US20080105085A1 - Method Of Production Of High Purity Silver Particles - Google Patents
Method Of Production Of High Purity Silver Particles Download PDFInfo
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- US20080105085A1 US20080105085A1 US11/664,640 US66464005A US2008105085A1 US 20080105085 A1 US20080105085 A1 US 20080105085A1 US 66464005 A US66464005 A US 66464005A US 2008105085 A1 US2008105085 A1 US 2008105085A1
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- silver
- surfactants
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- oxalate
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- 238000000034 method Methods 0.000 title claims abstract description 47
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 239000002245 particle Substances 0.000 title claims abstract description 41
- 229910052709 silver Inorganic materials 0.000 title claims abstract description 40
- 239000004332 silver Substances 0.000 title claims abstract description 40
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- XNGYKPINNDWGGF-UHFFFAOYSA-L silver oxalate Chemical compound [Ag+].[Ag+].[O-]C(=O)C([O-])=O XNGYKPINNDWGGF-UHFFFAOYSA-L 0.000 claims abstract description 42
- 239000004094 surface-active agent Substances 0.000 claims abstract description 41
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 235000019441 ethanol Nutrition 0.000 claims description 11
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 11
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 11
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 11
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 7
- 238000009210 therapy by ultrasound Methods 0.000 claims description 7
- 229920000159 gelatin Polymers 0.000 claims description 6
- 235000019322 gelatine Nutrition 0.000 claims description 6
- -1 oxalate compound Chemical class 0.000 claims description 6
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 6
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 6
- 108010010803 Gelatin Proteins 0.000 claims description 5
- 239000008273 gelatin Substances 0.000 claims description 5
- 235000011852 gelatine desserts Nutrition 0.000 claims description 5
- 229940039748 oxalate Drugs 0.000 claims description 5
- 239000002280 amphoteric surfactant Substances 0.000 claims description 4
- 239000003945 anionic surfactant Substances 0.000 claims description 4
- 239000003093 cationic surfactant Substances 0.000 claims description 4
- 239000002736 nonionic surfactant Substances 0.000 claims description 4
- 229940100890 silver compound Drugs 0.000 claims description 4
- 150000003379 silver compounds Chemical class 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 235000006408 oxalic acid Nutrition 0.000 claims description 2
- ZNCPFRVNHGOPAG-UHFFFAOYSA-L sodium oxalate Chemical compound [Na+].[Na+].[O-]C(=O)C([O-])=O ZNCPFRVNHGOPAG-UHFFFAOYSA-L 0.000 claims description 2
- 229940039790 sodium oxalate Drugs 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- 230000000063 preceeding effect Effects 0.000 claims 2
- 238000005406 washing Methods 0.000 claims 1
- 239000000084 colloidal system Substances 0.000 abstract description 11
- 239000003638 chemical reducing agent Substances 0.000 abstract description 7
- 230000002194 synthesizing effect Effects 0.000 abstract description 7
- 238000006243 chemical reaction Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 7
- HDCUKDHYRMGLRT-UHFFFAOYSA-L [Ag+2].[O-]C(=O)C([O-])=O Chemical class [Ag+2].[O-]C(=O)C([O-])=O HDCUKDHYRMGLRT-UHFFFAOYSA-L 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 5
- 239000011368 organic material Substances 0.000 description 5
- 125000004432 carbon atom Chemical group C* 0.000 description 4
- 239000010944 silver (metal) Substances 0.000 description 4
- 241000894006 Bacteria Species 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 230000002209 hydrophobic effect Effects 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- 238000005979 thermal decomposition reaction Methods 0.000 description 3
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000001828 Gelatine Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000010946 fine silver Substances 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/30—Making metallic powder or suspensions thereof using chemical processes with decomposition of metal compounds, e.g. by pyrolysis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
Definitions
- the present invention relates to a method of forming silver particles by dispersing silver oxalate into an appropriate carrier and then applying heat at a temperature of 100° C. or higher to decompose the silver oxalate.
- a number of methods have been developed to synthesize silver particles including, but not limited to, chemical reduction, photochemical, sonochemical and gas evaporation methods.
- chemical reduction method is widely used due to the ease of production.
