JP2009156939A - Antiglare film, antiglare polarizing plate and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antiglare film showing excellent antiglare performance, preventing decrease in visibility due to haze, achieving a high contrast without causing glare and having excellent mechanical strength. <P>SOLUTION: The antiglare film has a hard coat layer having a fine concavo-convex pattern on its surface laminated on at least one surface of a resin base film having a flat surface, and is characterized in that: a ratio n<SB>r</SB>/n<SB>f</SB>of the refractive index n<SB>r</SB>of the hard coat layer to the refractive index n<SB>f</SB>of the resin base film is not more than 0.96; and when light is incident perpendicular from the resin base film side on the interface between the resin base film and the hard coat layer, a ratio T(60)/T(0) of the scattered light intensity T(60) at an angle 60° from the normal line in the hard coat layer side to the scattered light intensity T(0) along the normal direction in the hard coat layer is not more than 0.000001. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is not anti-glare while exhibiting excellent anti-glare performance, does not cause glare when applied to an image display device, exhibits high contrast, and provides good visibility, an anti-glare film. In addition, the present invention relates to an antiglare polarizing plate and an image display device using the antiglare film.

  In an image display device such as a liquid crystal display, a plasma display panel, a cathode ray tube (CRT) display, and an organic electroluminescence (EL) display, visibility is significantly impaired when external light is reflected on the display surface. Conventionally, in order to prevent such reflection of external light, televisions and personal computers that emphasize image quality, video cameras and digital cameras that are used outdoors with strong external light, and mobile phones that display using reflected light In a telephone or the like, a film layer for preventing external light from being reflected is provided on the surface of an image display device. For this film layer, anti-reflection processing technology using interference by optical multilayer film and anti-glare processing technology that blurs the reflected image by scattering incident light by forming fine irregularities on the surface are generally used. ing. In particular, the latter technique of scattering incident light by forming fine irregularities can be manufactured at a relatively low cost, and is therefore widely used in applications such as large monitors and personal computers.

  Conventionally, an anti-glare film to which such an anti-glare treatment technology has been applied, for example, a resin solution in which a filler is dispersed is applied on a base sheet, and the coating film thickness is adjusted to expose the filler on the coating film surface. Thus, it is manufactured by a method of forming random irregularities on a base sheet. However, the antiglare film produced by dispersing such a filler has an unevenness as intended because the arrangement and shape of the unevenness depends on the dispersion state and application state of the filler in the resin solution. There is a problem that it is difficult to obtain, and sufficient anti-glare performance cannot be obtained if the haze is low. Furthermore, when such a conventional anti-glare film is disposed on the surface of an image display device, there is a problem that the entire display surface becomes whitish due to scattered light, and the display becomes cloudy, so-called whitening is likely to occur. It was.

  In addition, when the image display device is high-definition, the pixel of the image display device and the surface uneven shape of the anti-glare film interfere with each other, and as a result, a luminance distribution is generated and the so-called glare phenomenon is likely to occur. There was a problem. In order to eliminate glare, there is an attempt to scatter light by providing a difference in refractive index between the binder resin and the dispersion filler, but when such an antiglare film is applied to an image display device, scattered light is scattered. As a result, the luminance of black display is increased, resulting in a problem that the contrast is lowered and the visibility is remarkably lowered. In addition, in the antiglare film in which the surface unevenness shape is formed by such a filler, the surface unevenness shape for scattering incident light and the region mainly responsible for the internal scattering of light are simultaneously formed. In addition to designing with a balance between the particle size, concentration, refractive index, and dispersibility of the dispersed particles, precise control is necessary in production, but such design and control is practically difficult. As an attempt to avoid such complicated design and control, Patent Document 1 discloses that the formation of the resin layer having the internal scattering function of light and the formation of the uneven surface shape are performed separately. In the method of coating by dispersing in a resin solution, there is a problem that unexpected aggregation or the like is likely to occur during the drying process.

On the other hand, there is also an attempt to develop anti-glare properties only by fine irregularities formed on the surface of the transparent resin layer without containing a filler. For example, in Patent Document 2 (Claims 1 to 6, paragraphs 0043 to 0046), the ionizing radiation curable resin is cured with the ionizing radiation curable resin sandwiched between the embossing mold and the transparent resin film. On the transparent resin film, the three-dimensional 10-point average roughness and the average distance between adjacent convex portions on the three-dimensional roughness reference surface form fine irregularities satisfying predetermined values, respectively. An antiglare film in which a cured product layer of an ionizing radiation curable resin layer having surface irregularities is laminated is disclosed. On the other hand, an embossing method as disclosed in Patent Document 3 can be cited as a different type of embossing method for obtaining such an antiglare film.
JP 2007-101912 A JP 2002-189106 A JP 2006-053371 A

  The present invention has been made in view of the current situation, and its purpose is to provide excellent anti-glare performance, while preventing a decrease in visibility due to whitishness, and placing it on the surface of a high-definition image display device. Sometimes an anti-glare film exhibiting high contrast without causing glare and excellent in mechanical strength is provided. Further, an anti-glare polarizing plate using the anti-glare film and An image display device is provided.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the surface of the resin base film having a flat surface has a refractive index ratio of 0.96 or less to the surface of the resin base film. If a hard coat layer having a fine concavo-convex shape is formed and the scattered light intensity exhibits a predetermined value, as a result, the glare is sufficiently prevented and the contrast is little when applied to an image display device. It has been found that an antiglare film that does not decrease can be obtained. The present invention has been completed based on such findings and further various studies.

That is, the antiglare film according to the present invention is an antiglare film in which a hard coat layer having a fine concavo-convex shape is laminated on at least one surface of a resin base film having a flat surface, The ratio n _r / n _f of the refractive index n _r of the hard coat layer to the refractive index n _f of the material film is 0.96 or less, and at the interface between the resin substrate film and the hard coat layer, the resin substrate Scattered light intensity T (0) in the normal direction of the hard coat layer when light is vertically incident from the film side, and scattered light intensity T (60) having an angle of 60 ° from the normal on the hard coat layer side The ratio T (60) / T (0) is 0.000001 or less.

  In the antiglare film of the present invention, the total haze is preferably 5% or more and 50% or less.

  The resin base film used for the antiglare film of the present invention preferably has a thickness of 20 μm to 100 μm, and the hard coat layer preferably has a thickness of 2 μm to 20 μm.

  The resin base film used for the antiglare film of the present invention is preferably composed of a polyethylene terephthalate resin.

  In the antiglare film of the present invention, when light is incident at an incident angle of 30 ° from the hard coat layer side, the reflectance R (30) at a reflection angle of 30 ° is 0.05% or more and 2% or less. The reflectance R (40) at a reflection angle of 40 ° is 0.0001% or more and 0.005% or less, and the reflectance R (50) at a reflection angle of 50 ° is 0.00001% or more and 0.0005% or less. It is preferable.

  The antiglare film of the present invention may further have a low reflection film on the surface of the hard coat layer having a fine uneven shape.

  Further, according to the present invention, there is provided an antiglare polarizing plate obtained by laminating any one of the above antiglare films and a polarizing film, wherein the polarizing film is not laminated with a hard coat layer of the antiglare film. An anti-glare polarizing plate is provided on the surface side.

