WO2022041650A1 - 一种保偏光学膜及其制备方法 - Google Patents

一种保偏光学膜及其制备方法 Download PDF

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WO2022041650A1
WO2022041650A1 PCT/CN2021/074198 CN2021074198W WO2022041650A1 WO 2022041650 A1 WO2022041650 A1 WO 2022041650A1 CN 2021074198 W CN2021074198 W CN 2021074198W WO 2022041650 A1 WO2022041650 A1 WO 2022041650A1
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polarization
maintaining
layer
optical film
film
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PCT/CN2021/074198
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English (en)
French (fr)
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唐海江
夏寅
赵国林
缪锴
王小凯
付坤
钟林
李刚
张彦
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宁波激智科技股份有限公司
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Publication of WO2022041650A1 publication Critical patent/WO2022041650A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers

Definitions

  • the invention relates to a polarization-maintaining optical film, in particular to a polarization-maintaining optical film applied to an LCD linearly polarized backlight source and a preparation method thereof.
  • the display of the liquid crystal panel requires a backlight module to provide a light source for it.
  • the LED point light source can be converted into a uniform flat light source.
  • the utilization rate of the light energy of the flat light source is actually very low for the liquid crystal panel.
  • the loss is the largest (about 70%) when passing through the filter, this is because the white light is filtered out of the other two colors to produce RGB monochromatic light, and the second is that the loss is more serious (about 60%) when it first passes through the lower polarizer, This is because the ordinary light source needs to undergo the dichroic absorption process of the PVA layer to form linearly polarized light, and only the linearly polarized light (22) whose polarization direction is parallel to the transmission axis of the polarizer is retained, and the vertical direction (23) is absorbed, as shown in the figure
  • the light emitted by the backlight module (14) is partially polarized light (21), and after the partially polarized light (21) passes through the lower polarizer (13), the linearly polarized light (22) in parallel
  • the linearly polarized light (23) in the direction is absorbed by the lower polarizer (13), and the linearly polarized light in the parallel direction is twisted by the liquid crystal and changes the polarization direction when passing
  • Attenuation position Attenuation cause transmittance remaining light 6 cover surface reflection 90% 9.2% 5 upper polarizer surface reflection 90% 10.3% 4 filter wavelength cutoff, absorption 30% 11.4% 3 liquid crystal layer Polarized light transmission 95% 38% 2 lower polarizer Surface reflection, polarization 40% 40% 1 Area light source Backlight material light distribution conversion / 100% 0 point Light / / /
  • the backlight surface light source can be polarized before entering the lower polarized light and has been converted into linearly polarized light parallel to it, then the transmittance of the lower polarized light to it will be greatly improved, and the utilization rate of the light source opposite to the overall LCD panel will be greatly improved. Helps to improve the brightness of the display and save power and energy.
  • the traditional efficiency enhancement solution is to polarize at the back end, that is, to add a reflective polarizer (RP) (15) with a multi-layer film system to the original backlight structure: this reflective polarizer (15) can fully The polarized P light is transmitted and the S light is reflected; while the S light will be depolarized in the backlight system and re-form partial polarized light; the partially polarized light is repeatedly transmitted through the RP to generate more P light; after many cycles , until the energy is exhausted; and the final increase of P light can increase the utilization rate of light energy by 20-30% compared with the original architecture. As shown in FIG.
  • RP reflective polarizer
  • the light emitted by the backlight module (14) is partially polarized light (21), and the partially polarized light (21) enters the reflective polarizer (15), and the reflective polarizer (15) can
  • the linearly polarized light (22) is transmitted through, and the linearly polarized light (23) in the vertical direction is reflected; while the linearly polarized light (23) in the vertical direction will be depolarized in the backlight system to re-form partial polarized light (21); the parallel direction
  • the linearly polarized light (22) in the parallel direction passes through smoothly, at this time no linearly polarized light (23) in the vertical direction is absorbed, and the linearly polarized light (23) in the parallel direction is absorbed.
  • the liquid crystal panel (12) When passing through the liquid crystal panel (12), the liquid crystal is twisted and the polarization direction is changed, converted into a linearly polarized light in the vertical direction (23) and smoothly transmitted through the upper polarizer (11), and the emitted light is finally a linearly polarized light in the vertical direction (23) ).
  • the reflective polarizer is very expensive due to its complex equipment and process and few supply resources. Therefore, it is necessary to propose new efficiency enhancement schemes.
  • front-end polarizing that is, the backlight module adopts a linearly polarized point light source, emits linearly polarized light from the very beginning, and keeps the direction of the polarized light and the transmission axis of the lower polarizer (13). Consistent. As shown in FIG.
  • the light emitted by the backlight module (14) is linearly polarized light (22) in a parallel direction, and after the linearly polarized light (22) passes through the lower polarizer (13), the linearly polarized light (22) in a parallel direction
  • the linearly polarized light passes through the liquid crystal panel (12)
  • it is twisted by the liquid crystal and changes the polarization direction, converted into linearly polarized light (23) in the vertical direction, and smoothly transmitted through the upper polarizer (11), and the output light is finally Linearly polarized light in the vertical direction (23).
  • the degree of polarization maintenance is very low (completely polarized light is incident, and more or less depolarization will occur after passing through the optical film. , resulting in a decrease in the polarization degree of the outgoing light, resulting in partially polarized light.
  • the ratio of the polarization degree of the outgoing light to the incident light is the polarization maintaining degree.
  • the polarization maintaining degree can also be used as the polarization degree of the outgoing light to indicate), generally between 50 and 70%, the polarization degree of the final surface light source drops sharply, resulting in an obvious depolarization phenomenon, and this part of the polarized light will still be filtered out by the lower polarizer. It is expected that, as shown in Figure 4, after the linearly polarized light (22) in the parallel direction passes through the traditional optical film (3), the outgoing light is partially polarized light (21), and the partially polarized light (21) passes through the lower polarizer (13).
  • the linearly polarized light (22) in the parallel direction passes through smoothly, the linearly polarized light (23) in the vertical direction is absorbed by the lower polarizer (13), and the linearly polarized light in the parallel direction is twisted by the liquid crystal when passing through the liquid crystal panel (12). And change the polarization direction to convert into linearly polarized light (23) in vertical direction and smoothly pass through the upper polarizer (11), and the outgoing light is finally linearly polarized light (23) in vertical direction.
  • the present invention provides a polarization-maintaining optical film and a preparation method thereof.
  • the polarization-maintaining optical film provided by the present invention has a high degree of polarization-maintaining for incident ray polarized light, and reduces the depolarization phenomenon.
  • the present invention adopts the following technical solutions:
  • the present invention provides a polarization-maintaining optical film
  • the polarization-maintaining optical film comprises a polarization-maintaining matrix layer, a first structural layer and/or a second structural layer, the first structural layer is located on the upper surface of the polarization-maintaining matrix layer, and the second structural layer on the lower surface of the polarization-maintaining substrate layer.
  • the polarization-maintaining degree of the polarization-maintaining optical film to the incident line-polarized light is greater than or equal to 80%.
  • the polarized incident light can retain a high degree of polarization, and the degree of polarization-maintaining is greater than or equal to 80%. Thereby, it is ensured that the final height of the polarizer under the LCD is transmitted, and the utilization rate of the backlight source is greatly improved.
  • the optical film in the conventional backlight refers to the existing diffuser film, microlens film, prism film, or inverse prism film.
  • the polarization-maintaining optical film is one of a polarization-maintaining diffusion film, a polarization-maintaining microlens film, a polarization-maintaining prism film, and a polarization-maintaining inverse prism film.
  • the polarization-maintaining optical film provided by the present invention is an improvement on the existing optical film, and the material of the base layer (also called the support layer) of the existing optical film is changed to a material with high polarization-maintaining degree for linearly polarized light.
  • the polarization-maintaining degree of the polarization-maintaining matrix layer is greater than 99%.
  • the material of the polarization-maintaining matrix layer is an optically isotropic transparent polymer.
  • the thickness T of the polarization-maintaining base layer is 25-250 ⁇ m.
  • the material of the polarization-maintaining matrix layer is selected from one or at least two of polymethyl methacrylate (PMMA), polycarbonate (PC), triacetate cellulose (TAC), and cycloolefin polymer (COP). The combination.
  • PMMA polymethyl methacrylate
  • PC polycarbonate
  • TAC triacetate cellulose
  • COP cycloolefin polymer
  • the haze of the polarization-maintaining diffusion film is 60-98%.
  • the first structural layer of the polarization-maintaining diffusion film is an atomized layer
  • the second structural layer does not exist or is both an atomized layer
  • the atomized layer is selected from a particle-free coating or a particle-containing coating.
  • the haze of the first haze layer/second haze layer is 5-98%.
  • the particle-free coating of the polarization-maintaining diffusion film is composed of a transparent polymer resin.
  • the particle-containing coating is composed of transparent polymer resin and transparent polymer particles; the particle diameter of the transparent polymer particles is 1-20 ⁇ m. Further, the particle size of the transparent polymer particles is 1-15 ⁇ m. For example: 1 ⁇ 3 ⁇ m, 3 ⁇ 5 ⁇ m, 5 ⁇ 15 ⁇ m, 8 ⁇ 20 ⁇ m.
  • the haze of the polarization-maintaining microlens film is 60-98%.
  • the first structural layer of the polarization-maintaining microlens film is a microlens array layer; in the microlens array layer, the coordinates of the principal optical axes of three adjacent microlenses are connected to form a regular triangle, or, adjacent The coordinates of the main optical axes of the four microlenses are connected to form a square; the microlenses in the microlens array are closely arranged.
