JP3141503B2 - Optical laminated film and liquid crystal display device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical laminated film used for a liquid crystal display device and the like and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Liquid crystal display devices have been used in watches, calculators, laptop word processors, personal computers, etc. due to their features such as light weight, thinness, and low power consumption. However, the liquid crystal display device has a problem in viewing angle characteristics such that the contrast decreases and the hue changes as the viewing angle deviates from the vertical direction of the liquid crystal display device, that is, as the viewing angle increases. This is mainly due to the angle dependence of the birefringence of the liquid crystal cell itself and the super twisted nematic (hereinafter STN).
It is known that this is due to the angle dependence of the birefringence of a retardation film having in-plane birefringence used for a liquid crystal display device, etc., but an effective method for compensating for this. Has not been found yet.

[0003] From the above, the present inventors have made various studies on the improvement of the viewing angle characteristics of a liquid crystal display device, and as a result, added a function of compensating the viewing angle characteristics to a polarizing film indispensable for the liquid crystal display device. The present inventors have found that an optical laminated film in which a layer using a specific inorganic compound and a layer made of a polarizer are laminated has a property of improving the viewing angle characteristics of a liquid crystal display device, and completed the present invention. Was.

[0004]

That is, the present invention provides a method comprising laminating a layer using an inorganic layered compound and having a larger refractive index in a layer in-plane direction than a layer thickness direction and a layer comprising a polarizer. And a liquid crystal display device using the optical laminated film. Hereinafter, the present invention will be described in detail.

The inorganic stratiform compound used in the present invention comprises:
For example, when swelled and dispersed in a medium, laminated on a substrate and dried, when it is dried, it can be deposited on the substrate in a direction parallel to the substrate surface and randomly in the in-plane direction because of its planar structure. The inorganic layered compound layer as a whole has a refractive index structure in which the in-plane retardation is almost 0 and the in-plane average refractive index is larger than the refractive index in the thickness direction. Examples of the inorganic layered compound include a clay mineral. Clay-based minerals are of a two-layer structure having an octahedral layer with aluminum or magnesium as the central metal on top of a silica tetrahedral layer, and a silica tetrahedral layer with aluminum or magnesium as the central metal. Octahedral layers are classified into a three-layer structure sandwiched from both sides. Examples of the former include kaolinites and antigolites, and examples of the latter include smectites, vermiculites, and micas depending on the number of ion exchange cations. Specifically, kaolinite, dickite, nacrite, halloysite, antigorite, chrysotile, pyrophyllite, montmorillonite, hectorite, sodium 4 silicon mica, sodium teniolite, muscovite, margarite, talc, vermiculite, phlogopite , Zansophyllite, chlorite and the like.

As the layer using the inorganic layered compound, the layered inorganic compound may be used alone or as a mixture with another resin. Examples of the method of forming the inorganic layered compound alone as a layer include, for example, a method of laminating a dispersion of the inorganic layered compound on a substrate by a casting method, a coating method and the like, followed by drying and peeling from the substrate. A layer of uniform quality can be obtained continuously. Specifically, it can be obtained by forming an inorganic layered compound layer on a film having releasability such as a polyester film having a surface subjected to a release treatment, and then peeling off the film.

In the case of forming a layer of a mixture of an inorganic layered compound and another resin, a resin having solubility in a medium of a dispersion liquid of the inorganic layered compound can be used as the other resin. Cellulosic resin in that is excellent,
A polyvinyl alcohol-based resin or the like is preferably used.
As a method for forming a layer of a mixture of an inorganic layered compound and another resin, after dissolving a resin having solubility in a medium of a dispersion liquid of the inorganic layered compound, the same treatment as in the case of the inorganic layered compound alone is performed. Examples of the method include:

The above-mentioned inorganic layered compound alone or a mixture of the inorganic layered compound and another resin is laminated on a transparent substrate having no birefringence or having a very low birefringence in terms of handling. It is good also as a layer made to be. Here, the transparent substrate is not particularly limited as long as it does not have birefringence or has a very low birefringence and can uniformly laminate a dispersion of an inorganic layered compound. A cellulosic film, a clean glass substrate, or the like, which has been subjected to a chemical treatment, is preferably used. In addition, a transparent protective layer having no or very low birefringence can be provided on one or both sides of a layer of the inorganic layered compound alone or a layer of a mixture of the inorganic layered compound and another resin. The transparent protective layer is not particularly limited as long as it does not have birefringence or has a very low birefringence.For example, a cellulose-based film subjected to a surface saponification treatment, a clean glass substrate, or the like is preferably used. Can be As a method of laminating the transparent protective layer, for example, a method of laminating with an adhesive, a method of laminating with a low concentration aqueous solution of polyvinyl alcohol by a wet lamination method, or the like can be used.

The layer comprising a polarizer used in the present invention is obtained by orienting a polymer composition containing a dichroic dye or a liquid crystal polymer containing a dichroic dye by a method such as uniaxial stretching. There are, for example, those obtained by adsorbing and orienting iodine molecules on uniaxially stretched polyvinyl alcohol and those obtained by adsorbing and orienting an azo dichroic dye on uniaxially drawn polyvinyl alcohol. Further, the layer made of a polarizer can be provided with a transparent protective layer having no birefringence or a very small birefringence on one or both sides, and it is preferable to provide the transparent protective layer in terms of durability. . As the transparent protective layer, the same layer as the transparent protective layer used in the layer of the inorganic layered compound alone or the layer of the mixture of the inorganic layered compound and another resin can be used. Can be carried out in the same manner as the laminating method.

