JP2008308700A - Near infrared ray absorbing compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a near infrared ray absorbing compound strongly absorbing near infrared rays while hardly absorbing visible light and showing very good water solubility. <P>SOLUTION: The near infrared ray absorbing compound comprises a copper salt of phytic acid formed from cupric ions (Cu<SP>2+</SP>) and phytic acid at a molar ratio of 2:1 or higher. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a near-infrared absorber that efficiently absorbs light in the near-infrared wavelength region.

  A material that absorbs light in the near-infrared wavelength region is used as a heat ray absorbing material or as an optical filter.

  Various things have been examined so far.

  For example, metal iron oxides such as ferrous oxide are known to absorb heat rays, but they are not practical because of their low absorption rate and low solubility in solvents. Moreover, although it is known that carboxylic acid copper, such as copper benzoate, copper acetate, or copper naphthenate, also absorbs heat rays as an organic copper salt, the maximum absorption wavelength is near 600 to 750 nm and absorption in the near infrared region. Is weak.

  Further, it has been reported that a solution containing water as a basic base and containing ferrous sulfate or ferrous ammonium sulfate absorbs light in the near-infrared wavelength region (Japanese Patent Laid-Open Nos. 63-116625 and 4). -48404). However, since these sulfates react with water to form precipitates and precipitates when left for a while, there is a problem that an appropriate amount of sulfuric acid must be added to avoid them.

  On the other hand, phthalocyanine and naphthalocyanine are known as copper-containing compounds of near-infrared absorbing organic compounds, both of which have absorption in the visible light region, and have a maximum absorption wavelength of 800 nm or less, a sharp peak, and a wide range. It is not wavelength absorption.

Further, a copolymer obtained by copolymerizing a phosphate group-containing monomer having a specific structure and a monomer mixture copolymerizable therewith, and a metal salt containing a copper salt as a main component, There has been proposed an optical filter that absorbs light in the near-infrared region, characterized in that it contains (Japanese Patent Application Laid-Open No. 6-118228). Further, a near infrared which is a resin obtained by polymerizing a monomer having an unsaturated double bond, a phosphorus atom-containing compound having a specific structure and copper hydroxide, or a phosphorus atom-containing compound having a specific structure Absorbing resin compositions have been proposed (JP-A-10-152598 and JP-A-10-153964). These absorb light in the near-infrared wavelength region, but have a problem of low water solubility.
JP 63-116625 A JP-A-4-48404 JP-A-6-118228 Japanese Patent Laid-Open No. 10-152598 JP-A-10-153964

  It is an object of the present invention to provide a near-infrared absorbent that absorbs light in the near-infrared wavelength region strongly and absorbs light in the visible light wavelength region, and has very good solubility in water. .

  As a result of intensive studies to solve the above problems, the present inventors have found that a naturally occurring copper salt of phytic acid strongly absorbs near-infrared wavelength region, and has completed the present invention.

That is, the present invention is as follows.
(1) A near-infrared absorber containing a copper phytate salt in which a copper ion (Cu ²⁺ ) and phytic acid form a salt at a molar ratio of 2: 1 or more.
(2) The near infrared absorber according to (1), wherein the phytic acid copper salt is obtained by allowing an inorganic copper salt or an organic copper salt to act on phytic acid.
(3) The near-infrared absorber as described in (2) whose organic copper salt is a C2-C8 carboxylic acid copper salt.

  According to the present invention, it is possible to provide a near-infrared absorbent that absorbs light in the visible light wavelength region and absorbs light in the near-infrared wavelength region strongly and widely.

  Further, since phytic acid copper salt has high water solubility, the present invention is used in a water filter device that dissolves in water at a high concentration, absorbs light in the near-infrared wavelength region, and transmits visible light well. be able to.

  Furthermore, since the near-infrared absorber of this invention uses the raw material which exists naturally in large quantities, it can be manufactured cheaply.

  Hereinafter, the present invention will be described in more detail.

<1> Copper salt of phytic acid Phytic acid exists in nature, and is a compound in which the six hydroxyl groups of myo-inositol are substituted with phosphate groups (-P (O) (OH) ₂ ). In the present invention, a part of which is dephosphorylated may be present, and these are included as phytic acid.

  The said phytic acid can use what is marketed. For example, 50% phytic acid (manufactured by Tokyo Chemical Industry) can be used, and this phytic acid is also partially dephosphorylated.

The phytic acid copper salt is produced by replacing two hydrogen atoms of the phosphate group of phytic acid with 1 mol of copper ions (Cu ²⁺ ). In the present invention, as the phytic acid copper salt in which the copper ion (Cu ²⁺ ) and the phytic acid form a salt at a molar ratio of 2: 1 or more, 2 mol of copper ion (Cu ²⁺ ) per 1 mol of phytic acid. It is a salt formed in the above ratio. That is, when 1 mol of phytic acid forms a copper salt with 2 mol of copper ions (Cu ²⁺ ), the four hydrogens of the phosphate group of phytic acid are replaced with two copper ions (Cu ²⁺ ). Will be.

