JP2005164972A - Optical filter and display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter capable of solving problems in terms of image quality that an image is reflected in double when being arranged on the front face of a display. <P>SOLUTION: Regarding the optical filter having a laminated structure where at least a transparent base material is laminated with a near infrared ray absorbing layer containing near infrared ray absorbing pigment for absorbing the near infrared ray in acrylic resin, the double refraction value of the acrylic resin is 0 to 15nm. It is preferable that the acrylic resin is copolymerized acrylic resin constituted of methyl methacrylate and (meta) acrylic acid compound capable of negating the negative double refraction value of the methyl methacrylate and setting the double refraction value of the copolymer to be 0-15nm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical filter having a near infrared shielding property. The present invention also relates to a display provided with such an optical filter, particularly a plasma display.

  It is said that electromagnetic waves generated by electrical or electronic devices may adversely affect other devices and may affect human bodies and animals. As an example, an electromagnetic wave with a frequency of 30 MHz to 130 MHz is generated from a plasma display (hereinafter may be abbreviated as PDP), which may affect surrounding computers or computer-utilized equipment. It is desired that the electromagnetic wave to be transmitted is not leaked to the outside as much as possible.

  The PDP also uses a mixed gas of neon and xenon as the discharge gas, so it emits near infrared light with a wavelength of 800 nm to 1000 nm. This near infrared light is used for various devices using the near infrared light, for example, remote home appliances. It is said that there is a possibility of causing malfunction of communication devices using near infrared rays such as controllers, personal computers and cordless phones, and improvement is also desired in this respect.

  Conventionally, as an improvement as described above, an adhesive or pressure-sensitive adhesive, a metal thin film mesh, and a planarizing layer for flattening the uneven surface of the mesh are sequentially laminated on a transparent base film. An electromagnetic wave shielding member in which an absorbent that absorbs a specific wavelength of visible light and / or near infrared is contained in an adhesive or pressure sensitive adhesive in the inside or a flattening layer has been proposed (for example, Patent Document 1). reference.). Since the electromagnetic wave shielding member described in Patent Document 1 has a metal thin film mesh, the electromagnetic wave shielding member has an electromagnetic wave shielding property and contains an absorbent that absorbs a specific wavelength of visible light and / or near infrared. Therefore, it also has a near-infrared shielding property, and it is possible to improve the color balance of the display and the contrast by absorbing external light.

  Moreover, the film obtained by the coating method and the casting method using the pigment | dye which has a near-infrared absorptivity is also known (for example, refer patent document 2).

In Patent Document 3, in order to improve the image quality when the optical filter is arranged on the front surface of the display, the transparent base material does not substantially contain particles, and foreign matters having a size of 20 μm or more are 10 per unit film area. There has been proposed a method for reducing optical distortion by setting the number of particles / m ² or less.

JP 2002-311843 A (page 4, FIG. 7-9) JP-A-11-116826 (5th page, FIG. 1) JP 2001-174627 A

  However, in any of the above prior arts, depending on the resin of the layer containing the absorbent, there may be image quality problems such as double images when the optical filter is placed on the front surface of the display, or under high temperature or humidification. Thus, there is a problem that the shielding property of near infrared rays is lowered, specific absorption appears in the visible region, and it appears colored or discolored. In addition, when trying to solve these problems, the optical filter must be originally provided that the near-infrared absorbing layer and the metal mesh must not be visible (invisibility), transparency (haze), There are a transmittance in the visible region (luminous transmittance), a shielding property in the near infrared region (near infrared transmittance), and the like.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical filter in which image quality problems such as double images appearing when the optical filter is arranged on the front surface of a display are solved. In addition, the present invention provides an optical filter in which near-infrared shielding properties are reduced at high temperatures or humidification, or specific absorption appears in the visible region, and coloring or discoloration is solved. This is the issue. Furthermore, the present invention aims to provide an optical filter to which various functions are added after the above-mentioned problems are solved, and to provide a display, particularly a plasma display, to which these optical filters are applied. Let it be an issue.

  As a result of repeated studies to solve the above problems, the present inventor uses an acrylic resin having a birefringence value of a certain standard or less as a resin of a layer containing a near-infrared absorbing dye, In addition to the properties, it has been found that the above problems can be solved by using an acrylic resin having a hydroxyl value, an acid value, or a glass transition temperature in a predetermined range, and the present invention includes the following matters. Was able to reach.

  A first invention is an optical filter having a laminated structure in which at least a transparent base material and a near-infrared absorbing layer containing a near-infrared absorbing dye that absorbs near-infrared in an acrylic resin are laminated, The present invention relates to an optical filter having a birefringence value of 0 to 15 nm.

According to a second invention, in the first invention, the acrylic resin is produced by randomly copolymerizing two or more kinds of acrylic resin monomers.
According to a third invention, in the first or second invention, the acrylic resin is 100 parts by mass of the total amount of monomer components.
(1) 5 to 100 parts by mass of an acrylic resin monomer component having an alicyclic group or an aromatic ring group,
(2) 95-0 parts by mass of a monomer component other than an acrylic resin having the alicyclic group or aromatic ring group,
It is related with the optical filter characterized by being a copolymer or a homopolymer consisting of.

  According to a fourth invention, in the first or second invention, the acrylic resin cancels the negative birefringence value of the methyl methacrylate and the methyl methacrylate so that the birefringence value of the copolymer is 0 to 15 nm. It is related with the optical filter characterized by being a copolymerization acrylic resin with the (meth) acrylic acid compound which can be made. In this specification, (meth) acryl means acryl or methacryl.

  According to a fifth invention, in the first or second invention, the acrylic resin is a copolymerized acrylic resin of methyl methacrylate and a structural unit represented by the following general formula (1). The present invention relates to an optical filter.

(In the general formula (1), R ¹ represents a hydrogen atom or an alkyl group, and R ² represents an alicyclic group or an aromatic ring group.)

  A sixth invention relates to an optical filter according to any one of the first to fifth inventions, wherein the hydroxyl value of the acrylic resin is 10 or less.

  A seventh invention relates to the optical filter according to any one of the first to sixth inventions, wherein the acid value of the acrylic resin is 10 or less.

  An eighth invention relates to the optical filter according to any one of the first to seventh inventions, wherein the glass transition temperature of the acrylic resin is 80 ° C. to 150 ° C.

  A ninth invention relates to the optical filter according to any one of the first to eighth inventions, wherein the near-infrared absorbing dye is a diimmonium compound represented by the following general formula (2). is there.

(In the general formula (2), R is the same or different hydrogen, alkyl group, aryl group, hydroxyl group, phenyl group, or halogenated alkyl group, X is a monovalent or divalent anion, n Is 1 or 1/2.)

  A tenth invention relates to the optical filter according to the ninth invention, wherein X in the general formula (2) is a monovalent bistrifluoromethanesulfonylimido ion.

  An eleventh aspect of the present invention relates to the optical filter according to any one of the first to tenth aspects, further comprising an electromagnetic wave shielding layer in order to obtain an optical filter having excellent electromagnetic wave shielding properties.

  A twelfth invention relates to an optical filter characterized in that in any one of the first to eleventh inventions, an antifouling layer is provided in order to obtain an optical filter having excellent antifouling properties.

  A thirteenth aspect of the present invention relates to the optical filter according to any one of the first to twelfth aspects of the present invention, which includes an adhesive layer in order to facilitate attachment to the application surface.

  A fourteenth aspect of the present invention relates to the optical filter according to any one of the first to thirteenth aspects, further comprising an antireflection layer in order to obtain an optical filter having excellent antireflection properties.

  A fifteenth aspect of the present invention relates to the optical filter according to any one of the first to fourteenth aspects, further comprising an antiglare layer in order to obtain an optical filter excellent in antiglare property.

  A sixteenth aspect of the present invention relates to a display characterized in that the optical filter according to any one of the first to fifteenth aspects of the present invention is disposed on the viewing side of the display.

  According to the first invention, the near-infrared absorbing layer in the optical filter contains a near-infrared absorbing dye, and the binder resin is an acrylic resin having a birefringence value of 0 to 15 nm. Therefore, when the optical filter is disposed on the front surface of the display In addition, the double reflection of the image is suppressed, and there is an effect that high-definition image quality can be obtained.

