Roll mold, optical retardation film, and method for manufacturing optical retardation film

Abstract

To provide a roll mold capable of obtaining a large-area resin film.SOLUTION: A roll mold for transferring a pattern on its outer peripheral surface to a resin film, the roll mold having a diameter of 200 mmφ or more and a total length of 500 mm or more, the outer peripheral surface having a pattern of a plurality of parallel concave / convex portions, the concave portions in the pattern having non-uniform widths and depths, the convex portions having non-uniform widths and heights, a horizontal distance Pm1 between tips of adjacent convex portions being on an order of 100 nm or less, a horizontal distance Pm2 between tips of adjacent concave portions being on an order of 100 nm or less, a maximum value Hmmax of a height difference between adjacent convex portions and concave portions being in a range of 20 nm-100 nm, and an angle α(where 0°≤α≤90°) between an extension direction of the concave portions and a central axis of the roll mold being in a range of 30°-85°.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a roll mold, an optical retardation film, and a method for producing an optical retardation film. [Background technology]

[0002] In recent years, optical retardation films having a nanoscale micro-relief structure have been attracting attention, and nanoimprint technology has also been attracting attention as a method for producing such optical retardation films.

[0003] Nanoimprint technology uses a roll mold with a fine pattern on its outer surface. A substrate coated with a photocurable resin is pressed against the outer surface of this roll mold, and the photocurable resin is cured by UV irradiation to form an alignment layer with the transferred pattern. An optical retardation film can then be produced by placing a liquid crystal layer on top of the pattern in the alignment layer.

[0004] Incidentally, electron beam irradiation or laser irradiation is used as a method for drawing a fine pattern on a roll mold (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-005678 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-043590 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional methods for drawing fine patterns have the problem that it is difficult to enlarge the area of ​​the pattern. For this reason, alignment layers with relatively small patterns, i.e., resin films, have been produced using relatively small roll molds. In this case, in order to enlarge the area of ​​the resin film, multiple resin films must be joined together, which results in the problem of seams.

[0007] The present invention has been made in view of the above background, and an object of the present invention is to provide a roll mold capable of obtaining a seamless large-area resin film. Another object of the present invention is to provide an optical retardation film including such a resin film as an alignment layer. A further object of the present invention is to provide a method for producing such an optical retardation film. [Means for solving the problem]

[0008] In one embodiment of the present invention, A roll mold for transferring a pattern on an outer peripheral surface to a resin film, The diameter is 200mm or more, and the total length is 500mm or more. the outer circumferential surface has a pattern of a plurality of parallel recesses / protrusions; In the pattern, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; Horizontal distance P between the tips of adjacent convex parts m1 is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses m2 is on the order of 100 nm or less, The maximum height difference H between adjacent convex and concave portions mmax is in the range of 20 nm to 100 nm, The roll mold is provided, in which the angle α (where 0°≦α≦90°) formed by the extension direction of the recesses with respect to the central axis of the roll mold is in the range of 30° to 85°.

[0009] In another embodiment of the present invention, An optical retardation film, an alignment layer and a liquid crystal layer; The alignment layer is made of a resin and has a seamless rectangular main surface, and the main surface has a first side L s is 500 mm or more, and the second side W s is 500 mm or more, where L s >W s and the main surface has a pattern of a plurality of parallel recesses / protrusions formed thereon; In the pattern, the horizontal distance P between the tips of adjacent convex portions s1 is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses s2 is on the order of 100 nm or less, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; The maximum height difference H between adjacent convex and concave portions smax is in the range of 20 nm to 100 nm, The optical retardation film is provided, wherein the angle β (where 0°≦β≦90°) formed by the second side and the extension direction of the recess is in the range of 30° to 85°.

[0010] Furthermore, in another embodiment of the present invention, A method for producing an optical retardation film, comprising: (I) preparing a roll mold having a diameter of 200 mm or more and a total length of 500 mm or more; (II) polishing the outer peripheral surface of the roll mold to form a pattern of a plurality of parallel recesses / protrusions on the outer peripheral surface, In the pattern, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; Horizontal distance P between the tips of adjacent convex parts m1 is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses m2 is on the order of 100 nm or less, The maximum height difference H between adjacent convex and concave portions mmaxis in the range of 20 nm to 100 nm, The angle α (where 0°≦α≦90°) formed by the extension direction of the recess with respect to the central axis of the roll mold is in the range of 30° to 85°; (III) transferring the pattern to a first main surface of a resin film; (IV) providing a liquid crystal layer on the first main surface of the resin film; A method is provided, comprising: [Effects of the Invention]

[0011] The present invention can provide a roll mold capable of producing a seamless large-area resin film. The present invention can also provide an optical retardation film including such a resin film as an alignment layer. Furthermore, the present invention can also provide a method for producing such an optical retardation film. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic perspective view of a roll mold according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram schematically illustrating a cross section taken along line AA in the partially enlarged view of FIG. [Figure 3] 1 is a schematic cross-sectional view of an optical retardation film according to one embodiment of the present invention. [Figure 4] 1 is a schematic front view of an alignment layer included in an optical retardation film according to one embodiment of the present invention. [Figure 5] 5 is a diagram schematically showing a cross section taken along line BB in the partially enlarged view of FIG. 4. FIG. [Figure 6] FIG. 1 is a diagram schematically illustrating an example of a flow of a method for producing an optical retardation film according to one embodiment of the present invention. [Figure 7] FIG. 2 is a diagram showing an example of an atomic force microscope (AFM) image of a cross section of a resin film to which a pattern of a roll mold according to one embodiment of the present invention has been transferred. [Figure 8]FIG. 10 is a diagram showing an example of a cross-sectional AFM image of a resin film onto which a pattern of a roll mold has been transferred according to another embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing an example of a cross-sectional AFM image of a resin film onto which a pattern of a roll mold has been transferred according to yet another embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of a cross-sectional AFM image of a resin film onto which a pattern of a roll mold has been transferred according to yet another embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing an example of a cross-sectional AFM image of a resin film onto which a pattern of a roll mold has been transferred according to yet another embodiment of the present invention. [Figure 12] FIG. 10 is a diagram showing an example of a cross-sectional AFM image of a resin film to which a pattern of a roll mold has been transferred according to a comparative example. [Figure 13] FIG. 10 is a diagram showing an example of a cross-sectional AFM image of a resin film to which a roll mold pattern has been transferred according to another comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will be described below.

