JPH037921B2 - - Google Patents
Info
- Publication number
- JPH037921B2 JPH037921B2 JP58134959A JP13495983A JPH037921B2 JP H037921 B2 JPH037921 B2 JP H037921B2 JP 58134959 A JP58134959 A JP 58134959A JP 13495983 A JP13495983 A JP 13495983A JP H037921 B2 JPH037921 B2 JP H037921B2
- Authority
- JP
- Japan
- Prior art keywords
- film
- polarizing
- adhesives
- refractive index
- polyester
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000001070 adhesive effect Effects 0.000 claims description 17
- 239000000853 adhesive Substances 0.000 claims description 16
- 229920006267 polyester film Polymers 0.000 claims description 13
- 229920000728 polyester Polymers 0.000 claims description 5
- 239000012790 adhesive layer Substances 0.000 claims description 4
- 239000004830 Super Glue Substances 0.000 claims description 2
- 229920006332 epoxy adhesive Polymers 0.000 claims description 2
- 229920002635 polyurethane Polymers 0.000 claims description 2
- 239000004814 polyurethane Substances 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 description 12
- 238000000034 method Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 6
- 230000010287 polarization Effects 0.000 description 6
- 229920000139 polyethylene terephthalate Polymers 0.000 description 5
- 239000005020 polyethylene terephthalate Substances 0.000 description 5
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 4
- 229920002799 BoPET Polymers 0.000 description 4
- 239000004372 Polyvinyl alcohol Substances 0.000 description 4
- 229910052740 iodine Inorganic materials 0.000 description 4
- 239000011630 iodine Substances 0.000 description 4
- -1 polyethylene Polymers 0.000 description 4
- 229920002451 polyvinyl alcohol Polymers 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 239000011241 protective layer Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 2
- 230000014509 gene expression Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920006255 plastic film Polymers 0.000 description 2
- 239000002985 plastic film Substances 0.000 description 2
- 150000004291 polyenes Chemical class 0.000 description 2
- 229920001228 polyisocyanate Polymers 0.000 description 2
- 239000005056 polyisocyanate Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920000219 Ethylene vinyl alcohol Polymers 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- UFRKOOWSQGXVKV-UHFFFAOYSA-N ethene;ethenol Chemical compound C=C.OC=C UFRKOOWSQGXVKV-UHFFFAOYSA-N 0.000 description 1
- 239000005038 ethylene vinyl acetate Substances 0.000 description 1
- 239000004715 ethylene vinyl alcohol Substances 0.000 description 1
- 229920001477 hydrophilic polymer Polymers 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920001707 polybutylene terephthalate Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000003678 scratch resistant effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
Description
本発明は偏光板、詳しく言えばどの視野角度か
らの反射光または透過光でも着色干渉縞を発生し
ない透明保護層で保護された偏光板に関する。
偏光フイルムを外気に曝された環境条件で使用
する場合や、液晶を用いた表示器に使用する場合
などには、外傷や湿気あるいは化学薬品による腐
触から偏光フイルムを保護するために、表面に保
護層を設ける必要がある。保護層を形成する材料
にはガラスやプラスチツクフイルムが用いられる
が、ガラスは強度の点からあまり薄くできず、ま
た重量も重くなることが欠点である。プラスチツ
クフイルムとしてはセルロース系あるいはポリア
クリル系樹脂が実用化されているが、これらも、
形状、寸法の安定性や耐湿、耐熱性に優れず、特
に屋外用には適さない。これに対して、ポリエス
テルの一種であるポリエチレンテレフタート(以
下の説明でPETと略す)を伸延加工したフイル
ムの使用が試みられている。このフイルムは、伸
延加工されていることにより、化学薬品に対する
耐腐触性が大きく、また耐熱、耐湿性なども優れ
ているが、伸延加工によりフイルムに光学的異方
性が生じ、光に複屈折をおこさせる。従つて、こ
のフイルムで保護された偏光板を透かし物体を見
る場合、方向により保護膜上に光の干渉による色
むらが生じることがあり、例えば液晶を用いた表
示器に使用する偏光板の保護膜などには適さな
い。
本発明の目的は、PETその他のポリエステル
系フイルムの上記のような欠点を排除し、色むら
の生じないポリエステルフイルムで保護された偏
光板を提供することにある。かかる本発明の目的
は、膜面に平行な一方向に特に強く延伸されたポ
リエステルフイルムにおいて、Nyを特に強く延
伸された方向の屈折率、Nxをこれに垂直方向の
屈折率、Nzを膜厚方向の屈折率としたとき、
〔(1/Ny2−1/Nx2)/(1/Ny2−1/Nz2)〕1/2
>0.8
