed.

  In the TN mode, in order to further improve the viewing angle characteristics and the display characteristics, it is preferable to dispose an optically anisotropic layer also on the back side polarizing plate that forms a pair with the liquid crystal cell interposed therebetween. As described above, the optically anisotropic layer 131 provided between the back side polarizing film 121 and the cell substrate 112 is optically negative or positive uniaxial, and its optical axis is the normal direction of the film. An optically anisotropic layer inclined at 5 to 50 ° from the angle can be preferably used.

(Polarizing film)
The front-side polarizing film 120 and the back-side polarizing film 121 are generally of the type that transmits linearly polarized light that vibrates in one direction orthogonal to each other in the film plane and absorbs linearly polarized light that vibrates in the other direction. What is known as a board may be sufficient. Specifically, a polyvinyl alcohol film that has been uniaxially stretched and dyed with a high dichroic dye and further subjected to boric acid crosslinking can be used. There are iodine-based polarizers using iodine as the high-dichroic dye and dye-based polarizers using dichroic organic dyes as the high-dichroic dye, both of which can be used. Further, such a polyvinyl alcohol polarizing film itself may be used, or a triacetyl cellulose (TAC) film, an acrylic resin film, a polyethylene terephthalate film, an unstretched norbornene is provided on one or both surfaces of the polyvinyl alcohol polarizing film. A polarizing plate on which a transparent protective film such as a film is laminated may be used.

  In the liquid crystal display device shown in FIG. 21, the antiglare film 1 including the transparent support 101 and the antiglare layer 100 is laminated on the front side of the first polarizing film 120, and on the back side of the second polarizing film 121. A transparent protective film 102 is laminated.

  In the liquid crystal display device shown in FIG. 22, the antiglare film 1 and the transparent protective film 103 including the transparent support 101 and the antiglare layer 100 are laminated on the front side and the back side of the first polarizing film 120, A transparent protective film 102 is laminated on the back side of the second polarizing film 121.

  In the liquid crystal display device shown in FIG. 23, the antiglare film 1 including the transparent support 101 and the antiglare layer 100 is laminated on the front surface side of the first polarizing film 120, and the front surface of the second polarizing film 121. Transparent protective films 104 and 102 are laminated on the side and the back side.

  In the liquid crystal display device shown in FIG. 22, the transparent protective film 103 can be omitted by providing the first retardation film 130 with the role of the transparent protective film 103.

  In the liquid crystal display device shown in FIGS. 21 to 23, the transparent protective film 102 is disposed on the back side of the back side polarizing film 121. As shown in FIG. 21 and FIG. 22, when the optically anisotropic layer 131 is arranged on one side, the optically anisotropic layer 131 has a role of a transparent protective film for protecting the polarizing film 121. Can do. Even in this case, it is preferable to provide the transparent protective film as described above on the other surface of the polarizing film 121.

  A backlight (not shown) for supplying light to the liquid crystal cell 110 is usually provided on the back side of the back side polarizing film 121 (the back side of the transparent film 103).

<Anti-glare film>
Hereinafter, the antiglare film 1 described above will be described in detail.

  The antiglare film used in the present invention includes an antiglare layer comprising a transparent support and a fine uneven surface formed on the transparent support and having fine unevenness on the side opposite to the transparent support. The film has an internal haze of 1% or less and a surface haze of 0.4% or more and 10% or less.

Furthermore, the anti-glare film is irradiated from the main normal direction perpendicular to the average surface of the fine uneven surface (the average surface obtained from the average when the elevation of the fine uneven surface is measured), and is incident from the transparent support side. And about the plane wave of wavelength 550nm emitted from the glare-proof layer side,
The complex amplitude at the highest elevation surface, which includes a point with the highest elevation among the fine irregular surface, and is a virtual plane parallel to the average surface of the fine irregular surface, the elevation of the fine irregular surface and the refraction of the antiglare layer Calculated from the rate,
The graph when the one-dimensional power spectrum of the complex amplitude is expressed as the intensity with respect to the spatial frequency has two inflection points in the spatial frequency range of 0.032 μm ^{−1 to} 0.064 μm ^−1. And

  So far, regarding the period of the fine uneven surface of the antiglare film, the average length RSm of the roughness curve element described in JIS B 0601, the average length PSm of the cross-section curve element, the average length WSm of the undulation curve element, etc. It was evaluated by. However, such a conventional evaluation method cannot accurately evaluate a plurality of periods included in the fine uneven surface. Therefore, the correlation between the glare and the fine uneven surface and the correlation between the anti-glare property and the fine uneven surface cannot be accurately evaluated, and an anti-glare film having both suppression of glare and sufficient anti-glare performance is produced. It was difficult.

  In the antiglare film comprising a transparent support and an antiglare layer having a fine uneven surface formed on the transparent support and having fine unevenness on the side opposite to the transparent support, If the complex amplitude of the plane wave at the highest altitude surface calculated from the altitude and the refractive index of the antiglare layer shows a specific spatial frequency distribution, the glare is sufficiently prevented while exhibiting a sufficient antiglare effect. I found out that That is, according to the present invention, the shape of the fine uneven surface of the antiglare film disposed on the surface of the liquid crystal display device is such that the inflection point of the one-dimensional power spectrum of the complex amplitude is located within a specific range. As a result, it is possible to provide a liquid crystal display device that exhibits excellent anti-glare performance, prevents deterioration in visibility due to whitishness, and exhibits high contrast and wide viewing angle characteristics without causing glare.

  First, the elevation of the fine uneven surface of the antiglare film (antiglare layer) will be described. FIG. 1 is a perspective view schematically showing the surface of an antiglare film. As shown in FIG. 1, the antiglare film 1 includes an antiglare layer having a fine uneven surface on which fine unevenness 2 is formed.

  The “elevation on the surface of the fine unevenness” as used in the present invention is an average of the surface of the fine unevenness including an arbitrary point P on the surface of the antiglare film 1 and a point having the lowest elevation when measuring the elevation of the surface of the fine unevenness. The main normal direction (fine) between an elevation reference plane (elevation is 0 μm as a reference) that is a virtual plane parallel to the plane (average plane obtained from the average when measuring the elevation of the fine uneven surface) It means a linear distance in a direction perpendicular to the average surface of the uneven surface. As shown in FIG. 1, when the orthogonal coordinates in the average plane of the fine uneven surface are represented by (x, y), the altitude of the fine uneven surface at the coordinates (x, y) is set to h (x, y). In FIG. 1, the projection surface 3 which is the plane which projected the surface of the anti-glare film 1 whole is displayed.

The elevation of the surface of the fine irregularities can be obtained from three-dimensional information of the surface shape measured by an apparatus such as a confocal microscope, an interference microscope, an atomic force microscope (AFM). The horizontal resolution required for the measuring instrument 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. Non-contact three-dimensional surface shape / roughness measuring instruments suitable for this measurement include New View 5000 series (manufactured by Zygo Corporation, available from Zygo Corporation in Japan), three-dimensional microscope PLμ2300 (manufactured by Sensofar), etc. Can be mentioned. The measurement area needs to be at least 125 μm × 125 μm or more, more preferably 500 μm × 500 μm or more, because the resolution of the complex amplitude two-dimensional power spectrum needs to be 0.008 μm ⁻¹ or less.

FIG. 2 shows an elevation h (x, y) of the fine irregular surface and an elevation reference surface 20 (virtual parallel to the average surface of the fine irregular surface including the point having the lowest elevation when the elevation of the fine irregular surface is measured. 2) and the highest altitude surface 21 (a virtual plane that includes a point having the highest altitude among the fine uneven surfaces and is parallel to the average surface of the fine uneven surfaces). Here, the altitude of the highest altitude surface 21 is h _max (μm).

  The optical path length d (x, y) between the elevation reference plane 20 and the highest elevation plane 21 at the coordinates (x, y) is expressed by the equation (1) using a two-dimensional function h (x, y) related to elevation. I can do it.

Here, n _AG is the refractive index of the antiglare layer, and n _air is the refractive index of air. If the refractive index n _air of _air is approximated by 1, Equation (1) can be expressed by Equation (2).

  Next, a plane wave having a single wavelength λ is irradiated from the main normal direction 5 of the film (direction perpendicular to the average surface of the fine uneven surface) and incident from the transparent support side (elevation reference plane 20 side). The complex amplitude of the plane wave when emitted to the layer side (the highest elevation surface 21 side) will be described. The complex amplitude is a portion that does not include a time element when the amplitude of the wave is displayed in a complex manner. In general, the amplitude of a plane wave having a single wavelength λ can be complexly expressed by the following equation (3).

Where A is the maximum amplitude of the plane wave, π is the circularity ratio, i is the imaginary unit, z is the coordinate (optical path length from the origin) in the z-axis direction (main normal direction 5), ω is the angular frequency, and t is the time. , Φ ₀ is the initial phase.

  In Equation (3), the time-independent term is the complex amplitude. Therefore, the complex amplitude ψ (x, y) at the coordinates (x, y) of the highest elevation surface 21 for the plane wave represented by Expression (3) is the same as z in the term that does not depend on time in Expression (3). It can be expressed by the following formula (4) in which the optical path length d (x, y) is substituted.

