CN118805120A

CN118805120A - Optical laminate, lens unit and display method

Info

Publication number: CN118805120A
Application number: CN202380024841.3A
Authority: CN
Inventors: 小野健太郎; 后藤周作; 麻野井祥明
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2022-03-14
Filing date: 2023-03-08
Publication date: 2024-10-18
Also published as: JP2024095150A

Abstract

The invention provides an optical laminate capable of realizing light weight of VR goggles and improving visibility. An optical laminate (100) according to an embodiment of the present invention comprises a laminated film (31) having a base material and a surface treatment layer, and a phase difference member (22), wherein the base material of the laminated film is disposed adjacent to the phase difference member, the base material of the laminated film comprises a (meth) acrylic resin, and the laminate smoothness of the optical laminate is 1.0arcmin or less.

Description

Optical laminate, lens unit, and display method

Technical Field

The invention relates to an optical laminate, a lens unit, and a display method.

Background

Image display devices, such as liquid crystal display devices and Electroluminescent (EL) display devices (for example, organic EL display devices), are rapidly spreading. In an image display device, an optical member such as a polarizing member or a phase difference member is generally used in order to realize image display and improve image display performance (for example, refer to patent document 1).

In recent years, new uses of image display devices have been developed. For example, goggles with displays (VR goggles) for achieving Virtual Reality (VR) have begun to be commercialized. Since VR goggles have been studied for use in various scenes, light weight, improved visibility, and the like are desired. The weight reduction can be achieved by, for example, thinning a lens used for VR goggles. On the other hand, it is also desired to develop an optical member suitable for a display system using a thin lens.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2021-103286

Disclosure of Invention

Problems to be solved by the invention

In view of the above, a main object of the present invention is to provide an optical laminate capable of realizing weight reduction and improvement in visibility of VR goggles.

Means for solving the problems

1. An optical laminate according to an embodiment of the present invention includes a laminate film having a base material and a surface treatment layer, and a phase difference member, wherein the base material of the laminate film is disposed adjacent to the phase difference member, and the base material of the laminate film includes a (meth) acrylic resin, and the laminate smoothness of the optical laminate is 1.0arcmin or less.

2. The optical laminate according to the above 1, wherein the surface smoothness of the base material of the laminate film may be 0.7arcmin or less.

3. The optical laminate according to the item 1 or 2, wherein the surface smoothness of the laminate film is 0.5arcmin or less.

4. The optical laminate according to any one of the above 1 to 3, which has a laminate smoothness of 0.7arcmin or less.

5. The optical laminate according to any one of the above 1 to 4, wherein the surface-treated layer of the laminate film has an antireflection function.

6. The optical laminate according to any one of the above 1 to 5, wherein the retardation member may comprise a first retardation layer which exhibits refractive index characteristics of nx > ny.gtoreq.nz and satisfies the relationship of Re (450) < Re (550) < Re (650).

7. The optical laminate according to any one of 1 to 6, wherein the retardation member may comprise a second retardation layer exhibiting refractive index characteristics of nz > nx+.ny.

8. The optical laminate according to any one of the above 1 to 7, wherein the substrate of the laminated film has a transmittance of 20% or less at a wavelength of 400 nm.

9. The optical laminate according to any one of the above 1 to 8, wherein Re (550) is 130nm to 160nm.

10. The lens unit according to an embodiment of the present invention is a display system for displaying an image to a user, the lens unit including:

A reflective polarizing member which emits light, which is emitted from a display surface of a display element for displaying an image, forward and which reflects the light after passing through the polarizing member and the 1λ/4 th member;

a first lens unit disposed on an optical path between the display element and the reflective polarizing member;

a half mirror disposed between the display element and the first lens portion, and configured to transmit light emitted from the display element and reflect light reflected by the reflective polarizing member toward the reflective polarizing member;

a second lens unit disposed in front of the reflective polarizing member; and

The optical layered body according to any one of the above 1 to 9, which is disposed on an optical path between the half mirror and the reflective polarizing member.

11. The display method according to an embodiment of the present invention includes:

Passing the light of the display image emitted through the polarizing member and the 1λ/4 th member through the half mirror and the first lens section;

A step of passing the light passing through the half mirror and the first lens portion through the optical layered body according to any one of 1 to 9;

A step of reflecting the light passing through the optical laminate toward the half mirror at a reflective polarizing member;

transmitting the light reflected by the reflective polarizing member and the half mirror through the optical laminate to the reflective polarizing member; and

And passing the light passing through the reflective polarizing member through the second lens section.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the optical laminate of the embodiment of the present invention, it is possible to achieve a reduction in weight and an improvement in visibility of VR goggles.

Drawings

Fig. 1 is a schematic diagram showing a schematic configuration of a display system according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of details of a lens portion of the display system shown in fig. 1.

Fig. 3 is a schematic perspective view showing an example of a multilayer structure included in the reflective polarizing film.

Symbol description

2. Display system

4. Lens part

12. Display element

14. Reflective polarizing component

16. A first lens part

18. Half mirror

20. First phase difference member

22. Second phase difference member

24. A second lens part

28. Absorption type polarizing component

30. Third phase difference component

31. First protective member

32. Second protective member

41. Adhesive layer

42. Adhesive layer

43. Adhesive layer

44. Adhesive layer

45. Adhesive layer

46. Adhesive layer

100 First laminate (optical laminate)

200 Second laminate section

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. For the sake of more clear explanation, the drawings may schematically show the width, thickness, shape, etc. of each part in comparison with the embodiments, but are merely examples, and do not limit the explanation of the present invention. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and overlapping description thereof may be omitted.

(Definition of terms and symbols)

The terms and symbols in the present specification are defined as follows.

(1) Refractive index (nx, ny, nz)

"Nx" is a refractive index in a direction in which the refractive index in the plane reaches the maximum (i.e., the slow axis direction), "ny" is a refractive index in a direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and "nz" is a refractive index in the thickness direction.

(2) In-plane phase difference (Re)

"Re (λ)" is the in-plane retardation measured at 23℃with light of wavelength λnm. For example, "Re (550)" is the in-plane retardation measured at 23℃with light having a wavelength of 550 nm. When the thickness of the layer (film) is d (nm), the following formula can be used: re (λ) = (nx-ny) ×d was obtained as Re (λ).

(3) Retardation in thickness direction (Rth)

"Rth (λ)" is a phase difference in the thickness direction measured at 23℃with light having a wavelength of λnm. For example, "Rth (550)" is a phase difference in the thickness direction measured at 23℃with light having a wavelength of 550 nm. When the thickness of the layer (film) is d (nm), the following formula can be used: rth (λ) = (nx-nz) ×d to obtain Rth (λ).

(4) Nz coefficient

The Nz coefficient can be obtained by nz=rth/Re.

(5) Angle of

In this specification, when referring to an angle, the angle includes both clockwise and counterclockwise with respect to a reference direction. Thus, for example, "45" means ± 45 °.

