JP5144826B1 - Optical element - Google Patents

Abstract

An optical element having excellent antireflection performance in a wide wavelength range from visible to near infrared and in a wide incident light angle range is provided.
An optical element (1) according to the present invention comprises a substrate (10) and fine irregularities provided on the surface of the substrate (10) and including a plurality of convex portions (11) and a plurality of concave portions (12). And the height of the vertices (11a) of the plurality of protrusions (11) from the reference plane (X) is 200 nm or more, and any of the protrusions (11) included in the plurality of protrusions (11) The interval between the vertex (11a) of the convex portion (11) and the vertex (11a) of the convex portion (11) closest to the arbitrary convex portion (11) is less than 260 nm in plan view, and a plurality of convex portions (11) or the arrangement pattern of the plurality of recesses (12) is an N-shaped lattice, and the N protrusions (11) adjacent to the arbitrary protrusions (11) and the arbitrary protrusions (11). 1 to (N−2) ridges exist between the two.
[Selection] Figure 1

Description

  The present invention relates to an optical element used in a display device such as a display-equipped device, and more particularly to an optical element having a fine uneven structure on the surface.

  In recent years, with the expansion of the display market, there has been an increasing demand to view clearer images indoors and outdoors. However, there is a problem that a television that is visually recognized indoors cannot visually recognize a clear image due to reflection on the screen by illumination light. In addition, a mobile phone, a small game machine, a digital camera, a digital video camera, and the like that are visually recognized outdoors have a problem that a clear image cannot be visually recognized due to reflection on the screen by sunlight.

  In order to prevent such reflection and improve visibility, it is necessary to improve the antireflection performance for incident light from the front side of the screen in a wide wavelength region. Further, the incident angle of incident light on the screen differs depending on the type of display-equipped device and the place where it is used. For this reason, in order to prevent the reflection on the screen and improve the visibility, it is necessary to have antireflection performance in a wide incident light angle range.

  As a technique for improving the antireflection performance of a display, an antireflection film having an alternating multilayer structure of a high refractive index layer and a low refractive index layer has been proposed (see, for example, Patent Document 1). This antireflection film exhibits an antireflection effect by canceling the reflected light by utilizing the interference action between the transmitted light and the reflected light caused by the difference in refractive index between the high refractive index layer and the low refractive index layer.

  As a technique for improving the antireflection performance of the display, a structure having a shape in which the effective refractive index neff (h) intersects with the function Neff (h) at three points has been proposed (see, for example, Patent Document 2). Non-Patent Document 1 shows that a so-called moth-eye structure in which a submicron-order pyramidal concavo-convex structure is arranged in a two-dimensional pattern like an eyelet has an antireflection effect. Further, Non-Patent Document 2 discloses an optical element having a moth-eye structure on a substrate such as resin or glass, and the spectral reflectance of the optical element in the visible wavelength region.

Japanese Patent Laid-Open No. 06-337302 JP 2009-217278 A

Endeavor 26, P.I. 79-84 (1967) Phototechnical Contact 43 (11), p. 630-637 (2005)

  However, the antireflection film described in Patent Document 1 exhibits excellent antireflection performance at a specific wavelength, but does not exhibit sufficient antireflection performance over a wide wavelength region, and is sufficient in a wide incident light angle range. In addition, antireflection performance cannot be realized. In addition, in the optical elements described in Patent Document 2, Non-Patent Document 1, and Non-Patent Document 2, both sufficient antireflection performance in a wide wavelength region and sufficient antireflection performance in a wide incident light angle range can be realized. It's hard to say.

  This invention is made | formed in view of this point, and it aims at providing the optical element which was excellent in the antireflection performance in the wide wavelength range ranging from visible to near infrared, and a wide incident light angle range. .

The optical element of the present invention has a base material and a fine concavo-convex structure including a plurality of convex portions and a plurality of concave portions provided on the surface of the base material, and in a predetermined region of the fine concavo-convex structure, from a reference surface The height of the vertices of the plurality of protrusions is 200 nm or more, the interval between the plurality of adjacent protrusions is less than 260 nm in plan view, and the arrangement pattern of the plurality of protrusions or the plurality of recesses is , A hexagonal lattice, and there is a ridge between the arbitrary convex portion and three or four convex portions belonging to the six convex portions adjacent to the arbitrary convex portion, and the arbitrary convex portion Among the six convex portions adjacent to the portion, convex portions other than the three or four convex portions are not adjacent to each other .
Further, the optical element of the present invention has a base material and a fine concavo-convex structure including a plurality of convex portions and a plurality of concave portions provided on the surface of the base material, and in a predetermined region of the fine concavo-convex structure, a reference The height of the vertices of the plurality of projections from the surface is 200 nm or more, the interval between the plurality of adjacent projections is less than 260 nm in plan view, and the plurality of projections or the plurality of recesses are arranged. The pattern is a tetragonal lattice, and there is a ridge between the arbitrary convex portion and two or three convex portions belonging to the four convex portions adjacent to the arbitrary convex portion, and the arbitrary Among the four convex portions adjacent to the convex portion, convex portions other than the two or three convex portions are not adjacent to each other.

According to this configuration, the height of the convex portion from the reference surface is set to 200 nm or more, and the interval between the adjacent convex portions is set to 260 nm in a plan view, so that only incident light entering the optical element from the front side is obtained. In addition, it is possible to sufficiently secure the height of the apex of the convex portion and the interval between the convex portions from the reference plane X necessary for improving the antireflection performance, even for incident light entering from an oblique direction. Thereby, generation | occurrence | production of a diffraction phenomenon can be suppressed and the raise of the reflectance in a specific wavelength can be suppressed, Therefore The antireflection performance in a visible wavelength region can be improved. And the arrangement pattern of a plurality of convex parts or a plurality of concave parts is a hexagonal lattice pattern, and three or four convex parts belonging to any convex part and six convex parts adjacent to the arbitrary convex part A ridge is present between the two convex portions other than the three or four convex portions among the six convex portions adjacent to the arbitrary convex portion, or the The arrangement pattern is a tetragonal lattice, and there is a ridge between any convex part and two or three convex parts belonging to four convex parts adjacent to the arbitrary convex part, and the arbitrary pattern Among the four convex portions adjacent to the convex portion, the convex portions other than the two or three convex portions are not adjacent to each other, so that a fine concavo-convex structure in the height direction from the reference plane X is provided. The refractive index gradient of the substrate surface can be made smooth. As a result, an optical element having excellent antireflection performance can be realized in a wide wavelength range from visible to near infrared and in a wide incident light angle range.

In the optical element of the present invention, when the array pattern is a hexagonal lattice, the ridge is 4 between the arbitrary convex portions and the six convex portions adjacent to the arbitrary convex portions. It is preferable that there exist .

In the optical element of the present invention, a ratio of an area occupied by a region having a height of 250 nm or more from the reference surface to an area of the predetermined region in a plan view is 5% or more, and the fine concavo-convex structure is The number of fractions generated when fractionating into 50-nm sections from the reference plane in the height direction is n, and the area occupied by the i-th fraction in plan view with respect to the area occupied by all fractions in the predetermined region in plan view The average deviation of the height represented by the following formula (1) is 3 or more and 8 or less, where the ratio of the ratio is Hi and the value obtained by dividing the total of the ratios Hi in all fractions by n is Have. In the concavo-convex structure, it is preferable that there are two or more inflection points in a curve indicating the relationship between the height and the ratio of the area occupied by the region higher than the predetermined height in plan view.

  In the optical element of the present invention, it is preferable that the standard deviation of the recess depth of the recess is 3 or more and 20 or less.

  In the optical element of the present invention, it is preferable that the standard deviation of the height of the convex portion is 3 or more and 20 or less.

  In the optical element of the present invention, it is preferable that an average value of the height of the ridge with respect to an average value of the heights of the convex portions is 20% or more and 80% or less.

  In the optical element of the present invention, it is preferable that there are 4 or 8 ridges in an arbitrary unit cell composed of the arbitrary convex portion and a plurality of convex portions closest to the arbitrary convex portion.

  In the optical element of the present invention, in the unit cell composed of the plurality of concave portions and the plurality of convex portions, the sum of the area of the unit cell (Sall) and the area of the bottom region having a height of 10 nm or less from the reference surface ( The ratio (Sb / Sall) to Sb) is preferably 10% or less.

  In the optical element of the present invention, the difference between the maximum value and the minimum value among the intervals between the apex of the arbitrary convex portion and the apexes of the six or four convex portions closest to the arbitrary convex portion is calculated. The value [(Pmax−Pmin) / Pave] divided by the average value of the intervals is preferably 20% or less.

  In the optical element of the present invention, it is preferable that the fine concavo-convex structure is constituted by a composition layer, and the thickness of the resin composition layer is 0.4 μm or more and 10 μm or less.

  In the optical element of the present invention, the composition layer contains 20 parts by mass to 60 parts by mass of one or more monomer components having three or more acrylic groups and / or methacrylic groups in one molecule in 100 parts by mass. It is preferable to harden a composition containing 5 parts by mass to 40 parts by mass of a monomer component having an N-vinyl group and 0 to 75 parts by mass of other monomer components.

  In the optical element of the present invention, the composition is preferably a photocurable composition.

  In the optical element of the present invention, the viscosity of the photocured composition before photocuring at 50 ° C. is preferably 100 mPa · s or less.

  The resin film roll of the present invention includes the optical element described above, and has a width of 10 cm or more and a length of 50 m or more.

  A display device according to the present invention includes the above-described optical element.

  The illuminating device of this invention was equipped with the said optical element.

  The solar cell of the present invention includes the above-described optical element.

  ADVANTAGE OF THE INVENTION According to this invention, the optical element excellent in the antireflection performance is realizable in the wide wavelength range ranging from visible to near infrared, and a wide incident light angle range.

