KR20160007389A - Polarizing plate and liquid crystal display device - Google Patents
Polarizing plate and liquid crystal display device Download PDFInfo
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- KR20160007389A KR20160007389A KR1020150096505A KR20150096505A KR20160007389A KR 20160007389 A KR20160007389 A KR 20160007389A KR 1020150096505 A KR1020150096505 A KR 1020150096505A KR 20150096505 A KR20150096505 A KR 20150096505A KR 20160007389 A KR20160007389 A KR 20160007389A
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
- B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
- B32B17/08—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of cellulosic plastic substance or gelatin
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
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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
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- Physics & Mathematics (AREA)
- Polarising Elements (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Mathematical Physics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Liquid Crystal (AREA)
- Laminated Bodies (AREA)
Abstract
Description
The present invention relates to a polarizing plate and a liquid crystal display.
With the recent commercialization of liquid crystal display devices, a high durability is required for a polarizing plate constituting the liquid crystal display device. For example, Japanese Unexamined Patent Publication (Kokai) No. 1-145645 (Patent Document 1) discloses a protective film in which the linear expansion coefficient in the direction parallel to the transmission axis of the polarizing film in the protective film is smaller than the linear expansion coefficient in the transmission axis direction of the polarizing film (Cracks) of a polarizing film in an environment (a cold / heat shock environment) in which there is an abrupt temperature change such as a repetition of a low temperature and a high temperature is suppressed in a polarizing plate obtained by laminating it on a polarizing film.
On the other hand, the above-mentioned polarizing plate has insufficient durability in an environment in which there is a rapid temperature change such as repeating low temperature and high temperature under a high humidity atmosphere (condensation cold / heat shock environment), and there is room for improvement.
An object of the present invention is to provide a polarizer excellent in durability under a cold and heat shock environment as well as in a condensation cold and heat impact environment.
That is, the present invention provides a polarizing plate in which a first protective film having a thickness of 50 m or less is laminated on at least one surface of a polarizing film having a thickness of 30 m or less, wherein a ratio of a thickness of the first protective film to a thickness of the polarizing film is larger than 1.9 Further, the polarizing film was adjusted for 24 hours in an atmosphere having a temperature of 23 캜 and a relative humidity of 55%, and subsequently heated in an oven from 25 캜 to 85 캜 at a rate of 2 캜 / min. Wherein the amount of deformation of the polarizing film in the direction of the transmission axis when the polarizing film is heated for 1 minute after adhering 0.3 ml of pure water at 23 占 폚 is 700 占 or less.
In the above-mentioned polarizing plate, it is preferable that a first protective film is laminated on one side of the polarizing film and a second protective film which is the same thickness as the first protective film or thinner than the first protective film is laminated on the other side.
In the polarizing plate described above, at least one of the first and second protective films preferably has retardation (Re) of 10 nm or less at a wavelength of 590 nm and retardation (Rth) in the thickness direction at the same wavelength, And the absolute value of the retardation (Rth) in the thickness direction at a wavelength of 480 to 750 nm is 15 nm or less. The first and second protective films may be independently composed of a cellulose resin or a polyolefin resin.
The present invention also provides a liquid crystal display device in which the polarizing plate described in any one of the above is laminated on at least one surface of a liquid crystal cell.
According to the present invention, it is possible to provide a polarizing plate which does not generate cracks or the like in the polarizing film and is excellent in durability even in a cold / heat shock environment and a condensation cold / heat shock environment.
Fig. 1 is a layout diagram of a measurement jig and a polarizing film provided for measurement of deformation amount.
Fig. 2 is a schematic view of a polarizing film and a strain gauge adhered to each other.
Hereinafter, the present invention will be described.
[Polarizer]
The polarizing plate of the present invention has a structure in which a protective film having a thickness of 50 占 퐉 or less is laminated on at least one surface of a polarizing film having a thickness of 30 占 퐉 or less.
<Polarizing Film>
The polarizing film which is a constituent member of the polarizing plate usually has a step of staining the dyed film made of a polyvinyl alcohol resin with a dichroic dye to adsorb the dichroic dye (dyeing treatment step), a step of treating with a boric acid aqueous solution A boric acid treatment step), a water washing step (water washing step), and a film drying step (drying step). At this time, the polyvinyl alcohol-based resin film is stretched before or after the dyeing process, or after the dyeing process.
The polyvinyl alcohol resin constituting the fabric film can be produced by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate and other monomers copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamides having an ammonium group, and the like.
The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified or may be polyvinyl formal or polyvinyl acetal modified with aldehyde, for example. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.
Such a polyvinyl alcohol resin film is formed into a fabric film as described above. The polyvinyl alcohol resin can be formed by a known method. The film thickness of the raw film is, for example, about 10 to 150 mu m, preferably about 10 to 100 mu m.
In the method for producing a polarizing film, the film to be applied to the polyvinyl alcohol resin film may be uniaxially oriented or biaxially oriented. For example, in the case of performing uniaxial stretching on a polyvinyl alcohol-based resin film, stretching may be performed before or simultaneously with the dyeing treatment step, or after the dyeing treatment step, as described above. In the case where uniaxial stretching is performed after the dyeing treatment step, the stretching may be carried out before the boric acid treatment step or during the boric acid treatment step. Of course, uniaxial stretching can also be performed in a plurality of steps disclosed herein. As the uniaxial stretching, a method of stretching between rolls having different circumferential velocities, a method of stretching using hot rolls, or the like can be adopted. The uniaxial stretching may be performed by dry stretching in which stretching is performed in the air or by wet stretching in which a polyvinyl alcohol resin film is stretched by using a solvent such as water. The stretching magnification is usually about 3 to 8 times.
The dyeing treatment step can be carried out, for example, by immersing a polyvinyl alcohol resin film in an aqueous solution containing a dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye. It is preferable that the polyvinyl alcohol-based resin film is subjected to treatment in which it is immersed in water and swelled before dyeing.
When iodine is used as the dichroism dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide is generally employed.
The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution is usually about 20 to 40 占 폚. The immersion time (dyeing time) for this aqueous solution is usually about 20 to 1,800 seconds.
On the other hand, when a dichroic organic dye is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing a water-soluble dichroic organic dye is generally employed. The content of the dichroic organic dye in this aqueous solution is usually about 1 x 10-4 to 10 parts by weight, preferably 1 x 10-3 to 1 part by weight, per 100 parts by weight of water. The dye aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution of the dichroic organic dye is usually about 20 to 80 캜. The immersion time (dyeing time) for this aqueous solution is usually about 10 to 1,800 seconds.
The boric acid treatment step performed after dyeing with the dichroic dye can be carried out by dipping the dyed polyvinyl alcohol resin film in an aqueous solution of boric acid. The content of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous solution of boric acid contains potassium iodide. The content of potassium iodide in the aqueous solution of boric acid is usually about 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time for the boric acid aqueous solution is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 占 폚 or higher, preferably 50 to 85 占 폚, and more preferably 60 to 80 占 폚.
After the boric acid treatment step, the polyvinyl alcohol resin film is usually subjected to a water washing treatment step. The water washing treatment step can be carried out by, for example, a method of immersing the polyvinyl alcohol resin film after the boric acid treatment step in water or a method of spraying water on the film. When immersed in water, the temperature of the water is usually about 5 to 40 캜, and the immersion time is usually about 1 to 120 seconds.