  According to the second invention, a copolymer resin is used for the binder resin used for the near infrared absorption layer, and the copolymer component is prepared by random copolymerization of two or more kinds of acrylic resin monomer components. Therefore, since it becomes easy to set the birefringence value of the copolymer to 0 to 15 nm, when the optical filter is arranged on the front surface of the display, double reflection of the image is suppressed, and high-definition image quality is obtained. effective.

According to the third invention, a copolymer acrylic resin is used for the binder resin used for the near-infrared absorbing layer, and the acrylic resin is 100 parts by mass of the total amount of monomer components.
(1) 5 to 100 parts by mass of an acrylic resin monomer component having an alicyclic group or an aromatic ring group,
(2) 95-0 parts by mass of a monomer component other than an acrylic resin having the alicyclic group or aromatic ring group,
Since it is easy to make the birefringence value of the acrylic resin from 0 to 15 nm because it is a copolymer or homopolymer made of the above, the double image of the image is suppressed when the optical filter is placed on the front surface of the display. As a result, high-definition image quality can be obtained.

  According to the fourth invention, a copolymer acrylic resin is used as the binder resin used in the near infrared absorption layer, and as a copolymer component, methyl methacrylate and the negative birefringence value possessed by the methyl methacrylate are canceled to co-polymerize. Since a (meth) acrylic acid compound capable of setting the combined birefringence value to 0 to 15 nm is used, when the optical filter is arranged on the front surface of the display, double image reflection is suppressed and high-definition image quality is achieved. Is effective.

  According to the fifth invention, a copolymer acrylic resin is used as the binder resin used in the near infrared absorption layer, and as a copolymer component, methyl methacrylate and the negative birefringence value of the methyl methacrylate are canceled to co-polymerize. Since the monomer of the structural unit represented by the general formula (1) capable of setting the combined birefringence value to 0 to 15 nm is used, when the optical filter is arranged on the front surface of the display, a double image is displayed. Is suppressed, and there is an effect that a high-definition image quality can be obtained.

  Moreover, according to 5th invention, the (meth) acrylic resin monomer which has an alicyclic group or an aromatic ring group of the structural unit represented by the said General formula (1) is used for the binder resin used for a near-infrared absorption layer. Because it is used, it has a high transparency, and has a structure containing a lot of carbon and hydrogen with no lone pair, suppressing moisture in the atmosphere from being adsorbed by the resin, and reducing the water absorption of the acrylic resin. It is possible to prevent the near-infrared absorbing dye from reacting with water to deteriorate, and to have a stable near-infrared absorbing ability even under high temperature and high humidity. In addition, by using an acrylic resin monomer having an alicyclic group or an aromatic ring group, which is the structural unit represented by the general formula (1), an effect of increasing the glass transition temperature can be obtained.

  Furthermore, according to the fifth invention, by copolymerizing the compound represented by the general formula (1) with methyl methacrylate, there is also an effect of suppressing a decrease in mechanical strength such as bending fracture strength of the optical filter. can get.

  According to the sixth invention, in addition to the effects of any one of the first to fifth inventions, the acrylic resin having a hydroxyl value of 10 or less is used. It is possible to provide an optical filter having a near-infrared absorption function that is stable over time even under high temperature and high humidity conditions.

  According to the seventh invention, in addition to the effects of any one of the first to sixth inventions, an acrylic resin having an acid value of 10 or less is used. It is possible to provide an optical filter having a near-infrared absorption function that is stable over time even under high temperature and high humidity conditions.

  According to the eighth invention, in addition to the effects of any one of the first to seventh inventions, the range of the glass transition temperature of the acrylic resin is defined above the normal use conditions. Alternatively, the reaction between the near-infrared absorbing dye and the surrounding acrylic resin can be suppressed, and an optical filter having practically sufficient heat resistance can be provided.

  According to the ninth and tenth inventions, in addition to the effects of the first to eighth inventions, the near-infrared absorbing dye is a diimmonium compound represented by the general formula (2), and the counter ion is Since it is a bistrifluoromethanesulfonyl imido ion, it is possible to provide an optical filter having a near-infrared absorption function that is stable over time even when used for a long time.

  According to the eleventh aspect of the invention, in addition to the effects of any one of the first to tenth aspects of the invention, an electromagnetic wave shielding layer is provided to shield electromagnetic waves generated from the applied electrical and electronic devices. Possible optical filters can be provided and are particularly suitable for application to plasma displays.

  According to the twelfth invention, in addition to the effects of any one of the first to eleventh inventions, by providing the antifouling layer, it is possible to prevent dust and contaminants from adhering, and even if they adhere, they can be removed. An easy optical filter can be provided.

  According to the thirteenth invention, in addition to the effects of any one of the first to twelfth inventions, by having an adhesive, it is possible to provide an optical filter that can be easily attached to an application surface.

  According to the fourteenth invention, in addition to the effects of any one of the first to thirteenth inventions, by providing the antireflection layer, it is possible to prevent reflection of unnecessary light on the laminated surface, and to An optical filter capable of improving the contrast can be provided.

  According to the fifteenth invention, in addition to the effects of any one of the first to fourteenth inventions, when the antiglare layer is laminated, when placed on the front surface of the display, in a specific position and direction of the display. An optical filter capable of mitigating generated scintillation can be provided.

  According to the sixteenth aspect, it is possible to provide a display in which the effect of any one of the first to fifteenth optical filters is exhibited.

  1A and 1B are cross-sectional views illustrating the laminated structure of the optical filter of the present invention. The optical filter of the present invention is most basically a near-infrared absorbing laminate having a laminated structure in which a near-infrared absorbing layer 3 is laminated on a transparent substrate 2 as indicated by reference numeral 1A in FIG. It consists of four. This transparent substrate 2 may have been subjected to a treatment for improving adhesiveness that can be performed during lamination.

  The near-infrared absorbing laminate 4 shown in FIG. 1 (a) is provided with additional functions by adding one or more of various layers known in the field of optical filters. An optical filter can be configured. That is, as shown in FIG. 1B, one or more functional layers 5, for example, an electromagnetic wave shield for cutting electromagnetic waves, are disposed on the near infrared absorption layer 3 side of the near infrared absorption laminate 4, that is, on the upper side in the drawing. One layer or two or more functional layers selected from a layer, an antifouling layer for preventing contamination during use, and other antireflection layers and antiglare layers may be laminated. These functional layers 5 may be laminated only on the lower side of the transparent base material 2, may be laminated on both the upper side and the lower side, or between the transparent base material 2 and the near-infrared absorbing layer 3. May be.

  The optical filters 1A and 1B with or without various layers as described above are laminated on one or both sides with an adhesive layer, and attached to the application surface to which the optical filter is to be applied. You may comprise so that it may be. Since the pressure-sensitive adhesive layer is difficult to handle as it is exposed, it is preferable that a sheet having peelability is laminated until just before sticking. The optical filters 1A and 1B that can adopt these various structures can be applied to various types of displays. For example, as shown in FIG. 2, the front surface (viewing side surface) of a plasma display (PDP) 6 is used. The optical filter 1 on which a pressure-sensitive adhesive layer (not shown) is laminated can be directly attached to the front surface of the plasma display 6 for use. In many cases, the pressure-sensitive adhesive layer is laminated on one side of the optical filter 1; however, the pressure-sensitive adhesive is laminated on both sides, and one side is attached to a display and the other side is a film having other functions. It can also be used for purposes such as sticking together.

  The transparent substrate 2 and the near-infrared absorbing layer 3 constituting the optical filter 1 of the present invention, and the materials and lamination methods of each layer that can be added to the basic laminated structure as described above will be described in detail below. .

Near-infrared absorbing layer:
The near-infrared absorbing layer 3 basically contains a near-infrared absorbing dye that absorbs near-infrared rays in a transparent binder resin.

