JP2009068061A - Method for producing core shell type silver-tin composite particle, core shell type silver-tin composite particle, black material, black light shielding film, and black particle-dispersed liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a core shell type silver-tin composite particle not only having high blackness and excellent light shieldability, but also having excellent heat resistance and a reduced environmental load, to provide an inexpensive core shell type silver-tin composite particle, to provide a black material, to provide a black light shielding film, and to provide a black particle-dispersed liquid. <P>SOLUTION: The core shell type silver-tin composite particle 1 has the average particle diameter of 1 to 300 nm, and has a structure where a tin particulate 2 essentially consisting of tin and also formed into the nucleus is covered with an outer shell layer 3 as a film with fine pores composed of at least one kind selected from silver, a silver-tin alloy, silver and a silver-tin alloy. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for producing core-shell type silver-tin composite particles, core-shell type silver-tin composite particles, black materials, black light-shielding films, and black particle dispersions, and is particularly suitable for recording materials, black matrices of various display devices, and the like. Core-shell type silver-tin composite particles having high blackness and excellent light shielding properties, core-shell type silver-tin composite particles obtained by this production method, and core-shell type silver-tin composite particles The present invention relates to the contained black material, black light shielding film, and black particle dispersion.

Conventionally, carbon black, low-order titanium oxide, iron oxide, chromium, silver fine particles, and the like are known as black materials (see, for example, Patent Document 1).
These black materials are black light shielding film, black light shielding glass, black paper, black cloth, black ink, black matrix material for plasma display (PDP) and liquid crystal display (LCD), black seal material, black mask material. For example, it is used as a material that imparts black color or light shielding properties.

On the other hand, when blackening gold, platinum group elements, or alloys thereof, a method of forming a film made of a black oxide on the surface of the base material of these metals or alloys has been adopted, The black oxide easily peeled from the base material, and a durable black alloy was not obtained. Therefore, by adding metal such as copper, nickel, iron, etc. to gold, platinum group elements, alloys thereof, or any of the above metals or alloys to which silver is added, the surface is adhered. A black alloy having a good black oxide layer has been proposed (see Patent Document 2).
Furthermore, in the field of photosensitive materials, aqueous gelatin is used as a photographic photosensitive material that improves sharpness, records optical information exposed from the back surface at an appropriate density, and has improved infrared detection characteristics during development processing. A black colloidal silver dispersion in which black colloidal silver is dispersed has been proposed (see Patent Document 3).
JP-A-5-127433 Japanese Patent Laid-Open No. 10-8235 JP 2000-155387 A

By the way, conventional carbon black, low-order titanium oxide, iron oxide and the like are black but have insufficient light shielding properties. Therefore, in order to shield light using a film containing these black materials, it is necessary to form a thick film on a substrate by thickly applying a coating liquid containing a black material.
When these black materials are used as a recording material that draws a black line on a white substrate, the light shielding property is weak, so the boundary line with the white substrate is blurred and draws a sharp line. There was a problem that could not.
When these black materials are used as the light shielding material, it is necessary to increase the volume ratio of the black material in the material in order to improve the light shielding properties, and the binder content is relatively reduced. Therefore, when a black coating film was produced using these black materials, there was a problem that the strength of the coating film was lowered and the reliability could not be maintained.

Although chromium is excellent in blackness and light shielding properties, there is a problem that applicable products are limited for various reasons such as a heavy metal and a large environmental load.
In addition, silver particles produced by reducing silver bromide used in photographic films and the like are excellent in blackness and light shielding properties, but silver itself is a noble metal and is expensive. Apart from some expensive products, they are generally not used as black materials for general purpose products.
Furthermore, when forming a black coating film using silver colloid, although it is excellent in light-shielding property, since it is tinged with metallic color, it cannot express the outstanding blackness.

  Therefore, the inventors of the present invention have a core composed mainly of tin, which is cheaper than silver but is inferior to silver in heat resistance and corrosion resistance, and has a silver tin alloy, silver and silver tin alloy excellent in heat resistance and corrosion resistance. Core-shell particles coated with an outer shell layer made of any one of the above, and by making the average particle diameter of the core-shell particles 1 nm or more and 300 nm or less, the blackness is high and the light shielding property is excellent. A black material excellent in heat resistance and corrosion resistance compared to particles and cheaper than silver was proposed (Japanese Patent Application No. 2006-67477).