  The antiglare film or antiglare polarizing plate of the present invention can be combined with an image display element such as a liquid crystal display element or a plasma display panel to form an image display device. That is, according to the present invention, the antiglare film according to any one of the above or the antiglare polarizing plate and an image display element are provided, and the antiglare film or the antiglare polarizing plate has a hard coat layer side. An image display device is provided that is disposed on the outside of the image display element on the viewing side.

  The anti-glare film of the present invention has excellent anti-glare performance, prevents deterioration of visibility due to whitening, and does not cause glare when placed on the surface of a high-definition image display device. Can exhibit high contrast. The anti-glare polarizing plate obtained by combining the anti-glare film of the present invention with a polarizing film (polarizer) also exhibits the same effect. And the image display apparatus which has arrange | positioned the anti-glare film or anti-glare polarizing plate of this invention has high anti-glare performance, is excellent in visibility, and the intensity | strength of a panel is reinforced and it can prevent the curvature of a panel. I can do it.

<Anti-glare film>
The antiglare film of the present invention has a structure in which a hard coat layer having a fine uneven shape is laminated on at least one surface of a resin base film having a flat surface. 1A and 1B are schematic cross-sectional views showing preferred examples of the antiglare film of the present invention. The anti-glare film 103a shown in FIG. 1A is a resin base film 101a having a flat surface and a resin base film having a fine uneven shape 105a laminated on the surface of the resin base film 101a. 101a includes a hard coat layer 102a having a different refractive index. The fine uneven shape 105a on the surface of the hard coat layer 102a is formed by the filler 104a dispersed in the hard coat layer 102a. In addition, the antiglare film 103b shown in FIG. 1B is a resin base film 101b having a flat surface and a resin base having a fine uneven shape 105b on the surface laminated on the surface of the resin base film 101b. The material film 101b includes a hard coat layer 102b having a different refractive index. The fine uneven shape 105b on the surface of the hard coat layer 102b is formed by an embossing method or the like, and no filler is present in the hard coat layer 102b. Here, the ratio n _r / n _f of the refractive index n _r of the hard coat layer to the refractive index n _f of the resin base film needs to be 0.96 or less. Furthermore, the scattered light intensity T (0) in the normal direction of the hard coat layer when the light is vertically incident from the resin base film side (side where the hard coat layer is not laminated), and the hard It is necessary that the ratio T (60) / T (0) of scattered light intensity T (60) whose angle from the normal line is 60 ° on the coating layer side is 0.000001 or less. In FIGS. 1A and 1B, the hard coat layer is formed only on one surface of the resin base film, but in the present invention, the hard coat layer is thus formed on one surface. It is not restricted only to the aspect currently formed only in this, The aspect in which the hard-coat layer was formed in the front and back both surfaces of the resin base film is also included. In the following, an embodiment in which the hard coat layer is formed on one surface of the resin base film in principle will be mainly described.

<Refractive index ratio>
First, it will be described that the ratio n _r / n _f between the refractive index n _r of the hard coat layer and the refractive index n _f of the resin base film is 0.96 or less. In an image display device, particularly a liquid crystal display device, the contrast is lowered due to light leakage from an oblique direction during black display, resulting in a narrow viewing angle and a loss of visibility. Such light leakage from the oblique direction can be effectively suppressed by setting the refractive index ratio n _r / n _f to 0.96 or less. That is, as shown in FIG. 2, when the light leaked from the oblique direction (that is, the incident light 204) enters the hard coat layer 202 from the resin base film 201, the incident light 204 from the film normal direction 207. When the angle ψ satisfies the following relational expression (1), the incident light 204 does not pass through the interface between the resin base film 201 and the hard coat layer 202 but is totally reflected. The film normal direction 207 is a direction perpendicular to the flat surface of the resin base film 201.

sinψ> n _r / n _f (1)
Here, FIG. 2 shows the case of sin ψ = n _r / n _f . When the incident angle ψ of the incident light 204 is sin ψ = n _r / n _f , the refraction angle φ of the transmitted light 205 to the hard coat layer 202 is 90 °. Therefore, when the incident angle ψ is larger than this, that is, when the relational expression (1) is satisfied, the incident light 204 does not pass through the interface between the resin base film and the hard coat layer, and is totally reflected. You can see (reflected light 206). As a result, when the refractive index ratio n _r / n _f is 0.96 or less, light whose angle from the normal direction of the film is about 74 ° or more causes total reflection and leaks to the image display device viewing side. The contrast is improved and the viewing angle is improved. Therefore, the refractive index ratio is preferably 0.96 or less, more preferably 0.93 or less. The lower limit of the refractive index ratio is not particularly limited. However, if the refractive index ratio is too small, the light transmittance is lowered, and the screen becomes dark when the antiglare film of the present invention is arranged in an image display device. Since there exists a tendency, it is preferable that it is 0.8 or more.

<Scattered light intensity>
Next, the antiglare film of the present invention is hard coated when light is incident vertically from the resin base film side of the antiglare film (the resin base film side at the interface between the resin base film and the hard coat layer). The ratio T (60) / T (0) between the scattered light intensity T (0) in the layer normal direction and the scattered light intensity T (60) at an angle of 60 ° from the normal on the hard coat layer side is It is necessary to show a value of 0.000001 or less. Hereinafter, the scattered light intensity T (0) in the normal direction of the hard coat layer side and the scattered light whose angle from the normal line on the hard coat layer side is 60 ° when light is incident vertically from the resin base film side The strength T (60) will be described. In addition, “perpendicular” when light is incident vertically from the substrate film side means that light is incident from the direction perpendicular to the flat surface of the resin substrate film, and overlaps with the normal line on the hard coat layer side. The direction.

  FIG. 3 shows that light is incident perpendicularly to the resin base film from the resin base film side of the antiglare film (the one where the hard coat layer is not laminated at the interface between the resin base film and the hard coat layer). , Scattered light intensity T (0) in the normal direction of the hard coat layer side (side having fine irregularities on the surface), and scattered light intensity T (60) in the direction of 60 ° from the normal direction of the hard coat layer side It is the perspective view which showed typically the incident direction of light when measuring, and a transmitted scattered light intensity | strength measurement direction. In FIG. 3, light 13 vertically incident from the resin base film side of the antiglare film 11 (the lower side of the antiglare film 11) (that is, the direction of the incident light 13 is a method on the hard coat layer side of the antiglare film). The intensity of the transmitted scattered light 14 transmitted in the normal direction 12 on the hard coat layer side is measured as T (0), and 60 to 60 from the normal direction 12 on the hard coat layer side. The intensity of the transmitted scattered light 15 transmitted in the direction of ° is measured and is defined as T (60). The transmitted scattered light 15, the normal direction 12, the light 13 incident from the resin base film side, and the transmitted scattered light 14 are all measured to be on the same plane (plane 19 in FIG. 3). The

And the ratio T (60) / T (0) of the scattered light intensity measured in this way needs to be 0.000001 or less. When the ratio T (60) / T (0) exceeds 0.000001, when this anti-glare film is applied to an image display device, the luminance at the time of black display is increased by scattered light, and the contrast is decreased. Therefore, it is not preferable. The antiglare film of the present invention suppresses light leakage from an oblique angle of the image display device by setting the refractive index ratio n _r / n _f to 0.96 or less, and wide-angle scattering is achieved by a ratio T (60 of scattered light intensity). ) / T (0) is controlled to 0.000001 or less. Therefore, when the antiglare film of the present invention is arranged in an image display device, a high contrast display can be obtained by these synergistic effects.

