JP4160041B2 - Insulating varnish impregnation method - Google Patents

Description

  The present invention relates to a method and apparatus for insulating a general industrial and consumer coil (motor, generator, etc.), and an insulating varnish impregnation treatment method in which a varnish impregnated in the coil is cured using current heating to the coil, and The present invention relates to an impregnation processing apparatus.

  Conventionally, in a stator coil or the like, varnish insulation processing is performed to protect the winding. By performing this insulation treatment, various functions such as insulation of the winding, physical support, transmission of heat generation to the slot wall, wire pinhole and processing flaw cover are imparted to the coil.

  The insulation treatment of the varnish includes, for example, a preheating process for preheating the coil, an impregnation process for impregnating the coil with the varnish, a curing process for heating and curing the varnish attached to the coil.

  At this time, as a method of impregnating the varnish into the coil, there are a dipping impregnation method (dipping), a dripping impregnation method (drip), a rotary impregnation method, a vacuum impregnation method, etc., and these methods are used and types of coils to be processed. , Depending on the process. Recently, electric appliances (motors, generators, etc.) have a large coil line area, taped outermost packaging, interstitial paper between the poles, and so on. (Penetration) is lowered and it is difficult to sufficiently impregnate, and various conditions have been studied in order to improve the impregnation property of the coil.

  By the way, although the insulation treatment varnish used for the impregnation of the coil is roughly classified into a solvent type varnish treatment and a solventless varnish treatment, most of the solvent varnish used in the immersion impregnation method has a nonvolatile content of 20 to 70% by mass. The remainder is volatile matter (solvent). At this time, in order to improve the varnish impregnation property, it is often used by further diluting with a solvent or the like, but in this case, the amount of resin that actually adheres to the winding is very small, and the desired adhesion amount is achieved by one impregnation. I can't do it.

  On the other hand, it is conceivable to increase the non-volatile content in order to increase the adhesion amount, but the viscosity of the varnish increases and impregnation becomes worse, and it becomes difficult to penetrate into the minute gaps between the windings in the slot. The amount of adhesion only on the surface will increase. In addition, it becomes difficult for the varnish to impregnate the inside of the slot or the inner side of the interphase paper, and the purpose of the varnish treatment cannot be achieved. In any case, in the drying process, the solvent contained in the total amount of varnish is scattered by 30% by mass or more, and the amount of resin adhering to the impregnated winding is reduced, or there are many voids inside the slot. Sometimes it became.

  In order to improve this, in order to increase the resin adhesion amount, when the coil is immersed in the varnish, the winding is energized and heated to cause the varnish to gel, and to the winding body A processing method for increasing the amount of varnish attached has been known (see, for example, Patent Document 1).

  On the other hand, solvent-free varnish may be used instead of solvent-type varnish. In this case, if the amount of varnish adhesion is increased, the viscosity of the varnish is increased to reduce the dripping flow, or the varnish curing speed is increased. It is possible to speed up. However, if the viscosity of the varnish is increased, it is difficult for the minute gaps between the windings in the slot to penetrate, and only the surface of the iron core increases. On the other hand, when the curing speed of the varnish is increased, the pot life of the varnish remaining in the container is shortened, which is very disadvantageous in terms of workability and economy.

The dripping impregnation method is a method developed to avoid the above-mentioned drawbacks, in which a preheated coil is rotated or rotated at an angle, and a varnish that hardens in a short time is dropped onto the winding from the top. It is. The varnish dripped onto the upper part of the winding penetrates between the windings by capillary action and does not gel until reaching the end of the winding, but hardens quickly after penetration. This method is an excellent method capable of adjusting the adhesion amount of the cured product, and is a method capable of thick coating by selecting a resin component.
JP-A-7-39120

  However, in a varnish using a diluent or a solvent, it is necessary to increase the temperature of the coil in the preheating process, and in the dropping impregnation process, it takes time to impregnate the varnish depending on the size, shape, presence or absence of interphase paper, etc. In the curing process, as with preheating, it is often heated with hot air, and it is clear from past results that it can be done faster with a far-infrared heater, but it is almost effective for coils with a weight of 2 kg or more. Cannot be obtained.

  As described above, the coil varnish impregnation process requires a great deal of time for the preheating, impregnation and curing processes, and for manufacturers of motors or generators, improvement of shortening the time of the varnish insulation treatment process is desired. It was rare.

