TW201419322A - Non-corrosive soft-magnetic powder - Google Patents

Abstract

The invention concerns a process for coating soft-magnetic powder, which comprises the step of treating the soft-magnetic powder with a solution containing: (A) at least one inhibitor, which is a 5- to 12-membred heterocyclic compound containing at least one substituted or unsubstituted ring-nitrogen atom and at least one ring-carbon atom, wherein one ring atom is substituted with C2 - C28 alkyl, C2 - C28 alkenyl or C2 - C28 alkynyl; and optionally (B) at least one inhibitor, which is a compound with general formula (I), wherein R1 indicates C2 - C28 alkyl, C2 - C28 alkenyl or C2 - C28 alkynyl; R2 and R3 independently of each other indicate H, C1 - C6 alkyl, C2 - C6 alkenyl, C1 - C6 alkynyl, C3 - C7 cycloalkyl or C6 - C12 aryl. The invention further relates to a soft-magnetic powder containing inhibitors of class (A) and class (B), use of such powder as well as an electronic component comprising such powder.

Description

Non-corrosive soft magnetic powder

This invention relates to a process for preparing non-corrosive soft magnetic powders. The invention further relates to the products produced by the process and to the use of the soft magnetic powder.

Iron-based powders have long been used as the base material in the manufacture of electronic components. Other applications for such powders include metal injection molded parts, powder metallurgy, and various specialty products such as food supplements.

Popular applications for soft magnetic powders include magnetic core components that are used as magnetic materials with high magnetic permeability for use in electrical, electromechanical, and magnetic devices (eg, electromagnets, transformers, electric motors, inductors, and magnetic assemblies). Limit and direct the magnetic field. These components are typically produced in different shapes and sizes by molding soft magnetic powder under high pressure in a mold.

In electronic applications, especially in alternating current (AC) applications, two key features of the magnetic core component are magnetic permeability and core loss characteristics. In this context, the magnetic permeability of a material provides an indication of its ability to become magnetized or its ability to carry magnetic flux. The magnetic permeability is defined as the ratio of the induced magnetic flux to the magnetizing force or the magnetic field strength. When the magnetic material is exposed to a rapidly changing magnetic field, the total energy of the core is reduced by hysteresis losses and/or eddy current losses. Hysteresis losses are caused by the necessary energy consumption to overcome the magnetic forces retained within the core components. Eddy current losses are caused by currents in the core components due to flux changes due to AC conditions, and which essentially result in resistive losses.

Typically, devices for high frequency applications are sensitive to core losses, and to reduce losses due to eddy currents, improved insulation properties are desirable. The easiest way to achieve this is to thicken The insulating layer of each particle. In addition, rust has been found to reduce electrical resistance and the rust inhibitor layer can reduce these losses. However, the thicker the insulating layer, the lower the core density of the obtained soft magnetic particles and the lower the magnetic flux density. In addition, attempts to increase the magnetic flux density by performing compression molding under high pressure can make the strain in the core larger, and thus make the hysteresis loss higher.

In order to produce a soft magnetic powder core with the best key characteristics, it is necessary to simultaneously increase the resistivity and density of the core. For this reason, the particles should ideally be covered by a thin insulating layer with high insulating properties. In the field of magnetic powders, there are different ways to solve this problem.

WO 2007/084 363 A2 relates to a process for preparing a metallurgical powder composition and a compacted article produced therefrom. The metallurgical powder composition comprises a base metal powder that is at least partially coated with a metal phosphate and a particulate internal lubricant. Internal lubricants used include (e.g.) polyamides, C ₅ to C ₃₀ fatty acid, metal salts of polyamides, C ₅ to C ₃₀ fatty acid metal salt of, C ₅ to C ₃₀ fatty acid is an ammonium salt, stearate Lithium, zinc stearate, magnesium stearate, calcium stearate, ethylene bis-lipidamine, polyethylene wax, polyolefin, and combinations thereof. The combination of a phosphate coating and an internal lubricant increases the lubricity of the metal particles and the compression members while reducing the amount of organic compounds present.

EP 0 810 615 B1 describes a soft magnetic powder composite core comprising particles having an insulating layer. Specifically, the soft magnetic particles are treated by a solution containing a phosphorylation solution containing a solvent and a phosphate. Further, the solution contains a surfactant and a rust inhibitor, and the rust inhibitor contains an organic compound having a nitrogen and/or sulfur of a lone pair of electrons and suppressing formation of an iron oxide.

EP 0 765 199 B1 discloses mixing a powder composition based on iron particles with a thermoplastic material and a lubricant selected from the group consisting of stearates, waxes, paraffins, natural and synthetic fat derivatives and Polyamine type oligomer. The obtained mixture is compacted at a temperature lower than the glass transition temperature or melting point of the thermoplastic resin, and the compacted product is heated to cure the thermoplastic resin. By adding a lubricant to the thermoplastic material, the process consumes less time, but the necessary improvement in soft magnetic properties cannot be achieved.

In addition, in the field of metal working, especially metal surface structures, different insulating layers are used to eliminate corrosion. For example, CN 101 525 563 A relates to a post-polishing detergent comprising a corrosion inhibitor for protecting the surface of the treated object from corrosion when performing a chemical mechanical polishing cleaning. CN 100 588 743 A discloses an acid solution for treating the surface of a magnesium alloy comprising two acids, a corrosion inhibitor and a wetting agent for activating the surface of the magnesium alloy to form a compact film.