  • the haze of the microlens array layer is 60-98%.
  • the distance D between the main optical axes of adjacent microlenses is 10-50 ⁇ m
  • the height of the microlens is H
  • the aspect ratio is H/W is 0.05 to 0.5.
  • the first structural layer of the polarization-maintaining prism film is a prism layer, and the second structural layer does not exist or is an atomized layer;
  • the prism layer is formed by tiling triangular prism ribs, and the cross-section of the triangular prism ribs is an isosceles triangle , the base of the triangle is 10-100 ⁇ m, the apex angle is 75-105°; the haze of the atomized layer is 0-30%.
  • the bottom surface of the triangular prism rib is located on the upper surface of the polarization-maintaining base layer.
  • the second structural layer of the polarization-maintaining inverse prism film is an inverse prism layer, and the first structural layer does not exist or is an atomized layer;
  • the inverse prism layer is formed by tiling triangular prism ribs, and the cross section of the triangular prism ribs is Isosceles triangle or ordinary triangle, the base width L of the triangle is 10 ⁇ 100 ⁇ m, the vertex angle ⁇ is selected from 40 ⁇ 80°, preferably 60°, and a larger base angle ⁇ is 90°-0.5 ⁇ + ⁇ , ⁇ is 0-10°, when ⁇ is 0°, the cross-section is an isosceles triangle, and when ⁇ is greater than 0°, the cross-section is an ordinary triangle.
  • the haze of the atomized layer is 0-60%.
  • the bottom surface of the triangular prism rib is located on the lower surface of the polarization-maintaining base layer.
  • the material of the atomization layer is selected from one of AR (Acrylic resin, acrylic resin or modified acrylic resin), PMMA, PC or polyurethane (PU).
  • AR is preferably a light curing process
  • PMMA and PC are preferably a hot pressing process
  • PU is preferably a thermal curing process.
  • the refractive index na of the transparent polymer resin is selected from 1.4-1.65.
  • the refractive index nb of the transparent polymer resin is selected from 1.4-1.65.
  • the transparent polymer particles are selected from one or a combination of at least two of PMMA, PBMA (polybutyl methacrylate), PS (polystyrene), PU (polyurethane) and silicone.
  • the microlens array layer is formed of a transparent polymer resin, and the material of the transparent polymer resin is selected from one of AR, PMMA or PC.
  • AR is preferably a photocuring process
  • PMMA and PC are preferably a hot pressing process.
  • the refractive index nc of the transparent polymer resin of the microlens array layer is selected from 1.4-1.65.
  • the prism layer is made of transparent polymer resin, and the material of the transparent polymer resin is selected from one of AR, PMMA or PC.
  • AR is preferably a photocuring process
  • PMMA and PC are preferably a hot pressing process.
  • the refractive index nd of the transparent polymer resin is selected from 1.5 ⁇ 1.65.
  • the inverse prism layer is made of transparent polymer resin, and the material of the transparent polymer resin is selected from one of AR, PMMA or PC.
  • AR is preferably a photocuring process
  • PMMA and PC are preferably a hot pressing process.
  • the refractive index ne of the transparent polymer resin of the prism layer is selected from 1.5-1.65.
  • the first structural layer is an atomization layer DL (Diffusion layer), and the second structural layer does not exist.
  • the thickness T of the base layer is 50-250 ⁇ m (for example, 50 ⁇ m, 100 ⁇ m-250 ⁇ m), and the material of the polarization-maintaining base layer is selected from PC, TAC, PMMA, or COP, optically isotropic, and polarization-maintaining degree>99% , the haze of the polarization-maintaining diffusion film is 98%.
  • the haze of the first atomized layer is 98%, the type of the atomized layer is a particle coating, the transparent polymer resin is selected from PU or AR, and the transparent polymer particles are PMMA, PS, silicone, or PU , the particle size d is 5-15 ⁇ m or 8-20 ⁇ m, and the refractive index na of the transparent polymer resin is 1.4, 1.5 or 1.65.
  • the polarization maintaining degree of the polarization maintaining diffusion film is 81-83% (eg, 81%, 82% or 83%).
  • the first structural layer is an atomization layer DL (Diffusion layer), and the second structural layer does not exist.
  • the thickness T of the base layer is 250 ⁇ m
  • the material of the polarization-maintaining base layer is PC
  • optically isotropic and the polarization-maintaining degree is >99%
  • the haze of the polarization-maintaining diffusion film is 98%.
  • the haze of the first atomized layer is 98%
  • the type of the atomized layer is particle-free coating
  • the transparent polymer resin is PC
  • the refractive index na of the transparent polymer resin is 1.5.
  • the polarization maintaining degree of the polarization maintaining diffusion film is 83%.
  • the first structural layer is an atomized layer
  • the second structural layer is an atomized layer.
  • the thickness T of the base layer is 25-250 ⁇ m (for example, 25 ⁇ m, 50 ⁇ m, 75 ⁇ m, 100 ⁇ m, 125 ⁇ m, 250 ⁇ m)
  • the material of the polarization-maintaining base layer is selected from PC or PMMA, optically isotropic, and polarization maintaining degree>99 %
  • the haze of the polarization-maintaining diffusion film is 60-98% (for example, 60%, 80%, 90%, 95% or 98%).
  • the haze of the first atomized layer is 98%, the type of the atomized layer is a particle coating, the transparent polymer resin is PU or AR, the transparent polymer particles are PMMA, and the particle size d is 5-15 ⁇ m,
  • the refractive index na of the transparent polymer resin is 1.5 or 1.65.
  • the haze of the second atomized layer is 5%, the type of the second atomized layer is a particle coating, the transparent polymer resin is AR, the transparent polymer particles are PMMA, the particle size d is 1-3 ⁇ m, Or 5-15 ⁇ m, and the refractive index na of the transparent polymer resin is 1.5.
  • the first structural layer is an atomized layer
  • the second structural layer is an atomized layer.
  • the thickness T of the base layer is 250 ⁇ m
  • the material of the polarization-maintaining base layer is PC
  • optically isotropic and the polarization-maintaining degree is >99%
  • the haze of the polarization-maintaining diffusion film is 98%.
  • the haze of the first atomized layer is 98%, the type of the atomized layer is a particle coating, the transparent polymer resin is PU or AR, the transparent polymer particles are PMMA, and the particle size d is 5-15 ⁇ m,
  • the refractive index na of the transparent polymer resin is 1.5 or 1.65.
  • the haze of the second atomization layer is 5%, the type of the atomization layer is a particle-free coating, and is composed of a transparent polymer resin AR, and the refractive index nb of the transparent polymer resin is 1.5 or 1.6.
  • the polarization maintaining degree of the polarization maintaining diffusion film is 80%.
  • the present invention provides a polarization-maintaining microlens film, wherein the first structural layer is a microlens array layer ML (Microlens layer), and the second structural layer does not exist.
  • the thickness T of the base layer is 25 ⁇ m-250 ⁇ m (for example, 25 ⁇ m, 50 ⁇ m, 75 ⁇ m, 100 ⁇ m, 125 ⁇ m, 250 ⁇ m), and the material of the polarization-maintaining base layer is selected from PC or PMMA, optically isotropic, and polarization maintaining degree>99 %, the haze of the PM microlens film is 60%-98% (for example, 60%, 70%, 85%, 92%, 96%, 98%).
  • the haze of the microlens array layer is 98%
  • the microlens array layer is formed of a transparent polymer resin AR or PC
  • the transparent polymer resin has a refractive index nc of 1.4-1.65 (for example, 1.4, 1.5, 1.65 ).
  • the distance D between the main optical axes of adjacent microlenses is 10 ⁇ m-50 ⁇ m (for example, 10 ⁇ m, 20 ⁇ m, 35 ⁇ m, 50 ⁇ m)
  • the aspect ratio H/W is 0.05-0.5 (for example, 0.05, 0.1, 0.2, 0.5); the polarization-maintaining degree of the polarization-maintaining microlens is 80%-97% (for example, 80%, 85%, 88%) , 90%, 95%, 97%).
  • the present invention provides a polarization-maintaining microlens film, wherein the first structural layer is a microlens array layer, and the second structural layer is an atomization layer.
  • the thickness T of the base layer is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC
  • is optically isotropic and has a polarization-maintaining degree of >99%
  • the haze of the polarization-maintaining microlens film is 96%.
  • the haze of the microlens array layer is 98%
  • the microlens array layer is composed of a transparent polymer resin AR
  • the refractive index nc of the transparent polymer resin is 1.5.
  • the distance D between the main optical axes of adjacent microlenses is 50 ⁇ m
  • the height of the microlenses is H
  • the aspect ratio H/W is 0.5.
  • the haze of the atomized layer is 5%
  • the type of the atomized layer is a particle-free coating, and is composed of a transparent polymer AR
  • the refractive index nb of the transparent polymer resin is 1.5.
  • the polarization-maintaining degree of the polarization-maintaining microlens film is 85%.
  • the present invention provides a polarization-maintaining microlens film, wherein the first structural layer is a microlens array layer, and the second structural layer is an atomization layer.
  • the thickness T of the base layer is 100 ⁇ m
  • the material of the polarization-maintaining base layer is selected from TAC, PMMA or COP, optically isotropic, and the polarization-maintaining degree is >99%
  • the haze of the polarization-maintaining microlens film is 96 %.
  • the haze of the microlens array layer is 98%
  • the microlens array layer is formed of a transparent polymer resin AR or PMMA
  • the refractive index nc of the transparent polymer resin is 1.5.
