Method for manufacturing optical film and method for managing long optical film

Abstract

A method for manufacturing an optical film according to the present invention comprises: a step for preparing a first long optical film including a phase difference member; and a step for cutting the first long optical film in the longitudinal direction to obtain a plurality of second long optical films. The width of the first long-strip-shaped optical film is more than 10 times of the width of the optical film, and the width of the second long-strip-shaped optical film is more than 1.1 times and less than 3.0 times of the width of the optical film.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an optical film used in a display system such as goggles with a display, and a method for managing a long strip of optical film. Background Art

[0002] Image display devices, represented by liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays), are rapidly gaining popularity. In image display devices, optical components such as polarizing elements and phase shifting elements are generally used to achieve image display and improve image display performance (e.g., see Patent Document 1).

[0003] In recent years, new applications for image display devices have been developed. For example, goggles with displays (VR goggles) for realizing virtual reality (VR) have begun to be commercialized. As VR goggles are being studied for their use in various scenarios, they are increasingly being sought after for their high resolution.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-103286 Summary of the Invention

[0007] Problems solved by the invention

[0008] A main object of the present invention is to provide an optical member suitable for manufacturing a display system such as goggles with a high-definition display.

[0009] Solutions to Problems

[0010] [1] The manufacturing method of the optical film sheet according to an embodiment of the present invention includes: a process of preparing a first long strip optical film including a phase difference component, and a process of slitting the first long strip optical film along the length direction to obtain a plurality of second long strip optical films, wherein the width of the first long strip optical film is more than 10 times the width of the optical film sheet, and the width of the second long strip optical film is more than 1.1 times and less than 3.0 times the width of the optical film sheet.

[0011] [2] In the above [1], the manufacturing method may further include:

[0012] a step of continuously punching out the optical film sheet while conveying the second long optical film in a longitudinal direction.

[0013] [3] In the above [1] or [2], in the second long optical film, the deviation of the in-plane phase difference in the longitudinal direction may be 1.5 nm or less.

[0014] [4] In any one of the above [1] to [3], the manufacturing method may further include: a step of classifying the plurality of second long strip optical films into two or more groups based on in-plane phase difference.

[0015] [5] In the above [4], the classification step may include classifying the plurality of second long strip optical films into two or more groups according to the width of each given in-plane phase difference.

[0016] [6] In the above [4] or [5], the in-plane phase difference may be measured before and / or after the slit is formed.

[0017] [7] In any one of the above [4] to [6], the in-plane phase difference can be measured at two or more locations at the front end of the second long strip of optical film.

[0018] [8] In the above [7], the in-plane phase difference may be measured at two or more locations at the end of the second long optical film.

[0019] [9] In any one of the above [1] to [8], the length of the first long strip optical film may be greater than 100 m and less than 2000 m.

[0020]

[10] In any one of the above [1] to [9], the process of preparing the above-mentioned first long strip optical film may include: selecting a long strip optical film with a deviation of the in-plane phase difference in the width direction of less than 5nm and a deviation of the in-plane phase difference in the length direction of less than 1.5nm as the first long strip optical film.

[0021]

[11] The method for managing a long strip optical film according to an embodiment of the present invention includes: a process of preparing a first long strip optical film including a phase difference component, a process of slitting the first long strip optical film along the length direction to obtain a plurality of second long strip optical films, and a process of classifying the plurality of second long strip optical films into two or more groups based on the in-plane phase difference.

[0022]

[12] In the above

[11] , the classification step may include: classifying the plurality of second long strip optical films into two or more groups according to the width of each given in-plane phase difference.

[0023] Effects of the Invention

[0024] According to the method for manufacturing an optical film according to an embodiment of the present invention, an optical film with small in-plane phase difference deviation can be obtained. By using such an optical film, a display system such as goggles with a high-definition display can be suitably manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [ Figure 1 ] is a schematic diagram showing a brief structure of a display system to which the optical film obtained by the manufacturing method of the optical film according to the embodiment of the present invention can be applied.

[0026] [ Figure 2 ] Figure 2 (a) and 2(b) are schematic cross-sectional views illustrating an example of the structure of the first long optical film.

[0027] [ Figure 3 ] is a schematic diagram illustrating an example of step II of the method for manufacturing an optical film sheet according to an embodiment of the present invention.

[0028] [ Figure 4 ] is a schematic diagram illustrating an example of step III of the method for manufacturing an optical film sheet according to an embodiment of the present invention.

[0029] [ Figure 5 ] Figure 5 (a) is a schematic diagram illustrating an example of step IV of the method for manufacturing an optical film sheet according to an embodiment of the present invention. Figure 5 (b) Observation from above Figure 5 (a) The schematic diagram obtained.

[0030] Explanation of symbols

[0031] 2 Display System

[0032] 4 Lens section

[0033] 12 display components

[0034] 14 Reflective polarization component

[0035] 16. First lens unit

[0036] 18 Half Mirror

[0037] 20 first phase difference member

[0038] 22 second phase difference member

[0039] 22a Second λ / 4 member

[0040] 22b positive C plate

[0041] 24 Second lens unit

[0042] 30 The first long strip optical film (mother roll)

[0043] 40 Second long strip optical film (sub-roll) DETAILED DESCRIPTION

[0044] The following describes embodiments of the present invention with reference to the accompanying drawings, but the present invention is not limited to these embodiments. Furthermore, for greater clarity, the drawings sometimes schematically illustrate the width, thickness, shape, etc. of various components, as compared to the embodiments. However, this is merely an example and does not limit the interpretation of the present invention. In this specification, "elongated" refers to an elongated shape that is sufficiently long relative to its width, including, for example, an elongated shape that is at least 10 times, and preferably at least 20 times, its width.

