JP2013061612A - Optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element having excellent antireflection performance, in a wide wavelength region of visible to near-infrared rays, and a wide incident light angle range.SOLUTION: In an optical element, any vertex of a plurality of projection portions (11) has a height of 200 nm or higher from a reference surface, a space between any one vertex of the plurality of the projection portions (11) and the vertex of the projection portion (11) which is the closest to the projection portion (11) is less than 260 nm in plan view, a ratio occupied by a region having a height of 250 nm or higher from the reference surface in plan view with respect to an area in a predetermined region in plan view is 5% or more, and average deviation of heights of a fine uneven structure (10) is 3 or more and 8 or less. In the fine uneven structure (10), in a curve indicating a relationship between the height and a ratio of an area occupied by a region of the height or higher in the predetermined region in plan view, there exist two or more inflection points.

Description

  The present invention relates to an optical element excellent in antireflection performance in a wide wavelength range from visible to near infrared and in a wide incident light angle range.

  In recent years, with the expansion of the display market, there is an increasing demand for viewing clearer images indoors and outdoors. However, in a television that is mainly viewed indoors, there is a problem that a clear image cannot be visually recognized 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 surface of the screen in a wide wavelength region. In addition, since the incident angle of incident light on the screen varies depending on the type of display-equipped device and the place where it is used, it is necessary to provide antireflection performance in a wide incident light angle range.

  As a technique for improving the antireflection performance of a display, a method using an antireflection film is known. For example, Patent Document 1 discloses an antireflection film having an alternating multilayer structure of a high refractive index layer and a low refractive index layer. This antireflection film exhibits an antireflection effect by canceling the reflected light by utilizing the interference action of 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. However, the antireflection film described above exhibits excellent antireflection performance at a specific wavelength, but does not exhibit sufficient antireflection performance over a wide wavelength region. Furthermore, sufficient antireflection performance cannot be exhibited in a wide incident light angle range.

  Patent Document 2 discloses a structure having a shape in which an effective refractive index neff (h) intersects with a function Neff (h) at three points. Non-Patent Document 1 shows that a so-called moth-eye structure, in which submicron-order pyramid-like uneven structures are arranged in a two-dimensional pattern such as a grid, has an antireflection effect. Non-Patent Document 2 discloses an optical element having a moth-eye structure on a substrate such as resin or glass and its spectral reflectance in the visible wavelength region.

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

Endeavor, 26, P79-84 (1967) Optical Technology Contact, 43 (11), P630-637 (2005)

  However, it is difficult to say that the above-described optical element can achieve both sufficient antireflection performance in a wide wavelength region and sufficient antireflection performance in a wide incident light angle range.

  In view of the above, an object of the present invention is to provide an optical element having excellent antireflection performance in a wide wavelength range from visible to near infrared and a wide incident light angle range.

The optical element of the present invention has a fine concavo-convex structure composed of a plurality of concave portions and a plurality of convex portions on the substrate surface, and in the predetermined region of the fine concavo-convex structure, the vertices of the plurality of convex portions are all The height is 200 nm or more from the reference plane including the lowest point among the bottoms of the plurality of concave portions, and the interval between any vertex of the plurality of convex portions and the vertex of the convex portion closest to the convex portion is 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 in the plan view is less than 260 nm in the plan view and 5% or more in the plan view, 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 is relative to the area occupied by the entire fraction in the predetermined region in the plan view. Occupied in plan view When the ratio of the area 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 is 3 or more and 8 or less, and the fine uneven structure In the curve, there are two or more inflection points in the curve indicating the relationship between the height and the ratio of the area occupied by the area of the predetermined area or more in plan view of the predetermined area.

According to this configuration, in a wide wavelength region from visible to near infrared, and a wide incident light angle range,
An optical element having excellent antireflection performance can be obtained.

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

  In the optical element of the present invention, it is preferable that a 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 a ridge exists between the convex portion and the convex portion adjacent to the convex portion.

  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 four or eight ridges in an arbitrary unit cell composed of the convex portions and a plurality of convex portions closest to the convex portions.

  In the optical element of the present invention, the fine concavo-convex structure has a ratio (Sb / Sall) of an area (Sall) of the unit cell and a total area (Sb) of a bottom region having a height of 10 nm or less from the reference plane. Is preferably 10% or less.

  In the optical element of the present invention, it is preferable that the arrangement pattern of the convex portions or the concave portions is a hexagonal lattice.

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

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

  In 100 parts by mass of the optical element of the present invention, 20 to 60 parts by mass of one or more monomer components having 3 or more acrylic groups and / or methacrylic groups in one molecule, and an N-vinyl group. It is preferable to cure a composition containing 5 to 40 parts by mass of the monomer component and 0 to 75 parts by mass of the other monomer component.

  In the optical element of the present invention, it is preferable that the composition constituting the concavo-convex portion is a photocurable composition.

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

  A resin film roll having a width of 10 cm or more and a length of 50 m or more including the optical element of the present invention can be provided. In addition, a display device, a lighting device, a solar cell, and the like provided with the optical element of the present invention are provided.

