Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
  • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
  • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
  • B22F1/054—Nanosized particles
  • B22F1/0545—Dispersions or suspensions of nanosized particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
  • B22F1/102—Metallic powder coated with organic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
  • B82B3/00—Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/62—Metallic pigments or fillers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2304/00—Physical aspects of the powder
  • B22F2304/05—Submicron size particles
  • B22F2304/054—Particle size between 1 and 100 nm
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/84—Manufacture, treatment, or detection of nanostructure
  • Y10S977/895—Manufacture, treatment, or detection of nanostructure having step or means utilizing chemical property
  • Y10S977/896—Chemical synthesis, e.g. chemical bonding or breaking

Definitions

• the present invention relates to the technical field of nanotechnology.
• the present invention relates to a process for the preparation of metal nanoparticles and the metal nanoparticles obtainable in this way and to their use. Furthermore, the present invention relates to the invention containing metal nanoparticles dispersions. Finally, the present invention relates to coating materials and coating systems, glasses and glassy coatings, inks and printing inks, plastics, foams, cosmetics, cleaning agents and impregnating agents, adhesives, sealants and catalyst systems which contain the metal nanoparticles according to the invention or the dispersions of the invention.
• the preparation of such metal nanoparticles can be carried out via the reduction of a metal salt (eg a silver salt) in a two-phase reaction with sodium borohydride as the reducing agent.
• a metal salt eg a silver salt
• the metal salt is first using z. B. of tetraoctylammonium bromide from the aqueous into the organic phase (eg., Toluene or chloroform) and then reduced by means of sodium borohydride.
• the organic phase eg., Toluene or chloroform
• a stabilizer such.
• dodecanethiol almost monodisperse metal nanoparticles can be synthesized and dispersed in various media due to the surface modification. For use in water, it requires in most cases a phase transfer catalyst such.
• Another alternative is the so-called polyol method (see, for example, US 2006/0090599 A1), according to which a reduction of a metal ion source in or by a polyol at elevated temperatures above 100 0 C, in general above 150 ° C, is performed.
• the polyol also serves as a stabilizer and solvent, ie no additional solvent is required.
• a disadvantage of this method is that the resulting metal nanoparticles as such are not or at most very expensive isolatable. In addition, the resulting metal nanoparticles are not or only with difficulty modifiable for non-polar systems.
• Another disadvantage is the use of relatively expensive starting chemicals and the relatively high process temperatures.
• metal nanoparticles in particular gold nanoparticles
• sonolysis is possible, but generally only on an experimental scale.
• This method is based on an energy input by means of ultrasound.
• An aqueous solution of, for example, HAuCl 4 is reacted with glucose, the actual reducing agent being hydroxyl radicals and sugar pyrolysis radicals which form at the interface region between the collapsing cavities of the glucose and the water.
• So-called nanoribbons with widths of 30 to 50 nm and lengths of a few micrometers are created, these bands are flexible and more than 90 ° flexible.
• JP 2003-147418 A relates to the preparation of metal nanoparticles (for example Au or Pd) by reduction in micelles in aqueous media, the micelles being produced from amphiphilic block copolymers.
• metal nanoparticles for example Au or Pd
• the necessary for Micellbil- formation block copolymers are relatively expensive to produce and also act as a reducing agent.
• US 2006/0266156 A1 relates to metal particles which comprise on their surface two mutually different wetting or dispersing agents with different evaporation temperatures, and a process for their preparation.
• US 2006/0266157 A1 describes the preparation of metal nanoparticles by reduction of aqueous metal salt solutions in the presence of a wetting agent, such. Cetyltrimethylammonium bromide (CTAB).
• CTCAB Cetyltrimethylammonium bromide
