Powder coating

Abstract

To provide powder coating which achieves both excellent filling property and suppression of sag.SOLUTION: Powder coating used for coating a coil end contains a particulate thermosetting resin composition, wherein the thermosetting resin composition contains an epoxy resin, a curing agent, and an inorganic filler, in complex viscosity of the powder coating measured at 150°C and 1 Hz by dynamic viscoelasticity measurement, viscosity η1 after 1 min from the start of measurement is 40 Pa s or more and 1,000 Pa s or less, and a ratio (η2 / η1) of viscosity η2 after 2 min from the start of measurement to η1 is 6.0 or more and 100 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to powder coatings. [Background technology]

[0002] Patent Documents 1 to 3 describe techniques relating to powder coatings containing epoxy resins. Patent Document 1 (JP Patent Publication No. 6-039344) describes a powder coating method in which a resin powder coating containing a crystalline thermosetting resin and having high melt fluidity is applied to the lower surface of a preheated workpiece, the workpiece is then turned upside down, and the powder coating is heated to its curing temperature in this state, causing the resin powder coating applied to the workpiece to flow down in a molten state while undergoing a curing reaction (Claim 1).The same document also describes that a crystalline epoxy resin is used as the crystalline thermosetting resin (paragraph 0005), that the workpiece may be a coil (Claim 2), and that the viscosity of the powder coating when molten may be 1000 cp or less (Claim 3).

[0003] Patent document 2 (JP Patent Publication No. 2001-238419A) describes that an insulating resin is applied to cover the top surface of the coil end of the stator coil (claim 1), and also describes that the insulating resin can be a resin whose main component is an epoxy resin with a predetermined viscosity that does not penetrate from the top of the coil end to the parts of the wire other than the top when it dries and hardens (claim 9).

[0004] Patent Document 3 (JP 2000-278901 A) describes an insulating structure for a stator of a rotating electrical machine, which includes a stator winding having a joint and an insulating resin covering the joint, and in which the elastic modulus of the insulating resin is set to a value smaller than the upper limit at which separation occurs between the insulating resin and the joint, and the upper limit is changed according to the thickness of the insulating resin (Claim 1).The same document also describes that the maximum thickness of the insulating resin is set to approximately 0.5 mm, the stator winding is made of copper, the insulating resin is epoxy (Claim 4), and the viscosity of the insulating resin before hardening must be at least 50 a·s (Paragraph 0031). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-039344 [Patent Document 2] Japanese Patent Application Publication No. 2001-238419 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-278901 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the present inventors have studied the techniques described in the above documents, they have found that there is room for improvement in terms of achieving both excellent filling properties and suppression of sagging. [Means for solving the problem]

[0007] According to the present invention, A powder coating used to coat coil ends, a particulate thermosetting resin composition, The thermosetting resin composition is Epoxy resin, A hardener; an inorganic filler; Including, The complex viscosity of the powder coating measured by dynamic viscoelasticity measurement under the conditions of 150°C, 1Hz, 25mmφ, aluminum parallel plate, 0.5mm gap, is: The viscosity η1 one minute after the start of measurement is 40 Pa·s or more and 1000 Pa·s or less, There is provided a powder coating material in which the ratio (η2 / η1) of the viscosity η2 after 2 minutes from the start of measurement to the viscosity η1 is 6.0 or more and 100 or less.

[0008] According to the present invention, there is provided a coil having the coil end, the exposed portion of which is sealed with the powder coating material of the present invention.

[0009] According to the present invention, The method includes a step of immersing a coil end of a coil in which a conductor portion is covered with an insulating coating and which has a coil end provided with an exposed portion where the conductor portion is exposed from the insulating coating, into a fluidized bath in which a powder paint flows, and adhering the molten powder paint to the outside of the exposed portion, There is provided a method for sealing a coil end, wherein the powder coating material is the powder coating material of the present invention.

[0010] Any combination of these configurations and conversion of the present invention between methods, devices, etc. are also valid aspects of the present invention. For example, according to the present invention, it is also possible to obtain an article that is coated with the powder coating material of the present invention. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a powder coating material that has both excellent filling properties and suppressed sagging. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view showing a configuration example of a stator in the embodiment. [Figure 2] 2 is a plan view showing an example of the configuration of a coil end of a stator coil in the stator shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment will be described. In this embodiment, the composition may contain each component either alone or in combination of two or more.