  When the optical filter 1 is applied to the front surface of the plasma display 6, which is a typical use of the optical filter 1, near infrared rays generated when the plasma display 6 emits light using xenon gas discharge are as described above. In addition, since it may cause malfunction in various devices, the near infrared absorption layer 3 in the optical filter 1 preferably absorbs the near infrared region, that is, the wavelength region of 800 nm to 1200 nm. The light transmittance at is preferably 20% or less, and more preferably 10% or less.

  At the same time, the near-infrared absorbing layer 3 needs to have a sufficient light transmittance in the visible light region, that is, in the wavelength region of 380 nm to 780 nm.

  In addition, the light transmittance in both the above-mentioned wavelength ranges is based on a spectrophotometer (manufactured by Shimadzu Corporation, product number: “UV-3100PC”).

(I) Near infrared absorbing dye Specific examples of the inorganic infrared absorbing dye include tin oxide, indium oxide, magnesium oxide, titanium oxide, chromium oxide, zirconium oxide, nickel oxide, aluminum oxide, Examples include zinc oxide, iron oxide, ammonium oxide, lead oxide, bismuth oxide, and lanthanum oxide. Specific examples of organic near-infrared absorbing dyes include cyanine compounds, phthalocyanine compounds, naphthalocyanine compounds, naphthoquinone compounds, anthraquinone compounds, aminium compounds, pyrylium compounds, cerium compounds, squarylium compounds, diimmonium compounds. Compounds, copper complexes, nickel complexes, dithiol metal complexes and the like.

  These near infrared absorbing dyes can be used alone or in combination of two or more. Among these, the inorganic near-infrared absorbing dye is desirably fine particles having an average particle diameter of 0.005 μm to 1 μm, more preferably 0.05 μm to 1 μm, and most preferably 0.05 μm to 0.5 μm.

  Among the above, it is preferable to use a diimmonium compound as the near-infrared absorbing dye used in the optical filter 1 of the present invention. The reason for this is that the diimmonium compound has a large absorption with a molar extinction coefficient ε of about 100,000 in the near-infrared region and a slight light absorption in the visible light region at a wavelength of 400 nm to 500 nm. This is because the light transmittance is superior to other near infrared absorbing dyes.

  As the diimmonium-based compound, those represented by the general formula (2) are preferable, and R in the formula is as described above. Among them, the alkyl group includes a methyl group, an ethyl group, a propyl group, or a butyl group. Groups and the like are preferred. X in the formula is a monovalent or divalent anion. In the case of a monovalent anion, n is 1, and in the case of a divalent anion, n is 1/2. Examples of monovalent anions include organic acid monovalent anions and inorganic monovalent anions.

  Examples of the organic acid monovalent anion include organic carboxylate ions such as acetate ion, lactate ion, trifluoroacetate ion, propionate ion, benzoate ion, oxalate ion, succinate ion and stearate ion; Organic sulfonic acid such as acid ion, toluenesulfonic acid ion, naphthalene monosulfonic acid ion, chlorobenzenesulfonic acid ion, nitrobenzenesulfonic acid ion, dodecylbenzenesulfonic acid ion, benzenesulfonic acid ion, ethanesulfonic acid ion, trifluoromethanesulfonic acid ion Ions; organic borate ions such as tetraphenylborate ion and butyltriphenylborate ion; bistrifluoromethanesulfonylimido ion, etc., preferably bistrifluoromethanesulfone Ruimido ion, trifluoromethanesulfonate ion, include halogenoalkyl sulfonate ion or an alkyl aryl sulfonate ion such as toluenesulfonate ion, particularly preferably a bistrifluoromethanesulfonylimide ion. In the case of bistrifluoromethanesulfonylimido ion, a stable near-infrared absorbing function can be maintained over time even when the optical filter is used as the optical filter 1 of the plasma display 6 for a long time.

  Inorganic monovalent anions include, for example, halogen ions such as fluorine ion, chlorine ion, bromine ion and iodine ion; thiocyanate ion, hexafluoroantimonate ion, perchlorate ion, periodate ion, nitrate ion, tetra Fluoroborate ion, hexafluorophosphate ion, molybdate ion, tungstate ion, titanate ion, vanadate ion, phosphate ion, borate ion, etc. are preferable, and preferred are perchlorate ion, iodine Ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, and the like. Among these inorganic anions, particularly preferred are tetrafluoroborate ion, hexafluorophosphate ion, hexafluoroantimonate ion and the like.

  Examples of the divalent anion include naphthalene-1,5-disulfonic acid, R acid, G acid, H acid, benzoyl H acid, p-chlorobenzoyl H acid, p-toluenesulfonyl H acid, chloro H acid, Chloroacetyl H acid, methanyl γ acid, 6-sulfonaphthyl-γ acid, C acid, ε acid, p-toluenesulfonyl R acid, naphthalene-1,6-disulfonic acid, 1-naphthol-4,8-disulfonic acid, Naphthalenedisulfonic acid derivatives such as carbonyl J acid, 4,4′-diaminostilbene-2,2′-disulfonic acid, diJ acid, naphthalic acid, naphthalene-2,3-dicarboxylic acid, diphenic acid, stilbene-4,4 '-Dicarboxylic acid, 6-sulfo-2-oxy-3-naphthoic acid, anthraquinone-1,8-disulfonic acid, 1,6-diaminoanthraquinone-2,7-disulfur Acid, 2- (4-sulfophenyl) -6-aminobenzotriazole-5-sulfonic acid, 6- (3-methyl-5-pyrazolonyl) -naphthalene-1,3-disulfonic acid, 1-naphthol-6 And divalent organic acid ions such as (4-amino-3-sulfo) anilino-3-sulfonic acid. Preferable examples include naphthalene-1,5-disulfonic acid and R acid.

The diimmonium compound represented by the general formula (2) can be obtained, for example, by the following method described in Japanese Patent Publication No. 43-25335. That is, the amino compound obtained by reducing the product obtained by the Ullmann reaction of p-phenylenediamine and 1-chloro-4-nitrobenzene is dissolved in an organic solvent, preferably water-soluble polar such as dimethylformamide (DMF). A halogenated compound corresponding to the desired R in the general formula (2) (for example, BrCH ₂ CH ₂ when R is n-C ₄ H ₉ ) in a solvent at 30 to 160 ° C., preferably 50 to 140 ° C. It can be reacted with (CH ₂ CH ₃ ) to obtain a compound in which all the substituents (R) are the same (hereinafter referred to as all substituents).

In addition, when synthesizing a compound other than all substituents, for example, when synthesizing a compound in which seven out of eight Rs are iso-C ₄ H _{9 and the} remaining one is n-C ₄ H ₉ , moles after the introduction of reagents _{(BrCH 2 CH (CH 3)} 2) and iso-C ₄ H ₉ group in seven of reacted by eight R (7 mole per the amine compound to 1 mole), the remaining Is reacted with the corresponding reagent (BrC ₄ H ₉ ) in the number of moles (1 mole per 1 mol of the amine compound) necessary to introduce the substituent (n—C ₄ H ₉ ). Any compound other than all substituted compounds can be obtained by the same method as the exemplified method for producing this compound.

  Thereafter, the compound synthesized above is oxidized in an organic solvent, preferably in a water-soluble polar solvent such as DMF at 0 to 100 ° C., preferably 5 to 70 ° C., corresponding to X in the general formula (2) ( For example, silver salt) is added to carry out the oxidation reaction. If the equivalent of the oxidizing agent is 2 equivalents, the diimmonium salt compound represented by the general formula (2) is obtained, and if the equivalent is 1 equivalent, a monovalent aminium salt compound (hereinafter referred to as an aminium body) is obtained. can get. In addition, after the compound synthesized above is oxidized with an oxidizing agent such as silver nitrate, silver perchlorate, cupric chloride, etc., salt exchange is performed by adding an acid or salt of a desired anion to the reaction solution. The compound represented by the general formula (2) can also be synthesized.

  In the near-infrared absorbing layer 3, the use of one or more near-infrared absorbing dyes as described above is as described above, but the diimmonium compound which is a preferred near-infrared absorbing dye in the present invention is used. The near-infrared absorbing layer other than the diimmonium-based compound for the purpose of expanding the near-infrared absorbing wavelength range of the near-infrared absorbing layer or preparing the color of the near-infrared absorbing layer (= appearance color). For example, a phthalocyanine compound or a dithiol metal complex is used in combination with a diimmonium compound. Both phthalocyanine compounds and dithiol metal complexes may be used.