Further, in the equation (4), the maximum amplitude A of the plane wave and the initial transfer φ ₀ do not depend on the coordinates (x, y), and try to define the distribution of the shape of the fine uneven surface at the coordinates (x, y). Since it is a constant in the present invention, A = 1 and φ ₀ = 0 in the following. When the above equation (2) is substituted, the complex amplitude ψ (x, y) can be expressed by the following equation (5). In the present invention, λ = 550 nm is used as a reference.

Next, a method for obtaining the power spectrum of the complex amplitude will be described. First, two-dimensional function [psi (x, y) represented by the formula (5) from the two-dimensional function [psi (f _x, f _y) by a two-dimensional Fourier transform defined by equation (6) is obtained.

Where f _x and f _y are the x and y directions of spatial frequencies, respectively, with the dimension of reciprocal length. The resulting two-dimensional function Ψ (f _x, f _y) by squaring the two-dimensional power spectrum of the complex amplitude ^{_{Ψ 2 (f x, f y}} ) can be obtained. The two-dimensional power spectrum ^{_{Ψ 2 (f x, f y}} ) represents the spatial frequency distribution of the complex amplitude is calculated from the elevation of the fine uneven surface of the antiglare film.

  Hereinafter, a method for obtaining a two-dimensional power spectrum having a complex amplitude calculated from the altitude of the fine uneven surface of the antiglare film will be described more specifically. The three-dimensional information of the surface shape actually measured by the above confocal microscope, interference microscope, atomic force microscope or the like is generally obtained as discrete values, that is, elevations corresponding to a large number of measurement points. FIG. 3 is a schematic diagram showing a state in which the function h (x, y) representing the altitude is obtained discretely. As shown in FIG. 3, the orthogonal coordinates in the film plane are displayed as (x, y), and the line divided on the film projection plane 3 by Δx in the x-axis direction and the line divided by Δy in the y-axis direction. Is indicated by a broken line, the actual elevation of the surface of the fine irregularities is obtained as a discrete elevation value at each intersection of the broken lines on the film projection surface 3.

  The number of elevation values obtained 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 = (M−1) Δx, and the measurement range in the y-axis direction is Y = (N -1) Assuming Δy, the number of obtained elevation values is M × N.

  As shown in FIG. 3, the coordinates of the point of interest A on the film projection surface 3 are (jΔx, kΔy) (where j is 0 or more and M−1 or less, and k is 0 or more and N−1 or less). Then, the altitude of the point P on the film surface corresponding to the point of interest A can be expressed as h (jΔx, kΔy).

  Here, the measurement intervals Δx and Δy depend on the horizontal resolution of the measuring device, and in order to accurately evaluate the fine uneven surface, both Δx and Δy are preferably 5 μm or less, as described above, and preferably 2 μm or less. Is more preferable. Further, as described above, the measurement ranges X and Y are both preferably 125 μm or more, and more preferably 500 μm or more.

As described above, in actual measurement, the function representing the altitude of the fine uneven surface is obtained as a discrete function h (x, y) having M × N values. From the discrete function h (x, y) obtained by the measurement, the complex amplitude ψ (x, y) represented by the equation (5) is obtained, and this complex amplitude ψ (x, y) is defined by the equation (7). discrete function Ψ (f _x, f _y) by a discrete Fourier transform that is Motomari, discrete function Ψ (f _x, f _y) discrete function of the two-dimensional power spectrum by squaring the ^{_{Ψ 2 (f x, f y}} ) is Desired. In formula (7), l is an integer of −M / 2 or more and M / 2 or less, and m is an integer of −N / 2 or more and N / 2 or less. Also, Delta] f _x and Delta] f _y are frequency intervals of the x and y directions, is defined by equation (8) and (9).

Here, as shown in FIG. 4, since the fine uneven surface of the antiglare film irregularities are formed at random, two-dimensional power spectrum in the frequency space (the spatial frequency _{^{domain) Ψ 2 (f x, f}} y ) Is symmetric about the origin (f _x = 0, f _y = 0). Therefore, two-dimensional function ^{_{Ψ 2 (f x, f y}} ) , the distance f (unit: [mu] m ^-1) from the origin in the frequency space can be converted to one-dimensional function [psi ² (f) to the variable. The antiglare film has a characteristic that the one-dimensional power spectrum obtained from the one-dimensional function Ψ ² (f) is constant.

Specifically, first, in the frequency space, as shown in FIG. 5, from the origin _{O (f x = 0, f} y = 0) (n-1/2) Δf least (n + 1/2) at a distance of less than Delta] f The number N _n of all the positions (black dots in FIG. 5) is calculated. In the example shown in FIG. 5, N _n = 16. Then, from the origin O (n-1/2) Δf least (n + 1/2) all the points of the ^{_{Ψ 2 (f x, f y}} ) located at a distance of less than Delta] f sum [psi ² _n (in FIG. 5 in Ψ ² (total value of f _x , f _y ) at the black circle points of _γ ² ) is calculated, and Ψ ² is obtained by dividing the total value Ψ ² _n by the number of points N _n as shown in the equation (10). The value of (f) was used.

Here, when M ≧ N, n is an integer of 0 or more and N / 2 or less, and when M <N, n is an integer of 0 or more and M / 2 or less. M and N mean the number of measurement points in the X-axis direction and the number of measurement points in the Y-axis direction, respectively, as shown in FIG. Δf was set to (Δf _x + Δf _y ) / 2.

FIG. 6 shows the one-dimensional power spectrum Ψ ² (f) of the complex amplitude thus obtained. The one-dimensional power spectrum shown in FIG. 6 includes noise, and in order to eliminate the influence of this noise when obtaining the inflection point of the one-dimensional power spectrum, a linear function is used to obtain a discrete function every 0.008 μm ^−1. Convert and reduce noise. FIG. 7 shows a state in which the one-dimensional power spectrum Ψ ² (f) is converted into a discrete function every 0.008 μm ⁻¹ by linear interpolation. In the example of FIG. 7, the value of the spatial frequency 0.016Myuemu ^-1 are linearly interpolated, in 0.0153Myuemu ^-1 is the largest spatial frequency in the spatial frequency 0.016Myuemu ^-1 smaller spatial frequency [psi ² From the value 17.7915 of (f) and the value 16.15881 of Ψ ² (f) of 0.0164 μm ⁻¹ which is the smallest spatial frequency among the spatial frequencies greater than 0.016 μm ⁻¹ , the spatial frequency 0 The value 16.8135 of .016 μm ⁻¹ is calculated. FIG. 8 shows the result of converting the one-dimensional power spectrum Ψ ² (f) of FIG. 6 into a discrete function for each spatial frequency of 0.008 μm ⁻¹ . It can be seen that the one-dimensional power spectrum Ψ ² (f) converted into a discrete function for each spatial frequency of 0.008 μm ⁻¹ has less noise.

The inflection point of the complex amplitude one-dimensional power spectrum Ψ ² (f) is calculated from the second derivative of the one-dimensional power spectrum Ψ ² (f) converted into a discrete function for each spatial frequency of 0.008 μm ^−1. I can do it. Specifically, the second derivative can be calculated by the difference method of Equation (11).

FIG. 9 shows the second derivative of the one-dimensional power spectrum Ψ ² (f) of FIG. As is clear from FIG. 9, the second-order derivative d ² Ψ ² (f) / df ² is twice in the horizontal axis (d ² Ψ ² (f) at a spatial frequency of 0.032 μm ^{−1 to} 0.064 μm ^−1. / Df ² = 0), and has one inflection point from the positive side to the negative side on the lower side of the spatial frequency within the spatial frequency range of 0.032 μm ^{−1 to} 0.064 μm ^−1. It is clear that it has one inflection point from negative to positive on the higher spatial frequency side. The “inflection point” in the graph when the one-dimensional power spectrum of the complex amplitude is expressed as the intensity with respect to the spatial frequency has the same meaning as the general term, but the one of the one-dimensional power spectrum Ψ ² (f) This is a point on the graph of the one-dimensional power spectrum Ψ ² (f) corresponding to the spatial frequency at which the second-order derivative d ² Ψ ² (f) / df ² is zero.

In the antiglare film, the second derivative d ² Ψ ² (f) / df ² of the complex amplitude one-dimensional power spectrum is a space in order to effectively prevent glare and obtain a sufficient antiglare effect. It is preferably positive at a frequency of 0.024 μm ⁻¹ . That is, it is preferable that the one-dimensional power spectrum of the complex amplitude has a downward convex shape at a spatial frequency of 0.024 μm ⁻¹ .

  Next, the relationship between the one-dimensional power spectrum of the complex amplitude calculated from the altitude of the fine uneven surface and the refractive index of the antiglare layer, the antiglare effect and the glare of the antiglare film will be described.

