WO2020106120A1 - Method for preparing monodispersed silver powder - Google Patents

Method for preparing monodispersed silver powder

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Publication number
WO2020106120A1
WO2020106120A1 PCT/KR2019/016204 KR2019016204W WO2020106120A1 WO 2020106120 A1 WO2020106120 A1 WO 2020106120A1 KR 2019016204 W KR2019016204 W KR 2019016204W WO 2020106120 A1 WO2020106120 A1 WO 2020106120A1
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Prior art keywords
silver powder
silver
reaction solution
reaction
acid
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PCT/KR2019/016204
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French (fr)
Korean (ko)
Inventor
강태훈
김영환
이미영
이창근
진우민
최재원
Original Assignee
엘에스니꼬동제련 주식회사
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Publication of WO2020106120A1 publication Critical patent/WO2020106120A1/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00Making metallic powder or suspensions thereof
    • B22F9/16Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/06Metallic powder characterised by the shape of the particles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2301/00Metallic composition of the powder or its coating
    • B22F2301/25Noble metals, i.e. Ag Au, Ir, Os, Pd, Pt, Rh, Ru
    • B22F2301/255Silver or gold

Definitions

  • the present invention relates to a method for manufacturing silver powder contained in a conductive paste used in electronic components, such as an electrode for a solar cell, an internal electrode of a multilayer capacitor, and a conductor pattern of a circuit board, and a conductive paste containing silver powder.
  • Silver is widely used as an electrode material in the field of electrical and electronic due to its inherent high electrical conductivity and oxidation stability.
  • an industry for conductive pastes in which silver is powdered and processed into a paste or ink form has been developed.
  • Conductive pastes using silver powder have various uses such as plasma display panel (PDP), solar cell front electrode or rear electrode, and touch screen, as well as traditional conductive electrodes such as through-holes, die-bonding, and chip parts. This is an increasing trend.
  • silver powder for solar cell electrodes often has non-uniform nucleation during synthesis, agglomeration of powders due to difference in reaction rate, and wide particle size distribution, which causes defects due to disconnection and short circuit between electrodes in the printing process after paste preparation. .
  • the present invention is to solve the above problems to solve the agglomeration of the silver powder and to provide an economical manufacturing method capable of mass-producing sub-micro grade fine powder.
  • the present invention is a reaction solution production step (S21) for preparing a first reaction solution containing a silver ion, ammonia (NH 3) and an organic acid alkali metal salt and a second reaction solution containing a reducing agent; And a silver salt reduction step (S2) including a precipitation step (S22) of reacting the first reaction solution and the second reaction solution while freely falling in the air to obtain silver powder.
  • S21 reaction solution production step
  • S2 for preparing a first reaction solution containing a silver ion, ammonia (NH 3) and an organic acid alkali metal salt and a second reaction solution containing a reducing agent
  • S2 silver salt reduction step
  • S22 precipitation step
  • the first reaction solution and the second reaction solution are respectively supplied at a specific height of the reaction tank through a supply line capable of adjusting the flow rate while the first reaction solution and the second reaction solution are freely dropped. It is characterized by reacting.
  • the height (H) to which the first reaction solution and the second reaction solution are supplied is characterized in that the reaction tank and the reaction temperature of the reaction tank are 30 to 50 ° C.
  • the alkali metal salt of the organic acid is acetic acid (CH3COOH), formic acid (CH2O2), oxalic acid (C2H2O4), lactic acid (C3H6O3), citric acid (C6H8O7), fumaric acid (C4H4O4), citric acid (C6H8O7), butyric acid (C4H8O2), butyric acid (C4H8O2) )
  • any one or more organic acids selected from the group consisting of uric acid (C5H4N4O3) and lithium (Li), sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg). Characterized in that it comprises a salt formed by any one or more metals.
  • the organic acid alkali metal salt is characterized in that it is added at a ratio of 300 to 600 g with respect to 1600 ml of the 500 g / L silver nitrate (AgNO3).
  • the present invention is a silver powder produced by the above manufacturing method, wherein the silver powder has a SEM size (DSEM) of 03 to 13 ⁇ m and a PSA size (D50) of 01 to 20 ⁇ m.
  • DSEM SEM size
  • D50 PSA size
  • the silver powder is characterized in that the span value calculated by the following formula (span value) is 10 or less.
  • D90, D10, and D50 mean particle sizes corresponding to 90%, 10%, and 50% of the maximum value in the cumulative distribution of solid particle size, respectively.
  • the silver powder is characterized in that the aggregation degree calculated by the ratio (D50 / DSEM) of PSA size (D50, ⁇ m) to SEM size (DSEM, ⁇ m) is 17 or less.
  • the present invention can obtain a monodispersed silver powder having a size of 03 to 13 ⁇ m (SEM size) by precipitating silver powder by an air-free fall method, and can prevent agglomeration from occurring, and the amount of organic acid alkali metal salt added and the reaction temperature By controlling the, even if a fine powder having a size of about 03 ⁇ m is manufactured, it is possible to maintain monodispersity and prevent aggregation from occurring.
  • SEM size size
  • Figure 1 shows a process schematic diagram of the precipitation step according to an embodiment of the present invention.
  • the terms comprise, comprises, comprising means referring to an article, step or group of articles, and steps, and any other article It is not intended to exclude a stage or group of things or a group of stages.
  • a silver powder having a level of 0.3 to 1.3 ⁇ m can be obtained by preparing a silver powder by adjusting an air-free fall reaction and an input amount of oxalic acid.
  • the method for preparing silver powder according to an embodiment of the present invention includes a silver salt production step (S1); Silver salt reduction step (S2); Purification step such as filtration and washing (S3); Surface treatment step (S4); And a post-treatment step (S5).
  • the method for preparing silver powder according to the present invention necessarily includes a silver salt reduction step (S2), and other steps can be omitted.
  • silver salt solution containing silver ions (Ag +) is prepared by acid treatment of silver (Ag +) in the form of an ingot, a chip, or a granule. It is a step.
  • a silver salt solution may be directly prepared through a silver salt preparation step (S1), and a subsequent step may be performed using a commercially available silver nitrate (AgNO3), silver salt complex, or silver intermediate solution.
  • the silver salt reduction step (S2) is a step of depositing silver particles by reducing silver ions by reacting the silver salt solution and the reduction solution in an air-free fall method.
  • the reaction solution production step (S21) for preparing a first reaction solution containing a silver salt solution, a first reaction solution containing ammonia and an alkali metal salt of an organic acid and a reducing agent (S21), and freely falling the first reaction solution and the second reaction solution It comprises a precipitation step (S22) to obtain a silver powder by reacting in a manner.
  • reaction solution preparation step (S21) ammonia and an organic acid alkali metal salt are added to a silver salt solution containing silver ions and stirred and dissolved to prepare a first reaction solution. More specifically, a first reaction solution is prepared by adding an alkali metal salt of an organic acid to a silver salt solution containing silver ions and adjusting the pH with ammonia.
  • the silver ion is not limited as long as it is in the form of a silver cation.
  • it may be silver nitrate (AgNO3), a silver salt complex, or a silver intermediate. It is preferable to use silver nitrate (AgNO3).
  • AgNO3 silver nitrate
  • the use of silver nitrate (AgNO3) containing silver ions will be described as an example.
  • the content of other components based on 1600 g / L silver nitrate (AgNO3) 1600 mL will be described.
  • the organic acid alkali metal salt is acetic acid (CH3COOH), formic acid (CH2O2), oxalic acid (C2H2O4), lactic acid (C3H6O3), citric acid (C6H8O7), fumaric acid (C4H4O4), citric acid (C6H8O7), butyric acid (C4H8O2), butyric acid (C4H8O2), And one or more organic acids (short-chain fatty acids) selected from the group consisting of uric acid (C5H4N4O3), lithium (Li), sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg). And salts formed by any one or more metals selected from the above.
  • potassium oxalate (C2K2O4) is used, and it is preferable to selectively use potassium sulfide.
  • the organic acid alkali metal salt may be added in a ratio of 300 to 600 g with respect to 1600 ml of the 500 g / L silver nitrate (AgNO3). It is possible to provide an effect of increasing the shrinkage rate by adding the organic acid alkali metal salt in the above range, and it is also possible to control the size of the precipitated silver powder as supported by the experimental examples to be described later.
  • the addition amount of the alkali metal salt of the organic acid is outside the above range, the pH of the first reaction solution is lowered, and thus, the reaction rate is significantly reduced. Therefore, it is difficult to secure the height for free falling in the air in the precipitation step, which will be described later.
  • the silver particles can be grown non-uniformly with the same result as reacting.
  • the addition amount of the alkali metal salt of the organic acid is adjusted within the above range, the particle size of the precipitated silver powder can be controlled, and when added beyond the above range, the powder aggregates, and there is a problem in that a silver powder of uniform size cannot be obtained.
  • Ammonia can be used in the form of an aqueous solution.
  • a 25% aqueous ammonia solution may be added at a rate of 2000 ml to 3000 ml with respect to 1600 ml of 500 g / L silver nitrate (AgNO3).
  • ammonia serves to control the pH.
  • a 25% aqueous ammonia solution When a 25% aqueous ammonia solution is added in a proportion of less than 2000 ml with respect to 1600 ml of 500 g / L silver nitrate (AgNO3), all silver ions may not be reduced or it may be difficult to form a uniform particle distribution.
  • 25% ammonia aqueous solution is added in a proportion exceeding 3000 ml with respect to 1600 ml of 500 g / L silver nitrate (AgNO3), the spheroidization or monodispersity of the powder improves as the pH increases, but the organic content in the prepared silver powder After the conductive paste is higher than the desired standard, carbon may be accumulated and conductivity may be deteriorated.
  • the ammonia includes its derivatives.
  • the reduction rate should be fast when reacting in the air free fall method.
  • the ammonia serves to control the pH and the reduction rate, and when the ammonia is included below the content, the reduction rate is lowered and the reaction rate is slowed down. Therefore, there is a problem that particles are grown non-uniformly at the bottom of the reaction tank, and if it is included in excess of the above content, the reaction rate becomes too fast, and the second reaction liquids are captured in the powder, causing a slight increase in organic matter ( ⁇ 1.5%). Can occur.
