CN107132606B - Polarizing plate group and liquid crystal panel - Google Patents
Polarizing plate group and liquid crystal panel Download PDFInfo
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- CN107132606B CN107132606B CN201710105956.1A CN201710105956A CN107132606B CN 107132606 B CN107132606 B CN 107132606B CN 201710105956 A CN201710105956 A CN 201710105956A CN 107132606 B CN107132606 B CN 107132606B
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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
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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
- G02B5/3016—Polarising elements involving passive liquid crystal elements
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- 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
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
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- 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
- G02B1/14—Protective coatings, e.g. hard coatings
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- 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
- G02F1/0136—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 for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation
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- 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
- G02F1/133536—Reflective polarizers
Abstract
The invention provides a polarizing plate group capable of inhibiting the warping of a liquid crystal panel in a high-temperature environment and a liquid crystal panel formed by bonding the polarizing plate group to a liquid crystal unit. The invention provides a polarizing plate group, which is a polarizing plate group comprising a 1 st polarizing plate arranged on the observation side of a liquid crystal cell and a 2 nd polarizing plate arranged on the back side of the liquid crystal cell, wherein the 2 nd polarizing plate comprises a reflective polarizing film, the shrinkage force per 2mm width in the absorption axis direction when the 1 st polarizing plate is kept at 80 ℃ for 4 hours is F1, the shrinkage force per 2mm width in the transmission axis direction is F2, the shrinkage force per 2mm width in the absorption axis direction when the 2 nd polarizing plate is kept at 80 ℃ for 4 hours is F3, and the shrinkage force per 2mm width in the transmission axis direction is F4, (F1 XF 2)/(F3 XF 4) is 0.5-5.0.
Description
Technical Field
The present invention relates to a polarizing plate group capable of suppressing warping of a liquid crystal panel in a high-temperature environment, and a liquid crystal panel using the polarizing plate group.
Background
In recent years, liquid crystal displays that are low in power consumption, operate at low voltage, and are lightweight and thin have rapidly become popular as information display devices such as mobile phones, portable information terminals, monitors for computers, and televisions. With the development of liquid crystal technology, various modes of liquid crystal displays have been proposed, and problems of liquid crystal displays such as response speed, contrast, narrow viewing angle, and the like are gradually being eliminated. In addition, with the spread of liquid crystal displays for mobile use, there is a demand for a thin and lightweight liquid crystal panel.
With the thinning of the liquid crystal panel, the following problems exist: the liquid crystal panel is warped due to shrinkage of the polarizing plate bonded to the liquid crystal cell in a high-temperature environment, and cannot be accommodated in a case of a final product.
In order to suppress such warpage of the liquid crystal display panel, the following methods have been developed: warping of the liquid crystal display panel is suppressed by changing the thickness of the polarizing plate disposed on the observation side of the liquid crystal cell and on the side (back side) of the liquid crystal cell opposite to the observation side. For example, japanese patent laid-open No. 2012-58429 (patent document 1) describes the following method: the warping of the liquid crystal display panel is suppressed by making the polarizing film of the polarizing plate disposed on the observation side of the liquid crystal cell (the polarizing plate in the present invention) thinner than the polarizing film disposed on the back side of the liquid crystal cell.
In addition, the following methods are proposed in japanese patent application laid-open No. 2013-37115 (patent document 2): the polarizing film (the polarizing plate in the present invention) included in the optical laminate on the observation side is made to be 5 μm or more thicker than the polarizing film included in the optical laminate on the side opposite to the observation side, thereby suppressing the warping of the liquid crystal panel. However, although these methods can exert an effect on a liquid crystal cell having a large thickness (for example, 0.5mm or more, and further 0.7mm or more), the effect of suppressing warpage on a thin liquid crystal cell is insufficient.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2012-58429
Patent document 2: japanese patent laid-open publication No. 2013-37115
Disclosure of Invention
Problems to be solved by the invention
The invention aims to provide a polarizing plate group capable of inhibiting the warping of a liquid crystal panel under a high-temperature environment and a liquid crystal panel formed by bonding the polarizing plate group to a liquid crystal unit.
Means for solving the problems
[1] A polarizing plate group comprising a 1 st polarizing plate disposed on the viewing side of a liquid crystal cell and a 2 nd polarizing plate disposed on the back side of the liquid crystal cell,
the 2 nd polarizing plate described above has a reflective polarizing film,
when the 1 st polarizing plate is held at 80 ℃ for 4 hours, the shrinkage force per 2mm width in the absorption axis direction is F1, the shrinkage force per 2mm width in the transmission axis direction is F2, the shrinkage force per 2mm width in the absorption axis direction when the 2 nd polarizing plate is held at 80 ℃ for 4 hours is F3, and the shrinkage force per 2mm width in the transmission axis direction is F4, (F1 XF 2)/(F3 XF 4) is 0.5 to 5.0.
[2] The polarizing plate set according to item [1], wherein each of the 1 st and 2 nd polarizing plates has a polarizing plate comprising a polyvinyl alcohol resin film, and each of the polarizing plates has a thickness of 20 μm or less.
[3] The polarizing plate set according to item [2], wherein the polarizer included in the 1 st polarizing plate has a thickness of 10 μm or more, and the polarizer included in the 2 nd polarizing plate has a thickness of 10 μm or less.
[4] The polarizing plate assembly according to item [2] or [3], wherein the 2 nd polarizing plate is configured such that a protective film is laminated on one surface of the polarizer and the reflective polarizer is laminated on the other surface.
[5]According to [4]]The polarizing plate set described above, wherein the protective film has a moisture permeability of 500 g/(m)224hr) or less.
[6] A liquid crystal panel comprising the polarizing plate group according to any one of [1] to [5] and a liquid crystal cell, wherein the liquid crystal cell has a thickness of 0.4mm or less.
Effects of the invention
According to the present invention, warping of the liquid crystal panel in a high-temperature environment can be eliminated, and a liquid crystal panel housed in a case of a final product in a high-temperature environment can be obtained.
Drawings
Fig. 1 is a schematic cross-sectional view showing an example of a preferable layer structure of a polarizing plate group of the present invention.
Fig. 2 is a schematic cross-sectional view showing an example of a preferable layer structure of the polarizing plate group of the present invention.
Fig. 3 is a perspective view showing an example of a preferred axial configuration of the polarizing plate group of the present invention.
Fig. 4 is a schematic view of an example of the reflective polarizing plate used in the present invention.
Fig. 5 is a schematic cross-sectional view showing an example of a liquid crystal panel of the present invention.
Detailed Description
Hereinafter, a polarizing plate group according to the present invention and a liquid crystal panel using the same will be described with reference to the drawings as appropriate, but the present invention is not limited to these embodiments.
