KR101075934B1 - Method of recycling metallic grains using eco-friendly process - Google Patents

Abstract

The present invention comprises the steps of preparing a slurry by adding a water-soluble heavy metal complex compound, a water-soluble polymer flocculant and a solvent to the metallic paste waste, and an ultrasonic treatment step of injecting ultrasonic waves into the slurry using an ultrasonic vibrator while stirring the slurry, The heavy metal ions contained in the frit glass of the metallic paste waste by the water-soluble heavy metal complex compound are chelated to form a complex so that the frit glass is agglomerated, and the polymer resin in which the bond between the atoms of the polymer resin is broken by the sonication step is a water-soluble polymer. Reacting with the flocculant to form a mesh structure to form agglomerates, selectively classifying the agglomerated polymer resin and frit glass from the metallic powder using a bubble flotation method or a wet sifting method, and optionally classifying metallic Dragon in powder Method of regenerating the metallic powder using an environmentally friendly process comprising the steps of dissolving and removing the polymer resin remaining finely attached to the surface of the metal powder and washing the solvent-treated metallic powder and performing a drying process to obtain a metallic powder It is about. According to the present invention, since the heavy metal present in the metallic paste waste can be selectively separated and disposed of, it is possible to suppress the problem of environmental pollution by the heavy metal of the metallic paste waste.

 Metallic powder, silver powder, ultrasonic wave, plasma display panel electrode, water soluble heavy metal complex, water soluble polymer flocculant

Description

Method of recycling metallic grains using eco-friendly process

The present invention relates to a method for regenerating metallic powder, and more particularly, to a polymer resin or frit present in a metallic paste waste by combining a physical method using ultrasonic waves and a chemical method using a water soluble heavy metal complex compound and a water soluble polymer flocculant. The present invention relates to a method for regenerating high purity metallic powder which can remove glass and polymer resins in an environmentally friendly manner.

PDP (Plasma Display Panel) electrode is a core part of PDP, and is composed of transparent electrode (ITO), bus electrode of upper glass and address electrode of lower glass. The bus electrode and the address electrode are formed by a photolithography method using a conductive metallic paste.

A conductive metallic paste used in the electrode printing process, which contains conductive metallic powders such as silver (Ag), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), and palladium (Pd). The paste will be used. In particular, silver (Ag) paste containing silver (Ag) powder is mainly used as the conductive metallic paste. Such silver (Ag) paste is composed of silver (Ag) powder (approximately 60 to 80 wt%) having a size of 1 to 3 µm, frit glass (2 to 5 wt%), and acryl to improve adhesion to the glass substrate. It consists of a rate binder (7-10 wt%), a solvent, and an additive (dispersant, antifoamer, leveling agent, etc.).

1 to 5 are cross-sectional views illustrating a method of forming a PDP electrode using a photolithography method.

1 to 5, after applying and printing the silver (Ag) paste 20 to one surface of the glass substrate 10, the silver (Ag) is deposited on the glass substrate 10 when a predetermined drying process is performed. The paste 20 is dried. After selectively shielding and exposing the photomask 30 using the photomask 30, an electrode pattern from which silver (Ag) paste 20 is selectively removed is formed. After the development process, the electrode 40 is formed by passing through the firing process.

As such, the PDP electrode is formed through a series of processes such as printing, drying, exposure, development, and firing. The silver (Ag) paste waste is produced in the developing step during the electrode forming step. Since silver (Ag) powder is expensive in silver (Ag) paste, it needs to be recycled and used rather than discarded or reprocessed as waste.

Such silver (Ag) paste waste contains a dry powder of the silver (Ag) paste from which the solvent has been removed, and sodium carbonate (Na ₂ CO ₃ ) or caustic soda (NaOH) as a release agent.

Silver (Ag) paste waste contains approximately 80 wt% of silver (Ag) powder, and the remaining components are mainly composed of frit glass and a binder which is a polymer resin. The frit glass has PbO, Bi ₂ O _3, and SiO _{2 as} main components, and has a size of about 0.5 to 1 μm. In addition, the binder of the polymer resin component is mostly an acrylate, and is present in a state of being chemically bonded to the surface of the silver (Ag) powder or the frit glass during the drying process.

In the case of reprocessing silver (Ag) powder from silver (Ag) paste waste, the silver (Ag) paste waste is melted at a high temperature to remove the polymer resin component, and the frit glass component is removed by a purification process to remove silver ( After the Ag) ingot is processed, high purity silver (Ag) powder is synthesized. However, since the reprocessing process is performed at a high temperature, it may be a cause of environmental pollution by carbonization of organic matters, and a lot of energy is consumed and it is expensive. In addition, the synthesis of silver (Ag) powder having a micrometer (μm) size from the silver (Ag) ingot is expensive because it requires harmful expensive chemicals and various facilities.

On the other hand, Patent Application No. 10-2003-0080529 proposes a regeneration method of the PDP partition wall polishing powder. Patent application No. 10-2003-0080529 proposes a regeneration method applied to polishing powders such as Al ₂ O ₃ powder, SiC powder, glass powder or stainless steel powder.

However, the need for regenerating metallic powders with high purity has been continuously requested in the industry. In particular, in order to reuse the recycled silver (Ag) powder in a PDP electrode or the like, not only the conductivity and shape should be damaged, but also the high purity of the frit glass and the polymer resin component should be high. The difficulty in regenerating metallic powder was very great.

If the regeneration is not performed properly and a large amount of frit glass remains in the regenerated silver (Ag) powder, the conductivity of the PDP electrode using the regenerated silver (Ag) powder is reduced.

