JPH10268135A - Bonded compensation polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonded compensation polarizing plate capable of preventing the easy inclusion of an error in an inspection result even in the case of using a separator of double refraction type and implementing an inspection work with an adhesive layer protected with the separator, and further capable of efficiently performing the inspection work of high reliability. SOLUTION: This compensation polarizing plate 7 is formed to have a polarizing plate 1 and a phase difference plate 3 bonded and fixed to each other, so as to keep the absorption axis of the polarizing plate 1 and the optical axis of the phase difference plate 3 in parallel or orthogonal with each other, thereby forming a compensation polarizing plate 4, and an adhesive layer 5 on the outer side of the compensation polarizing plate 4 at the side of the phase difference plate 3 are bonded as well as protected with a transparent separator 6. This separator 6 is made of material having a transmission factor equal to or less than 0.1% in the case of arrangement at an optical axis angle capable of giving maximum extinction between cross Nicol prisms with a transmission factor equal to or less than 0.02%, and the optical axis of the separator 6 and the absorption axis of the polarizing plate 1 are arranged at an intersection angle between 0 and 10 degrees, or 80 and 90 degrees. According to this construction, an inspection work can be executed in such a manner as preventing an effect due to the double refraction function of the separator 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive-type compensating polarizing plate which can easily inspect an optical characteristic abnormality and foreign matter mixing without a mistake while adhering a separator.

[0002]

BACKGROUND OF THE INVENTION Used for forming a liquid crystal display, etc.
A compensating polarizing plate formed by bonding and fixing a polarizing plate and a retardation plate is usually an adhesive type compensating polarizing plate in which an adhesive layer is provided in advance on an outer surface thereof for the purpose of simplifying the bonding operation and the like. ,
Therefore, for the purpose of preventing contamination of the adhesive layer provided on the outer surface, the adhesive layer provided on the outer surface is temporarily adhered and protected by a separator to be subjected to an inspection process or a distribution process. Therefore, the separator
In practical use such as assembling the apparatus, it is removed from the adhesive layer.

The above inspection is for eliminating defective products such as abnormal optical characteristics such as optical distortion, unevenness, and bright spot defects and defective products such as foreign matter inclusions. ,
For the contamination of the transparent foreign material, etc., it is inspected by the method of interposing the phase difference plate of the adhesion type compensating polarizing plate while forming the cross Nicol between the polarizing plate of the adhesion type compensating polarizing plate and the separate analyzer. You. In this case, if there is an abnormality or foreign matter, the light is transmitted and appears as a bright spot.

[0004] However, there is a passing product among those judged to be defective due to the appearance of a bright spot, or a defective product that is judged to be a passing product by showing a uniform dark color without a bright spot. It was found that there was a problem that inspection reliability was poor.

[0005]

The inventors of the present invention have conducted intensive studies to overcome the above-mentioned problems, and have found that there is a problem with the separator. That is, as a separator,
A biaxially stretched film is usually used to make it thin and durable, but the stretching process involves birefringence with large variations such as a bowing phenomenon, and the phase difference due to the birefringence is examined by cross Nicol inspection. It was found that there was room for error in the inspection result, because a bright spot was formed or an abnormal phase difference was offset.

The variation in the birefringence characteristics of the separator is discarded after the protection purpose is attained, and is not an optical element, and is not important for optical characteristics other than transparency. Is not controlled with good uniformity. Therefore, it is possible to prevent an error by using the adhesive-type compensating polarizing plate in a state where the separator is peeled off as an inspection target, and it is possible to perform an inspection with excellent reliability. It takes a lot of time and labor to process such as handling to prevent contamination and damage of the adhesive surface inside, and the inspection efficiency is greatly reduced, which is not practical.

[0007] In addition, even if an isotropic film having no birefringence is used for the separator, a highly reliable inspection can be performed. However, a film having such characteristics is poor in mass productivity and strength, and after the protection purpose is attained. It is not worth using it for discarded separators, nor is it suitable for strength.

Accordingly, the present invention provides a highly reliable inspection which uses a separator having a birefringence as described above and which is less likely to cause errors in the inspection result even when the adhesive layer is protected by the separator. It is an object to obtain an adhesion-type compensating polarizing plate that can be performed well.