  By the way, when the above black material proposed by the present inventors was evaluated for use as a black matrix material for a color filter, the blackness and light shielding properties were excellent, but the heat resistance was insufficient. It was a thing. Further, when this black material is applied to a material other than the black matrix material, it may be necessary to further improve the heat resistance depending on the material, and it has been important to further improve the heat resistance of the black material. .

  Moreover, when it is going to adjust the characteristic of said black material, a characteristic will be adjusted by controlling the quantity of the outer shell layer of a core-shell particle, ie, the thickness of an outer shell layer. In this case, since the amount and size of the core mainly composed of tin are not necessarily the optimum value, the required characteristic value may not be obtained only by adjusting the amount of the core. . Further, even if necessary characteristics are obtained, there is a problem that the amount of the outer shell layer becomes excessive and the cost is increased.

  The present invention has been made to solve the above-described problems, and has high blackness and excellent light shielding properties, as well as excellent heat resistance, and has a low environmental burden and is inexpensive. The object is to provide a method for producing tin composite particles, core-shell type silver-tin composite particles, a black material, a black light-shielding film, and a black particle dispersion.

  As a result of intensive studies to improve the black material containing core-shell particles having high blackness and excellent light-shielding properties, the present inventors have found that silver, silver or silver The outer shell layer made of any one of tin alloy, silver and silver-tin alloy is formed, and then the relative amount between the fine particles and the outer shell layer is adjusted by dissolving and removing a part of the fine particles. If so, the present inventors found that core-shell type silver-tin composite particles having high blackness, excellent light-shielding properties, sufficient heat resistance, easy characteristic adjustment, and low cost can be obtained. It came to be completed.

That is, in the method for producing core-shell type silver-tin composite particles of the present invention, fine particles that are mainly composed of tin and are cores are formed by an outer shell layer made of any one of silver, silver-tin alloy, silver, and silver-tin alloy. A core-shell type silver-tin composite particle comprising a core-shell structure particle coated and having an average particle diameter of 1 nm or more and 300 nm or less.
An outer shell layer made of any one of silver, a silver-tin alloy, silver and a silver-tin alloy is formed on the surface of fine particles containing tin as a main component and serving as a nucleus, and then a part of the fine particles is dissolved and removed. By doing so, the relative amount of the fine particles and the outer shell layer is adjusted.

In this method for producing a core-shell type silver-tin composite particle, when part of the fine particles are dissolved and removed, the amount of the fine particles and the outer shell layer to be dissolved / removed is made different so that the fine particles and the outer shell are separated. It is preferable to adjust the relative amount with the shell layer.
Adjusting the mass of the fine particles and the mass of the starting material of the outer shell layer so that the silver content of the whole particles composed of the fine particles and the outer shell layer is 30% by mass or more and 80% by mass or less. preferable.
The outer shell layer is preferably either a film having fine pores or a film formed by collecting ultrafine particles.
It is preferable that the dissolving agent used when dissolving and removing a part of the fine particles is an organic acid.

In this method for producing core-shell type silver-tin composite particles, a dispersion liquid in which fine particles serving as a main component of tin and nuclei are dispersed in a dispersion medium is complexed with one or both of a silver compound, a silver compound and a tin compound. It is preferable to add a solution containing an agent to form an outer shell layer made of any one of silver, silver tin alloy, silver and silver tin alloy on the surface of the fine particles.
It is preferable to adjust the hydrogen ion index of the solution and add the adjusted solution to the dispersion.

The core-shell type silver-tin composite particles of the present invention are obtained by the method for producing core-shell type silver-tin composite particles of the present invention.
In the core-shell type silver-tin composite particles, the silver content is preferably 30% by mass or more and 80% by mass or less.

The black material of the present invention is characterized by containing the core-shell type silver-tin composite particles of the present invention.
The black light-shielding film of the present invention is characterized by containing the black material of the present invention.
The black particle dispersion of the present invention is characterized in that the core-shell type silver tin composite particles of the present invention are dispersed in a dispersion medium.

