JP2000310712A - Optical laminated body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new diffraction element of which the diffracted rays themselves produce specified polarized light such as circularly polarized light or linearly polarized light. SOLUTION: The optical laminated body is a laminated body which at least comprises a supporting substrate/an adhesive layer 1/a cholesteric liquid crystal layer/an adhesive layer 2/a diffraction element layer/and a protective layer. The protective layer is provided with an ultraviolet ray absorbing property and a hard coatability. Besides the protective layer is formed with at least two layers comprising on ultraviolet ray absorbing layer and a hard coat layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical laminate comprising a novel optical element capable of generating diffracted light having polarization.

[0002]

2. Description of the Related Art A diffractive element is a general-purpose optical element that is widely used in the field of spectral optics and the like for the purpose of splitting light and splitting a light beam. Diffraction elements are classified into several types based on their shape.Amplitude type diffraction elements, in which light-transmitting and non-light-transmitting parts are periodically arranged, are phase-type, in which periodic grooves are formed in a highly transparent material. It is usually classified as a diffraction element. Further, they may be classified as a transmission type diffraction element or a reflection type diffraction element according to the direction in which diffracted light is generated.

In the above-described conventional diffraction element, only non-polarized light can be obtained as diffracted light obtained when natural light (non-polarized light) is incident. Polarizing optical instruments such as ellipsometers, which are frequently used in the field of spectroscopy, can only obtain non-polarized light as diffracted light. In general, a method of using diffracted light through a polarizer in order to use only the polarized light component is used.
In this method, there is a problem that about 50% or more of the obtained diffracted light is absorbed by the polarizer, so that the amount of light is reduced by half. For that purpose, it is necessary to prepare a detector having a high sensitivity and a light source having a large amount of light, and the development of a diffraction element in which the diffracted light itself becomes a specific polarized light such as a circularly polarized light or a linearly polarized light has been required.

[0004] Diffraction elements having a large area are used in fields completely different from the above-mentioned optical equipment, for example, decorations incorporating various designs and authenticity discrimination means. In these applications, they are often exposed to external light, and improvements in light resistance and the like are required.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides an optical laminate which functions suitably as a polarization diffraction element by utilizing a laminate comprising a cholesteric liquid crystal layer and a diffraction element layer. Invented.

[0006]

That is, the present invention relates to a laminate comprising at least a support substrate / adhesive layer 1 / cholesteric liquid crystal layer / adhesive layer 2 / diffraction element layer / protective layer. Relates to an optical laminate having an ultraviolet absorbing property and a hard coat property.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The optical laminate of the present invention comprises at least a support substrate / adhesive layer 1 / cholesteric liquid crystal layer / adhesive layer 2 / diffraction element layer / protective layer. Here, the support substrate / adhesive layer 1 / cholesteric liquid crystal layer / adhesive layer 2 / diffractive element layer / protective layer means the support substrate, adhesive layer 1, cholesteric liquid crystal layer, adhesive layer 2, diffractive element layer, and protective layer. It means a configuration in which layers are stacked in the order of layers.

The support substrate which is a component of the present invention is not particularly limited as long as it has a shape such as a sheet, a film, and a plate. For example, polyimide, polyamide imide, polyamide , Polyether imide, polyether ether ketone, polyether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyvinyl chloride, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene Plastics such as naphthalate, polycarbonate, polyvinyl alcohol, polyacetal, polyarylate, cellulosic plastics, epoxy resin and phenol resin Sheet, film or substrate or paper, paper such as synthetic paper, metal foil, can be appropriately selected from a glass plate or the like. Further, the support substrate may be a substrate having irregularities on its surface.

The adhesive layers (adhesive layer 1 and adhesive layer 2) which are constituents of the present invention are not particularly limited, and various conventionally known adhesives and adhesives, hot-melt adhesives, A heat, light or electron beam curable reactive adhesive or the like can be used as appropriate. Among them, a light or electron beam curing type reactive adhesive is preferably used. The adhesive layer 1 and the adhesive layer 2 may be the same or different, and different types of adhesives and adhesives can be used as appropriate according to the required optical characteristics and the like.

As the reactive adhesive, a prepolymer and / or a monomer having photo- or electron beam polymerizability, if necessary, other monofunctional or polyfunctional monomers, various polymers, a stabilizer, a photopolymerization initiator, A sensitizer or the like can be compounded and used.