[0045] (Definition of Terms and Symbols)

[0046] The definitions of terms and symbols in this specification are as follows.

[0047] (1) Refractive index (nx, ny, nz)

[0048] "nx" is the refractive index in the direction where the refractive index in the plane reaches a maximum (ie, the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), and "nz" is the refractive index in the thickness direction.

[0049] (2) In-plane retardation (Re)

[0050] "Re(λ)" is the in-plane retardation measured at 23°C using light of a wavelength of λ nm. For example, "Re(550)" is the in-plane retardation measured at 23°C using light of a wavelength of 550 nm. When the thickness of a layer (film) is d (nm), Re(λ) can be calculated using the formula: Re(λ) = (nx - ny) × d.

[0051] (3) Retardation in the thickness direction (Rth)

[0052] "Rth(λ)" is the retardation in the thickness direction measured at 23°C using light with a wavelength of λ nm. For example, "Rth(550)" is the retardation in the thickness direction measured at 23°C using light with a wavelength of 550 nm. When the thickness of a layer (film) is d (nm), Rth(λ) can be calculated using the formula: Rth(λ) = (nx - nz) × d.

[0053] (4) Nz coefficient

[0054] The Nz coefficient can be calculated by Nz=Rth / Re.

[0055] (5) Angle

[0056] In this specification, when referring to an angle, unless otherwise specified, the angle includes both clockwise and counterclockwise angles relative to a reference direction. Thus, for example, "45°" means ±45°. Furthermore, in this specification, "substantially parallel" includes angles within the range of 0°±10°, for example, 0°±5°, preferably 0°±3°, and more preferably 0°±1°. "Substantially orthogonal" includes angles within the range of 90°±10°, for example, 90°±5°, preferably 90°±3°, and more preferably 90°±1°.

[0057] A. Display system overview

[0058] Figure 1 FIG. 1 is a schematic diagram showing a schematic structure of a display system to which the optical film obtained by the method for manufacturing the optical film according to the embodiment of the present invention can be applied. Figure 1 , the configuration and shape of each component of the display system 2 are schematically shown. The display system 2 includes a display element 12, a reflective polarizing element 14, a first lens unit 16, a half mirror 18, a first phase difference element 20, a second phase difference element 22, and a second lens unit 24. The reflective polarizing element 14 is arranged on the display surface 12a side of the display element 12, that is, in front, and can reflect light emitted from the display element 12. The first lens unit 16 is arranged on the optical path between the display element 12 and the reflective polarizing element 14, and the half mirror 18 is arranged between the display element 12 and the first lens unit 16. The first phase difference element 20 is arranged on the optical path between the display element 12 and the half mirror 18, and the second phase difference element 22 is arranged on the optical path between the half mirror 18 and the reflective polarizing element 14. Although not shown in the figure, from the perspective of improving visual recognition, an absorptive polarizing element can be arranged between the reflective polarizing element 14 and the second lens unit 24. In this case, the reflection axis of the reflective polarization element 14 and the absorption axis of the absorptive polarization element may be arranged substantially parallel to each other, and the transmission axis of the reflective polarization element 14 and the transmission axis of the absorptive polarization element may be arranged substantially parallel to each other.

[0059] Components arranged in front of the half mirror (in the illustrated example, the half mirror 18 , the first lens unit 16 , the second phase difference member 22 , the reflective polarization member 14 , and the second lens unit 24 ) are sometimes collectively referred to as a lens unit (lens unit 4 ).

[0060] The display element 12 is, for example, a liquid crystal display or an organic EL display, and has a display surface 12a for displaying images. Light emitted from the display surface 12a passes through a polarizing member (typically a polarizing film) that may be included in the display element 12 and then is emitted as first linearly polarized light.

[0061] The first phase difference member 20 includes a first λ / 4 element capable of converting the first linearly polarized light incident on the first phase difference member 20 into the first circularly polarized light. If the first phase difference member does not include any other member other than the first λ / 4 element, the first phase difference member may correspond to the first λ / 4 element. The first phase difference member 20 may be integrally provided with the display element 12.

[0062] The half mirror 18 transmits light emitted from the display element 12 and reflects light reflected by the reflective polarization element 14 toward the reflective polarization element 14 . The half mirror 18 is integrally provided with the first lens portion 16 .

[0063] The second phase difference member 22 includes a second λ / 4 element that allows light reflected by the reflective polarization member 14 and the half mirror 18 to pass through the reflective polarization member 14. If the second phase difference member does not include any other components, the second phase difference member may correspond to the second λ / 4 element. The second phase difference member 22 may be integrally provided with the first lens portion 16.

[0064] The first circularly polarized light emitted from the first λ / 4 element included in the first phase difference element 20 passes through the half mirror 18 and the first lens unit 16, and is converted into second linearly polarized light by the second λ / 4 element included in the second phase difference element 22. The second linearly polarized light emitted from the second λ / 4 element does not pass through the reflective polarization element 14 but is reflected toward the half mirror 18. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarization element 14 is the same as the reflection axis of the reflective polarization element 14. Therefore, the second linearly polarized light incident on the reflective polarization element 14 is reflected by the reflective polarization element 14.

[0065] The second linearly polarized light reflected by the reflective polarizing element 14 is converted into second circularly polarized light by the second λ / 4 element included in the second phase difference element 22. The second circularly polarized light emitted from the second λ / 4 element passes through the first lens unit 16 and is reflected by the half mirror 18. The second circularly polarized light reflected by the half mirror 18 passes through the first lens unit 16 and is converted into third linearly polarized light by the second λ / 4 element included in the second phase difference element 22. The third linearly polarized light is transmitted through the reflective polarizing element 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing element 14 is the same as the transmission axis of the reflective polarizing element 14. Therefore, the third linearly polarized light incident on the reflective polarizing element 14 is transmitted through the reflective polarizing element 14.