US 5,415,805 A describes compositions and methods for inhibiting corrosion of iron and ferrous metals in sulfur ore. The composition comprises an aqueous solution of an alcohol, an acid, a fatty imidazoline and an ethoxylated fatty diamine, and an aqueous solution of a molybdate compound or a salt thereof.

Known processes for forming an insulating layer on magnetic particles are typically directed to one of the key features (i.e., density or insulating properties) while leaving the other constant. Therefore, the available resistivity and permeability are limited. Accordingly, there is still a need in the art to further improve processes for treating soft magnetic powders to achieve optimal results from magnetic core components prepared from such powders.

Accordingly, it is an object of the present invention to provide a process for coating soft magnetic powders and corresponding soft magnetic powders which are advantageous for achieving high resistivity, high magnetic permeability and non-corrosive properties when used in magnetic core components. Moreover, it is an object of the present invention to provide a process that allows for the above objectives to be achieved in a simple, cost effective and uncomplicated manner. Another object of the present invention is to provide an electronic component comprising soft magnetic powder that does not require additional corrosion protection. In this context, it is an object of the present invention to provide a soft magnetic powder that permits the creation of electronic components without other corrosion protection layers.

The objects are achieved by a process for applying a soft magnetic powder, the process comprising the step of treating the soft magnetic powder with a solution comprising:

(A) at least one first inhibitor which contains at least one substituted or unsubstituted ring nitrogen atom and at least one ring carbon atom from 5 to 12 members, preferably from 5 to 9 members, particularly preferably a 5- to 7-membered heterocyclic compound wherein one ring atom, preferably one ring carbon atom, is substituted by a C ₂ -C ₂₈ alkyl group, a C ₂ -C ₂₈ alkenyl group or a C ₂ -C ₂₈ alkynyl group. Preferably, C ₈ -C ₂₆ alkyl, C ₈ -C ₂₆ alkenyl or C ₈ -C ₂₆ alkynyl, more preferably C ₁₂ -C ₂₂ alkyl, C ₁₂ -C ₂₂ alkenyl or C ₁₂ - C ₂₂ alkynyl and most preferably C ₁₄ -C ₁₈ alkyl, C ₁₄ -C ₁₈ alkenyl or C ₁₄ -C ₁₈ alkynyl; and optionally

(B) at least one second inhibitor having a compound of the formula (I),

Wherein R ^{1 represents} C ₂ -C ₂₈ alkyl, C ₂ -C ₂₈ alkenyl or C ₂ -C ₂₈ alkynyl, preferably C ₈ -C ₂₆ alkyl, C ₈ -C ₂₆ alkenyl or C ₈ - C ₂₆ alkynyl, more preferably C ₁₂ -C ₂₂ alkyl, C ₁₂ -C ₂₂ alkenyl or C ₁₂ -C ₂₂ alkynyl and most preferably C ₁₄ -C ₁₈ alkyl, C ₁₄ -C ₁₈ alkenyl Or a C ₁₄ -C ₁₈ alkynyl group; R ² and R ³ independently of each other represent H, C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₁ -C ₆ alkynyl, C ₃ -C ₇ ring Alkyl or C ₆ -C ₁₂ aryl.

For the purposes of the present invention, -COOH also includes carboxylates, which preferably have carboxylic acid functional groups (particularly metal carboxylates), carboxylate functional groups or derivatives of carboxamide functional groups. . These include, for example, esters formed with C ₁ -C ₄ -alkanols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, second butanol, and third butanol.

The present invention further relates to a soft magnetic powder obtained by the above process for a soft magnetic powder containing at least one first inhibitor of the class (A) specified above and at least one second inhibitor of the class (B) as specified above. Powder and the use of the powder in electronic components. The following description relates to the processes and products set forth in the present invention. In particular, preferred embodiments of the inhibitor classes (A) and (B), the inhibitor composition and the soft magnetic powder are suitable for the treatment of soft magnetic powders and similar treated soft magnetic powders.

The present invention also relates to the treatment of soft magnetic powders for use in the manufacture of electrical devices, electromechanical devices. The use of electronic components, in particular magnetic core components, used in magnetic devices such as electromagnets, transformers, electric motors, inductors and magnetic assemblies. Other uses for coated soft magnetic powders include the manufacture of radio frequency identification (RFID) tags and the fabrication of components that reflect or shield electromagnetic radiation.

The present invention provides a process for coating soft magnetic powders and corresponding processed powders which are optimally suited for the manufacture of electronic components. In particular, soft magnetic powders coated in accordance with the present invention allow for high resistivity, high magnetic permeability, and non-corrosive properties to be achieved when used in the manufacture of electronic components, such as magnetic core components. The invention further allows flexibility to adjust this feature by varying the treatment solution and the amount of inhibitor used therein. In addition, due to the simple and uncomplicated manner of the proposed method, high batch-to-batch consistency can be achieved, which in turn allows for reliable generation of electronic components. In general, the soft magnetic powder coated in accordance with the present invention facilitates the fabrication of electronic components having unique electromagnetic performance characteristics. In addition, electronic components comprising soft magnetic powder coated in accordance with the present invention do not require additional layers for corrosion protection, thereby saving space and production costs.

The soft magnetic powder of the present invention comprises a plurality of particles composed of a soft magnetic material. The powders comprise particles having an average size between 0.5 μm and 250 μm, preferably between 2 μm and 150 μm, more preferably between 2 μm and 10 μm. The shape of the particles can vary. In terms of shape, there may be many variations known to those skilled in the art. The shape of the powder particles can be, for example, a needle shape, a cylindrical shape, a plate shape, a teardrop shape, a flat shape, or a spherical shape. Soft magnetic particles of various particle shapes are commercially available. Preferred are spherical shapes because the particles are easier to apply, which is actually more effective for electrical insulation.