- silver powder produced using the chemical reduction method can be contaminated by the reducing agent, the surfactant and impurity ions used during the reaction process, which can serve as a limiting factor in the field of electronics requiring high conductivity or in the field of bacteria resistance requiring high purity.
- the object of the present invention is to synthesize high purity silver particles and colloids in a process that does not require either surfactants or reducing agents, or only a minimal amount of a surfactant.
- this object is achieved by dispersing silver oxalates into an appropriate carrier and then thermally decomposing the silver oxalates at a temperature of 100° C. or higher to synthesize high purity silver particles and colloids.
- the process of synthesizing silver particles and colloids by the method of the present invention comprises: (i) a silver oxalate synthesizing process; (ii) a process of dispersing silver oxalates into an appropriate carrier, for example, water, alcohol or the like, including a combination of more than one carrier; and (iii) a process of heating said silver oxalates dispersed into said carrier at a temperature of 100° C. or higher under a pressure greater than atmospheric pressure.
- FIG. 1 is a microphotograph of silver particles obtained under the conditions described in Example 1.
- FIG. 2 is a microphotograph of silver particles obtained under the conditions described in Example 2.
- FIG. 3 is a microphotograph of silver particles obtained under the conditions described in Example 3.
- FIG. 4 is a microphotograph of silver particles obtained under the conditions described in Example 4.
- FIG. 5 is a microphotograph of silver particles obtained under the conditions described in Example 5.
- FIG. 6 is a microphotograph of silver particles obtained under the conditions described in Example 6.
- a method for the production of silver particles and colloids comprises three processes as follows: (i) a silver oxalate (Ag 2 C 2 o 4 ) synthesizing process; (ii) a process of dispersing silver oxalate into an appropriate carrier, for example, water, alcohol or the like, including a combination of more than one carrier; and (iii) a process of heating said silver oxalate dispersed into said carrier at a temperature of 100° C. or higher under a pressure greater than atmospheric pressure to form silver particle or colloids from the decomposition of the silver oxalate.
- a silver oxalate Ag 2 C 2 o 4
- a first solution of a water soluble silver compound and a second solution of an oxalate compound are mixed together to precipitate silver oxalates.
- the silver compound may be AgNO 3 .
- the oxalate compound may be sodium oxalate or oxalic acid.
- the present invention is not, however, limited to these specific compounds but may include any two solutions of compounds that form silver oxalates upon mixing. After water cleaning processes, preferably two or more rounds of water cleaning processes, are performed to remove impure ions from the precipitated silver oxalate, the silver oxalate is used as the starting material for synthesizing silver powder or colloids.
- the synthesized silver oxalate is dispersed into an appropriate carrier.
- the silver oxalate is not dissolved to any substantial extent in the carrier, but is dispersed as solid particles by using ultrasonic treatment.
- the appropriate carrier may include all types of carriers which can disperse silver oxalate to effectively deliver heat.
- the carrier is selected to have properties that allow it to behave similarly to a surfactant so as to prevent agglomeration of the silver particles formed from the thermal decomposition of the silver oxalate.
- alcohols consist of alkyl and hydroxyl groups. Generally, alkyl groups have hydrophobic properties and hydroxyl groups have hydrophilic properties. Organic materials having both hydrophobic and hydrophilic properties can play a role as a surfactant.
- organic materials having higher carbon numbers tend to be dominantly hydrophobic and may therefore tend to lose the ability to act as a surfactant in the process of the present invention.
- organic materials having higher numbers of carbon atoms have superior surfactant properties.
- organic materials with a higher number of carbon atoms is observed to agglomerate silver particles.
- organic materials with a higher number of carbon atoms do not mix well with water. Therefore, the present invention is limited to methyl, ethyl and propyl alcohols, which have a low number of carbon atoms. Water is also effective in the practice of the present invention.
- the appropriate carrier may therefore consist of ethyl alcohol, methyl alcohol, propyl alcohol, water or a combination of more than one of the preceding.