  • the above-described first reaction solution may be prepared in an aqueous solution state by adding silver ions, an alkali metal salt of an organic acid and an aqueous ammonia solution to a solvent such as water and stirring it to dissolve, and may also be prepared in a slurry form.
  • the reaction solution preparation step (S21) according to an embodiment of the present invention also prepares a second reaction solution containing a reducing agent.
  • the reducing agent may be at least one selected from the group consisting of alkanolamine, hydroquinone, hydrazine and formalin, and among them, hydroquinone may be preferably selected.
  • the reducing agent may be included in 300 to 500g with respect to 1600ml of 500g / L nitric acid contained in the first reaction solution.
  • 500g / L silver nitrate may reduce all of the silver ions when the reducing agent is less than 300g for 1600ml, and 500g / L silver nitrate may increase the organic content when reducing agent exceeds 500g for 1600ml. there is a problem.
  • the reducing agent should be included in an amount capable of reducing all of the silver ions, and by adjusting the concentration of the reducing agent included in the second reaction solution. The reduction rate can be adjusted.
  • the reduction rate may be increased by increasing the concentration of the reducing agent or increasing the reduction rate or decreasing the concentration of the reducing agent.
  • the second reaction solution containing the reducing agent may be prepared by adding a reducing agent to a solvent such as water, stirring and dissolving it to form an aqueous solution having a concentration of 5% or less.
  • Precipitation step (S22) is a step of obtaining a silver powder by reacting the first reaction solution and the second reaction solution, the first reaction solution and the preparation prepared by the reaction solution production step (S21) 2
  • the reaction solution can be reacted in a free-falling manner.
  • an appropriate amount of the reaction solution reacts uniformly and continuously during the free-fall of the reaction solutions to prevent aggregation between particles and increase dispersibility.
  • silver particles may be precipitated in a free-falling manner using a reaction liquid tank and a reaction tank as shown in FIG. 1.
  • the first reaction liquid and the second reaction liquid may be prepared in a first reaction liquid production tank and a second reaction liquid production tank, respectively.
  • the reaction liquids prepared in each tank are respectively supplied to the reaction tanks through a supply line capable of adjusting the flow rate.
  • a supply line capable of adjusting the flow rate.
  • the reaction liquid is injected through a nozzle having a diameter of 15 ⁇ to the reaction tank, it is preferable to be supplied at a flow rate of 3.8L / min to 4.5L / min.
  • the first reaction liquid and the second reaction liquid react while being supplied to the reaction tank through a nozzle and dropping in the air.
  • the height (H) at which the first reaction solution and the second reaction solution are supplied is dropped from the height of 3 m or more relative to the bottom of the reaction tank.
  • aggregation of silver powder produced when falling in the air below 3 m occurs.
  • monodisperse particles having better air-falling at a height of 5 m to 7 m can be obtained.
  • the reaction temperature of the reaction tank is adjusted to 30 to 50 ° C to react.
  • the size of the precipitated silver powder can be controlled by controlling the reaction temperature to the above range, as supported by the experimental examples described later.
  • the reaction temperature is increased, it is possible to increase the density of the powder surface, increase the crystallinity, and affect the coating degree of the coating agent, and increase the reaction temperature when the content of the organic acid alkali metal salt added to the first reaction solution is the same.
  • the particle size of the precipitated silver powder can be reduced.
  • Purification step (S3) is a step of separating and washing the silver powder dispersed in the silver powder dispersion obtained at the bottom of the reaction tank through filtration through silver salt (S31) (S31) ). More specifically, after the silver particles in the silver powder dispersion are precipitated, the supernatant of the dispersion is discarded, filtered using a centrifuge, and the filter medium is washed with pure water. The washing process can completely remove the washing water from washing the powder.
  • the purification step (S3) may further include a drying and disintegration step (S32) after washing.
  • the water content may be 10% or less, but the present invention is not limited thereto.
  • the surface treatment step (S4) is a step of hydrophobicizing the hydrophilic surface of the silver powder, and may be selectively performed. This is because if the silver powder has a hydrophilic surface, properties may change due to moisture and surface oxidation during long-term storage, and may have a great influence on compatibility with organic solvents and final printing properties when prepared with a conductive paste.
  • the surface treatment agent a single or multiple compounds in the form of a salt or emulsion may be used.
  • hydrophobicity may be imparted to the silver powder by adding a surface treatment agent containing octadecylamine to the silver powder obtained after filtration.
  • octadecylamine may contain 0.01 to 0.1 parts by weight (eg, 0.03 parts by weight) with respect to 100 parts by weight of silver nitrate.
  • the silver powder can be obtained again through filtration, washing, drying, and crushing.
  • the silver powder is surface-treated, the powder must be well dispersed, so that the surface treatment is sufficiently achieved. If the water content is low, the dispersion efficiency decreases, so that the surface treatment is performed with a certain amount of water content (for example, 70 to 85%). good.
  • the post-treatment step (S5) may include a crushing process for dispersing the agglomerated powder and drying the silver powder obtained after the surface treatment, and a classification process for removing the coarse powder.
  • the crushing process may be performed at a constant air pressure (for example, 0.4 kgf) and a feeding speed (for example, 30 to 60 g / min) using a jet mill or the like, but the present invention is limited thereto. It does not work.
  • the silver powder prepared according to the method of manufacturing a silver powder according to an embodiment of the present invention has a SEM size (DSEM) of 0.3 to 1.3 ⁇ m, a PSA size (D50) of 1.0 to 2.0 ⁇ m, and is measured in an experimental example to be described later.
  • the resulting span value is 1.0 or less, and the degree of aggregation (D50 / DSEM) measured in the experimental examples to be described later is 1.7 or less.
  • the SEM size is less than 0.3 ⁇ m, and even fine silver powder, which appears to be monodisperse on the SEM image, can be manufactured.
  • the present invention also provides a conductive paste comprising silver powder prepared according to one embodiment of the present invention. More specifically, the conductive paste according to the present invention can be suitably used for forming a solar cell electrode, including silver powder, glass frit, and organic vehicle prepared according to the present invention.
  • the conductive paste composition according to the present invention may further include additives commonly known as necessary, for example, dispersants, plasticizers, viscosity modifiers, surfactants, oxidizing agents, metal oxides, metal organic compounds, and the like.
  • the present invention also provides a method for forming an electrode of a solar cell, characterized in that the conductive paste is applied onto a substrate, dried and fired, and a solar cell electrode produced by the method. Except for using the conductive paste containing the silver powder of the above characteristics in the method for forming a solar cell electrode of the present invention, substrates, printing, drying and firing can be used, as well as methods commonly used in the manufacture of solar cells. to be.
  • the substrate may be a silicon wafer.
  • a first reaction solution was prepared by adding and stirring 1600 ml of silver nitrate (500 g / L), 380 g of potassium oxalate, and 2560 ml of ammonia (concentration 25%) in 15840 g of pure water at room temperature in the first reaction solution tank. Meanwhile, in the second reaction liquid tank, 400 g of hydroquinone was added to 20000 g of pure water at room temperature and stirred to prepare a second reaction liquid.
  • the flow rate was controlled at 3.8L / min 4.5L / min using a chemical pump from WILO, and the reaction solution was transferred to the reaction tank, respectively, and then sprayed from the nozzle (air-dropping method) to generate the first reaction solution and the second reaction solution.
  • the silver powder dispersion liquid containing silver powder that reacted and precipitated while falling in the air was recovered from the bottom of the reaction tank.
  • the reaction temperature of the reaction tank was 35 ° C, and the drop heights of the first reaction solution and the second reaction solution were 6 m.
  • the supernatant of the dispersion is discarded, filtered using a centrifuge, and the filter medium is washed with pure water. Thereafter, the washing water was removed to a water content of less than 10%. After this, a surface treatment agent was added, and the water content was adjusted to 70 to 85%, and the final silver powder was obtained through drying and crushing.
  • Silver powder was obtained in the same manner as in Example 1, except that the drop heights of the first reaction solution and the second reaction solution were 3 m.
  • Silver powder was obtained in the same manner as in Example 1, except that the reaction tank had a reaction temperature of 50 ° C.
  • Silver powder was obtained in the same manner as in Example 1, except that the drop heights of the first reaction solution and the second reaction solution were 2 m.
  • Example 1 15480 1600 380 2560 20000 400 Airdrop 35 6
  • Example 2 15480 1600 380 2560 20000 400 Airdrop 35 3
  • Example 3 15480 1600 380 2560 20000 400 Airdrop 50 6
  • Example 4 15480 1600 570 2560 20000 400 Airdrop 50 6 Comparative Example 1 15480 1600 380 2560 20000 400 Airdrop 35 2 Comparative Example 2 15480 1600 380 2560 20000 400 Airdrop 35 -
  • the silver powder prepared according to the Examples and Comparative Examples of the present invention was measured using a scanning electron microscope manufactured by JEOL, and the diameter of each of the 100 powders was measured and averaged to measure the SEM size ( ⁇ m). It is shown in Table 2 below. In addition, SEM images of silver powders prepared according to Examples and Comparative Examples are shown in FIGS. 2 to 7.
  • D90, D10, and D50 mean particle sizes corresponding to 90%, 10%, and 50% of the maximum value in the cumulative distribution of solid particle size, respectively.
  • the span value is small, it means that the distribution of the particle size is narrow, and it can be seen that a silver powder of uniform size was produced.
  • the ratio (D50 / DSEM) of PSA size (D50, ⁇ m) to SEM size (DSEM, ⁇ m) was calculated. It means that the PSA particle size, in which particle size analysis of particles dispersed by light scattering into one particle, is smaller than the particle size measured by SEM imaging, has better dispersion.

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  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Abstract

The method for preparing a silver powder according to the present invention relates to a method for preparing a silver powder, comprising: a reaction solution preparation step (S21) for preparing a first reaction solution comprising a silver ion, ammonia (NH3), and an organic acid alkali metal salt, and a second reaction solution comprising a reducing agent; and a salt reduction step (S2) comprising a deposition step (S22) for acquiring a silver powder by allowing the first reaction solution and the second reaction solution to free fall in the air and react, wherein a monodispersed silver powder having a SEM size of 0.3-1.3 μm can be acquired by depositing the silver powder through the mid-air free fall method.

