JPH0875904A - Low reflection laminated film, polarizing plate and liquid crystal display device - Google Patents

Abstract

PURPOSE: To provide a low reflection laminated body film having excellent characteristics sufficiently durable for practical use which holding high productivity by forming a hard coating layer and an optical interference layer by wet film forming method, including respectively one or more layer of a specific high refractive index layer and low refractive index layer in the optical interference layer and arranging a specific polarizing plate. CONSTITUTION: The hard coating layer and the optical interference layer are formed by wet film forming method and the optical interference layer includes respectively one or more layer of the high refractive index layer and the low refractive index layer. One layer of the high refractive index layers uses a layers formed by applying a coating solution containing >=70% organic titanium compound and/or the oligomer expressed by formula 1 by solid matter weight ratio and drying by heating. For the low refractive index layers, one layer formed by applying a coating solution containing >=50% organic silicon compound expressed in terms of solid content and/or the carrier of the oligomer and/or the mixture expressed by formulas II-V and drying by heating is used. And for the polarizing plate, a surface protective plate composed of the low reflection laminated body film is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low reflection laminate film in which a hard coat layer and an optical interference layer are laminated in this order on at least one surface of a triacetyl cellulose film. The present invention also relates to a polarizing plate constituted by sandwiching a polarizer between two surface protection plates. Furthermore, the present invention relates to a liquid crystal display device in which a polarizing plate is arranged on the outermost surface of at least one side of a liquid crystal display element.

[0002]

2. Description of the Related Art A low reflection laminated film is provided, for example, on a surface protective plate for protecting the surface of a polarizer in a polarizing plate, or on the outermost surface of a liquid crystal display device, etc. It is used to reduce the reflection of light, increase the light transmittance of the device, and improve the visibility.

Many proposals have been made for such a low reflection laminate mainly in the field of optical lenses and the like, and the refractive index and the optical film thickness of the layer laminated as an optical interference layer have appropriate values. By doing so, it is possible to reduce the reflection of light at the interface between the laminate and the air.

The optical film thickness mentioned here is an amount defined by the product of the refractive index of the layer and the film thickness. For example, an optical interference layer in which a high-refractive index layer and a low-refractive index layer are sequentially laminated is provided on the substrate surface, and the optical film thicknesses of the high-refractive index layer and the low-refractive index layer are λ / 4 with respect to light of wavelength λ. Low-reflection laminates made by setting are well known.

The high-refractive index layer and the low-refractive index layer which are laminated as such an optical interference layer are generally manufactured by a dry method such as a sputtering method, a vacuum deposition method, an ion plating method or the like from the viewpoint of stable control of the refractive index. Membrane method is adopted.

In particular, with respect to a polarizing plate, a triacetyl cellulose film is generally used as a surface protective plate for protecting both sides of a polarizer. Then, a low reflection polarizing plate has been proposed in which a hard coat layer and an optical interference layer composed of several inorganic metal oxide film layers are laminated on a surface protective plate made of a triacetyl cellulose film.

Such a low-reflection polarizing plate can be used not only as an optical element but also as a liquid crystal display device as described above. That is, by disposing the polarizing plate on at least one surface of the liquid crystal display element, reflection of external light can be suppressed and display performance can be improved.

[0008]

Regarding the low reflection laminate using a plastic film or a plastic sheet as a substrate, a technique for producing a low reflection laminate sheet using a plastic sheet as a substrate using a dry film forming method is known. ing. Then, the low reflection laminate film using the triacetyl cellulose film as a substrate can obtain good low reflection characteristics when manufactured by a dry film forming method such as a sputtering method.

However, when the low reflection laminate film is manufactured by using the dry film forming method, it is not possible to obtain high productivity while securing a required level of film thickness uniformity for a wide film. difficult.

Therefore, a method other than the dry film forming method is required to obtain high productivity while ensuring the film thickness uniformity even for such a wide film. Then, for example, by using a wet film-forming method in which a liquid material is continuously applied using a roll coater or the like, and a layer is formed by heat drying, a required level of film thickness uniformity can be obtained even for a wide film. High productivity can be obtained while securing.

For forming a low reflection laminate using a wet film forming method, a low reflection is obtained by using a dipping method, a spin coating method, a spray coating method, a curtain coating method, a liquid removal coating method or the like on a glass or plastic substrate. Techniques for forming a laminate are known. However, as seen in these examples, the conventional method for forming a low-reflection laminate using a wet film-forming method requires a very long drying time in forming each layer, and thus a wide plastic film substrate is required. On the other hand, high productivity could not be obtained when the low reflection laminate was continuously formed.

Further, in order to form a low reflection laminate on a wide plastic film substrate by using a wet film forming method while ensuring high productivity, when the drying time in forming each layer is shortened, the substrate film Since the drying temperature of the coating liquid is limited by the heat resistance and mechanical properties of the, the high refractive index value in the high refractive index layer necessary for low reflectance and the hardness, abrasion resistance, etc. of each layer There is a problem in that it is difficult to obtain one that satisfies all mechanical properties.

Similarly, when a laminate is formed by a wet film-forming method using a triacetyl cellulose film as a substrate film, a drying temperature of a relatively low temperature limited by the characteristics of the film and a drying time of a relatively short period are used. Even at temperature, it is difficult to obtain a low-reflection laminate that satisfies all the high refractive index values required for low reflectance and high mechanical properties such as hardness and wear resistance of each layer. , Was a big issue.