As the soft magnetic material, an elemental metal, an alloy or a mixture of one or more elemental metals and one or more alloys may be employed. Typical elemental metals include Fe, Co, and Ni. The alloy may include an alloy based on Fe, such as Fe-Si alloy, Fe-Si-Cr alloy, Fe-Si-Ni-Cr alloy, Fe-Al alloy, Fe-N alloy, Fe-Ni alloy, Fe-C alloy, Fe-B alloy, Fe-Co alloy, Fe-P alloy, Fe-Ni-Co alloy, Fe-Cr alloy, Fe-Mn alloy, Fe-Al-Si Gold and ferrite, or alloys based on rare earth Fe, such as Nd-Fe-B alloy, Sn-Fe-N alloy, Sm-Co alloy, Sm-Co-Fe-Cu-Zr alloy, and Sr-ferrite. In a preferred embodiment, Fe or an alloy based on Fe (Fe-Si-Cr, Fe-Si or Fe-Al-Si) acts as a soft magnetic material.

In a particularly preferred embodiment, Fe acts as a soft magnetic material and the soft magnetic powder is a carbonyl iron powder. The carbonyl iron can be obtained by thermally decomposing iron pentacarbonyl in the gas phase according to known processes, for example, Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A14, page 599 or DE 3 428 121 or DE 3 940, 347 illustrated, and which contains in particular the pure metallic iron.

The carbonyl iron powder is a gray fine powder of metallic iron having a low content of a minor component and consisting essentially of spherical particles having an average particle diameter of at most 10 μm. Preferred in the context of the invention is an iron content of the unreduced carbonyl iron powder of >97% by weight (here based on the total weight of the powder), a carbon content of <1.5% by weight, a nitrogen content of <1.5% by weight, and an oxygen content of <1.5% by weight. %. The iron content of the reduced carbonyl iron powder which is particularly preferred in the process of the present invention is >99.5% by weight (here based on the total weight of the powder), the carbon content is <0.1% by weight, the nitrogen content is <0.01% by weight, and the oxygen content is <0.5. weight%. The average diameter of the powder particles is preferably from 1 μm to 10 μm and the specific surface area (BET of the powder particles) is preferably from 0.2 m ² /g to 2.5 m ² /g.

In another embodiment of the invention, the soft magnetic powder is pretreated, preferably phosphorylated. Phosphorylation can include coating a soft magnetic material with an insulating amorphous compound such as phosphoric acid or a salt thereof with at least one element selected from the group consisting of Al, Si, Mg, Y, Ca, B, Zr, and Fe. These materials are particularly suitable for pretreating particles of soft magnetic powders because they provide moderately good insulating properties and allow the metal to be sufficiently coupled to organic compounds. In addition, the surface of the powder particles is prepared by pretreatment so that the inhibitor contained in the solution is more likely to adhere.

The average thickness of the coating derived from the pretreatment may be between 1 nm and 1 μm, preferably between 1 nm and 50 nm. Further, the amount of the coating relative to the soft magnetic material is not more than 4% by weight, and therefore, the magnetic flux density of the magnetic core obtained by molding the soft magnetic powder can be prevented The degree is significantly reduced.

A method of pretreating soft magnetic particles includes mixing a soft magnetic powder with phosphoric acid or a salt thereof, optionally mixing an organic solvent. Those skilled in the art can select the appropriate time and appropriate temperature conditions to form the iron phosphate layer. The pretreatment can be carried out, for example, at room temperature for a period of from 10 minutes to 10 hours. Then, the dry powder can be formed by evaporating the solvent at an elevated temperature. After phosphorylation, the phosphor content typically varies between 0.01% and 1% by weight of the dry powder, preferably between 0.02% and 1% by weight.

According to the invention, at least one first inhibitor of class (A) contains from 5 to 12 members, preferably from 5 to 9 members, of at least one substituted or unsubstituted ring nitrogen atom and at least one ring carbon atom. More preferably, a 5- to 7-membered heterocyclic compound wherein one ring atom, preferably one ring carbon atom, is substituted by a C ₂ -C ₂₈ alkyl group, a C ₂ -C ₂₈ alkenyl group or a C ₂ - C ₂₈ alkynyl, preferably C ₈ -C ₂₆ alkyl, C ₈ -C ₂₆ alkenyl or C ₈ -C ₂₆ alkynyl, more preferably C ₁₂ -C ₂₂ alkyl, C ₁₂ -C ₂₂ alkenyl Or a C ₁₂ -C ₂₂ alkynyl group and most preferably a C ₁₄ -C ₁₈ alkyl group, a C ₁₄ -C ₁₈ alkenyl group or a C ₁₄ -C ₁₈ alkynyl group.

Preferred heterocyclic compounds are imidazole, imidazoline, imidazolium, benzimidazole, benzimidazoline, benzimidazole, thiazole, thiazoline, thiazole, benzothiazole, benzothiazoline, benzothiazole, Oxazole, oxazoline, oxazolidine, benzoxazole, benzoxazoline, benzoxazole, pyridine, collidine, pyrimidine, triazole, benzotriazole, triazoline Or tetrazole. More preferably, the heterocyclic ring is imidazole, imidazoline, imidazolium, benzimidazole, benzimidazoline or benzimidazole. The most preferred heterocyclic ring is imidazole, imidazoline, imidazolium.