(Ii) Acrylic resin The acrylic resin as the binder resin used for the near-infrared absorbing layer 3 is a highly transparent resin having a birefringence value of 0 to 15 nm. By setting the birefringence value to 0 to 15 nm, when the optical filter is arranged on the front surface of the display, double reflection of the image is suppressed, and there is an effect that a high-definition and highly transparent image quality can be obtained.

  The acrylic resin as the binder resin is preferably capable of canceling the negative birefringence value of methyl methacrylate and the methyl methacrylate so that the birefringence value of the copolymer is 0 to 15 nm (meta ) Copolymerized acrylic resin with acrylic acid compound. More preferably, it is a copolymer acrylic resin of methyl methacrylate and the (meth) acrylic acid compound represented by the general formula (1), and a copolymer acrylic resin having a birefringence value of 0 to 15 nm.

  Acrylic resin is a resin having a high light transmittance in the visible light region and is excellent in mechanical properties such as weather resistance, moldability, and tensile strength, and thus is suitable for an optical filter. The average molecular weight of the acrylic resin as the binder resin of the near-infrared absorbing layer of the optical filter of the present invention is preferably 500 to 600,000, more preferably 10,000 to 400,000. By setting the average molecular weight within these ranges, the properties such as transparency, weather resistance, moldability, and tensile strength described above are excellent.

  The birefringence value of the acrylic resin used in the present invention is 0 to 15 nm, preferably 0 to 10 nm, and more preferably 0 to 5 nm. The reason is that considering that the optical filter of the present invention is installed on the front surface of the display, if the birefringence value of the resin is larger than 15 nm, a double image appears and a high-definition image cannot be obtained. However, since a resin having a birefringence value of 0.1 nm or less requires extremely precise control and management at the time of production, the production cost increases.

  Birefringence is a phenomenon in which the phase of light having a polarization plane in the X-axis direction and light having a polarization plane in the Y-axis direction are shifted when light is incident on a material having an anisotropic refractive index from the Z-axis direction. Can be seen with calcite. The occurrence of birefringence leads to a double image of the image, so it can be a serious obstacle for display applications. For example, in the case of an acrylic resin composed only of methyl methacrylate, the birefringence value is 50 nm in the negative direction (a value obtained by measuring a single-pass phase difference of a He—Ne laser at a gate vicinity (5 mm) of an injection molded product, plastic Age 1999. Jan. 134-138) and birefringence is large, and a high-definition image cannot be obtained. In general, a resin has a refractive index anisotropy because the repeating unit constituting it has a certain degree of polarizability, but if the molecular chain takes the form of a random coil and the resin is in an amorphous state as a whole, birefringence is Does not occur. However, even when such a resin is subjected to a processing process that receives a shearing force, such as injection molding, the molecular chain is stretched and birefringence occurs.

The theoretical formula of the birefringence value is shown in Formula 1.
Δn = Δn _A f _A + Δn _B f _B Formula 1
(Δn _A , Δn _B : intrinsic birefringence values of resin A and resin B, f _A and f _B : degree of orientation of resin A and resin B)
The following measures can be taken in designing a resin having low birefringence. That is, (1) random copolymerization method, (2) blend method, (3) new development of low birefringence monomer resin, etc. are mentioned.

  The strategy based on the random copolymerization method (1) realizes a birefringence value of 0 to 15 nm with low birefringence by randomly copolymerizing a monomer resin having a positive birefringence value and a negative monomer resin. To do.

  Monomer resin showing negative contains (meth) acrylic acid ester such as methyl methacrylate and methyl acrylate, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, 2-vinylpyridine, vinylnaphthalene, cellulose ester, fluorene ring Compounds, and the like.

  Examples of the positive monomer resin include olefin compounds (ethylene compounds, propylene compounds), carbonate compounds, ester compounds, vinyl chloride compounds, vinyl alcohol compounds, cellulose compounds, ethylene-terephthalate compounds, ethylene. -Naphthalate compounds, sulfone compounds, ether sulfone compounds, allyl sulfone compounds, arylate compounds, imide compounds, amide-imide compounds, maleimides, norbornene compounds, trifluoroethyl methacrylate, benzyl methacrylate, Examples include phenylene oxide compounds and phenylene sulfide compounds.

  The principle based on the blending technique (2) is the same as the copolymerization method, and is a combination of polymer resins having positive and negative birefringence values.

  The strategy based on the newly developed (3) low birefringence monomer resin is that the intrinsic birefringence value has a positive correlation with the polarizability of the monomer, so that a bulky alicyclic group or aromatic ring group with a low polarizability is a molecule. This can be done by developing a monomeric resin in the structure. Furthermore, a high water vapor barrier can be achieved by incorporating a bulky alicyclic group or aromatic ring group into the molecular structure.

  By the way, as a transparent binder resin used for the near-infrared absorption layer 3, the function of suppressing deterioration of the near-infrared absorbing dye at high temperatures and high humidity is also required. Near-infrared absorbing dyes react with moisture in the atmosphere and deteriorate, but acrylic resins that are particularly preferable as the transparent binder resin used in the near-infrared absorbing layer 3 are highly transparent and many have high water absorption. This is because the acrylic resin has a feature that contains more oxygen atoms than other resins, and water molecules are adsorbed by intermolecular forces or hydrogen bonds if there are lone electron pairs with oxygen atoms. Therefore, a general acrylic resin has a low water vapor barrier property and is liable to cause pigment deterioration. Therefore, when an acrylic resin is used, it is preferable to use an acrylic resin having a substituent containing a large amount of carbon and hydrogen that does not have a lone electron pair in order to achieve a high water vapor barrier. This can be realized by incorporating a high alicyclic group or aromatic ring group into the molecular structure of the acrylic resin.

As an acrylic resin which has an alicyclic group or an aromatic ring group, the acrylic resin containing the structural unit represented by the said General formula (1) is mentioned, for example. In the general formula (1), R ¹ represents a hydrogen atom or an alkyl group, and R ² represents an alicyclic group or an aromatic ring group.

Examples of the alkyl group of the substituent R ¹ of the acrylic resin include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group.

Typical representative examples of the structural unit of the alicyclic acrylic resin when the substituent R ^{2 of the} acrylic resin is an alicyclic group include cyclopentyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, Norbornyl methacrylate, norbornyl methyl methacrylate, cyano norbornyl methacrylate, phenyl norbornyl methacrylate, isobornyl methacrylate, bornyl methacrylate, menthyl methacrylate, fentyl methacrylate, adamantyl methacrylate, dimethyl adamantyl methacrylate, Examples include tricyclodecyl methacrylate, tricyclodecyl-4-methyl methacrylate, cyclodecyl methacrylate, and the like. Moisture and heat resistance because isobornyl acid has sufficient heat resistance due to its high glass transition point (Tg) and has the property that moisture, etc., that promotes the deterioration of pigments cannot easily enter the resin layer. It is particularly preferable since it has excellent birefringence and is excellent.

Typical examples of the structural unit of the aromatic substituted acrylic resin when the substituent R ^{2 of the} acrylic resin is an aromatic ring group include benzyl methacrylate, phenyl methacrylate, naphthyl methacrylate, benzyl acrylate, acrylic Examples thereof include phenyl acid and naphthyl acrylate.

  The acrylic resin used in the present invention may be an acrylic resin monomer component having an alicyclic group or an aromatic ring group in which the above structural unit acrylic resin monomer is homopolymerized, or two or more acrylic resin monomers having the above structure. May be copolymerized. In addition, in order to suppress a decrease in mechanical strength such as bending fracture strength, the acrylic resin used in the present invention may be copolymerized with other monomer components in which the structural unit is other than the structural unit.

