JP2013144836A - Surface treatment agent for silver and silver alloy, silver and silver alloy, and light emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment agent which is used for various silver and silver alloys, e.g., for electronic parts and lighting equipment such as light emitting diodes, has excellent preventability for the discoloration (corrosion) of silver and silver alloys, and can impart excellent discoloration resistance to a silver vapor deposition face in particular.SOLUTION: The surface treatment agent for silver and silver alloys includes smectite and a silicic acid compound as components. In the surface treatment agent for silver and silver alloys, the solid mass ratio between the smectite and silicic acid compound satisfies smectite/silicic acid compound=99/1 to 1/99. In the surface treatment agent for silver and silver alloys, the smectite is any one or more kinds of stevensite, hectorite, saponite, montmorillonite and beidellite.

Description

  The present invention is excellent in discoloration (corrosion) prevention of various silver and silver alloys, for example, silver and silver alloys used in lighting devices such as electronic parts and light-emitting diodes. The present invention relates to a surface treatment agent that can be provided. The present invention also relates to silver and a silver alloy having a film made of a solid component contained in the surface treatment agent on the surface, and further to a light emitting diode having the silver and the silver alloy as a substrate.

  Silver and silver alloys have been used as precious metals as ornaments, money, tableware, electronic materials, lighting equipment, and dental materials for a long time using their excellent optical properties and electrochemical properties. Particularly recently, the demand as a reflective material for light emitting diodes has been rapidly increasing. The demand for light emitting diodes is also increasing rapidly in applications such as lighting equipment for automobiles and fluorescent lamps or incandescent lamps.

  However, silver and silver alloys used for these applications are chemically very unstable, and easily react with oxygen, moisture, hydrogen sulfide, sulfurous acid gas, etc. in the air to produce silver oxide and silver sulfide. , Thereby having the disadvantage that the silver surface changes color (corrosion) to brown or black.

  As a method for preventing such discoloration (corrosion) of silver and silver alloys, for example, organic rust preventives have been proposed (see, for example, Patent Documents 1 and 2). However, these organic rust preventives have a drawback of low resistance to ultraviolet rays and discoloration due to long-term exposure to ultraviolet rays. Since light emitting diodes used in lighting equipment and automotive applications use near ultraviolet light, it is difficult to apply these organic anticorrosive agents.

  A modified silicone material having high gas shielding properties and UV resistance has been proposed as an alternative to organic rust inhibitors, and application as a sealing material for light-emitting diodes has been proposed (see, for example, Patent Document 3). . However, the modified silicone material has insufficient malleability. When used as a sealing material for a light emitting diode, stress is generated due to heat generated during driving, and peels off from the adhesive surface. As a result, the gas shielding property is lowered, so that application to a light emitting diode is difficult.

JP-A-10-158572 JP 2004-238658 A JP 2010-248413 A

  The object of the present invention is to prevent discoloration (corrosion) of various silver and silver alloys, for example, silver and silver alloys used in lighting devices such as electronic parts and light-emitting diodes, and in particular, excellent discoloration resistance to silver-deposited surfaces. It is to provide a surface treatment agent capable of imparting properties. Moreover, it is providing the light emitting diode which equips the surface which has the film | membrane which consists of a solid component contained in a surface treating agent, and also comprises the silver and silver alloy as a board | substrate.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by a surface treatment agent having a specific composition.