• the particles obtained in this way can be dispersed with the addition of wetting or dispersing agents and combined for bindings with binders.
• the preparation is not carried out in a purely aqueous medium.
• the reaction is a combination of citrate method on the one hand and two-phase reaction on the other hand.
• the coverage of the particle surfaces, for example with CTAB as wetting agent provides readily dispersible particles in nonpolar media, but CTAB is relatively expensive and must be used in significant excess.
• the addition of further dispersants is required in order to achieve a certain coating compatibility at all.
• WO 2006/053225 A2 relates to the preparation of metal nanoparticles / protein complexes.
• the preparation is carried out in an aqueous medium below
• WO 2006/072959 A1 relates to water-based dispersions of metal nanoparticles and to a process for their preparation in the presence of a reducing water-soluble polymer which allows metal formation to form metal cores.
• US 2007/0034052 A1 and US 2006/0159603 A1 describe the preparation of metal nanoparticles, in particular silver nanoparticles, by reduction of metal ions by means of polyols.
• No. 6,992,039 B2 relates to the preparation of supported monodisperse noble metal nanoparticles on oxidic substrates.
• the in situ preparation of noble metal nanoparticles on porous ceramics is described.
• the reduction of the noble metal salts occurs in the presence of metal alkoxides and wetting agents, followed by a subsequent step of calcining.
• US 2003/0199653 A1 relates to the preparation of metal nanoparticles in an aqueous medium in the presence of sulfur-containing copolymers by reduction with NaBH 4 . Due to the use of sulfur-containing stabilizers, the particles obtained in this way can not be used for catalysis. Furthermore, the synthesis is relatively expensive. Also, the redispersibility of the particles thus obtained is not very large.
• WO 02/087749 A1 CA 2 445 877 A1 and US 2004/0147618 A1 describe the preparation of silver nanoparticles in various media using gamma radiation or ultrasound in the presence of polymeric stabilizers.
• the problem underlying the present invention is thus to provide a process for the production of metal nanoparticles, which at least largely avoids or at least mitigates the previously described disadvantages of the prior art processes.
• the present invention proposes a method according to claim 1; Further, advantageous embodiments are the subject of the relevant sub-claims.
• the subject of the present invention are dispersions of the metal nanoparticles according to the invention in a carrier or dispersion medium according to claim 44.
• the invention further relates to coating materials and coating systems, in particular paints, paints and the like, glasses and glassy coatings, inks and printing inks, plastics, foams, cosmetics, in particular nail varnishes, cleaning agents and impregnating agents, adhesives, sealants and catalyst systems, which are known from US Pat Metal nanoparticles according to the invention or the dispersions according to the invention contain (claim 45).
• coating materials and coating systems in particular paints, paints and the like, glasses and glassy coatings, inks and printing inks, plastics, foams, cosmetics, in particular nail varnishes, cleaning agents and impregnating agents, adhesives, sealants and catalyst systems, which are known from US Pat Metal nanoparticles according to the invention or the dispersions according to the invention contain (claim 45).
• the subject matter of the present invention is a process for the preparation of metal nanoparticles in which metal ions are reduced by means of at least one reducing agent in the presence of at least one polymeric stabilizer and converted into metal nanoparticles. This results in dispersions of metal nanoparticles, which are modified or coated on their surface with the polymeric stabilizer.
• the reducing agent effects the reduction to elemental metal in the oxidation state 0, while the polymeric stabilizer ensures that the metal particles formed are produced as so-called nanoparticles, in particular agglomerate or not as an amorphous precipitate can separate or the like.
• the inventive method is carried out in a liquid, preferably an aqueous medium or medium.
• a liquid preferably an aqueous medium or medium.
• the metal ions are dissolved in the respective medium or finely distributed in the form of salts.
