JP4237148B2 - Black fine particle dispersion, black light shielding film using the same, and substrate with black light shielding film - Google Patents

Description

  The present invention relates to a black fine particle dispersion and a black light-shielding film and a substrate with a black light-shielding film using the same, and particularly suitable for recording materials, black matrices of various display devices, black decorative films, etc. The present invention relates to a film technology that is high and has excellent light shielding properties.

Conventionally, as black materials, metal materials such as carbon black, low-order titanium oxide, iron oxide, chromium, silver fine particles, and inorganic materials are known (for example, see Patent Document 1).
These black materials include black light-shielding film, black light-shielding glass, black paper, black cloth, black ink, black matrix material for plasma display panel (PDP) and liquid crystal display (LCD), black seal material, black mask material, etc. It is used as a material that imparts black color and 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 gold alloy could not be 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 black layer made of a good metal oxide 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, although metal materials and inorganic materials, such as conventional carbon black, low-order titanium oxide, and iron oxide, are black, they have insufficient light shielding properties. Therefore, in order to shield light using a film containing these black materials, a thick film is formed by applying a coating liquid containing a black material thickly or by applying the coating liquid a plurality of times. It is necessary to form on a substrate.
When these black materials are used as a recording material that draws a black line on a white base material, the boundary with the white base material is blurred because the light-shielding property is weak. There was a problem that could not.
Further, 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 property, and the binder content is relatively reduced. Therefore, when a black coating film is produced using these black materials, there is a problem that the strength of the coating film is lowered and the reliability of the light shielding film cannot be maintained.

In addition, although chromium is excellent in blackness and light shielding properties, it has a problem that applicable products are limited due to various reasons such as being a heavy metal, a large environmental load, and a high cost. there were.
In addition, silver particles produced by reducing silver bromide used in photographic films, etc., and black silver colloids are excellent in blackness and light-shielding properties. It can only be synthesized underneath, and the gelatin and silver particles cannot be completely separated after synthesis.
Furthermore, since gelatin is insoluble in an organic solvent, it cannot be dispersed in an organic solvent. Therefore, it can be used only for water-based paints and the width of the paints is very narrow.
In addition, when a black coating is prepared using a silver colloid, this black paint has excellent light shielding properties, but has a black color due to metallic color and plasmon absorption. There was a problem that it was not possible.

  The present invention has been made in order to solve the above-described problems. A neutral black color is obtained, the light shielding property is excellent, the environmental load is small, and an inexpensive black fine particle dispersion is used. An object is to provide a black light-shielding film and a substrate with a black light-shielding film.

  As a result of intensive studies on materials excellent in blackness and light-shielding properties, the present inventors have obtained a black fine particle dispersion containing silver tin alloy particles having an average particle size of 1 nm to 300 nm and a polymer dispersant. As a result, it was found that a black light-shielding film and a black decorative film having high blackness and excellent light-shielding properties can be obtained, and the present invention has been completed.

  That is, the black fine particle dispersion of the present invention is characterized by containing fine particles having a silver tin alloy as a main component and an average particle diameter of 1 nm to 300 nm and a polymer dispersant.

The silver-tin alloy preferably contains 47.6% by weight to 90% by weight of silver.
In the fine particles, one or both of fine particles having a silver alloy as a main component and an average particle size of 1 nm to 300 nm, and fine particles having a tin alloy as a main component and an average particle size of 1 nm to 300 nm are mixed. It may be.
The polymer dispersant is preferably contained in an amount of 1% by weight to 10% by weight with respect to the total weight of the fine particles.
The polymer dispersant is preferably polyvinylpyrrolidone.

  The black light-shielding film of the present invention is formed by applying the black fine particle dispersion of the present invention.

The base material with a black light-shielding film of the present invention is characterized in that the black light-shielding film of the present invention is provided on one main surface of the base material.
The black light-shielding film has a CIE lightness L ^* of 10 or less, a chromaticity a ^* of −1 or more and 1 or less, a chromaticity b ^* of −1 or more and 1 or less, and an OD value that is an optical density of 3 or more. Is preferred.