The polarizing plate group of the present invention includes a 1 st polarizing plate 10 disposed on the viewing side of the liquid crystal cell and a 2 nd polarizing plate 11 disposed on the back side of the liquid crystal cell. The layer structure of the 1 st polarizing plate 10 and the 2 nd polarizing plate 11 of the present invention will be described with reference to fig. 1. In fig. 1, the 1 st polarizing plate 10 has protective films 30a and 30b attached to both surfaces of a polarizer 20. It is also useful to form a surface treatment layer on the surface of the protective film 30a opposite to the bonding surface of the polarizing plate 20. The 2 nd polarizing plate 11 preferably has a protective film on at least one side of the polarizer 21, and may be formed by laminating protective films 31a and 31b on both sides of the polarizer and laminating a reflective polarizer 50 with an adhesive layer 40 interposed therebetween as shown in fig. 1. Further, it is also preferable that: as shown in fig. 2, a protective film 31a is laminated on one surface of the polarizing plate 21, and a reflection-type polarizing plate 50 is directly laminated on the polarizing plate 21 via an adhesive layer 40 without interposing a protective film 31b therebetween on the other surface. These polarizing plates are bonded to the liquid crystal cell via adhesive layers 32 and 33, respectively, to form a liquid crystal panel.
The polarizing plate group of the present invention has (F1 XF 2)/(F3 XF 4) of 0.5 to 5.0, where F1 represents a contraction force per 2mm width in the absorption axis direction when the 1 st polarizing plate is held at 80 ℃ for 4 hours, F2 represents a contraction force per 2mm width in the transmission axis direction, F3 represents a contraction force per 2mm width in the absorption axis direction when the 2 nd polarizing plate is held at 80 ℃ for 4 hours, and F4 represents a contraction force per 2mm width in the transmission axis direction. The following are found: it is not sufficient to simply reduce the contraction force of the 1 st and 2 nd polarizing plates, and by satisfying such a condition, even when the thickness of the liquid crystal cell is thin, the warping of the liquid crystal panel when the liquid crystal panel is left standing for 250 hours in an environment of 85 ℃.
The inventors theorize the following without limiting the invention in any way. It is inferred that the shrinkage force of the polarizing plate here affects the warpage of the liquid crystal panel, and the shrinkage force in the absorption axis direction of the polarizer included in the polarizing plate further dominates the warpage of the liquid crystal panel, so that F1/F4 relates to the ease of warpage in the absorption axis direction of the 1 st polarizing plate (the transmission axis direction of the 2 nd polarizing plate) in the liquid crystal panel, and F3/F2 relates to the ease of warpage in the transmission axis direction of the 1 st polarizing plate (the absorption axis direction of the 2 nd polarizing plate) in the liquid crystal panel. The warpage of an actual liquid crystal panel is considered to be determined by the ratio (balance) of F1/F4 to F3/F2, and thus the ratio is (F1 × F2)/(F3 × F4).
The contraction force F1 in the absorption axis direction of the 1 st polarizing plate is preferably 3N/2mm or less, more preferably 2.5N/2mm or less, and may exceed 1.6N/2mm from the viewpoint of easily satisfying the above formula. The contraction force F2 in the transmission axis direction of the 1 st polarizing plate is preferably 0.3N/2mm or less, more preferably 0.15N/2mm or less, and usually 0.00N/2mm or more.
The shrinkage force F3 in the absorption axis direction of the 2 nd polarizing plate is preferably 3N/2mm or less, more preferably 2.5N/2mm or less, and from the viewpoint of easily satisfying the above formula, more preferably 2.0N/2mm or less, and still more preferably 1.6N/2mm or less. The shrinkage force F4 in the transmission axis direction of the 2 nd polarizing plate is preferably 0.3N/2mm or less, more preferably 0.15N/2mm or less, and usually 0.00N/2mm or more.
In order to easily satisfy the above formula in the range of 0.5 to 5.0, the contraction force F3 in the absorption axis direction of the 2 nd polarizing plate is preferably smaller than the contraction force F1 in the absorption axis direction of the 1 st polarizing plate.
In the polarizing plate group of the present invention, the ratio of the thickness of the 1 st polarizing plate to the thickness of the 2 nd polarizing plate is preferably 0.8 to 1.5, more preferably 1.01 to 1.5, and even more preferably 1.01 to 1.4, in view of the ease of adjusting the range of (F1 xf 2)/(F3 xf 4). Specifically, the thickness of the 1 st polarizer is preferably 80 μm or less, and more preferably 70 μm or less. The thickness of the polarizing plate of the 2 nd polarizing plate is preferably 70 μm or less, and more preferably 60 μm or less. The thickness of the polarizing plate described here does not include the thickness of the adhesive layer for bonding to the liquid crystal cell.
Further, the following configuration is preferably adopted: the absorption axis of the 1 st polarizing plate is substantially parallel to the short side direction of the liquid crystal cell, and the absorption axis of the 2 nd polarizing plate is substantially parallel to the long side direction of the liquid crystal cell. The "substantially parallel" is not limited to being strictly parallel, and for example, an angle formed by the absorption axis of the polarizing plate and each side of the liquid crystal cell is preferably 5 ° or less, more preferably 3 ° or less, and further preferably 1 ° or less.
Hereinafter, the polarizing plate group and the members constituting the liquid crystal panel according to the present invention will be described in detail. The polarizer 20 included in the 1 st polarizing plate 10 and the polarizer 21 included in the 2 nd polarizing plate 11 may be collectively referred to as a polarizer, and the protective film 30a, the protective film 30b, the protective film 31a, and the protective film 31b may be collectively referred to as a protective film.
[ polarizing plate ]
As the polarizing plates 20 and 21, any suitable polarizing plate may be used as long as the above-described curling force is satisfied. The polarizing plate is generally manufactured through the following processes: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing the polyvinyl alcohol resin film with a dichroic dye to thereby adsorb the dichroic dye; treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution to crosslink the polyvinyl alcohol resin film; and a step of washing the resultant product after the crosslinking treatment with an aqueous boric acid solution.
The polyvinyl alcohol resin can be produced by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.
The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.
The polyvinyl alcohol resin can be used as a raw material film of a polarizing plate after being formed into a film. The method for forming the film of the polyvinyl alcohol resin is not particularly limited, and a known method can be used for forming the film. The thickness of the polyvinyl alcohol resin film is, for example, about 10 to 100 μm, preferably about 10 to 50 μm.
The uniaxial stretching in the machine direction of the polyvinyl alcohol resin film may be performed before, simultaneously with, or after the dyeing with the dichroic dye. In the case where the uniaxial longitudinal stretching is performed after dyeing, the uniaxial longitudinal stretching may be performed before or during the boric acid treatment. Of course, uniaxial longitudinal stretching may also be performed in multiple stages as shown herein. As the longitudinal uniaxial stretching, a method of performing uniaxial stretching between rolls having different peripheral speeds, a method of performing uniaxial stretching using a hot roll, or the like can be used. The longitudinal uniaxial stretching may be performed by dry stretching performed in the air, or by wet stretching performed in a state where the polyvinyl alcohol resin film is swollen with a solvent such as water. The draw ratio is usually about 3 to 8 times.