  Such other copolymerizable monomer component is not particularly limited as long as it does not impair the transparency, birefringence, heat resistance and low hygroscopicity of the optical polymer. , Methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, pentyl acrylate, n-hexyl acrylate, acrylic Acrylic acid esters such as 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, octadecyl acrylate, butoxyethyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, ethyl methacrylate, n-methacrylate Propyl, i-propyl methacrylate, n-butyl methacrylate, methacrylic acid -Butyl, t-butyl methacrylate, pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, butoxyethyl methacrylate, glycidyl methacrylate, methacrylic acid Methacrylic acid esters such as 2-hydroxyethyl, 4-vinylpyridine, 2-vinylpyridine, α-methylstyrene, α-ethylstyrene, α-fluorostyrene, α-chlorostyrene, α-bromostyrene, fluorostyrene, Aromatic vinyl compounds such as chlorostyrene, bromostyrene, methylstyrene, methoxystyrene, styrene, acrylamide, methacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-dimethylmeta (Meth) acrylamides such as rilamide, N-diethylmethacrylamide, calcium acrylate, barium acrylate, lead acrylate, tin acrylate, zinc acrylate, calcium methacrylate, barium methacrylate, lead methacrylate, methacrylic acid Examples include (meth) acrylic acid metal salts such as tin and zinc methacrylate, unsaturated fatty acids such as acrylic acid and methacrylic acid, and vinyl cyanide compounds such as acrylonitrile and methacrylonitrile alone or in combination of two or more. It is done.

  Among them, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, methacrylic acid, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, 4-vinylpyridine, Acrylamide or the like is preferable, and methyl methacrylate is easily dissolved in an organic solvent and is a readily available resin, and is particularly preferable in terms of imparting flexibility to the resin.

  In addition, when copolymerizing other resin monomer components with an acrylic resin monomer component having an alicyclic group or aromatic ring group that exhibits a low birefringence value, the birefringence value of the other resin monomer component to be copolymerized is set. It is more preferable to further copolymerize components that cancel.

  For example, methyl methacrylate has a negative birefringence value. Therefore, when methyl methacrylate is copolymerized with an acrylic resin monomer component having an alicyclic group or an aromatic ring group, it has a positive birefringence value. Further, benzyl methacrylate may be further copolymerized.

  In the present invention, the amount of each monomer component is preferably 5 to 100 parts by weight, more preferably (meth) acrylic resin monomer component having an alicyclic group or aromatic ring group, based on the total amount of monomer component (100 parts by weight). 5 to 95, still more preferably 10 to 70 parts by weight, most preferably 20 to 40 parts by weight, while being copolymerizable with the (meth) acrylic resin component having the alicyclic group or aromatic ring group Preferably (meth) acrylic resin monomer components other than those described above are used in an amount of 95 to 0 parts by mass, more preferably 95 to 5 parts by mass, still more preferably 90 to 30 parts by mass, and most preferably 80 to 60 parts by mass. The near-infrared of the optical filter of the present invention is obtained by copolymerizing both monomers, or polymerizing a monomer component having a alicyclic group or an aromatic ring group alone. Acrylic resin used for the absorption layer can be produced.

  The reason why the amount of the (meth) acrylic resin monomer having an alicyclic group or an aromatic ring group is preferably 5 to 100 parts by mass with respect to 100 parts by mass of the total amount of the monomer components is that the amount is 5 parts by mass. This is because if the ratio is less than 2, birefringence may increase or hygroscopicity may increase. When the blending amount of the (meth) acrylic resin monomer having an alicyclic group or aromatic ring group exceeds 95 parts by mass, mechanical strength such as bending fracture strength may be lowered.

  On the other hand, the blending amount of the (meth) acrylic resin monomer other than the above that can be copolymerized with the (meth) acrylic resin monomer having an alicyclic group or an aromatic ring group is 95 to 0 with respect to 100 parts by mass of the total amount of the monomer components. The reason why it is preferable to use a part by mass is that when the amount exceeds 95 parts by mass, the heat resistance may be lowered or the birefringence may be increased. If the copolymerizable monomer is not blended at all, it may be difficult to adjust heat resistance and hygroscopicity.

  Any of the existing methods such as bulk polymerization, suspension polymerization, and solution polymerization can be applied as the polymerization method used for producing the acrylic resin used in the optical filter of the present invention. In particular, it is preferable to employ a suspension polymerization method or a bulk polymerization method from the viewpoints of the transparency of the resin and ease of handling.

  When the suspension polymerization method is employed, since the polymerization is carried out in an aqueous medium, it is preferable to add a suspending agent and, if necessary, a suspending aid. Examples of such a suspending agent include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and polyacrylamide, and poorly soluble inorganic substances such as calcium phosphate and magnesium pyrophosphate. The amount of the suspending agent is not particularly limited. Specifically, when a water-soluble polymer is used, it is 0.03 to 1% by mass with respect to the total amount of the monomer component. In the case where a hardly soluble inorganic substance is used, it is preferably 0.05 to 0.5% by mass with respect to the total amount of the monomer components. Moreover, when using a hardly soluble inorganic substance as a suspending agent, it is more preferable to use a suspending aid. Examples of such a suspension aid include an anionic surfactant such as sodium dodecylbenzenesulfonate. The amount of the suspension aid used is not particularly limited, but is preferably 0.001 to 0.02 mass% with respect to the total amount of the monomer components.

  When performing polymerization, it is preferable to use a radical polymerization initiator. Examples of such radical polymerization initiators include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxide. Organic peroxides such as oxy-3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone Used for normal radical polymerization such as 1-carbonitrile, azo compounds such as azodibenzoyl, water-soluble catalysts such as potassium persulfate and ammonium persulfate, redox catalysts based on a combination of peroxides or persulfates and reducing agents Anything that can be used can be used.

  The amount of the polymerization initiator used is not particularly limited, but specifically, it is preferably 0.01 to 10% by mass with respect to the total amount of the monomer components. This is because when the amount of the polymerization initiator used is less than 0.01% by mass, the reactivity may decrease, or the molecular weight of the resulting optical polymer may become excessively large. Moreover, it is because a polymerization initiator will remain when the usage-amount of a polymerization initiator exceeds 10 mass%, and optical characteristics may be reduced.

  As the molecular weight modifier, it is also preferable to use a mercaptan compound, thioglycol, carbon tetrachloride, α-methylstyrene dimer or the like in combination with a quinone compound or a phosphorus compound. Thus, by adding a conventional molecular weight regulator, it becomes easier to adjust the molecular weight to a value within a predetermined range. It is also preferable to use various organic solvents so that the monomer components can be uniformly polymerized.

  Regarding the polymerization conditions, the polymerization temperature is preferably 0 to 200 ° C. The reason for this is that when the polymerization temperature is less than 0 ° C., the reactivity is significantly reduced and the polymerization time may be prolonged. On the other hand, when the polymerization temperature exceeds 200 ° C., it is difficult to control the reaction. This is because there is a case of becoming. The polymerization temperature is preferably 40 to 150 ° C, more preferably 50 to 100 ° C. The polymerization time depends on the polymerization temperature. When the polymerization temperature is 0 to 200 ° C., it is preferably 1 to 48 hours, more preferably 2 to 24 hours, and 3 to 12 hours. More preferably.

  By introducing the alicyclic structure into the resin, the effect of increasing the glass transition temperature of the resin can also be obtained.

  In the present invention, when the near-infrared absorbing layer 3 contains a near-infrared absorbing dye having a counter ion, the acrylic resin has a hydroxyl group or an acid group, or polymerization starts in the acrylic resin. In the case where an agent or the like is blended, the equilibrium state between the mother skeleton of the near-infrared absorbing dye and the counter ion is disrupted by the hydroxyl group, acid group, polymerization initiator, or the like, and the function of near-infrared absorption can be achieved. Since it may be difficult, for the purpose of eliminating this, it is preferable to use an acrylic resin having a low hydroxyl value or an acid value, and more preferably a resin having a low hydroxyl value or an acid value. . The near-infrared absorbing dye having a counter ion is a diimonium compound, a nickel complex, a dithiol complex, an aminium compound, a cyanine compound, a pyrylium compound, or the like.