It is a cross-sectional schematic diagram of the optical element which concerns on this Embodiment. It is a typical perspective view which shows the fine grooving | roughness structure which concerns on this Embodiment. It is the plane schematic diagram and photograph which show the arrangement pattern of the fine concavo-convex structure which concerns on this Embodiment. It is a conceptual diagram which shows the mode of a fractionation. It is a conceptual diagram shown about a filling rate and an inflection point. It is a figure which shows the example of the cross-sectional profile containing the recessed part and ridge of a fine concavo-convex structure. It is a figure which shows the example of the cross-sectional profile containing the recessed part and convex part of a fine term convex structure. It is a figure which shows the example of the cross-sectional profile containing the convex part and ridge of a fine concavo-convex structure. It is a schematic diagram which shows the relationship between a unit lattice and a bottom face area | region. It is a figure which shows the depth distribution of the structure surface which consists of the recessed part and convex part of an optical element when the highest point position in the measurement area of the operation type probe microscope which concerns on Example 1 to Example 3 shall be 0 nm. 4 is an electron micrograph of an optical element according to Comparative Example 1. It is a figure which shows the wavelength dependence and incident light angle dependence of regular reflectance. It is a figure which shows the wavelength dependence and incident light angle dependence of regular reflectance. It is a figure which shows the wavelength dependence and incident light angle dependence of regular reflectance. It is a correlation diagram which shows the correlation curve of the height and filling rate in Example 1. It is a correlation diagram which shows the correlation curve of the height and filling rate in Example 2. It is a correlation diagram which shows the correlation curve of the height and filling rate in Example 3.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited to the following embodiment, In the range with the effect of this invention, it can change suitably and can implement.

<Basic structure of optical element>
FIG. 1 is a schematic cross-sectional view of an optical element 1 according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing a fine uneven structure of the optical element 1 according to the present embodiment. As shown in FIG. 1, the optical element 1 according to the present embodiment includes a base material 10 and a fine concavo-convex structure 10 a provided on the surface of the base material 10. The fine concavo-convex structure 10a includes a plurality of convex portions 11 and a plurality of concave portions 12 provided so as to continuously extend in the in-plane direction (left-right direction and depth direction in FIG. 1) of the reference surface X of the optical element 1. Have.

  The fine concavo-convex structure 10a has a height between the apex 11a of the convex portion 11 and the height of the bottom 12a of the concave portion 12 from the reference plane X between the apexes 11a of the plural convex portions 11 and the bottom 12a of the plural concave portions 12. It has a region 13 (hereinafter referred to as “ridge”) having an intermediate height. The ridge 13 is, for example, a linear region that connects the vertices 11a of the adjacent convex portions 11, and connects the regions having a height H higher than the bottom 12a of the concave portion 12 or the bottoms 12a of the adjacent concave portions 12. It is a linear region, and is a region having a height H lower than the vertex 11a of the convex portion 11. The lowermost height of the U-shaped ridge 13 connecting the vertices 11a of the convex portions 11 is 20% to 80% of the height of the convex portions 11, so that the anti-reflection performance of oblique incident light is excellent, and the convex portions 11 can be obtained. In the present specification, unless otherwise specified, the height H is a distance between the reference plane X and the object in a direction perpendicular to the reference plane X. The reference plane X is a plane that includes the lowest point of the bottoms 12 a of the plurality of recesses 12 and is substantially parallel to the surface of the substrate 10, for example. In addition, about how to take the reference plane X, it is not restricted to this.

  The vertices 11a of the plurality of convex portions 11 all have a height H of 200 nm or more from the reference plane X within a predetermined region of the fine concavo-convex structure 10a. The term “within a predetermined area” means an area having a size that can be visually confirmed. By providing the convex portion 11 in this way, not only the incident light that enters the optical element 1 from the front but also the incident light that enters from an oblique direction, the reference plane X necessary for improving the antireflection performance. Can sufficiently secure the height of the apex 11a of the convex portion 11 from above, so that an excellent antireflection performance can be expressed in a wide incident light angle range and an antireflection performance in the near-infrared wavelength region (700 to 1000 nm). Can be improved. As long as the optical element 1 is within the range where the effects of the present invention can be achieved, the height H of the vertices of all the convex portions 11 is not necessarily 200 nm or more from the reference plane X. This means that the protrusion 11 may have a defect or a protrusion 11 of less than 200 nm as long as it does not affect the antireflection performance within the predetermined area. In addition, from the viewpoint of further manifesting the above effects, the height of the vertex 11a of the convex portion 11 is preferably 200 nm or more, more preferably 260 nm or more, further preferably 300 nm or more, and 400 nm or more. It is particularly preferred. Note that “the height H of the vertex 11a of the convex portion 11 (or the bottom 12a of the concave portion 12)” refers to the vertex 11a (or the concave portion 12) of the convex portion 11 from the reference plane X in the direction perpendicular to the reference plane X of the optical element 1. The distance to the bottom 12a).

  Further, the fine concavo-convex structure 10a has an interval P (pitch) between a vertex 11a of an arbitrary convex portion 11 included in the plurality of convex portions 11 and a vertex 11a of the convex portion 11 closest to the arbitrary convex portion 11. It is less than 260 nm in plan view. By providing the convex portion 11 in this manner, the occurrence of diffraction phenomenon can be suppressed and the increase in reflectance at a specific wavelength can be suppressed, so that the antireflection performance in the visible wavelength region can be improved. The interval P between the apexes 11a of the adjacent convex portions 11 is preferably less than 230 nm and more preferably less than 200 nm from the viewpoint of further manifesting the above effects.

  Further, in the optical element 1 according to the present embodiment, in the plan view from the vertical direction in which the fine concavo-convex structure 10a is orthogonal to the reference plane X, arbitrary regularity by the plurality of convex portions 11 and the plurality of concave portions 12 is provided. Having an array pattern.

  3A and 3B are a schematic plan view and an electron micrograph showing an example of an array pattern of the fine relief structure 10a according to the present embodiment. 3A is a schematic plan view prepared based on the electron micrograph shown in FIG. 3B. 3A and 3B show an example where the arrangement pattern formed by the plurality of convex portions 11 and the plurality of concave portions 12 has a hexagonal lattice shape in plan view.

  As shown in FIG. 3A and FIG. 3B, the hexagonal lattice-like arrangement pattern refers to the convex portion with respect to any one convex portion 11 of the fine concavo-convex structure 10a in a plan view from the direction perpendicular to the reference plane X. There are six convex portions 11 closest to 11, and the six convex portions 11 form a hexagonal shape 14. In this arrangement pattern, there are four ridges 13 between an arbitrary convex portion 11-1 and six convex portions 11-2 to 11-7 adjacent to the arbitrary convex portion 11-1. Yes. Moreover, between the arbitrary convex part 11-1 and the four convex parts 11-2 adjacent to the arbitrary convex part 11-1, the convex part 11-3, the convex part 11-5, and the convex part 11-6. The ridge 13 exists in

  Thus, in the optical element 1 according to the present embodiment, the arrangement pattern by the plurality of convex portions 11 and the plurality of concave portions 12 is an N-shaped lattice in a plan view (N is 4 to 8). There are 1 to (N−2) ridges between the arbitrary convex portion 11 and the N convex portions 11 adjacent to the arbitrary convex portion. By providing the ridge 13 in this way, the ratio of the area occupied by the area higher than the height of the convex portion 11 and the target area in plan view (hereinafter also referred to as “filling rate”) is improved, so that high reflection is achieved. Prevention performance can be obtained. In addition, since the structure has a gentle refractive index gradient even with respect to light incident from an oblique direction, high antireflection performance can be obtained for a wide incident angle.

  In the optical element 1 according to the present embodiment, the N-side lattice is an array pattern formed by a plurality of convex portions 11 and a plurality of concave portions 12 and has an array shape as long as it allows a dispersion of the ridges 13. The shape of the unit cell of the pattern and the dispersion structure of the ridge 13 are not particularly limited. Examples of the N-side lattice include a tetragonal lattice, a hexagonal lattice, and an octagonal lattice. In addition, in this specification, the N-lattice shape includes a shape that can allow dispersibility within the range in which the effect of the present invention is achieved, in addition to a strict N-lattice lattice.

When the arrangement pattern is a hexagonal lattice pattern, it is preferable that a ridge 13 exists between any convex portion 11 and one to five convex portions 11 adjacent to the arbitrary convex portion 11. In this case, a ridge exists between the arbitrary convex portion 11 and the three or four convex portions 11 belonging to the six convex portions 11 adjacent to the arbitrary convex portion 11, and is adjacent to the arbitrary convex portion 11. It is more preferable that the convex portions 11 other than the three or four convex portions 11 are not adjacent to each other. In this way, the plurality of convex portions 11 or the plurality of concave portions 12 of the fine concavo-convex structure 10a are arranged in a hexagonal lattice shape in a plan view, so that the convex portions 11 are compared with the case where they are arranged in a tetragonal lattice shape. When the interval P is the same, the filling density of the protrusions 11 can be increased. As a result, the optical anisotropy due to the arrangement of the plurality of convex portions 11 and the plurality of concave portions 12 can be reduced, and a refractive index gradient can be easily formed, so that reflection is prevented in a wide region from visible light to near infrared light. Performance is improved. In addition, in this specification, the hexagonal lattice shape includes a shape capable of allowing dispersibility within the range where the effects of the present invention are exhibited, in addition to a strict hexagonal lattice.

Further, the arrangement pattern constituted by the plurality of convex portions 11 and the plurality of concave portions 12 may be a tetragonal lattice shape in plan view. The four-sided lattice-shaped array pattern has four convex portions 11 closest to the convex portion 11 for any one convex portion 11, and the four convex portions 11 form a quadrangular shape. It is an array pattern. When the arrangement pattern is a tetragonal lattice, a ridge is formed between an arbitrary convex portion 11 and two or three convex portions 11 belonging to the four convex portions 11 adjacent to the arbitrary convex portion 11. It is preferable that the convex parts 11 other than the two or three convex parts 11 are not adjacent to each other among the four convex parts 11 that are present and adjacent to the arbitrary convex part. In addition, in this specification, the tetragonal lattice shape includes a shape that can allow dispersibility within the range where the effects of the present invention are exerted, in addition to a strict tetragonal lattice shape.

  Further, when the arrangement pattern of the convex portions 11 and the concave portions 12 is a tetragonal lattice or a hexagonal lattice, the ridge 13 extends in two directions belonging to the reference plane X, and the convex portions 11 and the ridges in the two directions. It is preferable that 13 and 13 exist alternately. By providing the ridge 13 in this way, regularity occurs in the fine concavo-convex structure 10a. Due to this regularity, when the optical element 1 is manufactured by transfer from a mold having a nano pattern in which the shape of the fine concavo-convex structure 10a is inverted, it is possible to stably fill the nano pattern of the mold with resin. At the same time, the optical element 1 can be easily peeled off from the mold after the transfer. As a result, the fine concavo-convex structure 10a can be uniformly transferred to the surface of the substrate 10, and the optical element 1 having good optical performance can be obtained.

  The shape of the fine concavo-convex structure 10a is not particularly limited as long as it is a continuous structure including a plurality of convex portions 11 and a plurality of concave portions 12, and is within a range where the effects of the present invention can be obtained. Examples of the type of continuous structure include a line and space structure, a dot structure, a honeycomb structure, and a moth eye structure. Among these, it is preferable to apply a moth-eye structure, which is one of the dot structures, from the viewpoint of obtaining high antireflection performance.