[0014] (powder paint) In this embodiment, the powder coating material is used to coat coil ends and contains a particulate thermosetting resin composition. The thermosetting resin composition contains an epoxy resin, a curing agent, and an inorganic filler. Furthermore, in dynamic viscoelasticity measurement under conditions of 150°C, 1 Hz, 25 mm diameter, aluminum parallel plates, and a 0.5 mm gap, the complex viscosity of the powder coating material is measured. The viscosity η1 after 1 minute from the start of measurement is 40 Pa·s or more and 1000 Pa·s or less, and the ratio of the viscosity η2 after 2 minutes from the start of measurement to the viscosity η1 (η2 / η1) is 6.0 or more and 100 or less.

[0015] In this embodiment, the particulate thermosetting resin composition contained in the powder coating contains specific components, and the viscosity η1 and viscosity ratio (η2 / η1) are each within specific ranges, making it possible to obtain a powder coating that combines excellent filling properties with suppressed sagging.

[0016] The inventors of the present invention have investigated how to achieve excellent insulation by stably coating coil ends with powder coating while suppressing sagging during coating, even when the spacing between adjacent coil ends becomes smaller as coils become smaller. As a result, they focused on the flow behavior of powder coating and discovered that by controlling the viscosity η1 at 150°C and the viscosity ratio (η2 / η1) as indicators, it is possible to achieve both excellent filling between conductors and suppressed sagging. The reason for this is thought to be that optimal control of the curing behavior of the powder coating is important to achieve both of these.

[0017] By using the powder coating material of this embodiment, it is possible to stably seal, for example, the connection parts and welded parts of the conductor in the exposed parts, thereby improving the insulation and strength of, for example, the connection parts and welded parts. According to this embodiment, a powder coating material suitable for coating coil ends can be obtained, and it is also possible to provide a powder coating material suitable for use in painting the coil ends of coils in which the conductor portion is covered with an insulating coating and which has coil ends with exposed portions where the conductor portion is exposed from the insulating coating.

[0018] Furthermore, the powder coating material in this embodiment can be used in a powder coating method that includes, for example, a step of immersing the coil end of a coil in which the conductor portion is covered with an insulating coating and which has a coil end with an exposed portion where the conductor portion is exposed from the insulating coating, in a fluidized bath in which the powder coating is flowing, and adhering the molten powder coating material to the outside of the exposed portion; for example, in the above powder coating method, the molten powder coating material can be adhered from the exposed portion of the coil end to the insulating coating. The composition of the powder coating will be explained in more detail below.

[0019] The ratio (η2 / η1) of the viscosity η2 after 2 minutes from the start of measurement to the viscosity η1 after 1 minute from the start of measurement is 6.0 or more, preferably 10 or more, more preferably 20 or more, and even more preferably 30 or more, from the viewpoint of suppressing sagging of the coating film and improving curability. From the viewpoint of improving the filling property, the viscosity ratio (η2 / η1) is 100 or less, preferably 80 or less, more preferably 60 or less, and even more preferably 50 or less.

[0020] From the viewpoint of suppressing sagging, the viscosity η1 of the powder coating is 40 Pa·s or more, preferably 80 Pa·s or more, and more preferably 100 Pa·s or more. From the viewpoint of improving filling properties, the viscosity η1 of the powder coating is 1000 Pa·s or less, preferably 600 Pa·s or less, more preferably 400 Pa·s or less, and even more preferably 200 Pa·s or less.

[0021] From the viewpoint of suppressing sagging, the viscosity η2 of the powder coating may be, for example, 300 Pa·s or more, preferably 1000 Pa·s or more, more preferably 2000 Pa·s or more, and even more preferably 3000 Pa·s or more. From the viewpoint of improving filling properties, the viscosity η2 of the powder coating is preferably 10,000 Pa·s or less, more preferably 9,000 Pa·s or less, and even more preferably 8,000 Pa·s or less.