In addition, when the organic component, which is a modified polymer resin component, remains in the regenerated silver (Ag) powder, when the silver (Ag) paste is prepared from the regenerated silver (Ag) powder and used in a PDP electrode, the viscosity in the printing process Increasing, deteriorating printability, etc. can cause serious defects in the PDP electrode.

Meanwhile, a method of regenerating high purity metallic powder by applying a physical method using an ultrasonic wave and an environmentally friendly chemical method to Korean Patent Registration No. 10-0769352 filed and registered by the present applicant in relation to the metallic powder regeneration. Is presented.

The present invention has been made to solve the above problems, and an object of the present invention is to present in the metallic paste waste by combining a physical method using ultrasonic waves and a chemical method using a water-soluble heavy metal complex compound and a water-soluble polymer flocculant. The present invention provides a method for regenerating a metallic powder using an environmentally friendly process that can easily remove the polymer resin or frit glass and the polymer resin.

The present invention relates to a method for regenerating metallic powder from metallic paste waste organically prepared by metallic paste, the method comprising the steps of preparing a slurry by adding a water soluble heavy metal complex compound, a water soluble polymer flocculant and a solvent to the metallic paste waste, When ultrasonic waves are injected into the slurry using an ultrasonic vibrator while stirring, the interatomic bonds of the polymer resin are interrupted to promote chemical reactions, and bubbles in the slurry are violently expanded and burst at the limit due to the high pressure. The ultrasonic wave acts on the metallic paste waste to exfoliate the frit glass or the polymer resin around the metallic powder, and the heavy metal ions contained in the frit glass of the metallic paste waste by the water-soluble heavy metal complex compound. The frit glass is agglomerated to form a complex, and the polymer resin in which the bond between the atoms of the polymer resin is broken by the sonication step reacts with the water-soluble polymer flocculant to form a network structure to form agglomerates; Selectively classifying the polymer resin and frit glass from the metallic powder by using the bubble flotation method or the wet sieve method, and adding the solvent to the selectively sorted metallic powder to adhere to the surface of the metallic powder to remain finely. It provides a method for regenerating the metallic powder using an environmentally friendly process comprising the steps of dissolving and removing the solvent and washing the solvent-treated metallic powder and performing a drying process to obtain a metallic powder.

The metallic powder regeneration method using the eco-friendly process may further include performing an ultrasonic sieve to remove foreign substances mixed in the regeneration process and agglomerated particles generated in the drying process after drying, and the ultrasonic sieve classification is 500 It is desirable to sift the metallic powder while applying ultrasonic waves of a powerful size of 36 kHz to the mesh vibrating body.

The water-soluble heavy metal complex compounds include ethylenediaminetetraacetic acid, sodium hexametaphosphate, nitrile triacetate, hydroxyethylene disphosphonate, polycarboxylate, polyhydroxycarbonate, aminotri (methylenephosphonic acid) and di Preference is given to using at least one substance selected from ethylene-triaminepentaacetate and diethylene-triaminepenta (methylenephosphonic acid).

The water-soluble polymer flocculant is a (co) polymer of acryloyloxyethyltrimethylammonium chloride, a (co) polymer of methacryloyloxyethyltrimethylammonium chloride, air of polyamidine, acrylamide and acrylic acid (salt) It is preferably at least one substance selected from among copolymers, copolymers of acrylamide and acrylamide-2-methylpropanesulfonic acid, polymers of acrylamide, polycarboxylic alkyl ammonium salts, sodium polyacrylates and ammonium polyacrylates. .

The bubble flotation method is a sludge containing polymer resin and frit glass by bubbles and water generated while passing water and air from a lower inlet through a perforated plate having fine pores while gradually stirring a stirrer installed in a reaction tank. It floats together and overflows and is discharged, and the metallic powder has a specific gravity, so that it is not floated by bubbles and remains on the bottom surface of the reactor to selectively classify the metallic powder, and the rotation speed of the stirrer is preferably in the range of 5 rpm to 100 rpm. .

Ultrasonic waves are applied through the ultrasonic horn provided in the reactor, and the frit glass and the polymer resin adhered to the metallic powder surface are peeled off from the metallic powder surface by the ultrasonic waves.

The wet sieve classification method uses a vibrating body of 1450 mesh (8 μm) smaller than the size of the aggregate of the polymer resin and the frit glass, and selectively selects the aggregate of the polymer resin and the frit glass having a larger particle size than the mesh of the sieve. It is desirable to filter.

The solvent is preferably a substance containing at least one selected from an aromatic hydrocarbon system consisting of toluene, xylene or benzene, and an ester system consisting of butyl acetate, propylene glycol monomethyl ether acetate or ethylene glycol diacetate.

The metallic paste is a paste for forming a PDP electrode, the metallic paste waste is waste discharged from a developing process during a PDP electrode forming process, and the metallic powder may be conductive silver (Ag) powder.

The metallic paste is silver (Ag) paste, gold (Au) paste, platinum (Pt) paste, nickel (Ni) paste, copper (Cu) paste or palladium (Pd) paste, and the metallic powder is conductive silver (Ag). ) Powder, gold (Au) powder, platinum (Pt) powder, nickel (Ni) powder, copper (Cu) powder or palladium (Pd) powder.

According to the method of regenerating the metallic powder using the environmentally friendly process according to the present invention, a polymer resin or frit present in the metallic paste waste is a combination of a physical method using ultrasonic wave and a chemical method using a water soluble heavy metal complex compound and a water soluble polymer flocculant. Metallic powder can be regenerated by removing glass and polymer resins in an environmentally friendly manner.

In addition, according to the present invention, since heavy metals present in the metallic paste waste can be selectively separated and disposed of, it is possible to suppress the environmental pollution problem caused by the heavy metal of the metallic paste waste.

