JP2000028813A - Optical filter and its production as well as front surface plate for plasma display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter which is excellent in an adhesion property of a transparent resin substrate and a film, makes it possible to obtain sufficient durability, is excellent in scratching resistance, has execute surface quality by suppressing the occurrence of cracking on the surface, may be easily produced with a decreased number of production stages and is excellent in productivity and a process for producing the same. SOLUTION: A polycarbonate film 3 is used as the film in the constitution obtd. by adhering and integrating the transparent resin plate 2 and the film via an adhesive layer and the integration by adhering is executed by hot pressing. Since the plate and the film are adhered by hot pressing, the excellent adhesion property of the transparent resin substrate and the film and the sufficient tight adhesion durability are obtd. Since the polycarbonate film 3 is used as the film, the occurrence of crack in the surface coating layer after hot pressing may be suppressed even with the constitution provided with the surface coating layer, such as light control coating layer or hard-coating layer, for the purpose of preventing reflection and dazzle on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter which is used by being disposed on the front of a display panel of, for example, a computer or a television, or a display panel of a plasma display, a method of manufacturing the same, and a plasma display using the optical filter. It relates to the front plate.

[0002] In this specification, the term "electromagnetic wave" means an electromagnetic wave (mainly a radio wave or the like) having a wavelength longer than that of near infrared rays, and is clearly distinguished from the term "near infrared rays". Shall be.

[0003]

2. Description of the Related Art A large amount of harmful electromagnetic waves are generated from various computer displays in office automation equipment, factory automation equipment, etc., displays such as game consoles and televisions, and these electromagnetic waves have recently affected the health of operators. The problem has been pointed out, and interference with other devices due to electromagnetic waves has become a problem.

Recently, a plasma display has been attracting attention as a large-sized display device. This plasma display has a front surface compared to a conventional display such as a cold cathode ray tube (CRT) or a liquid crystal display panel (LCD). From the strong intensity of electromagnetic waves leaked from
There is a strong demand for providing an electromagnetic wave shielding function having better shielding performance. Furthermore, in this plasma display, near-infrared rays derived from the emission of the inert gas in the cell are emitted from the front surface, and the wavelength of this near-infrared ray is close to the operating wavelength of the remote control device of various home appliances. , As it may cause malfunction,
There is also a demand for providing a function of sufficiently shielding this near infrared ray.

[0005] On the other hand, it is required that such displays have a sufficient anti-reflection function and anti-glare function from the viewpoint of improving image quality and visibility.

As described above, various kinds of functions are applied to the display panel according to the use and form used, that is, the electromagnetic wave shielding function, the near infrared ray shielding function, the antireflection function, the antiglare function, and the like. In response to such a requirement, a front plate called an optical filter which is appropriately provided with some of these various functions is conventionally provided in front of the display panel. Many arrangement methods are adopted.

As such an optical filter, a filter in which an antireflection layer or an antiglare layer is directly coated on a transparent resin substrate having an electromagnetic wave shielding function and / or an infrared ray shielding function, or a transparent resin substrate having a similar function There is known a filter in which a surface-treated film having a surface coated with an antireflection layer and an antiglare layer is bonded and integrated with a pressure-sensitive adhesive.

[0008]

However, the above prior art has the following problems. That is, in the former optical filter directly coated on the substrate, when the area thereof becomes large, it is necessary to increase the size of the equipment for directly coating at the time of manufacturing, but this increases the equipment space. Not only that, equipment costs also increased, and restrictions on equipment were great. This tendency is particularly large in a plasma display having a large area.

On the other hand, in the latter optical filter in which a surface-treated film is bonded and integrated with an adhesive, an optical filter having various desired functions can be obtained simply by bonding a surface-treated film provided with various functions with an adhesive. Because it is obtained, it is easy to manufacture. However, when the optical filter is provided with a plurality of the various functions as described above, it is necessary to adhere a plurality of films having a desired function to one or both sides of the transparent resin substrate,
In this case, since the number of film bonding steps increases in accordance with the number of films to be bonded, there is a problem that productivity is remarkably reduced and manufacturing cost is also increased.

The present invention has been made in view of such a technical background, and has excellent adhesiveness between a transparent resin substrate and a film, sufficient durability, excellent scratch resistance, and excellent surface resistance. Provided is an optical filter which suppresses the occurrence of cracks, has excellent surface quality, has a small number of manufacturing steps, can be easily manufactured, and is excellent in productivity, a method for manufacturing the same, and a front panel for a plasma display using the optical filter. The purpose is to do.

[0011]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies and, as a result, selected a polycarbonate resin as a material for a surface treatment film and bonded the polycarbonate film to a transparent resin plate. The present invention has been completed by finding that the desired optical filter can be obtained by superimposing and bonding together by a hot press through a layer made of an agent.

That is, an optical filter according to the present invention is an optical filter in which a transparent resin plate and a film are bonded and integrated via an adhesive layer, wherein the film is a polycarbonate film, and the transparent resin plate and the film are bonded via the adhesive layer. Is characterized by being integrated by hot pressing.

[0013] In addition to the fact that the adhesive forming the adhesive layer is sufficiently softened by the heating at the time of the hot pressing, the bonding is started, and the adhesive is integrated under the pressure at the time of the hot pressing. From the excellent adhesion between the transparent resin substrate and the film,
Sufficient adhesion durability is secured.