  The ratio T (60) / T (0) is more preferably 0.0000005 or less, and further preferably 0.0000003 or less.

  In measuring the ratio T (60) / T (0) of the scattered light intensity of the antiglare film, it is possible to accurately measure the ratio T (60) / T (0) of the scattered light intensity of 0.000001 or less. is necessary. Therefore, it is effective to use a detector with a wide dynamic range. As such a detector, for example, a commercially available optical power meter can be used, and an aperture is provided in front of the detector of the optical power meter so that the angle at which the antiglare film is expected is 2 °. Measurements can be made using a goniophotometer. Visible light of 380 to 780 nm can be used as incident light, and a collimated light emitted from a light source such as a halogen lamp may be used as a measurement light source, or parallelism with a monochromatic light source such as a laser. Higher ones may be used. Moreover, in order to prevent the curvature of a film, it is preferable to use it for a measurement, after sticking to a glass substrate so that the fine uneven surface of a hard-coat layer may become the surface using an optically transparent adhesive.

  In view of the above, the ratio T (60) / T (0) of the scattered light intensity defined in the present invention is measured as follows. The antiglare film is bonded to a glass substrate so that the fine uneven surface of the hard coat layer becomes the surface, and irradiated with parallel light from a He-Ne laser from the direction of the film normal on the glass surface side, The transmitted scattered light intensity at a predetermined angle from the film normal direction is measured on the fine uneven surface side of the hard coat layer of the antiglare film. For the measurement of transmitted scattered light intensity, “3292 03 Optical Power Sensor” and “3292 Optical Power Meter” manufactured by Yokogawa Electric Corporation are used for both T (0) and T (60).

  FIG. 4 is a diagram showing the relationship between the ratio of scattered light intensity T (60) / T (0) and contrast. As apparent from FIG. 4, when the ratio T (60) / T (0) of the scattered light intensity exceeds 0.000001, the contrast is decreased by 10% or more, and the visibility tends to be impaired. The contrast was measured by the following procedure. First, the polarizing plate on the back side and the display surface side is peeled off from a commercially available liquid crystal television (“LC-42GX1W” manufactured by Sharp Corporation), and instead of the original polarizing plate, A polarizing plate “Sumikaran SRDB31E” manufactured by Sumitomo Chemical Co., Ltd. is bonded via an adhesive so that each absorption axis coincides with the absorption axis of the original polarizing plate. For example, an anti-glare film showing various scattered light intensity ratios T (60) / T (0) was bonded via an adhesive so that the fine uneven shape would be the surface. Next, the liquid crystal television thus obtained was activated in a dark room, and using a luminance meter “BM5A” manufactured by Topcon Corporation, the luminance in the black display state and the white display state was measured, 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. The numerical value indicating the contrast on the vertical axis in FIG. 4 represents this ratio, and the higher the numerical value, the higher the contrast.

<All haze>
In the antiglare film of the present invention, the total haze of the antiglare film is preferably 5% or more and 50% or less. When the total haze of the antiglare film is less than 5%, the antiglare property is insufficient, or glare tends to occur when the antiglare film is placed on an image display device. Further, when the total haze exceeds 50%, whitening occurs or the contrast tends to be lowered when placed in an image display device, and the visibility tends to be lowered.

  In the antiglare film of the present invention, the total haze is measured as follows. That is, first, a hard coat layer is formed on one surface of a resin base film having a flat surface so that a fine uneven shape becomes the surface, and the resin base film side (side on which the hard coat layer is not formed) is The antiglare film and the glass substrate are bonded using a transparent adhesive so as to be a bonding surface. And all haze can be measured based on JISK7136 by using this bonding thing.

  The total haze of such an antiglare film is more preferably 40%, more preferably 30%, and the lower limit is 10%, more preferably 15%.

<Reflectance>
The antiglare film of the present invention has a reflectance R (30) at a reflection angle of 30 ° of 0.05% or more and 2% or less when light is incident from the hard coat layer side at an incident angle of 30 °. The reflectance R (40) at a reflection angle of 40 ° is 0.0001% or more and 0.005% or less, and the reflectance R (50) at a reflection angle of 50 ° is 0.00001% or more and 0.0005% or less. It is preferable. By making the reflectance R (30), the reflectance R (40) and the reflectance R (50) within the above ranges, the anti-glare is more effectively suppressed while showing excellent anti-glare performance. A film is provided.

  Here, the reflectance for each angle when light is incident at an incident angle of 30 ° from the hard coat layer side will be described. FIG. 5 is a perspective view schematically showing an incident direction and a reflection direction of light from the hard coat layer side with respect to the antiglare film when the reflectance is obtained. Referring to FIG. 5, the reflected light in the direction of the reflection angle of 30 °, that is, the regular reflection direction 506 with respect to the light 505 incident at an angle of 30 ° from the normal 502 on the hard coat layer side of the antiglare film 501. Let R (30) be the reflectance (that is, regular reflectance). Of the light 507 reflected at an arbitrary reflection angle θ, the reflectance of reflected light at θ = 40 ° and the reflectance of reflected light at θ = 50 ° are R (40) and R (50), respectively. . Note that the direction of reflected light when measuring the reflectance (the specular reflection direction 506 and the reflection direction of the light 507 reflected at the reflection angle θ) is within the plane 509 including the direction of the incident light 505 and the normal line 502. To do.

  When the regular reflectance R (30) exceeds 2%, a sufficient antiglare function cannot be obtained, and the visibility tends to decrease. On the other hand, even if the regular reflectance R (30) is too small, since it tends to cause whitening, it is preferably 0.05% or more. The regular reflectance R (30) is more preferably 1.5% or less, particularly 0.7% or less, and more preferably 0.1% or more, and particularly preferably 0.3% or more. On the other hand, if R (40) exceeds 0.005% or R (50) exceeds 0.0005%, the antiglare film is whitened and the visibility tends to be lowered. That is, for example, even when black is displayed on the display surface with an anti-glare film installed on the forefront of the display device, a whitish color occurs that picks up light from the surroundings and makes the display surface entirely white. There is a tendency. Therefore, it is preferable that R (40) and R (50) are not so large. On the other hand, R (40) is generally preferably 0.0001% or more, and R (50) is generally 0, since sufficient antiglare properties are not exhibited even if the reflectance at these angles is too small. It is preferably 0.0001% or more. R (40) is more preferably 0.0005% or more and 0.002% or less, and R (50) is more preferably 0.00005% or more and 0.0001% or less.

  FIG. 6 shows the reflection of the light 507 reflected at the reflection angle θ with respect to the light 505 incident at an angle of 30 ° from the normal 502 on the hard coat layer side of the antiglare film of the present invention (antiglare film 501 in FIG. 5). It is an example of the graph which plotted the relationship between angle (theta) and a reflectance (a reflectance is a logarithmic scale). Such a graph representing the relationship between the reflection angle and the reflectance, or the reflectance for each reflection angle read therefrom may be referred to as a reflection profile. As shown in this graph, the regular reflectance R (30) is a reflectance peak with respect to the light 505 incident at 30 °, and the reflectance tends to decrease as the angle deviates from the regular reflection direction. In the example of the reflection profile shown in FIG. 6, the regular reflectance R (30) is about 0.55%, R (40) is about 0.0003%, and R (50) is about 0.00004%. .