[0066] The light transmitted through the reflective polarizing element 14 passes through the second lens portion 24 and then enters the user's eye 26 .

[0067] For example, the absorption axis of the polarization element included in the display element 12 and the reflection axis of the reflective polarization element 14 can be arranged approximately parallel to each other or approximately orthogonal to each other. The angle formed by the absorption axis of the polarization element included in the display element 12 and the slow axis of the first λ / 4 element included in the first phase difference element 20 is, for example, 40° to 50°, 42° to 48°, or approximately 45°. The angle formed by the absorption axis of the polarization element included in the display element 12 and the slow axis of the second λ / 4 element included in the second phase difference element 22 is, for example, 40° to 50°, 42° to 48°, or approximately 45°. The first λ / 4 element and the second λ / 4 element are preferably arranged so that their slow axis directions are approximately parallel to each other or approximately orthogonal to each other.

[0068] The in-plane retardation Re(550) of the first λ / 4 element is, for example, 100 nm to 190 nm, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 element preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. The Re(450) / Re(550) ratio of the first λ / 4 element is, for example, 0.75 or greater and less than 1, or 0.8 or greater and 0.95 or less.

[0069] The in-plane retardation Re(550) of the second λ / 4 element is, for example, 100 nm to 190 nm, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 element preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. The Re(450) / Re(550) ratio of the second λ / 4 element is, for example, 0.75 or greater and less than 1, or 0.8 or greater and 0.95 or less.

[0070] As described above, in the display system 2, linearly polarized light emitted forward from the display surface 12a of the display element 12 sequentially passes through the first and second λ / 4 elements, then reflects off the reflective polarizing element 14 and re-reflects off the half mirror 18. It then passes through the second λ / 4 element twice, passing through the reflective polarizing element 14 and then exiting forward, where it is visually perceived by the viewer. Therefore, if the in-plane retardation of the first or second λ / 4 element is significantly offset, polarization may be disrupted, causing light leakage, or light that should be reflected may be mixed with light that should be perceived, resulting in a blurred image. To prevent this problem and achieve high-definition image display, the in-plane retardation accuracy of the first and second λ / 4 elements is desired. Furthermore, the in-plane retardation of the first and second λ / 4 elements is desired to be highly consistent.

[0071] B. Manufacturing Method of Optical Film

[0072] B-1. Overview of Optical Film Manufacturing Method

[0073] The manufacturing method of the optical film sheet according to the embodiment of the present invention includes: step I of preparing a first long strip optical film including a phase difference component, and step II of slitting the above-mentioned first long strip optical film along the length direction to obtain a plurality of second long strip optical films, wherein the width of the above-mentioned first long strip optical film is more than 10 times the width of the above-mentioned optical film sheet, and the width of the above-mentioned second long strip optical film is more than 1.1 times and less than 3.0 times the width of the above-mentioned optical film sheet.

[0074] In one embodiment, the method for manufacturing the optical film further includes step III of classifying the plurality of second long optical films into two or more groups based on in-plane phase difference.

[0075] In one embodiment, the method for manufacturing the optical film sheet further includes step IV of continuously punching the optical film sheet while conveying the second long optical film in a longitudinal direction.

[0076] Wide-width phase difference components usually have a deviation in the in-plane phase difference in the width direction. Therefore, for the optical film punched out at the end portion in the width direction and the optical film punched out in the center portion in the width direction, there is a case where the difference in in-plane phase difference is large. If an optical film with such a deviation in in-plane phase difference is applied to the manufacture of the display system described in item A, it is difficult to stably manufacture a high-precision display system. In contrast, according to the method for manufacturing an optical film according to an embodiment of the present invention, a wide-width long-strip optical film is slit along the length direction to form a narrow-width long-strip optical film. Thus, the long-strip optical film with reduced deviation in the in-plane phase difference in the width direction can be provided to the punching process. As a result, an optical film with suppressed deviation in the in-plane phase difference can be effectively obtained.

[0077] The optical film obtained by the manufacturing method of the embodiment of the present invention can have any appropriate shape. In one embodiment, the optical film is substantially circular. In this specification, the substantially circular shape includes a circle or an ellipse, and further includes a shape that is visually recognized as close to a circle or an ellipse. For example, the substantially circular shape can be a circle, an ellipse, or a shape with concave and convex shapes formed around them, or a shape with a portion of their periphery formed by straight lines.

[0078] The ratio of the major diameter to the minor diameter of the optical film (minor diameter / major diameter) is, for example, greater than 0.8 and less than 1, and can also be, for example, greater than 0.9 and less than 1. The major diameter of the optical film is, for example, greater than 40 mm and less than 60 mm, and can also be, for example, greater than 42 mm and less than 50 mm. It should be noted that the major diameter and minor diameter of the optical film represent the maximum and minimum values ​​of the interval between parallel lines of the optical film, respectively.

[0079] Below, refer to Figures 2 to 5 Each step will be described in detail.

[0080] B-2. Process I

[0081] In step I, a first long optical film including a phase difference member is prepared. This phase difference member is, for example, the second phase difference member 22 in the display system 2 described in section A, including a λ / 4 member as the second λ / 4 member. The first long optical film can be wound into a roll. Hereinafter, the first long optical film wound into a roll may be referred to as a "mother roll."