  • the distance D between the main optical axes of adjacent microlenses is 50 ⁇ m
  • the height of the microlenses is H
  • the aspect ratio H/W is 0.5.
  • the haze of the atomized layer is 5%
  • the type of the atomized layer is a particle coating, which is composed of transparent polymer resin AR and transparent polymer resin particles PMMA, and the refractive index nb of the transparent polymer resin is 1.5
  • the particle size of the polymer resin particles PMMA is 3-5 ⁇ m.
  • the polarization-maintaining degree of the polarization-maintaining microlens film is 85%.
  • the present invention provides a polarization-maintaining prism film, wherein the first structural layer is a prism layer PL (Prism layer), and the second structural layer does not exist.
  • the thickness T of the base layer is 25 ⁇ m-250 ⁇ m (for example, 25 ⁇ m, 50 ⁇ m, 100 ⁇ m, 125 ⁇ m, 250 ⁇ m), and the material of the polarization-maintaining base layer is selected from PC, TAC, PMMA, or COP, optically isotropic, polarization-maintaining degree>99%
  • the prism layer is formed of a transparent polymer resin AR, PMMA or PC, the transparent polymer resin has a refractive index nd of 1.5-1.65 (eg 1.5, 1.55 or 1.65).
  • the prism layer is formed by tiling triangular prism ribs, the cross section of the triangular prism ribs is an isosceles triangle, the base of the triangle is 10 ⁇ m-100 ⁇ m (for example, 10 ⁇ m, 20 ⁇ m, 50 ⁇ m, 100 ⁇ m), and the top angle is 75°-105 ° (eg 75°, 90°, 105°).
  • the polarization maintaining degree of the polarization maintaining prism film is 98%.
  • the present invention provides a polarization-maintaining prism film, wherein the first structural layer is a prism layer PL (Prism layer), and the second structural layer is an atomization layer.
  • the thickness T of the base layer is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%
  • the prism layer is composed of a transparent polymer resin AR, and the transparent polymer
  • the refractive index nd of the tree is 1.55.
  • the prism layer is formed by tiling triangular prism ribs, the cross section of the triangular prism ribs is an isosceles triangle, the base of the triangle is 50 ⁇ m, and the vertex angle is 90°.
  • the haze of the atomized layer is 5%-30%, the type of the atomized layer is a particle-free coating, and is composed of a transparent polymer AR, and the refractive index nb of the transparent polymer resin is 1.5.
  • the polarization maintaining degree of the polarization maintaining prism film is 95%-97%.
  • the present invention provides a polarization-maintaining reverse prism film, wherein the first structural layer does not exist, and the second structural layer is a reverse prism layer RL (Rverse-prism layer).
  • the thickness T of the base layer is 25 ⁇ m-250 ⁇ m (for example, 25 ⁇ m, 50 ⁇ m, 75 ⁇ m, 100 ⁇ m, 125 ⁇ m, 250 ⁇ m), and the material of the polarization-maintaining base layer is selected from PC, TAC, PMMA, or COP, optically isotropic,
  • the polarization maintaining degree is >99%
  • the inverse prism layer is formed of transparent polymer resin AR, PC or PMMA, and the transparent polymer tree has a refractive index nd of 1.5-1.65 (eg 1.5, 1.55 or 1.65).
  • the inverse prism layer is formed by tiling triangular prism ribs, the cross section of the triangular prism rib is an isosceles triangle or a common triangle, the base width L of the triangle is 10 ⁇ m-100 ⁇ m (for example, 10 ⁇ m, 20 ⁇ m, 50 ⁇ m, 100 ⁇ m),
  • the angle ⁇ is selected from 40°-90° (eg, 40°, 60°, 80°, or 90°), wherein a larger base angle ⁇ is 90°-0.5 ⁇ + ⁇ , and the declination angle ⁇ is 0°-10 °.
  • the polarization-maintaining degree of the polarization-maintaining inverse prism film is 98%.
  • the present invention provides a polarization-maintaining inverse prism film, wherein the first structural layer is an atomization layer, and the second structural layer is a reverse-prism layer RL (Rverse-prism layer).
  • the thickness T of the base layer is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%
  • the inverse prism layer is composed of transparent polymer resin AR, and the transparent
  • the refractive index nd of the polymer tree is 1.55.
  • the inverse prism layer is formed by tiling triangular prism ribs, the cross section of the triangular prism ribs is an isosceles triangle, the base width L of the triangle is 50 ⁇ m, and the vertex angle ⁇ is selected from 60°, and one of the larger base angle ⁇ is is 90°-0.5 ⁇ + ⁇ , and the declination angle ⁇ is 0°.
  • the haze of the atomized layer is 30%-60%, the type of the atomized layer is a particle-free coating, and is composed of a transparent polymer AR, and the refractive index nb of the transparent polymer resin is 1.5.
  • the polarization maintaining degree of the polarization maintaining prism film is 90%-95%.
  • the present invention also provides a method for preparing the polarization-maintaining optical film.
  • the transparent polymer resin or transparent polymer containing transparent polymer particles is formed by coating, micro-replication or hot pressing on the front/back of the polarization-maintaining substrate layer in sequence.
  • the resin prepares the first structural layer or the second structural layer respectively; wherein, the coating is suitable for the preparation of the atomized layer of the polarization-maintaining diffusion film, and the micro-replication and hot pressing are suitable for the polarization-maintaining diffusion film, the polarization-maintaining microlens film, the polarization-maintaining Preparation of polarizing prism film, atomized layer, microlens layer and prism layer of polarization-maintaining inverse prism film.
  • the preparation method of the polarization-maintaining optical film comprises the following steps:
  • the preparation method of the polarization-maintaining optical film comprises the following steps:
  • the first structural layer (convex) is micro-replicated or hot-pressed on the front side using the roller 1 to obtain a polarization-maintaining optical film containing the first structural layer;
  • the preparation method of the polarization-maintaining optical film comprises the following steps:
  • the preparation method of the polarization-maintaining optical film comprises the following steps:
  • the second structural layer is micro-replicated or hot-pressed on the back using the roller 2 to obtain a polarization-maintaining optical film containing the second structural layer;
  • the preparation method of the polarization-maintaining optical film comprises the following steps:
  • step (2) coating the back of the semi-finished product obtained in step (1) with a second structure layer to obtain a polarization-maintaining optical film containing both the first structure layer and the second structure layer;
  • the preparation method of the polarization-maintaining optical film comprises the following steps:
  • processing methods of the first structural layer and the second structural layer should be selected according to the type of the structural layer and the type of material, which is not preferred in the present invention.
  • the preparation method of the polarization-maintaining optical film provided by the present invention is suitable for the production of sheets and rolls.
  • the polarization-maintaining optical film can be used as an optical functional material in an optical system requiring polarization-maintaining. It is especially suitable for LCD linearly polarized backlight. When the linearly polarized light in the backlight passes through the polarization-maintaining optical film, it can retain a high degree of polarization, ensuring the final high transmission of the polarizer under the LCD, and greatly improving the utilization of the backlight. .
  • the polarization-maintaining optical film provided by the present invention can be designed in combination with a linearly polarized point light source, so as to facilitate the generation of a linearly polarized backlight source, without the need for complex and expensive reflective polarizers, which can ensure that the LCD under the
  • the high transmittance of the polarizer improves the utilization rate of the backlight source, and the efficiency enhancement solution is more cost-effective and has obvious advantages.
  • FIG 1 shows the reasons for the low utilization of LCD light energy
  • Figure 2 is a schematic diagram of a traditional LCD efficiency enhancement scheme
  • FIG. 3 is a schematic diagram of a new LCD efficiency enhancement scheme
  • Fig. 4 is a schematic diagram of the depolarization result of the traditional optical film in the novel synergistic optical path
  • FIG. 5 is a schematic diagram of the polarization-maintaining effect of the polarization-maintaining optical film provided by the present invention.
  • Fig. 6 is the test method schematic diagram of polarization maintaining degree
  • FIG. 7 is a schematic diagram of the basic structure of the polarization-maintaining optical film.
  • 21 Partially polarized light
  • 22 Linearly polarized light in parallel directions (relative to the transmittance axis of the lower polarizer or paper)
  • 23 Linearly polarized light in the vertical direction (relative to the transmittance axis of the lower polarizer or paper);
  • 50 polarization-maintaining matrix layer
  • 51 first structural layer
  • 52 second structural layer
  • 60 Diaphragm to be tested; 61: Polarizer; 62: Parallel analyzer (parallel to the polarizer, used to detect Imax); 63: Vertical analyzer (perpendicular to the polarizer, to detect Imin).
  • the present invention provides a polarization-maintaining optical film (4), the polarization-maintaining optical film (4) is used to replace the traditional optical film (3) in FIG. 4, as shown in FIG. 5, the linearly polarized light (22) in the horizontal direction After passing through the polarization-maintaining optical film (4) provided by the present invention, the outgoing light remains as the linearly polarized light (22) in the horizontal direction.
  • the properties of the polarization-maintaining optical films provided by the present invention were evaluated in the following manner.
  • the analyzer As shown in FIG. 6, place the film to be tested (60) above the polarizer (polarizer) (61), and below the parallel analyzer (polarizer) 62 or the vertical analyzer (polarizer) 63 , measure the intensity of the outgoing light.
  • the analyzer When the angle of the analyzer is parallel to the linear polarization, the analyzer is called a parallel analyzer, and the light intensity is recorded as Imax.
  • the analyzer When the angle of the analyzer is perpendicular to the linear polarization, the analyzer is called a vertical analyzer.
