JP2005126664A - Treating agent for forming thin film and method for forming thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating agent for forming thin film, capable of imparting near infrared light-blocking property and designing property to glass, etc., and a method for forming the thin film. <P>SOLUTION: This method for forming the thin film is provided by applying the treating agent for forming the thin film containing (1) precious metal nanorods, (2) an organometallic compound, (3) a solvent, (4) a viscosity-adjusting agent and (5) a sol-gel reaction catalyst on the surface of a substrate made from the glass, a ceramic or a metal, drying and firing the dried gel film for forming a metal oxide film on the substrate surface by fixing the precious metal nanorods without their cohesion. Thereby, it is possible to develop properties originated from both nanorod's short axis and long axis and to impart the both functions of the designing property and near infrared light-blocking property. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thin film forming treatment agent and a thin film forming method capable of imparting near-infrared shielding properties and design properties to glass or the like.

  Glass used for windows of buildings, vehicles, and interior decorations is colored in a desired color so as to impart design properties. As a method for coloring glass, (a) a method of baking spherical noble metal nanoparticles on a substrate surface together with an organic metal compound to obtain a colored film having excellent durability, and (b) a method based on a noble metal complex and an organic metal compound. A method of baking and coloring the surface of the material, (c) a method of coloring by ion exchange by applying and baking copper or a silver compound on the surface of the substrate, and the like have been proposed. (For example, see Patent Document 1)

On the other hand, there is a need for a heat-shielding glass that has a reduced cooling burden and an antiglare effect. Also, in plasma display devices, it is known that near-infrared rays emitted along with plasma discharge cause malfunctions in remote control operations of home appliances, giving near-infrared shielding to the front glass of plasma display panels. Attempts have been made. As a method for giving near-infrared shielding function to glass, (d) a method of fixing transparent conductive material nanoparticles such as ITO and ATO on the surface of a substrate using sol-gel glass as a medium, and (e) a metal thin film by sputtering. There have been proposed a method of forming on the substrate surface, (f) a method of forming a metal oxide film on the substrate surface by CVD, and the like. (For example, see Patent Document 2)
(For example, see Patent Document 2)

Recently, an optical filter having an absorption function selective to visible light and near infrared light is known. Specifically, it is an optical filter in which a polymer film in which rod-shaped fine metal particles are dispersed in a resin component is laminated on a transparent substrate, and visible light and near infrared light originating from the long axis of the rod. Absorption is used. (For example, see Patent Document 3)
Japanese Patent Laid-Open No. 08-73240 JP-A-10-265718 JP 2003-315531 A

  However, it is not possible to expect a heat ray shielding effect with colored glasses such as (A) to (C), and it is possible to meet the required design properties for heat ray shielding glasses such as (D) to (F). Neither has only a single function.

  In addition, in an optical filter in which a polymer film in which rod-shaped metal fine particles are dispersed in a resin component is laminated, the medium that fixes the rod-shaped metal fine particles is a polymer, so that the polymer deteriorates due to environmental conditions and the like. There was a problem. Furthermore, since the rod-shaped metal fine particles are deformed into a stable shape, that is, spherical when energy is applied from the outside, the performance due to the rod is lost when the thermal energy is applied to the optical filter, and the improvement There was room.

  As a result of intensive research in view of the above problems, by simultaneously expressing the properties derived from the single axis and the long axis of the noble metal nanorods, the coloration and heat ray shielding properties are excellent, and the above-mentioned by external energy. Provided are a thin film forming treatment agent and a thin film forming method which suppress performance loss and hardly deteriorate due to environmental conditions.

  That is, the present invention comprises (1) noble metal nanorods, (2) an organometallic compound, (3) a solvent, (4) a viscosity modifier, and (5) a sol-gel reaction catalyst. In the treatment agent. Further, in the treatment agent for forming a thin film, (1) the noble metal nanorod is selected from the group consisting of gold, silver, platinum, palladium, and alloys thereof; (2) the organometallic compound is titanium, zirconium, Containing at least one metal selected from the group consisting of hafnium and aluminum; (4) the viscosity adjusting agent is nitrocellulose; (5) the sol-gel reaction catalyst is a basic catalyst; The invention is characterized in that the catalyst is an amino compound.

