JPH01127329A - Laminated body with optical phase function - Google Patents

Abstract

PURPOSE:To enable the title laminated body to use as a phase sheet by sticking to a liquid crystal cell, by a method wherein an optical phase difference board comprised of a laminated film obtained by laminating an optically isotropic noncrystalline film on an optical phase difference elemental film or at least on one side of the film is laminated on a peeled off sheet through an adhesive agent layer. CONSTITUTION:The title laminated body possesses a laminated constitution of an optical phase difference board 1/adhesive agent layer 2/peeled-off sheet 3. A laminated film obtained by laminating an optically isotropic noncrystalline film B on either an optical phase difference elemental film A comprised of a stretched synthetic resin film or at least one side of the film A is used for the optical phase difference board 1. A film which is comprised of noncrystalline molecule whose glass transition point is 60 deg.C or higher, for example, of a high molecule such as polycarbonate and has performed molecular orientation is used for the optical phase difference elemental film A. Polycarbonate is preferable for the optically isotropic noncrystalline film B.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a laminate having optical phase shift, particularly a laminate used as a phase plate for producing a liquid crystal display panel with improved color tone and viewing angle dependence. It's about the body.

A conventional liquid crystal display panel basically has a structure in which polarizing plates are arranged on both sides of a liquid crystal cell.

Polarizing plate ■Liquid crystal cell member Polarizing plate Among these, the liquid crystal cell consists of two substrates with transparent electrode layers placed facing each other with a spacer interposed between them, liquid crystal is sealed between the two substrates, and the periphery is sealed with epoxy adhesive. It has a structure that is completely sealed with an adhesive such as.

Substrate 1 Transparent electrode 1 Liquid crystal 1 Transparent electrode 1 Substrate The substrate is required to be optically transparent and isotropic, otherwise the liquid crystal display panel may be significantly colored and lack visibility. become. Therefore, it is essential to use an amorphous material as the substrate, and conventionally, substrates exclusively made of glass plates have been used. However, glass substrates have problems such as being heavy, not being able to be made thin, being easily damaged and having poor impact resistance, and not being able to be rolled up in one roll, making it difficult to mass produce. Substrates made of wood films are also coming into use.

Liquid crystal display panels are used in large quantities as display devices for office automation equipment such as word processors and personal computers.
A TN (super twisted nematic) liquid crystal is used. However, with this method, the contrast is poor because the background color is yellow, green, or dark blue, and the contrast is even worse when viewed from an oblique direction, which is a problem that is dependent on the viewing angle, resulting in poor visibility for the user. It was not possible to fully meet requests for improvement.

However, recently, with improvements in liquid crystal structure and liquid crystal materials, samples of high-contrast, large-capacity simple matrix liquid crystals with increased black levels have been published one after another, making it possible to achieve high-contrast, almost completely black-and-white displays. Panels and colored panels are now being produced.

Among these, the one that attracts the most attention is the one in which two STN liquid crystal cells are stacked one on top of the other and the coloring such as yellow, green, or dark blue is removed. In the second layer of cells, the arrangement of liquid crystal molecules is reversed, and the coloring that occurred in the first layer is restored. (“Nikkei Microdevice.

(Refer to articles in "August 1987 issue, pages 36-38" and "Nikkei Microdevices, 1987 Lθ issue, pages 84-88") Problems to be solved by the invention However, the black and white 9 display has high contrast. The above-mentioned simple matrix liquid crystal panel has a neutral color tone by stacking two liquid crystal cells (that is, by using one of the liquid crystal cells as a phase plate with an optical phase function). This method attempts to improve the contrast by using a gray color, but using two liquid crystal cells inevitably makes the liquid crystal panel heavier and thicker. This goes against the trend of lighter weight and thinner films. Also,
There is also room for improvement in this respect since it has a viewing angle dependency that causes coloration when viewed from an oblique direction.

The present invention was made in order to solve the above-mentioned problems, and in order to manufacture a liquid crystal display panel with improved contrast and viewing angle dependence by neutralizing the color tone,
V that can be attached to a liquid crystal cell and used as a phase plate
This was done for the purpose of providing a te body.