The dyeing of the polyvinyl alcohol resin film with the dichroic dye can be performed, for example, by a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, specifically, iodine or a dichroic organic dye is used. The polyvinyl alcohol resin film is preferably subjected to a treatment of swelling by immersing in water before dyeing.
When iodine is used as the dichroic dye, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing iodine and potassium iodide to dye the film is generally employed.
The content of iodine in the aqueous solution is usually about 0.01 to 1 part by weight relative to 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight relative to 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ℃. The immersion time (dyeing time) in the aqueous solution is usually about 20 to 1,800 seconds.
On the other hand, in the case of using a dichroic organic dye as the dichroic dye, a method of impregnating a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye to dye the resin film is generally employed, and the content of the dichroic organic dye in the aqueous solution is generally 1 × 10 relative to 100 parts by weight of water-4About 10 parts by weight, preferably 1 × 10-3About 1 part by weight. The aqueous dye solution may also contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the dichroic dye aqueous solution used for dyeing is usually about 20 to 80 ℃. The immersion time (dyeing time) in the aqueous solution is usually about 10 to 1,800 seconds.
The boric acid treatment after dyeing with the dichroic dye can be performed by a method of immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid. The boric acid content of the aqueous solution containing boric acid is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of water. In the case of using iodine as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide. The content of potassium iodide in the aqueous solution containing boric acid is usually about 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of water. The immersion time in the aqueous solution containing boric acid is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is preferably 60 to 70 ℃ when the polarizer of the 1 st polarizing plate is manufactured and 55 to 65 ℃ when the polarizer of the 2 nd polarizing plate is manufactured, from the viewpoint that the shrinkage force of each polarizer can be easily adjusted so that (F1 × F2)/(F3 × F4) satisfies 0.5 to 5.0.
The polyvinyl alcohol resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be performed, for example, by a method of immersing the polyvinyl alcohol resin film subjected to the boric acid treatment in water. The temperature of water in the water washing treatment is usually about 5 to 40 ℃. The dipping time is usually about 1 to 120 seconds.
After washing with water, drying treatment was performed to obtain a polarizing plate. The drying treatment may be performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ℃, preferably 50 to 80 ℃. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. The moisture content of the polarizing film is reduced to a practical level by drying treatment. The water content is usually about 5 to 20% by weight, preferably 8 to 15% by weight. When the water content is less than 5% by weight, the flexibility of the polarizing plate is lost, and damage or breakage may occur after drying. When the water content exceeds 20% by weight, the thermal stability tends to be insufficient.
In this manner, a polarizing plate having a dichroic dye adsorbed and aligned on a polyvinyl alcohol resin film can be produced.
The stretching, dyeing, boric acid treatment, water washing, and drying of the polyvinyl alcohol resin film in the process of producing the polarizing plate can be carried out, for example, according to the method described in japanese patent application laid-open No. 2012-159778. Among the methods described in this document, a method of forming a polyvinyl alcohol resin layer to be a polarizing plate by coating a polyvinyl alcohol resin on a base film is also useful.
In order to adjust the shrinkage force of each polarizing plate in the polarizing plate group to the above range, the thicknesses of the polarizing plates included in the 1 st polarizing plate and the 2 nd polarizing plate are each preferably 20 μm or less, and more preferably less than 15 μm. Further, it is preferable that the thickness of the polarizer included in the 1 st polarizing plate is 10 μm or more and the thickness of the polarizer included in the 2 nd polarizing plate is 10 μm or less. The thickness of the polarizing plate is usually 3 μm or more in terms of imparting good optical characteristics. The shrinkage force of the polarizing plate is also affected by the shrinkage of the reflective polarizer, and the warping of the liquid crystal panel is more easily reduced by setting the thickness of the polarizer to 20 μm or less and a predetermined thickness difference between the thickness of the polarizer included in the 1 st polarizing plate and the thickness of the polarizer included in the 2 nd polarizing plate.
[ protective film ]
As the protective films 30a, 30b, 31a, and 31b, protective films made of an appropriate transparent resin can be used. Specifically, a protective film containing a polymer excellent in transparency, uniform optical characteristics, mechanical strength, thermal stability, and the like is preferably used. As such a transparent resin film, for example: cellulose films such as triacetyl cellulose and diacetyl cellulose; polyester films such as polyethylene terephthalate, polyethylene isophthalate, and polybutylene terephthalate; acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; a polycarbonate-based film; a polyethersulfone membrane; a polysulfone-based membrane; a polyimide-based film; a polyolefin-based film; polynorbornene-based films, and the like. However, the transparent resin film is not limited thereto.
The protective films 30a and 30b applied to the 1 st polarizing plate 10 and the protective films 31a and 31b applied to the 2 nd polarizing plate 11 may be the same protective film or different protective films, respectively.
The protective films 31a and 31b applied to the 2 nd polarizing plate 11 preferably have different moisture permeabilities, and the difference in moisture permeability is preferably 750 g/(m) under the conditions of a temperature of 40 ℃ and a relative humidity of 90%224hr) or more, more preferably 1000 g/(m)224hr) above. For example, by using different materials for the protective films 31a and 31b, the difference in moisture permeability can be increased. In addition, it is also preferable to omit the protective film 31b of the 2 nd polarizing plate and to have a protective film only on one side of the polarizer, and in this case, the moisture permeability of the protective film 31a is preferably 500 g/(m)224hr) or less, more preferably 250 g/(m)224hr) or less.
The protective film may be subjected to an easy adhesion treatment such as saponification treatment, corona treatment, undercoating treatment, anchor coating treatment, or the like on the surface to be bonded to the polarizer before bonding. The thickness of the protective film is usually in the range of about 5 to 200 μm, preferably 10 μm or more, and preferably 80 μm or less, more preferably 40 μm or less, and particularly preferably 35 μm or less.
In addition, a coating layer (surface treatment layer) may be provided on the outer surface of the protective film 30a in order to impart desired surface optical characteristics or other features. Specific examples of the coating layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer. The method for forming the coating layer is not particularly limited, and a known method can be used.
When the liquid crystal cell is In an In-Plane Switching (IPS) mode, the wide viewing angle characteristic inherent In the IPS mode liquid crystal cell is not impaired, and therefore, the retardation value Rth In the thickness direction of the protective films 30b and 31b is preferably In the range of-10 to 10 nm. The in-plane retardation value Re is preferably in the range of-10 to 10 nm.
The retardation value Rth in the thickness direction is a value obtained by subtracting the refractive index in the thickness direction from the average in-plane refractive index and multiplying the value by the thickness of the film, and is defined by the following formula (a). The in-plane retardation value Re is a value obtained by multiplying the in-plane refractive index difference by the film thickness, and is defined by the following formula (b).