According to the black fine particle dispersion of the present invention, since the silver tin alloy is the main component and the fine particle having an average particle diameter of 1 nm or more and 300 nm or less and the polymer dispersant are contained, the blackness of the fine particles themselves is improved. The blackness of the coating film itself formed using this black fine particle dispersion can be improved.
Therefore, it is possible to obtain a black light shielding film and a black decorative film that are neutral black and have high light shielding properties.
Moreover, since the main component of the fine particles is a silver-tin alloy, the heat resistance can be improved as compared with particles having tin as a main component.

The best mode of the black fine particle dispersion of the present invention, the black light shielding film using the same, and the substrate with the black light shielding film 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 black fine particle dispersion of this embodiment contains silver tin (AgSn) alloy as a main component, fine particles having an average particle diameter of 1 nm or more and 300 nm or less, and a polymer dispersant.
This black fine particle dispersion contains a solvent and, if necessary, an organic binder.
When this AgSn alloy is represented by the chemical formula Ag _x Sn, the range of x in which a chemically stable AgSn alloy can be obtained is 1 ≦ x ≦ 10, and chemical stability and blackness can be obtained simultaneously. The range is 3 ≦ x ≦ 4.
The fine particles may be composed of an AgSn alloy as a main component, and may contain, for example, Ni, Pd, Au, etc. as other metal components.
The fine particles may be a mixture of Ag fine particles and Sn fine particles in addition to AgSn alloy fine particles.

Here, when the weight ratio of Ag in the AgSn alloy is determined within the range of x,
When x = 1, Ag / AgSn = 0.4762
When x = 3, 3 · Ag / Ag ₃ Sn = 0.7317
When x = 4, 4 · Ag / Ag ₄ Sn = 0.7843
When x = 10, 10 · Ag / Ag ₁₀ Sn = 0.008
It becomes. Therefore, this AgSn alloy becomes chemically stable when Ag is contained in an amount of 47.6 wt% or more and 90 wt% or less, and when Ag is contained in an amount of 73.17 wt% or more and 78.43 wt% or less. The chemical stability is further improved.

The polymer dispersant improves the dispersibility of the fine particles by improving the wettability of the surface of the fine particles, and as a result, improves the uniformity of the dispersion. For example, polyvinyl pyrrolidone (PVP), polyethylene Glycol, polyacrylamide and the like are preferably used.
The polymer dispersant is preferably contained in an amount of 1 to 10% by weight, more preferably 2 to 8% by weight, based on the total weight of the fine particles contained in the black fine particle dispersion. More preferably, it is 3% by weight or more and 6% by weight or less.

  Examples of the solvent include, but are not limited to, monohydric alcohols such as water, methanol, ethanol, n-propanol, 2-propanol, and butanol, dihydric alcohols such as ethylene glycol, and β-oxyethyl. Ethylene glycol ethers (cellosolves) such as methyl ether (methyl cellosolve), β-oxyethyl ether (ethyl cellosolve), β-oxyethylpropyl ether (propyl cellosolve), butyl-β-oxyethyl ether (butyl cellosolve), ethylene glycol , Glycols such as propylene glycol, ketones such as acetone, methyl ethyl ketone and diethyl ketone, esters such as ethyl acetate, butyl acetate and benzyl acetate, ether alcohols such as methoxyethanol and ethoxyethanol S, and propylene glycol monomethyl ether acetate.

In the black fine particle dispersion of the present embodiment, the AgSn alloy is the main component, and the fine particles having an average particle diameter of 1 nm or more and 300 nm or less are contained, so that the blackness is higher than the single Ag fine particles and Sn fine particles, and the light shielding property. Will improve.
Further, the fine particles mainly composed of the AgSn alloy are superior in heat resistance as compared with the Sn fine particles.

  The fine particles in the black fine particle dispersion of the present embodiment can be produced using a normal fine particle synthesis method. As the fine particle synthesis method, any method such as a gas phase reaction method, a spray pyrolysis method, an atomization method, a liquid phase reaction method, a freeze-drying method, or a hydrothermal synthesis method may be used.