• the process according to the invention is carried out as a liquid-phase process, in particular as a single-phase reaction. This is a significant advantage over the initially described in the prior art reactions with two liquid phases to see.
• defoamers known per se to the person skilled in the art can be used for this purpose.
• the amount of defoamer can vary within wide ranges; Usually, the defoamer in amounts of 0.0001 to 5 wt .-%, preferably 0.001 to 2 wt .-%, particularly preferably 0.01 to 1 wt .-%, based on the total reaction mixture used.
• Additives suitable according to the invention are selected, for example, from the group of pH regulators, pH buffer substances, emulsifiers, rheology modifiers, preservatives, surfactants or the like.
• co-solvent may also be added to the reaction mixture.
• the amount of co-solvent (s) can likewise vary widely; Usually amounts of from 0.01 to 10% by weight, particularly preferably from 0.1 to 7% by weight, very particularly preferably from 0.5 to 5% by weight, of co-solvent (s) are used on the entire reaction.
• the co-solvent may in particular be selected from organic, preferably polar solvents, such as alcohols, glycols (eg butylglycol etc.) or the like, or else from inorganic solvents, such as acids and bases.
• inorganic acids or bases for metal salts can be used as co-solvents for starting materials.
• NH 3 to achieve the solubility of AgCl in water, which leads to the formation of [Ag (NH 3 ) 2 ] Cl, or HCl for AuCl 3 as the starting material, which in turn leads to the formation of HAuCl 4 .
• the process according to the invention can be carried out over a wide temperature range. Since the process is carried out as a liquid phase process, the temperature range is limited downwards by the melting point of the reaction milieu and upwards by its boiling point. In general, especially when using an aqueous medium, the process in the temperature range of> 0 0 C and ⁇ 100 0 C, in particular 5 to 90 0 C, preferably 10 to 80 0 C, particularly preferably 10 to 40 0 C, very particularly preferably 10 to 30 0 C, performed. Lower temperatures have the advantage that generally more stable dispersions are obtained and, in addition, the resulting nanoparticles generally show better redispersibility.
• a further advantage of the method according to the invention can be seen in the relatively short process times, which is of great advantage, especially in the case of large-scale implementation or implementation on an industrial scale.
• the process according to the invention is usually carried out with a reaction time of ⁇ 10 minutes, in particular ⁇ 5 minutes, preferably ⁇ 1 minute, more preferably ⁇ 0.5 minutes.
• the process according to the present invention is carried out with a reaction time in the range of 0.0001 to 10 minutes, in particular 0.0001 to 5 minutes, preferably 0.0001 to 1 minute, particularly preferably 0.0001 to 0.5 minutes.
• the actual implementation is completed within a few seconds in the context of the method according to the invention.
• the process according to the invention can alternatively be operated either batchwise or batchwise or else continuously.
• the inventive method can be carried out, for example, in a simple stirred tank.
• a continuous procedure however, the process of the invention in a continuous stirred or tubular reactor, a continuous Rhakkesselkaskade or be carried out in a so-called spinning disk reactor.
• the continuous implementation in a so-called spinning-disk reactor offers the additional advantage of extremely fast conversion due to a very rapid and intensive mixing; for further details of the procedure in a spinning disk reactor, reference may be made, for example, to WO 2006/018622 A1, WO 2006/040566 A1 and WO 2006/008500 A1, the entire disclosure of which is hereby incorporated by reference.
• the method according to the invention can be carried out such that a temporal and / or local separation of the nucleation and growth processes is achieved by regulating temperature and / or volume flows;
• the method according to the invention can be carried out in particular in a so-called microreaction technology system.
• a particular advantage of this procedure is that a particularly uniform morphology and / or monodispersibility of the resulting metal nanoparticles is achieved.
• the reducing agent should be selected such that it is capable of reducing the relevant metal ion to be reduced to elemental metal (i.e., oxidation state: 0).