According to the method for producing core-shell type silver-tin composite particles of the present invention, the outer shell composed of any one of silver, silver-tin alloy, silver and silver-tin alloy is formed on the surface of fine particles which are mainly composed of tin and are cores. By forming a layer and then dissolving and removing a part of the fine particles, the relative amount of the fine particles and the outer shell layer is adjusted, so that the blackness is high, the light shielding property is excellent, and sufficient heat resistance is obtained. The core-shell type silver-tin composite particles can be produced.
Moreover, since the relative amount of the fine particles and the outer shell layer is adjusted by dissolving and removing a part of the fine particles, the characteristics of the core-shell type silver-tin composite particles can be easily adjusted.
Further, since the main component of the fine particles serving as the core is tin, it is less expensive than the fine silver particles.

The production method of the core-shell type silver-tin composite particles, the core-shell type silver-tin composite particles, and the best mode for carrying out the black material, the black light-shielding film, and the black particle dispersion will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

The method for producing core-shell type silver-tin composite particles of the present embodiment is obtained by coating fine particles mainly containing tin and forming a core with an outer shell layer made of any one of silver, silver-tin alloy, silver, and silver-tin alloy. A core-shell type silver-tin composite particle, wherein the core-shell structure particles have an average particle diameter of 1 nm or more and 300 nm or less,
An outer shell layer made of any one of silver, a silver-tin alloy, silver and a silver-tin alloy is formed on the surface of fine particles containing tin as a main component and serving as a nucleus, and then a part of the fine particles is dissolved and removed. This is a method for adjusting the relative amount of the fine particles and the outer shell layer.

Here, first, the core-shell type silver-tin composite particles obtained by the manufacturing method of the core-shell type silver-tin composite particles of this embodiment will be described.
FIG. 1 is a schematic diagram showing a cross-sectional structure of a core-shell type silver-tin composite particle of the present embodiment. In the figure, 1 is a core-shell type silver-tin composite particle having an average particle diameter of 1 nm or more and 300 nm or less. This is a structure in which the tin fine particles 2 which are the main components and serve as nuclei are covered with the outer shell layer 3 which is a film having fine pores made of any one of silver, silver-tin alloy, silver and silver-tin alloy.

  FIG. 2 is a schematic view showing another example of the cross-sectional structure of the core-shell type silver-tin composite particle of the present embodiment. The core-shell type silver-tin composite particle 11 is different from the core-shell type silver-tin composite particle 1 of FIG. Is formed by the outer shell layer 13 which is a film in which tin fine particles 2 containing tin as a main component and serving as a nucleus are densely aggregated with fine particles 12 made of any one of silver, silver-tin alloy, silver and silver-tin alloy. It is a covered point.

  By setting the average particle diameter of these core-shell type silver-tin composite particles 1 and 11 to 1 nm or more and 300 nm or less, the blackness is higher than that of silver particles or tin particles, and thus the light shielding property is improved.

  Further, the tin fine particles 2 serving as the core are made of an outer shell layer 3 which is a film having fine pores made of any one of silver, silver-tin alloy, silver and silver-tin alloy, silver, silver-tin alloy, silver and silver-tin. By coating with any one of the outer shell layer 13 which is a film in which the ultrafine particles 12 made of any one of the alloys are densely assembled, the heat resistance is superior to that of the tin particles, and the mechanical strength is also improved. It has an excellent feature of being high and difficult to wear.

These core-shell type silver-tin composite particles 1 and 11 preferably contain 30% by mass or more and 80% by mass or less of silver in order to satisfy both chemical stability and blackness.
Here, the reason why the silver content is limited to 30% by mass or more and 80% by mass or less is that when the silver content is less than 30% by mass, the outer shell layer 3 that covers the core tin fine particles 2; Since the amount of silver contained in 13 is excessively reduced, the outer shell layer of silver, silver-tin alloy, silver or silver-tin alloy cannot be sufficiently coated, and the thermal stability This is because the tin fine particles 2 which are scarcely oxidized are liable to be oxidized and discoloration or the like is liable to occur, and therefore there is a risk that the blackness will be lowered and the light-shielding property may be lowered, while the silver content exceeds 80% by mass. Then, since the amount of silver contained in the outer shell layers 3 and 13 becomes excessive, the light shielding properties are excellent, but the outer shell layers 3 and 13 themselves become tinged with a metal color and the reflectance is increased. This is because the problem arises.