  According to the present invention, an optical element excellent in antireflection performance can be provided in a wide wavelength region 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 the photograph which expanded a part of fine concavo-convex structure concerning this embodiment. It is an electron micrograph which shows the arrangement pattern of the fine concavo-convex structure concerning 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 a recessed part and a ridge in a fine concavo-convex structure. It is a figure which shows the example of the cross-sectional profile containing a recessed part and a convex part in a fine term convex structure. It is a figure which shows the example of the cross-sectional profile containing a convex part and a ridge in a fine concavo-convex structure. It is a figure which shows the relationship between a unit cell 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 an operation type probe microscope is 0 nm. 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 an operation type probe microscope is 0 nm. It is a figure which shows the wavelength dependence and incident light angle dependence of the regular reflectance of Example 1. FIG. It is a figure which shows the wavelength dependence and incident light angle dependence of the regular reflectance of Example 2. It is a figure which shows the wavelength dependence and incident light angle dependence of the regular reflectance of Example 3. It is a figure which shows the wavelength dependence and incident light angle dependence of the regular reflectance of the comparative example 1. It is a figure which shows the wavelength dependence and incident light angle dependence of the regular reflectance of the comparative example 2. It is a figure which shows the wavelength dependence and incident light angle dependence of the regular reflectance of the comparative example 3. It is a figure which shows the incident light angle dependence in wavelength 465nm (blue light) of regular reflectance. It is a figure which shows the incident light angle dependence in wavelength 525nm (green light) of regular reflectance. It is a figure which shows the incident light angle dependence in wavelength 630nm (red light) of regular reflectance. It is a figure which shows the incident light angle dependence in wavelength 900nm (near infrared light) of a regular reflectance. It is a figure which shows the wavelength dependence of (positive + diffusion) reflectance. It is a figure in Example 1 which shows the reflectance in the incident angle from 0 degree to 60 degrees of the perpendicular direction of visible light region (400 nm-800 nm). It is a figure which shows the reflectance in the incident angle from 0 degree to 60 degrees of the perpendicular | vertical direction of the visible light region (400 nm-800 nm) in the comparative example 4. It is a figure which shows the reflectance in the incident angle from 0 degree to 60 degrees of the perpendicular | vertical direction of the visible region (400 nm-800 nm) in the comparative example 5. FIG. 3 is a correlation diagram showing a correlation curve between height and filling rate in Example 1. FIG. 6 is a correlation diagram showing a correlation curve between height and filling rate in Example 2. FIG. 6 is a correlation diagram showing a correlation curve between height and filling rate in Example 3. 6 is a correlation diagram showing a correlation curve between height and filling rate in Comparative Example 1. FIG. 10 is a correlation diagram showing a correlation curve between height and filling rate in Comparative Example 2. FIG. FIG. 10 is a correlation diagram showing a correlation curve between height and filling rate in Comparative Example 3. It is a figure which shows an example of the display apparatus provided with the optical element which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

<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. As shown in FIG. 1, the optical element 1 according to the present embodiment has a fine concavo-convex structure 10 molded on the surface. The fine concavo-convex structure 10 has a plurality of convex portions 11 and 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 ( (See FIG. 2). Further, the fine concavo-convex structure 10 forms an array pattern having arbitrary regularity by the plurality of convex portions 11 and the plurality of concave portions 12 in a plan view from a perpendicular direction orthogonal to the reference plane X of the optical element 1. . For example, the reference plane X can be a plane including the lowest point among the bottoms of the plurality of recesses 12. In addition, about how to take the reference plane X, it is not restricted to this.

  In the optical element 1 according to the present embodiment, it is preferable that the convex portions 11 or the concave portions 12 of the fine concavo-convex structure are arranged in a hexagonal lattice shape in plan view. By using a hexagonal lattice, the packing density of the convex portions at the same pitch can be made higher than that of the tetragonal lattice. Further, the optical anisotropy due to the arrangement can be reduced. Furthermore, it becomes easy to form a refractive index gradient gently. This improves the antireflection performance in a wide region from visible light to near infrared light. FIG. 3 shows an example of an arrangement pattern of the protrusions 11 of the fine concavo-convex structure 10 arranged in a hexagonal lattice pattern. As shown in FIG. 3, the hexagonal lattice-like arrangement pattern is most similar to the convex portion 11 with respect to any one convex portion 11 of the fine concavo-convex structure 10 in a plan view from the direction perpendicular to the reference plane X. There are six adjacent protrusions 11, and the six protrusions 11 form an array pattern that forms a hexagonal shape 21. FIG. 3 also shows a region (ridge 22) that is provided in a region between the convex portion 11 and the concave portion 12 and has an intermediate height between the height of the vertex of the convex portion 11 and the bottom height of the concave portion 12. The ridge 22 is, for example, a linear region that connects the vertices of adjacent convex portions 11 and corresponds to a region that is higher than the bottom of the concave portion 12. Or it is a linear area | region which connects the bottoms of the adjacent recessed part 12, Comprising: It corresponds to the area | region lower than the vertex of the convex part 11. FIG. In this specification, unless otherwise specified, the height (H) is the distance between the reference plane X and the object in the direction perpendicular to the reference plane. As an array pattern of the convex portions 11 or the concave portions 12 of the fine concavo-convex structure 10, there are four convex portions 11 closest to the convex portion 11 for any one convex portion 11, and the four It may be a tetragonal lattice-like arrangement pattern that forms a quadrangular shape by the convex portions 11, or a random pattern having no regularity in the arrangement of the convex portions 11.

  In the optical element 1 according to the present embodiment, the average value of the pitch P between the convex portions 11 adjacent to each other is less than 260 nm, preferably less than 230 nm, and more preferably less than 200 nm. At least by setting the pitch P to less than 260 nm, it is possible to suppress the occurrence of diffraction phenomenon, suppress the increase in reflectance at a specific wavelength, and improve the antireflection performance in the visible wavelength region.

  In the optical element 1 according to the present embodiment, the height of the convex portion 11 is preferably 200 nm or more. The height of the convex portion 11 is more preferably 260 nm or more, further preferably 300 nm or more, and further preferably 400 nm or more. By making the height of the projection 11 at least 200 nm, excellent antireflection performance can be expressed in a wide incident light angle range. Further, the antireflection performance in a wide wavelength region, particularly in the near infrared wavelength region (700 to 1000 nm) can be improved. However, as long as a predetermined antireflection performance is exhibited as an optical element, the height of all the convex portions 11 does not need to be 200 nm or more. The “height of the convex portion 11 (or the concave portion 12)” is a distance from the reference plane X in the direction perpendicular to the reference plane X of the optical element 1 to the apex of the convex portion 11 (or the bottom of the concave portion 12). .

  Further, the antireflection performance can be further improved by setting the height of the convex portion 11 to 200 nm or more and the pitch P to less than 260 nm.

  The shape of the continuous structure of the fine concavo-convex structure 10 is not particularly limited as long as it is a continuous structure including the convex portions 11 and the concave portions 12 and can obtain the effects of the present invention. 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, in order to obtain high antireflection performance, it is preferable to apply a moth-eye structure which is one of dot structures.