The polyvinyl alcohol-based resin film is subjected to a drying step after the water-washing treatment step to become a polarizing film. The drying process can be performed using a hot-air dryer or a far-infrared heater. The temperature of the drying step is usually about 30 to 100 占 폚, preferably 50 to 80 占 폚. The time of the drying step is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By the drying step, the moisture content in the polarizing film is reduced to a practical degree. The moisture content thereof is usually about 5 to 20% by weight, preferably 8 to 15% by weight at room temperature (23 캜). When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and it may be damaged or broken after drying. When the moisture content exceeds 20% by weight, the thermal stability tends to be insufficient.
Here, the moisture content means the ratio (% by weight) of water in the film to the dry weight of the polyvinyl alcohol-based resin film, and can be measured by drying a sample cut out of a part of the film in a heating oven or the like. Specifically, from the weight of the cut sample before drying and the weight after drying, it is defined by the following formula.
Moisture content = [(weight before drying - weight after drying) / weight before drying] × 100
As described above, a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be produced. The thickness of the polarizing film may be, for example, about 1 to 40 mu m.
In the present invention, among the above-described polarizing films, a polarizing film having a humidity of 24 hours and a humidity of 23% at a temperature of 23 캜 and a relative humidity of 55% is heated in an oven at 25 캜 to 85 캜 at a rate of 2 캜 / (Absolute value) of the length of the polarizing film in the direction of the transmission axis of the polarizing film produced in one minute after the attachment, and the length in the transmission axis direction of the polarizing film before adhering water The deformation amount is set to be 700 占 or less, preferably 650 占 or less. By employing a polarizing film having a deformation amount of 700 占 이하 or less and combining this with a protective film to be described later, a polarizing plate having excellent durability is obtained even if condensation occurs in a polarizing plate under an environment in which high temperature conditions and low temperature conditions are repeated under a high humidity atmosphere .
Here, the deformation means the amount of change per unit length when a load is applied to an object. The ratio of the elongation at this time is deformation amount, and the deformation amount is a value obtained as follows.
When a tensile force (or a compressive force) P is applied to a material having a length L 0 , a stress σ corresponding to the tensile force (or compressive force) P is generated in the material. The length L of the material is deformed to be long or short. The amount of deformation is obtained as a ratio of the deformation length (? L) of the material to the length (L 0 ), and is expressed by the following formula (1).
? = (LL 0 ) / L 0 =? L / L 0 (1)
Measurement of the maximum variation of the length of the polarizing film in the transmission axis direction required for the calculation of the deformation amount is performed as follows. Fig. 1 shows a measuring jig A for measuring the maximum variation and a sectional view (B) for assembling the polarizing film and the measuring jig, respectively. Referring to the drawings, the polarizing film is cut into pieces each having a size of 100 mm × 100 mm in the direction of the absorption axis × the transmission axis. On both sides of the
The
As shown in Fig. 2, the strain gauge for measuring the maximum variation of the length of the polarizing film in the transmission axis direction is arranged to be parallel to the transmission axis direction (direction perpendicular to the stretching direction) of the polarizing film. The strain gage is disposed at the center of the polarizing film through an adhesive. As this adhesive, a commercially available adhesive such as a cyanoacrylate adhesive can be used.
At the time of measuring the maximum change amount, pure water at 23 DEG C dropped onto the film piece of the polarizing film is dropped onto the portion where the polarizing film adheres to the strain gage.
<Protection film>
A polarizing plate of the present invention is a polarizing film in which a first protective film having a thickness of 50 탆 or less is laminated on at least one surface of a polarizing film as the thickest protective film and the ratio of the thickness of the first protective film to the thickness of the polarizing film is larger than 1.9. The ratio of this thickness is preferably 2 or more, and more preferably 40 or less.
In the present invention, it is preferable that the first protective film is laminated on at least one surface of the polarizing film, but the second protective film which is the same thickness as the first protective film or thinner than the first protective film is laminated on the other surface of the polarizing film Do. The first protective film and the second protective film may be the same or different.
It is preferable that the first and second protective films are each composed of a resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property and the like. As such a resin, for example, a polyolefin-based resin including an acrylic resin typified by a methyl methacrylate-based resin, a chained polyolefin-based resin typified by a polypropylene-based resin and a cyclic polyolefin-based resin, , Polyethyleneterephthalate resin, polybutylene terephthalate resin, polyvinyl chloride resin, styrene resin, acrylonitrile styrene copolymer resin, acrylonitrile-butadiene styrene copolymer resin, polyvinyl acetate resin , A polyvinylidene chloride resin, a polyamide resin, a polyacetal resin, a polycarbonate resin, a modified polyphenylene ether resin, a polysulfone resin, a polyether sulfone resin, a polyarylate resin, Based resin, a polyimide-based resin, and the like. These resins may be used alone or in combination of two or more. A resin obtained by subjecting any of these polymers to polymer modification may also be used as a resin constituting the protective film. The polymer modification includes, for example, copolymerization, crosslinking, molecular terminal modification, stereoregularity control, mixing involving reactions between different polymers, and the like.
Of the above resins, acrylic resins, polyolefin resins, cellulose resins and polyethylene terephthalate resins are preferably used.
The acrylic resin is generally a polymer containing methacrylic acid ester as a main component and may be a copolymer in which a small amount of another comonomer component is copolymerized. Among these acrylic resins, a methyl methacrylate resin containing 50% by weight or more of a structural unit derived from methyl methacrylate based on the total amount of the resin is preferable. In the methyl methacrylate resin, the content of the structural unit derived from methyl methacrylate is preferably 70% by weight or more based on the total amount of the methyl methacrylate resin. Or may be a homopolymer of methyl methacrylate having a content of 100% by weight.
The methyl methacrylate resin can be usually obtained by polymerizing a monofunctional monomer having methyl methacrylate as a main component under the coexistence of a radical polymerization initiator and a chain transfer agent. In the monofunctional monomer, in addition to methyl methacrylate, a copolymerizable component may be blended and copolymerized. In some cases, a small amount of a polyfunctional monomer is added to a monofunctional monomer having methyl methacrylate as a main component and copolymerized with the monofunctional monomer.
Examples of the monofunctional monomer copolymerizable with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate Methacrylic acid esters other than methyl methacrylate such as 2-hydroxyethyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, and 2-ethylhexyl acrylate; Acrylic acid hydroxyalkyl esters such as hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate; Unsaturated acids such as acrylic acid, methacrylic acid, and acrylic acid; Halogenated styrenes such as chlorostyrene, and bromostyrene; Substituted styrenes such as vinyltoluene, and? -Methylstyrene; Unsaturated nitriles such as acrylonitrile, and methacrylonitrile; Unsaturated acid anhydrides such as maleic anhydride, and citraconic anhydride; Phenylmaleimide, and unsaturated imides such as cyclohexylmaleimide. These monomers may be copolymerized singly with methyl methacrylate, or may be copolymerized by combining two or more species.