Next, the manufacturing method of the core-shell type silver tin composite particle of this embodiment is demonstrated.
First, tin fine particles 2 containing tin as a main component and serving as a core are covered with outer shell layers 3 and 13 made of any one of silver, silver-tin alloy, silver, and silver-tin alloy. As a method of coating with the outer shell layer, a plating method such as electroless plating, a gas phase reaction method, a spray pyrolysis method, an atomization method, a liquid phase reaction is performed so that the desired outer shell layers 3 and 13 are obtained. A fine particle synthesis method such as a method, a freeze-drying method or a hydrothermal synthesis method can be appropriately selected and used.

  For example, when the electroless plating method is used, the core tin fine particles 2 are dispersed in a dispersion medium to form a dispersion once, and any one of a silver compound, a silver compound and a tin compound serving as an outer shell layer is added to the dispersion. By adding a solution containing one or both and a complexing agent, the outer shell layers 3 and 13 made of any one of silver, a silver-tin alloy, silver and a silver-tin alloy are formed on the core tin fine particles 2. It can be formed on the surface. In this electroless plating method, silver having a high redox potential is deposited on the surface of the tin fine particles 2 having a low redox potential, so that plating can be performed without adding a reducing agent. If an agent is added, silver can be easily deposited.

As the complexing agent, nitrogen-based complexing agents such as ammonia and amine compounds are preferably used.
Further, the solution containing one or both of the silver compound, the silver compound and the tin compound and the complexing agent may be added to the dispersion after adjusting the hydrogen ion index (pH) in advance. preferable. The hydrogen ion index (pH) is preferably 9 or more and 13 or less, more preferably 10 or more and 11 or less.
The reason for selecting these complexing agents and adjusting the hydrogen ion index is to stably maintain the silver ions and the silver ion complex in the solution and to perform electroless plating easily and stably.

  By adjusting the conditions of the electroless plating, the outer shell layer is a film having fine pores made of any one of silver, silver-tin alloy, silver and silver-tin alloy on the surface of the tin fine particles 2 serving as the nucleus. 3, outer shell layer 13 which is a film in which ultrafine particles 12 made of any one of silver, silver tin alloy, silver and silver tin alloy are densely assembled can be formed.

For example, in order to obtain a film-like outer shell layer 3 having micropores, only the difference in redox potential is used without using silver and / or silver tin ultrafine particle depositing agents such as a reducing agent. Adjustment may be made so that silver having a high redox potential is deposited on the surface of the tin fine particles 2 having a low potential.
Further, in order to obtain the outer shell layer 13 in which the ultrafine particles 12 are densely aggregated, silver and / or silver tin ultrafine particles are precipitated in the liquid in advance by using a reducing agent contrary to the above, and then What is necessary is just to adjust so that it may adhere to the surface of the tin fine particle 2.

  Thus, by adjusting the electroless plating method and conditions, the film properties of the outer shell layers 3 and 13 are controlled, and the film thickness uniformity and adhesion to the tin fine particles 2 serving as the core are improved. be able to. Therefore, the oxidation of the tin fine particles 2 having poor thermal stability can be prevented, the blackness and the light shielding property can be prevented from being lowered, and the heat resistance can be improved.

Next, the relative amount of the tin fine particles 2 serving as the nucleus and the outer shell layers 3 and 13 is adjusted by dissolving a part of the tin fine particles 2 serving as the nucleus.
In this adjustment, in order to simultaneously satisfy the chemical stability and blackness of the obtained core-shell type silver-tin composite particles, as described above, so as to contain 30% by mass or more and 80% by mass or less of silver, It is preferable to adjust the relative amount between the tin fine particles 2 serving as the nucleus and the outer shell layers 3 and 13.
In addition, when part of the tin fine particles 2 is dissolved, part of the outer shell layers 3 and 13 are also dissolved. By differentiating the amount of dissolution of these tin fine particles 2 and the outer shell layers 3 and 13, The relative amount of the tin fine particles 2 and the outer shell layers 3 and 13 can be adjusted.

Here, as a solubilizing agent used when dissolving the tin fine particles 2 serving as the core, one having a dissolution rate of the tin fine particles 2 larger than that of the outer shell layers 3 and 13 may be selected and used.
The tin fine particles 2 are mainly composed of tin which is a base metal, while the outer shell layers 3 and 13 are mainly composed of silver which is a noble metal such as silver, silver tin alloy, silver and silver tin alloy silver. Therefore, if an acid is used as the solubilizer, the dissolution rate of the tin fine particles 2 as the base metal is larger than the dissolution rate of the outer shell layers 3 and 13 containing silver as the noble metal. A difference in dissolution rate can be generated between the shell layers 3 and 13.