を満足し、かつ、フイルム厚さをdとしたとき
2.3〔(1.642/1/N2y+0.642/N2z)1/2−Nx〕d>4
を満足するポリエステルフイルムが偏光フイルム
の少なくとも片方の面に接着剤の層を介して貼り
合せることにより達成される。
次に本発明の基礎をなす理論について説明す
る。
第1図に示すように、互いに光軸が直交するよ
う配置された2個の偏光子P1,P2から成る直交
ニコル光学系の、両偏光子P1,P2の間に複屈折
性を有するサンプルをおくと、この光学系を透過
する光の強度Iは、偏光子の光軸とサンプルの光
軸との間の角度をφとして、
I=Asin22φ・sin2δ/2 …(1)
で表される。ここでAは定数、δは、
δ=2πΔn・d/λ
で与えられる位相因子である。但し、Δnはサン
プルの表面に平行な面内での主屈折率の差、λは
光の波長、dはサンプルの厚さとする。従つて式
(1)は、
I=Asin22φ×sin2(π・Δn・d/λ) …(2)
と表すことができる。なお、Δn・dはレターデ
イシヨンと呼ばれる。式(2)からわかるようにφ=
0,π/2,π,3π/2,…の時は光は透過しないが
、
例えば0<φ<π/2であつても、Nを整数として
Δn・d/λがNに等しくなる条件と(N+
1)/2に等しくなる条件の間で、光度は0から
ピーク値まで、sin2(π・Δn・d/λ)に従つて
変化する。しかし、実際にはNが大きくなるとこ
の変化のコントラストは急速に弱まり、そのよう
な条件を満たす波長の光は事実上色むらに関与し
ない。従つて、いまN=1とし、dに典型的な膜
厚の値として100μmを、λに可視光中央部の波
長550nmを用いると、Δnはほぼ0.005と算出され
る。この値はPETフイルムのΔnの値0.08〜0.14
に比べて1桁以上小さく、従つてλとdを同じと
するならPETがΔn・d/λ=N,or(N+1)/
2を満足するNの値は10以上となり、膜面に対し
て垂直な方向に関する限り、色むらに関しては全
く問題はない。即ち、レターデイシヨンΔn・d
が10μm近くであれば、可視光について垂直方向
に関する限り色むらは問題とならず、上記の
PETフイルムの場合レターデイシヨンは8〜14μ
mになつている。しかし、斜めの方向の場合、
Δnが0.005近くになる場合もあり得るかも知れ
ず、このような方向からフイルムを見た場合、着
色干渉縞が現れる。これについて以下にさらに考
察を進める。
第2図は主屈折率をnx,ny,nzとしたとき、
式
X2/nx2+y2/ny2+z2/nz2=1 …(3)
で表される屈折率楕円体の図である。原点を通る
この楕円体の断面が円になるとき、その断面の法
線方向に近い方向からフイルムを見た場合Δnは
非常に小さくなり(法線方向から見ればΔn=
0)、今の場合、具体的には、Δn=0.005になる
方向からフイルムを見るとき、着色干渉縞が観測
されるようになる。断面の形が円になるような断
面はz軸に対称に2つ存在する。断面が円となる
条件は次のようにして求められる。即ち、原点0
を通り、法線がz軸と角θ′をなし、y−z面に直
交する平面で式(3)の楕円体を切断したときの断面
の図形(一般に楕円で、第8図において斜線をほ
どこした図形)は、
x2/nx2+z′2(cos2θ′/ny2+sin2θ′/nz2)…(4)
で表される。ここでz′は、断面の法線(y′軸)
とx軸に直交して選んだ座標軸である。この式(4)
が円を表すための条件はx2の係数とz′2の係数が
等しいこと、つまり、
1/nx2=cos2θ′/ny2+sin2θ′/nz2…(5)
が成り立つことである。なお、ここで、式(4)の導
出方法を第8図を用いて説明する。同図は第2図
における座標軸y,y′,z,z′の間の関係を説明
する図で、このような座標変換によりy,y′,
z,z′の間には、
y=y′cos(90゜−θ′)−z′sin(9゜−θ)
=y′sinθ′−z′cosθ′ …(4a)
z=y′sin(90゜−θ′)+z′cos(90゜−θ′)
y′cosθ′+z′sinθ′ …(4b)
の関係が成り立つ。式(4a)および(4b)を式
(3)に代入すれば、
x2/nx2+(y′sinθ′−z′cosθ′)2/ny2
+(y′cosθ′+z′sinθ′)2/nz2=1 …(4c)
が得られる。即ち、式(4c)は式(3)に、式(4a)
と式(4b)で示された座標変換をほどこしたも
のである。従つて、法線がz軸と角θ′をなし、y
−z面に直交する平面で式(3)の楕円体を切断した
断面を表わす式は、式(4c)においてy′=0とお
くこにより、
x2/nz2+z′2(cos2θ′/ny2+sin2θ′/nz2)=1
で表される。即ち、このようにして式(4)が導かれ
る。式(5)より、
sinθ′=〔(1/ny2−1/nx2)/
(1/ny2−1/nz2)〕1/2 …(6)
が導かれ、式(6)を満足する角θ′の方向に近い方向
から見たときに着色干渉縞が現れる。但し、ここ
で求めた角θ′は媒質フイルム内での角であり実際
には、フイルム面での光の屈折を考慮して、空気
中より観察する場合の角θ(第3図参照)に換算
する必要がある。空気の屈折率(事実上1と考え
てよい)をn1、フイルムの屈折率をn2とすると、
θとθ′の間には、
n1・sinθ=n2・sinθ′ …(7)
の関係があり、θが90゜近くになれば、実際上フ
イルム面を斜めの方向から観察しても着色干渉縞
は現れない。ここで式(6)と式(7)より、n1=1,n2
=1.6(PETフイルムの平均的な屈折率)としてθ
>90゜となる条件を求めると、
sinθ′=〔(1/Ny2−1/Nx2)
/(1/Ny2−1/Nz2)〕1/2
>0.8 …(8)
が得られる。従つて主屈折率Nx,Ny,Nzが式
(8)を満足するようなフイルムであれば斜め方向か
らフイルムを見てもコントラストの強い着色干渉
縞は現われない。さらにコントラストの弱くなつ
た数次の干渉縞次数のものも無くし、完ぺきなも
のとするためには、最も斜めに傾けた場合、すな
わち最も条件の悪い状態での縞次数を算出し、こ
れが一定値以上にし、コントラストを無くする方
向へもつてゆけばよい。具体的には、Nz=1.60,
θ=90゜(この時θ′=38.7゜)とした時の縞次数を算
出すればよい。
第4図に、こような場合の屈折率楕円体の図を
示す。この図において光の入射する方向でのΔN
を計算すると
これを用いて縞次数を算出すると
N=ΔNd/cosθ′/λ …(10)
N値が4以上となると実際には干渉縞が観察さ
れないことから
N>4 …(11)
(11)式に(9)、(10)およびθ′=38.7゜を代入し、
2.3〔(1.642/1/Ny2+0.642/N2z)1/2−Nx〕d>4
の条件が得られる。
すなわち(8)式を満足し、かつ(12)式を満足するフ
イルムを偏光フイルムの保護膜に用いることによ
りどの方向から見ても干渉縞は全く認められない
偏光板を得ることができる。なお本発明にあたつ
て試作したPETフイルムサンプルについて検証
した(8)式、(12)式の右辺の値を次表に示す。
The present invention relates to a polarizing plate, and more specifically to a polarizing plate protected with a transparent protective layer that does not generate colored interference fringes even with reflected or transmitted light from any viewing angle. When using a polarizing film in an environment where it is exposed to the outside air or when using it in a liquid crystal display, the surface of the polarizing film must be coated to protect it from external damage, moisture, or corrosion due to chemicals. It is necessary to provide a protective layer. Glass or plastic film is used as the material for forming the protective layer, but glass has the disadvantage that it cannot be made very thin due to its strength and is also heavy. Cellulose or polyacrylic resins have been put into practical use as plastic films;