Further, since a polycarbonate film is used as the film, even if a surface coat layer such as a light control coat layer or a hard coat layer for antireflection and antiglare is provided on the surface of the polycarbonate film, The generation of cracks and cracks in the surface coat layer after hot pressing is suppressed, and the surface quality is excellent.

[0015] Further, when the electromagnetic wave shielding function is provided, the electromagnetic wave is effectively prevented from reaching the operator. In particular, it is preferable that a conductive net is laminated and integrated between the transparent resin plate and the polycarbonate film to have an electromagnetic wave shielding function. By arranging the conductive mesh at such a position, the occurrence of warpage of the optical filter is effectively prevented.

[0016] Further, when the device has a near-infrared shielding function, it is possible to prevent remote control devices of various home electric appliances from malfunctioning. Above all, the total light transmittance of the transparent resin plate in the visible light region is 60% or more and the wavelength is 800
When the transmittance of light having a wavelength of up to 1000 nm is 30% or less, sufficient transparency (transparency) as an optical filter is ensured, and malfunction of the remote control device is reliably prevented.

Further, a hard coat layer is preferably provided on the surface side of the polycarbonate film, whereby the scratch resistance of the optical filter is further improved.

When an anti-reflection function or an anti-glare function is provided, the surface of the polycarbonate film is
It is preferable that one or more light control coat layers having one or two kinds of functions selected from the group consisting of an antireflection function and an antiglare function are provided. By arranging the optical filter on the front side (operator side) of the optical filter, the above function can be exhibited more effectively.

Further, it is desirable that at least one surface of the filter is formed with irregularities, thereby preventing the generation of Newton rings. In particular, when the unevenness is transferred from a transfer mold, a desired uneven shape can be imparted, and the performance of preventing Newton's ring from occurring can be further improved.

A method of manufacturing an optical filter according to the present invention is characterized in that a transparent resin plate and a polycarbonate film are bonded together by performing a hot press in a state where the transparent resin plate and the polycarbonate film are overlaid via a layer made of an adhesive. is there. Due to the heating at the time of hot pressing, in addition to starting the bonding in a state where the adhesive constituting the adhesive layer is sufficiently softened, the bonding is integrated by pressing in a pressurized state. Excellent adhesion to the film, and therefore sufficient adhesion durability. Further, since a polycarbonate film is used in this manner, even if a surface coat layer such as a light control coat layer or a hard coat layer for anti-reflection and anti-glare is provided on the surface of the film, the surface coat after hot pressing can be obtained. Generation of cracks and cracks in the layer is suppressed, and a layer having excellent surface quality is provided. Further, even when the light control coat layer or the hard coat layer as described above is provided to form a multi-layer structure, it can be bonded and integrated by a single hot press, so that it is excellent in productivity and, consequently, at low cost. It can be manufactured economically.

In the above manufacturing method, the adhesive is preferably a thermosetting resin or a hot-melt resin. In the case of a thermosetting resin, the pressure is applied during thermosetting, so that the adhesive strength is further improved. In the case of a hot melt resin, the pressure is applied in a more sufficiently softened state, so that the adhesive strength is further improved.

Further, even if the optical filter of the present invention is large, it is not necessary to particularly increase the size of the equipment for producing the filter, and it can be manufactured simply, easily and with high efficiency. It can be used particularly preferably as a front panel for a plasma display that is large.

[0023]

FIG. 1 is a sectional view of an optical filter according to an embodiment of the present invention. The optical filter (1) of the present invention is one in which a transparent resin plate (2) and a polycarbonate film (3) are bonded and integrated by a hot press via an adhesive layer (4).

In the present invention, the transparent resin plate (2) may be in the form of a film, a sheet, or a plate, and its size (area) is appropriately determined according to the screen size of the target display. Should be set to. The thickness of the transparent resin plate (2) is not particularly limited, but is usually in the range of 0.01 to 10 mm.

The resin constituting the transparent resin plate (2) is usually a synthetic resin, and is not particularly limited. For example, acrylic resin, polycarbonate, polystyrene,
Methyl methacrylate-styrene copolymer and the like can be mentioned. Above all, it is preferable to use an acrylic resin because it can be easily formed into a desired size.

In the present invention, it is necessary to use a polycarbonate film (3) as a film to be bonded and integrated with the transparent resin plate (2). By selecting this polycarbonate, a surface coat layer such as a light control coat layer (7) or a hard coat layer (6) for anti-reflection and anti-glare is provided on the surface of the polycarbonate film (3). This is also because the occurrence of cracks and cracks in the surface coat layer during hot pressing is suppressed. For example, when an acrylic film was used as the above film, cracks and cracks were easily generated in the surface coat layer laminated thereon by hot pressing. Particularly in the case of a configuration in which an antireflection film or a transparent conductive film is laminated as described later, cracks are remarkable. The thickness of the polycarbonate film (3) is not particularly limited, but may be 30 to
It is preferably 250 μm. If the thickness is less than 30 μm, it is not preferable because handling becomes difficult. On the other hand, if it exceeds 250 μm, the adhesiveness decreases, which is not preferred.