Description

단분산 은 분말의 제조방법Manufacturing method of monodisperse silver powder
본 발명은 태양전지용 전극이나 적층 콘덴서의 내부전극, 회로기판의 도체 패턴 등 전자부품에 사용되는 도전성 페이스트에 포함되는 은 분말의 제조방법 및 은 분말을 포함하는 도전성 페이스트에 관한 것이다.The present invention relates to a method for manufacturing silver powder contained in a conductive paste used in electronic components, such as an electrode for a solar cell, an internal electrode of a multilayer capacitor, and a conductor pattern of a circuit board, and a conductive paste containing silver powder.
은(silver)은 고유의 높은 전기전도도와 산화안정성으로 인해 전기 전자 분야에서 전극재료로서 널리 사용되고 있다. 특히 최근에는 원하는 형태의 회로를 직접적으로 형성하는 인쇄전자기술의 발달에 힘입어 은을 분말화하고 이를 페이스트나 잉크형태로 가공한 도전성 페이스트에 관한 산업이 발달하고 있다. 은 분말이 사용되는 도전성 페이스트는 쓰루홀, 다이본딩, 칩부품 등의 전통적인 도전 전극뿐만 아니라 플라스마 디스플레이 패널(PDP), 태양전지 전면 전극 또는 후면 전극, 터치스크린 등 그 사용처가 다양하고 계속해서 그 사용량이 증가되고 있는 추세이다.Silver is widely used as an electrode material in the field of electrical and electronic due to its inherent high electrical conductivity and oxidation stability. In particular, in recent years, with the development of printed electronics technology that directly forms a desired type of circuit, an industry for conductive pastes in which silver is powdered and processed into a paste or ink form has been developed. Conductive pastes using silver powder have various uses such as plasma display panel (PDP), solar cell front electrode or rear electrode, and touch screen, as well as traditional conductive electrodes such as through-holes, die-bonding, and chip parts. This is an increasing trend.
종래부터, 은 분말의 제조에는, 질산은 수용액과 암모니아수로 은 암민 착체 수용액을 제조하고, 이것에 유기환원제를 첨가하는 습식환원 프로세스가 적용되었다. 이러한 은 분말은 칩 부품, 플라즈마 디스플레이 패널, 태양 전지 등의 전극이나 회로의 형성에 이용되고 있다.Conventionally, in the production of silver powder, a wet reduction process in which an aqueous silver nitrate complex is prepared with an aqueous silver nitrate solution and ammonia water and an organic reducing agent is added thereto has been applied. These silver powders are used for forming electrodes or circuits such as chip parts, plasma display panels, and solar cells.
특히 태양전지 전극용 은 분말은 합성 시 불균일 핵생성, 반응속도 차이로 인한 분말의 응집 및 넓은 입도분포를 가지는 경우가 많으며, 이는 페이스트 제조 후 인쇄 공정에서 단선 및 전극간 단락으로 인한 불량을 발생시킨다.In particular, silver powder for solar cell electrodes often has non-uniform nucleation during synthesis, agglomeration of powders due to difference in reaction rate, and wide particle size distribution, which causes defects due to disconnection and short circuit between electrodes in the printing process after paste preparation. .
일반적으로 덤핑방식의 반응에서는 환원제 투입속도와 조성, 핵생성-성장간의 미스매치 및 반응기 외벽에서의 은거울 반응으로 인하여 불균일 성장이 이뤄지며, 이를 보완하기 위하여 PVP, 젤라틴 등의 분산제를 적용하지만, 분말의 유기물 함량 증가 및 그로 인한 전극 특성 저하 등의 문제가 발생할 수 있는 등 단점을 가진다.In general, in the reaction of the dumping method, heterogeneous growth is achieved due to the rate and composition of the reducing agent, mismatch between nucleation-growth, and the silver mirror reaction on the outer wall of the reactor.To compensate for this, dispersants such as PVP and gelatin are applied, but powder It has disadvantages such as problems such as an increase in the organic matter content and a decrease in electrode characteristics.
본 발명은 상기와 같은 문제점을 해결하기 위한 것으로 은 분말의 응집을 해소하고 서브마이크로 급의 미세분말을 대량 생산 가능한 경제적 제조방법을 제공하고자 한다.The present invention is to solve the above problems to solve the agglomeration of the silver powder and to provide an economical manufacturing method capable of mass-producing sub-micro grade fine powder.
그러나 본 발명의 목적들은 상기에 언급된 목적으로 제한되지 않으며, 언급되지 않은 또 다른 목적들은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다.However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.
본 발명은 은 이온, 암모니아(NH3) 및 유기산 알칼리 금속염을 포함하는 제1 반응액 및 환원제를 포함하는 제2 반응액을 제조하는 반응액제조단계(S21); 및 제1 반응액 및 제2 반응액을 공중 자유 낙하시키면서 반응시켜 은 분말을 얻는 석출단계(S22)를 포함하는 은 염 환원단계(S2);를 포함하는 은 분말의 제조방법을 제공한다.The present invention is a reaction solution production step (S21) for preparing a first reaction solution containing a silver ion, ammonia (NH 3) and an organic acid alkali metal salt and a second reaction solution containing a reducing agent; And a silver salt reduction step (S2) including a precipitation step (S22) of reacting the first reaction solution and the second reaction solution while freely falling in the air to obtain silver powder.
또한 상기 석출단계(S22)는 상기 제1 반응액 및 제2 반응액을 유량 조절이 가능한 공급라인을 통하여 반응 탱크의 특정 높이에서 각각 공급하여 상기 제1 반응액과 제2 반응액이 자유 낙하하면서 반응하도록 하는 것을 특징으로 한다.In addition, in the precipitation step (S22), the first reaction solution and the second reaction solution are respectively supplied at a specific height of the reaction tank through a supply line capable of adjusting the flow rate while the first reaction solution and the second reaction solution are freely dropped. It is characterized by reacting.
또한 상기 제1 반응액과 제2 반응액이 공급되는 높이(H)는 상기 반응 탱크 또한 상기 반응 탱크의 반응 온도는 30 내지 50℃ 인 것을 특징으로 한다.In addition, the height (H) to which the first reaction solution and the second reaction solution are supplied is characterized in that the reaction tank and the reaction temperature of the reaction tank are 30 to 50 ° C.
또한 상기 유기산 알칼리 금속염은 초산(CH3COOH), 포름산(CH2O2), 옥살산(C2H2O4), 젖산(C3H6O3), 시트르산(C6H8O7), 푸마르산(C4H4O4), 구연산(C6H8O7), 뷰티르산(C4H8O2), 프로피온산(CH3CH2COOH) 및 요산(C5H4N4O3) 으로 구성되는 군에서 선택되는 어느 1종 이상의 유기산과 리튬(Li), 나트륨(Na), 칼륨(K), 칼슘(Ca) 및 마그네슘(Mg)으로 구성되는 군에서 선택되는 어느 1종 이상의 금속이 염을 형성한 것을 포함하는 것을 특징으로 한다.In addition, the alkali metal salt of the organic acid is acetic acid (CH3COOH), formic acid (CH2O2), oxalic acid (C2H2O4), lactic acid (C3H6O3), citric acid (C6H8O7), fumaric acid (C4H4O4), citric acid (C6H8O7), butyric acid (C4H8O2), butyric acid (C4H8O2) ) And any one or more organic acids selected from the group consisting of uric acid (C5H4N4O3) and lithium (Li), sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg). Characterized in that it comprises a salt formed by any one or more metals.
또한 상기 은 이온이 500g/L의 질산은(AgNO3) 수용액으로 첨가될 경우, 상기 유기산 알칼리 금속염은 상기 500g/L의 질산은(AgNO3) 1600ml에 대하여 300 내지 600g 비율로 첨가되는 것을 특징으로 한다.In addition, when the silver ion is added as a 500 g / L silver nitrate (AgNO3) aqueous solution, the organic acid alkali metal salt is characterized in that it is added at a ratio of 300 to 600 g with respect to 1600 ml of the 500 g / L silver nitrate (AgNO3).
또한 본 발명은 상기 제조방법에 의해 제조되는 은 분말로서, 상기 은 분말은 SEM size(DSEM) 가 03 내지 13 μm 이며, PSA size(D50)가 01 내지 20μm 인 것을 특징으로 한다.In addition, the present invention is a silver powder produced by the above manufacturing method, wherein the silver powder has a SEM size (DSEM) of 03 to 13 μm and a PSA size (D50) of 01 to 20 μm.
또한 상기 은 분말은 하기 식에 의해 계산되는 스팬값(span value)이 10 이하인 것을 특징으로 한다.In addition, the silver powder is characterized in that the span value calculated by the following formula (span value) is 10 or less.
Span value=(D90-D10)/D50 Span value = (D90-D10) / D50
(여기서 D90, D10 및 D50은 각각 고형분 입도의 누적분포에서 최대값에 대하여 90%, 10% 및 50%에 해당하는 입도를 의미한다.) (Here, D90, D10, and D50 mean particle sizes corresponding to 90%, 10%, and 50% of the maximum value in the cumulative distribution of solid particle size, respectively.)
또한 상기 은 분말은 SEM size(DSEM, μm) 에 대한 PSA size(D50, μm)의 비(D50/DSEM)로 계산되는 응집도가 17 이하인 것을 특징으로 한다.In addition, the silver powder is characterized in that the aggregation degree calculated by the ratio (D50 / DSEM) of PSA size (D50, μm) to SEM size (DSEM, μm) is 17 or less.
본 발명은 공중 자유 낙하 방식으로 은 분말을 석출하여 03~13μm 크기(SEM size)의 단분산된 은 분말을 얻을 수 있으며, 응집이 발생하는 것을 방지할 수 있고, 유기산 알칼리 금속염의 첨가량 및 반응 온도를 조절함으로써 약 03μm 크기의 미세 분말이 제조되더라도 단분산을 유지하며 응집이 발생하는 것을 방지할 수 있다.The present invention can obtain a monodispersed silver powder having a size of 03 to 13 μm (SEM size) by precipitating silver powder by an air-free fall method, and can prevent agglomeration from occurring, and the amount of organic acid alkali metal salt added and the reaction temperature By controlling the, even if a fine powder having a size of about 03 μm is manufactured, it is possible to maintain monodispersity and prevent aggregation from occurring.