Means for Solving the Problems The laminate having an optical retardation function of the present invention is an optical retardation element film (
A) or an optical retardation substrate (1) consisting of a laminated film having an optically isotropic amorphous film (B) laminated on at least one side thereof, is placed on a release sheet (3) via an adhesive layer (2). It has a laminated structure.

The present invention will be explained in detail below.

<Optical retardation substrate (1)) As described above, the optical retardation substrate (1) is: (1) an optical retardation functional film (A) made of an oriented synthetic tree film;

(2) A laminated film in which an optically isotropic amorphous film (B) is laminated on at least one side of the optical retardation element film (A) is used.

Here, the optical retardation element film (A) is an amorphous polymer having a glass transition point of 60° C. or higher, such as polycarbonate, phenoxy resin, polyparabanic acid resin,
From polymers such as fumaric acid resin, polyamino acid resin, polystyrene, polysulfone, polyether sulfone, polyarylene ester, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polymethyl methacrylate, polyester, and cellulose polymers. A molecularly oriented film is used.

Such an optical retardation element film (A) is produced by molecularly orienting the above-mentioned polymer film under appropriate temperature conditions, and further performing aging (thermal relaxation) as necessary. Optical retardation film (
When obtaining A) by stretching, conditions such as stretching temperature, stretching ratio, aging temperature, and aging time cannot be unconditionally defined because they vary depending on the type of polymer used. or higher (especially at a temperature 10°C or more higher than the glass transition point).

The stretching ratio is often about 1.1 to 8 times, the aging temperature is above the glass transition point, and the aging time is often about 1 to 300 seconds. Usually, the stretching is carried out in a uniaxial direction.
Depending on the polymer, it may be possible to perform the process biaxially.

In this way, molecular orientation is often achieved by stretching,
Molecular orientation may occur during film formation without stretching, and some types of polymers may have optical rotation, so the molecular alignment may occur naturally.

The optical retardation element film (A) described above can be used alone as an optical retardation substrate (1), but more generally, the mechanical strength of the laminate and the post-process stability, especially thermal stability, retardation element film (A
) is used as a laminated film with an optically isotropic amorphous film (B) laminated on at least one side thereof. An example of an a-layer configuration is (A)/(
B) , (B)/(A)/(B) , (A)/(B
)/(B) , (B)/(B)/(A)/(B)/(
B) etc., and an adhesive layer may be interposed between each layer.

Regardless of whether the optical retardation substrate (1) is in either of the above cases (■) or (■), its overall retardation value is 60n.
- It is desirable that the wavelength is 70 nm or more, and the upper limit is not particularly limited, but it is often about 1000 nm, the transparency is 60% or more, and the heat resistance is 60 nm or more.
Optical retardation substrate (1
) is preferably set to about 5 to 3000 Bm, particularly about 7 to 300 Bm.

Here, as the optically isotropic amorphous film (B), polycarbonate, polyparabanic acid resin, Fehl resin, polystyrene, polyether sulfone, polyarylene ester, cellulose polymer, air permeable synthetic resin surface, crosslinkable resin cured product etc. are listed as preferable.

Among the above, the layer of the crosslinkable resin cured product includes at least one selected from the group consisting of phenoxy ether type crosslinkable resin, epoxy resin, acrylic resin, acrylic epoxy resin, melamine resin, phenol resin, and urethane resin.
Examples include a curable resin composition formed by blending one or more resins with a crosslinking agent capable of reacting with active hydrogen, and phenoxy ether type crosslinkable resins are particularly important. Crosslinking agents capable of reacting with active hydrogen include incyanate groups, carboxyl groups, mercapto groups, and the like.

In addition to heating, irradiation with active energy rays (ultraviolet rays and electron beams) is also used as a curing method.

Among the above, the rR4 air permeable synthetic tree layer has an oxygen permeability (measured according to ASTM D-1434-75) of 3.
0cc/ 24hr @ rn' * below at+w,
Preferably, the layers below the 20cc/24hr*rn'at layer, especially the acrylonitrile component, vinyl alcohol component, or vinylidene halide component, contain 50 mol%.
Examples include a layer formed from a polymer containing the above-mentioned components and a reactive group with the above-mentioned crosslinkable resin. Among these, particularly important are polymers having OH groups, such as polyvinyl alcohol or its copolymerized modified products or graft products, and ethylene-vinyl alcohol copolymers with an ethylene content of 15 to 50 mol %.