[0022] In terms of the complex viscosity of the powder coating, the ratio (η3 / η1) of the viscosity η3 1.5 minutes after the start of measurement to the viscosity η1 is preferably greater than 1, more preferably 1.5 or greater, and even more preferably 2.0 or greater, from the viewpoint of suppressing sagging and improving curing properties. From the viewpoint of improving the filling property, the viscosity ratio (η3 / η1) is preferably 10 or less, more preferably 8.0 or less, and even more preferably 5.0 or less.

[0023] In terms of the complex viscosity of the powder coating, the viscosity η4 10 seconds after the start of measurement is preferably 20 Pa·s or more, more preferably 22 Pa·s or more, and even more preferably 24 Pa·s or more, from the viewpoint of suppressing sagging. From the viewpoint of improving filling properties, the viscosity η4 of the powder coating is preferably 40 Pa·s or less, more preferably 35 Pa·s or less, and even more preferably 30 Pa·s or less.

[0024] Here, the complex viscosity of the powder coating is measured under the conditions mentioned above, more specifically, using a dynamic viscoelasticity measuring device (for example, MCR301 manufactured by Anton Paar) under conditions of a temperature of 150°C, a frequency of 1 Hz, 25 mmφ aluminum parallel plates, and a gap of 0.5 mm. The viscosities measured 1 minute, 2 minutes, 1.5 minutes, and 10 seconds after the start of measurement are designated as η1, η2, η3, and η4, respectively.

[0025] Next, the particle size characteristics of the thermosetting resin composition in the powder coating will be described. Particle size d of the thermosetting resin composition90 From the viewpoint of ensuring that the powder coating material flows favorably in the fluidizing tank when coating the coil end, the thickness is preferably 50 μm or more, more preferably 70 μm or more, and even more preferably 100 μm or more. In addition, in order to prevent the accumulation of coarse particles on the bottom of the fluidized bed and to ensure more stable coating, the particle size d of the thermosetting resin composition is 90 is preferably 200 μm or less, more preferably 180 μm or less, and even more preferably 150 μm or less.

[0026] Here, the particle size characteristics of the thermosetting resin composition and the particle size characteristics of the inorganic particles described later can be obtained by a laser diffraction method, specifically, by measuring the particle size distribution of the particles on a volume basis using a commercially available laser diffraction particle size distribution measuring device (for example, SALD-2300 manufactured by Shimadzu Corporation).

[0027] Next, the constituent components of the powder coating will be described. The powder coating contains a thermosetting resin composition, which contains an epoxy resin, a curing agent, and an inorganic filler.

[0028] Specific examples of epoxy resins include those that have two or more epoxy groups in the molecule and are solid at room temperature, such as bisphenol A, bisphenol F, bisphenol S, novolac, phenol novolac, cresol novolac, biphenyl, naphthalene, biphenyl aralkyl, and aromatic amine epoxy resins.

[0029] From the viewpoint of more stably covering the coil end, the epoxy resin preferably contains one or more selected from the group consisting of bisphenol A type epoxy resins, biphenyl type epoxy resins such as biphenyl aralkyl type epoxy resins, dicyclopentadiene type epoxy resins, orthocresol novolac type epoxy resins, and tetramethylbiphenyl type epoxy resins; More preferably, the epoxy resin comprises a bisphenol A type epoxy resin and one or more selected from the group consisting of biphenyl type epoxy resins, dicyclopentadiene type epoxy resins, biphenyl aralkyl type epoxy resins, and tetramethylbiphenyl type epoxy resins: More preferably, it contains a bisphenol A type epoxy resin and a biphenyl aralkyl type epoxy resin. In this case, the softening point of the bisphenol A type epoxy resin is, for example, 65 to 150°C or less, and preferably 70 to 120°C or less, from the viewpoint of suppressing solidification in the tank and improving the desirable appearance of the coating film formed by the powder coating.

[0030] From the viewpoint of improving the surface smoothness of the cured powder coating, the content of the epoxy resin in the thermosetting resin composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, based on the total amount of the thermosetting resin composition. Furthermore, from the viewpoint of improving the coating moldability of the powder coating, the content of the epoxy resin in the thermosetting resin composition is preferably 70 mass % or less, more preferably 60 mass % or less, even more preferably 50 mass % or less, and even more preferably 40 mass % or less, based on the total amount of the thermosetting resin composition.