• the reducing agent in the electrochemical series has a lower normal potential than the metal of the metal ion to be reduced.
• the reducing agent should be selected to be soluble or dispersible in the reaction medium.
• Reducing agents which are suitable according to the invention are in particular selected from the group of inorganic hydrides, such as sodium borohydride or lithium aluminum hydride; inorganic thiosulfates or thiosulfuric acid; inorganic sulfides or hydrogen sulfide; inorganic sulfites; hydrazines; hydroxylamines; Hydrogen (eg gaseous or in situ generated hydrogen or nascent hydrogen); carbon monoxide; Acetylene; Oxalic acid or oxalates; Citric acid or citrates; Tartaric acid or tartrates; monohydric or polyhydric alcohols, e.g.
• inorganic hydrides such as sodium borohydride or lithium aluminum hydride
• inorganic thiosulfates or thiosulfuric acid inorganic sulfides or hydrogen sulfide
• inorganic sulfites inorganic sulfites
• hydrazines
• glycol or else hydroxy-functional polyglycol ethers; Sugar; inorganic phosphides; and mixtures or combinations of at least two of the aforementioned reducing agents.
• inorganic hydrides in particular of the aforementioned type.
• the amount of reducing agent used can likewise vary widely.
• the reducing agent in a ratio of reducing agent to metal ions, calculated as the amount of electrons required for the reduction in the range of 1.05: 1 to 200: 1, in particular 1.1: 1 to 100: 1, preferably 1 , 1: 1 to 50: 1, used.
• the larger the aforementioned ratio the more nuclei are formed and the smaller the nanoparticles are formed.
• the metal is selected from at least one metallic element of groups III A to VA and IB to VIII B of the periodic system of the elements.
• the metal is selected from the group of Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Ru, Os, Se, Te, Cd, Bi, In, Ga, As, Ti, V, W , Mo, Si, Al and / or Sn and mixtures, alloys and mixed crystals of at least two of these elements.
• the metal is selected from the group of Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Ru, Os, Se and / or Te and mixtures, alloys and mixed crystals of at least two of these elements .
• the metal is selected from noble metals, in particular Cu, Ag, Au, Ni, Pd, Pt, Ru, Ir and / or Rh, most preferably Ag, Au, Pd and / or Pt.
• the nanoparticles can be obtained based on at least two metals, in particular of the type CdSe, CdTe, BiTe, GaAs, InAs, AgPd, CoPt and / or AgAu. These are thus at least binary metal nanoparticles.
• Such systems are of interest, for example, for the semiconductor technology and the catalyst technology.
• the metal ions can basically be used in any desired forms. It is possible to use all metal ion sources which are compatible in the context of the process according to the invention, in particular in which the reaction medium is soluble or dispersible.
• the metal ions may be present in particular in the form of metal salts (eg AgNO 3 , Na 2 PtCl 4 , NaAuCl 4 • 2H 2 O etc.), metal acids and their hydrates (eg HAuCl 4 • 3 H 2 O, H 2 PtCl 4 • 6H 2 O, H 2 PtCl 4 etc.), ionic or covalent metal compounds (eg AuCl 3 , PtCl 2 , AgCl etc.), complexed metal ions and / or metal electrodes (eg in electrolysis ), preferably in the form of metal salts.
• metal salts eg AgNO 3 , Na 2 PtCl 4 , NaAuCl 4 • 2H 2 O etc.
• metal acids and their hydrates e
• the amount of metal ions used can likewise vary widely.
• the metal ions based on the total reaction mixture and calculated as metal, in amounts of 0.0001 to 20 wt .-%, in particular 0.001 to 15 wt .-%, preferably 0.005 to 10 wt .-%, particularly preferably 0, 01 to 3 wt .-%, most preferably 0.1 to 2 wt .-%, used.
• the metal nanoparticles obtained can have absolute particle sizes in the range from 0.3 to 1000 nm, in particular 0.5 to 750 nm, preferably 1 to 500 nm, particularly preferably 2 to 100 nm, very particularly preferably 3 to 50 nm.
• the metal nanoparticles obtained have average particle sizes (determined as so-called D50 value) in the range from 1 to 500 nm, in particular 2 to 200 nm, particularly preferably 2 to 100 nm, very particularly preferably 5 to 40 nm.
• the size and shape of the resulting metal nanoparticles can be varied by the corresponding variation of the reaction conditions. For example, by varying the type and / or quantity of the reduction by means of and / or the type and / or amount of the polymeric stabilizer and / or the reaction temperature and / or the addition mode (single addition, stepwise addition, etc.) or the like, the particle size targeted influence or adjust. This is known to the skilled person as such.
