JP2010128256A - Method of manufacturing optical sheet and the optical sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which antidazzle properties are evaluated simply, and to provide an optical sheet which is high in antidazzle properties is efficiently manufactured. <P>SOLUTION: In the method of manufacturing the optical sheet, having a functional layer at least on one surface of a transparent base material and a diffusion element in the outermost surface and/or the inside, the manufacturing condition is controlled so as to have the relations formula (I) and (II): where (I) is 1.40<γ-α and (II) is 0.90<γ-β, where (α) expresses a diffusion angle where the diffusion intensity is 1/2 of the diffusion intensity, determined by extrapolating a straight line made by connecting a reflection intensity at ±2° to the reflection intensity at ±1° reflected intensity to the diffuse regular reflecting direction to the diffuse regular reflection angle; (β) expresses a diffusion angle, where the diffusion intensity is 1/3 of the diffusion intensity determined by extrapolating a straight line made by connecting a reflection intensity at ±2° to the reflection intensity at ±1° reflection intensity to the diffuse regular reflecting direction to the diffuse regular reflection angle, and (γ) expresses a diffusion angle where the diffusion intensity is 1/10 of the diffusion intensity determined by extrapolating a straight line, made by connecting a reflection intensity at ±2° to the reflection intensity at ±1° reflection intensity to the diffuse regular reflecting direction to the diffuse regular reflection angle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing an optical sheet having excellent antiglare properties and an optical sheet obtained by the method.

  As an optical sheet used on the surface of a display device, one in which a functional layer having an antiglare property is laminated on an observer-side surface of a substrate is known. In order to impart such antiglare properties, methods such as imparting a concavo-convex shape to the surface layer or adding diffusing particles to the resin forming the surface layer are taken. Since such diffusing particles are not completely compatible with the resin forming the surface layer, the optical sheet using them has an action of diffusing visible light. The unevenness of the surface layer also has the effect of diffusing visible light.

  In the present invention, what causes the diffusion of visible light as described above is defined as a diffusing element, and the antiglare property is imparted by such a diffusing element. Conventionally, as a method for evaluating the antiglare property, a haze value or a ratio of internal haze to total haze has been generally used. That is, it has been considered that an optical sheet having antiglare properties as desired can be manufactured by controlling the haze value in the manufacturing process of the optical sheet (see Patent Documents 1 to 3).

JP 2002-267818 A JP 2007-334294 A JP 2007-17626 A

However, even when the haze value is the same, the antiglare property is often different, and in the production using the haze value and the ratio between the internal haze and the total haze as an index, it is not always possible to stably produce a good optical sheet. I understood it.
Under such circumstances, an object of the present invention is to provide a production method for stably supplying an optical sheet having high antiglare property and an optical sheet having high antiglare property.

Until now, it has been considered that the antiglare property depends on the haze value. According to JIS K7136: 2000 and ISO 14782: 1999, the haze value is “percentage of transmitted light that has passed through the specimen by 0.044 rad (2.5 degrees) or more from the incident light due to forward scattering. Is defined. That is, the haze value indicates the ratio of scattered light in which incident light is scattered by ± 2.5 degrees or more, and the luminance distribution due to diffusion is not considered at all. In an extreme example, an optical sheet that completely reflects specularly (no diffusion) and no specular reflection, but both optical sheets that diffuse all transmitted light within ± 2.5 degrees have a haze value of 0 It will be.
On the other hand, for example, the optical sheet in which the amount of transmitted light within ± 2.5 degrees is 30% and the transmitted light is scattered to an angle of 70 to 80 degrees, and the amount of transmitted light within ± 2.5 degrees are the same. The optical sheets that scatter the transmitted light at an angle of 5 to 10 degrees at 30% both have a haze value of 70%.

FIG. 1 shows the relationship between the haze value and the antiglare property, and FIG. 2 shows the result of verifying the relationship between the ratio of the internal haze and the total haze and the antiglare property by preparing optical sheets having various conditions. As shown in FIG. 1 and FIG. 2, it can be seen that there are optical sheets with completely different anti-glare properties as an observer's evaluation even though they have the same haze value and ratio of internal haze to total haze.
As a result of intensive studies based on these findings, the present inventors have found that by adding the concept of luminance distribution by diffusion, it is possible to easily evaluate anti-glare properties that could not be evaluated with conventional haze values. It was. More specifically, the intensity that is 1/2 of the diffusion intensity obtained by extrapolating the straight line connecting the reflection intensity at ± 2 degrees and the reflection intensity at ± 1 degree to the diffuse regular reflection direction to the diffuse regular reflection angle is When the diffusion angle shown is α, the diffusion angle showing the intensity of 1/3 is β, and the diffusion angle showing the intensity of 1/10 is γ, γ-α and / or γ-β is used as an index, It is possible to easily evaluate the antiglare property, and in the process of manufacturing the optical sheet, using this as an index, by controlling the specification of the material, production conditions, etc., an optical sheet with high antiglare property can be efficiently obtained, and It has been found that it can be produced stably. The present invention has been completed based on these findings.

That is, the present invention is a method for producing an optical sheet having a functional layer on at least one surface of a transparent substrate and having a diffusing element on the outermost surface and / or inside of the functional layer, which has the following formula (I) In addition, the present invention provides a method for producing an optical sheet for use on the surface of a display element, wherein production conditions are controlled so as to have a relationship of (II).
1.40 <γ-α (I)
0.90 <γ-β (II)
α: Diffusion angle β indicating a half of the diffusion intensity obtained by extrapolating the straight line connecting the reflection intensity at ± 2 degrees and the reflection intensity at ± 1 degree to the diffuse regular reflection direction to the diffuse regular reflection angle A diffusion angle γ indicating the intensity of 1/3 of the diffusion intensity obtained by extrapolating a straight line connecting the reflection intensity at ± 2 degrees and the reflection intensity at ± 1 degree to the diffuse regular reflection direction; Diffusion angle indicating 1/10 of the diffusion intensity obtained by extrapolating the straight line connecting the reflection intensity at ± 2 degrees and the reflection intensity at ± 1 degree to the diffuse regular reflection direction to the diffuse regular reflection angle

  ADVANTAGE OF THE INVENTION According to this invention, the evaluation of anti-glare which was not able to be evaluated with the conventional haze value can be performed simply, and the method of manufacturing an optical sheet with high anti-glare can be provided efficiently.