(Evaluation of anti-glare effect)
The antiglare effect of the antiglare film can be evaluated by the reflection definition measured according to the method defined in JIS K 7105. In this standard, the reflection definition uses four types of optical combs in which the ratio of the width of the dark portion to the bright portion is 1: 1 and the width is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. Thus, it is defined as the sum of image sharpness (unit:%) measured at a light incident angle of 45 °. However, when an optical comb having a width of 0.125 mm is used, in the antiglare film defined in the present invention, the measurement error of the image sharpness becomes large. When the 125 mm optical comb is used, image sharpness is not added, and the sum of image sharpness measured using three types of optical combs having widths of 0.5 mm, 1.0 mm, and 2.0 mm. It will be called reflection sharpness. Therefore, the maximum value of the reflection definition defined in this way is 300%. It shows that the anti-glare effect of an anti-glare film is so high that this reflection definition is small.

About the anti-glare film having various fine uneven surfaces, the intensity of the one-dimensional power spectrum Ψ ² (f) of complex amplitude for each spatial frequency in the range of spatial frequency 0.0024 to 0.3 μm ⁻¹ , and the reflection sharpness The correlation was analyzed. As a result, it was found that, by increasing the intensity of Ψ ² (f) at a spatial frequency of 0.03 μm ⁻¹ , the reflection sharpness is effectively reduced and the antiglare effect is enhanced. FIG. 10 shows the relationship between the intensity of Ψ ² (f) and the reflection definition at a spatial frequency of 0.03 μm ⁻¹ . From this, it was found that in order to enhance the antiglare effect of the antiglare film, it is necessary to increase the intensity of the complex amplitude one-dimensional power spectrum Ψ ² (f) at a spatial frequency of 0.03 μm ⁻¹ .

(Evaluation of glare)
On the other hand, the glare of the antiglare film was evaluated by the following method. That is, first, a photomask having a unit cell pattern as shown in a plan view in FIG. 11 was prepared. In this figure, a unit cell 40 has a key-shaped chrome light shielding pattern 41 with a line width of 10 μm formed on a transparent substrate, and a portion where the chrome light shielding pattern 41 is not formed is an opening 42. Here, a unit cell having a size of 211 μm × 70 μm (vertical × horizontal in the figure) and an opening having a dimension of 201 μm × 60 μm (vertical × horizontal in the figure) was used. A large number of unit cells shown in the figure are arranged vertically and horizontally to form a photomask.

  Then, as shown in a schematic cross-sectional view in FIG. 12, the chrome light-shielding pattern 41 of the photomask 43 is placed on the diffusion plate 50 on the light box 45, and the glass plate 47 is antiglare with an adhesive. A sample on which the film 1 is bonded so that the uneven surface is the surface is placed on the photomask 43. A light source 46 is disposed in the light box 45. In this state, by visually observing at a position 49 about 30 cm away from the sample, the degree of glare was sensory evaluated in seven stages. Level 1 corresponds to a state where no glare is observed, level 7 corresponds to a state where severe glare is observed, and level 4 refers to a state where only slight glare is observed.

For the antiglare film having various fine uneven surfaces, the intensity of the one-dimensional power spectrum Ψ ² (f) of the complex amplitude for each spatial frequency in the spatial frequency range of 0.0024 to 0.3 μm ⁻¹ , and the aforementioned glare As a result of analyzing the correlation with the evaluation results, it was found that the degree of glare increases as the intensity at a spatial frequency of 0.02 μm ⁻¹ increases. FIG. 13 shows the relationship between the intensity of Ψ ² (f) and the reflection definition at a spatial frequency of 0.02 μm ⁻¹ . From this, it was found that in order to prevent glare of the antiglare film, it is necessary to reduce the intensity of the one-dimensional power spectrum Ψ ² (f) of the complex amplitude at the spatial frequency of 0.02 μm ⁻¹ .

As described above, in the antiglare film used in the present invention, the one-dimensional power spectrum of the complex amplitude calculated from the elevation of the fine uneven surface has a spatial frequency of 0.032 μm ⁻¹ or more and 0.064 μm ⁻¹ or less. 2 has two inflection points. Further, it is preferable that the second-order derivative related to the spatial frequency of the one-dimensional power spectrum of the complex amplitude is positive at the spatial frequency of 0.024 μm ⁻¹ . The antiglare film showing such a frequency distribution (one-dimensional power spectrum) has a shape in which the one-dimensional power spectrum Ψ ² (f) of complex amplitude is convex downward near the spatial frequency of 0.02 μm ⁻¹ . The complex amplitude one-dimensional power spectrum Ψ ² (f) is convex upward at a spatial frequency of 0.03 μm ⁻¹ and the complex amplitude one-dimensional power spectrum near the spatial frequency of 0.01 μm ^−1. Ψ ² (f) has a shape that is convex downward. As a result, the intensity of the one-dimensional power spectrum Ψ ² (f) of the complex amplitude at the spatial frequency of 0.02 μm ^{−1 that} causes glare is reduced, and at the spatial frequency of 0.03 μm ⁻¹ contributing to the antiglare effect. The intensity of the complex amplitude one-dimensional power spectrum Ψ ² (f) can be increased. Further, it is possible to reduce high spatial frequency components of 0.1 μm ⁻¹ or more that do not effectively contribute to the antiglare property and scatter light incident on the fine uneven surface and cause whitening.

  In addition, in the anti-glare film, the present inventors have shown that, if each minute surface constituting the fine uneven surface exhibits a specific inclination angle distribution, the anti-glare performance can be effectively achieved while exhibiting excellent anti-glare performance. It was found to be more effective in preventing the above. That is, in the antiglare film, it is preferable that the proportion of minute surfaces having an inclination angle of 5 ° or more in the fine uneven surface is less than 10%. If the ratio of the minute surfaces with an inclination angle of 5 ° or more of the fine uneven surface exceeds 10%, the minute surfaces with a sharp inclination angle of the uneven surface will increase, condensing light from the surroundings, It becomes easy to generate whitish that the display surface becomes white as a whole. In order to suppress such a condensing effect and prevent whitishness, the smaller the proportion of the micro-surfaces with an inclination angle of 5 ° or more, the better, among the fine uneven surfaces, which is less than 5%. Preferably, it is less than 2%.

  Here, the “inclination angle of the minute surface on the surface of the fine unevenness” as used in the present invention means the unevenness of the minute surface including the point P as described later at an arbitrary point P on the surface of the antiglare film 1 shown in FIG. It means an angle θ between the local normal 6 added and the main normal direction 5 of the film. Similarly to the altitude, the inclination angle of the fine uneven surface can be obtained from three-dimensional information of the surface shape measured by an apparatus such as a confocal microscope, an interference microscope, an atomic force microscope (AFM).

  FIG. 14 is a schematic diagram for explaining a method of measuring the inclination angle of the minute surface of the minute uneven surface. A specific method of determining the tilt angle will be described. As shown in FIG. 14, a point of interest A on a virtual plane FGHI indicated by a dotted line is determined, and the point of interest on the x-axis passing there passes in the vicinity. The points B and D are approximately symmetrical with respect to the point A, and the points C and E are approximately symmetrical with respect to the point A in the vicinity of the point of interest A on the y-axis passing through the point A. , C, D, and E, the points Q, R, S, and T on the film surface are determined. In FIG. 14, the orthogonal coordinates in the film plane are represented by (x, y), and the coordinates in the film thickness direction are represented by z. The plane FGHI is parallel to the x axis passing through the point C on the y axis and parallel to the x axis passing through the point E on the y axis and to the y axis passing through the point B on the x axis. It is a plane formed by the respective intersections F, G, H, and I with a straight line and a straight line passing through the point D on the x-axis and parallel to the y-axis. Further, in FIG. 14, the actual film surface position is drawn upward with respect to the plane FGHI, but the actual film surface position is naturally above the plane FGHI depending on the position taken by the point of interest A. Sometimes it comes down, sometimes down.

  The inclination angle of the obtained surface shape data is the actual film surface corresponding to the point P on the actual film surface corresponding to the point of interest A and the four points B, C, D, E taken in the vicinity thereof. Obtained by averaging four normal planes 6a, 6b, 6c, 6d of four polygons PQR, PRS, PST, PTQ spanned by a total of five points Q, R, S, T above. It can be obtained by obtaining the polar angle of the local normal (vector) 6 (angle θ formed with the main normal direction 5 of the film in FIG. 1). After obtaining the inclination angle for each measurement point (small surface), a histogram is calculated.

  FIG. 15 is a graph showing an example of the histogram of the inclination angle distribution of the minute surface of the minute uneven surface of the antiglare film. In the graph shown in FIG. 15, the horizontal axis is the inclination angle, and is divided in increments of 0.5 °. For example, the leftmost vertical bar shows the distribution of a set having an inclination angle in the range of 0 to 0.5 °, and the angle increases by 0.5 ° as going to the right. In the figure, the upper limit value is displayed for every two scales on the horizontal axis. For example, a portion with “1” on the horizontal axis is a set of minute surfaces whose inclination angle is in the range of 0.5 to 1 °. The distribution of. The vertical axis represents the ratio of the set to the whole, and is a value that becomes 1 when summed. In this example, the ratio of the minute surfaces whose inclination angle is 5 ° or more is substantially zero.

