Classifications

• • 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
  • C09D179/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen, with or without oxygen, or carbon only, not provided for in groups C09D161/00 - C09D177/00
  • C09D179/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
  • C09D179/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• • 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
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
• • 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
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/20—Diluents or solvents
• • 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
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
• • 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

Definitions

• This disclosure relates to a method for producing insulating electrocoating paint and insulating electrocoating paint.
• Patent Document 1 discloses a suspension (electrodeposition liquid) in which resin particles and heat-resistant particles are dispersed in a dispersion medium.
• the present disclosure has been made in consideration of the above circumstances, and aims to provide a method for producing an insulating electrocoating for forming a coating film that is heat resistant and has excellent long-term insulating stability.
• the present disclosure also aims to provide an insulating electrocoating produced by the method.
• a method for producing an insulating electrocoating comprising the step of preparing an insulating electrocoating by mixing a resin liquid containing a polyimide resin and a liquid medium containing water and an organic solvent with a silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property.
• the present disclosure it is possible to provide a manufacturing method for insulating electrocoating for forming a coating film that is heat resistant and has excellent long-term insulating stability.
• One aspect of the present disclosure provides a method for producing an insulating electrodeposition paint, comprising a step of mixing a resin liquid containing a polyimide-based resin and a liquid medium containing water and an organic solvent with a silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property to prepare an insulating electrodeposition paint.
• a resin liquid containing a polyimide-based resin and a liquid medium containing water and an organic solvent with a silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property to prepare an insulating electrodeposition paint.
• the organic solvent may contain N-methyl-2-pyrrolidone and 1-methoxy-2-propanol. This makes it easier to maintain good dispersibility of the polyimide resin and silica particles.
• the insulating electrodeposition paint may contain 0.01 to 22 parts by mass of silica particles per 100 parts by mass of polyimide resin. This makes it easier to maintain the dispersibility of the polyimide resin and silica particles.
• the silica sol may contain at least one of NaOH and NH 4 OH, which makes it easier to maintain the dispersibility of the polyimide resin and the silica particles.
• the average particle size of the silica particles may be 1 to 60 nm. This makes it easier to maintain the dispersibility of the silica particles.
• the pH of the silica sol may be 2.0 to 10.0. This makes it easier to maintain the dispersibility of the silica particles and to form a coating film that is heat resistant and has excellent insulation stability over the long term.
• the liquid medium may contain 70 to 95% by mass of an organic solvent. This makes it easier to maintain the dispersibility of the polyimide resin and silica particles.
• an insulating electrodeposition paint comprising a mixture of a resin liquid containing a polyimide-based resin and a liquid medium containing water and an organic solvent, and a silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property.
• the insulating electrodeposition paint can form a coating film that is heat resistant and has excellent insulating stability over a long period of time.
• the method for producing an insulating electrodeposition paint according to the present disclosure includes a step of mixing a resin liquid containing a polyimide-based resin and a liquid medium containing water and an organic solvent with a silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property to prepare an insulating electrodeposition paint.
• an insulating electrodeposition paint (hereinafter, sometimes simply referred to as a "paint")
• a coating film that has heat resistance and excellent insulation stability over a long period of time.
• the inventors speculate that it is because the polyimide resin and silica particles are suitably dispersed in the paint prepared as described above, resulting in the formation of a homogeneous coating film.
• the resin liquid and silica sol are mixed so that the paint contains preferably 0.01 parts by mass or more of silica particles, more preferably 0.05 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of polyimide resin. Also, from the viewpoint of easily forming a coating film having heat resistance and excellent long-term insulation stability, the resin liquid and silica sol are mixed so that the paint contains preferably 22 parts by mass or less of silica particles, more preferably 15 parts by mass or less, and even more preferably 8 parts by mass or less, per 100 parts by mass of polyimide resin.