According to the black fine particle dispersion of the present embodiment, since the AgSn alloy is the main component and the fine particles having an average particle diameter of 1 nm or more and 300 nm or less are contained, the blackness can be increased and the light shielding property can be improved. .
Further, when the polymer dispersant is contained in an amount of 1% by weight or more and 10% by weight or less based on the total weight of the fine particles contained in the black fine particle dispersion, good dispersion stability can be obtained, and good black color can be obtained. Light shielding properties can be obtained.

Further, by using polyvinyl pyrrolidone as the polymer dispersant, it is possible to obtain even better dispersion stability. Since this polyvinyl pyrrolidone is also soluble in organic solvents, using polyvinyl pyrrolidone as a polymer dispersant can disperse the fine particles in various solvents, and as a result, it can be applied to various paints. Become.
As described above, it is possible to provide a black fine particle dispersion that is a raw material for an inexpensive black light-shielding film having high blackness, excellent light-shielding properties and heat resistance, and low environmental burden.

The black light-shielding film of this embodiment is obtained by applying the black fine particle dispersion of this embodiment on a substrate and then drying.
If this black light-shielding film is formed on one main surface of the substrate, a substrate with a black light-shielding film is obtained.
Although it does not specifically limit as a base material, A glass base material and a plastic base material (organic polymer base material) can be mentioned. Moreover, as the shape, a flat plate, a film form, a sheet form, etc. are mentioned. Moreover, as said plastic base material, a plastic sheet, a plastic film, etc. are suitable.

The material of the glass substrate is not particularly limited, and can be appropriately selected from soda glass, potash glass, non-alkali glass, and the like.
The material of the plastic substrate is not particularly limited. For example, cellulose acetate, polystyrene (PS), polyethylene terephthalate (PET), polyether, polyimide, epoxy, phenoxy, polycarbonate (PC), polyvinylidene fluoride , Triacetyl cellulose, polyethersulfone (PES), polyacrylate, and the like.

  As a coating method, a commonly used method such as a spin coating method, a spray coating method, an ink jet method, a dipping method, a roll coating method, a screen printing method, a bar coating method, or the like is preferably used.

Since the dispersion applied on the substrate contains a solvent, the solvent is removed by a subsequent drying step.
For example, the substrate coated with the dispersion liquid is allowed to stand at room temperature (25 ° C.) in the atmosphere or heated at a predetermined temperature, for example, 50 ° C. to 80 ° C. in the atmosphere. The solvent contained in the liquid is dissipated to form a black light shielding film.

The black light-shielding film has a CIE lightness L ^* standardized by CIE (International Lighting Commission) of 10 or less, a chromaticity a ^* of −1 or more and 1 or less, a chromaticity b ^* of −1 or more and 1 or less, It is preferable that OD value which is an optical density is 3 or more.
The lower the CIE lightness L ^* , the better the blackness. In particular, when the CIE lightness L ^* is used as a black matrix for a liquid crystal display (LCD) or the like, the lower the CIE lightness L ^* , the better the display contrast. Therefore, a preferable range is 10 or less, which is a range where the display contrast is good.

The chromaticities a ^* and b ^* are preferably achromatic from the viewpoint of display quality, and when the absolute value exceeds 1, the hue becomes tinged. Therefore, the absolute value for an achromatic color within the preferred range is 1 or less, that is, -1 or more and 1 or less.
If the OD value is low, sufficient light shielding properties cannot be obtained, and in order to obtain sufficient light shielding properties with a film having a low OD value, the film thickness must be increased. In particular, a liquid crystal display (LCD), etc. When used as a black matrix, display unevenness and the like are likely to occur due to an increase in film thickness. Therefore, even when the film thickness is thin, the range in which sufficient light shielding properties can be obtained is set to 3 or more.

