KR20110055731A - A mixture of diimonium compounds, method for synthesizing the same, a near infrared ray absorbing film comprising the same and an optical filter comprising the near infrared ray absorbing film for plasma display panel - Google Patents

Abstract

상기 식에서, n-Pr은 노르말 프로필기를 나타내고, iso-Bu는 이소부틸기를 나타내고, n은 0∼8의 정수를 나타낸다.Development of a near-infrared absorbing film containing a dimonium compound having a relatively broad absorption wavelength band of near infrared rays, having good heat resistance, moisture and heat resistance, and all other physical properties, and an optical filter for PDP using the same. A mixture of dimonium compounds having different n's of formula (1) is evaporated on a transparent support film, and a near-infrared absorbing film contained in an adhesive layer is prepared, and an optical filter for PDP is prepared using the same.

In the formula, n-Pr represents a normal propyl group, iso-Bu represents an isobutyl group, and n represents an integer of 0 to 8.

Description

A mixture of diimonium compounds, method for synthesizing the same, a near infrared ray absorbing film comprising a mixture of dimonium compounds, a method for synthesizing thereof, a near infrared absorbing film containing the same, and a near infrared absorbing film the same and an optical filter configure the near infrared ray absorbing film for plasma display panel}

The present invention provides a near-infrared absorbing film using a dimonium compound that absorbs light of a wavelength in the near-infrared region broadly and is excellent in heat resistance, moist heat resistance, and solvent solubility, and an optical filter for plasma display panel (hereinafter referred to as PDP) using the same. It is about.

Since near-infrared rays are used as beams for remote operation of electrical devices, devices that emit near-infrared rays may cause malfunctions of electrical devices installed in the vicinity, and near-infrared rays may be applied to the front of such devices (for example, PDPs). It is necessary to provide an optical filter or the like having a function of blocking.

The principle of the PDP is to apply a voltage to a rare gas (neon, xenon, etc.) enclosed in a cell between two sheets of glass, and the ultraviolet rays generated by the rare gas in the plasma state reaches the light emitting body coated on the cell wall. Although it generates the necessary visible light, it is harmful to people and electrical equipment such as orange light (hereinafter referred to as neon light) near the wavelength of 595 nm, which is caused by near-infrared rays, electromagnetic waves and neon gas and lowers the color purity of red light. Since it emits together, beneficial visible light transmits, but it is necessary to block harmful electromagnetic waves including near infrared rays, and therefore, PDP requires an optical filter.

The near-infrared absorbing film used for an optical filter is used for the purpose of blocking near-infrared rays, and the compound (near-infrared absorptive compound) which has a function which absorbs near-infrared rays is used for this. That is, by containing these near-infrared absorptive compounds in a layer provided on the surface of a transparent support film (a transparent functional film such as a transparent base film and an anti-reflective film or a film that blocks electromagnetic waves harmful to a human body (hereinafter referred to as an electromagnetic wave blocking film)). , A near infrared absorbing film is produced. There are several kinds of near-infrared absorptive compounds used herein, but are widely used dimonium compounds having a relatively broad absorption wavelength range of near-infrared rays alone or in combination with one or more other near-infrared absorbing compounds based thereon. However, many compounds having near-infrared absorptivity have insufficient heat stability and moisture-heat stability (hereinafter, both are simply referred to as 'thermal stability'), and the same applies to dimonium compounds. In addition, as a dimonium compound, the dimonium compound which has the antimony hexafluoride ion generally has been used, but this compound corresponds to a foreign substance, for the reason that the use regulation of heavy metals etc. becomes severe from environmental problems, etc. Safer dimonium compounds have been desired. As a means to solve this problem, a compound using an organic counterion such as naphthalenedisulfonic acid (Patent Document 1) and a compound using trifluoromethanesulfonic acid ion (Patent Document 2) are disclosed, but 'thermal stability' is still insufficient. In particular, in the case of the near infrared absorbing film in which these compounds are contained in the adhesive layer, the layer containing these compounds may be discolored, and the absorbance of the near infrared rays may be deteriorated.

As a main specific method of maintaining a near-infrared absorptive compound on a transparent support film, it melt | dissolves and / or disperse | distributes with a binder resin in a solvent, coats on a transparent resin film, and forms a polymeric resin layer, and the method included in an adhesion layer In the former case, there is a characteristic that the thermal stability is easily influenced by the glass transition temperature of the binder resin used and the amount of residual solvent in the resin layer, whereas in the latter method, the thermal stability is It is easy to fall, and there exists a characteristic that there exists a concern that it may adversely affect the haze value which is a criterion of transparency, and the transmittance | permeability of visible light.

As a technique for stabilizing the dimonium compound in a layer (overcoating layer, adhesive layer, processing layer, etc. using a polymer resin) provided on the transparent support film, a layer provided on the transparent support film in Patent Document 3 It is disclosed that the dimonium compound may be contained in a state in which the amount of remaining solvent in the solvent is controlled to a predetermined ratio or less, and stabilization can be achieved by using a binder resin having a high glass transition temperature. However, efforts to control the amount of remaining solvent have been disclosed. It is difficult to say that it is a simple method, such as there is a need and the binder resin to be used has limitation. Moreover, the method of effectively preventing a bad influence on the haze value and visible-light transmittance at the time of containing a dimonium compound in the adhesion layer provided on a transparent support film is not reported.

As a result, by using a dimonium compound having relatively good near infrared absorption ability, the near infrared absorbing film which does not inhibit the absorption ability to near infrared rays and its 'thermal stability', and does not limit the binder resin used and has excellent performance as an optical filter. It is desired to establish a simple manufacturing technique.

Literature List

Patent Document 1: Japanese Patent Application Laid-open No. Hei 10-316633 (Page 5)

Patent Document 2: Japanese Patent Application Publication No. Hei 7-51555 (Page 2)

Patent Document 3: Japanese Patent Application Publication No. 2000-227515

Patent Document 4: Japanese Patent Application Publication No. 43-25335 (pp. 7-14)

DISCLOSURE OF INVENTION

Problems to be Solved by the Invention

In the dimonium compound having a relatively broad absorption wavelength in the near infrared region, since the solvent solubility is good, it is easy to handle, and the width of the glass transition temperature (hereinafter referred to as Tg) of the binder resin that can be used is wide. Finding a dimonium compound that can maintain excellent 'thermal stability' even when included in the adhesive layer, can efficiently absorb near infrared rays, maintain a low haze value, and can be synthesized at low cost. It is a subject of this invention to provide the optical filter which has the outstanding performance used.