In addition, according to the present invention, the silver (Ag) powder can be almost completely recovered from the silver (Ag) paste waste for PDP electrodes, and the expensive silver (Ag) powder can be recovered and used again in the industrial field. Industrial and production costs can be significantly reduced and environmental pollution can be reduced compared to the reprocessing of silver (Ag) paste waste.

Further, according to the present invention, the present invention can also be applied to metallic paste waste containing no frit glass, thereby improving the environmental pollution problem caused by the reprocessing of the metallic paste waste.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen. Like numbers refer to like elements in the figures.

The present invention provides a method for regenerating metallic powder from conductive metallic paste waste. The metallic powder may include silver (Ag) powder, gold (Au) powder, platinum (Pt) powder, nickel (Ni) powder, copper (Cu) powder, palladium (Pd) powder, and the like.

In a preferred embodiment of the present invention, a method of regenerating silver (Ag) powder from silver (Ag) paste waste is described as an example, and the regeneration method presented in the following examples is based on gold (Au) and platinum (Pt) in a metallic paste waste. ), Nickel (Ni), copper (Cu), palladium (Pd) and the like can also be applied to regenerate the metallic powder.

In addition, the metallic paste waste may include not only metallic paste waste containing oxide fine particles such as frit glass, but also metallic paste waste not containing frit glass. Since the PDP electrode is formed on the glass substrate, a metallic paste containing frit glass is used in the printing process of the PDP electrode to improve adhesion to the glass substrate, and the metallic paste containing no frit glass is mainly used in a general printing process. have.

Silver (Ag) paste mainly used in the printing process of the PDP electrode is a silver (Ag) powder, frit glass for enhancing the adhesion to the upper (or lower) glass substrate of the PDP, an acrylate-based binder which is a polymer resin component, It consists of a solvent, an additive, etc. Silver (Ag) paste waste contains a silver (Ag) powder component, a frit flask component and a binder component, and the binder component is chemically bonded to the silver (Ag) powder and frit glass.

The frit glass powder mixed in the silver (Ag) paste waste has a specific gravity of about 1.4 and an average particle diameter of 1 µm or less. Silver (Ag) powder has a specific gravity of about 10, an average particle diameter of about 1 to 3 µm, and is spherical. The specific gravity difference between the frit glass and the silver (Ag) powder shows a large variation, but the average particle diameter does not show the variation. In addition, since the maximum particle size of silver (Ag) powder and frit glass is 5 µm or less, it is not easy to selectively remove the frit glass powder through a general classification process, and the method described in the preferred embodiment of the present invention. It must be removed through the same special process.

Hereinafter, a method of regenerating metallic powder according to a preferred embodiment of the present invention will be described.

The physical and chemical methods using ultrasonic wave, water soluble heavy metal complex and water soluble polymer flocculant can selectively classify silver (Ag) powder from silver (Ag) paste waste.

In order to selectively classify only silver (Ag) powder, a water soluble heavy metal complex and a water soluble polymer flocculant are prepared.

The water soluble heavy metal complex compound forms a complex with lead (Pb), bismuth (Bi), and the like, which are heavy metal ions included in the frit glass of silver (Ag) paste waste to chelate. The water soluble heavy metal complex compound is ethylenediaminetetraacetic acid (EDTA), sodium hexameta phosphate (HMP), nitrile triacetate (NTA), hydroxyethylene disphosphonate (HEDP), poly Carboxylate (PC), polyhydroxycarbonate (PHC), aminotri (methylenephosphonic acid) (ATMOP), diethylene-triaminepentaacetate DTPA), diethylene-triaminepenta (methylenephosphonic acid); and DTPMP.

The ethylenediaminetetraacetic acid (C ₁₀ H ₁₆ N ₂ O ₈ ; hereinafter referred to as 'EDTA') is a colorless crystalline complex compounded with heavy metals through four carboxylates and two amine groups, and almost all heavy metal ions. And water-soluble chelates. Sodium hexametaphosphate (HMP) is a polyphosphate complex that can chelate metal ions such as calcium. Nitrile triacetate (NTA) is an amino-polycarbonate family such as EDTA, which is stable against alkali and has high selectivity to heavy metal ions. Hydroxyethylene disulfonate (HEDP) has a high effect on polyvalent heavy metal ions (calcium, magnesium, iron), and polycarboxylate (PC) has limited efficiency in strong alkalis but heavy metals The binding force is high and polyhydroxycarbonate (PHC) is only effective in limited acids / alkali.

In addition, the water-soluble polymer flocculant has excellent binding properties with the binder, which is a polymer resin component contained in the silver paste waste, and separates the frit glass contained in the silver paste waste from the silver metal powder. It plays a role. The water-soluble polymer flocculant is a (co) polymer of acryloyloxyethyltrimethylammonium chloride, a (co) polymer of methacryloyloxyethyltrimethylammonium chloride, a copolymer of polyamidine, acrylamide and acrylic acid (salt) , Copolymers of acrylamide and acrylamide-2-methylpropanesulfonic acid, polymers of acrylamide, polycarboxylic alkyl ammonium salts, sodium polyacrylates, ammonium polyacrylates, and the like.

A solvent such as the water-soluble heavy metal complex compound, the water-soluble polymer flocculant and water is added to the silver (Ag) paste waste and stirred to form a slurry of about 0.01 to 50 wt%. At this time, while stirring the slurry by using a stirrer, ultrasonic waves are injected into the slurry using an ultrasonic wave vibrator to perform an ultrasonic treatment process. The sonication process removes the frit glass and the resin adhering to the metal powder surface from the metal powder surface. The slurry is formed at about 10 to 100 ° C., and the stirring speed is about 300 to 2000 rpm so that the frit glass powder mixed in the silver (Ag) paste waste is sufficiently dispersed and reacted.