- the carriers selected for the practice of the present invention all have low boiling points: water (100° C.), methyl alcohol (64.65° C.), ethyl alcohol (78.3° C.), and propyl alcohol (82° C.). Accordingly, when the carrier with the dispersed silver oxalate is heated in a container at or above 100° C., the pressure is always above atmospheric pressure. Typical reaction pressures are about 1.86*10 5 N/m 2 when using water as the carrier and about 5.31*10 5 N/m 2 when using ethyl alcohol as the carrier.
- the carbon dioxide gas evolved during the thermal decomposition of the silver oxalate and the carrier vapor may be evacuated as necessary but pressure drops of less than about 6.89*10 4 N/m 2 do not affect the quality of the silver particles.
- the dispersed silver oxalate in the carrier is placed into a closed reactor to heat the dispersed silver oxalate and carrier up to at least 100° C. to synthesize silver powder or colloids of various form factors.
- This method may optionally use surfactants in order to prevent coagulation or agglomeration of the silver particles.
- Surfactants may be added to the water soluble silver or oxalate solutions used to produce silver oxalate, or may be added after the silver oxalate is produced by mixing the two solutions.
- Surfactants used in this method may include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorochemical surfactants, and polymerizable surfactants, or combinations of the preceding, which may be added to aid in forming silver particles and to break down silver plates or prevent silver plates from coagulation.
- Surfactants suitable for use in the present invention include PVP (polyvinyl pyrrolidone) and gelatine.
- silver particles or colloids can be obtained by the method of the present invention, however, it is desirable to limit the amount of surfactant to no more than 80% of the weight of the silver. For example, if 10 grams of silver is placed into the reactor, the weight of the surfactant, such as PVP or gelatin, should be no more than 8 grams.
- PVP polyvinyl pyrrolidone
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- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Colloid Chemistry (AREA)
Abstract
A method for synthesizing high purity silver particles and colloids without requiring the addition of either surfactants or reducing agents thereto, or requiring only a minimal amount thereof. The synthesizing process comprises: (i) a silver oxalate synthesizing process; (ii) a process of dispersing silver oxalate into an appropriate carrier; and {iii) a process of heating said silver oxalate dispersed into said carrier at a temperature of at least 100° C. Silver particles and colloids of various form factor and size may be synthesized depending upon the reaction conditions, the carrier, and the type of surfactant.
Description
- This application claims the benefit of U.S. Provisional Application No. 60/618,876, filed Oct. 14, 2004 and entitled “Method for Production of Fine Silver Particles,” which is incorporated herein by reference.
- The present invention relates to a method of forming silver particles by dispersing silver oxalate into an appropriate carrier and then applying heat at a temperature of 100° C. or higher to decompose the silver oxalate.
- A number of methods have been developed to synthesize silver particles including, but not limited to, chemical reduction, photochemical, sonochemical and gas evaporation methods. Of these methods, the chemical reduction method is widely used due to the ease of production. However, silver powder produced using the chemical reduction method can be contaminated by the reducing agent, the surfactant and impurity ions used during the reaction process, which can serve as a limiting factor in the field of electronics requiring high conductivity or in the field of bacteria resistance requiring high purity.
- In order to resolve these problems, it is desirable to have a method of producing high purity silver powder and silver colloids that does not require either surfactants or reducing agents, or only a minimal amount of a surfactant.
- The object of the present invention is to synthesize high purity silver particles and colloids in a process that does not require either surfactants or reducing agents, or only a minimal amount of a surfactant. In the present invention, this object is achieved by dispersing silver oxalates into an appropriate carrier and then thermally decomposing the silver oxalates at a temperature of 100° C. or higher to synthesize high purity silver particles and colloids.
- The process of synthesizing silver particles and colloids by the method of the present invention comprises: (i) a silver oxalate synthesizing process; (ii) a process of dispersing silver oxalates into an appropriate carrier, for example, water, alcohol or the like, including a combination of more than one carrier; and (iii) a process of heating said silver oxalates dispersed into said carrier at a temperature of 100° C. or higher under a pressure greater than atmospheric pressure.
- These and other features, objects and advantages of the present invention will become better understood from a consideration of the following detailed description of the preferred embodiments and appended claims in conjunction with the drawings as described following.
