JP2001264532A - Infrared ray absorbing filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared ray absorbing filter having a steep absorption in a near-infrared ray region, a high absorption index and a wide absorption width in the near-infrared ray region and high light transmissivity in a visible ray region and excellent in environmental stability, workability and productivity. SOLUTION: The infrared ray absorbing filter formed by laminating an infrared ray absorbing layer having an infrared ray absorbing dye and a polymer resin adopted as main components on a transparent base material is characterized in that at least a diimonium salt compound is contained as the infrared ray absorbing dye and the polymer resin is a polyester resin formed by co- polymerization with >=60 mol% specified aromatic diol component and has 85-130 deg.C glass transition temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter.
The present invention relates to an optical filter that efficiently blocks near-infrared rays from 0 nm to 1200 nm, and is suitable for blocking infrared rays emitted from the front surface of a plasma display (hereinafter abbreviated as PDP).

[0002]

2. Description of the Related Art Conventionally, the following filters have been widely used as heat ray absorption filters, filters for correcting the visibility of a video camera, and the like. Filters containing phosphoric acid-based glass containing metal ions such as copper and iron (JP-A-60-235740, JP-A-62-153144, etc.). Interlayer filters having different refractive indices laminated on a substrate and transmitting a specific wavelength by interfering transmitted light (Japanese Patent Application Laid-Open Nos. 55-21091 and 59-18474).
No. 5 publication). Acrylic resin filters containing copper ions in the copolymer (JP-A-6-324213). Filters having a structure in which a dye is dispersed in a binder resin (JP-A-57-21458, JP-A-57-198)
413, JP-A-60-43605, JP-A-9-888855, JP-A-11-116826, and the like.

[0003]

However, the above-mentioned infrared absorption filters have the following problems.

[0004] In the above-mentioned method, the absorption is sharp in the near-infrared region and the infrared cutoff rate is very good, but a part of red in the visible region is also largely absorbed, and the transmitted color appears blue. In display applications, color balance is emphasized, and in such a case, it is difficult to use. Also,
Since it is glass, it has a problem in workability.

In the case of the above-mentioned method, the optical characteristics can be freely designed, and it is possible to manufacture a filter substantially equivalent to the designed one. However, on the other hand, there is a disadvantage that the number of layers having a refractive index difference needs to be very large, and the production cost increases. In addition, when a large area is required, it is difficult to manufacture because a highly accurate film thickness uniformity is required over the entire area.

In the case of the above method, the workability of the above method is improved. However, although there is a steep absorption characteristic as in the case of the above method, the problem that the red portion also absorbs and the filter looks blue remains unchanged.

In the above-mentioned method, as an infrared absorbing dye,
Many dyes such as phthalocyanine, nickel complex, azo compound, polymethine, diphenylmethane, triphenylmethane, and quinone are used. However, many of them have problems such as insufficient absorption and absorption of a specific wavelength in the visible region.

In recent years, PDPs which have been developed as thin and large-screen displays have a problem in that near infrared rays emitted from the front face may cause malfunctions of a remote controller or the like. Installation is required. However, even in the infrared cutoff filter for PDP, at present, the infrared absorption filter described above has not reached a sufficient demand.

However, when a diimmonium salt-based compound is used as the infrared absorbing dye in the above-mentioned method, the above problems can be overcome, and the requirement that the absorption in the near infrared region is large and the absorption in the visible region is small is satisfied. Filter can be obtained. Furthermore, performance suitable as an infrared absorption filter for PDP can be obtained.

However, if a filter using a diimonium salt compound is left for a long time at a high temperature or under humidification, there is a problem that the absorption becomes small or a specific absorption appears in the visible region and the color changes to yellow-green. is there. As a countermeasure, it has been proposed to use a polyester resin having a suitably high glass transition temperature. For example, Tokuhei 9-
JP-A-838855 and JP-A-11-116826 exemplify a mixture of a polyester resin obtained by copolymerizing a specific aromatic diol in an amount of 10 mol% or more and an infrared absorbing dye. However, in the composition range using the aromatic diol, on the contrary, the glass transition temperature becomes too high, so that when the copolymerized polyester resin is mixed with a near-infrared absorbing dye and a solvent and coated on a base film, it is dried. There are problems that it takes time, the environmental stability is deteriorated due to the residual solvent due to insufficient drying, and the film curls after coating and drying. Furthermore, some of the above-mentioned copolymerized polyester resins have low solubility in a solvent and do not withstand coating suitability.

An object of the present invention is to have a steep absorption in the near-infrared region, a large absorption rate and absorption width in the near-infrared region, a high light transmittance in the visible region, and furthermore, environmental stability, workability, and the like. An object of the present invention is to provide an infrared absorbing filter having good productivity.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and an infrared absorbing filter which can solve the above problems is as follows.

[0013] The first invention of the present invention is an infrared absorption filter comprising an infrared absorbing layer mainly composed of an infrared absorbing dye and a polymer resin laminated on a transparent substrate, wherein at least a diimmonium salt is used as the infrared absorbing dye. A polyester resin containing a compound, wherein the polymer resin is obtained by copolymerizing the alicyclic diol component represented by the general formula (1) by 60 mol% or more, and has a glass transition temperature of 85 to 130 ° C.
An infrared absorption filter characterized by the following.

[0014]

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(Wherein, R ₁ and R ₂ represent a hydroxyl group and / or a hydroxyalkylene group having 1 to 8 carbon atoms and / or a hydroxyalkylene group having 1 to 4 carbon atoms to which 1 to 10 mol% of alkylenoxide is added) Shown.)

According to a second aspect, there is provided an infrared absorption filter, wherein the diimmonium salt compound according to the first aspect has a structure represented by the general formula (2).

[0017]

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[0018] (wherein, R ₁ to R ₈ is a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an aralkyl group, an alkynyl group, even each identical or different may .R ₉ also be ~ R ₁₂ is a hydrogen atom, a halogen atom, an amino group, an amido group, a cyano group, a nitro group, a carboxyl group, an alkyl group, even each same, in which may be different .R ₁ to R ₁₂ you can bind a substituent which may have a substituent .X ^- represents an anion).

A third invention is the infrared absorption filter according to the first or second invention, wherein at least one of a phthalocyanine compound and a nickel complex compound is used as the infrared absorbing dye.

A fourth invention is an infrared absorption filter, wherein the phthalocyanine compound according to the third invention is a fluorinated phthalocyanine compound.

A fifth aspect of the present invention is the infrared absorbing filter according to the third or fourth aspect, wherein the nickel complex compound has a structure represented by the following general formula (3).

[0022]

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(In the formula, R _{1 to} R ₄ represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, and an amino group.)

According to a sixth aspect of the present invention, the mixing ratio of the infrared-absorbing dye in the infrared-absorbing layer is from 0.5 to 0.0 of the phthalocyanine compound with respect to 1.0 part by weight of the diimmonium salt compound.
The infrared absorbing filter according to any one of claims 3 to 5, wherein the amount is 1.0 to 0.0 parts by weight of the nickel complex compound.

The seventh invention is the infrared absorption filter according to any one of the first to sixth inventions, wherein the infrared absorption layer is laminated on a transparent substrate by a coating method.

An eighth invention is the infrared absorption filter according to any one of the first to seventh inventions, wherein the transparent substrate is a polyester film.

A ninth invention is characterized in that, in the infrared absorbing layer, the specific gravity of the polyester resin is in the range of 1.05 to 1.35, and the solubility of the infrared absorbing dye is 1% by weight or more. An infrared absorption filter according to any one of the first to eighth aspects.

In a tenth aspect, the amount of the residual solvent in the infrared absorbing layer is 5.0% by weight or less.
An infrared absorption filter according to any one of the first to ninth aspects.

An eleventh invention is the infrared absorbing filter according to any one of the first to tenth inventions, wherein the polyester resin has a glass transition temperature of 85 to 130 ° C.

A twelfth invention is the infrared absorption filter according to any one of the first to eleventh inventions, wherein the infrared absorption filter has an antireflection layer as an outermost layer.