It does not have excellent shape or dimensional stability, moisture resistance, or heat resistance, making it particularly unsuitable for outdoor use. In response, attempts have been made to use a film made by stretching polyethylene tereftate (abbreviated as PET in the following description), which is a type of polyester. Due to the stretching process, this film has high corrosion resistance against chemicals, as well as excellent heat and moisture resistance. cause refraction. Therefore, when viewing an object through a polarizing plate protected by this film, color unevenness may occur on the protective film due to light interference depending on the direction. Not suitable for membranes, etc. An object of the present invention is to eliminate the above-mentioned drawbacks of PET and other polyester films and to provide a polarizing plate protected by a polyester film that does not cause color unevenness. The purpose of the present invention is to obtain a polyester film that has been particularly strongly stretched in one direction parallel to the film surface, where Ny is the refractive index in the particularly strongly stretched direction, Nx is the refractive index in the direction perpendicular to this, and Nz is the film thickness. When the refractive index in the direction is [(1/Ny 2 -1/Nx 2 )/(1/Ny 2 -1/Nz 2 )] 1/2 >0.8, and the film thickness is d. A polyester film that satisfies 2.3 [(1.642/1/N 2 y + 0.642/N 2 z) 1/2 −Nx] d>4 is attached to at least one surface of the polarizing film via an adhesive layer. This is achieved by matching. Next, the theory underlying the present invention will be explained. As shown in Figure 1, birefringence exists between the two polarizers P 1 and P 2 of a crossed Nicol optical system consisting of two polarizers P 1 and P 2 arranged so that their optical axes are perpendicular to each other. When we have a sample with It is expressed as (1). Here, A is a constant and δ is a phase factor given by δ=2πΔn·d/λ. However, Δn is the difference in principal refractive index in a plane parallel to the surface of the sample, λ is the wavelength of light, and d is the thickness of the sample. Therefore, the expression
(1) can be expressed as I=Asin 2 2φ×sin 2 (π・Δn・d/λ) (2). Note that Δn·d is called a letter dation. As can be seen from equation (2), φ=
Light does not pass through when 0, π/2, π, 3π/2, ..., but for example, even if 0<φ<π/2, the condition that Δn・d/λ is equal to N, where N is an integer and (N+
Between the conditions equal to 1)/2, the luminous intensity varies according to sin 2 (π·Δn·d/λ) from 0 to the peak value. However, in reality, as N increases, the contrast of this change rapidly weakens, and light with a wavelength that satisfies such conditions does not actually contribute to color unevenness. Therefore, if N=1, d is a typical film thickness of 100 μm, and λ is the wavelength of 550 nm at the center of visible light, Δn is calculated to be approximately 0.005. This value is the value of Δn of PET film 0.08 to 0.14
Therefore, if λ and d are the same, PET is Δn・d/λ=N, or (N+1)/
The value of N that satisfies 2 is 10 or more, and there is no problem with color unevenness as far as the direction perpendicular to the film surface is concerned. That is, the letter d is Δn・d
If it is close to 10 μm, color unevenness will not be a problem as far as visible light is concerned in the vertical direction, and the above
In the case of PET film, the lettering is 8 to 14μ.