The surface haze of the antiglare film is preferably 0.4% or more and 10% or less, and the internal haze is preferably 1% or less. Here, the surface haze and internal haze of the antiglare film are measured as follows. That is, first, after the antiglare layer is formed on the transparent support, the antiglare film and the glass substrate are combined with the transparent adhesive so that the side of the transparent support on which the antiglare layer is not formed becomes a bonding surface. And light is incident from the glass substrate side, and the haze is measured according to JIS K 7136. The haze measured in this way corresponds to the total haze of the antiglare film. Next, a triacetyl cellulose film having a haze of almost 0 is bonded to the surface of the fine uneven shape of the antiglare layer using glycerin, and the haze is measured again in accordance with JIS K 7136. The haze can be regarded as the “internal haze” of the antiglare film because the surface haze due to the fine uneven shape is almost canceled by the triacetyl cellulose film bonded onto the surface unevenness. . Therefore, the “surface haze” of the antiglare film is represented by the following formula (12):

Surface haze = Total haze-Internal haze Formula (12)

More demanded.

  The surface haze of the antiglare film is set to 10% or less from the viewpoint of suppressing whitening, and is preferably 5% or less in order to more effectively suppress whitening. On the other hand, the surface haze is preferably 0.4% or more and more preferably 1% or more in order to obtain sufficient antiglare properties. Moreover, it is preferable that an internal haze is 1% or less from a viewpoint which can express a high contrast effectively, when the said anti-glare film is arrange | positioned on the surface of an image display apparatus.

  A conventional anti-glare film is a method in which a resin solution in which fine particles are dispersed is applied onto a transparent support, the coating thickness is adjusted, and fine particles are exposed on the surface of the coating film to form random irregularities on the sheet. Is manufactured by. In order to eliminate glare, the anti-glare film manufactured by dispersing such fine particles scatters light by providing a refractive index difference between the binder resin and the fine particles, and intentionally causes internal haze. Often granted. When such an antiglare film is disposed on the surface of the image display device, the contrast is lowered due to light scattering at the interface between the fine particles and the binder resin. On the other hand, in the antiglare film, since the frequency distribution (one-dimensional power spectrum) of the complex amplitude calculated from the altitude of the fine uneven surface is appropriately designed as described above, the light is scattered. There is no need to eliminate glare. Therefore, the smaller the internal haze that causes the decrease in contrast, the better.

<Method for producing antiglare film>
The antiglare film, in order to obtain better frequency distribution of the complex amplitude as described above (the one-dimensional power spectrum) precision, one-dimensional power spectrum, maximum in large 0.04 .mu.m ^-1 the range from spatial frequency 0 .mu.m ^-1 no value, and it is preferably produced by using the pattern spatial frequency has a local maximum in the larger 0.08 .mu.m ^-1 the range from 0.04 .mu.m ^-1. Here, the “pattern” means image data for forming the fine uneven surface of the antiglare film, a mask having a light transmitting part and a light shielding part, and the like.

For example, when the pattern is image data, the two-dimensional power spectrum of the pattern is obtained by converting the image data into two-level binary image data, and then converting the gradation of the image data by a two-dimensional function g (x, y). represents, resulting two-dimensional function g (x, y) to Fourier transform two-dimensional function G (f _x, f _y) to calculate the resulting two-dimensional function G (f _x, f _y) square It is required by doing. Here, x and y represent orthogonal coordinates of the image data plane, f _x and f _y represent the frequency of the frequency and the y direction of the x-direction.

  Similar to the case of obtaining the two-dimensional power spectrum of the complex amplitude of the fine uneven surface of the antiglare layer, the two-dimensional function g (x, y) of the gradation is also expressed as a discrete function in the case of obtaining the two-dimensional power spectrum of the pattern. It is common to obtain it. In that case, the two-dimensional power spectrum may be calculated by discrete Fourier transform, as in the case of obtaining the complex amplitude two-dimensional power spectrum. The one-dimensional power spectrum of the pattern is obtained from the two-dimensional power spectrum of the pattern in the same manner as the one-dimensional power spectrum of the complex amplitude.

  FIG. 16 is a diagram showing a part of image data which is a pattern used for producing an antiglare film. The image data that is the pattern shown in FIG. 16 has a size of 33 mm × 33 mm and was created at 12800 dpi.

FIG. 17 shows a two-dimensional power spectrum G ² (f _x , f _y ) obtained by performing a discrete Fourier transform on the two-dimensional discrete function g (x, y) having the gradation shown in FIG. It is the figure represented as a function of distance f from an origin like a power spectrum. While this than having a maximum value at the pattern spatial frequencies 0.063Myuemu ^-1 shown in FIG. 16, it can be seen that the spatial frequency does not have a local maximum in the larger 0.04 .mu.m ^-1 the range from 0 .mu.m ^-1.

When the one-dimensional power spectrum of the pattern for making an antiglare film (antiglare layer) has a maximum value at large 0.04 .mu.m ^-1 less than 0 .mu.m ^-1 is the complex amplitude of the antiglare film resulting The one-dimensional power spectrum may not have a downwardly convex shape in the vicinity of a spatial frequency of 0.02 μm ⁻¹ . Also, when the one-dimensional power spectrum pattern does not have a maximum value at large 0.08 .mu.m ^-1 less than 0.04 .mu.m ^-1 is a one-dimensional power spectrum spatial frequency of the complex amplitude of the antiglare film resulting There is a possibility that the convex shape does not have an upward shape after 0.03 μm ⁻¹ . Therefore, it is not possible to combine glare and sufficient antiglare properties.

One dimensional power spectrum does not have a local maximum in the larger 0.04 .mu.m ^-1 less than 0 .mu.m ^-1, and, in order to create a pattern with a maximum value greater than the 0.08 .mu.m ^-1 below 0.04 .mu.m ^-1 The dots having a diameter of 10 μm or more and less than 20 μm may be arranged randomly and uniformly. One or more types of dots may be arranged at random. In addition, in order to more effectively remove a component having a spatial frequency of 0.04 μm ⁻¹ or less from a pattern created by randomly arranging dots in this way, a specific spatial frequency of 0.04 μm ⁻¹ or less is used. It is good also as a pattern for anti-glare film preparation using the pattern obtained by letting the high-pass filter which removes this component pass. Furthermore, the pattern created by placing dots at random, more effectively removes spatial frequency 0.04 .mu.m ^-1 following ingredients, and greater than 0.04 .mu.m ^-1 0.08 .mu.m ^-1 below a maximum value to create a pattern with, passed through a band-pass filter for removing a particular spatial frequency or more components is 0.04 .mu.m ^-1 greater than a specific spatial frequency following ingredients and 0.08 .mu.m ^-1 or less to give It is good also as a pattern for glare-proof film preparation using the obtained pattern. When creating a pattern using a method that passes through a high-pass filter, band-pass filter, etc., a random brightness distribution with the density determined by a random number or a pseudo-random number generated by a computer is used as the pattern before passing through the filter. The pattern which has can also be used.

  In the antiglare film, it is preferable to appropriately form the spatial frequency distribution of the fine uneven surface of the antiglare layer as described above. Therefore, the antiglare film is manufactured using a pattern having the above-described pattern to produce a mold having a fine concavo-convex surface, transferring the concavo-convex surface of the produced mold to a photocurable resin layer or the like on a transparent support, It is preferably produced by an embossing method characterized by producing an antiglare film by peeling off the antiglare layer and the transparent support onto which the uneven surface has been transferred from the mold.

  Here, examples of the embossing method include a UV embossing method using a photocurable resin and a hot embossing method using a thermoplastic resin. Among these, the UV embossing method is preferable from the viewpoint of productivity.

  The UV embossing method forms a photocurable resin layer on the surface of a transparent support, and cures the photocurable resin layer while pressing the photocurable resin layer against the uneven surface of the mold. It is a method of transferring to a layer. Specifically, an ultraviolet curable resin is coated on a transparent support, and the ultraviolet curable resin is irradiated with ultraviolet rays from the transparent support side in a state where the coated ultraviolet curable resin is in close contact with the uneven surface of the mold. The shape of the mold is transferred to the ultraviolet curable resin by curing the resin and then peeling the transparent support on which the cured ultraviolet curable resin layer is formed from the mold.

  When the UV embossing method is used, the transparent support may be a substantially optically transparent film. For example, a triacetyl cellulose film, a polyethylene terephthalate film, a polymethyl methacrylate film, a polycarbonate film, or a norbornene compound is used as a monomer. And a resin film such as a solvent cast film of thermoplastic resin such as amorphous cyclic polyolefin and an extruded film.

  Further, the type of the ultraviolet curable resin in the case of using the UV embossing method is not particularly limited, but a commercially available appropriate one can be used. It is also possible to use a resin that can be cured by visible light having a wavelength longer than that of ultraviolet rays by combining an ultraviolet curable resin with an appropriately selected photoinitiator. Specifically, polyfunctional acrylates such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate are used singly or as a mixture of two or more thereof and Irgacure 907 (manufactured by Ciba Specialty Chemicals). ), Irgacure 184 (manufactured by Ciba Specialty Chemicals), and a photopolymerization initiator such as Lucillin TPO (manufactured by BASF) can be suitably used.