[0031] The thermosetting resin composition may also contain other thermosetting resins, such as one or more selected from the group consisting of phenolic resins, melamine resins, unsaturated polyester resins, and polyurethane resins. The thermosetting resin may also contain a resin curing agent such as a phenolic resin curing agent, which will be described later.

[0032] The content of the thermosetting resin in the thermosetting resin composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, based on the total thermosetting resin composition, from the viewpoint of improving the surface smoothness of the cured powder coating material. Furthermore, from the viewpoint of improving the coating moldability of the powder coating, the content of the thermosetting resin in the thermosetting resin composition is preferably 70 mass % or less, more preferably 60 mass % or less, even more preferably 50 mass % or less, still more preferably 45 mass % or less, and even more preferably 40 mass % or less, based on the total thermosetting resin composition.

[0033] Specific examples of the curing agent include aromatic amines such as diaminodiphenylmethane and aniline resin, condensates of aliphatic amines and aliphatic dicarboxylic acids, and amines such as dicyandiamide and its derivatives; Various imidazole and imidazoline compounds; Polydicarboxylic acids or their anhydrides, such as adipic acid, sebacic acid, phthalic acid, maleic acid, trimellitic acid, benzophenone dicarboxylic acid, and pyromellitic acid; phenolic resins such as novolac-type phenolic resins, biphenyl aralkyl-type phenolic resins, and naphthol aralkyl-type phenolic resins; Novolaks, which are condensation products of aldehydes with dihydrazides such as adipic acid and phthalic acid, phenol, cresol, xylenol, bisphenol A, etc.; Carboxylic acid amides; Methylolated melamines; and Examples include blocked isocyanurates. From the viewpoint of suppressing sagging of the powder coating and improving the filling properties of the powder coating, the curing agent preferably contains one or more members selected from the group consisting of acid anhydrides and phenolic resins.

[0034] The ratio of the curing agent to the epoxy resin can be adjusted, for example, by changing the types of epoxy resin and curing agent used. From the viewpoint of obtaining good curability and properties of the cured product, the ratio of the curing agent to the epoxy resin is such that the (number of) functional groups of the curing agent is preferably 0.1 molar equivalents or more, more preferably 0.2 molar equivalents or more, and even more preferably 0.3 molar equivalents or more, relative to the (number of) epoxy groups of the epoxy resin, and is also preferably 1.2 molar equivalents or less, more preferably 1.1 molar equivalents or less, and even more preferably 0.9 molar equivalents or less.

[0035] Specific examples of inorganic fillers include silica such as crystalline silica, fused silica such as crushed fused silica, spherical silica, and surface-treated silica; calcium compounds such as calcium carbonate and calcium sulfate; barium sulfate, aluminum oxide (specifically alumina), aluminum hydroxide, magnesium hydroxide, talc, kaolin, clay, mica, dolomite, wollastonite, glass fiber, glass beads, zircon, and molybdenum compounds. From the viewpoint of availability, the inorganic filler preferably contains one or more types selected from the group consisting of silica, alumina, and calcium carbonate, more preferably one or more types selected from the group consisting of silica, alumina, and calcium carbonate, and even more preferably silica.

[0036] When the inorganic filler is silica, the average particle size of the silica, d 50 From the viewpoint of improving the narrow-part filling ability of the powder coating, the diameter is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less, and may be, for example, 1 μm or more.

[0037] The content of the inorganic filler in the thermosetting resin composition is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total weight of the thermosetting resin composition, from the viewpoint of improving the mechanical strength of the thermosetting resin composition. Also, from the viewpoint of improving the smoothness of the cured product of the thermosetting resin composition, the content of the inorganic filler in the thermosetting resin composition is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less, based on the total weight of the thermosetting resin composition.

[0038] The thermosetting resin composition may contain components other than the above-mentioned components. For example, the thermosetting resin composition may contain a curing accelerator, a colorant, a leveling agent, a flame retardant, a coupling agent, etc.

[0039] For example, from the viewpoint of suppressing sagging of the powder coating and improving the filling properties of the powder coating, it is preferable that the thermosetting resin composition further contains a curing accelerator.