Examples of the polyfunctional monomer copolymerizable with methyl methacrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate and tetraethylene glycol di (Meth) acrylate, or a compound obtained by esterifying both terminal hydroxyl groups of the oligomer with acrylic acid or methacrylic acid; A compound obtained by esterifying both terminal hydroxyl groups of propylene glycol or an oligomer thereof with acrylic acid or methacrylic acid; Compounds obtained by esterifying a hydroxyl group of a dihydric alcohol such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate and butanediol di (meth) acrylate with acrylic acid or methacrylic acid; A compound obtained by esterifying both terminal hydroxyl groups of bisphenol A, an alkylene oxide adduct of bisphenol A or a halogen substituent thereof with acrylic acid or methacrylic acid; Compounds obtained by esterifying a polyhydric alcohol such as trimethylol propane and pentaerythritol with acrylic acid or methacrylic acid; A compound in which an epoxy group of glycidyl acrylate or glycidyl methacrylate is ring-opened on the terminal hydroxyl group of a compound having two or more hydroxyl groups; A compound obtained by ring-opening addition of an epoxy group of glycidyl acrylate or glycidyl methacrylate to a dibasic acid such as succinic acid, adipic acid, terephthalic acid, phthalic acid and halogen substituents thereof, or an alkylene oxide adduct thereof; Allyl (meth) acrylate; And aromatic divinyl compounds such as divinylbenzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used when copolymerizing a multifunctional monomer.
The modified resin may also be used by reacting between the functional groups of the methyl methacrylate resin. Examples of the reaction between these functional groups include a condensation reaction between a methyl ester group of methyl acrylate and a hydroxyl group of 2- (hydroxymethyl) methyl acrylate in a polymer chain, a condensation reaction between a carboxyl group of acrylic acid and methyl 2- (hydroxymethyl) A dehydration condensation reaction in a polymer chain of a hydroxyl group, and the like.
Commercially available methyl methacrylate resins can be easily obtained. Commercially available products include, for example, "Sumipex" (registered trademark) sold by Sumitomo Chemical Co., Ltd., "Acrifet" (registered trademark) sold by Mitsubishi Rayon Co., Ltd., Asahi Kasei (Registered trademark) sold by Kuraray Co., Ltd .; "Arpetlea" (registered trademark) sold by Nippon Shokubai Co., Ltd. (registered trademark) Trademark).
The polyolefin-based resin includes a chain-like polyolefin-based resin and a cyclic polyolefin-based resin as described above. Typical examples of the chain-like polyolefin-based resin include a polyethylene-based resin and a polypropylene-based resin. Among them, a polypropylene resin is preferable. The polypropylene type resin is a polymer of a chain type olefin monomer containing propylene as a main component and is usually a chain type olefin type resin in which 80 mol% or more of the repeating units are composed of propylene. The polypropylene resin may be a homopolymer of propylene or a copolymer mainly composed of propylene and copolymerized with a comonomer copolymerizable therewith. The copolymerizable comonomer can be copolymerized in a proportion of about 1 to 20% by weight, preferably 3 to 10% by weight, based on the total amount of monomers to be copolymerized.
As the comonomer copolymerizable with propylene, ethylene, 1-butene or 1-hexene is preferable. Among them, it is preferable to copolymerize ethylene in a proportion of 1 to 20% by weight, preferably 3 to 10% by weight, in view of obtaining a polypropylene resin having a comparatively excellent transparency. When the copolymerization ratio of ethylene is 1% by weight or more, transparency is enhanced. On the other hand, when the copolymerization ratio of ethylene exceeds 20% by weight, the melting point of the resin is lowered and the heat resistance required for the protective film may be impaired.
The polypropylene resin preferably has a content of xylene-soluble component (CXS component: CXS is abbreviation of cold xylene soluble) at 20 ° C of 1 wt% or less, preferably 0.5 wt% or less More preferable. Among the polypropylene-based resins, a homopolymer of propylene having a CXS content of 1% by weight or less and 0.5% by weight or less is a suitable example.
The polypropylene-based resin can easily obtain a commercially available product. Examples of commercially available products include "Prime Polypro" (registered trademark) sold by Prime Polymer Co., Ltd., "Nova Tech" (registered trademark) sold by Nippon Polypro Corporation, and " (Registered trademark) sold by Sumitomo Chemical Co., Ltd., "Sumitomo Noble" (registered trademark) sold by Sumitomo Chemical Co., Ltd., and "Sun Allomer" (registered trademark) sold by Sun Allomer Co.,
The cyclic polyolefin resin is obtained by polymerizing a cyclic olefin monomer such as norbornene and other cyclopentadiene derivatives in the presence of a catalyst.
Examples of the cyclic polyolefin-based resin include ring-opening metathesis polymerization of cyclopentadiene, olefin or (meth) acrylic acid or its ester using norbornene or a derivative thereof obtained by the Diels-Alder reaction as a monomer, followed by hydrogen A resin obtained by the addition; A resin obtained by ring-opening metathesis polymerization of dicyclopentadiene, tetracyclododecene or a derivative thereof obtained by the Diels-Alder reaction from an olefin or (meth) acrylic acid or an ester thereof as a monomer, followed by hydrogenation; Norbornene, tetracyclododecene, derivatives thereof, and other cyclic olefin monomers are similarly subjected to ring-opening metathesis copolymerization followed by hydrogenation; And resins obtained by addition-copolymerizing a cyclic olefin such as norbornene, tetracyclododecene or a derivative thereof with an aromatic compound having a chain type olefin and / or a vinyl group.
The cyclic polyolefin-based resin can easily obtain commercially available products. Examples of commercially available products include "TOPAS" (registered trademark), "Aton" (registered trademark) sold by TOPAS ADVANCED POLYMERS GmbH and sold by JSR Corporation, "Zeonoa" and "Zeonex" sold by Nippon Zeon Co., Ltd., and "Apel" (registered trademark) sold by Mitsui Chemicals, Inc., and the like.
The cellulose-based resin may be an organic acid ester or a mixed organic acid ester of cellulose, in which a part or all of the hydrogen atoms in the hydroxyl group of the cellulose are substituted with an acetyl group, a propionyl group and / or a butyryl group. Examples thereof include acetate esters of cellulose, propionic acid esters, butyric acid esters, and mixed esters thereof. Among them, triacetylcellulose, diacetylcellulose, cellulose acetate propionate, cellulose acetate butyrate and the like are preferable.
The polyethylene terephthalate resin may be a resin composed of ethylene terephthalate in an amount of 80 mol% or more of the repeating units based on the total amount of the resin, and may contain other dicarboxylic acid component and / or other diol component. Examples of other dicarboxylic acid components include isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, 1,4-dicarboxycyclohexane, and the like. Examples of other diol components include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol .
These other dicarboxylic acid components and other diol components may be used in combination of two or more kinds, if necessary, and in combination with hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-beta-hydroxyethoxybenzoic acid You may. As the other copolymerization component, a dicarboxylic acid component or a diol component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond or the like may also be used.
Examples of the method for producing the polyethylene terephthalate resin include a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as necessary), a method of directly polycondensing a dialkyl ester of terephthalic acid and ethylene glycol A dialkyl ester of dicarboxylic acid or other diol) while transesterifying an ethylene glycol ester (and optionally other diol ester) of terephthalic acid (and optionally dicarboxylic acid) with a catalyst And a method of polycondensation in the presence of a catalyst. Further, if necessary, further solid phase polymerization may be carried out to increase the molecular weight or lower the low molecular weight component.
As the method for forming the resin as described above, a method according to each resin may be appropriately selected. For example, a solvent casting method in which a resin dissolved in a solvent is poured into a metal band or a drum and the solvent is removed by drying to obtain a film, a resin is heated to a temperature not lower than its melting temperature, And a melt extrusion method for obtaining a melt-extruded product. In the melt extrusion method, the single layer film may be extruded, or the multilayer film may be simultaneously extruded. Generally, for film formation of a polyolefin-based resin, a melt extrusion method is preferably employed from the viewpoint of productivity, and a solvent casting method is adopted for film formation of a cellulose-based resin.