• the metal nanoparticles obtained may have a bimodal particle size distribution.
• the average particle diameter (D50) of the two fractions of metal nanoparticles can advantageously not differ by at least 10 nm, in particular at least 25 nm, preferably at least 50 nm, particularly preferably at least 75 nm, very particularly preferably at least 100 nm.
• special effects, in particular surface effects can be achieved, in particular with regard to the mechanical properties, such as mechanical stability, abrasion resistance, surface properties, gloss etc.
• a bimodal particle size distribution can be achieved by deliberate variation or adjustment of the reaction conditions, for example by selecting the ratio of reducing agent to metal ions to be reduced, by the amount of polymeric stabilizer (eg lower or substoichiometric amounts of polymeric Stabilizer), by stepwise and / or repeated addition of the individual reagents etc. This is familiar to the person skilled in the art as such.
• the polymeric stabilizer As far as the polymeric stabilizer is concerned, it can equally be used in wide ranges.
• the polymeric stabilizer may be used in amounts of 1 to 1000% by weight, preferably 5 to 500% by weight, more preferably 10 to 200% by weight, most preferably 20 to 100% by weight, based on the resulting metal nanoparticles are used.
• the polymeric stabilizer As far as the chemical nature of the polymeric stabilizer is concerned, it is in particular a polymeric dispersant or a polymeric wetting agent and / or a surfactant.
• the molecular weight of the polymeric stabilizer used can equally vary within wide ranges.
• the polymeric stabilizer used usually has an average, in particular weight-average molecular weight of at least 1,000 g / mol, preferably at least 1,500 g / mol.
• the polymeric stabilizer has an average, in particular weight-average molecular weight in the range from 1,000 to 1,000,000 g / mol, in particular from 1,250 to 100,000 g / mol, preferably from 1,500 to 75,000 g / mol, particularly preferably from 2,000 to 50,000 g / mol ,
• the polymeric stabilizer is based on a functionalized, in particular acid and / or basic functionalized, polymer, in particular with polar functional groups formed.
• the polymeric stabilizer can be selected from the group of functionalized polyamines, functionalized polyurethanes, functionalized poly (meth) acrylates, functionalized vinyl copolymers, functionalized polyether / polyester copolymers, functionalized polyethers, functionalized polyesters, functionalized fatty acid copolymers, functionalized block copolymers. copolymeric and / or functionalized polyalkoxy laten and mixtures or combinations of at least two of these compounds.
• the polymeric stabilizer may usually be based on a functionalized, especially acid and / or basic functionalized polymer, the polymer containing at least one functional group, which may in particular be selected from the group of hydroxyl (-OH), thiol (-) SH), amine, ammonium, carboxyl, carbonyl, ester, ether, sulfonyl, phosphoric and / or phosphoric acid ester functions, preferably hydroxyl (-OH), thiol (-SH) and / or amine functions.
• a functionalized, especially acid and / or basic functionalized polymer the polymer containing at least one functional group, which may in particular be selected from the group of hydroxyl (-OH), thiol (-) SH), amine, ammonium, carboxyl, carbonyl, ester, ether, sulfonyl, phosphoric and / or phosphoric acid ester functions, preferably hydroxyl (-OH), thiol (-SH) and / or
• the base number of the polymer in question may be at least 10 mg KOH / g, in particular at least 20 mg KOH / g, preferably at least 25 mg KOH / g, and in the case of acidic functionalization, the acid number may be at least 10 mg KOH / g, preferably at least 25 mg KOH / g, more preferably at least 50 mg KOH / g.
• the polymeric stabilizer can be selected from the dispersants and / or wetting agents mentioned below, as described in the publications listed below, whose respective disclosure content is hereby incorporated by reference:
• modified polyurethanes and polyamines according to EP 1 593 700 A; salified polyamines according to EP 0 893 155 A; - Phosphoric acid ester according to EP 0 417 490 A;
• a step of purification may follow the actual production of the metal nanoparticles.
• the purification can be carried out in a manner known per se to those skilled in the art, so that no further relevant embodiment is required.