  The acid may be either an inorganic acid or an organic acid. However, since the average particle diameter of the core-shell type silver-tin composite particles 1 and 11 of the present embodiment is as very small as 1 nm or more and 300 nm or less, for example, inorganic When an acid having a high activity, such as a strong acid, is used, the tin fine particles 2 serving as nuclei immediately dissolve with the addition of the acid, and the controllability in dissolving the tin fine particles 2 may be extremely deteriorated. . Therefore, in order to give a certain controllability to the process of dissolving the tin fine particles 2, it is preferable to use an organic acid which is a weak acid.

Among these organic acids, it is preferable to use an acid capable of forming a chelate complex with a metal ion, such as citric acid and tartaric acid.
The reason why this acid having a chelating action is preferable is that by forming a chelate complex with a tin ion on the surface of the tin fine particle 2, the release of the tin ion on the surface of the tin fine particle 2 is promoted and the tin on the surface of the tin fine particle 2 is promoted. This is because it is possible to improve the solubility.
Moreover, these acids exert a chelating action on the silver ions forming the outer shell layers 3 and 13, and temporarily generate the effects as the outer shell layers 3 and 13 by generating a stable chelate compound with the silver ions. This is because, as a result, dissolution of the tin fine particles 2 serving as the nucleus into the acid is promoted.

Here, in the state where the outer shell layers 3 and 13 are maintained, a part of the tin fine particles 2 serving as a nucleus can be dissolved using an organic acid for the following reason.
Generally, in the case of core-shell particles in which core metal fine particles are covered with an outer shell layer, it is not easy to dissolve the metal fine particles with an acid while maintaining the outer shell layer.

  On the other hand, the core-shell type silver-tin composite particles 1 and 11 according to the present embodiment, the core tin fine particles 2 are not formed from a dense outer shell layer but from any one of silver, silver-tin alloy, silver and silver-tin alloy. The outer shell layer 3 having fine pores and the outer shell layer 13 which is a film in which ultrafine particles 12 made of any one of silver, silver-tin alloy, silver and silver-tin alloy are densely assembled are covered. The outer shell layers 3 and 13 themselves have a structure in which the acid penetrates easily, and the dissolution rate of the tin fine particles 2 is higher for the acid than the dissolution rate of the outer shell layers 3 and 13. The acid penetrates the outer shell layers 3 and 13 almost without dissolving and reaches the surface of the tin fine particles 2 and dissolves a part of the tin fine particles 2. Here, if an organic acid capable of forming a chelate complex with a metal ion such as citric acid or tartaric acid is used as the acid, the organic acid temporarily reduces the effect of the outer shell layer 3, and the tin fine particles 2 serving as the nucleus This is preferable because it facilitates dissolution of the acid in the acid.

When the outer shell layers 3 and 13 contain tin, such as silver tin alloy or silver and silver tin alloy, the outer shell layers 3 and 13 are used when the tin fine particles 2 are dissolved using an organic acid. May also be dissolved. When a part of the outer shell layers 3 and 13 is dissolved by the organic acid, the acid enters from the dissolved part and dissolves a part of the tin fine particles 2 serving as a nucleus.
Furthermore, when a part of the outer shell layers 3 and 13 is dissolved, the surface state of the outer shell layer may be changed by this dissolution, such as formation of fine irregularities on the surface of the outer shell layer. Even in such a case, it is possible to improve the blackness and the light shielding property.

The core-shell type silver-tin composite particles of the present embodiment can be used as a black material because of their high blackness.
Since this black material has high blackness and excellent light shielding properties, a black light shielding film can be obtained using this black material.
Further, by dispersing the core-shell type silver-tin composite particles of the present embodiment in a dispersion medium composed of a mixture of an inorganic material such as glass or an organic material such as a resin and a solvent such as water or an organic solvent, black particle dispersion is achieved. A liquid can be obtained.
Furthermore, a black light-shielding film can also be produced by applying this black particle dispersion on a substrate to form a coating film, and subjecting this coating film to drying treatment, heat treatment, ultraviolet irradiation or infrared irradiation.