A thirteenth invention is the infrared absorption filter according to any one of the first to twelfth aspects, wherein the infrared absorption filter has an antiglare treatment layer as an outermost layer.

According to a fourteenth aspect, there is provided an infrared absorption filter, wherein the filter according to any one of the first to thirteenth aspects is provided on a front surface of a plasma display.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The infrared absorbing filter of the present invention has a structure in which an infrared absorbing layer mainly composed of an infrared absorbing dye and a polymer resin is laminated on a transparent substrate.
Hereinafter, embodiments of the infrared absorption filter of the present invention will be described.

In the infrared absorption filter of the present invention,
It is necessary to use at least a diimonium salt compound as the infrared absorbing dye. The diimonium salt compound to be used is not particularly limited as long as it has a large absorption in the near infrared region and a high visible light transmittance, but in particular, the general formula (2)
Those having the structural formula represented by are preferred.

[0035]

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(Wherein R _{1 to} R ₈ represent a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, or an aralkyl group, and may be the same or different.
₉ to R _{1 2} is hydrogen atom, a halogen atom, an amino group, an amido group, a cyano group, a nitro group, a carboxyl group, an alkyl group, even each same or may be different. Those capable of bonding a substituent at R _{1 to} R ₁₂ may have a substituent. X ^- represents an anion. )

In R _{1 to} R ₈ in the general formula (2),
Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a t-butyl group, an n-amyl group, an n-hexyl group, and an n-octyl group. , 2-hydroxyethyl group, 2-cyanoethyl group, 3-hydroxypropyl group, 3-cyanopropyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group and the like. Examples of the aryl group include a phenyl group, a fluorophenyl group, a chlorophenyl group, a tolyl group, diethylaminophenyl, and a naphthyl group. Examples of the alkenyl group include a vinyl group, a propenyl group, a butenyl group, and a pentenyl group. Further, examples of the aralkyl group include a benzyl group, a p-fluorobenzyl group, a p-chlorophenyl group, a phenylpropyl group, and a naphthylethyl group.

R _{9 to} R ₁₂ in the general formula (2) represent hydrogen, fluorine, chlorine, bromine, diethylamino, dimethylamino, cyano, nitro, methyl, ethyl,
And a trifluoromethyl group. X ^- represents fluorine ion, chloride ion, bromine ion, iodine ion, perchlorate ion, hexafluoroantimonate ion,
Hexafluorophosphate ion, tetrafluoroborate ion and the like can be mentioned. However, the present invention is not limited to the above.

As the infrared absorbing dye used in the present invention, it is preferable to use at least one of a phthalocyanine compound and a nickel complex compound in addition to the diimmonium salt compound. The phthalocyanine-based compound and / or thionickel-based complex compound used in the present invention is not particularly limited, but it is preferable to supplement the absorption in the near infrared region of the diimonium salt compound.

The phthalocyanine compound is preferably a fluorine-containing phthalocyanine compound. Available commercial products include Excolor IR1, IR2, IR3, IR4, TX manufactured by Nippon Shokubai Co., Ltd.
-EX805K, TX-EX810K, TX-EX811K, TX-EX812K and the like. Among them, IR1 and TX-EX811K are particularly preferred.

The thionickel complex-based compound is preferably a compound represented by the general formula (3). Commercial products include Mitsui Chemicals SIR-128, SIR-130, SIR-132, SIR
-159 and the like. Among them, SIR-128 and SIR-159 are particularly preferred.

[0042]

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(R _{1 to} R ₄ are a hydrogen atom, a halogen atom,
Represents an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or an amino group. )

The mixing ratio of the infrared absorbing dye contained in the infrared absorbing layer of the infrared absorbing filter of the present invention is 0.5 to 0.0 parts by weight of the fluorinated phthalocyanine compound to 1.0 part by weight of the diimmonium compound. The nickel complex compound having 1.0 to 0.0 parts by weight has steep absorption in the near infrared region, has a large absorption rate and absorption width in the near infrared region, and has a light transmittance in the visible region. It is more preferable in terms of increasing the height.

In the present invention, the high molecular resin which is a main component of the infrared absorbing layer is a polyester resin comprising a polyvalent carboxylic acid and a polyvalent alcohol. Specific examples of the polycarboxylic acid include the following. (1) terephthalic acid, isophthalic acid, orthophthalic acid,
1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenic acid, sulfoterephthalic acid, 5-
Sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5 [4-sulfophenoxy] isophthalic acid, sulfoterephthalic acid, and / or
Or aromatic dicarboxylic acids such as metal salts and ammonium salts thereof; (2) aromatic oxycarboxylic acids such as p-oxybenzoic acid and p- (hydroxyethoxy) benzoic acid; and (3) succinic acid, adipic acid, azelaic acid, Aliphatic dicarboxylic acids such as sebacic acid and dodecane dicarboxylic acid (4) Unsaturated aliphatic dicarboxylic acids and alicyclic dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid, hexahydrophthalic acid and tetrahydrophthalic acid 5) Trivalent or higher polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid

As the polyhydric alcohol, it is necessary to use an alicyclic diol represented by the general formula (1) as an essential component, and to copolymerize the alicyclic diol component with a polyester resin in an amount of 60 mol% or more.

[0047]

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As the alicyclic diol represented by the general formula (1), tricyclodecane dimethylol, tricyclodecane dielol, tricyclodecane dipropylol,
Tricyclodecanedibutanol, dimethyltricyclodecanedimethylol, and the like. Of these, R ₁
And R ₂ is particularly preferably tricyclodecane dimethylol, which is a methylol group.

In addition to the alicyclic diol component represented by the general formula (1), the polyhydric alcohol component of the polyester resin, which is a main component of the infrared absorbing layer used in the present invention, may be an aliphatic polyhydric alcohol. Alcohols, alicyclic polyhydric alcohols, aromatic polyhydric alcohols and the like can be copolymerized within a range of 40 mol% or less of the polyhydric alcohol component.

For example, the aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, 1,
3-propanediol, 2,3-butanediol, 1,
4-butanediol, 1,5-pentanediole, 1,
6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2
Aliphatic diols such as 4-trimethyl-1,3-pentaneddiol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolethane, trimethylolpropane, glycerin, pentaerthrite And triol such as thiol and tetraol.

The alicyclic polyvalent alcohols include 1,4
-Cyclohexanediol, 1,4-cyclohexanedimethanol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, tricyclodecanediol And tricyclodecane dimethanol.

The aromatic polyhydric alcohols include para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol,
Examples thereof include an ethylene oxide adduct of 1,4-phenylene glycol, bisphenol A, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct.

Further, as other polyhydric alcohols,
Lactone-based polyester polyols obtained by ring-opening polymerization of a lactone such as ε-caprolactone can be exemplified.

In addition, a monofunctional monomer may be introduced into the polyester resin in order to block the polar group at the terminal of the polyester resin.

The monofunctional monomers include benzoic acid, chlorobenzoic acid, bromobenzoic acid, parahydroxybenzoic acid,
Monoammonium sulfobenzoate, monosodium sulfobenzoate, cyclohexylaminocarbonylbenzoic acid, n-dodecylaminocarbonylbenzoic acid, tert-butylbenzoic acid, naphthalenecarboxylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, Salicylic acid, thiosalicylic acid, phenylacetic acid, acetic acid, propionic acid, butyric acid,
Monocarboxylic acids such as isobutyric acid, octanecarboxylic acid, lauric acid, stearyl acid and lower alkyl esters thereof, and monoalcohols such as aliphatic alcohols, aromatic alcohols and alicyclic alcohols Can be used.

JP-A-9-888855 and JP-A-11-116826 disclose polyester resins obtained by copolymerizing a specific aromatic diol in an amount of 10 mol% or more. It has been found that by making the alicyclic diol represented by 1) a copolymer with 60 mol% or more of a polyester resin, the solvent solubility and coating suitability are extremely excellent.