Examples of the prepolymer having photo- or electron beam polymerizability include polyester acrylate, polyester methacrylate, polyurethane acrylate, polyurethane methacrylate, epoxy acrylate, epoxy methacrylate, polyol acrylate, polyol methacrylate and the like. . Examples of the monomer having photo- or electron beam polymerizability include monofunctional acrylate, monofunctional methacrylate, difunctional acrylate, difunctional methacrylate, trifunctional or higher polyfunctional acrylate, and polyfunctional methacrylate. These can also use a commercial item, for example, Aronix (acrylic special monomer, oligomer;
Toagosei Co., Ltd.), Light Ester (Kyoeisha Chemical Co., Ltd.), Biscoat (Osaka Organic Chemical Industry Co., Ltd.)
Etc. can also be used in the present invention.

As the photopolymerization initiator, for example, benzophenone derivatives, acetophenone derivatives, benzoin derivatives, thioxanthones, Michler's ketone, benzyl derivatives, triazine derivatives, acylphosphine oxides, azo compounds and the like can be used. .

The viscosity of the light or electron beam curable reactive adhesive which can be used in the present invention is appropriately selected depending on the processing temperature of the adhesive and cannot be unconditionally determined. ~ 2000 mPa · s, preferably 50
１０００1000 mPa · s, more preferably 100 to 50
0 mPa · s. When the viscosity is lower than 10 mPa · s, it is difficult to obtain a desired thickness. 2000mPa
-If it is higher than s, workability may decrease, which is not desirable. If the viscosity is out of the above range,
It is preferable to adjust the solvent and the proportion of the monomer appropriately to obtain a desired viscosity.

When a photo-curing reactive adhesive is used, a known curing method such as a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, or a xenon lamp is used as a method for curing the adhesive. be able to. Although the exposure amount cannot be determined unconditionally because it differs depending on the type of the reactive adhesive used, it is usually 50 to 2000 mJ.
/ Cm ² , preferably 100 to 1000 mJ / cm ² .

When an electron beam-curable reactive adhesive is used, the method of curing the adhesive is appropriately selected depending on the penetrating power and the curing power of the electron beam, and cannot be determined unconditionally. Usually, curing can be carried out by irradiating under an acceleration voltage of 50 to 1000 kV, preferably 100 to 500 kV.

When a hot-melt type adhesive is used as the adhesive layer in the present invention, the adhesive is not particularly limited, but a hot-melt working temperature of 80 to 200 ° C., preferably about 100 to 160 ° C. Is desirably used from the viewpoint of workability and the like. Specifically, for example, polyvinyl acetal resins such as ethylene-vinyl acetate copolymer resins, polyester resins, polyurethane resins, polyamide resins, thermoplastic rubbers, polyacrylic resins, polyvinyl alcohol resins, and polyvinyl butyral And those manufactured using petroleum-based resins, terpene-based resins, rosin-based resins, and the like as base resins.

Further, the use of a pressure-sensitive adhesive as the adhesive layer in the present invention is not particularly limited. For example, a rubber-based, acrylic, silicone-, or polyvinyl ether-based pressure-sensitive adhesive can be used. The thickness of the adhesive layer varies depending on the application to be used and its workability and cannot be unconditionally determined, but is usually 0.5 to 50 μm, preferably 1 to 10 μm.

The method for forming the adhesive layer varies depending on the method for producing the optical laminate of the present invention described below. Examples of the method include a roll coating method, a die coating method, a bar coating method, a curtain coating method, an extrusion coating method, and the like. It can be formed on a support substrate or the like using a known method such as a gravure roll coating method, a spray coating method, and a spin coating method.

The cholesteric liquid crystal layer which is a component of the present invention is not particularly limited as long as it is a cholesteric liquid crystal film, sheet, or plate having a fixed cholesteric orientation. The cholesteric liquid crystal film can be formed from a polymer liquid crystal, a low molecular liquid crystal, a mixture thereof, or the like.

The polymer liquid crystal is not particularly limited as long as the cholesteric alignment can be fixed.
Any of a side chain type polymer liquid crystal and the like can be used.
Specific examples include main-chain liquid crystal polymers such as polyester, polyamide, polycarbonate, and polyesterimide, and side-chain liquid crystal polymers such as polyacrylate, polymethacrylate, polymalonate, and polysiloxane. Among them, a liquid crystalline polyester which has good orientation in forming cholesteric orientation and is relatively easy to synthesize is desirable. As the structural unit of the polymer,
For example, aromatic or aliphatic diol units, aromatic or aliphatic dicarboxylic acid units, and aromatic or aliphatic hydroxycarboxylic acid units are preferred examples.