Rth＝〔(nx+ny)/2-nz〕×d (a)
Re＝(nx-ny)×d (b)
In the formula, nx is a refractive index in an x-axis direction (in-plane slow axis direction) in the film surface, ny is a refractive index in a y-axis direction (in-plane fast axis direction and in-plane direction orthogonal to the x-axis) in the film surface, nz is a refractive index in a z-axis direction (thickness direction) perpendicular to the film surface, and d is a film thickness.
Here, the phase difference value may be a value at any wavelength in the range of about 500 to 650nm, which is the vicinity of the center of visible light, but in the present specification, the phase difference value at a wavelength of 590nm is taken as a standard. The retardation value Rth in the thickness direction and the retardation value Re in the plane can be measured by using various commercially available retardation meters.
As a method for controlling the retardation value Rth in the thickness direction of the protective film to be in the range of-10 to 10nm, there is a method for reducing the strain remaining in the plane and in the thickness direction as much as possible when the film is produced. For example, in the solvent casting method, a method of relaxing residual shrinkage strain in the in-plane and thickness directions generated when the casting resin solution is dried by heat treatment or the like can be employed. On the other hand, in the above melt extrusion method, the following methods and the like can be adopted: in order to prevent the resin film from being extruded from the die and stretched until cooling, the distance from the die to the cooling drum is shortened as much as possible, and the extrusion amount and the rotation speed of the cooling drum are controlled in such a manner that the film is not stretched. In addition, a method of relaxing the strain remaining in the obtained film by heat treatment may be employed as in the solvent casting method.
[ reflection type polarizing plate 50]
The polarizing plate 11 of the present invention 2 has a reflective polarizer 50. Fig. 4 is a schematic cross-sectional view of an example of a reflection type polarizing plate used in the present invention. The reflective polarizer 50 is a multilayer laminate in which a layer a having birefringence and a layer B having substantially no birefringence are alternately laminated. For example, in the illustrated 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, and 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. Therefore, 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. The result is: the x-axis direction is a reflection axis, and the y-axis direction is a transmission axis. The difference between the refractive index of the layer A and that of the layer B in the x-axis direction is preferably 0.2 to 0.3. The x-axis direction corresponds to the stretching direction of the reflective polarizer.
The layer a is preferably made of a material exhibiting birefringence by stretching. Typical examples of such materials include naphthalenedicarboxylic acid polyesters (e.g., polyethylene naphthalate), polycarbonates, and acrylic resins (e.g., polymethyl methacrylate). Polyethylene naphthalate is preferred. The B layer is preferably made of a material which does not substantially exhibit birefringence even when stretched. As a representative example of such a material, a copolyester of naphthalenedicarboxylic acid and terephthalic acid is cited.
The reflective polarizer transmits light having a 1 st polarization direction (for example, p-wave) at an interface between the a layer and the B layer, and reflects light having a 2 nd polarization direction (for example, s-wave) orthogonal to the 1 st polarization direction. The reflected light is transmitted partially as light having the 1 st polarization direction and is reflected partially as light having the 2 nd polarization direction at the interface between the a layer and the B layer. The reflection and transmission as described above are repeated a plurality of times inside the reflection-type polarizing plate, whereby the light use efficiency can be improved.
The reflection type polarizing plate 50 preferably includes a reflection layer R as an outermost layer on the side opposite to the polarizing plate 21. By providing the reflective layer R, light that is not finally used and returns to the outermost portion of the reflective polarizer can be further utilized, and thus the light utilization efficiency can be further improved.
The reflective layer R typically exhibits a reflective function by a multilayer structure of a polyester resin layer.
The overall thickness of the reflective polarizer may be appropriately set according to the purpose, the total number of layers included in the reflective polarizer, and the like. From the viewpoint of suppressing dimensional change in a high-temperature environment, the thickness of the entire reflection-type polarizing plate is preferably 15 μm to 50 μm, and more preferably 30 μm or less.
As the reflection type polarizing plate, for example, a reflection type polarizing plate described in Japanese patent application laid-open No. 9-507308 can be used.
The reflection type polarizing plate 50 may be a commercially available one as it is, or may be a commercially available one subjected to secondary processing (for example, stretching). Examples of commercially available products include trade names DBEF and APF manufactured by 3M company.
[ lamination of polarizing plate and protective film ]
The polarizing plate and the protective film may be bonded to each other with an adhesive or a bonding agent. The thickness of the adhesive layer for bonding the polarizer and the protective film may be about 0.01 to 30 μm, preferably 0.01 to 10 μm, and more preferably 0.05 to 5 μm. When the thickness of the adhesive layer is within this range, floating and peeling between the laminated protective film and the polarizing plate do not occur, and practically satisfactory adhesion is obtained. The thickness of the adhesive layer for bonding the polarizer and the protective film may be about 5 to 50 μm, preferably 5 to 30 μm, and more preferably 10 to 25 μm.
When the polarizing plate and the protective film are bonded to each other, it is also useful to preliminarily subject the polarizing plate and the protective film to saponification treatment, corona treatment, plasma treatment, or the like.
(Adhesives)
In forming the adhesive layer, an appropriate adhesive can be used according to the kind and purpose of the adherend, and an anchor coating agent can be used as needed. Examples of the adhesive include a solvent type adhesive, an emulsion type adhesive, a pressure sensitive adhesive, a remoistenable adhesive, a condensation polymerization type adhesive, a solvent-free type adhesive, a film type adhesive, and a hot melt type adhesive.
As one of the preferable adhesives, an aqueous adhesive, that is, an adhesive in which an adhesive component is dissolved or dispersed in water can be cited. Examples of the adhesive component that can be dissolved in water include a polyvinyl alcohol resin. Examples of the adhesive component that can be dispersed in water include polyurethane resins having a hydrophilic group. The aqueous adhesive can be prepared by mixing such an adhesive component with an additional additive added as needed in water. Examples of commercially available polyvinyl alcohol resins that can be used as water-based adhesives include "KL-318" which is a carboxyl-modified polyvinyl alcohol sold by Coli.
The aqueous adhesive may contain a crosslinking agent as needed. Examples of the crosslinking agent include amine compounds, aldehyde compounds, methylol compounds, water-soluble epoxy resins, isocyanate compounds, polyvalent metal salts, and the like. When a polyvinyl alcohol resin is used as the adhesive component, an aldehyde compound typified by glyoxal, a methylol compound typified by methylolmelamine, a water-soluble epoxy resin, or the like is preferably used as the crosslinking agent.
The water-soluble epoxy resin may be, for example, a polyamide epoxy resin obtained by reacting a polyamide polyamine, which is a reaction product of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine and a dicarboxylic acid such as adipic acid, with epichlorohydrin. Examples of commercially available products of water-soluble epoxy resins include "Sumirez Resin (registered trademark) 650 (30)", which is sold by tianggang chemical industries co.