  In measuring the reflectance of the antiglare film, it is necessary to accurately measure a reflectance of 0.001% or less as with the scattered light intensity. Therefore, it is effective to use a detector with a wide dynamic range. As such a detector, for example, a commercially available optical power meter can be used, and an aperture is provided in front of the detector of the optical power meter so that the angle at which the antiglare film is expected is 2 °. Measurements can be made using a goniophotometer. As incident light, visible light of 380 to 780 nm can be used, and as a measurement light source, a collimated light emitted from a light source such as a halogen lamp may be used, or a monochromatic light source such as a laser is used in parallel. A high degree may be used. In the case of an antiglare film having a smooth and transparent back surface, reflection from the back surface of the antiglare film may affect the measured value. For example, the smooth surface of the antiglare film is adhered to a black acrylic resin plate with an adhesive or It is preferable that only the reflectance on the outermost surface of the antiglare film can be measured by optical adhesion using a liquid such as water or glycerin.

  In view of the above, the reflectances R (30), R (40) and R (50) defined in the present invention are measured as follows. Irradiate the parallel light from the He-Ne laser on the hard coat layer surface of the antiglare film (the surface having a fine uneven shape) from a direction inclined by 30 ° with respect to the film normal (normal line 502), The measurement is performed by changing the reflectance angle in the plane including the film normal and the light incident direction (that is, in the plane 509 including the normal 502 and the incident light 505). For the measurement of reflectance, both “3292 03 Optical Power Sensor” and “3292 Optical Power Meter” manufactured by Yokogawa Electric Corporation can be used.

<Resin base film>
As the resin constituting the resin base film of the present invention, a substantially optically transparent resin is used. Examples of such resins include acrylic resins such as triacetyl cellulose, polyethylene terephthalate, and polymethyl methacrylate, and thermoplastic resins such as polycarbonate and amorphous cyclic polyolefin using norbornene compounds as monomers. Among such resins, it is preferable to use a polyethylene terephthalate film having excellent transparency, weather resistance, mechanical strength, and high refractive index. In other words, the resin base film of the present invention is composed of a polyethylene terephthalate resin. It is preferred that

  Such a resin base film of the present invention preferably has a thickness of 20 μm to 100 μm, more preferably 30 μm to 50 μm. If the thickness is less than 20 μm, handling tends to be difficult, and if it exceeds 100 μm, the merit of thinning tends to be reduced.

The polyethylene terephthalate film used as the resin base film in the antiglare film of the present invention is preferably uniaxially stretched or biaxially stretched (hereinafter, such a uniaxially stretched or biaxially stretched polyethylene terephthalate film is simply referred to as “stretched”). Also referred to as “polyethylene terephthalate film”). The stretched polyethylene terephthalate film is a film excellent in mechanical properties, solvent resistance, scratch resistance, cost, etc., and the antiglare film using such a polyethylene terephthalate film as a resin base film is mechanical strength, etc. In addition, the thickness can be reduced. In addition, since the refractive index of the resin constituting the hard coat layer is often about 1.5 to 1.55 in general, the refractive index ratio n _r / n can be obtained by using a polyethylene terephthalate resin having a high refractive index. The requirement of the present invention that _f is 0.96 or less can be satisfied.

  Here, in the present invention, the polyethylene terephthalate resin constituting the polyethylene terephthalate film is composed of polyethylene terephthalate, and this polyethylene terephthalate means a resin in which 80 mol% or more of the repeating units are composed of ethylene terephthalate, A structural unit derived from a copolymerization component may be included. Other copolymer components include isophthalic acid, p-β-oxyethoxybenzoic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid Dicarboxylic acid components such as sebacic acid, 5-sodium sulfoisophthalic acid, 1,4-dicarboxycyclohexane; propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, bisphenol A ethylene oxide adduct, polyethylene glycol, Examples of the diol component include polypropylene glycol and polytetramethylene glycol. These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. It is also possible to use an oxycarboxylic acid such as p-oxybenzoic acid in combination with the carboxylic acid component or diol component. As another copolymer component, a dicarboxylic acid component and / or a diol component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used. That is, in this invention, even when it contains such other copolymerization component, it shall be described as polyethylene terephthalate.

  Polyethylene terephthalate can be produced by a direct polymerization method in which terephthalic acid and ethylene glycol (and other dicarboxylic acids and / or other diols as required) are directly reacted, dimethyl ester of terephthalic acid and ethylene glycol (and necessary) Depending on the above, any production method such as a so-called transesterification method in which a dimethyl ester of another dicarboxylic acid and / or another diol) is transesterified can be applied. Moreover, the polyethylene terephthalate may contain a well-known additive as needed. Known additives include, for example, lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents, impact resistance improvers and the like. However, since transparency is required as the base film of the antiglare film, it is preferable to keep the additive amount to a minimum.

  A stretched polyethylene terephthalate film can be produced by forming a raw material resin produced by the above-described production method into a film and performing a uniaxial stretching process or a biaxial stretching process. By performing the stretching treatment, a polyethylene terephthalate film having high mechanical strength can be obtained. The production method of the stretched polyethylene terephthalate film is arbitrary and is not particularly limited. For example, as the uniaxially stretched polyethylene terephthalate film, the raw material resin is melted and extruded into a sheet shape. A method of performing heat setting treatment after transverse stretching with a tenter at a temperature equal to or higher than the glass transition temperature can be mentioned. In addition, in a biaxially stretched polyethylene terephthalate film, a non-oriented film obtained by melting the raw material resin and extruding it into a sheet is longitudinally stretched with a tenter at a temperature equal to or higher than the glass transition temperature, and then subjected to a heat setting treatment. The method of performing a heat setting process after extending | stretching can be mentioned. In this case, the stretching temperature is 80 to 130 ° C., preferably 90 to 120 ° C., and the stretching ratio is 2.5 to 6 times, preferably 3 to 5.5 times. When the draw ratio is low, the polyethylene terephthalate film tends not to exhibit sufficient transparency.

  Moreover, in order to reduce the distortion of the orientation main axis, it is desirable to relax the polyethylene terephthalate film before the heat setting treatment after stretching. The temperature during the relaxation treatment is 90 to 200 ° C, preferably 120 to 180 ° C. The amount of relaxation varies depending on the stretching conditions, and it is preferable to set the amount of relaxation and the temperature during the relaxation treatment so that the heat shrinkage rate at 150 ° C. of the polyethylene terephthalate film after the relaxation treatment is 2% or less.

  The heat setting treatment temperature can be 180 to 250 ° C., preferably 200 to 245 ° C. In the heat setting process, it is preferable to perform a relaxation process in the width direction after the heat setting process is performed at a constant length and then the distortion of the orientation main axis is reduced and the strength such as heat resistance is improved. The amount of relaxation in this case is preferably adjusted such that the heat shrinkage rate at 150 ° C. of the polyethylene terephthalate film after the relaxation treatment is 1 to 10%, more preferably 2 to 5%. The maximum value of the orientation main axis strain of the stretched polyethylene terephthalate film used in the present invention is 10 degrees or less, preferably 8 degrees or less, and more preferably 5 degrees or less. When the maximum value of the orientation main axis is larger than 10 degrees, the coloring defect tends to increase when bonded to the liquid crystal display screen. In addition, the “maximum value of the distortion of the orientation main axis” of the stretched polyethylene terephthalate film can be measured, for example, by a retardation film inspection apparatus RETS system manufactured by Otsuka Electronics Co.