도 1은 본 발명의 일실시예에 따른 석출단계의 공정 모식도를 나타낸 것이다.Figure 1 shows a process schematic diagram of the precipitation step according to an embodiment of the present invention.
도 2는 실시예 1에 따른 은 분말의 SEM 사진이고,2 is a SEM photograph of the silver powder according to Example 1,
도 3은 실시예 2에 따른 은 분말의 SEM 사진이고,3 is a SEM photograph of the silver powder according to Example 2,
도 4는 실시예 3에 따른 은 분말의 SEM 사진이고,4 is a SEM photograph of the silver powder according to Example 3,
도 5는 실시예 4에 따른 은 분말의 SEM 사진이고,5 is a SEM photograph of the silver powder according to Example 4,
도 6은 비교예 1에 따른 은 분말의 SEM 사진이고,6 is a SEM photograph of the silver powder according to Comparative Example 1,
도 7은 비교예 1에 따른 은 분말의 SEM 사진이다.7 is a SEM photograph of the silver powder according to Comparative Example 1.
이하에 본 발명을 상세하게 설명하기에 앞서, 본 명세서에 사용된 용어는 특정의 실시예를 기술하기 위한 것일 뿐 첨부하는 특허청구의 범위에 의해서만 한정되는 본 발명의 범위를 한정하려는 것은 아님을 이해하여야 한다. 본 명세서에 사용되는 모든 기술용어 및 과학용어는 다른 언급이 없는 한은 기술적으로 통상의 기술을 가진 자에게 일반적으로 이해되는 것과 동일한 의미를 가진다.Before describing the present invention in detail below, it is understood that the terms used herein are only for describing specific embodiments and are not intended to limit the scope of the present invention, which is limited only by the scope of the appended claims. shall. All technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the art unless otherwise stated.
본 명세서 및 청구범위의 전반에 걸쳐, 다른 언급이 없는 한 포함(comprise, comprises, comprising)이라는 용어는 언급된 물건, 단계 또는 일군의 물건, 및 단계를 포함하는 것을 의미하고, 임의의 어떤 다른 물건, 단계 또는 일군 의 물건 또는 일군의 단계를 배제하는 의미로 사용된 것은 아니다.Throughout this specification and claims, unless otherwise stated, the terms comprise, comprises, comprising means referring to an article, step or group of articles, and steps, and any other article It is not intended to exclude a stage or group of things or a group of stages.
한편, 본 발명의 여러 가지 실시예들은 명확한 반대의 지적이 없는 한 그 외의 어떤 다른 실시예들과 결합될 수 있다. 특히 바람직하거나 유리하다고 지시하는 어떤 특징도 바람직하거나 유리하다고 지시한 그 외의 어떤 특징 및 특징들과 결합될 수 있다. 이하, 첨부된 도면을 참조하여 본 발명의 실시예 및 이에 따른 효과를 설명하기로 한다.On the other hand, various embodiments of the present invention can be combined with any other embodiments, unless otherwise indicated. Any feature indicated as particularly preferred or advantageous may be combined with any other feature or features indicated as preferred or advantageous. Hereinafter, embodiments and effects according to the present invention will be described with reference to the accompanying drawings.
본 발명의 일실시예에 따른 은 분말의 제조방법에서는 공중 자유 낙하 반응 및 옥살산 투입량을 조절하여 은 분말을 제조함으로써, 0.3~1.3μm 수준의 단분산 은 분말을 얻을 수 있다.In the method of manufacturing a silver powder according to an embodiment of the present invention, a silver powder having a level of 0.3 to 1.3 μm can be obtained by preparing a silver powder by adjusting an air-free fall reaction and an input amount of oxalic acid.
본 발명의 일실시예에 따른 은 분말의 제조방법은 은 염 제조단계(S1); 은 염 환원단계(S2); 여과 및 세척 등 정제단계(S3); 표면처리단계(S4); 및 후처리 단계(S5)를 포함하여 이루어진다. 본 발명에 따른 은 분말의 제조방법은 은 염 환원단계(S2)를 반드시 포함하고, 이외의 단계는 생략 가능하다.The method for preparing silver powder according to an embodiment of the present invention includes a silver salt production step (S1); Silver salt reduction step (S2); Purification step such as filtration and washing (S3); Surface treatment step (S4); And a post-treatment step (S5). The method for preparing silver powder according to the present invention necessarily includes a silver salt reduction step (S2), and other steps can be omitted.
본 발명의 일실시예에 따른 은 염 제조단계(S1)는 잉곳, 칩, 그래뉼 형태의 은(silver, Ag)을 산처리하여 은 이온(Ag+)을 포함하는 은 염(silver salt) 용액을 제조하는 단계이다. 본 발명에서는 은 염 제조단계(S1)를 거쳐 은 염 용액을 직접 제조할 수도 있고, 시중에서 구입한 질산은(AgNO3), 은 염 착체 또는 은 중간체 용액을 이용하여 이후 단계를 진행할 수 있다.In the silver salt production step (S1) according to an embodiment of the present invention, silver salt solution containing silver ions (Ag +) is prepared by acid treatment of silver (Ag +) in the form of an ingot, a chip, or a granule. It is a step. In the present invention, a silver salt solution may be directly prepared through a silver salt preparation step (S1), and a subsequent step may be performed using a commercially available silver nitrate (AgNO3), silver salt complex, or silver intermediate solution.
본 발명의 일실시예에 따른 은 염 환원단계(S2)는 은 염 용액과 환원 용액을 공중 자유 낙하 방식으로 반응시켜 은 이온을 환원킴으로써 은 입자(silver particle)를 석출하는 단계이다. 구체적으로 은 염 용액, 암모니아 및 유기산 알칼리 금속염을 포함하는 제1 반응액 및 환원제을 포함하는 제2 반응액을 제조하는 반응액제조단계(S21) 및 제1 반응액 및 제2 반응액을 공중 자유 낙하 방식으로 반응시켜 은 분말을 얻는 석출단계(S22)를 포함한다.The silver salt reduction step (S2) according to an embodiment of the present invention is a step of depositing silver particles by reducing silver ions by reacting the silver salt solution and the reduction solution in an air-free fall method. Specifically, the reaction solution production step (S21) for preparing a first reaction solution containing a silver salt solution, a first reaction solution containing ammonia and an alkali metal salt of an organic acid and a reducing agent (S21), and freely falling the first reaction solution and the second reaction solution It comprises a precipitation step (S22) to obtain a silver powder by reacting in a manner.
본 발명의 일실시예에 따른 반응액제조단계(S21)는 은 이온을 포함하는 은 염 용액에 암모니아, 유기산 알칼리 금속염을 첨가하고 이를 교반 용해하여 제1 반응액을 제조한다. 더욱 구체적으로, 은 이온을 포함하는 은 염 용액에 유기산 알칼리 금속염을 첨가하고 암모니아로 pH를 조절하여 제1 반응액을 제조한다.In the reaction solution preparation step (S21) according to an embodiment of the present invention, ammonia and an organic acid alkali metal salt are added to a silver salt solution containing silver ions and stirred and dissolved to prepare a first reaction solution. More specifically, a first reaction solution is prepared by adding an alkali metal salt of an organic acid to a silver salt solution containing silver ions and adjusting the pH with ammonia.
상기 은 이온은 은 양이온의 형태라면 제한되지 않는다. 일례로 질산은(AgNO3), 은 염 착체 또는 은 중간체일 수 있다. 바람직하게는 질산은(AgNO3)을 사용하는 것이 좋다. 이하 은 이온을 포함하는 질산은(AgNO3)을 사용하는 것을 일예시로 서술한다. 이하 500g/L의 질산은(AgNO3) 1600mL를 기준으로 기타 다른 성분의 함량 등을 설명한다.The silver ion is not limited as long as it is in the form of a silver cation. For example, it may be silver nitrate (AgNO3), a silver salt complex, or a silver intermediate. It is preferable to use silver nitrate (AgNO3). Hereinafter, the use of silver nitrate (AgNO3) containing silver ions will be described as an example. Hereinafter, the content of other components based on 1600 g / L silver nitrate (AgNO3) 1600 mL will be described.
상기 유기산 알칼리 금속염은 초산(CH3COOH), 포름산(CH2O2), 옥살산(C2H2O4), 젖산(C3H6O3), 시트르산(C6H8O7), 푸마르산(C4H4O4), 구연산(C6H8O7), 뷰티르산(C4H8O2), 프로피온산(CH3CH2COOH) 및 요산(C5H4N4O3) 으로 구성되는 군에서 선택되는 어느 1종 이상의 유기산(단쇄지방산)과 리튬(Li), 나트륨(Na), 칼륨(K), 칼슘(Ca) 및 마그네슘(Mg)으로 구성되는 군에서 선택되는 어느 1종 이상의 금속이 염을 형성한 것을 들 수 있다. 바람직하게는 옥살산 칼륨(C2K2O4)을 사용하고, 선택적으로 황화칼륨(potassium sulfide)을 혼합하여 사용하는 것이 좋다.The organic acid alkali metal salt is acetic acid (CH3COOH), formic acid (CH2O2), oxalic acid (C2H2O4), lactic acid (C3H6O3), citric acid (C6H8O7), fumaric acid (C4H4O4), citric acid (C6H8O7), butyric acid (C4H8O2), butyric acid (C4H8O2), And one or more organic acids (short-chain fatty acids) selected from the group consisting of uric acid (C5H4N4O3), lithium (Li), sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg). And salts formed by any one or more metals selected from the above. Preferably, potassium oxalate (C2K2O4) is used, and it is preferable to selectively use potassium sulfide.