The water-soluble heavy metal complex compound forms a chelate by forming a complex with lead (Pb), bismuth (Bi), and the like, which are heavy metal ions included in the frit glass of the silver paste waste, and the water-soluble polymer coagulant is contained in the silver paste waste. It is excellent in binding property with the binder, which is a polymer resin component, to separate the silver (Ag) metal powder and the polymer resin component, and the frit glass contained in the silver (Ag) paste waste and the silver (Ag) metal powder and The ultrasonic treatment process serves to separate the frit glass and the polymer resin from the silver (Ag) metal powder surface from the silver (Ag) metal powder surface. By the separation process and the ultrasonication process, the polymer resin component or the frit glass and the polymer resin component contained in the silver (Ag) paste waste are separated from the silver (Ag) metal powder. The polymer resin and the frit glass separated from the silver (Ag) metal powder aggregate to form sludge.

The sludge containing the polymer resin and the frit glass separated from the silver (Ag) metal powder are separated and discharged. The separation discharge uses a bubble floating method in which bubbles are generated while the stirrer is rotated, and the sludge containing the polymer resin and the frit glass are floated together with the bubbles by the bubbles to separate and discharge the bubbles. The frit glass powder mixed in the silver paste waste has a specific gravity of about 1.4, the silver (Ag) powder has a specific gravity of about 10, and the polymer resin has a smaller specific gravity than the frit glass powder, so that the polymer resin and the frit glass The specific gravity difference between and silver (Ag) powder shows a big deviation. Using this, the polymer resin and the frit glass may be classified from the silver (Ag) powder by using the bubble floating method to selectively remove the polymer resin and the frit glass powder.

While stirring the slurry using an agitator, ultrasonic waves are injected into the slurry using an ultrasonic wave oscillator, and the frequency of the ultrasonic waves to be injected may be about 28 to 40 kHz. It is preferable to apply an ultrasonic wave for 30 minutes-about 2 hours. In general, ultrasound refers to sound waves having a frequency of 20kHz or more. When ultrasonic waves are irradiated to the slurry, gas molecules (bubbles) in the slurry expand violently, and the gas molecules have a very high pressure and burst at their limit points. When the bubble bursts, the shock wave acts on the silver (Ag) paste waste to exfoliate the surrounding frit glass or polymer resin from the silver (Ag) metal powder.

In addition, when the ultrasonic wave is injected into the slurry, the binder, which is a polymer resin component such as an acrylate type, breaks the bond between atoms, thus promoting a chemical reaction between the binder and the water-soluble polymer flocculant. As a result, the binder surrounding the silver (Ag) may be accelerated from the silver (Ag) metal powder. In addition, by promoting the reaction between the water-soluble heavy metal complex compound and the heavy metal contained in the frit glass, the heavy metal is chelated by the heavy metal complex compound and the frit glass is aggregated.

As a result of the physical and ultrasonic methods, the binder surrounding the silver (Ag) metal powder is broken off from the silver (Ag) metal powder by breaking the bond between atoms, and the binder reacts with the water-soluble polymer flocculant to form a net. By forming a structure, aggregates are formed, and heavy metals contained in the frit glass are chelated to a water-soluble heavy metal complex compound to form a complex, whereby the frit glass aggregates.

The agglomerated polymer resin and frit glass can be selectively classified from silver (Ag) metal powder using the bubble floating method described below. Since the specific gravity of the silver (Ag) powder is relatively higher than that of the frit glass and the polymer resin, the waste in which the binder is bonded to silver (Ag) is heavier than the waste in which the binder is bonded to the frit glass. The specific gravity of the silver (Ag) powder may be classified using the bubble floating method using the property that the specific gravity of the silver (Ag) powder is relatively larger than that of the frit glass and the polymer resin.

FIG. 6 shows a reactor 100 in which the polymer resin and the frit glass are floated and filtered while generating bubbles by the bubble floating method.

In the reaction tank 100, a stirrer 120 including a motor M and a rotary blade 110 rotated by the motor M is installed, and the rotary blade 110 of the stirrer 120 is provided. Rotate at 5 rpm to 100 rpm. In addition, an ultrasonic horn H is installed in the reactor 100, and the ultrasonic horn H is connected to an ultrasonic wave generator (not shown). The ultrasonic waves oscillated by the ultrasonic generator are applied to the ultrasonic horn H to generate ultrasonic waves in the reaction tank. The ultrasonic waves applied to the ultrasonic horn H serve to separate the frit glass and the polymer resin from the silver metal powder surface in the reaction tank 100 from the metal powder surface. In addition, the lower surface of the reaction tank 100 is provided with a perforated plate 130 having a plurality of fine pores, the function of generating bubbles when passing through the perforated plate 130 by injecting water and air from the lower perforated plate 130 Do it.

The sludge and silver (Ag) metal powder containing the polymer resin and the frit glass are not precipitated by the rotation of the stirrer 40, thereby preventing the pores of the perforated plate 130 from being blocked. In addition, while the water and air is injected from the injection hole in the lower portion of the perforated plate 130 through the perforated plate 130, bubbles are generated and the sludge floats together with the bubbles.

On the other hand, the silver (Ag) metal powder has a large specific gravity and cannot be floated by bubbles and remains on the bottom surface of the reactor 100. Bubbles generated through the stirring process in the reaction tank 100 cling to the sludge surface including the polymer resin and the frit glass to increase the buoyancy so that the sludge rises quickly above the water surface. The sludge containing the polymer resin and the frit glass that floated to the upper portion of the reactor 100 is discharged to the sludge recovery container while overflowing. At this time, if the rotational speed of the stirrer 40 is too large, since the vortex occurs large, silver (Ag) metal powder may also float along the wall surface of the reaction tank 100 by the vortex, causing overflow, and the stirrer 40 If the rotational speed of the aggregator is too small, the sludge containing the polymer resin and the frit glass does not occur, and it is mixed with the silver metal powder so that sufficient separation is difficult, so that the rotational speed of the stirrer 40 is about 5 rpm to about 100 rpm. Do.