That is, the present invention is characterized by the following items (1) to (12).
(1) A surface treatment agent for silver and a silver alloy containing smectite and a silicate compound as components.
(2) The surface treatment agent for silver and silver alloy according to (1), wherein the solid mass ratio of smectite and silicate compound is smectite / silicate compound = 99/1 to 1/99.
(3) The surface treatment agent for silver and silver alloy according to (1) or (2), wherein the smectite is at least one of stevensite, hectorite, saponite, montmorillonite, and beidellite.
(4) Any one of the water glasses in which the silicic acid compound is represented by the general formula M ₂ O · nSiO ₂ (n = 0.5 to 4.0, M represents an alkali metal of Li, Na, K) The surface treatment agent for silver and silver alloy according to any one of (1) to (3).
(5) The silver and silver alloy surface treating agent according to any one of (1) to (4), wherein the smectite is at least one of stevensite, hectorite, saponite, montmorillonite, and beidellite.
(6) The surface treatment agent for silver and silver alloy according to any one of (1) to (5), further comprising a vaporizable rust inhibitor.
(7) The vaporizable rust inhibitor is 1,2,3-benzotriazole, tolyltriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, imidazole, 2-mercaptobenzoimidazole, The surface treatment agent for silver and silver alloy according to (6), which is one or more vaporizable rust preventives selected from the group of 2-mercaptobenzothiazole and alkali metal salts thereof.
(8) Silver and a silver alloy comprising a film made of a solid component contained in the surface treating agent according to any one of (1) to (7).
(9) A light emitting diode comprising the silver and silver alloy according to (8) as a substrate.
(10) The light emitting diode according to (9), which is sealed with a transparent resin.
(11) The light emitting diode according to (10), wherein the transparent resin is a silicone resin.
(12) The light emitting diode according to any one of (9) to (11), wherein silver and a silver alloy have an uneven shape.

  According to the present invention, various silver and silver alloys, for example, silver and silver alloys used in lighting devices such as electronic parts and light-emitting diodes, etc. are excellent in discoloration (corrosion) prevention properties, and in particular, excellent resistance to discoloration on silver-deposited surfaces. It becomes possible to provide a surface treatment agent capable of imparting properties. In addition, it is possible to provide silver and a silver alloy having a film made of a solid component contained in the surface treatment agent on the surface, and a light emitting diode having the silver and the silver alloy as a substrate.

  Hereinafter, the present invention will be described in detail.

  The surface treatment agent for silver and silver alloy of the present invention is characterized by containing smectite and a silicate compound as components.

  The smectite particles contained in the surface treatment agent of the present invention have a plate-like shape with a thickness of 1 nm to 10 nm and an average long side length of 1 nm to 5000 nm, and swell when mixed with a solvent such as water and alcohol. And preferably have a property of being dispersed in a solvent. Moreover, the silicic acid compound contained in the surface treating agent of the present invention also has the property of being swollen and mixed in a solvent by mixing with a solvent such as water and alcohol, like smectite. The surface treatment agent of the present invention is composed of a mixture thereof, and after coating on silver and a silver alloy, by removing the solvent, particularly giving excellent discoloration resistance to the silver deposited surface. Can do. That is, when the plate-shaped smectite particles contained in the surface treatment agent of the present invention are laminated on silver and a silver alloy, for example, the shielding property of hydrogen sulfide gas in the atmosphere, which is a discoloration factor of silver and silver alloy, for example. Will improve. Moreover, the silicic acid compound contained in the surface treating agent of the present invention has an effect of improving the adhesion between smectite particles and silver and a silver alloy. That is, by containing a silicate compound, the stress at the interface between smectite particles and silver and a silver alloy is relaxed and the adhesive force is improved.

  In addition, it is preferable that the solid mass ratio of the smectite and the silicate compound contained in the surface treatment agent of the present invention is smectite / silicate compound = 99/1 to 1/99. In addition, solid mass ratio is mass ratio in the solid content state which does not contain a solvent etc.

When the solid content of the smectite and the silicate compound is more than 99 parts by mass with respect to 1 part by mass of the silicate compound, the content of the silicate compound having an effect of improving adhesion to silver and a silver alloy. There is little and there exists a possibility that the adhesiveness of the smectite particle | grains on silver and a silver alloy may fall. As a result, the gas permeation amount of hydrogen sulfide or the like from the adhesion interface increases, and the discoloration suppressing effect of silver and silver alloy cannot be obtained.
On the other hand, when the solid content of the smectite and the silicate compound is more than 99 parts by mass with respect to 1 part by mass of the smectite, the content of the smectite particles having gas shielding properties decreases. As a result, the gas permeation amount of hydrogen sulfide or the like increases, and there is a possibility that the effect of suppressing discoloration of silver and silver alloy cannot be obtained.