상기 500g/L의 질산은(AgNO3) 1600ml에 대하여 상기 유기산 알칼리 금속염이 300 내지 600g 첨가되는 비율로 첨가될 수 있다. 유기산 알칼리 금속염을 상기 범위로 첨가하여 수축 속도를 높이는 효과를 제공할 수 있으며, 또한 후술할 실험예에 의해 뒷받침되는 것과 같이 석출되는 은 분말의 크기를 제어할 수 있다. 유기산 알칼리 금속염의 첨가량이 상기 범위를 벗어나면 제1 반응액의 pH가 낮아지게 되고, 따라서 반응속도가 현저히 감소하므로 후술할 석출단계에서 공중 자유 낙하시키기 위한 높이 확보가 어려워 반응탱크 하부에서 덤핑 방식으로 반응시키는 것과 동일한 결과로 은 입자가 불균일 성장될 수 있는 문제점이 있다. 또한 유기산 알칼리 금속염의 첨가량을 상기 범위 내에서 조절하면 석출되는 은 분말의 입경을 조절 가능하고, 상기 범위를 넘어서 첨가하는 경우 분말이 응집되며, 균일한 크기의 은 분말을 얻을 수 없는 문제점이 있다.The organic acid alkali metal salt may be added in a ratio of 300 to 600 g with respect to 1600 ml of the 500 g / L silver nitrate (AgNO3). It is possible to provide an effect of increasing the shrinkage rate by adding the organic acid alkali metal salt in the above range, and it is also possible to control the size of the precipitated silver powder as supported by the experimental examples to be described later. When the addition amount of the alkali metal salt of the organic acid is outside the above range, the pH of the first reaction solution is lowered, and thus, the reaction rate is significantly reduced. Therefore, it is difficult to secure the height for free falling in the air in the precipitation step, which will be described later. There is a problem that the silver particles can be grown non-uniformly with the same result as reacting. In addition, when the addition amount of the alkali metal salt of the organic acid is adjusted within the above range, the particle size of the precipitated silver powder can be controlled, and when added beyond the above range, the powder aggregates, and there is a problem in that a silver powder of uniform size cannot be obtained.
암모니아(NH3)는 수용액 형태로 사용될 수 있다. 예를 들어 25% 암모니아 수용액을 사용하는 경우 500g/L의 질산은(AgNO3) 1600ml에 대하여 25%의 암모니아 수용액이 2000ml 내지 3000ml 첨가되는 비율로 첨가될 수 있다. 상술한 바와 같이 본 발명에서는 암모니아가 pH를 제어하는 역할을 한다.Ammonia (NH3) can be used in the form of an aqueous solution. For example, when a 25% aqueous ammonia solution is used, a 25% aqueous ammonia solution may be added at a rate of 2000 ml to 3000 ml with respect to 1600 ml of 500 g / L silver nitrate (AgNO3). As described above, in the present invention, ammonia serves to control the pH.
500g/L의 질산은(AgNO3) 1600ml에 대하여 25%의 암모니아 수용액이 2000ml 미만의 비율로 첨가되면, 은 이온이 모두 환원되지 않거나 균일한 입자 분포를 형성시키기 어려울 수 있다. 500g/L의 질산은(AgNO3) 1600ml에 대하여 25%의 암모니아 수용액이 3000ml를 초과한 비율로 첨가되는 경우, pH가 높아짐에 따라 분말의 구형화 또는 단분산성은 좋아지지만 제조된 은 분말 중 유기물 함량이 원하는 기준보다 높아 도전성 페이스트 제조 후 탄소가 집적되어 전도성이 저하될 수 있다. 상기 암모니아는 그 유도체를 포함한다.When a 25% aqueous ammonia solution is added in a proportion of less than 2000 ml with respect to 1600 ml of 500 g / L silver nitrate (AgNO3), all silver ions may not be reduced or it may be difficult to form a uniform particle distribution. When 25% ammonia aqueous solution is added in a proportion exceeding 3000 ml with respect to 1600 ml of 500 g / L silver nitrate (AgNO3), the spheroidization or monodispersity of the powder improves as the pH increases, but the organic content in the prepared silver powder After the conductive paste is higher than the desired standard, carbon may be accumulated and conductivity may be deteriorated. The ammonia includes its derivatives.
후술할 석출단계에서 공중 자유 낙하 방식으로 반응시키는 경우 환원속도가 빨라야 하는데, 상기 암모니아는 pH 및 환원속도를 제어할 수 있는 역할로서 암모니아가 상기 함량 미만으로 포함되는 경우 환원속도가 낮아져 반응속도가 느려지므로 입자가 반응 탱크 하부에서 불균일하게 성장될 문제가 있고, 상기 함량을 초과하여 포함되는 경우 반응속도가 너무 빨라져 제2 반응액들이 분말 내에 캡쳐링되어 유기물이 다소 증가(~1.5%) 하는 문제가 발생할 수 있다.In the precipitation step, which will be described later, the reduction rate should be fast when reacting in the air free fall method. The ammonia serves to control the pH and the reduction rate, and when the ammonia is included below the content, the reduction rate is lowered and the reaction rate is slowed down. Therefore, there is a problem that particles are grown non-uniformly at the bottom of the reaction tank, and if it is included in excess of the above content, the reaction rate becomes too fast, and the second reaction liquids are captured in the powder, causing a slight increase in organic matter (~ 1.5%). Can occur.
상술한 제1 반응액은, 물 등의 용제에 은 이온, 유기산 알칼리 금속염, 암모니아 수용액을 첨가하고 교반하여 용해시켜 수용액 상태로 제조될 수 있으며, 또한 슬러리 형태로 제조될 수 있다.The above-described first reaction solution may be prepared in an aqueous solution state by adding silver ions, an alkali metal salt of an organic acid and an aqueous ammonia solution to a solvent such as water and stirring it to dissolve, and may also be prepared in a slurry form.
본 발명의 일실시예에 따른 반응액제조단계(S21)는 또한 환원제를 포함하는 제2 반응액을 제조한다.The reaction solution preparation step (S21) according to an embodiment of the present invention also prepares a second reaction solution containing a reducing agent.
상기 환원제는 알칸올아민, 하이드로퀴논, 히드라진 및 포르말린으로 이루어지는 군으로부터 선택되는 1종 이상일 수 있으며, 이 중에서 하이드로퀴논을 바람직하게 선택할 수 있다. 이때, 환원제는 제1 반응액에 포함되는 500g/L의 질산은 1600ml에 대하여 300 내지 500g로 포함될 수 있다. 500g/L의 질산은 1600ml에 대하여 환원제가 300g 미만의 비율인 경우 은 이온이 모두 환원되지 않을 수 있고, 500g/L의 질산은 1600ml에 대하여 환원제가 500g을 초과한 비율로 사용하는 경우 유기물 함량이 증가하는 문제가 있다.The reducing agent may be at least one selected from the group consisting of alkanolamine, hydroquinone, hydrazine and formalin, and among them, hydroquinone may be preferably selected. At this time, the reducing agent may be included in 300 to 500g with respect to 1600ml of 500g / L nitric acid contained in the first reaction solution. 500g / L silver nitrate may reduce all of the silver ions when the reducing agent is less than 300g for 1600ml, and 500g / L silver nitrate may increase the organic content when reducing agent exceeds 500g for 1600ml. there is a problem.
환원제가 상기 범위 미만으로 포함되는 경우 은 이온을 전부 환원시키지 못하는 문제점이 있어, 은 이온을 전부 환원시킬 수 있는 양으로 환원제를 포함하여야 하며, 상기 제2 반응액에 포함되는 환원제의 농도를 조절함으로써 환원속도를 조절할 수 있다.When the reducing agent is included below the above range, there is a problem that all silver ions cannot be reduced. The reducing agent should be included in an amount capable of reducing all of the silver ions, and by adjusting the concentration of the reducing agent included in the second reaction solution. The reduction rate can be adjusted.
예를 들면, 환원제의 농도를 높여 환원속도를 증가시키거나 환원제의 농도를 낮춰 환원속도를 감소시킬 수 있다. 환원제를 포함하는 제2 반응액은 물 등의 용매에 환원제를 첨가하고 교반하여 용해시켜 농도 5% 이하의 수용액 상태로 제조될 수 있다.For example, the reduction rate may be increased by increasing the concentration of the reducing agent or increasing the reduction rate or decreasing the concentration of the reducing agent. The second reaction solution containing the reducing agent may be prepared by adding a reducing agent to a solvent such as water, stirring and dissolving it to form an aqueous solution having a concentration of 5% or less.
본 발명의 일실시예에 따른 석출단계(S22)는 제1 반응액 및 제2 반응액을 반응시켜 은 분말을 얻는 단계로서, 반응액제조단계(S21)에 의해 제조된 제1 반응액 및 제2 반응액을 공중 자유 낙하 방식으로 반응시킬 수 있다. 상기와 같은 공중 자유 낙하 방식으로 반응시켜 은 분말을 얻는 경우 반응액들이 공중자유낙하 하는 동안 적정량의 반응액이 균일하고 지속적으로 반응하여 입자끼리의 응집을 방지하고 분산성을 높일 수 있다.Precipitation step (S22) according to an embodiment of the present invention is a step of obtaining a silver powder by reacting the first reaction solution and the second reaction solution, the first reaction solution and the preparation prepared by the reaction solution production step (S21) 2 The reaction solution can be reacted in a free-falling manner. When a silver powder is obtained by reacting in the free-falling manner as described above, an appropriate amount of the reaction solution reacts uniformly and continuously during the free-fall of the reaction solutions to prevent aggregation between particles and increase dispersibility.
더욱 구체적으로 본 발명에 따른 석출단계(S22)는 도 1에 나타낸 것과 같은 반응액 탱크 및 반응 탱크를 이용하여 공중 자유 낙하 방식으로 은 입자를 석출할 수 있다. 상기 반응액제조단계(S21)에서 상기 제1 반응액 및 제2 반응액은 제1 반응액 제조 탱크 및 제2 반응액 제조 탱크에서 각각 제조될 수 있다.More specifically, in the precipitation step (S22) according to the present invention, silver particles may be precipitated in a free-falling manner using a reaction liquid tank and a reaction tank as shown in FIG. 1. In the reaction liquid production step (S21), the first reaction liquid and the second reaction liquid may be prepared in a first reaction liquid production tank and a second reaction liquid production tank, respectively.
각 탱크에서 제조된 반응액들은 유량 조절이 가능한 공급라인을 통하여 반응 탱크에 각각 공급된다. 반응액들은 반응 탱크에 직경 15Ф인 노즐을 통하여 분사될 경우 3.8L/min 내지 4.5L/min 의 유량으로 공급되는 것이 바람직하다.The reaction liquids prepared in each tank are respectively supplied to the reaction tanks through a supply line capable of adjusting the flow rate. When the reaction liquid is injected through a nozzle having a diameter of 15Ф to the reaction tank, it is preferable to be supplied at a flow rate of 3.8L / min to 4.5L / min.