  According to the method for producing core-shell type silver-tin composite particles of the present embodiment, the outer shell layer 3 made of any one of silver, silver-tin alloy, silver and silver-tin alloy is formed on the surface of the tin fine particles 2 serving as the nucleus. 13, and then the relative amount of the tin fine particles 2 and the outer shell layers 3 and 13 is adjusted by dissolving and removing a part of the tin fine particles 2 using an acid such as an organic acid. In addition, core-shell type silver-tin composite particles having excellent light shielding properties and sufficient heat resistance can be produced.

Moreover, since the relative amount of the tin fine particles 2 and the outer shell layers 3 and 13 is adjusted by dissolving and removing a part of the tin fine particles 2, the characteristics of the core-shell type silver tin composite particles 1 and 11 can be easily adjusted. can do.
Further, since the main component of the fine particles serving as the core is tin, it is less expensive than the fine silver particles.

According to the core-shell type silver-tin composite particles 1 and 11 obtained by the manufacturing method of the core-shell type silver-tin composite particles of this embodiment, the blackness is high because the blackness is high and the light-shielding property and heat resistance are excellent. Further, it is possible to provide a black material having excellent light shielding properties and heat resistance at low cost. Moreover, it is economically advantageous because it has a low environmental load and is inexpensive.
Furthermore, by using the core-shell type silver-tin composite particles 1 and 11, it is possible to easily provide a black material having high blackness, excellent light shielding properties and heat resistance, and inexpensive.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely by Examples 1-4 and Comparative Examples 1-2, this invention is not limited by these Examples.

Example 1
50 g of a tin colloid (average particle size: 50 nm, solid content: 5.4% by mass, manufactured by Sumitomo Osaka Cement) was taken, 160 g of pure water was added thereto, and 10 g of a 1% polyvinyl alcohol (PVA) aqueous solution was further added. A liquid A was produced.
Further, 5 g of silver nitrate is dissolved in pure water to obtain a silver nitrate aqueous solution having a total amount of 150 g, 10 g of concentrated aqueous ammonia (NH ₃ : 28%) is added thereto, and 3 g of sodium hydroxide aqueous solution (NaOH: 25%) is further added. B liquid was produced.
Moreover, 50 g was fractionated from 36% citric acid aqueous solution, and it was set as C liquid.

Subsequently, these A liquid and B liquid were mixed, stirring, and it was set as D liquid.
Subsequently, C liquid was added to this D liquid, and it stirred for 4 hours, solid-liquid separation was performed by centrifugation after that, and solid content (cake) was extract | collected. Next, this cake was dispersed in pure water, and washed by ultrafiltration until the electrical conductivity reached 200 μs / cm, thereby preparing liquid E in which core-shell type silver tin composite particles were dispersed in pure water.

  Particles were separated from the E solution by a filtration method and then dried to prepare a powder sample of Example 1. As apparent from the above manufacturing process, this powder sample was a core-shell type silver-tin composite particle in which tin fine particles serving as a core were covered with an outer shell layer containing silver.

Subsequently, the quantitative analysis of the element of this powder sample was performed using the electron probe microanalyzer (EPMA), and the ratio (Sn / Ag) of silver and tin was calculated | required. Moreover, the peak intensity of the strongest line of each of silver, tin and silver-tin alloy of this powder sample was measured using an X-ray diffractometer (XRD), and the ratio of tin to silver-tin alloy (from the ratio of these peak intensities ( Sn / alloy) and the ratio of alloy to silver (alloy / Ag) were determined.
As a result, the ratio of silver to tin (Sn / Ag) is 0.35, the ratio of tin to silver tin alloy (Sn / alloy) is 0.15, and the ratio of alloy to silver (alloy / Ag) is 0.71. there were.

Subsequently, 1% polyvinyl alcohol (PVA) aqueous solution is added to this E liquid so that it may become solid content in E liquid: PVA = 25: 75 (volume ratio), and ultrasonic disperser Sonifier 450 (made by BRANSON ULTRASONICS) ), And then allowed to stand for 1 hour to obtain a coating solution.
Next, this coating solution was applied onto a 1.1 mm thick glass substrate by a spin coating method to form a black coating film. Here, the thickness of the coating film was set to 0.5 μm by adjusting the amount of water in the coating solution. In addition, the thickness of the coating film was confirmed by measuring with a film thickness measuring instrument Tencor (manufactured by Tencor).

