Ultrafine copper powder

Isotopic ultrafine copper powder at least 99,999x%

Ultrafine copper powder

Ultrafine copper powder in Aargon - ISE

Ultrafine copper powder is one of the most expensive elements in the world. This is not due to the cost of materials, but more to the complex production. In order to obtain a copper powder which can be used for medical purposes and in the aerospace industry, the particle size must not be larger than 1 µm, the particles must be approximately round and the purity must be at least 99,999%. Copper powder of this quality costs between EUR 300 and EUR 2500 per gram, depending on the purchase quantity. To produce one gram of this powder, more than a quarter of a ton of copper is required, along with a lot more solutions, catalysts and additives. The most expensive part of this process, however, is the equipment required to manufacture it.

The worldwide annual demand for ultrafine copper powder is 12-15 tonnes. However, a much larger amount of copper is used as a financing object. How much copper powder has disappeared into bank vaults worldwide and will probably never come out again, can not be verified.

If you are in possession of ultrafine copper powder, you are welcome to contact us for an analysis, evaluation or sale.

If you are looking for ultrafine copper powder, please contact us directly.

Your contact for ultrafine copper powder: Arndt Uhlendorff [email protected]

The following description from the patent register gives an insight into the complex procedure. The patent described here is registered with Mitsubishi Gas Chemical Co. Inc. Tokyo, Japan. An alternative production is filtration and separation by means of a centrifuge. However, this is even more complicated and cost-intensive than the methodology described here.

The present invention relates to a process for producing a novel fine copper powder containing nearly spherical primary particles having an average particle diameter between 0,2 and 1 μm, a specific surface area between 5 and 0,5 m² / g, and a low tendency to agglomerate. The fine copper powder produced by the method of the present invention can be advantageously used as an electrically conductive filler for, for example, coating compositions, pastes and resins, as an antibacterial additive, and as a starting powder for powder metallurgy.

Conventionally known methods for producing copper powders include an electrolytic method, a sputtering method and the mechanical pulverization, and such copper powders produced by the above methods are mainly used in powder metallurgy.

Although these methods, which usually produce powders of relatively large particle diameters, have been advanced to produce finer copper powders; By controlling the manufacturing conditions or by sieving, the production efficiency is low and the fineness achievable by such methods is limited.

The article 'Decomposition process for iron, cobalt, nickel and copper formates' published in Poroshk. Metal. (Kiev 1977 (5), 7-13 discloses the thermal decomposition of Fe, Co, Ni and Cu formates. The average size of the Fe and Co particles obtained by the formate decomposition was 0,1 to 0,3, 60 µm and the specific surface area was about XNUMX m² / g. Larger particles of Ni and Cu were obtained due to sintering.

For use for purposes such as applications in coating compositions, pastes and resins, on the other hand, in view of uniform dispersion and uniform coating, copper powder must be composed of powder particles which are finer, ie 10 μm or less, and uniform in shape. For use in electronic parts, copper powder having only an insignificant amount of alkali metals such as Na or K, sulfur and halogens such as Cl are preferable in view of prevention of corrosion and deterioration of electrical properties due to moisture.

Fine copper powders for use for the above purposes are prepared, for example, by reduction precipitation of a copper compound in the liquid phase, evaporation in a vacuum or in an inert gas, gas phase reduction of a copper salt, and solid phase reduction of an oxide.

However, the liquid phase reduction precipitation process is poor in performance and cost because the particle diameter distribution is wide, the reducing agent is expensive, and the process has to be carried out in batch operation. Evaporation in vacuum or in an inert gas is deficient because although copper powders can be obtained which are extremely fine and have a large specific surface area, prevention of oxidation and handling of copper powders is difficult, the production equipment is expensive and mass yield is low. The gas phase reduction of a copper salt, in particular a copper halide, which is carried out at high reaction temperatures, has problems such as the corrosion of the plant by a halogen generated in the decomposition of the halide and the annoying collection of the powder produced, and it is also deficient because a large amount of the halogen remains in the copper produced. In carrying out the solid-phase reduction of an oxide, it is essential that the starting material is finely pulverized and purified before use, since the shape and purity of the copper powder to be produced depends on the starting material, and the particles are agglomerated and waxy due to their sufficient contact with the reducing gas and also due to the heat generation accompanying the reduction. Consequently, the solid phase reduction method has been deficient because the production efficiency is low and the control of the production conditions is difficult.