The method for producing an optical sheet of the present invention is a method for producing an optical sheet used on a display element surface having a functional layer on at least one surface of a transparent substrate and having a diffusing element on the outermost surface and / or inside of the functional layer. The manufacturing conditions are controlled so as to satisfy the relationship of 1.40 <γ-α and / or 0.90 <γ-β.
Hereafter, the calculation method of (alpha), (beta), and (gamma) is demonstrated using FIGS.

(Calculation method of α, β and γ)
As shown in FIG. 3, when the optical sheet 1 is irradiated with visible light from the direction 4, the light is diffusely specularly reflected in the direction 5 and part of the light is diffused. In the present invention, the reflection intensity R2 in the direction of ± 2 degrees with respect to the diffuse regular reflection direction (when θ in FIG. 3 is 2 degrees) and the direction of ± 1 degree with respect to the diffuse regular reflection direction (in FIG. 3) The reflection intensity R1 when θ is 1 degree) is measured, and 1 of the diffusion intensity (hereinafter referred to as “virtual regular reflection diffusion intensity”) obtained by extrapolating the straight line connecting R2 and R1 to the diffuse regular reflection angle. The angle indicating the intensity of / 2 is defined as α, the diffusion angle indicating the intensity of 1/3 is defined as β, and the diffusion angle indicating the intensity of 1/10 is defined as γ (see FIGS. 4 to 6). As will be described later, a visible light absorbing material 8 such as a black acrylic plate is attached to the back surface of the base material 2 with an adhesive in order to suppress back surface reflection and match the conditions during actual use. .

Then, in the process of manufacturing the optical sheet, it is possible to efficiently manufacture an optical sheet having excellent antiglare property by performing selection of materials, control of manufacturing conditions, etc. using α, β and γ as indices. is there.
Specifically, the diffuse reflection intensity is measured as follows.

(Measurement method of diffuse reflection intensity)
A sample for evaluation is prepared by attaching the back surface of the optical sheet (the surface having no surface layer, the surface opposite to the viewer side) to a flat black acrylic plate having no irregularities or warping through a transparent adhesive. . In addition, the black acrylic board used here is for preventing back surface reflection as described above, so that it does not have an air layer on the back surface of the optical sheet and can absorb visible light. There is no particular limitation. For example, when measuring in a production line, it is also possible to measure online by a method such as applying a black paint to the back surface of the inspection portion of the optical sheet.
Next, the evaluation sample is installed in a measuring apparatus, and a light beam is incident on the optical sheet side surface of the evaluation sample at an angle of 45 degrees from the normal of the surface. Diffuse reflection in a certain range, for example, in the range of −85 degrees to 85 degrees with respect to the normal direction of the surface of the optical sheet 1 with respect to light that is incident on the optical sheet surface of the evaluation sample and diffusely reflected. Measure strength. Of these, the reflection intensity in the direction of ± 1 degree with respect to the diffuse regular reflection direction and the reflection intensity in the direction of ± 2 degrees with respect to the diffuse regular reflection direction are calculated as described above. Used for. When the diffusion is small, the measurement range may be narrowed to such an extent that it does not greatly contribute to the diffuse reflection intensity result in order to shorten the time. Although there is no restriction | limiting in particular about the apparatus which measures a diffuse reflection intensity, In this invention, Nippon Denshoku Industries Co., Ltd. product "GC5000L" was used.

Next, the reason why the value of γ-α and / or γ-β in the optical sheet determines the antiglare property will be described.
The antiglare property needs to be able to recognize the diffusion, and it is necessary to increase the diffusion up to γ which is the range of diffusion that can contribute to the antiglare property. Here, as schematically shown in FIG. 7, when the diffusion layer b is added to the transparent base material a that shows only regular reflection without diffusion, the characteristics of the optical sheet c are exhibited. Here, since α <β <γ, the decrease in regular reflection intensity with respect to changes in α, β, and γ is α << β << γ, and the change in γ is the largest, which decreases the regular reflection intensity. That is, in terms of diffusion and antiglare property due to the diffusing element, it is more preferable to increase γ in order to improve the antiglare property.

Further, in the optical sheet, there is regular reflection (r) due to the portion (r) having the reflection intensity only in the regular reflection direction, in addition to the regular reflection due to the portion (R) having the diffusing element. That is, in a normal optical sheet, specular reflection is observed as the sum of r and R, so it cannot be determined whether the diffusion intensity in the vicinity of specular reflection changes rapidly or slowly. Here, FIG. 8 schematically shows an example in which the ratio of r and R is the same and the diffusion intensity characteristics of the diffusion elements are different. Since the (B) characteristic in this schematic diagram has a higher intensity (5 or more in the example of FIG. 8) in the range where the diffusion is stronger than the (A) characteristic, the regular reflection becomes smaller. In addition, (A) characteristics α, β, and γ are 4, 5.5, and 8, respectively, and (B) characteristics α, β, and γ are 8, 9, and 10, respectively. (B)> (A). Assuming that the antiglare performance is determined only by γ, it can be said that (B) shows a more preferable antiglare property. However, in (B), since the intensity near the regular reflection by the R component is low, the optical sheet has a large difference from the regular reflection of the r component, and the change occurs rapidly. Will be detected inferior.
On the other hand, in (A), since the intensity near the regular reflection by the R component is high, the difference from the regular reflection by the r component is small, and the regular reflection is not strongly recognized, so it is detected that the antiglare property is excellent. Is done. However, γ-α and γ-β in (A) and (B) are 4 and 2.5 in (A), 2 and 1 in (B), respectively, and the magnitude relationship between γ-α and γ-β is ( A)> (B), which matches the antiglare property. That is, since γ-α and γ-β exhibit antiglare properties taking into account the reflection intensity in the vicinity of regular reflection by the diffusing element, the values of γ-α and / or γ-β are excellent as an index of antiglare properties. Analogy.
If α and β are too small, the intensity change in the vicinity of the above-mentioned regular reflection will occur abruptly. Therefore, α is preferably 1.2 degrees or more, more preferably 1.4 degrees or more, and 1.6 degrees. The above is more preferable, and 1.9 degrees or more is particularly preferable. Β is preferably 1.6 ° or more, more preferably 1.9 ° or more, further preferably 2.5 ° or more, and particularly preferably 2.8 ° or more.

The production method of the present invention is characterized by controlling using the following formula (I) and / or (II) as an index.
1.40 <γ-α (I)
0.90 <γ-β (II)
By producing so that γ-α exceeds 1.40 or γ-β exceeds 0.90, an optical sheet excellent in antiglare property can be obtained. From the viewpoint of obtaining better antiglare properties, γ-α preferably exceeds 1.55 (formula (III) 1.55 <γ-α), and more preferably exceeds 1.80 ( Formula (V) 1.80 <γ-α). Further, γ-β is preferably more than 1.30 (formula (IV) 1.30 <γ-β), more preferably 1.90 (formula (VI) 1.90 <γ-β). .