In one embodiment, the ring nitrogen atom may be substituted with a monovalent straight chain or a branched carbon chain R _chain having 2 to 10, preferably 2 to 6 carbon atoms, wherein the chain is via the groups NH ₂ , OH , at least one of OR _Y , OC(O)R _Y , OC(O)R _Z , COOH, CO ₂ R _Y is substituted,

Wherein R _Y means a monovalent straight chain or a branched chain comprising from 1 to 10 carbon atoms, wherein R _Y may also be substituted by one or more substituents selected from the group consisting of R _Y , R _Z , F, Cl, Br, I, OH, CN, NO ₂ , CF ₃ , NH ₂ , NHR _Y , NHR _Z , NO ₂ , CO ₂ H, CO ₂ R _Y , CO ₂ R _Z , CO ₂ NH ₂ , SH, SO ₃ H, SO ₂ NH ₂ , CHO, COCH ₃ , CH ₂ OH,

Wherein R _Z means an aromatic hydrocarbon group having 6 to 8 ring carbons, wherein R _Z may also be substituted with one or more substituents selected from the group consisting of R _Y , F, Cl, Br, I, CN , NO ₂ , CF ₃ , NH ₂ , NHR _Y , NO ₂ , CO ₂ H, CO ₂ R _Y , CO ₂ NH ₂ , SH, SO ₃ H, SO ₂ NH ₂ , CHO, COCH ₃ , CH ₂ OH.

Preferably, R _Y means methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, t-butyl, n-pentyl, isopentyl, 1- Methyl butyl, third pentyl, neopentyl, n-hexyl, 3-hexyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl , 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2-methyl-3-pentyl, 3-methyl-3-pentyl 2,2-Dimethyl-1-butyl, 2,3-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, 2,3-Dimethyl-2-butyl, 3,3-dimethyl-2-butyl, n-heptyl, n-octyl, 1-methylheptyl, 2-ethylhexyl, 2,4 , 4-trimethyl-pentyl, 1,1,3,3-tetramethylbutyl, n-decyl, n-decyl, n-undecyl, n-dodecyl.

R _{Z is} preferably unsubstituted or substituted phenyl, naphthyl, anthryl, phenanthryl, fused tetraphenyl, 1,2-benzophenanthrenyl, anthracenyl, and particularly preferably phenyl or Naphthyl.

Substituted R _Z is, for example, 2-methylphenyl, 3-methylphenyl and 4-methylphenyl; 2,4-dimethylphenyl, 2,5-dimethylphenyl, 3,5-Dimethylphenyl and 2,6-dimethylphenyl; 2,4,6-trimethylphenyl; 2-ethylphenyl, 3-ethylphenyl and 4-ethyl Phenyl; 2,4-diethylphenyl, 2,5-diethylphenyl, 3,5-diethylphenyl and 2,6-diethylphenyl; 2,4,6-tri Ethylphenyl; 2-propylphenyl, 3-propylphenyl and 4-propylphenyl; 2,4-dipropylphenyl, 2,5-dipropylphenyl, 3,5- Dipropylphenyl and 2,6-dipropylphenyl; 2,4,6-tripropylphenyl; 2-isopropylphenyl, 3-isopropylphenyl and 4-isopropylbenzene 2,4-diisopropylphenyl, 2,5-diisopropylphenyl, 3,5-diisopropylphenyl and 2,6-diisopropylphenyl; 2,4, 6-triisopropylphenyl; 2-butylphenyl, 3-butylphenyl and 4-butylphenyl; 2,4-dibutylphenyl, 2,5-dibutylphenyl, 3,5-dibutylphenyl and 2,6-dibutylphenyl; 2,4,6-tributylphenyl; 2-isobutylphenyl, 3-isobutylphenyl and 4- Isobutylphenyl; 2,4-diisobutylphenyl, 2,5-diisobutylphenyl, 3,5-diisobutylphenyl 2,6-diisobutylphenyl; 2,4,6-triisobutylphenyl; 2-second butylphenyl, 3-secondbutylphenyl and 4-secondbutylphenyl 2,4-di-second butylphenyl, 2,5-di-second butylphenyl, 3,5-di-second butylphenyl and 2,6-di-second butyl Phenyl; 2,4,6-tri-t-butylphenyl; 2-tert-butylphenyl, 3-tert-butylphenyl and 4-tert-butylphenyl; 2,4-di -T-butylphenyl, 2,5-di-t-butylphenyl, 3,5-di-t-butylphenyl and 2,6-di-t-butylphenyl; 2,4 , 6-tri-t-butylphenyl; and 2-dodecylphenyl, 3-dodecylphenyl, 4-dodecylphenyl; 2-methoxyphenyl, 3- Methoxyphenyl and 4-methoxyphenyl; 2,4-dimethoxyphenyl, 2,5-dimethoxyphenyl, 3,5-dimethoxyphenyl and 2,6 -dimethoxyphenyl; 2,4,6-trimethoxyphenyl; 2-ethoxyphenyl, 3-ethoxyphenyl and 4-ethoxyphenyl; 2,4-diethyl Oxyphenyl, 2,5-diethoxyphenyl, 3,5-diethoxyphenyl and 2,6-diethoxyphenyl; 2,4,6-triethoxyphenyl ; 2-propoxyphenyl, 3-propoxyphenyl and 4-propoxyphenyl; 2,4-di Propoxyphenyl, 2,5-dipropoxyphenyl, 3,5-dipropoxyphenyl and 2,6-dipropoxyphenyl; 2-isopropoxyphenyl, 3- Isopropoxyphenyl and 4-isopropoxyphenyl; 2,4-diisopropoxyphenyl, 2,5-diisopropoxyphenyl, 3,5-diisopropoxybenzene And 2,6-diisopropoxyphenyl; 2-butoxyphenyl, 3-butoxyphenyl and 4-butoxyphenyl; 2-hexyloxyphenyl, 3-hexyloxy Phenylphenyl, 4-hexyloxyphenyl; 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl; 2,4-dichlorophenyl, 2,5-dichlorophenyl, 3, 5-dichlorophenyl and 2,6-dichlorophenyl; trichlorophenyl; 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl; 2,4-difluorophenyl, 2, 5-difluorophenyl, 3,5-difluorophenyl and 2,6-difluorophenyl; trifluorophenyl, such as 2,4,6-trifluorophenyl, tetrafluorophenyl, pentafluorobenzene 2-cyanophenyl, 3-cyanophenyl and 4-cyanophenyl; 2-nitrophenyl, 4-nitrophenyl, 2,4-dinitrophenyl, 2,6 -dinitrophenyl; 4-dimethylaminophenyl; 4-ethenylphenyl; methoxyethylphenyl, ethoxymethylphenyl.