  For the above reasons, the hydroxyl value is preferably 10 or less, more preferably 5 or less, and particularly preferably 0. By reducing the hydroxyl value in this way, the near-infrared absorbing layer contains, for example, the near-infrared absorbing dye having a counter ion can be prevented from reacting with the hydroxyl group of the acrylic resin. An optical filter whose function is stable over time even under high temperature and high humidity can be obtained, and the range of selection of near-infrared absorbing dyes can be expanded. Here, the hydroxyl value means the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated.

  Similarly, the acid value is preferably 10 or less, more preferably 5 or less, and particularly preferably 0. By reducing the acid value in this way, it is possible to prevent the near-infrared absorbing dye from reacting with the acid contained in the acrylic resin, so that the near-infrared absorbing function is stable over time even under high temperature and high humidity. It can be an optical filter. Here, the acid value refers to the number of mg of potassium hydroxide required to neutralize 1 g of the sample.

  Moreover, as an acrylic resin, it is preferable that the glass transition temperature (it may be called Tg hereafter) is more than the temperature when the optical filter 1 is actually used. If the glass transition temperature is below the temperature at which the optical filter 1 is actually used, in other words, if the optical filter 1 is used above the glass transition temperature, the near infrared absorbing dyes contained in the acrylic resin This is because a reaction occurs and the acrylic resin absorbs moisture in the air, so that the near-infrared absorbing dye and the acrylic resin easily deteriorate.

  From the above viewpoint, the glass transition temperature of the acrylic resin is preferably, for example, 80 ° C. to 150 ° C., although it depends on the temperature value when the optical filter 1 is actually used. When an acrylic resin having a glass transition temperature of less than 80 ° C. is used, an interaction between the near-infrared absorbing dye and the acrylic resin, an interaction between the near-infrared absorbing dyes, or the like occurs, and the near-infrared absorbing dye is modified. When an acrylic resin having a glass transition temperature exceeding 150 ° C. is used, a composition for forming a near infrared absorption layer is prepared by dissolving such an acrylic resin in a solvent, and the near infrared absorption layer 3 is formed by coating. In addition, since it is necessary to increase the drying temperature in order to perform sufficient drying, when using a near-infrared absorbing dye having low heat resistance, the near-infrared absorbing dye is liable to deteriorate. If the drying temperature is lowered, a long drying time is required, so that the efficiency of the drying process is reduced, the production cost is increased, or the solvent that remains because the drying cannot be sufficiently performed is a near infrared absorbing dye. It may also cause deterioration of.

  A preferable blending ratio of the near infrared absorbing dye and the acrylic resin in the near infrared absorbing layer 3 is near infrared absorbing dye 0.001 to 100 with respect to the acrylic resin 100, and more preferably near infrared absorbing dye 0.01. It is -50, Most preferably, it is 0.1-10. In addition, a compounding ratio is a mass reference | standard.

  The near-infrared absorbing layer 3 is formed by adding a near-infrared-absorbing dye and an acrylic resin together with other additives as necessary, adding and mixing a solvent and / or a diluent, and dissolving or dispersing each component. The composition for forming an infrared absorbing layer is prepared, and the obtained composition for forming a near infrared absorbing layer is applied to a coating target. Or it can also carry out by apply | coating to the application | coating object, melt-extruding the composition melt-kneaded with the additive which adds a near-infrared absorption pigment | dye and an acrylic resin as needed.

  As said additive, in order to improve the durability of a near-infrared absorption layer, antioxidant, a ultraviolet absorber, etc. can be used, and as antioxidant, phenol type, amine type, hindered phenol, etc. , Hindered amine, sulfur, phosphoric acid, phosphorous acid, or metal complex, and ultraviolet absorbers include benzophenone or benzotriazole.

  Solvents used in preparing the above composition for forming a near infrared absorption layer include acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, benzene, toluene, xylene, methanol, ethanol from the viewpoint of dye solubility. , Isopropanol, chloroform, tetrahydrofuran, N, N-dimethylformamide, acetonitrile, trifluoropropanol, n-hexane, n-heptane, water, and the like may be mentioned, but other materials may be used.

  In addition, the above-mentioned composition for forming a near-infrared absorbing layer may be applied by Meyer bar coating, doctor blade coating, gravure coating, gravure reverse coating, kiss reverse coating, three-roll reverse coating, slit reverse die coating, die Various coating methods such as coating or comma coating can be used.

Transparent substrate:
The transparent substrate 2 is a layer to be laminated with the near-infrared absorbing layer 3 and various additional layers, or is a support for the optical filter 1. Accordingly, the transparent substrate 2 is transparent to visible light, and the type thereof is not particularly limited as long as the near infrared absorption layer 3 and other various layers can be laminated. It is more preferable if the birefringence is small.

  For example, the transparent substrate 2 includes polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefins such as cyclic polyolefin, polyethylene, polypropylene, and polystyrene, and vinyl-based materials such as polyvinyl chloride and polyvinylidene chloride. Examples include films made of resins such as resin, polycarbonate, acrylic resin, triacetyl cellulose (TAC), polyethersulfone, or polyetherketone, and used alone or in layers of the same or different types. Can do.

  As transparency of the transparent base material 2, when the transparent base material 2 is a single layer, it is preferable that the light transmittance of a visible region is 80% or more. Moreover, although having transparency is preferably colorless and transparent, it is not necessarily limited to being colorless and transparent, and may be colored and transparent as long as the object of the present invention is not hindered. Good. The light transmittance in the visible region is preferably as high as possible. However, since the final product requires a light transmittance of 50% or more, even when at least two sheets are laminated, each transparent substrate 2 has a light transmittance. A rate of 80% is suitable for the purpose. Of course, the higher the light transmittance, the more transparent substrate 2 can be laminated, so the light transmittance of a single layer of the transparent substrate 2 is more preferably 85% or more, most preferably 90% or more. is there. Reducing the thickness is also an effective means for improving the light transmittance.

  The thickness of the transparent substrate 2 is not particularly limited as long as the transparency is satisfied, but is preferably in the range of about 12 μm to about 300 μm from the viewpoint of workability. When the thickness is less than 12 μm, the transparent substrate 2 is too flexible, and stretch and wrinkles are likely to occur due to the tension during processing. In addition, when the thickness exceeds 300 μm, the flexibility of the film decreases, and continuous winding in each step becomes difficult, and the workability when laminating a plurality of transparent base materials 2 is greatly inferior. There is also a problem.

Electromagnetic wave shielding layer:
The electromagnetic wave shielding layer that can be added to the near-infrared absorbing laminate 4 shields electromagnetic waves generated from an electrical or electronic device to which the optical filter 1 is applied, particularly the plasma display 6. As the electromagnetic wave shielding layer, a metal mesh layer and a transparent conductive thin film layer are used, and a metal mesh having high electromagnetic wave shielding properties is preferable. Since the metal mesh layer is formed by laminating a metal foil on a transparent base material and forming a mesh shape by etching, an adhesive layer is usually interposed between the transparent base material 2 and the metal mesh. Adhesive layer is acrylic resin, polyester resin, polyurethane resin, polyvinyl alcohol alone or partially saponified product thereof, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyimide resin, epoxy resin, polyurethane ester resin It consists of adhesives such as. The metal mesh layer is not particularly limited as long as it has electromagnetic wave shielding ability. For example, copper, iron, nickel, chromium, aluminum, gold, silver, stainless steel, tungsten, chromium, Titanium or the like can be used, among which copper is preferable, and examples of the copper foil include a rolled copper foil and an electrolytic copper foil, and an electrolytic copper foil is particularly preferable. By selecting the electrolytic copper foil, the thickness can be improved to 10 μm or less, and the adhesion with chromium oxide or the like can be improved when blackened. Because it can.

  Here, in the present invention, it is preferable that one side or both sides of the metal mesh is blackened. The blackening process is a process of blackening the surface of the metal mesh with chromium oxide or the like. In the optical filter, the oxidation-treated surface is arranged to be a surface on the viewer side. The external light on the surface of the optical filter is absorbed by chromium oxide or the like formed on the surface of the metal mesh layer by this blackening treatment, so that it is possible to prevent light from being scattered on the surface of the optical filter and to achieve good transmission. Therefore, the optical filter can be obtained.