On the other hand, as an adhesive constituting an adhesive layer (4) for adhering the transparent resin plate (2) and the polycarbonate film (3), the two (2) and (3) are favorably adhered by hot pressing. There is no particular limitation as long as it can be obtained, but a thermosetting resin or a hot melt resin (having a softening point enough to melt at a set pressing temperature) is preferable. Of course, both resins may be used in combination. In the case of a thermosetting resin, the adhesive strength is further improved due to the pressurized state at the time of thermosetting, and in the case of a hot melt resin, the adhesive strength is increased since the pressure is more sufficiently softened. It is further improved.

Examples of the thermosetting resin include urethane resins, acrylic resins and epoxy resins, and examples of hot melt resins include olefin resins.

The adhesive layer (4) may be coated beforehand on the surface of the polycarbonate film (3) before hot pressing, or may be formed into a film-like shape with a transparent resin plate (2) and a polycarbonate film (3). (3) It is good also as what is hot-pressed in between. The thickness of the adhesive layer (4) is not particularly limited, but is 20 to 200 μm.
m is preferable. If the thickness is less than 20 μm, it is not preferable because sufficient adhesive strength cannot be secured.
If it exceeds μm, the adhesive layer (4) tends to seep out from the end face of the optical filter during hot pressing, which is not preferable.

On the surface side of the polycarbonate film (3), from the viewpoint of further improving the scratch resistance,
It is preferable that the hard coat layer (6) is laminated.
As a method of forming such a hard coat layer (6), a method of applying a coating agent containing a polyfunctional monomer as a main component and then curing the coating agent with ultraviolet light or the like,
Alternatively, a method of applying a silicone-based crosslinkable resin, a melamine-based crosslinkable resin, an epoxy-based crosslinkable resin, and the like, followed by curing with heat, ultraviolet light, or the like may be used, but the method is not particularly limited to these methods. Examples of the coating method include a spin coating method, a dipping method, a roll coating method, a gravure coating method, and a curtain flow method. The coating agent used is usually diluted with various solvents. In this case, the solvent evaporates until the curing of the resin is completed.

Examples of the polyfunctional monomer include a polymerizable compound having at least two (meth) acryloyloxy groups in a molecule.

Specific examples of such a polymerizable compound include an ester compound of a polyhydric alcohol and (meth) acrylic acid, or a reaction of a compound having an isocyanate group at a terminal with a (meth) acrylic acid derivative having a hydroxyl group. The resulting urethane-modified (meth) acrylic oligomer may, for example, be mentioned.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, propanediol, butanediol, pentanediol, hexanediol, neopentyl glycol, 2-ethyl-1,3-hexane. Diol, 2,2 '
Dihydric alcohols such as thiodiethanol and 1,4-cyclohexanedimethanol; trihydric or higher alcohols such as trimethylolpropane, pentaglycerol, glycerol, pentaerythritol, diglycerol and dipentaglycerol.

To the ester compound of the polyhydric alcohol and the (meth) acrylic acid, a small amount of a polyunsaturated carboxylic acid is further added in order to impart flexibility to the obtained cured film and to prevent cracking. It may be a mixed ester. Such polyunsaturated carboxylic acids include, for example, succinic acid, tetrahydrophthalic acid, phthalic acid, maleic acid, fumaric acid, itaconic acid and the like.

The urethane-modified (meth) acrylic oligomer is obtained by reacting a polyisocyanate such as hexamethylene diisocyanate and isophorone diisocyanate with an oligomer having a hydroxyl group such as polycaprolactone diol and polytetramethylene diol. In addition to a polyurethane having an isocyanate terminal, a (meth) acrylic acid derivative having a hydroxyl group (for example, 2-hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate)
Are preferably obtained by reacting (urethane).

The thickness of the hard coat layer (6) is not particularly limited, but is preferably 1 to 20 μm. When the thickness is less than 1 μm, not only the effect of the hard coat treatment is not sufficiently obtained, but also interference fringes due to the hard coat layer are likely to be generated.
If it exceeds 0 μm, cracks are likely to occur in the hard coat layer (6), which is not preferable.

In order to improve the adhesion between the polycarbonate film (3) and the hard coat layer (6),
An adhesive layer may be provided between both (3) and (6). Known adhesive layers can be used.

The optical filter (1) of the present invention may be provided with various functions according to the characteristics, form, use environment and the like of the display to be mounted. Such functions include, for example, an electromagnetic wave shielding function, a near-infrared shielding function, an antireflection function, an antiglare function, and the like.

Examples of the method of imparting the electromagnetic wave shielding function include a method of laminating a transparent conductive film on at least one surface of the transparent resin plate (2) and a method of forming a conductive mesh on at least one surface of the transparent resin plate (2). A method of laminating an electromagnetic wave shielding layer (8), such as a method of laminating a body, or a method of embedding a conductive net in a transparent resin plate (2) and laminating and integrating them. It is not limited to these methods, and any means may be used as long as it can impart conductivity. Further, the place where the conductivity is given does not necessarily need to be on the side of the transparent resin plate (2), but may be on the side of the polycarbonate film (3). For example, a transparent conductive film may be laminated on the surface of the polycarbonate film (3).

As the method of laminating the transparent conductive film, for example, a method of forming one or more transparent conductive layers made of metal and / or metal oxide by means such as vacuum deposition or sputtering, metal fine particles and / or Examples include a method of coating a resin in which conductive fine particles such as metal oxide fine particles are dispersed.