-
FIG. 1 is a microphotograph of silver particles obtained under the conditions described in Example 1. -
FIG. 2 is a microphotograph of silver particles obtained under the conditions described in Example 2. -
FIG. 3 is a microphotograph of silver particles obtained under the conditions described in Example 3. -
FIG. 4 is a microphotograph of silver particles obtained under the conditions described in Example 4. -
FIG. 5 is a microphotograph of silver particles obtained under the conditions described in Example 5. -
FIG. 6 is a microphotograph of silver particles obtained under the conditions described in Example 6. - With reference to
FIGS. 1-6 , the preferred embodiments of the present invention may be described as follows. - In the present invention, a method for the production of silver particles and colloids comprises three processes as follows: (i) a silver oxalate (Ag2C2o4) synthesizing process; (ii) a process of dispersing silver oxalate into an appropriate carrier, for example, water, alcohol or the like, including a combination of more than one carrier; and (iii) a process of heating said silver oxalate dispersed into said carrier at a temperature of 100° C. or higher under a pressure greater than atmospheric pressure to form silver particle or colloids from the decomposition of the silver oxalate.
- A first solution of a water soluble silver compound and a second solution of an oxalate compound are mixed together to precipitate silver oxalates. The silver compound may be AgNO3. The oxalate compound may be sodium oxalate or oxalic acid. The present invention is not, however, limited to these specific compounds but may include any two solutions of compounds that form silver oxalates upon mixing. After water cleaning processes, preferably two or more rounds of water cleaning processes, are performed to remove impure ions from the precipitated silver oxalate, the silver oxalate is used as the starting material for synthesizing silver powder or colloids.
- The synthesized silver oxalate is dispersed into an appropriate carrier. The silver oxalate is not dissolved to any substantial extent in the carrier, but is dispersed as solid particles by using ultrasonic treatment. The appropriate carrier may include all types of carriers which can disperse silver oxalate to effectively deliver heat. The carrier is selected to have properties that allow it to behave similarly to a surfactant so as to prevent agglomeration of the silver particles formed from the thermal decomposition of the silver oxalate. For example, alcohols consist of alkyl and hydroxyl groups. Generally, alkyl groups have hydrophobic properties and hydroxyl groups have hydrophilic properties. Organic materials having both hydrophobic and hydrophilic properties can play a role as a surfactant. However, organic materials having higher carbon numbers tend to be dominantly hydrophobic and may therefore tend to lose the ability to act as a surfactant in the process of the present invention. Generally, organic materials having higher numbers of carbon atoms have superior surfactant properties. However, in the present invention, organic materials with a higher number of carbon atoms is observed to agglomerate silver particles. Furthermore, organic materials with a higher number of carbon atoms do not mix well with water. Therefore, the present invention is limited to methyl, ethyl and propyl alcohols, which have a low number of carbon atoms. Water is also effective in the practice of the present invention. The appropriate carrier may therefore consist of ethyl alcohol, methyl alcohol, propyl alcohol, water or a combination of more than one of the preceding.
- The carriers selected for the practice of the present invention all have low boiling points: water (100° C.), methyl alcohol (64.65° C.), ethyl alcohol (78.3° C.), and propyl alcohol (82° C.). Accordingly, when the carrier with the dispersed silver oxalate is heated in a container at or above 100° C., the pressure is always above atmospheric pressure. Typical reaction pressures are about 1.86*105 N/m2 when using water as the carrier and about 5.31*105 N/m2 when using ethyl alcohol as the carrier. During thermal decomposition of silver oxalate, the silver oxalate (Ag2C2O4) decomposes into silver (Ag) and carbon dioxide (CO2) according to the formula Ag2C2O4=2Ag+2CO2. The carbon dioxide gas evolved during the thermal decomposition of the silver oxalate and the carrier vapor may be evacuated as necessary but pressure drops of less than about 6.89*104 N/m2 do not affect the quality of the silver particles.
- The dispersed silver oxalate in the carrier is placed into a closed reactor to heat the dispersed silver oxalate and carrier up to at least 100° C. to synthesize silver powder or colloids of various form factors.