Further, there is a strong demand for low cost production of a polarizing plate and a liquid crystal display device using such a low reflection laminate film. At that time, the manufacturing cost is greatly influenced by the productivity of the process for producing the low reflection laminate film. From these points as well, it has been a major problem to produce a low-reflection laminate film having high productivity and excellent characteristics.

The present invention solves the above problems by using a triacetyl cellulose film as a substrate film,
When forming a laminate by a wet film-forming method, even if the drying temperature is relatively low and the drying time is relatively short, the high refractive index value in the high refractive index layer necessary for lowering the reflectance, each layer, It is an object of the present invention to obtain a low reflection laminated film which satisfies all the mechanical properties such as hardness and abrasion resistance. Furthermore, by using such a low reflection laminated film,
The purpose is to obtain a polarizing plate and a liquid crystal display device having necessary characteristics with high productivity.

[0016]

The low reflection laminate film of the present invention is a low reflection laminate film in which a hard coat layer and an optical interference layer are laminated in this order on at least one surface of a triacetyl cellulose film. The hard coat layer and the optical interference layer are layers formed by a wet film forming method, and the optical interference layer includes at least one high refractive index layer and at least one low refractive index layer, and the high refractive index layer is at least one layer. But,
The following general formula (1) Ti (OR ¹ ) ₄ (1) (wherein R ¹ represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms)
The organic titanium compound monomer and / or oligomer thereof represented by the formula (1) is formed by applying a coating liquid containing 70% or more by weight of solid content and heat drying, and has a refractive index of 1.
65 to 2.25, and at least one layer of the low refractive index layer has the following general formulas (2) to (5) Si (OR ² ) ₄ (2) Si—X ₄ ^{··· (3) R 3 -Si (} OR 2) 3 ··· (4) R 3 -Si-X 3 ··· (5) ( where R ² is an aliphatic hydrocarbon group having 1 to 4 carbon atoms To R ³
Represents a methyl group or an ethyl group, and X represents a halogen atom), and contains 50% or more by weight of the solid content of the organic silicon compound monomer and / or its oligomer alone and / or a mixture thereof. The refractive index formed by applying the coating liquid and heat drying is 1.3.
It is characterized in that it is a layer within the range of 5 to 1.55.

The polarizing plate of the present invention is a polarizing plate constituted by sandwiching a polarizer between two surface protection plates, and the low reflection laminate film of the present invention is used as a polarizer as at least one surface protection plate. It is characterized in that a hard coat layer and an optical interference layer are arranged on the side not in contact with each other.

Furthermore, in the liquid crystal display device of the present invention, the polarizing plate of the present invention is provided on the outermost surface of at least one side of the liquid crystal display element, and the surface protective plate made of a low reflection laminate film is provided on the outermost surface side. It is characterized by having been placed.

That is, in the low reflection laminate film of the present invention, the high refractive index layer in the optical interference layer has a refractive index in the range of 1.65 to 2.25 from the viewpoint of optical design for obtaining low reflectivity. It is necessary to be. However, as mentioned above,
The heat drying temperature has an upper limit due to the characteristics of the substrate, triacetyl cellulose film. Therefore, the high refractive index layer is
It must have the required high refractive index and have good mechanical properties such as the hardness of the layer.

Therefore, at least one of the high refractive index layers is coated with a coating liquid containing the organotitanium compound monomer represented by the general formula (1) and / or its oligomer in an amount of 70% or more in terms of solid content weight ratio. It is necessary to use a layer formed by heat drying.

Here, when the coating liquid does not contain the organic titanium compound monomer represented by the general formula (1) and / or its oligomer in a solid content weight ratio of 70% or more, the high refractive index layer. It becomes difficult to stably obtain a refractive index of 1.65 or more. In many cases, the refractive index of the high refractive index layer shows a value of less than 1.65. It's hard to get.

Incidentally, as the layer having a refractive index value of 1.65 or more, in addition to the layer containing the organic titanium compound as a main component, for example, titanium oxide having a particle diameter of 10 nm or less,
There is a layer whose main component is metal fine particles such as tantalum oxide and cerium oxide. However, under the above-mentioned heat drying temperature conditions, it is difficult to obtain a layer that sufficiently satisfies mechanical properties such as hardness and adhesiveness while securing a high refractive index value.

Further, the layer containing an organic zirconium compound as a main component is relatively excellent in mechanical properties such as hardness and adhesiveness, but under the above heat drying temperature condition, a required high refractive index is obtained. Is difficult to obtain.

Among the organotitanium compounds represented by the general formula (1), more preferably tetra-i-propoxytitanium, tetra-n-butoxysilane and tetrakis (2
-Ethylhexoxy) titanium or the like is used. These organotitanium compounds may be used in the monomer state, may be used by slightly oligomerizing the monomer in advance, or may be used by mixing the monomer and the oligomer.

Further, in the low reflection laminate film of the present invention, the low refractive index layer in the optical interference layer has a refractive index in the range of 1.35 to 1.55 in terms of optical design for obtaining low reflectivity. It is necessary to be. Further, when the low refractive index layer is located on the outermost surface side in the low reflection laminate film of the present invention, it is necessary to have characteristics particularly excellent in mechanical characteristics such as hardness and abrasion resistance of the layer. However, as described above, the heat drying temperature has an upper limit value due to the characteristics of the triacetyl cellulose film that is the substrate. Therefore, a low refractive index layer having a required low refractive index and good mechanical properties such as hardness of the layer is required.