When the content of the alicyclic diol is less than 60 mol%, the solubility in a solvent is improved and the coating is easy, but the glass transition temperature of the copolymerized polyester resin is lowered and the environmental stability when an infrared absorbing dye is mixed. Deteriorates. In the present invention, the upper limit of the copolymerization amount of the alicyclic diol component represented by the general formula (1) is preferably less than 95 mol%. If it is 95 mol% or more, the degree of polymerization of the copolyester resin is difficult to increase, and as a result, it tends to be very brittle, which is not preferable.

In the present invention, the glass transition temperature of the copolymerized polyester resin serving as the dispersion medium of the near-infrared absorbing dye may be equal to or higher than the guaranteed use temperature of a device using an infrared absorbing filter in order to improve weather resistance. I need it.

When the glass transition temperature is lower than the temperature at which the apparatus is used, the diimmonium salt compound which is an infrared absorbing dye reacts with the copolymerized polyester itself or reacts with other infrared absorbing dyes dispersed in the copolymerized polyester. Or Further, under humidification, the copolyester absorbs moisture in the outside air and the like, and the infrared absorbing dye and the copolyester deteriorate more.

In the present invention, the glass transition temperature of the copolymerized polyester resin, which is a main component of the infrared absorbing layer, needs to be 85 to 130 ° C., and preferably 90 to 110 ° C. When the glass transition temperature is lower than 85 ° C., the diimmonium salt compound is modified as described above. When the glass transition temperature exceeds 130 ° C.,
When the copolymerized polyester resin is dissolved in a solvent, coated on a transparent substrate and sufficiently dried, the temperature must be raised to a high temperature, and the diimonium salt compound is denatured. In addition, the deterioration of other heat-resistant infrared-absorbing dyes is also caused. Further, when drying is performed at a low temperature, the drying time has to be prolonged, thereby lowering productivity and making it impossible to produce an inexpensive infrared absorption filter. Further, there is a possibility that sufficient drying cannot be performed.

In the infrared absorbing filter of the present invention, the amount of the residual solvent in the infrared absorbing layer is preferably 5.0% by weight or less. When the infrared absorbing layer is formed by a solvent-based coating method, even if the amount of the residual solvent exceeds 5.0% by weight, even if it is visually dry and no blocking or the like occurs, an apparent glass transition occurs. The temperature drops significantly. In particular, when a diimmonium salt compound is used as the infrared absorbing dye, there is a problem that when left under high temperature and humidification for a long time, the diimonium salt dye is denatured, and the filter turns yellow-green.

In the present invention, the amount of the residual solvent in the infrared absorbing layer is particularly preferably 0.05 to 3.0% by weight. When the amount of the residual solvent is less than 0.05% by weight, the modification of the near-infrared absorbing dye when left under high temperature and high humidity for a long time becomes small, The infrared absorbing dye is easily denatured.

The amount of the residual solvent in the infrared absorbing layer was 5.0% by weight.
In order to achieve the following, it is necessary to simultaneously satisfy the drying conditions of the following formulas (4) to (6). The following equation (4)
The unit of the factors used in (6) is wind speed m / sec, hot air temperature is ° C., drying time is minute, and coat thickness is μm. Wind speed × (hot air temperature−20) × drying time / coat thickness> 48 (4) Hot air temperature: ≧ 80 ° C. (5) Drying time: ≦ 60 minutes (6)

In the present invention, the copolymerized polyester resin used for the infrared absorbing layer has a specific gravity of 1.05 to 1.05.
Preferably, the solubility of the infrared absorbing dye is not less than 1.35% by weight.

The transparent substrate of the infrared absorbing layer of the present invention is preferably a polymer film, and the resin constituting the film may be polyester, acrylic, cellulose, polyethylene, polypropylene, polyolefin, polyolefin, or the like. Examples thereof include vinyl chloride-based, polycarbonate, phenol-based, and urethane-based resins, but are not particularly limited. Among them, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate are preferable from the viewpoint of environmental load, cost performance, and the like. Above all,
Polyethylene terephthalate (hereinafter abbreviated as PET) is particularly preferred. Hereinafter, PET will be described in detail as an example.

The PET resin is produced by a known direct polymerization method in which terephthalic acid and ethylene glycol are used as starting materials and polycondensation is carried out through an esterification reaction, or a polymerization is carried out by using dimethyl terephthalate and ethylene glycol as starting materials and a transesterification reaction. Any of the known transesterification methods for condensation can be used. In the case of the direct polymerization method, the polycondensation catalyst (Sb ₂ O ₃ ,
Sb glycolate, etc.), thermal stabilizers (P-based compounds such as trimethyl phosphate), and adhesion improvers (glycol-soluble alkali metal salts, alkaline earths) for producing unstretched films using electrostatic coating Metal salt). In the case of the transesterification method, a transesterification catalyst (eg, an acetate such as Mg, Ca, Zn, or Mn) is required in addition to the above compound. In particular, when Sb ₂ O ₃ is used as a polycondensation catalyst, the polymerization and / or unstretched P
During the production of the ET film, Sb ₂ O ₃ is reduced to metal Sb, and tends to precipitate as an aggregate on the film surface. Since this is one of the causes of optical defects in the film, it is preferable to reduce the content of Sb ₂ O ₃ as much as possible within a range that does not significantly delay the polycondensation time.

In order to reduce the number of foreign substances having a size of 20 μm or more in the PET film to 10 particles / m ² or less per unit area of the PET film, the content of Sb ₂ O ₃ in the PET resin should be 50 to 250 ppm as Sb element. Preferably 5
The content is more preferably 0 to 200 ppm, particularly preferably 7 ppm.
0 to 150 ppm. In addition, in general, the PET resin contains inert particles and internally precipitated particles for the purpose of imparting lubricity. However, from the viewpoint of improving transparency and reducing the above-mentioned foreign substances, these particles are substantially used. It is necessary not to contain it. The term “substantially free of particles” means that, for example, when inorganic particles are taken as an example, the content of the inorganic particles in the film is lower than the detection limit when analyzed by fluorescent X-ray. I do.

Further, after completion of the polycondensation, the PET resin is filtered with a NASLON filter having a pore diameter (95% cut) of 7 μm or less, or when the molten resin is extruded in a strand form into the cooling water, the cooling water is previously filtered. (Pore size: 1
μm or less), and making this process a closed room, and reducing foreign matter of 1 μm or more in the environment with a hepafilter can reduce foreign matter of 20 μm or more in PET resin as a raw material of the base film. 1 per unit area of film
It is preferable to set the number to 0 / m ² or less.

The intrinsic viscosity of the PET resin is 0.45
The range of -0.70 dl / g is preferable. It is more preferably from 0.50 to 0.67 dl / g, and particularly preferably from 0.55 to 0.65 dl / g. Intrinsic viscosity is 0.4
When it is lower than 5 dl / g, rupture frequently occurs during film production, and the high elongation characteristics become insufficient. On the other hand, 0.70d
If it is larger than 1 / g, the increase in filtration pressure becomes large, and high-precision filtration for removing foreign substances becomes difficult, which is not preferable.

After sufficiently vacuum-drying the PET resin substantially free of inert particles and internally precipitated particles, the PET resin is supplied to an extruder and melt-extruded into a sheet at about 280 ° C.
After cooling and solidifying, an unstretched PET sheet is formed. At this time, in order to further remove foreign substances contained in the PET resin, the high-precision filtration is performed at an arbitrary place where the molten resin is kept at about 280 ° C. to remove the foreign substances contained in the resin. Do.

The filter medium used for the high-precision filtration of the molten resin is not particularly limited. In the case of a filter medium of a sintered stainless steel, the catalyst and additives in the raw PET resin, the falling objects from the reaction vessel wall, the external contamination, etc. It is suitable for reducing the number of foreign substances having a size of 20 μm or more such as coarse foreign substances and high melting point organic substances caused by the substance to 10 pieces / m ² or less per unit area of the film. It is preferable that the filtration particle size (initial filtration efficiency: 95%) of the filter medium used for high-precision filtration of the molten resin is 15 μm or less. When the filtration particle size of the filter medium exceeds 15 μm, the removal of foreign substances of 20 μm or more tends to be insufficient. Filtration particle size (initial filtration efficiency 95%) is 15 μm
By performing high-precision filtration of the molten resin using the following filter media, productivity may be reduced, but it is extremely important to obtain a PET film having few optical defects and excellent transparency.