In the present invention, 1.40 <γ-α and 0.90 <γ-β can be achieved by adjusting the diffuse luminance distribution and intensity with the internal and external diffusion elements.
As a method of adjusting the transmission luminance distribution and intensity by the internal diffusion element, the resin constituting the functional layer may be described as translucent inorganic particles and / or translucent organic particles (hereinafter simply referred to as “translucent particles”). There is a way to disperse. Furthermore, it can be performed by controlling the shape of the transparent resin constituting the functional layer, the shape of the translucent particles dispersed in the transparent resin, the dispersed state, the particle diameter, the addition amount, the refractive index, and the like. Further, the concentration of additives other than the translucent particles that can be added to the transparent resin also affects the diffuse transmission intensity of the internal diffusion element.

On the other hand, as a method of adjusting the diffuse transmission intensity by the external diffusion element, for example,
(1) A method for transferring an uneven shape onto the surface of an optical sheet using a mold having fine unevenness on the surface,
(2) A method of forming irregularities on the surface by curing shrinkage of a resin constituting a functional layer such as an ionizing radiation curable resin,
(3) A method of forming irregularities on the surface by projecting and solidifying translucent fine particles from the surface layer,
(4) There is a method of imparting surface irregularities by external pressure.
As the method of (1), for example, an ionizing radiation curable resin is disposed on a transparent substrate, a mold having fine irregularities is brought into close contact with the coating layer of the ionizing radiation curable resin, and cured by ionizing radiation. Thus, an uneven shape can be provided on the surface of the optical sheet.
The method (2) is effective in preventing glare because fine irregularities having a smooth surface can be obtained, and the method (3) described above is the selection of translucent particles and transparent resin, and the coating film. Since the performance can be adjusted by selecting the thickness, solvent selection, drying conditions, permeability to the transparent substrate, etc., it is effective in that the process is short, the operation is simple, and it can be manufactured at low cost.
It should be noted that the antireflection layer provided on the uneven surface, and the functional layers such as the antifouling layer, the hard coat layer, and the antistatic layer also affect the diffuse transmission intensity by the external diffusion element. Specifically, by providing another functional layer on the uneven surface to form a two-layer structure, the surface unevenness can be moderated and surface diffusion can be suppressed. In addition, by increasing the thickness of the coating film of the other functional layer, the surface unevenness can be moderated, and the surface diffusion can be controlled by the coating solution composition, coating and drying conditions, and the like.

The method (3) for obtaining the above-mentioned external diffusion element is preferable in that the external diffusion and the internal diffusion can be simultaneously applied depending on the kind of the light-transmitting fine particles to be used, and the manufacturing process can be simplified. Is the method.
On the other hand, when using a method other than the above (3), the method of adjusting the diffuse transmission intensity by the external diffusion element and the method of adjusting the diffusion transmission intensity by the internal diffusion element can be designed separately and independently. Other than anti-glare properties, it is preferable in terms of easy adjustment of optical performance such as resolution, glare, and contrast. In addition, since the diffusion transmission strength can be adjusted by an external diffusion element without considering the optical performance of the resin used, a resin that exhibits physical performance such as hard coat properties, antifouling properties, and antistatic properties of the surface resin. Is easy to select.

[Translucent particles]
The preferable range of the translucent particles dispersed in the transparent resin will be described in detail below.
The translucent particles may be organic particles, inorganic particles, or a mixture of organic particles and inorganic particles.
In the optical sheet of the present invention, the average particle size of the translucent particles used is preferably in the range of 0.5 to 20 μm, more preferably 1 to 10 μm. Within this range, it is possible to adjust the diffuse transmission intensity distribution by internal diffusion and / or external diffusion. In particular, when the average particle diameter of the translucent particles is 0.5 μm or more, the aggregation of the particles does not become excessive and adjustment of the unevenness is facilitated, and when it is 20 μm or less, a glare or rough image is produced. Since it is difficult, a degree of freedom in designing the diffuse transmission intensity distribution is secured.

In addition, the smaller the variation in the particle size of the translucent particles, the less the scattering characteristics, and the easier the diffuse transmission intensity distribution design. More specifically, when the average diameter by weight average is MV, the cumulative 25% diameter is d25, and the cumulative 75% diameter is d75, (d75−d25) / MV is preferably 0.25 or less. More preferably, it is 20 or less. The cumulative 25% diameter means the particle diameter when counted from a particle having a small particle diameter in the particle size distribution to 25% by mass, and the cumulative 75% diameter is similarly counted to 75% by mass. The particle size when
As a method for adjusting the particle size variation, for example, it can be carried out by adjusting the conditions of the synthesis reaction, and classification after the synthesis reaction is also an effective means. In classification, particles having a desired distribution can be obtained by increasing the number of times or increasing the degree. It is preferable to use a method such as an air classification method, a centrifugal classification method, a sedimentation classification method, a filtration classification method, or an electrostatic classification method for classification.

  Furthermore, it is preferable that the refractive index difference between the transparent resin constituting the functional layer and the translucent particles is 0.01 to 0.25. When the difference in refractive index is 0.01 or more, glare in the antiglare sheet can be suppressed, and when it is 0.25 or less, the diffuse transmission intensity distribution design becomes easy. From the above viewpoint, the difference in refractive index is preferably 0.01 to 0.2, and more preferably 0.02 to 0.15. The refractive index of the translucent particles was measured by measuring the turbidity by dispersing an equal amount of the translucent particles in the solvent in which the refractive index was changed by changing the mixing ratio of two types of solvents having different refractive indexes. It is measured by measuring the refractive index of the solvent when the turbidity is minimized with an Abbe refractometer.

In addition, two or more kinds of translucent particles having a specific gravity difference of 0.1 or more are used in combination, or two or more kinds of translucent particles having different particle diameters having a difference in particle diameter of 0.5 μm or more are used in combination. The diffusion transmission intensity can also be adjusted by using two or more kinds of light-transmitting particles having a refractive index difference of 0.01 or more, or by using spherical light-transmitting particles and amorphous light-transmitting particles in combination. Is possible.
Specific gravity is liquid phase substitution method, gas phase substitution method (pycnometer method), particle size is Coulter counter method, light diffraction scattering method, etc., and refractive index is measured directly by Abbe refractometer or spectral reflection It can be quantitatively evaluated by measuring spectrum and spectroscopic ellipsometry.