Therefore, at least one layer of the low refractive index layer is a single substance of an organosilicon compound monomer represented by any of the above-mentioned general formulas (2) to (5) and / or an oligomer thereof and / or a mixture thereof. It is necessary to use a layer formed by applying a coating liquid containing 50% or more by weight of solid content and heat drying.

When the coating liquid does not contain the organosilicon compound monomer represented by the general formulas (2) to (5) and / or the oligomer thereof in a solid content weight ratio of 50% or more, it is low. Mechanical properties such as hardness and abrasion resistance of the refractive index layer become insufficient, which is not preferable.

Of the organosilicon compounds represented by the general formulas (2) to (5), more preferred are tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane and ethyl. Triethoxysilane or the like is used. Even if these organosilicon compounds are used in the monomer state,
The monomers may be used in a state of being slightly oligomerized, or the monomers and oligomers may be mixed and used.

Further, the coating liquid may contain various curing agents for the purpose of accelerating the curing of the component organosilicon compound monomer or oligomer. Examples of these curing agents include:
Inorganic acids such as boric acid and phosphoric acid, oxalic acid, malonic acid, maleic acid, tartaric acid, citric acid, malic acid, glycolic acid,
Carboxylic acids such as hexafluoroglutaric acid are preferably used. These curing agents are preferably contained in a molar ratio of 0.05 to 3 with respect to the main component such as the organosilicon compound.

When the coating liquid is used for forming the low refractive index layer on the outermost surface of the low reflection laminate, various leveling agents, surfactants, low surface tension substances such as silicone oil are added to the coating liquid. This is preferably done. These components have the effect of enhancing the water repellency and oil repellency of the coating film, and by extension have the effect of enhancing the stain resistance of the surface of the low reflection laminate film. From the viewpoint of the balance between the above-mentioned effect expression and the mechanical strength of the coating film, these components are added in an amount of 0.01 relative to the solid content component of the coating liquid.
It is preferable to add it in the range of ˜1 wt%.

By the way, the following general formulas (6) to (6) are applied to a coating liquid containing an organic titanium compound as a main component for the high refractive index layer.
(7) R ⁴ -Si (OR ² ) ₃ (6) (However, R ² is an aliphatic hydrocarbon group having 1 to 4 carbon atoms,
R ⁴ is an organic group containing any of an epoxy group, an amino group, a methacryl group and a vinyl group, and R ³ is a methyl group or an ethyl group) and / or an organosilicon compound monomer The oligomer and / or the solid content can be added in the range of 30% by weight or less. This makes it possible to finely adjust the refractive index of the high refractive index layer, adjust the adhesion between the high refractive index layer and the hard coat layer, or adjust the adhesiveness between the high refractive index layer and the low refractive index layer.

Further, for the coating liquid containing an organosilicon compound as a main component for the low refractive index layer, the above-mentioned general formulas (6) to (6)
Organosilicon compound monomer and / or oligomer thereof represented by any of (7) and / or particle size 1
Silica fine particles of 0 nm or less can be added in the range of 50% or less by weight of solid content. Thereby, the adhesiveness between the low refractive index layer and the high refractive index layer can be adjusted.

Among the organosilicon compounds represented by the general formulas (6) and (7), more preferred are γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-
Aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane and the like are used.

For the coating liquid containing the organotitanium compound as the main component or the coating liquid containing the organosilicon compound as the main component, the solid component is a hydrocarbon-based component for the purpose of adjusting the viscosity and coatability. Those used after being dissolved in a suitable organic solvent such as an alcoholic solvent are preferably used.

As the optical interference layer that can be used in the low reflection laminate film of the present invention, in addition to the optical interference layer in which the high refractive index layer and the low refractive index layer are laminated one by one, for example, It is possible to use an optical interference layer in which a refractive index layer, a high refractive index layer, and a low refractive index layer are sequentially laminated one by one. In this case, the high-refractive index layer and the low-refractive index layer may be the high-refractive index layer and the low-refractive index layer described in the claims, respectively, and the medium-refractive index layer may be the hard coat layer and the high-refractive index layer. A layer having a refractive index positioned approximately in the middle of the refractive index layer may be used.

It is also possible to use, for example, an optical interference layer in which a first high refractive index layer, a first low refractive index layer, a second high refractive index layer and a second low refractive index are laminated in this order. The high refractive index layer may be used as the first high refractive index layer and the second high refractive index layer, and the low refractive index layer described in the claims may be used as the first low refractive index layer and the second low refractive index layer, respectively. In this case, the first high-refractive index layer and the second high-refractive index layer or the first low-refractive index layer and the second low-refractive index layer do not necessarily have to have the same refractive index and film thickness.

In the low reflection laminate film of the present invention, when an optical interference layer in which a high refractive index layer and a low refractive index layer are laminated one by one in this order is used as the optical interference layer,
Both layers have a refractive index within the above range, and in view of the optical design that human beings have high visibility, particularly low reflectance for light in the wavelength range of 500 to 600 nm, a high refractive index layer The optical thickness of the low refractive index layer is 10.0 to 18.0 n, respectively.
It is preferably in the range of m, and more preferably 13.
It is preferably in the range of 0 to 15.0 nm.