It's becoming m. However, in the case of diagonal direction,
It may be possible for Δn to be close to 0.005, and if the film is viewed from such a direction, colored interference fringes will appear. We will discuss this further below. Figure 2 shows that when the principal refractive index is nx, ny, nz,
It is a diagram of a refractive index ellipsoid expressed by the formula X 2 /nx 2 +y 2 /ny 2 +z 2 /nz 2 =1 (3). When the cross section of this ellipsoid passing through the origin is a circle, if the film is viewed from a direction close to the normal direction of the cross section, Δn will be extremely small (if viewed from the normal direction, Δn =
0), in this case, specifically, when viewing the film from a direction where Δn=0.005, colored interference fringes will be observed. There are two cross sections that are circular in shape and are symmetrical about the z-axis. The conditions for a circular cross section can be found as follows. That is, origin 0
, the normal line makes an angle θ' with the z-axis, and the ellipsoid of equation (3) is cut by a plane perpendicular to the y-z plane. The created figure) is expressed as x 2 /nx 2 +z′ 2 (cos 2 θ′/ny 2 +sin 2 θ′/nz 2 )…(4). Here, z′ is the normal to the cross section (y′ axis)
is the coordinate axis chosen perpendicular to the x-axis. This formula (4)
The condition for this to represent a circle is that the coefficients of x 2 and z′ 2 are equal, that is, 1/nx 2 = cos 2 θ′/ny 2 + sin 2 θ′/nz 2 …(5) holds true. It is. Here, the method for deriving equation (4) will be explained using FIG. 8. This figure is a diagram explaining the relationship between the coordinate axes y, y', z, and z' in Figure 2. Through such coordinate transformation, y, y',
Between z and z′, y=y′cos(90°−θ′)−z′sin(9°−θ)=y′sinθ′−z′cosθ′…(4a) z=y′sin (90°−θ′) + z′cos (90°−θ′) y′cosθ′+z′sinθ′ …(4b) holds. Expressions (4a) and (4b) are expressed as
Substituting into (3), x 2 /nx 2 + (y′sinθ′−z′cosθ′) 2 /ny 2 + (y′cosθ′+z′sinθ′) 2 /nz 2 = 1 … (4c) is obtained. That is, equation (4c) becomes equation (3), and equation (4a)
is obtained by applying the coordinate transformation shown in equation (4b). Therefore, the normal line makes an angle θ′ with the z-axis, and y
By setting y′=0 in equation (4c), the equation representing the cross section of the ellipsoid in equation (3) taken by a plane orthogonal to the -z plane becomes x 2 /nz 2 +z′ 2 (cos 2 θ ′/ny 2 +sin 2 θ′/nz 2 )=1. That is, equation (4) is derived in this way. From equation (5), sinθ' = [(1/ny 2 - 1/nx 2 )/ (1/ny 2 - 1/nz 2 )] 1/2 ...(6) is derived, and equation (6) is Colored interference fringes appear when viewed from a direction close to the direction of the satisfied angle θ'. However, the angle θ' found here is the angle within the medium film, and in reality, taking into account the refraction of light at the film surface, the angle θ when observed from air (see Figure 3) is need to be converted. If the refractive index of air (which can be considered as 1 in fact) is n 1 and the refractive index of film is n 2 , then
There is a relationship between θ and θ′ as n 1・sinθ=n 2・sinθ′ (7), and if θ is close to 90°, it is actually difficult to observe the film surface from an oblique direction. No colored interference fringes appear. Here, from equations (6) and (7), n 1 = 1, n 2
θ as = 1.6 (average refractive index of PET film)
If we find the condition for >90°, we get sinθ′=[(1/Ny 2 −1/Nx 2 ) /(1/Ny 2 −1/Nz 2 )] 1/2 >0.8 …(8) . Therefore, the principal refractive indices Nx, Ny, Nz are expressed as
If the film satisfies (8), colored interference fringes with strong contrast will not appear even when the film is viewed from an oblique direction. Furthermore, in order to eliminate the interference fringe orders of several orders where the contrast is weak and to make it perfect, calculate the fringe order when tilted most diagonally, that is, under the worst conditions, and this is a constant value. All you have to do is go in the direction of eliminating the contrast. Specifically, Nz=1.60,
It is sufficient to calculate the fringe order when θ=90° (in this case, θ′=38.7°). FIG. 4 shows a diagram of the index ellipsoid in such a case. In this figure, ΔN in the direction of light incidence
If you calculate Using this to calculate the fringe order, N=ΔNd/cosθ'/λ...(10) Since no interference fringes are actually observed when the N value is 4 or more, N>4...(11) Equation (11) By substituting (9), (10) and θ′=38.7°, the condition of 2.3 [(1.642/1/Ny 2 +0.642/N 2 z) 1/2 −Nx] d>4 is obtained. That is, by using a film that satisfies equations (8) and (12) as a protective film for a polarizing film, it is possible to obtain a polarizing plate in which no interference fringes are observed when viewed from any direction. The following table shows the values on the right side of equations (8) and (12) that were verified for PET film samples prototyped in the present invention.