Means to solve the problem

MEANS TO SOLVE THE PROBLEM The present inventors conducted research in order to solve the said subject, and found out that the mixture of the dimonium compound which has a specific substituent on the cation side, and selected the specific thing as an anion can solve the said subject, The present invention has been completed.

That is, the present invention

(1) A near-infrared absorbing film represented by the following formula (1), wherein a mixture of two or more dimonium compounds in which n is different is contained in a layer formed on the transparent support film:

(In formula (1), n-Pr represents a normal propyl group, iso-Bu represents an isobutyl group, n represents an integer of 0-8.),

(2) Mixture of 2 or more types of dimonium compounds in which n in Formula (1) is different is 70% (calculated by mast spectrum) of dimonium compounds in which n is 3 to 6 in Formula (1). The near-infrared absorption film as described in (1) containing% or less,

(3) the near-infrared absorbing film as described in (1) or (2) whose layer formed on the transparent support film is an adhesion layer,

(4) (1) to (3), wherein the layer formed on the transparent support film contains a mixture of two or more dimonium compounds in which n of formula (1) is different and a compound having maximum absorption at a wavelength of 550 to 620 nm. The near-infrared absorbing film of any one of

(5) The near-infrared absorbing film in any one of (1)-(4) whose transparent support film is a film which has an anti-reflective function or an electromagnetic wave shielding function,

(6) an optical filter for plasma display panel, comprising the near-infrared absorbing film according to any one of (1) to (5),

(7) The optical filter for plasma display panel as described in (6) containing the near-infrared absorption film in any one of (1)-(5), the film which has an electromagnetic wave shielding capability, and / or the film which has an anti-reflective function,

(8) A mixture of two or more dimonium compounds represented by the following formula (1), wherein n is different:

(In formula (1), n-Pr represents a normal propyl group, iso-Bu represents an isobutyl group and n represents the integer of 0-8.)

It is about.

Effects of the Invention

Since the mixture of the dimonium compound used for this invention can be synthesize | combined at low cost by a simple method, and does not contain heavy metals, such as antimony, it is not a polar thing and since solvent solubility is good, it is easy to handle, The near-infrared absorbing film obtained by using the same absorbs near-infrared rays in the wavelength range of 1 to 1100 nm well, and exhibits excellent haze value and thermal stability 'even when it is contained in the adhesive layer. And the optical filter for PDP which combined this near-infrared absorbing film and another functional film without the deterioration of surface quality etc. shows the outstanding performance, and can fully respond to the said subject.

Carrying out the invention  Best embodiment for

Hereinafter, the present invention will be described in detail.

The near-infrared absorbing film of the present invention is a mixture of two or more kinds of dimonium compounds having different numbers of normal propyl groups and isobutyl groups, which are substituents of the dimonium compound represented by the formula (1) (hereinafter, 'the present dimonium mixture ') Is a near-infrared absorbing film in which the binder resin layer or the adhesive layer provided on the transparent support film has good physical properties as an optical film, and absorbs near-infrared rays in the wavelength range of 800 to 1100 nm.

The near-infrared absorbing film having the layer containing 'the present dimonium mixture' has good near-infrared absorptivity, excellent in thermal stability, and when included in the adhesive layer, all of the substituents of formula (1) are isobutyl group (n It is characterized by better near-infrared absorption ability and lower haze value than dimonium compound having = 0, and all of the substituents of formula (1) are more solvent soluble than (n = 8) dimonium compound of normal propyl group. We found that it was good and was easy to coat. In addition, a "this dimonium mixture" is easy to manufacture and can be easily manufactured by a well-known method by adjusting the ratio of the alkylating agent added to the manufacturing process of a precursor as demonstrated below.

The 'present dimonium mixture' according to the present invention can be obtained, for example, according to the method described in Patent Document 4. That is, the amino body represented by the following formula (2) obtained by the Uulman reaction and the reduction reaction is preferably in an organic solvent, preferably dimethylformamide (DMF), dimethylimidazolidinone (DMI) or N-methylpyrrolidone ( In a water-soluble polar solvent such as NMP), a mixture of a compound represented by the formula (3) by reacting a halogenated normal propyl compound and an isobutyl compound at an arbitrary ratio at 30 to 160 ° C, preferably 50 to 140 ° C Can be obtained. In addition, in order to control the ratio of the normal propyl group and the isobutyl group, first, a compound corresponding to a normal propyl group (or isobutyl group) is reacted, and then a compound corresponding to an isobutyl group (or normal propyl group) is reacted. It is also possible to synthesize a mixture of compounds in a proportion.

In the formula (3), n represents the same meaning as in the formula (1).

The mixture of the formula (3) synthesized above is in an organic solvent, preferably in a water-soluble polar solvent such as dimethylformamide (DMF), dimethylimidazolidinone (DMI) or N-methylpyrrolidone (NMP). , The oxidation reaction is carried out by adding 2 equivalents of tris (trifluoromethylsulfonyl) carbonic acid at 0 to 100 캜, preferably 5 to 70 캜, and the 'bone dimonium mixture' used in the present invention. Get

Next, the method of obtaining the composition ratio of each dimonium compound in a "this dimonium mixture" is demonstrated.

Mass for measuring the molecular ion peak intensity of each dimonium compound (nine dimonium compounds in which n is 0, 1, 2, 3, 4, 5, 6, 7 or 8 in formula (1)) As the analyzer, LCT manufactured by Micromas Corporation was used. The measurement sample for calculating the composition ratio of each dimonium compound is based on the compound of formula (3) (hereinafter referred to as precursor) before cationization, but this is a direct measurement of the 'bone dimonium mixture' after cationization This is because it is difficult, and there is no reliability of the measured value, and it can be judged that the composition ratio of each precursor is extremely correlated with the composition ratio of each component after cationization. Specifically, the electrospray (ESI) ionization mass spectrum of the sample for measurement was measured, and the molecular ion peak intensity [M] ⁺ of each precursor was calculated | required, and the composition ratio was computed. The composition ratio A of each component was estimated and calculated from A (%) = 100x [M] ⁺ // (n is the sum of [M] ⁺ of each precursor of 0-8). In addition, for example, the sum of the composition ratios of the components of n to 3 to 6 is equal to (%) = 100 x (n is the sum of [M] ⁺ of each precursor of 3 to 6) / (n is 0 The sum of [M] ⁺ of each precursor of ˜8).