[0009]

According to the present invention, there is provided a compensating polarizing plate comprising a polarizing plate and a retardation plate bonded and fixed such that the absorption axis of the polarizing plate and the optical axis of the retardation plate have a parallel relationship or an orthogonal relationship. When the adhesive layer provided on the outer surface on the side of the retardation plate is adhesively protected by a transparent separator, and the separator is arranged at an optical axis angle showing maximum extinction between crossed Nicols having a transmittance of 0.02% or less. With a transmittance of 0.1% or less,
It is an object of the present invention to provide an adhesion-type compensating polarizing plate, wherein the optical axis of the separator and the absorption axis of the polarizing plate are arranged at a crossing angle of 0 to 10 degrees or 80 to 90 degrees.

[0010]

By arranging the separator satisfying the transmittance at the intersection angle, it is possible to prevent the influence of the birefringence of the separator while the separator is adhered, and to perform the inspection under the condition that the depolarization based on the separator is suppressed. It is possible to efficiently and easily perform an inspection with high reliability, which is unlikely to cause an error in the inspection result.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the adhesive compensating polarizing plate of the present invention, a polarizing plate and a retardation plate are bonded and fixed such that the absorption axis of the polarizing plate and the optical axis of the retardation plate have a parallel relationship or an orthogonal relationship. An adhesive layer provided on the outer surface of the compensating polarizing plate on the side of the retardation plate is bonded and protected by a transparent separator, and the separator exhibits maximum extinction between crossed Nicols having a transmittance of 0.02% or less. With transmittance of 0.1% or less when placed at an axial angle, the optical axis of the separator and the absorption axis of the polarizing plate are placed at an intersection angle of 0 to 10 degrees or 80 to 90 degrees. It is.

FIG. 1 illustrates an adhesive type compensating polarizing plate according to the present invention. Reference numeral 4 denotes a compensating polarizing plate formed by bonding and fixing the polarizing plate 1 and the phase difference plate 3 via the adhesive layer 2, and 7 denotes an adhesive formed by bonding and protecting the adhesive layer 5 provided on the outer surface of the compensating polarizing plate 4 with a separator 6. A type-compensating polarizing plate, and 11 is a protective film provided as needed. FIG. 1 illustrates an inspection method, in which 8 is an analyzer and 9 is a surface light source.

In the present invention, when the separator is arranged at an optical axis angle showing maximum extinction between crossed Nicols having a transmittance of 0.02% or less, the transmittance of the separator is 0.1%.
A transparent body having a characteristic of not more than 0.08%, preferably not more than 0.06% is used. The material and the like are not particularly limited as long as they are transparent bodies exhibiting such characteristics. Generally, a film obtained by stretching a plastic film by an appropriate method such as uniaxial or biaxial is used from the viewpoints of strength, handleability, and the like. The thickness of the separator is 5
200 μm, especially 10 to 100 μm, especially 20 to 50 μm
Is generally used, but is not limited to this, and can be appropriately determined according to the strength and the like.

As the above-mentioned plastic film forming the separator, any suitable one can be used without any particular limitation. In general, for example, a film made of polyolefin, polyester, polycarbonate, polyamide, polyimide, polyether sulfone, an acrylic resin, an acetate resin, or the like is used. The plastic film may be formed by an appropriate method such as an extrusion method. Note that the separator is required to be a transparent body exhibiting light transmittance, but need not be colorless.

The formation of the separator exhibiting the above-mentioned transmittance characteristics can be performed by an appropriate method. For example, in the separator made of stretched film, the maximum refractive indices n _x in the plane, the direction of the refractive index perpendicular thereto n _y, the refractive index in the thickness direction is taken as n _z, wherein: Nz = (n _x -n _z) / (that n _x -n _y) Nz defined by is in the range of 1 to 5, i.e., 1 ≦
It can be formed of a stretched film satisfying Nz ≦ 5. A separator can be obtained by providing a coating layer made of an appropriate release agent such as a silicone-based, long-chain alkyl-based, or fluorine-based film on such a stretched film or the like, if necessary.

