Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/40—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes epoxy resins
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K3/00—Details of windings
  • H02K3/30—Windings characterised by the insulating material
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/003—Polymeric products of isocyanates or isothiocyanates with epoxy compounds having no active hydrogen
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/04—Details of the magnetic circuit characterised by the material used for insulating the magnetic circuit or parts thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2150/00—Compositions for coatings
  • C08G2150/20—Compositions for powder coatings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers

Definitions

• the present invention relates to a powder coated rotor which is used in an electrical motor or generator.
• a rotor which can also be referred to as an armature, is the part that acts as support for the coil windings in the electrical motor or generator.
• the coating on the rotor has been worn away to a large extent, short circuiting will occur and the rotor can no longer be used. It was found that in addition to good adhesion to the surface of the rotor, the coating also needs to have a high cut-through resistance to ensure that a rotor for an electrical motor or generator will have a long lifetime. In addition, it was found that the coating can also be used to coat the stator or field coil of an electrical motor or generator or a toroid or toroidal tape core.
• thermosetting powder coating composition comprising an epoxy-terminated polyoxazolidone resin and a curing agent for the resin.
• the present invention relates to a rotor for use in an electrical motor or generator coated with a powder coating wherein the powder coating is obtained by curing a thermosetting powder coating composition comprising an epoxy- terminated polyoxazolidone resin and a curing agent for the resin.
• thermosetting powder coating composition comprising an epoxy-terminated polyoxazolidone resin and a curing agent for the resin as a coating for a rotor in an electrical motor or generator.
• the epoxy-terminated polyoxazolidone resin that can be used according to the present invention can be obtained by reacting a stoichiometric excess of a diepoxide with a diisocyanate.
• the reaction conditions are chosen such that a low-molecular weight, epoxy-terminated polyoxazolidone resin is obtained.
• Epoxy resins that can be used in the preparation of an epoxy-terminated polyoxazolidone include diglycidyl ethers of aromatic, aliphatic, cylcoaliphatic or heterocyclic compounds, for example, diglycidyl ethers of bisphenol A, diglycidyl ethers of hydrogenated bisphenol A, diglycidyl ethers of bisphenol F, diglycidyl ethers of novolacs, or diglycidyl ethers of polyglycols.
• Examples of commercially available suitable epoxy resins are EPON 828, EPON 825, DER 330, DER 331 , DER 332, DER 337, and DEN 431.
• Isocyanates that can be used in the preparation of an epoxy-terminated polyoxazolidone include isocyanates that can be represented by the formula R- (NCO) k , wherein k is 2 and R represents a divalent aliphatic hydrocarbon group having 2 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having 5 to 15 carbon atoms, a divalent araliphatic hydrocarbon group having 7 to 15 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.
• organic diisocyanates which are particularly suitable include ethylene diisocyanate, 1 ,3-propylene diisocyanate, 1 ,4- tetramethylene diisocyanate, 1 ,6-hexamethylene diisocyanate (HMDI), 2,2,4- trimethyl-1 ,6-hexamethylene diisocyanate, 2-methyl-1 ,5-diisocyanate pentane, 2-ethyl-1 ,4-diisocyanate butane, 1 ,12-dodecamethylene diisocyanate, cyclohexane-1 ,3- and -1 ,4-diisocyanate, 1-isocyanato-2-isocyanatomethyl cyclopentane, isophorone diisocyanate (IPDI), bis-(4-isocyanatocyclohexyl)- methane, 2,4'-dicyclohexylme_hane diisocyanate, 1 ,3-
• polyoxazolidones having an epoxy equivalent weight in the range of 250 to 4000 that can be prepared by reacting diepoxide and diisocyanate reactants in a ratio of epoxide equivalents to isocyanate equivalents of 5: 1 to 1.1 :1 , preferably in the range of 3: 1 to 1.2: 1.
• a condensation catalyst can be used in the reaction to form the polyoxazolidones.
• Such catalysts include those conventionally used for these types of reactions between epoxides and isocyanates, such as quaternary ammonium halides, tertiary amines, lithium halides, lithium halide-phosphonium oxide complexes, n-butoxy lithium, dialkyl zinc, organozinc chelate compounds, trialkyl aluminium, and dibutyltin dilaurate.
• the reaction can be carried out in a solvent, for example, in lower alkanols or dimethylformamide at a temperature in the range of 75 to 200°C.
• the powder coating composition used according to the present invention further comprises a curing agent for the epoxy-terminated polyoxazolidone resin.
• a curing agent for the epoxy-terminated polyoxazolidone resin is well-known in the art and include polyamines, polyamides, polyaminoamides, polyphenols, polymeric thiols, polycarboxylic acids, polyols, imidazoles, tertiary amines, and quaternary ammonium halides. These last three curing agents can also act as an accelerator for the curing reactions.
• Examples of imidazoles that can be used as curing agent and curing accelerator include 2-styrylimidazole, 1-benzyl-2-methylimidazole, 2-methyl- imidazole, and 2-butylimidazole.