Under the above circumstances, the inventors have made intensive studies to develop a method for producing fine copper powder by simple procedures. As a result of their efforts, they have found a method defined in claim 1 for producing a copper powder having an average primary particle diameter of 0,2 to 1 μm, a specific surface area of ​​5 to 0,5 m² / g, and a low tendency to agglomerate. The present invention has been completed on the basis of the above.

Preferred embodiments are listed in the dependent claims 2 and 3.

Accordingly, it is an object of the present invention to provide a method for producing a fine copper powder as described above.

The method of producing a fine copper powder according to the present invention involves thermally solid-phase decomposing anhydrous copper formate in a non-oxidizing atmosphere at a temperature ranging between 150 and 300 ° C to obtain a fine copper powder having an average primary particle diameter of 0,2 to 1 μm , having a specific surface area of ​​5 to 015 m2 / g and a low tendency to agglomerate, wherein the anhydrous copper formate is a waterless copper formate powder having a particle size of 850 μm or less, and 20 weight percent or more thermal decomposition within a temperature range of 90 to 160 ° C when the anhydrous copper formate powder is heated in a nitrogen or hydrogen gas atmosphere at a heating rate of 200 ° C / min. is heated.

In a preferred embodiment of the present invention, the obtained fine copper powder contains agglomerates of fine copper powder primary particles, wherein the average diameter of the agglomerates is 10 μm or less. The anhydrous copper formate powder is obtained by dehydrating copper formate hydrate at a temperature of 130 ° C or less, and then pulverizing the dehydrated copper formate. The anhydrous copper formate in powder form is copper formate obtained by reacting at least one copper compound selected from the group consisting of copper carbonate, copper hydroxide and copper oxide with formic acid or methyl formate and the fine copper powder obtained by the method described above is then washed with water, an organic solvent or a solution of rust inhibitor for copper in water or an organic solvent so as to reduce in the powder at least one impurity element which is selected from the group of halogen, sulfur, alkali metals and heavy metals to produce a purified fine copper powder.

Detailed description of the invention

The method of the present invention will be described in detail below.

The anhydrous copper formate used in the present invention is generally copper (II) formate. The anhydrous copper formate is an anhydrous copper formate powder satisfying the thermal decomposition requirement that, when the powder is contained in an amount of 10 mg in a nitrogen or hydrogen gas atmosphere at a heating rate of 3 ° C / min. is heated, 90 weight percent or more of the powder within a temperature range of 160 to 200 ° C are thermally decomposed. This thermal decomposition behavior is preferable from the viewpoint of obtaining a fine copper powder which has higher purity and less tendency to agglomerate. In view of obtaining a copper powder having a smaller agglomerate particle size, the anhydrous copper formate powder has a particle size of 850 μm (20 mesh) or finer, and especially a powder having a particle size of 150 μm (100 mesh or finer). Such an anhydrous copper formate powder can be obtained by dehydrating copper formate hydrate at a temperature of 130 ° C or less, and then pulverizing the dehydrated copper formate by forming crystals of anhydrous copper formate directly from an aqueous solution of copper formate and then pulverizing the crystals, or by directly forming a crystalline anhydrous copper formate powder having a particle size of 850 μm (20 mesh) or finer from an aqueous solution of copper formate. It is preferable that the anhydrous copper formate powder thus obtained has a low content of impurity elements, especially alkali metals such as Na or K, sulfur and halogens such as Cl, for the purpose of producing a fine copper powder having a reduced impurity content.