A polarizing plate can be obtained by applying an aqueous adhesive to the adhesive surface of the polarizer and/or the protective film attached to the polarizer, attaching the two, and then drying the two. It is also effective to subject the protective film to an easy-adhesion treatment such as saponification treatment, corona discharge treatment, plasma treatment, or undercoating treatment before adhesion to improve the wettability in advance. The drying temperature may be, for example, about 50 to 100 ℃. In order to further improve the adhesion, it is preferable to cure the composition at a temperature slightly higher than room temperature, for example, at a temperature of about 30 to 50 ℃ for about 1 to 10 days after the drying treatment.
Another preferable adhesive is a curable adhesive composition which is cured by irradiation with an active energy ray or heating. Examples of the curable adhesive composition include a curable adhesive composition containing a radical polymerizable compound such as an acrylic compound, and a curable adhesive composition containing a cation polymerizable compound such as an epoxy compound. These compositions preferably contain a radical polymerization initiator or a cationic polymerization initiator, respectively.
The curable adhesive composition may further contain other additives such as an ion scavenger, an antioxidant, a chain transfer agent, a sensitizer, a thickener, a thermoplastic resin, a filler, a flow control agent, a plasticizer, and a defoaming agent without impairing the adhesiveness thereof. Examples of the ion scavenger include powdery inorganic compounds such as bismuth, antimony, magnesium, aluminum, calcium, titanium, and mixtures thereof, and examples of the antioxidant include hindered phenol antioxidants.
The polarizing plate and the protective film can be bonded by applying the curable adhesive composition to the bonding surface of the polarizing plate or the protective film, or to the bonding surface of both, bonding the polarizing plate and the protective film to each other on the surface to which the adhesive is applied, and curing the uncured adhesive layer by irradiation with an active energy ray or heating. As a method for applying the adhesive, various application methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used.
The curable adhesive composition can be used as a solvent-free adhesive substantially containing no solvent, and since there is an optimum viscosity range for each application method, a solvent may be contained to adjust the viscosity. The solvent is preferably an organic solvent which does not deteriorate the optical performance of the polarizing plate and dissolves each component represented by an epoxy compound well, and for example, hydrocarbons represented by toluene, esters represented by ethyl acetate, and the like can be used.
When the adhesive composition is cured by irradiation with an active energy ray, various active energy rays described above can be used, but ultraviolet rays are preferably used because of ease of handling, ease of controlling the amount of irradiation light, and the like. The irradiation intensity and the irradiation amount of the active energy ray such as ultraviolet ray can be appropriately determined so as to ensure appropriate productivity within a range that does not affect various optical properties represented by the degree of polarization of the polarizing plate and various optical properties represented by the transparency and the retardation characteristics of the protective film.
[ Binders ]
The pressure-sensitive adhesive may be any pressure-sensitive adhesive having excellent optical transparency and excellent pressure-sensitive adhesive properties including appropriate wettability, cohesiveness, adhesiveness, and the like, but a pressure-sensitive adhesive having excellent durability and the like is preferable. Specifically, as the adhesive for forming the adhesive layer, an adhesive containing an acrylic resin (acrylic adhesive) is preferable.
The acrylic resin contained in the acrylic adhesive is a resin containing, as a main monomer, an alkyl acrylate such as butyl acrylate, ethyl acrylate, isooctyl acrylate, or 2-ethylhexyl acrylate. The acrylic resin is usually copolymerized with a polar monomer. The polar monomer is a compound having a polymerizable unsaturated bond and a polar functional group, wherein the polymerizable unsaturated bond is usually derived from a (meth) acryloyl group, and the polar functional group may be a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, or the like. Specific examples of the polar monomer include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, 2-N, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.
In addition, a crosslinking agent is generally blended with the acrylic resin in the acrylic adhesive.
Typical examples of the crosslinking agent include isocyanate compounds having at least 2 isocyanate groups (-NCO) in the molecule.
Various additives may be further blended in the binder. Examples of suitable additives include silane coupling agents and antistatic agents. The silane coupling agent is effective in improving adhesion to glass. Antistatic agents are effective in reducing or preventing the occurrence of static electricity.
The adhesive layer may be formed by: a method in which an adhesive composition in which the above adhesive component is dissolved in an organic solvent is prepared, and the adhesive composition is directly applied to a polarizing plate or a protective film, followed by drying to remove the solvent; alternatively, a method of applying the above adhesive composition to a release-treated surface of a base film comprising a resin film subjected to release treatment, drying the adhesive composition to remove the solvent, forming an adhesive layer, and bonding the adhesive layer to a transparent protective film to transfer the adhesive layer. When a pressure-sensitive adhesive layer is formed on a transparent protective film by the former direct coating method, it is common practice to: a resin film (also referred to as a separator) subjected to a release treatment is bonded to the surface thereof, and the surface of the pressure-sensitive adhesive layer is temporarily protected by adhesion until use. The latter transfer method is often employed from the viewpoint of workability of the adhesive composition as an organic solvent solution, and in this case, the release-treated base film used for forming the adhesive layer first can be used as a separator directly after being bonded to the polarizing plate, which is also advantageous from the viewpoint of handling.
It is also useful to subject the surface of the polarizing plate, the surface of the protective film, and the surface of the adhesive agent to corona treatment, plasma treatment, or the like in advance before laminating the adhesive agent on the polarizing plate or the protective film.
[ lamination of other members ]
An adhesive layer may be used for laminating the polarizing plate and the liquid crystal cell, and an adhesive or an adhesive may be used for laminating the adhesive layer of the reflective polarizer 50. The pressure-sensitive adhesive layer may be any pressure-sensitive adhesive layer having excellent optical transparency and excellent pressure-sensitive adhesive properties such as appropriate wettability, cohesiveness, and adhesiveness, but is preferably an electrically excellent pressure-sensitive adhesive layer having excellent durability. Specifically, as the adhesive for forming the adhesive layer, an adhesive containing an acrylic resin (acrylic adhesive) is preferable.
As the pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer similar to that used for bonding the polarizing plate and the protective film can be used. The adhesives may be different from each other, or the same adhesive may be used.
It is also useful to subject the polarizer surface, the protective film surface, and the adhesive surface to corona treatment, plasma treatment, or the like in advance before laminating the adhesive on the polarizing plate. In addition, when the reflection type polarizing plate is laminated, it is also useful to perform corona treatment, plasma treatment, or the like on the bonding surface and the adhesive surface of the reflection type polarizing plate 50 in advance. The adhesive layer used for laminating the reflective polarizer 50 is preferably 25 μm or less. More preferably 15 μm or less. The thickness of the pressure-sensitive adhesive layer is usually 3 μm or more.