  The aperture ratio of the metal mesh layer is preferably as low as possible from the viewpoint of electromagnetic wave shielding ability. However, since the light transmittance decreases as the aperture ratio decreases, the aperture ratio is preferably 50% or more.

  When the metal mesh layer is laminated, the opening portion and the non-opening portion of the metal mesh layer are uneven, so that the transparent resin is formed on the metal mesh layer with a thickness greater than or equal to the thickness of the metal mesh layer. A planarization layer may be stacked.

Antifouling layer:
When using the optical filter 1, the antifouling layer that can be added to the near-infrared-absorbing laminate 4 prevents dirt or contaminants from adhering to the surface due to inadvertent contact or environmental contamination. It is a layer that is formed to prevent or remove even if attached. For example, a fluorine-based coating agent, a silicon-based coating agent, a silicon / fluorine-based coating agent, or the like is used, and among these, a silicon / fluorine-based coating agent is preferably applied. The thickness of these antifouling layers is preferably 100 nm or less, more preferably 10 nm or less, and further preferably 5 nm or less. When the thickness of these antifouling layers exceeds 100 nm, the initial value of antifouling property is excellent, but the durability is inferior. 5 nm or less is the most preferable from the balance of antifouling property and its durability.

Adhesive layer:
The pressure-sensitive adhesive layer used in the present invention is a layer made of any transparent pressure-sensitive adhesive. As long as the light transmittance in the visible region is high, the type and the like are not particularly limited. Specifically, the acrylic adhesive, the silicon adhesive, the urethane adhesive, the polyvinyl butyral adhesive, and the polyvinyl ether. -Based adhesives, ethylene-vinyl acetate adhesives, and the like.

Antireflection layer:
The antireflection layer that can be added to the near-infrared absorbing laminate 4 is typically one in which a high-refractive index layer and a low-refractive index layer are sequentially laminated, but there are also those having other laminated structures. The high refractive index layer is, for example, a thin film of ZnO or TiO ₂ material, or a transparent resin film in which fine particles of these materials are dispersed. Further, the low refractive index layer, a thin film made of SiO ₂ or SiO ₂ gel film or a fluorine-containing, or a transparent resin film of fluorine and silicon-containing. Since the antireflection layer is laminated, it is possible to reduce reflection of unnecessary light such as external light on the laminated side, and to increase the contrast of the image or video of the applied display.

Antiglare layer:
Examples of the antiglare layer that can be added to the near-infrared absorbing laminate 4 include those in which beads such as polystyrene resin and acrylic resin having a diameter of about several μm are dispersed in a transparent resin. This is for preventing scintillation occurring at a specific position and direction of the display when it is arranged on the front of the display.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Note that the present invention is not limited by these descriptions.

A diimmonium-based near-infrared absorbing dye represented by the general formula (2) and having a counter ion (X ⁻ ) as a monovalent anion “bistrifluoromethanesulfonylimido ion” was synthesized as follows. In the examples, “parts” means “parts by mass” unless otherwise specified.

  In 30 parts of DMF, 3.8 parts of N, N, N ′, N′-tetrakis (aminophenyl) -p-phenylenediamine, 21 parts of n-butyl bromide, and 15 parts of potassium carbonate were added, and the mixture was heated at 80 ° C. for 1 hour. The reaction was carried out at 90 ° C. for 7 hours and at 130 ° C. for 1 hour. After cooling, the mixture was filtered, 30 parts of isopropanol was added to the reaction solution (filtrate), and the mixture was stirred at 5 ° C. or lower for 1 hour. The produced crystals were washed with methanol and dried to obtain 2.5 parts of light brown crystals.

  1 part of the compound synthesized above was added to 10 parts of DMF and heated and dissolved at 60 ° C. Then, 0.78 part of silver bistrifluoromethanesulfonylimido dissolved in 10 parts of DMF was added and reacted for 30 minutes. After cooling, the precipitated silver was filtered off. To this reaction liquid (filtrate), 10 parts of water was slowly added dropwise, followed by stirring for 15 minutes. The produced black crystals were filtered, washed with 50 parts of water, and the resulting cake was dried to obtain 0.5 parts of the compound of the general formula (2). The results of measurement of λmax, molecular extinction coefficient, and melting point of the compound are shown below.

λmax 1076nm (dichloromethane)
Molecular extinction coefficient 101,000
Melting point 186.5 ° C. (DSC)

Copolymer acrylic resin (trade name: Optrez oz1330, manufactured by Hitachi Chemical Co., Ltd.) comprising tricyclodecyl methacrylate represented by the above general formula (1), methyl methacrylate, and benzyl methacrylate as a transparent binder resin. , Tg: 110 ° C., hydroxyl value: 0, acid value: 0, birefringence value: 4 nm) prepared in the above step in a resin solution in which the solid content ratio is 20% (mass basis) in methyl ethyl ketone. Diimonium-based near-infrared absorbing dye 0.2 g / m ² whose counter ion (X ⁻ ) is bistrifluoromethanesulfonylimido ion, and phthalocyanine-based near-infrared absorbing dye (manufactured by Nippon Shokubai Co., Ltd., trade name: “IR”) -1 ") Using a coating solution obtained by adding two types of near-infrared absorbing pigments of 0.1 g / m ² and sufficiently dispersing them, a thickness of 100 μm was used. On a polyethylene terephthalate resin film (product name: “A4300”, manufactured by Toyobo Co., Ltd.), it was applied with a Meyer bar to a dry film thickness of 5 μm, and in an oven where dry air with a wind speed of 5 m / sec was applied. It dried at 100 degreeC for 1 minute, the near-infrared absorption layer was formed, and the near-infrared absorption filter was obtained.

A near-infrared absorbing filter was obtained in the same manner as in Example 1 except that only the diimmonium-based near-infrared absorbing dye 0.2 g / m ² synthesized in Example 1 was used as the near-infrared absorbing dye.

Copolymer acrylic resin of isobornyl methacrylate represented by the above general formula (1) and methyl methacrylate and benzyl methacrylate (Tg: 130 ° C., hydroxyl value: 0, acid value: 0, birefringence) as transparent binder resin (Value: 9 nm) A near-infrared absorption filter was obtained in the same manner as in Example 1 except that it was used.

  Copolymer acrylic resin of isobornyl methacrylate represented by the general formula (1) and methyl methacrylate and phenyl methacrylate (Tg: 105 ° C., hydroxyl value: 0, acid value: 0, birefringence as transparent binder resin (Value: 13 nm) A near-infrared absorption filter was obtained in the same manner as in Example 1 except that it was used.

  On the near infrared absorption layer side of the near infrared absorption filter obtained in Example 1, a fluorine-based silane compound (trade name “KP801M”, manufacturer name “Shin-Etsu Chemical Co., Ltd.”) which is a silicon / fluorine antifouling agent )) Was applied and dried and cured to a thickness of 3.0 nm to form an antifouling layer to obtain a near infrared absorbing film with an antifouling layer.

  An acrylic adhesive (trade name “AS2140”) diluted with a solvent so that the solid content is 20% on the release surface of the release film (trade name “E7002”, manufacturing company name “Toyobo Co., Ltd.”) (Manufacturer's name “One Company Oil & Fat Co., Ltd.”) was applied with a doctor blade so that the dry film thickness was 25 μm, and dried at 100 ° C. for 1 minute in an oven hit with dry air with a wind speed of 5 m / sec. The pressure-sensitive adhesive film obtained by forming the pressure-sensitive adhesive layer was such that the pressure-sensitive adhesive layer was in contact with the near-infrared absorbing layer side of the near-infrared absorbing filter obtained in Example 1, and the roller temperature: 23 ° C., linear pressure: 0. Bonding was performed using a 035 kg / cm laminating roller to obtain a near-infrared absorbing filter with an adhesive layer.