Examples of the metal include gold, silver, platinum,
Palladium, copper, titanium, chromium, molybdenum, nickel, zirconium and the like can be mentioned. Among them, silver is preferable because a conductive layer having more excellent conductivity can be easily obtained. When this metal layer is provided as a conductive layer, it is preferable to form a multilayer film with a dielectric layer in order to prevent reflection of the metal layer. Examples of such a dielectric layer include layers made of various metal oxides, metal nitrides, metal sulfides, and the like.

Examples of the metal oxide include silicon oxide, titanium oxide, tantalum oxide, tin oxide, indium oxide, zirconium oxide, zinc oxide, and a composite oxide of indium oxide and tin oxide.

One of these metals and metal oxides may be used alone, or two or more thereof may be used in combination.

As the method of laminating the conductive mesh, for example, a method of laminating a metal mesh or a resin woven cloth having a metal layer coated on its surface (hereinafter referred to as “conductive mesh”). Or a method of printing a grid pattern on the surface of a transparent resin plate using conductive ink, etc., or forming a grid pattern by means such as etching after providing a metal thin film such as copper or aluminum on the surface of the transparent resin plate And the like.

As the conductive mesh body, for example,
A mesh made of copper fiber, a mesh made of stainless steel fiber, gold, silver,
One coated with a metal layer such as copper, and the like.

The diameter of the fiber constituting the mesh of the conductive mesh is usually 10 to 60 μm, and the mesh size is preferably in the range of 40 to 200 mesh. The mesh size is a size specified by a Tyler standard sieve. Such a conductive mesh body may be colored black with a conductive paint, plating, or the like on its surface to prevent metallic luster.

It is preferable that the conductive net is laminated and integrated between the transparent resin plate (2) and the polycarbonate film (3). By arranging in such a position, the warpage of the optical filter (1) can be reduced.
Specifically, for example, a transparent resin plate (2), a conductive network,
The adhesive layer (4) and the polycarbonate film (3) may be arranged in this order and bonded and integrated by hot pressing.
Alternatively, a configuration may be adopted in which an adhesive layer is provided between the transparent resin plate and the conductive net-like body in order to improve the adhesiveness. That is, a transparent resin plate (2), an adhesive layer (4), a conductive network, an adhesive layer (4), a polycarbonate film (3)
May be arranged in this order and bonded and integrated by hot pressing. Above all, it is particularly preferable that the conductive network is disposed at a position within 0.5 mm in depth from either surface of the optical filter from the viewpoint of preventing the filter from warping.

When a conductive layer is formed on the polycarbonate film (3) side, a transparent conductive film, a conductive net or the like may be formed on the surface in the same manner as described above.

On the other hand, the means for imparting the near-infrared ray shielding function is not particularly limited, and known means can be used. For example, as a resin constituting the transparent resin plate (2),
The near-infrared shielding resin composition exemplified below may be used as the near-infrared shielding layer (9), or the resin composition may be coated on a transparent resin plate (2) or a polycarbonate film (3). The near-infrared shielding layer (9) may be laminated.

The near-infrared shielding resin composition includes:
For example, a resin composition containing a monomer having an unsaturated double bond, a copolymer obtained by polymerizing a phosphorus atom-containing monomer, and a copper atom-containing compound described in JP-A-6-118228 And other Japanese Patent Publication Nos. 62-5190, 6-73197, and U.S. Pat.
Resin compositions described in, for example, JP-A No. 29 can be used.

In the optical filter provided with the near-infrared shielding function by the above-mentioned means, the transparent resin plate (2) has a total light transmittance of 60% or more in the visible light region and a light beam having a wavelength of 800 to 1000 nm. 30 transmittance
% Or less is preferable. By setting the thickness in such a range, it is possible to sufficiently secure the transparency (transparency) as the optical filter (1) and to reliably prevent the malfunction of the remote control device. The visible light region refers to a wavelength range of 450 to 650 nm.

On the other hand, the means for imparting the anti-reflection function and / or the anti-glare function is not particularly limited, and known means can be used. The locations where these functions are provided are not particularly limited, but are preferably provided on the surface side of the polycarbonate film (3) where these light control functions can be more effectively exerted. That is, it is preferable to provide one or more light control coat layers (7) having one or two kinds of functions selected from the group consisting of an antireflection function and an antiglare function on the surface side of the polycarbonate film (3). .

When both the hard coat layer (6) and the light control coat layer (7) are laminated on the surface side of the polycarbonate film (3), as shown in FIG.
Preferably, a hard coat layer (6) is laminated on the surface of the polycarbonate film (3), and a light control coat layer (7) is further laminated on the surface (non-adhesive surface) of the hard coat layer (6). . With such a configuration, the mechanical strength of the light control coat layer (7) can be improved.

Means for imparting the antireflection function include, for example, laminating a layer made of a low-refractive-index substance such as magnesium fluoride and silicon oxide, or adding a layer made of this low-refractive-index substance to titanium oxide, Means for laminating a multilayer antireflection layer in combination with a layer made of a high-refractive-index substance such as tantalum, tin oxide, indium oxide, zirconium oxide, and zinc oxide may be used.