A commercially available product of these resins can be easily obtained. Examples of commercially available methyl methacrylate resin films include "Techoloy" (registered trademark) sold by Sumitomo Chemical Co., Ltd., "Acrylite" sold by Mitsubishi Rayon Co., (Registered trademark) sold by Kuraray Co., Ltd. and "Paraglas" (registered trademark) sold by Kuraray Co., Ltd. sold by Asahi Kasei Co., (Registered trademark), " COMOGRASH " (registered trademark), " ARVITEA " (registered trademark) sold by Nippon Shokubai Co.,
Examples of commercially available products of polyolefin-based resin films include "Aton film" (a registered trademark of the company) sold by JSR Corporation and " (Registered trademark) sold by Nippon Zeon Co., Ltd., and the like.
Examples of commercially available products of the cellulose-based resin film include TAC film sold under the trade names " Fujitak (registered trademark) TD " and Konica Minolta Advanced Material Co., &Quot; KC series " (trade name).
Examples of commercially available products of the polyethylene terephthalate-based resin film include "Novacreia" (registered trademark) sold by Mitsubishi Chemical Corporation, "A-PET (trade name) Sheet ". Examples of commercially available products of the polypropylene resin films are sold under the trade names of "FILMAX CPP film" sold by FILMAX Co., "Suntox" sold by Sun and Tokus Co., and Dosselo Co., (Trade name) manufactured by Nippon Poly Ace Co., Ltd., which is sold by Doyle Film Processing Co., Ltd., which is sold by Toyobo Co., Ltd., "Nippon Poly Ace" sold and "Daiko FC" sold by Futamura Chemical Co., Ltd., and the like.
The first and / or second protective films are each composed of a resin as described above, but may be given a retardation (retardation) by being subjected to a stretching treatment or a shrinking treatment depending on the use. The retardation value of the first and / or second protective film is preferably 10 nm or less in in-plane retardation (Re) at a wavelength of 590 nm, and the absolute value of the retardation (Rth) in the thickness direction at the same wavelength is 10 nm or less , And the absolute value of the retardation (Rth) in the thickness direction is 15 nm or less in the wavelength range of 480 to 750 nm.
When a retardation is imparted to the first and / or second protective films, a cellulose resin or a polyolefin resin containing a cyclic polyolefin resin or a cyclic polyolefin resin is preferable because control of the phase difference is easy, Based resin is preferably used.
The thickness of the first protective film is 50 占 퐉 or less, preferably 5 占 퐉 or more, more preferably 10 占 퐉 or more, further preferably 49 占 퐉 or less, and more preferably 30 占 퐉 or less. The thickness of the second protective film may be the same as the thickness of the first protective film, or thinner than that of the first protective film.
The polarizing plate of the present invention has a polarizing film laminated on at least one surface of the polarizing film as the thickest protective film in which the first protective film described above is laminated on the polarizing film and the ratio of the thickness of the first protective film to the thickness of the polarizing film is 1.9 .
If the ratio of the thickness of the first protective film to the thickness of the polarizing film is in the above-mentioned range, the polarizing plate is capable of preventing the stress such as shrinkage occurring in the polarizing film in the environment where the high temperature condition and the low temperature condition are repeated It is suppressed by the film and cracks are not generated in the polarizing film well, resulting in a polarizer excellent in durability.
In the present invention, as the polarizing film, the amount of deformation in the transmission axis direction (direction perpendicular to the stretching direction) of the polarizing film under the above specific conditions is 700 占 or less, and the thickness of the first protective film relative to the polarizing film In the above-mentioned range becomes important.
When the ratio of the thickness of the first protective film to the polarizing film is 1.9 or less and the deformation amount of the polarizing film is larger than 700 占,, the polarizing plate can not sufficiently suppress the dimensional change caused in the polarizing film of the first protective film A cold and heat impact test in which an environment in which a high temperature condition and a low temperature condition are repeated is assumed and a condensation cold heat shock test in which an environment in which a high temperature condition and a low temperature condition are repeated under a high humidity atmosphere is assumed, There is a tendency to occur. When the ratio of the thickness of the first protective film to the polarizing film is larger than 40 and the deformation amount of the polarizing film is larger than 700 占,, the polarizing plate has a problem that the first protective film excessively suppresses the dimensional change occurring in the polarizing film The stress applied to the inside of the polarizing film becomes large and a crack tends to occur in the polarizing film in the cold-shock test and the condensation cold-shock test.
≪ Adhesive (adhesive layer) >
The first protective film is laminated on at least one surface of the polarizing film described above to form a polarizing plate. The protective film is usually laminated on the polarizing film through an adhesive layer or a pressure-sensitive adhesive layer. The thickness of the adhesive layer or the pressure-sensitive adhesive layer can be about 0.01 to 30 mu m, preferably 0.01 to 10 mu m, more preferably 0.05 to 5 mu m. When the thickness of the adhesive layer or the pressure-sensitive adhesive layer is within this range, adhesive force without practical problems is obtained without causing lifting or peeling between the protective film and the polarizing film.
The adhesive layer or the pressure-sensitive adhesive layer may employ an appropriate adhesive or pressure-sensitive adhesive, depending on the type and purpose of the adherend, and may also use an anchor coating agent if necessary. Examples of the adhesive include a solvent type adhesive, an emulsion type adhesive, a pressure-sensitive adhesive, a re-wetting adhesive, a polycondensation type adhesive, a solventless type adhesive, a film type adhesive and a hot melt type adhesive. The pressure-sensitive adhesive may be one that can sufficiently adhere the polarizing film and the protective film, and a pressure-sensitive adhesive layer described later may be employed depending on the kind of the protective film.
As one of preferred adhesives, an aqueous adhesive, that is, an adhesive component is dissolved or dispersed in water. Examples of such an adhesive component include a polyvinyl alcohol resin and a urethane resin having a hydrophilic group. The water-based adhesive can be prepared by mixing such an adhesive component with water together with an additive to be compounded as required. Examples of a commercially available polyvinyl alcohol resin that can be used for an aqueous adhesive include "Kurarupofal (registered trademark) KL-318" (trade name), which is a carboxyl group-modified polyvinyl alcohol sold by Kuraray Co., have.
The aqueous adhesive may contain a crosslinking agent if necessary. 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 an adhesive component, an aldehyde compound including glyoxal, a methylol compound including methylolmelamine, a water-soluble epoxy resin, and the like are preferably used as a crosslinking agent.
Examples of the water-soluble epoxy resin include polyamides obtained by reacting epichlorohydrin with a polyamide polyamine which is a reaction product of a polyalkylene polyamine such as diethylene triamine or triethylene tetramine and a dicarboxylic acid such as adipic acid, Epoxy resin. Examples of commercially available water-soluble epoxy resins include "Sumireze Resin (registered trademark) 650 (30)" (trade name) sold by Sumika-Chemtech.