Translucent organic particles include polymethyl methacrylate particles, polyacryl-styrene copolymer particles, melamine resin particles, polycarbonate particles, polystyrene particles, crosslinked polystyrene particles, polyvinyl chloride particles, benzoguanamine-melamine formaldehyde particles, silicone particles, Fluorine resin particles, polyester resin particles, and the like are used.
Examples of the light-transmitting inorganic particles include silica particles, alumina particles, zirconia particles, titania particles, and inorganic particles having a hollow shape or pores.

Moreover, even if the light-transmitting fine particles have the same refractive index and particle size distribution, the diffuse transmission intensity distribution differs depending on the degree of aggregation of the light-transmitting particles. Therefore, two or more kinds of light-transmitting particles having different aggregation states are used. It is possible to adjust the diffuse transmission intensity distribution by changing the aggregation state by using two or more inorganic particles having different silane coupling treatment conditions.
In addition, the method of adding the silica etc. which have a particle diameter below the wavelength of visible light, for example, a particle diameter of about 50 nm or less, is mentioned suitably for aggregation of a translucent particle.

  In order to obtain the effect of internal diffusion, amorphous translucent particles such as silica having a particle diameter equal to or larger than the wavelength of visible light are effective. This is because amorphous particles have the effect of widening the distribution of transmission diffusion angles compared to spherical particles. However, amorphous translucent particles also have a wide internal reflection distribution, which affects the diffusibility of the coating and may make it difficult to adjust the diffuse transmission intensity. It is preferable to add it according to. More specifically, it is preferable to add the amorphous translucent particles within a range of less than 4% by mass with respect to the total amount of the spherical particles and the amorphous translucent particles.

  It is preferable to mix | blend translucent particle | grains so that 1-30 mass% may be contained in transparent resin (solid content), and the range of 2-25 mass% is more preferable. When it is 1% by mass or more, sufficient antiglare property and light diffusibility can be produced, and good visibility can be obtained. On the other hand, when it is 30% by mass or less, the resolution is not deteriorated and the image is not blurred.

[Transparent resin]
As the transparent resin constituting the functional layer, an ionizing radiation curable resin or a thermosetting resin can be used. In order to form a functional layer, a resin composition containing an ionizing radiation curable resin or a thermosetting resin is applied to a transparent substrate, and monomers, oligomers and prepolymers contained in the resin composition are crosslinked and / or Alternatively, it can be formed by polymerization.
As the functional groups of the monomer, oligomer and prepolymer, those having ionizing radiation polymerization are preferable, and among them, a photopolymerizable functional group is preferable.

Examples of the photopolymerizable functional group include unsaturated polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group.
Examples of the prepolymer and oligomer include acrylates such as urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate, silicon resins such as siloxane, unsaturated polyester, and epoxy resin.
Monomers include styrene monomers such as styrene and α-methylstyrene; methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, pentaerythritol (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di Acrylic monomers such as pentaerythritol penta (meth) acrylate and trimethylolpropane tri (meth) acrylate; two in a molecule such as trimethylolpropane trithioglycolate, trimethylolpropane trithiopropylate, and pentaerythritol tetrathioglycol Examples include polyol compounds having the above thiol groups.

Moreover, it is also possible to add a polymer to the said resin composition and use it as a binder. Examples of the polymer include polymethyl methacrylate (PMMA). By adding the polymer, it is possible to adjust the viscosity of the coating liquid, and this has the advantage of facilitating the coating and facilitating the adjustment of unevenness formation due to particle aggregation.
Moreover, a radical photopolymerization initiator can be added to the resin composition as necessary. As the radical photopolymerization initiator, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds and the like are used.
As acetophenones, 2,2-dimethoxyacetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxy-dimethylphenylketone, 1-hydroxy-dimethyl-p-isopropylphenylketone, 1-hydroxycyclohexylphenyl Ketone, 2-methyl-4-methylthio-2-morpholinopropiophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, 4-phenoxydichloroacetophenone, 4-t-butyl- Examples of benzoins include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl dimethyl ketal, and benzoin benzene sulfonic acid. Ester, benzoin toluenesulfonic acid ester, benzoin methyl ether, benzoin ethyl ether. Benzophenones include benzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone, 4,4′-dimethylaminobenzophenone. (Michler's ketone), 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone and the like can be used.
Moreover, a photosensitizer can also be mixed and used and the specific example includes n-butylamine, triethylamine, poly-n-butylphosphine, and the like.

Moreover, it is also possible to adjust the diffuse transmission intensity by the internal diffusion element by using a plurality of phase-separable resins as the transparent resin. That is, in the above-mentioned prepolymer, oligomer, monomer, and polymer, it is also possible to adjust the diffuse transmission intensity by the internal diffusion element by using a mixture of a compatible component and an incompatible component. For example, when one resin is a styrene resin (polystyrene, styrene-acrylonitrile copolymer, etc.), the other resin is a cellulose derivative (cellulose ester such as cellulose acetate propionate), a (meth) acrylic resin ( Suitable examples include polymethyl methacrylate), alicyclic olefin resins (polymers having norbornene as a monomer), polycarbonate resins, polyester resins, and the like. When one resin is a cellulose derivative (cellulose ester such as cellulose acetate propionate), the other resin is a styrene resin (polystyrene, styrene-acrylonitrile copolymer, etc.), (meth) acrylic resin. (Polymethyl methacrylate, etc.), alicyclic olefin resins (polymers having norbornene as a monomer, etc.), polycarbonate resins, polyester resins and the like are preferred.
The ratio (mass ratio) of the resin to be combined can be selected from the range of 1/99 to 99/1, preferably in the range of 5/95 to 95/5, more preferably in the range of 10/90 to 90/10, and 20 / The range of 80-80 / 20, especially the range of 30 / 70-70 / 30 is preferable.

  Furthermore, it is also possible to adjust the diffuse transmission intensity by the external diffusion element by using the prepolymer, oligomer and monomer having a large polymerization shrinkage. The larger the polymerization shrinkage, the larger the surface unevenness and the wider the diffuse transmission intensity distribution.

  In addition, a solvent is usually used in the radiation curable resin composition in order to adjust the viscosity and to dissolve or disperse each component. The solvent is preferably selected as appropriate in consideration of the fact that the surface state of the coating film varies depending on the coating and drying steps depending on the type of solvent used, and the transmission intensity distribution due to external diffusion can be adjusted. Specifically, it is selected in consideration of saturated vapor pressure, permeability to a transparent substrate, and the like.