Fig. 1 is a schematic diagram showing a schematic configuration of a display system according to an embodiment of the present invention. Fig. 1 schematically illustrates the arrangement, shape, and the like of the respective components of the display system 2. The display system 2 includes a display element 12, a reflective polarizing member 14, a first lens portion 16, a half mirror 18, a first phase difference member 20, a second phase difference member 22, and a second lens portion 24. The reflective polarizing member 14 is disposed on the display surface 12a side of the display element 12, that is, in front of the display element, and can reflect light emitted from the display element 12. The first lens portion 16 is disposed on the optical path between the display element 12 and the reflective polarizing member 14, and the half mirror 18 is disposed between the display element 12 and the first lens portion 16. The first phase difference member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second phase difference member 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing member 14.

The components (in the illustrated example, the half mirror 18, the first lens unit 16, the second phase difference member 22, the reflective polarizing member 14, and the second lens unit 24) disposed in front of the half mirror or the first lens unit are sometimes collectively referred to as a lens unit (lens unit 4).

The display element 12 is, for example, a liquid crystal display or an organic EL display, and has a display surface 12a for displaying an image. The 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, for example, and is emitted as 1 st linearly polarized light.

The first phase difference member 20 includes 1λ/4 th members capable of converting the 1 st linearly polarized light incident on the first phase difference member 20 into 1 st circularly polarized light. In the case where the first phase difference member does not include a member other than the 1λ/4 th member, the first phase difference member may correspond to the 1λ/4 th member. The first phase difference member 20 may be integrally provided to the display element 12.

The half mirror 18 transmits light emitted from the display element 12, and reflects light reflected by the reflective polarizing member 14 toward the reflective polarizing member 14. The half mirror 18 is integrally provided to the first lens portion 16.

The second phase difference member 22 includes a2λ/4 th member that transmits the light reflected by the reflective polarizing member 14 and the half mirror 18 through the reflective polarizing member 14. In the case where the second phase difference member does not include a member other than the 2λ/4 th member, the second phase difference member may correspond to the 2λ/4 th member. The second phase difference member 22 may be integrally provided to the first lens portion 16.

The 1 st circularly polarized light emitted from the 1 st λ/4 th member included in the first phase difference member 20 passes through the half mirror 18 and the first lens section 16, and is converted into the 2 nd linearly polarized light by the 2 nd λ/4 th member included in the second phase difference member 22. The 2 nd linearly polarized light emitted from the 2λ/4 th member is not transmitted through the reflective polarizing member 14 but reflected toward the half mirror 18. At this time, the polarization direction of the 2 nd linearly polarized light incident on the reflective polarizing member 14 is the same direction as the reflection axis of the reflective polarizing member 14. Therefore, the 2 nd linearly polarized light incident on the reflective polarizing member 14 is reflected at the reflective polarizing member 14.

The 2 nd linear polarized light reflected by the reflective polarizing member 14 is converted into 2 nd circular polarized light by the 2λ/4 th member included in the second phase difference member 22, and the 2 nd circular polarized light emitted from the 2λ/4 th member is reflected by the half mirror 18 after passing through the first lens portion 16. The 2 nd circularly polarized light reflected by the half mirror 18 passes through the first lens portion 16, and is converted into the 3 rd linearly polarized light by the 2λ/4 th member included in the second phase difference member 22. The 3 rd linearly polarized light is transmitted through the reflective polarizing member 14. At this time, the polarization direction of the 3 rd linearly polarized light incident on the reflective polarizing member 14 is the same as the transmission axis of the reflective polarizing member 14. Therefore, the 3 rd linearly polarized light incident on the reflective polarizing member 14 is transmitted through the reflective polarizing member 14.

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

For example, the absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 may be arranged substantially parallel to each other or substantially orthogonal to each other. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the 1λ/4 th member included in the first phase difference member 20 is, for example, 40 ° to 50 °, 42 ° to 48 °, or about 45 °. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the 2λ/4 th member included in the second phase difference member 22 is, for example, 40 ° to 50 °, 42 ° to 48 °, or about 45 °.

The in-plane phase difference Re (550) of the 1λ/4 th member may be, for example, 100nm to 190nm, 110nm to 180nm, 130nm to 160nm, or 135nm to 155nm. The 1λ/4 th member preferably exhibits a reverse dispersion wavelength characteristic in which a phase difference value becomes large in accordance with the wavelength of the measurement light. The 1λ/4 th member preferably satisfies the relationship of Re (450) < Re (550) < Re (650). Re (450)/Re (550) of the 1λ/4 th member is, for example, 0.75 or more and less than 1, or may be 0.8 or more and 0.95 or less.

The in-plane phase difference Re (550) of the 2λ/4 th member may be, for example, 100nm to 190nm, 110nm to 180nm, 130nm to 160nm, or 135nm to 155nm. The 2λ/4 th member preferably exhibits a reverse dispersion wavelength characteristic in which a phase difference value becomes large in accordance with the wavelength of the measurement light. The 2λ/4 th member preferably satisfies the relationship of Re (450) < Re (550) < Re (650). Re (450)/Re (550) of the 2λ/4 th member is, for example, 0.75 or more and less than 1, or may be 0.8 or more and 0.95 or less.

In the lens portion 4, a space may be formed between the first lens portion 16 and the second lens portion 24. In this case, the member disposed between the first lens portion 16 and the second lens portion 24 is preferably integrally provided to either one of the first lens portion 16 and the second lens portion 24. For example, a member disposed between the first lens portion 16 and the second lens portion 24 is preferably integrated with either one of the first lens portion 16 and the second lens portion 24 via an adhesive layer. According to this aspect, for example, the workability of the respective members can be made excellent. The adhesive layer may be formed of an adhesive or an adhesive. Specifically, the adhesive layer may be an adhesive layer or an adhesive layer. The thickness of the adhesive layer is, for example, 0.05 μm to 30. Mu.m.

Fig. 2 is a schematic cross-sectional view showing an example of details of a lens portion of the display system shown in fig. 1. Specifically, fig. 2 shows the first lens portion, the second lens portion, and members disposed therebetween. The lens section 4 includes: the first lens portion 16, the first laminated portion 100 provided adjacent to the first lens portion 16, the second lens portion 24, and the second laminated portion 200 provided adjacent to the second lens portion 24. In the example shown in fig. 2, the first lamination portion 100 is disposed separately from the second lamination portion 200. Although not shown, the half mirror may be integrally provided to the first lens portion 16. Hereinafter, the first laminated portion may be referred to as an optical laminated body.

The first lamination portion 100 includes the second phase difference member 22 and an adhesive layer (for example, an adhesive layer) disposed between the first lens portion 16 and the second phase difference member 22, and is integrally provided to the first lens portion 16 via the adhesive layer 41. The first laminated portion 100 further includes a first protection member 31 disposed in front of the second phase difference member 22. The first protection member 31 is laminated on the second phase difference member 22 via an adhesive layer (for example, an adhesive layer) 42, and is disposed adjacent to the second phase difference member 22. The first protection member 31 may be located at the outermost surface of the first lamination portion 100. In the present specification, adjacent includes not only direct adjacent but also adjacent via an adhesive layer.

In the example shown in fig. 2, the second phase difference member 22 includes a member (second phase difference layer) 22b having refractive index characteristics in which nz > nx+.ny, in addition to the 2λ/4 th member (first phase difference layer) 22 a. The second phase difference member 22 has a laminated structure of a first phase difference layer 22a and a second phase difference layer 22b. By using the member 22b showing a relationship of nz > nx+.ny, light leakage (for example, light leakage in an oblique direction) can be prevented. As shown in FIG. 2, in the second phase difference member 22, it is preferable that the position of the 2λ/4 th member 22a is closer to the front than the member 22b showing the relationship of nz > nx+.ny.