Examples of the low-molecular liquid crystal include those having a basic skeleton of a biphenyl derivative, a phenylbenzoate derivative, a stilbene derivative or the like into which a functional group such as an acryloyl group, a vinyl group or an epoxy group is introduced. As the low-molecular liquid crystal, both lyotropic properties and thermotropic properties can be used, but those exhibiting thermotropic properties are more preferable from the viewpoint of workability, process and the like.

A method for fixing the cholesteric alignment is a known method. For example, in the case of using a polymer liquid crystal, a polymer liquid crystal is disposed on an alignment substrate, and then a cholesteric liquid crystal phase is developed by heat treatment or the like. A method of quenching to fix the cholesteric orientation can be used. When a low-molecular liquid crystal is used, a low-molecular liquid crystal is disposed on an alignment substrate, a cholesteric liquid crystal phase is developed by a heat treatment or the like, and the cholesteric liquid crystal phase is crosslinked by light, heat, or an electron beam while maintaining the state. A method of fixing the orientation or the like can be appropriately adopted. Further, a diffraction element layer which is a component of the present invention can be used as an alignment substrate.

In order to improve the heat resistance and the like of the cholesteric liquid crystal layer, a crosslinking agent such as a bisazide compound or glycidyl methacrylate may be added to the high-molecular liquid crystal or the low-molecular liquid crystal within a range that does not hinder the development of the cholesteric phase. By adding these cross-linking agents, cross-linking can be performed in a state where a cholesteric phase is developed. In addition, dichroic dyes in high-molecular liquid crystals and low-molecular liquid crystals are used as long as they do not interfere with the expression of the cholesteric liquid crystal phase.
Various additives such as dyes and pigments may be appropriately added as long as the effects of the present invention are not impaired.

The structure of the cholesteric liquid crystal layer, which is a component of the present invention, usually comprises one layer of a cholesteric liquid crystal film in which cholesteric orientation is fixed. Further, a configuration in which a plurality of cholesteric liquid crystal films are laminated according to the application and required optical characteristics may be employed.

The thickness of the cholesteric liquid crystal layer is usually 0.1.
If it is 3 to 20 μm, preferably 0.5 to 10 μm, and more preferably 0.7 to 3 μm, the effect of the present invention may not be exhibited if it is out of the above range. When the cholesteric liquid crystal film is composed of a plurality of layers, the total thickness of all the films is preferably in the above range.

The diffractive element layer which is a component of the present invention is not particularly limited as long as it has a diffractive effect by providing a difference in transmittance, thickness, refractive index and the like. For example, a relief hologram having unevenness on the surface or a volume phase hologram having a refractive index difference inside can be suitably used. In addition, for example, a commercially available Commer manufactured by Edmund Scientific Inc.
Cial Grade ruled line diffraction grating, transmission type diffraction grating film, Ruled Gr manufactured by JOBIN YVON
Ating and the like can also be used.

Examples of the material for forming the relief hologram include thermoplastic resins such as vinyl chloride, polyester, acrylic resin and cellulose resin, and photo-curable resins such as acrylic resin. The relief hologram may be provided with a thin aluminum film by vapor deposition or the like in order to improve the appearance of the diffraction image. Such a relief hologram can also be used as a diffraction element layer.

The material for forming the volume phase hologram is not particularly limited. For example, a silver salt film, gelatin dichromate, a photosensitive resin or the like can be used as the material.

The thickness of the diffraction element layer is usually 0.3 to 20 μm.
m, preferably 0.5 to 10 μm, more preferably 0.7 to 3 μm. If the ratio is out of this range, the effects of the present invention may not be effectively exhibited. The protective layer, which is a component of the present invention, is not particularly limited as long as it has an ultraviolet absorbing property and a hard coat property. For example, a material in which a protective layer-forming material containing an ultraviolet absorber and a hard coat agent is formed into a film, a sheet, a thin film, or a plate. Further, a protective layer having an ultraviolet absorbing property made of a protective layer forming material containing an ultraviolet absorbent (hereinafter, referred to as an ultraviolet absorbing layer) and a protective layer having a hard coating property made of a protective layer forming material containing a hard coat agent (Hereinafter, a hard coat layer) may be used as the protective layer in the present invention. In addition, a laminate of a commercially available ultraviolet cut film and a hard coat film can be used as the protective layer. A laminate formed by applying various hard coat agents to the ultraviolet absorbing layer to form a film can also be used as the protective layer. Here, the ultraviolet absorbing layer and the hard coat layer are 2
It may be formed of layers or more, and each layer can be laminated via an adhesive layer or the like.