By the way, the triacetyl cellulose film used as the substrate of the present invention has a thickness of 50 to 500 μm.
The thing of a grade is used preferably. Further, it is preferable that at least one surface of the triacetyl cellulose film substrate is subjected to surface treatment such as saponification treatment before the step of forming the low reflection laminate of the present invention. This saponification treatment can be performed by a known method such as immersing the triacetyl cellulose film in a strong alkaline aqueous solution such as an aqueous sodium hydroxide solution.

Thus, for example, when the low reflection laminate film is attached to another article as in the case where the low reflection laminate film is attached to a polarizer and used as a surface protective plate of a polarizing plate, it is possible to obtain an adhesive property. It is possible to sufficiently secure the adhesive force or adhesive force between the agent, adhesive, etc. and the triacetyl cellulose film. Further, it is possible to sufficiently secure the adhesiveness between the triacetyl cellulose film and the hard coat layer.

The hard coat layer used in the present invention preferably has a layer refractive index in the range of 1.4 to 1.55 in terms of optical design for obtaining low reflectivity, and the layer thickness is 2. 0
It is preferably in the range of up to 10.0 μm. This is because if the film thickness is less than 2.0 μm, sufficient impact resistance cannot be obtained, and if the film thickness exceeds 10.0 μm, problems such as flexibility or economy in production occur.

As a hard coat layer having a refractive index within the above range and having sufficient impact resistance, a coating liquid containing a thermosetting type or ultraviolet curing type hard coating material is applied onto a film. Then, after being dried, it is cured by heat or ultraviolet rays to form a layer.

As the thermosetting hard coat material, the following general formulas (8) to (12) Si (OR ² ) ₄ (8) R ⁵ -Si (OR ² ) ₃ (9) are used. _{^{R 4 -Si (OR 2) 3}} ··· (11) (R ² is a hydrocarbon group having 1 to 4 carbon atoms, R ⁴ is an organic group containing any of an epoxy group, an amino group, a methacryl group and a vinyl group, and R ⁵ is a methyl group, an ethyl group or a phenyl group. In addition to a silicon-based material containing an organosilicon compound monomer and / or oligomer thereof and / or silica fine particles as shown in any one of (1) to (4), an organic polymer material such as an epoxy resin, a melamine resin, a urethane resin, an alkyd resin is used. I can do things. From the viewpoint of hardness and weather resistance of the hard coat layer, it is more preferable to use a thermosetting hard coat material containing the organosilicon material.

As the ultraviolet curable hard coat material,
Radical polymerization type UV curable resin material consisting of acrylic oligomers such as polyester acrylate, polyether acrylate, acrylic acrylate, epoxy acrylate and acrylic monomers, and radical polymerization initiators, epoxy compounds, vinyl ether compounds, cyclic ether compounds Use of a cationic polymerization type UV curable resin material comprising a compound, a monomer or oligomer such as a spiro compound and a photoreactive cationic polymerization initiator, or a mixed material of a radical polymerization type UV curable resin material and a cationic polymerization type UV curable resin material. You can

These hard coat materials may be used after being dissolved in an appropriate organic solvent such as a hydrocarbon type or alcohol type for the purpose of adjusting the viscosity and coating property of the coating liquid.

In the hard coat layer used in the present invention, for the purpose of adjusting the refractive index of the hard coat layer, a metal such as titanium oxide, zirconium oxide, tantalum oxide, antimony oxide or cerium oxide is added to the above-mentioned hard coat material. A layer formed by coating and curing a material to which fine particles and an organometallic compound such as an organotitanium compound, an organozirconium compound, an organoaluminum compound, and an organic tantalum compound and a chelate compound of a general metal are added and cured may be used.

In the low reflection laminate film of the present invention, the hard coat layer, the high refractive index layer and the low refractive index layer are laminated in this order on the film surface opposite to the film surface. It is possible to reduce the size of curl generated in the film. In this case, the hard coat layers laminated on both sides of the film are made of the same kind of hard coat material, and by further laminating the film thicknesses of the layers to be substantially equal to each other, the curl generated in the film can be made extremely small.

In the present invention, a primer layer may be provided between the triacetyl cellulose film as the substrate and the hard coat layer for the purpose of improving the adhesiveness at the interface between the two layers. The refractive index of the primer layer is 1.4 to
It is preferably in the range of 1.55 from the viewpoint of optical characteristics, and the film thickness is preferably in the range of 0.5 to 3.0 μm in order to satisfy both the primer property and the economical efficiency.

Further, in the low reflection laminate film of the present invention, the haze value defined by JIS is preferably 1.0% or less with respect to the transmitted light of the film, more preferably from the viewpoint of optical characteristics. Is preferably 0.5% or less.

By the way, the hard coat layer, the high refractive index layer, the low refractive index layer and the like to be laminated on the triacetyl cellulose film which is the substrate are, as described above, coated with the coating liquid, dried and then exposed to heat or ultraviolet rays. It is hardened and formed,
As a coating method of these coating liquids, a coating method using a known coating device such as a knife coater, a bar coater, a blade coater, a squeeze coater, a reverse roll coater, a gravure roll coater, a curtain coater, a spray coater, and a spin coater. An immersion method or the like is used. In the examples described below, a bar coater is used for coating the coating liquid for forming the hard coat layer, the high refractive index layer, and the low refractive index layer, which are laminated on the substrate triacetyl cellulose film, Similar results can be obtained by using other coating liquid coating equipment such as a roll coater.