  On the other hand, the hot embossing method is a method in which a transparent support formed of a thermoplastic resin is pressed against a mold in a heated state, and the surface shape of the mold is transferred to the transparent support. The transparent support used in the hot embossing method may be any material as long as it is substantially transparent. For example, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, triacetyl cellulose, norbornene compound is used as a monomer. A solvent cast film or an extruded film of a thermoplastic resin such as amorphous cyclic polyolefin can be used. These transparent resin films can also be suitably used as a transparent support for coating the ultraviolet curable resin in the UV embossing method described above.

<Method for producing mold for producing antiglare film>
Below, the method to manufacture the metal mold | die used for manufacture of the said glare-proof film is demonstrated. The method for producing the mold used for producing the antiglare film is not particularly limited as long as it is a method capable of obtaining a predetermined surface shape using the above-described pattern. However, the fine uneven surface can be accurately and reproducibly. In order to manufacture well, [1] first plating step, [2] polishing step, [3] photosensitive resin film coating step, [4] exposure step, [5] development step, [6] It is preferable to basically include a first etching step, [7] photosensitive resin film peeling step, [8] second etching step, and [9] second plating step. FIG. 18 is a diagram schematically illustrating a preferred example of the first half of the method for manufacturing a mold used for manufacturing an antiglare film. FIG. 18 schematically shows a cross section of the mold in each step. Hereafter, each process of the manufacturing method of the metal mold | die used for manufacture of an anti-glare film is demonstrated in detail, referring FIG.

[1] First plating step In the method of manufacturing a mold used for manufacturing an antiglare film, first, copper plating or nickel plating is applied to the surface of a substrate used for the mold. Thus, by performing copper plating or nickel plating on the surface of the mold base, it is possible to improve the adhesion and gloss of chromium plating in the subsequent second plating step. This is because copper plating or nickel plating has a high covering property and a strong smoothing action, so that a flat and glossy surface is formed by filling minute irregularities and voids of the mold base. is there. Due to these copper plating or nickel plating characteristics, even if chrome plating is applied in the second plating step, which will be described later, the rough surface of the chrome plating that appears to be caused by minute irregularities and voids that existed on the substrate is eliminated. In addition, the occurrence of fine cracks is reduced due to the high coverage of copper plating or nickel plating.

  The copper or nickel used in the first plating step may be a pure metal, or may be an alloy mainly composed of copper or an alloy mainly composed of nickel. “Copper” means to include copper and copper alloy, and “nickel” means to include nickel and nickel alloy. Copper plating and nickel plating may be performed by electrolytic plating or electroless plating, respectively, but electrolytic plating is usually employed.

  When copper plating or nickel plating is performed, if the plating layer is too thin, the influence of the underlying surface cannot be completely eliminated. Therefore, the thickness is preferably 50 μm or more. Although the upper limit of the plating layer thickness is not critical, generally about 500 μm is sufficient from the viewpoint of cost and the like.

  In the metal mold manufacturing method of the present invention, examples of the metal material suitably used for forming the base material include aluminum and iron from the viewpoint of cost. Furthermore, lightweight aluminum is more preferable from the convenience of handling. The aluminum and iron here may be pure metals, respectively, or may be an alloy mainly composed of aluminum or iron.

  The shape of the substrate is not particularly limited as long as it is an appropriate shape that has been conventionally employed in this field, and may be a flat plate shape, or a columnar or cylindrical roll. If a mold is produced using a roll-shaped substrate, there is an advantage that the antiglare film can be produced in a continuous roll shape.

[2] Polishing Step In the subsequent polishing step, the surface of the substrate that has been subjected to copper plating or nickel plating in the first plating step described above is polished. In the mold manufacturing method of the present invention, it is preferable that the substrate surface is polished in a state close to a mirror surface through this step. This is because metal plates and metal rolls that serve as base materials are often subjected to machining such as cutting and grinding in order to achieve the desired accuracy, and as a result, machine marks remain on the base material surface. This is because even if copper plating or nickel plating is applied, those processed marks may remain, and the surface may not be completely smooth in the plated state. That is, even if a process described later is performed on the surface where such deep processed marks remain, unevenness such as processed marks may be deeper than the unevenness formed after each process is performed. Such effects may remain, and when an antiglare film is produced using such a mold, the optical characteristics may be unexpectedly affected. In FIG. 18 (a), a plate-shaped mold substrate 7 is subjected to copper plating or nickel plating on its surface in the first plating step (for the copper plating or nickel plating layer formed in this step). Further, a state in which the surface 8 is mirror-polished by a polishing process is schematically shown.

  There is no particular limitation on the method for polishing the surface of the substrate on which copper plating or nickel plating has been applied, and any of mechanical polishing, electrolytic polishing, and chemical polishing can be used. Examples of the mechanical polishing method include super finishing, lapping, fluid polishing, and buff polishing. Moreover, it is good also considering the base material surface 7 for metal mold | die as a mirror surface by carrying out mirror surface cutting using a cutting tool in a grinding | polishing process. The material and shape of the cutting tool at that time are not particularly limited, and carbide tools, CBN tools, ceramic tools, diamond tools, etc. can be used, but diamond tools should be used from the viewpoint of processing accuracy. Is preferred. As for the surface roughness after polishing, the center line average roughness Ra in accordance with the provisions of JIS B 0601 is preferably 0.1 μm or less, and more preferably 0.05 μm or less. If the center line average roughness Ra after polishing is greater than 0.1 μm, the final unevenness of the mold surface may be affected by the surface roughness after polishing, which is not preferable. In addition, the lower limit of the center line average roughness Ra is not particularly limited, and there is no limit in particular because there is a natural limit from the viewpoint of processing time and processing cost.

[3] Photosensitive resin film application step In the subsequent photosensitive resin film application step, the photosensitive resin is applied as a solution in which the photosensitive resin is dissolved in a solvent to the surface 8 of the substrate 7 that has been mirror-polished in the above-described polishing step, and heated. -A photosensitive resin film is formed by drying. FIG. 18B schematically shows a state in which the photosensitive resin film 9 is formed on the surface 8 of the base material 7.

  A conventionally known photosensitive resin can be used as the photosensitive resin. For example, a negative photosensitive resin having a property of curing the photosensitive part includes an acrylic ester monomer or prepolymer having an acrylic group or a methacrylic group in the molecule, a mixture of bisazide and diene rubber, polyvinyl thinner. Mart compounds and the like can be used. In addition, as a positive photosensitive resin having a property that a photosensitive portion is eluted by development and only an unexposed portion remains, a phenol resin type or a novolac resin type can be used. Moreover, you may mix | blend various additives, such as a sensitizer, a development accelerator, an adhesiveness modifier, and a coating property improving agent, with a photosensitive resin as needed.

  When these photosensitive resins are applied to the surface 8 of the substrate 7, in order to form a good coating film, it is preferable to dilute and apply in an appropriate solvent. Cellosolve solvents, propylene glycol solvents An ester solvent, an alcohol solvent, a ketone solvent, a highly polar solvent, or the like can be used.

  As a method for applying the photosensitive resin solution, known methods such as meniscus coating, fountain coating, dip coating, spin coating, roll coating, wire bar coating, air knife coating, blade coating, curtain coating, ring coating, etc. are used. be able to. The thickness of the coating film is preferably in the range of 1 to 6 μm after drying.

[4] In the exposure step subsequent exposure step, one-dimensional power spectrum above not a lifting a maximum value is greater 0.04 .mu.m ^-1 less than 0 .mu.m ^-1, and greater than 0.04 .mu.m ^-1 0.08 .mu.m ^-1 The pattern having the maximum value below is exposed on the photosensitive resin film 9 formed in the above-described photosensitive resin film coating step. The light source used in the exposure process may be appropriately selected according to the photosensitive wavelength, sensitivity, etc. of the coated photosensitive resin. For example, g line (wavelength: 436 nm) of a high pressure mercury lamp, h line (wavelength: 405 nm) of a high pressure mercury lamp. , High pressure mercury lamp 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 excimer laser (wavelength: 193 nm), F2 excimer laser (wavelength: 157 nm), or the like.

  In order to form the surface uneven shape with high accuracy in the mold manufacturing method of the present invention, it is preferable to expose the above-described pattern on the photosensitive resin film in a precisely controlled manner in the exposure step. In the mold manufacturing method of the present invention, in order to accurately expose the above-described pattern on the photosensitive resin film, the pattern is created as image data on the computer, and the pattern based on the image data is controlled by the computer. It is preferable to draw with a laser beam emitted from the laser head. When performing laser drawing, a laser drawing apparatus for making a printing plate can be used. An example of such a laser drawing apparatus is Laser Stream FX (manufactured by Sink Laboratories).

  FIG. 18C schematically shows a state in which the pattern is exposed to the photosensitive resin film 9. When the photosensitive resin film is formed of a negative photosensitive resin, the exposed region 10 undergoes a crosslinking reaction of the resin by exposure, and the solubility in a developing solution described later decreases. Therefore, the unexposed area 11 in the developing process is dissolved by the developer, and only the exposed area 10 remains on the substrate surface as a mask. On the other hand, in the case where the photosensitive resin film is formed of a positive photosensitive resin, the exposed region 10 is cut by bonding of the resin by exposure, and the solubility in a developer described later increases. Therefore, the area 10 exposed in the development process is dissolved by the developer, and only the unexposed area 11 remains on the substrate surface as a mask.