  In addition, from the viewpoint of the effect of improving adhesion to silver and silver alloys and the effect of improving gas shielding properties such as hydrogen sulfide, the solid content of smectite and silicate compound is such that the solid mass ratio is smectite / silicate compound = 95/5. 5/95 is more preferable, and 80/20 to 20/80 is even more preferable.

  Moreover, as a smectite contained in the surface treating agent of the present invention, any one or more of stevensite, hectorite, saponite, montmorillonite and beidellite can be suitably used. That is, smectite particles having a flat plate shape with a thickness of 1 nm or more and 10 nm or less and an average long side length of 1 nm or more and 5000 nm or less are laminated on silver and a silver alloy, thereby exhibiting gas shielding properties such as hydrogen sulfide. To do.

From the viewpoint of maintaining the gas shielding properties and the gloss inherent to silver and silver alloys, the average long side length of the smectite particles contained in the surface treatment agent of the present invention is preferably 10 to 4000 nm, preferably 10 to 2000 nm. More preferably, it is more preferably 100 to 1500 nm.
The average long side length of the smectite particles can be measured by using, for example, a transmission electron microscope. The average long side length is the average length of the long side portion of the flat plate-like particles.

The smectite contained in the surface treatment agent of the present invention may be a synthetic product or a natural product.
In addition, as a synthesis method of a smectite, a hydrothermal synthesis method can be used suitably, for example.

  As a vaporizable rust preventive contained in the surface treatment agent of the present invention, the Japan Rust Technology Association edited by "Actual of vaporizable rust preventive" (issued April 5, 1982), page 5, Corrosion inhibitor / discoloration inhibitor for copper and copper alloys, benzotriazole and tolyltriazole (methylbenzotriazole) having a triazole ring, those having a pyrrole, pyrazole ring, thiazole ring, imidazole ring, and mercapto group, or Examples include thioureas.

  Among them, 1,2,3-benzotriazole, tolyltriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, imidazole, 2-mercaptobenzoimidazole, 2-mercaptobenzothiazole, and the like One or two or more vaporizable rust preventives selected from the group of alkali metal salts can be suitably used.

The silicic acid compound contained in the surface treatment agent of the present invention is represented by the general formula M ₂ O · nSiO ₂ (n = 0.5 to 4.0, M represents an alkali metal of Li, Na, K). Any one or more of the water glasses can be suitably used. It is described in Japanese Industrial Standard (JIS K1408).

  In addition, as a solvent used for the surface treating agent of the present invention, water can be suitably used, and polar solvents such as methanol, ethanol, propanol and the like can also be used. The solid component concentration contained in the surface treatment agent of the present invention is, for example, 0.005% by mass to 2% by mass from the viewpoint of shielding properties of hydrogen sulfide gas, which is a discoloration factor of silver and silver alloys. Preferably, the content is 0.01% by mass to 1.5% by mass, and more preferably 0.05% by mass to 1% by mass.

  By using the surface treatment agent of the present invention, a film composed of the solid component contained in the surface treatment agent of the present invention can be formed on the surface of silver and silver alloy, and the solid component contained in the surface treatment agent of the present invention It is possible to provide silver and a silver alloy comprising a film made of Specifically, smectite and silicate compound contained in the surface treatment agent of the present invention on silver and silver alloy by removing the solvent after coating the surface treatment agent of the present invention on silver and silver alloy Can be formed on silver and silver alloys.

  As a method for applying the surface treating agent of the present invention to silver and a silver alloy, methods such as bar coating, dip coating, spin coating, spray coating, and potting can be suitably used.

  Moreover, drying can be used suitably as a method for removing the solvent from the surface treatment agent of the present invention, and the drying temperature is not particularly limited as long as the drying temperature is room temperature or higher. In addition, in this invention, room temperature is 20-25 degreeC.