  Further, the shape of the plurality of convex portions 11 and the plurality of concave portions 12 of the fine concavo-convex structure 10a is preferably any one of a substantially pyramid shape, a substantially cone shape, a substantially truncated cone shape, and a substantially truncated cone shape. Among these, the shapes of the plurality of convex portions 11 and the plurality of concave portions 12 are more preferably a substantially pyramid shape and a substantially conical shape, and more preferably a substantially conical shape. The substantially conical shape may be a true cone or an elliptical cone, and the apex 11a of the convex portion 11 or the bottom 12a of the concave portion 12 is preferably rounded. By making the apex 11a of the convex part 11 or the bottom 12a of the concave part 12 round in a substantially conical shape, the antireflection performance can be further improved. Examples of the substantially conical shape include a tent shape (a shape in which the ridge line of the convex portion 11 is dented), a bell shape (a shape in which the ridge line of the convex portion 11 swells), and a triangular shape (a shape in which the ridge line of the convex portion 11 is a straight line). It is done. From the viewpoint of obtaining excellent antireflection performance in a wide wavelength region, particularly in the near infrared wavelength region (700 to 1000 nm), the bell type is more preferable.

  In plan view from a direction perpendicular to the reference plane X of the optical element 1, the ratio of the area occupied by the region whose height from the reference plane X is 250 nm or more is 5% or more with respect to the area of the target region. Preferably there is. This target region is an arbitrary measurement target region having an area of 2 μm □ or more, including a plurality of unit cells. By setting the ratio of the area of the region having a height of 250 nm or more to 5% or more, excellent antireflection performance can be exhibited in a wide incident light angle range. Further, the ratio of the area occupied by the region whose height from the reference plane X is 250 nm or more is more preferably 10% or more, further preferably 30% or more, and further preferably 50% or more. The area ratio of the region having a height of 300 nm or more is preferably 5% or more with respect to the area of the target region, and the area ratio of the region having a height of 350 nm or more is 5% or more. More preferably, the area ratio of the region having a height of 500 nm or more is further preferably 5% or more.

Moreover, in the optical element 1, it is preferable that the average deviation of the height calculated by the following formula (1) is 3 or more and 8 or less. In the following formula (1), n is the number of fractions (number of segments) generated when the target region is fractionated into 50-nm segments from the reference plane X in the height direction. The target region refers to a region that can be measured with high accuracy by a measuring instrument such as a scanning probe microscope, and more specifically, for example, a region of 2.0 μm × 2.0 μm. However, the target area is not limited to this. In the following formula (1), Hi is the area of the region related to the i-th fraction (i-th section) in the plan view from the direction perpendicular to the reference plane X of the optical element 1. It is a ratio (fraction ratio) to occupy. Have is a value obtained by dividing the sum of ratios Hi in all fractions by n, that is, an arithmetic mean value (ΣHi / n) of each fraction ratio. The fraction ratio is rounded off to the first decimal place and up to one decimal place is used as a significant figure. Further, when the fraction ratio is zero, that is, when the fraction ratio before rounding to the second decimal place is less than 0.50%, it is treated as no fraction ratio.

  FIG. 4 is a schematic diagram showing a state of fractionation. FIG. 4 shows an example in which a region in which one convex portion 11 and one concave portion 12 exist is fractionated. However, the area related to fractionation is not limited to this. FIG. 4A is a plan view showing a state of fractionation, and FIG. 4B is a cross-sectional profile taken along line AA ′ of FIG. 4A. Here, the height of the bottom of the recess 12 is set as a reference (reference plane: 0 nm), and a region having a height up to 50 nm is set as the fraction 101 (first division). A region having a height from 50 nm to 100 nm is defined as a fraction 102 (second division). Similarly, the target area is divided (segmented) into fractions 103 to 108. In this case, since the target area is divided into 8 height sections, n is 8. Since Hi is the ratio of the area occupied by the fraction i to the area of the target region, for example, if the area of the target region is 100 and the area of the fraction 1 is 10, H1 is 10 (%).

  In the optical element 1, it is preferable that the average deviation of the height calculated using the above formula (1) is 3 or more and 8 or less. If the average deviation of the height is 3 or more, the peelability from the stamper can be maintained, so that excellent antireflection performance can be exhibited in a wide incident light angle range. If the average deviation of the height is 8 or less, excellent antireflection performance can be exhibited in a wide incident light angle range, and antireflection performance can be improved in a wide wavelength region. The average deviation in height is preferably 3 or more and 7 or less, more preferably 3 or more and 5 or less, and further preferably 3 or more and 4 or less.

  The optical element 1 has a curve (hereinafter referred to as a correlation curve) indicating a relationship between the height and a ratio of an area occupied by a region having the height or higher in plan view (hereinafter referred to as a filling rate). It is preferable to have two or more inflection points. Thus, by having two or more inflection points in the correlation curve between the height and the filling rate, the correlation curve approaches a straight line connecting the reference point of height and the point at which the height is maximum, and the inclination thereof Becomes gentle. The inclination of the correlation curve corresponds to the inclination of the fine concavo-convex structure 10a, and the correlation curve having a gentle inclination means that the inclination of the fine concavo-convex structure 10a is gentle. For this reason, by having two or more inflection points in the correlation curve, the gradient of the fine concavo-convex structure 10a can be made gentle to suppress a steep refractive index change. Thereby, antireflection performance improves.

FIG. 5 is a conceptual diagram showing the filling rate and the inflection point. 5A is a plan view of the optical element 1, and FIG. 5B is a cross-sectional view taken along the line BB ′ of FIG. 5A. FIG. 5C is a schematic diagram showing a correlation curve between height and filling rate. Figure 5A, as shown in B, the filling factor of the height Ha, the sum _{S D} of the area of the height Ha or more regions D in the plan view, the area of the target region as _{S A,} with S D / _{S A} expressed. The inflection point is a point where the increase / decrease in f ′ (x) changes when the correlation curve is a function y = f (x) of the height x and the filling rate y (the point where the increase turns to decrease). Or the point where the decrease starts to increase). For example, in FIG. 5C, with respect to x is f 'of (x) is (when x is large tangent slope is changing in the negative direction) monotonically has decreased in x ₀ smaller area, x is x _{In a} region larger than ₀ , f ′ (x) monotonously increases (when x increases, the tangent slope changes in the positive direction). That is, the increase / decrease in f ′ (x) changes at the point (x ₀ , f (x ₀ )). The point (x ₀ , f (x ₀ )) where the increase / decrease in f ′ (x) changes is called an inflection point. Note that a minute change in shape in the range of 10 nm or less is negligible.

  In the optical element 1, the standard deviation of the recess depth of the recess 12 (that is, the height from the reference plane X to the bottom 12 a of the recess 12) is preferably 3 or more and 20 or less. Moreover, in the optical element 1, it is more preferable that the standard deviation of the convex part height of the convex part 11 (that is, the height of the vertex 11a of the convex part 11) is 3 or more and 20 or less. By making the concave depth of the concave portion 12 or the convex portion height of the convex portion 11 within the above range, the reflectance prevention characteristic can be further improved.

  In addition, when the standard deviation of the concave part depth of the concave part 12 and / or the convex part height of the convex part 11 is 3 or more and 20 or less, the reference point and the height of the height are maximum in the correlation curve and the correlation curve. Are compared with the straight line connecting the correlation curve and the straight line near the reference point of height and the point where the height is maximum. Therefore, as described above, by forming the fine concavo-convex structure 10a so that two or more stop points appear in the correlation curve, the correlation curve and the straight line approach each other, and a gentle correlation curve without a sharp refractive index change is obtained. Anti-reflection performance is improved.

  Since the optical element 1 according to the present embodiment has the ridge 13 as described above, the physical strength of the optical element 1 against bending is increased, and it can be applied to a flexible display having a curved screen. By applying the optical element 1 to a flexible display or the like, high antireflection performance can be obtained in a wide wavelength region. The average height of the ridges 13 is preferably 20% or more and 80% or less with respect to the average height of the protrusions 11. By making the average value of the heights of the ridges 13 within the above range, the optical element 1 having a good balance between the strength of the optical element 1 against bending and the antireflection performance can be realized. The average height of the ridges 13 is more preferably 30% or more and 70%, and further preferably 35% or more and 60% or less.

  Further, in the optical element 1, there are four or eight ridges 13 in an arbitrary unit cell composed of an arbitrary convex portion 11 and a plurality of convex portions 11 closest to the arbitrary convex portion 11. Is preferred. With this configuration, the antireflection performance can be further improved.

  Moreover, it is preferable that the direction where the ridge 13 exists and the direction where the ridge 13 does not exist coexist in the fine concavo-convex structure 10a. That is, it is preferable that a cross section where the ridge 13 appears and a cross section where the ridge 13 does not appear coexist. By taking such a structure, the antireflection performance can be further improved.

  FIG. 6 is a diagram illustrating an example of a cross-sectional profile of the concavo-convex structure in a cross-section 30 (a cross-section in which a ridge exists) composed of the concave portion 12 and the ridge 13. In the cross section 30 shown in FIG. 6, the bottom 12 a and the ridge 13 of the recess 12 can be confirmed. FIG. 7 is a diagram illustrating an example of a cross-sectional profile of the fine concavo-convex structure 10a in a cross-section 31 (a cross-section having no ridge) formed by the convex portions 11 and the concave portions 12. In FIG. In the cross section 31 shown in FIG. 7, the apex 11a of the convex part 11 and the bottom 12a of the concave part 12 can be confirmed. FIG. 8 is a diagram illustrating an example of a cross-sectional profile of the fine concavo-convex structure 10a in a cross-section 32 (a cross-section in which a ridge exists) including the convex portion 11 and the ridge. In the cross section 32 shown in FIG. 8, the vertex 11a and the ridge 13 of the convex part 11 can be confirmed. 6, 7 and 8, the scale in the height direction is the same.

  In the optical element 1, in the unit lattice of the fine concavo-convex structure 10a, the ratio (Sb / Sall) between the area (Sall) of the unit lattice and the sum (Sb) of the area of the bottom region having a height of 10 nm or less from the reference plane X Is preferably 10% or less. By setting the ratio (Sb / Sall) to 10% or less, antireflection performance in a wide wavelength region can be improved. FIG. 9 schematically shows the relationship between the unit cell and the bottom region. The ratio (Sb / Sall) is more preferably 5% or less, further preferably 3% or less, and most preferably the bottom region is a point. The lower limit of the ratio (Sb / Sall) is about 0.1% due to the limit of the manufacturing accuracy of the optical element 1, but the smaller the ratio (Sb / Sall) is, the more preferable it is to be 0.1% or less. Is particularly preferred.