[5] Development Step In the subsequent development step, when a negative photosensitive resin is used for the photosensitive resin film 9, the unexposed region 11 is dissolved by the developer, and only the exposed region 10 is gold. It remains on the mold substrate and acts as a mask in the subsequent first etching step. On the other hand, when a positive photosensitive resin is used for the photosensitive resin film 9, only the exposed region 10 is dissolved by the developer, and the unexposed region 11 remains on the mold substrate. It acts as a mask in the subsequent first etching step.

  A conventionally well-known thing can be used about the developing solution used for a image development process. For example, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, primary amines such as ethylamine and n-propylamine, diethylamine, di-n-butylamine, etc. Secondary amines, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, secondary amines such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and trimethylhydroxyethylammonium hydroxide Examples include alkaline aqueous solutions such as quaternary ammonium salts, cyclic amines such as pyrrole and pihelidine, and organic solvents such as xylene and toluene.

  The development method in the development step is not particularly limited, and methods such as immersion development, spray development, brush development, and ultrasonic development can be used.

  FIG. 18D schematically shows a state in which a development process is performed using a negative photosensitive resin for the photosensitive resin film 9. In FIG. 18C, the unexposed region 11 is dissolved by the developer, and only the exposed region 10 becomes the remaining mask 12 on the substrate surface. FIG. 18E schematically shows a state in which a development process is performed using a positive photosensitive resin for the photosensitive resin film 9. In FIG. 18C, the exposed area 10 is dissolved by the developer, and only the unexposed area 11 becomes the remaining mask 12 on the substrate surface.

[6] First Etching Step In the subsequent first etching step, the mold base is mainly used in a portion where there is no mask, using the photosensitive resin film remaining on the mold base surface after the development step as a mask. Etch the material.
FIG. 19 is a diagram schematically showing a preferred example of the latter half of the mold manufacturing method of the present invention.
FIG. 19A schematically shows a state in which the mold base 7 in the region 13 without the mask is mainly etched by the first etching step. The mold base 7 below the mask 12 is not etched from the mold base surface, but the etching from the region 13 without the mask proceeds with the progress of etching. Therefore, in the vicinity of the boundary between the mask 12 and the region 13 without the mask, the mold base 7 below the mask 12 is also etched. In the vicinity of the boundary between the mask 12 and the unmasked region 13, the etching of the mold base 7 below the mask 12 is hereinafter referred to as side etching.

The etching process in the first etching step is usually performed using a ferric chloride (FeCl ₃ ) solution, a cupric chloride (CuCl ₂ ) solution, an alkaline etching solution (Cu (NH ₃ ) ₄ Cl ₂ ), or the like. Although it is performed by corroding the surface, a strong acid such as hydrochloric acid or sulfuric acid can be used, or reverse electrolytic etching by applying a potential opposite to that at the time of electrolytic plating can also be used. The concave shape formed on the mold base material when the etching process is performed differs depending on the type of the base metal, the type of the photosensitive resin film, the etching technique, and the like. In the following cases, the etching is performed isotropically from the metal surface in contact with the etching solution. The etching amount here is the thickness of the base material to be cut by etching.

  The etching amount in the first etching step is preferably 1 to 50 μm, more preferably 2 to 10 μm. When the etching amount is less than 1 μm, the unevenness shape is hardly formed on the metal surface, and the die is almost flat, so that the antiglare property is not exhibited. Further, when the etching amount exceeds 50 μm, the height difference of the uneven shape formed on the metal surface is increased, and the antiglare film produced using the obtained mold is preferably whitened. Absent. The etching process in the first etching step may be performed by one etching process, or the etching process may be performed twice or more. Here, when the etching process is performed twice or more, the total etching amount in the two or more etching processes is preferably 1 to 50 μm.

[7] Photosensitive resin film peeling step In the subsequent photosensitive resin film peeling step, the remaining photosensitive resin film used as a mask in the first etching step is completely dissolved and removed. In the photosensitive resin film peeling step, the photosensitive resin film is dissolved using a peeling solution. As the stripper, the same developer as that described above can be used. When a negative photosensitive resin film is used by changing pH, temperature, concentration, immersion time, etc., the exposed portion is exposed. When the positive photosensitive resin film is used, the photosensitive resin film in the non-exposed portion is completely dissolved and removed. There is no particular limitation on the peeling method in the photosensitive resin film peeling step, and methods such as immersion development, spray development, brush development, and ultrasonic development can be used.

  FIG. 19B schematically shows a state where the photosensitive resin film used as a mask in the first etching process is completely dissolved and removed by the photosensitive resin film peeling process. A first surface irregularity shape 15 is formed on the surface of the mold substrate by the mask 12 and etching using the photosensitive resin film.

[8] Second Etching Step In the second etching step, the first surface uneven shape 15 formed by the first etching step using the photosensitive resin film as a mask is blunted by an etching process.
By this second etching process, there is no portion with a steep surface inclination in the first surface irregularity shape 15 formed by the first etching process, and the optical characteristics of the antiglare film manufactured using the obtained mold are reduced. It changes in the preferred direction. In FIG. 19C, the second etching process causes the first surface uneven shape 15 of the mold base 7 to be blunted, a portion having a steep surface slope is blunted, and a second surface having a gentle surface slope is obtained. The state in which the surface irregularities 16 are formed is shown.

Similarly to the first etching step, the etching process in the second etching step is usually ferric chloride (FeCl ₃ ) solution, cupric chloride (CuCl ₂ ) solution, alkaline etching solution (Cu (NH ₃ ) ₄ Cl ₂ ) or the like, and by corroding the surface, strong acid such as hydrochloric acid or sulfuric acid can be used, or reverse electrolytic etching by applying a potential opposite to that during electrolytic plating can be used. The bluntness of the unevenness after the etching process varies depending on the type of the underlying metal, the etching technique, and the size and depth of the unevenness obtained by the first etching process. The largest factor in controlling the amount is the etching amount. The etching amount here is also the thickness of the base material to be cut by etching, as in the first etching step. If the etching amount is small, the effect of dulling the surface shape of the unevenness obtained by the first etching step is insufficient, and the optical characteristics of the antiglare film obtained by transferring the uneven shape to a transparent film are not so good. . On the other hand, when the etching amount is too large, the uneven shape is almost lost and the die is almost flat, so that the antiglare property is not exhibited. Therefore, the etching amount is preferably in the range of 1 to 50 μm, and more preferably in the range of 4 to 20 μm. Similarly to the first etching process, the etching process in the second etching process may be performed by one etching process, or the etching process may be performed twice or more. Here, when the etching process is performed twice or more, the total etching amount in the two or more etching processes is preferably 1 to 50 μm.

[9] Second plating step Subsequently, by performing chromium plating, the second surface irregularity shape 16 is blunted and the mold surface is protected. In FIG. 19 (d), as described above, the chromium plating layer 17 is formed on the second surface irregularities 16 formed by the etching process of the second etching step, and the surface 18 of the chromium plating layer is blunted. It is shown.

In the present invention, chrome plating is employed which has a glossy surface, a high hardness, a low coefficient of friction, and good release properties on the surface of a flat plate or a roll. The type of chrome plating is not particularly limited, but it is preferable to use a chrome plating that expresses a good gloss, so-called gloss chrome plating or decorative chrome plating. Chromium plating is usually performed by electrolysis, and an aqueous solution containing chromic anhydride (CrO ₃ ) and a small amount of sulfuric acid is used as the plating bath. By adjusting the current density and electrolysis time, the thickness of the chromium plating can be controlled.

  In the second plating step, it is not preferable to perform plating other than chromium plating. This is because plating other than chromium has low hardness and wear resistance, so that the durability as a mold is lowered, and unevenness is worn away during use or the mold is damaged. In an antiglare film obtained from such a mold, there is a high possibility that a sufficient antiglare function cannot be obtained, and there is a high possibility that defects will occur on the film.

  Further, polishing the surface after plating is also not preferable in the present invention. By polishing, a flat part is generated on the outermost surface, which may lead to deterioration of optical characteristics, and since shape control factors increase, shape control with good reproducibility becomes difficult. Depending on the reason.

  Thus, in the present invention, it is preferable to use the chrome plated surface as the uneven surface of the mold without polishing the surface after chrome plating. This is because, by applying chromium plating to the surface on which the fine surface irregularities are formed, a mold having an irregular surface that is dulled and whose surface hardness is increased can be obtained. The bluntness of the irregularities at this time varies depending on the type of the base metal, the size and depth of the irregularities obtained from the first etching process, and the type and thickness of the plating. The greatest factor in controlling is the plating thickness. If the thickness of the chrome plating is thin, the effect of dulling the surface shape of the unevenness obtained before the chrome plating process is insufficient, and the optical properties of the antiglare film obtained by transferring the uneven shape to a transparent film are not sufficient. It doesn't get better. On the other hand, when the plating thickness is too thick, productivity is deteriorated and a projection-like plating defect called a nodule is generated, which is not preferable. Therefore, the thickness of the chrome plating is preferably in the range of 1 to 10 μm, and more preferably in the range of 3 to 6 μm.