The 2λ/4 th member (first retardation layer) 22a and the member (second retardation layer) 22b exhibiting a relationship of nz > nx+.ny are preferably laminated via an adhesive layer not shown. The second phase difference member 22 includes a first phase difference layer 22a, an adhesive layer, and a second phase difference layer 22b. By stacking the phase difference layers with the adhesive layer, cracking and cracking of the phase difference layers can be suppressed. In addition, peeling between the retardation layers can be prevented. Further, an optical laminate excellent in durability can be obtained.

The above-mentioned 2λ/4 th member preferably shows a relationship of nx > ny.gtoreq.nz. Here, "ny=nz" includes not only the case where ny is exactly equal to nz but also the case where ny is substantially equal. Therefore, ny < nz may be used in some cases within a range that does not impair the effect of the present invention. The Nz coefficient of the 2λ/4 th member is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

The 2λ/4 th member is formed of any suitable material capable of satisfying the above characteristics. The 2λ/4 th member may be, for example, a stretched film of a resin film or an alignment-fixing layer of a liquid crystal compound.

The resin contained in the resin film includes: polycarbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cyclic olefin-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, acrylic-based resins, and the like. These resins may be used alone or in combination. Examples of the method of combination include blending and copolymerization. In the case where the 2λ/4 th member exhibits the inverse dispersion wavelength characteristic, a resin film containing a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, may be simply referred to as a polycarbonate-based resin) may be suitably used.

As the polycarbonate resin, any suitable polycarbonate resin can be used. For example, the polycarbonate resin contains a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from alicyclic diols, alicyclic dimethanol, di-, tri-, or polyethylene glycols, and alkylene glycols or spirodiols. Preferably, the polycarbonate resin contains a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, a structural unit derived from alicyclic dimethanol, and/or a structural unit derived from di-, tri-, or polyethylene glycol; it is further preferable to contain a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di-, tri-, or polyethylene glycol. The polycarbonate resin may contain a structural unit derived from another dihydroxy compound as required. Details of a polycarbonate resin suitable for use in the 2λ/4 th member and a method for forming the 2λ/4 th member are described in, for example, japanese patent application laid-open No. 2014-10291, japanese patent application laid-open No. 2014-26262, japanese patent application laid-open No. 2015-212816, japanese patent application laid-open No. 2015-212817, and Japanese patent application laid-open No. 2015-212818, and these publications are incorporated by reference into the present specification.

The thickness of the 2λ/4 th member composed of the stretched film of the resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, more preferably 20 μm to 60 μm.

The alignment fixing layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a predetermined direction in the layer and the alignment state thereof is fixed. The term "alignment layer" is a concept including an alignment cured layer obtained by curing a liquid crystal monomer as described later. In the 2λ/4 th member, typically, a rod-like liquid crystal compound is aligned in a state of being aligned along the slow axis direction of the 2λ/4 th member (parallel alignment (homogeneous alignment)). Examples of the rod-like liquid crystal compound include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably capable of undergoing polymerization. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by polymerizing after aligning the liquid crystal compound.

The alignment fixing layer (liquid crystal alignment fixing layer) of the above-mentioned liquid crystal compound can be formed by the following method: an alignment treatment is performed on the surface of a given substrate, a coating liquid containing a liquid crystal compound is applied to the surface, the liquid crystal compound is aligned in a direction corresponding to the alignment treatment, and the alignment state is fixed. As the orientation treatment, any suitable orientation treatment may be employed. Specific examples include: mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of the mechanical orientation treatment include a rubbing treatment and a stretching treatment. Specific examples of the physical alignment treatment include a magnetic field alignment treatment and an electric field alignment treatment. Specific examples of the chemical alignment treatment include a tilt vapor deposition method and a photo alignment treatment. The process conditions of the various orientation processes may be any suitable conditions depending on the purpose.

The alignment of the liquid crystal compound may be performed by performing a treatment at a temperature at which a liquid crystal phase is exhibited, corresponding to the kind of the liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound is in a liquid crystal state, and the liquid crystal compound is aligned in accordance with the alignment treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the aligned liquid crystal compound as described above. In the case where the liquid crystal compound is polymerizable or crosslinkable, the alignment state can be fixed by subjecting the aligned liquid crystal compound to polymerization treatment or crosslinking treatment as described above.

As the above-mentioned liquid crystal compound, any suitable liquid crystal polymer and/or liquid crystal monomer may be used. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination. Specific examples of the liquid crystal compound and a method for producing the liquid crystal alignment fixing layer are described in, for example, japanese patent application laid-open No. 2006-163343, japanese patent application laid-open No. 2006-178389, and International publication No. 2018/123551. The disclosures of these publications are incorporated by reference into this specification.

The thickness of the 2λ/4 th member composed of the liquid crystal alignment cured layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, still more preferably 1 μm to 4 μm.

The retardation Rth (550) in the thickness direction of the member (second phase difference layer) having the refractive index characteristics in which nz > nx.gtoreq.ny is preferably from-260 nm to-10 nm, more preferably from-230 nm to-15 nm, and even more preferably from-215 nm to-20 nm. In one embodiment, the second phase difference layer is a so-called positive C plate whose refractive index shows a relationship of nx=ny. Here, "nx=ny" includes not only the case where nx and ny are exactly equal but also the case where nx and ny are substantially equal. For example, the case where Re (550) is less than 10nm is also included. In another embodiment, the refractive index of the second phase difference layer exhibits a relationship of nx > ny. In this case, the in-plane phase difference Re (550) of the second phase difference layer is preferably 10nm to 150nm, more preferably 10nm to 80nm.

The member whose refractive index characteristics show a relationship of nz > nx+.ny can be formed of any suitable material. Preferably a film comprising a liquid crystal material fixed in a vertical orientation. The liquid crystal material (liquid crystal compound) capable of vertical alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such a liquid crystal compound and a method for forming a film include those described in [0020] to [0042] of JP-A-2002-333642. In this case, the thickness is preferably 0.1 μm to 5. Mu.m, more preferably 0.5 μm to 4. Mu.m.

As another preferable specific example, the member having refractive index characteristics showing a relationship of nz > nx.gtoreq.ny may be a retardation film formed of a fumaric acid diester resin described in Japanese unexamined patent publication No. 2012-32784. In this case, the thickness is preferably 5 μm to 50. Mu.m, more preferably 10 μm to 35. Mu.m.

The adhesive layer included in the second phase difference member 22 may be formed of any suitable adhesive. The adhesive has a property of having fluidity at the time of application and being cured by curing treatment (for example, irradiation with active energy rays, heating) in the process of forming the adhesive layer, the state of which is irreversibly changed from a liquid to a solid. As the adhesive, a curable adhesive is preferably used. Specifically, the adhesive layer is preferably a cured layer of resin. As the curable adhesive, an ultraviolet curable adhesive can be preferably used.

The ultraviolet curable adhesive contains a curable monomer such as a compound having a (meth) acryloyl group or a compound having a vinyl group as a curable monomer. It may be preferable to use a compound having a (meth) acryloyl group. Here, (meth) acryl means acryl and/or methacryl.