【表】【table】
【表】
サンプルではsinθ′=0.50であるためコントラ
ストの強い干渉じまが認められた。またサンプル
ではsinθ′>0.8ではあるがN=2.2であるためコ
ントラストの弱いうすい干渉縞が認められた。サ
ンプルではsinθ′>0.8,N=4ともに満足して
おり、どの方向から見ても干渉縞は全く認められ
なかつた。
次に本発明の偏光板に使用する偏光フイルムの
素材とその処理方法、偏光フイルムの表面に保護
膜として貼り合わせる着色干渉縞を生じないポリ
エステルフイルムの種類とその処理方法および偏
光フイルムと保護膜との接着に使用する接着剤の
種類等について説明する。
本発明の実施に当たつて用いられる偏光フイル
ムは、ポリビニルアルコール系フイルム、部分ホ
ルマール化ポリビニルアルコール系フイルム、エ
チレン−酢酸ビニル共重合物ケン化物(EVOH)
フイルムの如き親水性高分子系フイルムに、沃素
及び/又は二色性染料の如き偏光素子を、吸着配
向せしめた沃素及び/又は二色性染料系偏光フイ
ルム、又はポリビニルアルコール系フイルムを脱
水処理するか或いはポリ塩化ビニル系フイルムを
脱塩酸処理するかしてポリエンを形成せしめ配向
してなるポリエン系偏光フイルムなどである。
偏光フイルムの片面又は両面に接着剤層を介し
て貼り合わされる保護用のポリエステルフイルム
は、ポリエチレンイソフタレート、ポリプチレン
テレフタレートなどのポリエステルからなるフイ
ルムであつて、これに軸方向の伸延加工を施し、
化学薬品に対する耐蝕性を付与する。
偏光フイルムとポリエステルフイルムとの貼り
合わせに使用される接着剤組成物は、接着特性以
外に、約2〜50μmの厚みにおいて光学的透明性
を有すると共に、含有成分によつて偏光フイルム
の偏光特性を消失又は低下させないものであるこ
とが必要で、好適にはポリエステル系接着剤、ポ
リアクリル系接着剤、エポキシ系接着剤、シアノ
アクリレート系接着剤、ポリウレタン系接着剤、
スピラン系接着剤などを挙げることができる。
さらに、両フイルムの貼り合わせに際しては、
充分な接着強度を得るために、両フイルムの貼り
合わせ界面側を表面処理することが望ましい。
ポリエステルフイルムの表面処理法としては、
スパツタリング法、酸化火災法、或いはプライマ
ー処理法、アルカリ処理法などが使用でき、偏光
フイルムの表面処理法としては、シランカツプリ
ング剤、ポリイソシアネート化合物などによるプ
ライマー処理法などが使用できる。
なお、ポリエステルフイルムの表面(露出面)
に、シリコン系樹脂などを塗布して耐スクラツチ
処理したり、フツ化マグネシウムなどを蒸着など
の手段により形成して透明性を向上させたりする
ことも、偏光板の寿命をを長くすると共に偏光特
性上好ましい。
次に本発明の実施例を図面に基づいて説明す
る。第5図は、本実施例の断面図、第6図は本実
施例の部分切欠斜視図である。両図において、偏
光フイルム2は、沃素を吸着させたポリビニルア
ルコール系フイルムを約4倍の長さに伸延するこ
とによつて沃素分子に配向を与えて偏光性を持た
せた偏光フイルムで、両面にポリイソシアネート
化合物による表面処理が施されている。保護膜1
および3は、厚さ100μm、表面に平行な面内で
の主屈折率の差が0.14、厚さ方向の主屈折率が
1.51となるよう伸延加工されたポリエチレンテレ
フタレートのフイルムで、伸延方向を偏光フイル
ムの偏光軸と直交するようポリエステル系の接着
剤を用いて偏光フイルム2の両面にそれぞれ接着
されている。図には接着剤の層は示されていな
い。図において実線の矢印は偏光フイルム2の偏
光軸の方向を、点線の矢印は保護膜1および3の
伸延の方向を示す。
次に本発明の他の実施例として、上記と全く同
じ偏光フイルム、保護膜および接着剤を使用し、
偏光フイルムの偏光軸と、保護膜の伸延方向とを
一致させて偏光フイルムの両面に保護膜を接着さ
せた偏光板の部分切欠斜視図を第7図に示す。第
7図におて、第6図に示した実施例に対応する構
成要素には第6図の場合と同じ番号を付した。ま
た、第7図においても実線の矢印は偏光フイルム
2の偏光軸の偏光を、点線の矢印は保護膜1およ
び3の伸延の方向を示す。
以上に示した両実施例とも、これら偏光板を白
色光の照射のもとに如何なる方向から観察しても
着色干渉縞は観測されなかつた。即ち、先に述べ
た理論的考察から判るように、本発明に用いた保
護膜としての延伸ポリエステル・フイルムはそれ
自体単独で、着色干渉縞を生じないための光学的
条件を満たしているので、これを偏光フイルムに
貼り付けて本発明の偏光板を構成するに際して、
同ポリエステル・フイルムの延伸方向と偏光フイ
ルムの偏光軸方向の関係は考慮する必要なく任意
でよいが、極端な例として両者を直交ないし平行
させた上記の両実施例もこのことを裏付けたこと
になる。また、液晶表示器に用いる場合のよう
に、これら両実施例による偏光板を互いに平行、
かつ、各々の偏光軸が互いに直交するように保持
して観察を行つても、着色干渉縞は全く観測され
なかつた。
以上の説明から明らかなように、本発明によ
り、単独に用いても、また光軸が互いに直交すよ
う配置しても着色干渉縞の生じない偏光板が得ら
れる。[Table] Since sin θ' = 0.50 in the sample, interference fringes with strong contrast were observed. In addition, in the sample, although sin θ'>0.8, since N=2.2, faint interference fringes with weak contrast were observed. In the sample, both sin θ'>0.8 and N=4 were satisfied, and no interference fringes were observed at all when viewed from any direction. Next, we will discuss the material of the polarizing film used in the polarizing plate of the present invention and its processing method, the type and processing method of the polyester film that does not produce colored interference fringes and is attached as a protective film to the surface of the polarizing film, and the polarizing film and protective film. We will explain the types of adhesives used for bonding. The polarizing film used in carrying out the present invention is a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a saponified ethylene-vinyl acetate copolymer (EVOH).