Next, the optical density (OD value) of the black coating film is measured using a Macbeth densitometer, which is a transmission densitometer, and the coating value required for an OD value of 4 from the measured value obtained thereby. The film thickness was calculated. In addition, the film thickness at the time of OD value measurement is 0.5 micrometer as above-mentioned. Hereinafter, the thickness of the coating film required for the OD value to be 4 is referred to as “OD4 film thickness”. In addition, since this value is the thickness of the coating film required for the OD value to be 4, it indicates that the smaller the value, that is, the thinner the film thickness, the higher the light shielding degree.
Moreover, the reflectance with respect to the light of the wavelength of 500 nm of this black coating film was measured using the spectrospectrometer.

Subsequently, this glass substrate with a black coating film was hold | maintained at 240 degreeC for 50 minute (s), and the black coating film was dried, and the glass substrate with a black light shielding film was obtained.
The film thickness of the black coating film after drying was measured using a film thickness measuring instrument Tencor (manufactured by Tencor), and then the optical density (OD value) of the black coating film after drying and light having a wavelength of 500 nm. The reflectance was measured as described above. The OD4 film thickness was calculated using the OD measurement value and the film thickness measurement value thus obtained.
Using these measured values, the change rate of the OD4 film thickness value before and after drying was calculated. These results are shown in Tables 1 and 2.

(Example 2)
The powder sample of Example 2, a black coating film, and a glass substrate with a black light-shielding film, except that the stirring time when adding C liquid to D liquid in Example 1 was 3 hours. Was made.
The characteristics of the powder sample, the black coating film, and the glass substrate with the black light-shielding film were measured in the same manner as in Example 1. These results are shown in Tables 1 and 2.

(Example 3)
In the liquid B used in Example 1, the amount of silver nitrate dissolved in the liquid B was 6.5 g, and the stirring time when the liquid C was added to the liquid D in Example 1 was 3 hours. In the same manner as in Example 1, a powder sample of Example 3, a black coating film, and a glass substrate with a black light-shielding film were produced.
The characteristics of the powder sample, the black coating film, and the glass substrate with the black light-shielding film were measured in the same manner as in Example 1. These results are shown in Tables 1 and 2.

Example 4
The powder sample, black coating film, and black light-shielding film-coated glass substrate of Example 4 except that the stirring time when adding C liquid to D liquid in Example 1 was 2 hours. Was made.
The characteristics of the powder sample, the black coating film, and the glass substrate with the black light-shielding film were measured in the same manner as in Example 1. These results are shown in Tables 1 and 2.

(Comparative Example 1)
The powder sample, black coating film, and black light-shielding film-coated glass substrate of Comparative Example 1 except that the stirring time when adding C liquid to D liquid in Example 1 was 2 hours. Was made.
The characteristics of the powder sample, the black coating film, and the glass substrate with the black light-shielding film were measured in the same manner as in Example 1. These results are shown in Tables 1 and 2.

(Comparative Example 2)
A powder sample, a black coating film, and a black light-shielding film of Comparative Example 2 were provided in the same manner as in Example 1 except that the stirring time when adding C liquid to D liquid in Example 1 was 1.5 hours. A glass substrate was produced.
The characteristics of the powder sample, the black coating film, and the glass substrate with the black light-shielding film were measured in the same manner as in Example 1. These results are shown in Tables 1 and 2.

From these results, the following was found.
(1) It can be seen that as the stirring time increases, the ratio of tin to silver and the silver-tin alloy decreases, and tin is dissolved from tin fine particles serving as nuclei.
(2) It can be seen that as the tin ratio decreases, the amount of change in the OD4 film thickness value approaches 1, and the difference between the OD4 film thickness value during coating and the OD4 film thickness value after drying decreases. Thereby, it turns out that the high temperature degradation by the heating at the time of drying is reducing with the reduction | decrease of the ratio of tin.
Further, as the ratio of tin decreases, the OD4 film thickness value decreases at the time of application and after drying, and it can be seen that the light shielding degree is improved.
(3) It can be seen that the reflectivity decreases as the ratio of tin decreases.

(4) There is a correlation between the tin ratio and the reflectivity, and the reflectivity decreases as the tin ratio decreases. However, when the tin ratio becomes 0, there are no tin fine particles as nuclei, and only the outer shell layer made of silver, that is, the silver particles themselves, but in this case, the reflectivity is high. Therefore, the reflectance becomes the minimum value at a certain specific value of the tin ratio.