In the production method of the present invention, the resin composition for forming the functional layer preferably contains an ionizing radiation curable resin as a transparent resin, translucent particles, and a solvent. Here, the resin composition impregnates the transparent substrate with a solvent impregnated in the transparent substrate (hereinafter sometimes referred to as “penetrating solvent”) and / or an ionizing radiation curable resin impregnated in the transparent substrate. It is preferable to include an ionizing radiation curable resin that is not impregnated into the solvent and / or the transparent substrate that is not impregnated. This is because the thickness of the functional layer can be controlled by adjusting the amount of impregnation into the transparent substrate, and as a result, the diffuse transmission intensity can be adjusted.
More specifically, the diffuse transmission intensity can be controlled by the amount of impregnation into the transparent substrate and the size of the translucent particles. Specifically, when the amount of impregnation of the solvent and / or ionizing radiation curable resin (hereinafter sometimes referred to as “solvent etc.”) into the substrate is small and the translucent particles are small, the solvent Although the functional layer is formed in a form in which most of the particles are embedded in the surface, the translucent particles are likely to aggregate, and the surface irregularities are relatively large. On the other hand, when a solvent having a large amount of impregnation into a transparent substrate and a light-transmitting particle having a small particle diameter are used in combination, the aggregation of the light-transmitting particles is reduced, and the surface unevenness is relatively small. become.
In addition, when a solvent and / or ionizing radiation curable resin with a large amount of impregnation into a transparent substrate is used in combination with a light-transmitting particle having a large particle size, the thickness of the functional layer is reduced. The light-sensitive particles protrude from the functional layer, and surface irregularities resulting from the light-transmitting particles can be obtained. On the other hand, when a solvent having a small amount of impregnation into a transparent substrate and a light-transmitting particle having a large particle size are used in combination, the thickness of the functional layer is increased. Protrusion to the surface is suppressed, and surface irregularities are relatively small.
In this way, by adjusting the amount of impregnation of the solvent and / or ionizing radiation curable resin into the transparent base material and controlling it in combination with the particle size of the translucent particles, various surface irregularities can be formed. Can be formed.
This technique is particularly effective when the transparent substrate is made of a cellulose resin.

Further, as the solvent, one kind can be used alone, or two or more kinds of solvents having different boiling points at room temperature and normal pressure can be contained. By using two or more solvents, the drying speed of the solvent can be controlled in various ways. When the drying speed is high, the particles are volatilized and the solvent is reduced and the viscosity is increased before the particles are sufficiently aggregated, so that further aggregation does not proceed. Therefore, controlling the drying rate will control the particle size of the translucent particles, and as described above, in relation to the degree of penetration of the solvent and / or ionizing radiation curable resin into the substrate, It leads to controlling the diffuse transmission intensity.
Specific solvents can be appropriately selected from the above viewpoints. Specific examples include aromatic solvents such as toluene and xylene, and ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone. Are preferred. These can be used alone or in combination of two or more. It is preferable to use a mixture of at least one aromatic solvent and at least one ketone. In addition, in order to control the drying speed, cellosolves such as methyl cellosolve and ethyl cellosolve and cellosolve acetates, alcohols such as ethanol, isopropanol, butanol, and cyclohexanol may be mixed.

In the optical sheet according to the present invention, additives other than the translucent particles are blended in the transparent resin as necessary. For example, various inorganic particles can be added to improve physical properties such as hardness, optical properties such as reflectance, and scattering properties.
Examples of inorganic particles include metals such as zirconium, titanium, aluminum, indium, zinc, tin, and antimony, ZrO ₂ , TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO, Examples thereof include metal oxides such as ATO and SiO ₂ . Other carbon, MgF, silicon, BaSO _4, CaCO _3, talc, and the like kaolin.
The particle size of the inorganic particles is preferably as fine as possible in the resin composition when the functional layer is applied in order to reduce the influence on the diffuse transmission intensity distribution, and the average particle size is 100 nm or less. It is preferable that it is the range of these. By miniaturizing the inorganic particles to 100 nm or less, an optical sheet that does not impair transparency can be formed. The particle diameter of the inorganic particles can be measured by a light scattering method or an electron micrograph.

In the present invention, various surfactants can be used to improve the properties such as anti-aggregation effect and anti-settling effect, and other leveling properties. Examples of the surfactant include silicone oil, a fluorine-based surfactant, and preferably a fluorine-based surfactant containing a perfluoroalkyl group.
Furthermore, in the present invention, an antifouling agent, an antistatic agent, a colorant (pigment, dye), a flame retardant, an ultraviolet absorber, an infrared absorber, an adhesion promoter, a polymerization inhibitor, an antioxidant, a surface modifier, etc. Can be added.

The transparent substrate used in the optical sheet of the present invention is not particularly limited as long as it is usually used in an optical sheet, such as a transparent resin film, a transparent resin plate, a transparent resin sheet, or transparent glass.
Transparent resin films include triacetylcellulose film (TAC film), diacetylcellulose film, acetylbutylcellulose film, acetylpropylcellulose film, cyclic polyolefin film, polyethylene terephthalate film, polyethersulfone film, polyacrylic resin film, polyurethane film Resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyether ketone films, (meth) acrylonitrile films, polynorbornene resin films, and the like can be used. In particular, when the optical sheet of the present invention is used together with a polarizing plate, the TAC film and the cyclic polyolefin film are preferable because they do not disturb the polarization, and polyester films such as a polyethylene terephthalate film are preferable when the mechanical strength and smoothness are important. .

  The transparent substrate may be a multilayer or a single layer, and a primer layer may be provided on the surface for the purpose of adhesion to the coating film. In addition, in order to prevent interference fringes generated at the interface when there is a substantial difference in refractive index between the transparent substrate and the coating layer, for example, interference fringes having an intermediate refractive index between the transparent substrate and the coating layer. It is also possible to provide a prevention layer and to provide unevenness of about 0.3 to 1.5 μm as the surface roughness (ten-point average roughness Rz). Rz is a value measured according to JIS B0601 1994.

