JP2000347181A - Optical member and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical member which hardly causes blocking due to stacking and which is excellent in the assembling efficiency for a liquid crystal display device or the like by temporarily applying a separator having specified or higher surface roughness Ra of the outer surface to cover an adhesive layer formed on the outermost surface, especially on one face of an optical material. SOLUTION: The optical member is produced by temporarily applying a separator having >=0.03 μm surface roughness Ra of the outer surface to cover an adhesive layer formed on the outermost surface, especially on one surface of an optical material, and if necessary, by adhering and applying a protective film on the other side of the optical material. As for the optical material, proper material may be used, for example, a polarizing plate, phase difference plate, or elliptic polarizing plate or luminance improving plate produced by laminating those plates to be used to form a liquid crystal display device or the like, and its kind is not especially limited. Therefore, the polarizing plate may be a reflection type or semitransmission type. For example, the optical member consists of a separator 1, adhesive layer 2, polarizing plate 3, protective film 4, phase difference plate 5, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical member which is less likely to cause blocking due to stacking and which is excellent in assembling efficiency of a liquid crystal display device or the like.

[0002]

BACKGROUND OF THE INVENTION A polarizing plate or the like used for forming a liquid crystal display device (LCD) is provided with an adhesive layer for bonding to other members such as a liquid crystal cell in advance for the purpose of increasing the efficiency of LCD assembly and the like. The optical member is used for transportation and storage in a state where it is temporarily covered with a separator so that the exposed adhesive layer is not unnecessarily adhered or contaminated in that case.

However, if the conventional optical members are stacked and transported or stored and then subjected to an automatic assembling operation of a liquid crystal display device or the like, the optical members cannot be separated for each unit due to blocking. Import multiple units,
There has been a problem that the assembling apparatus detects the abnormality and stops the assembling line, thereby lowering the assembling efficiency.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a method of manufacturing a liquid crystal display device by assembling a unit of optical members even when the stacked or stacked unit is transported or stored and used for automatic assembly of a liquid crystal display device or the like. It is an object of the present invention to develop an optical member that can be separated smoothly for each unit, can avoid a stop of an assembly line by taking in a plurality of units, and can efficiently manufacture a liquid crystal display device and the like.

[0005]

According to the present invention, an outermost surface of an optical material, in particular, an adhesive layer provided on one side thereof is temporarily adhered and coated with a separator having an outer surface having a surface roughness Ra of 0.03 μm or more,
Another object of the present invention is to provide an optical member characterized in that the other surface of the optical material is bonded and covered with a protective film as necessary.

[0006]

According to the optical member of the present invention, the rough surface provided on the outer surface of the separator prevents blocking even when transported or stored in a stacked state, and the stacked body is used for a liquid crystal display device or the like. The optical member can be smoothly separated for each unit by the automatic assembling operation, and the stop of the assembling line by taking in a plurality of units can be avoided, so that the liquid crystal display device and the like can be manufactured with high assembling efficiency.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An optical member according to the present invention is prepared by temporarily coating an outermost surface of an optical material, particularly an adhesive layer provided on one side thereof, with a separator having an outer surface having a surface roughness Ra of 0.03 μm or more. If necessary, the other side of the optical material is adhered and covered with a protective film. Examples are shown in FIGS.
It was shown to. 1 is a separator, 2, 21 and 22 are adhesive layers,
3 is a polarizing plate, 4 is a protective film, 5 is a retardation plate, and 6 is a brightness enhancement plate.

The optical material may be any suitable material used for forming a liquid crystal display device such as a polarizing plate, a retardation plate, an elliptically polarizing plate or a brightness enhancement plate obtained by laminating them, and the type thereof is not particularly limited. There is no. Therefore, the polarizing plate may be of a reflection type or a transflective type. Also, the retardation plate may have an appropriate purpose, such as a half-wave plate or a quarter-wave plate or viewing angle compensation. In the case of a laminated type optical material such as the above-mentioned elliptically polarizing plate, the lamination may be performed through an appropriate bonding means such as an adhesive layer.

Incidentally, specific examples of the above-mentioned polarizing plate include iodine and / or iodine on a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. Examples thereof include a film obtained by adsorbing a dichroic dye and stretching, a polarizing film made of a polyene oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride. The polarizing plate may have a transparent protective layer on one or both sides of a polarizing film.