[0082] In one embodiment, the deviation of the in-plane phase difference (e.g., Re (590)) in the length direction of the first long strip optical film is, for example, less than 3 nm, preferably less than 1.5 nm. In addition, the deviation of the in-plane phase difference in the width direction of the first long strip optical film is, for example, less than 5 nm, preferably less than 3 nm, for example, greater than 0.5 nm. By preparing an optical film sheet from a first long strip optical film having a small deviation in in-plane phase difference through the preparation of a second long strip optical film, the effect of the present invention can be suitably obtained. The deviation of the in-plane phase difference in the length direction can be measured at any position in the width direction of the long strip optical film (e.g., the center in the width direction) along a given length (e.g., about 50 m or more, or the entire length) along the length direction, and the in-plane phase difference can be obtained as the difference between its maximum and minimum values. In addition, the deviation of the in-plane phase difference in the width direction can be determined by measuring the in-plane phase difference at multiple locations at given intervals (for example, intervals of about 30 mm to about 350 mm) along the width direction at any position in the longitudinal direction of the long optical film and calculating it as the difference between the maximum and minimum values.

[0083] Figure 2 (a) and 2(b) are schematic cross-sectional views illustrating an example of the structure of the first long optical film. Figure 2 The first long optical film 30a shown in (a) includes an adhesive layer 32, a λ / 4 member 22a, and a protective member 34 in this order. Figure 2 In the optical film 30a having the structure shown in (a), the phase difference member (the second phase difference member in the display system 2) 22 is composed of a λ / 4 member (the second λ / 4 member in the display system 2) 22a. Figure 2 The first long optical film 30b shown in (b) includes an adhesive layer 32, a λ / 4 member 22a, a member having a refractive index characteristic showing the relationship nz>nx=ny (so-called positive C plate) 22b, and a protective member 34 in this order. Figure 2 (b) The optical film 30b shown in the structure is a phase difference member (the second phase difference member in the display system 2) 22 including a λ / 4 member (the second λ / 4 member in the display system 2) 22a and a positive C plate 22b. In other words, the phase difference member 22 has a stacked structure of the λ / 4 member 22a and the positive C plate 22b. Figure 2 Unlike the configuration shown in (b), in the phase difference member 22, the λ / 4 member 22a can also be positioned on the protective member 34 side relative to the positive C plate 22b. The surfaces of the adhesive layer 32 of the first long optical films 30a and 30b shown in the figure are protected by a release liner 36. The resulting optical film sheet formed from the long optical films 30a and 30b can be bonded to the first lens portion 16 via the adhesive layer 32 during the manufacture of the display system 2.

[0084] The width of the first long strip optical film is more than 10 times the width of the optical film sheet to be manufactured, preferably more than 15 times and less than 25 times, more preferably more than 15 times and less than 20 times. In this specification, the width of the optical film sheet can be the punching width when the optical film sheet is punched out from the second long strip optical film (in Figure 5 In one embodiment, the width of the first long strip optical film is, for example, 500 mm to 1500 mm, or, for example, 900 mm to 1200 mm.

[0085] The length of the first long optical film is, for example, greater than or equal to 100 m and less than or equal to 2000 m, and for example, greater than or equal to 500 m and less than or equal to 1000 m.

[0086] B-2-1. λ / 4 member

[0087] As described in Section A for the second λ / 4 member, the in-plane retardation Re(550) of the λ / 4 member 22a is, for example, 100 nm to 190 nm, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The λ / 4 member preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. The Re(450) / Re(550) ratio of the λ / 4 member is, for example, 0.75 or greater and less than 1, or 0.8 or greater and 0.95 or less.

[0088] The refractive index characteristics of the λ / 4 member preferably exhibit the relationship nx > ny ≥ nz. Here, "ny = nz" encompasses not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny < nz may be acceptable without impairing the effects of the present invention. The Nz coefficient of the λ / 4 member is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0089] In one embodiment, the λ / 4 member is a stretched film of a resin film, for example, a stretched film obtained by stretching a long resin film in the width direction.

[0090] Examples of the resin contained in the resin film include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. These resins can be used alone or in combination. Examples of the combination method include blending and copolymerization. When the λ / 4 component exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes referred to as a polycarbonate resin) can be suitably used.

[0091] As the above-mentioned polycarbonate resin, any appropriate polycarbonate resin can be used. For example, the polycarbonate resin contains structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from at least one dihydroxy compound selected from alicyclic diols, alicyclic dimethanols, di-, tri- or polyethylene glycols, and alkylene glycols or spirodiols. Preferably, the polycarbonate resin contains structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, structural units derived from alicyclic dimethanols and / or structural units derived from di-, tri- or polyethylene glycols; more preferably, it contains structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di-, tri- or polyethylene glycols. The polycarbonate resin may also contain structural units derived from other dihydroxy compounds as needed. It should be noted that details of polycarbonate resins that can be suitably used for λ / 4 components and methods for forming λ / 4 components are described, for example, in Japanese Patent Application Publication No. 2014-10291, Japanese Patent Application Publication No. 2014-26266, Japanese Patent Application Publication No. 2015-212816, Japanese Patent Application Publication No. 2015-212817, and Japanese Patent Application Publication No. 2015-212818, and the descriptions of these publications are incorporated herein by reference.

[0092] The thickness of the λ / 4 member as a stretched film of the resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, and more preferably 20 μm to 60 μm.

[0093] In one embodiment, the λ / 4 component is an orientation fixing layer of a liquid crystal compound. The orientation fixing layer of a liquid crystal compound is a layer in which the liquid crystal compound is oriented in a given direction within the layer and its orientation state is fixed. It should be noted that the "orientation fixing layer" is a concept that includes an orientation solidification layer obtained by solidifying a liquid crystal monomer as described later. In the λ / 4 component, representatively, the rod-shaped liquid crystal compound is oriented in a state of being arranged along the slow axis direction of the λ / 4 component (parallel orientation (homogeneous alignment)). Examples of the rod-shaped liquid crystal compound include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably capable of polymerization. If the liquid crystal compound is capable of polymerization, the orientation state of the liquid crystal compound can be fixed by polymerizing after the liquid crystal compound is oriented.