The optical sheet produced by the production method of the present invention has excellent antiglare properties. As for the antiglare property, the transparent resin capable of imparting hard coat properties described later preferably contains translucent particles for imparting antiglare property, and a solvent, and the projections of the translucent particles themselves or It is preferable that surface irregularities are formed by protrusions formed by an aggregate of a plurality of particles. The antiglare property is evaluated by the following method.
(Anti-glare evaluation method)
A measurement sample is produced by sticking an optical sheet on a flat black acrylic plate. A light source is incident from a direction of 15 degrees with respect to the normal direction of the measurement sample, and a reflection image of the light source is photographed by a CCD camera installed at a position in the mirror surface direction to obtain the maximum peak intensity of the reflected light. When this measurement is performed with two light sources of different sizes, the reflected light peak intensity value when measured with a large light source is P _L , and the reflected light peak intensity value when measured with a small light source is P _S , The antiglare property is evaluated by the formula (VII).
50 × log (P _L / P _S ) (VII)
The larger this value, the higher the antiglare property. In this evaluation, it is preferably 20 or more, more preferably 40 or more, and particularly preferably 60 or more.
Also, a measurement sample is prepared by sticking an optical sheet on a flat black acrylic plate, and a light source of about 900 lux is captured at an angle of, for example, 15 degrees, and the degree of blurring seen from the regular reflection direction is visually observed. May be evaluated.

In addition to the antiglare property, the optical sheet according to the present invention can have functions such as hard coat property, antireflection property, antistatic property, and antifouling property.
Hard coat properties are usually the maximum load at which scratches are not confirmed when a black tape is applied to the backside of the 10-round rubbing test while applying a load with pencil hardness (measured according to JIS K5400) or steel wool # 0000. (Steel wool scuff resistance) In the optical sheet according to the present invention, the pencil hardness is preferably H or higher, more preferably 2H or higher. Further, in the steel wool scuff resistance, is preferably 200 g / cm ² or more, more preferably 500 g / cm ² or more, particularly preferably 700 g / cm ² or more.

Next, for antireflection, a low refractive index layer is provided on the outermost surface in order to reduce the reflectance of the sheet. The refractive index of the low refractive index layer is preferably 1.5 or less, and more preferably 1.45 or less.
The low refractive index layer is formed of a material containing silica or magnesium fluoride, a fluororesin that is a low refractive index resin, or the like.
The thickness d of the low refractive index layer preferably satisfies d = mλ / 4n. Here, m represents a positive odd number, n represents the refractive index of the low refractive index layer, and λ represents the wavelength. m is preferably 1, and λ is preferably 480 to 580 nm. Moreover, it is preferable to have a relationship of 120 <n · d <145 from the viewpoint of low reflectance.

Moreover, it is preferable to provide antistatic performance in terms of preventing static electricity on the optical sheet surface. In order to impart antistatic performance, for example, a method of applying a conductive coating liquid containing conductive fine particles, a conductive polymer, a quaternary ammonium salt, thiophene and a reactive curable resin, or a transparent film is formed. Conventionally known methods such as a method of forming a conductive thin film by vapor deposition or sputtering of metal, metal oxide or the like can be mentioned. Further, the antistatic layer can be used as a part of a functional layer such as a hard coat, antiglare and antireflection.
As an index indicating antistatic property, there is a surface resistance value. In the present invention, the surface resistance value is preferably 10 ¹² Ω / □ or less, more preferably 10 ¹¹ Ω / □ or less, and particularly preferably 10 ¹⁰ Ω / □ or less. . The so-called saturation band voltage, which is the maximum voltage that can be stored in the optical film, is preferably 2 kV or less with an applied voltage of 10 kV.

  Further, an antifouling layer can be provided on the outermost surface of the optical sheet of the present invention. The antifouling layer lowers the surface energy and makes it difficult to attach hydrophilic or lipophilic stains. The antifouling layer can be applied by adding an antifouling agent, and examples of the antifouling agent include fluorine compounds, silicon compounds, and mixtures thereof, and compounds having a fluoroalkyl group are particularly preferred.

Hereinafter, the manufacturing method of the optical sheet of the present invention will be described in detail. In the present invention, as described above, it is important to control the manufacturing conditions so as to satisfy the expression Q / P <0.94 as an index.
The optical sheet of the present invention is produced by applying a resin composition constituting a functional layer to a transparent substrate. Various methods can be used as the coating method, such as dip coating, air knife coating, curtain coating, roll coating, wire bar coating, gravure coating, die coating, blade coating, Known methods such as a micro gravure coating method, a spray coating method, and a spin coating method are used.
In the present invention, since the transmission diffusion luminance characteristics vary depending on the coating amount, a roll coating method, a gravure coating method, and a die coating method that can easily obtain the functional layer thickness in a range of 1 to 20 μm are preferable.

After coating by any of the above methods, the solvent is dried by various known methods by being transported to a heated zone to dry the solvent. Here, by selecting the solid content concentration, coating solution temperature, drying temperature, drying air speed, drying time, solvent atmosphere concentration in the drying zone, etc., external diffusion due to the profile of the surface uneven shape and the translucent particles or the above-mentioned The internal diffusion due to the additive can be adjusted. In particular, a method of adjusting the transmission diffusion luminance characteristics by selecting drying conditions is simple and preferable. Specifically, the drying temperature is preferably 30 to 120 ° C., and the drying wind speed is preferably 0.2 to 50 m / s, and the transmission diffusion luminance characteristic can be adjusted by appropriately adjusting within this range.
More specifically, by increasing the drying temperature, the permeability of the resin and the solvent to the base material is improved. That is, by controlling the drying temperature, the permeability of the resin and solvent to the base material can be controlled, and as described above, the diffuse transmission intensity is controlled in relation to the particle size of the translucent particles. It leads to things.
For example, a resin composition for forming a functional layer is composed of a transparent resin, translucent particles, and a solvent, and the refractive index of the transparent resin penetrating component is lower than the refractive index of the translucent particles. When the settling and aggregation of the ring and translucent particles are the same, if the drying time until curing becomes longer, the low refractive component in the transparent resin penetrates the transparent substrate, and the refractive index of the transparent resin increases. Thus, the difference in refractive index from the translucent particles is reduced. On the other hand, since the ratio of the translucent particles to the transparent resin is increased, the translucent particles are likely to protrude on the surface, and surface irregularities are easily developed. Therefore, the longer the drying time, the smaller the internal diffusion and the larger the external diffusion. By using this permeability, the adhesion between the transparent base material and the functional layer due to the anchor effect and the occurrence of interference fringes that become noticeable when the difference in refractive index between the transparent base material and the functional layer is 0.03 or more are prevented. It is also possible to do. This is because the low-refractive component in the transparent resin penetrates the transparent base material, and the permeation layer expresses the function as a refractive index adjustment layer in which the refractive index continuously changes between the transparent base material and the functional layer. This is because it has the effect of eliminating the interface.