[0014] As described above, conventional methods for drawing fine patterns have the problem that it is difficult to enlarge the area of ​​the pattern, and it is difficult to provide a large roll mold.

[0015] In contrast to this, in one embodiment of the present invention, A roll mold for transferring a pattern on an outer peripheral surface to a resin film, The diameter is 200mm or more, and the total length is 500mm or more. the outer circumferential surface has a pattern of a plurality of parallel recesses / protrusions; In the pattern, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; Horizontal distance P between the tips of adjacent convex parts m1is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses m2 is on the order of 100 nm or less, The maximum height difference H between adjacent convex and concave portions mmax is in the range of 20 nm to 100 nm, The roll mold is provided, in which the angle α (where 0°≦α≦90°) formed by the extension direction of the recesses with respect to the central axis of the roll mold is in the range of 30° to 85°.

[0016] As will be described later, in the roll mold according to one embodiment of the present invention, the pattern on the outer peripheral surface is formed by polishing.

[0017] This method has fewer dimensional restrictions than conventional electron beam irradiation or laser irradiation methods, and therefore can provide a relatively large roll mold. That is, the roll mold according to one embodiment of the present invention can be made large, with a diameter of 200 mm or more and a total length of 500 mm or more.

[0018] Furthermore, when the roll mold according to one embodiment of the present invention is used, the area of ​​the resin film onto which the concave-convex pattern is transferred can also be increased.

[0019] That is, in another embodiment of the present invention, An optical retardation film, an alignment layer and a liquid crystal layer; The alignment layer is made of a resin and has a seamless rectangular main surface, and the main surface has a first side L s is 500 mm or more, and the second side W s is 500 mm or more, where L s >W s and the main surface has a pattern of a plurality of parallel recesses / protrusions formed thereon; In the pattern, the horizontal distance P between the tips of adjacent convex portions s1 is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses s2 is on the order of 100 nm or less, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; The maximum height difference H between adjacent convex and concave portions smax is in the range of 20 nm to 100 nm, The optical retardation film is provided, wherein the angle β (where 0°≦β≦90°) formed by the second side and the extension direction of the recess is in the range of 30° to 85°.

[0020] When a conventional small roll mold is used, it is necessary to join a plurality of resin films together in order to increase the area of ​​the resin film for the alignment layer of the optical retardation film.

[0021] In contrast to this, in one embodiment of the present invention, a seamless resin film can be obtained that has a pattern formed on a large main surface area of ​​500 mm x 500 mm or more.

[0022] Therefore, in one embodiment of the present invention, an optical retardation film having a large area alignment layer can be obtained.

[0023] (Roll mold according to one embodiment of the present invention) Hereinafter, a roll mold according to one embodiment of the present invention will be described in more detail with reference to FIGS.

[0024] FIG. 1 shows a schematic perspective view of a roll mold according to one embodiment of the present invention.

[0025] 1, a roll mold 100 according to one embodiment of the present invention (hereinafter simply referred to as a "first roll mold") has a generally cylindrical shape extending along a central axis E. Therefore, the first roll mold 100 has two generally circular end faces (a first end face 102 and a second end face 104) and an outer circumferential surface 106 extending between the end faces.

[0026] The diameter φ of the first end surface 102 and the second end surface 104 of the first roll mold 100m The total length L of the first roll mold 100 is 200 mm or more, and preferably 300 mm or more. m is 500 mm or more, and preferably in the range of 600 mm to 2000 mm.

[0027] On the outer peripheral surface 106 of the first roll mold 100, a pattern 120 of minute projections and depressions on the order of nm is formed.

[0028] As shown in the partially enlarged view in FIG. 1, the pattern 120 has a concave-convex structure.

[0029] More specifically, the pattern 120 has a plurality of protrusions 122 and recesses 124 (described later), each of which extends in the same direction. When the angle between the central axis E of the first roll mold 100 and the extension direction of the recesses / protrusions in the pattern 120 is defined as a first angle α (where α is in the range of 0° to 90°), the first angle α is 30°≦α≦85°. The first angle α is preferably 40°≦α≦50°, e.g., α=45°.

[0030] Fig. 2 shows a schematic cross section taken along line AA in the partially enlarged view of Fig. 1. Here, line AA is a straight line substantially perpendicular to the extending direction of the recessed / protruding portions.

[0031] As shown in FIG. 2, the pattern 120 formed on the outer peripheral surface 106 of the first roll mold 100 has a plurality of protrusions 122 and a plurality of recesses 124 .

[0032] 2, the protrusions 122 do not have periodicity, and therefore the widths and heights of the respective protrusions 122 are irregular. Similarly, the recesses 124 do not have periodicity, and therefore the widths and depths of the respective recesses 124 are irregular.