Among them, a multilayer antireflection layer in which a layer made of indium oxide and tin oxide (ITO layer) and a layer made of silicon oxide are combined, or at least two layers of a layer made of silicon oxide and a layer made of titanium oxide It is preferable to use a multilayer antireflection layer. The former multilayer anti-reflection layer is preferable in that a more excellent anti-reflection effect is obtained, and furthermore, it has excellent surface hardness and adhesiveness. On the other hand, the latter multilayer anti-reflection layer only has excellent transparency. It is preferable because it is inexpensive and has excellent surface hardness and adhesion.

Means for imparting an antireflection function include:
A substance having a lower refractive index than that of the polycarbonate film (3) is applied to the surface of the polycarbonate film (3) by, for example, 0.1.
It may be applied with a thickness of from 0.5 to 0.3 μm.
The means for imparting the antireflection function is not limited to these exemplified means.

Means for imparting the antiglare function include:
Although it is not particularly limited, for example, a method of dispersing fine particles in a polymer film and laminating a layer having fine irregularities on the surface thereof may be used. As the polymer coating,
The same ones as those exemplified as forming the hard coat layer (6) are preferable. That is, a resin obtained by curing a polyfunctional monomer, or a resin obtained by curing a silicone-based crosslinkable resin, a melamine-based crosslinkable resin, an epoxy-based crosslinkable resin, or the like by heat or ultraviolet light, It is not particularly limited to these.

The fine particles are for forming irregularities for reducing the gloss of the surface. As the fine particles, fine particles of an inorganic compound are preferably used.

The fine particles usually have a particle size of 0.002 to 0.002.
20 μm is used. The amount of the fine particles is
1 to 15 based on 100 parts by weight of the polymerizable compound added
It is preferred to use parts by weight.

The inorganic compound is not particularly limited. For example, inorganic oxides such as silicon dioxide, aluminum oxide, magnesium oxide, tin oxide, silicon monoxide, zirconium oxide and titanium oxide are preferred. Above all, silica fine particles whose main component is silicon dioxide are particularly preferable from the viewpoint of obtaining inexpensive particles having a narrow particle size distribution.

Commercial products of such silica fine particles include, for example, Syloid 72 (manufactured by Fuji Devison Chemical), Syloid 244 (manufactured by Fuji Devison Chemical),
Mizukasil P527 (manufactured by Mizusawa Chemical), Aerosil TT
600 (manufactured by Degussa).

Further, an aggregate of colloidal silica may be used as the silica fine particles. Commercial products of colloidal silica include Ludox AM (manufactured by DuPont),
Xenole A200 (manufactured by Bayer AG), Snowtex-C (manufactured by Nissan Chemical Industries, Ltd.) and the like.

An antifouling layer may be further formed on the frontmost side of the optical filter (1) of the present invention. Such an antifouling layer can be formed, for example, by applying a solution of a fluorine-based or silicon-based coupling agent and then drying it, but is not particularly limited thereto.

In the present invention, it is preferable that at least one surface of the filter (1) is formed with irregularities in order to prevent the occurrence of Newton rings when the filter (1) is mounted on the front surface of the display panel. Above all, from the viewpoint of further improving the prevention of Newton ring occurrence, the 10-point average surface roughness of the surface on which the irregularities are formed is 0.05 μm
It is preferably 20 μm.

The irregularities may be formed by transferring from a transfer mold, by laminating a hard coat layer containing particles such as silica gel, or by any other method capable of providing irregularities. It may be formed by means. Above all, it is preferable that the unevenness is formed by transferring from a transfer mold. In this case, a desired uneven shape can be provided, and the performance of preventing Newton's ring from occurring can be further improved. Furthermore, by using a transfer mold at the time of heating and pressing for hot pressing, it is possible to impart concavities and convexities at the same time as bonding and integration, so that there is an advantage that it is simple and excellent in productivity and the yield can be improved. is there.

When irregularities are formed on the surface of the filter (1), it is preferable that the outermost surface of the formed surface is the hard coat layer (6). With such a configuration, the mechanical strength and scratch resistance of the unevenness itself can be improved, and the generation of Newton rings can be stably prevented over a longer period of time. In this case, the thickness of the hard coat layer (6) is also 1 to 2 as described above.
It is preferably 0 μm.

The optical filter (1) according to the present invention comprises:
The transparent resin plate (2) and the polycarbonate film (3) are manufactured by being bonded by heat pressing in a state where they are overlapped with each other via a layer made of an adhesive. For example, as shown in FIG. 4, each constituent material is put into a pair of press plates (50) (51).
Between the press plate in this state (50) (51)
The adhesive is integrated by pressing under heating conditions. The opposing surfaces of the press plates (50) and (51) are preferably mirror surfaces, so that an optical filter (1) having excellent surface flatness can be obtained.

Further, in order to provide the above-mentioned electromagnetic wave shielding function, near infrared ray shielding function, anti-reflection function, anti-glare function, etc.
When laminating layers having these functions, a sheet or film having the functions is stacked on a pair of press plates (5
It is sufficient to insert and arrange at a predetermined position between 0) and (51) and perform hot pressing. Of course, the layer having these functions is previously formed of a transparent resin plate (2) or a polycarbonate film (3).
May be laminated.