  Further, by increasing the drying speed, the aggregation time of the translucent particles is shortened, so that the aggregation does not proceed, and the same effect as when the particle size of the translucent particles that act substantially becomes smaller is exhibited. . That is, by controlling the drying rate, the particle size of the translucent particles that act substantially can be controlled. As described above, the penetration of the solvent and / or ionizing radiation curable resin into the base material is possible. It leads to controlling the diffuse transmission intensity in relation to the degree.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
(Evaluation methods)
1. Calculation of α, β and γ For the optical sheet produced in each production example, the diffuse reflection intensity was measured using “GC5000L” manufactured by Nippon Denshoku Industries Co., Ltd. by the method described in the specification text. , Α, β and γ were calculated. The diffuse reflection intensity was measured in the range of -85 degrees to 85 degrees.
2. Measurement of haze The optical sheet produced in each production example was measured with “Haze Meter HM-150” manufactured by Murakami Color Research Laboratory.
3. Antiglare property For the optical sheet produced in each production example, a measurement sample was prepared by sticking an optical sheet on a flat black acrylic plate, and a 900 lux light source was captured at an angle of 15 degrees. The degree of blurring seen from the reflection direction was visually evaluated. The evaluation 1 is the worst antiglare property, and the evaluation 5 is the best antiglare property.

Production Example 1
Triacetyl cellulose (manufactured by Fuji Film Co., Ltd., thickness 80 μm) was prepared as a transparent substrate. As a transparent resin, a mixture (mass ratio; PETA / DPHA / PMMA = 86/5/9) of pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), and polymethyl methacrylate (PMMA) is used (refraction) 1.51), polystyrene particles (refractive index 1.6, average particle size 3.5 μm, (d75-d25) / MV is 0.05) and styrene-acrylic copolymer particles (transparent particles). 18.5 and 3.5 parts by mass of a refractive index of 1.56, an average particle diameter of 3.5 μm, and (d75-d25) / MV of 0.04) were added to 100 parts by mass of the transparent resin. A resin composition obtained by adding 190 parts by mass of a mixed solvent (mass ratio 7: 3) of toluene (boiling point 110 ° C.) and cyclohexanone (boiling point 156 ° C.) as a solvent to 100 parts by mass of the transparent resin. Was coated on the transparent substrate, and dried at 70 ° C. at a flow rate of 0.2 m / s for 1 minute. Thereafter, ultraviolet rays were irradiated (200 mJ / cm ² under a nitrogen atmosphere) to cure the transparent resin, and an optical sheet (antiglare sheet) was produced. The coating thickness was 3.5 μm. Table 2 shows the results of evaluating the optical sheet by the above method.

Production Examples 2-7 and Production Examples 10-18
In Production Example 1, the type of transparent substrate, the type of transparent resin, the type and content of translucent particles, the type and content of solvent, the drying conditions, and the coating thickness change as described in Table 1. Thus, an optical sheet (antiglare sheet) was produced. Table 2 shows the evaluation results for each optical sheet in the same manner as in Production Example 1.

Production Example 8
Triacetyl cellulose (manufactured by Fuji Film Co., Ltd., thickness 80 μm) was prepared as a transparent substrate. Pentaerythritol triacrylate (PETA, refractive index 1.51) was used as a transparent resin, and styrene-acrylic copolymer particles (refractive index 1.51, average particle size 9.0 μm, (d75- d25) / MV is 0.04) and polystyrene particles (refractive index 1.6, average particle size 3.5 μm, (d75-d25) / MV is 0.05), respectively, with respect to 100 parts by mass of the transparent resin. It was made to contain 10.0 mass parts and 16.5 mass parts. A resin composition obtained by adding 190 parts by mass of a mixed solvent (mass ratio 7: 3) of toluene (boiling point 110 ° C.) and cyclohexanone (boiling point 156 ° C.) as a solvent to 100 parts by mass of the transparent resin. Was coated on the transparent substrate, dried at a flow rate of 1 m / s at 85 ° C. for 1 minute. This was irradiated with ultraviolet rays (100 mJ / cm ^{2 in an} air atmosphere) to cure the transparent resin (formation of an antiglare layer).
On the coating layer (antiglare layer), PETA (pentaerythritol triacrylate, refractive index 1.51) as a transparent resin, and a mixed solvent of toluene (boiling point 110 ° C.) and cyclohexanone (boiling point 156 ° C.) as a solvent ( The resin composition obtained by blending 190 parts by mass with respect to 100 parts by mass of the transparent resin at a mass ratio of 7: 3) was applied, and 70 ° C. dry air was circulated at a flow rate of 5 m / s. It was dried for a minute (formation of a hard coat layer). This was irradiated with ultraviolet rays (200 mJ / cm ² under a nitrogen atmosphere) to cure the transparent resin, and an optical sheet (antiglare sheet having a hard coat layer) was produced. The coating thickness was 12.0 μm as a whole. Table 2 shows the evaluation results of this optical sheet in the same manner as in Production Example 1.

Production Example 9
In Production Example 8, the content of polystyrene particles that are translucent particles is 6.5 parts by mass with respect to 100 parts by mass of the transparent resin, and the production thickness is 13.0 μm in total. In the same manner as in Example 8, an optical sheet (antiglare sheet having a hard coat layer) was produced. The results evaluated in the same manner as in Production Example 1 are shown in Table 2.

A: polystyrene particles (refractive index 1.6, average particle size 3.5 μm, (d75-d25) / MV is 0.05)
B: Styrene-acrylic copolymer particles (refractive index 1.56, average particle size 3.5 μm, (d75-d25) / MV is 0.04)
C: Styrene-acrylic copolymer particles (refractive index 1.51, average particle size 9.0 μm, (d75-d25) / MV is 0.04)
D: amorphous silica (refractive index 1.45, average particle size 1.5 μm, (d75-d25) / MV is 0.6)
E: amorphous silica (refractive index 1.45, average particle size 2.5 μm, (d75-d25) / MV is 0.8)
F: Melamine particles (refractive index 1.66, average particle size 2.0 μm, (d75-d25) / MV is 0.2)
P: a mixture of pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), and polymethyl methacrylate (PMMA) (mass ratio; PETA / DPHA / PMMA = 86/5/9) (refractive index 1. 51)
Q: pentaerythritol triacrylate (PETA) (refractive index 1.51)
X: Mixture of toluene (boiling point 110 ° C.) and methyl isobutyl ketone (boiling point 116 ° C.) (mass ratio 8: 2)
Y: Mixture of toluene (boiling point 110 ° C.) and cyclohexanone (boiling point 156 ° C.) (mass ratio 7: 3)

Example 1
In Production Examples 1 to 18, γ-α and γ-β were calculated from the measurement results of diffuse reflection intensity, γ-α and γ-β were plotted on the horizontal axis, and antiglare properties were plotted on the vertical axis. Shown in It has been demonstrated that γ-α and γ-β and antiglare properties are correlated.