  Furthermore, the present invention provides (1) a noble metal nanorod, (2) an organometallic compound, (3) a solvent, (4) a viscosity modifier, and (5) a thin film forming treatment agent containing a sol-gel reaction catalyst. It is a thin film forming method characterized by firing a gel dry film after coating and drying. In the thin film forming method, (1) the noble metal nanorod is selected from the group consisting of gold, silver, platinum, palladium, and alloys thereof; (2) the organometallic compound is titanium, zirconium, hafnium, And (4) the viscosity adjusting agent is nitrocellulose; (5) the sol-gel reaction catalyst is a basic catalyst; the basic catalyst is It is an invention characterized by being an amino compound.

  According to the present invention, by fixing the noble metal nanorods in the metal oxide film without agglomerating, the properties derived from the nanorod short axis and the properties derived from the long axis are developed, and the design properties and near infrared shielding properties are improved. Both functions can be provided. In addition, by adding a sol-gel reaction catalyst to the treating agent, it is possible to promote the polycondensation of the organometallic compound near room temperature to form a rigid structure, so that the noble metal nanorods are thermally deformed during subsequent firing. It is hard to do. In addition, since the thin film to which the noble metal nanorods are fixed is a metal oxide, it has excellent durability, and even when external energy is applied to the thin film, it is possible to suppress deformation of the noble metal nanorods. Furthermore, by designing the metal oxide treatment composition so as to be a highly refractive material, the film on which the nanorods are fixed has a high reflectivity, and the near-infrared shielding property, the design property, etc. can be further improved. .

  The treatment agent for forming a thin film according to the present invention contains (1) noble metal nanorods, (2) an organometallic compound, (3) a solvent, (4) a viscosity adjusting agent, and (5) a sol-gel reaction catalyst. The thin film forming treatment agent is applied to the surface of a substrate such as glass, ceramic, or metal, dried, and then the gel film is baked to fix the noble metal nanorods without agglomerating the substrate. It can be formed on the surface.

  (1) The noble metal nanorod has a cylindrical shape with a minor axis length of 2 to 30 nm and a major axis length of 5 to 300 nm, and is composed of a noble metal such as gold, silver, platinum, palladium, or an alloy thereof. Is platinum, which is not easily oxidized even during firing. As noble metal nanorods, those prepared by a chemical reduction method called a soft template method and those produced by an electrolytic reduction method called a hard template method have been proposed, but the noble metal nanorods used in the present invention are a production method Any noble metal nanorod can be used. Further, since the properties of the noble metal nanorods are determined by the constituent metal species, the short axis length, and the long axis length, these factors must be selected from desired characteristics. In order to allow the noble metal nanorods to exist stably without agglomeration and sedimentation in the treatment agent, it is desirable that the major axis length of the noble metal nanorods is less than 200 nm.

  The property derived from the short axis of the noble metal nanorod is absorption in the visible region, and the property derived from the long axis is absorption in the long wavelength region that is greater than or equal to the visible region. In addition, one of the excellent properties of noble metal nanorods is that the absorption wavelength derived from the long axis can be freely changed from the visible range to the infrared range by changing the aspect ratio of the noble metal nanorods. Since the aspect ratio indicates that 1 is a sphere, the aspect ratio of the noble metal nanorod needs to be larger than 1.

  The addition amount of (1) noble metal nanorods used in the present invention must be appropriately determined depending on the desired properties, the treatment liquid coating method, and the treatment liquid adhesion amount to the substrate. For example, in the case of a treating agent using gold nanorods, it is desired to obtain an absorbance of the absorption peak derived from the long axis of the gold nanorods by about 0.5 by applying it to the glass substrate by screen printing (type: polyester # 250). If it exists, 0.2 to 0.4 wt% of gold nanorods may be added to the treatment liquid.