The thickness of the adhesive layer included in the retardation member is, for example, 0.5 μm or more and 3 μm or less, preferably 2 μm or less, more preferably 1.3 μm or less, still more preferably 1.1 μm or less, and particularly preferably 0.9 μm or less. With such a thickness, an optical laminate having extremely excellent smoothness can be obtained.

Typically, the first protective member includes a base material. The thickness of the base material is preferably 5 μm to 80. Mu.m, more preferably 10 μm to 50. Mu.m, still more preferably 15 μm to 40. Mu.m. The surface smoothness of the substrate is preferably 0.7arcmin or less, more preferably 0.6arcmin or less, still more preferably 0.5arcmin or less, and particularly preferably 0.45arcmin or less. In the display system described above, the image can be enlarged in the lens portion (for example, by a convex lens), and the smoothness of the optical laminate may significantly affect the visibility. The smoothness of the base material of the protective member that can be positioned on the outermost surface of the laminated portion can be made excellent, and the smoothness of the optical laminate obtained using the base material can also be made extremely excellent. Further, according to such an optical laminate, significantly excellent visibility can be achieved in the display system. For example, a clear image without distortion can be realized. The surface smoothness of the substrate is, for example, 0.1arcmin or more. The surface smoothness can be measured by focusing the irradiation light on the surface of the object.

The substrate may be composed of any suitable film. Examples of the material that becomes the main component of the film constituting the substrate include: cellulose resins such as cellulose Triacetate (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, cycloolefins such as polynorbornene, polyolefins, (meth) acrylic acid, acetate resins, and the like. Here, (meth) acrylic acid means acrylic acid and/or methacrylic acid. In one embodiment, the substrate is preferably formed of a (meth) acrylic resin. By using the (meth) acrylic resin, film formation of a base material excellent in smoothness (for example, satisfying the above surface smoothness) can be achieved by extrusion molding. And a protective member excellent in smoothness can be obtained.

For example, the transmittance of the substrate at a wavelength of 400nm may be 20% or less, for example.

The first protective member is preferably composed of a laminated film having a base material and a surface treatment layer formed on the base material. The thickness of the laminated film is preferably 10 μm to 80 μm, more preferably 15 μm to 60 μm, and still more preferably 20 μm to 45 μm. The thickness of the surface treatment layer is preferably 0.5 μm to 10. Mu.m, more preferably 1 μm to 7. Mu.m, still more preferably 2 μm to 5. Mu.m.

Typically, the surface treatment layer comprises a hard coat layer. Typically, the hard coating layer is formed by coating a hard coating layer forming material on a substrate and curing the coating layer. Typically, the hard coat layer forming material contains a curable compound as a layer forming component. Examples of the curing mechanism of the curable compound include a thermosetting type and a photo-curing type. Examples of the curable compound include monomers, oligomers, and prepolymers. As the curable compound, a polyfunctional monomer or oligomer can be preferably used. Examples of the polyfunctional monomer or oligomer include a monomer or oligomer having 2 or more (meth) acryloyl groups, an oligomer of urethane (meth) acrylate or urethane (meth) acrylate, an epoxy monomer or oligomer, and an organosilicon monomer or oligomer.

The thickness of the hard coat layer is preferably 0.5 μm to 10. Mu.m, more preferably 1 μm to 7. Mu.m, still more preferably 2 μm to 5. Mu.m.

The surface treatment layer preferably comprises a functional layer. The functional layer preferably functions as an antireflection layer. In a preferred embodiment, the surface treatment layer includes the hard coat layer and the antireflection layer in this order from the substrate side. The thickness of the functional layer is preferably 0.05 μm to 10. Mu.m, more preferably 0.1 μm to 5. Mu.m, still more preferably 0.1 μm to 2. Mu.m.

The first protection member having the surface treatment layer may be disposed such that the surface treatment layer is located on the front side. Specifically, the surface treatment layer may be located at the outermost surface of the first lamination portion. The surface treatment layer may have any suitable function. For example, the surface treatment layer preferably has an antireflection function from the viewpoint of suppressing light loss at the interface with air and from the viewpoint of improving visibility. In one embodiment, the maximum value of the 5 ° specular reflectance spectrum of the first protective member in the range of 420nm to 680nm is preferably 2.0% or less, more preferably 1.2% or less, further preferably 1.0% or less, particularly preferably 0.8% or less. Here, the 5 ° specular reflectance can be measured, for example, as follows: the measurement sample was prepared by adhering the measurement object to a black acrylic plate using an adhesive, and the measurement was performed by using a spectrophotometer (trade name "U-4100" manufactured by HITACHI HIGH-Tech corporation) as a measurement device, with an incident angle of light to the measurement sample set at 5 °.

The surface smoothness of the first protective member is preferably 0.5arcmin or less, more preferably 0.4arcmin or less. The surface smoothness of the first protective member is substantially, for example, 0.1arcmin or more. The stack smoothness of the optical stack 100 is 1.0arcmin or less, preferably 0.9arcmin or less, more preferably 0.8arcmin or less, and even more preferably 0.7arcmin or less. By making the optical laminate satisfy such laminate smoothness, the generation of diffused light can be suppressed, and the image can be suppressed from becoming unclear. The stack smoothness of the optical stack 100 is, for example, 0.1arcmin or more. The smoothness of the laminate can be obtained by irradiating the object with irradiation light, and detecting reflection and transmission of each member constituting the object (laminate).

The optical stack 100 may have high transmittance. For example, the Y value of the transmittance of the visibility-modifying monomer of the optical laminate 100 is, for example, 90% or more, preferably 93% or more, more preferably 94% or more, and still more preferably 95% or more. The transmittance may be, for example, a single body transmittance Ts measured by an ultraviolet-visible spectrophotometer (manufactured by Japanese Specification Co., ltd., V-7100). Here, ts is a Y value obtained by measuring a 2-degree field of view (C light source) of JIS Z8701 and performing visibility correction.

The in-plane retardation Re (550) of the optical laminate 100 may be, for example, 100nm to 190nm, 110nm to 180nm, 130nm to 160nm, or 135nm to 155nm.

The second lamination portion 200 includes the reflective polarizing member 14, and an adhesive layer (for example, an adhesive layer) disposed between the reflective polarizing member 14 and the second lens portion 24. From the viewpoint of improving visibility, the second laminated portion 200 further includes, for example, an absorptive polarizing member 28 disposed between the reflective polarizing member 14 and the second lens portion 24. The absorptive polarizing member 28 is laminated in front of the reflective polarizing member 14 via an adhesive layer (e.g., an adhesive layer) 44. The reflection axis of the reflective polarizing member 14 and the absorption axis of the absorptive polarizing member 28 may be disposed substantially parallel to each other, and the transmission axis of the reflective polarizing member 14 and the transmission axis of the absorptive polarizing member 28 may be disposed substantially parallel to each other. By laminating the reflective polarizing member 14 and the absorptive polarizing member 28 via the adhesive layer, the offset of the axis arrangement of the reflection axis and the absorption axis (transmission axis and transmission axis) can be prevented. In addition, adverse effects caused by an air layer that may be formed between the reflective polarizing member 14 and the absorptive polarizing member 28 can be suppressed.