Preferably, the R _chain is a monovalent straight or branched carbon chain having from 2 to 10 carbon atoms, wherein the chain is via the group -OH (eg 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxyl) Propyl, 3-hydroxybutyl, 4-hydroxybutyl, 2-hydroxy-2,2-dimethylethyl, 5-hydroxy-3-oxapentyl, 6-hydroxyhexyl, 7-hydroxy-4 At least one of -oxaheptyl, 8-hydroxy-4-oxaoctyl, 8-hydroxy-3,6-dioxaoctyl, and the like is substituted.

Preferably, the R _chain is a monovalent straight or branched carbon chain having from 2 to 10 carbon atoms, wherein the chain is via a group -COOH (eg, carboxymethyl, 2-carboxyethyl, 3-carboxypropyl) , 4-carboxybutyl, 5-carboxypentyl, 6-carboxyhexyl, 7-carboxyheptyl, 8-carboxyoctyl, 9-carboxymethyl, 10-carboxymethyl, 12-carboxydodecyl and At least one of 14-carboxytetradecyl) is substituted.

Preferably, the R _chain is a monovalent straight or branched carbon chain having from 2 to 10 carbon atoms, wherein the chain is via an amine group (eg 2-aminoethyl, 2-aminopropyl, 3-amine) At least one of a propyl group, a 4-aminobutyl group, a 6-aminohexyl group, and the like is substituted.

The heterocyclic compound, in particular at least one carbocyclic atom, is optionally substituted by the following groups: H, C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₁ -C ₆ alkynyl, C ₃ -C ₇ A cycloalkyl group or a C ₆ -C ₁₂ aryl group, preferably a C ₁ -C ₆ alkyl group and more preferably a methyl group.

In a preferred embodiment of the invention, the compound of formula (I) is derived from a fatty acid. In this context, the fatty acid may be saturated or unsaturated, preferably unsaturated, and may be selected from the group consisting of: myristic acid, palmitoleic acid, cis-6-hexadecene Acid, oleic acid, oleic acid, trans-11-octadecenoic acid, linoleic acid, trans linoleic acid, alpha-linolenic acid, peanut oleic acid, docosapentaenoic acid, sinapic acid , docosahexaenoic acid, octanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, tetracosic acid, and hexacylic acid. Preferred fatty acids are palmitoleic acid, oleic acid, linoleic acid, translinoleic acid, alpha-linolenic acid, lauric acid, palmitic acid, ricinoleic acid or stearic acid. Particularly preferred fatty acids have from 12 to 18 carbon atoms and from 1 to 4 double bonds in fatty acids such as oleic acid, lauric acid, ricinoleic acid and stearic acid.

In a preferred embodiment, at least one second inhibitor of class (A) is a compound of formula (II):

In formula (II), R ^{4 represents} C ₂ -C ₂₈ alkyl, C ₂ -C ₂₈ alkenyl or C ₂ -C ₂₈ alkynyl, preferably C ₈ -C ₂₆ alkyl, C ₈ -C ₂₆ Alkenyl or C ₈ -C ₂₆ alkynyl, more preferably C ₁₂ -C ₂₂ alkyl, C ₁₂ -C ₂₂ alkenyl or C ₁₂ -C ₂₂ alkynyl, and most preferably C ₁₄ -C ₁₈ alkyl, C ₁₄ -C ₁₈ alkenyl or C ₁₄ -C ₁₈ alkynyl.

Here, X can be selected from the group consisting of O, S, and NR ⁵ . In a preferred embodiment, X can be S or NR ⁵ , and in a more preferred embodiment, X is NR ⁵ .

In this context, R ⁵ denotes H, C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₁ -C ₆ alkynyl, C ₃ -C ₇ cycloalkyl or C ₆ -C ₁₂ aryl Preferably, H, optionally, a C ₁ -C ₆ alkyl group substituted with 1 or 2 substituents selected from the group consisting of OH, COOH or NH ₂ .

Further, the alkyl group in R ⁵ is optionally substituted with 1 to 3 substituents selected from the group consisting of F, Cl, Br, C, OH, C ₁ to C ₄ alkoxy, C ₆ to C ₁₀ aryl, CF ₃ , CN, NH ₂ .