Comparative Example 1
In Production Examples 1 to 18, the result of plotting haze on the horizontal axis and anti-glare property on the vertical axis from the measurement result of the haze value is shown in FIG. Furthermore, the result of plotting the ratio of internal haze to total haze on the horizontal axis and antiglare property on the vertical axis is shown in FIG. It can be seen that there is no correlation between haze and antiglare property, internal haze / total haze ratio and antiglare property.

  According to the method for producing an optical sheet of the present invention, it is possible to easily evaluate an antiglare property that could not be evaluated with a conventional haze value, and to efficiently produce an optical sheet with little decrease in the antiglare property.

It is a figure which shows the relationship between a haze value and anti-glare property. It is a figure which shows the relationship between ratio of internal haze / total haze, and anti-glare property. It is a conceptual diagram which shows the measuring method of the diffuse transmission intensity in this invention. It is a figure explaining the calculation method of (alpha). It is a figure explaining the calculation method of (beta). It is a figure explaining the calculation method of (gamma). It is a figure which shows distribution of the diffusion intensity with respect to a diffusion angle. It is a figure which shows the distribution of the diffusion intensity with respect to the diffusion angle (an example in which the ratio of r and R is the same and the characteristics of the diffusion intensity due to the diffusion element are different). It is a figure which shows correlation with (gamma)-(alpha) and (gamma)-(beta), and anti-glare property.

Explanation of symbols

1. Optical sheet Base material 4. 4. Light incident direction 5. Diffuse regular reflection direction Functional layer (antiglare layer)
7). Translucent particles 8. Visible light absorbing material (black acrylic board)

Claims (19)

A method for producing an optical sheet having a functional layer on at least one surface of a transparent substrate, and having a diffusing element on the outermost surface and / or inside of the functional layer, the following formula (I) and / or (II) The manufacturing method of the optical sheet used for the surface of a display element characterized by controlling manufacturing conditions so that it may have these relationships.
1.40 <γ-α (I)
0.90 <γ-β (II)
α: Diffusion angle β indicating a half of the diffusion intensity obtained by extrapolating the straight line connecting the reflection intensity at ± 2 degrees and the reflection intensity at ± 1 degree to the diffuse regular reflection direction to the diffuse regular reflection angle A diffusion angle γ indicating the intensity of 1/3 of the diffusion intensity obtained by extrapolating a straight line connecting the reflection intensity at ± 2 degrees and the reflection intensity at ± 1 degree to the diffuse regular reflection direction; Diffusion angle indicating 1/10 of the diffusion intensity obtained by extrapolating the straight line connecting the reflection intensity at ± 2 degrees and the reflection intensity at ± 1 degree to the diffuse regular reflection direction to the diffuse regular reflection angle Furthermore, the manufacturing method of the optical sheet of Claim 1 controlled so that it may have the relationship of following formula (III) and / or (IV).
1.55 <γ-α (III)
1.30 <γ-β (IV) Furthermore, the manufacturing method of the optical sheet of Claim 1 controlled so that it may have the relationship of following formula (V) and / or (VI).
1.80 <γ-α (V)
1.90 <γ-β (VI)   The method for producing an optical sheet according to any one of claims 1 to 3, wherein the functional layer is formed by dispersing translucent inorganic particles and / or translucent organic particles in a transparent resin.   The method for producing an optical sheet according to claim 1, wherein the functional layer is made of a transparent resin, and the transparent resin is made of a plurality of resins capable of phase separation.   The method for producing an optical sheet according to claim 4, wherein the transparent resin and the translucent inorganic particles and / or translucent organic particles have different refractive indexes.   The manufacturing method of the optical sheet of Claim 4 or 6 which provides an unevenness | corrugation on the surface of a functional layer with the said translucent inorganic particle and / or translucent organic particle.   The method for producing an optical sheet according to claim 6 or 7, wherein a refractive index difference between the transparent resin and the light-transmitting inorganic particles and / or the light-transmitting organic particles is 0.01 to 0.25.   The method for producing an optical sheet according to any one of claims 4 and 6 to 8, wherein the translucent inorganic particles and / or translucent organic particles have an average particle size of 0.5 to 20 µm.   When the average diameter of the light-transmitting inorganic particles and / or the light-transmitting organic particles is MV, the cumulative 25% diameter is d25, and the cumulative 75% diameter is d75, (d75−d25) / MV is 0. The method for producing an optical sheet according to any one of claims 4 and 6 to 9, wherein the optical sheet is 25 or less.   The method for producing an optical sheet according to any one of claims 4 and 6 to 10, wherein 1 to 30% by mass of the translucent inorganic particles and / or translucent organic particles are contained in the transparent resin.   The method for producing an optical sheet according to claim 1, wherein the unevenness provided on the surface of the mold is reversely transferred to provide unevenness on the surface of the functional layer.   2. The transparent resin is an ionizing radiation curable resin, and the functional layer is formed by applying an ionizing radiation curable resin composition containing the ionizing radiation curable resin on a transparent base material and curing by crosslinking. The manufacturing method of the optical sheet in any one of -12.   The transparent substrate is made of a cellulose-based resin, and the ionizing radiation curable resin composition includes a solvent that impregnates the transparent substrate and / or an ionizing radiation curable resin that impregnates the transparent substrate, and a solvent that does not impregnate the transparent substrate. And / or an ionizing radiation curable resin not impregnated in the transparent base material, and adjusting the amount of impregnation into the transparent base material, the relationship of any one of the above formulas (I), (III) and (V) 14. The method for producing an optical sheet according to claim 13, wherein the optical sheet is controlled so as to have any one of the formulas (II), (IV), and (VI).   The method for producing an optical sheet according to claim 14, wherein the transparent substrate is triacetylcellulose.   The method for producing an optical sheet according to claim 1, wherein the transparent substrate is polyethylene terephthalate. The method for producing an optical sheet according to claim 1, wherein the functional layer includes a hard coat layer, and the steel wool scuff resistance is 200 g / cm ² or more.   The manufacturing method of the optical sheet in any one of Claims 1-17 which forms an antireflection functional layer in the outermost layer.   The optical sheet obtained by the manufacturing method in any one of Claims 1-18.

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