상기 반응액들은 반응 탱크로 이송된 후 노즐을 통하여 반응 탱크 내부로 공급되어 공중 낙하되면서 제1 반응액과 제2 반응액이 반응한다. 제1 반응액과 제2 반응액이 공급되는 높이(H)는 반응 탱크의 바닥을 기준으로 3m 이상의 높이에서 공중 낙하시킨다. 3m 미만에서 공중 낙하시키는 경우 제조되는 은 분말의 응집이 발생하는 문제가 있다. 바람직하게는 5m 내지 7m 의 높이에서 공중 낙하시키는 것이 더욱 우수한 단분산 입자를 얻을 수 있다.After the reaction liquids are transferred to the reaction tank, the first reaction liquid and the second reaction liquid react while being supplied to the reaction tank through a nozzle and dropping in the air. The height (H) at which the first reaction solution and the second reaction solution are supplied is dropped from the height of 3 m or more relative to the bottom of the reaction tank. There is a problem in that aggregation of silver powder produced when falling in the air below 3 m occurs. Preferably, monodisperse particles having better air-falling at a height of 5 m to 7 m can be obtained.
반응 탱크의 반응 온도는 30 내지 50℃ 로 조절하여 반응시킨다. 반응 온도를 상기 범위로 조절하여 후술할 실험예에 의해 뒷받침되는 것과 같이 석출되는 은 분말의 크기를 제어할 수 있다. 반응온도를 증가시키는 경우 분말 표면의 댄스(dense) 증가, 결정화도 증가 및 코팅제의 코팅 정도에 영향을 미칠 수 있고, 제1 반응액에 첨가되는 유기산 알칼리 금속염의 함량이 동일할 때 반응 온도를 높임으로써 석출되는 은 분말의 입도를 감소시킬 수 있다.The reaction temperature of the reaction tank is adjusted to 30 to 50 ° C to react. The size of the precipitated silver powder can be controlled by controlling the reaction temperature to the above range, as supported by the experimental examples described later. When the reaction temperature is increased, it is possible to increase the density of the powder surface, increase the crystallinity, and affect the coating degree of the coating agent, and increase the reaction temperature when the content of the organic acid alkali metal salt added to the first reaction solution is the same. The particle size of the precipitated silver powder can be reduced.
본 발명에 따른 석출단계(S22)를 통하여 0.3~1.3μm 크기(SEM size)의 단분산된 은 분말을 얻을 수 있으며, 응집이 발생하는 것을 방지할 수 있고, 유기산 알칼리 금속염의 첨가량 및 반응 온도를 조절함으로써 약 0.3 μm 크기의 미세 분말이 제조되더라도 단분산을 유지하며 응집이 발생하는 것을 방지할 수 있다.Through the precipitation step (S22) according to the present invention, 0.3-1.3 μm size (SEM size) monodispersed silver powder can be obtained, aggregation can be prevented from occurring, and the amount of organic acid alkali metal salt added and the reaction temperature. By adjusting, even if a fine powder having a size of about 0.3 μm is produced, it is possible to maintain monodispersity and prevent aggregation from occurring.
본 발명의 일실시예에 따른 정제단계(S3)는 은 염 환원단계(S2)를 통해 반응 탱크 하단에서 얻어지는 은 분말 분산액 내에 분산되어 있는 은 분말을 여과 등을 이용하여 분리하고 세척하는 단계(S31)를 포함한다. 더욱 구체적으로는 은 분말 분산액 중의 은 입자를 침강시킨 후, 분산액의 상등액을 버리고 원심분리기를 이용하여 여과하고, 여재를 순수로 세정한다. 세척을 하는 과정은 분말을 세척한 세척수를 완전히 제거할 수 있다.Purification step (S3) according to an embodiment of the present invention is a step of separating and washing the silver powder dispersed in the silver powder dispersion obtained at the bottom of the reaction tank through filtration through silver salt (S31) (S31) ). More specifically, after the silver particles in the silver powder dispersion are precipitated, the supernatant of the dispersion is discarded, filtered using a centrifuge, and the filter medium is washed with pure water. The washing process can completely remove the washing water from washing the powder.
또한 본 발명의 일실시예에 따른 정제단계(S3)는 세척 후 건조 및 해쇄단계(S32)를 더 포함할 수 있다. 여기서, 함수율은 10% 이하일 수 있으나, 본 발명이 이에 한정되는 것은 아니다.In addition, the purification step (S3) according to an embodiment of the present invention may further include a drying and disintegration step (S32) after washing. Here, the water content may be 10% or less, but the present invention is not limited thereto.
본 발명의 일실시예에 따른 표면처리단계(S4)는 은 분말의 친수 표면을 소수화하는 단계로서, 선택적으로 이루어질 수 있다. 은 분말이 친수 표면을 가지면 장기 보관 시 수분 및 표면 산화에 의하여 특성이 변화할 수 있으며, 도전성 페이스트로 제조할 때 유기 용매와의 상용성 및 최종 인쇄 특성에 큰 영향을 미칠 수 있기 때문이다. 이때, 표면 처리제로는 염 또는 이멀전 형태의 단독 또는 다종의 화합물을 사용할 수 있다.The surface treatment step (S4) according to an embodiment of the present invention is a step of hydrophobicizing the hydrophilic surface of the silver powder, and may be selectively performed. This is because if the silver powder has a hydrophilic surface, properties may change due to moisture and surface oxidation during long-term storage, and may have a great influence on compatibility with organic solvents and final printing properties when prepared with a conductive paste. At this time, as the surface treatment agent, a single or multiple compounds in the form of a salt or emulsion may be used.
일 예로, 여과 후 얻어지는 은 분말에 옥타데실아민을 포함하는 표면처리제를 첨가하여 은 분말에 소수성을 부여할 수 있다. 일 예로, 옥타데실아민을 질산은 100 중량부에 대하여 0.01 내지 0.1 중량부(일 예로, 0.03 중량부)로 포함할 수 있다. 이 후 다시 여과, 세정, 건조, 해쇄 과정을 거쳐 은 분말을 얻을 수 있다. 은 분말을 표면처리할 때 분말의 분산이 잘 되어야 표면처리가 충분히 이루어지고, 함수율이 낮으면 분산 효율이 떨어지기 때문에 일정량의 함수율(예를 들면, 70~85%)을 가지고 표면처리를 하는 것이 좋다.For example, hydrophobicity may be imparted to the silver powder by adding a surface treatment agent containing octadecylamine to the silver powder obtained after filtration. As an example, octadecylamine may contain 0.01 to 0.1 parts by weight (eg, 0.03 parts by weight) with respect to 100 parts by weight of silver nitrate. After that, the silver powder can be obtained again through filtration, washing, drying, and crushing. When the silver powder is surface-treated, the powder must be well dispersed, so that the surface treatment is sufficiently achieved. If the water content is low, the dispersion efficiency decreases, so that the surface treatment is performed with a certain amount of water content (for example, 70 to 85%). good.
본 발명의 일실시예에 따른 후처리단계(S5)는 표면 처리 후 얻어진 은 분말의 건조 및 응집 분말을 분산하기 위한 해쇄 과정 및 조대 분말을 제거하기 위한 분급 공정을 포함할 수 있다. 일 예로, 제트밀(Jetmil) 등을 이용하여 일정한 공기압(예를 들어, 0.4kgf) 및 피딩 속도(예를 들어, 30 내지 60g/min)에서 해쇄 과정을 수행할 수 있으나, 본 발명이 이에 한정되는 것은 아니다.The post-treatment step (S5) according to an embodiment of the present invention may include a crushing process for dispersing the agglomerated powder and drying the silver powder obtained after the surface treatment, and a classification process for removing the coarse powder. For example, the crushing process may be performed at a constant air pressure (for example, 0.4 kgf) and a feeding speed (for example, 30 to 60 g / min) using a jet mill or the like, but the present invention is limited thereto. It does not work.
본 발명의 일실시예에 따른 은 분말의 제조방법에 따라 제조된 은 분말은 SEM size(DSEM) 가 0.3 내지 1.3 μm 이며, PSA size(D50)가 1.0 내지 2.0μm이며, 후술할 실험예에서 측정되는 스팬값(span value)이 1.0 이하이며, 후술할 실험예에서 측정되는 응집도(D50/DSEM)가 1.7 이하 이다.The silver powder prepared according to the method of manufacturing a silver powder according to an embodiment of the present invention has a SEM size (DSEM) of 0.3 to 1.3 μm, a PSA size (D50) of 1.0 to 2.0 μm, and is measured in an experimental example to be described later. The resulting span value is 1.0 or less, and the degree of aggregation (D50 / DSEM) measured in the experimental examples to be described later is 1.7 or less.
본 발명의 제조방법에 따르면 후술할 실시예에서 나타나는 것과 같이 SEM size가 0.3 μm 미만이고 SEM 이미지상 단분산으로 보이는 미세 은 분말까지도 제조가 가능하다.According to the manufacturing method of the present invention, even as shown in the examples to be described below, the SEM size is less than 0.3 μm, and even fine silver powder, which appears to be monodisperse on the SEM image, can be manufactured.
본 발명은 또한 본 발명의 일실시예에 따라 제조되는 은 분말을 포함하는 도전성 페이스트를 제공한다. 더욱 구체적으로 본 발명에 따른 도전성 페이스트는 본 발명에 따라 제조되는 은 분말, 유리 프릿 및 유기 비히클을 포함하여 태양전지 전극 형성에 적합하게 사용될 수 있다.The present invention also provides a conductive paste comprising silver powder prepared according to one embodiment of the present invention. More specifically, the conductive paste according to the present invention can be suitably used for forming a solar cell electrode, including silver powder, glass frit, and organic vehicle prepared according to the present invention.
본 발명에 의한 도전성 페이스트 조성물은 필요에 따라 통상적으로 알려져 있는 첨가제, 예를 들면, 분산제, 가소제, 점도 조정제, 계면활성제, 산화제, 금속 산화물, 금속 유기 화합물 등을 더 포함할 수 있다.The conductive paste composition according to the present invention may further include additives commonly known as necessary, for example, dispersants, plasticizers, viscosity modifiers, surfactants, oxidizing agents, metal oxides, metal organic compounds, and the like.