When the cured crosslinking resin layer and the air-permeable synthetic resin layer are placed adjacent to each other, the crosslinking agent used to cure the former can simultaneously create close contact with the latter layer, even without an adhesive layer between the two layers. This is advantageous because the lamination of both layers allows the brittleness of the former layer to be covered by the latter layer, and the moisture permeability of the latter layer to be covered by the former layer.

In addition to those exemplified above, examples of the optically isotropic amorphous film (B) include polyester, polysulfone, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyacetate, and poly-4-methylpentene-1.
, a film made of polyphenylene oxide resin, etc. can also be used.

The retardation value (total retardation value when using multiple layers) of the optically isotropic amorphous film (El) used above is preferably 50 nm or less, particularly 40 nm or less.

<Adhesive layer (2)> As the adhesive forming the adhesive layer (2), acrylic adhesive, polyether adhesive, silicone adhesive,
Various adhesives including rubber adhesives are used. In this case, it is particularly preferable to use a curable pressure-sensitive adhesive that initially has tackiness but develops permanent adhesive properties by reacting to light, heat, humidity, etc. over time.

There is no particular limit to the amount of adhesive applied, but it is usually 3 to 50g.
/m'', particularly preferably about 1 O to 30 g/m''.

<Release sheet (3)> Release sheet (3) includes: 1. A paper or plastic sheet or film coated with a silicone release agent made from organopolysiloxane, etc. 2. A sheet or film that itself has releasability ,
For example, plastic sheets or films made of fluororesin, high-density polyethylene, etc.; 3. Plastic sheets or films molded by blending release agents; 4. Graft copolymerization of organopolysiloxane rubber and polyolefin resin. Plastic sheets or films are used.

There is no limit to the thickness of the release sheet (3), but it is usually 12~
The thickness is about 2501 Lm, especially about 30 to 80 IL.

<Laminated body having an optical phase mechanism> The laminate body having an optical phase a-moat according to the present invention is obtained by laminating each of the above-mentioned layers, and as examples thereof are shown in FIGS. 1 to 3. , optical retardation substrate (1)/adhesive layer (2)/
It has a laminated structure of release sheets (3).

When manufacturing the laminate of the present invention, an adhesive is coated on one side of the optical retardation substrate (1) to form an adhesive layer (2), and a release sheet (3) is laminated on top of the adhesive layer (2). You can, but
Since the optical retardation substrate (1) is often easily affected by heat, solvent, tensile force, etc., the adhesive layer (2) is coated on the release sheet (3), and the formed adhesive layer is coated on the release sheet (3). layer(
2) Generally, an optical retardation substrate (1) is laminated thereon, and when the release sheet (3) is peeled off from the obtained laminate, the adhesive layer (2) is attached to the optical retardation substrate. It transfers to (1) and remains.

The optical retardation substrate (1) is obtained in the form of a long film or sheet in which the direction of molecular orientation of the optical retardation element film (A) is the longitudinal direction due to its manufacturing process. When adhering to the cell, care should be taken so that the axis of molecular orientation (that is, the optical axis) of the optical retardation element film (A) is oblique, for example, at an angle of 10'' to 85°.

Therefore, when cutting the laminate into predetermined dimensions after manufacturing the laminate, it is necessary to take care to ensure that the optical axis is at an optimal angle. Alternatively, the optical retardation substrate (1) is cut at a predetermined angle in advance and then adhered onto a release sheet (3) with an adhesive layer (2) to form a laminate.

<Liquid Crystal Display Panel> Generally, a liquid crystal display panel has a structure in which polarizing plates are arranged on both sides of a liquid crystal cell, as described above. A liquid crystal cell has a structure in which liquid crystal is sealed between two substrates provided with transparent electrodes.