As the material for forming the protective layer, those having high light transmittance are desirable. For example, polyethylene, polypropylene, poly (4-methyl-pentene-1), polystyrene, ionomer, polyvinyl chloride, polymethyl methacrylate, polyethylene terephthalate, polyamide,
A material obtained by adding an ultraviolet absorber and / or a hard coat agent to polysulfone, a cellulose resin, or the like can be used. Further, as the protective layer, an adhesive composition obtained by adding an ultraviolet absorber and / or a hard coat agent to the heat, light or electron beam-curable reactive adhesive described above can also be used. The cured product can be used as a protective layer.

The ultraviolet absorber is not particularly limited as long as it is compatible or dispersible in the protective layer forming material. For example, a benzophenone compound, a salsylate compound,
Organic ultraviolet absorbers such as benzotriazole-based compounds, oxalic anilide-based compounds, and cyanoacrylate-based compounds, and inorganic ultraviolet absorbers such as cesium oxide, titanium oxide, and zinc oxide can be used. Among them, a benzophenone-based compound having high ultraviolet absorption efficiency is preferably used. In addition, one or more ultraviolet absorbers can be added. The blending ratio of the ultraviolet absorber in the protective layer varies depending on the material for forming the protective layer to be used.
It is 1 to 20% by weight, preferably 0.5 to 10% by weight.

The hard coating agent is not particularly limited as long as it is compatible or dispersible in the protective layer forming material.
For example, use of an inorganic compound such as an organopolysiloxane-based, photo-curable resin-based acrylic oligomer-based, urethane acrylate-based, epoxy acrylate-based, polyester acrylate-based, thermosetting resin-based acryl-silicone-based, or ceramics. Can be. Above all, an organopolysiloxane-based or photo-curable resin-based acrylic oligomer-based hard coat agent is preferably used from the viewpoint of film-forming properties and the like. These hard coat agents are
Either a solventless type or a solvent type can be used.

The material for forming the protective layer includes, in addition to an ultraviolet absorber and a hard coat agent, if necessary, a light stabilizer such as a hindered amine or a quencher, an antistatic agent, a slipperiness improver, a dye, a pigment, a surfactant. Various additives such as fillers such as fine silica and zirconia can also be blended. The mixing ratio of these various additives is not particularly limited as long as the effects of the present invention are not impaired, but is usually 0.01 to 10% by weight, preferably 0.05 to 5% by weight.

The ultraviolet absorbing layer constituting the protective layer can be formed using a material obtained by appropriately blending the above-described protective layer forming material with an ultraviolet absorbing agent and, if necessary, a light stabilizer. Further, a commercially available ultraviolet cut film or the like can be used as the ultraviolet absorbing layer in the present invention.

The hard coat layer constituting the protective layer is
The protective layer can be formed by using a material in which a hard coat agent and various additives are added to the protective layer forming material described above. The hard coat layer may be formed by applying the above hard coat agent on a transparent support film. As a transparent support film, polymethyl methacrylate, polystyrene, polycarbonate,
Examples include films formed from polyether sulfone, polyphenylene sulfide, amorphous polyolefin, triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, and the like.

The ultraviolet absorbing layer and the hard coat layer may be laminated via an adhesive or the like to form a protective layer according to the present invention. Suitable examples of the adhesive include the above-described heat, light, or electron beam curing type reactive adhesive. The protective layer can also be formed by using an adhesive containing an ultraviolet absorbent and laminating a separately prepared hard coat layer on the cholesteric liquid crystal layer. Further, a dye, a pigment, a surfactant and the like may be appropriately added to the adhesive as needed.

Further, as the hard coat layer, a vehicle resin for gravure ink or the like can be preferably used.
Examples of the gravure ink vehicle resin include nitrocellulose, ethylcellulose, polyamide resin, vinyl chloride, chlorinated polyolefin, acrylic resin, polyurethane, and polyester. In addition, hard resins such as ester gum, dammar gum, maleic resin, alkyd resin, phenol resin, ketone resin, xylene resin, terpene resin, petroleum resin, etc. are used in the gravure ink vehicle resin in order to improve adhesion and film strength. May be blended.