R ⁶ and R ⁷ may be bonded via a single bond or a double bond and independently of each other to indicate H, C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₁ -C ₆ alkynyl, C ₃ -C ₇ ring Alkyl or C ₆ -C ₁₂ aryl. Preferably, R ⁶ and R ⁷ independently of each other indicate H, C ₁ to C ₆ alkyl, more preferably H or methyl.

In a preferred embodiment of the invention, the compound of formula (II) is derived from a fatty acid. In this context, the fatty acid may be saturated or unsaturated, preferably unsaturated, and may be selected from the group consisting of: myristic acid, palmitoleic acid, cis-6-hexadecenoic acid, Oleic acid, oleic acid, trans-11-octadecenoic acid, linoleic acid, trans-linolenic acid, α-linolenic acid, peanut oleic acid, docosapentaenoic acid, sinapic acid, two Docosahexaenoic acid, octanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, tetracosic acid, hexacylic acid. Preferred fatty acids are palmitoleic acid, oleic acid, linoleic acid, Trans linoleic acid, alpha-linolenic acid, lauric acid, palmitic acid, ricinoleic acid and stearic acid. Particularly preferred fatty acids have from 12 to 18 carbon atoms and from 1 to 4 double bonds in fatty acids such as oleic acid, lauric acid, ricinoleic acid and stearic acid.

In the context of the present specification, unless otherwise stated, % by weight (wt%) means the fraction of the total weight of the soft magnetic powder. For example, the solution for treating the soft magnetic powder includes the first inhibitor of the class (A) as specified above, the second inhibitor of the case (B) as appropriate, and optionally other components (for example, a solvent). Unless otherwise stated, wt% herein refers to the fraction of the total weight of the soft magnetic powder to be treated with the solution. Thus, the indicated wt% is based on the total weight of soft magnetic powder that does not include, for example, other components from the solution.

The solution utilized in the method of the present invention preferably contains at least one inhibitor of each of the categories (A) and (B) as specified above. In one embodiment, the solution contains at least one of the categories (A) of 0.05 wt% or more, preferably between 0.1 wt% and 1.0 wt%, and particularly preferably between 0.10 wt% and 0.8 wt%. The first inhibitor. Further, the solution may contain at least one second of the category (B) of 0.03 wt% or more, preferably between 0.05 wt% and 0.6 wt%, and particularly preferably between 0.1 wt% and 0.5 wt%. Inhibitor. The total fraction of inhibitors contained in the solution may vary between 0.05 wt% and 1 wt%, preferably between 0.1 wt% and 0.5 wt%.

The weight ratio of the inhibitor of category (A) to the inhibitor of class (B) may be between 0.5 and 10, preferably between 0.8 and 5, and particularly preferably between 1 and 3.

Additionally, the solution may contain a solvent. Particularly suitable solvents are water, acetone, acetic acid, acetonitrile, glycerol, hexane, methyl tert-butyl ether, propanol, benzene, ethanol or methanol. Examples of other suitable solvents are aromatic hydrocarbons such as toluene or xylene; alkyl esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate and 3 -methylbutanol; alkoxy alcohols such as methoxypropanol, methoxybutanol, ethoxypropanol; alkylbenzenes such as ethylbenzene, cumene; butanediol, butyl Diethylene glycol, alkyl glycol acetate, such as butanediol acetate and butyl diethylene glycol acetate; acetic acid 2- Methoxy-1-methylethyl ester, diethylene glycol dialkyl ether, diethylene glycol monoalkyl ether, dipropylene glycol dialkyl ether, dipropylene glycol monoalkyl ether, diethylene glycol alkyl Ether acetate, dipropylene glycol alkyl ether acetate, ethers such as dioxane and tetrahydrofuran, lactones such as butyrolactone; ketones such as acetone, 2-butanone, cyclohexanone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK); methyl phenol (o-cresol, m-cresol or p-cresol), pyrrolidone, such as N-methyl-2-pyrrolidone; dimethyl Formamide, also a mixture of two or more such solvents.

The solvent content of the solution may amount to a total of up to 50% by weight. Preferably, the solvent content is between 20% and 5% by weight.

The solution can be prepared by mixing at least one first inhibitor of the class (A) and at least one second inhibitor of the class (B) as appropriate with a solvent. The prepared solution can then be mixed with a soft magnetic powder. The method of mixing the components is not limited, and the mixing can be achieved by a mixer such as a stirring tank, a planetary mixer, a paddle mixer or a kneading machine. After mixing the soft magnetic powder and the solution including the solvent, the mixture may be heated to evaporate the solvent. In this way, a dried soft magnetic powder is obtained which comprises a non-corrosive thin coating.

The average thickness of the inhibitor coating can range from 0.5 nm to 20 nm. Further, the ratio of the inhibitor coating to the soft magnetic material is not higher than 0.1 and preferably not higher than 0.01. Therefore, the magnetic flux density of the magnetic core obtained by molding the soft magnetic powder can be prevented from being remarkably lowered.

The soft magnetic powder and the treated soft magnetic iron powder according to the above process are particularly suitable for the manufacture of electronic components. Electronic components such as magnetic cores can be obtained by, for example, compression molding or injection molding of soft magnetic powder. For the manufacture of such electronic components, soft magnetic powders are typically incorporated with one or more types of resins, such as epoxies, urethane resins, polyurethane resins, phenolic resins, amine resins, hydrazines. Resin, polyamide resin, polyimide resin, acrylic resin, polyester resin, polycarbonate resin, norbornene resin, styrene resin, polyether oxime resin, oxime resin, polyoxy siloxane resin, fluororesin , polybutadiene resin, vinyl ether resin, polyvinyl chloride resin or vinyl ester resin. mixing The method of the components is not limited, and the mixing can be achieved by a mixer such as a belt blender, a roller machine, a Nauta mixer, a Henschel mixer. Or high-speed mixers or kneading machines, for example, Banbury mixers, kneaders, rolls, kneader-ruders, paddle mixers, planetary mixers or single or twin axes Extruder.