After removing the release sheet (3) from the laminate of the present invention, the optical retardation substrate (1) with the adhesive layer (2) is pasted on one of the substrates of a liquid crystal cell, and the optical retardation A polarizing plate will be laminated from above the substrate (1).

Here, as the substrate constituting the liquid crystal cell, a glass plate is most commonly used, but in addition, an optically isotropic film consisting of a single layer or multiple layers of the above-mentioned optically isotropic amorphous film (B) is used. A substrate is also suitably used. It is also effective to use a glass plate as one substrate constituting a liquid crystal cell and use this optically isotropic substrate as the other substrate.

The optically isotropic substrate for this purpose is a single layer of an optically isotropic amorphous film (B) or a lamination of two or more types of optically isotropic amorphous films (B) with or without an adhesive. is preferably used. especially.

When the cured crosslinking resin layer and the air-permeable synthetic resin film layer are arranged adjacent to each other, the advantages of each layer can be utilized as described above, and the disadvantages of each layer can be covered.

Whether the optically isotropic substrate is a single layer or a multilayer, it is desirable that the overall retardation value is 50n+s or less, particularly 40 partsm or less, and its transparency It is preferable that the optically isotropic substrate has chemical resistance (solvent resistance), and the thickness of the optically isotropic substrate is , 20-1000IL, especially 50-800IL1
It is preferable to set it to about 1.

The materials for the transparent electrode formed on the above substrate (glass plate or optically isotropic substrate) include Sn, In, Ti, and P.
Metals such as Tb and Tb or their oxides are commonly used.

The transparent electrode is formed by vacuum evaporation, sputtering, or the like.

The layer thickness of the transparent electrode is set according to required characteristics such as transparency and conductivity, and is usually 100 A or more, and preferably 300 A or more to provide stable conductivity.

STN (super twisted nematic) liquid crystal is preferably used as the liquid crystal, but other types of liquid crystal can also be used depending on the purpose.

As a polarizing plate, ■ polyvinyl alcohol/iodine system, ethylene-vinyl alcohol copolymer/iodine system, ■ polyvinyl alcohol Schiff dichroic dye system, ethylene-vinyl alcohol copolymer/dichroic dye system, ethylene-vinyl alcohol copolymer/dichroic dye system, etc. Polarizing element films such as vinyl alcohol copolymer/polyene, polyvinyl alcohol/polyene, polyhalogenated vinyl/polyene, polyacrylonitrile/polyene, polyacrylate/polyene, polymethacrylate/polyene, etc. 81 layers of the optically isotropic amorphous film (B) as described above are used.

Operation/Use When using the laminate of the present invention, first, the release sheet (3) is peeled off and removed from the laminate. Adhesive layer (2)
Since the adhesive layer (2) is attached to the optical retardation substrate (1), the adhesive layer (2) is attached to one of the substrates of the liquid crystal cell, and a polarizing plate is further laminated thereon. A polarizing plate is also laminated on the other substrate of the liquid crystal cell. In this way, a liquid crystal display panel is created.

By incorporating the optical retardation substrate (1) of the present invention into a liquid crystal cell, the contrast of the liquid crystal display panel is significantly improved, and viewing angle dependence is also significantly improved.

Example Next, the present invention will be further explained with reference to Examples.

Hereinafter, "parts" are expressed on a weight basis.

Example 1 FIG. 1 is a cross-sectional view showing an example of a laminate having an optical retardation function of the present invention, (1) is an optical retardation substrate,
(A) is an optical retardation film, (B) is an optically isotropic amorphous film, (2) is an adhesive layer, and (3) is a release sheet.

Optical retardation element film (A)> Polycarbonate 10 derived from bisphenol A
1 part was added to 150 parts of methylene chloride, and the mixture was stirred and dissolved. This solution was cast onto a glass plate and dried at 40° C. to produce a transparent film with a thickness of 58 μm. Further, this film was stretched three times in one direction at an ambient temperature of 180° C., and then aged.

As a result, the thickness is 32gm and the retardation value is 14.
A 3n+s optical retardation element film (A) was obtained.