The heating temperature and pressurizing pressure in the above-mentioned hot press are appropriately set according to the properties of the materials used and the like. Usually, the heating temperature is 100 to 180 ° C. and the pressurizing pressure is It is 10 to 60 kg / cm ² .

Further, when the filter (1) has a structure in which at least one surface has irregularities, the filter (1) can be manufactured as follows. That is, in the case where the unevenness is transferred and formed by the transfer method, for example, the pressing plate (50) (51) used for the hot press may be formed by using a transfer die on the press surface. Alternatively, the transfer film (60) having its surface roughened may be formed by placing the transfer film (60) on the press surface side of a normal press plate (50) (51) and performing hot pressing. Among them, the latter means is preferably used because it can be easily removed from between the press plates (50) and (51) after hot pressing. The unevenness of the transfer film (60) may be formed by embossing or may be formed by dispersing a filler in the film. However, from the viewpoint of the durability of the transfer film (60) itself, the embossing is performed. Preferably, it is formed.

The transfer film (60) is not particularly limited as long as it can withstand the heating and pressing conditions during hot pressing. Examples thereof include a polyethylene terephthalate (PET) film and a triacetyl cellulose (TAC) film. Among them, a PET film is preferable from the viewpoint of economy. The thickness of the transfer film (60) is 20 to 500 μm.
m is preferable. When the thickness is less than 20 μm, the handleability of the transfer film (60) itself is reduced, which is not preferable.
If the thickness exceeds 500 μm, the cost increases, which is not preferable. Above all, the thickness of the transfer film (60) is 30 to 300
More preferably, it is set to μm.

In the case of the above-described optical filter (1) having an electromagnetic wave shielding function, in order to shield electromagnetic waves more effectively, the ground is taken from a conductive layer such as a transparent conductive film or a conductive mesh. In many cases, the configuration is such that a part of the conductive layer is exposed to the outside from the end face of the optical filter (1) in order to ensure grounding. With such a configuration, the size of each of the constituent materials such as the transparent resin plate (2) and the polycarbonate film (3) disposed between the pair of press plates (50) and (51) at the time of the above-mentioned hot pressing is determined. It can be easily achieved by appropriately adjusting the pod overlapping position. Alternatively, after bonding and integration by hot pressing, the optical filter (1) may be cut into a predetermined shape so that the conductive layer is exposed from the end face.

According to the production method of the present invention, by using a polycarbonate film as the film, the surface of the film such as the light control coat layer (7) or the hard coat layer (6) for anti-reflection and anti-glare is formed on the surface of the film. Even in the configuration in which the coat layer is provided, it is possible to suppress the occurrence of cracks and cracks in the surface coat layer after hot pressing.

Even in the case where the light control coat layer (7) and the hard coat layer (6) are provided to form a multi-layer structure, a large number of constituent materials are formed by a pair of press plates (50). (51) There is an advantage that it can be manufactured only by performing the hot pressing once by placing it between them. That is, even a multi-layer structure can be manufactured by one hot press, so that it is extremely excellent in productivity. Therefore, even a multi-layer structure can be economically manufactured at low cost.

The optical filter according to the present invention is suitably used, for example, as a front panel for various displays, but is not particularly limited to this use. Among them, it is particularly suitably used as a front panel for a plasma display panel, which is a large display device, or a front panel for a CRT (cathode ray tube).

[0076]

Next, specific embodiments of the present invention will be described.

<Materials Used> (Transparent resin plate A) 3 mm thick having near-infrared shielding function
Acrylic resin cast plate (having a near-infrared shielding function by incorporating a phosphorus compound and a copper compound into the resin) The transparent resin plate A has a total light transmittance of 80% in the visible light region.
The light transmittance at a wavelength of 800 to 1000 nm was 20% or less over the entire region. (Adhesive film A) Soft acrylic film "Sanjuren" manufactured by Kaneka Corporation
(Thickness: 50 μm) (Polycarbonate film A) A polycarbonate film (glass transition temperature: 142 ° C., thickness: 125 μm) with a hard coat layer (4 μm in thickness) made of an acrylic ultraviolet curable resin laminated on one side (Polycarbonate film) B) A hard coat layer (4 μm in thickness) made of an acrylic ultraviolet curable resin is laminated on one side of a polycarbonate film (glass transition temperature 142 ° C., thickness 125 μm), while an adhesive (Sumitomo Chemical Co., Ltd.) Industrial “SUMIPEX CEMENT 7”) coated with a thickness of 2 μm (polycarbonate film with anti-reflection coating) On the hard coat surface of the polycarbonate film A, an indium oxide-tin oxide layer (ITO layer) by DC magnetron sputtering, Silicon oxide layer, ITO layer (Conductive woven fabric) A conductive mesh body in which a woven fabric made of polyester fibers is thinly plated with copper and further coated with a conductive resin for preventing reflection (a conductive woven fabric) The mesh size is 135 × 135 mesh, fiber diameter 44 μm, manufactured by Seiren Co., Ltd.).