In the above-described example, the method of selectively removing the sludge containing the polymer resin and the frit glass using the bubble floating method has been described. However, the wet body classification method described below may be used instead of the bubble floating method.

The sieve used for the wet sifting is used having a 1450 mesh (sieve pore size of about 8 mu m). Since the aggregated polymer resin or frit glass has a particle size of about 10 μm or more, and the silver (Ag) powder has a particle size of about 1 to 3 μm, the aggregated polymer resin or frit glass is selectively removed by wet classification. can do.

Specifically, the wet vibrating classification process is performed to sift the slurry treated with the water-soluble heavy metal complex compound and the water-soluble polymer flocculant in a 1450 mesh sieve to separate silver (Ag) metal powder from the slurry. Aggregated polymer resin or frit glass having a particle size larger than the size of the 1450 mesh does not pass through the sieve of 1450 mesh and silver (Ag) metal powder having a particle size smaller than the size of the 1450 mesh passes through the sieve, whereby Sludges containing polymeric resin and frit glass are selectively classified from silver (Ag) metal powder.

A solvent is added to the silver (Ag) metal powder selectively classified by the bubble flotation method or the wet sieve classification method to adhere to the surface of the silver (Ag) metal powder to dissolve and remove fine polymer resin remaining. As the solvent, aromatic hydrocarbons such as toluene, xylene, benzene, or esters such as butyl acetate, propylene glycol monomethyl ether acetate, and ethylene glycol diacetate may be used. The polymer resin of the silver (Ag) paste waste is generally photosensitive acrylate-based, and the solvent may serve to dissolve and remove the polymer resin such as the acrylate-based. The solvent may be added to the solvent in order to promote the interface separation between the silver (Ag) metal powder and the polymer resin.

Examples of the surfactant include ethylene glycol monostearate, propylene glycol dioleate, sorbitan monolaurate, sorbitan monolaurate, sorbitan monopalmitinate, sorbitan monooleate, sorbitan sorbitan sulphate, trisorbate sorbitan, Sugar fatty acid esters, undecylenic acid diethanolamide, lauric acid diethanolamide, palm oil fatty acid diethanolamide, monolauric acid polyethylene glycol, monostearic acid polyethylene glycol, monooleic acid polyethylene glycol, lactic acid mylate, lactic acid cetrate, polyoxy Ethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, olioxyethylene stearic acid amide, polyoxyethylene glycerin mono Stearate, poly Cyethylene sorbitol monolaurate, polyoxyethylene (20) soribitan monolaurate, polyoxyethylene (20) soribitan monopalmitate, polyoxyethylene (6) sorbitan monostearate, polyoxyethylene (20) Non-monostearate, polyoxyethylene sorbitol hexastearate, polyoxyethylene (20) sorbitan monooleate, polyoxyethylene (20) sorbitan trioleate and polyoxyethylene sorbitan tetraoleate One or more types can be used.

Solvent treated silver (Ag) metal powder is washed with water. The washed silver (Ag) metal powder cake is dried to obtain silver (Ag) metal powder. The drying may be carried out through a general drying process such as hot air drying, vacuum drying, spray drying. The drying is preferably performed for 10 minutes to 48 hours at a temperature of room temperature to 120 ℃.

After the drying, it is also possible to obtain silver (Ag) metal powder from which foreign matters mixed in the regeneration process and aggregated particles generated during the drying process are removed by using the ultrasonic sieve classification method. Ultrasonic sifting is a method of sieving by pulverizing the aggregated silver (Ag) metal powder generated during the drying process by applying a powerful 36kHz ultrasonic wave to a sieve having 500 mesh. Aggregated silver (Ag) metal powder and foreign matter having a particle size larger than the size of 500 mesh does not pass through the sieve of 500 mesh, silver (Ag) metal powder having a particle size smaller than the size of 500 mesh passes through the sieve. . Since silver is continuously applied to the silver (Ag) metal powder that does not pass through the 500 mesh sieve, the silver (Ag) metal powder agglomerated by the applied ultrasonic waves is cracked, and the silver having a particle size smaller than the size of 500 mesh ( Ag) is finely divided into metal particles to pass through a sieve. By the ultrasonic sieve method, not only the finely divided silver (Ag) metal powder can be obtained, but also a short circuit caused by agglomerated particles and foreign substances can be prevented when the silver (Ag) paste is produced using the regenerated silver metal powder. .

In the following, the invention is described in more detail with reference to the following examples, which do not limit the invention.

≪ Example 1 >

The water-soluble heavy metal complex compound, the water-soluble polymer flocculant, and water were added to the silver (Ag) paste waste, and stirred to form a slurry. Specifically, 300 g of the water-soluble heavy metal complex compound, 300 g of the water-soluble polymer flocculant, 3 kg of silver (Ag) paste waste, and 3 L of water were added to a 5 L beaker and mixed, followed by stirring with a stirrer to form a slurry. Ethylenediaminetetraacetic acid (EDTA) was used as the water-soluble heavy metal complex compound, and a copolymer of acryloyloxyethyltrimethylammonium chloride was used as the water-soluble polymer coagulant.