[0094] The orientation fixing layer (liquid crystal orientation fixing layer) of the above-mentioned liquid crystal compound can be formed by the following method: an orientation treatment is applied to the surface of a given substrate, a coating liquid containing a liquid crystal compound is applied to the surface, and the liquid crystal compound is oriented along the direction corresponding to the above-mentioned orientation treatment to fix the orientation state. As an orientation treatment, any appropriate orientation treatment can be adopted. Specifically, mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment can be mentioned. As a specific example of a mechanical orientation treatment, friction treatment and stretching treatment can be mentioned. As a specific example of a physical orientation treatment, magnetic field orientation treatment and electric field orientation treatment can be mentioned. As a specific example of a chemical orientation treatment, inclined evaporation method and optical orientation treatment can be mentioned. The processing conditions of various orientation treatments can adopt any appropriate conditions according to the purpose.

[0095] The liquid crystal compound can be aligned by treating it at a temperature that exhibits a liquid crystal phase, depending on the type of the liquid crystal compound. By treating it at this temperature, the liquid crystal compound assumes a liquid crystal state and is aligned in the alignment treatment direction on the substrate surface.

[0096] In one embodiment, the alignment state is fixed by cooling the aligned liquid crystal compound as described above. If the liquid crystal compound is polymerizable or cross-linkable, the alignment state can be fixed by subjecting the aligned liquid crystal compound to a polymerization treatment or a cross-linking treatment as described above.

[0097] As the liquid crystal compound, any appropriate liquid crystal polymer and / or liquid crystal monomer can be used. The liquid crystal polymer and liquid crystal monomer can be used alone or in combination. Specific examples of liquid crystal compounds and methods for preparing liquid crystal alignment fixing layers are described, for example, in Japanese Patent Application Publication No. 2006-163343, Japanese Patent Application Publication No. 2006-178389, and International Publication No. 2018 / 123551. The contents of these publications are incorporated herein by reference.

[0098] The thickness of the λ / 4 member composed of the liquid crystal alignment solidified layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and further preferably 1 μm to 4 μm.

[0099] B-2-2. Positive C-plate

[0100] The thickness-direction retardation Rth(550) of the positive C plate 22b is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, even more preferably -90 nm to -200 nm, and particularly preferably -100 nm to -180 nm. Here, "nx = ny" encompasses not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. The in-plane retardation Re(550) of the positive C plate is, for example, less than 10 nm.

[0101] The positive C plate can be formed from any suitable material, but the positive C plate is preferably composed of a film containing a liquid crystal material fixed in a homeotropic orientation. The liquid crystal material (liquid crystal compound) capable of homeotropic orientation can be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and methods for forming positive C plates include the liquid crystal compounds and methods for forming the phase difference layer described in

[0020] to

[0028] of Japanese Patent Application Laid-Open No. 2002-333642. In this case, the thickness of the positive C plate is preferably 0.5 μm to 5 μm.

[0102] B-2-3. Protective components

[0103] Typically, the protective member 34 includes a substrate. The substrate can be formed of any appropriate film. Examples of materials constituting the main component of the film constituting the substrate include cellulose resins such as triacetyl cellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, cycloolefins such as polynorbornene, polyolefins, (meth)acrylic acids, acetates, and the like. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 35 μm.

[0104] The protective member preferably comprises a substrate and a surface treatment layer formed on the substrate. The protective member having the surface treatment layer can be arranged so that the surface treatment layer is located on the front side. The surface treatment layer can have any appropriate function. For example, from the perspective of improving visual recognition, the surface treatment layer preferably has an anti-reflection function. In addition, the surface treatment layer may include a hard coating layer. The thickness of the surface treatment layer is preferably 1 μm to 20 μm, more preferably 2 μm to 15 μm, and even more preferably 3 μm to 10 μm.

[0105] When the protective member includes a substrate and a surface treatment layer formed on the substrate, a second protective member may be further provided to protect the surface treatment layer. As the second protective member, a film similar to that used for the substrate may be used.

[0106] B-2-4. Adhesive layer

[0107] The adhesive constituting the adhesive layer 32 typically contains a (meth)acrylic polymer, a urethane polymer, a silicone polymer, or a rubber polymer as a base polymer. The adhesive is preferably a (meth)acrylic adhesive containing a (meth)acrylic polymer as a main component. The thickness of the adhesive layer is, for example, 12 μm or greater, preferably 15 μm or greater, and for example, 100 μm or less, preferably 80 μm or less.

[0108] B-2-5. Release liner

[0109] The release liner 36 typically includes a substrate and a release-treated layer (e.g., a silicone-treated layer) provided on the surface of the substrate facing the adhesive layer 32. The substrate is formed of, for example, a resin such as a polyolefin resin, a polyester resin, a (meth)acrylic resin, a polyamide resin, a polyimide resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a cellulose resin, a polystyrene resin, or a polycarbonate resin.

[0110] B-2-6. Manufacturing method

[0111] The first elongated optical film can be produced by any suitable method. For example, the first elongated optical film can be obtained by a manufacturing method that includes forming the aforementioned components into an elongated strip and, as needed, sequentially laminating the components via an adhesive layer, and then winding the components into a roll as needed. The lamination is preferably performed on a roll-to-roll basis. "Roll-to-roll" here means laminating the rolls of film while they are transported so that their lengths are aligned. The adhesive layer can be an adhesive layer or a bonding agent layer.