The sum of the composition ratios of the n = 3 to 6 dimonium compounds calculated as described above from the peak intensity of the mass spectrum is 98% at 70% or more of the total (the sum of the respective dimonium compounds where n is 0 to 8). The following mixture is a more preferable mixture for the purpose of the present invention. Such a composition can be easily manufactured by adjusting the addition amount, reaction temperature, and reaction time of an alkylating agent in the above.

The present 'dimonium mixture' used in the present invention may be used alone, or may be used in combination with one or more other near-infrared absorbing compounds in order to adjust the absorption wavelength range and the absorption ratio of the desired near-infrared rays, and other near-infrared rays that can be used. Specific examples of the absorbing compound include dimonium compounds, nitrone compounds, metal salts, cyanine compounds, squaraineium compounds, thiol nickel complex salt compounds, phthalocyanine compounds, and naphthalocyanine compounds other than the present dimonium mixture. Compounds, triallyl methane compounds, naphthoquinone compounds, anthraquinone compounds, and the like. In this invention, it is preferable to select and use the compound which has maximum absorption in these wavelengths from these compounds at 800-1100 nm.

Hereinafter, the method of forming a near-infrared absorbing film by forming the layer containing a "this dimonium mixture" on a transparent support film is demonstrated. In addition, when using a near-infrared absorption compound other than a "bone dimonium mixture" together, the method of mixing and coating in the same coating liquid as the "bone dimonium mixture" is advantageous, but it is the same by a well-known method as a separate layer. It can also hold | maintain in a transparent support film.

As a method of holding a "this dimonium mixture" on a transparent support film, the method of forming a coating layer (henceforth a binder resin layer) using a binder resin, making it contain in it, and including in an adhesion layer This is a preferable method.

The transparent support film used in the present invention is not particularly limited in type and thickness as long as the transparent support film is high in transparency, does not easily scratch, and is durable in use as an optical film. Preferably, about the kind of film, there exists a polymer resin film, such as polyester type, a polycarbonate type, a triacetate type, norbornene type, an acryl type, a cellulose type, a polyolefin type, or a urethane type, and has physical properties as optical films, such as transparency. And polyethylene terephthalate (hereinafter referred to as PET) in view of availability and the like. In order to absorb ultraviolet rays from the outside and stabilize the function of the inner member, a transparent support film containing an ultraviolet absorbing material may be used, and the surface of the film may be corona discharged or plasma treated to increase adhesion with the coating film. , Glow discharge treatment, roughening treatment or chemical treatment, and coating with an anchor coating agent and a primer may be improved.

In addition, the transparent support film may be a transparent support film having a single or a plurality of functions such as anti-reflective property, anti-glare / reflective property, antistatic property, anti-fouling property, neon light absorbing property, electromagnetic wave blocking property, color tint or the like. In particular, when the 'dimonium mixture' is contained in the adhesive layer of these functional transparent support films, an optical film having both of these functions and near infrared absorptivity is obtained. It is possible and using a functional transparent support film is an advantageous choice. As a functional transparent support film, the transparent support film which has an anti-reflective function or an electromagnetic wave blocking function is preferable.

Next, although the example of the preferable functional transparent support film mentioned above is demonstrated, the kind of the transparent support film which has functionality is not limited to these.

A transparent support film having an anti-reflective function (anti-reflective film) is a film or transparent support film which suppresses light reflection from the outside by coating a low refractive index agent with a binder resin and other additives on the surface of a transparent support film such as PET. Hard coating layer and high refractive index layer between the layer and the low refractive index layer, and control to remove the reflected light by each layer to improve the visibility, anti-glare, anti-reflective film is a high reflection film It is a film which contains fine particles in a refractive index layer and a hard coat layer, and diffuses | reflects the light from the exterior, and improves visibility. These films can be easily purchased from the market as an arc top series (made by Nippon Kayaku Co., Ltd.), a kayak coat ARS series (manufactured by Nippon Kayaku Co., Ltd.), a kayak coat AGRS series (manufactured by Nippon Kayaku Co.), and a rear look series (manufactured by Nihon Yushi Co., Ltd.). have.

Next, in the transparent support film (electromagnetic wave blocking film) which has an electromagnetic wave shielding function, the method of blocking an electromagnetic wave includes the mesh type which hold | maintained the micro fine wire of metals, such as copper, on the transparent support film in geometrical form like a mesh, and light There is a thin film type in which an ultra-thin metal film is held on a transparent base film in a range having transparency, but in the case of a PDP, a near-infrared absorbing film is required when the thin film type is used (it is generally not transmitted because the near infrared rays are reflected). I never do that. Therefore, in this invention, when using an electromagnetic wave shielding film, it is preferable to use the electromagnetic wave shielding film of a mesh type as a transparent support film. In addition, when a film having an anti-reflective property and an electromagnetic wave shielding property obtained by applying an electromagnetic wave shielding layer on a mesh surface by a screen printing method or the like on the opposite side of the anti-reflective surface of the anti-reflective film is used as a transparent support film, It is preferable in manufacturing an optical filter.

As the transparent support film having other functionalities that can be used in the present invention, there are transparent support films in which functions such as neon light absorbency, ultraviolet absorbency, antistatic property, antifouling property, color tone, etc. are maintained alone or in plurality. It can manufacture according to the method well-known by itself by the method of forming from the binder resin composition containing each compound which has these performance.

First, the method of including the 'bone dimonium mixture' in the adhesive layer will be described. The resin mainly used as the adhesive layer is not particularly limited as long as it can uniformly disperse the 'bone dimonium mixture', forms a transparent layer on the surface of the transparent support film, and impairs its function as an optical film. And adhesive resins such as polyester, polyamide, polyurethane, polyolefin, polycarbonate, rubber or silicone resins, and acrylic resin adhesives are preferred in that they are excellent in transparency, adhesiveness, heat resistance and the like. The acrylic resin adhesive material is made by copolymerizing an acrylic acid alkyl ester having no functional group (preventing double bonds) as a main component and an acrylic acid alkyl ester having a functional group and other monomer components other than the acrylic acid alkyl ester. The copolymerization ratio of the monomer component other than the acrylic acid alkyl ester and the acrylic acid alkyl ester having the functional group is 0.1 to 20 parts by weight, more preferably 1 to 10 parts by weight per 100 parts by weight of the acrylic acid alkyl ester component having no functional group. It is wealth.