While stirring the slurry using an stirrer, an ultrasonic treatment was performed by injecting 28 μs of ultrasonic waves into the slurry for 1 hour using an ultrasonic wave vibrator. The stirring speed of the stirrer was 800rpm, the stirring temperature was 70 ℃, the stirring time was 2 hours.

The agglomerated polymer resin and frit glass were selectively classified from silver (Ag) metal powder using the bubble floating method. The classifier for the bubble floating method is provided with a reaction tank 100, the reaction tank 100 in the stirrer 120 composed of a motor (M) and the rotary blades 110 rotated by the motor (M). ) Is installed, an ultrasonic horn (H) is installed in the reactor 100, and the ultrasonic horn 50 is connected to an ultrasonic wave generator (not shown). On the lower surface of the reactor 100, a perforated plate 130 having a plurality of holes is installed, and water and air are injected from the perforated plate 130 to generate bubbles when passing through the perforated plate 130.

During the classification process for the bubble injury, an ultrasonic wave of 28 Hz was applied to the ultrasonic horn. Rotary blade 30 of the stirrer 120 was rotated at 5rpm.

The sludge containing the polymer resin and the frit glass is floated together with the bubbles by the bubbles and water generated while passing the perforated plate 130 having fine pores by injecting water and air from the lower inlet while slowly stirring the stirrer 120. Flowed and discharged, the silver (Ag) metal powder is large, the specific gravity is not floating by the bubbles remained on the bottom surface of the reaction tank (100).

The sludge containing the polymer resin and the frit glass that floated to the upper portion of the reactor 100 was discharged to the sludge recovery container while overflowing.

Solvent was added to the silver (Ag) metal powder selectively classified by the bubble flotation method, and the polymer resin attached to the silver (Ag) metal powder surface was dissolved and removed. The solvent used toluene.

Solvent treated silver (Ag) metal powder was washed with water, followed by a drying process. In the drying process, a hot air dryer was used, and in order to avoid aggregation of silver (Ag) metal powder, drying was performed at 90 ° C. for 24 hours to obtain a high purity silver (Ag) powder.

After drying, ultrasonic body classification was performed to remove foreign matter and aggregated particles contained in the aggregated silver (Ag) metal powder to obtain a silver (Ag) metal powder. Ultrasonic sifting was sieved by pulverizing the aggregated silver (Ag) metal powder generated during the drying process while applying a powerful 36kHz ultrasonic wave to a 500mesh sieve.

<Example 2>

The water-soluble heavy metal complex compound, the water-soluble polymer flocculant, and water were added to the silver (Ag) paste waste, and stirred to form a slurry. Specifically, 200 g of the water-soluble heavy metal complex compound, 200 g of the water-soluble polymer flocculant, 5 kg of silver (Ag) paste waste, and 15 L of water were added to a 30 L sus- tain vessel, followed by mixing with a stirrer to form a slurry. Nitrile triacetate (NTA) was used as the water soluble heavy metal complex, and ammonium polyacrylate was used as the water soluble polymer coagulant.

While stirring the slurry using an stirrer, an ultrasonic treatment was performed by injecting 28 μs of ultrasonic waves into the slurry for 1 hour using an ultrasonic wave vibrator. The stirring speed of the stirrer was 800rpm, the stirring temperature was 70 ℃, the stirring time was 2 hours.

The agglomerated polymer resin and frit glass were selectively classified from silver (Ag) metal powder using a wet sifting method. The sieve used in the wet sieve was used having a 1450 mesh (sieve pore size of about 8 μm). Since the aggregated polymer resin or frit glass has a particle size of about 10 μm or more, and the silver (Ag) powder has a particle size of about 1 to 3 μm, the aggregated polymer resin or frit glass is selectively removed by wet classification. It was.

A solvent was added to the silver (Ag) metal powder selectively classified by the wet sieve classification method to adhere to the surface of the silver (Ag) metal powder to dissolve and remove fine polymer resin remaining. The solvent used toluene.

The solvent-treated silver (Ag) metal powder was washed with water, followed by a drying step after washing. At this time, the temperature of the dryer was 70 ℃, vibration degree 2 × 10 ^-2 Torr, was dried for 24 hours to obtain a high purity silver (Ag) metal powder.

After drying, ultrasonic body classification was performed to remove foreign matter and aggregated particles contained in the aggregated silver (Ag) metal powder to obtain a silver (Ag) metal powder. Ultrasonic sifting was sieved by pulverizing the aggregated silver (Ag) metal powder generated during the drying process while applying a powerful 36kHz ultrasonic wave to a sieve having 500 mesh.

7 is a Scanning Electron Microscope (SEM) photograph showing silver (Ag) powder before being used in the printing process of the PDP electrode, and FIG. 8 is the silver paste waste after being used in the printing process of the PDP electrode. 9 is a scanning electron microscope (SEM) photograph showing, and FIG. 9 is a scanning electron microscope (SEM) photograph showing silver (Ag) powder regenerated according to Example 1 of the silver (Ag) paste waste shown in FIG. 8, and FIG. 10. Is a scanning electron microscope (SEM) photograph showing the silver (Ag) powder regenerated according to Example 2 of the silver (Ag) paste waste shown in FIG.