When the coating liquid is applied to the substrate, the thickness of the layer and the coating uniformity can be controlled by adjusting the solid content concentration in the coating liquid and the amount of the coating liquid applied onto the substrate. Can be adjusted. In addition, a trace amount of a surfactant or the like may be added to the coating liquid to improve the coating property on the base film.

After the step of forming the low reflection laminate on the film is completed, the mechanical properties of the laminate can be obtained by aging the film at a temperature of about 60 ° C. for several days in a state where the film is rolled. It is possible to improve the durability and the like. Since such aging can be performed at a very low cost, it is very effective and is preferably performed.

After the step of forming the low reflection laminate on the film is completed, the surface of the film may be protected by attaching a removable protective film or the like to the surface of the film. Of course, in this case, when the low reflection laminate film is actually used, the protective film can be removed and used.

On the other hand, the polarizing plate of the present invention is characterized in that, of the two surface protective plates for protecting the polarizer, at least one of them is a surface protective plate made of the above-mentioned low reflective laminate film. It is a plate, and is manufactured by a method substantially similar to the manufacturing process of a general polarizing plate except that a low-reflection laminated film is used as a surface protection plate.

That is, in the production of the polarizing plate of the present invention, after the production process of the low reflection laminate film is completed, the film surface on the side where the low reflection laminate is not formed and the polarizer are treated with an appropriate pressure-sensitive adhesive or adhesive. The step of laminating with a polarizer is performed. As the pressure-sensitive adhesive or adhesive, those used in ordinary production of a polarizing plate can be used as they are, and a water-soluble pressure-sensitive adhesive or adhesive is preferably used.

In the polarizing plate of the present invention, the low reflection laminate film described above is used for only one of the two surface protective plates for protecting the polarizer to obtain low reflectance on only one side of the polarizing plate. Also, it is possible to obtain low reflectivity on both surfaces of the polarizing plate by using a low reflective laminate film for both, and it is selected as necessary.

After the production process of the low reflection laminate film is completed, a protective film or the like which can be easily detached is adhered to the surface of the film to protect the surface, and then a step of laminating with a polarizer may be carried out. Of course, in this case, when the polarizing plate is actually used, the protective film can be removed and used.

On the other hand, the liquid crystal display device of the present invention is a liquid crystal display device characterized in that the polarizing plate is arranged on the outermost surface of at least one of the liquid crystal display elements, and the polarizing plate is arranged on the outermost surface. Other than the above, it is manufactured by using a method substantially similar to the method of manufacturing a general liquid crystal display device.

That is, the liquid crystal display device of the present invention is manufactured by arranging the polarizing plate of the present invention on the outermost surface of at least one side of the liquid crystal display device, with the surface of the low reflection laminate film being the outermost surface. . Here, as the liquid crystal display element, for example, a twisted nematic type (TN type) liquid crystal cell, a super twisted nematic type (STN type) liquid crystal cell, or the like is known, and a polarized light is applied to the cell to modulate incident polarized light to perform a display function. The general liquid crystal display element can be used. These may be light transmissive liquid crystal display elements or light reflective liquid crystal display elements.

In general, these liquid crystal display elements include some or all of a substrate made of glass or plastic, a transparent electrode, an alignment film, a liquid crystal layer, a pixel driving element, a black matrix, a color filter and the like. It will be.

In the liquid crystal display device of the present invention, a retardation plate may be sandwiched between the liquid crystal display element and the polarizing plate. Here, the retardation plate refers to an optical element having a layer having a refractive index anisotropy in the layer,
For example, it is produced by a method of stretching a plastic film having optical isotropy to give birefringence to the film.

Usually, such a retardation film is sandwiched between a liquid crystal display element and a polarizing plate and used to improve the display quality of the liquid crystal display element. Particularly when a super twist nematic liquid crystal cell is used as a liquid crystal display element, it is generally essential to dispose a retardation plate as an optical compensation plate. Further, even when the twisted nematic liquid crystal cell is used as a liquid crystal display element, the retardation plate may be disposed for the purpose of improving display quality such as increasing the viewing angle at which a high display contrast can be obtained. These retardation plates may be used alone or as a laminate of two or more as necessary.

[0062]

Example 1 A primer layer was formed on one side of a saponified 80 μm thick triacetyl cellulose film substrate.
A hard coat layer, a high-refractive index layer, and a low-refractive index layer were sequentially laminated to produce a laminated film.

As the coating liquid for forming the primer layer, a primer liquid (trade name "PC manufactured by Shin-Etsu Chemical Co., Ltd."
-7A ") is used as it is without dilution, is coated on a substrate with a bar coater, and is heat-cured at 100 ° C. for 3 minutes,
A primer layer was formed. The film thickness of the primer layer thus formed was about 1.1 μm.

Next, as a coating liquid for forming the hard coat layer, a thermosetting type organic silicon type hard coat liquid (trade name "KP-85" manufactured by Shin-Etsu Chemical Co., Ltd.) was used as it is without dilution. Using a bar coater on the substrate on which the primer layer has been formed, heat-curing at 100 ° C. for 5 minutes,
Then, aging was performed at 60 ° C. for 24 hours to form a hard coat layer. The thickness of the hard coat layer thus formed was about 3.0 μm.