- This method may optionally use surfactants in order to prevent coagulation or agglomeration of the silver particles. Surfactants may be added to the water soluble silver or oxalate solutions used to produce silver oxalate, or may be added after the silver oxalate is produced by mixing the two solutions. Surfactants used in this method may include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorochemical surfactants, and polymerizable surfactants, or combinations of the preceding, which may be added to aid in forming silver particles and to break down silver plates or prevent silver plates from coagulation. Surfactants suitable for use in the present invention include PVP (polyvinyl pyrrolidone) and gelatine.
- Irrespective of the amount of surfactant added, silver particles or colloids can be obtained by the method of the present invention, however, it is desirable to limit the amount of surfactant to no more than 80% of the weight of the silver. For example, if 10 grams of silver is placed into the reactor, the weight of the surfactant, such as PVP or gelatin, should be no more than 8 grams.
- After 2.8 grams of silver oxalate was placed into 300 cc of distilled water, ten minutes of ultrasonic treatment was performed to disperse the particles. The dispersed silver oxalate was reacted for 15 minutes at 130° C. to obtain a solution containing silver particles as shown in
FIG. 1 . - After 28 grams of silver oxalate was placed into 1000 cc of ethyl alcohol, ten minutes of ultrasonic treatment was performed to disperse the particles. The dispersed silver oxalate was reacted for 15 minutes at 134° C. to obtain silver powder as shown in
FIG. 2 . - After 70 mg of silver oxalate was placed into 1000 cc of ethyl alcohol, ten minutes of ultrasonic treatment was performed to disperse the particles. The dispersed particles were reacted for 25 minutes at 135° C. to obtain nano-sized silver particles as shown in
FIG. 3 . - After 4.2 grams of silver oxalate was placed into a mixed solution of water (vol. 50%) and ethyl alcohol (vol. 50%), the solution was reacted for 15 minutes at 130° C. to synthesize 0.5 μm silver particles as shown in
FIG. 4 . - 30 wt % of PVP (polyvinyl pyrrolidone) was placed into 4.2 grams of silver oxalate in 1 Liter of water and ultrasonic treatment was performed to disperse the particles thereof. The dispersed particles were reacted for 20 minutes at 135° C. to synthesize silver particles of 0.5 μm or smaller in size as shown in
FIG. 5 . - 10 grams of gelatin was placed into 28 grams of silver oxalate in 1 Liter of water and ultrasonic treatment was performed to disperse the particles thereof. The dispersed particles were reacted for 15 minutes at 135° C. to synthesize silver particles of 50 nm or smaller in size as shown in
FIG. 6 . - Due to its inherent characteristics of high conductivity and bacteria resistance, silver particles are widely used in the electronics industry as well as in other industries requiring bacteria resistance.
- The present invention has been described with reference to certain preferred and alternative embodiments that are intended to be exemplary only and not limiting to the full scope of the present invention as set forth in the appended claims.
Claims (19)
1. A method for production of silver particles, comprising the steps of:
(a) dispersing solid silver oxalate particles in a carrier; and
(b) heating said dispersed silver oxalate to a temperature of at least 100° C. under a pressure that is greater than atmospheric pressure to decompose said silver oxalate into silver particles.
2. The method of claim 1 , further comprising the step before step (a) of producing said silver oxalate by mixing a first solution of a silver compound and a second solution of an oxalate compound to form silver oxalate.
3. The method of claims 1 or 2 , further comprising the step of adding a surfactant to said dispersed silver oxalate before the heating of step (b).
4. The method of claim 3 wherein said surfactant is selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorochemical surfactants, polymerizable surfactants, and any combination of the preceding surfactants.
5. The method of claim 2 , further comprising the step of adding a surfactant to said first solution before said mixing step.
6. The method of claim 5 wherein said surfactant is selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluOrochemical surfactants, polymerizable surfactants, and any combination of the preceeding surfactants.
7. The method of claim 2 further comprising the step of adding a surfactant to said second solution before said mixing step.
8. The method of claim 7 wherein said surfactant is selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorochemical surfactants, polymerizable surfactants, and any combination of the preceeding surfactants.
9. The method of claims 1 or 2 , wherein the dispersing of step (a) comprises adding silver oxalate to said carrier and subjecting the mixture of silver oxalate and carrier to ultrasonic treatment.