  Although the invention that uses current heating in the preheating process described above is able to significantly reduce the time compared to the case of only hot air circulation up to that point, in the curing process, the solvent, diluent, etc. contained in the varnish The volatile components contained in the varnish of the product volatilize, and there is a risk of ignition due to sparks due to the heat of the coil or malfunction of the wire being energized. However, the reduction in time was limited.

  In addition, the method using solventless varnish requires delicate adjustments such as the amount of varnish dripping, heating temperature, rotation speed, and inclination angle of the varnish depending on the characteristics of the resin component and the type of the object to be processed. To do this, the equipment is very expensive. Moreover, since it takes a lot of time for preheating, dripping and curing, it is not always a good method. For this reason, it is advantageous to continuously insulate models of the same shape, but if the shapes are different, it is necessary to set processing conditions that match the shape. It was not necessarily suitable for production.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors can use current heating in the curing process by using a specific varnish, and can achieve a reduction in coil manufacturing time. The present invention has been completed by finding a coil insulation treatment method and insulation treatment apparatus that can be used.

  That is, the insulating varnish impregnation method of the present invention includes a coil preheating step for preheating an electric device coil comprising an iron core and a winding wound around the iron core, a varnish impregnation step for impregnating the coil with a varnish, and an impregnation step. Insulating varnish impregnation treatment method comprising a varnish curing step of heating and curing the varnish adhering to the coil, wherein the varnish contained in the varnish has a flash point of less than 150 ° C. is less than 1% by mass, and varnish curing The heating in the process is performed by energization heating of the coil.

  Further, the second insulating varnish impregnation method of the present invention includes a coil preheating step for preheating an electric device coil comprising an iron core and a winding wound around the iron core, and a varnish impregnation step for impregnating the coil with varnish. An insulating varnish impregnation treatment method comprising a varnish curing step of heating and curing the varnish adhering to the coil in the impregnation step, wherein a volatile component having a flash point of less than 150 ° C. contained in the varnish is less than 1% by mass The varnish impregnation step is characterized in that the impregnation is performed while the coil is energized and heated.

  Further, the insulating varnish impregnation processing apparatus of the present invention comprises a coil preheating means for heating an electric equipment coil comprising an iron core and a winding wound around the iron core, a varnish impregnation means for impregnating the coil with varnish, and a coil A varnish curing means for curing the varnish impregnated in the coil by energization heating of the coil, and a chuck mechanism capable of holding the coil and rotating the coil about the axis in the coil preheating means, the varnish impregnation means and the varnish curing means , Characterized by having.

  According to the coil insulation treatment method and the insulation treatment apparatus of the present invention, by using a specific varnish, the varnish can be efficiently cured using current heating to the coil in the curing step of the coil impregnation treatment. In addition, since there is little generation of highly flammable gas, there is less danger and workability can be improved.

  Hereinafter, the varnish impregnation processing method and impregnation processing apparatus of this invention are demonstrated, referring drawings.

(First embodiment)
First, the insulating varnish impregnation processing apparatus of the present invention will be described in detail with reference to FIGS. FIG. 1 is a diagram schematically showing the configuration of an insulating varnish impregnation apparatus, and FIG. 2 is a cross-sectional view showing a coil holding / rotating unit provided in the varnish impregnation apparatus of FIG.

  The varnish impregnation treatment apparatus 1 of the present invention includes a coil preheating means 2 for preheating a coil, a varnish impregnation means 3 for impregnating a coil with a varnish, a varnish hardening means 4 for hardening an attached varnish, and a varnish hardening means 4 energizing the coil. It is a batch-type apparatus composed of an electric heating means 5 that can be heated.

  The function of the varnish impregnation processing apparatus 1 is to rotate the stator coil 23 formed in a ring (circular tube) shape used for the stator of the motor (by rotating the rotating shaft 16 (in the S1 direction), the coil itself is also rotated). Rotating at the axis of the coil), a varnish, which is an insulating material, is dropped and impregnated into the winding portion (coil portion) 23a of the stator coil 23.

  The coil preheating means 2 heats the stator coil 23 and performs preheat treatment. At this time, the coil can be heated by a heating means such as an energization heating means, an induction heating means, or a hot air heating means. The varnish impregnation means 3 drops varnish onto the winding portion 23a of the stator coil 23 that has been preheated.