  The area (Sall) of the unit cell can be determined by, for example, a surface SEM micrograph. In addition, the area (Sb) of the bottom surface region of the recess 12 can be obtained using, for example, a scanning probe microscope. The area of the bottom area is the area in plan view.

  The uniformity of the height of the ridge 13 is the average value (Kave) of the height of the ridge 13 with respect to the reference plane X (height = 0 nm) and the height of the ridge (Kj) at an arbitrary point j. It is represented by an arithmetic average value of absolute values of differences (| Kave−Kj |). In the optical element 1, the height uniformity of the ridge 13 is preferably 60% or less, more preferably 40% or less, further preferably 20% or less, and most preferably 10% or less. When it is 60% or less, the antireflection performance can be improved. The height uniformity of the ridge 13 can be calculated from 100 or more measured values by measuring the height of the ridge 13 with a scanning probe microscope.

  In the optical element 1, when the arrangement pattern of the convex portions 11 or the concave portions 12 is a hexagonal lattice, the apex 11a of the arbitrary convex portion 11 (or the bottom 12a of the concave portion 12) and the six convex portions 11 closest to the apex 11a. Of the interval P between the apex 11a (or the bottom 12a of the recess 12), the difference between the maximum value (Pmax) of the interval P and the minimum value (Pmin) of the interval P is the average value (Pave) of the interval P. The divided value [(Pmax−Pmin) / Pave] is preferably 20% or less, and by setting the value of (Pmax−Pmin) / Pave to 20% or less, the array pattern of the convex portion 11 or the concave portion 12 is reduced. Increase regularity. This means that the shape of the unit cell approaches a regular hexagon. Thus, the anisotropy of the antireflection performance of the optical element can be suppressed by increasing the regularity of the arrangement pattern of the convex portions 11 or the concave portions 12. The value of (Pmax−Pmin) / Pave is more preferably 15% or less, and further preferably 10% or less.

  Moreover, when the arrangement pattern of the convex part 11 or the recessed part 12 is a tetragonal lattice, the vertex 11a (or bottom 12a of the recessed part 12) of arbitrary convex parts 11 and the vertex 11a of the four convex parts 11 nearest to this (or A value obtained by dividing the difference between the maximum value (Pmax) of the interval P and the minimum value (Pmin) of the interval P by the average value (Pave) of the interval P among the intervals P between the bottom 12a) of the recess 12 [ (Pmax−Pmin) / Pave] is preferably 20% or less. By setting the value of (Pmax−Pmin) / Pave to 20% or less, the regularity of the arrangement pattern of the convex portions 11 or the concave portions 12 is increased. This means that the shape of the unit cell approaches a square. Thus, the anisotropy of the antireflection performance of the optical element can be suppressed by increasing the regularity of the arrangement pattern of the convex portions 11 or the concave portions 12. The value of (Pmax−Pmin) / Pave is more preferably 15% or less, and further preferably 10% or less.

  In the optical element 1, the average value of the aspect ratio (H / P) defined by the ratio of the pitch P and the height H in the convex portion 11 having a height of 200 nm or more is preferably 0.67 or more and 10 or less, and preferably 1 or more and 5 or more. The following is preferred. By making the average value of the aspect ratio 0.67 or more, the antireflection performance can be improved, and by making the average value of the aspect ratio 10 or less, the releasability from the stamper can be maintained at the time of producing the optical element, and the fine unevenness An optical element having a small average deviation of the height of the structure 10a can be obtained.

  Next, materials used for the optical element 1 according to the above embodiment will be described in detail.

<Base material>
The base material 10 used for the optical element 1 has (a) good adhesion to the composition constituting the fine relief structure 10a, and (b) a difference in refractive index from the composition constituting the fine relief structure 10a. That it is small and (c) the haze of the composition layer constituting the fine relief structure 10a is required to be small. Further, the substrate 10 has (d) flexibility, (e) easy processability, (f) high productivity, (g) light weight, and (h) high impact resistance. And (i) low cost.

  Examples of materials that satisfy the requirements (a) to (c) include glass and resin. In addition to the requirements (a) to (c) above, a resin that satisfies the requirements (d) to (g) above may be used. In addition, the base material used for the optical element 1 is not limited to this. An inorganic material such as glass, ceramic and metal, and an organic material such as resin can be arbitrarily selected according to the purpose of use and application.

  The optical element 1 may be required to be transmissive or non-transmissive. For this reason, it is desirable to select the type of the base material 10 according to the purpose and application. When transparency is required, the substrate 10 needs to be substantially transparent in the target wavelength region. In this case, it is preferable to use a transparent resin or glass as the substrate 10. In the case where further flexibility is required, it is preferable to use a transparent resin as the substrate 10. Moreover, when non-transparency is required, the base material needs to be opaque in the target wavelength region. In this case, it is preferable to use ceramic, metal, or opaque resin as the substrate 10. Further, in order to satisfy the above requirements (d) to (g), it is preferable to use an opaque resin.

  Examples of the transparent resin include polymethyl methacrylate resin (PMMA resin), acrylic resin, polycarbonate resin (PC resin), polystyrene resin (PS resin), methyl methacrylate-styrene resin (MS resin), and styrene resin. Resin, cycloolefin resin (COP resin), polyarylate resin, polyetherimide resin, polyethersulfone resin, polysulfone resin, polyetherketone resin, polyethylene terephthalate resin (PET resin), polyethylene naphthalate resin (PEN resin) , Polytrimethylene terephthalate resin, aromatic polyester resin, triacetyl cellulose resin (TAC resin), polyimide resin, acrylic-based, epoxy-based, urethane-based ultraviolet curable resin and thermosetting resin. . Among these, PMMA resin, acrylic resin, PC resin, PS resin, styrene resin, COP resin, PET resin, PEN resin, aromatic polyester resin, and TAC resin are particularly preferable.

  Examples of the opaque resin include ABS (acrylonitrile / butadiene / styrene) resin, AAS (acrylonitrile / acrylic rubber / styrene) resin, AES (acrylonitrile / ethylene-propylenediene / styrene) resin, ACS (acrylonitrile / chlorinated polyethylene).・ Styrene) resin, rubber-containing styrene resin, rubber-containing acrylic resin, polyamide resin, polyacetal resin, polyethylene resin, cross-linked polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyphenylene ether resin, modified polyphenylene ether resin, polybutylene terephthalate Resin etc. are mentioned. Further, as the opaque resin, ABS resin (or AAS resin, AES resin, ACS resin, rubber-containing styrene resin) / polyamide resin, ABS resin (or AAS resin, AES resin, ACS resin, rubber-containing styrene resin) (Resin) / acrylic resin.

  In the case where the substrate 10 is a resin, an additive may be used as necessary as long as the target requirements are not impaired. The additive may be directly contained in the resin, or may be formed as another layer on the surface of the substrate 10 made of the resin. Examples of the additive include organic particles, inorganic particles, plasticizers, antioxidants, ultraviolet absorbers, antistatic agents, antifogging agents, and easy adhesives.

  In order to improve the impermeability of the optical element 1, a black pigment and / or dye may be contained in the resin of the base material 10. Further, a black paint may be applied to the non-formed surface of the fine uneven structure 10a.

  In addition, a barrier resin layer may be formed by coating or the like on the surface of the substrate 10 made of resin within a range that does not impair the intended requirements. By forming a barrier resin layer on the surface of the substrate 10 made of resin, the substrate 10 can be protected from deterioration factors such as heat, light, moisture, oxygen, carbon dioxide, nitrogen, and hydrogen. .

  When the substrate 10 is glass, surface treatment such as silane coupling agent, primer treatment, or UV treatment may be performed. These surface treatments may be used in combination.

  Moreover, as the base material 10, you may use what the surface coating, the contact bonding layer, and the interference reduction layer are formed.

  As a shape of the base material 10, a board, a sheet, a film, a thin film, a woven fabric, a nonwoven fabric, other arbitrary shapes, and what combined these can be suitably selected according to the intended purpose. When flexibility is required, the substrate 10 is preferably a sheet, a film, a thin film, a woven fabric, or a non-woven fabric.

  The thickness of the base material 10 can be appropriately selected according to the purpose of use. When the optical element 1 is required to be thin or flexible, the thickness of the substrate 10 is preferably 350 μm or less, more preferably 120 μm or less, further preferably 80 μm or less, and 40 μm or less. Most preferably. Moreover, it is preferable that the thickness of the base material 10 is 10 micrometers or more from the point of the ease of handling.

<Composition constituting the fine relief structure>
The fine relief structure 10a of the optical element 1 is composed of a composition. As a kind of composition which comprises the fine concavo-convex structure 10a, it can select from a photocuring composition, a thermosetting composition, a thermoplastic composition, etc. suitably. Among these, as a composition which comprises the fine concavo-convex structure 10a, a photocurable composition is preferable from the viewpoint of transfer fidelity.

  The types of monomers and oligomers (hereinafter also referred to as monomer components) in the photocurable composition used for the fine concavo-convex structure 10a are radical polymerization monomers from the viewpoint of reaction rate and continuous productivity. Ingredients are more preferred. In addition, from the viewpoint of increasing the reactivity of the stamper in the deep part of the concavo-convex structure pattern, a cationic polymerization monomer component having a long reaction lifetime may be mixed with the radical polymerization monomer. As the cationic polymerization monomer for photocuring, a monomer having an epoxy group, a vinyloxy group, an oxetanyl group, an oxazolyl group or the like as a polymerizable functional group is preferable.