From these results, the core-shell type silver tin composite particles produced in Examples 1 to 4 have good characteristics as a black material and a black light-shielding film, and the OD4 film thickness even when the temperature is increased to 240 ° C. It was found that there was almost no deterioration of the value and the high temperature characteristics were excellent.
Therefore, by controlling the ratio of tin by dissolving tin, the OD4 film thickness value of the generated core-shell type silver-tin composite particles, the high temperature deterioration characteristics based on this OD4 film thickness value, and the reflectance are controlled. I found out that
As described above, it was found that the characteristics of the black material and the black light shielding film using the core-shell type silver tin composite particles can be controlled, and a good black material and the black light shielding film can be obtained.

  The core-shell type silver-tin composite particles of the present invention can be produced at low cost because the core-shell type silver-tin composite particles having excellent blackness, light-shielding property, heat resistance and corrosion resistance can be produced at low cost. The core-shell type silver-tin composite particles applied can be applied to any material that requires blackness or light shielding properties, or blackness and light shielding properties, such as black light shielding film, black light shielding glass, black paper, It can also be used as black matrix materials, black seal materials, black mask materials, etc. for flat panel displays (FPD) such as black cloth, black ink, plasma display (PDP) and liquid crystal display (LCD).

It is a schematic diagram which shows the cross-sectional structure of the core-shell particle of one Embodiment of this invention. It is a schematic diagram which shows the other example of the cross-section of the core-shell particle of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Core-shell type silver tin composite particle 2 Tin fine particle 3, 13 Outer shell layer 12 Very fine particle

Claims (12)

Core-shell structure comprising particles of core-shell structure in which fine particles which are mainly composed of tin and are cores are coated with an outer shell layer made of any one of silver, silver-tin alloy, silver and silver-tin alloy. The average particle size of the particles is a method for producing core-shell type silver-tin composite particles having a particle diameter of 1 nm or more and 300 nm or less,
An outer shell layer made of any one of silver, a silver-tin alloy, silver and a silver-tin alloy is formed on the surface of fine particles containing tin as a main component and serving as a nucleus, and then a part of the fine particles is dissolved and removed. By doing so, the relative amount of the said fine particle and the said outer shell layer is adjusted, The manufacturing method of the core-shell type silver tin composite particle characterized by the above-mentioned.   When dissolving and removing a part of the fine particles, the relative amount of the fine particles and the outer shell layer is adjusted by changing the amount of the fine particles and the outer shell layer to be dissolved and removed. The method for producing core-shell type silver-tin composite particles according to claim 1.   Adjusting the mass of the fine particles and the mass of the starting material of the outer shell layer so that the total silver content of the fine particles and the outer shell layer is 30% by mass or more and 80% by mass or less. The method for producing core-shell type silver-tin composite particles according to claim 1 or 2.   The method for producing core-shell type silver-tin composite particles according to claim 1, 2 or 3, wherein the outer shell layer is either a film having fine pores or a film formed by collecting ultrafine particles.   The method for producing core-shell type silver-tin composite particles according to any one of claims 1 to 4, wherein a solubilizer used when dissolving and removing a part of the fine particles is an organic acid.   A solution containing a silver compound, a silver compound and / or a tin compound, and a complexing agent is added to a dispersion liquid in which fine particles serving as a main component and nuclei are dispersed in a dispersion medium, and the fine particles 6. The core-shell type silver-tin composite particle according to claim 1, wherein an outer shell layer made of any one of silver, a silver-tin alloy, silver, and a silver-tin alloy is formed on the surface of the core-shell type silver-tin composite particle according to claim 1. Manufacturing method.   The method for producing core-shell type silver-tin composite particles according to claim 6, wherein the hydrogen ion index of the solution is adjusted, and the solution after the adjustment is added to the dispersion.   A core-shell type silver-tin composite particle obtained by the method for producing a core-shell type silver-tin composite particle according to any one of claims 1 to 7.   The core-shell type silver-tin composite particle according to claim 8, wherein the silver content is 30% by mass or more and 80% by mass or less.   A black material comprising the core-shell type silver-tin composite particles according to claim 8 or 9.   A black light-shielding film comprising the black material according to claim 10.   10. A black particle dispersion comprising the core-shell type silver-tin composite particles according to claim 8 dispersed in a dispersion medium.

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