Next, as a coating liquid for forming the high refractive index layer, a mixed solvent of n-hexane and n-butanol was used.
A solution obtained by dissolving an oligomer of tetra-n-butoxytitanium and a monomer of γ-glycidoxypropyltrimethoxysilane in a weight ratio of 9: 1 was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, and heat-cured at 100 ° C. for 5 minutes to form a high refractive index layer. The high refractive index layer thus formed had a refractive index of about 1.70 and a film thickness of about 81 nm.

Next, as a coating liquid for forming the low refractive index layer, a tetraethoxysilane oligomer and a γ-glycidoxypropyltrimethoxysilane monomer were mixed in ethanol at a weight ratio of 4: 1. What was dissolved was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, heated and cured at 100 ° C. for 5 minutes, and then aged at 60 ° C. for 48 hours to form a low refractive index layer. The low refractive index layer thus formed had a refractive index of about 1.45 and a film thickness of about 95 nm.

The reflection interference color of the laminate film thus obtained was reddish purple, and the wavelength at which the reflectance was minimum was about 55.
At 0 nm, its minimum reflectance was about 0.1% and haze was 0.2%. Furthermore, the pencil hardness is H
The surface abrasion resistance was within 5 scratches / cm, and the adhesiveness was 100% in the cross-cut test residual rate. That is, it was extremely excellent in both low reflection characteristics and mechanical characteristics, and was sufficiently practical.

The refractive index and the film thickness of each layer were calculated by measuring the spectral reflectance. The low reflection optical characteristics of the produced low reflection laminate film were measured by using a spectrophotometer (U-3500 type manufactured by Hitachi, Ltd.) under the condition of regular reflection of 5 degrees. At that time, the surface of the substrate on which the low reflection laminate is not laminated is subjected to light absorption treatment using a black spray to prevent reflection of light on the back surface of the film, and then the reflectance of the low reflection laminate. Was measured. The haze is JIS standard K7105 for light with a wavelength of 550 nm.
The measurement was carried out according to. Surface hardness is JIS standard K54
In accordance with No. 00, the pencil hardness under a load of 1 kg was evaluated.
Surface abrasion resistance is evaluated by the number of scratches per centimeter width in the reciprocating direction of the steel wool after 10 reciprocations on the surface of the laminated film by applying a load of 0.1 kg per square centimeter to # 0000 steel wool. did. Further, the adhesiveness was evaluated by a cross-cut test (cross-cut tape method) in accordance with JIS K5400, and a residual rate of squares where peeling did not occur.

[0069]

Example 2 A laminate film was prepared and evaluated under the same conditions as in Example 1 except that the low refractive index layer was changed. That is, in Example 2, as a coating liquid for forming the low refractive index layer, an oligomer of tetraethoxysilane and silica fine particles having a particle size of 10 nm or less were mixed in ethanol in a weight ratio of 2:
What was melt | dissolved in the ratio of 1 was used. This coating liquid is applied on the substrate on which the hard coat layer is formed by a bar coater,
Heat cure at 100 ° C for 5 minutes and then at 60 ° C for 48 minutes.
A low refractive index layer was formed by performing time aging. The formed low refractive index layer has a refractive index of about 1.47 and a film thickness of about 94n.
It was m.

The reflection interference color of the laminate film thus obtained was reddish purple, and the wavelength at which the reflectance was minimum was about 55.
The minimum reflectance at 0 nm was about 0.2%, and the haze was 0.2%. Further, the pencil hardness is H, abrasion scratches are within 5 pieces / cm, and the residual rate in the cross-cut test is 100.
%, Which was extremely excellent in both low reflection characteristics and mechanical characteristics, and was sufficiently practical.

[0071]

Example 3 A laminate film was prepared and evaluated under the same conditions as in Example 1 except that the low refractive index layer was changed. That is, in Example 3, as a coating liquid for forming the low refractive index layer, an oligomer of methyltriethoxysilane and a monomer of γ-glycidoxypropyltrimethoxysilane were mixed in ethanol in a weight ratio of 9: 1. What was dissolved at a ratio was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, heated and cured at 100 ° C. for 5 minutes, and then aged at 60 ° C. for 48 hours to form a low refractive index layer. The low refractive index layer thus formed had a refractive index of about 1.47 and a film thickness of about 94 nm.

The reflection interference color of the laminate film thus obtained is reddish purple, and the wavelength at which the reflectance is minimum is about 55.
At 0 nm, the minimum reflectance was about 0.2% and the haze was 0.2%. Furthermore, the pencil hardness is H, the number of abrasion scratches is 5 / cm or less, the cross-cut test residual rate is 100%, and the low reflection characteristics and mechanical characteristics are very excellent.
It was sufficiently practical.

[0073]

Example 4 A laminate film was prepared and evaluated under the same conditions as in Example 1 except that the low refractive index layer was changed. That is, in Example 4, as a coating liquid for forming the low refractive index layer, each monomer of tetramethoxysilane, methyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and phosphoric acid were added to isopropyl alcohol. Was dissolved in a weight ratio of 1: 2: 2: 1.
This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, heated and cured at 100 ° C. for 5 minutes, and then aged at 60 ° C. for 48 hours to form a low refractive index layer. The low refractive index layer thus formed had a refractive index of about 1.47 and a film thickness of about 94 nm.

The reflection interference color of the laminate film thus obtained is reddish purple, and the wavelength at which the reflectance is minimum is about 55.
At 0 nm, the minimum reflectance was about 0.2% and the haze was 0.2%. Furthermore, the pencil hardness is H, the abrasion scratches are within 2 / cm, the cross-cut test residual rate is 100%, and both the low reflection characteristics and the mechanical characteristics are very excellent.
It was sufficiently practical.