The second lamination portion 200 further includes a second protection member 32 disposed rearward of the reflective polarizing member 14. The second protective member 32 is laminated to the reflective polarizing member 14 via an adhesive layer (e.g., an adhesive layer) 43. The second protective member 32 may be positioned at the outermost surface of the second lamination portion 200. The first protection member 31 is disposed opposite to the second protection member 32 with a space therebetween. The second protective member may be typically a laminated film having a base material and a surface treatment layer, as in the case of the first protective member. In this case, the surface treatment layer may be located at the outermost surface of the second lamination portion. The details of the second protection member can be the same as those of the first protection member. Specifically, the same description as that of the first protective member can be applied to the reflection characteristics of the second protective member, the effects thereof, the smoothness, the thickness, and the constituent materials.

In the example shown in fig. 2, the second lamination portion 200 further includes a third phase difference member 30 disposed between the absorptive polarizing member 28 and the second lens portion 24. The third phase difference member 30 is laminated to the absorptive polarizing member 28 via an adhesive layer (e.g., an adhesive layer) 45. The third phase difference member 30 is laminated on the second lens portion 24 via an adhesive layer (for example, an adhesive layer) 46, and the second lamination portion 200 is integrally provided on the second lens portion 24. The third phase difference member 30 comprises, for example, a 3λ/4 th member. The angle between the absorption axis of the absorption-type polarizing member 28 and the slow axis of the 3λ/4 th member included in the third phase difference member 30 is, for example, 40 ° to 50 °, 42 ° to 48 °, or about 45 °. By providing such a member, reflection of external light from the second lens portion 16 side, for example, can be prevented. In the case where the third phase difference member does not include a member other than the 3λ/4 th member, the third phase difference member may correspond to the 3λ/4 th member.

The reflective polarizing member transmits polarized light (typically, linearly polarized light) parallel to the transmission axis thereof while maintaining the polarization state thereof, and reflects light having other polarization states. As the reflective polarizing member, a film having a multilayer structure (sometimes referred to as a reflective polarizing film) is typically used. In this case, the thickness of the reflective polarizing member is, for example, 10 μm to 150 μm, preferably 20 μm to 100 μm, and more preferably 30 μm to 60 μm.

Fig. 3 is a schematic perspective view showing an example of a multilayer structure included in the reflective polarizing film. The multilayer structure 14a includes layers a having birefringence and layers B having substantially no birefringence alternately. The total number of layers constituting the multilayer structure may be 50 to 1000. For example, the refractive index nx in the x-axis direction of the a layer is larger than the refractive index ny in the y-axis direction, the refractive index nx in the x-axis direction of the B layer is substantially the same as the refractive index ny in the y-axis direction, and the refractive index difference between the a layer and the B layer is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction can be made the reflection axis and the y-axis direction can be made the transmission axis. The refractive index difference between the a layer and the B layer in the x-axis direction is preferably 0.2 to 0.3.

The a layer is typically formed of a material exhibiting birefringence by stretching. Examples of such a material include naphthalene dicarboxylic acid polyesters (e.g., polyethylene naphthalate), polycarbonates, and acrylic resins (e.g., polymethyl methacrylate). The B layer is typically formed of a material that does not substantially exhibit birefringence even when stretched. Examples of such a material include a copolyester of naphthalene dicarboxylic acid and terephthalic acid. The above-described multilayer structure may be formed by combining coextrusion with stretching. For example, the material constituting the layer a and the material constituting the layer B are extruded and then multilayered (for example, using a multiplier). Subsequently, the obtained multilayer laminate is stretched. The x-axis direction of the illustrated example may correspond to the stretching direction.

Examples of the commercial products of the reflective polarizing film include trade names "DBEF", "APF" manufactured by 3M company and trade name "APCF" manufactured by niton electric company.

The orthogonal transmittance (Tc) of the reflective polarizing member (reflective polarizing film) may be, for example, 0.01% to 3%. The single transmittance (Ts) of the reflective polarizing member (reflective polarizing film) is, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing member (reflective polarizing film) may be 92% to 99.99%, for example.

The orthogonal transmittance, the single transmittance, and the polarization degree can be measured by using an ultraviolet-visible spectrophotometer, for example. The degree of polarization P can be determined by measuring the individual transmittance Ts, the parallel transmittance Tp, and the orthogonal transmittance Tc using an ultraviolet-visible spectrophotometer, and from the obtained Tp and Tc, the degree of polarization P can be obtained by the following equation. Note that Ts, tp, and Tc are Y values obtained by measuring a 2-degree field of view (C light source) of JIS Z88 701 and performing visibility correction.

Degree of polarization P (%) = { (Tp-Tc)/(tp+tc) } ^1/2 ×100

The absorption-type polarizing member may typically include a resin film (sometimes referred to as an absorption-type polarizing film) containing a dichroic substance. The thickness of the absorption-type polarizing film is, for example, 1 μm or more and 20 μm or less, and may be 2 μm or more and 15 μm or less, or may be 12 μm or less, or may be 10 μm or less, or may be 8 μm or less, or may be 5 μm or less.

The absorption-type polarizing film may be formed of a single resin film or may be formed of a laminate of two or more layers.

In the case of producing a single-layer resin film, for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or an ethylene-vinyl acetate copolymer partially saponified film is subjected to dyeing treatment or stretching treatment with a dichroic substance such as iodine or a dichroic dye, thereby obtaining an absorptive polarizing film. Among them, an absorbing type polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching the same is preferable.

The dyeing with iodine can be performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the unidirectional stretching is preferably 3 to 7 times. Stretching may be performed after dyeing treatment or may be performed while dyeing. In addition, dyeing may be performed after stretching. The PVA-based film may be subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, and the like as needed.

As a laminate produced using the above-described laminate of two or more layers, there may be mentioned a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a laminate of a resin base material and a PVA-based resin layer formed on the resin base material by coating. An absorptive polarizing film obtained by using a laminate of a resin base material and a PVA-based resin layer formed on the resin base material, can be produced by the following method: for example, a PVA-based resin solution is applied to a resin substrate, and dried to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; the laminate was stretched and dyed to prepare an absorptive polarizing film from the PVA-based resin layer. In the present embodiment, it is preferable to form a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin on one side of the resin base material. Stretching typically includes immersing the laminate in an aqueous boric acid solution to stretch the laminate. The stretching may further include stretching the laminate in a gas atmosphere at a high temperature (for example, 95 ℃ or higher) before stretching in an aqueous boric acid solution, as needed. In the present embodiment, it is preferable that the laminate is subjected to a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction so as to shrink by 2% or more in the width direction. Typically, the manufacturing method of the present embodiment includes sequentially subjecting the laminate to an auxiliary stretching treatment in a gas atmosphere, a dyeing treatment, a stretching treatment in an aqueous solution, and a drying shrinkage treatment. By introducing the auxiliary stretching, even when PVA is coated on the thermoplastic resin, crystallinity of PVA can be improved, and high optical characteristics can be achieved. Further, by increasing the orientation of PVA in advance, problems such as decrease in orientation and dissolution of PVA can be prevented when immersed in water in the subsequent dyeing step and stretching step, and high optical characteristics can be achieved. In addition, when the PVA-based resin layer is immersed in a liquid, disorder of alignment of polyvinyl alcohol molecules and decrease of alignment property can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical characteristics of the absorptive polarizing film obtained by the treatment step of immersing the laminate in a liquid, such as dyeing treatment or stretching treatment in an aqueous solution. Further, the laminate is shrunk in the width direction by the drying shrinkage treatment, whereby the optical characteristics can be improved. The obtained laminate of the resin substrate and the absorption-type polarizing film may be used as it is (that is, the resin substrate may be used as a protective layer for the absorption-type polarizing film), or the resin substrate may be peeled from the laminate of the resin substrate and the absorption-type polarizing film, and any appropriate protective layer according to the purpose may be laminated on the peeled surface or on the surface opposite to the peeled surface. Details of such a method for producing an absorbing-type polarizing film are described in, for example, japanese patent application laid-open No. 2012-73580 and japanese patent No. 6470455. The entire disclosures of these publications are incorporated herein by reference.