  Examples of the radical monomer component include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate, isoamyl acrylate, n-lauryl acrylate, and isomyristyl acrylate. , Stearyl acrylate, n-butoxyethyl acrylate, butoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxypolyethylene glycol acrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, caprolactone acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate The Noxyethyl acrylate, isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentanyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, diethylaminoethyl acrylate, Dimethylaminoethyl acrylate quaternized product, acrylic acid, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl 2-hydroxyethyl Phthalic acid, neopentyl glycol acrylic acid benzoate, 2-acryloyloxyethyl 2-hydroxypropyl phthalate, glycidyl acrylate, 2 Acryloyloxyethyl acid phosphate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, PEG # 200 diacrylate, PEG # 400 diacrylate, PEG # 600 diacrylate, 1,4-butanediol diacrylate, neo Pentyl glycol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol Diacrylate, 1,10-decanediol diacrylate, glycerin diacrylate, 2-hydroxy-3-acryloyloxypropyl acrylate, bisphenol A-EO adduct di Acrylate, trifluoroethyl acrylate, tetrafluoropentyl acrylate, octafluoropentyl acrylate, perfluorooctyl ethyl acrylate, nonylphenol-EO adduct acrylate, dimethylol tricyclodecane diacrylate, trimethylolpropane acrylic acid benzoate, hydroxypivalic acid Neopentyl glycol diacrylate, tetrafurfuryl alcohol oligoacrylate, ethyl carbitol oligoacrylate, 1,4-butanediol oligoacrylate, 1,6-hexanediol oligoacrylate, trimethylolpropane oligoacrylate, pentaerythritol oligoacrylate, pentamethyl Piperidyl acrylate, tetramethylpiperidyl acrylate , Paracumylphenol-EO modified acrylate, N-acryloyloxyethyl hexahydrophthalimide, isocyanuric acid-EO modified diacrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl Methacrylate, isodecyl methacrylate, isoamyl methacrylate, n-lauryl methacrylate, isomyristyl methacrylate, stearyl methacrylate, n-butoxyethyl methacrylate, butoxydiethylene glycol methacrylate, methoxytriethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, tripropylene glycol dimethacrylate, tetraethylene Glico Rudimethacrylate, caprolactone methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, dicyclopentanyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxypropyl methacrylate, diethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate quaternized product, methacrylic acid, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl hexahydrophthalic acid , 2-methacryloyloxy Ethyl phthalic acid, 2-methacryloyloxyethyl 2-hydroxyethyl phthalic acid, neopentyl glycol methacrylic acid benzoate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, glycidyl methacrylate, 2-methacryloyloxyethyl acid phosphate, Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, PEG # 200 dimethacrylate, PEG # 400 dimethacrylate, PEG # 600 dimethacrylate, 1,4-butanediol dimethacrylate, neopentylglycol dimethacrylate, 3- Methyl-1,5-pentanediol dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol dimethacrylate 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, bisphenol A-EO addition Dimethacrylate, trifluoroethyl methacrylate, tetrafluoropentyl methacrylate, octafluoropentyl methacrylate, perfluorooctyl ethyl methacrylate, nonylphenol-EO adduct methacrylate, dimethylol tricyclodecane dimethacrylate, trimethylolpropane methacrylic acid benzoate, hydroxy Pivalic acid neopentyl glycol dimethacrylate, tetrafurfuryl alcohol oligomethacrylate, Tylcarbitol oligomethacrylate, 1,4-butanediol oligomethacrylate, 1,6-hexanediol oligomethacrylate, trimethylolpropane oligomethacrylate, pentaerythritol oligomethacrylate, pentamethylpiperidylmethacrylate, tetramethylpiperidylmethacrylate, paracumylphenol-EO Modified methacrylate, N-methacryloyloxyethyl hexahydrophthalimide, isocyanuric acid-EO modified dimethacrylate, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis {[(3-ethyloxetane-3-yl) methoxy] Methyl} benzene, 3-ethyl-3-{[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 3-ethyl-3- (2-ethyl) Hexyloxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3- (cyclohexyloxy) methyloxetane, oxetanylsilsesquioxane, oxetanyl silicate, phenol novolak oxetane, 1,3-bis [ (3-ethyloxetane-3-yl) methoxy] benzene and the like.

  The composition of the fine concavo-convex structure 10a is composed of three or more acrylic groups and / or methacrylic groups in one molecule in a total of 100 parts by mass of monomer components in the composition constituting the fine concavo-convex structure 10a. One or more kinds of monomer components are 20 to 60 parts by mass, the monomer component having an N-vinyl group is 5 to 40 parts by mass, and the other monomer components are 0 to 75 parts by mass. It is preferable. By setting the content of one or more monomer components having three or more acrylic groups and / or methacrylic groups in one molecule to 20 parts by mass or more, the composition portion constituting the fine concavo-convex structure 10a is high. Since the strength and the crosslink density are high, bleeding out of unreacted monomers and low polymerization degree oligomers from the composition part constituting the fine concavo-convex structure 10a and generation of by-products can be minimized. . Moreover, the viscosity of the composition which comprises the fine concavo-convex structure 10a by making content of 1 or more types of monomer components which have 3 or more acryl group and / or methacryl group in 1 molecule into 60 mass parts or less. The rise can be suppressed, and a decrease in the filling rate of the composition into the uneven pattern of the stamper can be prevented. The content of one or more monomer components containing three or more acrylic groups and / or methacryl groups in one molecule is 100 parts by mass in total of the monomer components in the composition constituting the fine relief structure 10a. Among them, the content is more preferably 25 parts by mass to 50 parts by mass, and further preferably 30 parts by mass to 40 parts by mass.

  Examples of monomer components containing three or more acrylic groups and / or methacrylic groups in one molecule include trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, and pentaerythritol. Triacrylate, propoxylated glyceryl triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris (2-hydroxyethyl) isocyanurate triacrylate , Trisacryloyloxyethyl phosphate, trifunctional or higher polyester acrylate Oligomer, trifunctional or higher urethane acrylate oligomer, trifunctional or higher epoxy acrylate oligomer, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane trimethacrylate, propoxylated trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, Propoxylated glyceryl trimethacrylate, pentaerythritol tetramethacrylate, ethoxylated pentaerythritol tetramethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, tris (2-hydroxyethyl) isocyania Nurate trimethacrylate, trismethacrylo Oxyethyl phosphate, tri- or higher-functional polyester methacrylate oligomer, trifunctional or higher urethane methacrylate oligomer, and the like trifunctional or more epoxy methacrylate oligomer. Here, the ethoxylated and propoxylated monomer component refers to a monomer component containing 1 to 20 equivalents of one or more ethoxy groups and / or propoxy groups per monomer molecule.

  Among the monomer components containing three or more acrylic groups and / or methacrylic groups in one molecule, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, trimethylolpropane Trimethacrylate, ethoxylated trimethylolpropane trimethacrylate, and propoxylated trimethylolpropane trimethacrylate are preferred because of a good balance of physical properties. Among these, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate are more preferable because they are excellent in the release property of the cured molded product from the cured stamper. One type or two or more types of monomer components containing three or more acrylic groups and / or methacrylic groups in one molecule may be used.

  The monomer component having an N-vinyl group is more preferably contained in an amount of 15 to 38 parts by mass in 100 parts by mass of the monomer components in the composition constituting the fine relief structure 10a, and 25 parts by mass. It is more preferable to contain -35 mass parts. By containing 5 parts by mass or more of the monomer component having an N-vinyl group, the adhesion of the molded body to the base material can be improved, and the mold release from the stamper of the molded body after curing is improved. In addition, by containing 40 parts by mass or less, bleed out can be suppressed to a minimum from the molded body of the unreacted monomer and the low polymerization degree oligomer, and excessive moisture absorption of the molded body can be suppressed. Moisture resistance can be improved.

  As the monomer component having an N-vinyl group, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, and N-vinylcaprolatum are particularly preferably used. One or more kinds of monomer components having an N-vinyl group may be used.

<Silicon compounds>
The composition constituting the fine concavo-convex structure 10a may contain a silicon compound containing an acryl group and / or a methacryl group. It is preferable to contain 0.1 to 10 parts by mass of a silicon compound containing an acryl group and / or a methacryl group with respect to 100 parts by mass of the total monomer components of the composition constituting the fine relief structure 10a. It is more preferable to contain 2-5 mass parts, and it is still more preferable to contain 0.3-2 mass parts. By containing 0.1 part by mass or more, the releasability of the cured optical element from the stamper can be further improved, and by containing 10 parts by mass or less, the composition constituting the fine concavo-convex structure 10a of the optical element 1 The strength of the layer, particularly the fine relief structure 10a can be maintained.

  As a kind of silicon compound containing an acryl group and / or a methacryl group, for example, a silicon acrylate compound can be exemplified. BYK-UV3500, BYK-UV3570 (manufactured by Big Chemie Japan) and ebecyl350 (manufactured by Daicel-Cytech), which have an acrylic group bonded to the polydimethylsiloxane skeleton, constitute the fine relief structure 10a of the optical element 1 after curing. The bleed-out from the composition layer is less and more preferable.

<Photopolymerization initiator>
When using a photocurable composition as a composition which comprises the fine concavo-convex structure 10a, a photoinitiator can be contained. Examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Benzophenone, 1-hydroxycyclohexyl phenyl ketone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [ 4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propane, phenylglyoxylic acid methyl ester, 2-methyl-1- [4- (methylthio) phenyl] -2 -Morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinof Nyl) -butanone, 1,2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one, bis (2,4,6 -Trimethylbenzoyl) -phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (η5-2,4-cyclopentadiene -1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, 1,2-octanedione, 1- [4- (phenylthio) -2- (O -Benzoyloxime)] ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] -1- (O In the present invention, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1,2-octanedione, 1- [4- (oxy-oxime), etc. (Phenylthio) -2- (O-benzoyloxime)] ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] -1- (O-acetyloxime) and the like. It can be preferably used. The blending ratio of the photopolymerization initiator is preferably 0.1 parts by mass to 5.0 parts by mass with respect to 100 parts by mass of the total monomer components in the photocuring composition. These photopolymerization initiators can be applied alone, but can also be used in combination of two or more.

<Photosensitizer>
When using a photocurable composition as a composition which comprises the fine concavo-convex structure 10a, it can also be used for a photocurable composition in combination with a photoinitiator, a photosensitizer, etc. For example, photosensitizers include n-butylamine, di-n-butylamine, tri-n-butylphosphine, allylthiourea, s-benzisoisouronium-p-toluenesulfinate, triethylamine, diethylaminoethyl methacrylate, Triethylenetetramine, 4,4′-bis (dialkylamino) benzophenone, N, N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanol Photosensitizers such as amines such as amines can be used alone or in combination of two or more.

<Filtration of photocuring composition>
When using a photocurable composition as a composition which comprises the fine concavo-convex structure 10a, it is preferable that a photocurable composition removes a foreign material by methods, such as filtration. The filter pore size used for filtration is more preferably 1 μm or less, and further preferably 0.5 μm or less. The foreign matter capturing efficiency of the filter is preferably 99.9% or more. By removing the foreign matter, the filling rate of the uneven portion of the stamper and the photocuring reaction rate can be improved, and the structural defects of the fine uneven structure 10a of the optical element 1 can be reduced to a level where there is no practical problem.