  The varnish curing means 4 heats and cures the varnish impregnated in the winding portion 23a of the stator coil 23. Here, an energization heating means 5 capable of energizing the coil winding portion 23a is provided. For example, a temperature sensor may be provided so that the coil is energized and heated via a lead wire and is not heated above a predetermined temperature. The varnish curing means 4 may be provided with a heating means by ultraviolet (UV) irradiation or hot air heating in addition to the energization heating means 5 and used together with the energization heating means.

  At this time, a varnish gelling means may be provided between the varnish impregnation means 3 and the varnish curing means 4 to heat the gel at a temperature lower than that of the curing means. By providing the varnish gelling means, it is possible to prevent the varnish impregnated in the coil from flowing down and out of the coil.

  In addition, it is preferable to provide a coil cooling means for cooling the stator coil 23 in which the varnish is heated and cured at the winding portion 23a after the varnish hardening means. The coil preheating means 2, the varnish hardening means 4 and the coil cooling means are provided in the coil cooling means. A plurality of fans may be provided as air conditioning equipment.

  As shown in FIG. 2, the coil holding / rotating unit 6 includes a chuck mechanism 21 that rotatably holds the stator coil 23 and a driving force transmission mechanism 20 that transmits power for driving the chuck mechanism 21. ing. The driving force transmission mechanism 20 is mainly provided with a pair of main bearings 11 and auxiliary bearings 15 that rotatably support a rotating shaft 12 described later, and a sprocket 14 that applies a rotating force to the rotating shaft 12.

  The pair of main bearings 11 and auxiliary bearings 15 are attached to the mounting base 10. A collar 13 for positioning the sprocket 14 is interposed between the pair of main bearings 11 on the mounting base 10. The sprocket 14 applies a rotational force that rotates the rotating shaft 12 in the direction of the arrow S1.

  The chuck mechanism 21 has a coil insertion member 22, and after inserting the coil insertion member 22 into the iron core 23 b, the coil can be chucked by switching the pressure contact state between the insertion member and the iron core. .

  Next, the insulating varnish impregnation method of the present invention will be described with reference to the insulating varnish impregnation apparatus 1 in FIG. 1 and the drawings showing the coil end impregnation method in FIG.

  First, in the preheating step, the coil can be heated to a temperature at which the coil preheating means 2 can remove moisture from the workpiece such as a chuck, improve the aryling, and improve the impregnation of the varnish, for example, about 90 to 110 ° C. At this time, the coil can be heated by a heating method such as energization heating, induction heating, or hot air heating, or can be combined and heated. The combination of heating methods is preferably energization + induction heating or energization + hot air heating.

  Next, in the varnish impregnation step, the preheated coil (stator) is cantilevered by the inner diameter chuck and the chuck is kept horizontal as shown in FIG. A varnish 31 is dropped from the nozzle 30 to impregnate the coil end. Accordingly, the inside of the interphase paper at the coil end can be impregnated with the varnish, and the varnish can be quickly and sufficiently impregnated into the slot.

  In this varnish impregnation step, the varnish can be impregnated by heating by energization heating to the coil. According to this method, gelation is performed to some extent in the impregnation step, and the amount of varnish attached can be increased. This is preferable because productivity can be improved. In addition, even if the electric heating is performed here, the varnish used in the present invention has a small amount of volatile components with a flash point of less than 150 ° C. of 1% by mass. Is excellent.

  After the impregnation, the coil proceeds to a varnish curing process, in which the varnish adhering to the coil is heated in the varnish curing means 4 to be completely cured. The heating temperature at this time is preferably about 100 to 170 ° C., and this heating is performed by conducting current heating to the coil using the current heating means 5. By performing the electric heating, the curing process can be completed in a shorter time than the conventional heating method.

  Furthermore, in the past, it was difficult to adopt a complete explosion-proof structure with the current heating method and the induction heating method, and it could not be used for the curing process of the insulating varnish, but the present invention has a volatile component with a flash point of less than 150 ° C. Since less than 1% by mass of varnish is used, it is possible to cure safely and quickly even when energized and heated before entering the curing process.

  In this varnish curing process, in addition to energization heating, it is also possible to perform heating (energization + hot air heating, UV + energization heating) in combination with UV irradiation and hot air heating. It is preferable in that the curing time can be further shortened compared to that used in the above, and it is also possible to carry out a combination of energization heating, UV irradiation, and hot air heating.