[0075]

[Example 5] In Example 5, a fluorosurfactant (trade name "Florard FC430" manufactured by Sumitomo 3M Limited) was added to the coating solution used in Example 4 in a solid content weight ratio of 0.1%. A low reflection laminate film was prepared in the same manner as in Example 4 except for the above.

The low reflection laminate film thus obtained had high water repellency and oil repellency and had a surface excellent in stain resistance against stains such as fingerprints. Further, low reflection characteristics, mechanical characteristics and the like were the same as in the case where no addition was made (Example 4), and no deterioration was observed.

[0077]

Example 6 In Example 6, silicon oil (Toray Dow Corning Silicon Co., Ltd., trade name “SH28PA”) was added to the coating liquid used in Example 4 in an amount of 0.1% by weight of solid content. A low reflection laminate film was prepared in the same manner as in Example 4.

The low reflection laminate film thus obtained had high water repellency and oil repellency, and had a surface excellent in stain resistance against stains such as fingerprints. Further, low reflection characteristics, mechanical characteristics and the like were the same as in the case where no addition was made (Example 4), and no deterioration was observed.

[0079]

Comparative Example 1 A laminate film was prepared and evaluated under the same conditions as in Example 1 except that the low refractive index layer was changed. That is, in Comparative Example 1, as a coating liquid for forming the low refractive index layer, silica fine particles having a particle size of 10 nm or less and a monomer of γ-glycidoxypropyltrimethoxysilane were mixed in a weight ratio of 2: 1 in ethanol. What was dissolved at a ratio was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, heated and cured at 100 ° C. for 5 minutes, and then aged at 60 ° C. for 48 hours to form a low refractive index layer. The low refractive index layer thus formed had a refractive index of about 1.50 and a film thickness of about 92 nm.

The reflection interference color of the laminate film thus obtained is reddish purple, and the wavelength at which the reflectance is minimum is about 55.
At 0 nm, the minimum reflectance was about 0.4% and the haze was 0.3%. Furthermore, the pencil hardness is H, and the residual rate in the cross-cut test is 100%, but there are 50 scratches / wear scratches /
Since it was cm or more, and particularly the abrasion resistance was poor, it was not practically usable.

[0081]

Comparative Example 2 Except that the high refractive index layer and the low refractive index layer were changed,
A laminate film was prepared and evaluated under the same conditions as in Example 1. That is, in Comparative Example 2, as a coating liquid for forming the high refractive index layer, titanium oxide fine particles having a particle diameter of 10 nm or less and a monomer of γ-aminopropyltrimethoxysilane were mixed in ethanol in a weight ratio of 4: 1. The one dissolved in was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, and heat-cured at 100 ° C. for 5 minutes to form a high refractive index layer. The high refractive index layer thus formed has a refractive index of about 1.70 and a film thickness of about 81 nm.
Met.

Next, as a coating liquid for forming the low refractive index layer, an oligomer of tetraethoxysilane and a monomer of γ-glycidoxypropyltrimethoxysilane were mixed in ethanol at a weight ratio of 4: 1. What was dissolved was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, heated and cured at 100 ° C. for 5 minutes, and then aged at 60 ° C. for 48 hours to form a low refractive index layer. The low refractive index layer thus formed had a refractive index of about 1.45 and a film thickness of about 95 nm.

The reflection interference color of the laminate film thus obtained was reddish purple, and the wavelength at which the reflectance was minimum was about 55.
At 0 nm, the minimum reflectance was about 0.1% and the haze was 0.3%. Further, the pencil hardness is H, but abrasion scratches are 50 or more / cm, and the residual rate in the cross-cut test is 70%.
Although it was excellent in low reflection characteristics, it was not practically usable because it was inferior in mechanical characteristics such as abrasion resistance and adhesion.

[0084]

[Comparative Example 3] Except that the high refractive index layer and the low refractive index layer were changed,
A laminate film was prepared and evaluated under the same conditions as in Example 1. That is, in Comparative Example 3, as a coating liquid for forming the high refractive index layer, an oligomer of tetra-n-butoxyzirconium and γ-glycidoxypropyltriene was added in a mixed solvent of n-hexane and n-butanol. A methoxysilane monomer dissolved at a weight ratio of 9: 1 was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, and heat-cured at 100 ° C. for 5 minutes to form a high refractive index layer. The high refractive index layer thus formed had a refractive index of about 1.60 and a film thickness of about 86 nm.

Next, as a coating liquid for forming the low refractive index layer, an oligomer of tetraethoxysilane and a monomer of γ-glycidoxypropyltrimethoxysilane were mixed in ethanol at a weight ratio of 4: 1. What was dissolved was used. This coating liquid was applied by a bar coater onto the substrate on which the hard coat layer was formed, heated and cured at 100 ° C. for 5 minutes, and then aged at 60 ° C. for 48 hours to form a low refractive index layer. The low refractive index layer thus formed had a refractive index of about 1.45 and a film thickness of about 95 nm.

The reflection interference color of the thus-obtained low reflection laminate film was reddish purple, the wavelength at which the reflectance was minimum was about 550 nm, and the minimum reflectance was about 0.8%.
The haze was 0.2%. Furthermore, the pencil hardness is H,
10 scratches / cm or less for abrasion damage, 9 remaining rate in cross cut test
0%, which is relatively excellent in mechanical properties,
Since it was inferior in low reflection property, it was not practically usable.