본 발명은 또한 상기 도전성 페이스트를 기재 위에 도포하고, 건조 및 소성하는 것을 특징으로 하는 태양전지의 전극 형성 방법 및 상기 방법에 의하여 제조된 태양전지 전극을 제공한다. 본 발명의 태양전지 전극 형성방법에서 상기 특성의 은 분말을 포함하는 도전성 페이스트를 사용하는 것을 제외하고, 기재, 인쇄, 건조 및 소성은 통상적으로 태양전지의 제조에 사용되는 방법들이 사용될 수 있음은 물론이다. 일예로 상기 기재는 실리콘 웨이퍼일 수 있다.The present invention also provides a method for forming an electrode of a solar cell, characterized in that the conductive paste is applied onto a substrate, dried and fired, and a solar cell electrode produced by the method. Except for using the conductive paste containing the silver powder of the above characteristics in the method for forming a solar cell electrode of the present invention, substrates, printing, drying and firing can be used, as well as methods commonly used in the manufacture of solar cells. to be. In one example, the substrate may be a silicon wafer.
실시예 및 비교예Examples and comparative examples
(1) 실시예 1(1) Example 1
제1 반응액 탱크에서 상온의 순수 15840g에 500g/L의 질산은 1600ml, 옥살산칼륨 380g 및 암모니아(농도25%) 2560ml를 첨가하고 교반하여 제1 반응액을 조제하였다. 한편 제2 반응액 탱크에서 상온의 순수 20000g에 하이드로퀴논 400g을 첨가하고 교반하여 제2 반응액을 조제하였다.A first reaction solution was prepared by adding and stirring 1600 ml of silver nitrate (500 g / L), 380 g of potassium oxalate, and 2560 ml of ammonia (concentration 25%) in 15840 g of pure water at room temperature in the first reaction solution tank. Meanwhile, in the second reaction liquid tank, 400 g of hydroquinone was added to 20000 g of pure water at room temperature and stirred to prepare a second reaction liquid.
이어서, WILO社 화학펌프를 이용하여 3.8L/min 4.5L/min으로 유량 제어하여 상기 반응액을 각각 반응탱크로 이송한 후 노즐에서 분사(공중낙하 방식)시켜 제1 반응액과 제2 반응액이 공중에서 낙하하면서 반응하여 석출되는 은 분말을 포함한 은 분말 분산액을 반응 탱크 하부에서 회수하였다. 이 때 반응 탱크의 반응온도는 35℃ 이며, 제1 반응액과 제2 반응액의 낙하 높이는 6m 이었다.Subsequently, the flow rate was controlled at 3.8L / min 4.5L / min using a chemical pump from WILO, and the reaction solution was transferred to the reaction tank, respectively, and then sprayed from the nozzle (air-dropping method) to generate the first reaction solution and the second reaction solution. The silver powder dispersion liquid containing silver powder that reacted and precipitated while falling in the air was recovered from the bottom of the reaction tank. At this time, the reaction temperature of the reaction tank was 35 ° C, and the drop heights of the first reaction solution and the second reaction solution were 6 m.
상기 얻어진 은 분말 분산액 중의 은 입자를 침강시킨 후, 분산액의 상등액을 버리고 원심분리기를 이용하여 여과하고, 여재를 순수로 세정한다. 이 후 함수율 10% 미만으로 세척수를 제거하였다. 이 후 표면처리제를 첨가하고 함수율을 70 내지 85%로 조절하고, 건조 및 해쇄 과정을 거쳐 최종 은 분말을 얻었다.After separating the silver particles in the obtained silver powder dispersion, the supernatant of the dispersion is discarded, filtered using a centrifuge, and the filter medium is washed with pure water. Thereafter, the washing water was removed to a water content of less than 10%. After this, a surface treatment agent was added, and the water content was adjusted to 70 to 85%, and the final silver powder was obtained through drying and crushing.
(2) 실시예 2(2) Example 2
제1 반응액과 제2 반응액의 낙하 높이가 3m 인 것을 제외하고는 실시예 1과 동일한 방법으로 은 분말을 얻었다.Silver powder was obtained in the same manner as in Example 1, except that the drop heights of the first reaction solution and the second reaction solution were 3 m.
(3) 실시예 3(3) Example 3
반응 탱크의 반응온도가 50℃인 것을 제외하고는 실시예 1과 동일한 방법으로 은 분말을 얻었다.Silver powder was obtained in the same manner as in Example 1, except that the reaction tank had a reaction temperature of 50 ° C.
(4) 실시예 4(4) Example 4
제1 반응액에 옥살산칼륨을 570g 첨가하고, 반응 탱크의 반응온도가 50℃ 인 것을 제외하고는 실시예 1과 동일한 방법으로 은 분말을 얻었다.570 g of potassium oxalate was added to the first reaction solution, and silver powder was obtained in the same manner as in Example 1, except that the reaction temperature of the reaction tank was 50 ° C.
(5) 비교예 1(5) Comparative Example 1
제1 반응액과 제2 반응액의 낙하 높이가 2m 인 것을 제외하고는 실시예 1과 동일한 방법으로 은 분말을 얻었다.Silver powder was obtained in the same manner as in Example 1, except that the drop heights of the first reaction solution and the second reaction solution were 2 m.
(6) 비교예 2(6) Comparative Example 2
35℃ 반응 온도에서 비이커에 제1 반응액에 제2 반응액을 일괄 첨가(덤핑 방식)하여, 첨가 종료 후부터 10분간 더 교반하여 석출된 은 입자를 포함하는 은 분말 분산액을 얻은 것을 제외하고는 실시예 1과 동일한 방법으로 은 분말을 얻었다. It was carried out except that the second reaction solution was added to the first reaction solution in a beaker at a reaction temperature of 35 ° C (dumping method) and stirred for 10 minutes after the addition was completed to obtain a silver powder dispersion solution containing precipitated silver particles. Silver powder was obtained in the same manner as in Example 1.
구분division 제1 반응액First reaction solution 제2 반응액Second reaction solution 반응방법Reaction method 온도(℃)Temperature (℃) 높이(m)Height (m)
순수(g)Pure (g) 질산은(ml)Silver nitrate (ml) 옥살산칼륨(g)Potassium oxalate (g) 암모니아(ml)Ammonia (ml) 순수(g)Pure (g) 하이드로퀴논(g)Hydroquinone (g)
실시예1Example 1 1548015480 16001600 380380 25602560 2000020000 400400 공중낙하Airdrop 3535 66
실시예2Example 2 1548015480 16001600 380380 25602560 2000020000 400400 공중낙하Airdrop 3535 33
실시예3Example 3 1548015480 16001600 380380 25602560 2000020000 400400 공중낙하Airdrop 5050 66
실시예4Example 4 1548015480 16001600 570570 25602560 2000020000 400400 공중낙하Airdrop 5050 66
비교예1Comparative Example 1 1548015480 16001600 380380 25602560 2000020000 400400 공중낙하Airdrop 3535 22
비교예2Comparative Example 2 1548015480 16001600 380380 25602560 2000020000 400400 공중낙하Airdrop 3535 --
실험예Experimental Example
(1) 은 분말의 SEM size 측정(1) SEM size measurement of silver powder
본 발명의 실시예 및 비교예에 따라 제조된 은 분말을 지올(JEOL)회사제 주사전자현미경을 이용하여, 파우더 100개 각각의 지름 크기를 측정한 후 평균을 내어 SEM size(μm)를 측정하여 하기 표 2에 나타내었다. 또한 실시예 및 비교예에 따라 제조된 은 분말의 SEM 이미지를 도 2 내지 7에 나타내었다.The silver powder prepared according to the Examples and Comparative Examples of the present invention was measured using a scanning electron microscope manufactured by JEOL, and the diameter of each of the 100 powders was measured and averaged to measure the SEM size (μm). It is shown in Table 2 below. In addition, SEM images of silver powders prepared according to Examples and Comparative Examples are shown in FIGS. 2 to 7.
(2) 은 분말의 PSA(Particle size analysis) 측정(2) Particle size analysis (PSA) measurement of silver powder
본 발명의 실시예 및 비교예에 따라 제조된 은 분말 50mg을 에탄올 30ml에 첨가하여 초음파 세척기에 3분간 분산시킨 후 레이저 회절법에 의한 입도분포 측정 장치(S3500, Microtrac사)를 이용하여 PSA size(μm)를 측정하였다. 그 결과를 하기 표 2에 나타내었다.50 mg of silver powder prepared according to Examples and Comparative Examples of the present invention was added to 30 ml of ethanol and dispersed in an ultrasonic washer for 3 minutes, and then a particle size distribution measurement apparatus (S3500, Microtrac) by a laser diffraction method was used to measure PSA size ( μm) was measured. The results are shown in Table 2 below.
(3) 스팬값(Span value) 측정(3) Span value measurement
본 발명의 실시예 및 비교예에 따라 제조된 은 분말에 대하여 측정된 입도분포를 이용하여 아래와 같이 정의된 스팬값(span value)을 계산하였다.Using the particle size distribution measured for the silver powder prepared according to the Examples and Comparative Examples of the present invention, a span value defined as follows was calculated.
Span value=(D90-D10)/D50Span value = (D90-D10) / D50
(여기서 D90, D10 및 D50은 각각 고형분 입도의 누적분포에서 최대값에 대하여 90%, 10% 및 50%에 해당하는 입도를 의미한다.)(Here, D90, D10, and D50 mean particle sizes corresponding to 90%, 10%, and 50% of the maximum value in the cumulative distribution of solid particle size, respectively.)
스팬값이 작으면 입도의 분포가 좁은 것을 의미하여 균일한 크기의 은 분말이 제조된 것으로 볼 수 있다.If the span value is small, it means that the distribution of the particle size is narrow, and it can be seen that a silver powder of uniform size was produced.