Anhydrous copper formate produced by any of a variety of methods can be used in the present invention as far as the copper formate to be used satisfies the above requirements. However, anhydrous copper formate prepared by a method using copper carbonate, copper hydroxide or copper oxide as the starting copper compound and reacting this starting copper compound with formic acid or methyl formate is useful as a starting material for the process of the present invention when the process is industrial is performed.

Since copper carbonate, copper hydroxide and copper oxide, which are industrially obtained from cheaper copper salts or waste copper, are all practically insoluble in water, it can easily be achieved that the copper compounds obtained have a reduced content of such impurities as described above, by the copper compounds before Drying be washed or subjected to a different treatment. For example, in the case where copper sulfate is reacted with sodium carbonate or sodium bicarbonate to produce copper carbonate, the impurity elements attributable to the starting compounds, such as Na and S, in the copper carbonate can be reduced by a process which involves adding sodium carbonate or sodium bicarbonate to one another aqueous copper sulfate solution, allowing the reactant to react at a temperature of from 60 to 85 ° C to form a precipitate, and then washing the precipitate with water without drying it.

The order of reactivity of the above-described copper compounds with formic acid is: copper hydroxide> copper carbonate>> copper (I) oxide, copper (II) oxide. A copper compound selected from these compounds is mixed with formic acid or methyl formate usually in an aqueous medium, the proportion of the formic acid or methyl formate being not less than the equivalent proportion of the copper compound, the proportion being determined according to the kind of the copper compound. The resulting mixture is kept at a temperature between room temperature and 30 ° C for 24 minutes to 100 hours to allow the reactants to undergo a liquid phase reaction to give an aqueous solution of copper formate.

In the above process, the starting compounds may remain unreacted depending on the reaction conditions, by-products may be formed in addition to the copper formate, or the copper formate may further react to form other compounds. In this way, the resulting copper formate contains such other compounds. For example, since copper formate is remarkably unstable in aqueous solution, the greater the proportion of water and the higher the temperature, the more the formation of water-insoluble products such as basic copper formates is accelerated due to side reactions or subsequent decomposition reactions. Any unreacted starting compounds, such as copper carbonate, copper hydroxide and copper oxide, and the products of side reactions or decomposition reactions, such as basic copper formates, can be converted by reduction into metallic copper, without any substance included in the copper being supplied. However, since the reduction reaction is accompanied by considerable heat generation and thereby water forms, such copper compounds are not suitable for the thermal solid phase decomposition in the method of the present invention, because the use of such compounds requires calorimetric control and other complicated procedures.

The thermal decomposition behavior of these copper compounds was examined by means of a differential thermal balance analysis in which copper hydroxide, basic copper carbonate, anhydrous copper formate and a product of the subsequent decomposition reaction of copper formate, each weighing 10 mg, in an N 2 or H 2 gas atmosphere with a heating rate of 3 ° C / min. were heated. The results obtained on the peak temperatures in the calorimetric changes (endothermic, exothermic or the like changes) and the decomposition products are shown in Table 1.

Table 1

Atmosphere N 2 gas H 2 gas Copper hydroxide Basic copper carbonate monohydrate Anhydrous copper formate Decomposition product of copper formate endothermic; Oxide slightly endothermic; Copper powder exothermic; Oxide-containing copper exothermic; Copper powder

Table 1 shows that all copper compounds other than the anhydrous copper formate decompose in a nitrogen (N 2 gas) atmosphere to form copper oxide or a powder mainly containing copper oxide, and the decomposition of these copper compounds is endothermic or exothermic. The calorimetric changes in these copper compounds are at least ten times greater than those in anhydrous copper formate and, in particular, the endothermic change in basic copper carbonate monohydrate, which contains water of crystallization, is about a hundred times greater than that in anhydrous copper formate.

In addition, with the exception of anhydrous copper formate, all copper compounds must be heated in a reducing atmosphere (H 2 gas) to form metallic copper powder, and their reactions in the reducing atmosphere are exothermic, their exothermic amounts of heat at least five times greater than that of anhydrous copper formate are.