• the resulting metal nanoparticles can be separated by methods known per se, to which may optionally follow a process step of redispersing (for example in another medium).
• the metal nanoparticle dispersions obtained can also be used as such, ie as they are obtained immediately after the preparation, since the respective metal nanoparticles are present in stable, in particular long-term stable dispersion.
• the process according to the invention for the preparation of metal nanoparticles is associated with a number of advantages, some of which are to be mentioned below in a nonlimiting manner:
• the inventive method works cost-effectively and economically and is also readily Anlagenmotherbar on an industrial or industrial scale.
• the method according to the invention can be configured extremely flexibly with regard to its process control.
• the process of the invention can be operated continuously as a batch. In discontinuous procedure can be moved, for example, in a stirred tank. In a continuous procedure, the reaction can be carried out, for example, in a continuous stirred reactor or tubular reactor, a continuous stirred tank cascade or in a so-called spinning disk reactor.
• the relatively low process temperatures also contribute to process efficiency and process economics and also meet today's environmental requirements.
• the process according to the invention is carried out in purely aqueous media; it is, as it were, a "green process" which, moreover, is flexibly modifiable.
• the process is thus simple, inexpensive and ecologically compatible and largely dispenses with organic solvents.
• the metal nanoparticles obtained in the context of the process according to the invention can readily be isolated from the dispersion. Due to the stability of the dispersions, however, the dispersions can also be used as such without having to carry out a preceding isolation of the metal nanoparticles.
• nanoparticles are achieved in a variety of media (such as water, organic solvents, polymers, waxes, oils, glycols, etc.).
• dispersants or wetting agents used can readily be removed either partially or completely
• the metal nanoparticles obtained by the process according to the invention allow a wide variety of uses, for example as paint and / or plastic additives, as pigments, as catalysts, etc. This is described in detail below.
• the process according to the invention thus provides a purely aqueous synthesis of metal nanoparticles, more preferably noble metal nanoparticles, using suitable polymeric wetting or dispersing agents.
• the synthesis can be flexibly applied to different metals (eg silver, gold, etc.).
• suitable wetting or dispersing agents By using suitable wetting or dispersing agents, the subsequent dispersibility can be controlled in a wide variety of media.
• By adapting the oxidation potential of the reducing agent and choosing a suitable stabilizer it is also possible to produce nanoparticles (oxidation) -sensitive metals.
• the inventive method is also flexible transferable to a variety of metals. With the method according to the invention can be achieve significantly higher concentrations in dispersion of nanoparticles compared to the prior art. In addition, the process according to the invention uses exclusively favorable starting chemicals or educts. In addition, the method according to the invention can also be carried out on an industrial or industrial scale and thus upscalebar. Due to the removability of the wetting or dispersing agents used, no "dead" surfaces are formed on the resulting metal nanoparticles.
• a further subject of the present invention - according to one aspect of the invention - are the metal nanoparticles obtainable by the process according to the invention.
• the present invention relates to metal nanoparticles which comprise on their surface at least one polymeric stabilizer, in particular a polymeric wetting and dispersing agent, or on their surface with at least one polymeric stabilizer, in particular a polymeric wetting agent Dispersants, modified and / or coated.
• the metal nanoparticles according to the invention have an excellent dispersing behavior and can be easily redispersed even after isolation from the reaction mixture.
• the metal nanoparticles according to the invention are dispersible both in aqueous and in organic media.
• the metal nanoparticles according to the invention are dispersible in both polar and non-polar solvents.