As a method of cooling the unstretched film,
A known method can be applied in which the molten resin is extruded from a die into a sheet onto a rotary cooling drum, and the sheet-like molten material is rapidly cooled while being brought into close contact with the rotary cooling drum by an electrostatic application contact method.

The polymer film serving as the transparent substrate of the infrared absorbing filter of the present invention is preferably a film stretched in at least one direction, and particularly preferably a biaxially stretched film. The biaxially stretched film is manufactured under the following conditions.

The obtained unstretched film was treated with 80 to 120
The film is stretched into at least two or more stages in the longitudinal direction by a roll heated to a temperature of C, and stretched so that the total longitudinal stretching ratio becomes 2.5 to 5.0 times to obtain a uniaxially oriented PET film. Further, the end of the film is gripped with a clip, guided to a hot air zone heated to 80 to 180 ° C., and stretched 2.5 to 5.0 times in the width direction. Further, this biaxial stretching may be performed by a simultaneous biaxial stretching method driven by a linear motor system with a tenter instead of the sequential biaxial stretching method for the purpose of reducing scratches caused by rolls. Note that a conventional simultaneous biaxial stretching method may be used. Subsequently, it is led to a heat treatment zone of 200 to 240 ° C. and heat treated for 1 to 60 seconds to complete the crystal orientation. During this heat treatment step, if necessary, a relaxation treatment of 3 to 10% may be performed in the width direction and / or the longitudinal direction.

Further, it is preferable to laminate a high polymer adhesive layer on at least one surface of the biaxially oriented PET film. The polymer easy-adhesion layer is laminated at any stage in the film production process by applying and drying a coating solution of a polymer easy-adhesion resin composed of a water-soluble or water-dispersible resin on at least one surface of the PET film. Is preferred.

The step of applying the aqueous coating solution may be a normal coating step, that is, a step of coating a base film which has been biaxially stretched and heat-set. However, an in-line coating method of coating during the production step of the film may be used. preferable. More preferably, it is applied to the base film before the completion of the crystal orientation. The cleanliness in the air in the coating process after the preparation of the unstretched film (number of particles of 0.5 μ or more / ft ³ )
Is controlled by a hepafilter so as to have a class of 100,000, which is effective for reducing foreign substances adhering to the film surface.

When the above coating solution is applied to an unstretched or uniaxially stretched polyester film substrate and then dried and stretched, in the drying step after the application, only the solvent such as water is removed and the crosslinking reaction of the coating layer is carried out. It is important to choose a temperature and time that will not proceed. Drying temperature is 70-140 ° C
The drying time is adjusted according to the application liquid and the amount of application, and the temperature product of the temperature (° C.) and the time (second) is preferably 3000 or less.

The solid content in the aqueous coating solution is 30% by weight.
Or less, particularly preferably 10% by weight
It is as follows. The film to which the aqueous coating solution has been applied and dried is guided to a tenter for stretching and heat fixing, where it is heated to form a stable film by a thermal crosslinking reaction,
It becomes a biaxially oriented laminated PET film. In order to obtain good adhesiveness with the infrared absorbing layer, it is necessary to use 10
It is preferable that the heat treatment is performed at 0 ° C. or more for 1 minute or more, and the application amount of the easy adhesion layer after the heat treatment is 0.05 g / m ² or more.

The aqueous coating solution can be applied by a known method. For example, a reverse roll coating method, a gravure coating method, a kiss coating method, a roll brushing method, a spray coating method, an air knife coating method, a wire bar bar coating method, a pipe doctor method, an impregnation coating method, a curtain coating method, and the like, and these methods are mentioned. Can be used alone or in combination.

The above-mentioned high polymer adhesive resin is not particularly limited, and examples thereof include an aqueous polyester resin, an aqueous polyurethane resin, an aqueous acrylic resin, an acrylic acid-grafted polyester resin, and a maleic acid-grafted polyester resin. Can be Above all, a polymer resin and a maleic acid-grafted polyester resin containing the above-mentioned copolymerized polyester resin and polyurethane resin as main components are excellent in adhesiveness to a PET film or an infrared absorbing layer of a base material, and have an infrared ray. It is excellent in adhesiveness to an anti-reflection layer or an anti-glare treatment layer laminated on the outermost layer of the absorption filter, and is preferable because it also has high transparency. Therefore, the surface of the PET film of the substrate on which the infrared absorbing layer is laminated, and the surface of the PET film of the substrate on which the antireflection layer or the antiglare treatment layer is laminated, are provided with the above-mentioned polymer easy-adhesion layer, especially a copolymer polyester. It is preferable to provide an easy-adhesion layer made of a polymer resin containing a base resin and a polyurethane resin as main components and / or a maleic acid-grafted polyester resin.

A catalyst may be added to the aqueous coating solution used for the easy-adhesion layer of the biaxially oriented laminated PET film, which is the transparent substrate of the infrared absorbing filter of the present invention, in order to promote the thermal crosslinking reaction. For example, various chemical substances such as inorganic substances, salts, organic substances, alkaline substances, acidic substances, and metal-containing organic compounds can be used. In order to adjust the pH of the aqueous solution, an alkaline substance or an acidic substance may be added.

When the aqueous coating solution is applied to the surface of a substrate film, a known anionic active agent and a nonionic interface are used to improve the wettability to the film and uniformly coat the coating solution. The required amount of activator can be used. The solvent used for the coating liquid is alcohol such as ethanol, isopropyl alcohol, and benzyl alcohol in addition to water, and the proportion of the total coating liquid is 50% by weight.
You may mix until it becomes less than. Further, when the content is less than 10% by weight, an organic solvent other than alcohols may be mixed in a range where it can be dissolved. However, the total of alcohols and other organic solvents in the coating liquid is preferably less than 50% by weight.

When the addition amount of the organic solvent is less than 50% by weight, the drying property is improved at the time of coating and drying, and the appearance of the coating film is improved as compared with the case where only water is used. If it exceeds 50% by weight, the solvent evaporates at a high rate, the concentration of the coating solution changes during coating, the viscosity increases, and the coating property decreases, which may cause poor appearance of the coating film. In addition, there is a risk of fire.

In the present invention, since the base film does not contain particles for the purpose of imparting lubricity or the like, the particles are contained in the aqueous coating solution to form appropriate protrusions on the surface of the easily adhesive layer. This is preferred from the viewpoints of the film handling properties (slip properties, winding properties, blocking resistance), abrasion resistance, scratch resistance and the like. Examples of such particles include calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite,
Examples include inorganic particles such as molybdenum sulfide, crosslinked polymer particles, and organic particles such as calcium oxalate. Among these, silica particles are most preferable because they have a refractive index relatively close to that of the polyester resin and can provide a film having high transparency.

The average particle size of the particles contained in the aqueous coating solution is preferably 0.01 to 1.0 μm, and 0.03 to 0.1 μm.
Particularly preferred is 5 μm or less. When the average particle size exceeds 1.0 μm, the film surface tends to be rough, and the transparency of the film tends to decrease. On the other hand, if the average particle size is less than 0.01 μm, the film tends to have insufficient sliding properties, winding properties, blocking properties, and the like.

The particle content in the above-mentioned easy-adhesion layer is as follows:
It is preferably from 0.01 to 60% by weight, more preferably from 0.05 to 30% by weight, even more preferably from 0.1 to 10% by weight. When the content of the particles in the easy-adhesion layer exceeds 60% by weight, the transparency of the film tends to be deteriorated, and the easy-adhesion may be further impaired. On the other hand, when the content of the particles in the easy-adhesion layer is less than 0.01% by weight, the slip property, winding property, blocking property and the like of the film tend to be insufficient.

Two or more kinds of the above-mentioned particles may be blended in the easy-adhesion layer, and the same kind of particles having different particle diameters may be used in combination. In any case, it is preferable that the average particle diameter of the whole particles and the total content satisfy the above-mentioned ranges.

In applying the above-mentioned coating solution, it is preferable to arrange a filter medium so that the coating solution is finely filtered just before the application in order to remove coarse aggregates of particles in the coating solution.