  • the present invention provides a polarization-maintaining optical film
  • the polarization-maintaining optical film includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52
  • the first structural layer is located in the polarization-maintaining base layer 50 on the upper surface
  • the second structure layer is located on the lower surface of the polarization-maintaining base layer 50 .
  • the present invention provides a polarization-maintaining optical film, as shown in FIG. 7 , the polarization-maintaining optical film is a polarization-maintaining diffusion film, the first structure layer 51 is a fogging layer DL (Diffusion layer), and the second structure Layer 52 does not exist.
  • the thickness T of the base layer 50 is 250 ⁇ m, the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%, and the haze of the polarization-maintaining diffusion film is 98%.
  • the haze of the first atomization layer is 98%
  • the type of the atomization layer is a particle coating, which is composed of transparent polymer resin PU and transparent polymer particles PMMA, and the particle size d is 5-15 ⁇ m.
  • the refractive index na of the transparent polymer resin was 1.5.
  • the polarization-maintaining degree of the polarization-maintaining diffusion film is 82%.
  • the polarization-maintaining optical film provided by the present invention includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52 .
  • the first structural layer is located on the upper surface of the base layer 50
  • the second structural layer is located on the upper surface of the base layer 50 .
  • the polarization-maintaining optical film is a polarization-maintaining diffusion film
  • the first structure layer 51 is an atomization layer
  • the second structure layer 52 is an atomization layer.
  • the thickness T of the base layer 50 is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%
  • the haze of the polarization-maintaining diffusion film is 98%.
  • the haze of the first atomization layer is 98%
  • the type of the atomization layer is a particle coating, which is composed of transparent polymer resin PU and transparent polymer particles PMMA, and the particle size d is 5-15 ⁇ m.
  • the refractive index na of the transparent polymer resin was 1.5.
  • the haze of the second atomization layer is 5%, the type of the atomization layer is a particle-free coating, and is composed of a transparent polymer resin AR, and the refractive index nb of the transparent polymer resin is 1.5.
  • the polarization maintaining degree of the polarization maintaining diffusion film is 80%.
  • T is the thickness of the polarization-maintaining substrate layer.
  • Table 1 shows examples of polarization-maintaining diffusion films matched with different materials and design parameters. It can be found that when the material of the substrate layer is the polarization-maintaining substrate such as PC, PMMA, TAC, COP, the polarization-maintaining degree of the prepared polarization-maintaining diffusion film is all greater than 80%, and the thickness T has little effect. When the haze of the atomization layer decreases, the polarization maintaining degree will increase, but the type of atomization layer, resin and particle material have little effect on it. When the second structural layer is an atomized layer with low haze, it can have anti-sticking and anti-scratch effects, and has little effect on optics.
  • the material of the substrate layer is the polarization-maintaining substrate such as PC, PMMA, TAC, COP, the polarization-maintaining degree of the prepared polarization-maintaining diffusion film is all greater than 80%, and the thickness T
  • the polarization-maintaining optical film provided by the present invention includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52 .
  • the first structural layer is located on the upper surface of the base layer 50
  • the second structural layer is located on the upper surface of the base layer 50 .
  • the polarization-maintaining optical film is a polarization-maintaining microlens film
  • the first structure layer 51 is a microlens array layer ML (Microlens layer)
  • the second structure layer 52 does not exist.
  • the thickness T of the base layer 50 is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, is optically isotropic, and has a polarization-maintaining degree of >99%
  • the haze of the polarization-maintaining microlens film is 96%.
  • the haze of the microlens array layer was 98%
  • the microlens array layer was formed of a transparent polymer resin AR
  • the refractive index nc of the transparent polymer resin was 1.5.
  • the distance D between the main optical axes of adjacent microlenses is 50 ⁇ m
  • the height of the microlens is H
  • the aspect ratio H/W is 0.5
  • the microlenses are hemispherical; the polarization-maintaining degree of the polarization-maintaining microlenses is 85%.
  • the polarization-maintaining optical film provided by the present invention includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52 .
  • the first structural layer is located on the upper surface of the base layer 50
  • the second structural layer is located on the upper surface of the base layer 50 .
  • the polarization-maintaining optical film is a polarization-maintaining microlens film
  • the first structure layer 51 is a microlens array layer
  • the second structure layer 52 is an atomization layer.
  • the thickness T of the base layer 50 is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC
  • is optically isotropic and has a polarization-maintaining degree of >99%
  • the haze of the polarization-maintaining microlens film is 96%.
  • the haze of the microlens array layer is 98%
  • the microlens array layer is composed of a transparent polymer resin AR
  • the refractive index nc of the transparent polymer resin is 1.5.
  • the haze of the atomized layer is 5%, the type of the atomized layer is a particle-free coating, and is composed of a transparent polymer AR, and the refractive index nb of the transparent polymer resin is 1.5.
  • the polarization-maintaining degree of the polarization-maintaining microlens film is 85%.
  • T is the thickness of the base layer
  • D is the distance between the main optical axes of adjacent microlenses
  • W is the width of the microlens
  • H is the height of the microlens
  • H/W is the aspect ratio
  • Table 2 shows examples of polarization-maintaining microlens films matched with different materials and design parameters. It can be found that when the material of the substrate layer is the polarization-maintaining substrate such as PC, PMMA, TAC, and COP, the polarization-maintaining degree of the prepared polarization-maintaining microlens film is all greater than 80%, and the thickness T has little effect. When the haze of the microlens layer decreases, the polarization-maintaining degree will increase, and when the refractive index of the transparent polymer decreases, or the aspect ratio decreases, the haze will also decrease, and the polarization-maintaining degree will also increase. Big. When the second structural layer is an atomized layer with low haze, it can have anti-sticking and anti-scratch effects, and has little effect on optics.
  • the second structural layer is an atomized layer with low haze, it can have anti-sticking and anti
  • the polarization-maintaining optical film provided by the present invention includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52 .
  • the first structural layer is located on the upper surface of the base layer 50
  • the second structural layer is located on the upper surface of the base layer 50 .
  • the polarization-maintaining optical film is a polarization-maintaining prism film
  • the first structural layer 51 is a prism layer PL (Prism layer)
  • the second structural layer 52 does not exist.
  • the thickness T of the base layer 50 is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%
  • the prism layer is made of transparent polymer resin AR, and the transparent
  • the refractive index nd of the polymer resin was 1.55.
  • the prism layer is formed by tiling triangular prism ribs, the cross section of the triangular prism ribs is an isosceles triangle, the base of the triangle is 50 ⁇ m, and the vertex angle is 90°.
  • the polarization maintaining degree of the polarization maintaining prism film is 98%.
  • the polarization-maintaining optical film provided by the present invention includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52 .
  • the first structural layer is located on the upper surface of the base layer 50
  • the second structural layer is located on the upper surface of the base layer 50 .
  • the polarization-maintaining optical film is a polarization-maintaining prism film
  • the first structure layer 51 is a prism layer PL (Prism layer)
  • the second structure layer 52 is an atomization layer.
  • the thickness T of the base layer 50 is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%
  • the prism layer is made of transparent polymer resin AR, and the transparent
  • the refractive index nd of the polymer resin was 1.55.
  • the prism layer is formed by tiling triangular prism ribs, the cross section of the triangular prism ribs is an isosceles triangle, the base of the triangle is 50 ⁇ m, and the vertex angle is 90°.
  • the haze of the atomized layer is 5%, the type of the atomized layer is a particle-free coating, and is composed of a transparent polymer AR, and the refractive index nb of the transparent polymer resin is 1.5.
  • the polarization maintaining degree of the polarization maintaining prism film is 97%.
  • T is the thickness of the base layer.
  • Table 3 shows examples of polarization-maintaining prism films matched with different materials and design parameters. It can be found that when the material of the substrate layer is the polarization-maintaining substrate such as PC, PMMA, TAC, COP, the polarization-maintaining degree of the prepared polarization-maintaining prism film is all greater than 80%, and the thickness T has little effect. When the material, refractive index, bottom edge, and top angle of the prism layer are changed, the polarization-maintaining degree is basically unaffected. When the second structural layer is an atomized layer, it can play an anti-sticking and anti-scratch effect, and when the haze increases, the polarization maintaining degree decreases slightly.
  • the material of the substrate layer is the polarization-maintaining substrate such as PC, PMMA, TAC, COP, the polarization-maintaining degree of the prepared polarization-maintaining prism film is all greater than
  • the polarization-maintaining optical film provided by the present invention includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52 .
  • the first structural layer is located on the upper surface of the base layer 50
  • the second structural layer is located on the upper surface of the base layer 50 .
  • the polarization-maintaining optical film is a polarization-maintaining reverse prism film
  • the first structural layer 51 does not exist
  • the second structural layer 52 is a reverse-prism layer RL (Rverse-prism layer).
  • the thickness T of the base layer 50 is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%
  • the inverse prism layer is made of transparent polymer resin AR, and the The refractive index nd of the transparent polymer resin was 1.55.
  • the inverse prism layer is formed by tiling triangular prism ribs.
  • the cross section of the triangular prism ribs is an isosceles triangle or a common triangle.
  • the base angle ⁇ is 90°-0.5 ⁇ + ⁇ , and the declination angle ⁇ is 0°.
  • the polarization-maintaining degree of the polarization-maintaining inverse prism film is 98%.
  • the polarization-maintaining optical film provided by the present invention includes a first structural layer 51 , a polarization-maintaining base layer 50 and a second structural layer 52 .
  • the first structural layer is located on the upper surface of the base layer 50
  • the second structural layer is located on the upper surface of the base layer 50 .