  Moreover, it is preferable that the shape of the convex part 11 and the recessed part 12 of the fine concavo-convex structure 10 is any one of a substantially pyramid shape, a substantially cone shape, a substantially truncated cone shape, and a substantially truncated cone shape. Among these, a substantially pyramid shape and a substantially conical shape are more preferable, and a substantially conical shape is more preferable. The substantially conical shape may be a true cone or an elliptical cone, and preferably has a round top. The antireflection performance can be further improved by rounding the top of the substantially conical shape. 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. The bell type is more preferable in that an excellent antireflection performance can be obtained in a wide wavelength region, particularly in the near infrared wavelength region (700 to 1000 nm).

In the optical element 1, it is preferable that the average deviation of the height calculated by the following formula is 3 or more and 8 or less. 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. If the average deviation in height is at least 3 or more, the peelability from the stamper can be maintained, and excellent antireflection performance can be exhibited in a wide incident light angle range, and if it is 8 or less, a wide incident light angle. The antireflection performance excellent in the range can be expressed, and the antireflection performance can be improved in a wide wavelength region. In the following formula, n is the number of fractions (number of segments) generated when the target area is fractionated from the reference plane X in the height direction every 50 nm. 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, Hi represents the area of the area 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 with respect to the area of the predetermined area. It is the ratio (fraction ratio) that it occupies. 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 a fraction 1 (first division). A region having a height from 50 nm to 100 nm is defined as fraction 2 (second division). Similarly, the target area is fractionated (segmented) into fraction 3 to fraction 8. 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 is 3 or more and 8 or less. Further, it is more preferably 3 or more and 7 or less, further preferably 3 or more and 5 or less, and further preferably 3 or more and 4 or less. If the average deviation in height is at least 3, the peelability from the stamper can be maintained. Moreover, if it is 8 or less, the excellent antireflection performance can be expressed in a wide incident light angle range, and the antireflection performance can be improved in a wide wavelength region.

  In a 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. It is preferable. Further, it 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. 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 expressed in a wide incident light angle range.

The optical element 1 varies in 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 higher than the height in a plan view of the target region (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 slope of the correlation curve corresponds to the slope of the fine concavo-convex structure 10, and the correlation curve of the gentle slope means that the slope of the fine concavo-convex structure 10 is gentle. For this reason, by having two or more inflection points in the correlation curve, the gradient of the fine concavo-convex structure 10 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, it is preferable that the standard deviation of the height of the recess 12 (that is, the height of the bottom of the recess 12) is 3 or more and 20 or less. By making the height of the recess 12 within this range, the reflectance prevention characteristic can be improved. Furthermore, it is more preferable that the standard deviation of the height of the convex portion 11 (that is, the height of the vertex of the convex portion 11) is 3 or more and 20 or less. By making the height of the convex portion 11 within this range, the reflectance prevention characteristic can be further improved. When the standard deviation of the height of the concave portion 12 and / or the height of the convex portion 11 is 3 or more and 20 or less, the correlation curve is connected to the height reference point and the point where the height is maximum in the correlation curve. When the straight line is compared, the deviation between the correlation curve and the straight line becomes large near the height reference point and near the maximum height. Therefore, by forming the fine concavo-convex structure 10 so that two or more stop points appear in the correlation curve as described above, the correlation curve and the straight line are close to each other, and a gentle correlation curve without a steep refractive index change is obtained. Therefore, the antireflection performance is improved.

  The optical element 1 preferably has the ridge 22 described above. In the case of having a ridge, the physical strength of the optical element 1 against bending is increased. This makes it possible to apply to a flexible display having a curved screen. Further, high antireflection performance can be obtained in a wide wavelength region. Here, the average value of the height of the ridge 22 is preferably 20% or more and 80% or less, more preferably 30% or more and 70% with respect to the average value of the height of the convex portion 11, % To 60% is more preferable. By setting 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. Moreover, it is preferable that 4 or 8 ridges exist in an arbitrary unit cell. Thereby, the antireflection performance can be further improved.

  Moreover, it is preferable that the direction where the ridge 22 exists and the direction where the ridge 22 does not exist coexist in the fine concavo-convex structure 10. That is, it is preferable that a cross section where the ridge 22 appears and a cross section where the ridge 22 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) including the concave portion 12 and the ridge. In the cross section shown in FIG. 6, the bottom 22 and the ridge 23 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 10 in a cross-section 31 (a cross-section having no ridge) formed by the convex portions 11 and the concave portions 12. In the cross section shown in FIG. 7, the apex 20 of the convex portion 11 and the bottom 22 of the concave portion 12 can be confirmed. FIG. 8 is a diagram illustrating an example of a cross-sectional profile of the fine concavo-convex structure 10 in a cross-section 32 (a cross-section where a ridge exists) including the convex portion 11 and the ridge. In the cross section shown in FIG. 8, the apex 20 and the ridge 23 of the convex part 11 can be confirmed. 6, 7 and 8, the scale in the height direction is the same.

  The uniformity of the height of the ridge 22 is the average value (Kave) of the height of the ridge 22 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 ridge height uniformity 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 22 can be calculated from 100 or more measured values by measuring the height of the ridge 22 with a scanning probe microscope.

  In the optical element 1, the arrangement pattern of the convex portions 11 or the concave portions 12 may be any of a hexagonal lattice, a tetragonal lattice, and a random lattice. In the case of a hexagonal lattice, the maximum value (Pmax) of the pitch P and the minimum value (Pmin) of the pitch P between the certain convex part 11 (or concave part 12) and the six convex parts 11 (or concave parts 12) closest thereto. The value [(Pmax−Pmin) / Pave] obtained by dividing the difference by the average pitch value (Pave) is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. In the case of a tetragonal lattice, the maximum value (Pmax) and the minimum value (Pmax) of the pitch P between the certain convex portion 11 (or concave portion 12) and the four convex portions 11 (or concave portions 12) closest thereto. The value [(Pmax−Pmin) / Pave] obtained by dividing the difference from Pmin) by the average value (Pave) of the pitch P is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. In the case of a random lattice, the convex portions 11 (or concave portions 12) and the four adjacent convex portions 11 (or concave portions 12 in order from the closest distance between the convex portions 11 (or concave portions 12)). ) And the difference between the maximum value (Pmax) of the pitch P and the minimum value (Pmin) of the pitch P by the average value (Pave) of the pitch P [(Pmax−Pmin) / Pave] is 20% or less Is preferably 15% or less, more preferably 10% 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 regular hexagon in the case of a hexagonal lattice and a square in the case of a tetragonal lattice. 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.