• the powder coating composition can further comprise fillers and/or additives to improve the properties of the coating, such as stabilisers, antioxidants, levelling agents, anti-settling agents, matting agents, rheology modifiers, flexibility agents, surface-active agents, UV light absorbers, light stabilisers, amine synergists, waxes, or adhesion promoters. Further, the coating composition can comprise one or more pigments.
• the coating composition can also comprise additional resins, such as 0 - 30, preferably 5 - 20, percent by weight of an epoxy resin or a mixture of epoxy resins, such as DER 663, DER 664, DR 667, or 0 - 30, preferably 5 - 20, percent by weight of an epoxy novolac or a mixture of epoxy novolacs, such as DER 642, DER 672, Araldit ECN1299 or Araldit ECN9699.
• additional resins such as 0 - 30, preferably 5 - 20, percent by weight of an epoxy resin or a mixture of epoxy resins, such as DER 663, DER 664, DR 667, or 0 - 30, preferably 5 - 20, percent by weight of an epoxy novolac or a mixture of epoxy novolacs, such as DER 642, DER 672, Araldit ECN1299 or Araldit ECN9699.
• the powder coating composition used according to the present invention comprises: - 30 - 90, preferably 40 - 50, percent by weight of the powder coating composition of a polyoxazolidone resin or a mixture of polyoxazolidone resins;
• the powder coating composition can be made by any process wherein all ingredients of the composition are uniformly mixed.
• the composition can be prepared by intimately mixing the ingredients in an extruder at a temperature above the softening point of the film forming polymer(s), but below the temperature at which significant pre-reaction would occur.
• the extrudate is usually rolled into a flat sheet, allowed to cool, and broken down into small particles, for example by grinding.
• the powder coating particles should have a size below 300 ⁇ m, preferably an average size in the range of 100 to 200 ⁇ m.
• the powder coating can be applied to the rotor by any known powder coating process. Fluidised bed sintering, electrostatic powder coating, or an electrostatic fluidised bed process is preferred.
• electrostatic powder coating for the coating of a rotor with a powder coating composition comprising an epoxy-terminated polyoxazolidone resin the electrostatic fluidised bed process is preferred.
• the rotor is normally heated to a temperature in the range of 180 - 260°C.
• the coating is applied in a film thickness in the range of 250 to 500 ⁇ m.
• thermosetting powder coating composition comprising an epoxy-terminated polyoxazolidone resin and a curing agent for the resin
• the coated rotor can be used in small-size electrical motors in household and automotive appliances, but it can also be used in larger-size electrical motors or generators or drilling machines.
• the thermosetting powder coating composition comprising an epoxy-terminated polyoxazolidone resin can also be used for coating field coils, stators, toroids, or toroidal tape cores.
• a powder coating composition a density of 1.65 - 1.75 g/cm 3 and less than 0.5 wt.% of particles with a size above 200 ⁇ m was prepared by mixing the following compounds:
• This powder coating composition was applied to a rotor in a fluidised bed process and cured at a temperature in the range of 200 - 240°C.
• the obtained coated rotor was coated with a smooth film with a thickness in the range of 250 - 500 ⁇ m.
• the film had a gloss (measured in accordance with DIN 67530) of 80 - 100 units, an impact resistance (measured in accordance with DIN 30671) of 10 Joule, a hardness (measured in accordance with DIN 53153) > 100, and an edge coverage > 40%, a breakdown voltage > 30 kV/mm, and a high cut-through resistance at a temperature above 300°C.
• thermosetting powder coating composition comprising an epoxy-terminated polyoxazolidone resin and a curing agent for the resin as prepared in Example 1 was compared to the stability of a commercially available anhydride-containing thermosetting powder coating composition.
• Freshly prepared samples of both coatings were applied to a rotor and cured to a smooth coating film. A part of these samples was stored at 23°C and applied to a rotor after 6 months' storage.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Power Engineering (AREA)
• Wood Science & Technology (AREA)
• Materials Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Paints Or Removers (AREA)
• Iron Core Of Rotating Electric Machines (AREA)
• Insulation, Fastening Of Motor, Generator Windings (AREA)

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Applications Claiming Priority (4)

Publications (1)

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• 2001
  • 2001-05-31 TW TW090113190A patent/TW593404B/zh not_active IP Right Cessation
• 2002
  • 2002-03-04 WO PCT/EP2002/003681 patent/WO2002073772A1/en not_active Ceased
  • 2002-03-04 CA CA002440857A patent/CA2440857A1/en not_active Abandoned
  • 2002-03-04 KR KR10-2003-7011445A patent/KR20040030521A/ko not_active Ceased
  • 2002-03-04 MX MXPA03008345A patent/MXPA03008345A/es active IP Right Grant
  • 2002-03-04 JP JP2002572703A patent/JP2004526396A/ja active Pending
  • 2002-03-04 EP EP02720002A patent/EP1368879A1/de not_active Withdrawn
  • 2002-03-04 CN CNA028064488A patent/CN1496601A/zh active Pending

Non-Patent Citations (1)

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