On the other hand, the reflection type polarizing plate is provided with a reflection layer on the polarizing plate, and is used for forming a liquid crystal display device or the like of a type that reflects incident light from the viewing side (display side) to display. In addition, there is an advantage that a built-in light source such as a backlight can be omitted, and the thickness of the liquid crystal display device can be easily reduced. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is provided on one surface of the polarizing plate via a transparent protective layer or the like as necessary.

Specific examples of the reflective polarizing plate include a transparent protective layer which is matted if necessary, and a reflective layer formed by attaching a foil or a vapor-deposited film made of a reflective metal such as aluminum to one surface of the transparent protective layer. can give. Further, there may be mentioned, for example, those in which fine particles are contained in the transparent protective layer to form a fine surface uneven structure, and a reflective layer having a fine uneven structure is provided thereon. The reflective layer is used in a state where the reflective surface is covered with a transparent protective layer, a polarizing plate, or the like, in order to prevent a decrease in reflectance due to oxidation, and to maintain the initial reflectance for a long period of time, and to separately provide a protective layer. Is more preferable.

The reflective layer having the above-described fine uneven structure has an advantage that the incident light is diffused by irregular reflection to prevent directivity and glaring appearance, and that unevenness in brightness can be suppressed.
Further, the transparent protective layer containing fine particles also has an advantage that the incident light and the reflected light thereof are diffused when transmitting the light and the unevenness of light and darkness can be further suppressed.

The reflection layer having a fine uneven structure reflecting the fine uneven structure on the surface of the transparent protective layer is formed by an appropriate method such as an evaporation method such as a vacuum evaporation method, an ion plating method and a sputtering method, and a plating method. The method can be performed by directly attaching a metal to the surface of the transparent protective layer.

For the formation of the transparent protective layer in the above-mentioned polarizing plate, a polymer or the like having excellent transparency, mechanical strength, heat stability and moisture shielding properties is preferably used. Examples of such resins include polyester resins and acetate resins, polyethersulfone resins and polycarbonate resins,
Examples of the resin include a polyamide resin, a polyimide resin, a polyolefin resin, an acrylic resin, and a thermosetting resin such as an acrylic resin, a urethane resin, an acrylic urethane resin, an epoxy resin, or a silicone resin, or an ultraviolet curable resin.

The transparent protective layer may be formed by an appropriate method such as a method of applying a polymer or a method of laminating a film, and the thickness may be appropriately determined. Generally 500 μm
Hereinafter, the thickness is preferably 1 to 300 μm, particularly 5 to 200 μm. The fine particles to be contained in the formation of the transparent protective layer having the fine surface irregularity structure include, for example, an average particle size of 0.5 to 5
Transparent inorganic fine particles of 0 μm silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like, and organic fine particles of a crosslinked or uncrosslinked polymer, etc. Fine particles are used. The amount of fine particles used is 1
It is common to use 2 to 50 parts by weight, especially 5 to 25 parts by weight, per 100 parts by weight.

On the other hand, as a specific example of the above retardation plate, a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefin, polyarylate, or polyamide is stretched. Birefringent film or liquid crystal polymer oriented film,
Examples thereof include a film in which an alignment layer of a liquid crystal polymer is supported by a film.

The retardation plate may have an appropriate retardation in accordance with the intended use, such as, for example, various wavelength plates or ones for the purpose of compensating coloring or viewing angle due to birefringence of the liquid crystal layer. The film may be an obliquely oriented film having a controlled refractive index in the vertical direction. Further, two or more kinds of retardation plates may be laminated to control optical characteristics such as retardation. The above-mentioned obliquely oriented film is, for example, a method in which a heat-shrinkable film is adhered to a polymer film, and the polymer film is stretched and / or shrunk in order to exert its shrinking force by heating, or a method in which a liquid crystal polymer is obliquely oriented. Can be obtained by

The optical material may be formed by laminating two or three or more optical layers, such as a laminate of the above-mentioned elliptically polarizing plate, reflection type polarizing plate and retardation plate. Therefore, as shown in FIGS. 2 and 3, a combination of the polarizing plate 3 and the retardation plate 5 or / and the brightness enhancement plate 6 or a combination of the reflection polarizing plate or the transflective polarizing plate and the retardation plate is used. There may be.