  • the polarization-maintaining optical film is a polarization-maintaining reverse prism film
  • the first structural layer 51 is an atomization layer
  • the second structural layer 52 is a reverse-prism layer RL (Rverse-prism layer).
  • the thickness T of the base layer 50 is 250 ⁇ m
  • the material of the polarization-maintaining base layer is selected from PC, optically isotropic, and the polarization-maintaining degree is >99%
  • the inverse prism layer is made of transparent polymer resin AR, and the The refractive index nd of the transparent polymer resin was 1.55.
  • the inverse prism layer is formed by tiling triangular prism ribs, the cross section of the triangular prism ribs is an isosceles triangle, the base width L of the triangle is 50 ⁇ m, and the vertex angle ⁇ is selected from 60°, and one of the larger base angle ⁇ is is 90°-0.5 ⁇ + ⁇ , and the declination angle ⁇ is 0°.
  • the haze of the atomization layer is 30%, the type of the atomization layer is a particle-free coating, and is composed of a transparent polymer AR, and the refractive index nb of the transparent polymer resin is 1.5.
  • the polarization maintaining degree of the polarization maintaining prism film is 95%.
  • T is the thickness of the base layer.

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Abstract

一种应用于LCD线偏振背光源的保偏光学膜（4）及其制备方法，保偏光学膜（4）包括保偏基体层（50）、第一结构层（51）和/或第二结构层（52），第一结构层（51）位于基体层（50）上表面，第二结构层（52）位于基体层（50）下表面。当LCD背光中的线偏振光通过保偏光学膜（4）时可以保留较高入射光偏振度，保偏度大于80％，确保最终对LCD下偏光片的高度透过，提高背光源的利用率,解决了传统背光中光学膜在偏振光源增效方案中会产生退偏的问题。

Description

一种保偏光学膜及其制备方法 技术领域
本发明涉及一种保偏光学膜，尤其涉及一种应用于LCD线偏振背光源的保偏光学膜及其制备方法。
背景技术
在传统的液晶显示领域(LCD)，液晶面板的显示需要背光模组为其提供光源，通过背光模组中各类光学薄膜、导光板可以将LED点光源转化成均匀的平面光源。然而，该平面光源的光能对于液晶面板而言，实际上利用率非常低。
其中一个原因是液晶面板的下偏光片(13)的透过率仅为40％(如表1所示)。由于点光源到面光源的转化效率因背光设计(直下式or侧入式)不同而差异较大，本文以面光源为100％基准来探讨传统液晶显示面板对背光源的光能衰减过程。可以看到，通过滤光片时损失最多(约70％)，这是因为白光被滤掉其他两色产生RGB单色光，其次就是最初通过下偏光片时损失比较严重(约60％)，这是因为普通光源形成线偏光需要经历PVA层的二向色吸收过程，仅保留偏振方向与偏光片透光轴平行的线偏振光(22)，垂直方向(23)的均被吸收，如图1所示，背光模组(14)发出的光为部分偏振光(21)，部分偏振光(21)经过下偏光片(13)后，平行方向的线偏振光(22)顺利透过，垂直方向的线偏振光(23)被下偏光片(13)吸收，平行方向的线偏振光通过液晶面板(12)时被液晶扭转并改变偏振方向，转变为垂直方向的线偏振光(23)并从上偏光片(11)顺利透过，出射光最终为垂直方向的线偏振光(23)。
表1传统液晶显示面板对背光源的光能衰减过程
考察顺序 衰减位置 衰减原因 透过率 光能剩余
6 盖板 表面反射 90％ 9.2％
5 上偏光片 表面反射 90％ 10.3％
4 滤光片 波长截止、吸收 30％ 11.4％
3 液晶层 偏振光透过 95％ 38％
2 下偏光片 表面反射、起偏 40％ 40％
1 面光源 背光材料光分布转化 / 100％
0 点光源 / / /
如果能使背光面光源在进入下偏光前起偏，已经转化为与其平行的线偏振光，那么就大大提高了下偏光对其的透过率，整体液晶面板对面光源的利用率将大幅提升，有助于显示器亮度提升，省电节能。
传统增效方案是在后端起偏，即在原始背光架构上增加一张采用多层膜系设计的反射型偏光片(RP)(15)：这种反射型偏光片(15)能使完全偏振的P光透过、S光反射；而S光在背光系统中会发射退偏振，重新形成部分偏振光；部分偏振光反复从RP透过，以产生更多的P光；经过多次循环，直至能量耗尽；而最终增加的P光可让光能利用率相比原始架构提升20～30％。如图2所示，背光模组(14)发出的光为部分偏振光(21)，部分偏振光(21)进入反射型偏光片(15)，反射型偏光片(15)能使平行方向的线偏振光(22)透过、垂直方向的线偏振光(23)反射；而垂直方向的线偏振光(23)在背光系统中会发生退偏振，重新形成部分偏振光(21)；平行方向的线偏振光(22)经过下偏光片(13)后，平行方向的线偏振光(22)顺利透过，此时没有垂直方向的线偏振光(23)被吸收，平行方向的线偏振光通过液晶面板(12)时被液晶扭转并改变偏振方向，转变为垂直方向的线偏振光(23)并从上偏光片(11)顺利透过，出射光最终为垂直方向的线偏振光(23)。
然而，反射型偏光片因其设备、工艺复杂，且供应资源少，价格非常昂贵。因此，有必要提出新的增效方案。
另一种比较可行的方案是前端起偏，即让背光模组采用线偏点光源，从最开始就发出线偏振光，并使偏振光的方向与下偏光片(13)的透光轴保持一致。如图3所示，背光模组(14)发出的光为平行方向的线偏振光(22)，该线偏振(22)经过下偏光片(13)后，平行方向的线偏振光(22)顺利透过，该线偏振光通过液晶面板(12)时被液晶扭转并改变偏振方向，转变为垂直方向的线偏振光(23)并从上偏光片(11)顺利透过，出射光最终为垂直方向的线偏振光(23)。然而，这种线偏点光源在转化成面光源的过程中，因传统光学膜具有光学各向异性，保偏度很低(完全偏振光入射，经过光学膜会发生或多或少的退偏振，导致出射光偏振度下降，产生部分偏振光，该出射光与入射光的偏振度之比即保偏度，由于入射光的偏振度为1，因此保偏度也可以用出射光的偏振度来表示)，一般在50～70％之间，最终面光源的偏振度急剧下降，产生明显的退偏现象，而这种部分偏振光仍会被下偏光片滤掉很大一部分，达不到增效预期，如图4所示，平行方向的线偏振光(22)经过传统光学膜(3)后，出射光线为部分偏振光(21)，部分偏振光(21)经过下偏光片(13)后，平行方向的线偏振光(22)顺利透过，垂直方向的线偏振光(23)被下偏光片(13)吸收，平行方向的线偏振光通过液晶面板(12)时被液晶扭转并改变偏振方向，转变为垂直方向的线偏振光(23)并从上偏光片(11)顺利透过，出射光最终为垂直方向的 线偏振光(23)。
发明内容
为了解决传统背光中光学膜在偏振光源增效方案中会产生严重退偏现象的问题，本发明提供一种保偏光学膜及其制备方法。本发明提供的保偏光学膜对入射线偏振光具有较高保偏度，减轻了退偏现象。
为了解决上述技术问题，本发明采用下述技术方案：
本发明提供一种保偏光学膜，所述保偏光学膜包括保偏基体层、第一结构层和/或第二结构层，第一结构层位于保偏基体层上表面，第二结构层位于保偏基体层下表面。
当线偏振光通过该保偏光学膜时，该保偏光学膜对入射线偏振光的保偏度大于或等于80％。
进一步的，当LCD背光中的线偏振光通过该保偏光学膜时，偏振入射光可以保留较高偏振度，保偏度大于或等于80％。从而确保最终对LCD下偏光片的高度透过，大大提高背光源的利用率。
传统背光中的光学膜指现有的扩散膜、微透镜膜、棱镜膜、或逆棱镜膜。
所述保偏光学膜为保偏扩散膜、保偏微透镜膜、保偏棱镜膜、保偏逆棱镜膜中的一种。
本发明提供的保偏光学膜是对现有光学膜的改进，将现有光学膜的基体层(也称支撑层)的材质改为对线偏振光具有高保偏度的材质。
所述保偏基体层的保偏度大于99％。
所述保偏基体层的材质为光学各向同性的透明聚合物。
所述保偏基体层的厚度T为25～250μm。
所述保偏基体层的材质选自聚甲基丙烯酸甲酯(PMMA)、聚碳酸酯(PC)、三醋酸纤维素(TAC)、环烯烃聚合物(COP)中的一种或至少两种的组合。
所述保偏扩散膜的雾度为60～98％。
所述保偏扩散膜的第一结构层为雾化层，第二结构层不存在或同为雾化层，雾化层选自无粒子涂层或有粒子涂层。
所述第一雾化层/第二雾化层的雾度为5～98％。