Table 1 below shows silver (Ag) paste waste, silver (Ag) powder (regular) before being used in the printing process of the PDP electrode, silver (Ag) powder regenerated according to Example 1 and regenerated according to Example 2 Metals detected in one silver (Ag) powder are shown.

division Silver (Ag) Paste
Waste (% by weight) Regular article (%) Example 1 (% by weight) Example 2 (% by weight) Ag 96.9 99.8540  99.8  99.8 Pb 0.406 ND ND ND Si 0.309 0.0137  0.0270  0.0384 Bi 1.47 ND ND ND Na ND ND ND ND Al 0.287 0.0114  0.0203  0.0163 Zn 0.0733 ND ND ND Pt ND ND ND ND Cr ND ND ND ND Ni ND ND 0.0282 0.0213 Fe 0.0509 0.0310 0.0761 0.0465 Ca ND 0.0642  ND  ND S ND 0.0257  ND  0.0039 Mg 0.0349 ND ND 0.0188 P 0.0262 ND 0.0051 ND Mn 0.0419 ND ND ND Co 0.0330 ND ND ND Cu 0.0429 ND 0.0236 0.0160

Referring to Table 1 and FIGS. 7 to 10, the silver (Ag) powder regenerated from the silver (Ag) paste waste according to Examples 1 and 2 includes silver (Ag) powder before being used in the printing process of the PDP electrode. It can be confirmed that the regeneration was completed by removing impurities to a degree similar to that of (regular product).

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

1 to 5 are cross-sectional views illustrating a method of forming a PDP electrode using a photolithography method.

6 is a view schematically showing a classification apparatus for the bubble floating method.

7 is a scanning electron microscope (SEM) photograph showing silver (Ag) powder before being used in the printing process of the PDP electrode.

8 is a scanning electron microscope (SEM) photograph showing the silver (Ag) paste waste after being used in the printing process of the PDP electrode.

9 is a scanning electron microscope (SEM) photograph showing the silver (Ag) powder regenerated according to Example 1 of the silver (Ag) paste waste shown in FIG.

FIG. 10 is a scanning electron microscope (SEM) photograph showing the silver (Ag) powder regenerated according to Example 2 of the silver (Ag) paste waste shown in FIG. 8.

<Explanation of symbols for the main parts of the drawings>

10: glass substrate 20: silver (Ag) paste

30: photo mask 40: PDP electrode

100: reactor 110: rotary wing

120: stirrer 130: perforated plate

M: Motor H: Ultrasonic Horn

Claims (10)