The structure of the hard coat layer can be a single hard coat layer or a composite layer depending on the required weather resistance and the like. As the composite layer, for example, a hard coat layer containing an organopolysiloxane, a hard coat layer containing a photocurable resin, a hard coat layer containing a thermosetting resin,
A composite layer composed of two or more layers, such as a hard coat layer containing an inorganic compound, may be used as the hard coat layer.

Further, the degree of the hard coat property, that is, the hardness, cannot be unconditionally determined by the material constituting the optical laminate of the present invention. However, when the evaluation is carried out according to the test method described in JIS L0849, the determination of discoloration is made. It is desirable that the standard is at least 3 or more, preferably 4 or more.

The protective layer, which is a component of the present invention, and the ultraviolet absorbing layer and the hard coat layer constituting the protective layer are generally formed by a roll coating method, a dipping method, a gravure coating method, a bar code method, a spin coating method, or the like. Known methods such as a method, a spray coating method, and a printing method can be employed. After forming a film on the diffraction element layer or the support film by these methods, a protective layer can be formed by performing a post-treatment according to the protective layer forming material used. Examples of a method for forming a protective layer composed of a composite layer of an ultraviolet absorbing layer and a hard coat layer include, for example, a method in which a hard coating agent is applied directly to the ultraviolet absorbing layer, a method in which the ultraviolet absorbing layer is laminated via an adhesive, and the like. .

The thickness of the protective layer cannot be specified unconditionally because it differs depending on the required performance of the ultraviolet absorbing property and the hard coating property, but it is usually 0.1 to 100 μm, preferably 1 to 50 μm. Also, when the protective layer is formed of a composite layer with an ultraviolet absorbing layer and a hard coat layer, the total thickness of each layer is preferably within the above range.

The method for producing the optical laminate of the present invention includes:
(1) Laminate sequentially on a support substrate to have the configuration of the present invention. (2) Press, heat, and cure the remaining laminate separately manufactured on a support substrate having an adhesive layer formed on the surface in advance. (3)
On the supporting substrate, the remaining laminated body separately prepared is prepared on a peelable substrate, and the peeling substrate is removed by transferring the pressure, heating, curing, etc. to the supporting substrate side alone or in combination. Method and the like.

As a more specific example of the production method, (1) a cholesteric liquid crystal layer formed on an alignment substrate is supported by forming an adhesive layer on a support substrate or a cholesteric liquid crystal layer on which an adhesive layer is previously formed. Transfer to a substrate, and peel off the alignment substrate. Then, a separately prepared diffraction element layer is laminated on the cholesteric liquid crystal layer via an adhesive, and then a protective layer is formed on the diffraction element layer. (2) The cholesteric liquid crystal layer formed on the alignment substrate is transferred to the diffraction element layer And
The alignment substrate is peeled off. Next, an adhesive layer is formed on a support substrate or a cholesteric liquid crystal layer on which an adhesive layer has been formed in advance, and a laminate including a cholesteric liquid crystal layer / adhesive layer / diffraction element layer is laminated on the support substrate. Then, a method of forming an ultraviolet absorbing layer and a hard coat layer on the diffraction element layer, (3) transferring the cholesteric liquid crystal layer formed on the alignment substrate to a second substrate different from the alignment substrate via an adhesive layer, The substrate is peeled off and the cholesteric liquid crystal layer is transferred to the support substrate on which the adhesive layer has been formed in advance,
The second substrate is peeled and removed. Then, a method of laminating a diffraction element layer on a cholesteric liquid crystal layer via an adhesive layer, and laminating an ultraviolet absorbing layer and a hard coat layer on the diffraction element layer via an adhesive layer can be used.

Here, the second substrate (hereinafter, referred to as a re-peelable substrate) is not particularly limited as long as it has a re-peelable property and has a self-supporting property. Usually, a plastic film having releasability is desirably used. The term "removability" as used herein means that the cholesteric liquid crystal layer and the removable substrate can be separated at the interface between the adhesive and the removable substrate in a state where the cholesteric liquid crystal layer and the removable substrate are bonded via the adhesive. As such a removable substrate, specifically, polyethylene, polypropylene, olefin resins such as 4-methylpentene-1 resin, polyamide, polyimide, polyamideimide, polyetherimide, polyetherimide, polyetherketone, Polyether ether ketone, polyether sulfone, polyketone sulfide, polysulfone, polystyrene, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate,
Polyarylate, polyacetal, polycarbonate,
Examples include polyvinyl alcohol and cellulose-based plastic. These plastic films may be used by themselves, or those coated with silicone or fluororesin, organic thin films or inorganic thin films formed on the surface of these plastic films to have appropriate removability. Those subjected to chemical treatment and those subjected to physical treatment such as vapor deposition and surface polishing can also be used.