10. The method of claims 1 or 2 , wherein said carrier is selected from the group consisting of water, methyl alcohol, ethyl alcohol, propyl alcohol, and a mixture of any of the preceding.
11. The method of claim 2 , wherein said silver compound is AgNO3.
12. The method of claim 2 , wherein said oxalate compound is selected from the group consisting of sodium oxalate and oxalic acid.
13. The method of claim 2 , further comprising the step following the production of silver oxalate of washing said silver oxalate with water to remove impurities.
14. The method of claim 4 , wherein said surfactant is selected from the group consisting of PVP (polyvinyl pyrrolidone) and gelatin.
15. The method of claim 6 , wherein said surfactant is selected from the group consisting of PVP (polyvinyl pyrrolidone) and gelatin.
16. The method of claim 8 , wherein said surfactant is selected from the group consisting of PVP (polyvinyl pyrrolidone) and gelatin.
17. The method of claim 3 , wherein said surfactant is no greater than 80% by weight of the silver in step (b).
18. The method of claim 5 , wherein said surfactant is no greater than 80% by weight of the silver in step (b).
19. The method of claim 7 , wherein said surfactant is no greater than 80% by weight of the silver in step (b).
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US11/664,640 US20080105085A1 (en) | 2004-10-14 | 2005-10-13 | Method Of Production Of High Purity Silver Particles |
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US61887604P | 2004-10-14 | 2004-10-14 | |
US11/664,640 US20080105085A1 (en) | 2004-10-14 | 2005-10-13 | Method Of Production Of High Purity Silver Particles |
PCT/US2005/036727 WO2006049831A1 (en) | 2004-10-14 | 2005-10-13 | Method of production of high purity silver particles |
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US (1) | US20080105085A1 (en) |
EP (1) | EP1819467A4 (en) |
JP (1) | JP2008517153A (en) |
KR (1) | KR100888559B1 (en) |
CN (1) | CN101065205A (en) |
WO (1) | WO2006049831A1 (en) |
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US20100226851A1 (en) * | 2006-09-21 | 2010-09-09 | Insoo Kim | Low temperature process for producing nano-sized titanium dioxide particles |
US20110088593A1 (en) * | 2010-12-23 | 2011-04-21 | Mansour Hemmati | Silver dz nano-fluid composition for nano-fin formation and a method of producing the same |
US9545668B2 (en) | 2009-11-27 | 2017-01-17 | Tokusen Kogyo Co., Ltd. | Fine metal particle-containing composition |
US20180096747A1 (en) * | 2012-02-13 | 2018-04-05 | Dowa Electronics Materials Co., Ltd. | Spherical silver powder and method for producing same |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US20080064592A1 (en) * | 2004-10-14 | 2008-03-13 | Insoo Kim | Method for Synthesizing Nano-Sized Titanium Dioxide Particles |
US20100226851A1 (en) * | 2006-09-21 | 2010-09-09 | Insoo Kim | Low temperature process for producing nano-sized titanium dioxide particles |
US8557217B2 (en) | 2006-09-21 | 2013-10-15 | Tokusen, U.S.A., Inc. | Low temperature process for producing nano-sized titanium dioxide particles |
US9545668B2 (en) | 2009-11-27 | 2017-01-17 | Tokusen Kogyo Co., Ltd. | Fine metal particle-containing composition |
US20110088593A1 (en) * | 2010-12-23 | 2011-04-21 | Mansour Hemmati | Silver dz nano-fluid composition for nano-fin formation and a method of producing the same |
US20180096747A1 (en) * | 2012-02-13 | 2018-04-05 | Dowa Electronics Materials Co., Ltd. | Spherical silver powder and method for producing same |
Also Published As
Publication number | Publication date |
---|---|
KR100888559B1 (en) | 2009-03-16 |
CN101065205A (en) | 2007-10-31 |
KR20070073775A (en) | 2007-07-10 |
EP1819467A4 (en) | 2010-01-20 |
JP2008517153A (en) | 2008-05-22 |
EP1819467A1 (en) | 2007-08-22 |
WO2006049831A1 (en) | 2006-05-11 |
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