  (2) As the organometallic compound, (5) a polymer that can be polycondensed by a sol-gel reaction catalyst to form a rigid structure and can suppress deformation of noble metal nanorods due to heat is used. The reason for this is that noble metal nanorods are deformed by heat in a direction in which the aspect ratio becomes smaller. Therefore, a rigid structure is formed before firing to suppress this deformation, and the characteristics derived from the long axis of the nanorods are fully exhibited. Because. This condensation polymerization reaction is desirably performed at around room temperature, but it is sufficient that it is performed at least in a temperature range where the noble metal nanorods are not greatly deformed. The temperature range varies depending on the type of noble metal nanorods. It is desirable to form a simple structure.

  Preferred (2) organometallic compounds include ethoxides of metals such as titanium, zirconium, hafnium and aluminum, alkoxides such as propoxide and butoxide, chelates such as acetylacetone salt and glycolate salt, hydroxystearate, hydroxylactate, etc. Of the acylates. Among them, an organometallic compound having titanium, aluminum, or the like as a metal species, an organometallic compound having a methoxy group, an ethoxy group, or the like as an organic group has high reactivity and is preferably used. These are not limited to being used alone, but can be used in combination.

  The amount of (2) organometallic compound used in the present invention is the ratio of (1) the number of metal atoms (M) contained in the organometallic compound to (1) the number of noble metal atoms (N) contained in the noble metal nanorods. However, it is desirable that M / N = 0.5 or more. The upper limit of M / N is naturally limited by the amount of other additives. When M / N is less than 0.5, (1) noble metal nanorods are thermally deformed or aggregated during firing, and the intended effect of the present invention cannot be sufficiently obtained.

  (3) The solvent is not particularly limited as long as it can disperse (1) noble metal nanorods and (2) an organometallic compound and (4) a viscosity modifier. It is necessary to select appropriately depending on the method of applying the treatment liquid to the substrate, for example, high-boiling solvents such as metacresol, dimethylformamide, carbitol, α-terpineol, diacetone alcohol, triethylene glycol, paraxylene, toluene, It is preferable for applying each processing solution to the surface of the glass substrate by using screen printing or flexographic printing.

  The (4) viscosity adjusting agent used in the present invention is soluble in the above-mentioned (3) solvent and gives the processing solution a viscosity suitable for the processing solution coating method. It is preferable to use an organic polymer. Considering the durability of the fired film, it is desirable to select a compound such as carbon that has as little residue as possible after firing. Specific examples of the viscosity adjusting agent include resins such as thermally decomposable celluloses such as ethyl cellulose and nitrocellulose, and polyacryls such as polyvinyl chloride and polymethyl methacrylate. Among them, nitrocellulose is preferably used because it can be decomposed and volatilized explosively at a relatively low temperature, and hence a stronger thin film can be obtained.

  The addition amount of (3) solvent and (4) viscosity modifier used in the present invention is appropriately determined depending on the coating method of the treatment agent.

  (5) The sol-gel reaction catalyst is (3) soluble in a solvent, and (1) in a temperature range in which noble metal nanorods are not deformed. (2) An organic metal compound is polycondensed to form a rigid structure. It is done. For example, an acid catalyst, a base catalyst, and the like can be mentioned. As the acid catalyst, an inorganic acid, an organic acid, or an acid anhydride is used. Examples of inorganic acids include hydrochloric acid, nitric acid, and sulfuric acid, and examples of organic acids include acetic acid, oxalic acid, succinic acid, malonic acid, phthalic acid, maleic acid, and tartaric acid. Examples of the acid anhydride include acetic anhydride, maleic anhydride, and phthalic anhydride. Examples of the base catalyst include inorganic bases and organic bases. Inorganic bases include ammonia, potassium hydroxide, sodium hydroxide and the like. As the organic base, primary, secondary or tertiary amino compounds are used, and tertiary amines are particularly preferably used. For example, N, N-dimethylbenzylamine, tributylamine, tri-n-propylamine, tripentylamine, tripropargylamine, N, N, N-trimethylethylenediamine, tri-n-hexylamine and the like can be used. Among these, ethylenediamine is particularly preferable.