所述保偏扩散膜的无粒子涂层由透明聚合物树脂构成。所述有粒子涂层由透明聚合物树脂和透明聚合物粒子构成；透明聚合物粒子的粒径为1～20μm。进一步的，透明聚合物粒子的粒径为1～15μm。例如：1～3μm，3～5μm，5～15μm，8～20μm。
所述保偏微透镜膜的雾度为60～98％。
所述保偏微透镜膜的第一结构层为微透镜阵列层；在所述微透镜阵列层中，相邻的三个微透镜的主光轴的坐标相连形成正三角形，或者，相邻的四个微透镜的主光轴的坐标相连形成正方形；所述微透镜阵列中的微透镜紧密排列。
所述微透镜阵列层的雾度为60～98％。
在所述微透镜阵列层中，相邻微透镜的主光轴的间距D为10～50μm，微透镜的宽度为W(W＝D)，微透镜的高度为H，高宽比H/W为0.05～0.5。
所述保偏棱镜膜的第一结构层为棱镜层，第二结构层不存在或为雾化层；所述棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形，三角形的底边为10～100μm，顶角为75～105°；所述雾化层的雾度为0～30％。三棱镜肋的底面位于保偏基体层的上表面。
所述保偏逆棱镜膜的第二结构层为逆棱镜层，第一结构层不存在或为雾化层；所述逆棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形或普通三角形，三角形的底边宽度L为10～100μm，顶角θ选自40～80°，优选为60°，其中一个较大的底角α为90°-0.5θ+γ，γ为0～10°，当γ为0°时，横截面为等腰三角形，当γ大于0°时，横截面为普通三角形。所述雾化层的雾度为0～60％。三棱镜肋的底面位于保偏基体层的下表面。
所述雾化层的材质选自AR(Acrylic resin，丙烯酸树脂或改性丙烯酸树脂)、PMMA、PC或聚氨酯(PU)中的一种。AR优选为光固化制程，PMMA、PC优选为热压制程，PU优选为热固化制程。
当雾化层为有粒子涂层时，所述透明聚合物树脂的折射率na选自1.4～1.65。当雾化层为无粒子涂层时，所述透明聚合物树脂的折射率nb选自1.4～1.65。
所述透明聚合物粒子选自PMMA、PBMA(聚甲基丙烯酸丁酯)、PS(聚苯乙烯)、PU(聚氨酯)和有机硅中的一种或至少两种的组合。
所述微透镜阵列层由透明聚合物树脂形成，所述透明聚合物树脂的材质选自AR、PMMA或PC中的一种。AR优选为光固化制程，PMMA、PC优选为热压制程。所述微透镜阵列层的透明聚合物树脂的折射率nc选自1.4～1.65。
所述棱镜层由透明聚合物树脂构成，所述透明聚合物树脂的材质选自AR、PMMA或PC中的一种。AR优选为光固化制程，PMMA、PC优选为热压制程。所述透明聚合物树脂的折射率nd选自1.5～1.65。
所述逆棱镜层由透明聚合物树脂构成，所述透明聚合物树脂的材质选自AR、PMMA或PC中的一种。AR优选为光固化制程，PMMA、PC优选为热压制程。所述棱镜层的透明聚合物树脂的折射率ne选自1.5～1.65。
进一步的，本发明提供的保偏扩散膜，所述第一结构层为雾化层DL(Diffusion layer)， 所述第二结构层不存在。所述基体层的厚度T为50-250μm(例如50μm、100μm-250μm)，所述保偏基体层的材质选自PC、TAC、PMMA、或COP，光学各向同性，保偏度>99％，所述保偏扩散膜的雾度为98％。所述第一雾化层的雾度为98％，所述雾化层种类为有粒子涂层，透明聚合物树脂选自PU或AR，透明聚合物粒子为PMMA、PS、有机硅、或PU，粒径d为5～15μm或8-20μm，所述透明聚合物树脂的折射率na为1.4、1.5或1.65。所述保偏扩散膜的保偏度为81-83％(例如81％、82％或83％)。
本发明提供的保偏扩散膜，所述第一结构层为雾化层DL(Diffusion layer)，所述第二结构层不存在。所述基体层的厚度T为250μm，所述保偏基体层的材质为PC，光学各向同性，保偏度>99％，所述保偏扩散膜的雾度为98％。所述第一雾化层的雾度为98％，所述雾化层种类为无粒子涂层，透明聚合物树脂为PC，所述透明聚合物树脂的折射率na为1.5。所述保偏扩散膜的保偏度为83％。
本发明提供的保偏扩散膜，所述第一结构层为雾化层，所述第二结构层为雾化层。所述基体层的厚度T为25-250μm(例如25μm，50μm，75μm，100μm，125μm，250μm)，所述保偏基体层的材质选自PC或PMMA，光学各向同性，保偏度>99％，所述保偏扩散膜的雾度为60-98％(例如60％、80％、90％、95％或98％)。所述第一雾化层的雾度为98％，所述雾化层种类为有粒子涂层，透明聚合物树脂为PU或AR，透明聚合物粒子为PMMA，粒径d为5～15μm，所述透明聚合物树脂的折射率na为1.5或1.65。所述第二雾化层的雾度为5％，所述第二雾化层种类为有粒子涂层，透明聚合物树脂为AR，透明聚合物粒子为PMMA，粒径d为1～3μm，或5～15μm，所述透明聚合物树脂的折射率na为1.5。
本发明提供的保偏扩散膜，所述第一结构层为雾化层，所述第二结构层为雾化层。所述基体层的厚度T为250μm，所述保偏基体层的材质为PC，光学各向同性，保偏度>99％，所述保偏扩散膜的雾度为98％。所述第一雾化层的雾度为98％，所述雾化层种类为有粒子涂层，透明聚合物树脂为PU或AR，透明聚合物粒子为PMMA，粒径d为5～15μm，所述透明聚合物树脂的折射率na为1.5或1.65。所述第二雾化层的雾度为5％，所述雾化层种类为无粒子涂层，由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nb为1.5或1.6。所述保偏扩散膜的保偏度为80％。
进一步的，本发明提供一种保偏微透镜膜，所述第一结构层为微透镜阵列层ML(Microlens layer)，所述第二结构层不存在。所述基体层的厚度T为25μm-250μm(例如25μm，50μm，75μm，100μm，125μm，250μm)，所述保偏基体层的材质选自PC或PMMA，光学各向同性，保偏度>99％，所述保偏微透镜膜的雾度为60％-98％(例如60％、70％、85％、92％、96％、98％)。所述微透镜阵列层的雾度为98％，所述微透镜阵列层由透明聚 合物树脂AR或PC形成，所述透明聚合物树脂的折射率nc为1.4-1.65(例如1.4、1.5、1.65)。所述微透镜阵列层中，相邻微透镜的主光轴的间距D为10μm-50μm(例如10μm、20μm、35μm、50μm)，微透镜的宽度为W(W＝D)，微透镜的高度为H，高宽比H/W为0.05-0.5(例如0.05、0.1、0.2、0.5)；所述保偏微透镜的保偏度为80％-97％(例如80％、85％、88％、90％、95％、97％)。
本发明提供一种保偏微透镜膜，所述第一结构层为微透镜阵列层，所述第二结构层为雾化层。所述基体层的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述保偏微透镜膜的雾度为96％。所述微透镜阵列层的雾度为98％，所述微透镜阵列层由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nc为1.5。所述微透镜阵列层中，相邻微透镜的主光轴的间距D为50μm，微透镜的宽度为W(W＝D)，微透镜的高度为H，高宽比H/W为0.5。所述雾化层的雾度为5％，所述雾化层种类为无粒子涂层，由透明聚合物AR构成，所述透明聚合物树脂的折射率nb为1.5。所述保偏微透镜膜保偏度为85％。
本发明提供一种保偏微透镜膜，所述第一结构层为微透镜阵列层，所述第二结构层为雾化层。所述基体层的厚度T为100μm，所述保偏基体层的材质选自TAC、PMMA或COP，光学各向同性，保偏度>99％，所述保偏微透镜膜的雾度为96％。所述微透镜阵列层的雾度为98％，所述微透镜阵列层由透明聚合物树脂AR或PMMA形成，所述透明聚合物树脂的折射率nc为1.5。所述微透镜阵列层中，相邻微透镜的主光轴的间距D为50μm，微透镜的宽度为W(W＝D)，微透镜的高度为H，高宽比H/W为0.5。所述雾化层的雾度为5％，所述雾化层种类为有粒子涂层，由透明聚合物树脂AR和透明聚合物树脂粒子PMMA构成，所述透明聚合物树脂的折射率nb为1.5，所述聚合物树脂粒子PMMA的粒径为3-5μm。所述保偏微透镜膜保偏度为85％。
进一步的，本发明提供一种保偏棱镜膜，所述第一结构层为棱镜层PL(Prism layer)，所述第二结构层不存在。所述基体层的厚度T为25μm-250μm(例如25μm，50μm，100μm，125μm，250μm)，所述保偏基体层的材质选自PC、TAC、PMMA、或COP，光学各向同性，保偏度>99％，所述棱镜层由透明聚合物树脂AR、PMMA或PC形成，所述透明聚合物树脂的折射率nd为1.5-1.65(例如1.5、1.55或1.65)。所述棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形，三角形的底边为10μm-100μm(例如10μm、20μm、50μm、100μm)，顶角为75°-105°(例如75°、90°、105°)。所述保偏棱镜膜的保偏度为98％。
本发明提供一种保偏棱镜膜，所述第一结构层为棱镜层PL(Prism layer)，所述第二结 构层为雾化层。所述基体层的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述棱镜层由透明聚合物树脂AR构成，所述透明聚合物树的折射率nd为1.55。所述棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形，三角形的底边为50μm，顶角为90°。所述雾化层的雾度为5％-30％，所述雾化层种类为无粒子涂层，由透明聚合物AR构成，所述透明聚合物树脂的折射率nb为1.5。所述保偏棱镜膜的保偏度为95％-97％。