The above Nz condition defines the uniaxiality of the stretched film. That is, in the present invention, a biaxially stretched product may be used as described above, but in that case, a point that becomes an optical axis appears in a strongly biaxially stretched film, and a bowing phenomenon or the like occurs when the viewing angle is changed. The change in the interference color is remarkable, which tends to hinder the inspection. From the viewpoint of preventing such an obstacle, a preferable separator is 1 ≦ Nz ≦ 4, preferably 1 ≦ Nz ≦ 4.
It is made of a stretched film satisfying Nz ≦ 3.5, particularly 1 ≦ Nz ≦ 2.

There is no particular limitation on the polarizer, retardation plate, adhesive layer, and other components other than the separator used for forming the adhesion-type compensating polarizer of the present invention, and any suitable one can be used. Incidentally, examples of the polarizing plate include iodine and / or two-color hydrophilic polymer films such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, an ethylene-vinyl acetate copolymer-based partially saponified film, and a cellulose-based film. Stretched by adsorbing a reactive dye, and a polyene oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride. The thickness of the polarizing film is usually 5 to 80 μm, but is not limited thereto.

The polarizing plate may be a polarizing film itself or a polarizing film provided with a transparent protective layer on one side or both sides. The transparent protective layer may be formed by an appropriate method such as a film laminating method or a coating method, and an appropriate transparent resin or the like may be used for the formation.

The preferred transparent protective layer is excellent in transparency, mechanical strength, heat stability, moisture shielding property, isotropy and the like. Examples of the separator include, in addition to the plastics exemplified above as the separator, thermosetting or ultraviolet-curing resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone resins. Above all, a film obtained by laminating a film having excellent isotropy such as triacetyl cellulose via an adhesive layer or the like is preferable.

The retardation plate can be obtained as a uniaxially or biaxially stretched film of a transparent plastic, an alignment film of a liquid crystal polymer or the like, or a transparent base material provided with an alignment layer of a liquid crystal polymer or the like. As the plastic, an appropriate plastic may be used.
% Or more is preferable. Among them, polycarbonate, polyester, polysulfone and polyether sulfone, polyolefin such as polystyrene and polyethylene, polypropylene, polyvinyl alcohol and cellulose acetate, polyvinyl chloride and polymethyl methacrylate, polyvinylidene chloride and polyarylate, and polyamide are preferable.

The plastic film for the stretching treatment may be formed by an appropriate method such as a casting method or an extrusion method. A solution casting method such as a casting method is preferred from the viewpoint of obtaining a plastic film with less thickness unevenness and orientation distortion unevenness. The thickness of the plastic film can be appropriately determined depending on the intended retardation and the like,
Generally, it is 10 to 500 μm, especially 20 to 200 μm. The stretching treatment of the plastic film can be performed by an appropriate method.

The retardation plate may be arranged for an appropriate purpose, for example, to prevent coloring or the like due to a change in the viewing angle based on the phase difference of the liquid crystal cell, or to enlarge the good viewing angle.
Therefore, the retardation plate may be formed as a superimposed body of two or more stretched films.

In order to form an adhesive layer provided on the outer surface of the compensating polarizing plate on the side of the retardation plate for bonding and fixing to a liquid crystal cell or the like,
For example, an appropriate adhesive such as acrylic, silicone, polyester, polyurethane, polyether, or rubber can be used. Above all, acrylic pressure-sensitive adhesives are preferred from the viewpoints of optical transparency, adhesive properties, weather resistance and the like. The adhesive layer can also be provided on the polarizing plate side of the compensating polarizing plate.

When an adhesive layer is also provided on the polarizing plate side of the compensating polarizing plate, the adhesive layer may be provided as a protective film 11 as shown in the figure. That is, the above-mentioned separator is used to leave the adhesive layer on the compensating polarizing plate when the separator is peeled off, but the protective film 11 is integrated with the adhesive layer 12 so that it cannot be easily peeled off. . The protective film can be formed as a film according to the transparent protective layer of the polarizing plate described above.

The polarizing film, the transparent protective layer, the retardation plate, the adhesive layer, etc. forming the adhesive type compensating polarizing plate may be formed of, for example, a salicylate compound, a benzophenol compound, a benzotriazole compound, a cyano compound, or a cyano compound. Ultraviolet absorbing ability can be provided by a method of treating with an ultraviolet absorber such as an acrylate compound or a nickel complex compound.