  Moreover, as a varnish used for the varnish impregnation processing method of this invention, both a solvent-free varnish and a water-soluble varnish can be used, and unless it is contrary to the objective of this invention, it will not specifically limit. Specifically, the insulating varnish used in the present invention is a resin composition in which the content of a volatile component having a flash point of less than 150 ° C. is less than 1% by mass in the varnish, and almost no gas is generated in the curing step. It is.

  Examples of the resin component (A) of the insulating varnish used in the present invention include resin components that are usually used as varnishes for impregnation such as unsaturated polyester resins and epoxy ester resins, and are epoxy ester resins from the viewpoint of heat resistance. It is preferable.

  The unsaturated polyester resin used as the resin component of the varnish can be obtained by reacting an acid component containing an unsaturated dibasic acid with an alcohol component.

  Acid components used here include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, adipic acid and other fatty acids, soybean oil fatty acid, linseed oil fatty acid, The thing which mixed multiple types of fatty acids, such as a coconut oil fatty acid, tall oil fatty acid, rice bran oil fatty acid, is mentioned, These can be used individually or in mixture of 2 or more types.

  The alcohol component used here is propylene glycol, neopentyl glycol, 1,4-butadienediol, 1,6-hexanediol, 1,6-cyclohexanedimethanol, glycerol monoallyl ether, trimethylolpropane monoallyl ether, pentaerythritol. Examples include dihydric alcohols such as diallyl ether, trivalent or higher alcohols such as glycerin, trimethylolpropane, tris-2-hydroxyethyl isocyanurate, pentaerythritol triallyl ether, and these are used alone or in combination of two or more. can do.

  The epoxy ester resin used here is obtained by reacting an acid component and an epoxy component with an esterification catalyst. Examples of the acid component used here include unsaturated monobasic acids such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and sorbic acid, and phthalic acid, phthalic anhydride, isophthalic acid, hexahydrophthalic anhydride as necessary. A dibasic acid such as acid or adipic acid can be mixed and used.

  Any epoxy component may be used as long as it has two or more epoxy groups in one molecule, and the molecular structure, molecular weight and the like are not particularly limited and can be widely used. Specific examples include epoxy resins having aromatic groups such as bisphenol type, novolac type, and biphenyl type, epoxy resins obtained by glycidyl etherification of polycarboxylic acid, and alicyclic epoxy resins obtained by condensation of cyclohexane derivatives and epoxy. These can be used alone or in admixture of two or more.

  The (B) air drying resin of the insulating varnish used in the present invention can be used without limitation as long as it contains an unsaturated group having air drying properties. An epoxy ester resin having an allyl group in the chain is preferred.

  The (C) reactive diluent of the insulating varnish used in the present invention is mainly composed of a flash point of 150 ° C. or higher, and the reactive diluent having a flash point of less than 150 ° C. is less than 1% by mass in the varnish. There is only an amount that is a content ratio.

  Examples of the reactive diluent having a flash point of 150 ° C. or more used in the present invention include polyalkylene oxide diacrylate derivatives having a number average molecular weight of 250 to 2000, such as diethylene glycol di (meth) acrylate (flash point 150 ° C.), Examples include ethylene glycol di (meth) acrylate (flash point 155 ° C.) and tetraethylene glycol di (meth) acrylate (flash point 162 ° C.).

  Methanol (flash point 16 ° C), toluene (flash point 7 ° C), xylene (flash point 29 ° C) and monomer styrene (flash point 32 ° C), vinyl toluene, which are diluents used in conventional insulating varnishes (Flash point 50 ° C.), acrylic monomer; 2HEMA (flash point 99 ° C.) and the like generate a combustible gas when the coil is cured, and are therefore dangerous in the present invention using current heating.

  Next, the (D) organic peroxide of the insulating varnish used in the present invention is blended in order to cure the resin component, for example, benzoyl peroxide, t-butyl peroxide, acetyl peroxide. . Examples thereof include methyl ethyl ketone peroxide, acyl peroxide, cumene peroxide and the like, and these can be used alone or in combination of two or more.

  In addition to this, the varnish also contains a curing accelerator such as a metal salt of naphthenic acid or octylic acid, a polymerization inhibitor such as hydroquinone, methoquinone, pt-butylcatechol, pyrogallol, silica powder, alumina powder, if necessary. Further, metal oxide powder such as magnesia powder, metal hydroxide powder such as aluminum hydroxide and magnesium hydroxide, colorant, anti-settling agent, and the like can be mixed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram illustrating a method for impregnating coil ends, and is a diagram illustrating impregnation using both immersion and dripping.