• the dispersing properties of the metal nanoparticles according to the invention can be adjusted selectively by the surface modification with the polymeric stabilizer or, so to speak, tailor-made.
• Another object of the present invention - according to a third aspect of the invention - is the inventive use of the metal nanoparticles according to the present invention.
• the metal nanoparticles according to the invention can be used, for example, as additives, pigments or fillers, in particular for paints, coatings and plastics.
• metal nanoparticles according to the invention can be used as or in catalysts or catalyst systems.
• the metal nanoparticles according to the invention can also be used in coating materials and coating systems, in particular paints, inks and the like, in glasses and glassy coatings, in inks and printing inks, in dispersions of all kinds, in plastics, in foams, in cosmetics, in particular nail varnishes , in detergents and impregnating agents, in adhesives, in sealants and in catalysts or catalyst systems, in particular as additives, pigments or fillers.
• coating materials and coating systems in particular paints, inks and the like, in glasses and glassy coatings, in inks and printing inks, in dispersions of all kinds, in plastics, in foams, in cosmetics, in particular nail varnishes , in detergents and impregnating agents, in adhesives, in sealants and in catalysts or catalyst systems, in particular as additives, pigments or fillers.
• the nanoparticles according to the invention can be used in optics and optoelectronics as well as in electronics, electrical engineering and semiconductor technology.
• the metal nanoparticles according to the invention can be used to increase conductivities, in particular of plastics, or else for the production of printable circuits.
• metal nanoparticles according to the invention can also be used in spectroscopy, in particular in Raman spectroscopy, for example for purposes of signal amplification.
• metal nanoparticles of the invention in the glass, ceramic and enamel manufacture, for. As in the manufacture of windows (for example, church windows), in particular as pigments or dyes. Furthermore, it is possible to use the metal nanoparticles according to the invention in textile production, for example, equally as pigments and / or dyes.
• a further subject matter of the present invention - according to one aspect of the invention - are dispersions which contain the metal nanoparticles according to the invention in a carrier or dispersion medium.
• further object of the present invention are coating materials and coating systems, in particular paints, inks and the like, plastics, foams, cosmetics, in particular nail varnishes, adhesives, sealants and catalyst systems comprising the metal nanoparticles according to the invention or the comprising dispersions containing them.
• Gold nanoparticles are prepared according to the method described by Turkevich et al. developed method by citrate synthesis as follows. 10 ml of an aqueous solution of 2.5 - 10 '4 mol / 1 HAuCl 4 • 3 H 2 O are heated to 95 0 C. Subsequently, 417 ⁇ l of a 20 mmol / l trisodium citrate solution are added with vigorous stirring, whereupon the solution slowly changes its color to red. The Au / citrate ratio is 0.3. The solution is left for 15 minutes near the boiling point, then allowed to cool the whole.
• the example is repeated except that 312 ⁇ l of a 20 mmol / l trisodium citrate solution are added, which corresponds to an Au / citrate ratio of 0.4.
• the aforementioned Au / citrate ratios influence the resulting sizes of the Au nanoparticles obtained.
• Example 2 Preparation of Silver Nanoparticles by Two-Phase Synthesis in the Presence of NaBH 4 as Reducing Agent (Comparative, Prior Art) 9 mmol (1.53 g) of silver nitrate are dissolved in 300 ml of water in a 1-liter three-necked flask. 40 mmol (21.86 g) of tetra-n-octylammonium bromide are dissolved in 204 ml of CHCl 3 in a beaker.
• the CHCl 3 solution is added to the silver nitrate solution. After about 1 minute, the N 2 stream is issued. The CHCl 3 phase turns green and becomes cloudy. The water phase becomes milky, but contains no target product.
• the resulting powder must still be washed with ethanol to remove impurities and then be dispersed in nonpolar solvents up to 0.2%.
• the particle size is 10 nm, but has a coarse fraction (10%) of> 100 nm. The reaction is very sensitive and not always reproducible.