  (5) The addition amount of the sol-gel reaction catalyst varies depending on the desired processability and required characteristics, and the catalyst species and organometallic compound species, but is 0.01 to 50 mass parts with respect to 100 mass parts of the organometallic compound. It is desirable to be used at a ratio of

  Although the preparation method of the said thin film formation processing agent is not specifically limited, For example, a predetermined amount of (3) solvent is first measured to a container and this container is set to the water bath set to 40-80 degreeC. Thereafter, the viscosity modifier (4) is added to the container and stirred for 15 to 30 minutes. Further, the precious metal nanorod (1), the organometallic compound (2), and the sol-gel reaction catalyst (5) are added and stirred for 10 to 20 minutes, and then cooled at room temperature to obtain the treating agent used in the present invention.

  The processing agent for forming a thin film prepared as described above is applied to a substrate such as transparent glass by a method such as spray, dip, roll coating, spin coating, flow coating, knife coating, gravure printing, flexographic printing, or screen printing. . The coating amount of the treatment agent is adjusted by the treatment liquid composition, the coating method, the coating conditions, etc. so that the film thickness after baking is 10 to 500 nm, dried at 40 to 400 ° C., and then the obtained gel dry film Can be baked in a furnace at 400 to 800 ° C. in an air atmosphere and cooled to form a thin film. In addition, in order to give sufficient durability to a thin film, it is desirable to bake at 600-800 degreeC.

  By forming a rigid structure in which (2) the organometallic compound is polycondensed by a sol-gel reaction before the firing step, a thin film in which thermal deformation of the noble metal nanorods during firing can be suppressed can be obtained. That is, there is an effect that the noble metal nanorods are hardly thermally deformed by firing the gel dry film in which a rigid structure is formed in advance in a temperature range where the noble metal nanorods are not greatly deformed. In consideration of handling properties, it is desirable that gelation does not occur during the preparation of the treatment agent but progresses during drying.

  The thin film thus obtained is a thin film in which noble metal nanorods are dispersed and fixed in a metal oxide, and absorption derived from the short axis of the noble metal nanorods and absorption derived from the long axis are confirmed. . In addition, (5) when using a treatment agent that does not contain a sol-gel reaction catalyst, a rigid structure cannot be formed before firing, and the noble metal nanorods are deformed by firing and the aspect ratio is reduced, that is, particles are formed. In the obtained thin film, there are many precious metal fine particles whose rod shape is damaged.

  An optical filter can be obtained using this thin film. For example, by laminating on a transparent substrate such as glass or interposing between transparent substrates such as glass, an optical filter having absorption performance derived from the short axis and absorption performance derived from the long axis is obtained. When this optical filter is applied as glass for buildings, vehicles, etc., it is preferable that the optical filter has an absorption characteristic around 1500 nm, and when it is applied as a filter for a plasma display, an absorption characteristic is preferably expressed around 800 nm.

  Install a propeller stirrer and a stirring vessel in a water bath whose temperature is adjusted to 80 ° C., and first dissolve the viscosity modifier in the solvent according to the blending amount shown in Table 1, then nanorod dispersion, organometallic compound, and In Example 1, ethylenediamine was added and mixed as a sol-gel reaction catalyst. Then, each treatment agent was produced by naturally cooling to room temperature.

  Each treatment agent shown in Table 1 was applied on a transparent glass substrate having a thickness of 3 mm × 50 mm × 50 mm by screen printing (type: polyester # 250, pattern: 40 × 30 mm solid, squeegee: urethane hardness 70 degrees). The sample was dried in a hot air circulation oven at 150 ° C. for 5 minutes, baked in a muffle furnace at 600 ° C. in an air atmosphere for 10 minutes, and finally naturally cooled to obtain each sample. The unit of the blending amount is wt%.

