WO2021019808A1

WO2021019808A1 - Coating material and light absorption body

Info

Publication number: WO2021019808A1
Application number: PCT/JP2020/005192
Authority: WO
Inventors: 靖英山口; 康輝馬渡
Original assignee: 日本イットリウム株式会社
Priority date: 2019-07-29
Filing date: 2020-02-10
Publication date: 2021-02-04
Also published as: JP6942924B2; JPWO2021019808A1

Abstract

The coating material according to the present invention is obtained by dissolving, in an organic solvent, a complex of at least one rare-earth element selected from the group consisting of praseodymium, neodymium, samarium, dysprosium, holmium, erbium, thulium, and ytterbium. The rare-earth element is particularly preferably neodymium. The complex preferably has a ligand represented by formula (1). In formula (1), ring A represents a benzene ring or a naphthalene ring, R represents an alkyl group having 1-24 carbon atoms or an alkoxy group having 1-22 carbon atoms, and m represents a number of 0-3.

Description

Paint and light absorber

The present invention relates to a paint. The present invention also relates to a light absorber.

Conventionally, in order to produce a resin that shields visible light and infrared rays, colored particles having absorption in the wavelength region are dispersed in the resin, or a dye is contained in the resin. As such colored particles and dyes, for example, tungstate (M _x W _y _Oz ) fine particles and organic dyes are known. Further, a method of producing colored glass by adding metal ions to molten glass is also well known. These various methods are described in, for example, Patent Documents 1 to 5 below.

US2018 / 017721A1 Japanese Unexamined Patent Publication No. 2017-179053 Japanese Unexamined Patent Publication No. 2016-014866 Japanese Unexamined Patent Publication No. 2019-001933 US2013 / 231468A1

It is known that rare earth element ions have the property of absorbing only a very narrow wavelength region. Therefore, strong absorption is observed in a narrow wavelength region in the absorption spectra of aqueous solutions and single crystals of rare earth elements and the reflection spectra of powders of rare earth elements. However, when fine particles made of a compound of a rare earth element are dispersed in a resin, the scattering becomes strong and the resin becomes excessively cloudy. As a result, there is a problem that it is difficult to fabricate a film that strongly absorbs a narrow wavelength region peculiar to rare earth atomic ions, that is, a filter. Although it is possible to obtain colored glass by adding rare earth ions to the molten glass, there is a problem that it is difficult to form a film and the usage method is limited because the glass has a high firing temperature. Further, although it is possible to prepare a film capable of absorbing visible light by dispersing the organic dye in a resin, the organic dye has low heat resistance and weather resistance, so that strong light such as laser light can be produced. There is a problem that decolorization is likely to occur and it is not practical when irradiated with.

The present invention provides a material that can solve various problems of the above-mentioned prior art.

The present invention provides a coating material in which a polymer complex of at least one rare earth element selected from praseodymium, neodymium, samarium, dysprosium, holmium, erbium, thulium and ytterbium is dissolved in an organic solvent. Is the solution.

The present invention also provides a light absorber obtained by using the above-mentioned coating material.

FIG. 1 is a transmission spectrum of visible light measured for the thin film obtained in Example 1. FIG. 2 is a transmission spectrum of visible light measured for the thin film obtained in Comparative Example 1.

Hereinafter, the present invention will be described based on its preferred embodiment. In the present invention, a complex having a rare earth element ion as a central metal ion is used. Hereinafter, this complex is also referred to as a "rare earth element complex". This rare earth element complex has an advantage that it has light absorption and can be dissolved in an organic solvent at room temperature. This rare earth element complex has absorption especially in the wavelength region of visible light. The preferred properties of this rare earth element complex are that the ligand does not contain a nitrogen element, that the ligand has a high molecular weight (for example, the ligand has a molecular weight of 200 or more), and that it is dissolved in an organic solvent. After the organic solvent volatilizes from the solution state, it becomes a solid. In the following description, a rare earth element complex having a total molecular weight of 600 or more of all the coordinating ligands is also referred to as a “polymer complex”.

Rare earth element ions in rare earth element complexes generally have a trivalent positive charge. Depending on the type of rare earth element, it may have a divalent or tetravalent positive charge. Rare earth element ions have an advantage in that they can absorb only specific light because a sharper light absorption spectrum is observed as compared with the iron group 3d transition metal ions. When the rare earth element that can be used in the present invention is at least one selected from praseodymium, neodymium, samarium, dysprosium, holmium, erbium, thulium and ytterbium, the rare earth element complex has a very narrow wavelength range of visible light. The characteristic of absorbing only the wavelength region becomes remarkable. Of these, praseodymium and neodymium, especially neodymium, are more preferable because they have strong absorption in the wavelength region of visible light.