The optical material in which two or three or more optical layers are laminated can also be formed by a method in which the optical materials are laminated separately in the manufacturing process of a liquid crystal display device or the like. The method described above has an advantage in that it is excellent in quality stability, assembling workability, and the like, and can improve manufacturing efficiency of a liquid crystal display device and the like.

The brightness enhancement plate, which is combined with a polarizing plate as necessary to form an optical material, is sometimes referred to as a polarization separating plate or the like. When natural light is incident, linearly polarized light having a predetermined polarization axis is obtained. Or reflect circularly polarized light in a predetermined direction,
Other light shows the characteristic of transmitting light, and is used for the purpose of improving the brightness of the liquid crystal display device.

That is, the brightness enhancement plate receives light from a light source such as a backlight to obtain transmitted light of a predetermined polarization state, and at the same time, inverts the reflected light through a reflection layer or the like to re-enter the brightness enhancement plate. A part or all of the light is transmitted as light in a predetermined polarization state to increase the amount of light transmitted through the brightness enhancement plate, and at the same time, the amount of light that can be used in a liquid crystal display or the like is increased by supplying polarized light that is hardly absorbed by the polarization plate. It is used for the purpose of improving the luminance by a method for achieving the same.

Accordingly, as a brightness enhancement plate, for example, a linearly polarized light having a predetermined polarization axis is transmitted and other light is reflected, such as a multilayer thin film of a dielectric or a multilayer laminate of thin films having different refractive index anisotropy. Those exhibiting characteristics (D-BEF, manufactured by 3M)
Etc.), cholesteric liquid crystal layer, especially cholesteric liquid crystal polymer oriented film and those having the oriented liquid crystal layer supported on a film substrate (manufactured by Nitto Denko Corporation, PCF350 or M
Appropriate materials such as those exhibiting characteristics of reflecting one of the left and right circularly polarized light and transmitting the other light, such as Transmax manufactured by erck, can be used.

In the brightness enhancement plate of the type that transmits linearly polarized light having a predetermined polarization axis, the transmitted light is incident on the polarization plate with the polarization axis aligned as it is, thereby efficiently transmitting the light while suppressing the absorption loss by the polarization plate. Can be done.

On the other hand, a brightness enhancement plate of a type that transmits circularly polarized light, such as a cholesteric liquid crystal layer, can be incident on the polarizing plate as it is. It is preferable that the light is converted into linearly polarized light through the polarizer and then incident on the polarizing plate. Incidentally, by using a quarter-wave plate as the retardation plate and disposing it between the polarizing plate and the brightness enhancement plate, it is possible to convert circularly polarized light into linearly polarized light.

A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region is, for example, a retardation layer that functions as a quarter-wave plate with respect to monochromatic light such as light having a wavelength of 550 nm. , For example, a method of superimposing a retardation layer functioning as a half-wave plate with the retardation layer exhibiting the above retardation characteristic. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement plate may be composed of one or more retardation layers.

The cholesteric liquid crystal layer has a structure in which two or three or more cholesteric liquid crystal layers having different reflection wavelengths are overlapped with each other to reflect circularly polarized light in a wide wavelength range such as a visible light region. Thus, it is possible to obtain circularly polarized light transmitted in a wide wavelength range.

In the optical member according to the present invention, an adhesive layer intended to adhere to another member such as a liquid crystal cell is provided on one or both outermost surfaces of the optical material, and the adhesive layer is provided with a surface roughness of the outer surface. This is temporarily coated with a separator having an Ra of 0.03 μm or more. Therefore, the separator can be provided on both the front and back surfaces of the optical material. In general, an adhesive layer 2 is provided on one side of the optical material as shown in FIG. On the side, a protective film 4 for the purpose of preventing damage to the surface is bonded and coated.

The separator to which the pressure-sensitive adhesive layer is temporarily adhered is used to prevent the contamination of the pressure-sensitive adhesive layer until the pressure-sensitive adhesive layer is put to practical use. The purpose is to prevent excessive adhesion. The separator can be formed by, for example, a method of providing a release coat with an appropriate release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide as needed on a suitable thin leaf.

As the above-mentioned thin leaf, for example, a plastic film or rubber sheet, paper or cloth, nonwoven fabric or net, foamed sheet or metal foil, or a laminate thereof may be used as appropriate. . The thickness of the thin leaf can be appropriately determined according to the strength and the like.
m, especially 5 to 300 μm, especially 10 to 200 μm, but is not limited to this.