  In this invention, it is possible to provide the light emitting diode which comprises silver and silver alloy which comprise the film | membrane which consists of a solid component contained in the surface treating agent of this invention as a board | substrate. That is, specifically, a method of mounting a light emitting diode on silver and a silver alloy, or a light emitting diode mounted on silver and a silver alloy, comprising a film made of a solid component contained in the surface treatment agent of the present invention. Thereafter, a method of applying the surface treatment agent of the present invention and removing the solvent, to provide a light emitting diode comprising silver and a silver alloy having a film made of a solid component contained in the surface treatment agent of the present invention as a substrate. It is possible to provide.

  In addition, as a method for applying the surface treatment agent of the present invention after mounting a light emitting diode on silver and a silver alloy, for example, a method such as bar coating, dip coating, spin coating, spray coating, or potting is preferably used. Can do.

Moreover, drying can be used suitably as a method for removing the solvent from the surface treatment agent of the present invention, and the drying temperature is not particularly limited as long as the drying temperature is room temperature or higher.
The light emitting diode is generally sealed with a transparent resin, and a silicone resin is preferable as the transparent resin. Moreover, the surface of the silver and silver alloy board | substrate with which a light emitting diode is equipped has uneven | corrugated shape, and it is preferable from the point of adhesiveness with the said transparent resin.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

<Combination of steven sites>
(Synthesis example)
20 ml of nitric acid was added to a dispersion obtained by mixing 60 g of colloidal silica (Ludox ™ 50, manufactured by SigmaAldrich) and 120 ml of distilled water. A solution prepared by mixing 91 g of magnesium nitrate (primary reagent) and 128 ml of distilled water was added thereto, and ammonia water (28 mass% aqueous solution) was slowly added dropwise thereto while stirring. The dripping was stopped when the pH reached 10, and the mixture was aged at room temperature overnight to obtain a uniform composite precipitate. Thereafter, water washing by adding distilled water, shaking, and solid-liquid separation was repeated until the ammonia odor disappeared. 25.4 ml of a 10% by weight lithium hydroxide aqueous solution was added to the well-mixed homogeneous composite precipitation dispersion and thoroughly mixed to obtain a starting raw material slurry. The starting material slurry was charged into an autoclave and hydrothermally reacted at 200 ° C. for 48 hours. After cooling, the reaction product in the autoclave was taken out, dried at 60 ° C., and then pulverized to obtain a smectite classified as a steven site.

<Synthesis of lithium silicate>
A reaction vessel equipped with a stirrer was charged with 2800 kg of water, and 840 kg of silica gel was added and dispersed over 40 minutes while stirring the water to prepare a cloudy silica gel dispersion. Next, 280 kg of lithium hydroxide was added to the stirred silica gel dispersion over 20 minutes and mixed, and the white turbidity in which the molar ratio of SiO ₂ to LiO _{2 in} the liquid was kept substantially constant, SiO ₂ / LiO _2. A water-containing mixture was prepared. Next, after raising the temperature of the water-containing mixture to 50 ° C., stirring was stopped, and the silica gel was peptized by leaving it in this state for 24 hours (curing step). As peptization progressed, the cloudy water-containing mixture gradually changed to a translucent slurry.
Next, the temperature of the translucent slurry was raised to 90 ° C. while stirring, and then kept in this state for 5 hours to age lithium silicate. As the aging progressed, the translucent slurry gradually changed to a cloudy gel. After ripening, the cloudy gel is allowed to cool to 50 ° C. or lower and left for 14 hours, followed by filtration to obtain a colorless and transparent lithium silicate solution having a viscosity of 11.7 cPs (0.0117 Pa · s) at 25 ° C. It was. The product production rate from SiO ₂ to lithium silicate in the raw silica gel was 92.1%. The production rate of the low-mol lithium silicate product was 6%.

Example 1
The stevensite 0.99g obtained in the synthesis example was used as smectite, 0.01g lithium silicate was used as a silicate compound, and distilled water was added to make the total weight 100g. ARE-310), 2000 rpm, 10 minutes mixing, 2200 rpm, 10 minutes defoaming was performed to obtain a surface treatment agent with a synthetic smectite / silicate compound solid mass ratio of 99/1 and 1% by mass.