In the case of neodymium, a specifically useful absorption wavelength is around 580 nm or around 740 nm. In the case of praseodymium, it is around 450 nm or around 580 nm. In the case of holmium, it is around 450 nm. In the case of erbium, it is around 520 nm. In particular, neodymium is more effective as an optical filter because it absorbs a large amount of visible light in the wavelength region and does not emit light in the visible light wavelength region.

In the present invention, one kind of rare earth element complex may be used alone, or two or more kinds may be used in combination. By using two or more kinds of rare earth element complexes in combination, it is possible to adjust the strength and viscosity of the coating film containing the complex.

The rare earth element complex has the property of dissolving in an organic solvent at room temperature. "Dissolution" means that all or part of the solute becomes an ion after dissolution, the solute exists in a molecular form without dissociating into ions, or the molecule or ion exists in association with each other. including. Further, "room temperature" means 25 ° C.

The type of ligand of the rare earth element complex is not particularly limited as long as it is dissolved in an organic solvent at room temperature. It is preferable that the rare earth element complex is a polymer complex because the solubility in an organic solvent is improved. In particular, a polymer complex in which a ligand represented by the following formula (1) is coordinated is preferable because it has higher solubility in an organic solvent at room temperature.

In the formula, ring A represents a benzene ring or a naphthalene ring, R represents an alkyl group having 1 or more and 24 or less carbon atoms or an alkoxy group having 1 or more and 22 or less carbon atoms, and m represents a number of 0 or more and 3 or less. Represent.

In the ligand represented by the formula (1), m may be 0, but is preferably 1 or more and 3 or less, more preferably 1 or more and 2 or less, and even more preferably 1. Is.

In the ligand represented by the formula (1), the hydrogen atom at an arbitrary position in the benzene ring and the naphthalene ring which is the ring A may be substituted with another group. Examples of such groups include hydroxyl groups, amino groups, carboxyl groups, sulfoacid groups, nitro groups, aldehyde groups and halogens. One of these groups may be used alone, or two or more of these groups may be used.

In the ligand represented by the formula (1), the alkyl group represented by R may be a straight chain or a branched chain. As described above, the number of carbon atoms of the alkyl group is 1 or more and 24 or less, preferably 4 or more and 16 or less, and further preferably 6 or more and 12 or less.

Specific examples of the alkyl group include a linear alkyl group such as docosyl group, octadecyl group, hexadecyl group, tetradecyl group, dodecyl group, decyl group, octyl group, hexyl group, butyl group, and branched alkyl group. Examples thereof include 2-ethyl-hexyl group, 2-decyl-tetradecyl group, 2-butyl-octyl group, 2-hexyl-decyl group and 2-octyl-dodecyl group. As these alkyl groups, one type may be used alone or two or more types may be used depending on the number of m in the formula (1).

In the ligand represented by the formula (1), the alkoxy group represented by R may be a straight chain or a branched chain. In particular, the alkoxy group represented by R is a branched chain from the viewpoint of further improving the solubility of the complex in the hydrophobic organic solvent used when producing the film containing the complex according to the present invention. It is preferable to have. As described above, the number of carbon atoms of the alkoxy group is 1 or more and 22 or less, preferably 4 or more and 16 or less, and further preferably 6 or more and 12 or less.

Specific examples of the alkoxy group include a linear alkoxy group such as docosyloxy group, octadecyloxy group, hexadecyloxy group, tetradecyloxy group, dodecyloxy group, decyloxy group, octyloxy group, hexyloxy group and butyloxy group. , 2-Ethyl-hexyloxy group, 2-decyl-tetradecyloxy group, 2-butyl-octyloxy group, 2-hexyl-decyloxy group, 2-octyl-dodecyloxy group, which are the alkoxy groups of the branched chain. Be done. As these alkoxy groups, one type may be used alone or two or more types may be used depending on the number of m in the formula (1).

Preferred examples of the ligand represented by the formula (1) are as shown in (2)-(6) below. The use of these ligands is advantageous because it can form a strong coating containing the rare earth element complex. In addition, there is an advantage that the synthesis yield of the complex can be increased by using these ligands. Further, there is an advantage that it can be more easily dissolved in an organic solvent at room temperature.

In the ligand represented by the formula (1), when m is 2 or more, two or more kinds of alkyl groups may be used, two or more kinds of alkoxy groups may be used, or one kind. The above alkyl groups and one or more alkoxy groups may be used.