In the method of regenerating metallic powder from metallic paste waste which is organically formed by metallic paste, Preparing a slurry by adding a water soluble heavy metal complex compound, a water soluble polymer flocculant and a solvent to the metallic paste waste; By injecting ultrasonic waves into the slurry using an ultrasonic vibrator while stirring the slurry, the interatomic bonds of the polymer resin are interrupted to promote chemical reactions, and the bubbles in the slurry are violently expanded to burst at the limit due to the high pressure. A sonication step in which the shock wave when detonated acts on the metallic paste waste to exfoliate the frit glass or the polymer resin around the metallic powder; The heavy metal ions contained in the frit glass of the metallic paste waste by the water-soluble heavy metal complex compound are chelated to form a complex so that the frit glass is agglomerated, and the polymer resin in which the bond between the atoms of the polymer resin is broken by the sonication step is water-soluble. Reacting with the polymer coagulant to form a network structure to form an aggregate; Selectively classifying the aggregated polymer resin and the frit glass from the metallic powder using a bubble flotation method; Adding a solvent to the selectively classified metallic powder to dissolve and remove the finely polymer polymer remaining on the metallic powder surface; And Washing the solvent-treated metallic powder, and performing a drying process to obtain the metallic powder, The bubble floating method, The sludge containing the polymer resin and the frit glass floats and overflows with the bubbles and water generated by passing water and air from the lower inlet and passing through the perforated plate having a plurality of pores while gradually stirring the stirrer installed in the reactor. It is discharged, the metal powder has a high specific gravity and can not be lifted by the bubbles and remain on the bottom of the reactor to selectively classify the metal powder, Rotational speed of the stirrer is a metallic powder recycling method using an environmentally friendly process, characterized in that the range of 5rpm ~ 100pm. In the method of regenerating metallic powder from metallic paste waste which is organically formed by metallic paste, Preparing a slurry by adding a water soluble heavy metal complex compound, a water soluble polymer flocculant and a solvent to the metallic paste waste; By injecting ultrasonic waves into the slurry using an ultrasonic vibrator while stirring the slurry, the interatomic bonds of the polymer resin are interrupted to promote chemical reactions, and the bubbles in the slurry are violently expanded to burst at the limit due to the high pressure. A sonication step in which the shock wave when detonated acts on the metallic paste waste to exfoliate the frit glass or the polymer resin around the metallic powder; The heavy metal ions contained in the frit glass of the metallic paste waste by the water-soluble heavy metal complex compound are chelated to form a complex so that the frit glass is agglomerated, and the polymer resin in which the bond between the atoms of the polymer resin is broken by the sonication step is water-soluble. Reacting with the polymer coagulant to form a network structure to form an aggregate; Selectively classifying the aggregated polymer resin and the frit glass from the metallic powder using a bubble flotation method or a wet sifting method; Adding a solvent to the selectively classified metallic powder to dissolve and remove the finely polymer polymer remaining on the metallic powder surface; And Washing the solvent-treated metallic powder, and performing a drying process to obtain the metallic powder, And performing ultrasonic sifting to remove foreign matters mixed in the regeneration process and aggregated particles generated in the drying process after drying. The ultrasonic body classification is a metal powder regeneration method using an environmentally friendly process, characterized in that the sieve sifted metallic powder while applying a powerful 36kHz ultrasonic wave to the 500 mesh vibrating body. In the method of regenerating metallic powder from metallic paste waste which is organically formed by metallic paste, Preparing a slurry by adding a water soluble heavy metal complex compound, a water soluble polymer flocculant and a solvent to the metallic paste waste; By injecting ultrasonic waves into the slurry using an ultrasonic vibrator while stirring the slurry, the interatomic bonds of the polymer resin are interrupted to promote chemical reactions, and the bubbles in the slurry are violently expanded to burst at the limit due to the high pressure. A sonication step in which the shock wave when detonated acts on the metallic paste waste to exfoliate the frit glass or the polymer resin around the metallic powder; The heavy metal ions contained in the frit glass of the metallic paste waste by the water-soluble heavy metal complex compound are chelated to form a complex so that the frit glass is agglomerated, and the polymer resin in which the bond between the atoms of the polymer resin is broken by the sonication step is water-soluble. Reacting with the polymer coagulant to form a network structure to form an aggregate; Selectively classifying the aggregated polymer resin and the frit glass from the metallic powder using a bubble flotation method or a wet sifting method; Adding a solvent to the selectively classified metallic powder to dissolve and remove the finely polymer polymer remaining on the metallic powder surface; And Washing the solvent-treated metallic powder, and performing a drying process to obtain the metallic powder, The water-soluble heavy metal complex compound, Ethylenediaminetetraacetic acid, sodium hexametaphosphate, nitrile triacetate, hydroxyethylene disphosphonate, polycarboxylate, polyhydroxycarbonate, aminotri (methylenephosphonic acid), diethylene-triaminepentaacetate And diethylene-triamine penta (methylene phosphonic acid) using at least one material selected from the group. In the method of regenerating metallic powder from metallic paste waste which is organically formed by metallic paste, Preparing a slurry by adding a water soluble heavy metal complex compound, a water soluble polymer flocculant and a solvent to the metallic paste waste; By injecting ultrasonic waves into the slurry using an ultrasonic vibrator while stirring the slurry, the interatomic bonds of the polymer resin are interrupted to promote chemical reactions, and the bubbles in the slurry are violently expanded to burst at the limit due to the high pressure. A sonication step in which the shock wave when detonated acts on the metallic paste waste to exfoliate the frit glass or the polymer resin around the metallic powder; The heavy metal ions contained in the frit glass of the metallic paste waste by the water-soluble heavy metal complex compound are chelated to form a complex so that the frit glass is agglomerated, and the polymer resin in which the bond between the atoms of the polymer resin is broken by the sonication step is water-soluble. Reacting with the polymer coagulant to form a network structure to form an aggregate; Selectively classifying the aggregated polymer resin and the frit glass from the metallic powder using a bubble flotation method or a wet sifting method; Adding a solvent to the selectively classified metallic powder to dissolve and remove the finely polymer polymer remaining on the metallic powder surface; And Washing the solvent-treated metallic powder, and performing a drying process to obtain the metallic powder, The water-soluble polymer flocculant, (Co) polymer of acryloyloxyethyltrimethylammonium chloride, (co) polymer of methacryloyloxyethyltrimethylammonium chloride, polyamidine, copolymer of acrylamide and acrylic acid (salt), acrylamide and acryl Eco-friendly process characterized by using at least one material selected from copolymers of amide-2-methylpropanesulfonic acid, polymers of acrylamide, polycarboxylic alkyl ammonium salts, sodium polyacrylate and ammonium polyacrylate Metal powder recycling method using. delete The method of claim 1, wherein ultrasonic waves are applied through an ultrasonic horn installed in the reaction tank, and the frit glass and the polymer resin adhered to the metallic powder surface are separated from the metallic powder surface by the ultrasonic waves. Powder regeneration method. In the method of regenerating metallic powder from metallic paste waste which is organically formed by metallic paste, Preparing a slurry by adding a water soluble heavy metal complex compound, a water soluble polymer flocculant and a solvent to the metallic paste waste; By injecting ultrasonic waves into the slurry using an ultrasonic vibrator while stirring the slurry, the interatomic bonds of the polymer resin are interrupted to promote chemical reactions, and the bubbles in the slurry are violently expanded to burst at the limit due to the high pressure. A sonication step in which the shock wave when detonated acts on the metallic paste waste to exfoliate the frit glass or the polymer resin around the metallic powder; The heavy metal ions contained in the frit glass of the metallic paste waste by the water-soluble heavy metal complex compound are chelated to form a complex so that the frit glass is agglomerated, and the polymer resin in which the bond between the atoms of the polymer resin is broken by the sonication step is water-soluble. Reacting with the polymer coagulant to form a network structure to form an aggregate; Selectively classifying the aggregated polymer resin and the frit glass from the metallic powder using a wet sifting method; Adding a solvent to the selectively classified metallic powder to dissolve and remove the finely polymer polymer remaining on the metallic powder surface; And Washing the solvent-treated metallic powder, and performing a drying process to obtain the metallic powder, The wet body classification method, Metallic material using an environmentally friendly process characterized in that a sieve of 1450 mesh larger than the size of the aggregate of the polymer resin and the frit glass is used, and the polymer resin and the frit glass aggregate having the particle size larger than the mesh of the sieve are selectively filtered out. Powder regeneration method. The method of claim 1, wherein the solvent, Using an aromatic process comprising at least one selected from an aromatic hydrocarbon system consisting of toluene, xylene or benzene, and an ester system consisting of butyl acetate, propylene glycol monomethyl ether acetate or ethylene glycol diacetate. Metallic powder regeneration method. The method of claim 1, wherein the metallic paste is a PDP electrode forming paste, the metallic paste waste is a waste discharged from the development process during the PDP electrode forming process, the metallic powder is a conductive silver (Ag) powder. Metal powder recycling method using an environmentally friendly process. The metal paste of claim 1, wherein the metallic paste is a silver paste, a gold paste, a platinum paste, a nickel paste, a copper paste, or a palladium paste. Metallic powder regeneration using an environmentally friendly process, characterized in that the silver conductive silver (Ag) powder, gold (Au) powder, platinum (Pt) powder, nickel (Ni) powder, copper (Cu) powder or palladium (Pd) powder Way.

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