[0040] Specific examples of the curing accelerator include organic phosphines such as triphenylphosphine; imidazole compounds such as 2-phenylimidazole; and amine compounds such as tertiary amines. In addition, from the viewpoint of further improving the balance between the effects of suppressing sagging and improving filling property, it is also preferable that the thermosetting resin composition contains a bisphenol A type epoxy resin and a biphenyl type epoxy resin such as a biphenyl aralkyl type epoxy resin, and further contains a curing accelerator.

[0041] From the viewpoint of obtaining good curing properties, the content of the curing accelerator in the thermosetting resin composition is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and is preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less, based on the total amount of the thermosetting resin composition.

[0042] The thermosetting resin composition may further contain a colorant such as a pigment. Specific examples of the pigment include one or more selected from the group consisting of titanium oxide, iron oxide, zinc oxide, carbon black, and cyanine blue. From the viewpoint of obtaining favorable coloring properties, the content of the pigment in the powder coating is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, even more preferably 1 mass% or more, based on the total powder coating, and is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 2 mass% or less.

[0043] The powder coating may be composed of a particulate thermosetting resin composition or may further contain other components, such as a fluidity-imparting agent, for example, inorganic particles of silica, alumina, etc.

[0044] Next, a method for producing a powder coating will be described. Specifically, the method for producing a powder coating includes a step of preparing a thermosetting resin composition. Furthermore, when the powder coating contains components other than the thermosetting resin composition (e.g., inorganic particles), the method for producing a powder coating may further include, for example, a step of mixing the thermosetting resin composition with the other components. For example, in the case of a particulate thermosetting resin composition, an epoxy resin, an inorganic filler, a curing agent, and optional components are blended and mixed in a predetermined order, and then melt-kneaded while heating to obtain a kneaded mixture of all raw materials. The resulting kneaded mixture of all raw materials is then pulverized using an impact mill to obtain an epoxy resin powder coating. Furthermore, after pulverization, the particle size of the powder coating may be adjusted by sieving to remove fine particles and coarse particles.

[0045] In order to obtain a powder coating having the above viscosity characteristics within a specific range, it is important to appropriately select the components and composition of the thermosetting resin composition, such as the type and amount of epoxy resin. It is also preferable to further add a curing accelerator.

[0046] (coil) The coil has coil ends whose exposed portions are sealed with the powder coating of this embodiment. A specific example of the coil is a motor coil such as a drive motor coil, etc. Hereinafter, a more specific description will be given using a stator coil of a motor as an example.

[0047] Fig. 1 is a perspective view showing an example of the configuration of a stator in an embodiment. The stator 100 shown in Fig. 1 has a stator core 101 and a stator coil 103. The stator coil 103 is disposed in a groove (slot, not shown) provided in the inner wall of the stator core 101.

[0048] Fig. 2 is a plan view showing an example of the configuration of a coil end 105 of a stator coil 103. The coil end 105 is provided with an enamel coating portion 107 in which the conductor portion is covered with an insulating coating, such as enamel, and an exposed portion 109 in which the conductor portion is exposed from the enamel coating, and the exposed portion 109 is sealed with the powder paint of this embodiment. In Fig. 2, a coating portion 111 is provided from the exposed portion 109 to the enamel coating portion 107. The coating portion 111 is made of a cured product of the powder paint of this embodiment.

[0049] (Powder coating method) The powder coating method is a method of sealing the coil ends using, for example, the powder coating of this embodiment. Specifically, this method includes a step (step 1) of immersing the coil ends 105 of a coil (stator coil 103) having coil ends 105 in which the conductor portions are covered with an insulating coating and which are provided with exposed portions 109 where the conductor portions are exposed from the insulating coating, in a fluidized bath in which the powder coating flows, and causing the molten powder coating to adhere to the outside of the exposed portions.

[0050] Step 1 may include, for example, a step (step 1-1) of introducing air into a fluidization tank containing powder paint to cause the powder paint to flow, and a step (step 1-2) of immersing the coil end 105 in the fluidization tank in which the powder paint is flowing. Step 1-1 can be carried out, for example, by using a fluidization tank having a perforated plate at the bottom, filling the powder coating material above the perforated plate, and introducing air from outside the perforated plate into the fluidization tank through the perforated plate.