• EXAMPLE 3A Preparation of Silver Nanoparticles by the Process According to the Invention (Invention) First, a solution of 3.5 parts by weight of AgNO 3 , 100 parts by weight of water, 7.2 parts by weight of a polymeric wetting or dispersing agent ( z. B. Disperbyk ® 2001, BYK-Chemie GmbH, Wesel, Germany) and optionally 0.6 parts by weight of a defoamer (z. B. BYK028 BYK-Chemie GmbH, Wesel, Germany) ( "solution a”) prepared and stirred at room temperature. The approach is a cloudy mixture.
• a polymeric wetting or dispersing agent z. B. Disperbyk ® 2001, BYK-Chemie GmbH, Wesel, Germany
• a defoamer z. B. BYK028 BYK-Chemie GmbH, Wesel, Germany
• solution B is prepared from 3 parts by weight of NaBH 4 and 50 parts by weight of water. Solution B is slowly added to solution A at room temperature. It creates strong foam and blackening. This results in a dispersion of Ag nanoparticles in water.
• z. B. be extracted with PMA (methoxypropyl acetate), which leads to nanoparticles of high purity, which z. B. can be used for catalytic purposes, or centrifuged, dried and redispersed (eg in PMA).
• PMA methoxypropyl acetate
• the preceding experiment is repeated, but with the difference that the solution B is rapidly added to the solution A. Rapid addition of solution B to solution A produces smaller nanoparticles. As a result of the rate of addition, the particle size of the resulting nanoparticles can thus be controlled in a targeted manner.
• Example 3B is used: Preparation of silver nanoparticles by the inventive process (invention) Example 3A but with the difference that another wetting agent (Disperbyk ® 194 from BYK-Chemie GmbH, Wesel, Germany concrete) is repeated.
• the resulting Ag nanoparticles are redispersible both in water and in PMA. This dispersion of Ag nanoparticles can thus be used directly as an additive, if appropriate after a corresponding treatment and / or concentration step.
• HAuCl 4 is used instead of AgNO 3 . This results in the corresponding Au nanoparticles.
• Example 3D Reduction of AgNO 3 in Water Without the Presence of a Dispersing Agent (Comparison)
• Example 3A is repeated, but with the difference that no wetting or dispersing agent is used as stabilizer. There is no formation of Ag nanoparticles, but a through-reaction to an Ag sludge.
• the silver particles produced at temperatures up to 40 ° C have much better redispersibilities in polar solvents, such as water and 1,3-propanediol.
• polar solvents such as water and 1,3-propanediol.
• the dispersing behavior in ethyl acetate is initially good in all experiments, but the dispersions of the nanoparticles From 60 0 C lower stability in ethyl acetate, as evidenced by the formation of a silver level on the glass wall. Redispersibility in PMA is equally good at all temperatures.
• the formation of a silver mirror can also be used to advantage for the mirroring or formation of conductive layers.
• the destabilization causes the particles to approach each other and optionally a plasmon transition.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Nanotechnology (AREA)
• Crystallography & Structural Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Dispersion Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Composite Materials (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)
• Conductive Materials (AREA)
• Non-Insulated Conductors (AREA)
• Cosmetics (AREA)
• Paints Or Removers (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Powder Metallurgy (AREA)

Priority Applications (6)

Applications Claiming Priority (4)

Publications (1)

Family

ID=42168810

Family Applications (1)

Country Status (8)

Cited By (7)

Families Citing this family (68)

Citations (33)

Family Cites Families (17)

• 2009
  • 2009-03-28 DE DE102009015470A patent/DE102009015470A1/de not_active Withdrawn
  • 2009-11-20 WO PCT/EP2009/008289 patent/WO2010066335A1/de not_active Ceased
  • 2009-11-20 JP JP2011539917A patent/JP5833447B2/ja not_active Expired - Fee Related
  • 2009-11-20 KR KR1020117016016A patent/KR101278939B1/ko not_active Expired - Fee Related
  • 2009-11-20 EP EP09760108A patent/EP2358489A1/de not_active Withdrawn
  • 2009-11-20 BR BRPI0923509A patent/BRPI0923509A2/pt not_active IP Right Cessation
  • 2009-11-20 US US13/139,366 patent/US8870998B2/en not_active Expired - Fee Related
  • 2009-11-20 CN CN2009801499743A patent/CN102245333B/zh not_active Expired - Fee Related

Patent Citations (36)

Non-Patent Citations (5)

Also Published As

Similar Documents

Legal Events