Embodiment 1 As shown in FIG. 4, a transparent resin plate A (2) is provided on the mirror surface of the lower press plate (51) between the pair of upper and lower stainless steel mirror press plates (50) and (51). ,
Adhesive film B (30), polycarbonate film A
(31) After the transfer type non-glare PET film (60) (the uneven surface (60a) is turned down) is placed in this order (with the hard coat surface facing up), a pair of upper and lower press plates (50)
According to (51), pressing was performed at a pressure of 30 kg / cm ² and a temperature of 130 ° C. for 30 minutes. Next, after quenching under a pressure of 30 kg / cm ² , a pair of press plates (50) and (51) were opened to obtain an optical filter having the layered structure as shown in FIG.

The non-glare PET film is obtained by forming a hard coat on a PET film having a thickness of 188 μm and forming an uneven surface (non-glare surface) by embossing on the surface of the hard coat layer.

<Example 2> A polycarbonate film A (hard coat side down) was placed on the mirror surface of the lower press plate between a pair of upper and lower stainless steel mirror press plates.
After the adhesive film A, the transparent resin plate A, the conductive woven fabric, the adhesive film A, and the polycarbonate film A (with the hard coat surface facing up) are placed in this order, the pressure is set to 40 kg / cm by a pair of upper and lower press plates. ^2. Pressed at a temperature of 120 ° C. for 30 minutes. Next, after rapidly cooling under a pressure of 40 kg / cm ² , a pair of press plates was opened to obtain an optical filter having a multilayer structure as shown in FIG.

The polycarbonate film A and the adhesive film A placed above the conductive woven fabric are 20 mm smaller in length and width than other materials (including the conductive woven fabric). Therefore, the obtained optical filter had a configuration in which the periphery of one side was 10 mm in width and the conductive woven fabric was exposed.

Example 3 Polycarbonate film B was used in place of polycarbonate film A in Example 2.
And an optical filter having a multilayer structure as shown in FIG. 2 was obtained in the same manner as in Example 2 except that the press temperature was set to 110 ° C.

Example 4 A polycarbonate film B (with the hard coat side down) was placed on the mirror surface of the lower press plate between a pair of upper and lower stainless steel mirror press plates.
After placing the transparent resin plate A, the conductive woven fabric, the adhesive film A, and the polycarbonate film A (with the hard coat surface facing up) in this order, the pressure is 40 kg / cm ^{2 at} a temperature of 130 ° C. by a pair of upper and lower press plates. For 30 minutes. Then, after quenching under a pressure of 40 kg / cm ² ,
The pair of press plates was opened to obtain a multilayer optical filter as shown in FIG.

Example 5 A multilayer optical filter as shown in FIG. 3 was prepared in the same manner as in Example 2 except that a polycarbonate film with an antireflection film was used instead of the polycarbonate film A in Example 2. obtain.
Cracks and the like hardly occur on the surface of the optical filter.

Comparative Example 1 Polycarbonate Film A
An optical filter was obtained in the same manner as in Example 2 except that an acrylic film with a hard coat layer was used instead of the above, and the hard coat layer side was arranged upward.

Each optical filter manufactured as described above was evaluated according to the following test method. The results are shown in Tables 1 and 2.

<Electromagnetic Wave Shielding Test> A silver paste was applied to the conductive woven fabric exposed at one edge of each optical filter, dried, and then dried with a copper conductive tape (copper foil tape 8321 manufactured by Teraoka Seisakusho; 20 mm width). ) Was affixed to the periphery, and then the level (dB) at which electromagnetic waves of each frequency attenuated was examined using a shield material evaluation system R2547 type (manufactured by Advantest Corporation).

<Total Light Transmittance Measurement Method> The total light transmittance was measured using a haze meter (manufactured by Suga Test Instruments).

<Visible / Near-Infrared Transmittance Measurement Method> The transmittance at each wavelength was measured using a self-recording spectrophotometer type 330 (manufactured by Hitachi, Ltd.).

<Reflectance Evaluation Method> A reflection spectrum was measured in the range of 300 to 800 nm using MPS2000 (manufactured by Shimadzu Corporation), and the luminosity-corrected reflectance was determined from the spectrum, and this was defined as the reflectance.

<Surface Quality Evaluation Method> The surface of the obtained optical filter was observed and evaluated based on the following criteria.

(Judgment Criteria) Cracks are hardly generated: "」 "A small number of cracks are generated ..." △ "A large number of cracks are generated ..." x "

<Evaluation Method of Newton Ring Generation Prevention> The obtained optical filter was brought into close contact with a plasma display and the presence or absence of Newton rings was visually checked.
Those that did not occur were indicated by “○”, and those that did occur were indicated by “×”.

[0094]

[Table 1]

[0095]

[Table 2]

As is clear from the table, the optical filters of Examples 1 to 4 of the present invention have a polycarbonate film surface on which a surface coat layer such as an antireflection layer, an antiglare layer and a hard coat layer is provided. No cracks were generated, and excellent surface quality was obtained. In addition, they have sufficient functions such as desired electromagnetic wave shielding, near-infrared shielding, antireflection, and prevention of Newton's ring.

On the other hand, in Comparative Example 1 in which an acrylic film was used as the film, many cracks occurred in the hard coat layer on the surface, and the surface quality was poor.

[0098]

As described above, since the optical filter of the present invention is bonded by hot pressing, it has excellent adhesion between the transparent resin substrate and the film, and sufficient adhesion durability can be obtained. In addition, since a polycarbonate film is used as the film, even if the surface is provided with a surface coat layer such as a light control coat layer or a hard coat layer for anti-reflection and anti-glare, the surface coat may be formed after hot pressing. The generation of cracks and cracks in the layer can be suppressed.