<Optical isotropic amorphous film (B)> On a biaxially stretched polyester film with a thickness of 188 JJ and 11, a water/isopropyl alcohol copolymer of ethylene-vinyl alcohol with an ethylene content of 32 mol%
150) A 16% solution of a mixed solvent is cast and dried to form an air-permeable synthetic resin film layer (B-1) with a thickness of l 2 gts, and a layer of the following composition is directly applied on top of the layer (B-1). The crosslinkable resin composition of the phenoxy ether resin type was cast and dried to form a cured crosslinkable resin layer (B-2) with a thickness of 20 gm.

Then, by peeling the laminated film from the biaxially stretched polyester film, a two-layer optically isotropic amorphous film (B) having a layer structure of (B-1)/(B-2) is obtained.
was gotten.

<Optical retardation substrate (1)> Next, the two-layer optically isotropic amorphous film obtained above (B-
1)/(B-2) are adhesively laminated via an acrylic adhesive to form (B-2)/(B-1)/(A)/(B-1)/
A (B-2) type optical retardation substrate (1) was produced.

The thickness of this optical retardation substrate (1) is approximately 1106p, the retardation value is 145nm, and the visible light transmittance is 87.
%, oxygen permeability (measured according to ASTM D-34-75) is 1.2 cc/24hr * m″eat1
1. The pencil hardness of the surface was 2H, and it had no moisture permeability.

<Laminated body with optical phase function> Thickness 50 coated with silicone release agent at 0.5 g/rn'
An adhesive composition with the following formulation was applied to the silicone-coated surface of the release sheet (3) of the tile (■) so that the solid content was approximately 25 g/m'', and dried to form an adhesive layer (2). .

Then, the optical retardation substrate (1) obtained above was adhered onto the adhesive layer (2) to create a laminate having the desired optical retardation function.

This laminate was cut at an angle of 45° to the optical axis to obtain a laminate of predetermined dimensions.

<Liquid crystal display panel> A substrate consisting of a glass plate with a transparent electrode on which a 320A thick ITO (indium tin oxide) layer is provided by sputtering is prepared, and an epoxy adhesive is applied as a sealant between the two substrates. As, STN with torsion angle of about 21O@
(Super twisted nematic) liquid crystal was sealed to create an STN liquid crystal cell.

On one side of this liquid crystal cell, the optical retardation substrate (1) with the adhesive layer (2) after peeling off the release sheet (3) from the cut laminate obtained above is attached, and the L An iodine-based polarizing plate having a visible light transmittance of 42% and a polarization degree of 86% was laminated and bonded. Further, the same iodine-based polarizing plates were laminated and bonded on the other side of the liquid crystal cell so that the optical axes of the two polarizing plates were orthogonal to each other.

The liquid crystal display panel thus obtained has a neutral hue when no voltage is applied, but when a 7 volt charge is applied, the display area becomes dark gray-blue, and the display contrast ratio is 8:1. The results were good, and the viewing angle dependence was also improved.

Comparative Example 1 A liquid crystal display panel was prepared in the same manner as in Example 1 except that the attachment of the optical retardation substrate (1) was omitted, but this panel was green when no voltage was applied, and when the voltage was applied to several volts. When applied, it was a deep blue color with a contrast ratio of 3:1.

Example 2 FIG. 2 is a sectional view showing another example of the laminate having an optical phase function of the present invention.

<Optical retardation element film (A)) 10 parts of polyamino acid resin (manufactured by Ajinomoto Co., Inc.: trade name "Azikoat J") was mixed with 7 parts of dichloroethane/percrene.
3 (heavy water ratio) dissolved in 90 parts of mixed solvent, and this was
An optical retardation element film with a thickness of 4 mm, a retardation value of 110 nm, and a visible light transmittance of 92% was produced by casting on a 0 pm biaxially stretched polyester film (
A) was created.

Optical retardation substrate (1)> On one side of the optical retardation element film (A), a two-layer optically isotropic non-isotropic substrate of (B-1)/(B-2) prepared in Example 1 was applied. The crystalline film (B) was adhesively laminated to obtain an optical retardation substrate (1).

The thickness of this optical retardation substrate (1) is about 85 pm,
Retardation value is 104n, visible light transmittance is 8
It was 6%.