Such thickness d _PET of stretched polyethylene terephthalate film is preferably set to 20μm or 100μm or less, and more preferably to 30μm or 50μm or less. When the thickness d _PET of the stretched polyethylene terephthalate film is less than 20 μm, handling tends to be difficult, and when the thickness d _PET exceeds 100 μm, the merit of thinning tends to be reduced. The in-plane retardation value R _PET of the stretched polyethylene terephthalate film is preferably 1000 nm or more, and more preferably 3000 nm or more. When the in-plane retardation value R _PET is less than 1000 nm, coloring from the front tends to be conspicuous. The in-plane retardation value R _PET of the stretched polyethylene terephthalate film is represented by the following formula (2).

_{R PET = (n a -n b} ) × d PET ··· (2)
Here, n _a is the refractive index in the in-plane slow axis direction of the oriented polyethylene terephthalate film, the n _b is the refractive index in the in-plane fast axis direction (perpendicular to the plane slow axis direction).

  The surface of the resin base film needs to be flat in order to prevent light leakage from an oblique direction when it is used as an antiglare film. In order to flatten the surface of the resin base film, for example, a method of forming a film by bringing both surfaces of a film-like product obtained by melt extrusion into contact with the roll surface or the belt surface is preferable. In the roll or belt used at this time, the roll surface or the belt surface is preferably a mirror surface in order to impart smoothness to the film surface.

  In the present invention, in the case of a resin base film having a flat surface, “flat” means that the haze due to the surface shape of the resin base film (surface haze) is approximately 0%. The arithmetic average height Pa is 0.01 μm or less, preferably 0.005 μm or less, and the maximum cross-sectional height Pt is 0.1 μm or less, preferably 0.05 μm or less.

  Moreover, various easy-adhesion processes may be given to one side or both surfaces in the resin base film. The easy adhesion treatment is not particularly limited, and examples thereof include conventionally known treatments such as corona treatment, plasma treatment, flame treatment, primer treatment, and solvent treatment.

<Hard coat layer>
The hard coat layer having a fine concavo-convex shape on the surface formed on the antiglare film of the present invention is laminated on the surface of the resin base film and can be formed by a conventionally known method. Such a hard coat layer mainly functions as an antiglare layer, and preferably has the total haze described above as an antiglare film, and the total haze of such an antiglare film is (of the hard coat layer). ) It consists of surface haze and internal haze (of antiglare film). And since the surface haze of a hard-coat layer becomes the surface haze of an anti-glare film, it is preferable that they are 0.5% or more and 15% or less. When the surface haze exceeds 15%, it is not preferable because whitening occurs. In order to suppress whitening more effectively, the surface haze is preferably 5% or less. However, when it is less than 0.5%, it is not preferable because sufficient antiglare property is not exhibited. The internal haze of the antiglare film is preferably 4.5% or more and 35% or less. When the internal haze of the antiglare film is less than 4.5%, glare tends to occur when it is placed on the image display device, and when it exceeds 35%, the contrast when placed on the image display device Tend to decrease. A more preferable range of the internal haze is 9.5% or more and 25% or less.

  Here, the surface haze and internal haze of the antiglare film are measured as follows. That is, first, after forming the hard coat layer on the resin base film, the antiglare film and the glass substrate are pasted with a transparent adhesive so that the side on which the hard coat layer is not formed becomes the bonding surface. And 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 approximately 0 is bonded to the surface of the fine irregular shape of the hard coat layer using glycerin, and the haze is measured 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 can be obtained based on the following formula (3).

Surface haze = Total haze-Internal haze (3)
When a stretched polyethylene terephthalate film is used as the resin base film of the antiglare film of the present invention, the total haze (H%) and transmission clarity (Tc%) of the antiglare film are expressed by the following relational expression (4). It is preferable to satisfy. When the relational expression (4) is not satisfied, color unevenness due to the phase difference of the stretched polyethylene terephthalate film is observed when the antiglare film is disposed in the image display device. In the antiglare film of the present invention, the lower limit of the transmission clarity is not particularly limited from the viewpoint of suppressing color unevenness, but is preferably 30% or more from the viewpoint of the visibility of the image display device. In order to reduce the transmission sharpness of the antiglare film so as to satisfy the relational expression (4) of the present invention, it is known that, for example, the period of the fine irregularities on the surface of the hard coat layer may be increased. It has been.

Tc ≦ 8H (4)
Here, the transmission clarity (Tc%) of the antiglare film of the present invention is measured as follows. That is, on the stretched polyethylene terephthalate film which is a resin base film, a hard coat layer having a fine uneven shape is formed on the surface, and the surface on which the hard coat layer is not formed becomes a bonding surface. The laminated film (that is, the antiglare film) and the glass substrate are bonded using a transparent adhesive and measured by a method defined in JIS K 7105. In this standard, as an optical comb used for measurement of image definition, the ratio of the width of the dark part to the bright part is 1: 1, and the width is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. The type is specified. In the antiglare film defined in the present invention, the sum of image sharpness measured using these four types of optical combs is referred to as transmission sharpness. In this definition, the maximum value of the transmission definition is 400%.

  The method for producing a hard coat layer having fine irregularities on the surface of the present invention, including the case where the above optical characteristics are satisfied, is not particularly limited, and a conventionally known method can be used. For example, a method of forming random irregularities by applying a resin solution in which a filler is dispersed on a resin base film, adjusting the coating film thickness to expose the filler on the surface of the coating film, or disclosed in Patent Document 3 above The embossing method etc. which can be mentioned. In particular, when a hard coat layer satisfying the above optical characteristics is produced, by preparing such that the period of the fine irregularities on the surface is increased in any of these methods, the relational expression (4) A relationship can be achieved. Here, increasing the period of the fine concavo-convex shape means increasing the average length PSm in the cross-sectional curve of the fine concavo-convex shape, for example. The average length PSm at that time is preferably 20 μm or more and 100 μm or less.

  Here, the filler in the case of forming a hard coat layer by applying a resin solution in which a filler is dispersed on a resin base film is not particularly limited as long as it is translucent, and conventionally known particles are used. Can be used. For example, inorganic fine particles include calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide, zinc oxide, and other inorganic particles, and these inorganic particles with a fatty acid or the like surface. The thing which processed can be mentioned as a typical thing. The organic fine particles include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index 1.50 to 1.59). ), Polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polyvinyl chloride beads (refractive index 1.46), silicone resin beads (refractive index 1.46), etc. It can be cited as a typical one.