<Application of surface treatment agent on silver substrate>
Using a bar coater with a wet thickness of 12 μm on a silver substrate on which silver with a thickness of 100 nm is deposited on a soda glass slide glass, the surface treatment agent of the present invention is applied at 22 ° C. for 12 hours. Then, the solvent was removed to obtain a silver substrate having a smectite / silicate compound film on the surface. In addition, wet thickness is the thickness immediately after application | coating of the surface treating agent before removing a solvent.

<Application of surface treatment agent to light emitting diode>
A light emitting diode chip having a light emission wavelength of 467.5 nm to 470 nm and a capacity of 3.7 μL was connected to the silver plated substrate with a gold wire to produce a light emitting diode. Thereafter, 0.2% of the surface treatment agent of 1% by mass of the present invention was dropped on the light emitting diode by a potting method, that is, with a dropper, left at 12 ° C. for 12 hours to remove the solvent, and the smectite / silicate compound film was surfaced. A light emitting diode provided in 1) was obtained.

<Hydrogen sulfide gas resistance evaluation of silver substrate coated with surface treatment agent>
First, the visible light reflectance at a wavelength of 550 nm of a silver substrate having a smectite / silicate compound film on its surface was measured using a spectrophotometer (manufactured by JASCO Corporation, V-570), and [reflection before exposure to hydrogen sulfide] Rate]. A silver substrate having a smectite / silicate compound film on its surface was allowed to stand in a 10 ppm hydrogen sulfide gas stream, 40 ° C., 90% RH (relative humidity) for 96 hours, and then the visible light reflectance at a wavelength of 550 nm was measured. [Reflectance after exposure to hydrogen sulfide].
[Reflectivity before exposure to hydrogen sulfide]-[Reflectivity after exposure to hydrogen sulfide] = [Reflectance reduction rate], and the case where the reflection reduction rate is within 20%, the hydrogen sulfide gas resistance is “Yes”, and the case where the reflectance exceeds 20%. The hydrogen sulfide gas resistance was evaluated as “none”. The results are shown in Table 1.

<Hydrogen sulfide gas resistance evaluation of light emitting diodes coated with surface treatment agent>
A light-emitting diode having a smectite / silicate compound film on its surface is caused to emit light at a forward current of 20 mA and a forward voltage of 3.3 V, and light is emitted using a multiphotometer (manufactured by Otsuka Electronics Co., Ltd., MCPD-3700) at an exposure time of 30 milliseconds. The intensity was measured and was defined as [emission intensity before exposure to hydrogen sulfide]. A light-emitting diode having a smectite / silicate compound film on its surface was allowed to stand in a 10 ppm hydrogen sulfide gas stream, 40 ° C., 90% RH for 96 hours, and then allowed to emit light at a forward current of 20 mA and a forward voltage of 3.3 V. The luminescence intensity was measured using a meter at an exposure time of 30 milliseconds, and was defined as [luminescence intensity after exposure to hydrogen sulfide].
([Emission intensity after exposure to hydrogen sulfide] / [Emission intensity before exposure to hydrogen sulfide]) × 100 = [Emission intensity maintenance rate], and when the emission intensity maintenance rate is 80% or more, the hydrogen sulfide gas resistance is “Yes” The case of less than 80% was evaluated as “no” resistance to hydrogen sulfide gas. The results are shown in Table 1.

(Example 2)
A surface treatment agent was prepared in the same manner as in Example 1 except that the solid mass ratio of smectite / silicate compound was 80/20, and evaluation was performed in the same manner as in Example 1.

(Example 3)
A surface treatment agent was prepared in the same manner as in Example 1 except that the solid mass ratio of smectite / silicate compound was 50/50, and evaluation was performed in the same manner as in Example 1.

Example 4
A surface treatment agent was prepared in the same manner as in Example 1 except that the solid mass ratio of smectite / silicate compound was 20/80, and evaluation was performed in the same manner as in Example 1.