[0051] In step 1-2, immersing the coil end 105 in the fluidized bed and adhering the molten powder paint to the outside of the exposed portion may be performed as a single step or in stages, but is preferably performed as a single step from the viewpoint of improving the sealing stability of the exposed portion 109. In other words, the adhesion of the molten powder paint to the outside of the exposed portion preferably occurs while the coil end 105 is immersed in the fluidized bed.

[0052] From the viewpoint of improving the sealing stability of the exposed portion 109, the powder coating method preferably further includes a step of heating the coil end 105 before immersing the coil end 105 in the fluidizing bath. At this time, by immersing the heated coil end 105 in the fluidizing bath in which the powder paint is flowing, the powder paint near the coil end 105 adheres to the coil end 105 as a molten material in the fluidizing bath. Furthermore, from the viewpoint of more stably molten powder paint adhered to the coil end 105, the coil end 105 may be heated after being removed from the fluidizing bath. The coil ends 105 can be heated, for example, by a heater disposed above the fluidization tank.

[0053] In this embodiment, the powder coating method may further include a step (step 2) of heating the coil end 105 to harden the powder paint after the step of applying the molten powder paint to the outside of the exposed portion 109 of 105. The heat hardening conditions can be set appropriately depending on the type and size of the coil end 105, the constituent components of the powder paint, etc. In addition, in the powder coating method, steps 1 and 2 may be alternately repeated multiple times in order to increase the coating thickness.

[0054] In this embodiment, by using a powder paint containing a thermosetting resin composition having specific components and particle size characteristics, it is possible to suppress dripping when stably sealing the coil end 105, while improving the filling ability of the connection and welded parts in the exposed part 109, and to form a coating part 111 with excellent insulating properties.

[0055] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Below, examples of reference forms are added. 1. A powder coating used to coat coil ends, a particulate thermosetting resin composition, The thermosetting resin composition is Epoxy resin, A hardener; an inorganic filler; Including, The complex viscosity of the powder coating measured by dynamic viscoelasticity measurement under the conditions of 150°C, 1Hz, 25mmφ, aluminum parallel plate, 0.5mm gap, is: The viscosity η1 one minute after the start of measurement is 40 Pa·s or more and 1000 Pa·s or less, A powder coating having a ratio (η2 / η1) of the viscosity η2 after 2 minutes from the start of measurement to the viscosity η1 of 6.0 or more and 100 or less. 2. The powder coating material according to 1, wherein the η2 is 300 Pa·s or more and 10,000 Pa·s or less. 3. The powder coating material according to 1. or 2., wherein the ratio (η3 / η1) of the complex viscosity η3 1.5 minutes after the start of measurement to the viscosity η1 is greater than 1 and not greater than 10. 4. A powder coating material according to any one of 1. to 3., wherein the complex viscosity η4 10 seconds after the start of measurement is 20 Pa·s or more and 40 Pa·s or less. 5. The epoxy resin is Bisphenol A epoxy resin, one or more selected from the group consisting of biphenyl-type epoxy resins, dicyclopentadiene-type epoxy resins, biphenylaralkyl-type epoxy resins, and tetramethylbiphenyl-type epoxy resins; 5. The powder coating material according to any one of 1. to 4., 6. A powder coating material according to any one of 1. to 5., wherein the curing agent comprises one or more members selected from the group consisting of acid anhydrides and phenolic resins. 7. Particle size d of the thermosetting resin composition measured by laser diffraction method 90 The powder coating material according to any one of 1. to 6., wherein the particle size is 50 μm or more and 200 μm or less. 8. The powder coating material according to any one of 1. to 7., wherein the thermosetting resin composition further contains a curing accelerator. 9. The powder coating material according to any one of 1. to 8., which is used in a powder coating method in which a molten powder coating material is applied from the exposed portion of the coil end to the insulating coating. 10. A coil having the coil end, the exposed portion of which is sealed with the powder coating material described in any one of 1. to 9. 11. A method for manufacturing a coil, the method including the steps of: immersing a coil end, the conductor of which is covered with an insulating coating and having an exposed portion where the conductor is exposed from the insulating coating, in a fluidized bath in which a powder paint is flowing; and adhering the molten powder paint to the outside of the exposed portion; A method for sealing a coil end, wherein the powder paint is the powder paint described in any one of 1. to 9. [Example]

[0056] (Examples 1 to 4, Comparative Examples 1 to 4) In this example, a powder coating composition was produced from a thermosetting resin composition and evaluated. The components used in the powder coating composition are shown below.