In the ligands of formula (1), m is 1, when the ring A is a benzene ring, R is COO - ^- that they are positioned in the para position or meta position with respect to the base Is preferable. When m is 1, ring A is a naphthalene ring, and the COO ⁻ − group is located at the 2-position, R is preferably located at the 6-position with respect to the COO ⁻ − group.

In the ligands of formula (1), m is 2, ring A is when a benzene ring, R is COO - or are located respectively in the meta and para to the group, ^- Alternatively, it is preferably located at two meta positions.

In the ligands of formula (1), m is 3, when the ring A is a benzene ring, R is COO - ^- located in the para position and two meta positions with respect to the base It is preferable to have.

The number of ligands represented by the formula (1) coordinated with rare earth element ions can take various values depending on the valence of the rare earth element ions and the electron configuration (electron orbital). When the number of ligands that neutralizes the valence of the rare earth element ion is coordinated to the rare earth element ion, that is, when the ligand is coordinated so that the charge of the complex becomes zero, it becomes a volatile organic solvent described later. This is preferable because the complex is easily dissolved. Typically, the three ligands represented by the formula (1) are coordinated with respect to the trivalent rare earth element ion, so that the complex is more easily dissolved in the volatile organic solvent described later. It is preferable because it becomes.

The rare earth element complex can be suitably produced by the method described below. First, a solution of the ligand represented by the formula (1) is prepared. This solution is called solution A. As the solvent, a solvent in which the ligand represented by the formula (1) is soluble may be used. This solvent is preferably water soluble. Examples of such a solvent include saturated aliphatic monovalent alcohols having 1 to 4 carbon atoms, ethers such as tetrahydrofuran and dioxane, and aprotic polar solvents such as acetonitrile, N, N-dimethylformamide, and dimethyl sulfoxide. Used. Basic substances such as aqueous ammonia, sodium hydroxide, potassium hydroxide, and triethylamine may be added to this solution for the purpose of converting the carboxylic acid into a carboxylate anion, which is necessary for advancing complex synthesis. preferable.

Separately from the preparation of solution A, prepare a solution containing rare earth element ions. This solution is called solution B. Liquid B can be prepared by dissolving a water-soluble rare earth element-containing compound in water.

The liquid A and the liquid B prepared in this way are mixed. As a result, the desired rare earth element complex is formed and precipitated in the liquid. For mixing the liquid A and the liquid B, for example, a method of mixing both at the same time, a method of adding the liquid B to the liquid A, and a method of adding the liquid A to the liquid B can be adopted. Further, the liquid A and the liquid B can be mixed at room temperature (25 ° C.) or under heating.

It is preferable that the rare earth element complex precipitated by mixing the liquid A and the liquid B is solid-liquid separated, recovered, washed with an organic solvent such as ethanol, and then dried.

The rare earth element complex thus obtained preferably has absorption in the wavelength region of visible light. As a result, the rare earth element complex can be used as a raw material for the visible light absorber. The wavelength region of visible light is generally 400 nm or more and 750 nm or less. In the transmission spectrum measured in this wavelength region, when an absorption peak having a peak top having a transmittance difference of 5% or more with respect to the line assumed to be the baseline is observed, the rare earth element complex is visible light. It can be said that it has absorption in the wavelength region of. Strictly speaking, the baseline needs to be measured with a rare earth element complex containing a rare earth element that does not have absorption in the visible light region, but it can be calculated from the difference between the transmittance and the absorption peak in the flat part without absorption. ..

The rare earth element complex preferably has one or two or more absorption peaks in the wavelength region of visible light in the measurement of the transmission spectrum. The position of the peak top of the absorption peak changes depending on the type of rare earth element and the type of ligand.

The magnitude of the absorption peak obtained in the measurement of the transmission spectrum is 90% when the rare earth element complex is, for example, a neodymium-containing complex or a coating film containing the same, and the transmittance at a wavelength of 850 nm is preferably 80% or more. The above is more desirable. On the other hand, the transmittance at a wavelength of 800 nm is preferably 60% or less, and more preferably 40% or less.

It is also preferable that the rare earth element complex does not emit light in the wavelength region of visible light. The fact that light emission does not occur in the wavelength region of visible light means that excitation corresponding to the energy level in the wavelength region of visible light does not occur due to irradiation with energy rays such as ultraviolet rays. Since the rare earth element complex has such a property, the rare earth element complex can be suitably used as a raw material for a visible light absorber. Rare earth elements may emit light depending on the excitation wavelength or may disappear as heat, so it is desirable to select a wavelength that absorbs strongly and does not emit light. Specifically, in the case of neodymium, absorption at wavelengths of 580 nm and 740 nm, and in the case of placeodium, absorption at wavelengths of 440 nm and 590 nm have a high absorption coefficient and no light emission is observed in the visible light region. Is suitable.