  The chromium plating layer formed in the second plating step is preferably formed to have a Vickers hardness of 800 or more, and more preferably 1000 or more. When the Vickers hardness of the chrome plating layer is less than 800, the durability when using the mold is reduced, and the decrease in hardness due to chrome plating is due to abnormalities in the plating bath composition, electrolysis conditions, etc. during the plating process. This is because the possibility of occurrence is high, and the possibility of undesirably affecting the occurrence of defects is also high.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. Moreover, the evaluation method of the metal mold | die or anti-glare film in the following examples is as follows.

[1] Measurement of surface shape of antiglare film (Measurement of surface elevation)
The elevation of the surface of the antiglare film was measured using a three-dimensional microscope PLμ2300 (manufactured by Sensofar). In order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent pressure-sensitive adhesive so that the uneven surface became the surface. During the measurement, the objective lens was measured at a magnification of 10 times. The horizontal resolutions Δx and Δy were both 1.66 μm and the measurement area was 1270 μm × 950 μm.

(Power spectrum of complex amplitude)
Sampling 512 × 512 data (850 μm × 850 μm in measurement area) from the center of the measurement data obtained above, and using the two-dimensional function h (x, y) as the elevation of the fine uneven surface of the antiglare film Asked. The complex amplitude was calculated as a two-dimensional function ψ (x, y) from the obtained two-dimensional function h (x, y). The wavelength λ for calculating the complex amplitude was set to 550 nm. The two-dimensional function ψ (x, y) two-dimensional function with a discrete Fourier transform Ψ (f _x, f _y) was determined. Two-dimensional function [psi (f _x, f _y) a two-dimensional function ^{_{Ψ 2 (f x, f y}} ) of the two-dimensional power spectrum by squaring calculates a is a function of the distance f from the origin of the one-dimensional power spectrum A one-dimensional function Ψ ² (f) was calculated. The one-dimensional function Ψ ² (f) is linearly interpolated to obtain discrete functions every 0.008 μm ⁻¹ . The inflection point of the one-dimensional power spectrum of the complex amplitude was calculated from the second derivative of Ψ ² (f), which is a discrete function every 0.008 μm ⁻¹ .

(Inclination angle of fine uneven surface)
Based on the measurement data obtained above, calculation is performed based on the above-described algorithm, a histogram of the inclination angle of the uneven surface is created, a distribution for each inclination angle is obtained therefrom, and the inclination angle is 5 ° or more. The percentage of the surface was calculated.

(Surface roughness parameter of fine uneven surface)
The surface roughness parameter of the antiglare film was measured using a surface roughness measuring device Surf Test SJ-301 manufactured by Mitutoyo Corporation in accordance with JIS B 0601. In order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent pressure-sensitive adhesive so that the uneven surface became the surface.

[2] Measurement of optical properties of antiglare film (haze)
The total haze of the antiglare film is obtained by bonding the antiglare film to a glass substrate on the side opposite to the antiglare layer forming surface using an optically transparent adhesive, and the antiglare film bonded to the glass substrate. The glare film was measured using a haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd. in accordance with JIS K 7136 with light incident from the glass substrate side. Further, the internal haze was measured based on JIS K 7136 again by laminating a triacetyl cellulose film having a haze of almost 0 on the uneven surface of the antiglare layer using glycerin. The surface haze was calculated based on the above formula (12).

(Transparency definition)
The transmission clarity of the antiglare film was measured using an image clarity measuring device “ICM-1DP” manufactured by Suga Test Instruments Co., Ltd. based on JIS K 7105. Also in this case, in order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent adhesive so that the fine uneven surface of the antiglare layer was the surface. . In this state, light was incident from the glass side and measurement was performed. The measured value here is a total value of values measured using four types of optical combs in which the widths of the dark part and the bright part are 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively. . In this case, the maximum value of the transmission clarity is 400%.

(Reflection sharpness)
The reflection sharpness of the antiglare film was measured using an image measuring device “ICM-1DP” manufactured by Suga Test Instruments Co., Ltd. based on JIS K 7105. Also in this case, in order to prevent the sample from warping, it is used for measurement after being bonded to a black acrylic substrate using an optically transparent adhesive so that the fine uneven surface of the antiglare layer becomes the surface. did. In this state, light was incident at 45 ° from the concavo-convex surface side, and measurement was performed. The measured value here is a total value of values measured using four types of optical combs in which the widths of the dark part and the bright part are 0.5 mm, 1.0 mm, and 2.0 mm, respectively. In this case, the maximum value of the reflection definition is 300%.

[3] Measurement of mechanical properties of antiglare film (pencil hardness)
The pencil hardness of the antiglare film was measured by the method defined in JIS K5600-5-4. Specifically, the measurement was performed with a load of 500 g using an electric pencil scratch hardness tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) compliant with this standard.

[4] Evaluation of liquid crystal display device (contrast)
The backlight of the liquid crystal display device was turned on in the dark room, and the brightness of the liquid crystal display device in the black display state and the white display state was measured using a luminance meter BM5A type (manufactured by Topcon Corporation), and the contrast was calculated. . Here, the contrast is represented by the ratio of the luminance in the white display state to the luminance in the black display state.

(Reflection, whitish, glare)
The contrast evaluation system was moved into a bright room, and the reflected state and whitishness were visually observed as a black display state. Next, the white display state was set in the bright room, and the glare was also visually observed. The evaluation criteria for reflection, whiteness, and glare are as follows.

(A) Reflection 1: Reflection is not observed.

2: Reflection is slightly observed.
3: Reflection is clearly observed.

(B) Whitish 1: Whitish is not observed.

2: A little whitish is observed.
3: The whitish is clearly observed.

(C) Glare 1: No glare is observed.

2: Very slight glare is observed.
3: Severe glare is observed.

[5] Evaluation of pattern for production of anti-glare film The created pattern data was made into binary image data of two gradations, and the gradation was expressed by a two-dimensional discrete function g (x, y). The horizontal resolutions Δx and Δy of the discrete function g (x, y) are both 2 μm. The resulting two-dimensional function g (x, y) and by discrete Fourier transform, two-dimensional function G (f _x, f _y) was determined. Two-dimensional function G (f _x, f _y) a two-dimensional function ^{_{G 2 (f x, f y}} ) of the two-dimensional power spectrum by squaring calculates a is a function of the distance f from the origin of the one-dimensional power spectrum A one-dimensional function G ² (f) was calculated.

<Example 1>
(A) Production of Polarizing Film A polyvinyl alcohol film having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm was immersed in pure water at 30 ° C., and then iodine / potassium iodide / water. It was immersed in an aqueous solution having a mass ratio of 0.02 / 2/100 at 30 ° C. Then, it immersed at 56.5 degreeC in the aqueous solution whose mass ratio of potassium iodide / boric acid / water is 12/5/100. Subsequently, after washing with pure water at 8 ° C., it was dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.
(B) Production of mold for production of anti-glare film A surface of an aluminum roll having a diameter of 200 mm (A5056 by JIS) was prepared by applying copper ballad plating. Copper ballad plating consists of a copper plating layer / thin silver plating layer / surface copper plating layer, and the thickness of the entire plating layer was set to be about 200 μm. The copper plating surface was mirror-polished, and a photosensitive resin was applied to the polished copper plating surface and dried to form a photosensitive resin film. Then, the pattern having a pattern (random brightness distribution shown in FIG. 16, is passed through a bandpass filter to remove 0.035 .mu.m ^-1 or lower spatial frequency components and 0.15 [mu] m ^-1 or more high spatial frequency components The prepared pattern was repeatedly exposed and developed on the photosensitive resin film with a laser beam. Laser light exposure and development were performed using Laser Stream FX (manufactured by Sink Laboratory Co., Ltd.). A positive photosensitive resin was used for the photosensitive resin film.

  Then, the 1st etching process was performed with the cupric chloride liquid. The etching amount at that time was set to 3 μm. The photosensitive resin film was removed from the roll after the first etching treatment, and the second etching treatment was performed again with cupric chloride solution. The etching amount at that time was set to 10 μm. Then, the chromium plating process was performed and the metal mold | die A was produced. At this time, the chromium plating thickness was set to 4 μm.

(C) Production of antiglare film The following components were dissolved in ethyl acetate at a solid concentration of 60%, and an ultraviolet curable resin composition A having a refractive index of 1.53 after curing was obtained.

Pentaerythritol triacrylate 60 parts Multifunctional urethanated acrylate 40 parts (Reactive product of hexamethylene diisocyanate and pentaerythritol triacrylate)
Diphenyl (2,4,6-trimethoxybenzoyl) phosphine oxide 5 parts

The ultraviolet curable resin composition A was applied onto a triacetyl cellulose (TAC) film having a thickness of 80 μm so that the coating thickness after drying was 7 μm, and was dried in a dryer set at 60 ° C. for 3 minutes. . The film after drying was brought into close contact with the concavo-convex surface of the mold A obtained previously with a rubber roll so that the photocurable resin composition layer was on the mold side. In this state, light from a high-pressure mercury lamp with an intensity of 20 mW / cm ² was irradiated from the TAC film side so that the amount of light in terms of h-line was 200 mJ / cm ² to cure the photocurable resin composition layer. Then, the TAC film was peeled from the mold together with the cured resin, and a transparent antiglare film A composed of a laminate of a cured resin (antiglare layer) having irregularities on the surface and the TAC film was produced.