[0057] (Raw material for thermosetting resin composition) (epoxy resin) Epoxy resin 1: Bisphenol A type epoxy resin, JER1001, manufactured by Mitsubishi Chemical Corporation, softening point 64°C Epoxy resin 2: Bisphenol A type epoxy resin, JER1002, manufactured by Mitsubishi Chemical Corporation, softening point 78°C Epoxy resin 3: Bisphenol A type epoxy resin, JER1003F, manufactured by Mitsubishi Chemical Corporation, softening point 89°C Epoxy resin 4: biphenyl aralkyl type epoxy resin, NC-3000H, manufactured by Nippon Kayaku Co., Ltd. Epoxy resin 5: Dicyclopentadiene type epoxy resin, XD-1000, manufactured by Nippon Kayaku Co., Ltd. Epoxy resin 6: Tetramethylbiphenyl type epoxy resin, manufactured by Mitsubishi Chemical Corporation, YX4000 (Inorganic filler) Inorganic filler 1: spherical silica, manufactured by Nippon Steel Chemical & Material Co., Ltd., HS-208, d 50 = 20 μm (hardening agent) Hardener 1: 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) Hardener 2: Novolac phenolic resin, PR-51470, manufactured by Sumitomo Bakelite (curing accelerator) Curing accelerator 1: Triphenylphosphine (TPP), manufactured by KI Chemical Co., Ltd. (pigment) Pigment 1: Titanium oxide, manufactured by Ishihara Sangyo Co., Ltd., CR-500

[0058] (Powder paint manufacturing) A thermosetting resin composition was prepared according to the formulation shown in Table 1, and the resulting thermosetting resin composition and other components were mixed in a conventional manner to obtain the powder coating material of each example. Here, for the thermosetting resin composition, the raw material components were mixed in a mixer, melt-kneaded at 80°C, and then pulverized in a pulverizer. Then, air classification and sieving were performed to obtain a thermosetting resin composition having the particle size characteristics shown in Table 1.

[0059] (Physical properties and evaluation of powder coatings) The particle size distribution and viscosity characteristics of the thermosetting resin compositions obtained in each example were measured by the following methods. The thermosetting resin composition was used as a powder coating, and the linear expansion coefficient, filling property, and sagging were measured by the following methods. The measurement results are also shown in Table 1.

[0060] (complex viscosity) The complex viscosity of the thermosetting resin composition obtained in each example was measured using a dynamic viscoelasticity measuring device (MCR301 manufactured by Anton Paar) under conditions of a temperature of 150°C, a frequency of 1 Hz, 25 mmφ aluminum parallel plates, and a gap of 0.5 mm. The viscosities 1 minute, 2 minutes, 1.5 minutes, and 10 seconds after the start of the measurement were defined as η1, η2, η3, and η4, respectively.

[0061] (Particle size distribution of thermosetting resin composition) The particle size distribution of the particles was measured on a volume basis using a laser diffraction particle size distribution analyzer (HORIBA, Partica LA-950V2).

[0062] (coefficient of linear expansion) The powder coating material obtained in each example was melt-cured at 190°C for 20 minutes to obtain a molded product, which was then cut into a size of 5 mm x 5 mm x 20 mm and used as a measurement sample. The linear expansion coefficient was measured using a Seiko Instruments TMA SS6000 at a temperature rise rate of 5°C / min under a load of 10 g, and the average linear expansion coefficient from 40°C to 50°C was calculated.

[0063] (Fillability) A 50mm long x 3mm wide x 1mm thick copper plate was wrapped with 500µm thick heat-resistant tape at 50µm from the bottom edge and 10mm from the bottom edge. A test piece (TP) with a V-shaped gap was created by bonding together a copper plate of the same size without tape. The test piece was preheated to 170°C and painted by the flow dipping method to a height that filled the gap. After hardening at 170°C, the specimens were polished and the size of the unfilled area that occurred in the 50µm gap was compared. An unfilled portion of less than 500 μm was rated as ◯, 500 μm or more but less than 1000 μm as △, and 1000 μm or more as ×.