进一步的，本发明提供一种保偏逆棱镜膜，所述第一结构层不存在，所述第二结构层为逆棱镜层RL(Rverse-prism layer)。所述基体层的厚度T为25μm-250μm(例如25μm，50μm，75μm，100μm，125μm，250μm)，所述保偏基体层的材质选自PC、TAC、PMMA、或COP，光学各向同性，保偏度>99％，所述逆棱镜层由透明聚合物树脂AR、PC或PMMA形成，所述透明聚合物树的折射率nd为1.5-1.65(例如1.5、1.55或1.65)。所述逆棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形或普通三角形，三角形的底边宽度L为10μm-100μm(例如10μm、20μm、50μm、100μm)，顶角θ选自40°-90°(例如40°、60°、80°、或90°)，其中一个较大的底角α为90°-0.5θ+γ，偏角γ为0°-10°。所述保偏逆棱镜膜的保偏度为98％。
本发明提供一种保偏逆棱镜膜，所述第一结构层为雾化层，所述第二结构层为逆棱镜层RL(Rverse-prism layer)。所述基体层的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述逆棱镜层由透明聚合物树脂AR构成，所述透明聚合物树的折射率nd为1.55。所述逆棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形，三角形的底边宽度L为50μm，顶角θ选自60°，其中一个较大的底角α为90°-0.5θ+γ，偏角γ为0°。所述雾化层的雾度为30％-60％，所述雾化层种类为无粒子涂层，由透明聚合物AR构成，所述透明聚合物树脂的折射率nb为1.5。所述保偏棱镜膜的保偏度为90％-95％。
本发明还提供所述保偏光学膜的制备方法，在保偏基体层正面/背面依次利用涂布、微复制或热压成型过程，将透明聚合物树脂或含有透明聚合物粒子的透明聚合物树脂分别制备出第一结构层或第二结构层；其中，涂布适用于保偏扩散膜的雾化层制备，微复制和热压成型适用于保偏扩散膜、保偏微透镜膜、保偏棱镜膜、保偏逆棱镜膜的雾化层、微透镜层、棱镜层的制备。
进一步的，所述保偏光学膜的制备方法包括下述步骤：
(1)将保偏基体层作为支撑层，在正面涂布第一结构层，得到含有第一结构层的保偏光学膜；
进一步的，所述保偏光学膜的制备方法包括下述步骤：
(1)制备第一结构层的模具辊(辊1)；
(2)将保偏基体层作为支撑层，利用辊1在正面微复制或热压成型出第一结构层(凸)，得到含有第一结构层的保偏光学膜；
进一步的，所述保偏光学膜的制备方法包括下述步骤：
(1)将保偏基体层作为支撑层，在背面涂布第二结构层,得到含有第二结构层的保偏光学膜；
进一步的，所述保偏光学膜的制备方法包括下述步骤：
(1)制备第二结构层的模具辊(辊2)；
(2)将保偏基体层作为支撑层，利用辊2在背面微复制或热压成型出第二结构层,得到含有第二结构层的保偏光学膜；
进一步的，所述保偏光学膜的制备方法包括下述步骤：
(1)将保偏基体层作为支撑层，在正面涂布第一结构层,得到含有第一结构层的半成品；
(2)将步骤(1)制得的半成品背面涂布第二结构层,得到同时含有第一结构层和第二结构层的保偏光学膜；
进一步的，所述保偏光学膜的制备方法包括下述步骤：
(1)制备第一结构层的模具辊(辊1)；
(2)利用模具辊在保偏基体层正面微复制或热压成型出第一结构层，得到含有第一结构层的半成品；
(3)制备第二结构层的模具辊(辊2)；
(4)利用辊2在保偏基体层正面微复制或热压成型出第二结构层，得到同时含有第一结构层和第二结构层的保偏光学膜；
应当注意，第一结构层和第二结构层的加工方式应根据结构层种类和材质种类进行选择，本发明不做优选；
应当注意，本发明提供的保偏光学膜制备方法，适用于片材的生产，也适用于卷材的生产。
该保偏光学膜可以作为光学功能材料用于需保偏的光学系统中。特别适用于LCD线偏振背光源中，当背光中的线偏振光通过该保偏光学膜时可以保留较高偏振度，确保最终对LCD下偏光片的高度透过，大大提高背光源的利用率。
与现有技术相比，本发明提供的保偏光学膜，可以与线偏点光源搭配设计，方便产生 线偏振背光源，无需工艺复杂、价格昂贵的反射型偏光片，便可确保对LCD下偏光片的高度透过，提高背光源的利用率，增效方案性价比更高，优势明显。
附图说明
图1为LCD光能利用率低的原因；
图2为LCD传统增效方案示意图；
图3为LCD新型增效方案示意图；
图4为新型增效光路中传统光学膜的退偏结果示意图；
图5为本发明提供的保偏光学膜的保偏效果示意图；
图6为保偏度的测试方法示意图；
图7为保偏光学膜的基本结构示意图。
其中：
11：上偏光片；12：液晶面板(含玻璃基板、滤光片、液晶层、薄膜晶体管等)；13：下偏光片；14：背光模组；15：反射型偏光片；
21：部分偏振光；22：平行方向的线偏振光(相对于下偏光片透光轴或纸面)；23：垂直方向的线偏振光(相对于下偏光片透光轴或纸面)；
3：传统光学膜；
4：保偏光学膜；
50：保偏基体层；51：第一结构层；52：第二结构层；
60：待测膜片；61：起偏器；62：平行检偏器(与起偏器平行，用于检测Imax)；63：垂直检偏器(与起偏器垂直，检测Imin)。
具体实施方式
为了更易理解本发明的结构及所能达成的功能特征和优点，下文将本发明的较佳的实施例，并配合图式做详细说明如下。
本发明提供一种保偏光学膜(4)，该保偏光学膜(4)用来替代图4中的传统光学膜(3)，如图5所示，水平方向的线偏振光(22)经过本发明提供的保偏光学膜(4)后，出射光保持为水平方向的线偏振光(22)。
按照下述方式评价本发明提供的保偏光学膜的性能。
(A)保偏度
如图6所示，把待测膜片(60)置于起偏器(偏光片)(61)的上方，平行检偏器(偏光片)62或垂直检偏器(偏光片)63的下方，测量出射光的光强。当检偏器角度与线偏光平行时，检偏器称为平行检偏器，光强记为Imax，当检偏器角度与线偏光垂直时，检偏器称为垂检偏器，光强记为Imin，通过膜片后光的偏振度P＝(Imax-Imin)/(Imax+Imin)，P可同样被视为膜片的对该线偏光的保偏度。
如图7所示，本发明提供一种保偏光学膜，所述保偏光学膜包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于保偏基体层50上表面，第二结构层位于保偏基体层50下表面。
实施例1
本发明提供一种保偏光学膜，如图7所示，所述保偏光学膜为保偏扩散膜，所述第一结构层51为雾化层DL(Diffusion layer)，所述第二结构层52不存在。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述保偏扩散膜的雾度为98％。所述第一雾化层的雾度为98％，所述雾化层种类为有粒子涂层，由透明聚合物树脂PU和透明聚合物粒子PMMA构成，粒径d为5～15μm，所述透明聚合物树脂的折射率na为1.5。所述保偏扩散膜的保偏度为82％。
实施例2
如图7所示，本发明提供的保偏光学膜，包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于基体层50上表面，第二结构层位于基体层50下表面，所述保偏光学膜为保偏扩散膜，所述第一结构层51为雾化层，所述第二结构层52为雾化层。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述保偏扩散膜的雾度为98％。所述第一雾化层的雾度为98％，所述雾化层种类为有粒子涂层，由透明聚合物树脂PU和透明聚合物粒子PMMA构成，粒径d为5～15μm，所述透明聚合物树脂的折射率na为1.5。所述第二雾化层的雾度为5％，所述雾化层种类为无粒子涂层，由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nb为1.5。所述保偏扩散膜的保偏度为80％。
实施例3-20
如实施例1提供的保偏扩散膜，所述其他各项参数如表1所列。
表1实施例1～20提供的保偏扩散膜的设计参数和光学性能
Figure PCTCN2021074198-appb-000001
Figure PCTCN2021074198-appb-000002
注1：T为保偏基体层厚度。
如表1所示，为不同材质和设计参数搭配的保偏扩散膜的实施例。可以发现，当基体 层的材质为所述保偏基体如PC、PMMA、TAC、COP时，所制得的保偏扩散膜的保偏度均大于80％，厚度T影响不大。当雾化层的雾度降低时，保偏度会提高，而雾化层的种类，树脂、粒子材质对其影响不大。当第二结构层为低雾度的雾化层时，可以起到防粘、抗刮的效果，对光学影响不大。
实施例21
如图7所示为本发明提供的保偏光学膜，包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于基体层50上表面，第二结构层位于基体层50下表面，所述保偏光学膜为保偏微透镜膜，所述第一结构层51为微透镜阵列层ML(Microlens layer)，所述第二结构层52不存在。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述保偏微透镜膜的雾度为96％。所述微透镜阵列层的雾度为98％，所述微透镜阵列层由透明聚合物树脂AR形成，所述透明聚合物树脂的折射率nc为1.5。所述微透镜阵列层中，相邻微透镜的主光轴的间距D为50μm，微透镜的宽度为W(W＝D)，微透镜的高度为H，高宽比H/W为0.5，此时，微透镜为半球状；所述保偏微透镜的保偏度为85％。
实施例22
如图7所示为本发明提供的保偏光学膜，包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于基体层50上表面，第二结构层位于基体层50下表面，所述保偏光学膜为保偏微透镜膜，所述第一结构层51为微透镜阵列层，所述第二结构层52为雾化层。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述保偏微透镜膜的雾度为96％。所述微透镜阵列层的雾度为98％，所述微透镜阵列层由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nc为1.5。所述雾化层的雾度为5％，所述雾化层种类为无粒子涂层，由透明聚合物AR构成，所述透明聚合物树脂的折射率nb为1.5。所述保偏微透镜膜保偏度为85％。