When the filtration particle size of the filter medium for precision filtration of the coating solution used in the present invention is set to 25 μm or less (initial filtration efficiency: 95%), the surface and / or inside of the polymer easy-adhesion layer is formed to 100 μm It is suitable to set the number of coarse substances having the above maximum diameter to 3 / m ² or less per unit area of the high polymer adhesive layer. When the filter particle size of the filter medium is 25 μm or more, coarse aggregates cannot be sufficiently removed, and many coarse aggregates that cannot be removed are subjected to stretching stress when the easily adhesive layer is uniaxially stretched or biaxially stretched after coating and drying. Coarse aggregates spread and are recognized as aggregates of 100 μm or more, and as a result, many optical defects tend to occur.

The type of the filter medium for finely filtering the coating solution is not particularly limited as long as it has the above-mentioned performance. For example, a filament type, a felt type, and a mesh type are suitable. The material of the filter medium for finely filtering the coating liquid is not particularly limited as long as it has the above-described performance of removing coarse aggregates and does not adversely affect the coating liquid.
Materials such as polyethylene, polypropylene, and nylon are preferred.

In the aqueous coating solution, various additives such as an antistatic agent, an ultraviolet absorbing agent, a plasticizer, an antibacterial agent, a pigment, a lubricant and the like may be added in addition to the particles as long as the adhesion and the transparency are not impaired. Agents may be mixed.

The obtained biaxially stretched laminate P having an easily adhesive layer
The thickness of the ET film is preferably 50 to 300 μm,
Particularly preferably, it is 100 to 250 μm. If the film thickness is less than 50 μm, the rigidity becomes insufficient, which is not preferable. On the other hand, if the thickness of the film exceeds 300 μm, it is not preferable because foreign substances which are optical defects existing in the film increase and the total light transmittance decreases.

Further, it is necessary that foreign matters having a size of 20 μm or more in the PET film having the easy-adhesion layer are 10 pieces / m ² or less per unit area of the film, preferably 8 pieces / m ² or less. Particularly preferably, the number is 6 / m ² or less. If the number of foreign matters having a size of 20 μm or more exceeds 10 particles / m ² , the haze value of the entire film increases, and the total light transmittance may decrease. Further, it causes optical defects and is not preferable as an infrared absorption filter.

In order to reduce the number of foreign substances having a size of 20 μm or more to 10 particles / m ² or less per unit area of the film, as described above, for example, when a PET resin is used as a film material, the following method is used. It is suitable. (1) The content of Sb ₂ O ₃ , which is a polycondensation catalyst at the time of PET production, should be lower than usual (50 to 250 ppm as Sb element relative to PET, preferably 50 to 200 ppm).
pm is more preferable, and particularly preferably 70 to 150 p.
pm). (2) Inert particles and internally precipitated particles are not substantially contained. (3) After completion of polycondensation, the pore size of PET resin (95% cut)
Is filtered through a NASLON filter having a diameter of 5 μm or less, or when the molten resin is extruded in a strand form into the cooling water, the cooling water is filtered (pore diameter: 1 μm or less) in advance, and this step is separated by a curtain. To remove foreign matter of 1 μm or more in the environment. (4) Molten PET in the extrusion process during PET film production
High precision filtration of resin (filtration particle size at initial filtration efficiency of filter medium of 95%: ≤ 15 µm).

The haze value of the PET film serving as the base material of the infrared absorbing filter of the present invention is preferably 1.0% or less. It is more preferably at most 0.8%, particularly preferably at most 0.6%. If the haze value exceeds 1.0%, it is not preferable because the definition of a screen of a display using an infrared absorption filter having this PET film as a base material is reduced. In order to reduce the haze value to 1.0% or less, the above-mentioned film is made substantially free of inert particles and internally precipitated particles, and the above-mentioned means for removing coarse foreign substances is employed. As the resin constituting the adhesive layer, it is effective to use a polymer resin containing a copolymerized polyester resin and a polyurethane resin as main components and / or a maleic acid grafted polyester resin.

An infrared absorbing layer is laminated on the biaxially oriented laminated PET film obtained above, on which at least one surface is laminated with a high polymer adhesive layer. The lamination of the infrared absorbing layer may be on the easily adhesive surface of the transparent polymer film or on the surface without the easily adhesive layer.

Further, in order to further improve the light resistance of the infrared absorption filter of the present invention, a UV absorber may be contained in the infrared absorption layer. Further, in order to further improve weather resistance and solvent resistance, a polymer resin in which an infrared absorbing dye is dispersed may be crosslinked using a crosslinking agent. Further, in the infrared absorbing layer of the infrared absorbing filter of the present invention, other kinds of dyes may be further mixed as needed within a range not to impair the effects of the present invention.

However, when manufacturing an infrared filter in which an infrared absorbing layer is laminated on both sides of a PET film, both sides of the film are smoothed by the infrared absorbing layer, so that it is difficult to wind the film into a roll during mass production. Therefore, by containing inert particles on at least one surface of the infrared absorption layer, by forming irregularities on the surface of the infrared absorption layer,
It is preferable to improve handling properties such as slipperiness, winding property, and blocking property. The inert particles are preferably mixed in a polymer resin in which the infrared absorbing dye is dispersed. As the inert particles, from the viewpoint of transparency, the average particle diameter that is shorter than the wavelength of visible light is 0.01 to
Fine particles of a metal oxide such as 0.1 μm of silica or alumina, or fine particles of a fluorine resin, an acrylic resin, or a polyester resin can be used. Further, it is preferable that the infrared absorbing layer of the infrared absorbing filter of the present invention contains an ultraviolet absorber for the purpose of improving light resistance. Furthermore, in the infrared absorbing layer of the infrared absorbing filter of the present invention, if necessary within a range that does not impair the effects of the present invention,
Further, other kinds of dyes may be mixed.

When laminating an infrared absorbing layer on at least one side of a PET film as a substrate, a polymer resin is dissolved in a solvent such as methyl ethyl ketone, tetrahydrofuran, toluene, etc., and then a coating liquid in which an infrared absorbing dye is dispersed is applied to the substrate film. It is preferable to apply and dry on at least one side of the substrate. Further, it is preferable that the infrared absorbing layer of the infrared absorbing filter of the present invention contains an ultraviolet absorber for the purpose of improving light resistance. Further, in the infrared absorbing layer of the infrared absorbing filter of the present invention, if necessary, other kinds of dyes may be mixed as long as the effects of the present invention are not impaired.

When the infrared absorbing layer is applied to both sides of the substrate film, the method is not particularly limited,
As an example, the following method can be used. For example, by providing a plurality of coater heads on one coating line, a method of simultaneously coating both sides and drying both sides simultaneously, or a method of first coating and drying one side and then coating and drying the back side again And the like.

In the infrared absorbing filter of the present invention, it is preferable that a metal mesh conductive layer is laminated on the same side or the opposite side as the infrared absorbing layer. By laminating the metal mesh conductive layer, it is possible to remove harmful electromagnetic waves emitted from the display. As the metal mesh conductive layer, a metal foil with high electrical conductivity is subjected to etching treatment to form a mesh, a woven mesh using metal fibers, or a metal plated on the surface of polymer fibers. Fibers attached using a technique may be used.

The aperture ratio of the metal mesh used for the electromagnetic wave absorbing layer is preferably 50% or more in consideration of a case where the metal mesh is used for a display. The metal used for the electromagnetic wave absorbing layer may be any metal as long as it has high electric conductivity and good stability, and is not particularly limited. From the viewpoints of workability, cost, and the like, copper, nickel, tungsten, and the like are preferable.

The infrared absorbing filter of the present invention
A hard coat treatment layer (HC) may be provided on the outermost layer to improve scratch resistance. As the hard coat treatment layer (HC), a curable resin such as a polyester resin, a urethane resin, an acrylic resin, a melamine resin, an epoxy resin, a silicone resin, and a polyimide resin is used alone or as a mixture. A cured resin layer is preferred.