  In the fine concavo-convex structure 10 of the optical element 1, the ratio (Sb / Sall) between the area (Sall) of the unit cell and the total area (Sb) of the bottom region having a height of 10 nm or less from the reference plane X is 10%. The following is preferable. Further, Sb / Sall is more preferably 5% or less, further preferably 3% or less, and most preferably the bottom region is a point. By making Sb / Sall 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. Due to the limit of manufacturing accuracy, the lower limit of Sb / Sall is about 0.1%. However, Sb / Sall is preferably as small as possible, and may be 0.1% or less. 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.

  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 10 can be obtained.

<Base material>
The base material used for the optical element 1 has (a) good adhesion to the composition constituting the fine concavo-convex structure 10 and (b) small refractive index difference from the composition constituting the fine concavo-convex structure 10. (C) The haze of the composition layer constituting the fine relief structure 10 is required to be small. The base material has (d) flexibility, (e) easy processability, (f) high productivity, (g) light weight, and (h) high impact resistance. (I) it is required to be inexpensive. Examples of materials that satisfy the requirements (a) to (c) include glass and resin. Moreover, resin is mentioned as a material which satisfy | fills the requirements of (d)-(g) in addition to the requirements of (a)-(c). In addition, the base material used for the optical element which concerns on this invention is not limited to this. An inorganic material such as glass, ceramic or metal, or an organic material such as resin can be arbitrarily selected according to the purpose of use or application.

  The optical element according to the present invention may require transparency or non-transparency. For this reason, it is desirable to select the kind of base material according to the objective and the use. When transparency is required, the substrate needs to be transparent in the target wavelength region. In this case, it is preferable to use a transparent resin or glass as the substrate. Further, when flexibility is required, it is preferable to use a transparent resin. 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. Further, in order to satisfy the 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. , Cycloolefin resin (COP resin), polyarylate resin, polyetherimide resin, polyether sulfone resin, polysulfone resin, polyether ketone resin, polyethylene terephthalate resin (PET resin), polyethylene naphthalate resin (PEN resin), Examples include polytrimethylene terephthalate resin, aromatic polyester resin, triacetyl cellulose resin (TAC resin), polyimide resin, acrylic resin, epoxy resin, urethane resin such as ultraviolet curable resin, and thermosetting resin.In particular, PMMA resin, acrylic resin, PC resin, PS resin, styrene resin, COP resin, PET resin, PEN resin, aromatic polyester resin, and TAC resin are 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, crosslinked polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyphenylene ether resin, modified polyphenylene ether resin, polybutylene terephthalate resin Etc. Also, 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) / acrylic resin And the like.

  In the case where the substrate is a resin, an additive may be added as necessary as long as the target requirements are not impaired. The additive may be directly contained in the resin and / or may be layered on the surface of the resin substrate. Examples of the additive include organic and / or 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. Further, a black paint may be applied to the non-formed surface of the fine uneven structure 10.

  In addition, a barrier resin layer may be formed on the surface of the resin base material by coating or the like as long as the target requirements are not impaired. By forming the barrier resin layer on the surface of the resin substrate, the resin substrate can be protected from deterioration factors such as heat, light, moisture, oxygen, carbon dioxide, nitrogen, and hydrogen.

  When the substrate is glass, a surface treatment such as a silane coupling agent, primer treatment, or UV treatment can be applied. Moreover, you may use combining these.

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

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

  The thickness of the substrate can be selected according to the purpose of use. When thinning or flexibility is required, the thickness of the substrate is preferably 350 μm or less, more preferably 120 μm or less, further preferably 80 μm or less, and most preferably 40 μm or less. Further, the thickness of the substrate is preferably 10 μm or more from the viewpoint of easy handling.

<Composition constituting the fine relief structure>
The type of the composition constituting the fine concavo-convex structure 10 including the convex portion 11 and the concave portion 12 included in the optical element 1 can be selected from a photocuring composition, a thermosetting composition, a thermoplastic composition, and the like. From the viewpoint of transfer fidelity, it is preferably formed using a photocurable composition. As the types of monomers and oligomers (hereinafter also referred to as monomer components) in the photocurable composition used in the fine relief structure 10, radical polymerization monomer components are used from the viewpoint of reaction rate and continuous productivity. It is more preferable, and from the viewpoint of increasing the reactivity of the stamper in the deep part of the concave-convex structure pattern, a cationic polymerization monomer component having a long reaction lifetime may be mixed with the radical polymerization monomer. As the photopolymerization cationic monomer, a monomer having a polymerizable functional group having an epoxy group, a vinyloxy group, an oxetanyl group, an oxazolyl group, or the like is preferable.