[0112] In one embodiment, a portion of the long optical film produced as described above whose deviation of the in-plane phase difference in the length direction and / or width direction is within the above-given range (specifically, the deviation of the in-plane phase difference in the width direction is, for example, less than 5 nm, and the deviation of the in-plane phase difference in the length direction is, for example, less than 3 nm, and also, for example, less than 1.5 nm) can be selected and used as the first long optical film.

[0113] B-3. ​​Process II

[0114] In step II, Figure 3As shown, the first long strip of optical film 30 prepared in step I is slit along its length to obtain a plurality of second long strips of optical film 40. Slitting can be performed not only along its length but also along its width. This allows the production of a plurality of second long strips of optical film having a predetermined width and length.

[0115] In one embodiment, the second long optical film 40 is wound into a roll and then supplied to a subsequent process (hereinafter, the rolled second long optical film may be referred to as a "sub-roll").

[0116] The width of the second long strip optical film is greater than the width of the optical film piece to be manufactured, for example, greater than 1.1 times, preferably greater than 1.2 times, for example less than 3.0 times, preferably less than 2.0 times, more preferably less than 1.5 times the width of the optical film piece to be manufactured. The deviation of the in-plane phase difference (for example, Re(590)) in the width direction of the second long strip optical film having the above width can be, for example, less than 3 nm, preferably less than 1.5 nm. In addition, the deviation of the in-plane phase difference (for example, Re(590)) in the length direction of the second long strip optical film can be, for example, less than 3 nm, preferably less than 1.5 nm. According to such a second long strip optical film, the deviation of the in-plane phase difference of the optical film piece obtained from a second long strip optical film can be very small.

[0117] In one embodiment, the width of the second long optical film is, for example, 40 mm to 200 mm, for example, 45 mm to 150 mm, or 50 mm to 120 mm.

[0118] In one embodiment, the number of divisions of the film based on the slits along the length direction (referring to the number of divisions of the first long strip optical film in the width direction) is, for example, 6 or more, preferably 10 or more and 25 or less, and preferably 15 or more and 20 or less.

[0119] The length of the second long optical film is, for example, 50 m to 1000 m, 50 m to 300 m, or 100 m to 150 m.

[0120] B-4. Step III

[0121] In step III, if Figure 4As shown, the plurality of second long strip optical films 40 are classified into two or more groups based on the in-plane retardation (substantially the in-plane retardation of a λ / 4 member). Specifically, before step III, the in-plane retardation (e.g., Re(590)) of each of the plurality of second long strip optical films is measured, and based on the measured in-plane retardation, the plurality of second long strip optical films are classified into N groups in such a manner that the deviation of the in-plane retardation within each group is smaller than the deviation of the in-plane retardation of the entire group. In the example shown, the plurality of second long strip optical films 40 are classified into two groups, Group A and Group B, but N can be an integer greater than 2, for example, greater than 3. From the perspective of appropriately obtaining the effects of the present invention, it is preferably greater than 2 and less than 4, and more preferably 2 or 3.

[0122] The in-plane phase difference is measured, for example, at two or more locations (e.g., two locations) at the front end and / or the end of the second long strip optical film after slitting. For a long strip optical film with a small deviation in the in-plane phase difference in the length direction, even if it has a length of more than 50 m, its overall in-plane phase difference can be roughly grasped by measuring at the front end and / or the end. In one embodiment, as in Figure 4 As indicated by the "×" mark in the second long strip optical film 40 in the upper left section, the in-plane phase difference is measured at two or more locations in the width direction of the front end of the film (for example, at two or more locations within a distance of 500 mm from the front end (for example, multiple locations separated by a given interval in the width direction)). If necessary, it can also be measured at two or more locations in the width direction of the end (for example, at two or more locations within a distance of 500 mm from the end (for example, multiple locations separated by a given interval in the width direction)). The average value of these measurements can be used as the in-plane phase difference of the second long strip optical film.

[0123] Alternatively, the in-plane retardation can be measured on the first long strip of optical film before slitting. In this case, the first long strip of optical film before slitting can be divided along the lines intended for slitting. The in-plane retardation of the portion corresponding to the leading end and / or trailing end of the divided portion can be measured in the same manner as described above, and this value can be used as the in-plane retardation of the second long strip of optical film corresponding to the divided portion obtained after slitting.

[0124] The above classification can be performed, for example, by classifying the plurality of second elongated optical films according to a given in-plane retardation width based on the in-plane retardation measured in the above manner. The classification width of the in-plane retardation of each group can be, for example, 2 nm or less, preferably 1 nm or more and 1.5 nm or less, and more preferably 1 nm or more and 1.3 nm or less.

[0125] In one embodiment, the classification can be performed as follows: classification is performed according to the width of a given in-plane phase difference starting from a preset reference value. As a specific example, when Re(590) of 146 nm is used as the reference value and classification is performed with a classification width of 2 nm (classification width of ±1 nm), the classification can be sequentially divided into, for example, a group having Re(590) of 145 nm or more and less than 147 nm, a group having Re(590) of 143 nm or more and less than 145 nm, a group having Re(590) of 147 nm or more and less than 149 nm, a group having Re(590) of 141 nm or more and less than 143 nm, a group having Re(590) of 149 nm or more and less than 151 nm, and the like.

[0126] In another embodiment, the classification can be performed as follows: the classification is performed sequentially according to a given in-plane retardation width, starting from the largest or smallest measured in-plane retardation value. The classification width of the in-plane retardation (e.g., Re(590)) can be, for example, 2 nm or less, preferably 1 nm or more and 1.5 nm or less, and more preferably 1 nm or more and 1.3 nm or less.

[0127] The variation in the in-plane retardation between the second long optical films in each group classified as described above becomes smaller than the variation in the in-plane retardation between all the second long optical films before classification.