Examples of the acrylic acid alkyl ester having no functional group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and (meth) acrylic acid Acrylic acid alkyl esters having 1 to 12 carbon atoms of alkyl groups, such as heptyl, octyl (meth) acrylate, nonyl (meth) acrylate, (meth) acrylate, undecyl (meth) acrylate, or dodecyl (meth) acrylate, to meta Although there are acrylic acid alkyl esters, these may use two or more types together as needed.

As monomers other than the acrylic acid type alkyl ester or acrylic acid type alkyl ester which have a functional group, what functions as a crosslinking point with a crosslinking agent mentioned later, etc. are used, Although it does not specifically limit about the kind, 2- (meth) acrylate 2-hydroxyl ethyl , Amino group-containing (meth) acrylic acid monomers such as hydroxy group-containing (meth) acrylic acid ester monomers such as hydroxypropyl (meth) acrylate, N, N-dimethylaminoethyl acrylate, N-tert-butylaminoethyl acrylate, Or acrylic acid, maleic acid, etc. are mentioned, These may use two or more types together as needed.

It is preferable to use an adhesive in the composition which can bridge | crosslink the said acrylic acid type resin etc. by mix | blending a crosslinking agent. As a crosslinking agent, it is used suitably according to the kind of the said monomer, For example, aromatic diisocyanates, such as aliphatic diisocyanate, such as hexamethylene diisocyanate and the trimethylolpropane adduct of hexamethylene diisocyanate, a trilene diisocyanate, or a triylene diisocyanate, etc. Polyisocyanate compounds such as isocyanates, melamine compounds such as butyl etherated styrolmelamine, trimethylolmelamine, diamine compounds such as hexamethylenediamine or triethylenediamine, epoxy resin compounds such as bisphenol A and epichlorohydrin, urea resin compounds, Metal salts, such as aluminum chloride, ferric chloride, or aluminum sulfate, etc. are used, The compounding quantity is 0.005-5 weight part normally per 100 weight part of acrylic resin adhesives, Preferably it is 0.01-3 weight part.

The acrylic resin-based adhesive material is preferable because of its excellent adhesive strength and cohesive force and high stability to light and oxygen because there is no unsaturated bond in the polymer after crosslinking, and also because of the high degree of freedom in the type of monomer and the molecular weight selection. In order to maintain adhesiveness to the transparent support film, one having a high molecular weight (polymerization degree), that is, a weight average molecular weight (MV) of the main polymer is preferably about 600,000 to 2 million, more preferably about 800,000 to 1.8 million to be.

In the PDP, neon light having a wavelength of 550 nm to 620 nm originating from a neon gas generated when applying a voltage needs to be cut to some extent on the front of the display because the color purity of the red light is lowered. Although a neon light absorption filter held on a transparent support film is usually used, a method of obtaining a layer capable of simultaneously absorbing near infrared light and neon light by containing a compound having neon light absorbing power in a layer having near infrared light absorbing power is advantageous. Examples of the neon light absorbing compound that can be used include, for example, azaporphyrin-based, cyanine-based, squaraine-based, azomethine-based, xanthene-based, oxonol-based, or azo-based compounds. It is necessary to pay full attention to the 'thermal stability' of the 'dimonium mixture' used. For example, the tetraaza porphyrin-based compound is relatively stable and can be used as long as it can stabilize other compounds.

The 'dimonium mixture' is discolored by contact with the adhesive, the polymerization initiator, the crosslinking agent, the ultraviolet absorber, the colorant dye and other necessary additives, such as the metal used in the electromagnetic shielding mesh, which are the main components of the adhesive. In the case of forming a pressure-sensitive adhesive liquid, it is sufficiently dissolved or dispersed in a solvent such as methyl ethyl ketone (MEＫ) together with an antioxidant, a rust inhibitor, etc., and the layer thickness after drying is 5 to 100 μm, preferably 10, on the surface of the transparent support film. Coating is carried out so that it may become -50 micrometers. The coating method is not particularly limited, and is applied by a bar coater, a reverse coater, a comma coater, a gravure coater, or the like, dried to adhere the adhesive layer, and a bar coater, a reverse coater, a comma coater and the adhesive liquid on a release film. And a method of transferring the adhesive layer onto the transparent support film after coating with a gravure coater or the like and drying. The amount of solvent used depends on the coating method, but when the weight average molecular weight of the main polymer uses an acrylic resin pressure sensitive adhesive of around 1 million and is applied by a comma coater, the pressure sensitive adhesive is diluted to 10 to 25% by weight. It is desirable to. It is preferable that the near-infrared absorbing film of this invention is designed so that the transmittance | permeability of the near-infrared ray with a wavelength of 800-1100 nm may be 10% or less, and the "this dimonium mixture" may also use the quantity according to it, and it is about 1 with respect to an adhesion layer. What is necessary is just to contain so that it may become -20 weight%.

Although this dimonium mixture is a mixture of two or more types of dimonium compounds, it is used abundantly as a solvent at the time of coating in the single product (n = 8 in Formula (1)) of the dimonium compound of eight normal propyl groups. The solubility in solvents, such as ME ', which is not sufficient, tends to cause aggregates on the coating surface, and tends to have poor near-infrared absorptivity. When n is large, it becomes difficult to coat because solvent solubility worsens as it becomes a mixture with a high ratio of the dimonium compound with many normal propyl groups. In addition, when all eight are isobutyl groups (n = 0 in Formula (1)), the near-infrared absorptivity is slightly worse than the "bone dimonium mixture", the haze value is also high, and the "bone dimonium mixture" In particular, when n is small, the haze value tends to increase as the content ratio of the dimonium compound with many isobutyl groups increases. As described above, the 'bone dimonium mixture' is better in terms of physical properties or ease of handling than using a single product having 8 normal propyl groups and 8 isobutyl groups, and also in either of the 'bone dimonium mixtures'. Mixtures of compounds which are not excessively unbiased are more suitable, and the sum of the composition ratios of the dimonium compounds in which n is 3 to 6 calculated from the peak intensity of the mass spectrum described above is the total (n is the sum of the composition ratios of 0 to 8). More preferably 70% or more and 98% or less.

Next, the method of holding "this dimonium mixture" as a binder resin layer on a transparent support film is demonstrated.