Examples of radical monomer components include methyl acrylate, ethyl acrylate,
n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate, isoamyl acrylate, n-lauryl acrylate, isomyristyl acrylate, stearyl acrylate, n-butoxyethyl acrylate, butoxydiethylene glycol acrylate, methoxytriethylene Glycol acrylate, methoxy polyethylene glycol acrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, caprolactone acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, phenoxyethyl 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, neopentyl 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 diacrylate, trifluoroethyl acrylate, tetrafluoropentyl acrylate , Octafluoropentyl acrylate, perfluorooctyl ethyl acrylate, nonylphenol-EO adduct acrylate, dimethylol tricyclodecane diacrylate, trimethylol propane acrylate benzoate, hydroxypivalate neopentyl glycol diacrylate, tetrafurfuryl alcohol oligo Acrylate, ethyl carbitol oligoacrylate, 1,4-butanediol oligoacrylate, 1,6-hexanediol oligoacrylate, trimethylolpropane oligoacrylate, pentaerythritol oligoacrylate, pentamethylpiperidyl acrylate, tetramethylpiperidyl acrylate, paracumylphenol -EO modified acrylate, N-acryloyloxyethyl Sahydrophthalimide, 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, isomristyl Methacrylate, stearyl methacrylate, n-butoxyethyl methacrylate, butoxydiethylene glycol methacrylate, methoxytriethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, tripropylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 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-methacryloyloxyethyl phthalate Acid, 2-methacryloyloxyethyl 2-hydroxyethylphthalic acid, neo Pentyl 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, neopentyl glycol dimethacrylate, 3-methyl-1,5-pentanediol dimethacrylate, 2-butyl-2- Ethyl-1,3-propanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethyl Chryrate, 1,10-decanediol dimethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, bisphenol A-EO adduct dimethacrylate, trifluoroethyl methacrylate, tetrafluoropentyl methacrylate, octafluoropentyl methacrylate Perfluorooctylethyl methacrylate, nonylphenol-EO adduct methacrylate, dimethylol tricyclodecane dimethacrylate, trimethylolpropane methacrylic acid benzoate, hydroxypivalate neopentyl glycol dimethacrylate, tetrafurfuryl alcohol oligomethacrylate, ethyl carbitol Oligomethacrylate, 1,4-butanediol oligomethacrylate 1,6-hexanediol oligomethacrylate, trimethylolpropane oligomethacrylate, pentaerythritol oligomethacrylate, pentamethylpiperidylmethacrylate, tetramethylpiperidylmethacrylate, paracumylphenol-EO modified methacrylate, N-methacryloyloxyethylhexahydrophthalimide, 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-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane , 3-ethyl-3- (cyclohexyloxy) methyl oxetane, oxetanylsilsesquioxane, oxetanyl silicate, phenol novolac oxetane, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene, and the like. .

  The composition of the fine concavo-convex structure 10 includes three or more acrylic groups and / or methacrylic groups in one molecule in 100 parts by mass of the monomer components in the composition constituting the fine concavo-convex structure 10. It is preferable that the one or more kinds of monomer components have 20 to 60 parts by mass, the monomer component having an N-vinyl group 5 to 40 parts by mass, and the other monomer components 0 to 75 parts by mass.

  One or more types of monomer components containing three or more acrylic groups and / or methacrylic groups in one molecule are 25 in total of 100 parts by mass of monomer components in the composition constituting the fine relief structure 10. It is more preferable that it is -50 mass parts, and it is still more preferable to contain 30-40 mass parts. By setting it to 20 parts by mass or more, the composition part constituting the fine relief structure 10 has high strength and has a high crosslinking density. Therefore, unreacted monomers from the composition part constituting the fine relief structure 10 and Bleed out of low polymerization degree oligomer and generation of by-products can be minimized. Moreover, by setting it as 60 mass parts or less, the viscosity increase of the composition which comprises the fine concavo-convex structure 10 can be suppressed, and the filling rate reduction to the pattern of the recessed part and convex part of the stamper of the composition which comprises the fine concavo-convex structure 10 can be reduced. Can be prevented.

  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 a total of 100 parts by mass of the monomer components in the composition constituting the fine concavo-convex structure 10, and 25 to 35 parts by mass. It is more preferable to contain. 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 10 may contain a silicon compound containing an acryl group and / or a methacryl group. It is preferable to contain 0.1-10 mass parts of silicon compounds containing an acryl group and / or a methacryl group with respect to 100 mass parts in total of the monomer components of the composition constituting the fine concavo-convex structure 10. The content is more preferably 5 parts by mass, and further preferably 0.3 to 2 parts by mass. 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 uneven structure 10 of the optical element 1 The strength of the layer, particularly the fine relief structure 10 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 ebecryl 350 (manufactured by Daicel-Cytec), which have an acrylic group bonded to the polydimethylsiloxane skeleton, constitute the fine uneven structure 10 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 10, a photoinitiator can be contained. Examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propane- 1-one, benzophenone, 1-hydroxy-cyclohexyl-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- Ruphorinophenyl) -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-trimethylbenzoyl-diphenyl-phosphine oxide, bis (η5-2, 4-cyclopentadien-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-carbazole-3 -Yl] -1- (O-acetyloxime) and the like. In the present invention, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide having high sensitivity and low volatility, 2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyloxime)] ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]- 1- (O-acetyloxime) and the like can be preferably used. The blending ratio of the photopolymerization initiator is preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the total monomer components in the photocurable 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 10, 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 10, it is preferable that the photocurable composition removes a foreign material by a technique 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 10 of the optical element 1 can be reduced to a level where there is no practical problem.

<Viscosity of photocuring composition>
When a photocurable composition is used as the composition constituting the fine concavo-convex structure 10, the viscosity at 50 ° C. of the photocured composition before curing is preferably 100 mPa · s or less, more preferably 50 mPa · s or less, and 20 mPa · s. s is more preferable. When the photocurable composition is applied to the surface of the substrate by the roll-to-roll method, the thickness uniformity of the photocurable composition layer can be increased, and the stamper has an uneven structure portion. The filling rate of the photocurable composition can be increased, and as a result, the transfer fidelity to the optical element can be increased. 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 a photocurable composition is used as the composition constituting the fine concavo-convex structure 10, the surface temperature of the concavo-convex structure surface of the stamper used for producing the optical element 1 is preferably 25 to 100 ° C, more preferably 30 to 80 ° C. 35-70 degreeC is further more preferable, and 40-65 degreeC is the 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 10 is preferably 0.4 to 10 μm or less, more preferably 0.5 to 7 μm or less, and further preferably 0.8 to 4 μm or less. preferable. By making the thickness of the composition layer constituting the concavo-convex part 0.4 μm or more, the adhesion between the base material and the composition constituting the concavo-convex part is improved, and when the concavo-convex structure of the stamper is transferred to the base material Generation of untransferred parts 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 composition layer constituting the fine concavo-convex structure 10 is adjusted by the pressing pressure between the base material and the stamper, the surface temperature of the concavo-convex structure surface of the stamper, the temperature and viscosity of the composition constituting the fine concavo-convex structure 10, 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 glass, ultraviolet transmissive glass, sapphire, diamond, polydimethylsiloxane, and other silicone materials, 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 10 include a photocuring 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, bar code 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 10 may be reduced. When the roll length exceeds 10000 m, the winding accuracy decreases due to the shaft shake of the roll winder. In some cases, the roll strength of the roll winder becomes insufficient due to an increase in the mass of the roll, resulting in damage. For this reason, it is desirable to set it as the resin film roll of the said width | variety and length.