[0033] Here, the horizontal distance between the tips of adjacent convex portions 122 is P m1 Then, P m1is on the order of 100 nm or less. Similarly, the horizontal distance between the tips of adjacent recesses 124 is P m2 Then, P m2 is on the order of 100 nm or less.

[0034] The height difference between the adjacent convex portion 122 and concave portion 124 is H max The maximum value is H mmax When H mmax is in the range of 20nm to 100nm. mmax is preferably in the range of 25 nm to 500 nm.

[0035] In addition, the aforementioned dimension P m1 can also be considered as the width dimension of the recessed portion 124 sandwiched between the target protruding portions 122. Similarly, the aforementioned dimension P m2 can also be considered as the width dimension of the convex portion 122 sandwiched between the target concave portions 124.

[0036] In this way, the pattern 120 formed on the outer peripheral surface 106 of the first roll mold 100 has a fine uneven structure on the order of nm.

[0037] Therefore, when a resin film is placed on the outer peripheral surface 106 of the first roll mold 100 and a pattern 120 is transferred onto the resin film, a resin film having a pattern of numerous nanometer-order concave and convex portions extending in one direction can be obtained.

[0038] The first roll mold 100 has a diameter φ m is 200 mm or more, and the total length L m Therefore, by this transfer step, it is possible to produce a resin film having a seamless concave-convex pattern over a large area.

[0039] The material of the first roll mold 100 is not particularly limited as long as it can properly transfer the pattern 120 on the outer peripheral surface 106 to the resin film. For example, the first roll mold 100 may be made of a metal such as carbon steel or stainless steel.

[0040] Alternatively, the first roll mold 100 may have a cylindrical central core and a coating film provided on the outer circumferential surface of the central core. In this case, the central core may be made of the above-mentioned metal.

[0041] On the other hand, the coating film is selected from a material that can be polished to properly form a nm-order pattern 120 on its surface. In particular, the coating film is preferably selected from a material that has good adhesion to the outer circumferential surface of the central core. For example, the coating film may be made of a metal such as nickel or chromium, or a compound such as nickel phosphorus or nickel boron.

[0042] The thickness of the coating film is not particularly limited, but may be, for example, in the range of 100 μm to 500 μm.

[0043] (Optical Retardation Film According to an Embodiment of the Invention) Next, the optical retardation film according to one embodiment of the present invention will be described in more detail with reference to FIGS.

[0044] FIG. 3 shows a schematic cross-sectional view of an optical retardation film (hereinafter referred to as "first optical retardation film") 200 according to one embodiment of the present invention.

[0045] As shown in FIG. 3, the first optical retardation film 200 has a substrate 210, an alignment layer 220, and a liquid crystal layer 250 in this order.

[0046] The alignment layer 220 has a first major surface 222 and a second major surface 224 opposite each other. The liquid crystal layer 250 is disposed on the first major surface 222 side of the alignment layer 220, and the substrate 210 is disposed on the second major surface 224 side of the alignment layer 220.

[0047] The first optical retardation film 200 has a substantially rectangular sheet shape, and has a first side (long side) along the Y direction in FIG. 3 and a second side (short side) along the X direction in FIG.

[0048] FIG. 4 shows a schematic front view of the alignment layer 220 included in the first optical retardation film 200. As shown in FIG.

[0049] 4, the alignment layer 220 has a substantially rectangular sheet shape, and has a first side (long side) 232 and a second side (short side) 234. The first side 232 has a length Ls, and the second side 234 has a length Ws.

[0050] The length Ls of the first side 232 is 500 mm or more, and the length Ws of the second side 234 is 500 mm or more, where Ls>Ws.

[0051] The alignment layer 220 is seamless and consists of a single resin film.

[0052] Furthermore, in the alignment layer 220, a pattern 240 of minute projections and depressions on the order of nm is formed on the first main surface 222.

[0053] As shown in the partially enlarged view in FIG. 4, the pattern 240 has a concave-convex structure.

[0054] More specifically, the pattern 240 has a plurality of protrusions 242 and recesses 244 (described later), each of which extends in the same direction. In the alignment layer 220, the angle between the extension direction of the second side 234 and the extension direction of the recesses / protrusions in the pattern 240 is defined as a second angle β (where β is in the range of 0° to 90°), and the second angle β is 30°≦β≦85°. The second angle β is preferably 40°≦α≦50°, e.g., α=45°.

[0055] Fig. 5 shows a schematic cross section taken along line BB in the partially enlarged view of Fig. 4. Here, line BB is a straight line substantially perpendicular to the extending direction of the recessed / protruding portions.

[0056] As shown in FIG. 5, the pattern 240 formed on the first main surface 222 of the alignment layer 220 has a plurality of protrusions 242 and a plurality of recesses 244 .

[0057] 5, the protrusions 242 do not have periodicity, and therefore the widths and heights of the respective protrusions 242 are irregular. Similarly, the recesses 244 do not have periodicity, and therefore the widths and depths of the respective recesses 244 are irregular.

[0058] Here, the horizontal distance between the tips of adjacent convex portions 242 is P s1 Then, P s1 is on the order of 100 nm or less. Similarly, the horizontal distance between the tips of adjacent recesses 244 is P s2 Then, P s2 is on the order of 100 nm or less.

[0059] The height difference between the adjacent convex portion 242 and concave portion 244 is H smax The maximum value is H smax When H smax is in the range of 20nm to 100nm. smax is preferably in the range of 25 nm to 500 nm.

[0060] In addition, the aforementioned dimension P s1 can also be considered as the width dimension of the recessed portion 244 sandwiched between the target protruding portions 242. Similarly, the aforementioned dimension P s2 can also be considered as the width dimension of the convex portion 242 sandwiched between the target concave portions 244.