This dimonium mixture is dissolved in a solvent together with a binder resin and, if necessary, neon light absorbing dyes, color tone dyes, leveling agents, charging agents, antioxidants, dispersants, flame retardants, lubricants, plasticizers, ultraviolet absorbers, and other additives. And / or disperse | distribute to a coating liquid, the method of coating with a coating machine, and drying can be used. In the case of using a binder resin such as thermosetting or active energy ray curability, a curing step is required after drying, but deterioration of absorbing compounds of near infrared rays and neon light may occur due to heat of curing and active energy rays, and the process increases. It is preferable to use thermoplastic binder resin unless there is special circumstances.

As binder resin, it is easy to coat, adhesiveness with a transparent support film is good, visible light transmittance is good, and if there is no problem in surface quality etc., it will not specifically limit, but it is polyester resin, acrylic resin, polyamide resin, polyurethane type from the ease of handling. It is preferable to select from thermoplastic resins, such as resin, polyolefin resin, or polycarbonate resin. After coating and winding onto a roll, the choice of materials that have a glass transition temperature and other properties that do not cause problems such as blocking during storage and that do not adversely affect the 'thermal stability' of the 'dimonium mixture' used desirable.

Examples of the solvent include alcohols such as methanol, ethanol, isopropanol, diacetone alcohol, ethyl cellosolve or methyl cellosolve, ketones such as acetone, methyl ethyl ketone (ME '), cyclopentanone or cyclohexanone, N, Amides such as N-dimethylformamide or N, N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane or ethylene glycol monomethyl ether, methyl acetate, ethyl acetate or Esters such as butyl acetate, aliphatic hydrocarbons such as chloroform, methylene chloride, dichloroethylene or trichloroethylene, aromatics such as benzene, toluene, xylene, monochlorbenzene or dichlorbenzene, or n-hexane, n-heptane Aliphatic hydrocarbons such as fluorine-based solvents such as tetrafluoropropyl alcohol or pentafluoropropyl alcohol, etc. may be used. It is preferable to select a solvent which is high in dissolving power for each material, which is suitable for coating, drying, and the like, and which has no problems with safety.

Among the additives used as necessary, the same compound as the light contained in the pressure-sensitive adhesive layer is used as the neon light absorbing compound, and in consideration of the 'thermal stability' and the desired quality performance of the 'dimonium mixture' used for other additives. It is used while being contained in the solution.

Coating of coating liquid is finish by well-known coating methods, such as the flow coating method, the spray method, the bar coating method, the gravure coating method, the roll coating method, the blade coating method, the air knife coating method, the lip coating method, or the die coating method. Is applied so as to have a layer thickness of usually 0.1 to 30 m, preferably 0.5 to 10 m, and the treated layer is fixed by drying. In addition, when hardening is required separately, it hardens after drying and a process layer is fixed. As the barrier property of the near infrared ray, it is preferable that the transmittance of the near infrared ray having a wavelength of 800 to 1100 nm is 10% or less, similarly to the case where the 'bonded dimonium mixture' is contained in the adhesive layer. The amount of solvent used varies depending on the coating method, but when the weight average molecular weight of the main polymer is used with a thermoplastic acrylic resin binder of around 300,000, and is applied with a microgravure coater, the solvent is diluted with a solvent so as to be 15 to 30% by weight. It is desirable to.

When a dimonium compound is contained in a binder resin layer, the dimonium compound which uses the most commonly used antimony hexafluoride ion as an anion, such as Kayasolve IRG-022 (brand name; the product made by Nippon Kayaku Co.) and many diimos In the case of using a binder resin having a low Tg of 85 ° C. or lower, as described in Patent Literature 3, the thermal stability deteriorates. However, in this dimonium mixture, a binder resin of 85 ° C. or lower may be used. Moreover, it does not require management of the amount of the residual solvent in the binder resin layer as disclosed in patent document 3, and can be used also without drying also by normal drying conditions. In addition, in this formula (1), since all substituents are excellent in solvent solubility compared with the single product of a normal propyl group (n = 8), in this formula (1), it is easy to handle, It is possible to obtain a near-infrared absorbing film excellent in the method in which the 'nium mixture' is contained in the binder resin layer.

Next, the optical filter of the present invention is a transparent transparent film having the following functions as a minimum component of the near-infrared absorbing film of the present invention provided with a layer containing a 'bone dimonium mixture' on a transparent support film. It is obtained by laminating or bonding a support film. Preferred uses of these optical filters are for PDPs, and the optical filters of the present invention may be pasted together to a transparent glass plate and a plastic plate to the front of the PDP, or may be directly bonded to the front of the PDP.

Examples of the structure of various films in the optical filter of the present invention include examples of the following (1) to (13).

In the following description, NIRA indicates near infrared absorptivity, NeA indicates neon light absorptivity, and the part indicated by braces ({}) indicates the near infrared absorbing film of the present invention, and the part indicated by parentheses (()) indicates functional films other than the present invention. Respectively. As can be clearly seen from these structural examples, for example, two kinds of compounds are contained in the adhesive layer of the transparent support film having the same functionality as the anti-reflective transparent support film by containing the 'mixed dimonium mixture' and the neon light absorbing compound. The optical filter for PDP can be manufactured only by bonding a film. Furthermore, by using the film which blocked the electromagnetic wave of the mesh on the back surface of an anti-reflective film as a transparent support film, providing the binder resin layer and an adhesive layer which contain the "bone dimonium mixture" and a neon light absorber on the mesh surface, 1 It is also possible to manufacture an optical filter for PDP with a kind of film. As an optical filter of this invention, the form containing the near-infrared absorption film of this invention, the film which has an electromagnetic wave shielding ability, or the film which has an anti-reflective function is preferable.