<Application order>
When a photocurable composition is used as the composition constituting the fine concavo-convex structure 10, the optical element 1 is produced by applying the photocurable composition to the base material in a thin film and then applying the photocurable composition of the base material. 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 according to 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>
A protective film may be bonded to the surface of the optical element 1 having the fine uneven structure 10 and / or the surface not having the fine uneven structure 10. By sticking the protective film, the shape of the fine concavo-convex structure 10 can be protected and the 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) When peeling, the adhesive layer of the protective film does not remain on the surface having the fine concavo-convex structure 10, or even if it does not affect the reflectance or transmittance, (2 ) It does not contain foreign matters that damage the surface of the optical element 1 having the fine concavo-convex structure 10 or does 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 base material and the composition layer constituting the fine relief structure 10 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. 05 or less is more preferable, and 0.02 or less is most preferable. Moreover, you may add the intermediate | middle layer which has easy adhesiveness between the base material and the composition layer which comprises the fine concavo-convex structure 10. By setting the refractive index of the intermediate layer between the refractive indexes of the base material and each of the composition layers constituting the fine concavo-convex structure 10, interference can be reduced and interference fringes can be generated compared to the case where there is no intermediate layer. Can be suppressed.

  Moreover, when the adhesive layer is provided to the base material, the difference in refractive index between the base material and the adhesive layer is preferably 0.2 or less, more preferably 0.1 or less, and 0.05 or less for the same reason as described above. 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 10, the haze of the base material alone, and the value obtained by subtracting the haze of the base material 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 10 is formed only on one side. In particular, in order to reduce Δhaze to 1.5% or less, it is effective to give the base material surface a structure having an uneven shape having antireflection performance, in addition to making the refractive index difference 0.2 or less. is there. 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 disposed for use in 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 arranged in a solar cell, the total light transmittance increases, so that the light utilization efficiency can be improved. When the optical element 1 is disposed for illumination, the total light transmittance similarly increases, so that the light utilization efficiency can be improved, the luminance 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 luminance. .

  FIG. 31 is a diagram illustrating an example of a display device 100 (display device) including the optical element 1 according to the present embodiment. In addition, in FIG. 31, the cross section with respect to the surface of the display apparatus 100 is shown typically. In the display device 100, the optical element 1 is used as an antireflection film.

  The display device 100 according to the present embodiment is supported on the front surface side (upper surface side) of the display element 101 by the display element 101, the spacers 102 disposed at both ends of the upper surface of the display element 101, and the spacer 102. And a front plate 103. An antireflection film 104 (optical element 1) is disposed in the central area on the upper surface of the display element 101. Above the antireflection film 104, an antireflection film 106 (optical element 1) fixed to the main surface of the front plate 103 on the display element 101 side is disposed via an air layer (air gap layer) 105. .

  In the display device 100, the light emitted from the display element 101 passes through the antireflection film 104, the air layer 105, the antireflection film 106, and the front plate 104 and is emitted. Here, as the antireflection films 104 and 106, by using the optical element 1 according to the above embodiment, even when the antireflection film 104 is arranged on the display element 101, the total light transmittance is improved, Reflectance is reduced. As a result, the copy accuracy can be improved and the power consumption can be reduced. In particular, in the display device 100, by arranging the antireflection films 104 and 106 through the air layer 105, the influence of interface reflection can be reduced as much as possible when the antireflection films 104 and 106 are laminated. Therefore, in particular, the total light transmittance can be improved and the reflectance can be reduced as compared with the case where the antireflection films 104 and 106 are laminated.

  Hereinafter, the present invention will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
The characteristics of the optical element according to the above embodiment were measured and evaluated. The outline of the optical element and the evaluated characteristics will be described below.

(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, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide ( 2 parts by mass of Ciba Specialty Chemicals, Darocur TPO), 1 part by mass of silicon diacrylate as a silicon compound containing an acrylic group, and filter the foreign matter using a filter with a pore size of 1 μm to form an uneven structure A composition was prepared. The viscosity at 50 ° C. of the photocurable composition constituting the obtained uneven structure was 5 mPa · s. The viscosity was measured at 50 ° C. using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., model number: RE550L).

(Original plate production method)
A glass plate on which a photoresist layer having a uniform thickness was formed was irradiated with two laser beams separated by a beam splitter by a laser interference exposure method to obtain an interference draft. 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 composed of concave and convex portions. In the original plate, the concave portions and the convex portions were each arranged in 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 pitch of the concavo-convex structure was 240 nm and the height was 310 nm. In the stamper, the concave portions and the convex portions are arranged in a hexagonal lattice pattern. Thereafter, the stamper was processed into a cylindrical shape to obtain a stamper roll A having a moth-eye-like continuous structure composed of 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 to 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. A TAC film (manufactured by FUJIFILM Corporation, Fujitac, thickness 80 μm, width 250 mm) was used as the transparent substrate. Then, the composition application surface constituting the concavo-convex structure of the TAC film was brought into contact with the moth-eye continuous structure surface of the above-described stamper roll A, and a metal halide lamp (manufactured by USHIO INC., Model number: UVC-2519-1MNSC7-MS01) was contacted from the film side. ) Was irradiated with UV light at a light amount of 1 J / cm ² . Thereby, the composition which comprises the said uneven structure was photocured. 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.

(Measurement of angle and wavelength dependence of regular 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, incident light angles of 20 ° to 60 ° (20 °, 30 °, 40 °, 45 °, 50 °, 55 °, 60 °, respectively) when S wave polarized light or P wave polarized light is incident. °) and regular reflectance in a wavelength range of 400 to 1000 nm (every 1 nm). 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 regular reflectance at each incident light angle and wavelength.

((Positive + diffuse) 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) (Positive surface + diffuse) reflectivity was determined. The measurement was performed using a spectrocolorimeter (manufactured by Konica Minolta Sensing Co., Ltd., model: CM-2600d). Specifically, the (positive, diffuse) reflectance was measured every 10 nm at a light receiving angle of 8 ° and a wavelength range of 360 to 740 nm when diffused light was incident (measured spot diameter 8 mmφ).