A polarizing element such as iodine and/or dichroic dye is adsorbed and oriented on a hydrophilic polymer film such as a film, and an iodine and/or dichroic dye polarizing film or a polyvinyl alcohol film is dehydrated. Alternatively, there may be a polyene polarizing film made by subjecting a polyvinyl chloride film to dehydrochloric acid treatment to form polyene and orienting it. The protective polyester film bonded to one or both sides of the polarizing film via an adhesive layer is a film made of polyester such as polyethylene isophthalate or polybutylene terephthalate, which is subjected to an axial stretching process,
Provides corrosion resistance against chemicals. In addition to adhesive properties, the adhesive composition used for laminating the polarizing film and polyester film has optical transparency at a thickness of about 2 to 50 μm, and depending on the ingredients, the polarizing properties of the polarizing film can be improved. It is necessary that the adhesive does not disappear or deteriorate, and suitable adhesives include polyester adhesives, polyacrylic adhesives, epoxy adhesives, cyanoacrylate adhesives, polyurethane adhesives,
Examples include spirane adhesives. Furthermore, when bonding both films together,
In order to obtain sufficient adhesive strength, it is desirable to surface-treat the bonding interface between both films. As a surface treatment method for polyester film,
A sputtering method, an oxidation fire method, a primer treatment method, an alkali treatment method, etc. can be used. As a surface treatment method for the polarizing film, a primer treatment method using a silane coupling agent, a polyisocyanate compound, etc. can be used. In addition, the surface of the polyester film (exposed surface)
In addition, it is possible to extend the life of the polarizing plate and improve its polarizing properties by coating it with a silicone-based resin to make it scratch resistant, or by vapor-depositing magnesium fluoride to improve its transparency. It is preferable. Next, embodiments of the present invention will be described based on the drawings. FIG. 5 is a sectional view of this embodiment, and FIG. 6 is a partially cutaway perspective view of this embodiment. In both figures, the polarizing film 2 is a polarizing film made by stretching a polyvinyl alcohol film on which iodine has been adsorbed to about four times the length to give orientation to the iodine molecules and giving it polarizing properties. surface treatment with a polyisocyanate compound. Protective film 1
and 3 have a thickness of 100 μm, a difference in principal refractive index in the plane parallel to the surface of 0.14, and a principal refractive index in the thickness direction.