  In this embodiment, the varnish impregnation means 3 is provided with a varnish immersion tank 32, and is the same as that of the first embodiment except that the impregnation method in the varnish impregnation step is different.

  In the varnish impregnation step in the second embodiment, the varnish is impregnated so that the coil that has been held horizontally in the other steps so far is held vertically only in the impregnation step. In order to achieve such verticality, a joint can be provided on the shaft 12 that supports the coil, and the joint can be bent when entering the varnish impregnation process. As a result, the coil itself can be continuously rotated.

  In this way, a dipping impregnation method is used in which the coil is held vertically and one coil end is immersed in the varnish in the varnish impregnation tank, and the other coil end is dripped with the varnish 31 from the nozzle 30. By impregnating each with varnish, it is possible to obtain a coil having a good impregnation property that takes advantage of the respective advantages of the conventional immersion impregnation method and the drop impregnation method. That is, by this method, the varnish is also impregnated inside the interphase paper of both coil ends, and the varnish can be impregnated quickly and sufficiently into the slot.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In this embodiment, in the insulating varnish impregnation processing apparatus of FIG. 1, the energization heating means 5 is connected to the varnish impregnation means 3 instead of the varnish curing means 4. The only difference is that

  In this embodiment, the coil is energized and heated in the varnish impregnation step, and the varnish curing step is performed using UV irradiation and hot air heating. Such a configuration is preferable in that the gelation can be performed to some extent in the impregnation step, and the amount of varnish attached can be increased, so that productivity can be improved. However, the varnish used in the present invention has a low volatile component having a flash point of less than 150 ° C., which is as low as 1% by mass.

  In the case of not only the batch type described in the first to third embodiments of the present invention but also the continuous type, the varnish impregnation property to the coil is improved by the same method, and the insulating varnish is safe and has high productivity. Can be obtained.

  Hereinafter, the present invention will be described with reference to examples.

(Example 1)
In this example, the impregnation treatment was performed using the varnish impregnation method of FIG. 4 using the varnish impregnation treatment apparatus of FIG. First, a coil having a winding diameter of 0.8 mm, a line area ratio of 70%, and a coil having a total weight of 12 kg is preheated to 100 ° C. by energization heating and induction heating, and the preheated coil is impregnated with varnish A and the varnish A adheres to the coil. Was heated to 130 ° C. by energization heating and UV heating, cured to obtain a coil impregnated with an insulating coil.

(Examples 2-6, Comparative Examples 1-4)
The coil was impregnated by the same operation as in Example 1. In each Example and Comparative Example, the varnish used, the preheating method, the impregnation method, and the curing method are shown in Tables 1 and 2. The characteristics and configuration of the varnishes A and B used are as follows.

[Varnish A]: Viscosity 5 poise, gel time 240 seconds, manufactured by Kyocera Chemical Co., Ltd., TVB2470 (main agent) / TEC9637K (curing agent) mixed at 100/1. (Synthesized by adding hydroquinone to soybean oil fatty acid, dicyclopentadiene, ethylene glycol) and air-drying resin (Neopol 8414), reactive diluent (triethylene glycol di (meth) acrylate: flash point 192 ° C), naphthene Manganese acid, leveling agent and antifoaming agent are added.

[Varnish B]: Viscosity 2 poise, gel time 180 seconds, manufactured by Kyocera Chemical Co., Ltd., TVB2122 (main agent) / TEC9620 (curing agent) mixed at 100/1. (Synthesized by adding hydroquinone to soybean oil fatty acid, dicyclopentadiene, ethylene glycol), air drying resin (Neopol 8414), reactive diluent (styrene: flash point 32 ° C.), manganese naphthenate, leveling agent, extinction A foaming agent is added.

In addition, the energization output in the energization heating was 150 A, the dielectric output in the induction heating was 45 kW, the UV intensity in the UV heating was 312 nm, 860 μW / cm ² , and the hot air temperature in the hot air heating was 150 ° C.

(Test example)
About the coil obtained by the insulation process by the Example and the comparative example, the process external appearance, the amount of varnish adhesion, and the interphase paper impregnation state were evaluated, and each coil was evaluated. The results are shown in Tables 1 and 2.