The thickness of the hard coat treatment layer (HC) is preferably in the range of 1 to 50 μm, more preferably in the range of 2 to 30 μm. If the thickness is less than 1 μm, the scratch resistance becomes insufficient, and if the thickness exceeds 50 μm, the coating speed of the hard coat resin becomes extremely slow, which is not preferable in terms of productivity.

As a method of laminating the hard coat treatment layer (HC), the above-mentioned resin was coated on the surface of the PET film opposite to the surface on which the infrared absorption layer was provided by a gravure method, a reverse method, a die method or the like. Thereafter, a method of applying energy such as heat, ultraviolet rays, or an electron beam to cure the resin is preferable.

Further, the infrared absorption filter of the present invention
An anti-glare treatment layer (AG) may be provided as the outermost layer in order to improve visibility when used in a plasma display or the like. The anti-glare layer (AG) can be manufactured by coating a curable resin, drying and forming irregularities on the surface with an embossing roll, and then applying heat, ultraviolet light, electron beam, and other energy to cure the resin. it can. The curable resin is preferably a single or a mixture of a polyester resin, a urethane resin, an acrylic resin, a melamine resin, an epoxy resin, a silicon resin, and a polyimide resin.

Further, in order to further improve the transmittance of visible light when the infrared absorbing filter of the present invention is used for a display, an antireflection treatment layer (AR) may be provided on the outermost layer. It is preferable that a material having a refractive index different from that of the plastic film be a single layer or a laminate of two or more layers in the antireflection treatment layer (AR). In the case of a single-layer structure, it is preferable to use a material having a smaller refractive index than the plastic film. When a multilayer structure having two or more layers is used, a material having a higher refractive index than the plastic film is used for a layer adjacent to the plastic film, and a material having a lower refractive index is used for a layer above the plastic film. It is preferable to select As a material constituting such a reflection preventing treatment layer (AR), is not particularly limited as far as it satisfies the relation of the refractive index of the even inorganic materials in organic materials, for example, CaF _2, MgF _2, NaAl
F ₄ , SiO ₂ , ThF ₄ , ZrO ₂ , Nd ₂ O ₃ , Sn
It is preferable to use a dielectric such as O ₂ , TiO ₂ , CeO ₂ , ZnS, and In ₂ O ₃ .

The anti-reflection treatment layer (AR) may be laminated by a dry coating process such as a vacuum deposition method, a sputtering method, a CVD method, or an ion plating method, or a wet coating process such as a gravure method, a reverse method, or a die method. May be.

Further, the hard coat treated layer (H
C) Prior to lamination of the antiglare treatment layer (AG) and the antireflection treatment layer (AR), corona discharge treatment, plasma treatment, sputter etching treatment, electron beam irradiation treatment,
Known treatments such as an ultraviolet irradiation treatment, a primer treatment, and an easy adhesion treatment may be performed.

[0110]

EXAMPLES Next, the method for producing an infrared absorbing filter of the present invention will be described in detail with reference to examples, but it is needless to say that the present invention is not limited thereto. “Parts” used in Examples and Comparative Examples means “parts by weight” unless otherwise specified. The evaluation of the characteristic values used in this specification was based on the following method.

(1) Intrinsic Viscosity of Polyester Resin It was determined from the solution viscosity at 30 ° C. in a mixed solvent of 1,1,2,2-tetrachloroethane / phenol (weight ratio: 2/3).

(2) Size of foreign matter in the film and coarse aggregates in the coating liquid: 250 mm ×
Optically, 50 pieces of 16 pieces of 250 mm film were used.
Optical defects recognized as having a size of μm or more were detected. (Principle of Detecting Optical Defects) A 20 W × 2 fluorescent lamp as a light projector is arranged 400 mm below the XY table, and a mask having a slit width of 10 mm is provided. When light is incident at an angle of 12 degrees between the line connecting the projector and the light receiver and the vertical direction of the film surface to be measured, if there is an optical defect there, the portion shines and the amount of light is 500 mm above the XY table.
Is converted into an electric signal by a CCD image sensor camera arranged in the above, the electric signal is amplified, differentiated, and compared with a threshold level by a comparator to output a detection signal of an optical defect. Further, the size of the optical defect is measured by the image procedure from the video signal input from the CCD image sensor camera, and the position of the optical defect having the set size is displayed.

Using the above-described optical defect detection device, optical defects due to foreign matter and optical defects due to coarse aggregates in the coating solution are selected from the detected defect portions, and cut into appropriate sizes, and the film is cut with a microscope equipped with a scale. The size when observed from a direction perpendicular to the plane was measured. In the case of an optical defect caused by a foreign substance, the maximum diameter of the foreign substance was measured, and the number of foreign substances having a size of 20 μm or more was determined per unit area (1 m ² ) of the film. In the case of coarse aggregates in the coating solution, the maximum diameter of the coarse aggregates was measured, and the number of foreign substances having a size of 100 μm or more was determined per unit area (1 m ² ) of the easily adhesive layer.

(3) Haze value The haze value was measured using a haze meter (Model TC-H3DP manufactured by Tokyo Denshoku Industries Co., Ltd.) according to JIS-K7105.

(4) Spectral Characteristics Using a self-recording spectrophotometer (Hitachi U-3500 type),
It measured in the range of 500-200 nm.

(5) Environmental Stability Samples were prepared in an atmosphere at a temperature of 60 ° C. and a humidity of 95%.
After standing for a period of time, the spectral characteristics described above were measured.

Example 1 (1) Preparation of Coating Solution for Polymer Easy Adhesion Layer A coating solution used for the polymer easy adhesion layer to be laminated on the transparent polymer film in the present invention was prepared according to the following method. 95 parts of dimethyl terephthalate, 95 parts of dimethyl isophthalate
, 35 parts of ethylene glycol, 145 parts of neopentyl glycol, 0.1 part of zinc acetate and 0.1 part of antimony trioxide were charged into a reaction vessel, and transesterification was carried out at 180 ° C for 3 hours. Next, 6.0 parts of 5-sodium isophthalic acid was added, and the esterification reaction was performed at 240 ° C. for 1 hour, and then under reduced pressure (13.3) at 250 ° C.
To 0.267 hPa) for 2 hours to obtain a polyester resin having a molecular weight of 19,500 and a softening point of 60 ° C.

30% of the obtained polyester resin (A)
6.7 parts of an aqueous dispersion, 40 parts of a 20% aqueous solution of a self-crosslinkable polyurethane resin (B) containing isocyanate groups blocked with sodium bisulfite (product name: Elastron H-3, manufactured by Daiichi Kogyo Seiyaku), Elastron catalyst (Cat
64), 44.3 parts of water and 5 parts of isopropyl alcohol, and 0.6 part of a 10% aqueous solution of an anionic surfactant, and spherical silica particles A (Nissan Chemical Industries, Ltd.) 1.8 parts of a 20% aqueous dispersion (manufactured by: Snowtex OL, average particle size 40 nm), 4 of dry-processed silica particles B (manufactured by Nippon Aerosil Co., Ltd .; Aerosil OX50, average particle size 500 nm, average primary particle size 40 nm) % Aqueous dispersion was added to prepare a coating solution. (Hereinafter, coating solution A
Abbreviated as B. )

(2) Production of PET resin When the temperature of the esterification reactor was raised to 200 ° C., a slurry composed of 86.4 parts by weight of terephthalic acid and 64.4 parts by weight of ethylene glycol was charged. While stirring, 0.017 parts by weight of antimony trioxide and 0.16 parts by weight of triethylamine were added as catalysts. Then, the temperature was increased by applying pressure, and a gauge pressure of 0.34 MPa, 240
The pressure esterification reaction was carried out at a temperature of ° C. Thereafter, the pressure in the esterification reactor was returned to normal pressure, and 0.071 parts by weight of magnesium acetate tetrahydrate was added.
14 parts by weight were added. 260 ° C over 15 minutes
, And 0.012 parts by weight of trimethyl phosphate and then 0.0036 parts by weight of sodium acetate were added. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reactor, and the temperature was gradually increased from 260 ° C. to 280 ° C. under reduced pressure.
A polycondensation reaction was performed at 85 ° C. After completion of the polycondensation reaction, 95
Filtration was performed with a NASLON filter having a% cut diameter of 5 μm. The molten resin was extruded from a nozzle into a cooling water tank, and the strand-shaped PET resin was cut to obtain a PET chip. The obtained PET chip (A) had an intrinsic viscosity of 0.62 dl / g, an Sb content of 144 ppm, and a Mg content of Mg.
The content was 58 ppm, the P content was 40 ppm, the color L value was 56.2, and the color b value was 1.6. Inactive particles and internally precipitated particles were not substantially contained.