<Viscosity of photocuring composition>
When using a photocurable composition as a composition which comprises the fine concavo-convex structure 10a, it is preferable that the viscosity at 50 degreeC of the photocurable composition before hardening is 100 mPa * s or less. When the photocurable composition is applied to the substrate surface by a roll-to-roll method by setting the viscosity to 100 mPa · s or less, the thickness uniformity of the photocurable composition layer can be improved, and the uneven structure portion of the stamper It is possible to increase the filling rate of the photocuring composition into the optical element, and as a result, it is possible to increase the transfer fidelity to the optical element. The viscosity is more preferably 50 mPa · s or less, and further preferably 20 mPa · s. In addition, in order to obtain the desired thickness of the photocurable composition layer, the viscosity is appropriately adjusted within the viscosity range of the substrate by further adding a thickener or thickener to the photocurable composition. May be.

<Stamper surface temperature>
When using a photocurable composition as a composition constituting the fine concavo-convex structure 10a, the surface temperature of the concavo-convex structure surface of the stamper used for manufacturing the optical element 1 is preferably 25 ° C to 100 ° C, and 30 ° C to 80 ° C. More preferably, 35 ° C to 70 ° C is more preferable, and 40 ° C to 65 ° C is most preferable. Since the viscosity of the photocurable composition can be lowered by setting the surface temperature of the concavo-convex structure surface of the stamper to 25 ° C. or higher, the adhesion between the base material and the photocurable composition, and the optical element 1 after photocuring The mold releasability from the stamper can be improved. Moreover, the thermal deformation of a base material can be suppressed by making the surface temperature of the uneven | corrugated structure surface of a stamper into 100 degrees C or less. The surface temperature of the concavo-convex structure surface of the stamper is preferably adjusted to be substantially constant.

  As a means for adjusting the surface temperature substantially constant, a stamper with a temperature controller can be used. By maintaining the surface temperature of the concavo-convex structure surface of the stamper constant, the viscosity of the composition constituting the concavo-convex part can also be kept constant, thereby increasing the uniformity of the thickness of the composition layer constituting the concavo-convex part. Transfer fidelity from the stamper to the optical element 1 can be improved.

<Thickness of the composition layer constituting the fine relief structure>
The thickness of the composition layer constituting the fine concavo-convex structure 10a is preferably 0.4 μm to 10 μm. By setting the thickness to 10 μm or less, curling can be suppressed and cracks when bent can be suppressed. By increasing the thickness of the composition layer to 0.4 μm or more, the adhesion between the base material and the composition constituting the concavo-convex portion is improved, and an untransferred portion is generated when the concavo-convex structure of the stamper is transferred to the base material. Can be prevented. In addition, by setting the thickness of the composition layer constituting the concavo-convex portion to 4 μm or less, the occurrence of cracks in the composition layer constituting the concavo-convex portion generated under high temperature and high humidity conditions and the concavo-convex portion under high temperature and high humidity Curling due to shrinkage of the composition can be suppressed. The thickness of the resin layer is more preferably 0.5 μm to 7 μm, and further preferably 0.8 μm to 4 μm.

  The thickness of the composition layer constituting the fine relief structure 10a is adjusted by the pressing pressure between the base material and the stamper, the surface temperature of the relief structure surface of the stamper, the temperature and viscosity of the composition constituting the fine relief structure 10a, etc. can do.

<Preparation method of original plate>
Examples of a method for producing an optical element original plate used for manufacturing the optical element 1 include an interference exposure method using a laser beam, an electron beam drawing method, a machining cutting method, a dry etching method, and a lithography method. A production method can be arbitrarily selected according to the shape, pitch, or height of the concavo-convex portion, the arrangement pattern of the concavo-convex portion, regularity / irregularity thereof, the size of the original plate, cost, and the like. When it is desired to obtain an original plate having a regular pattern with uneven portions and a large area, an interference exposure method using laser light is preferable.

  The interference exposure method is an exposure method using interference fringes formed by irradiating laser light of a specific wavelength from two directions of angle θ ′, and the wavelength of the laser used by changing angle θ ′. The structure of the concavo-convex lattice having various pitches can be obtained within the range limited by the above. Examples of the laser that can be used for the interference exposure include a TEM00 mode laser. Examples of the ultraviolet laser capable of oscillating a TEM00 mode laser include an argon laser (wavelengths 364 nm, 351 nm, and 333 nm) and a fourth harmonic wave (wavelength 266 nm) of a YAG laser.

  Examples of the material of the original plate include quartz materials such as quartz glass, ultraviolet transmissive glass, sapphire, diamond, and polydimethylsiloxane, fluororesin, silicon wafer, SiC substrate, mica substrate, and the like. it can.

  In order to further improve the releasability at the time of transferring the nano pattern, the original plate may be subjected to a release treatment. As the release treatment agent, a silane coupling release agent is preferable, and a fluorine-containing release agent is more preferable. Examples of commercially available release agents include Daikin Industries, Ltd. OPTOOL DSX, Durasurf HD1101 and HD2101, Sumitomo 3M Novec, Shin-Etsu Chemical KP-801M, KBM-7103, Momentive Performance Examples include TSL-8257 manufactured by Materials Japan.

<Production method of stamper>
The stamper to which the concavo-convex structure and the array pattern of the original plate are transferred can be produced from the original plate by an electroforming method or the above-described nanoimprint method. From the viewpoint of resolution, an electroforming method and an optical nanoprint method using a photocuring composition are preferable.

  Further, the transfer can be repeated by the nanoimprint method. By repeating the transfer, (1) a plurality of transferred concavo-convex structure pattern transfer products can be produced, and / or (2) an inverted transfer mold in which the concavo-convex pattern is reversed can be obtained.

<Method for producing optical element>
The optical element 1 can be produced by transferring from an original plate or stamper having the concavo-convex structure pattern. As a manufacturing method of the optical element 1, a nanoimprint method is preferable. Examples of the nanoimprint method include microcontact printing (soft lithography), room temperature nanoimprint, reverse nanoimprint, thermal nanoimprint, and optical (UV) nanoprint. Examples of the resin that forms the fine concavo-convex structure 10a include a photocurable composition, a thermosetting composition, a thermoplastic composition, a sol-gel reaction product, etc., but in terms of resolution, overlay accuracy, and continuous transferability, The optical nanoimprint method using a curable composition is more preferable. Moreover, the thermal nanoimprint method using a thermoplastic composition is preferable in that it can be mass-produced with a simple and inexpensive apparatus. As the molding method of the thermal nanoimprint method, extrusion molding (transferring the concavo-convex structure surface of the embossing roll), cast molding method (transferring the concavo-convex structure surface of the embossing roll), press molding method, injection molding method and the like are preferable.

<Method for applying photocurable composition>
Examples of the method for applying the photocurable composition to the substrate in the optical nanoimprint method include a roll coater method, a (micro) gravure coater method, an air doctor coater method, a blade coater method, a knife coater method, a rod coater method, and a curtain ( Flow) coater method, kiss coater method, bead coater method, cast coater method, rotary screen method, dip coating method, slot orifice coater method, barcode method, spray coating method, spin coating method, extrusion coater and the like. In order to increase productivity and obtain an optical element with a large area, it is preferable to use a roll-to-roll method and select a coating method as appropriate from the above to obtain a film roll containing the optical element. The roll-to-roll method is preferable because it is superior to the batch method in that the standard deviations of productivity and the height of the convex portion 11 and the height of the concave portion 12 are controlled to 20 or less.

<Resin roll>
Moreover, it is preferable that the resin film roll containing the optical element 1 manufactured by the roll-to-roll method has a width of 10 cm or more and a length of 50 m or more. The roll width is more preferably from 10 cm to 200 cm, further preferably from 20 cm to 200 cm, and most preferably from 50 cm to 200 cm. The roll length is more preferably 50 m or more and 10,000 m or less, further preferably 200 m or more and 10,000 m or less, and most preferably 500 m or more and 10,000 m or less. By setting the width of the resin film roll to 10 cm and a length of 50 m or more, it is possible to provide a large amount of optical elements 1 having various sizes from small to large. When the roll width exceeds 200 cm, the thickness uniformity of the composition layer constituting the fine concavo-convex structure may decrease, and when the roll length exceeds 10,000 m, the winding accuracy decreases due to the shaft shake of the roll winder. In some cases, the roll strength increases and the roll winder has insufficient shaft strength and may be damaged. For this reason, it is desirable to set it as the resin film roll of the said width | variety and length.

<Application order>
When using a photocurable composition as a composition constituting the fine concavo-convex structure 10a, as a method for producing the optical element 1, the photocurable composition of the substrate is applied after the photocurable composition is applied to the substrate in the form of a thin film. There is a method in which a photocurable composition is filled between the uneven structure surface of the stamper and the substrate by bringing the object application surface and the uneven structure surface of the stamper into contact with each other, and then UV irradiation is performed. Further, there is a method in which a photocurable composition is applied to the concavo-convex structure surface of the stamper, the concavo-convex structure of the stamper is filled, and then contacted with a substrate, and then UV irradiation is performed. Also, after the photocurable composition is applied in a thin film on both the base material and the uneven structure surface of the stamper, the photocurable composition application surface of the base material and the uneven structure surface of the stamper are brought into contact with each other, and then UV irradiation is performed. There is a way. Depending on the application method to be selected, the order of application can be appropriately selected.

<Exposure light source>
As the type of exposure light source used for photocuring in the production of the optical element of the present invention, a metal halide lamp, a high-pressure mercury lamp, a chemical lamp, a UV-LED, and an electrodeless UV lamp are preferable. Further, from the viewpoint of suppressing heat generation during long exposure, it is preferable to use a filter (including a bandpass filter) that cuts a wavelength longer than the visible wavelength.

The integrated light quantity of the exposure light source, is preferably 300 mJ / cm ² or more, in order to increase the light curing reaction rate of the photocurable ^composition, more preferably ^{800mJ / cm 2 ~6000mJ / cm 2} , to prevent resin degradation due to ^light, further preferably ^{800mJ / cm 2 ~3000mJ / cm 2} .

<Protective film>
You may bond a protective film with respect to the surface which has the fine uneven structure 10a of the optical element 1, and / or the surface which does not have the fine uneven structure 10a. By sticking the protective film, the shape of the fine concavo-convex structure 10a can be protected and adhesion of foreign matters can be prevented until the protective film is peeled off for use. The performance required for the protective film is as follows: (1) At the time of peeling, the adhesive layer of the protective film does not remain on the surface having the fine concavo-convex structure 10a, or even if it remains, it does not affect the reflectance and transmittance. ) It should not contain foreign substances that damage the surface of the optical element 1 having the fine concavo-convex structure 10a, or it will not affect the reflectance or transmittance even if it is damaged. The optical element 1 can be arbitrarily selected from protective films having the above performance.