On the other hand, the above-mentioned protective film can be formed only on the protective substrate, but is generally formed such that an adhesive layer is provided on the protective substrate and the protective substrate can be peeled off from the optical material together with the adhesive layer. Is done. Therefore, in the case of a separator, the pressure-sensitive adhesive layer is usually left on the optical member by peeling, whereas in the case of a protective film, the surface of the optical material is exposed by peeling.

As described above, the protective film can also be formed according to the separator so that the adhesive layer to which the protective film adheres is left on the optical material. Further, as a protective base material for forming the protective film, an appropriate thin leaf according to the above-described separator can be used.

For forming the pressure-sensitive adhesive layer temporarily attached to the optical material and remaining on the optical material or the pressure-sensitive adhesive layer provided on the protective substrate, an appropriate pressure-sensitive adhesive or pressure-sensitive adhesive can be used, and there is no particular limitation. Incidentally, examples thereof include those using an appropriate polymer such as an acrylic polymer, a silicone polymer, a polyester or a polyurethane, a polyamide or a polyether, a fluorine or a rubber as a base polymer, and the like.

In particular, the formation of the adhesive layer remaining on the optical material is excellent in optical transparency like an acrylic adhesive, and exhibits appropriate wettability, cohesiveness and adhesive adhesive properties, and Those excellent in heat resistance and the like can be preferably used.

In addition to the above, the adhesive layer remaining on the optical material prevents foaming and peeling phenomena due to moisture absorption, prevents deterioration of optical characteristics due to differences in thermal expansion, prevents warpage of the liquid crystal cell, and provides high quality and durability. From the viewpoint of excellent formability of a liquid crystal display device, it is preferable that the liquid crystal display device is formed of a material having a low moisture absorption rate and excellent heat resistance.

The adhesive layer is made of, for example, natural or synthetic resins, especially, tackifier resins, fillers, pigments, coloring agents, oxidizing agents, and the like comprising glass fibers, glass beads, metal powders, and other inorganic powders. It may contain an appropriate additive such as an inhibitor which may be added to the adhesive layer. The adhesive layer remaining on the optical material may be one containing fine particles and exhibiting light diffusivity.

The attachment of an adhesive layer to an optical material or a protective substrate
It can be performed in an appropriate manner. Incidentally, as an example, an adhesive substance or a composition thereof is dissolved or dispersed in a solvent composed of an appropriate solvent alone or a mixture such as toluene or ethyl acetate to prepare an adhesive liquid of about 10 to 40% by weight. Then, it is directly applied on an optical material or a protective substrate by an appropriate developing method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and the optical material or the like is formed. And transfer to the top.

The pressure-sensitive adhesive layer may be provided on the optical member or the protective substrate as a superposed layer of different compositions or types. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, and the like, and is generally 1 to 500 μm, preferably 5 to 20 μm.
0 μm, especially 10 to 100 μm. The pressure-sensitive adhesive layer provided on the optical member or the protective substrate may have the same composition, the same type, or the like, or may have different compositions.

When the outer surface of the separator is smooth, a surface roughness of 0.03 μm or more based on Ra can be obtained by applying an appropriate surface roughening method such as buffing or embossing. Can be formed. Preferred surface roughness R on the outer surface of the separator from the viewpoint of preventing blocking due to stacking, and preventing deterioration of optical properties and adhesive properties due to reflection of surface roughness on the optical element and the adhesive layer.
a is 0.04 to 10 μm, preferably 5 μm or less, particularly 0.0
5-1 μm.

Each layer such as a polarizing plate, a retardation plate, a brightness enhancement plate, a transparent protective layer, an adhesive layer and a separator, which form the optical member, is made of, for example, a salicylate compound, a benzophenol compound, a benzotriazole compound, or the like. A material having an ultraviolet absorbing ability by an appropriate method such as a method of treating with an ultraviolet absorbent such as a cyanoacrylate compound or a nickel complex compound may be used.

The optical member according to the present invention can be preferably used for forming various devices such as a liquid crystal display device.
The liquid crystal display device conforms to a conventional type such as a transmissive type or a reflective type, or a transmissive / reflective type in which the optical member according to the present invention is disposed on one or both sides of a liquid crystal cell via an adhesive layer from which the separator is peeled off. It can be formed as having an appropriate structure.