[0061] In this way, the pattern 240 formed on the first main surface 222 of the alignment layer 220 has a fine uneven structure on the order of nm.

[0062] Typically, an alignment layer 220, i.e., a resin film, having a main surface on which a fine uneven pattern is formed over such a large area is constructed by joining together multiple resin films, and therefore there is a problem in that seams remain.

[0063] However, the alignment layer 220 can be formed using a large roll mold, such as the above-described first roll mold 100. This allows the production of an alignment layer 220 having a seamless pattern over a large area.

[0064] 4, the alignment layer 220 (and further the first optical retardation film 200) is provided in a form having a substantially rectangular first main surface 222. However, alternatively, the alignment layer 220 (and further the first optical retardation film 200) may be provided in the form of a roll wound along the Y direction in FIG. 4, i.e., the direction of the first side 232.

[0065] The first optical retardation film 200 having such an alignment layer 220 has a feature that, when used as a retardation plate, the variation in retardation Rd, which will be described later, is significantly reduced.

[0066] This is thought to be because in the first optical retardation film 200, the fine uneven structure included in the alignment layer 220 and the stretching angle β thereof allow the liquid crystals included in the liquid crystal layer 250 to be aligned more uniformly.

[0067] (Components included in the optical retardation film according to one embodiment of the present invention) Next, other features of each member included in the first optical retardation film 200 will be described.

[0068] (Substrate 210) The substrate 210 may be made of, for example, a transparent cycloolefin polymer or an acrylic resin.

[0069] The substrate 210 is not an essential component and may be omitted in some optical retardation films.

[0070] (Alignment layer 220) The alignment layer 220 is made of an energy curable resin, which may be, for example, a UV curable resin or a thermosetting resin.

[0071] The alignment layer 220 has a thickness in the range of, for example, 150 nm to 20 μm. The thickness of the alignment layer 220 is preferably in the range of 200 nm to 10 μm, and more preferably in the range of 300 nm to 5 μm.

[0072] (Liquid crystal layer 250) The liquid crystal layer 250 includes a plurality of liquid crystal molecules aligned parallel to each other by the alignment layer 220 .

[0073] The type of liquid crystal is not particularly limited, and may be, for example, a rod-shaped liquid crystal or a discotic liquid crystal.

[0074] The liquid crystal layer 250 has a slow axis and a fast axis. When viewed in the thickness direction, the slow axis is the direction in which the refractive index is greatest, and the fast axis is the direction in which the refractive index is smallest.

[0075] The retardation Rd is calculated by multiplying the difference Δn (Δn=ne−no) between the refractive index of the slow axis ne and the refractive index of the fast axis no by the dimension d in the thickness direction of the liquid crystal layer 250. In other words, the retardation Rd can be calculated by the formula Rd=Δn×d.

[0076] (Method of manufacturing an optical retardation film according to one embodiment of the present invention) Next, an example of a method for producing an optical retardation film having the above-mentioned characteristics will be described with reference to FIG.

[0077] FIG. 6 shows an example of the flow of a method for producing an optical retardation film according to one embodiment of the present invention (hereinafter referred to as "first method").

[0078] As shown in Figure 6, the first method is (I) a step (step S110) of preparing a roll mold having a diameter of 200 mm or more and a total length of 500 mm or more; (II) polishing the outer peripheral surface of the roll mold to form a pattern of a plurality of parallel recesses / protrusions on the outer peripheral surface (step S120); (III) transferring the pattern to a first main surface of a resin film (step S130); (IV) placing a liquid crystal layer on the first main surface of the resin film (step S140); It has.

[0079] Each step will be described below. In the following description, as an example, a method for producing a first optical retardation film 200 as shown in Figures 3 to 5 using a first roll mold 100 as shown in Figures 1 and 2 will be described.

[0080] Therefore, the reference numerals shown in FIGS. 1 to 5 are used to represent the respective members.

[0081] (Step S110) First, a first roll mold 100 is provided.

[0082] The first roll mold 100 has a diameter φ m is 200mmφm or more, total length L m has a cylindrical shape of 500 mm or more.

[0083] As described above, the first roll mold 100 may have a cylindrical central core and a coating film disposed around the central core.

[0084] The coating film may be formed on the outer peripheral surface of the center core by, for example, electrolytic plating, etc. The thickness of the coating film may be in the range of, for example, 100 μm to 500 μm.

[0085] Next, the outer peripheral surface 106 of the first roll mold 100 is mechanically polished (hereinafter referred to as "smoothing polishing process"). This smoothing polishing process is carried out to smooth the outer peripheral surface 106 before forming a fine uneven structure in the next process.

[0086] The smoothing polishing process is carried out using a polishing pad and polishing slurry. The polishing slurry contains abrasives (abrasive grains). By performing polishing several times, a sufficiently smooth outer surface 106 with a surface roughness Ra of 10 nm can be finally obtained.

[0087] (Step S120) Next, a pattern 120 is formed on the outer peripheral surface 106 of the first roll mold 100 by a polishing process (hereinafter referred to as "unevenness-forming polishing process") separate from the smoothing polishing process of step S110.

[0088] Specifically, a pattern 120 is formed having the following characteristics: The pattern 120 has a plurality of parallel extending protrusions 122 and recesses 124; The protrusions 122 are of varying widths and heights, and the recesses 124 are of varying widths and heights; The horizontal distance P between the tips of adjacent protrusions 122 m1 is on the order of 100 nm or less, and the horizontal distance P m2 is on the order of 100 nm or less; The maximum height difference H between the adjacent convex portion 122 and concave portion 124 mmax is in the range of 20 nm to 100 nm; The angle α (where 0°≦α≦90°) formed by the extension direction of the recesses 124 with respect to the central axis E of the first roll mold 100 is in the range of 30° to 85°.