The orthogonal transmittance (Tc) of the absorption-type polarizing member (absorption-type polarizing film) is preferably 0.5% or less, more preferably 0.1% or less, and further preferably 0.05% or less. The single transmittance (Ts) of the absorption-type polarizing member (absorption-type polarizing film) is, for example, 41.0% to 45.0%, and preferably 42.0% or more. The polarization degree (P) of the absorptive polarizing member (absorptive polarizing film) is, for example, 99.0% to 99.997%, and preferably 99.9% or more.

The in-plane retardation Re (550) of the 3λ/4 th member may be, for example, 100nm to 190nm, 110nm to 180nm, 130nm to 160nm, or 135nm to 155nm. The 3λ/4 th member preferably exhibits a reverse dispersion wavelength characteristic in which a phase difference value becomes large in accordance with the wavelength of the measurement light. Re (450)/Re (550) of the 3λ/4 th member is, for example, 0.75 or more and less than 1, or may be 0.8 or more and 0.95 or less. Preferably, the refractive index characteristics of the 3λ/4 th member show a relationship of nx > ny.gtoreq.nz. The Nz coefficient of the 3λ/4 th member is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

The 3λ/4 th member is formed of any suitable material capable of satisfying the above characteristics. The 3λ/4 th member may be, for example, a stretched film of a resin film or an alignment-fixing layer of a liquid crystal compound. The same description as the above-mentioned 2λ/4 th member can be applied to the 3λ/4 th member composed of a stretched film of a resin film or an alignment cured layer of a liquid crystal compound. The 2λ/4 th member and the 3λ/4 th member may have the same structure (e.g., a material for forming, a thickness, optical characteristics, etc.), or may have different structures.

The thickness of the adhesive layers used for lamination of the above-described members may be set to any appropriate thickness, respectively. The thickness of each of the pressure-sensitive adhesive layers used for lamination of the above-mentioned members is preferably 3 μm or more and 20 μm or less, and may be 15 μm or less, 10 μm or less, or 7 μm or less. With such a thickness, the degree of irregularities on the surface of the adhesive layer can be suppressed, and the smoothness of the laminated portion can be improved.

The adhesive layer may be composed of any suitable adhesive. Specific examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the kind, amount, combination and ratio of the monomers forming the base resin of the adhesive, the amount of the crosslinking agent, the reaction temperature, the reaction time, and the like, an adhesive having desired characteristics according to the purpose can be produced. The base resin of the adhesive may be used alone or in combination of two or more. As the base resin, an acrylic resin can be preferably used. Specifically, the adhesive layer is preferably formed of an acrylic adhesive.

For example, the adhesive layer can be formed by applying an adhesive composition containing an additive such as a base resin and a crosslinking agent and a solvent, and drying the composition. The adhesive composition may be applied directly to an adherend or may be applied to a substrate such as a substrate film prepared separately. Typically, drying is performed by heating.

For example, by adjusting the film thickness of the coating film of the adhesive composition, an adhesive layer excellent in smoothness can be obtained. If the film thickness is too thick, a liquid flow due to a temperature difference is generated in the coating film by heating, and an adhesive layer having a large degree of surface irregularities is formed.

In addition, for example, by controlling the drying conditions of the coating film of the adhesive composition, an adhesive layer excellent in smoothness can be obtained. Specifically, by adjusting the amount and speed of the air blown to the coating film during drying, an adhesive layer excellent in smoothness can be obtained. If the amount of wind and the wind speed of the wind blown onto the coating film are too large, undulation occurs in the coating film, and an adhesive layer having a large degree of surface irregularities is obtained. In one embodiment, the coating film is preferably dried by adjusting the air speed to a range of 2 to 15m/min, more preferably 2 to 8m/min, in a temperature environment of 65 to 110 ℃. For example, it is preferable to adjust the temperature and the wind speed to those described above in the vicinity of the inlet of the oven for drying after the application. Specifically, the temperature and the wind speed can be adjusted from the oven inlet to the center of the oven.

Examples

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The thickness, the phase difference value, and the surface smoothness are values measured by the following measurement method. Unless otherwise specifically stated, the "parts" and "%" are based on weight.

< Thickness >

The thickness of 10 μm or less was measured by a scanning electron microscope (product name "JSM-7100F", manufactured by Japanese electronics Co., ltd.). The thickness exceeding 10 μm was measured by a digital micrometer (manufactured by An Li Co., ltd., product name "KC-351C").

< Phase difference value >

The retardation value at each wavelength at 23℃was measured by using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan").

Surface smoothness

The surface smoothness was measured using a scanning white light interferometer (product name "NewView9000" manufactured by Zygo corporation). Specifically, a measurement sample is placed on a measurement table with a vibration isolation table, interference fringes are generated using single white LED illumination, and an interference objective lens (1.4 times) having a reference plane is scanned in the Z direction (thickness direction), whereby smoothness (surface smoothness) of the outermost surface of the measurement object in the field of view of 12.4mm ≡is selectively obtained.

When the object to be measured is an adhesive layer, the adhesive layer was attached to a micro slide glass (product name "S200200" manufactured by sonlano industrial Co., ltd.), and the smoothness of the exposed adhesive surface was measured. When the object to be measured is a film, an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm and less irregularities is formed on the glass, and the film to be measured is laminated on the pressure-sensitive adhesive surface so as not to introduce foreign matter, bubbles, and deformed streaks, and the smoothness of the surface opposite to the pressure-sensitive adhesive layer is measured. The acrylic pressure-sensitive adhesive layer having a thickness of 5 μm and less irregularities had a surface smoothness of 0.30arcmin.

For analysis, a value obtained by multiplying the index "Slope magnitude RMS" of the angle by 2 times (corresponding to 2σ) was defined as the surface smoothness (unit: arcmin).