[ liquid Crystal cell, liquid Crystal Panel ]
The liquid crystal cell has 2 cell substrates and a liquid crystal layer sandwiched between the two substrates. The unit substrate is usually made of glass in many cases, but may be a plastic substrate. The liquid crystal cell itself used in the liquid crystal panel of the present invention may be formed of various liquid crystal cells (for example, known modes such as IPS mode, VA mode, and TN mode as drive modes) used in this field. Recently, the liquid crystal cell has a small thickness and a low rigidity, and thus warping is very likely to occur when the liquid crystal panel is manufactured. Therefore, the conventional polarizing plate group capable of reducing the warpage of the liquid crystal panel can exert an effect on a liquid crystal cell having a large thickness (for example, 0.5mm or more), but when it is applied to a thin liquid crystal cell, the liquid crystal panel may be warped. However, according to the polarizing plate group of the present invention, even if the thickness of the liquid crystal cell is 0.4mm or less, further 0.3mm or less, the warpage can be remarkably reduced. In the present invention, the thickness of the liquid crystal cell includes the thickness of the liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer.
As shown in fig. 5, the polarizing plate set of the present invention is bonded to a liquid crystal cell via an adhesive layer, whereby a liquid crystal panel can be produced.
From another point of view, the absolute value of the warpage of the liquid crystal panel of the present invention when heated at 85 ℃ for 250 hours is 0.5mm or less, preferably 0.3mm or less. By bonding the polarizing plate set of the present invention to the liquid crystal cell, the liquid crystal panel of the present invention is suppressed from warping in a high-temperature environment, and becomes a front panel-integrated liquid crystal display panel housed in a case of a final product.
The polarizing plate is preferably rectangular in shape having long sides and short sides, from the viewpoint of making the effect of the present invention more remarkable. In the case where the polarizing plate of the present invention has a rectangular shape having long sides and short sides, the ratio of the length of the long sides to the length of the short sides is preferably 10: 1 to 1: 1, and more preferably 2: 1 to 1: 1. The polarizing plate is preferably 50mm or more, more preferably 150mm or more in length of the long side, and preferably 40mm or more, more preferably 80mm or more in length of the short side. Specifically, the size of the polarizing plate of the present invention is, for example, preferably 2.7 type (55mm × 41mm) or more, and preferably 11.3 type (174mm × 231mm) or less.
[ examples ]
The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. In the examples, "part(s)" and "%" indicating the content or amount used are based on weight unless otherwise specified. The measurement of each physical property in the following examples was performed by the following method.
(1) Measurement of thickness:
the measurement was carried out using a digital micrometer "MH-15M" manufactured by Nikon K.K.
(2) Measurement of contractile force
The polarizing plate having no adhesive layer for bonding to the liquid crystal cell was cut into a width of 2mm and a length of 50mm by SUPER CUTTER (manufactured by Seiko Seikagaku Kogyo Co., Ltd.) so that the direction of the measurement shrinkage force was set to the longer side. The obtained strip chip was used as a test piece. The shrinkage force of the test piece was measured using a thermomechanical analyzer (model TMA/6100, manufactured by SII Nanotechnology Co., Ltd.). The measurement was performed in a constant-dimension mode, and the inter-chuck distance was set to 10 mm. The test piece was left in a room of 23 ℃ and 55% for 24 hours or more, and then the temperature in the sample room was set to be increased from 23 ℃ to 80 ℃ for 1 minute, and after the temperature was increased, the temperature in the sample room was set to be maintained at 80 ℃. After the temperature was raised, the test piece was left to stand for a further 4 hours, and then the shrinkage force in the longitudinal direction of the test piece was measured at 80 ℃. In this measurement, the static load was set to 0mN, and a SUS probe was used as a holder.
(3) Measurement of warpage amount of liquid crystal panel
The amount of warpage of the produced liquid crystal panel in a high-temperature environment was measured by the following method. First, the liquid crystal display panel thus produced was left to stand at 85 ℃ for 250 hours, and then the 1 st polarizing plate was placed on the top of the measuring table of a two-dimensional measuring instrument "NEXIV VMR-12072" manufactured by nikon corporation. Then, the focal point is focused on the surface of the measurement table, the focal point is focused on the 4 corners, the center of the 4 sides, and the center of the surface of the liquid crystal panel based on the focal point, the distance from the focal point based on the focal point is measured, the longest distance in absolute value from the measurement table is used as the warpage amount, the warpage which is warped deep in the observation side surface plate of the liquid crystal panel is used as the positive warpage, and the warpage which is warped deep in the back surface side surface plate is used as the negative warpage. The results are summarized in Table 1.
(4) Moisture permeability measurement of protective film
The moisture permeability was measured according to the cup method specified in JIS Z0208 under the conditions of 40 ℃ and 90% relative humidity.
[ example 1]
The observation-side polarizing plate was produced in the following manner. A polyvinyl alcohol film (average degree of polymerization: 2400, degree of saponification: 99.9 mol% or more) having a thickness of 30 μm was uniaxially stretched to about 5 times in the longitudinal direction by dry stretching, immersed in pure water at 60 ℃ for 1 minute while being kept under tension, and then immersed in an aqueous solution at 28 ℃ for 60 seconds, wherein the weight ratio of iodine/potassium iodide/water was 0.05/5/100. Then, the plate was immersed in an aqueous solution at 70 ℃ having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 for 300 seconds. Subsequently, the substrate was washed with pure water at 26 ℃ for 20 seconds and then dried at 65 ℃ to obtain a polarizing plate having a thickness of 12 μm and an iodine-oriented layer adsorbed on the polyvinyl alcohol film.
Then, 3 parts by weight of carboxyl-modified polyvinyl alcohol ("KL-318", manufactured by Lely corporation) was dissolved in 100 parts by weight of water to prepare an aqueous polyvinyl alcohol solution, and a water-soluble polyamide-epoxy resin ("Sumirezresin (registered trademark)) 65 (manufactured by Sumitomo chemical Co., Ltd.) was mixed in an amount of 1.5 parts by weight per 100 parts by weight of water to both sides of the polarizing plate0(30) ", solid content concentration 30 wt%", triacetyl cellulose film (trade name "KC 2 UA" manufactured by Konica Minolta Opto corporation) having a thickness of 25 μm as a protective film and norbornene film (trade name "ARTON (registered trademark)" manufactured by JSR corporation) having a thickness of 15 μm and an in-plane retardation value R at a wavelength of 590nm were laminated to each other00nm, thickness direction phase difference value Rth0nm ]. The polarizing plate was dried at 80 ℃ for 5 minutes and cured at 40 ℃ for 168 hours. An adhesive having a thickness of 20 μm (trade name "# KT" manufactured by LINTEC K.) was applied to the other surface of the polarizing plate to obtain an observation-side polarizing plate.