The rare earth element complex can be used as a coating material by being dissolved in an organic solvent capable of dissolving the complex, preferably a volatile organic solvent. As used herein, a volatile organic solvent is a substance having a boiling point of less than 250 ° C. and being liquid at room temperature. Examples of the organic solvent capable of dissolving the rare earth element complex include halogenated saturated aliphatic hydrocarbons such as dichloromethane, aromatic hydrocarbons such as toluene and xylene, and hydrocarbons having a carbonyl group such as methyl ethyl ketone and acetone. In particular, from the viewpoint of high solubility of the rare earth element complex, it is preferable to use a halogenated saturated aliphatic hydrocarbon such as dichloromethane. When the organic solvent is a volatile organic solvent, dissolving the rare earth complex in the volatile organic solvent facilitates the formation of a coating film of the rare earth complex using a coating material containing the rare earth complex.

The paint containing the rare earth element complex may contain other components if necessary. For example, a polymer compound that is soluble in the volatile organic solvent and has a film-forming ability, an agent that improves the dispersibility of a rare earth element complex in the paint, and an agent that enhances the strength of the film formed from the paint. Examples include various additives to be obtained.

A light absorber can be obtained by using a paint containing a rare earth element complex. For example, by applying a coating material containing a rare earth element complex to the surface of a colorless and transparent material in the wavelength region of visible light such as glass, a visible light absorber composed of a coating film containing the rare earth element complex can be formed. .. Since this absorber has absorption in at least a part of the wavelength region of visible light and does not emit light in the wavelength region of visible light, this absorber should be used as an optical filter or a bandpass filter. Can be done. In this case, it is preferable to set the thickness of the coating film, which is an absorber of visible light, to 50 μm or more and 1000 μm or less from the viewpoint that the function as an optical filter can be sufficiently exhibited. The absorber made of a coating film formed of a coating film containing a rare earth element complex is strong, has high heat resistance and weather resistance, and absorbs a narrow wavelength region peculiar to rare earth element ions. Moreover, since the rare earth element complex is in the form of a paint, the rare earth element complex can be easily applied to an arbitrary place, for example, a part having a complicated shape such as a black matrix of three primary colors, or a fine part such as an optical fiber. Therefore, unnecessary light can be easily removed at the site.

In a visible light absorber composed of a coating film formed of a coating film containing a rare earth element complex, its absorbance can be controlled by adjusting the thickness of the coating film. Since the visible light absorber composed of the thin film absorbs only light in the wavelength region peculiar to rare earth element ions, it can be used as an optical filter even when irradiated with high-density light such as laser light. Unlike conventionally used organic pigments, it has the advantage of being less prone to decomposition and deterioration. This advantage is also common to the visible light absorbers described below, which are made by kneading a rare earth element complex into a polymer material.

It is also possible to disperse a rare earth element complex in a polymer material and use it as a light absorber. When the polymer material is colorless and transparent in the wavelength region of visible light, the light absorber can be used as the visible light absorber. Various thermoplastic resins can be used as the polymer material. Examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene and ethylene-α-olefin copolymers, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, acrylic resins such as methyl polyacrylate and polymethyl methacrylate, and polystyrene. And vinyl resins such as polyvinyl chloride, and polycarbonate resins. One of these resins may be used alone, or two or more of these resins may be used in combination.

The shape of the visible light absorber formed by dispersing the rare earth element complex in the polymer material is not particularly limited. For example, a rectangular plate-shaped or disk-shaped visible light absorber can be used. In this case, the thickness of the visible light absorber is preferably 0.005 mm or more and 5 mm or less, more preferably 0.1 mm or more and 1 mm or less, and 0.2 mm or more and 0.6 mm or less at the thickest portion. Is even more preferable.

In the visible light absorber in which the rare earth element complex is dispersed in the polymer material, the ratio of the rare earth element to the visible light absorber is preferably 1% by mass or more and 80% by mass or less, and 5% by mass. It is more preferably 80% by mass or less, and further preferably 10% by mass or more and 80% by mass or less. By setting the ratio of rare earth elements in this range, visible light can be sufficiently absorbed.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, "%" means "mass%".