<Refractive index>
The refractive index difference between the composition layer constituting the substrate 10 and the fine relief structure 10a is preferably 0.2 or less, more preferably 0.1 or less, in order to reduce refraction or reflection at the interface between the two. 0.05 or less is more preferable, and 0.02 or less is most preferable. Moreover, you may add the intermediate | middle layer which has adhesiveness between the base material 10 and the composition layer which comprises the fine concavo-convex structure 10a. By setting the refractive index of the intermediate layer between the refractive indexes of the base material 10 and each of the composition layers constituting the fine relief structure 10a, interference can be reduced compared to the case where there is no intermediate layer, and interference fringes are generated. Can be suppressed.

  Moreover, when the adhesion layer is provided to the base material 10, the refractive index difference of the base material 10 and the adhesion layer is also preferably 0.2 or less, more preferably 0.1 or less, for the same reason as described above. 05 or less is more preferable, and 0.02 or less is most preferable.

<Total light transmittance, haze>
When the optical element 1 requires transparency, the haze of the optical element 1 having the fine concavo-convex structure 10a, the haze of the base material alone, and the value obtained by subtracting the haze of the base material 10 from the haze of the optical element 1 (hereinafter referred to as Δhaze) ) Is preferably 1.5% or less, more preferably 1.0% or less, and even more preferably 0.5% or less when the fine relief structure 10a is formed only on one side. In particular, in order to reduce Δhaze to 1.5% or less, it is effective to give the surface of the base material 10 an uneven shape having antireflection performance in addition to setting the refractive index difference to 0.2 or less. It is. By reducing Δhaze, the total light transmittance of the optical element 1 can be improved.

  Haze is defined as the ratio of diffuse transmittance to total light transmittance. A small haze means that the amount of diffused light is small when light passes through the optical element 1, in other words, the ratio of the linear transmittance to the total light transmittance is high. When a transparent base material is used for the optical element 1, since refraction and reflection can be reduced at the interface, the haze is reduced and the total light transmittance is increased, so that the apparent transparency of the optical element 1 is increased.

<Reflectance>
The antireflection performance can be evaluated by regular reflectance and (positive + diffuse) reflectance. It is preferable that these values are all low.

<Application>
The optical element 1 can be used for any purpose or application. For example, when the optical element 1 is used in a display device such as a display device, the haze is reduced and the total light transmittance is increased, so that a clear image can be visually recognized. When the optical element 1 is used for a solar cell, the total light transmittance increases, so that the light utilization efficiency can be improved. When the optical element 1 is used in a lighting device, the total light transmittance similarly increases, so that the light use efficiency can be improved, the illuminance can be improved, or the power consumption can be reduced. When the optical element 1 is disposed for use in a copying machine, the total light transmittance increases and the reflectance decreases, so that the copying accuracy can be improved, or the power consumption can be reduced by improving the illuminance. . When the optical element 1 is used for a touch panel, the reflectance can be reduced by covering the fine concavo-convex structure 10a of the optical element 1 with a conductive layer as compared with the case where there is no fine concavo-convex structure. A highly transparent touch panel with excellent performance can be created. The optical element 1 can be used as a resin film roll having a width of 10 cm or more and a length of 50 m or more.

  As described above, according to the optical element 1 according to the above embodiment, the height of the convex portion 11 from the reference plane X is set to 200 nm or more, and the interval between the adjacent convex portions 11 is 260 nm in plan view. Therefore, not only the incident light entering the optical element 1 from the front but also the incident light entering from an oblique direction, the apex of the convex portion 11 from the reference plane X required for improving the antireflection performance It is possible to sufficiently secure the height and the interval between the convex portions 11. Thereby, generation | occurrence | production of a diffraction phenomenon can be suppressed and the raise of the reflectance in a specific wavelength can be suppressed, Therefore The antireflection performance in a visible wavelength region can be improved further. Since the plurality of convex portions 11 or the plurality of concave portions 12 are arranged in an N-shaped lattice shape, and (N−2) ridges 13 are provided between the convex portions 11 adjacent to the arbitrary convex portions 11, the reference The refractive index gradient on the surface of the substrate 11 provided with the fine concavo-convex structure in the height direction from the surface X can be made smooth. As a result, the optical element 1 having excellent antireflection performance can be realized in a wide wavelength range from visible to near infrared and in a wide incident light angle range.

  Hereinafter, although it demonstrates in detail based on the Example performed in order to clarify the effect of this invention, this invention is not limited at all by the following Examples.

Example 1
The optical element according to the above embodiment was manufactured, and the characteristics of the manufactured optical element were measured and evaluated. Hereinafter, the outline and evaluation results of the manufactured optical element will be described.

(Composition composing uneven structure)
32 parts by mass of trimethylolpropane triacrylate as a monomer component containing three or more acrylic groups and / or methacryl groups in one molecule, and N-vinyl-2 as a monomer component containing an N-vinyl group -32 parts by weight of pyrrolidone (NVP), 33 parts by weight of 1,9-nonanediol diacrylate as the other monomer component, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Ciba 2 parts by mass of Specialty Chemicals, Darocur TPO), 1 part by mass of silicon diacrylate as a silicon compound containing an acrylic group, and a composition that forms a concavo-convex structure by filtering foreign matter using a filter having a pore diameter of 1 μm A product was made. The viscosity at 50 ° C. of the photocurable composition constituting the obtained uneven structure was 5 mPa · s. The said viscosity was measured at 50 degreeC using the E-type viscosity meter (the Toki Sangyo company make, model number: RE550L).

(Original plate production method)
An interference manuscript was obtained by irradiating a glass plate on which a photoresist layer of uniform thickness was formed with two laser beams separated by a beam splitter by a laser interference exposure method. Next, the glass plate was rotated 60 ° to obtain an interference paper in the same manner. Thereafter, the photoresist was developed to prepare an original plate having a moth-eye continuous structure including concave and convex portions. In the original plate, the arrangement patterns of the concave portions and the convex portions were each a hexagonal lattice pattern.

(Stamper roll A)
From the original plate, the concavo-convex structure was transferred by electroforming to produce a nickel-plated stamper (flat plate, thickness 0.2 mm) having a moth-eye concavo-convex continuous structure. In the stamper, the interval (pitch) between the convex vertices of the concavo-convex structure was 240 nm, and the height was 310 nm. In the stamper, the arrangement pattern of the concave portions and the convex portions was each a hexagonal lattice. Thereafter, the stamper was processed into a cylindrical shape to obtain a stamper roll A having a moth-eye continuous structure including a concave portion and a convex portion. The stamper roll surface was subjected to a mold release treatment using a mold release agent (Daikin Industries, Durasurf HD-2101Z).

(Method for producing optical element)
The composition which comprises the said uneven structure was apply | coated on the transparent base material so that it might become width 200mm and thickness 0.5micrometer using the gravure coater. Application was performed continuously by a roll-to-roll method. As the transparent substrate, a TAC film (manufactured by FUJIFILM Corporation, Fujitack, thickness 80 μm, width 250 mm) was used. Thereafter, the application surface of the composition constituting the concavo-convex structure of the TAC film was brought into contact with the formation surface of the moth-eye continuous structure of the above-mentioned stamper roll A, and a metal halide lamp (manufactured by USHIO INC., Model number: UVC-2519-) was formed from the film side. 1MNSC7-MS01) was used to irradiate UV light under the condition of a light amount of 1 J / cm ² to photocur the composition constituting the concavo-convex structure. Thereafter, the cured product was peeled from the stamper roll to obtain a TAC film roll (length: 250 m) having a moth-eye continuous structure surface onto which the moth-eye continuous structure surface of the stamper roll was transferred. In the preparation of the TAC film roll having the moth-eye-like continuous structure surface, the surface temperature of the stamper roll during UV light irradiation is stable at about 50 ° C., and the photocuring reaction rate is 80% or more. (Absorption based on double bond of acryl group and / or methacryl group).

  The characteristics of the optical element obtained as described above were evaluated. Evaluation was performed as follows.

(Sequence pattern, ridge presence and pitch measurement)
By surface SEM microscopic observation, the distance between the apex (the highest point) of the convex part having a height of 200 nm or more and the apex of the convex part having a height of 200 nm or more closest to the apex of the convex part was measured as a pitch. In addition, when the convex part has no vertex and a plane exists, the center of gravity of the plane is defined as the vertex. Moreover, the presence or absence of a ridge and the number of ridges in a unit cell were determined from a surface SEM photograph. Further, the area (Sall) of the unit cell was obtained.

(Average value of convex part height)
First, the shape of the concave portion and the convex portion was measured using a scanning probe microscope (manufactured by Digital Instruments, model: Nano Scope IIIa). As a cantilever, Nano WORLD Co., Ltd., model: SSS-NCH-10 was used, the scan rate was 0.50 Hz, and measurement was performed in a taping mode. The measurement area was 2.0 μm × 2.0 μm. The number of measurement points was 256 points × 256 points (a total of 65536 points). As a result, the height of each measurement point and the corresponding position information in the plane direction were obtained.

  Next, in the analysis mode, the obtained measurement values were corrected for inclination with Flatten Order 0, and the height of the convex portion, the average deviation of the height of the concavo-convex structure, the height of the ridge, and the like were calculated by Bearing. Here, it confirmed that the average value of the height of a convex part was 200 nm or more.

(Standard deviation of convex part height and concave part height)
In addition, the average deviation of the height of the concavo-convex structure is the number of fractions generated when the measurement region is fractionated into 50-nm sections in the height direction with reference to the height of the lowest point of the recess (height = 0 nm). The number of sections) is n, the ratio of the area related to the i-th fraction (i-th section) to the area of the measurement region (fraction ratio) is Hi, and the total of the ratios Hi in all fractions is The value divided by n was calculated from the following formula (1) as Have. In addition, the fraction ratio was calculated | required by rounding off the 2nd decimal place to one decimal place. Further, when the fraction ratio was zero, that is, when the fraction ratio before rounding off the second decimal place was less than 0.50%, it was treated as no fraction ratio.

  The standard deviation of the concave height is obtained based on the data on the shape of the concave and convex portions measured using the above scanning probe microscope, and the standard height of the 40 concave portions adjacent to each other is obtained. Asked.

  The standard deviation of the height of the convex part is close to the target area when calculating the standard deviation of the concave part height based on the data on the shape of the concave part and the convex part measured using the scanning probe microscope. The height of the top part of 40 convex parts to obtain was obtained, and the standard deviation was obtained.