[0064] (Dripping) A copper plate measuring 50 mm long, 5 mm wide, and 3 mm thick was heated to 170°C and immersed twice for 1 second using fluidized bed dip coating, followed by heat curing at 170°C. The copper plate was immersed to a depth of 20 mm from the end of the plate. The film thickness of the side part 40 mm from the end of the unpainted part (10 mm from the end of the coating) was compared with the film thickness of the bottom of the coating. A value of 0 indicates a thickness of less than 2 times (bottom film thickness / side film thickness), a value of △ indicates a thickness of 2 times or more but less than 3 times, and a value of × indicates a thickness of 3 times or more or where the coating film had dripped.

[0065] [Table 1]

[0066] As can be seen from Table 1, the powder coatings obtained in each example had an excellent balance of filling properties and sagging prevention effects. The powder coatings in each example can be preferably used to cover the exposed parts of the coil ends. [Explanation of symbols]

[0067] 100 stator 101 Stator core 103 Stator coil 105 coil end 107 Enamel coated part 109 Exposed part 111 Covering part

Claims

1. A powder coating used to coat coil ends, The thermosetting resin composition is in the form of particles. The thermosetting resin composition is Epoxy resin, A hardener; an inorganic filler; A curing accelerator; Including, The epoxy resin is bisphenol A epoxy resin, one or more selected from the group consisting of biphenyl-type epoxy resins, dicyclopentadiene-type epoxy resins, biphenylaralkyl-type epoxy resins, and tetramethylbiphenyl-type epoxy resins; Including, the content of the epoxy resin in the thermosetting resin composition is 20% by mass or more and 50% by mass or less based on the total amount of the thermosetting resin composition; the curing agent comprises one or more selected from the group consisting of acid anhydrides and phenolic resins, the inorganic filler comprises silica; the content of the silica in the thermosetting resin composition is 40% by mass or more and 70% by mass or less based on the total amount of the thermosetting resin composition; the content of the curing accelerator in the thermosetting resin composition is 0.01% by mass or more and 1% by mass or less with respect to the entire thermosetting resin composition, The complex viscosity of the powder coating measured by dynamic viscoelasticity measurement (MCR301 manufactured by Anton Paar) under the conditions of 150°C, 1 Hz, 25 mmφ, aluminum parallel plates, 0.5 mm gap, is: A sample is placed on the aluminum parallel plate, the gap is set to 0.5 mm, and the time when the vibration of the aluminum parallel plate is started is defined as the measurement start time. The viscosity η1 one minute after the start of measurement is 40 Pa s or more and 1000 Pa s or less, A powder coating material having a ratio (η2 / η1) of the viscosity η2 after 2 minutes from the start of measurement to the viscosity η1 of the powder coating material of 6.0 or more and 100 or less.

2. 2. The powder coating material according to claim 1, wherein the viscosity η2 is 300 Pa·s or more and 10,000 Pa·s or less.

3. 3. The powder coating material according to claim 1, wherein the ratio (η3 / η1) of the complex viscosity η3 after 1.5 minutes from the start of measurement to the complex viscosity η1 is greater than 1 and less than or equal to 10.

4. 4. The powder coating material according to claim 1, wherein the complex viscosity η4 10 seconds after the start of measurement is 20 Pa·s or more and 40 Pa·s or less.

5. The particle diameter d of the thermosetting resin composition measured by a laser diffraction method 90 The powder coating material according to any one of claims 1 to 4, wherein the particle size is 50 µm or more and 200 µm or less.

6. The powder paint according to any one of claims 1 to 5, which is used in a powder coating method in which a molten powder paint is applied from the exposed portion of the coil end to the insulating coating.

7. A coil having the coil end, the exposed portion of which is sealed with the powder coating material according to claim 6.

8. The method includes a step of immersing a coil end of a coil in which a conductor portion is covered with an insulating coating and which has a coil end provided with an exposed portion where the conductor portion is exposed from the insulating coating, into a fluidized bath in which a powder paint flows, and adhering the molten powder paint to the outside of the exposed portion, A method for sealing a coil end, wherein the powder paint is the powder paint according to any one of claims 1 to 6.

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