The adhesive used for transferring the cholesteric liquid crystal layer to the removable substrate is not particularly limited, but it is preferable to use the heat and heat described above.
A light or electron beam curable reactive adhesive or the like can be used as appropriate.

Further, examples of the peeling and removing method in the above-mentioned manufacturing method include, for example, a method in which an adhesive tape is applied to a corner end of an oriented substrate or a removable substrate and artificially peeled off, or a mechanical peeling using a roll or the like. Method, method of mechanically peeling after immersion in poor solvent for all structural materials, method of peeling by applying ultrasonic wave in poor solvent, thermal expansion coefficient of cholesteric liquid crystal layer with alignment substrate or releasable substrate A method of peeling by giving a temperature change using the difference can be appropriately adopted.

The above manufacturing method is merely an example, and the optical laminate of the present invention is not limited to these. The optical laminated body of the present invention obtained in this manner has a very wide range of applications as a new diffractive function element because the diffracted light has a circular polarization property, which is a unique feature not found in conventional optical elements. For example, it can be used as various optical elements including a polarizing plate, optoelectronic elements, decoration materials, forgery prevention elements, and the like.

As an optical element or an optoelectronic element, for example, a transparent and isotropic film as a supporting substrate,
For example, triacetyl cellulose films such as Fujitac (manufactured by Fuji Photo Film Co., Ltd.) and Konikatac (manufactured by Konica Corporation), TPX films (manufactured by Mitsui Chemicals, Inc.),
Various types of optical laminates of the present invention are obtained using Arton film (manufactured by Nippon Synthetic Rubber Co., Ltd.), ZEONEX film (manufactured by Nippon Zeon Co., Ltd.), acrylene film (manufactured by Mitsubishi Rayon Co., Ltd.), etc. It is possible to expand to various optical applications. For example, if the optical laminate is TN
(Twisted nematic)-LCD (Liqu
id Crystal Display), STN (S
upper Twisted Nematic) -LC
D, ECB (Electrically Contro
lled Birefringence)-LCD, O
MI (Optical Mode Interfere)
nce) -LCD, OCB (Optically Co.)
mpensated Birefringence)-
LCD, HAN (Hybrid Aligned Ne)
magnetic) -LCD, IPS (In Plane S)
By providing a liquid crystal display such as a switching-LCD, various LCDs with improved color compensation and / or improved viewing angle can be obtained. In addition, the optical laminate of the present invention can be used as an optical device that requires dispersed polarized light, a polarizing optical element that obtains a specific wavelength by a diffraction phenomenon, an optical filter, a circularly polarizing plate, and a light diffusing plate. It is possible to provide various optical members that can exhibit an optical effect that has not existed as an optical element or an optoelectronic element, for example, a linear polarizing plate can be obtained by combining with a quarter-wave plate.

As the decorative member, various design molding materials can be obtained, including a new design film having a combination of iridescent coloring effect by diffractive ability and colorful coloring effect by cholesteric liquid crystal. In addition, since it can be made into a thin film, it can be expected to greatly contribute to differentiation from other similar products by a method of attaching it to an existing product or the like or integrating it. For example, when the optical laminate of the present invention incorporating a diffractive pattern having a design is attached to a glass window or the like, the selective reflection characteristic of the cholesteric liquid crystal accompanied by the diffraction pattern looks different from the outside depending on the viewing angle. , It will be excellent in fashionability. In addition, the interior can be hardly seen from the bright outside, and nevertheless, a window with good external visibility can be provided from the inside.

The anti-counterfeit element can be used as a new anti-counterfeit film, seal, label, etc. having both the anti-counterfeit effect of the diffraction element and the cholesteric liquid crystal. Specifically, as a supporting substrate constituting the optical laminate of the present invention, for example, a card substrate such as a car driver's license, an identification card, a passport, a credit card, a prepaid card, various cash vouchers, a gift card, a securities, a mount, etc. By using the optical laminate, the optical laminate of the present invention can be integrated with a card substrate, a mount, or the like, or can be provided in part, specifically, pasted, embedded, or woven into paper. In addition, the optical laminate of the present invention has the anti-counterfeiting effect that the forgery of the diffractive element is difficult unless the hard coat layer is destroyed by being covered with the viewing angle characteristics and the hard coat layer of the diffractive element, and the wavelength-selective reflectivity of the cholesteric liquid crystal,
It combines circular polarization selective reflection, viewing angle dependence of color, and anti-counterfeiting effect by beautiful cholesteric color. Therefore, forgery of the optical laminate of the present invention is very difficult. Further, the optical laminate of the present invention is very useful as an anti-counterfeit element, such as having an iridescent color effect of a diffractive element and an excellent design because of having a vivid color effect of a cholesteric liquid crystal. .