Example 1

(Production of lambda/4 Member)

Polymerization was carried out using a batch polymerization apparatus comprising 2 vertical reactors each having stirring blades and a reflux condenser controlled at 100 ℃. 29.60 parts by mass (0.046 mol) of bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl ] methane, 29.21 parts by mass (0.200 mol) of Isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiro-glycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19X10 ^-2 parts by mass (6.78X10 ^-5 mol) of calcium acetate monohydrate as a catalyst were charged. After the inside of the reactor was replaced with nitrogen under reduced pressure, the reactor was heated by a heat medium, and stirring was started at the time when the internal temperature reached 100 ℃. The internal temperature was allowed to reach 220℃40 minutes after the start of the temperature increase, and the pressure was reduced while the temperature was maintained so as to reach 13.3kPa after 90 minutes from the start of the temperature increase. The phenol vapor produced as a by-product during the polymerization reaction was introduced into a reflux condenser at 100℃to return a certain amount of the monomer components contained in the phenol vapor to the reactor, and the non-condensed phenol vapor was introduced into the condenser at 45℃to be recovered. After nitrogen gas was introduced into the 1 st reactor to temporarily return to the atmospheric pressure, the oligomerization reaction liquid in the 1 st reactor was transferred to the 2 nd reactor. Then, the temperature rise and pressure reduction in the 2 nd reactor were started to reach an internal temperature of 240℃and a pressure of 0.2kPa over 50 minutes. The polymerization is then allowed to proceed until a given stirring power is reached. At the time of reaching a given power, nitrogen gas was introduced into the reactor to restore the pressure, the polyester carbonate resin produced was extruded into water, and the strand was cut to obtain pellets.

The obtained polyester carbonate resin (pellet) was dried under vacuum at 80℃for 5 hours, and then a long resin film having a thickness of 135 μm was produced by using a film-forming apparatus equipped with a single screw extruder (manufactured by Toshiba machinery Co., ltd., cylinder set temperature: 250 ℃), a T-die (width: 200mm, set temperature: 250 ℃), a chilled roll (set temperature: 120 to 130 ℃) and a winder. The obtained long resin film was stretched at a stretching temperature of 143℃and a stretching ratio of 2.8 times in the width direction to obtain a stretched film having a thickness of 47. Mu.m. The Re (550) of the obtained stretched film was 143nm, re (450)/Re (550) was 0.86, and the nz coefficient was 1.12.

(Formation of positive C plate)

A liquid crystal coating liquid was prepared by dissolving 20 parts by weight of a side chain type liquid crystal polymer represented by the following chemical formula (1) (in which numerals 65 and 35 represent mol% of monomer units, and which is represented by a block polymer for convenience: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal (trade name PaliocolorLC, manufactured by BASF Co., ltd.: paliocolorLC) exhibiting a nematic liquid crystal phase, and 5 parts by weight of a photopolymerization initiator (trade name IRGACURE 907, manufactured by Chiba SPECIALTY CHEMICALS Co., ltd.) in 200 parts by weight of cyclopentanone. Then, the coating liquid was applied to the PET substrate subjected to the vertical alignment treatment by a bar coater, and then heated and dried at 80 ℃ for 4 minutes, thereby aligning the liquid crystal. The liquid crystal layer was irradiated with ultraviolet light to cure the liquid crystal layer, whereby a positive C plate having a thickness of 4 μm and Rth (550) of-100 nm was formed on the substrate.

[ Chemical formula 1]

(Production of protective Member)

The following hard coat layer-forming material was applied to an acrylic film having a lactone ring structure (thickness: 40 μm, surface smoothness: 0.45 arcmin), heated at 90℃for 1 minute, and the heated coating layer was irradiated with ultraviolet light having a cumulative light amount of 300mJ/cm ² by a high-pressure mercury lamp to cure the coating layer, whereby an acrylic film having a hard coat layer having a thickness of 4 μm (thickness: 44 μm, surface smoothness: 0.4arcmin on the hard coat layer side) was produced.

Next, the coating liquid a for forming an antireflection layer described below was applied onto the hard coat layer by a wire bar, and the applied coating liquid was heated at 80 ℃ for 1 minute and dried, thereby forming a coating film. The dried coating film was irradiated with ultraviolet rays having an accumulated light quantity of 300mJ/cm ² by a high-pressure mercury lamp to cure the coating film, thereby forming an antireflection layer A having a thickness of 140 nm.

Next, the coating liquid B for forming an antireflection layer described below was coated on the antireflection layer a by using a bar, and the coated coating liquid was heated at 80 ℃ for 1 minute and dried, thereby forming a coating film. The dried coating film was irradiated with ultraviolet rays having an accumulated light quantity of 300mJ/cm ² by a high-pressure mercury lamp to cure the coating film, thereby forming an antireflection layer B having a thickness of 105 nm.

Thus, a protective member (thickness 44 μm, surface smoothness on the antireflection layer side: 0.4 arcmin) was obtained.

(Hard coat layer Forming Material)

A hard coat layer-forming material was prepared by mixing 50 parts of urethane acrylic oligomer (product of Xinzhou Chemicals, "NK Oligo UA-53H"), 30 parts of multifunctional acrylate containing pentaerythritol triacrylate as a main component (product of Osaka organic chemical industry Co., ltd., "Viscoat # 300"), 20 parts of 4-hydroxybutyl acrylate (product of Osaka organic chemical industry Co., ltd.), 1 part of leveling agent (product of DIC Co., ltd., "GRANDIC PC 4100"), and 3 parts of photopolymerization initiator (product of Ciba Japan Co., ltd., "IRGACURE 907") and diluting the mixture with methyl isobutyl ketone so that the solid content concentration becomes 50%.

(Coating liquid A for Forming an antireflection layer)

100 Parts by weight of a multifunctional acrylate (trade name "OPSTAR KZ6728", solid content 20% by weight, manufactured by Kyowa chemical Co., ltd.), 3 parts by weight of a leveling agent (trade name "GRANDIC PC4100", manufactured by DIC Co., ltd.), and 3 parts by weight of a photopolymerization initiator (trade name "OMNIRAD907", solid content 100% by weight, manufactured by BASF Co., ltd.) were mixed. The mixture was stirred using butyl acetate as a diluting solvent so that the solid content became 12 wt%, to prepare an antireflective layer-forming coating liquid a.

(Coating liquid B for Forming an antireflection layer)

100 Parts by weight of a multifunctional acrylate (trade name "Viscoat #300", 100% by weight of solid content, manufactured by Osaka organic chemical Co., ltd.), 150 parts by weight of hollow nano silica particles (trade name "THRULYA 5320", 20% by weight of solid content, 75nm in weight average particle diameter), 50 parts by weight of solid nano silica particles (trade name "MEK-2140Z-AC", 30% by weight of solid content, 10nm in weight average particle diameter, manufactured by Nissan chemical Co., ltd.), 12 parts by weight of a fluorine element-containing additive (trade name "KY-1203", 20% by weight of solid content, manufactured by Xin-Yu chemical Co., ltd.), and 3 parts by weight of a photopolymerization initiator (BASF Co., ltd., trade name "OMNIRAD", 100% by weight of solid content) were mixed. To this mixture, a mixed solvent obtained by mixing TBA (t-butanol), MIBK (methyl isobutyl ketone), and PMA (propylene glycol monomethyl ether acetate) in a weight ratio of 60:25:15 was added as a diluent solvent, and the mixture was stirred so that the total solid content became 4% by weight, thereby preparing an antireflective layer-forming coating liquid B.

(Formation of adhesive layer)

A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube and a condenser was charged with a monomer mixture containing 94.9 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid and 0.1 part by weight of 2-hydroxyethyl acrylate. Further, 0.3 parts by weight of dibenzoyl peroxide as a polymerization initiator was added together with ethyl acetate to 100 parts by weight of the monomer mixture, nitrogen was introduced while stirring slowly to replace the inside of the flask with nitrogen, and then the liquid temperature in the flask was kept at 60℃to carry out a polymerization reaction for 7 hours. Next, ethyl acetate was added to the obtained reaction solution, and the solid content concentration was adjusted to 30% by weight, to prepare a solution of an acrylic polymer having a weight average molecular weight (Mw) of 220 ten thousand.