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

Example 1
To 200 ml of pure water kept at 60 ° C., 15 g of tin (Sn) colloid (average particle size: 20 nm, solid content: 20 wt%, manufactured by Sumitomo Osaka Cement Co., Ltd.) and silver (Ag) colloid (average particle size: 7 nm, A solution obtained by dissolving 60 g of solid content: 20% by weight, manufactured by Sumitomo Osaka Cement Co., Ltd. and 0.75 g of polyvinylpyrrolidone (PVP) (k15: manufactured by Tokyo Chemical Industry Co., Ltd.) in 100 ml of water was added to obtain a colloidal solution.
Next, this colloidal solution was stirred for 60 minutes while being kept at 60 ° C., and then irradiated with ultrasonic waves for 5 minutes. Next, this colloidal solution was concentrated by centrifugation to obtain a liquid A having a solid content of 15%.

Next, a PVA aqueous solution was added to the liquid A so that the volume ratio of solid content in the liquid A: PVA = 50: 50, and the dispersion was processed with an ultrasonic disperser (Sonifer 450: manufactured by BRANSON ULTRASONICS). Thereafter, the mixture was allowed to stand for 1 hour to obtain a black fine particle dispersion.
Next, this dispersion was applied on a glass substrate having a thickness of 1.1 mm 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 dispersion.
Subsequently, this glass substrate with a coating film was heated at 200 ° C. for 1 hour using a heating device to obtain a glass substrate with a black light-shielding film.

Subsequently, the light transmittance of this glass substrate with a black light shielding film was measured. Here, the light transmittance of the black light-shielding film itself with respect to light having a wavelength of 550 nm was measured with a spectrospectrometer.
In order to evaluate the blackness of the black light-shielding film, the CIE lightness L ^* , chromaticity a ^* , b ^* of the black light-shielding film is L ^* a ^* standardized by the CIE (International Commission on Illumination) ^. b ^* Measured based on the color system.
The OD value, which is the optical density of the black light-shielding film, was measured using a transmission densitometer. These measurement results are shown in Table 1.

Furthermore, the liquid A was dried by a freeze-drying method to produce a powder sample of Example 1, and the product phase in the powder sample was identified using an X-ray diffractometer.
FIG. 1 is a diagram showing a powder X-ray diffraction pattern of the powder sample of Example 1, in which Δ is a diffraction line of an Ag ₄ Sn alloy phase or an Ag ₃ Sn alloy phase.
Thereby, it turned out that the particle | grains in A liquid are the particle | grains comprised with the AgSn alloy.

(Example 2)
A glass substrate with a black light-shielding film of Example 2 was produced in the same manner as in Example 1 except that 15 g of the Sn colloid and 45 g of the Ag colloid in Example 1.
Next, in the same manner as in Example 1, measurement of light transmittance, measurement of CIE lightness L ^* , chromaticity a ^* , b ^* , and measurement of OD value were performed. These measurement results are shown in Table 1.

(Comparative Example 1)
Carbon black (HA3, manufactured by Tokai Carbon Co., Ltd.) was added with a PVA aqueous solution so as to have a volume ratio of carbon black: PVA = 50: 50 in the same manner as in Example 1, and dispersed in the same manner as in Example 1. The water content was adjusted and applied on a glass substrate by a spin coating method to prepare a black coating film having a thickness of 0.5 μm.
Subsequently, this glass substrate with a coating film was dried at room temperature (25 ° C.) to obtain a glass substrate with a black light-shielding film.
Next, in the same manner as in Example 1, measurement of light transmittance, measurement of CIE lightness L ^* , chromaticity a ^* , b ^* , and measurement of OD value were performed. These measurement results are shown in Table 1.

(Comparative Example 2)
To titanium black (13M, manufactured by Gemco), a PVA aqueous solution was added so that the volume ratio of titanium black: PVA = 50: 50 was the same as in Example 1, and the dispersion treatment and dispersion in the same manner as in Example 1 were performed. Adjustment of the amount of water and application onto a glass substrate by a spin coating method were performed to produce a black coating film having a thickness of 0.5 μm.
Subsequently, this glass substrate with a coating film was dried at room temperature (25 ° C.) to obtain a glass substrate with a black light-shielding film.
Next, in the same manner as in Example 1, measurement of light transmittance, measurement of CIE lightness L ^* , chromaticity a ^* , b ^* , and measurement of OD value were performed. These measurement results are shown in Table 1.