[0089] In order to form such a pattern 120, the following steps are carried out in the unevenness forming polishing process. (1) First, a polishing pad is placed on the first end face 102 of the first roll mold 100 or on the outer peripheral surface 106 near the first end face 102. Next, while the first roll mold 100 is rotated about the central axis E, the first roll mold 100 or the polishing pad is translated in a first direction parallel to the central axis E to the second end face 104 of the first roll mold 100 or near the second end face 104 (first pass). (2) Next, a polishing pad is again placed on the first end face 102 of the first roll mold 100 or on the outer peripheral surface 106 in the vicinity thereof. Then, the polishing of (1) is carried out again (second pass). (3) The same process is repeated 20 or more times. The total number of passes may be in the range of 50 to 200, for example.

[0090] In each of the above-described steps (1) to (3), a slurry containing an abrasive (abrasive grains) is continuously supplied to the polishing pad. The abrasive is pressed against the outer peripheral surface 106 of the first roll mold 100 via the polishing pad, thereby forming a concave-convex pattern 120.

[0091] The particle size of the abrasive grains used is smaller than the optical wavelength expected in the optical retardation film 200. For example, when use in the visible light region is expected, abrasive grains with an average particle size of 100 nm to 200 nm are used.

[0092] In steps (1) to (3), the rotation speed of the first roll mold 100 is set to be substantially equal, and the translational movement speed is also set to be substantially equal.

[0093] By combining various rotational speeds and translational speeds, the extending direction of the convex portions 122 and concave portions 124 formed on the outer peripheral surface 106 (the first angle α described above) can be controlled.

[0094] For example, the diameter φ mWhen the first roll mold 100 having a circumference of 200 mm (circumferential length of 628 mm) rotates 45 times per minute, the first angle α can be set to 45° by setting the translation speed to 471 mm per second. By changing the ratio between the two, it is possible to form a pattern 120 of protrusions 122 and recesses 124 having any desired first angle α.

[0095] (Step S130) Next, the pattern 120 formed on the outer peripheral surface 106 of the first roll mold 100 is transferred to the resin film, and an alignment layer 220 for the first optical retardation film 200 is formed.

[0096] The resin film uses a copolymer of an energy curable composition.

[0097] The energy curable composition is, for example, a photocurable composition or a thermosetting composition, with photocurable compositions being particularly preferred due to their excellent processability, heat resistance and durability.

[0098] The photocurable composition may be, for example, one described in paragraphs 0028 to 0060 of Japanese Patent No. 5978761. The photocurable composition contains, for example, a fluorine-containing monomer and a photocurable monomer that does not contain fluorine element.

[0099] A nanoimprint method is used when manufacturing a resin film for the alignment layer 220. That is, first, an energy curable composition is sandwiched between the substrate and the outer peripheral surface 106 of the first roll mold 100.

[0100] In this state, the first roll mold 100 is rotated around the central axis E to transfer the pattern 120 to the energy curable composition, and energy is applied to the energy curable composition. As a result, the energy curable composition is cured with the pattern 120 transferred, and a resin film is formed.

[0101] The energy curable composition may be coated onto a substrate or onto the outer peripheral surface 106 of the first roll mold 100 .

[0102] Examples of the coating method include spin coating, bar coating, dip coating, casting, spray coating, bead coating, wire bar coating, blade coating, roller coating, curtain coating, slit die coating, gravure coating, slit reverse coating, microgravure coating, and comma coating.

[0103] The resin film may also be supplied and collected using a roll-to-roll method.

[0104] (Step S140) Next, a liquid crystal layer 250 is placed on the first main surface 222 of the resulting resin film (ie, alignment layer 220) on which the pattern 240 has been formed.

[0105] The liquid crystal layer 250 is formed by applying a liquid crystal composition and then drying it.

[0106] The liquid crystal composition contains a photocurable liquid crystal containing an acrylic group or a methacrylic group. The liquid crystal composition may contain a component that does not exhibit a liquid crystal phase by itself, as long as a liquid crystal phase is generated by polymerization. The liquid crystal composition may contain a photocurable monomer. The polymerizable liquid crystal composition may contain an additive. Examples of the additive include a polymerization initiator, a surfactant, a chiral agent, a polymerization inhibitor, an ultraviolet absorber, an antioxidant, a light stabilizer, an antifoaming agent, and a dichroic dye. Multiple types of additives may be used in combination.

[0107] The liquid crystal composition may be applied onto the alignment layer 220 by a common application method.

[0108] The liquid crystal composition may be applied by, for example, spin coating, bar coating, extrusion coating, direct gravure coating, reverse gravure coating, or die coating.

[0109] The solvent in the liquid crystal composition is removed by heating after application.

[0110] The solvent for the liquid crystal composition is, for example, an organic solvent, such as an alcohol (e.g., isopropyl alcohol), an amide (e.g., N,N-dimethylformamide), a sulfoxide (e.g., dimethyl sulfoxide), a hydrocarbon (e.g., benzene or hexane), an ester (e.g., methyl acetate, ethyl acetate, butyl acetate, or propylene glycol monoethyl ether acetate), a ketone (e.g., acetone, cyclohexanone, or methyl ethyl ketone), or an ether (e.g., tetrahydrofuran or 1,2-dimethoxyethane).

[0111] Two or more organic solvents may be used in combination.

[0112] The liquid crystal layer 250 may be formed by evaporation or vacuum injection, which does not use a solvent.

[0113] The liquid crystal composition used may be one in which the wavelength dispersion of the Δn value after curing is positive or negative.