  Here, it is preferable to use silica-based fine particles (porous silica, agglomerated silica, spherical silica, etc.) or resin particles among the fillers described above in view of dispersibility, light transmittance, cost, and the like. When silica-based fine particles are used as the filler for forming the hard coat layer, the weight average particle diameter is 1 μm or more and 5 μm or less, and within the range of 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the translucent resin. It is preferably contained in the hard coat layer. When the weight average particle diameter is less than 1 μm, there is a tendency that sufficient anti-glare properties are not exhibited. When the weight average particle diameter is 5 μm or more, the surface haze increases, and as a result, the anti-glare film becomes white and visible. Tend to decrease. Further, when the addition amount of the silica-based fine particles is 1 part by weight or less, there is a tendency that the sufficient anti-glare property is not exhibited or the surface unevenness is sparse and the texture is deteriorated. As a result, the surface haze increases, and as a result, the antiglare film tends to become white and the visibility tends to decrease. Further, the thickness of the hard coat layer can be appropriately adjusted so as to obtain a required surface haze, but in general, it is preferably 85% or more, more preferably 100% with respect to the weight average particle diameter. % Or more. When the film thickness of the hard coat layer is less than 85% of the weight average particle diameter of the particles, the surface haze increases, and as a result, the antiglare film tends to be white and visibility tends to decrease. On the other hand, the upper limit of the thickness of the hard coat layer in this case is not particularly limited from the viewpoint of surface haze, but if it is too thick, it tends to break or the film curls due to curing shrinkage of the antiglare layer, and the productivity decreases. Therefore, it is preferably 20 μm or less. The thickness of the hard coat layer of the present invention thus prepared is more preferably 2 μm or more and 20 μm or less, and more preferably 4 μm or more and 12 μm or less.

  When resin particles are used as the filler (transparent fine particles) forming the hard coat layer, the weight average particle diameter is 2 μm or more and 10 μm or less, and 1 part by weight or more and 40 parts by weight with respect to 100 parts by weight of the light transmissive resin It is preferable to contain in a hard-coat layer within the range below a part. When the weight average particle diameter is less than 2 μm, there is a tendency that sufficient anti-glare properties are not exhibited. When the weight average particle diameter exceeds 10 μm, the surface haze increases, and as a result, the anti-glare film becomes white and is visible. Tends to decrease. Moreover, when the addition amount of the resin particles is less than 1 part by weight, there is a tendency that the antiglare property is not sufficient or the surface unevenness is sparse and the texture is lowered, and when it exceeds 40 parts by weight, The total haze (total of surface haze and internal haze) increases, and as a result, when applied to an image display device, the screen becomes dark and visibility tends to be impaired. Further, the thickness of the hard coat layer can be appropriately adjusted so as to obtain the required surface haze, but in general, it is preferably 85% or more with respect to the weight average particle diameter as described above. More preferably, it is 100% or more. When the film thickness of the hard coat layer is less than 85% of the weight average particle diameter of the particles, the surface haze increases, and as a result, the antiglare film tends to be white and visibility tends to decrease. On the other hand, the upper limit of the thickness of the hard coat layer in this case is not particularly limited from the viewpoint of surface haze, but if it is too thick, it tends to crack or the film curls due to curing shrinkage of the antiglare layer, and the productivity decreases. Therefore, it is preferably 20 μm or less.

  As the resin for dispersing the filler as described above, an ultraviolet curable resin, a thermosetting resin, an electron beam curable resin, or the like can be used, but an ultraviolet curable resin is preferably used from the viewpoint of productivity, hardness, and the like. Is done. A commercially available product can be used as the ultraviolet curable resin. For example, one or more polyfunctional acrylates such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate, and “Irgacure 907”, “Irgacure 184” (above, manufactured by Ciba Specialty Chemicals), “ A mixture with a photopolymerization initiator such as “Lucirin TPO” (manufactured by BASF) can be used as an ultraviolet curable resin. For example, when an ultraviolet curable resin is used, after the filler is dispersed in the ultraviolet curable resin, the resin composition is applied to a resin base film and irradiated with ultraviolet rays, whereby the resin (also referred to as a hard coat resin). ), A hard coat layer in which a filler is dispersed can be formed.

  In addition, when a hard coat layer having a fine uneven shape is formed by an embossing method (usually a hard coat layer is formed only with a resin not containing a filler), as disclosed in the above-mentioned Patent Document 3 etc. The mold shape may be transferred to a transparent resin film using a mold having a fine uneven shape. Transfer onto the mold-shaped film is preferably carried out by embossing, and UV embossing using an ultraviolet curable resin is preferred as embossing.

  In the UV embossing method, a UV curable resin layer is formed on the surface of a resin base film, and the UV curable resin layer is cured while being pressed against the rugged surface of the mold. Transferred to the resin layer. Specifically, an ultraviolet curable resin is applied on the resin base film, and the applied UV curable resin is adhered to the uneven surface of the mold, and ultraviolet rays are irradiated from the resin base film side. Then, the ultraviolet curable resin is cured, and then the shape of the mold is transferred to the ultraviolet curable resin by peeling the resin base film on which the cured ultraviolet curable resin layer is formed from the mold. The kind of ultraviolet curable resin is not particularly limited. Further, instead of the ultraviolet curable resin, a visible light curable resin that can be cured with visible light having a wavelength longer than that of ultraviolet light may be used by appropriately selecting a photoinitiator.

  Even when the hard coat layer is formed using the UV embossing method, a filler may be dispersed in the resin (hard coat resin) in order to impart internal haze. In order to impart internal haze, it is preferable to use resin particles having a refractive index different from that of the resin, and the resin particles may be selected from the above-described resin particles. The resin particles in that case also have a weight average particle diameter of 2 μm or more and 10 μm or less, and are contained in the hard coat layer within a range of 1 part by weight or more and 40 parts by weight or less with respect to 100 parts by weight of the translucent resin. Is preferred. When the weight average particle diameter is less than 2 μm, wide-angle scattering of transmitted light increases, and the antiglare film tends to become whitish as a whole, resulting in a decrease in contrast. There is a tendency not to be obtained. Moreover, when the addition amount of the resin particles is less than 1 part by weight, there is a tendency that sufficient internal scattering is not obtained, and when it exceeds 40 parts by weight, the total haze (total of surface haze and internal haze) As a result, when applied to an image display device, the screen becomes dark and visibility tends to be impaired.

  The thickness of such a hard coat layer is not particularly limited, but is preferably 2 μm or more and 20 μm or less as described above. If the thickness of the hard coat layer is less than 2 μm, sufficient hardness cannot be obtained and tends to be easily scratched. If the thickness is greater than 20 μm, the film tends to break or the film curls due to curing shrinkage of the hard coat layer. As a result, productivity tends to decrease.

  Note that the fine uneven shape imparted to the surface of the hard coat layer of the present invention means that, in the cross-sectional curve of the uneven shape, the arithmetic average height Pa is 0.05 μm or more and 0.3 μm or less, and the maximum cross-sectional height is Pt is preferably 0.2 μm or more and 2 μm or less. When the arithmetic average height Pa is less than 0.05 μm, it is not preferable because sufficient antiglare property as an antiglare film is not exhibited. Moreover, when arithmetic average height Pa exceeds 0.3 micrometer, the surface haze of an anti-glare film becomes large, and when it applies to an image display device, it will become whitish and visibility tends to be impaired. A case where the maximum cross-sectional height Pt is less than 0.2 μm is not preferable because a sufficient anti-glare property is not exhibited when an anti-glare film is produced. In addition, when the maximum cross-sectional height Pt exceeds 2 μm, the surface haze of the antiglare film increases, and when applied to an image display device, whitening occurs and visibility tends to be impaired. In addition, the thickness of the hard coat layer in the present invention means a case where the highest portion of the fine concavo-convex convex portions is measured.