(Example 5)
A surface treating agent was prepared in the same manner as in Example 1 except that the solid mass ratio of smectite / silicic acid compound was set to 1/99, and evaluated in the same manner as in Example 1.

(Example 6)
2 Mercaptobenzothiazole (manufactured by Sanshin Chemical Industry Co., Ltd., Sunseller NG, “Sunseller” is a registered trademark) was used as the vaporizable rust inhibitor, and the solid mass ratio of smectite / silicate compound / benzothiazole was 19: A surface treatment agent was prepared in the same manner as in Example 1 except that the ratio was 79: 2, and evaluation was performed in the same manner as in Example 1.

(Example 7)
A surface treatment agent was prepared in the same manner as in Example 1 except that the solid mass ratio of smectite / silicic acid compound / benzothiazole was 15/60/15, and evaluation was performed in the same manner as in Example 1.

(Example 8)
A surface treatment agent was prepared in the same manner as in Example 1 except that the solid mass ratio of smectite / silicic acid compound / benzothiazole was changed to 10/40/50, and evaluation was performed in the same manner as in Example 1.

(Comparative Example 1)
A surface treatment agent was prepared in the same manner as in Example 1 except that the solid mass ratio of smectite / silicic acid compound was set to 100/0, and evaluation was performed in the same manner as in Example 1.

(Comparative Example 2)
A surface treatment agent was produced in the same manner as in Example 1 except that the solid mass ratio of smectite / silicic acid compound was 0/100, and evaluation was performed in the same manner as in Example 1.

As shown in Table 1, it can be seen that Examples 1 to 8 are excellent in hydrogen sulfide gas resistance of the silver substrate and hydrogen sulfide gas resistance of the light emitting diode.
According to the present invention, various silver and silver alloys, for example, silver and silver alloys used in lighting devices such as electronic parts and light-emitting diodes, etc. are excellent in discoloration (corrosion) prevention properties, and in particular, excellent resistance to discoloration on silver-deposited surfaces. It becomes possible to provide a surface treatment agent capable of imparting properties. In addition, it is possible to provide silver and a silver alloy having a film made of a solid component contained in the surface treatment agent on the surface, and a light emitting diode having the silver and the silver alloy as a substrate.

Claims (12)

  A surface treatment agent for silver and a silver alloy containing smectite and a silicate compound as components.   The surface treatment agent for silver and silver alloy according to claim 1, wherein the solid mass ratio of smectite and silicic acid compound is smectite / silicic acid compound = 99/1 to 1/99.   The surface treatment agent for silver and silver alloy according to claim 1 or 2, wherein the smectite is at least one of stevensite, hectorite, saponite, montmorillonite, and beidellite. The silicic acid compound is at least one of water glasses represented by the general formula M ₂ O · nSiO ₂ (n = 0.5 to 4.0, M represents an alkali metal of Li, Na, K). The silver and the silver alloy surface treating agent according to any one of claims 1 to 3.   The surface treatment agent for silver and silver alloy according to any one of claims 1 to 4, wherein the smectite is at least one of stevensite, hectorite, saponite, montmorillonite, and beidellite.   Furthermore, the surface treatment agent of the silver and silver alloy in any one of Claims 1-5 containing a vaporizable rust preventive agent.   The vaporizable rust inhibitor is 1,2,3-benzotriazole, tolyltriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, imidazole, 2-mercaptobenzimidazole, 2-mercapto. The surface treatment agent for silver and silver alloy according to claim 6, which is one or more vaporizable rust preventives selected from the group consisting of benzothiazole and alkali metal salts thereof.   Silver and a silver alloy which comprise the film | membrane which consists of a solid component contained in the surface treating agent in any one of Claims 1-7.   A light emitting diode comprising the silver and silver alloy according to claim 8 as a substrate.   The light emitting diode according to claim 9 encapsulated with a transparent resin.   The light emitting diode according to claim 10, wherein the transparent resin is a silicone resin.   The light emitting diode according to any one of claims 9 to 11, wherein silver and a silver alloy have an uneven shape.