(1) {anti-reflective film / NIRA, NeA, color adjustment adhesive layer} / (electromagnetic wave blocking film / adhesive layer),

(2) {anti-reflective film / NIRA, color adjustment adhesion layer} / (electromagnetic wave blocking film / NeA adhesion layer),

(3) (anti-reflective film / adhesive layer) / {electromagnetic wave blocking film / NIRA, NeA, color adjustment adhesion layer},

(4) {anti-glare, anti-reflective film / NIRA, NeA, color adjustment adhesive layer} / (electromagnetic wave blocking film / adhesive layer),

(5) (anti-reflective film / adhesive layer) / {NIRA, NeA binder resin layer / PET / color adjustment adhesion layer} / (electromagnetic wave blocking film / adhesive layer),

(6) (anti-reflective film / adhesive layer) / {NeA film / NIRA, color adjustment adhesion layer} / (electromagnetic wave blocking film / adhesive layer),

(7) (anti-reflective film / adhesive layer) / (electromagnetic wave blocking film / adhesive layer) / {NeA film / NIRA, color adjustment adhesive layer},

(8) (Anti-reflective film / adhesive layer) / (electromagnetic wave blocking film) / {NIRA, NeA absorption adhesion layer / PET / color adjustment adhesion layer},

(9) (anti-reflective film / adhesive layer) / {NIRA, NeA binder resin layer / PET / color adjustment adhesion layer} / (electromagnetic wave blocking film / adhesive layer),

{10 Anti-reflective film / NIRA, NeA binder resin layer / color adjustment adhesion layer} / (electromagnetic wave blocking film / adhesion layer)

{11 Anti-reflective film / NIRA / NeA binder resin layer / color adjustment adhesion layer} / (electromagnetic wave blocking film / adhesive layer)

{12 antireflection film / electromagnetic wave shielding layer / NIRA binder resin layer / NeA adhesion layer}

{13 Anti-reflective film / electromagnetic wave shielding layer / NIRA, NeA adhesion layer}

Example

In the following Examples, the present invention will be described in more detail, but the present invention is not limited to such examples. In addition, in an Example, a part means a weight part and% means weight%, respectively.

Synthetic example  One

(Substitution reaction)

N, N, N ', N'-tetrakis (aminophenyl) -p-phenylenediamine 7 parts in DMF 100 parts, potassium carbonate 27 parts, potassium iodide 14.8 parts, isobutyl bromide 32 parts, 1-bromopropane 3 parts were added, it was made to react at 90 degreeC for 2 hours, and it was made to react at 110 degreeC for 6 hours. The crystals precipitated after cooling are separated by filtration, and the obtained crystals are dissolved in thermal DMF. After removing the insoluble fraction, methanol was added to the solution, the precipitated crystals were separated by filtration, washed with water, and dried to obtain 6.8 parts of a precursor of pale green crystals (see Chemical Formula (3) above).

(Oxidation reaction)

5 parts of the precursor crystals were added to 40 parts of DMF, and heated and dissolved at 60 ° C. Then, 9 parts of a 58% aqueous solution of tris (trifluoromethanesulfonyl) carbonic acid was added, and then 1.9 parts of nitric acid dissolved in 30 parts of DMF was added. The mixture was heated and stirred for a minute. After insoluble fraction was separated by filtration, water was added to the reaction solution, and the resulting crystals were filtered, washed with water and dried to obtain 5.2 parts of a mixture of dimonium compounds. The composition ratio of each component in this mixture was calculated by the above method, and the results are shown in Table 1. The maximum absorption wavelength of this mixture was 1107 nm (dichloromethane).

Synthetic example  2

(Substitution reaction)

Substituted reaction and purification were carried out in the same manner as in Synthesis Example 1, except that 3 parts of 1-bromopropane of Synthesis Example 1 was changed to 7.3 parts, thereby obtaining 6.5 parts of a precursor of pale green crystals.

(Oxidation reaction)

Oxidation reaction and purification were carried out in the same manner as in Synthesis Example 1, except that the precursor obtained in Synthesis Example 1 was changed to the precursor, to obtain 4.5 parts of a mixture of dimonium compounds. The composition ratio of each component in this mixture was computed by the said method, and the result is shown in Table 1. The maximum absorption wavelength of this mixture was 1092 nm (dichloromethane).

Synthetic example  3

(Substitution reaction)

Substitution reaction and purification were carried out in the same manner as in Synthesis Example 1, except that 3 parts of 1-bromopropane in Synthesis Example 1 was changed to 6.2 parts of precursors of pale green crystals.

(Oxidation reaction)

Oxidation reaction and purification were carried out in the same manner as in Synthesis Example 1, except that the precursor of Synthesis Example 1 was changed to the precursor, thereby obtaining 6.1 parts of a mixture of dimonium compounds. The composition ratio of each component in this mixture was computed by the said method, and the result is shown in Table 1. The maximum absorption wavelength of this mixture was 1103 nm (dichloromethane).

Synthetic example  4

(Substitution reaction)

Substitution reaction and purification were carried out in the same manner as in Synthesis Example 1, except that 3 parts of 1-bromopropane of Synthesis Example 1 was changed to 7.6 parts of pale green crystal precursors.

(Oxidation reaction)

Oxidation reaction and purification were carried out in the same manner as in Synthesis Example 1, except that the precursor of Synthesis Example 1 was changed to the precursor, thereby obtaining 5.4 parts of a mixture of dimonium compounds. The composition ratio of each component in this mixture was computed by the said method, and the result is shown in Table 1. The maximum absorption wavelength of this mixture was 1101 nm (dichloromethane).

The ratio of each component in the mixture of the dimonium compound obtained by the synthesis examples 1-4 was put together in Table 1.

(Solvent solubility)

Solvent solubility of the dimonium compound obtained by the synthesis examples 1-4 and the dimonium compound used by the following comparative examples 1, 2, and 3 was measured by the following method.

A 5% methyl ethyl ketone solution of the target dimonium compound was prepared at room temperature, and the dissolved state was observed. As a result, the dimonium compound used in Synthesis Examples 1 to 4 and Comparative Examples 2 and 3 was in a transparent state, while the dimonium compound used in Comparative Example 1 was not completely dissolved and precipitates were observed.

Composition Formula (1)
n Composition ratio (%) Synthesis Example 1 Synthesis Example 2 Synthesis Example 3 Synthesis Example 4 0 14.8 0.1 0.0 0.0 One 32.1 1.6 0.2 0.0 2 31.5 12.6 2.7 0.2 3 16.0 31.1 14.6 1.9 4 3.9 34.0 24.0 11.3 5 1.3 17.2 23.5 26.2 6 0.3 3.2 21.8 37.7 7 0.1 0.2 12.0 20.3 8 0.0 0.0 1.2 2.5

Example 1

(Production of Near Infrared Absorption Film 1)

The coating liquid which mixed and melt | dissolved each raw material shown in following Table 2 so that it may become uniform was coated with a comma coater on the MRF-75 (brand name, PET peeling film, the Mitsubishi Chemical Co., Ltd. make), and dried at 0.8 m / min. At 110 degreeC, it coated so that the thickness of an adhesion layer might be set to 18 micrometers, and the adhesion layer was formed. Then, on the opposite side of the anti-reflective surface of KAYACOAT ART-D501 (trade name, anti-reflective film, manufactured by Nippon Kayaku Co., Ltd.), the PET peeling film provided with an adhesive layer was press-pressed by a roll, and has anti-reflective properties and neon light intensity. The near-infrared absorbing film 1 of this invention which absorbs was obtained.