These applications are only examples, and the optical laminate of the present invention can exhibit various applications in which a single diffraction element or a single cholesteric liquid crystal film is conventionally used, or exhibit a new optical effect. Because it is possible, it can be applied to various applications other than the above-mentioned applications.

[0052]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Reference Example 1: Synthesis of Liquid Crystalline Polyester
Terephthalic acid 50 mmol, hydroxybenzoic acid 20 m
mol, 20 mmol of catechol, 10 mmol of (R) -2-methyl-1,4-butanediol and 100 mg of sodium acetate at 180 ° C. under a nitrogen atmosphere.
The polycondensation reaction was performed while the temperature was raised stepwise at 200 ° C. for 1 hour and at 250 ° C. for 1 hour.

Next, the polycondensation reaction was continued at 250 ° C. for 2 hours while flowing nitrogen, and the polycondensation was further performed at the same temperature under reduced pressure for 1 hour. After dissolving the obtained polymer in tetrachloroethane, reprecipitation was performed with methanol to obtain a liquid crystalline polyester. N-methyl-2 of the obtained liquid crystalline polyester
A pyrrolidone solution (20% by weight) was prepared, and the solution was applied to a rubbed polyphenylene sulfide film by a spin coating method. After the application, a drying treatment was performed to remove N-methyl-2-pyrrolidone, and a liquid crystalline polyester coating film was formed on the polyphenylene sulfide film.

Next, the coating film of the liquid crystalline film was
A heat treatment was performed in a heating atmosphere at a temperature of 5 ° C. for 5 minutes, and the resultant was cooled to room temperature to obtain a liquid crystalline polyester film exhibiting a golden specular reflection on a polyphenylene sulfide film.

When the transmission spectrum of the film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the selective reflection having a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm was observed. It was confirmed that the film was a cholesteric alignment film in which the cholesteric alignment shown was fixed. When the orientation state of the cholesteric alignment film was observed with a polarizing microscope and a transmission electron microscope of the cross section of the film, the helical axis orientation in the cholesteric phase was uniformly parallel to the film thickness direction, and the helical pitch was uniform in the film thickness direction. It was confirmed that the cholesteric orientation was formed at regular intervals.

The analysis methods of the obtained polyester are as follows. (1) Logarithmic viscosity of polymer Using a Ubbelohde viscometer, phenol / tetrachloroethane = 60/40 (weight ratio), a concentration of 0.5 g /
The measurement was performed at 100 ° C. and 30 ° C. (2) Glass transition point (Tg) Measured using a Du Pont 990 Thermal Analyzer. (3) Identification of Liquid Crystal Phase Observed using a BH2 polarizing microscope manufactured by Olympus Optical Co., Ltd.

Reference Examples 2 to 10 Liquid crystalline polyesters of various compositions were synthesized in the same manner as in Reference Example 1. Table 1 shows the results. Further, N-methyl-2-pyrrolidone solutions were prepared from various liquid crystalline polyesters in the same manner as in Reference Example 1,
By performing a heat treatment, a cholesteric liquid crystal film was obtained on the polyphenylene sulfide film used as the alignment substrate. Table 1 shows the selective reflection colors of the obtained film.

[0059]

[Table 1]

In Table 1, each symbol means the following compound. TPA: Terephthalic acid, MHQ: Methylhydroquinone, CT: Catechol, MBD: (R) -2-methyl-1,4-butanediol, BP
DA: 4,4'-biphenyldicarboxylic acid, CHQ: chlorohydroquinone, MHD: (R) -3-methyl-1,6-hexanediol, HB
A: hydroxybenzoic acid, NDCA: 2,6-naphthalenedicarboxylic acid, HQ: hydroquinone, CCT: 3-chlorocatechol, DMBD: (R) (R) -2,3-dimethyl-1,4-butanediol, t -BHQ: t-butylhydroquinone, PA: phthalic acid

Example 1 A 25 μm-thick polyethylene terephthalate (PET) film (T-type, manufactured by Toray Industries Inc.) having a polysiloxane hard coat layer on the surface was
Thickness 10μ made using acrylic photopolymer
An acrylic photocurable adhesive containing an ultraviolet absorber (Aronix UV-3630 (trade name) manufactured by Toagosei Co., Ltd.)
Through the laminate (diffraction film / adhesive layer / protective layer / P
ET film).