A polyethylene terephthalate film that has been stretched to have an angle of 1.51 and is adhered to both sides of the polarizing film 2 using a polyester adhesive so that the stretching direction is perpendicular to the polarization axis of the polarizing film. The adhesive layer is not shown in the figure. In the figure, solid arrows indicate the direction of the polarization axis of the polarizing film 2, and dotted arrows indicate the direction of extension of the protective films 1 and 3. Next, as another embodiment of the present invention, using exactly the same polarizing film, protective film and adhesive as above,
FIG. 7 shows a partially cutaway perspective view of a polarizing plate in which protective films are adhered to both sides of a polarizing film with the polarizing axis of the polarizing film aligned with the extending direction of the protective film. In FIG. 7, components corresponding to the embodiment shown in FIG. 6 are given the same numbers as in FIG. 6. Also in FIG. 7, the solid line arrows indicate the polarization of the polarization axis of the polarizing film 2, and the dotted line arrows indicate the direction of extension of the protective films 1 and 3. In both of the Examples shown above, no colored interference fringes were observed when these polarizing plates were observed from any direction under irradiation with white light. That is, as can be seen from the theoretical considerations described above, the stretched polyester film used as a protective film in the present invention alone satisfies the optical conditions for not producing colored interference fringes. When pasting this on a polarizing film to construct the polarizing plate of the present invention,
The relationship between the stretching direction of the polyester film and the polarization axis direction of the polarizing film does not need to be considered and may be arbitrary, but as an extreme example, both of the above examples in which the two were made perpendicular or parallel supported this. Become. In addition, as in the case of use in a liquid crystal display, the polarizing plates according to both of these embodiments may be arranged parallel to each other.
Moreover, even when observation was performed with the respective polarization axes being held orthogonal to each other, no colored interference fringes were observed. As is clear from the above description, the present invention provides a polarizing plate that does not produce colored interference fringes even when used alone or arranged so that the optical axes are orthogonal to each other.
第1図は直交ニコル光学系の構成図、第2図と
第4図は屈折率楕円体を示す図、第3図はPET
フイルムと空気との接触面における光の屈折状況
を示す図である。第5図と第6図は、それぞれ本
発明実施例の構成を示す断面図および部分切欠斜
視図である。第7図は、本発明の他の実施例の構
成を示す部分切欠図である。第8図は、座標変換
の様子を示す図である。
Figure 1 is a configuration diagram of the orthogonal Nicol optical system, Figures 2 and 4 are diagrams showing the refractive index ellipsoid, and Figure 3 is the PET
FIG. 3 is a diagram showing the state of refraction of light at the contact surface between a film and air. 5 and 6 are a sectional view and a partially cutaway perspective view, respectively, showing the structure of an embodiment of the present invention. FIG. 7 is a partially cutaway view showing the configuration of another embodiment of the present invention. FIG. 8 is a diagram showing the state of coordinate transformation.
Claims (1)
リエステルフイルムにおいて、Nyを特に強く延
伸された方向の屈折率、Nxをこれに垂直方向の
屈折率、Nzを膜厚方向の屈折率としたとき、 〔(1/Ny2−1/Nx2)/(1/Ny2−1/Nz2)〕1/2 >0.8 を満足し、かつ、フイルム厚さをdとしたとき 2.3〔(1.642/1/Ny2+0.642/Nz2)1/2−Nx〕d>4 を満足するポリエステルフイルムが偏光フイルム
の少なくとも片方の面に、接着剤の層を介して貼
り合わされている偏光板。 2 上記接着剤が、ポリエステル系接着剤、ポリ
アクリル系接着剤、エポキシ系接着剤、シアノア
クリレート系接着剤、ポリウレタン系接着剤およ
びスピラン系接着剤の群から選ばれた少なくとも
1つである特許請求の範囲第1項記載の偏光板。[Claims] 1. In a polyester film that has been particularly strongly stretched in one direction parallel to the film surface, Ny is the refractive index in the particularly strongly stretched direction, Nx is the refractive index in the direction perpendicular to this, and Nz is the film thickness. When the refractive index in the direction is [(1/Ny 2 -1/Nx 2 )/(1/Ny 2 -1/Nz 2 )] 1/2 >0.8, and the film thickness is d. A polyester film satisfying 2.3 [(1.642/1/Ny 2 +0.642/Nz 2 ) 1/2 −Nx] d>4 is attached to at least one surface of the polarizing film via an adhesive layer. Combined polarizing plates. 2. A patent claim in which the adhesive is at least one selected from the group of polyester adhesives, polyacrylic adhesives, epoxy adhesives, cyanoacrylate adhesives, polyurethane adhesives, and spirane adhesives. The polarizing plate according to the range 1 above.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13495983A JPS6026304A (en) | 1983-07-22 | 1983-07-22 | Polarizing plate |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13495983A JPS6026304A (en) | 1983-07-22 | 1983-07-22 | Polarizing plate |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6026304A JPS6026304A (en) | 1985-02-09 |