<Low reflective film>
The antiglare film of the present invention may have a low reflection film on the outermost surface thereof, that is, on the surface of the fine uneven shape of the hard coat layer. Even in the absence of a low reflection film, a sufficient antiglare function is exhibited, but the antiglare property can be further improved by providing a low reflection film on the outermost surface. The low reflection film can be formed by providing a layer of a low refractive index material having a lower refractive index on the hard coat layer. Specific examples of such a low refractive index material include lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), cryolite (3NaF · AlF ₃ or Na ₃ AlF _6). ) And other inorganic low-reflective materials containing acrylic resin, epoxy resin, etc .; fluorine-based or silicone-based organic compounds, thermoplastic resins, thermosetting resins, UV-curable resins, etc. An organic low reflection material can be mentioned.

  The thickness of such a low reflection film is 0.01 μm or more and 0.2 μm or less, more preferably 0.08 μm or more and 0.12 μm or less.

<Anti-glare polarizing plate>
The anti-glare film of the present invention has high anti-glare performance and excellent visibility, and the panel strength is reinforced and the panel can be prevented from warping. Excellent mechanical strength. When the image display device is a liquid crystal display, this antiglare film can be applied to the polarizing plate. In other words, in general, there are many polarizing plates in which a protective film is bonded to at least one surface of a polarizing film made of a polyvinyl alcohol-based resin film adsorbed and oriented with iodine or a dichroic dye. The antiglare film of the present invention is used. That is, the anti-glare polarizing plate of the present invention is formed by laminating an anti-glare film and a polarizing film, and the polarizing film is one in which the hard coat layer of the anti-glare film is not laminated. It is arranged on the surface side. In this case, the other surface of the polarizing film may be in a state where nothing is laminated, another protective film or an optical film may be laminated, and an adhesive layer for bonding to a liquid crystal cell. May be formed. In addition, the antiglare film of the present invention is bonded to the surface opposite to the surface on which the hard coat layer is formed on the protective film of the polarizing plate in which the protective film is bonded to at least one surface of the polarizing film. And it can also be set as an anti-glare polarizing plate. Furthermore, in the polarizing plate having a protective film bonded to at least one side, after bonding the resin base film to the polarizing film as the protective film, by forming the hard coat layer on the resin base film, It can also be set as an anti-glare polarizing plate.

  As described above, in the antiglare polarizing plate of the present invention, the polarizing film and the antiglare film are in direct contact with each other as long as the polarizing film is disposed on the side of the antiglare film on which the hard coat layer is not laminated. Thus, an aspect in which the polarizing film and the antiglare film are bonded together through another film is included.

<Image display device>
The image display device of the present invention comprises the antiglare film or antiglare polarizing plate of the present invention and an image display element. Here, the image display element is typically a liquid crystal panel that includes a liquid crystal cell in which liquid crystal is sealed between upper and lower substrates and displays an image by changing the alignment state of the liquid crystal by applying a voltage. The antiglare film or the antiglare polarizing plate of the present invention can also be applied to various known displays such as a display panel, a CRT display, and an organic EL display. In the image display device of the present invention, the antiglare film or the antiglare polarizing plate is disposed on the visual recognition side with respect to the image display element with the hard coat layer side facing outside. Under the present circumstances, it arrange | positions so that the uneven surface of an anti-glare film, ie, a hard-coat layer side, may become an outer side (viewing side). The antiglare film may be directly bonded to the surface of the image display element. When the liquid crystal panel is used as the image display means, for example, as described above, the antiglare film is bonded to the surface of the liquid crystal panel via the polarizing film. You can also. Thus, the image display device provided with the antiglare film of the present invention can scatter incident light due to the unevenness of the surface of the antiglare film and blur the reflected image, giving excellent visibility.

  In addition, when the antiglare film of the present invention is applied to an image display device, the strength of the panel is reinforced more than when a conventional antiglare film is used, and the warpage of the panel can be prevented. Further, color unevenness when observed from an oblique direction due to the retardation of the stretched polyethylene terephthalate film is not observed.

  EXAMPLES Hereinafter, the present invention will be described more specifically 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 anti-glare film in the following examples is as follows.

(1) Measurement of optical properties of antiglare film (1-1) Haze The total haze of the antiglare film is the surface opposite to the hard coat layer forming surface using an optically transparent adhesive. The anti-glare film bonded to the glass substrate was measured using a haze meter “HM-150” manufactured by Murakami Color Research Laboratory in accordance with JIS K 7136. . Further, the internal haze was measured in accordance with JIS K 7136 again by laminating a triacetyl cellulose film having a haze of almost 0 on the fine irregular surface of the hard coat layer using glycerin. The surface haze was calculated based on the above formula (3).

(1-2) Scattered light intensity ratio T (60) / T (0)
The antiglare film is bonded to a glass substrate so that the fine uneven surface is the surface, and the glass surface side is irradiated with parallel light from a He—Ne laser perpendicular to the antiglare film to prevent the antiglare film. The transmitted scattered light intensity (T (0)) in the normal direction of the film and the transmitted scattered light intensity (T (60)) at 60 ° from the normal direction were measured on the fine uneven surface side of the glare film. For the measurement of transmitted scattered light intensity, “3292 03 Optical Power Sensor” and “3292 Optical Power Meter” manufactured by Yokogawa Electric Corporation were used.

(1-3) Transmission Visibility The transmission clarity of the anti-glare film was measured using an image clarity measuring device “ICM-1DP” manufactured by Suga Test Instruments Co., Ltd. based on JIS K 7105. In this case as well, 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 hard coat layer would be 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%.

(1-4) Reflection profile The film normal line is irradiated with parallel light from a He-Ne laser on the fine irregular surface of the hard coat layer of the antiglare film from a direction inclined by 30 ° with respect to the film normal line. And the angle change of the reflectance in a plane including the irradiation direction (direction of incident light) was measured. In the measurement of reflectance, both “3292 03 optical power sensor” and “3292 optical power meter” manufactured by Yokogawa Electric Corporation were used.

(2) Evaluation of anti-glare performance of anti-glare film (2-1) Evaluation of reflection and whitish Reflection from the back surface of the anti-glare film (surface opposite to the fine uneven surface of the hard coat layer) In order to prevent this, the anti-glare film is bonded to the black acrylic resin plate so that the fine uneven surface of the hard coat layer is the surface, and the fine uneven shape of the hard coat layer is in a bright room with a fluorescent lamp. Visual observation was performed from the surface side, and the presence or absence of reflection of a fluorescent lamp and the degree of whitening were visually evaluated. Reflection and whitishness were evaluated according to the following criteria in three stages of 1 to 3, respectively (the evaluation was an average value of three observers).
(A) Reflection; 1: Reflection is not observed. 2: Reflection is slightly observed. 3: Reflection is clearly observed.
(B) Whiteness; 1: Whiteness is not observed. 2: A little whitish is observed. 3: The whitish is clearly observed.

<Example 1>
(A) Production of antiglare film An ultraviolet curable resin composition in which the following components were dissolved in ethyl acetate at a solid content concentration of 60% was prepared.