In the case of adopting an aqueous adhesive in the production of a polarizing plate, an aqueous adhesive is applied to the bonding surfaces of the polarizing film and / or the protective film, the two are bonded together, and then the aqueous adhesive is cured by a drying treatment to obtain a polarizing plate . Prior to bonding, it is also effective to increase the wettability of the protective film by performing easy adhesion treatment such as saponification treatment, corona discharge treatment, or plasma treatment. The drying temperature may be, for example, about 60 to 100 占 폚. Further, it is preferable that the curing is carried out at a temperature slightly higher than room temperature after the drying treatment, for example, at a temperature of about 30 to 50 占 폚 for about 1 to 10 days, because the adhesive strength can be further increased.
Another preferable adhesive includes a curable adhesive which is cured by irradiation with active energy rays or heating, and examples thereof include an epoxy adhesive. In the present invention, an epoxy adhesive is suitably used from the viewpoints of ease of handling, adhesive strength, and the like. Here, the epoxy adhesive is an adhesive containing an epoxy resin as a curing component. The epoxy resin refers to a compound or polymer that has at least two epoxy groups in the molecule and is cured by a polymerization reaction accompanied by ring-opening of an epoxy group. Also, according to convention in this field, the monomer is also referred to as an epoxy resin.
Curing of the epoxy resin is generally carried out by cationic polymerization of an epoxy resin. From the viewpoint of productivity, this curing is preferably carried out by irradiation of active energy rays.
The epoxy resin contained in the curable adhesive preferably has no aromatic ring in the molecule from the viewpoints of weatherability, refractive index, cationic polymerizability and the like. Examples of the epoxy resin which does not contain aromatic rings in the molecule include hydrogenated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. An epoxy resin appropriately contained in such a curable adhesive is described and publicly disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-245925, but the outline thereof will also be described here.
The hydrogenated epoxy resin is obtained by subjecting an aromatic polyhydroxy compound, which is a raw material of an aromatic epoxy resin, to a glycidyl etherification of a nuclear hydrogenated polyhydroxy compound obtained by selectively conducting a nuclehydrogenation reaction under a pressurized condition in the presence of a catalyst . Examples of the aromatic polyhydroxy compound include bisphenols such as bisphenol A, bisphenol F and bisphenol S; Novolak type resins such as phenol novolak resin, cresol novolak resin and hydroxybenzaldehyde phenol novolac resin; Tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol, and the like. The glycidyl etherification can be carried out by subjecting the aromatic polyhydroxy compound to a nuclear hydrogenation reaction and then reacting the obtained nucleus hydrogenated polyhydroxy compound with epichlorohydrin. Suitable hydrogenated epoxy resins include glycidyl ethers of hydrogenated bisphenol A.
The alicyclic epoxy resin is a compound having at least one epoxy group bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means a bridging oxygen atom -O- in the structure represented by the following formula, wherein m is an integer of 2 to 5.
A compound in which one or more hydrogen atoms in (CH 2 ) m in this formula are bonded to other chemical structures may be an alicyclic epoxy resin. Further, one or more hydrogen atoms in (CH 2 ) m forming an alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy resins, an epoxy resin having an epoxy cyclopentane structure (having m = 3 in the above formula) and an epoxy cyclohexane structure (having m = 4 in the above formula) . Specific examples of the alicyclic epoxy resin are given below. Here, the compounds are firstly named, and then the corresponding chemical formulas are given, and chemical names and corresponding chemical names are given the same reference numerals.
A: 3,4-
B: 3,4-epoxy-6-
C: Ethylene bis (3,4-epoxycyclohexanecarboxylate),
D: bis (3,4-epoxycyclohexylmethyl) adipate,
E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,
F: diethylene glycol bis (3,4-epoxycyclohexylmethyl ether),
G: ethylene glycol bis (3,4-epoxycyclohexylmethyl ether),
H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispyro [5.2.2.5.2.2] heneic acid,
I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane,
J: 4-vinylcyclohexene dioxide,
K: limonene dioxide,
L: bis (2,3-epoxycyclopentyl) ether,
M: dicyclopentadiene dioxide and the like.
The aliphatic epoxy resin may be a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. More specifically, diglycidyl ether of propylene glycol; Diglycidyl ether of 1,4-butanediol; Diglycidyl ether of 1,6-hexanediol; Triglycidyl ether of glycerin; Triglycidyl ether of trimethylolpropane; Polyglycidyl ether of a polyether polyol (e.g., diglycidyl ether of polyethylene glycol) obtained by adding an alkylene oxide (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol and glycerin .
In the curable adhesive, only one type of epoxy resin may be used alone, or two or more types may be used in combination. Among them, the epoxy resin preferably contains an alicyclic epoxy resin having at least one epoxy group bonded to an alicyclic ring in the molecule.
The epoxy equivalent of the epoxy resin contained in the curable adhesive is usually in the range of 30 to 3,000 g / equivalent, preferably 50 to 1,500 g / equivalent. If the epoxy equivalent is less than 30 g / equivalent, the flexibility of the polarizing plate after curing may be lowered or the adhesive strength may be lowered. On the other hand, if the epoxy equivalent exceeds 3,000 g / equivalent, compatibility with other components contained in the adhesive may be lowered.
In the present invention, as described above, it is preferable to employ a cationic polymerizable epoxy resin. Therefore, the curable adhesive preferably includes a cationic polymerization initiator. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation or heating of an active energy ray such as visible light, ultraviolet ray, X-ray and electron beam, and initiates polymerization reaction of the epoxy group. From the viewpoints of storage stability and workability, it is preferable that the cationic polymerization initiator is imparted with the potential to act catalytically by irradiation or heating of an active energy ray.
Hereinafter, a cationic polymerization initiator for generating a cationic species or a Lewis acid by irradiation of an active energy ray to initiate a polymerization reaction of an epoxy group is referred to as a " photo cationic polymerization initiator ", and a cationic species or a Lewis acid is generated by heat, The cationic polymerization initiator for initiating the polymerization reaction is referred to as " thermal cationic polymerization initiator ".
A method of curing an adhesive by adding a photo cationic polymerization initiator and irradiating an active energy ray is capable of curing at room temperature and the need to consider deformation due to heat resistance or expansion of the polarizing film is reduced, It is advantageous in that the film can be adhered well. Further, since the photo cationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy resin.
Examples of photo cationic polymerization initiators include aromatic diazonium salts; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts, and iron-arene complexes. The compounding amount of the photo cationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and more preferably 15 parts by weight or less, based on 100 parts by weight of the epoxy resin.
If the mixing amount of the photo cationic polymerization initiator is less than 0.5 part by weight, the curing becomes insufficient and the mechanical strength and the adhesive strength of the cured product tend to be lowered. On the other hand, if the blending amount of the photo cationic polymerization initiator exceeds 20 parts by weight, the amount of the ionic substance in the cured product increases, so that the hygroscopic property of the cured product increases, and the durability performance may be lowered.
When a photo cationic polymerization initiator is blended, the curable adhesive may further contain a photosensitizer, if necessary. By using a photosensitizer, the reactivity of the cationic polymerization can be improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfate, a redox compound, an azo compound, a diazo compound, a halogen compound, a photoreducible dye, and the like. When the photosensitizer is blended, the amount thereof is preferably within a range of 0.1 to 20 parts by weight based on 100 parts by weight of the curable adhesive.
On the other hand, examples of thermal cationic polymerization initiators include benzylsulfonium salts, thiophenium salts, thioronium salts, benzylammonium, pyridinium salts, hydrazinium salts, carboxylic acid esters, sulfonic acid esters and amine imides.