material usage Mixture of Dimonium Compounds of Synthesis Example 1 1.00part TAP-2 (brand name neon light absorbent, Yamada Gakuku Kogyo) 0.09part Tinuvin 109 (brand name ultraviolet absorber, product made by Shiba GI) 0.57part PTR-104 (brand name acrylic resin, product of Nippon Kayaku) Part 103.00 Coronate HL (brand name hardener, Nippon Polyurethane) 0.023part MEK 64.00 copies

TAP-2; Tetraaza porphyrin type compound, thyneubin 109; Benzotriazole type compound, Coronate HL; Isocyanate type hardening | curing agent

Example 2

(Manufacture of a near infrared absorbing film 2)

Except for using the mixture of the dimonium compound of Synthesis Example 2 instead of the mixture of the dimonium compound of Synthesis Example 1 of Example 1 in the same manner as in Example 1 and having an anti-reflective and absorbing neon light The near infrared absorbing film 2 was obtained.

(Manufacture of Optical Filter 1 for PDP)

Peeling off the protective film of ES-1534 (HCD-42-02) A (brand name, an electromagnetic wave blocking film, the Hitachi Chemical Industry Co., Ltd.), bonding the said near-infrared absorbing film 2 with an adhesion layer on it, and the optical for PDP of this invention A filter was obtained. Even if the filter was directly bonded to the front surface of the PDP module or bonded to a glass plate (transparent plate) and installed in front of the module, the filter sufficiently exhibited the required performance as an optical filter for PDP.

Example 3

(Production of Near Infrared Absorption Film 3)

Except for using the mixture of the dimonium compound of Synthesis Example 3 instead of the mixture of the dimonium compound of Synthesis Example 1 of Example 1 in the same manner as in Example 1 and having an anti-reflective and absorbing neon light The near infrared absorbing film 3 was obtained.

(Manufacture of optical filter 2 for PDP)

Peeling off the protective film of ES-1534 (HCD-42-02) A (brand name, an electromagnetic wave blocking film, the Hitachi Chemical Industry Co., Ltd.), bonding the said near-infrared absorption film 3 on it through an adhesion layer, and PDP of this invention An optical filter was obtained. Even if the filter was directly bonded to the front surface of the PDP module through the adhesive layer of the electromagnetic wave shielding film, or bonded to the glass plate and installed in front of the module, the filter sufficiently exhibited the required performance as an optical filter for PDP.

Example 4

(Production of Near Infrared Absorption Film 4)

Except for using the mixture of the dimonium compound of Synthesis Example 4 instead of the mixture of the dimonium compound of Synthesis Example 1 of Example 1 in the same manner as in Example 1 and having an anti-reflective and absorbing neon light The near infrared absorbing film 4 was obtained.

Example 5

(Production of Near Infrared Absorption Film 5)

0.5 part of the mixture of the dimonium compound of the synthesis example 2, and 37 parts of Foret PAN-125 (brand name, acrylic binder resin of Tg70 degreeC, the agent make) made into 40 parts of MEE 'were obtained, and the coating liquid was obtained. This coating solution was coated on a Cosmoshine A4300 (trade name, 100 micron thick polyester film, manufactured by Toyoboseki) at a line speed of 10 m / min using a microgravure roll with a microgravure coater at 70 to 130 ° C. It dried and the near-infrared absorption film 5 of this invention containing the mixture of the dimonium compound of the synthesis example 2 in the binder resin layer was obtained.

Comparative Example 1

In the same manner as in Synthesis Example 1, except that 32 parts of isobutyl bromide of Synthesis Example 1 and 44.7 parts of 1-bromopropane were used, all eight substituents in the formula (1) were normal profiles. After preparing the dimonium compound which is a group, the comparative near-infrared absorbing film was obtained by the same method as Example 1 except using this instead of the mixing part of the dimonium compound of the synthesis example 1.

Comparative Example 2

Except for using 44.7 parts of isobutyl bromide in place of 32 parts of isobutyl bromide and 12.7 parts of 1-bromopropane of Synthesis Example 1, all 8 substituents in Formula (1) are isobutyl groups A comparative near-infrared absorbing film was obtained in the same manner as in Example 1 except that an immonium compound was prepared and used instead of the mixed portion of the dimonium compound of Synthesis Example 1.

Comparative Example 3

Example 5 Synthesis Example 2 The same as in Example 5 except for using the same amount of Kayasolb® IRG-022 (trade name, dimonium compound of antimony hexafluoride anion, manufactured by Nippon Kayaku Co., Ltd.) in place of the mixture of dimonium compound of Synthesis Example 2 The comparative near-infrared absorbing film containing a near-infrared absorber in the binder resin layer was obtained by the method.

Performance test (1) (Near infrared absorbing film in which near-infrared absorber is contained in adhesion layer)

Transmittance and visual permeability at each maximum absorption wavelength when each test piece of the near-infrared absorbing film obtained in Examples 1-4 and the comparative near-infrared absorbing film obtained in each of Comparative Examples 1 and 2 was stored for 500 hours in an 80 degreeC thermostat. (Ｙ%) and the change in chromaticity coordinates (ｘ, ｙ) were measured, and the heat resistance of each test piece was compared. In addition, the transmittance | permeability is measured with # -3150 (brand name, a spectrophotometer, the Shimadzu Seisakusho company), and the visual permeability and chromaticity coordinates (y, y) are the display methods of the color by the "Ki colorimeter" of ISO8701 from this transmittance. Calculated according to. In addition, haze value was measured by TC-H3DP '(brand name, haze meter, Tokyo Color Technology Center). In addition, the appearance change was visually observed.

The results of the performance test (1) are summarized in Table 3.