[0087]

Example 7 A polarizing plate was produced using the laminate film produced under the same conditions as in Example 1. The polarizer has 99.
A polyvinyl alcohol-based polarizer having iodine as a polarizing element and having a polarization degree of 9% or more was used. Then, on one surface of this polarizer, a surface protective plate made of a laminate film produced under the same conditions as in Example 1 was adhered. Further, a surface protective plate made of a normal triacetyl cellulose film was adhered to the other surface.

Regarding the thus prepared polarizing plate, the transmittance of the polarizing plate alone at a wavelength of 550 nm was 4
It was 5.2%. Furthermore, the pencil hardness of this polarizing plate is H, abrasion scratches are within 5 lines / cm, and the residual rate in the cross-cut test is 100%, and the transmittance and mechanical properties are extremely excellent, and it is sufficiently practical. It was profitable.

[0089]

Comparative Example 4 A polarizing plate was prepared and evaluated under the same conditions as in Example 7, except that the surface protective plate sandwiching the polarizer in Example 7 was changed to a normal triacetyl cellulose film on both sides. As a result, the wavelength of the polarizing plate alone is 550 nm.
The transmittance was 43.5%, which was inferior to that in Example 7.

[0090]

Example 8 A liquid crystal display device was produced using the polarizing plate produced under the same conditions as in Example 7. For that purpose, first 2
Aperture ratio 10 driven by a single transparent electrode of 10 cm square
A simple 0% twisted nematic liquid crystal cell was prepared. Then, the polarizing plate prepared under the same conditions as in Example 7 was bonded to one surface of the cell. And on the other side of the cell,
A polarizing plate manufactured under the same conditions as in Comparative Example 4 and a reflecting plate made of aluminum were bonded in this order. Thus, a low reflection liquid crystal display device having a reflection type display function was manufactured.

In the liquid crystal display device thus obtained,
The reflectance at the wavelength of 550 nm in the ON state is about 30.0.
%, And the reflectance at the wavelength of 550 nm in the OFF state was about 1.2%. And from this wavelength 550nm
The display contrast in Example 2 was about 25.0, showing excellent characteristics.

[0092]

Comparative Example 5 A polarizing plate was prepared and evaluated under the same conditions as in Example 8 except that the polarizing plate adhered to the cell in Example 8 was replaced by the polarizing plate prepared under the same conditions as in Comparative Example 4. did. As a result, the reflectance at the wavelength of 550 nm in the ON state was about 32.7%, and the reflectance at the wavelength of 550 nm in the OFF state was about 5.0%. The display contrast at a wavelength of 550 nm was calculated from this to be about 6.5, which was inferior to that of Example 8.

[0093]

According to the present invention, even when a low reflective laminate is formed by a wet film forming method using a triacetyl cellulose film as a substrate film, a relatively low drying temperature limited by the characteristics of the film, Even with a relatively short drying time, a low-reflection laminate with excellent low-reflection properties and mechanical properties such as surface hardness and abrasion resistance was obtained, so that high productivity can be maintained and practical use can be sufficiently endured. It was possible to obtain a low reflection laminate film having excellent characteristics. Furthermore, by using such a low-reflection laminated film, a polarizing plate and a liquid crystal display device having necessary characteristics can be obtained with high productivity.

Claims (5)

[Claims] 1. A low reflection laminate film in which a hard coat layer and an optical interference layer are laminated in this order on at least one surface of a triacetyl cellulose film, wherein the hard coat layer and the optical interference layer are formed by a wet film forming method. The optical interference layer includes at least one high refractive index layer and at least one low refractive index layer, and at least one high refractive index layer has the following general formula (1) Ti (OR ¹ ) ₄ (1) (wherein R ¹ represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms)
The organic titanium compound monomer and / or oligomer thereof represented by the formula (1) is formed by applying a coating liquid containing 70% or more by weight of solid content and heat drying, and has a refractive index of 1.
65 to 2.25, and at least one layer of the low refractive index layer has the following general formulas (2) to (5) Si (OR ² ) ₄ (2) Si—X ₄ ^{··· (3) R 3 -Si (} OR 2) 3 ··· (4) R 3 -Si-X 3 ··· (5) ( where R ² is an aliphatic hydrocarbon group having 1 to 4 carbon atoms To R ³
Represents a methyl group or an ethyl group, and X represents a halogen atom), and contains an organic silicon compound monomer and / or oligomer thereof alone or / and a mixture thereof in an amount of 50% by weight or more in terms of solid content. The refractive index formed by applying the coating liquid and heat drying is 1.3.
A low-reflection laminate film, which is a layer within a range of 5 to 1.55. 2. The low reflection laminate film according to claim 1, wherein a primer layer is provided between the triacetyl cellulose film and the hard coat layer. 3. The low reflection laminate film according to claim 1, wherein at least one surface of the triacetyl cellulose film is previously saponified. 4. A polarizing plate constituted by sandwiching a polarizer between two surface protection plates, wherein the low reflection laminate film according to claim 1 is used as at least one surface protection plate. A polarizing plate comprising a hard coat layer and an optical interference layer disposed on the side not in contact with the child. 5. A liquid crystal characterized in that the polarizing plate according to claim 4 is disposed on the outermost surface of at least one side of a liquid crystal display element with a surface protective plate made of a low reflection laminate film as the outermost surface side. Display device.