On the near-infrared absorbing layer side of the near-infrared absorbing filter obtained in Example 1, a SiO ₁ N ₁ film as the first inorganic optical thin film, and then a thin film made of indium tin oxide compound (ITO), Sputtering a Ta ₂ O ₅ film and an SiO ₂ film as the outermost film, the respective film thicknesses are 23 nm for the SiO ₁ N ₁ film, 60 nm for the ITO film, 53 nm for the Ta ₂ O ₅ film, A SiO ₂ film was formed to a thickness of 90 nm, an antireflection layer was formed, and a near infrared absorption filter with an antireflection layer was obtained.

  A mixture of acrylic resin particles (manufactured by Nemoto Kogyo Co., Ltd., trade name: “Art Pearl”) dispersed in dipentaerythritol hexaacrylate on the near infrared absorption layer side of the near infrared absorption filter obtained in Example 1 above. The solution was applied and dried and cured with a Meyer bar so that the dry film thickness was 4 μm to form an antiglare layer, and a near-infrared absorbing filter with an antiglare layer was obtained.

  Copper foil (manufactured by Furukawa Circuit Foil Co., Ltd., trade name: one surface of a polyethylene terephthalate resin film (trade name: “A4300”, manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm is blackened by chromate treatment EXP-WS (thickness 9μ) is dry-laminated with a urethane adhesive and pasted together. After applying a resist on the copper foil, exposure and development are performed to remove unnecessary copper foil portions by etching. Then, an electromagnetic wave shielding layer having a metal mesh of 300 μm □ and a line width of 10 μm was formed. On this metal mesh, the near-infrared absorbing dye-containing coating solution used in Example 1 was applied with a Meyer bar so that the dry film thickness was 5 μm, and 100 ° C. in an oven to which dry air with a wind speed of 5 m / sec was applied. A near infrared absorption layer was formed by drying at 1 ° C. for 1 minute to obtain a near infrared absorption filter with an electromagnetic wave shielding function.

[Comparative Example 1]
Except that polymethyl methacrylate (manufactured by Mitsubishi Rayon Co., Ltd., trade name: BR-60, Tg: 75 ° C., hydroxyl value: 0, acid value: 1, birefringence value: 50 nm) was used as the transparent binder resin. This was carried out in the same manner as in Example 1 to obtain a near infrared absorption filter.

[Comparative Example 2]
A near-infrared absorption filter was obtained in the same manner as in Example 1 except that a polyester resin (Tg: 110 ° C., acid value: 26, hydroxyl value: 19, birefringence value: 20 nm) was used as the transparent binder resin. .

(Evaluation method)
About each near-infrared absorption filter obtained in Examples 1 to 9 and Comparative Examples 1 and 2 immediately after production and in a constant temperature and humidity chamber at 60 ° C. and 90% for 1000 hours. The results of measurement for each item of transparency (haze), luminous transmittance, and near-infrared transmittance after the measurement are shown in “Table 1” and “Table 2” below.

  The above items and the other items in the following “Table 1” and “Table 2” were measured under the following measurement conditions.

  Transparency (haze): Using a color computer (manufactured by Suga Test Instruments Co., Ltd., trade name: “SM-C”), a test piece having a size of 50 mm × 50 mm cut out from each near infrared absorption filter was obtained. .

  Luminous transmittance, near infrared region transmittance: Using a spectrophotometer (manufactured by Shimadzu Corporation, trade name: “UV-3100PC”), a size of 50 mm × 50 mm cut out from each near infrared absorption filter It measured about the test piece.

  Image quality: An optical filter was placed in front of the plasma display and confirmed visually.

  Birefringence value: A value obtained by measuring a single-pass phase difference of a He—Ne laser at a gate vicinity (5 mm) of an injection molded product, plastic age 1999. Jan. See pages 134-138

In the items of “Table 1” and “Table 2”, the unit of the added amount of the dye is g / m ² , the unit of birefringence is nm, the unit of acid value and hydroxyl value is mgKOH / g, The NIR transmittance after the wet heat resistance test indicates the maximum light transmittance in the near infrared region (wavelength: 800 nm to 1100 nm).

  As shown in the above “Table 1” and “Table 2”, the optical filters of Examples 1 to 9 are any of haze, luminous transmittance, near infrared region transmittance, and image quality immediately after manufacture. After production, it is maintained almost unchanged even after being exposed to an environment of temperature: 60 ° C. and humidity: 90% for 1000 hours, and thus has practically sufficient moisture and heat resistance. I understand. On the other hand, since the optical filters of Comparative Examples 1 and 2 have a large birefringence value, double reflection of an image occurs when the optical filter is arranged on the front surface of the plasma display. Further, Comparative Example 1 and Comparative Example 2, the Tg and / or acid value / hydroxyl value of the transparent binder resin is out of the predetermined range, so that the haze, luminous transmittance, and near-infrared region transmittance temperature are poor immediately after production, and the temperature is 60 ° C. and humidity is 90%. After 1000 hours exposure in the environment, these properties are further deteriorated. Therefore, it can be said that the optical filters of Comparative Example 1 and Comparative Example 2 have practical problems.

  When the optical filter of the present invention is arranged on the front surface of the display, the double reflection of the image is suppressed and a high-definition image quality can be obtained. Therefore, the optical filter of the present invention is suitably applied to a display, particularly a plasma display. .

It is a schematic sectional drawing which shows an example of the optical filter of this invention. It is a figure of the plasma display which has arrange | positioned the optical filter of this invention in the front surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B Optical filter 2 Transparent base material 3 Near-infrared absorption layer 4 Near-infrared absorption laminated body 5 Functional layer 6 PDP

Claims (16)

  An optical filter having a laminated structure in which a near-infrared absorbing layer containing at least a transparent substrate and a near-infrared absorbing dye that absorbs near-infrared in an acrylic resin is laminated, wherein the birefringence value of the acrylic resin is 0 to 0 An optical filter characterized by being 15 nm.   The optical filter according to claim 1, wherein the acrylic resin is produced by randomly copolymerizing two or more kinds of acrylic resin monomer components. When the acrylic resin is 100 parts by mass of the total amount of monomer components,
(1) 5 to 100 parts by mass of an acrylic resin monomer component having an alicyclic group or an aromatic ring group,
(2) 95-0 parts by mass of a monomer component other than an acrylic resin having the alicyclic group or aromatic ring group,
The optical filter filter according to claim 1, wherein the filter is a copolymer or a homopolymer. The acrylic resin is
(1) methyl methacrylate;
(2) Coordination with one or more of (meth) acrylic acid compounds capable of canceling the negative birefringence value of the methyl methacrylate and making the copolymer birefringence value 0-15 nm. The optical filter according to claim 1, wherein the optical filter is a polymerized acrylic resin. The acrylic resin is
(1) methyl methacrylate;
(2) The optical filter according to claim 1 or 2, which is a copolymerized acrylic resin with one or more compounds represented by the following general formula (1).

(In the general formula (1), R ¹ represents a hydrogen atom or an alkyl group, and R ² represents an alicyclic group or an aromatic ring group.)   The optical filter according to claim 1, wherein the acrylic resin has a hydroxyl value of 10 or less.   The optical value according to any one of claims 1 to 6, wherein the acrylic resin has an acid value of 10 or less.   The optical filter according to any one of claims 1 to 7, wherein the acrylic resin has a glass transition temperature of 80C to 150C. The optical filter according to claim 1, wherein the near-infrared absorbing dye is a diimmonium compound represented by the following general formula (2).


(In the general formula (2), R is the same or different hydrogen, alkyl group, aryl group, hydroxyl group, phenyl group, or halogenated alkyl group, X is a monovalent or divalent anion, n Is 1 or 1/2.)   The optical filter according to claim 9, wherein X in the general formula (2) is a bistrifluoromethanesulfonylimidate ion.   The optical filter according to any one of claims 1 to 10, wherein the optical filter includes an electromagnetic wave shielding layer.   The optical filter according to claim 1, wherein the optical filter includes an antifouling layer.   The optical filter according to claim 1, wherein the optical filter includes an adhesive layer.   The optical filter according to any one of claims 1 to 13, wherein the optical filter includes an antireflection layer.   The said optical filter is provided with the glare-proof layer, The 1 optical filter of any one of Claims 1-14 characterized by the above-mentioned.   A display, wherein the optical filter according to any one of claims 1 to 15 is disposed on an observation side of the display.