Next, the diffractive film layer of the laminate and Reference Example 1
Was adhered to the cholesteric liquid crystal film obtained in the above by using Aronix UV-3630, and the PPS film was peeled off (cholesteric liquid crystal film / adhesive layer / diffractive film layer / adhesive / protective layer / PET film). Next, an ethylene / vinyl acetate (EVA) hot melt adhesive was applied on the cholesteric liquid crystal film to form an adhesive layer.

The hot-melt adhesive layer of this laminate (hot-melt adhesive layer / cholesteric liquid crystal film / adhesive layer / diffraction film / adhesive layer / protective layer / PET film) was formed from a 1 mm thick polyvinyl chloride sheet. And bonded using a hot stamping machine. After cooling to room temperature, the PET film was peeled off to obtain an optical laminate comprising a polyvinyl chloride sheet / hot melt adhesive layer / cholesteric liquid crystal film / adhesive layer / diffraction film / protective layer. In the obtained optical laminate, a rainbow-colored effect unique to the diffraction pattern and a selective reflection unique to the cholesteric liquid crystal were clearly observed.

The accelerated light resistance test of the obtained optical laminate was carried out using a xenon arc lamp type light resistance tester, Santester CPS manufactured by Shimadzu Corporation, with a sample surface irradiance of 100 W / m ² (wavelength range of 300 to 700 nm) and a test time of 100. It was performed under the condition of time.

As a result of the test, when the reflection color of the optical laminate and the reflection color before the test were visually observed, no difference was observed in the reflection color, and even after the accelerated light resistance test, the rainbow caused by the diffraction pattern was observed. Color coloring characteristics and selective reflection characteristics specific to cholesteric liquid crystals were maintained. Next, the abrasion resistance test of the obtained optical laminate was performed using a friction tester FR-I manufactured by Suga Test Instruments Co., Ltd.
Performed using a mold. The test was performed according to the description of JIS L0849. However, the number of times of friction was 50 reciprocations in 50 seconds.

As a result of the test, no scratch was found on the protective layer, and the criterion for discoloration was 4-5. Further, when the reflection color of the cholesteric liquid crystal layer after the test and the reflection color of the liquid crystal layer before the test were visually observed, no difference was observed in the reflection color, and even after the abrasion resistance test, the rainbow caused by the diffraction pattern was observed. Color coloring characteristics and selective reflection characteristics characteristic of cholesteric liquid crystals were maintained.

On the other hand, the same operation was performed using PET without a hard coat layer to obtain an optical laminate. No difference was observed in the accelerated light resistance test, but after the abrasion resistance test, the surface became cloudy, and the criterion for discoloration was 2-3.

(Examples 2 to 10) Using the cholesteric liquid crystal films obtained in Reference Examples 2 to 10, Example 1
To obtain a laminate. In each of the obtained laminates, iridescent color due to the diffraction pattern and selective reflection peculiar to the cholesteric liquid crystal were clearly recognized. After the light resistance test and after the wear resistance test, as in the case before the test, iridescent color due to the diffraction pattern and selective reflection peculiar to the cholesteric liquid crystal were clearly recognized.

[0069]

The optical laminate of the present invention has unique optical characteristics such as diffracted light having a circular polarization property not found in conventional optical elements, and its application range is extremely wide as a diffraction function element. For example, it can be suitably used as an optical member such as an optical element, an optoelectronic element, a decoration material, and a forgery prevention element. In addition, the optical laminate of the present invention is excellent in various resistances including abrasion resistance without deteriorating its unique optical properties, and thus has an industrial value such as being applicable to various applications. Extremely high.

Claims (2)

[Claims] 1. A laminate comprising at least a support substrate / adhesive layer 1 / cholesteric liquid crystal layer / adhesive layer 2 / diffraction element layer / protective layer, wherein the protective layer has an ultraviolet absorbing property and a hard coat property. An optical laminate having the same. 2. The optical laminate according to claim 1, wherein the protective layer is formed from at least two layers of an ultraviolet absorbing layer and a hard coat layer.