As a method for laminating a layer composed of a polarizer and a layer using an inorganic layered compound, for example, a dispersion of an inorganic layered compound or a dispersion of a resin and an inorganic layered compound is applied to a layer composed of a polarizer and dried. A method of applying a dispersion of an inorganic layered compound or a dispersion of a resin and an inorganic layered compound on a transparent substrate, laminating a dried layer using a polarizer layer and an adhesive, etc., A method in which a layer of a compound or a layer of a mixture of an inorganic layered compound and another resin is sandwiched between a layer made of a polarizer and a transparent substrate and laminated using an adhesive or the like can be used. As a lamination method using an adhesive, for example, dry lamination, wet lamination and the like are widely applied and are preferably used. In the case of wet lamination, a dispersion of an inorganic layered compound or a dispersion of a resin and an inorganic layered compound can be used as an adhesive.

The method of mounting the optical laminated film obtained above on a liquid crystal display device is not particularly limited, and a method such as applying an adhesive or the like to one or both surfaces of the optical laminated film and bonding the optical laminated film to a liquid crystal cell, or the like. May be used.

[0012]

By using the optical laminated film of the present invention for a liquid crystal display, a liquid crystal display having good viewing angle characteristics can be obtained.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples. Example 1 A synthetic hectorite (trade name: Laponite XLS, manufactured by Nippon Silica Industry Co., Ltd.), which is a clay mineral, was formed on a surface-saponified film of an 80 μm-thick triacetyl cellulose film (Fujitac Fuji Photo Film Co., Ltd.).
1.5% and polyvinyl alcohol (brand name Poval 1)
03 Kuraray Co., Ltd.) A layer having a different refractive index in the thickness direction from the in-plane refractive index obtained by applying and drying an aqueous dispersion containing 1.75% to a film thickness of 3.0 μm after drying is used as an iodine. Series polarizing film (trade name: Sumikaran SH1832A)
(Sumitomo Chemical Co., Ltd.) was wet-laminated with the above aqueous dispersion as an adhesive to obtain an optical laminated film. When this film was used for a TN liquid crystal display device, the viewing angle characteristics were good.

Comparative Example 1 A TN-type liquid crystal display was used in the same manner as in Example 1 except that an iodine-based polarizing film (trade name: Sumikaran SH1832A, manufactured by Sumitomo Chemical Co., Ltd.) was used instead of the optical laminated film. The properties were not good.

Example 2 A synthetic hectorite (trade name: Laponite XLS, Nippon Silica Kogyo Co., Ltd.), a clay mineral, was formed on a surface-treated saponified triacetyl cellulose film (Fujitac Fuji Photo Film Co., Ltd.) having a thickness of 80 μm. Made)
1.5% and polyvinyl alcohol (brand name Poval 1)
03 Kuraray Co., Ltd.) A layer having a different refractive index in the thickness direction from the in-plane refractive index obtained by applying and drying an aqueous dispersion containing 1.75% so as to have a film thickness of 1.0 μm after drying. Series polarizing film (trade name: Sumikaran SH1832A)
Sumitomo Chemical Co., Ltd.) was wet-laminated with the above aqueous dispersion as an adhesive to obtain an optical laminated film. When this film was used in an STN-type liquid crystal display device equipped with a retardation film having negative birefringence, the viewing angle characteristics were good.

Comparative Example 2 An STN-type liquid crystal display device was used in the same manner as in Example 2 except that an iodine polarizing film (trade name: Sumikaran SH1832A manufactured by Sumitomo Chemical Co., Ltd.) was used instead of the optical laminated film. The properties were not good.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Aiko Shimizu 2-10-1, Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Co., Ltd. (72) Inventor Tadashi Shindo 2-10-1, Tsukahara, Takatsuki-shi, Osaka Sumitomo JP-A-3-1055311 (JP, A) JP-A-2-170121 (JP, A) JP-A-4-56802 (JP, A) JP-A-4-56803 ( JP, A) JP-A-64-57203 (JP, A) JP-A-58-149901 (JP, A) JP-A-58-149930 (JP, A) JP-A-2-289824 (JP, A) Patent 3060744 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 5/30 G02F 1/1335 G02F 1/13363

Claims (4)

(57) [Claims] With 1. A layered inorganic compound, and to a compared to the thickness direction the layer plane direction of the large refractive index layer of the layer, a layer comprising the polarizer, characterized in that are stacked
Optical laminated film that. 2. The optical laminated film according to claim 1, wherein a layer using an inorganic layered compound and having a higher refractive index in a layer in-plane direction than a layer thickness direction is laminated on a transparent substrate . 3. A layer using an inorganic layered compound and having a larger refractive index in a layer in-plane direction than a layer thickness direction is a layer comprising an inorganic layered compound and at least one resin.
Or the optical laminated film of 2. 4. Inorganic using layered compound, and a layer refractive index is larger than the thickness direction of the layer plane direction of the layer, a liquid crystal display device comprising a layer made of a polarizer using the optical laminate film obtained by laminating .