The curable adhesive containing an epoxy resin is preferably cured by photo cationic polymerization as described above. However, the thermal cationic polymerization initiator may be blended and cured by thermal cationic polymerization, or photo cationic polymerization and thermal cation And may be cured by both of the polymerization. In the case of curing by both photo cationic polymerization and thermal cationic polymerization, it is preferable to blend both the photo cationic polymerization initiator and the thermal cationic polymerization initiator in the curable adhesive.
The curable adhesive may further contain a compound that promotes cation polymerization such as an oxetane compound or a polyol compound. The oxetane compound is a compound having a 4-membered ring ether in the molecule. When the oxetane compound is blended, the blending amount thereof is usually 5 to 95% by weight, preferably 5 to 50% by weight, based on the total amount of the curable adhesive. The polyol compound may be an alkylene glycol or an oligomer thereof, such as ethylene glycol, hexamethylene glycol, or polyethylene glycol, a polyester polyol, a polycaprolactone polyol, a polycarbonate polyol, or the like. When blending the polyol compound, the blending amount thereof is generally 50% by weight or less, preferably 30% by weight or less, based on the total amount of the curable adhesive.
The curable adhesive may contain other additives such as an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoaming agent, etc., ≪ / RTI > Examples of the ion trap agent include inorganic compounds including a powdery bismuth, antimony, magnesium, aluminum, calcium, titanium, and mixtures thereof. Examples of the antioxidant include, for example, And hindered phenol-based antioxidants.
In the case of employing a curable adhesive for the production of a polarizing plate, a curable adhesive is applied to the bonding surface of the polarizing film or the protective film, or both of the bonding surfaces, and then the adhesive is bonded thereto. The uncured adhesive layer can be cured to adhere the polarizing film and the protective film. As the coating method of the adhesive, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be adopted.
This curable adhesive can basically be a solventless adhesive that does not substantially contain a solvent. However, since each coating method has an optimum viscosity range, a solvent may be added for viscosity adjustment. The solvent is preferably an organic solvent which dissolves each component including the epoxy resin well without deteriorating the optical performance of the polarizing film. For example, hydrocarbons typified by toluene, esters typified by ethyl acetate, and the like can be used .
When the adhesive is cured by irradiation of an active energy ray, various kinds of the above-mentioned active energy rays can be used. However, ultraviolet rays are preferable because they are easy to handle and easily control the amount of irradiation light. The irradiation intensity or irradiation amount of an active energy ray, for example, ultraviolet ray is appropriately adjusted so as to maintain proper productivity, without affecting various optical performances including the degree of polarization of the polarizing film and various optical performances including transparency and retardation characteristics of the protective film .
When the adhesive is cured by heat, it may be heated by a generally known method. Normally, the thermal cationic polymerization initiator compounded in the curable adhesive is heated to a temperature higher than the temperature at which the cationic species or Lewis acid is generated, and the heating temperature is, for example, about 50 to 200 캜.
[Pressure sensitive adhesive layer]
In the polarizing plate of the present invention, usually, a pressure-sensitive adhesive layer is laminated on the first or second protective film and bonded to a liquid crystal cell or the like through the laminate.
The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited as long as it is excellent in optical transparency and excellent in adhesion properties including wettability, cohesiveness and adhesiveness, and is preferably excellent in durability and the like. Specifically, as the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, a pressure-sensitive adhesive containing an acrylic resin (acrylic pressure-sensitive adhesive) is preferably used.
The acrylic resin contained in the acrylic pressure-sensitive adhesive is a resin having acrylic acid alkyl ester such as butyl acrylate, ethyl acrylate, isooctyl acrylate, and 2-ethylhexyl acrylate as main monomers. In general, a polar monomer is copolymerized with the acrylic resin. The polar monomer is a compound having a polymerizable unsaturated bond and a polar functional group, and the polymerizable unsaturated bond is generally derived from a (meth) acryloyl group, and the polar functional group is a carboxyl group, a hydroxyl group, an amide group, An amino group, an epoxy group, and the like. Specific examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, 2-N, ) Acrylate, and glycidyl (meth) acrylate.
A crosslinking agent is usually mixed with an acrylic resin in the acrylic pressure-sensitive adhesive.
As typical examples of the crosslinking agent, there can be mentioned isocyanate compounds having at least two isocyanato groups (-NCO) in the molecule.
The pressure-sensitive adhesive may further contain various additives. Suitable additives include silane coupling agents and antistatic agents. The silane coupling agent is effective in enhancing adhesion to glass. The antistatic agent is effective in reducing or preventing the generation of static electricity. Generally, when a polarizing plate is attached to a liquid crystal cell through a pressure-sensitive adhesive layer, a surface protective film (separator) covering the pressure-sensitive adhesive layer and temporarily adhered and protected until then is peeled and then bonded to the liquid crystal cell. The generated static electricity causes defective alignment of liquid crystal in the liquid crystal cell, and this phenomenon may cause display failure of the liquid crystal display device. As a means for reducing or preventing the generation of such static electricity, mixing of an antistatic agent with a pressure-sensitive adhesive is effective.
The pressure-sensitive adhesive layer can be formed by a direct coating method in which the above pressure-sensitive adhesive component is dissolved in an organic solvent to prepare a pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is applied directly onto the protective film of the polarizing plate and the solvent is dried and removed, It is possible to form the pressure-sensitive adhesive layer by applying the above-described pressure-sensitive adhesive composition to the release-treated surface of a base film made of a film and drying and removing the solvent to form a pressure-sensitive adhesive layer and then adhering it onto the protective film of the polarizing plate. In the case where the pressure-sensitive adhesive layer is formed on the protective film by the former direct coating method, the surface of the pressure-sensitive adhesive layer is temporarily adhered and protected by bonding a resin film (also referred to as a separator) to be. The latter transfer method is widely used from the viewpoint of handling properties of the pressure-sensitive adhesive composition as an organic solvent solution. In this case, the release-treated base film used for forming the pressure-sensitive adhesive layer first is bonded to the polarizing plate, It is also suitable in that it can be.
[Liquid crystal display device]
The polarizing plate of the present invention is suitably used for a liquid crystal display device. The liquid crystal display device includes a liquid crystal panel. This liquid crystal panel has a liquid crystal cell and a polarizing plate laminated on one or both surfaces of the liquid crystal cell, and the liquid crystal cell and the polarizing plate are bonded through the pressure-sensitive adhesive layer as described above. This liquid crystal cell may be of various types such as an IPS mode, a VA mode, and a TN mode. On the opposite side of the liquid crystal cell to which the polarizing plate of the present invention is bonded, a polarizing plate of the same kind or a known polarizing plate can be bonded.
When the polarizing plate of the present invention is disposed on the viewer side of the liquid crystal cell, the protective film (the protective film located closest to the viewer side) farther from the liquid crystal cell can be a film having haze-imparted anti-scattering properties. Examples of the method of imparting haze to the protective film include a method of producing a film by mixing inorganic fine particles or organic fine particles with the resin of the raw material constituting the protective film, a method of producing a resin in which fine particles are mixed with fine particles, A method of producing a three-layered film by using a resin mixed with fine particles as an outer layer, or a method of mixing an inorganic fine particle or an organic fine particle with a curable binder resin on one side of the film A method in which a coating solution is coated, and a binder resin is cured to form an antiglare layer.