The rear-side polarizing plate was produced in the following manner. A polyvinyl alcohol film (average degree of polymerization: 2400, degree of saponification: 99.9 mol% or more) having a thickness of 20 μm was uniaxially stretched to about 5 times in the longitudinal direction by dry stretching, immersed in pure water at 60 ℃ for 1 minute while being kept under tension, and then immersed in an aqueous solution at 28 ℃ for 60 seconds, wherein the weight ratio of iodine/potassium iodide/water was 0.05/5/100. Then, the plate was immersed in an aqueous solution at 65 ℃ having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 for 300 seconds. Subsequently, the substrate was washed with pure water at 26 ℃ for 20 seconds and then dried at 65 ℃ to obtain a polarizing plate having a thickness of 7 μm and an iodine-oriented film adsorbed on the polyvinyl alcohol film.
The aqueous adhesive was applied to one surface of a polarizing plate, a norbornene-based film having a thickness of 13 μm (trade name "ZEONOR (registered trademark)" manufactured by japan ZEON corporation) as a protective film and an in-plane retardation value Re of 0.8nm at a wavelength of 590nm were applied thereto, and the resultant was dried at 80 ℃ for 5 minutes and cured at 40 ℃ for 168 hours. A5 μ M thick adhesive (trade name "# L2" manufactured by LINTEC K.K.) was attached to the other surface of the polarizer, and a 26 μ M thick brightness enhancement Film (trade name "Advanced Polarized Film, Version 3" manufactured by 3M) was attached thereto. Then, a pressure-sensitive adhesive having a thickness of 20 μm (trade name "# KT" manufactured by LINTEC K.) was applied to the norbornene film side to obtain a back-side polarizing plate.
The thickness of the observation-side polarizing plate was 52 μm, the thickness of the back-side polarizing plate was 51 μm, and the thickness ratio was 1.02. At 40 deg.C and 90% relative humidityThe norbornene film used for the back-side polarizing plate had a moisture permeability of 30 g/(m)2·24hr)。
[ example 2]
The observation-side polarizing plate was produced in the following manner. A polarizing plate having a thickness of 12 μm was produced in the same manner as in example 1, and the water-based adhesive described in example 1 was applied to both surfaces thereof, and a film in which an acrylic hard coat having a thickness of 7 μm and a norbornene-based film having a thickness of 23 μm (trade name "ZEONOR (registered trademark)" made by japan ZEON corporation) were stacked on a triacetyl cellulose film having a thickness of 25 μm (trade name "KC 2 UA" made by Konica Minolta Opto corporation) as a protective film were laminated. The polarizing plate was dried at 80 ℃ for 5 minutes and cured at 40 ℃ for 168 hours. Then, an adhesive having a thickness of 20 μm (trade name "# KT" manufactured by LINTEC K.) was applied to the norbornene film side to obtain an observation side polarizing plate.
The back-side polarizing plate used in example 1 was used as the back-side polarizing plate.
The thickness of the observation-side polarizing plate was 67 μm, the thickness of the back-side polarizing plate was 51 μm, and the thickness ratio was 1.31.
Comparative example 1
The observation-side polarizing plate was produced in the following manner. A polarizing plate having a thickness of 7 μm was produced in the same manner as in example 1 except that the temperature of the aqueous solution containing potassium iodide/boric acid/water was set to 70 ℃, the aqueous adhesive described in example 1 was applied to both surfaces of the polarizing plate, and a film having an acrylic hard coat layer having a thickness of 7 μm and a triacetyl cellulose film having a thickness of 20 μm (trade name "KC 2 CTW" manufactured by Konica Minolta Opto K.) were laminated as protective films on a triacetyl cellulose film having a thickness of 25 μm (trade name "KC 2 UA" manufactured by Konica Minolta Opto K.), and an in-plane phase difference R at a wavelength of 590nm01.2nm, thickness direction phase difference value Rth1.3nm ]. The mixture was dried at 80 ℃ for 5 minutes and cured at 40 ℃ for 168 hours. Then, a binder having a thickness of 20 μm (trade name "# KT" manufactured by LINTEC K.) was applied to the triacetyl cellulose film having a thickness of 20 μm to obtain an observation-side polarizing plate.
The rear-side polarizing plate was produced in the following manner. A polarizing plate having a thickness of 12 μm was produced in the same manner as in example 1 except that the temperature of the aqueous solution containing potassium iodide/boric acid/water was 65 ℃, the aqueous adhesive described in example 1 was applied to both surfaces thereof, and a triacetyl cellulose film having a thickness of 25 μm [ trade name "KC 2 UA" manufactured by Konica Minolta Opto corporation ] and a norbornene film having a thickness of 23 μm [ trade name "ZEONOR (registered trademark)" manufactured by japan ZEON corporation ] were bonded as protective films. The mixture was dried at 80 ℃ for 5 minutes and cured at 40 ℃ for 168 hours. A5 μ M thick adhesive (trade name "# L2" manufactured by LINTEC K.K.) was bonded to the surface of a triacetyl cellulose Film, and a 26 μ M thick brightness enhancement Film (trade name "Advanced Polarized Film, Version 3" manufactured by 3M) was bonded thereto. Then, a pressure-sensitive adhesive having a thickness of 20 μm (trade name "# KT" manufactured by LINTEC K.) was applied to the norbornene film side to obtain a back-side polarizing plate.
The thickness of the observation-side polarizing plate was 59 μm, the thickness of the back-side polarizing plate was 91 μm, and the thickness ratio was 0.65. The triacetyl cellulose film has a moisture permeability of 1200 g/(m) at a temperature of 40 ℃ and a relative humidity of 90%224hr), the moisture permeability of the norbornene-based film was 6 g/(m)2·24hr)。
Comparative example 2
The observation-side polarizing plate used in example 1 was used as the observation-side polarizing plate.
The back-side polarizing plate used in comparative example 1 was used as the back-side polarizing plate.
The thickness of the observation-side polarizing plate was 52 μm, the thickness of the back-side polarizing plate was 91 μm, and the thickness ratio was 0.57.
Comparative example 3
The observation-side polarizing plate used in example 2 was used as the observation-side polarizing plate.
The rear-side polarizing plate was produced in the following manner. A polarizing plate having a thickness of 12 μm was produced in the same manner as in example 1 except that the temperature of the aqueous solution containing potassium iodide/boric acid/water was 65 ℃, the aqueous adhesive described in example 1 was applied to both surfaces of the polarizing plate, and a protective film having a thickness of 25 μm was bonded to the polarizing plateA triacetyl cellulose film (trade name "KC 2 UA" manufactured by Konica Minolta Opto Co., Ltd.) and a norbornene film (trade name "ARTON (registered trade name)" manufactured by JSR Co., Ltd.) having a thickness of 15 μm and an in-plane retardation value R at a wavelength of 590nm were not stretched00nm, thickness direction phase difference value Rth0nm ]. The polarizing plate was dried at 80 ℃ for 5 minutes and cured at 40 ℃ for 168 hours. A5 μ M thick adhesive (trade name "# L2" manufactured by LINTEC K.K.) was bonded to the surface of a triacetyl cellulose Film, and a 26 μ M thick brightness enhancement Film (trade name "Advanced Polarized Film, Version 3" manufactured by 3M) was bonded thereto. Then, a pressure-sensitive adhesive having a thickness of 20 μm (trade name "# KT" manufactured by LINTEC K.) was applied to the norbornene film side to obtain a back-side polarizing plate. The triacetyl cellulose film has a moisture permeability of 1200 g/(m) at a temperature of 40 ℃ and a relative humidity of 90%224hr), the moisture permeability of the norbornene-based film was 140 g/(m)2·24hr)。
The thickness of the observation-side polarizing plate was 67 μm, the thickness of the back-side polarizing plate was 83 μm, and the thickness ratio was 0.81.