[0128] B-5. Step IV

[0129] In step IV, if Figure 5 As shown in (a), the second long strip of optical film 40 is continuously punched out into optical film sheets 50 while being transported in its longitudinal direction. For example, the second long strip of optical film can be laminated to a surface protective film in a roll-to-roll manner before being punched out into optical film sheets. The punched out optical film sheets undergo quality inspection as required and are then used to assemble the display system 2.

[0130] Figure 5 (b) Observation from above Figure 5(a) is a schematic diagram obtained. As described above, the width X2 of the second long strip optical film 40 is, for example, 1.1 to 3.0 times, preferably 1.2 to 2.0 times, and more preferably 1.2 to 1.5 times the punched width X1 of the optical film sheet 50. Therefore, representatively, the number of optical film sheets punched out in the width direction of the second long strip optical film is one or two, preferably one. By making a wide mother roll, cutting along the length direction to make narrow sub-rolls, and punching out one or two, preferably only one, optical film sheets from each sub-roll along the width direction, an optical film sheet with reduced deviation in the in-plane phase difference can be obtained. In addition, by pre-classifying sub-rolls with similar in-plane phase differences into the same group, the optical film sheets obtained from the sub-rolls belonging to the same group have a characteristic of high uniformity in the in-plane phase difference.

[0131] The optical film obtained by the manufacturing method according to the embodiment of the present invention has a highly uniform in-plane retardation, and therefore, by being used as a component constituting the second retardation member 22, it can contribute to the efficient production of the high-definition display system 2. Furthermore, there is the advantage of easily matching the in-plane retardation of the first and second λ / 4 members, which is important for high definition.

[0132] C. Management of long strip optical films

[0133] The management method of the long strip optical film of the embodiment of the present invention includes: process A of preparing a first long strip optical film including a phase difference component; process B of cutting the above-mentioned first long strip optical film along the length direction to obtain a plurality of second long strip optical films; and process C of classifying the above-mentioned plurality of second long strip optical films into two or more groups based on the in-plane phase difference.

[0134] The same explanations as those for step I, step II, and step III described in section B can be applied to step A, step B, and step C, respectively.

[0135] According to the above management method, after producing a wide, long strip of optical film, slits are then made along its length to divide it into multiple narrow strips. Furthermore, by grouping these multiple narrow strips of optical film based on their in-plane retardation, a set of long strips of optical film with reduced variation in in-plane retardation in the width direction and similar in-plane retardation can be obtained. Therefore, by managing the narrow strips of optical film in groups and subjecting them to the subsequent punching process, optical film sheets with a desired in-plane retardation and minimal variation in in-plane retardation can be obtained in a concentrated manner.

[0136] Example

[0137] Hereinafter, the present invention will be specifically described with reference to the examples, but the present invention is not limited to these examples at all. It should be noted that the test and evaluation methods in the examples etc. are as follows. Wherein, when recorded as "parts", as long as there is no special record, then "parts by weight" is represented; when recorded as "%", as long as there is no special record, then "% by weight" is represented.

[0138] (1) Thickness

[0139] Thicknesses of 10 μm or less were measured using a scanning electron microscope (JSM-7100F, manufactured by JEOL Ltd.), and thicknesses exceeding 10 μm were measured using a digital micrometer (KC-351C, manufactured by Anritsu Co., Ltd.).

[0140] (2) In-plane phase difference Re(λ)

[0141] The in-plane retardation at 23±2° C. and 65±15% RH was measured using KOBRA (manufactured by Oji Scientific Instruments Co., Ltd.).

[0142] [Fabrication of λ / 4 Member A]

[0143] In a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled at 100°C, 29.60 parts by weight (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by weight (0.200 mol) of isosorbide (ISB), 42.28 parts by weight (0.139 mol) of spiroglycol (SPG), 63.77 parts by weight (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 mol of calcium acetate monohydrate as a catalyst were charged. -2 Parts by weight (6.78×10 -5mol). After the reactor was purged with nitrogen and heated with a heat medium, stirring began when the internal temperature reached 100°C. The internal temperature reached 220°C 40 minutes after the start of the temperature increase. While maintaining this temperature, the pressure was reduced until it reached 13.3 kPa 90 minutes after reaching 220°C. Phenol vapor, a by-product of the polymerization reaction, was introduced into a 100°C reflux condenser. A small amount of monomer components contained in the phenol vapor were returned to the reactor, while uncondensed phenol vapor was recovered by introducing it into a 45°C condenser. Nitrogen was introduced into the first reactor to temporarily restore the pressure to atmospheric pressure, and the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, the temperature and pressure in the second reactor were increased and reduced, reaching an internal temperature of 240°C and a pressure of 0.2 kPa over 50 minutes. Polymerization was then continued until the desired stirring power was achieved. When the predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, and the produced polyester carbonate resin was extruded into water. The strands were cut to obtain pellets.

[0144] The resulting polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours and then formed into a 130 μm thick long-strip resin film using a film-forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a chilled roll (set temperature: 120-130°C), and a winder. The resulting long-strip resin film was stretched in the width direction at a stretching temperature of 140°C and a stretch ratio of 2.7 times, and then wound into a roll. This produced a 47 μm thick λ / 4 member A. The Re (590) of the center portion in the width direction of the λ / 4 member A was 147 nm.

[0145] [Production of positive C plate A]

[0146] A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (1) (where the numbers 65 and 35 represent the molar percentage of the monomer unit, and for convenience, the block polymer is expressed as having a weight-average molecular weight of 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (Paliocolor LC242 manufactured by BASF), and 5 parts by weight of a photopolymerization initiator (IRGACURE 907 manufactured by Chiba Specialty Chemicals) in 200 parts by weight of cyclopentanone. This coating solution was then applied to a PET substrate that had been subjected to a vertical alignment treatment using a wire bar coater, and then heated and dried at 80°C for 4 minutes to align the liquid crystal. The liquid crystal layer was cured by irradiating it with ultraviolet light, thereby forming a positive C plate having a thickness of 4 μm and an Rth(550) of -100 nm on the substrate.