• the resin liquid and silica sol in advance and mixing the two, preferably by adding silica sol to the resin liquid and mixing them, it is easy to obtain a paint in which the polyimide resin and silica particles are suitably dispersed.
• a paint in which the polyimide resin and silica particles are suitably dispersed There are no particular restrictions on the method of mixing the two, but for example, if the amount is small, it can be mixed in a beaker while stirring with a magnetic stirrer, and if the amount is large, it can be mixed by stirring with an emulsifier such as a homodisper.
• polyimide resins examples include polyimide resins, polyamideimide resins, polyetherimide resins, polyesterimide resins, etc. Among these, polyimide resins may be used from the viewpoints of dispersibility in the coating material, long-term stability of the coating material, etc.
• the polyimide resin may be present in the coating material as polyimide resin particles.
• the average particle size of the polyimide resin is preferably 10 nm or more, more preferably 100 nm or more, from the viewpoint of facilitating the formation of a homogeneous coating film.
• the average particle size is preferably 1000 nm or less, more preferably 900 nm or less, from the viewpoint of facilitating the formation of a homogeneous coating film.
• the average particle size referred to here is the median size (D50), and can be measured, for example, by using a laser diffraction/scattering type particle size distribution measuring device.
• the content of polyimide resin based on the total amount of resin liquid is preferably 1% by mass or more, and more preferably 5% by mass or more, from the viewpoint of easily forming a coating film that is heat resistant and has excellent insulation stability over a long period of time.
• the content is preferably 25% by mass or less, and more preferably 10% by mass or less, from the viewpoint of easily forming a coating film that is heat resistant and has excellent insulation stability over a long period of time.
• the organic solvent is not particularly limited as long as it is used in a coating material for electrodeposition containing a polyimide resin, but examples thereof include N-methyl-2-pyrrolidone, N,N-dimethylformamide, dimethylsulfoxide, etc., and N-methyl-2-pyrrolidone may be used from the viewpoint of good dispersibility of the polyimide resin and silica particles.
• N-methyl-2-pyrrolidone or the like in combination with an alcohol-based solvent as the organic solvent, it is easy to maintain good dispersibility of the polyimide resin and silica particles.
• the alcohol-based solvent examples include methanol, ethanol, 1-propanol, 2-propanol, t-butyl alcohol, ethylene glycol, propylene glycol, 1-methoxy-2-propanol, etc., and 1-methoxy-2-propanol is preferred from the viewpoint of good dispersibility of the polyimide resin and silica particles.
• the organic solvent preferably contains water, N-methyl-2-pyrrolidone and 1-methoxy-2-propanol, and more preferably consists essentially of these.
• the liquid medium may mainly contain an organic solvent, that is, the content of the organic solvent may be greater than the content of water.
• the liquid medium preferably contains 70 to 95 mass % of the organic solvent, and more preferably contains 75 to 90 mass %.
• the resin liquid may contain a dispersant such as pyridine as an additive.
• Silica sol Silica particles are heat-resistant particles themselves, and when present together with the resin component in the coating film, they can suppress the deterioration of the resin component. It is presumed that this is because the dehydration and endothermic reaction on the surface of the silica particles caused by discharge in the coating film suppresses the deterioration of the resin component caused by discharge.
• polyimide resin the inventors' studies have shown that silica particles have superior properties in this respect compared to metal oxide particles such as alumina and zirconia, which also have heat resistance.
• the silica particles can be used without any particular restrictions, and examples thereof include amorphous (non-crystalline) silica particles.
• amorphous silica particles include fused silica particles, fumed silica particles, and colloidal silica particles. Of these, colloidal silica particles have high monodispersity and are easy to suppress from agglomerating in the paint.
• the shape of the silica particles is not particularly limited, and examples include spherical, cocoon-shaped, and association-shaped. Among these, the use of spherical silica particles makes it easier to suppress aggregation in the paint.
• the silica particles may be particles having a hollow structure, a porous structure, etc.
• the average particle size of the silica particles is preferably 1 nm or more, more preferably 5 nm or more, from the viewpoint of more easily maintaining good dispersibility of the polyimide resin and the silica particles, and is preferably 60 nm or less, more preferably 30 nm or less, from the viewpoint of more easily maintaining good dispersibility of the polyimide resin and the silica particles.