(Measurement of average reflectance)
The back side of the surface on which the concavo-convex structure of the optical element is formed (the surface on which the concavo-convex structure is not formed) is coated in black using a black paint spray, and then the surface on which the concavo-convex structure is formed (black non-coating) The regular reflectance was measured with respect to (work surface). The measurement was performed using a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, model: U-4100). Specifically, when S wave polarized light or P wave polarized light is incident, regular reflectance at incident light angles of 20 °, 45 °, 55 °, 60 ° and a wavelength range of 400 to 1000 nm (every 1 nm). Were measured, and the angle and wavelength dependence of the regular reflectance was examined. The average value of the regular reflectance of the S-wave polarized light and the regular reflectance of the P-wave polarized light was taken as the average reflectance at each incident light angle and wavelength.

(Total light transmittance)
When the substrate is transparent, the optical element on which the concavo-convex structure is formed, and the substrate are all transmitted through a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., model: NDH2000) according to JIS K7136. The rate was measured.

(Haze measurement)
When the base material is transparent, each haze is measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., model: NDH2000) in accordance with JIS K7136 for the optical element having the concavo-convex structure and the base material. Deserved. A value obtained by subtracting the haze of the base material from the haze of the optical element was taken as Δhaze.

(Correlation curve between convex height and filling factor)
After extracting the data regarding the height of the fine concavo-convex structure obtained from the scanning probe microscope by text conversion and correcting the data so that the position where the height becomes the minimum becomes the reference plane, the height is divided into sections of 10 nm. A correlation curve indicating the relationship between the height and the filling rate was obtained from the area of the partition, each section, and the area of the entire target region. Here, histogram analysis in the Excel 2003 analysis tool made by Microsoft was performed on 65536 text data, and the cumulative frequency was used as a correlation curve. In order to obtain a correlation curve by approximating such discrete data (in this case, discrete data of 10 nm section) to a continuous function, a polynomial approximation method, a method of interpolating discrete data with a straight line, and other general methods An approximation method can be used. FIG. 15 shows a correlation curve between the height and the filling rate. In the correlation curve shown in FIG. 15, the number of inflection points was four.

  The evaluation results regarding the above items are shown in Table 1 and Table 2 below. 6 to 8 for explaining the concavo-convex structure correspond to the concavo-convex shape of the optical element manufactured in Example 1. FIG. 6 and 8, it can be seen that the height of the ridge 13 is about 50% of the height of the vertex 11 a of the convex portion 11. FIG. 10 shows the depth distribution of the concavo-convex region, where the highest point position of the bulge is 0 nm.

(Examples 2 and 3)
Instead of the stamper roll A used in Example 1, the moth film-like continuous structure shape and the stamper rolls B and C having different arrangement patterns were used. From each stamper roll, a TAC film roll having a moth-eye continuous structure surface was obtained. Obtained. The production conditions were all the same as in Example 1 except that the stamper roll was different. Moreover, the same characteristic evaluation as Example 1 was performed with respect to the obtained optical element. Here, it was confirmed that the height of the convex portion was 200 nm or more. The evaluation results are shown in Table 1. FIG. 10 shows the depth distribution of the fine concavo-convex structure with the highest point position of the convex portion being 0 nm (Example 2 to Example 3). The evaluation results are shown in Table 1 and Table 2 below. 16 and 17 show correlation curves between the height and the filling rate. In the correlation curves shown in FIGS. 16 and 17, the number of inflection points was four.

(Comparative Example 1)
The fine concavo-convex structure of Comparative Example 1 was created by a lithography method using laser light. Under the condition that the substrate on which the photoresist was uniformly formed was rotated, the rotation speed of the substrate and the repetition frequency at which the laser pulse was emitted were adjusted, and laser exposure was performed. Next, development and etching of the exposed substrate were performed to obtain a fine uneven structure without a ridge. An optical element was produced in the same manner as in Example 1 except that an original was produced by a lithography method using this laser beam. An electron micrograph of the fine concavo-convex structure of the optical element according to Comparative Example 1 is shown in FIG. FIG. 11A is an electron micrograph obtained by imaging the fine concavo-convex structure from above, and FIG. 11B is a cross-sectional photograph of the fine concavo-convex structure in FIG. 11A. As can be seen from FIGS. 11A and 11B, the fine concavo-convex structure of the optical element according to Comparative Example 1 has a hexagonal lattice-like arrangement pattern in a top view, while the periphery of each convex portion is surrounded by concave portions, No ridge is provided between the convex portions and between the concave portions. Here, it was confirmed that the height of the convex portion was 200 nm or more. The evaluation results are shown in Table 1 and Table 2 below. In addition, the optical element according to Comparative Example 1 has not been measured for some evaluation items of the concavo-convex structure by the scanning probe microscope.

  As can be seen from Table 2, the fine concavo-convex structure has an N-sided lattice-like arrangement pattern, and from one protrusion (N−) between any protrusion and N protrusions adjacent to the protrusion. 2) When there is a single ridge, it is excellent in total light transmittance and haze, and can realize excellent antireflection performance in a wide wavelength range from visible to near infrared and a wide incident light angle range. It can be seen (Example 1 to Example 3). On the other hand, it has a hexagonal lattice-like arrangement pattern, but it can be seen that when there is no ridge, the average reflectance is significantly reduced (Comparative Example 1).

  12 to 14 are diagrams showing the relationship between the reflectance and the wavelength. As can be seen from FIGS. 12 to 14, in the optical elements according to Examples 1 to 3, the wavelength of incident light is 465 nm (blue light) and 525 nm (green) compared to the optical element according to Comparative Example 1. It can be seen that excellent antireflection performance is obtained in each wavelength region of light), 630 nm (red light), and 1000 nm (near infrared light).

  The present invention is not limited to the above-described embodiment, and can be implemented with various modifications. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, the present invention can be appropriately modified and implemented without departing from the scope of the object of the present invention.

  According to the present invention, an optical element excellent in antireflection performance can be obtained in a wide wavelength region from visible to near infrared and a wide incident light angle range. Moreover, the resin film roll containing the optical element of the present invention can be produced with high productivity by a roll-to-roll method. The optical element of the present invention can be disposed in a display device, a lighting device, a solar cell, a copying machine, or the like.

DESCRIPTION OF SYMBOLS 1 Optical element 10 Base material 10a Fine uneven structure 11 Convex part 11a Vertex 12 Concave part 12a Bottom 13 Ridge 14 Hexagonal shape 30 Cross section between a concave part and a ridge 31 Cross section between a concave part and a convex part 32 Between convex part and ridge Cross section between

Claims (17)

A substrate, and a fine uneven structure including a plurality of protrusions and a plurality of recesses provided on the surface of the substrate,
In the predetermined region of the fine concavo-convex structure, the height of the vertices of the plurality of convex portions from the reference surface is 200 nm or more,
An interval between the plurality of adjacent convex portions is less than 260 nm in plan view;
The array pattern of the plurality of protrusions or the plurality of recesses is a hexagonal lattice pattern, and the three or four protrusions belonging to the arbitrary protrusions and the six protrusions adjacent to the arbitrary protrusions An optical system characterized in that there is a ridge between the convex portions, and among the six convex portions adjacent to the arbitrary convex portions, convex portions other than the three or four convex portions are not adjacent to each other. Element . The optical element according to claim 1, wherein four ridges exist between the arbitrary convex portion and the six convex portions adjacent to the arbitrary convex portion. A substrate, and a fine uneven structure including a plurality of protrusions and a plurality of recesses provided on the surface of the substrate,
In the predetermined region of the fine concavo-convex structure, the height of the vertices of the plurality of convex portions from the reference surface is 200 nm or more,
An interval between the plurality of adjacent convex portions is less than 260 nm in plan view;
The array pattern of the plurality of protrusions or the plurality of recesses is a tetragonal lattice pattern, and two or three protrusions belonging to the arbitrary protrusions and the four protrusions adjacent to the arbitrary protrusions An optical system characterized in that there is a ridge between the convex portions and convex portions other than the two or three convex portions are not adjacent to each other among the four convex portions adjacent to the arbitrary convex portion. element. In a plan view, the ratio of the area occupied by the region having a height of 250 nm or more from the reference plane to the area of the predetermined region is 5% or more,
The number of fractions generated when the fine concavo-convex structure is fractionated every 50 nm in the height direction from the reference plane is n, and the i-th fraction with respect to the area occupied by all fractions in the predetermined region in plan view When the ratio of the area occupied in plane view is Hi and the value obtained by dividing the total of the ratios Hi in all fractions by n is Have, the average deviation in height represented by the following formula (1) is 3 or more and 8 And
2. The inflection point is present in two or more inflection points in a curve showing a relationship between a height and a ratio of an area occupied by a region higher than the height in plan view of the predetermined region in the fine concavo-convex structure. The optical element according to claim 3 .
The optical element according to claim 4, wherein a standard deviation of the recess depth of the recess is 3 or more and 20 or less. Claim 4 or 5 optical element, wherein the standard deviation of the convex height of the convex portion is 3 to 20. The optical element according to any one of claims 1 to 6 , wherein an average value of the height of the ridge with respect to an average value of the heights of the convex parts of the convex parts is 20% or more and 80% or less. . In the unit lattice having the fine concavo-convex structure, the ratio (Sb / Sall) of the area (Sall) of the unit lattice to the total sum (Sb) of the bottom region having a height of 10 nm or less from the reference plane is 10% or less. the optical element according to any one of claims 1 to 7, characterized in that it. Of the intervals between the vertices of the arbitrary convex portions and the vertices of six or four convex portions closest to the arbitrary convex portions, the difference between the maximum value and the minimum value is divided by the average value of the intervals. value [(Pmax-Pmin) / Pave ] optical element as claimed in any one of claims 8, characterized in that 20% or less. Wherein and micro-relief structure is constituted by a composition layer, the thickness of the composition layer, optical element according to any one of claims 1 to claim 9, characterized in that a 0.4μm or 10μm or less . The composition layer is composed of 20 parts by mass to 60 parts by mass of one or more monomer components having 3 or more acrylic groups and / or methacrylic groups in one molecule in 100 parts by mass, and an N-vinyl group. The optical element according to claim 10 , wherein a composition containing 5 to 40 parts by mass of the monomer component and 0 to 75 parts by mass of other monomer components is cured. The optical element according to claim 10 or 11 , wherein the composition is a photocurable composition. The optical element according to claim 12 , wherein the photocured composition before photocuring has a viscosity at 50 ° C of 100 mPa · s or less. Includes an optical element as claimed in any one of claims 13, resin film roll, wherein the width 10cm or more, and is 50m long or more. Display apparatus comprising the optical element as claimed in any one of claims 13. An illumination device comprising the optical element according to any one of claims 1 to 13 . A solar cell comprising the optical element according to any one of claims 1 to 13 .