Comparative example 4
The observation-side polarizing plate used in example 2 was used as the observation-side polarizing plate.
The rear-side polarizing plate was produced in the following manner. First, a polyvinyl alcohol film (having an average polymerization degree of about 2,400 and a saponification degree of 99.9 mol% or more) having a thickness of 60 μm was uniaxially stretched to about 5 times by dry stretching, immersed in pure water at 60 ℃ for 1 minute while being kept under tension, and then immersed in an aqueous solution at 28 ℃ having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 for 60 seconds. Then, the plate was immersed in an aqueous solution at 65 ℃ having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 for 300 seconds. Subsequently, the substrate was washed with pure water at 26 ℃ for 20 seconds and then dried at 65 ℃ to obtain a polarizing plate having a thickness of 23 μm and an iodine-oriented layer adsorbed on the polyvinyl alcohol film.
Then, the water-based adhesive described in example 1 was applied to both surfaces of the 23 μm polarizing plate, and a triacetyl cellulose film having a thickness of 40 μm [ trade name "KC 4 UY" manufactured by Konica Minolta Opto K.K. ] as a protective film and not stretched was laminatedA norbornene-based film having a thickness of 23 μm [ trade name "ZEONOR (registered trademark)" made by ZEON corporation of Japan ]. The polarizing plate was dried at 80 ℃ for 5 minutes and cured at 40 ℃ for 168 hours. Then, a 5 μ M thick adhesive (trade name "# L2" manufactured by LINTEC K.K.) was applied to the surface of the triacetyl cellulose Film, and a 26 μ M thick brightness enhancement Film (trade name "Advanced Polarized Film, Version 3" manufactured by 3M) was applied thereon. Then, a pressure-sensitive adhesive having a thickness of 20 μm (trade name "# KT" manufactured by LINTEC K.) was applied to the norbornene film side to obtain a back-side polarizing plate. The triacetyl cellulose film has a moisture permeability of 830 g/(m) at a temperature of 40 deg.C and a relative humidity of 90%224hr), the moisture permeability of the norbornene-based film was 6 g/(m)2·24hr)。
The thickness of the observation-side polarizing plate was 67 μm, the thickness of the back-side polarizing plate was 116 μm, and the thickness ratio was 0.58.
The above results are shown in table 1.
[ Table 1]
Industrial applicability
According to the present invention, it is possible to eliminate warping of the liquid crystal panel in a high-temperature environment and to obtain a liquid crystal panel housed in a case of a final product in a high-temperature environment, and therefore, the present invention is useful.
Description of the symbols
10 st and 11 nd polarizing plates
20. 21 polarizing plate
30a, 30b, 31a, 31b protective film
32. 33 adhesive layer
60 F1
61 F2
62 F3
63 F4
70 liquid crystal layer
71 substrate
72 liquid crystal cell
Claims (6)
1. A polarizing plate group comprising a 1 st polarizing plate disposed on the viewing side of a liquid crystal cell and a 2 nd polarizing plate disposed on the back side of the liquid crystal cell,
the 2 nd polarizing plate has a reflective polarizer,
the ratio of the thickness of the observation side polarizing plate (1) to the thickness of the rear side polarizing plate (2) is set to 1.01 to 1.31,
(F1 XF 2)/(F3 XF 4) is 0.5 to 4.39, where F1 represents a shrinkage force per 2mm width in the absorption axis direction when the 1 st polarizing plate is held at 80 ℃ for 4 hours, F2 represents a shrinkage force per 2mm width in the transmission axis direction when the 2 nd polarizing plate is held at 80 ℃ for 4 hours, F3 represents a shrinkage force per 2mm width in the absorption axis direction when the 2 nd polarizing plate is held at 80 ℃ for 4 hours, and F4 represents a shrinkage force per 2mm width in the transmission axis direction,
f1 is more than 1.6N/2mm and less than 3N/2mm,
f2 is 0.00N/2mm or more and 0.3N/2mm or less,
f3 is 3N/2mm or less,
f4 is 0.00N/2mm or more and 0.3N/2mm or less.
2. The polarizing plate group according to claim 1, wherein each of the 1 st and 2 nd polarizing plates has a polarizer including a polyvinyl alcohol-based resin film, and each of the polarizers has a thickness of 20 μm or less.
3. The polarizing plate group according to claim 2, wherein the polarizer included in the 1 st polarizing plate has a thickness of 10 μm or more, and the polarizer included in the 2 nd polarizing plate has a thickness of 10 μm or less.
4. The polarizing plate group according to claim 2 or 3, wherein the 2 nd polarizing plate has a protective film laminated on one surface of the polarizer and the reflective polarizer laminated on the other surface.
5. The method of claim 4The polarizing plate set of (1), wherein the protective film has a moisture permeability of 500 g/(m)224hr) or less.
6. A liquid crystal panel comprising the polarizing plate group according to any one of claims 1 to 5 and a liquid crystal cell, wherein the liquid crystal cell has a thickness of 0.4mm or less.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2016036952A JP2017156399A (en) | 2016-02-29 | 2016-02-29 | Set of polarizing plates and liquid crystal panel |
| JP2016-036952 | 2016-02-29 |
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| Publication Number | Publication Date |
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| CN107132606A CN107132606A (en) | 2017-09-05 |
| CN107132606B true CN107132606B (en) | 2020-08-28 |
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| JP (1) | JP2017156399A (en) |
| KR (1) | KR20170101810A (en) |
| CN (1) | CN107132606B (en) |
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|---|---|---|---|---|
| TWI672545B (en) * | 2018-05-04 | 2019-09-21 | 住華科技股份有限公司 | Display device |
| KR102621169B1 (en) * | 2019-01-11 | 2024-01-05 | 산진 옵토일렉트로닉스 (난징) 컴퍼니 리미티드 | Preparation Method of Polarizing Plate |
| KR20200087435A (en) * | 2019-01-11 | 2020-07-21 | 주식회사 엘지화학 | Polarizing Plate |
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Also Published As
| Publication number | Publication date |
|---|---|
| KR20170101810A (en) | 2017-09-06 |
| CN107132606A (en) | 2017-09-05 |
| TW201734515A (en) | 2017-10-01 |
| JP2017156399A (en) | 2017-09-07 |
| TWI706172B (en) | 2020-10-01 |
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