When the electromagnetic wave shielding function is provided, it is possible to effectively prevent the electromagnetic waves from reaching the operator. In particular, when the conductive mesh is laminated and integrated between the transparent resin plate and the polycarbonate film to have an electromagnetic wave shielding function, the advantage that the optical filter can be effectively prevented from warping. is there.

[0100] In the case of having near-infrared shielding, it is possible to prevent remote control devices of various home electric appliances from malfunctioning. Above all, when the total light transmittance in the visible light region of the transparent resin plate is 60% or more and the light transmittance at a wavelength of 800 to 1000 nm is 30% or less, sufficient transparency as an optical filter is secured. In addition, malfunction of the remote control device can be reliably prevented.

When a hard coat layer is provided on the surface side of the polycarbonate film, scratch resistance can be improved.

Further, when one or more light control coat layers having one or two kinds of functions selected from the group consisting of an antireflection function and an antiglare function are provided on the surface side of the polycarbonate film, By arranging it on the front side of the optical filter, the above function can be exhibited more effectively.

Further, when irregularities are formed on at least one surface of the filter, the generation of Newton rings can be prevented. In particular, when the irregularities are transferred from the transfer mold, the generation of Newton rings can be more reliably prevented.

The optical filter of the present invention is suitably used, for example, as a front panel for various displays, and is particularly suitable as a front panel for a plasma display panel or a front panel for a CRT (cathode ray tube).

Further, according to the manufacturing method of the present invention, since the bonding is performed by hot pressing, a product having excellent adhesion between the transparent resin substrate and the film can be provided. In addition, since a polycarbonate film is used as the film, even in a configuration in which a surface coat layer is provided on the surface thereof, it is possible to suppress the occurrence of cracks and cracks in the surface coat layer after hot pressing, and the surface quality is excellent. Can be provided. Furthermore, even if a light control coat layer, a hard coat layer, and the like are provided to form a multilayer structure, all the constituent materials can be bonded and integrated by performing a single heat press, so that the productivity is excellent, and It can be manufactured economically at low cost.

In the above manufacturing method, when the adhesive is a thermosetting resin, the adhesive is in a pressurized state during thermosetting, so that the adhesive strength can be further improved.

When the adhesive is a hot-melt resin, the adhesive can be adhered by applying pressure in a more sufficiently softened state, so that the adhesive strength can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical filter according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an optical filter according to another embodiment.

FIG. 3 is a cross-sectional view illustrating an optical filter according to yet another embodiment.

FIG. 4 is a sectional view showing an example of a state before hot pressing in the manufacturing method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical filter 2 ... Transparent resin plate 3 ... Polycarbonate film 4 ... Adhesive layer 6 ... Hard coat layer 7 ... Light control coat layer 8 ... Electromagnetic wave shielding layer 9 ... Near infrared shielding layer

Continued on the front page F-term (reference) 2H048 AA03 AA09 AA16 AA24 AA28 CA03 CA09 CA12 CA19 CA23 CA26 CA29 2K009 AA02 AA15 BB14 CC03 CC06 CC34 DD01 EE03 EE05 4F100 AA20E AA33E AB17C AK01A AK25BA00A04 BA05BA05BA10BAK BA10D BA10E BA13 CB03 DC16C DG12C EH71C EJ17 EJ20 EJ39 EJ42 GB90 HB21 JB14D JD08 JD10 JG01C JK12D JN01A JN06E JN30 JN30E YY00 5G435 AA00 AA08 AA14 AA16 BB06 GG03 GG06 GG06

Claims (13)

[Claims] 1. An optical filter comprising a transparent resin plate and a film bonded and integrated via an adhesive layer, wherein the film is a polycarbonate film, and the bonding and integration via the adhesive layer is performed by hot pressing. An optical filter characterized by being made. 2. The optical filter according to claim 1, wherein the optical filter has an electromagnetic wave shielding function. 3. The optical filter according to claim 2, wherein a conductive net is laminated and integrated between the transparent resin plate and the polycarbonate film to have an electromagnetic wave shielding function. 4. The optical filter according to claim 1, wherein the optical filter has a near-infrared shielding function. 5. The optical filter according to claim 4, wherein the transparent resin plate has a total light transmittance of 60% or more in a visible light region and a light transmittance of a wavelength of 800 to 1000 nm of 30% or less. 6. The optical filter according to claim 1, wherein a hard coat layer is provided on a surface side of the polycarbonate film. 7. A light control coating layer having one or two functions selected from the group consisting of an antireflection function and an antiglare function is provided on the surface side of the polycarbonate film. The optical filter according to any one of claims 1 to 6. 8. The optical filter according to claim 1, wherein irregularities are formed on at least one surface of the filter. 9. The optical filter according to claim 8, wherein the irregularities are transferred from a transfer mold. 10. A method for producing an optical filter, comprising: bonding a transparent resin plate and a polycarbonate film with each other via a layer made of an adhesive and performing heat pressing to integrate them. 11. The method according to claim 10, wherein the adhesive is a thermosetting resin. 12. The method according to claim 10, wherein the adhesive is a hot melt resin. 13. A front panel for a plasma display, comprising the optical filter according to claim 1.