The composition is used to produce a magnetic or magnetizable molding. A specific molding of this type is a coil core or bobbin used in electrical engineering. Coils with corresponding coil cores or bobbins are used in generators, laptops, small notebooks, mobile phones, electric motors, AC inverters, electronic components in the automotive industry, toys and the electronics industry (for example) Electromagnet. The composition can additionally be used to create a magnetic field concentrator.

To produce a molded article, the composition of the soft magnetic powder and the resin is heated and melted at the melting point of the resin, preferably the thermoplastic resin component, and then an electronic component, such as a magnetic core of a desired shape, is formed. Then, the composition was compressed in a mold to obtain a molded article. This compression produces a molded article having high strength.

Another method of producing a molded article comprises pressing a soft magnetic powder and a resin composition in a mold and at most 1000 MPa, preferably at most 500 MPa, with or without heating. After compression, the molding is cured.

Soft magnetic powders according to the above process or containing at least one first inhibitor of the class (A) and at least one second inhibitor of the class (B) as described above can be used for, for example, electrical devices, electromechanical devices and magnetic devices Electronic components used in (eg electromagnets, transformers, electric motors, inductors and magnetic assemblies), in particular magnetic core components, for the manufacture of radio frequency identification (RFID) tags and for the reflection or shielding of electromagnetics radiation.

Powder injection molding allows for the efficient and efficient production of complex metal parts. Powder injection molding generally involves pressing a soft magnetic powder together with a polymer as a binder into a desired shape, then removing the binder and pressing the powder into a solid metal part during the sintering stage. This applies in particular to carbonyl iron powders, because spherical iron particles can be extremely tight The ground is piled up together.

Soft magnetic powders may be employed in printed RFID structures in the production of RFID tags (radio frequency identification) for marking of rice targets for automatic target location or identification.

Finally, electronic components made of soft magnetic powder can be used to shield electronic devices. In such applications, the radiation magnetic field is altered such that the powder particles themselves are continuously rearranged. The powder particles convert the energy of the electromagnetic waves into heat due to the friction generated.

Preparation of carbonyl iron powder

In these examples, 2.2 kg of phosphorylated carbonyl iron powder (CIP) was filled into a 1.2 L coated tinplate beaker and placed in a planetary mixer. After inerting by purging with N ₂ , 190 mL of acetone containing the corresponding chemicals was added. The inhibitors used in these examples are oleyl alcohol-imidazoline (as the first inhibitor of class A) and oleyl-creatinine (as the second inhibitor of class B). The composition of each solution is given in Tables 1 and 3.

After the slurry was stirred by a paddle mixer at 30-100 r/min for 30 min at room temperature, the temperature was raised above the boiling point of acetone. After heat treatment for 3 hours to 4 hours, the dried powder became ready to use.

Mixed with epoxy resin

The coated CIP powder (100 g) and epoxy resin (Epikote 1004, Momentive) were mixed by dissolving an epoxy resin (2.8 g) in a solvent (20 mL; for example, acetone, methyl ethyl ketone). The coated CIP was stirred with the epoxy solution in a glass beaker using a dissolver mixer (IKA, RW20 D2M, 1000 R/min). After mixing, the slurry was poured into an aluminum plate and then placed in a fume hood for 8 h. The obtained dried CIP epoxy board was ground in a knife mill (Kinematica, Microtron MB550) for 10 seconds to obtain an instant powder.

Molding and wiring of the ring core

6.8 g (±0.1 g) of the pressed powder was placed in a steel mold (ring type: outer diameter 20.1 mm; inner diameter 12.5 mm; resulting height of about 5-6 mm), and molded at 440 MPa for several seconds. The density of the ring core is calculated based on the exact mass and height of the ring. The ring core was wired (20 windings) with an insulated 0.85 mm copper wire (Isodraht, Multogan 2000MH 62) to measure magnetic permeability and electrical resistivity.

Magnetic permeability and resistivity measurement

The magnetic permeability of the ring core was measured using an LRC gauge (E4980A Agilent). All measurements were made at 0 kHz with a bias of 0 V DC. Apply 10 mA test AC current To the core of the ring.

To measure the resistivity of the pressed part, connect the power supply to the voltmeter and the sample in series. 300 volts was applied to the multimeter and the samples were connected in series. Use the voltage reading of the multimeter to estimate the resistance of the sample using the following equation.

R = R _{Scale sample} × (V _PS -V _scale) / V _scale, wherein the resistance R of _{the sample} line of the cylindrical, internal resistance R of the _scale based scale, V _PS is applied from the power supply line of the voltage ( = 300V), and the V _gauge is derived from the reading of the voltmeter.

Corrosion test

Place the filter paper (Macherey-Nagel, MN640W) in a plastic Petri dish ( 33mm, 12mm high). 1 g of the coated powder (without epoxy) was placed on the filter paper. 2 mL of distilled water was added to the powder and the Petri dish was closed. The closed petri dish was placed in a climatic chamber set to 85 ° C and 85% relative humidity. After 24 h, the culture dish was removed from the climate chamber and opened. The filter paper was rinsed with water to remove the iron powder, and rinsed again with acetone, followed by drying. If iron oxide or hydroxide is formed, the filter paper turns orange to brown, or an orange to brown spot is observed. Corrosion resistance is evaluated by inspection of dry filter paper: ++ is equivalent to no corrosion marks; + corresponds to some small (<2mm) orange/brown dots or thin (<2mm) lines around the powder; - equivalent to powder around There are some (>2mm) orange/brown dots or (>2mm) lines; the entire sheet is orange/brown.