实施例23-36
如实施例21提供的保偏微透镜膜，所述其他各项参数如表2所列。
表2实施例21～36提供的保偏微透镜膜的设计参数和光学性能
Figure PCTCN2021074198-appb-000003
Figure PCTCN2021074198-appb-000004
注1：T为基体层厚度；D为相邻微透镜的主光轴的间距；W为微透镜的宽度，H为微透镜的高度，H/W为高宽比。
如表2所示，为不同材质和设计参数搭配的保偏微透镜膜的实施例。可以发现，当基体层的材质为所述保偏基体如PC、PMMA、TAC、COP时，所制得得保偏微透镜膜的保偏度均大于80％，厚度T影响不大。当微透镜层的雾度降低时，保偏度会提高，而透明聚合物的折射率降低，或高宽比降低时，雾度也会降低，保偏度也会提高，而树脂种类影响不大。当第二结构层为低雾度的雾化层时，可以起到防粘、抗刮的效果，对光学影响不大。
实施例37
如图7所示为本发明提供的保偏光学膜，包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于基体层50上表面，第二结构层位于基体层50下表面，所述保偏光学膜为保偏棱镜膜，所述第一结构层51为棱镜层PL(Prism layer)，所述第二结构层52不存在。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述棱镜层由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nd为1.55。所述棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形，三角形的底边为50μm，顶角为90°。所述保偏棱镜膜的保偏度为98％。
实施例38
如图7所示为本发明提供的保偏光学膜，包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于基体层50上表面，第二结构层位于基体层50下表面，所述保 偏光学膜为保偏棱镜膜，所述第一结构层51为棱镜层PL(Prism layer)，所述第二结构层52为雾化层。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述棱镜层由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nd为1.55。所述棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形，三角形的底边为50μm，顶角为90°。所述雾化层的雾度为5％，所述雾化层种类为无粒子涂层，由透明聚合物AR构成，所述透明聚合物树脂的折射率nb为1.5。所述保偏棱镜膜的保偏度为97％。
实施例39-50
如实施例37提供的保偏棱镜膜，所述其他各项参数如表3所列。
表3实施例37～50提供的保偏棱镜膜的设计参数和光学性能
Figure PCTCN2021074198-appb-000005
注1：T为基体层厚度。
如表3所示，为不同材质和设计参数搭配的保偏棱镜膜的实施例。可以发现，当基体层的材质为所述保偏基体如PC、PMMA、TAC、COP时，所制得得保偏棱镜膜的保偏度均大于80％，厚度T影响不大。当棱镜层的材质、折射率、底边、顶角改变时，保偏度基本不影响。当第二结构层为雾化层时，可以起到防粘、抗刮的效果，雾度增加时，保偏度略有下降。
实施例51
如图7所示为本发明提供的保偏光学膜，包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于基体层50上表面，第二结构层位于基体层50下表面，所述保偏光学膜为保偏逆棱镜膜，所述第一结构层51不存在，所述第二结构层52为逆棱镜层RL(Rverse-prism layer)。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述逆棱镜层由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nd为1.55。所述逆棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形或普通三角形，三角形的底边宽度L为50μm，顶角θ选自60°，其中一个较大的底角α为90°-0.5θ+γ，偏角γ为0°。所述保偏逆棱镜膜的保偏度为98％。
实施例52
如图7所示为本发明提供的保偏光学膜，包括第一结构层51、保偏基体层50和第二结构层52，第一结构层位于基体层50上表面，第二结构层位于基体层50下表面，所述保偏光学膜为保偏逆棱镜膜，所述第一结构层51为雾化层，所述第二结构层52为逆棱镜层RL(Rverse-prism layer)。所述基体层50的厚度T为250μm，所述保偏基体层的材质选自PC，光学各向同性，保偏度>99％，所述逆棱镜层由透明聚合物树脂AR构成，所述透明聚合物树脂的折射率nd为1.55。所述逆棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形，三角形的底边宽度L为50μm，顶角θ选自60°，其中一个较大的底角α为90°-0.5θ+γ，偏角γ为0°。所述雾化层的雾度为30％，所述雾化层种类为无粒子涂层，由透明聚合物AR构成，所述透明聚合物树脂的折射率nb为1.5。所述保偏棱镜膜的保偏度为95％。
实施例53-64
如实施例51提供的保偏逆棱镜膜，所述其他各项参数如表4所列。
表4实施例51～64提供的保偏逆棱镜膜的设计参数和光学性能
Figure PCTCN2021074198-appb-000006
Figure PCTCN2021074198-appb-000007
注1：T为基体层厚度。
如表4所示，为不同材质和设计参数搭配的保偏逆棱镜膜的实施例。可以发现，当基体层的材质为所述保偏基体如PC、PMMA、TAC、COP时，所制得得保偏逆棱镜膜的保偏度均大于80％，厚度T影响不大。当逆棱镜层的材质、折射率、底边、顶角改变时，保偏度基本不影响。当第一结构层为雾化层时，可以起到防粘、抗刮的效果，雾度增加时，保偏度略有下降。
应当注意，以上所述，仅为本发明的几种典型的实施例而已，并非用于限定本发明的保护范围。凡是根据本发明内容所做的均等变化与修饰，均涵盖在本发明的专利范围内。

Claims (14)

  1. 一种保偏光学膜，其特征在于，所述光学膜包括保偏基体层、第一结构层和/或第二结构层，第一结构层位于保偏基体层上表面，第二结构层位于保偏基体层下表面。
  2. 根据权利要求1所述的保偏光学膜，其特征在于，当线偏振光通过该保偏光学膜时，该保偏光学膜对入射线偏振光的保偏度大于或等于80％；所述保偏光学膜为保偏扩散膜、保偏微透镜膜、保偏棱镜膜、或保偏逆棱镜膜中的一种。
  3. 根据权利要求1所述的保偏光学膜，其特征在于，所述保偏基体层的保偏度大于99％。
  4. 根据权利要求3所述的保偏光学膜，其特征在于，所述保偏基体层为光学各向同性的透明聚合物。
  5. 根据权利要求2所述的保偏光学膜，其特征在于，所述保偏基体层的材质选自甲基丙烯酸甲酯(PMMA)、聚碳酸酯(PC)、三醋酸纤维素(TAC)、环烯烃聚合物(COP)中的一种或至少两种的组合。
  6. 根据权利要求2所述的保偏光学膜，其特征在于，所述保偏光学膜为保偏扩散膜，所述保偏扩散膜的雾度为60～98％。
  7. 根据权利要求6所述的保偏光学膜，其特征在于，所述保偏扩散膜的第一结构层为雾化层，第二结构层不存在或同为雾化层，雾化层种类选自无粒子涂层或有粒子涂层。
  8. 根据权利要求6所述的保偏光学膜，其特征在于，所述保偏扩散膜的无粒子涂层由透明聚合物树脂构成，有粒子涂层由透明聚合物树脂和透明聚合物粒子构成；透明聚合物粒子的粒径为1～20μm。
  9. 根据权利要求2所述的保偏光学膜，其特征在于，所述保偏光学膜为保偏微透镜膜，所述保偏微透镜膜的雾度为60～98％。
  10. 根据权利要求9所述的保偏光学膜，其特征在于，所述保偏微透镜膜的第一结构层为微透镜阵列层；在所述微透镜阵列层中，相邻的三个微透镜的主光轴的坐标相连形成正三角形，或者，相邻的四个微透镜的主光轴的坐标相连形成正方形；所述微透镜阵列中的微透镜紧密排列。
  11. 根据权利要求9所述的保偏光学膜，其特征在于，在所述微透镜阵列层中，相邻微透镜的主光轴的间距D为10～50μm，微透镜的宽度为W(W＝D)，微透镜的高度为H，高宽比H/W为0.05～0.5。
  12. 根据权利要求2所述的保偏光学膜，其特征在于，所述保偏棱镜膜的第一结构层为棱镜层，第二结构层不存在或为雾化层；所述棱镜层由三棱镜肋平铺而成，所述三棱镜肋的 横截面为等腰三角形，三角形的底边为10～100μm，顶角为75～105°；所述雾化层的雾度为0～30％。
  13. 根据权利要求2所述的保偏光学膜，其特征在于，所述保偏光学膜为保偏逆棱镜膜，所述保偏逆棱镜膜的第二结构层为逆棱镜层，第一结构层不存在或为雾化层；所述逆棱镜层由三棱镜肋平铺而成，所述三棱镜肋的横截面为等腰三角形或普通三角形，三角形的底边宽度L为10～100μm，顶角θ选自40～80°，其中一个较大的底角α为90°-0.5θ+γ，偏角γ为0～10°，当γ为0°时，横截面为等腰三角形，当γ大于0°时，横截面为普通三角形。
  14. 根据权利要求1-13中任一项所述的保偏光学膜的制备方法，其特征在于，在保偏基体层正面/背面依次利用涂布、微复制或热压成型过程，将透明聚合物树脂或含有透明聚合物粒子的透明聚合物树脂分别制备出第一结构层或第二结构层；其中，涂布适用于保偏扩散膜的雾化层制备，微复制和热压成型适用于保偏扩散膜、保偏微透镜膜、保偏棱镜膜、保偏逆棱镜膜的雾化层、微透镜层、棱镜层的制备。
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