Table 1 also shows that the decomposition peak temperatures of the anhydrous copper formate non-occlusive copper compounds are considerably different from those of the anhydrous copper formate, although some of the former overlap slightly with the latter.

From the above, it can be seen that anhydrous copper formate can be easily thermally decomposed to form copper powder without undergoing calorimetric changes. The following can also be understood. In the case where anhydrous copper formate is contaminated with these copper compounds, metallic copper is formed by the reducing power of the decomposed formic acid. However, if the proportion of the compounds other than anhydrous copper formate is too large, the exothermic heat accompanying the reduction reactions is too large, and as a result, the copper powder particles formed agglomerate with each other because of local heating, etc., so that it is difficult to to obtain a fine copper powder. If the proportion of these compounds is larger, the generated copper powder becomes a copper powder containing copper oxide.

Therefore, the anhydrous copper formate used in the present invention is preferably one having a small amount of these compounds other than copper formate. A practical measure of this is that when a sample of anhydrous copper formate in an amount of 10 mg in a nitrogen or hydrogen gas atmosphere at a heating rate of 3 ° C / min. is heated, 90 weight percent or more of the sample are thermally decomposed within the temperature range of 160 to 200 ° C. It is preferred that the above be considered when the anhydrous copper formate is industrially synthesized for use in this invention.

In the method of the present invention, an anhydrous copper formate powder as described above is thermally decomposed in the solid phase to produce a fine copper powder.

The thermal decomposition of anhydrous copper formate in the solid phase is carried out in a non-oxidizing atmosphere, usually under ordinary pressure, at a temperature in the range between 150 and 300 ° C, preferably between 160 and 250 ° C. The process may be carried out in batch mode wherein the anhydrous copper formate is packed in a can, can or other container and heated to and maintained at a predetermined temperature. Alternatively, the process may be carried out in a continuous manner wherein the anhydrous copper is applied to continuous transfer media, such as a conveyor belt, and the transfer agents continuously convey the copper formate to a heating zone which is heated to a predetermined temperature where the copper formate is thermally decomposed , and the decomposition product is then discharged.

In the present invention, the anhydrous copper formate powder in a solid phase means an anhydrous copper formate powder which is packed in a container such as a can or the like made of a material which is resistant to the heating temperatures and is not attacked by formic acid vapor, an anhydrous copper formate powder applied to a running belt made of such a material, or an anhydrous copper formate powder in a similar state. The amount of the anhydrous copper formate powder packed in a container or placed on a moving belt is not particularly limited because the relationship between the amount of the copper formate powder and the agglomerate-forming properties of the obtained fine copper powder is insignificant. However, the anhydrous copper formate powder is usually used in such an amount that the inner part of the anhydrous copper formate can be completely decomposed within a desired period of time, for example, from several minutes to several hours. The non-oxidizing atmosphere means an atmosphere of N 2, H 2, CO 2, CO, Ar or other non-oxidizing gas, or the atmosphere of a gas generated upon decomposition of anhydrous copper formate. In a preferred batch process, it is ensured that the decomposition atmosphere consists entirely of the gas which is produced when the copper formate powder is decomposed, for example by making the volume of the heating zone small. In a preferred continuous process, the same effect is achieved by making the open spaces of the inlet to and the outlet from the heating zone small. These modifications are advantageous because they eliminate the need to previously provide a system for creating an N 2, H 2, or other non-oxidizing gas atmosphere.