[0114] In the first method, the first optical retardation film 200 can be manufactured by the above steps. [Example]

[0115] Examples of the present invention will be described below, in which Examples 1 to 5 are examples, and Examples 11 and 12 are comparative examples.

[0116] (Example 1) An optical retardation film was prepared by the following method.

[0117] (Roll mold production) First, a roll mold was prepared. The roll mold had a diameter of φ m =200mm, total length L mThe specimen was made of carbon steel with a cylindrical shape of 2000 mm.

[0118] Next, a nickel-phosphorus coating film was formed on the outer circumferential surface of this roll mold by electrolytic plating, with the target thickness of the coating film being 300 μm.

[0119] Next, the coating film was polished using a polishing pad and an abrasive (smoothing polishing process) to smooth the surface of the coating film, and the surface of the coating film was finally finished to a surface roughness Ra of 10 nm or less.

[0120] Next, a fine uneven structure was formed on the outer peripheral surface of the roll mold by the steps (1) to (3) of the unevenness forming polishing treatment described above.

[0121] The mold rotation speed was 60 rpm, and the translation speed was 39 mm / sec. Under these conditions, it was predicted that a pattern would be obtained in which the first angle α, i.e., the angle between the central axis of the first roll mold and the extension direction of the irregularities (first angle α), would be 83°.

[0122] During each pass, a slurry containing an abrasive was continuously supplied to the polishing pad, with the abrasive grains having an average particle size of 100 nm.

[0123] The total number of passes was 100. In addition, the abrasive was not reused in each pass, and new abrasive grains were used for each pass.

[0124] As a result, a roll mold (hereinafter referred to as "roll mold A") having a fine uneven pattern on the outer peripheral surface was produced.

[0125] (Production of resin film) Next, a resin film having the pattern of the outer peripheral surface of roll mold A transferred onto its main surface was produced by the following method.

[0126] First, a photocurable resin composition was applied to the surface of the substrate by spin coating.

[0127] The substrate was made of acrylic resin (polymethyl methacrylate). The photocurable resin composition contained a monofunctional methacrylate, a trifunctional methacrylate, and a surfactant.

[0128] Next, the surface of the substrate on which the photocurable resin composition was placed was pressed against the outer circumferential surface of roll mold A, and UV rays were irradiated to cure the photocurable resin composition.

[0129] The obtained resin film (hereinafter referred to as "resin film A") was approximately rectangular, with a first side of 500 mm, a second side (in the direction of the central axis of roll mold A) of 500 mm, and a thickness of approximately 100 μm.

[0130] (Production of optical retardation film) Next, a liquid crystal layer was disposed on the resin film A to prepare an optical retardation film.

[0131] The liquid crystal layer was formed by placing it on the resin film A by a die coating method and curing the liquid crystal composition with ultraviolet light.

[0132] Through the above steps, an optical retardation film (hereinafter referred to as "optical retardation film A") was obtained.

[0133] (Example 2) Using the same method as in Example 1, a roll mold (hereinafter referred to as "roll mold B"), a resin film (hereinafter referred to as "resin film B"), and an optical retardation film (hereinafter referred to as "optical retardation film B") were produced.

[0134] However, in Example 2, the rotation speed when forming a pattern on the outer peripheral surface of roll mold B was set to 45 rpm and the translation speed was set to 471 mm / sec. Under these conditions, it is expected that a pattern having a first angle α of 45° will be obtained.

[0135] Other preparation conditions were the same as in Example 1.

[0136] (Example 3) Using the same method as in Example 1, a roll mold (hereinafter referred to as "roll mold C"), a resin film (hereinafter referred to as "resin film C"), and an optical retardation film (hereinafter referred to as "optical retardation film C") were produced.

[0137] However, in Example 3, the rotation speed when forming a pattern on the outer peripheral surface of the roll mold C was set to 30 rpm and the translation speed was set to 544 mm / sec. Under these conditions, it is expected that a pattern having a first angle α of 30° will be obtained.

[0138] Other preparation conditions were the same as in Example 1.

[0139] (Example 4) Using the same method as in Example 2, a roll mold (hereinafter referred to as "roll mold D"), a resin film (hereinafter referred to as "resin film D"), and an optical retardation film (hereinafter referred to as "optical retardation film D") were produced.

[0140] However, in Example 4, the outer peripheral surface of the roll mold was electroplated with a nickel film.

[0141] Other preparation conditions were the same as in Example 2.

[0142] (Example 5) Using the same method as in Example 3, a roll mold (hereinafter referred to as "roll mold E"), a resin film (hereinafter referred to as "resin film E"), and an optical retardation film (hereinafter referred to as "optical retardation film E") were produced.

[0143] However, in Example 5, the outer peripheral surface of the roll mold was electroplated with a nickel film.

[0144] Other preparation conditions were the same as in Example 3.

[0145] (Example 11) Using the same method as in Example 1, a roll mold (hereinafter referred to as "roll mold F"), a resin film (hereinafter referred to as "resin film F"), and an optical retardation film (hereinafter referred to as "optical retardation film F") were produced.

[0146] However, in Example 11, the rotation speed when forming a pattern on the outer peripheral surface of the roll mold F was set to 30 rpm and the translation speed was set to 673 mm / sec. Under these conditions, it is expected that a pattern having a first angle α of 25° will be obtained.

[0147] Other preparation conditions were the same as in Example 1.

[0148] (Example 12) Using the same method as in Example 1, a roll mold (hereinafter referred to as "roll mold G"), a resin film (hereinafter referred to as "resin film G"), and an optical retardation film (hereinafter referred to as "optical retardation film G") were produced.