Pentaerythritol triacrylate 60 parts Multifunctional urethanated acrylate 40 parts (Reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate)
Next, with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition, 3 porous silica particles “Silicia” (trade name, manufactured by Fuji Silysia Chemical Co., Ltd.) having a weight average particle diameter of 2.7 μm are used. 2 parts by weight of a photopolymerization initiator “Lucillin TPO” (manufactured by BASF, chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) was added to prepare a coating solution. The refractive index of the cured product of this ultraviolet curable resin composition (that is, the refractive index n _r of the hard coat layer) was 1.53.

This coating solution was a uniaxially stretched polyethylene terephthalate film (thickness: 40 μm, refractive index n _f : 1.66, surface haze: 0%, arithmetic average height Pa: 0.0053 μm, which is a resin base film, both surfaces being flat. The maximum cross-sectional height (Pt: 0.056 μm) was applied so that the coating thickness after drying was 3 μm, and dried in a drier set at 80 ° C. for 1 minute. The UV-curable resin composition is irradiated with light from a high-pressure mercury lamp having an intensity of 20 mW / cm ² from the side of the UV-curable resin composition layer of the dried film so that the amount of light converted to h-ray is 300 mJ / cm ² . The hard coat layer (cured resin) having a fine uneven shape on the surface by curing the layer is replaced with one of the resin base film (uniaxially stretched polyethylene terephthalate film; referred to as uniaxially stretched PET in Table 1) having a flat surface. An antiglare film laminated on the surface was obtained. The thickness of the hard coat layer of the antiglare film thus obtained was measured and found to be 2.7 μm. In addition, the thickness of the hard coat layer in the present invention is to measure the highest portion of the fine concavo-convex convex portions. Table 1 shows the arithmetic average height Pa and the maximum cross-sectional height Pt of the fine irregularities on the surface of the hard coat layer. In this antiglare film, the ratio n _r / n _f of the refractive index n _r of the hard coat layer to the refractive index n _f of the resin base film is 0.92.

  Other optical property evaluation results are shown in Table 2. The breakdown of the transmission clarity of the antiglare film of Example 1 shown in Table 2 is as follows.

Transmission clarity
0.125 mm optical comb: 54.5%
0.5mm optical comb: 62.3%
1.0mm optical comb: 82.8%
2.0mm optical comb: 94.5%
Total 294.1%
<Example 2 and Example 3>
An anti-glare film was produced in the same manner as in Example 1 except that the weight part and thickness of the filler (porous silica particles, simply indicated as “silica” in Table 1) dispersed in the coating solution were changed as shown in Table 1. The optical properties were evaluated. The refractive index ratio n _r / n _f and the optical property evaluation results are shown in Table 2.

<Comparative Example 1>
The weight part and thickness of the filler (porous silica particles, simply expressed as “silica” in Table 1) dispersed in the coating solution are changed as shown in Table 1, and a triacetyl cellulose film (thickness 80 μm) is used as the resin base film. The refractive index n _{f is} 1.49, the surface haze is 0%, the arithmetic average height Pa is 0.0047 μm, the maximum cross-sectional height Pt is 0.029 μm; The antiglare film was produced in the same manner as in Example 1, and the optical characteristics were evaluated. The refractive index ratio n _r / n _f and the optical property evaluation results are shown in Table 2.

The antiglare film of the present invention exhibits excellent antiglare performance, has high mechanical strength, and suppresses scattering on the wide angle side which causes a decrease in contrast and a decrease in viewing angle. Therefore, good visibility is provided when it is arranged in the image display device. On the other hand, in Comparative Example 1 in which the refractive index ratio n _r / n _f exceeds 1, the scattering on the wide-angle side exceeds the requirements of the present invention, and the contrast tends to decrease.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  By disposing the antiglare film of the present invention on various displays such as a liquid crystal panel, a plasma display panel, a CRT display, and an organic EL display so that the antiglare film is closer to the viewing side than the image display element. It is possible to blur the reflected image without generating a blur and to give excellent visibility. Further, since the mechanical strength is high, the warp of the panel can be effectively suppressed.

It is a cross-sectional schematic diagram which shows the preferable example of the anti-glare film of this invention, Comprising: (a) shows a case where a hard-coat layer contains a filler and (b) a hard-coat layer does not contain a filler. It is a schematic diagram which shows the total reflection in the interface of a resin base film and a hard-coat layer. The incident direction of light when light is incident perpendicular to the resin base film of the antiglare film and the scattered light intensity measured at 60 ° from the normal direction and the normal direction of the hard coat layer side It is a perspective view which shows typically the transmitted scattered light intensity | strength measurement direction. It is a figure which shows the relationship between ratio T (60) / T (0) of scattered light intensity, and contrast. It is a perspective view which shows typically the incident direction and reflection direction of the light from the hard-coat layer side when calculating | requiring a reflectance. It is an example of the graph which plotted the relationship between the reflection angle of the reflected light with respect to the light which injected at the angle of 30 degrees from the normal line of the anti-glare film of this invention, and a reflectance (a reflectance is a logarithmic scale).

Explanation of symbols

  11, 103a, 103b, 203, 501 Anti-glare film, 12 normal direction, 13, 505 Incident light, 14, 15 Transmitted scattered light, 19, 509 plane, 101a, 102b, 201 Resin base film, 102a, 102b , 202 Hard coat layer, 104a filler, 105a, 105b Fine irregular shape, 204 incident light, 205 transmitted light, 206 reflected light, 207 film normal direction, 502 normal, 506 regular reflection direction, 507 reflected light.

Claims (8)

An anti-glare film in which a hard coat layer having a fine uneven shape is laminated on at least one surface of a resin base film having a flat surface,
The ratio n _r / n _f of the refractive index n _r of the hard coat layer to the refractive index n _f of the resin base film is 0.96 or less,
Scattered light intensity T (0) in the normal direction of the hard coat layer side when light is incident vertically from the base resin film side at the interface between the resin base film and the hard coat layer, and the hard An anti-glare film characterized in that the ratio T (60) / T (0) of scattered light intensity T (60) at an angle from the normal of 60 ° on the coating layer side is 0.000001 or less.   The anti-glare film according to claim 1, wherein the total haze of the anti-glare film is 5% or more and 50% or less.   The antiglare film according to claim 1, wherein the resin base film has a thickness of 20 μm to 100 μm, and the hard coat layer has a thickness of 2 μm to 20 μm.   The anti-glare film according to any one of claims 1 to 3, wherein the resin base film is made of a polyethylene terephthalate resin. When light is incident at an incident angle of 30 ° from the hard coat layer side,
The reflectance R (30) at a reflection angle of 30 ° is 0.05% or more and 2% or less,
The reflectance R (40) at a reflection angle of 40 ° is 0.0001% or more and 0.005% or less,
The antiglare film according to any one of claims 1 to 4, wherein a reflectance R (50) at a reflection angle of 50 ° is 0.00001% or more and 0.0005% or less.   The antiglare film according to any one of claims 1 to 5, further comprising a low-reflection film on the surface of the hard coat layer having a fine uneven shape. An antiglare polarizing plate formed by laminating the antiglare film according to any one of claims 1 to 6 and a polarizing film,
The polarizing film is an antiglare polarizing plate disposed on the side of the antiglare film on which the hard coat layer is not laminated. An anti-glare film according to claim 1 or an anti-glare polarizing plate according to claim 7, and an image display device comprising an image display element,
The antiglare film or the antiglare polarizing plate is an image display device arranged on the viewing side of the image display element with the hard coat layer side facing outside.

Images