In the adhesive compensating polarizing plate of the present invention, as shown in FIG. 2, the absorption axis (arrow) of the polarizing plate 1 and the optical axis (arrow) of the retardation plate 3 have a parallel relationship or an orthogonal relationship. The optical axis (arrow) of the separator 6 is set to 0 to 10 degrees or 80 to 9 degrees with respect to the absorption axis of the polarizing plate 1 on the compensating polarizing plate fixed by adhesion.
It can be formed by, for example, a method of bonding and positioning so as to have a crossing angle (θ ₂ ) of 0 degrees. With such an arrangement, the influence of the phase difference due to the birefringence of the separator can be prevented or suppressed when the inspection is performed via the analyzer.

In the above description, the parallel or orthogonal relationship at the intersection angle (θ ₁ ) between the absorption axis of the polarizing plate and the optical axis of the retardation plate means a parallel state (θ ₁ = 0) or an orthogonal state (strict). θ ₁ = 90), and the deviation of the crossing angle due to the variation of the arrangement angle due to the adhesive fixing operation is allowed.
If there is a variation in the absorption axis or the optical axis, it is based on the overall average direction. The optical axis of the phase difference plate or the separator may be any optical axis such as a fast axis or a slow axis.

As described above, the adhesive type compensating polarizing plate of the present invention is obtained by bonding the polarizing plate, the retardation plate, and the separator so as to have a predetermined optical axis angle. What is necessary is just to adhere | attach and laminate, and the formation method is arbitrary. For example, the members forming each layer may be sequentially bonded from the top or bottom of the laminated form, or a compensation polarizing plate or a separator with an adhesive layer may be appropriately bonded in advance.

In general, a method of bonding a separator provided with an adhesive layer to a previously formed compensating polarizing plate, or a method of bonding a polarizing film having a protective film on one surface to a retardation plate having an adhesive layer on one surface. Then, a method of adhering a separator provided with an adhesive layer to the retardation plate or the like is employed. According to such a method, an adhesive type compensating polarizing plate can be continuously formed by using a long body for a polarizing plate, a retardation plate, and a separator.

In the above, an appropriate adhesive can be used for the adhesion between the polarizing plate and the retardation plate, the adhesion between the transparent protective layers, and the adhesive layer in the protective film or the like. Those having excellent stress relaxation properties are preferable from the viewpoint of maintaining the optical characteristics. Particularly, for the adhesion between the polarizing plate and the retardation plate and the adhesion between the transparent protective layers, the relaxation elastic modulus is 2 × 10 ⁵ to 1 × 10 ^7. A dyne / cm ² adhesive layer can be preferably used. According to the pressure-sensitive adhesive layer having such a relaxation elastic modulus, while preventing peeling under heating or humidifying conditions, stress generated due to a difference in linear expansion coefficient of each component is relaxed, and optical characteristics due to photoelastic deformation and the like are reduced. Changes can be suppressed. In addition, the above-mentioned relaxation modulus is a viscoelastic spectrometer (10H
Based on the measurement at 23 ° C. according to z).

In the inspection of the adhesive type compensating polarizing plate of the present invention, as shown in FIG. 1, for example, an analyzer 8 disposed on a surface light source 9 is attached to the polarizing plate 1 and the analyzer. It can be carried out by arranging the retardation plate 3 and the separator 6 between them. In the inspection, a layer which is not located between the polarizing plate and the analyzer in the adhesive-type compensating polarizing plate, or a layer having excellent isotropy and low phase difference such as an adhesive layer can be treated as a layer having no influence. .

[0032]

【Example】

Example 1 On one surface of an iodine / polyvinyl alcohol-based polarizing plate (NPF-G1225DU manufactured by Nitto Denko Corporation), a thickness of 20 μm was applied.
Of a polyester film having a thickness of about 38 μm on the retardation plate side of a compensating polarizing plate obtained by adhering a retardation plate having a retardation of about 445 nm made of a stretched polycarbonate film having a thickness of about 100 μm via an acrylic adhesive layer of A separator obtained by treating the uniaxially stretched film with a silicone-based release agent was adhered to the separator via a 20-μm-thick acrylic pressure-sensitive adhesive layer provided on the separator to obtain an adhesion-type compensating polarizing plate.