[0149] However, in Example 12, the rotation speed when forming a pattern on the outer peripheral surface of the roll mold G was set to 30 rpm and the translation speed was set to 1781 mm / sec. Under these conditions, it is expected that a pattern having a first angle α of 10° will be obtained.

[0150] Other preparation conditions were the same as in Example 1.

[0151] Table 1 below shows the manufacturing conditions for roll molds A to G in each example.

[0152] [Table 1] (evaluation) Next, the following evaluations were carried out.

[0153] (Evaluation of patterns formed on resin films) Using each resin film, the uneven structure formed on the surface was evaluated.

[0154] First, a sample of a predetermined size was taken from the approximate center of each of resin films A to G. Next, the surface morphology of each sample was observed using an atomic force microscope (AFM). In particular, the extension direction of the recesses / protrusions was observed, and the second angle β, i.e., the angle between the direction of the second side (corresponding to the central axis direction of the roll mold) and the extension direction of the recesses / protrusions, was evaluated.

[0155] Next, the sample was cut in a direction perpendicular to the second angle β, and the resulting cross sections were observed using an AFM device. The shapes of the recesses and protrusions were also evaluated from each cross section.

[0156] 7 to 13 show cross-sectional AFM images obtained for resin films A to G, respectively.

[0157] These results show that in resin films A to E, convex portions with non-uniform heights and widths and concave portions with non-uniform depths and widths are formed non-periodically. On the other hand, in the case of resin film F and resin film G, the height of the convex portions and the depth of the concave portions in the pattern are small, and it can be seen that there is not much difference in height.

[0158] Table 2 below shows the evaluation results of the concave-convex structures obtained in resin films A to G.

[0159] [Table 2] It can be seen from Table 2 that the stretching direction of the irregularities (second angle β) in resin films A to E is consistent with the expected value of the first angle α (see Table 1) in the corresponding roll molds A to G. From this, it is expected that the patterns formed on the outer peripheral surfaces of the roll molds A to G are equivalent to the patterns formed on the corresponding resin films A to E (i.e., P m1 ≒P S1 , P m2 ≒P S2 , and H mmax ≒H Smax etc.).

[0160] (Retardation Rd) The retardation Rd was evaluated using each optical phase difference film.

[0161] The retardation Rd was evaluated using Photal manufactured by Otsuka Electronics Co., Ltd. The measurement points were 25 points obtained by dividing the main surface on which the pattern of the optical retardation film was formed into 5 equal parts vertically and horizontally, and therefore the number of measurements was 25.

[0162] At each measurement point, retardation Rd was measured at a wavelength of 540 nm. The average was calculated from the obtained measurements, and the variation (σ) was calculated.

[0163] Table 3 below shows the evaluation results of the retardation Rd obtained for each optical phase difference film.

[0164] [Table 3] From these results, it was confirmed that the in-plane variation in retardation Rd was significantly suppressed in optical retardation films A to E compared to optical retardation films F and G.

[0165] (Aspects of the present invention) The present invention has the following aspects.

[0166] (Aspect 1) A roll mold for transferring a pattern on an outer peripheral surface to a resin film, The diameter is 200mm or more, and the total length is 500mm or more. the outer circumferential surface has a pattern of a plurality of parallel recesses / protrusions; In the pattern, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; Horizontal distance P between the tips of adjacent convex parts m1 is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses m2 is on the order of 100 nm or less, The maximum height difference H between adjacent convex and concave portions mmax is in the range of 20 nm to 100 nm, A roll mold, wherein an angle α (where 0°≦α≦90°) formed by the extension direction of the recesses with respect to the central axis of the roll mold is in the range of 30° to 85°.

[0167] (Aspect 2) An optical retardation film, an alignment layer and a liquid crystal layer; The alignment layer is made of a resin and has a seamless rectangular main surface, and the main surface has a first side L s is 500 mm or more, and the second side W s is 500 mm or more, where L s >W s and the main surface has a pattern of a plurality of parallel recesses / protrusions formed thereon; In the pattern, the horizontal distance P between the tips of adjacent convex portions s1 is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses s2 is on the order of 100 nm or less, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; The maximum height difference H between adjacent convex and concave portionssmax is in the range of 20 nm to 100 nm, An optical retardation film, wherein the angle β (0°≦β≦90°) formed by the second side and the extension direction of the recess is in the range of 30° to 85°.

[0168] (Aspect 3) 3. The optical retardation film of embodiment 2, further comprising a substrate disposed on the alignment layer opposite the liquid crystal layer.

[0169] (Aspect 4) The optical retardation film according to embodiment 2 or 3, wherein the alignment layer has a thickness in the range of 150 nm to 20 μm.

[0170] (Aspect 5) A method for producing an optical retardation film, comprising: (I) preparing a roll mold having a diameter of 200 mm or more and a total length of 500 mm or more; (II) polishing the outer peripheral surface of the roll mold to form a pattern of a plurality of parallel recesses / protrusions on the outer peripheral surface, In the pattern, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; Horizontal distance P between the tips of adjacent convex parts m1 is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses m2 is on the order of 100 nm or less, The maximum height difference H between adjacent convex and concave portions mmax is in the range of 20 nm to 100 nm, The angle α (where 0°≦α≦90°) formed by the extension direction of the recess with respect to the central axis of the roll mold is in the range of 30° to 85°; (III) transferring the pattern to a first main surface of a resin film; (IV) providing a liquid crystal layer on the first main surface of the resin film; A method comprising:

[0171] (Aspect 6) Aspect 6. The method according to aspect 5, wherein in (I), the outer peripheral surface of the roll mold is polished to have a surface roughness Ra of 10 nm or less.