Examples of the inorganic fine particles include silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate and the like. Examples of the organic fine particles include crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles and polyimide particles.
When a haze is imparted to the protective film, it is preferable that the haze value is within a range of 6 to 45%. If the haze value is less than 6%, a sufficient antiglare effect may not be obtained. On the other hand, if the haze value exceeds 45%, the screen of the liquid crystal display device on which the protective film is disposed may be spattered, resulting in deterioration of image quality. The haze is a value defined as a ratio of the diffusion transmittance to the total light transmittance and can be measured using a commercially available haze meter in accordance with JIS K 7136: 2000 " Method of determining haze of plastic-transparent material ". The commercially available haze meter includes, for example, " HM-150 " (product name) sold by Murakami Color Technology Research Institute. For measurement of the haze value, it is preferable to use a measurement sample in which the film surface is bonded to the glass substrate so that the antiglare surface becomes the surface, for example, by using an optically transparent pressure-sensitive adhesive in order to prevent the film from being warped.
When the polarizing plate of the present invention is disposed on the viewer side of the liquid crystal cell, a conductive layer, a hard coat layer, a low reflection layer, or the like is formed on the outermost surface (the surface opposite to the polarizing film) To form a functional layer containing the functional layer. As the coating liquid containing the binder resin constituting the above-mentioned antiglare layer, a resin composition capable of expressing these functions may be selected.
When the polarizing plate of the present invention is disposed on the rear side of the liquid crystal cell, the protective film that is farther from the liquid crystal cell (backlight side) may contain a resin having excellent transparency, mechanical strength, thermal stability, Instead of the film, a brightness enhancement film may be selected. For example, "DBEF" (registered trademark), "APF" (product name), and the like sold by Sumitomo 3M Ltd. under the trade name of "Brightness Enhancement Film" have. When a brightness enhancement film is used as a protective film that is far from the liquid crystal cell (on the backlight side), it can be laminated with the above-mentioned pressure sensitive adhesive.
When the polarizing plate of the present invention is bonded to a liquid crystal cell, the protective film of the protective film located on the liquid crystal cell side (between the liquid crystal cell and the polarizing film), whether on the viewer side or the back side, More preferably a cellulose resin or a polyolefin resin.
[Example]
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following examples, the calculation of the amount of deformation of the polarizing film and the measurement of the thickness of the polarizing film and the protective film were carried out in the following manner.
The deformation amount of the polarizing film was obtained as follows. First, the polarizing film was cut to a size of 100 mm x 100 mm in the direction of the absorption axis x the transmission axis. This polarizing film piece was molded into a plastic corrugated cardboard (a hollow structure extruded article made of polypropylene as a raw material) having a size of the outer periphery of 140 mm x 140 mm and a central portion of 80 mm x 80 mm, The polarizing film fragments and the plastic corrugated cardboard were fixed with a 10 mm wide polyimide adhesive tape for thermal insulation insulation (trade name " No.360 series " manufactured by NITTO DENKO CO., LTD.) So as to prevent them from shifting during measurement To prepare a sample for measurement. General purpose strain gage " KFG-5-120-C1 " sold by Kyoe Kogyo Co., Ltd. was bonded at the central position of the polarizing film so as to be parallel to the transmission axis direction of the polarizing film. The polarizing film and strain gage were bonded by a cyanoacrylate-based adhesive (trade name "AERONA (registered trademark) 201", available from DOA CO., LTD.). The strain gage was connected to a high-speed data logger "UCAM-65A", which is sold by Kyowa Kogyo Co., Ltd. As a result, a dimensional change in the transmission axis direction of the polarizing film was measured. Next, the sample for measurement was placed in an oven, and the temperature in the oven was raised from 85 ° C. to 85 ° C. at a rate of 2 ° C./min from 25 ° C. After that, a sample was taken out and the polarizing film , 0.3 mL of pure water at 23 占 폚 was dropwise added. The maximum amount of dimensional change (absolute value) produced during one minute after pure dropping was recorded, and the amount of deformation was calculated by the above formula (1).
The thickness of the polarizing film and the protective film was measured with a digital micrometer " MH-15M " (product name) manufactured by Nikon Corporation.
(Production Example 1)
A polyvinyl alcohol film having a mean polymerization degree of about 2400 and a saponification degree of 99.9 mol% and having a thickness of 30 mu m (trade name "VF-PE # 3000" manufactured by Kuraray Co., Ltd.) was immersed in pure water at 37 ° C, and potassium iodide / Water at a weight ratio of 0.04 / 1.5 / 100. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 12 / 3.6 / 100 at 56.5 캜. Subsequently, the film was washed with pure water at 10 占 폚 and then dried at 85 占 폚 to prepare a
(Production Example 2)
A polyvinyl alcohol film having a mean degree of polymerization of about 2400 and a degree of saponification of 99.9 mol% and having a thickness of 60 탆 (trade name: "VF-PE # 6000", manufactured by Kuraray Co., Ltd.) was immersed in pure water at 37 ° C., Was immersed in an aqueous solution having a weight ratio of potassium / water of 0.04 / 1.5 / 100 at 30 占 폚. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 12 / 3.6 / 100 at 56.5 캜. Subsequently, the film was washed with pure water at 10 占 폚 and then dried at 85 占 폚 to produce a polarizing film 2 having a thickness of about 23 占 퐉 in which iodine was adsorbed and oriented in polyvinyl alcohol. The stretching was carried out mainly in iodine dyeing and boric acid treatment steps, and the total stretching magnification was 5.3 times. The deformation amount of the polarizing film 2 was 711 占.
In the following Examples and Comparative Examples, a polarizing plate was produced from the polarizing film prepared above and the following protective film.
<Protection film>
Protective film A: Triacetylcellulose (TAC) film with hard coat, thickness 49 탆, product name "KY-40-C2A3" obtained from Konica Minolta Opto.
Protective film B: TAC film, thickness 25 탆, product name " KC2UAW " obtained from Konica Minolta Opto.
Protective film C: TAC film with hard coat, thickness 44 mu m, product name "40CHC" obtained from Toppan Printing Co., Ltd.
Protective film D: Cycloolefin polymer (COP) molded article, thickness 20 占 퐉, trade name "Zeonoa Film" (registered trademark) obtained from Nippon Zeon Co., Ltd.
Protective film E: molded product of cycloolefin polymer (COP), thickness 23 탆, trade name "Zeonoa Film" (registered trademark) obtained from Nippon Zeon Co., Ltd.
[Example 1]
(Preparation of aqueous adhesive)
3 parts of a carboxyl group-modified polyvinyl alcohol " KL-318 " (trade name), obtained from Kuraray Co., Ltd., was dissolved in 100 parts of water. To the aqueous solution was added a water-soluble polyamide epoxy 1.5 parts of a resin "Sumireiz resin (registered trademark) 650 (30)" (trade name, aqueous solution having a solid content concentration of 30%) was added to prepare an aqueous adhesive.
(Production of polarizing plate)
The bonding surfaces of the protective film A and the protective film D were saponified. On one side of the
[evaluation]
A polarizing plate with a pressure-sensitive adhesive layer was produced by adhering an acrylic pressure-sensitive adhesive sheet having a release film to the surface of the protective film D of the polarizing plate prepared above, which was opposite to the
In this cold and heat impact environmental test, the polarizing plate was bonded to a glass plate and heat-treated at a temperature of 85 占 폚 under a high-temperature condition using a cold / heat impact testing apparatus (trade name "TSA-71L-A-3" For 30 minutes, and exposed at -40 占 폚 for 30 minutes as a low-temperature condition. In addition, the temperature transition time was set to 0 minutes at the time of the temperature transition, and no air was introduced at the time of shifting the temperature, and a condition was set so as not to cause condensation in the evaluation sample. As a result, no crack occurred in the polarizing film even after repeating 400 cycles.