<Laminated body having optical phase function> Acrylic adhesive having the same composition as in Example 1 was applied to the silicone-coated surface of a release sheet (3) made of a silicone-treated polyester film with a thickness of 50 gm.

The adhesive composition is applied and dried to form an adhesive layer (2), and the optically isotropic amorphous film (B) side of the optical retardation substrate (1) obtained above is laminated and pasted thereon. A laminate having an optical phase function was created. This was then cut diagonally to form a laminate of predetermined dimensions.

<Liquid Crystal Display Panel> Using this cut laminate, a liquid crystal display panel was produced in the same manner as in Example 1.

However, as the substrate constituting the liquid crystal display cell, the following optically isotropic substrate was used instead of the glass plate.

That is, two optically isotropic amorphous films having the layer structure (B-1)/(B-2) in Example 1 were
B-1) Laminate and adhere using acrylic adhesive so that the surfaces face each other, and (B-2)/(B-1)/(B-1)
An optically isotropic amorphous film having a four-layer structure having a layer structure of /(B-2) was obtained, and this was used as an optically isotropic substrate. The thickness of this optically isotropic substrate is approximately 75 layers, the retardation value is 2 nm, the visible light transmittance is 92%, and the oxygen transmittance (measured according to ASTM D-1434-75) is 0.8 cc. / 24hr * m' * atm,
The pencil hardness of the surface was 2H, and it had no moisture permeability.

The liquid crystal display panel thus obtained has a neutral hue when no voltage is applied, but when a 7 volt charge is applied, the display area becomes dark gray-blue, and the display contrast ratio is 9:1. The results were good, and the viewing angle dependence was also improved.

Example 3 FIG. 3 is a sectional view showing still another example of the laminate having an optical phase function of the present invention.

After the phenoxy ether resin-based crosslinkable resin composition of Example 1 was cast onto a glass plate, it was dried for 60 minutes in an atmosphere of 70 to 80'C, resulting in a layer of cured crosslinkable resin with a thickness of 1304 m. Got the film. Then this film 1
It was stretched twice in the uniaxial direction at 45°C, and further aged at the same temperature for 20 minutes.

As a result, the thickness is 98 mm and the retardation value is 110.
Since an 8n optical retardation element film (A) was obtained, this was used as a single layer optical retardation substrate (1).

The other conditions were the same as in Example 1, and the optical retardation substrate (
A laminate consisting of 1)/adhesive layer (2)/release sheet (3) was created, and a liquid crystal display panel was also created, but the hue and display contrast showed results similar to those in Example 1, and the viewing angle The degree of improvement in dependence was even better than in Example 1.

Effects of the Invention After peeling and removing the release sheet (3) from the laminate of the present invention, the optical retardation substrate (1) with the adhesive layer (2) is pasted on one substrate of a liquid crystal cell, and By laminating a polarizing plate thereon and also laminating a polarizing plate on the other substrate of the liquid crystal cell, the desired liquid crystal display panel can be easily produced.

By attaching the optical retardation plate (1), it is possible to reduce the weight and thickness of the liquid crystal display panel, as well as improve contrast and reduce viewing angle dependence by making the color tone neutral, which is a concern. Improvements will be made.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a laminate having an optical phase function according to the present invention. FIG. 2 is a sectional view showing another example of a carcass carcass having an optical phase function of the present invention. FIG. 3 is a sectional view showing still another example of the laminate having an optical phase function according to the present invention. (1)... Optical retardation substrate, (2)... Adhesive layer, (3)... Release sheet, (A)... Optical retardation element film. (B), (B-1), (B-2)... Optically isotropic amorphous film patent applicant Fujimori Industries Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. An optical retardation element film (A) made of an oriented synthetic resin film or a laminated film in which an optically isotropic amorphous film (B) is laminated on at least one side thereof. A laminate having an optical retardation function, which has a configuration in which a retardation substrate (1) is laminated on a release sheet (3) via an adhesive layer (2). 2. The retardation value of the optical retardation substrate (1) is 6.
The laminate according to claim 1, which has a thickness of 0 nm or more.