An acrylic pressure-sensitive adhesive was prepared by blending 100 parts by weight of the solid content of the obtained acrylic polymer solution with 0.6 part by weight of trimethylolpropane/toluene diisocyanate adduct (trade name: coronate L, manufactured by Tosoh Co., ltd.) and 0.075 part by weight of a silane coupling agent (trade name: KBM403, manufactured by Xinyue chemical Co., ltd.).

The obtained acrylic adhesive composition was applied to a base film and dried to form an adhesive layer having a thickness of 12 μm and an adhesive layer having a thickness of 15 μm. The surface smoothness was 0.25arcmin for either.

(Production of optical laminate)

The positive C plate was bonded to the λ/4 member (stretched film) via an ultraviolet curable adhesive (thickness after curing 1 μm), to obtain a retardation member.

The protective member (an acrylic film having a hard coat layer and an antireflection layer formed thereon) was bonded to the lambda/4 member side of the obtained retardation member via the pressure-sensitive adhesive layer (thickness: 12 μm). Wherein the acrylic film of the protective member is bonded so as to be positioned on the lambda/4 member side.

Then, the adhesive layer (thickness: 15 μm) was attached to the positive C plate side of the retardation member, to obtain an optical laminate.

Example 2

An optical laminate was obtained in the same manner as in example 1, except that the conditions for forming the adhesive layer were changed, and an adhesive layer having a surface smoothness of 0.4arcmin was formed.

Comparative example 1

An optical laminate was obtained in the same manner as in example 2, except that a TAC film (thickness 60 μm, surface smoothness 0.5 arcmin) was used instead of the acrylic film having a lactone ring structure, and the thickness of the hard coat layer was set to 12 μm to obtain a protective member having a thickness of 72 μm and a surface smoothness of 0.5arcmin on the antireflection layer side.

The optical laminates obtained in examples and comparative examples were evaluated as follows. The evaluation results are shown in table 1.

(1) Smoothness of laminate

The smoothness of the laminate was measured using a phase-shift laser interferometer (product name "DynaFiz" manufactured by Zygo corporation). Specifically, the optical laminate was laminated on a micro slide glass (product name "S200200" manufactured by sonlano industrial co., ltd.) so as not to introduce foreign matter, bubbles, and deformed stripes. Next, in order to remove the influence of the fine bubbles, deaeration by a pressurized deaeration device (autoclave) was performed. The defoaming conditions were set at 50℃and 0.5MPa for 30 minutes. After deaeration, the sample was naturally cooled at room temperature for 30 minutes or more, to obtain a measurement sample.

The measurement sample was placed on a measurement stage with a vibration isolation stage, and the relative displacement in a predetermined region (30 mm phi circle) was measured by using a single wavelength (wavelength 633 nm) laser beam to interfere with a reference device that ensured flatness. For analysis, a value obtained by multiplying an index "Slope magnitude RMS" of an angle obtained by selecting a value of 0.1/mm to 1/mm by 2 times (corresponding to 2σ) was defined as laminate smoothness (unit: arcmin).

(2) Aesthetic appearance

The aesthetic properties (lens transmitted light) of the optical laminate were evaluated using an optical lens (trade name "LA1145" manufactured by Thorabs corporation) and a point light source (model "L8425-01" manufactured by bingo photonics corporation).

Specifically, the optical laminate cut into a circular shape of 45mm phi was laminated on the flat side of the optical lens so as not to introduce foreign matter, bubbles, and deformed stripes to the surface. Next, in order to remove the influence of the fine bubbles, deaeration by a pressurized deaeration device (autoclave) was performed. The defoaming conditions were set at 50℃and 0.5MPa for 30 minutes. After deaeration, the sample was naturally cooled at room temperature for 30 minutes or more, to obtain a measurement sample.

A point light source, an optical lens (measurement sample) and a screen were sequentially provided, and the light of the point light source passing through the optical lens was projected onto the screen, whereby the beauty thereof was evaluated. Wherein the lens is held by a holder at a position where light of the point light source enters from the convex side of the optical lens. The distance from the point light source to the screen was 1050mm, and the distance from the optical lens to the screen was 130mm.

The light passing through the optical lens, which was mapped on the screen by 10 evaluators, was visually observed, and the presence or absence of wrinkles and waviness was determined, whereby the appearance was evaluated. The number of evaluators judged to be wrinkle/ripple free is shown in table 1.

TABLE 1

	Example 1	Example 2	Comparative example 1
				Laminate smoothness (arcmin)	0.58	0.97	1.22
Aesthetic appearance	10/10	7/10	0/10

The present invention is not limited to the above embodiment, and various modifications can be made. For example, the components may be replaced with components substantially identical to those described in the above embodiments, components exhibiting the same operational effects, or components achieving the same purpose.

Industrial applicability

The optical laminate according to the embodiment of the present invention can be used for a display such as VR goggles.

Claims

1. An optical laminate comprising:

Laminated film having substrate and surface treatment layer, and method for producing the same

The phase difference member is provided with a plurality of phase difference grooves,

The base material of the laminated film is disposed adjacent to the phase difference member,

The base material of the laminated film contains a (meth) acrylic resin,

The optical laminate has a laminate smoothness of 1.0arcmin or less.

2. The optical stack according to claim 1, wherein,

The surface smoothness of the base material of the laminated film is 0.7arcmin or less.

3. The optical stack according to claim 1, wherein,

The surface smoothness of the laminated film is 0.5arcmin or less.

4. The optical laminate according to claim 1, which has a laminate smoothness of 0.7arcmin or less.

5. The optical stack according to claim 1, wherein,

The surface treatment layer of the laminated film has an antireflection function.

6. The optical stack according to claim 1, wherein,

The retardation member includes a first retardation layer exhibiting refractive index characteristics of nx > ny ≡nz and satisfying a relationship of Re (450) < Re (550) < Re (650),

Wherein Re (450) represents the in-plane retardation measured at 23℃with light having a wavelength of 450nm, re (550) represents the in-plane retardation measured at 23℃with light having a wavelength of 550nm, and Re (650) represents the in-plane retardation measured at 23℃with light having a wavelength of 650 nm.

7. The optical stack according to claim 1, wherein,

The retardation member includes a second phase difference layer exhibiting refractive index characteristics of nz > nx+.ny.

8. The optical stack according to claim 1, wherein,

The substrate of the laminated film has a transmittance of 20% or less at a wavelength of 400 nm.

9. The optical laminate according to claim 1, which has an in-plane retardation Re (550) of 130nm to 160nm measured at 23 ℃ with light having a wavelength of 550 nm.

10. A lens section for a display system for displaying an image to a user,

The lens section includes:

a second lens unit disposed in front of the reflective polarizing member; and

The optical laminate according to any one of claims 1 to 9, which is disposed on an optical path between the half mirror and the reflective polarizing member.

11. A display method, the method comprising:

a step of passing the light passing through the half mirror and the first lens portion through the optical layered body according to any one of claims 1 to 9;