In the above-described thermal decomposition method of the present invention, the thermal decomposition proceeds progressively from the outer part of the anhydrous copper formate to its inner part. The copper powder formed upon decomposition reaches the predetermined temperature at which the decomposition atmosphere is maintained in a short period of time because of the excellent thermal conductivity of copper powder, and the copper powder becomes copper formate vapor (copper (I) formate) at that temperature Formed copper formate, and also formic acid gas, which is formed in the decomposition, and exposed to gases of the decomposition products of formic acid. In this way, a copper powder produced in the initial stage of the process is exposed to these gases at the predetermined temperature throughout the thermal decomposition. When the thermal decomposition temperature exceeds 300 ° C, the copper powder disadvantageously tends to form agglomerates, and secondary decomposition tends to occur, ie, decomposition of formic acid formed upon decomposition of the anhydrous copper formate, which is unfavorable leads to the formation of water. However, when substantially all of the anhydrous copper formate has been decomposed, the temperature of the atmosphere may be raised above 300 ° C, as long as the exposure to such a high temperature is short-lived, even though the copper powder is higher for a limited period of time exposed to 300 ° C, the tendency of the powder to form agglomerates is not increased so much. On the other hand, if the thermal decomposition temperature is lower than 150 ° C, the decomposition unfavorably proceeds at an insufficient speed and takes much time. The more preferred range of thermal decomposition temperature is between 160 and 250 ° C, which range is near the lower limit of the 150-300 ° C range.

The copper powder produced by the above-described method of the present invention is generally a fine copper powder having an average primary particle diameter between 0,2 and 1 μm, a specific surface area between 5 and 0,5 m² / g, and a low tendency to agglomerate. The salient feature of the fine copper powder obtained by the thermal decomposition of anhydrous copper formate according to the present invention is that the powder has little tendency to agglomerate as compared with the copper powders prepared by the reduction method and other conventional methods Has.

As compared with the copper powders obtained by the reduction method and the like, the fine copper powder produced by the method of the present invention is more slowly oxidized in the air. Therefore, even if the fine copper powder according to the present invention is left in the air, no color change caused by oxidation takes place unless the duration of exposure is short. Since the produced fine copper powder contains impurity elements which were originally contained in the anhydrous copper formate powder which was expected to be present, and most of which adhere to the surface of the powder particles, it is preferred that the fine copper powder be mixed with water, an organic solvent or an organic solvent Solution of a rust inhibitor for copper in water or in an organic solvent is washed to reduce the impurity elements, such as halogens, sulfur, alkali metals and heavy metals. By such a washing treatment, for example, 90% or more of the alkali metals and halogens present as impurity elements may be removed, though depending on the amount of these impurity elements.

In a preferred washing treatment, water or an organic solvent such as an alcohol each containing an inhibitor or the like is used as a washing liquid in a single-stage washing or in the final stage of a multi-stage washing, and during washing, an ultrasonic dispersion treatment, a dispersion treatment with a Mixer or something similar done. This method is advantageous because it can achieve the reduction of impurity elements, a rust prevention treatment and the redispersion of agglomerated particles.

As apparent from the above description and as will be shown by the following Examples and Comparative Examples, the method of producing a fine copper powder by the thermal decomposition of anhydrous copper formate according to the present invention can provide a fine copper powder due to the use of the special anhydrous copper formate which has a small primary particle diameter and a low tendency to agglomerate. This particular anhydrous copper formate can be easily produced industrially at a low cost from a cheaper copper compound, and in this case, impurities contained in the starting material can be easily reduced.

Therefore, the present invention, which provides a practical and novel process for the industrial production of fine copper powder, is of considerable importance.

The present invention will be explained in more detail with reference to the following examples and comparative examples, but the examples should not be construed as limiting the scope of the invention. In these examples, unless otherwise stated, all parts and percentages are based on weight.

Example 1

1 kg of a 3 percent aqueous formic acid solution were added to 2 kg of basic copper carbonate (= CUCO 2 Cu (OH) 2,4 H 40 O). The resulting mixture was heated to 80 ° C and kept at that temperature for 30 minutes while the mixture was stirred. The water was then removed by evaporation at 80 ° C under reduced pressure to concentrate and dry the reaction product, whereby 1,28 kg of crystals of anhydrous copper formate were obtained. The thermal decomposition properties of this anhydrous copper formate were tested by adding 10 mg of the anhydrous copper formate in a nitrogen or hydrogen gas atmosphere at a heating rate of 3 ° C / min. were heated. As a result, it was found that the proportion of components which had decomposed in the temperature range of 160 to 200 ° C (hereinafter referred to as "thermal decomposition degree") was practically 100%.