(D) Preparation of anti-glare polarizing plate 1.8 parts by weight of carboxyl group-modified polyvinyl alcohol “Kuraray Poval KL318” (modified degree 2 mol%) sold by Kuraray Co., Ltd. with respect to 100 parts by weight of water Dissolve, and further add 1.5 parts by weight of “Smileze Resin 650” (aqueous solution with a solid content of 30%) sold by Sumika Chemtex Co., Ltd., which is a water-soluble polyamide epoxy resin, A polyvinyl alcohol-based adhesive was produced.

  After the saponification treatment is performed on the side opposite to the side on which the antiglare layer of the antiglare film A is formed, the polyvinyl alcohol-based adhesive prepared as described above is applied with a 10 μm bar coater, and is obtained on that. A polyvinyl alcohol-iodine polarizing film was bonded. Also, optically negative uniaxial discotic liquid crystal molecules are coated and fixed on the substrate on the surface opposite to the surface on which the anti-glare film of the polyvinyl alcohol-iodine polarizing film is bonded. A film having an optically anisotropic layer in which the axis is in a hybrid orientation sequentially inclined between 5 to 50 ° from the normal direction of the film, and the apparent optical axis as a whole is in the direction of about 18 ° from the normal line The name “WV film” manufactured by Fuji Photo Film Co., Ltd.] was saponified, and the polyvinyl alcohol-based adhesive prepared as described above was applied with a 10 μm bar coater and then bonded. Then, it dried at 80 degreeC for 5 minute (s), and also cured at normal temperature for 1 day, and the anti-glare polarizing plate A was obtained.

(E) Production of liquid crystal display device The polarizing plate is peeled off from the liquid crystal cell of a commercially available monitor (W2261VG-PF, manufactured by LG Electronics) on which a TN mode liquid crystal display element (that is, an image display element) is mounted. On the (backlight side) side, optically negative uniaxial discotic liquid crystal molecules are coated and fixed on the substrate, and the optical axis is sequentially inclined between 5 and 50 ° from the normal direction of the film. An optically anisotropic layer (trade name “WV film”, manufactured by Fuji Photo Film Co., Ltd.) having a hybrid orientation and an apparent optical axis of about 18 ° from the normal as a whole is a polyvinyl alcohol-iodine system. A linear polarizer / optically anisotropic layer laminate (trade name “Sumikaran SRH862), which is attached to one side of a linear polarizer and a triacetyl cellulose film attached to the other side of the polarizer. A ", manufactured by Sumitomo Chemical Co., Ltd.], and the anti-glare polarizing plate A on the front surface (viewing side) of the liquid crystal cell. A liquid crystal panel was prepared by bonding through an adhesive layer so as to coincide with the absorption axis direction of the plate. Next, this liquid crystal panel was assembled in a configuration of backlight / light diffusing plate / liquid crystal panel to produce a liquid crystal display device A (that is, an image display device).

<Comparative Example 1>
The surface of a 300 mm diameter aluminum roll (JIS A5056) is mirror-polished, and the polished aluminum surface is coated with zirconia beads TZ-SX-17 (Tosoh Corp.) using a blasting device (Fuji Seisakusho). ), Average particle size: 20 μm), and blasted at a blast pressure of 0.1 MPa (gauge pressure, the same shall apply hereinafter) and a bead usage of 8 g / cm ² (amount used per 1 cm ² of surface area of the roll, the same shall apply hereinafter) The surface was uneven. The obtained uneven aluminum roll was subjected to electroless nickel plating to produce a mold B. At this time, the electroless nickel plating thickness was set to 15 μm. An antiglare film B was produced in the same manner as in Example 1 except that the obtained mold B was used. Further, an antiglare polarizing plate B and a liquid crystal display device B were produced in the same manner as in Example 1 except that the antiglare film B was used.

FIG. 17 shows the power spectrum G ² (f) obtained from the pattern used for the production of the antiglare film A. Antiglare power spectrum of a pattern used to make the film A has no local maximum value in the following larger 0.04 .mu.m ^-1 than the spatial frequency is 0 .mu.m ^-1, maximum largely 0.08 .mu.m ^-1 less than 0.04 .mu.m ^-1 You can see that it has a value.

FIG. 20 shows the second derivative d ² Ψ ² (f) / df ² of the power spectrum of the complex amplitude calculated from the altitudes of the antiglare films A to C. From FIG. 20, the one-dimensional power spectrum of the complex amplitude calculated from the altitude of the antiglare film A has two inflection points in the spatial frequency range of 0.032 μm ^{−1 to} 0.064 μm ^−1. The one-dimensional power spectrum of the complex amplitude calculated from the altitudes of the antiglare films B and C does not have two inflection points in the spatial frequency range of 0.032 μm ^{−1 to} 0.064 μm ^−1. I understand that there is no.

  Table 1 shows the results of the above evaluations on the antiglare films A and B and the liquid crystal display devices A and B produced in Example 1 and Comparative Example 1.

  From the results shown in Table 1, the image display apparatus A (Example 1) that satisfies all the requirements of the present invention does not generate glare at all, exhibits sufficient antiglare properties, does not generate whiteness, and has high contrast. And wide viewing angle characteristics. On the other hand, the image display apparatus B (Comparative Example 1) using the anti-glare film B (see FIG. 20) that does not satisfy the requirements of the present invention showed a tendency to generate glare.

  DESCRIPTION OF SYMBOLS 1 Anti-glare film, 2 Concavity and convexity formed on film surface, 3 Projection plane of film, 5 Main normal direction of film, 6 Local normal, 6a-6d Polygon surface normal vector, 7 Mold base Material, 8 surface of substrate polished by polishing process, 9 photosensitive resin film, 10 exposed area, 11 unexposed area, 12 mask, 13 unmasked area, 15 first surface irregular shape ( Concave and convex shapes on the surface of the mold base after the first etching step), 16 Concave and convex shapes on the second surface (concave and convex shape on the surface of the mold base after the second etching step), 17 Chrome plating layer, 18 Chrome plating Layer surface, 20 elevation reference plane, 21 highest elevation plane, 40 photomask unit cell, 41 photomask chrome shading pattern, 42 photomask opening, 43 photomask, 4 5 light box, 46 light source, 47 glass plate, 49 glare observation position, 50 diffuser plate, 100 antiglare layer, 101 transparent support, 102, 103, 104 transparent protective film, 110 liquid crystal cell, 111, 112 cell substrate, 113, 114 electrode, 115 liquid crystal layer, 120 (front side) polarizing film, 121 (back side) polarizing film, 130 (first) optical anisotropic layer, 131 (second) optical anisotropic layer.

Claims (5)

A liquid crystal cell in which a twisted nematic liquid crystal is sealed between a pair of cell substrates parallel to each other;
A front-side polarizing film disposed on the viewing side of the liquid crystal cell;
A back side polarizing film disposed on the opposite side;
An optically anisotropic layer disposed between at least one of the back side polarizing film and the liquid crystal cell and between the front side polarizing film and the liquid crystal cell;
An antiglare film comprising a transparent support, and an antiglare layer formed on the transparent support and having a fine uneven surface having fine unevenness on the opposite side of the transparent support;
Furthermore, the antiglare film is a liquid crystal display device disposed so that the antiglare layer is on the most visible side on the side opposite to the surface facing the liquid crystal cell of the front side polarizing film,
The antiglare film has an internal surface having an internal haze of 1% or less, a surface haze of 0.4% or more and 10% or less, and an average surface obtained from an average when the altitude of the fine uneven surface is measured. Highest elevation that is incident from a main normal direction perpendicular to the average surface of the fine uneven surface, includes a point having the highest elevation among the fine uneven surface, and is a virtual plane parallel to the average surface of the fine uneven surface For a plane wave with a wavelength of 550 nm emitted from the surface, the complex amplitude at the highest altitude surface is calculated from the altitude of the surface of the fine unevenness and the refractive index of the antiglare layer, and the one-dimensional power spectrum of the complex amplitude is expressed as an intensity with respect to the spatial frequency. The liquid crystal display device according to claim ¹ , wherein the graph has two inflection points in a spatial frequency range of 0.032 μm ^{−1 to} 0.064 μm ⁻¹ .   The liquid crystal display device according to claim 1, wherein an optically anisotropic layer is disposed between the back side polarizing film and the liquid crystal cell and between the front side polarizing film and the liquid crystal cell.   The liquid crystal display device according to claim 1, wherein the optically anisotropic layer is optically negative or positive uniaxial, and the optical axis is inclined by 5 to 50 ° from a normal direction of the film. . The liquid crystal display device according to claim 1, wherein a second-order derivative related to a spatial frequency of the one-dimensional power spectrum of the complex amplitude is positive at a spatial frequency of 0.024 μm ⁻¹ .   The liquid crystal display device according to any one of claims 1 to 4, wherein a ratio of a minute surface having an inclination angle of 5 ° or more of the fine uneven surface is less than 10%.