  As the gold nanorods, those having a uniaxial length of 10 nm and a major axis length of 40 nm prepared by a soft template method were used in a state of being dispersed in toluene. The gold content of the dispersion is 10 wt%. Gold nanoparticles having a particle diameter of 3 nm were used in a state of being dispersed in toluene. The gold content of the dispersion is 5 wt%.

1. Absorption spectrum characteristics The obtained sample was measured for absorbance at a wavelength of 1500 to 400 nm with a near infrared visible spectrophotometer. The results are shown in FIG.

  In both Example 1 and Comparative Example 1, two absorption peaks were observed, which are considered to be a peak derived from the short axis of the gold nanorod on the short wavelength side and a peak derived from the long axis of the gold nanorod on the long wavelength side. In Example 1 is confirmed at 670 nm, and in Comparative Example 1 at 590 nm, Example 1 has a peak derived from the long axis of the gold nanorod on the long wavelength side, and has a rod-like property. It was found that it remained strong.

2. Transmission Electron Microscope Image Each sample was exposed to hydrofluoric acid vapor, and then immersed in water to peel the thin film from the glass. This was scooped with a carbon mesh and air-dried to obtain a sample for a transmission electron microscope (TEM). A TEM image of each sample is shown in FIG. 2 (Example 1) and FIG. 3 (Comparative Example 1).

  In FIG. 3 (Comparative Example 1), a large number of granular gold fine particles were observed, and gold nanorods with an aspect ratio of about 2 were scattered in a small part. On the other hand, in Example 1, many gold nanorods having an aspect ratio of 2 to 4 were confirmed. This is presumed that in Comparative Example 1, most of the gold nanorods were thermally deformed into particles in the firing step.

  The processing agent for thin film formation and the thin film formation method according to the present invention are applied to glass for buildings and vehicles, and filters for plasma displays.

It is a figure which shows the absorption spectrum characteristic of the Example which concerns on this invention, and a comparative example. It is a TEM image of the thin film of an Example. It is a TEM image of the thin film of a comparative example.

Claims (12)

  A treating agent for forming a thin film, comprising (1) a noble metal nanorod, (2) an organometallic compound, (3) a solvent, (4) a viscosity adjusting agent, and (5) a sol-gel reaction catalyst.   (1) The treatment agent for forming a thin film according to claim 1, wherein the noble metal nanorod is selected from the group consisting of gold, silver, platinum, palladium, and alloys thereof.   (2) The processing agent for forming a thin film according to claim 1 or 2, wherein the organometallic compound contains a metal selected from at least one selected from the group consisting of titanium, zirconium, hafnium, and aluminum.   (4) The viscosity adjusting agent is nitrocellulose, The treatment agent for forming a thin film according to any one of claims 1 to 3.   The treatment agent for forming a thin film according to any one of claims 1 to 4, wherein the sol-gel reaction catalyst is a basic catalyst.   The treatment agent for forming a thin film according to claim 5, wherein the basic catalyst is an amino compound.   (1) A noble metal nanorod, (2) an organometallic compound, (3) a solvent, (4) a viscosity adjusting agent, and (5) a treatment agent for forming a thin film containing a sol-gel reaction catalyst is applied to a substrate and dried. A method for forming a thin film, comprising firing a gel dry film.   (1) The thin film forming method according to claim 7, wherein the noble metal nanorod is selected from the group consisting of gold, silver, platinum, palladium, and alloys thereof.   (2) The thin film forming method according to claim 7 or 8, wherein the organometallic compound contains a metal selected from at least one selected from the group consisting of titanium, zirconium, hafnium, and aluminum.   (4) The viscosity adjusting agent is nitrocellulose, The thin film forming method according to any one of claims 7 to 9.   The thin film forming method according to claim 7, wherein the sol-gel reaction catalyst is a basic catalyst. The thin film forming method according to claim 11, wherein the basic catalyst is an amino compound.

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