(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. did. A value obtained by subtracting the haze of the base material from the haze of the optical element was taken as Δhaze.

(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.

(Height measurement)
The shape of the concave and convex portions 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 by 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 was confirmed that the height of the convex portion was 200 nm or more. 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 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.

(Standard deviation of recess height)
Based on the data relating to the shape of the concave and convex portions measured using the above scanning probe microscope, the heights of the bottoms of the 40 adjacent concave portions were obtained, and the standard deviation was obtained.

(Standard deviation of convex height)
Based on the data on the shape of the concave and convex portions measured using the scanning probe microscope, the tops of the 40 convex portions adjacent to each other in the target area when calculating the standard deviation of the concave portion height. The height was acquired and its standard deviation was determined.

(Correlation curve between convex height and filling rate)
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.

(Pitch measurement)
By observation with a surface SEM microscope, the distance between the apex of the convex part having a height of 200 nm or more (the highest point) 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 was judged from the surface SEM photograph, and the area (Sall) of the unit cell was obtained.

  Table 1 shows the evaluation results regarding the above items. 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 22 is about 50% of the height of the vertex 20 of the convex portion. FIG. 10A shows the depth distribution of the concavo-convex region, where the highest point position of the bulge is 0 nm. FIG. 11 shows the wavelength dependence and incident light angle dependence of regular reflectance. FIG. 11 shows that the regular reflectance is kept low in a wide wavelength range, and high antireflection performance can be obtained even when the incident light angle is large. 17 to 20 show the incident light angle dependency of the regular reflectance. 17 to 20 show the incident light angle dependency when the wavelength of incident light is 465 nm (blue light), 525 nm (green light), 630 nm (red light), and 900 nm (near infrared light), respectively. Show. FIG. 17 shows that in the case of a wavelength of 465 nm (blue light), extremely high antireflection performance (reflectance of 1% or less) is obtained in the range of the incident angle up to 60 °. Similarly, it can be seen from FIG. 18 that in the case of a wavelength of 525 nm (green light), an extremely high antireflection performance (reflectance of 1% or less) is obtained in the range where the incident angle is up to 60 °. Further, from FIG. 19, in the case of a wavelength of 630 nm (red light), extremely high antireflection performance (reflectance of 1% or less) is obtained in the range up to an incident angle of 55 °, and the incident angle is 55 ° to 60 °. It can be seen that high antireflection performance (reflectance of 2% or less) is also obtained in this range. Further, from FIG. 20, in the case of a wavelength of 900 nm (near infrared light), high antireflection performance (reflectance of 2% or less) is obtained in the range of the incident angle up to 50 °, and the incident angle is 50 ° -60 It can be seen that the necessary antireflection performance (reflectance of 5% or less) is obtained even in the range of °. FIG. 21 shows the wavelength dependence of (positive + diffuse) reflectance. From FIG. 21, it can be seen that (positive + diffuse) reflectance is kept low in a wide wavelength region, and that high antireflection performance is obtained even in a long wavelength region of 600 nm or more. In FIG. 22, the simulation result which shows the reflectance in the incident angle from 0 degree to 60 degrees of the perpendicular | vertical direction of visible region (400 nm-800 nm) is shown. FIG. 22 also shows that high antireflection performance is obtained in a wide wavelength range and a wide incident light angle range, and in particular, sufficient antireflection performance can be obtained even at a high angle of 40 ° or more. . FIG. 25 shows a correlation curve between the height and the filling rate. In the correlation curve shown in FIG. 25, the number of inflection points was four.

(Examples 2-3, Comparative Examples 1-3)
Using the stamper rolls B, C, D, E, and F having different moth-eye continuous structure shapes and arrangement patterns instead of the stamper roll A used in Example 1, the moth-eye continuous structure surface was obtained from each stamper roll. A TAC film roll having The production conditions were all the same except that the stamper rolls were 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. 10A and 10B show the depth distribution of the fine concavo-convex structure with the highest point position of the convex portion being 0 nm (Examples 2 to 3, Comparative Examples 1 to 3). 12 to 16 show the wavelength dependence and incident light angle dependence of regular reflectance (Examples 2 to 3, Comparative Examples 1 to 3). 12 to 16, it can be seen that in Examples 2 and 3, the reflectance is kept low in a wide wavelength range, and high antireflection performance can be obtained even when the incident light angle is large. 17 to 20 show the incident light angle dependency of the regular reflectance (Examples 2 to 3, Comparative Examples 1 to 3). 17 to 20 show the incident light angle dependency when the wavelength of incident light is 465 nm (blue light), 525 nm (green light), 630 nm (red light), and 900 nm (near infrared light), respectively. Show. 17 to 20, it can be seen that in Examples 2 and 3, the same high antireflection performance as in Example 1 is obtained. In particular, Example 3 is extremely excellent in antireflection performance when the incident light angle is large. FIG. 21 shows the wavelength dependence of (positive + diffuse) reflectance (Examples 2 to 3, Comparative Examples 1 to 3). From FIG. 21, it can be seen that also in Examples 2 and 3, the (positive + diffuse) reflectance is kept low in a wide wavelength range. FIG. 26 to FIG. 30 show the correlation curves of height and filling rate (Examples 2 to 3, Comparative Examples 1 to 3). In the correlation curve shown in FIG. 26 (Example 2) and the correlation curve shown in FIG. 27 (Example 3), the number of inflection points was 4, respectively.

(Comparative Examples 4-5)
The reflectivity of a hexagonal lattice-shaped sinusoidal optical element was determined by simulation. The reflectance spectrum was obtained by RCWA simulation (RSsoft DiffractMOD).