Performance test result (1) <heat resistance> Storage time Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Haze value
(%) 4.0 2.9 2.3 2.4 11.1 5.6 Wavelength 950nm
Transmittance (%) 0 hours 3.47 1.58 1.43 1.25 25.09 6.18 500 hours 3.39 1.00 1.71 1.31 33.31 5.45 car 0.08 0.58 -0.28 -0.06 -8.22 0.73 Visual transmittance
Y (%) 0 hours 48.660 48.304 49.615 48.878 51.477 48.917 500 hours 48.228 48.872 49.842 48.951 51.897 48,757 car 0.432 -0.568 -0.227 -0.073 -0.42 0.16 Chromaticity coordinates
x 0 hours 0.302 0.307 0.299 0.301 0.288 0.305 500 hours 0.302 0.304 0.296 0.299 0.285 0.303 car 0.000 0.003 0.003 0.002 0.003 0.002 Chromaticity coordinates
y 0 hours 0.314 0.312 0.305 0.307 0.299 0.315 500 hours 0.315 0.314 0.305 0.306 0.297 0.317 car -0.001 -0.002 0.000 0.001 0.002 -0.002 Appearance change 500 hours No change No change No change No change With aggregate No change

(Consideration) The comparative example 1 using the dimonium compound whose n is 8 in the said General formula (1) has a high haze value, and the aggregate also generate | occur | produced. Moreover, the comparative example 2 which used the dimonium compound whose n is 0 in the said General formula (1) had a bad haze value, and its near-infrared absorptivity was also bad. On the other hand, the near-infrared absorbing films of Examples 1 to 4 using a mixture of two or more dimonium compounds in which n is different from the present invention have practical results, but in particular, in the formula (1), n is 3 to 3. The near-infrared absorbing films of Examples 2 to 4 each having a mixture of dimonium compounds having a sum of six components of 70% or more in the pressure-sensitive adhesive layer were less than 70% or less in the haze value and the near-infrared blocking rate (Example 1). Excellent. Moreover, also about the test result about moisture-heat resistance (60 degreeC, RH90%, 500 hours), the same result as the above appeared. The results of the heat and humidity resistance are summarized in Table 4.

Performance test result (1) <moisture heat resistance> Storage time Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Haze value
(%) 4.0 2.9 2.3 2.4 11.1 5.6 Wavelength 950nm
Transmittance (%) 0 hours 3.50 1.57 1.46 1.30 25.50 5.90 500 hours 3.41 1.01 1.76 1.28 33.30 5.40 car 0.09 0.56 -0.30 0.02 -7.80 0.50 Visual transmittance
Y (%) 0 hours 48.550 48.250 49.680 49.010 51.889 48.904 500 hours 48.318 48.697 49.772 49.119 52.609 48,814 car 0.232 -0.447 -0.090 -0.109 -0.72 0.09 Chromaticity coordinates
x 0 hours 0.302 0.307 0.299 0.301 0.288 0.305 500 hours 0.302 0.305 0.296 0.299 0.286 0.302 car 0.000 0.002 0.003 0.002 0.002 0.003 Chromaticity coordinates
y 0 hours 0.314 0.312 0.305 0.307 0.299 0.315 500 hours 0.314 0.313 0.306 0.307 0.297 0.316 car 0.000 -0.001 -0.001 0.000 0.002 -0.001 Appearance change 500 hours No change No change No change No change With aggregate No change

Performance test (2) (near-infrared absorption film which a near-infrared absorber contains in a binder resin layer)

Each test piece of the near-infrared absorbing film (invention) obtained in Example 5 and the comparative near-infrared absorbing film obtained in Comparative Example 3 was subjected to the same performance test (heat resistance) as in the case of the performance test (1) and shown in Table 5. The result was obtained.

Performance test (2) <heat resistance> Storage time Example 5 Comparative Example 3 Wavelength 950nm
Transmittance (%) 0 hours 5.94 4.47 500 hours 6.03 4.85 car 0.09 0.38 Visual transmittance
Y (%) 0 hours 81.745 80.037 500 hours 81.945 80.494 car 0.209 0.457 Chromaticity coordinates
x 0 hours 0.319 0.320 500 hours 0.319 0.322 car 0.000 0.002 Chromaticity coordinates
y 0 hours 0.338 0.341 500 hours 0.339 0.347 car 0.001 0.006 Appearance change 500 hours No change Yellowish

(Considerations) In the heat resistance test, the transmittance of near-infrared is 10% or less, but Comparative Example 3 has a large change in transmittance. In the chromaticity coordinates, in Example 5, although the Tg of the binder resin was low at 70 ° C., the change was small and there was no change in appearance, but in Comparative Example 3, the change in chromaticity coordinates y was large due to the influence of Tg, and the appearance changed. It was yellow in color. Moreover, also about the test result about moisture-heat resistance (60 degreeC, RH90%, 500 hours), the same result as the above appeared. The results of the heat and humidity resistance are summarized in Table 6.

Performance test (2) <heat resistance> Storage time Example 5 Comparative Example 3 Wavelength 950nm
Transmittance (%) 0 hours 5.88 4.69 500 hours 6.00 5.13 car 0.12 0.44 Visual transmittance
Y (%) 0 hours 81.905 80.100 500 hours 82.090 80.886 car 0.185 0.786 Chromaticity coordinates
x 0 hours 0.319 0.320 500 hours 0.319 0.323 car 0.000 0.003 Chromaticity coordinates
y 0 hours 0.338 0.341 500 hours 0.339 0.348 car 0.001 0.007 Appearance change 500 hours No change Yellowish

Claims (5)

A mixture of two or more dimonium compounds represented by the following formula (1), wherein n is different:

Where
n-Pr represents a normal propyl group,
iso-Bu represents an isobutyl group,
n represents the integer of 0-8. The amino compound represented by the following formula (2) obtained by the Uulman reaction and the reduction reaction is represented by the formula (3) obtained by reacting a mixture of a halogenated normal propyl compound and an isobutyl compound at 30 to 160 ° C in an organic solvent. The mixture of compounds is oxidized by adding tris (trifluoromethylsulfonyl) carbonic acid at 0 to 100 ° C in an organic solvent, and is represented by the formula (1) according to claim 1 Synthesis method of mixture of dimonium compounds

In the above formula (3),
n-Pr represents a normal propyl group,
iso-Bu represents an isobutyl group,
n represents the integer of 0-8. The dimonium compound according to claim 2, wherein the mixture of the dimonium compounds represented by the formula (1) contains 70% or more and 98% or less of the dimonium compound having n of the formula (1) of 3 to 6. Method for the synthesis of mixtures of. The near-infrared absorption film which contains the mixture of the dimonium compound of Claim 1 in the adhesive layer on a transparent support film. The optical filter for plasma display panels containing the near-infrared absorption film of Claim 4.