(3) Production of Easy Adhesive Film The above PET chip (A) was used as a raw material for a film, dried at 135 ° C. for 6 hours under reduced pressure (1.33 hPa), and then supplied to an extruder. At this time, the molten resin was subjected to a filtration treatment using a stainless sintered filter medium having a filtration particle size (initial filtration efficiency: 95%) of 15 μm. Then, about 2
The molten resin at 80 ° C. is melt-extruded from a die into a sheet, and is applied with static electricity on a metal cooling roll (chill roll) maintained at a surface temperature of 20 ° C. to be rapidly cooled and solidified.
A μm unstretched film was obtained.

Next, the unstretched film is heated to 100 ° C. by using a heated roll group and an infrared heater, and then divided into two stages in the longitudinal direction by a roll group having a difference in peripheral speed, and the total longitudinal stretching ratio is increased. The film was stretched to 3.5 times to obtain a uniaxially oriented PET film.

Thereafter, the coating solution was finely filtered through a felt-type polypropylene filter medium having a filtration particle size (initial filtration efficiency: 95%) of 25 μm, applied to one surface of the uniaxially oriented PET film by a reverse roll method, and dried. The cleanliness in the air (the number of particles having a particle size of 0.5 μ or more / ft ³ ) in the coating step after the production of the unstretched cast film was controlled by a hepafilter so as to be in a class of 100,000. Subsequently, the end of the film was gripped with a clip and placed in a preheating zone of a tenter at 80 ° C. for 20 minutes.
After drying the coating layer for 1 second, 1
The film was stretched 4.0 times at 30 ° C. Subsequently, a heat-setting treatment is performed at 240 ° C., and a lateral relaxation treatment of 3% is performed at 200 ° C., and a biaxially oriented PET having a thickness of 100 μm having an easily adhesive layer is formed.
A film was obtained. Further, the coating amount was 0.1% as solid content.
It was 0 g / m ² . The obtained biaxially oriented PET film having an easy-adhesion layer contains substantially no particles in the film, and the number of foreign substances having a maximum diameter of 20 μm or more in the film is 6 / m ² . The number of foreign substances having a maximum diameter of 100 μm or more existing on the surface and inside was 3 / m ² .

(4) Production of Copolymerized Polyester Resin for Infrared Absorbing Layer A copolymerized polyester resin serving as a dispersion medium for an infrared absorbing dye was produced in the following manner. Equipped with thermometer and stirrer
In a reactor, 136 parts by weight of dimethyl terephthalate 58 parts by weight of dimethyl isophthalate 93 parts by weight of ethylene glycol 137 parts by weight of tricyclodecane dimethanol 0.09 parts by weight of antimony trioxide are charged and heated at 170 to 220 ° C. for 180 minutes. To perform a transesterification reaction. Next, the temperature of the reaction system was set to 245 ° C.
The reaction was continued for 180 minutes at a system pressure of 1.33 to 13.3 hPa, and the copolymerized polyester resin (A
1) was obtained. The intrinsic viscosity of the copolymerized polyester resin (A1) was 0.40 dl / g, the glass transition temperature was 90 ° C., and the specific gravity was 1.245.

The composition ratio of the constituent components of the copolymerized polyester resin (A1) by NMR analysis was as follows: acid component 71 mol% terephthalic acid 29 mol% alcohol component ethylene glycol 31 mol% tricyclodecane dimethanol 69 mol%.

(5) Production of Infrared Absorbing Filter Next, a solvent, the above-mentioned copolymerized polyester resin (A1), and an infrared absorbing pigment were added to the flask in the composition shown in Table 1, and stirred while heating. , The infrared absorbing dye and the copolyester resin (A1) were dissolved. Further, the dissolved resin was applied to the surface of the easy-adhesion layer of the easy-adhesion PET film substrate using an applicator having a gap of 100 μm, and dried at a drying temperature of 90 ° C. for 1 hour. The thickness of the dried infrared absorbing layer was 25 μm, and the amount of the residual solvent was 1% by weight.

The obtained infrared absorbing filter had a dark gray color visually. FIG. 1 shows the spectral characteristics. As shown in FIG. 1, a wavelength of 400 nm to 650 n
The absorption is flat in the visible range up to
Above nm, an infrared absorption filter having steep absorption was obtained. Further, the haze value was as extremely small as 0.5%, and it was highly transparent.

The obtained infrared absorbing filter was heated at a temperature of 60.
When left for 500 hours in an atmosphere at a temperature of 95 ° C. and a humidity of 95% RH, the spectral characteristics were measured again. The results were as shown in FIG. 2. Although a slight color change was observed, the near-infrared absorption characteristics were maintained. Further, when the obtained filter was arranged on the front surface of the plasma display, there was no change in color, the contrast was improved, and the emission of near-infrared rays was reduced.

[0128]

[Table 1]

(Example 2) In the same manner as in Example 1, except that the composition of the coating solution for the infrared absorbing layer was changed to the composition shown in Table 2 in the production of the infrared absorbing filter of Example 1, An absorption filter was obtained. The thickness of the infrared absorbing layer after drying was 25 μm, and the amount of the residual solvent was 1% by weight. FIG. 3 shows the spectral characteristics. The obtained infrared absorbing filter was placed in an atmosphere at a temperature of 60 ° C. and a humidity of 95% RH.
When left for 00 hours and the spectral characteristics were measured again, the results were as shown in FIG. 4. A slight color change was observed, but the near infrared absorption characteristics were maintained.

[0130]

[Table 2]

Comparative Example 1 As a polymer resin for an infrared absorbing layer, a copolymerized polyester resin (manufactured by Toyobo Co., Ltd., Byron RV200, specific gravity 1.255, glass transition temperature 67)
° C), except that the coating solution for an infrared absorbing layer was prepared in the same manner as in Example 1 to obtain an infrared absorbing filter. The thickness of the infrared absorption layer after drying was 25 μm. The color of the obtained infrared absorption filter was dark gray visually. FIG. 5 shows the spectral characteristics. As shown in FIG. 5, an infrared absorption filter having flat absorption in a visible region from a wavelength of 400 nm to 650 nm and sharp absorption at a wavelength of 700 nm or more was obtained.

However, the obtained infrared absorbing filter was placed in an atmosphere at a temperature of 60 ° C. and a humidity of 95% RH for 500 hours.
After standing for a while, the spectral characteristics were measured again, as shown in FIG. 6, the color tone changed to green, and the near-infrared absorption characteristics became extremely poor.

Comparative Example 2 A copolymerized polyester resin serving as a dispersion medium for an infrared absorbing dye was produced in the following manner. In an autoclave equipped with a thermometer and a stirrer, 136 parts by weight of dimethyl terephthalate 58 parts by weight of dimethyl isophthalate 105 parts by weight of ethylene glycol 98 parts by weight of tricyclodecanedimethanol 98 parts by weight of antimony trioxide 0.09 parts by weight The mixture was heated at 170 to 220 ° C. for 180 minutes to perform a transesterification reaction. Next, the temperature of the reaction system was set to 245 ° C.
The reaction was continued for 180 minutes at a system pressure of 1.33 to 13.3 hPa, and the copolymerized polyester resin (A
2) was obtained. The intrinsic viscosity of this copolymerized polyester resin was 0.40 dl / g, the glass transition temperature was 80 ° C., and the specific gravity was 1.245.

The composition ratio of the constituent components of the copolymerized polyester resin (A2) by NMR analysis was as follows: acid component terephthalic acid 71 mol% isophthalic acid 29 mol% alcohol component ethylene glycol 49 mol% tricyclodecane dimethanol 51 mol%. .