JPH037921B2 true JPH037921B2 (en) | 1991-02-04 |
Family
ID=15140574
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP13495983A Granted JPS6026304A (en) | 1983-07-22 | 1983-07-22 | Polarizing plate |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6026304A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2011059488A (en) * | 2009-09-11 | 2011-03-24 | Sumitomo Chemical Co Ltd | Polarizing plate and liquid crystal display device |
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JP2590005B2 (en) * | 1988-08-12 | 1997-03-12 | 日本ケミファ株式会社 | Anti-dementia agent |
JP2955704B2 (en) * | 1995-07-25 | 1999-10-04 | 株式会社有沢製作所 | Reflective screen for liquid crystal projector for aircraft and method of manufacturing reflective screen for liquid crystal projector |
JP4659265B2 (en) * | 2001-05-02 | 2011-03-30 | 株式会社カネカ | Polarizer protective film and polarizing plate |
JP4888853B2 (en) | 2009-11-12 | 2012-02-29 | 学校法人慶應義塾 | Method for improving visibility of liquid crystal display device, and liquid crystal display device using the same |
KR20160079928A (en) | 2010-06-22 | 2016-07-06 | 도요보 가부시키가이샤 | Liquid crystal display device, polarizing plate and polarizer protective film |
CN103547961B (en) | 2011-05-18 | 2017-07-14 | 东洋纺株式会社 | Liquid crystal display device, Polarizer and polaroid protective film |
US10175494B2 (en) | 2011-05-18 | 2019-01-08 | Toyobo Co., Ltd. | Polarizing plate suitable for liquid crystal display device capable of displaying three-dimensional images, and liquid crystal display device |
WO2013080948A1 (en) * | 2011-11-29 | 2013-06-06 | 東洋紡株式会社 | Liquid crystal display device, polarizing plate, and polarizer protective film |
WO2013080949A1 (en) * | 2011-11-29 | 2013-06-06 | 東洋紡株式会社 | Liquid crystal display device, polarizing plate, and polarizer protective film |
WO2013100041A1 (en) * | 2011-12-28 | 2013-07-04 | 東洋紡株式会社 | Liquid-crystal display device, polarizer, and film for protecting polarizing element |
JP6182858B2 (en) * | 2011-12-28 | 2017-08-23 | 東洋紡株式会社 | Liquid crystal display device, polarizing plate and polarizer protective film |
KR102300768B1 (en) * | 2011-12-28 | 2021-09-09 | 도요보 가부시키가이샤 | Liquid crystal display device, polarizing plate, and polarizer protective film |
KR102149433B1 (en) * | 2012-07-30 | 2020-10-14 | 도요보 가부시키가이샤 | Liquid crystal display device, polarizing plates, and polarizer protection film |
JP6111551B2 (en) * | 2012-08-02 | 2017-04-12 | 東洋紡株式会社 | Liquid crystal display device, polarizing plate and polarizer protective film |
JP6337474B2 (en) * | 2014-01-17 | 2018-06-06 | 東洋紡株式会社 | Polarizer protective film, polarizing plate, and liquid crystal display device |
JP6337481B2 (en) * | 2014-01-28 | 2018-06-06 | 東洋紡株式会社 | Polarizer protective film, polarizing plate and liquid crystal display device |
JP6521216B2 (en) * | 2014-11-25 | 2019-05-29 | 東洋紡株式会社 | Liquid crystal display device and polarizing plate |
JP2018077529A (en) * | 2018-01-22 | 2018-05-17 | 大日本印刷株式会社 | Polarizing plate, manufacturing method of polarizing plate, image display device, manufacturing method of image display device, and light transmissivity improvement method of polarizing plate |
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JPS51136434A (en) * | 1975-05-21 | 1976-11-25 | Hitachi Ltd | Liquid crystal indicating element |
JPS5898709A (en) * | 1981-12-08 | 1983-06-11 | Nitto Electric Ind Co Ltd | Polarizing plate |
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Publication number | Priority date | Publication date | Assignee | Title |
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JPS51136434A (en) * | 1975-05-21 | 1976-11-25 | Hitachi Ltd | Liquid crystal indicating element |
JPS5898709A (en) * | 1981-12-08 | 1983-06-11 | Nitto Electric Ind Co Ltd | Polarizing plate |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2011059488A (en) * | 2009-09-11 | 2011-03-24 | Sumitomo Chemical Co Ltd | Polarizing plate and liquid crystal display device |
Also Published As
Publication number | Publication date |
---|---|
JPS6026304A (en) | 1985-02-09 |
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