(Comparative Example 3)
A silver nanoparticle (manufactured by Sumitomo Osaka Cement Co., Ltd.) was added with a PVA aqueous solution so as to have a volume ratio of silver nanoparticles: PVA = 50: 50 in the same manner as in Example 1. Adjustment of the amount of moisture therein and application onto a glass substrate by a spin coating method were performed to prepare a black coating film having a thickness of 0.5 μm.
Subsequently, this glass substrate with a coating film was dried at room temperature (25 ° C.) to obtain a glass substrate with a black light-shielding film.
Next, in the same manner as in Example 1, measurement of light transmittance, measurement of CIE lightness L ^* , chromaticity a ^* , b ^* , and measurement of OD value were performed. These measurement results are shown in Table 1.

(Comparative Example 4)
Using an aniline black black dye (manufactured by Horiuchi Chemical Laboratory), coating was performed on a glass substrate by a spin coating method to produce a black coating film having a thickness of 0.5 μm.
Subsequently, this glass substrate with a coating film was dried at room temperature (25 ° C.) to obtain a glass substrate with a black light-shielding film.
Next, in the same manner as in Example 1, measurement of light transmittance, measurement of CIE lightness L ^* , chromaticity a ^* , b ^* , and measurement of OD value were performed. These measurement results are shown in Table 1.

According to this table, the black light-shielding films of Examples 1 and 2 have lower light transmittance, lower CIE lightness L ^* , and smaller absolute values of chromaticity a ^* and b ^* than Comparative Examples 1 to 4. From this, it was confirmed that the light shielding property and the blackness were excellent.
On the other hand, although the black light shielding film of Comparative Example 1 has a blackness close to that of Examples 1 and 2, the light transmittance is high, and it is found that the light shielding property is inferior to the black light shielding films of Examples 1 and 2. It was.
Moreover, it turned out that the black light shielding film of Comparative Examples 2 and 4 is inferior in both blackness and light transmittance.
Further, although the black light-shielding film of Comparative Example 3 has almost the same light-shielding properties as those of Examples 1 and 2, the color of the film was gray and not blackened, and there was a problem in color tone.

  The black fine particle dispersion of the present invention is excellent in blackness, light-shielding property, and further excellent in heat resistance, and can be used as an inexpensive black light-shielding film material. Therefore, blackness, light-shielding property, and heat resistance are required. Applicable to any kind of material. For example, display devices such as black light-shielding film, black light-shielding glass, black paper, black cloth, black ink, liquid crystal display (LCD), plasma display (PDP), electroluminescence display (ELD), electrochromic display (ECD) It can also be used as a black matrix material, black seal material, black mask material, and the like.

It is a figure which shows the powder X-ray-diffraction figure of the powder sample of Example 1 of this invention.

Claims (8)

  A black fine particle dispersion liquid comprising a fine particle having a silver tin alloy as a main component and an average particle diameter of 1 nm or more and 300 nm or less, and a polymer dispersant.   2. The black fine particle dispersion according to claim 1, wherein the silver-tin alloy contains 47.6 wt% or more and 90 wt% or less of silver.   In the fine particles, one or both of fine particles having a silver alloy as a main component and an average particle size of 1 nm to 300 nm, and fine particles having a tin alloy as a main component and an average particle size of 1 nm to 300 nm are mixed. The black fine particle dispersion according to claim 1 or 2, wherein   4. The black fine particle dispersion according to claim 1, wherein the polymer dispersant is contained in an amount of 1% by weight to 10% by weight with respect to the total weight of the fine particles.   The black fine particle dispersion according to any one of claims 1 to 4, wherein the polymer dispersant is polyvinylpyrrolidone.   A black light-shielding film obtained by applying the black fine particle dispersion according to any one of claims 1 to 5.   A base material with a black light-shielding film, comprising the black light-shielding film according to claim 6 on one main surface of the base material. The black light shielding film has a CIE lightness L ^* of 10 or less, a chromaticity a ^* of −1 or more and 1 or less, a chromaticity b ^* of −1 or more and 1 or less, and an OD value of 3 or more. The base material with a black light-shielding film according to claim 7.

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