[Varnish viscosity]
Using a BL type viscometer, the measurement was performed under the conditions of 25 ° C. and 60 rpm.

[Geltime]
The measurement was performed at a measurement temperature of 120 ° C. according to the measurement method of JIS C 2105.

[Coil processing appearance]
Based on visual appearance, it was determined according to the following criteria.
○: Cured, ×: Uncured part was seen

[Varnish adhesion amount]
The coil weight before and after coating was measured and calculated from the difference.

[Impregnated phase paper]
Based on visual appearance, it was determined according to the following criteria.
○: Completely impregnated, △: Some voids, ×: Many voids

  By the Example, it turned out that a coil with much varnish adhesion amount and a good external appearance can be obtained in a short manufacturing time by performing the heat curing in the curing process by energizing heating to the coil using a specific varnish.

  Note that the combination of energization + induction heating or energization + hot air heating for preheating, the method of FIG. 4 (dip + drip) for the impregnation process, and the combination of energization + hot air heating, UV + electric heating, UV + hot air heating for the curing process is varnish. This is preferable in terms of improving the adhesion amount, manufacturing time, and coil appearance. Further, by incorporating the method of FIG. 4 (dip + drip), the varnish impregnation property on the inner side (V layer) of the interphase paper was also improved. Based on the above, it was found that the most preferable impregnation treatment method was preheating for energization + induction heating, impregnation for the method shown in FIG. 4 (dip + drip), and curing for UV + current heating.

The figure which showed roughly the composition of the insulation varnish impregnation processing equipment Sectional drawing which showed the coil holding and rotation unit with which the varnish impregnation apparatus of FIG. Diagram showing impregnation method of coil end Diagram showing impregnation method of coil end

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulation varnish impregnation processing apparatus, 2 ... Coil preheating means, 3 ... Varnish impregnation means, 4 ... Varnish hardening means, 6 ... Coil holding | maintenance / rotation unit, 12 ... Rotary shaft, 20 ... Driving force transmission mechanism, 21 ... Chuck mechanism 22 ... Coil insertion member, 23 ... Stator coil, 23a ... Winding part (coil part), 23b ... Iron core, 30 ... Nozzle, 31 ... Varnish, 32 ... Varnish immersion bath

Claims (9)

A coil preheating step for preheating an electric device coil comprising an iron core and a winding wound around the iron core, a varnish impregnation step for impregnating the coil with varnish, and heating the varnish adhering to the coil by the impregnation step. An insulating varnish impregnation treatment method comprising a varnish curing step for curing,
The insulating varnish impregnation method, wherein a volatile component having a flash point of less than 150 ° C. contained in the varnish is less than 1% by mass, and heating in the varnish curing step is performed by energization heating of a coil.   2. The insulating varnish impregnation method according to claim 1, wherein the heating in the varnish curing step is performed by UV heating and energization heating.   2. The insulating varnish impregnation method according to claim 1, wherein the heating in the varnish curing step is performed by hot air heating and energization heating.   2. The insulating varnish impregnation method according to claim 1, wherein the heating in the varnish curing step is performed by hot air heating, UV heating and energization heating.   The insulating varnish impregnation method according to any one of claims 1 to 4, wherein the impregnation step is performed while the coil is energized and heated. A coil preheating step for preheating an electric device coil comprising an iron core and a winding wound around the iron core, a varnish impregnation step for impregnating the coil with varnish, and heating the varnish adhering to the coil by the impregnation step. An insulating varnish impregnation treatment method comprising a varnish curing step for curing,
The insulating varnish impregnation method, wherein a volatile component having a flash point of less than 150 ° C. contained in the varnish is less than 1% by mass, and the varnish impregnation step impregnates the coil while energizing and heating.   The insulating varnish impregnation method according to any one of claims 1 to 6, wherein the resin component of the varnish is an unsaturated polyester varnish or an epoxy ester resin and does not contain styrene.   The varnish comprises (A) an epoxy ester resin, (B) an air-drying resin, (C) a reactive diluent, and (D) an organic peroxide as essential components, The insulating varnish impregnation method according to claim 7, wherein the reactive diluent (C) has a flash point of 150 ° C or higher.   9. The insulating varnish impregnation method according to claim 8, wherein the reactive diluent (C) is a diacrylate derivative of polyalkylene oxide having a number average molecular weight of 250 to 2,000.

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