• the average particle size referred to here is the median size (D50), and can be measured, for example, by using a laser diffraction/scattering type particle size distribution measuring device.
• the content of silica particles based on the total amount of silica sol is preferably 5.0% by mass or more, and more preferably 10.0% by mass or more, from the viewpoint of easily forming a coating film that is heat resistant and has excellent insulation stability over a long period of time.
• the content is preferably 30% by mass or less, and more preferably 20% by mass or less, from the viewpoint of easily forming a coating film that is heat resistant and has excellent insulation stability over a long period of time.
• the liquid property of the silica sol is acidic to weakly alkaline.
• the pH of the silica sol is preferably 2.0 or more, more preferably 2.5 or more, from the viewpoint of more easily maintaining the good dispersibility of the polyimide resin and silica particles in the paint.
• the pH is preferably 10.0 or less, more preferably 9.6 or less, from the viewpoint of maintaining the dispersibility of silica particles when used as a paint.
• the pH here is a value measured at 25° C. using a pH meter in accordance with JIS Z 8802.
• the silica sol may contain an alkali or acid as a stabilizer for the silica particles.
• the alkali include NaOH, ammonia (NH 4 OH), etc.
• the acid include organic acids such as lactic acid and acetic acid, and inorganic acids such as nitric acid.
• the silica sol contains NaOH, ammonia (NH 4 OH), etc., from the viewpoint of more easily maintaining good dispersibility of the silica particles due to electrical mutual repulsion with the polyimide resin in the coating material.
• the insulating electrodeposition paint according to the present disclosure is obtained by mixing the above-mentioned resin liquid containing a polyimide resin and a liquid medium containing water and an organic solvent with the above-mentioned silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property.
• a coating film having heat resistance and excellent insulation stability over a long period of time can be formed.
• the liquid properties of the silica sol affect the expression of the characteristics of the coating film (preparation of the desired paint), but there is a risk that the liquid properties may not be properly reflected as the characteristics of the paint obtained by mixing the silica sol with the resin liquid.
• the insulating electrodeposition paint is said to be a mixture of the resin liquid and the silica sol.
• the coating preferably contains 0.01 to 22 parts by mass of silica particles per 100 parts by mass of polyimide resin, more preferably 0.05 to 15 parts by mass, and even more preferably 1 to 8 parts by mass.
• a heat-resistant coating film (insulating film) can be formed on the surface of the object.
• the coating conditions can be, for example, an applied voltage of 10 to 200 kV and a voltage application time of 1 second or more, and the thickness of the coating film formed can be, for example, 1 to 200 ⁇ m.
• the target object is not particularly limited as long as it is an object that is generally subjected to insulating electrodeposition coating, but examples thereof include electric high-power density motor stators, power semiconductors, transistors, and other electronic components that require heat resistance and insulating reliability over a long period of time.
• a method for producing an insulating electrodeposition paint comprising a step of mixing a resin liquid containing a polyimide resin and a liquid medium containing water and an organic solvent with a silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property to prepare an insulating electrodeposition paint.
• the organic solvent comprises N-methyl-2-pyrrolidone and 1-methoxy-2-propanol.
• the insulating electrodeposition paint contains 0.01 to 22 parts by mass of the silica particles per 100 parts by mass of the polyimide resin.
• An insulating electrodeposition paint comprising a mixture of a resin liquid containing a polyimide resin and a liquid medium containing water and an organic solvent, and a silica sol containing silica particles and water and having an acidic to weakly alkaline liquid property.
• alumina sol (Preparation of alumina sol) The alumina sols shown in Table 3 were prepared. Clearsol N: Manufactured by Kawaken Fine Chemicals Co., Ltd. Aluminasol-5F: manufactured by Kawaken Fine Chemical Co., Ltd. Aluminasol-10F: manufactured by Kawaken Fine Chemical Co., Ltd. Alumina sol-10D: manufactured by Kawaken Fine Chemical Co., Ltd.
• Test pieces with the coating film obtained as described above were placed in a drying furnace at 300° C. and taken out after 100 hours. When the appearance of the test pieces with the coating film after taking them out was visually observed, no defects such as cracks or peeling were found in the coating of any of the test pieces.

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Citations (8)

• 2024
  • 2024-05-22 JP JP2025527607A patent/JPWO2024257571A1/ja active Pending
  • 2024-05-22 WO PCT/JP2024/018863 patent/WO2024257571A1/ja active Pending

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