[0147] [Chemical Formula 1]

[0148]

[0149] [Production of Master Roll]

[0150] The positive C plate A was bonded to the λ / 4 member A via an ultraviolet-curable adhesive (thickness 1 μm after curing), and the substrate was peeled off to obtain a phase difference member A having a structure of [λ / 4 member A / positive C plate A]. An acrylic adhesive (thickness 50 μm) and a release liner were bonded to the λ / 4 member A side surface of the phase difference member A. In addition, an acrylic resin film with a hard coat layer as a protective member was bonded to the positive C plate A side surface of the phase difference member A via an acrylic adhesive (thickness 23 μm), with the acrylic resin film side becoming the positive C plate A side. The above bonding was performed on a roll-to-roll basis.

[0151] As described above, a roll of optical film (mother roll) having a structure of [release liner / adhesive layer / λ / 4 member A / positive C plate A / protective member] was obtained. The mother roll had a length of 1000 m and a width of 1120 mm.

[0152] [Creation of sub-volume 1]

[0153] The optical film was continuously unwound from the mother roll, slit at predetermined intervals along the longitudinal direction, and wound into a roll to obtain a sub-roll 1 consisting of three rolls.

[0154] [Creation of sub-volume 2]

[0155] Sub-rolls 2 to 6 having various lengths and widths were obtained in the same manner as in sub-roll production 1 except that slits were made at different intervals in the longitudinal direction and / or the width direction.

[0156] [Evaluation of In-Plane Phase Difference Deviation]

[0157] For each roll and the parent roll included in sub-rolls 1 to 6, Re (590) was measured at multiple locations with an interval of about 60 mm in the width direction over the entire length, and the average value of the measured values ​​at each measured location was calculated. The difference between the maximum and minimum values ​​of the average values ​​obtained for each measured location was taken as the deviation of the in-plane phase difference in the width direction of the roll. The results are shown in Table 1. It should be noted that in the table, the deviation of the in-plane phase difference of sub-rolls 1 to 6 is the average value of the deviation of the in-plane phase difference in the width direction of each roll included in sub-rolls 1 to 6. In addition, the "number of divisions in the width direction" is the number of divisions in the width direction based on the slits along the length direction (the number of blocks after division). It should be noted that, in each roll and the parent roll included in sub-rolls 1 to 6, the deviation of the in-plane phase difference in the length direction of each measured location is less than 1.5 nm.

[0158]

[0159] As shown in Table 1, narrow-width long strips of optical film have smaller variations in in-plane retardation along the width direction than wide-width long strips of optical film. Long strips of optical film with small variations in in-plane retardation along the width direction (e.g., variations of 1.5 nm or less, 1.2 nm or less, or 1 nm or less) can be produced by slitting a wide-width long strip of optical film along its length. Furthermore, by continuously punching out such long strips of optical film with small variations in in-plane retardation along the width direction, optical film sheets with excellent in-plane retardation uniformity can be produced with high production efficiency.

[0160] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configuration shown in the above-described embodiment may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiment, a configuration that exhibits the same function and effect, or a configuration that achieves the same purpose.

[0161] Industrial Applicability

[0162] The method for producing an optical film according to an embodiment of the present invention can be suitably used for producing a display such as VR goggles, for example.

Claims

1. A method for manufacturing an optical film, comprising: A step of preparing a first long optical film including a phase difference member; and The first long strip optical film is cut along the length direction to obtain a plurality of second long strip optical films. The width of the first long strip optical film is more than 10 times the width of the optical film sheet. The width of the second long strip of optical film is greater than or equal to 1.1 times and less than or equal to 3.0 times the width of the optical film sheet.

2. The manufacturing method according to claim 1, further comprising: a step of continuously punching out the optical film sheet while conveying the second long optical film in the longitudinal direction.

3. The manufacturing method according to claim 1, wherein In the second long optical film, the deviation of the in-plane retardation in the longitudinal direction is 1.5 nm or less.

4. The manufacturing method according to claim 1, further comprising: A step of classifying the plurality of second long optical films into two or more groups based on in-plane phase difference.

5. The manufacturing method according to claim 4, wherein: The classifying step includes classifying the plurality of second long-length optical films into two or more groups according to the width of each predetermined in-plane phase difference.

6. The manufacturing method according to claim 4, wherein: The in-plane phase difference is measured before the slitting and / or after the slitting.

7. The manufacturing method according to claim 6, wherein: The in-plane retardation is measured at two or more locations on the front end of the second long optical film.

8. The manufacturing method according to claim 7, wherein: Furthermore, the in-plane retardation is measured at two or more locations at the end of the second long optical film.

9. The manufacturing method according to claim 1, wherein: The length of the first long strip of optical film is greater than or equal to 100 m and less than or equal to 2000 m.

10. The manufacturing method according to claim 1, wherein: The step of preparing the first long optical film includes selecting a long optical film having a deviation of in-plane retardation in the width direction of 5 nm or less and a deviation of in-plane retardation in the length direction of 1.5 nm or less as the first long optical film.

11. A method for managing a long strip of optical film, comprising: A step of preparing a first long optical film including a phase difference member; The process of cutting the first long strip optical film along the length direction to obtain a plurality of second long strip optical films; as well as A step of classifying the plurality of second long optical films into two or more groups based on in-plane phase difference.

12. The management method according to claim 11, wherein: The classifying step includes classifying the plurality of second long-length optical films into two or more groups according to the width of each predetermined in-plane phase difference.

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