[0172] (Aspect 7) The (II) is (1) disposing a polishing pad on a first end face of the roll mold or on the outer peripheral surface in the vicinity thereof; and, while rotating the roll mold around a central axis, translating the roll mold or the polishing pad along a first direction parallel to the central axis to a second end face of the roll mold or in the vicinity thereof; (2) placing the polishing pad on the first end face of the roll mold or on the outer peripheral surface in the vicinity thereof again, and carrying out (1); and (3) Repeat the above (2) 20 or more times. 7. The method of embodiment 5 or embodiment 6, comprising:

[0173] (Aspect 8) Aspect 8. The method according to aspect 7, wherein in (II), a slurry containing abrasive grains is supplied to the polishing pad, and the abrasive grains are not reused during (1) to (3).

[0174] (Aspect 9) 9. The method of claim 8, wherein the abrasive grains have an average particle size in the range of 10 nm to 300 nm.

[0175] (Aspect 10) The above (III) is applying an energy curable composition to a substrate; applying energy to the energy curable composition while pressing the substrate coated with the energy curable composition against the roll mold to cure the energy curable composition; and

[0023] Embodiment 10. The method of any one of embodiments 5 to 9, comprising:

[0176] (Aspect 11) The method according to any one of aspects 5 to 10, wherein in (III), the substrate is supplied by a roll-to-roll method. [Explanation of symbols]

[0177] 100 First Roll Mold 102 first end face 104 Second end face 106 Outer surface 120 patterns 122 convex part 124 recess 200 First optical retardation film 210 Substrate 220 Orientation Layer 222 first major surface 224 Second main surface 232 First side (long side) 234 Second side (short side) 240 patterns 242 convex part 244 recess 250 LCD layers

Claims

1. A roll mold for transferring a pattern on an outer peripheral surface to a resin film, The diameter is 200 mm or more and the total length is 500 mm or more, the outer circumferential surface has a pattern of a plurality of parallel recesses / protrusions; In the pattern, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; Horizontal distance P between the tips of adjacent convex portions ｍ１ is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses ｍ２ is on the order of 100 nm or less, The maximum height difference H between adjacent convex and concave portions ｍｍａｘ is in the range of 20 nm to 100 nm, A roll mold, wherein an angle α (where 0°≦α≦90°) formed by the extension direction of the recesses with respect to the central axis of the roll mold is in the range of 30° to 85°.

2. An optical retardation film, an alignment layer and a liquid crystal layer; The alignment layer is made of a resin and has a seamless rectangular main surface, and the main surface has a first side L ｓ is 500 mm or more, and the second side W ｓ is 500 mm or more, where L ｓ >W ｓ and the main surface has a pattern of a plurality of parallel recesses / protrusions formed thereon; In the pattern, the horizontal distance P between the tips of adjacent convex portions ｓ１ is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses ｓ２ is on the order of 100 nm or less, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; The maximum height difference H between adjacent convex and concave portions ｓｍａｘ is in the range of 20 nm to 100 nm, an angle β (0°≦β≦90°) formed by the second side and the extension direction of the recessed portion is in the range of 30° to 85°;

3. The optical retardation film according to claim 2 , further comprising a substrate disposed on the side of the alignment layer opposite to the liquid crystal layer.

4. 4. The optical retardation film according to claim 2, wherein the alignment layer has a thickness in the range of 150 nm to 20 μm.

5. A method for producing an optical retardation film, comprising: (I) preparing a roll mold having a diameter of 200 mm or more and a total length of 500 mm or more; (II) polishing the outer peripheral surface of the roll mold to form a pattern of a plurality of parallel recesses / protrusions on the outer peripheral surface, In the pattern, the recesses have non-uniform widths and depths, and the protrusions have non-uniform widths and heights; Horizontal distance P between the tips of adjacent convex portions ｍ１ is on the order of 100 nm or less, and the horizontal distance P between the tips of adjacent recesses ｍ２ is on the order of 100 nm or less, The maximum height difference H between adjacent convex and concave portions ｍｍａｘ is in the range of 20 nm to 100 nm, The angle α (where 0°≦α≦90°) between the central axis of the roll mold and the extension direction of the recessed portion is in the range of 30° to 85°; (III) transferring the pattern to a first main surface of a resin film; (IV) providing a liquid crystal layer on the first main surface of the resin film; A method comprising:

6. The method according to claim 5, wherein in (I), the outer peripheral surface of the roll mold is polished so that the surface roughness Ra is 10 nm or less.

7. The (II) is (1) Placing a polishing pad on a first end face of the roll mold or on the outer peripheral surface in the vicinity thereof, and rotating the roll mold around a central axis, translating the roll mold or the polishing pad along a first direction parallel to the central axis to a second end face of the roll mold or in the vicinity thereof; (2) again placing the polishing pad on the first end face of the roll mold or on the outer peripheral surface in the vicinity thereof, and carrying out (1); and (3) Repeating (2) above 20 times or more 7. The method of claim 5 or 6, comprising:

8. 8. The method according to claim 7, wherein in (II), a slurry containing abrasive grains is supplied to the polishing pad, and the abrasive grains are not reused during (1) to (3).

9. The method of claim 8, wherein the abrasive grains have an average particle size in the range of 10 nm to 300 nm.

10. The above (III) is applying an energy curable composition to a substrate; applying energy to the energy curable composition while pressing the substrate coated with the energy curable composition against the roll mold to cure the energy curable composition; and 6. The method of claim 5, comprising:

11. The method according to claim 10 , wherein in (III), the substrate is supplied by a roll-to-roll method.

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