(4) 응집도 측정(4) Measurement of cohesion
제조된 은 분말의 응집도를 평가하기 위하여 SEM size(DSEM, μm) 에 대한 PSA size(D50, μm)의 비(D50/DSEM)를 계산하였다. 광산란에 의하여 다분산된 입자를 하나의 입자로 입도 분석이 이루어지는 PSA 입자 크기가 각각의 입자의 지름을 SEM 촬영을 통해 측정한 입자 크기와 차이가 적을수록 분산이 잘 된 것을 의미 한다.In order to evaluate the degree of aggregation of the prepared silver powder, the ratio (D50 / DSEM) of PSA size (D50, μm) to SEM size (DSEM, μm) was calculated. It means that the PSA particle size, in which particle size analysis of particles dispersed by light scattering into one particle, is smaller than the particle size measured by SEM imaging, has better dispersion.
구분division SeMsizeSeMsize PSAPSA Span valueSpan value 응집도Cohesion
D10D10 D50D50 D90D90
실시예1Example 1 1.081.08 0.930.93 1.371.37 2.112.11 0.860.86 1.271.27
실시예2Example 2 1.151.15 0.980.98 1.721.72 2.422.42 0.840.84 1.501.50
실시예3Example 3 1.221.22 0.980.98 1.451.45 2.202.20 0.840.84 1.191.19
실시예4Example 4 0.290.29 0.420.42 0.990.99 1.881.88 1.471.47 3.413.41
비교예1Comparative Example 1 3.813.81 -- -- -- -- --
비교예2Comparative Example 2 1.181.18 1.251.25 2.152.15 3.593.59 1.091.09 1.821.82
상기 표 2의 결과 및 도 2 내지 5에 나타나는 것과 같이 3m 이상의 높이에서 공중 자유 낙하 방식으로 은 입자를 석출하는 경우(실시예 1 내지 3) 낮은 스팬값 및 응집도를 가지고 단분산된 은 분말을 얻을 수 있으며, 반응 온도 증가 및 옥살산칼륨의 투입량을 증가시켜(실시예 4) 300μm 수준의 단분산 분말 수득이 가능하다. 실시예 4의 경우 입자의 크기가 매우 미세하여 표면 에너지가 높으므로 입도분석 측정 시 분말 간의 응집이 발생할 수 있어 스팬값 및 응집도가 다소 높게 측정되었지만 도 5에 나타나는 것과 같이 큰 응집없이 실시예 1 내지 3과 마찬가지로 대량생산이 가능한 것을 확인할 수 있다. 또한 낙하 높이가 3m 미만인 경우(비교예 1) 도 6에 나타나는 것과 같이 분말이 응집되어 PSA size 및 스팬값, 응집도 등을 측정할 수 없었으며, 비커에 덤핑방식으로 은 분말을 석출한 경우(비교예 2) 상기 표 2의 결과 및 도 7에 나타나는 것과 같이 높은 스팬값 및 응집도를 나타내고 응집이 발생한 은 분말을 얻은 것을 확인할 수 있다.As shown in the results of Table 2 and Figs. 2 to 5, when silver particles are precipitated by a free-falling method at a height of 3 m or more (Examples 1 to 3), monodispersed silver powders having low span values and cohesion are obtained It is possible to increase the reaction temperature and increase the input amount of potassium oxalate (Example 4) to obtain a monodisperse powder at a level of 300 μm. In the case of Example 4, since the particle size is very fine and the surface energy is high, aggregation between powders may occur during the particle size analysis measurement, and thus the span value and the degree of aggregation are measured rather high, but as shown in FIG. 5, Examples 1 to As in 3, it can be confirmed that mass production is possible. In addition, when the drop height was less than 3 m (Comparative Example 1), as shown in FIG. 6, the powder was aggregated, and thus PSA size, span value, and degree of aggregation could not be measured, and silver powder was precipitated by dumping in a beaker (Comparison) Example 2) As shown in Table 2 and the results of Table 2, it was confirmed that a silver powder having high span value and degree of aggregation and aggregation occurred was obtained.
전술한 각 실시예에서 예시된 특징, 구조, 효과 등은 실시예들이 속하는 분야의 통상의 지식을 가지는 자에 의하여 다른 실시예들에 대해서도 조합 또는 변형되어 실시 가능하다. 따라서 이러한 조합과 변형에 관계된 내용들은 본 발명의 범위에 포함되는 것으로 해석되어야 할 것이다.The features, structures, effects, and the like exemplified in each of the above-described embodiments may be combined or modified for other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

Claims (9)

  1. 은 이온, 암모니아(NH3) 및 유기산 알칼리 금속염을 포함하는 제1 반응액 및 환원제를 포함하는 제2 반응액을 제조하는 반응액제조단계(S21); 및 A reaction liquid preparation step (S21) of preparing a first reaction liquid containing a silver ion, ammonia (NH3) and an alkali metal salt of an organic acid and a second reaction liquid containing a reducing agent; And
    제1 반응액 및 제2 반응액을 공중 자유 낙하시키면서 반응시켜 은 분말을 얻는 석출단계(S22)를 포함하는 은 염 환원단계(S2);를 포함하는 은 분말의 제조방법.A silver salt reduction step (S2) comprising a precipitation step (S22) to obtain a silver powder by reacting while freely dropping the first reaction solution and the second reaction solution in the air.
  2. 제1항에 있어서,According to claim 1,
    상기 석출단계(S22)는 상기 제1 반응액 및 제2 반응액을 유량 조절이 가능한 공급라인을 통하여 반응 탱크의 특정 높이에서 각각 공급하여 상기 제1 반응액과In the precipitation step (S22), the first reaction solution and the second reaction solution are respectively supplied at a specific height of the reaction tank through a supply line capable of adjusting the flow rate, and the first reaction solution and
    제2 반응액이 자유 낙하하면서 반응하도록 하는 것을 특징으로 하는 은 분말의 제조방법.A method for producing silver powder, wherein the second reaction solution is allowed to react while falling freely.
  3. 제2항에 있어서,According to claim 2,
    상기 제1 반응액과 제2 반응액이 공급되는 높이(H)는 상기 반응 탱크의 바닥으로부터 3m 이상인 것을 특징으로 하는 은 분말의 제조방법.The height (H) of supplying the first reaction solution and the second reaction solution is 3 m or more from the bottom of the reaction tank, the method for producing silver powder.
  4. 제2항에 있어서,According to claim 2,
    상기 반응 탱크의 반응 온도는 30 내지 50℃ 인 것을 특징으로 하는 은 분말의 제조방법.The reaction tank has a reaction temperature of 30 to 50 ℃, characterized in that the production method of the silver powder.
  5. 제4항에 있어서,According to claim 4,
    상기 유기산 알칼리 금속염은 초산(CH3COOH), 포름산(CH2O2), 살산(C2H2O4), 젖산(C3H6O3), 시트르산(C6H8O7), 푸마르산(C4H4O4), 구연산(C6H8O7), 뷰티르산(C4H8O2), 프로피온산(CH3CH2COOH) 및 요산(C5H4N4O3) 으로 구성되는 군에서 선택되는 어느 1종 이상의 유기산과 리튬(Li), 나트륨(Na), 칼륨(K), 칼슘(Ca) 및 마그네슘(Mg)으로 구성되는 군에서 선택되는 어느 1종 이상의 금속이 염을 형성한 것을 포함하는 것을 특징으로 하는 은 분말의 제조방법.The alkali metal salt of the organic acid is acetic acid (CH3COOH), formic acid (CH2O2), salic acid (C2H2O4), lactic acid (C3H6O3), citric acid (C6H8O7), fumaric acid (C4H4O4), citric acid (C6H8O7), butyric acid (C4H8O2), propionic acid (C4H8O2) And one or more organic acids selected from the group consisting of uric acid (C5H4N4O3) and lithium (Li), sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg). Method of producing a silver powder, characterized in that it comprises one or more metal salts.
  6. 제5항에 있어서,The method of claim 5,
    상기 은 이온이 500g/L의 질산은(AgNO3) 수용액으로 첨가될 경우, 상기 유기산 알칼리 금속염은 상기 500g/L의 질산은(AgNO3) 1600ml에 대하여 300 내지 600g 비율로 첨가되는 것을 특징으로 하는 은 분말의 제조방법.When the silver ion is added as an aqueous solution of 500 g / L silver nitrate (AgNO3), the alkali metal salt of the organic acid is prepared at a ratio of 300 to 600 g with respect to 1600 ml of 500 g / L silver nitrate (AgNO3). Way.
  7. 제1항 내지 제6항 중 어느 한 항의 제조방법에 의해 제조되는 은 분말로서, 상기 은 분말은 SEM size(DSEM) 가 0.3 내지 1.3 μm 이며, PSA size(D50)가 0.1 내지 2.0μm 인 것을 특징으로 하는 은 분말의 제조방법.A silver powder produced by the method of any one of claims 1 to 6, wherein the silver powder has a SEM size (DSEM) of 0.3 to 1.3 μm and a PSA size (D50) of 0.1 to 2.0 μm. Method for producing silver powder.
  8. 제7항에 있어서,The method of claim 7,
    상기 은 분말은 하기 식에 의해 계산되는 스팬값(span value)이 1.0 이하인 것을 특징으로 하는 은 분말의 제조방법.The silver powder is a method for producing a silver powder, characterized in that the span value (span value) calculated by the following formula is 1.0 or less.
    Span value=(D90-D10)/D50Span value = (D90-D10) / D50
    (여기서 D90, D10 및 D50은 각각 고형분 입도의 누적분포에서 최대값에 대하여 90%, 10% 및 50%에 해당하는 입도를 의미한다.)(Here, D90, D10, and D50 mean particle sizes corresponding to 90%, 10%, and 50% of the maximum value in the cumulative distribution of solid particle size, respectively.)
  9. 제7항에 있어서,The method of claim 7,
    상기 은 분말은 SEM size(DSEM, μm) 에 대한 PSA size(D50, μm)의 비(D50/DSEM)로 계산되는 응집도가 1.7 이하인 것을 특징으로 하는 은 분말의 제조방법.The silver powder is a method of manufacturing a silver powder, characterized in that the aggregation degree calculated by the ratio (D50 / DSEM) of PSA size (D50, μm) to SEM size (DSEM, μm) is 1.7 or less.
PCT/KR2019/016204 2018-11-23 2019-11-22 Method for preparing monodispersed silver powder WO2020106120A1 (en)

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