In the above description, the optical axis (slow axis) of the phase difference plate and the separator is parallel to the absorption axis of the polarizing plate. The separator has an average in-plane retardation of 32.
At 00 nm, the slow axis almost coincides with the stretching (MD) direction, and the extinction transmittance (the transmittance when arranged at an optical axis angle showing the maximum extinction between crossed Nicols having a transmittance of 0.02% or less, the following: The same) was 0.05% and Nz was 1.7. The refractive index in each direction was measured with an Abbe refractometer using sodium D line as a light source (the same applies hereinafter).

Example 2 An adhesive type compensating polarizing plate was prepared in the same manner as in Example 1 except that the lamination was performed so that the slow axis of the retardation plate and the optical axis of the separator were orthogonal to the absorption axis of the polarizing plate. Obtained.

Example 3 A separator composed of a film obtained by subjecting a polyester film having a thickness of about 38 μm to two-stage biaxial stretching was laminated such that its slow axis had an intersection angle of 5 ° with the absorption axis of the polarizing plate. Otherwise in the same manner as in Example 1, an adhesive-type compensating polarizing plate was obtained.
The average value of the in-plane retardation of the separator was 950 nm, and the slow axis was inclined by 2 to 20 degrees with respect to the MD direction. The extinction transmittance was 0.05%, and Nz was 3.2.

COMPARATIVE EXAMPLE 1 A separator composed of a biaxially stretched polyester film having a thickness of about 38 μm was laminated so that its slow axis was at an intersection angle of 15 ° with the absorption axis of the polarizing plate. According to No. 1, an adhesive-type compensating polarizing plate was obtained. The average value of the in-plane retardation of the separator was 950 nm, and the slow axis was MD.
It was inclined by 2 to 36 degrees with respect to the direction. The extinction transmittance was 0.3%, and Nz was 6.9.

Comparative Example 2 An adhesive compensating polarizing plate was obtained in the same manner as in Comparative Example 1, except that the crossing angle of the slow axis of the separator with respect to the absorption axis of the polarizing plate was changed to 5 degrees.

Evaluation Test Transmittance An analyzer (NPF-G1220DU, manufactured by Nitto Denko Corporation) is arranged on the separator side of the adhesive compensating polarizing plate obtained in each of Examples and Comparative Examples, and the analyzer is rotated to visually color. Was set at an angle at which did not appear most, and the light transmittance in that case was examined.

Inspectivity Ten inspectors having more than three years' experience in the inspection performed the inspection according to the work procedure according to the above, and judged the easiness of the inspection.

The results are shown in the following table.

In the inspection characteristics of the above-mentioned table, in Example 1,
In 2, all 10 members of the inspection committee determined that the inspection was easy.
In Example 3, nine out of ten persons determined that the test was easy. However, a rainbow appeared due to a change in the visual angle, and the test was performed while determining the optimum viewpoint. On the other hand, in Comparative Example 1, all 10 persons determined that the inspection was impossible, and in Comparative Example 2, there was light leakage, and 3 out of 10 persons determined that inspection was possible after pointing out the difficulty of the inspection work. The remaining seven persons were determined to be untestable. No error occurred in the inspection result of the example product.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment (an explanatory view of an inspection method).

FIG. 2 is an explanatory diagram of an arrangement relationship.

[Explanation of symbols]

 7: adhesive type compensating polarizing plate 4: compensating polarizing plate 1: polarizing plate 2: adhesive layer 3: retardation plate 5: adhesive layer 6: separator

Claims (2)

[Claims] 1. A compensating polarizing plate, comprising a polarizing plate and a retardation plate, which is bonded and fixed such that an absorption axis of the polarizing plate and an optical axis of the retardation plate have a parallel relationship or an orthogonal relationship. The adhesive layer provided on the outer surface is adhesively protected with a transparent separator,
When the separator is arranged at an optical axis angle showing the maximum extinction between crossed Nicols having a transmittance of 0.02% or less, the separator has a transmittance of 0.1% or less. An adhesive-type compensating polarizing plate, wherein an absorption axis is arranged at a crossing angle of 0 to 10 degrees or 80 to 90 degrees. 2. The method of claim 1, the separator, the maximum in-plane refractive index n _x, the refractive index in the direction of orthogonal thereto n _y, the refractive index in the thickness direction is taken as n _z, wherein: Nz =
_{(N x -n z) / (} n x -n y) Nz defined by 1 to 5
Adhesive-type compensating polarizing plate comprising