A coating liquid for an infrared absorbing layer was prepared in the same manner as in Example 1 except that the above-mentioned copolymerized polyester resin (A2) was used as a polymer resin for an infrared absorbing layer, to obtain an infrared absorbing filter. The thickness of the infrared absorption layer after drying was 25 μm. The obtained infrared absorption filter is
The visual color was dark gray. The spectral characteristics were almost the same as those of Example 1.

However, the obtained infrared absorption filter was placed in an atmosphere of a temperature of 60 ° C. and a humidity of 95% RH for 500 hours.
After standing for a while, the spectral characteristics were measured again. The results were as shown in FIG. 7, the color tone changed to green, and the near-infrared absorption characteristics became extremely poor.

Comparative Example 3 As the polymer resin for the infrared absorbing layer, the copolymer polyester resin (A) used in Comparative Example 1 was used.
Except for using 2), a coating solution for an infrared absorbing layer was prepared in the same manner as in Example 2 to obtain an infrared absorbing filter. The thickness of the infrared absorption layer after drying was 25 μm. The color of the obtained infrared absorption filter was dark gray visually. FIG. 8 shows the spectral characteristics. As shown in FIG. 8, an infrared absorption filter was obtained in which the absorption was flat in the visible region from a wavelength of 400 nm to 650 nm and steeply absorbed at a wavelength of 700 nm or more.

However, the obtained infrared absorbing filter was placed in an atmosphere at a temperature of 60 ° C. and a humidity of 95% RH for 500 hours.
When left for a while, and the spectral characteristics were measured again, the result was as shown in FIG. 9, and the color tone changed to yellow-green.

(Comparative Example 4) As the polymer resin for the infrared absorbing layer, a copolymerized polyester resin (A3; glass transition temperature of 14) described in Example 1 of JP-A-9-888855.
A coating solution for an infrared absorbing layer was prepared in the same manner as in Example 1 except that 0 ° C., an intrinsic viscosity of 0.42, and a molecular weight of 45,000 were used to obtain an infrared absorbing filter. The thickness of the infrared absorption layer after drying was 25 μm. The color of the obtained infrared absorption filter was dark gray visually. The spectral characteristics were almost the same as those of Example 1. However, when the obtained infrared absorption filter was allowed to stand, it was curved. Further, the obtained infrared absorbing filter was subjected to a temperature of 60 ° C. and a humidity of 95% RH.
When left in the atmosphere for 500 hours, the infrared absorbing layer was completely peeled off from the PET film as the substrate.

[0140]

The infrared absorbing filter of the present invention has large and wide absorption in the near infrared region, has high light transmittance in the visible region, and has excellent environmental stability (high temperature or high humidity). Even when used under a long time, there is little change in spectral characteristics and color tone). In addition, there is an advantage that the workability and the productivity are good, and there is no curling even when left still. Therefore, optical devices such as video cameras and displays,
In particular, it is particularly suitable as an infrared absorption filter for a plasma display.

[Brief description of the drawings]

FIG. 1 is a diagram showing the spectral characteristics of an infrared absorption filter obtained in Example 1.

FIG. 2 shows the infrared absorption filter obtained in Example 1 at a temperature of 60.
FIG. 4 is a diagram showing spectral characteristics after being left in an atmosphere at 95 ° C. and a humidity of 95% for 500 hours.

FIG. 3 is a diagram illustrating spectral characteristics of an infrared absorption filter obtained in Example 2.

FIG. 4 shows the infrared absorption filter obtained in Example 2 at a temperature of 6
FIG. 5 is a diagram showing spectral characteristics after being left in an atmosphere of 0 ° C. and 95% humidity for 500 hours.

FIG. 5 is a diagram showing the spectral characteristics of the infrared absorption filter obtained in Comparative Example 1.

FIG. 6 shows the infrared absorption filter obtained in Comparative Example 1 at a temperature of 6
FIG. 5 is a diagram showing spectral characteristics after being left in an atmosphere of 0 ° C. and 95% humidity for 500 hours.

FIG. 7 shows the infrared absorption filter obtained in Comparative Example 2 at a temperature of 6;
FIG. 5 is a diagram showing spectral characteristics after being left in an atmosphere of 0 ° C. and 95% humidity for 500 hours.

FIG. 8 is a diagram showing the spectral characteristics of the infrared absorption filter obtained in Comparative Example 3.

FIG. 9 shows the infrared absorption filter obtained in Comparative Example 3 at a temperature of 6;
FIG. 5 is a diagram showing spectral characteristics after being left in an atmosphere of 0 ° C. and 95% humidity for 500 hours.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H048 CA04 CA12 CA24 4F100 AA20 AH04B AK41 AK41B AK51 AR00C AR00D AT00A BA02 BA03 BA04 BA10A BA10B BA10C BA10D CA30B DE04 EJ37 GB41 GB56 JD10B JN01A JN06C JN30D

Claims (14)

[Claims] 1. An infrared absorbing filter comprising an infrared absorbing layer mainly composed of an infrared absorbing dye and a polymer resin laminated on a transparent substrate, wherein the infrared absorbing filter contains at least a diimmonium salt compound as the infrared absorbing dye. The molecular resin is an alicyclic diol component represented by the general formula (1)
An infrared-absorbing filter, which is a polyester resin copolymerized by mol% or more and has a glass transition temperature of 85 to 130 ° C. Embedded image (In the formula, R ₁ and R ₂ represent a hydroxyl group and / or a hydroxyalkylene group having 1 to 8 carbon atoms and / or a hydroxyalkylene group having 1 to 4 carbon atoms, wherein alkylenoxide is 1 to
It shows a group added by 10 mol%. ) 2. An infrared absorbing filter, wherein the diimonium salt compound according to claim 1 has a structure represented by the general formula (2). Embedded image (Wherein, R _{1 to} R ₈ represent a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an aralkyl group, or an alkynyl group, and may be the same or different.
_{9 to} R ₁₂ represent a hydrogen atom, a halogen atom, an amino group, an amide group, a cyano group, a nitro group, a carboxylic acid group, or an alkyl group, and may be the same or different. Those capable of bonding a substituent at R _{1 to} R ₁₂ may have a substituent. X ^- represents an anion. ) 3. The method according to claim 1, wherein at least one of a phthalocyanine compound and a nickel complex compound is used as the infrared absorbing dye.
Infrared absorption filter as described. 4. An infrared absorption filter, wherein the phthalocyanine compound according to claim 3 is a fluorinated phthalocyanine compound. 5. The infrared absorption filter according to claim 3, wherein the nickel complex-based compound has a structure represented by the general formula (3). Embedded image (In the formula, R _{1 to} R ₄ represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, and an amino group.) 6. A compounding ratio of the infrared absorbing dye in the infrared absorbing layer is 0.5 to 0.0 part by weight of the phthalocyanine compound and 1.0 part by weight of the nickel complex compound per 1.0 part by weight of the diimmonium salt compound. The infrared absorbing filter according to any one of claims 3 to 5, wherein the amount is from 0 to 0.0 parts by weight. 7. The infrared absorption filter according to claim 1, wherein the infrared absorption layer is laminated on a transparent substrate by a coating method. 8. The infrared absorbing filter according to claim 1, wherein said transparent substrate is a polyester film. 9. The infrared absorbing layer according to claim 1, wherein the specific gravity of the polyester resin is in the range of 1.05 to 1.35, and the solubility of the infrared absorbing dye is 1% by weight or more. Infrared absorption filter as described. 10. The residual solvent amount of the infrared absorbing layer is 5.
The infrared absorbing filter according to any one of claims 1 to 9, wherein the content is 0% by weight or less. 11. The polyester resin according to claim 1, wherein the glass transition point temperature is 85 to 130 ° C.
11. The infrared absorption filter according to any one of items 10 to 10. 12. The infrared absorption filter according to claim 1, further comprising an antireflection layer as an outermost layer. 13. The infrared absorbing filter according to claim 1, further comprising an antiglare layer as an outermost layer. 14. An infrared absorption filter, wherein the filter according to claim 1 is installed on a front surface of a plasma display.