  A plurality of sinusoidal shapes in which the concavo-convex structure is arranged in a straight line (pitch and height of the concavo-convex structure are equal to each other) are overlapped at an angle of 60 degrees, and the height value is totaled to obtain the bottom of the recess A basic structure of a sinusoidal shape (Comparative Example 4) having a hexagonal lattice with no variation in the height of the vertices of the convex portions was prepared. In the obtained shape, the pitch and height were adjusted to the average pitch of Example 1 and the average height of irregularities. In the simulation, the created shape was divided every 2 nm in the height direction (Z-axis direction). In addition, a refractive index profile was created from the filling factor of the shape in each cross section with the refractive index of the medium constituting each divided shape being 1.5 and used for the simulation. The calculation area in the plane perpendicular to the height direction (XY plane) is 0.76 micrometers in the major axis direction (X direction) and 1 micrometer in the minor axis direction (Y direction). 16 convex portions and 16 concave portions were accommodated. Harmonics for the X and Y axes were set to 5, and IndexResolution was set to 0.01. The Z-axis Index Resolution was 0.002. The polarization of the incident light was 45 °, and the incident surface was set to the XZ plane. The total reflectivity including high-order diffracted light at the interface of the Z-axis calculation region is calculated in steps of 100 nm from a wavelength of 400 nm to 800 nm and in steps of 10 ° from an incident angle of 0 ° to 60 °, and the reflection of FIG. A spectrum of rates was obtained.

  The sinusoidal shape (Comparative Example 5) in which the heights of the bottoms of the recesses and the tops of the projections vary are based on the sinusoidal shape without any variation (Comparative Example 4) described above, and the recesses and projections adjacent to each other in Example 1 are used. The height of the corresponding concave and convex portions of the sinusoidal shape was adjusted so as to be approximately the same as the variation in the height of the portion. Similarly, a refractive index profile was created from a sinusoidal shape with variations, and the reflectance spectrum of FIG. 24 was obtained under the same calculation conditions. Compared with FIG. 23 and FIG. 24, Comparative Example 5 in which the height of the bottom of the concave portion and the height of the convex portion is different from Comparative Example 4 in which the height of the bottom of the concave portion and the height of the convex portion are aligned. It can be seen that is superior in antireflection performance. Further, by comparing FIG. 22 and FIG. 23, the inflection points in the correlation curve are four in the first embodiment under the same conditions such as the pitch, the height of the concave and convex portions, and the height variation of the concave and convex portions. It can be seen that the antireflection performance is superior to Comparative Example 4 having one inflection point.

  As described above, according to the comparison between the example and the comparative example, the ratio of the area where the apex of the convex part is 200 nm or more in height, the pitch (average value) of the convex part is less than 260 nm, and the height is 250 nm or more (area ratio). ) Is 5% or more, the average deviation of the height of the fine concavo-convex structure is 3 or more and 8 or less, and in the configuration of the example in which there are two or more inflection points in the correlation curve between the height and the filling rate, It can be seen that the antireflection performance is excellent in a wide wavelength region of the near infrared and a wide incident light angle range.

  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 said optical element which concerns on this invention can be produced with sufficient productivity by a roll-to-roll system. The optical element according to 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 Fine concavo-convex structure 11 Convex part 12 Concave part 21 Hexagonal shape 22 Ridge 30 Cross section consisting of concave part and ridge 31 Cross section consisting of concave part and convex part 32 Cross section consisting of convex part and ridge 100 Display device 101 Display element 102 Spacer 103 Previous Face plate 104,106 Antireflection film (optical element)
105 Air layer

Claims (17)

The substrate surface has a fine concavo-convex structure consisting of a plurality of concave portions and a plurality of convex portions,
In the predetermined region of the fine concavo-convex structure, the vertices of the plurality of convex portions are all at a height of 200 nm or more from the reference plane including the lowest point among the bottoms of the plurality of concave portions,
The interval between any vertex of the plurality of convex portions and the vertex of the convex portion closest to the convex portion is less than 260 nm in plan view,
The ratio of the area occupied in the planar view by the region having a height of 250 nm or more from the reference plane to the area of the predetermined region in the planar view 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 the entire fraction in the predetermined region in the 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 is 3 or more and 8 or less. ,
2. The optical element according to claim 1, wherein in the fine concavo-convex structure, there are two or more inflection points in a curve indicating a relationship between a height and a ratio of an area occupied by a region higher than the predetermined region in a plan view.
  The optical element according to claim 1, wherein a standard deviation of the height of the recess is 3 or more and 20 or less.   The optical element according to claim 1 or 2, wherein a standard deviation of the height of the convex portion is 3 or more and 20 or less.   4. The optical element according to claim 1, wherein a ridge exists between the convex portion and a convex portion adjacent to the convex portion. 5.   The optical element according to claim 4, wherein 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.   The optical system according to claim 4 or 5, wherein there are four or eight ridges in an arbitrary unit cell composed of the convex portions and a plurality of convex portions closest to the convex portions. element.   In a unit cell having a structure including the concave portion and the convex portion, a ratio (Sb / Sall) of an area (Sall) of the unit cell and a total area (Sb) of a bottom region having a height of 10 nm or less from the reference surface. The optical element according to claim 1, wherein the optical element is 10% or less.   The optical element according to claim 1, wherein the array pattern of the convex portions or the concave portions is a hexagonal lattice.   A value obtained by dividing the difference between the maximum value and the minimum value among the intervals between the vertices of the convex portions and the vertices of the six convex portions closest to the convex portions by the average value of the intervals [(Pmax−Pmin ) / Pave] is 20% or less.   10. The optical element according to claim 1, wherein a thickness of the composition layer constituting the fine concavo-convex structure is 0.4 μm or more and 10 μm or less.   In 100 parts by mass, 20 to 60 parts by mass of one or more monomer components having 3 or more acrylic groups and / or methacryl groups in one molecule, and 5 to 5 monomer components having an N-vinyl group The optical element according to any one of claims 1 to 10, wherein a composition containing 40 parts by mass 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 constituting the uneven portion is a photocurable composition.   The optical element according to claim 12, wherein a photocurable composition having a viscosity at 50 ° C. of 100 mPa · s or less before photocuring is photocured.   A resin film roll having a width of 10 cm or more and a length of 50 m or more, comprising the optical element according to claim 1.   A display device provided with the optical element according to claim 1.   An illuminating device provided with the optical element according to any one of claims 1 to 13.   A solar cell provided with the optical element according to any one of claims 1 to 13.