The crystals of the anhydrous copper formate obtained above were pulverized into a powder having a particle size of 150 μm (100 mesh) or finer, and 1 kg of the powder was packed in a can measuring 15 cm x 15 cm x 8 cm (height). This rifle was placed in an electric oven with a capacity of 3 liters, in which the atmosphere had been replaced by nitrogen. The temperature in the electric furnace was measured at a rate of 4 ° C / min. and then the temperature was held at 200 ° C for 1,5 hours to carry out the thermal decomposition. After the electric furnace was cooled to room temperature, the can was taken out and 414 g of a thermally decomposed product powder showing a copper color was obtained.

This powder was a fine copper powder having an oxygen content of 0,4% or less, consisting of nearly spherical primary particles uniform in size and having an average particle diameter of about 0,3 μm, and having a specific surface area of ​​3 m² / g would have.

To 0,1 g of fine copper powder obtained above, 0,3 g of a surfactant (sorbitan fatty acid ester, "LEODOL", a product of Kao Corporation) and 150 g of water were added, and this mixture was subjected to ultrasonic dispersion treatment. Thereafter, the obtained dispersion was analyzed for agglomerate particle diameter by means of a laser type particle size distribution analyzer. As a result, it was found that the agglomerate particle diameter (on the average) was about 3 µm.

Example 2

With the exceptions that 0,66 kg of cupric oxide powder and 2,4 kg of 80-percent formic acid solution were used as starting materials and that the starting materials were mixed and stirred at 80 ° C 20 for hours, anhydrous copper formate crystals in an amount of 1,28 kg in same way as in example 1. The degree of thermal decomposition of the thus obtained anhydrous copper formate was practically 100%.

The crystals of the anhydrous copper formate obtained above were pulverized into a powder having a particle size of 150 μm (100 mesh) or finer, and using 1 kg of the powder, except that the powder was kept at 300 ° C for one hour thermal decomposition in the same manner as in Example 1. In this way, 414 g of a powder which was the product of thermal decomposition was obtained.

This powder was a fine copper powder consisting of nearly spherical primary particles uniform in size and having a uniform particle diameter of about 0,4 μm and having a specific surface area of ​​2 m² / g. The agglomerate particle diameter of the powder was measured (on average) after the powder was dispersed in water by the treatment with a mixer, and found to be about 8 μm.

Comparative Example 1

To 0,66 kg of cupric oxide powder, 2,4 kg of 16-percent aqueous formic acid solution was added. The resulting mixture was heated to 80 ° C for three hours, and the water was then removed by evaporation at 100 ° C at reduced pressure to concentrate and dry the reaction product to give 1,2 kg of anhydrous copper formate crystals. The degree of thermal decomposition of this anhydrous copper formate was 85%. The crystals thus obtained were dissolved in water to determine the content of water-insoluble components, and the content was found to be 15%. The water-insoluble components were analyzed by X-ray diffractometry and found to have a composition corresponding to an approximately 1: 1 mixture of unreacted cupric oxide and basic copper formate.

The anhydrous copper formate crystals obtained above were subjected to thermal decomposition in the same manner as in Example 2 and then cooled to room temperature.

The powder thus obtained, which was the product of thermal decomposition, showed a brown color, had an oxygen content of about 3%, and consisted of uniform nearly spherical primary particles having an average particle diameter of about 0,3 μm. The agglomerate particle diameter of the powder was measured (on average) after the powder was dispersed in water by the treatment with a mixer, and found to be about 15 μm.

Comparative Example 2

Using the same anhydrous copper formate powder as used in Comparative Example 1, thermal decomposition was carried out in the same manner as in Comparative Example 1 except that the thermal decomposition was effected while allowing hydrogen gas to flow into the vessel containing the starting material ,

The powder thus obtained, which was the product of thermal decomposition, showed a copper color and consisted of uniform nearly spherical primary particles having an average particle diameter of about 0,3 μm. However, the powder became brown within a relatively short time. In addition, the agglomerate particle diameter of the powder was measured (on average) after the powder was dispersed in water by the treatment with a mixer, and found to be about 20 μm.