Test Results

After the carbonyl iron powder was processed and a compacted sample was formed, the magnetic permeability, electrical resistivity, and corrosion characteristics were measured as described above. The results of Examples 1 to 11 are given in Table 2.

In contrast, Table 3 shows in the first row the magnetic permeability, electrical resistivity and corrosion resistance of the phosphorylated carbonyl iron powder which has not been treated with the inhibitor A or B. In this context, example number 4 and number 5, including inhibitor A or B, individually illustrate the effect of each inhibitor on magnetic permeability, electrical resistivity, and corrosion resistance. However, treatment with Inhibitor A (Example No. 11) produced a high corrosion resistance, moderately high magnetic permeability, but produced a small electrical resistivity, using Inhibitor B (Example No. 5) High magnetic permeability and high electrical resistivity are obtained, but only moderate corrosion resistance is obtained.

Examples 1 to 3 and 6 to 11 including phosphorylated carbonyl iron powder treated with two inhibitors show that the characteristic parameters (e.g., magnetic core) of the compacting device can be optimized by adjusting the content. Specifically, increasing the content of the inhibitor A exhibits better corrosion resistance and higher electrical resistivity. On the other hand, the higher content of the inhibitor B causes the magnetic permeability to increase, and the threshold is at most about 0.3% by weight. An optimal inhibitor composition was achieved in Example 2 wherein the solution used to treat the phosphorylated carbonyl iron powder contained about 0.2 wt% inhibitor A and 0.1 wt% inhibitor B. The composition produces a compacted sample core exhibiting high magnetic permeability values as well as resistivity values and high corrosion resistance.

Claims (15)

A method of coating a soft magnetic powder, comprising the step of treating the soft magnetic powder with a solution comprising: A) at least one first inhibitor comprising at least one substituted or unsubstituted ring nitrogen atom and a 5- to 12-membered heterocyclic compound of at least one ring carbon atom in which one ring atom is substituted with a C ₂ -C ₂₈ alkyl group, a C ₂ -C ₂₈ alkenyl group or a C ₂ -C ₂₈ alkynyl group; and optionally B) At least one second inhibitor having a compound of formula (I), Wherein R ^{1 represents} C ₂ -C ₂₈ alkyl, C ₂ -C ₂₈ alkenyl or C ₂ -C ₂₈ alkynyl; and R ² and R ³ independently of each other indicate H, C ₁ -C ₆ alkyl, C ₂ - C ₆ alkenyl, C ₁ -C ₆ alkynyl, C ₃ -C ₇ cycloalkyl or C ₆ -C ₁₂ aryl. The method of claim 1, wherein the heterocyclic compound of the at least one first inhibitor of the class (A) is selected from the group consisting of imidazole, imidazoline, imidazolium, benzimidazole, benzimidazole Porphyrin, benzimidazole, thiazole, thiazoline, thiazole, benzothiazole, benzothiazoline, benzothiazole, oxazole, oxazoline, oxazolidine, benzoxazole, benzoxazoline , benzoxazole, pyridine, colin base, pyrimidine, triazole, triazoline, benzotriazole, tetrazole. The method of claim 1 or 2, wherein the heterocyclic compound is further subjected to H, C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₁ -C ₆ alkynyl, C ₃ -C ₇ cycloalkyl Or a C ₆ -C ₁₂ aryl group. The method of claim 1 or 2, wherein the compound of formula (I) is derived from a fatty acid. The method of claim 1 or 2, wherein the solution contains at least each of categories A) and B) An inhibitor. The method of claim 1 or 2, wherein the solution contains 0.05% by weight or more of the first inhibitor of the class A). The method of claim 1 or 2, wherein the solution contains 0.03 wt% or more of the second inhibitor of category B). The method of claim 1 or 2, wherein the weight ratio of one or more inhibitors of class A) to one or more inhibitors of class B) is greater than one. The method of claim 1 or 2, wherein the soft magnetic powder is a carbonyl iron powder. The method of claim 1 or 2, wherein the soft magnetic powder is pretreated. The method of claim 1, wherein the soft magnetic powder is phosphorylated. A soft magnetic powder obtained by the method of claim 1. A soft magnetic powder comprising: A) at least one inhibitor which is a 5- to 12-membered heterocyclic compound containing at least one substituted or unsubstituted ring nitrogen atom and at least one ring carbon atom, wherein one ring atom Substituted by C ₂ -C ₂₈ alkyl, C ₂ -C ₂₈ alkenyl or C ₂ -C ₂₈ alkynyl; and optionally B) at least one inhibitor having the compound of formula (I) Wherein R ^{1 represents} C ₂ -C ₂₈ alkyl, C ₂ -C ₂₈ alkenyl or C ₂ -C ₂₈ alkynyl; and R ² and R ³ independently of each other indicate H, C ₁ -C ₆ alkyl, C ₂ - C ₆ alkenyl, C ₁ -C ₆ alkynyl, C ₃ -C ₇ cycloalkyl or C ₆ -C ₁₂ aryl. A soft magnetic powder of claim 12 or 13 for use in the manufacture of electronic components. An electronic component comprising a soft magnetic powder as claimed in claim 12 or 13.