[0041]

Example 1 A triacetyl cellulose film was adhered to both sides of a polarizing film formed by stretching a polyvinyl alcohol film having a thickness of 80 μm by a factor of 5 in an aqueous iodine solution via a polyvinyl alcohol-based adhesive layer. About 180μ thick
A protective film having a 50 μm thick polyester film and a 20 μm thick acrylic pressure-sensitive adhesive layer provided on the back surface was bonded to one surface of a polarizing plate having a thickness of 50 μm via the pressure-sensitive adhesive layer.

Next, an acrylic adhesive layer having a thickness of 25 μm was provided on the other surface of the polarizing plate through a silicone release coat on the back surface of a separator made of a polyester film having a thickness of 38 μm, and the acrylic adhesive layer was adhered to the separator together with the separator. A member was obtained. The surface roughness R of the outer surface of the separator described above
a was 0.06 μm as measured by a surface roughness meter (Surfcom, manufactured by Tokyo Seimitsu Co., Ltd .; the same applies hereinafter).

Example 2 A separator of a polarizing plate was peeled off, and a retardation plate obtained by uniaxially stretching a polycarbonate film at 170 ° C. was adhered thereto, and the separator provided on the retardation plate had a thickness of 25 μm.
An optical member was obtained in the same manner as in Example 1, except that the m-type acrylic pressure-sensitive adhesive layer was adhered together with the separator.

Example 3 An optical member according to Example 2, except that a retardation plate having a discotic liquid crystal layer of inclined orientation supported by a film substrate (WVA02A, manufactured by FUJIFILM Corporation) was used. I got

Example 4 Film base supporting cholesteric liquid crystal layer and 1/4
Brightness enhancement plate made of a laminate with a wave plate (Nitto Denko Corporation,
PCF350) was adhered to the polarizing plate from which the protective film was peeled off via an acrylic adhesive layer having a thickness of 25 μm, and the peeled protective film was adhered to the exposed surface of the brightness enhancement plate. A member was obtained.

Comparative Example As a separator, the outer surface had a surface roughness Ra of 0.02 μm.
An optical member was obtained in the same manner as in Example 1 except that m was used.

Evaluation Test 30 units of the optical members obtained in Examples and Comparative Examples were sequentially stacked, sealed with a polyethylene inner bag and a moisture-proof aluminum outer bag under reduced pressure, left for 48 hours, and then opened. hand,
The presence or absence of blocking was examined. The results are shown in the following table.

Example 1 Example 2 Example 3 Example 4 Comparative Example Blocking No No No No No Yes

In the above, each unit was blocked via the separator surface in the comparative example.
Then, without blocking, the stack is subjected to an automatic adhesion processing machine and separated smoothly for each unit, the separator is peeled off and adhered to the liquid crystal cell via the adhesive layer, and the stop of the device by taking in multiple units is possible. Did not occur.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of an optical member.

FIG. 2 is a sectional view of another example of an optical member.

FIG. 3 is a cross-sectional view of still another optical member example.

[Explanation of symbols]

 1: separator 2, 21, 22: adhesive layer 3: polarizing plate (optical material) 4: protective film 5: retardation plate (optical material) 6: brightness enhancement plate (optical material)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ning Takahashi 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Inside Nitto Denko Corporation (72) Inventor Homori Mamoru 1-1-1 Shimohozumi, Ibaraki City, Osaka Prefecture No. 2 Nitto Denko Corporation F term (reference) 2H042 BA02 BA03 BA20 DA02 DA11 DA21 DC01 DC02 DE00 2H049 BA02 BA06 BB03 BB54 BC14 BC22 2H091 FA08X FA08Y FA11X FA11Y FA14Y FB02 FD14 GA01 LA02 LA12

Claims (4)

[Claims] 1. An optical member comprising: a pressure-sensitive adhesive layer provided on the outermost surface of an optical material; and a temporary coating of an outer surface with a separator having a surface roughness Ra of 0.03 μm or more. 2. The optical member according to claim 1, comprising a separator on one side of the optical material and a protective film on the other side of the optical material. 3. The optical member according to claim 1, wherein the optical material has at least a polarizing plate or a polarizing plate and a retardation plate or a brightness enhancement plate. 4. A liquid crystal display device comprising the optical member according to claim 1 with its separator removed.