The maximum molar ratio of phytic acid: copper ions (Cu ²⁺ ) is 1: 6.

  The phytic acid copper salt can be obtained by allowing an inorganic copper salt or an organic copper salt to act on the phytic acid.

  Examples of the inorganic copper salt used for the reaction include copper sulfate, copper chloride, and copper carbonate. The amount of the inorganic copper salt depends on the inorganic copper salt used, but is 0.5 to 6.0 molar equivalents, preferably 1.5 to 2.5 molar equivalents, based on the phosphate group of phytic acid. Is preferably used.

  Moreover, when using organic copper salt, although carboxylic acid copper salts, such as copper acetate, copper formate, copper stearate, copper tartrate, copper citrate, copper benzoate, can be used, copper acetate is preferable.

  The amount of the organic copper salt depends on the organic copper salt used, but is 0.5 to 6.0 molar equivalents, preferably 1.5 to 2.5 molar equivalents relative to the phosphate group of phytic acid. Is preferably used.

  The reaction temperature depends on the reactants and the like, but is 10 to 90 ° C, preferably 20 to 30 ° C.

  The reaction time depends on the reactants and the like, but is until the reactants are completely dissolved, and is usually about 0.5 to 4 hours.

  The treatment after the reaction is obtained by dropping the reaction solution into an organic solvent that can be mixed with water at an arbitrary ratio after the reaction is completed, and collecting the precipitated phytate copper salt by filtration or the like.

  The organic solvent that can be mixed with water at an arbitrary ratio may be a poor solvent for precipitating copper phytate after the completion of the reaction, but lower alcohols such as methanol, ethanol, n-propanol, isopropanol, acetonitrile, Acetone, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran and the like or a mixed solvent thereof can be used.

  If necessary, the solid obtained as described above may be washed with a solvent such as alcohol.

<2> Near-infrared absorber This invention is a near-infrared absorber containing said phytic acid copper salt.

  Moreover, since the phytic acid copper salt has the ability to absorb light in the ultraviolet wavelength region, it can also serve as an ultraviolet absorber.

  Examples of the near-infrared absorber of the present invention include a film obtained by adding an appropriate amount of the phytate copper salt of the present invention to a synthetic resin such as a vinyl resin. This film is preferably transparent.

  Moreover, since the phytic acid copper salt has a very high solubility in water, it can be used by dissolving the phytic acid copper salt in water. As an example of the near-infrared absorber in that case, it is between two transparent plates provided as opposed to each other (as a material, synthetic resin such as polycarbonate, acrylic, vinyl chloride, or plate glass can be used). In addition, a filter obtained by housing a copper phytate aqueous solution in a hermetically sealed state can be mentioned.

  By attaching the film or filter to a window glass of a building, light in the near infrared wavelength region can be blocked. Since the compound of the present invention does not block visible light unlike curtains and blinds, it can block heat rays that are light in the near-infrared wavelength region without impairing indoor brightness.

  Furthermore, since this film or filter is used as a cultivation film or cultivation filter in plant cultivation, heat rays and ultraviolet rays harmful to plant growth are blocked, and visible light necessary for plant growth is not blocked. , Good growth of the plant can be obtained.

  In addition to the above, these films and filters can be used as optical filters such as a photometric filter for adjusting the characteristics of the photodiode.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.
[Example 1]

  4.15 g of copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 13.7 g of a 50% phytic acid solution (manufactured by Tokyo Chemical Industry Co., Ltd.) with stirring, and completely dissolved. The solution was added dropwise little by little into a vigorously stirred mixture of 400 ml of isopropanol and 50 ml of methanol. After the crystals were precipitated, the solution was filtered under reduced pressure using a Kiriyama funnel and washed several times with isopropanol to obtain a solid having a slight viscosity. This was moistened with methanol and pulverized into a fine powder with a spoonful, and further methanol was added, followed by stirring and washing for 30 minutes. This suspension was again filtered under reduced pressure using a Kiriyama funnel and dried under vacuum to obtain 6.60 g of a near-infrared absorbing composition as a blue powder.

  When the ratio of copper to phosphate groups in this powder was analyzed, the ratio was 1: 2.45.

  This powder was dissolved in ion-exchanged water at a concentration of 20 mg / ml, and an absorption spectrum was measured to obtain an absorption spectrum. The result is shown in FIG.

  The near-infrared absorber in FIG. 1 has almost no absorption at 400 to 600 nm, which corresponds to the visible light portion, and a wide absorption is observed at 750 to 1100 nm.

The absorption spectrum of the near-infrared absorber of this invention is shown.

Claims (3)

The near-infrared absorber containing the phytic acid copper salt in which the copper ion (Cu < ²⁺ >) and phytic acid formed the salt by the molar ratio of 2: 1 or more.   The near-infrared absorber according to claim 1, wherein the phytic acid copper salt is obtained by allowing an inorganic copper salt or an organic copper salt to act on phytic acid. The near-infrared absorber of Claim 2 whose organic copper salt is a C2-C8 carboxylic acid copper salt.

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