Examples 3 and 4 and comparative examples 3 and 4

To 1,62 kg of copper hydroxide powder was added 4,8 kg of 80-percent aqueous formic acid solution, and this mixture was stirred for one hour. By filtration of the obtained mixture, copper formate tetrahydrate was obtained, which was then dehydrated at 100 ° C in vacuo to obtain anhydrous copper formate.

Using the anhydrous copper formate obtained above, with the exceptions that the powder particle size and thermal decomposition conditions for each starting powder were as shown in Table 2, copper powder was obtained by the procedure used in Example 1. The results obtained are shown in Table 2.

Table 2

Example Comparative example Particle size of the anhydrous copper formate (mesh) µm Conditions of thermal decomposition: - Temperature - Duration (hours) Produced Cu powder - Primary particle ∅ (µm) - Specific surface area (m² / g) - Agglomerate particles ∅ (µm)

Example 5

Five types of anhydrous copper formate, each having impurity contents as shown in Table 3, were used as starting material except for basic copper carbonates which were different in their Na, Cl and S contents same way as in example 1. The anhydrous copper formates were thermally decomposed in the same manner as in Example 1 to obtain copper powders.

Each of the copper powders thus obtained was washed in the same manner as shown in Table 3 to obtain a copper powder having a greatly improved purity. The results obtained are shown in Table 3.

Table 3

Impurities in the anhydrous copper formate (ppm) impurities in the produced Cu powder (ppm) washing liquids and technology impurities in the washed Cu powder (ppm)

The washing liquids and the washing technique for each copper powder shown in the table 3 are as follows.

Washing liquids:

1: 0,5-percent benzotriazole solution in water.

2: water.

3: 0,5 percent benzotriazole solution in methanol.

4: methanol.

Washing Technology:

For a wash operation, 100 ml of a wash was used per 20 g of copper powder

and stirring or ultrasonic treatment (indicated by *) was performed for ten minutes. In cases where a washing operation has been repeated, the number of repeated washing operations is shown in the table after 'x' (e.g. 'x9' means 'washed nine times').

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the claims.

Claim [en]

1. A method for producing a fine copper powder which includes solid phase thermal decomposition of an anhydrous copper formate in a non-oxidizing atmosphere at a temperature in the range between 150 and 300 ° C to obtain a fine copper powder having a primary particle diameter of 0,2 to 1 μm, a specific one Surface of 5 to 0,5 m² / g and having a low tendency to agglomerate, said anhydrous copper formate being an anhydrous copper formate powder having a particle diameter of 20 mesh or finer and 90 by weight or more within a temperature range between 160 and 200 ° C undergoes thermal decomposition when the anhydrous copper formate powder is heated in a nitrogen or hydrogen gas atmosphere at a heating rate of 3 ° C / min. and said anhydrous copper formate powder is obtained by dehydrating copper formate hydrate at a temperature of 130 ° C or less and then pulverizing the anhydrous copper formate, or by at least one copper compound selected from the group consisting of copper carbonate, copper hydroxide and copper oxide is reacted with formic acid or methyl formate.

2. A method as claimed in claim 1, wherein said fine copper powder contains agglomerates of fine copper powder primary particles, wherein the diameter of said agglomerates is 10 μm or less.

3. A method as claimed in claim 1 for producing a purified fine copper powder which comprises washing the fine copper powder obtained by the method claimed in claim 1 with water, an organic solvent or a solution of a rust inhibitor for copper in water or in an organic Solvent so as to reduce in said powder at least one impurity element selected from the group consisting of halogens, sulfur, alkali metals and heavy metals.

Source: www.patent-de.com

Patent owner: Mitsubishi Gas Chemical Co., Inc. Tokyo, Japan

Document: DE69024884T2

Further links to ultrafine copper powder:

Price for ultra-fine copper powder -> prices for high-purity metals

 

Do you have questions about our services?
We will advise you by phone. Make an appointment with us and use the contact form.
Go to the contact form