[Example 1]
As the ligand, the ligand represented by the above formula (2) was used. This ligand is called "42EHBA". 42EHBA of -COO ^- substances proton group bonded (. This material is referred to as "H42EHBA") and 7.51 g, to obtain a solution dissolved in ethanol 300 mL. 2 mL of aqueous ammonia (concentration 28%) was added to this solution to obtain solution A. Apart from this operation, to obtain a solution B by dissolving NdCl ₃ · 6H ₂ O of 3.59g to ion-exchanged water 100 mL. At room temperature, solution B was added dropwise while stirring solution A. Stirring was continued for 2 hours after the dropping was completed. As a result, a precipitate was formed in the liquid. The precipitate was collected by filtration, washed with a small amount of ethanol, and further dried under reduced pressure at 80 ° C. for 24 hours. This gave 6.4 g of a white solid.

The obtained white solid was measured by ESI-MS by JMS-T100LP (manufactured by JEOL Ltd.). CHCl ₃ / MeOH was used as the mobile phase. As a _{^{result, m / z = 642.17 [Nd}} (42EHBA) 2] +, m / z = 892.32 [Nd (42EHBA) 3 H] +, 924.35 [Nd (42EHBA) 3 H (CH 3 OH )] ⁺ Was observed, and it was confirmed that the white solid was an Nd (42EHBA) ₃ complex.

15 g of the obtained Nd (42EHBA) ₃ complex was dissolved in 60 mL of dichloromethane at room temperature (25 ° C.) to obtain a coating material. This paint was applied to one surface of a glass plate having a thickness of 1 mm to form a coating film. This coating film was dried at room temperature to prepare a coating film containing an Nd (42EHBA) ₃ complex. The thickness of the coating film measured from the SEM image of the cross section of the coating film was about 600 μm.

This thin film was placed on the sample measurement surface of a visible absorptiometer (U-3100 manufactured by Hitachi, Ltd.), and only a glass plate was placed on the reference light side, and the transmission spectrum of 900 nm to 300 nm was measured. The result is shown in FIG. As shown in the figure, strong absorption was observed at 580 nm, 750 nm, 800 nm and the like. Therefore, it was confirmed that this coating film can be used as an optical filter that absorbs only a narrow wavelength region. As described above, it was confirmed that the Nd (42EHBA) ₃ complex was soluble in an organic solvent at room temperature, and that the coating film had a transmission region and an absorption region in the wavelength region of visible light.

[Example 2]
15 g of the Nd (42EHBA) ₃ complex obtained in Example 1 was dissolved in 60 mL of dichloromethane, and 4 g of an acrylic resin (LR-167 manufactured by Mitsubishi Chemical Corporation) was further added to obtain a coating material. A coating film of this paint was formed in the same manner as in Example 1. The coating film was strong, and the coating film did not fall even when the glass plate was turned upside down. This coating film had substantially the same transmission spectrum as in Example 1.

[Comparative Example 1]
7 g of neodymium oxide powder was dispersed in 10 mL of methyl ethyl ketone and ground with a paint shaker together with 0.3 mmφ zirconia beads for 15 minutes. The particle size of neodymium oxide after pulverization was measured with a dynamic scattering particle size distribution meter (ELSZ-2000 manufactured by Otsuka Electronics Co., Ltd.) and found to be 0.3 μm. 22 g of acrylic resin was added to the pulverized slurry and dispersed again with a paint shaker. The dispersion was applied onto a polyethylene terephthalate film using a bar coater # 36 to form a coating film. This coating film was dried to obtain a coating film having a thickness of 15.5 μm. When this coating film was fired and the oxide weight was measured to measure the concentration of neodymium oxide in the coating film, it was about 13%.

For this thin film, the transmission spectrum of 900 nm to 300 nm was measured by the same method as in Example 1. The result is shown in FIG. As shown in the figure, no sharp absorption of visible light was observed.

As described in detail above, according to the present invention, there is provided a material that has light absorption and can be easily formed into a coating film at room temperature.

Claims

A paint made by dissolving at least one rare earth element complex selected from praseodymium, neodymium, samarium, dysprosium, holmium, erbium, thulium and ytterbium in an organic solvent.
The paint according to claim 1, wherein the rare earth element is neodymium.
The coating material according to claim 1 or 2, wherein the complex has a ligand represented by the following formula (1).

In the formula, ring A represents a benzene ring or a naphthalene ring, R represents an alkyl group having 1 or more and 24 or less carbon atoms or an alkoxy group having 1 or more and 22 or less carbon atoms, and m represents a number of 0 or more and 3 or less. Represent.
The coating material according to claim 3, wherein the complex has a ligand represented by the following formula (2).
A light absorber obtained by using the paint according to any one of claims 1 to 4.
The light absorber according to claim 5, which does not emit light in the wavelength region of visible light and absorbs light in the wavelength region of visible light.