The condensation cold / heat shock environmental test was conducted under the condition that intentional condensation was generated in the evaluation sample by introducing the outside air into the apparatus for 5 minutes at the time of shifting the temperature in the aforementioned cold / heat shock environmental test. As a result, no crack occurred in the polarizing film even after repeating 50 cycles. The outside air introduced at the time of this test was 23 ° C and the relative humidity was 55%.
After performing a cold / heat shock environment test (cycle number: 400 times) and a condensation cold / heat shock environment test (cycle number: 50 times), the presence or absence of cracks was visually confirmed. In Table 1 to be described later, " o " indicates that there was no change before the test, and " x " indicates that the crack occurred after the test.
[Experimental Example 2]
A polarizing plate was produced in the same manner as in Example 1 except that the protective film A was changed to the protective film B and the protective film D was changed to the protective film E.
An acrylic pressure-sensitive adhesive sheet was bonded to the surface of the polarizing plate opposite to the
[Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that the protective film A was replaced with the protective film C, the protective film D was replaced with the protective film E, and the
An acrylic pressure sensitive adhesive sheet was bonded to the surface of the polarizing plate opposite to the
[Comparative Example 2]
A polarizing plate was produced in the same manner as in Example 1 except that the protective film A was changed to the protective film B and the
An acrylic pressure sensitive adhesive sheet was bonded to the protective film D side of the polarizing plate to prepare a polarizing plate with a pressure-sensitive adhesive layer. The resulting polarizer with a pressure-sensitive adhesive layer was cut into a size of 5.1 inches, and the pressure-sensitive adhesive layer was bonded to a glass plate, and the same cold and heat impact environment test and condensation cold and heat impact environmental test as in Example 1 were carried out. As a result, in the cold / heat shock environmental test, the polarizing film cracked after repeating 400 cycles. Further, even in the condensation cold / heat shock environmental test, cracks were generated in the polarizing film when it was repeated for 50 cycles.
1: film fragments of polarizing films,
3: Measuring jig,
5: Polyimide tape,
7: strain gauge.
Claims (6)
The ratio of the thickness of the first protective film to the thickness of the polarizing film is larger than 1.9,
The polarizing film was conditioned (conditioned) for 24 hours in an atmosphere having a temperature of 23 캜 and a relative humidity of 55%, and then heated from 25 캜 to 85 캜 at a rate of 2 캜 / minute in an oven. Of the polarizing film produced after 1 minute has elapsed from adhering 0.3 mL of pure water at 23 DEG C in an amount of 700 mu E or less.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014142985A JP2016018183A (en) | 2014-07-11 | 2014-07-11 | Polarizing plate and liquid crystal display device |
| JPJP-P-2014-142985 | 2014-07-11 |
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| Publication Number | Publication Date |
|---|---|
| KR20160007389A true KR20160007389A (en) | 2016-01-20 |
| KR101643503B1 KR101643503B1 (en) | 2016-07-27 |
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| Application Number | Title | Priority Date | Filing Date |
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| KR1020150096505A KR101643503B1 (en) | 2014-07-11 | 2015-07-07 | Polarizing plate and liquid crystal display device |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP2016018183A (en) |
| KR (1) | KR101643503B1 (en) |
| CN (1) | CN105301676B (en) |
| TW (1) | TWI566934B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20200100202A (en) * | 2018-03-30 | 2020-08-25 | 닛토덴코 가부시키가이샤 | Polarizing film and image display device with pressure-sensitive adhesive layer |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP7181260B2 (en) * | 2019-09-17 | 2022-11-30 | 住友化学株式会社 | circular polarizer |
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| JP2002174727A (en) * | 2000-12-07 | 2002-06-21 | Nitto Denko Corp | Polarizing plate and liquid crystal display device using the same |
| KR20020088052A (en) * | 2001-05-14 | 2002-11-25 | 닛토덴코 가부시키가이샤 | Polarizer and method of producing the same |
| KR20030093991A (en) * | 2002-05-31 | 2003-12-11 | 스미또모 가가꾸 고오교오 가부시끼가이샤 | The method for producing a laminated polarizing film |
| JP2012145645A (en) | 2011-01-07 | 2012-08-02 | Nitto Denko Corp | Polarizing plate |
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| TWI251089B (en) * | 2000-06-19 | 2006-03-11 | Nitto Denko Corp | Polarizer, polarizing plate, and liquid crystal display using the same |
| JP2005215700A (en) * | 2005-03-24 | 2005-08-11 | Fuji Photo Film Co Ltd | Polarizing plate |
| JP2007292917A (en) * | 2006-04-24 | 2007-11-08 | Konica Minolta Opto Inc | Polarizing plate |
| JP5041532B2 (en) * | 2007-12-06 | 2012-10-03 | 日東電工株式会社 | Polarizing plate, optical film and image display device |
| KR101930958B1 (en) * | 2011-02-08 | 2018-12-19 | 닛토덴코 가부시키가이샤 | Method for manufacturing laminated multilayer film |
| KR20130125319A (en) * | 2012-05-08 | 2013-11-18 | 후지필름 가부시키가이샤 | Optical film, polarizing plate, image display device, and method of producing optical film |
| JP2014041340A (en) * | 2012-07-27 | 2014-03-06 | Fujifilm Corp | Cellulose acylate film, roll type cellulose acylate film, polarizing plate, and liquid crystal display device |
| JP5569622B2 (en) * | 2013-05-10 | 2014-08-13 | コニカミノルタ株式会社 | Method for producing cellulose ester film and method for producing polarizing plate |
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2014
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2015
- 2015-06-24 TW TW104120288A patent/TWI566934B/en active
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002174727A (en) * | 2000-12-07 | 2002-06-21 | Nitto Denko Corp | Polarizing plate and liquid crystal display device using the same |
| KR20020088052A (en) * | 2001-05-14 | 2002-11-25 | 닛토덴코 가부시키가이샤 | Polarizer and method of producing the same |
| KR20030093991A (en) * | 2002-05-31 | 2003-12-11 | 스미또모 가가꾸 고오교오 가부시끼가이샤 | The method for producing a laminated polarizing film |
| JP2012145645A (en) | 2011-01-07 | 2012-08-02 | Nitto Denko Corp | Polarizing plate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20200100202A (en) * | 2018-03-30 | 2020-08-25 | 닛토덴코 가부시키가이샤 | Polarizing film and image display device with pressure-sensitive adhesive layer |
| US11169312B2 (en) | 2018-03-30 | 2021-11-09 | Nitto Denko Corporation | Pressure-sensitive-adhesive-layer-attached polarizing film, and image display device |
Also Published As
| Publication number | Publication date |
|---|---|
| TW201605623A (en) | 2016-02-16 |
| CN105301676B (en) | 2018-03-27 |
| TWI566934B (en) | 2017-01-21 |
| KR101643503B1 (en) | 2016-07-27 |
| JP2016018183A (en) | 2016-02-01 |
| CN105301676A (en) | 2016-02-03 |
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