JP5832402B2 - Insulating film, stator coil and gas insulated switchgear - Google Patents

Description

  The present invention relates to an insulating film and a method for forming the same, a stator coil, and a gas insulated switchgear.

  In devices such as gas insulated switchgears, high voltage devices, and rotating machines (small, medium, and large), insulating films are formed on the surfaces of various members in order to insulate the various members. For example, in a gas insulated switchgear, a stator coil (conductor) is disposed inside a hermetically sealed metal container, and sulfur hexafluoride gas (SF6) is generally used as an insulating medium, but its dielectric strength is improved. For this purpose, an insulating film is formed on the surface of the stator coil. This insulating film is generally formed by applying a powder coating containing an epoxy resin by a powder coating method such as a fluid dipping method or an electrostatic coating method. However, although the powder coating method is suitable for forming a thin insulating film, it is not suitable for forming a thick insulating film. For example, in the powder coating method, as the insulating coating becomes thicker, the powder coating becomes difficult to melt, and as a result, the powder coating falls off before the powder coating melts and adheres to the object to be coated. Is difficult. Even if the powder coating does not fall off, the powder coating does not melt sufficiently, and defects such as voids are likely to occur in the insulating film.

As a method for forming a thick coating film, Patent Document 1 surrounds the surface of an object to be coated with a frame body having a height required for the thickness of the coating film, and applies a powder coating material on the object to be coated in the frame body. A method of filling and melting is proposed.
On the other hand, Patent Document 2 proposes a method for forming a coating film in which a fluororesin and a polyester resin are separated from each other by using a powder coating material containing a fluororesin, a polyester resin, and a filler (pigment). doing.

Japanese Patent Laid-Open No. 2-160082 JP 2011-12119 A

  However, in the method of Patent Document 1, it is necessary to provide a frame corresponding to the surface of an object to be coated, and when the object to be coated has a shape other than a plane (for example, a cylindrical shape), as shown in FIG. In addition, dripping of the melted powder paint occurs when heated, and a uniform coating film cannot be formed. In addition, since the thermal expansion coefficient of the two separated layers is different in the method of Patent Document 2, the two layers are easily separated and the filler is not uniformly dispersed in the coating film.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a uniform and thick insulating film that can be formed without dripping the paint and a method for forming the same.

As a result of diligent research to solve the above problems, the present inventors have applied a specific paint that hardens faster than the powder paint on the surface and then cured the paint. The present inventors have found that it is possible to prevent the powder coating from sagging and achieve both uniformity and thickening of the insulating film.
That is, the present invention comprises an inner layer that is a powder coating film formed from a powder coating material, and an outer layer that is a coating film formed on the inner layer and formed from a coating material that cures faster than the powder coating material. An insulating film having a feature that the coating material forming the outer layer is a photo-curable coating material containing a vinyl compound .
The present invention also includes an inner layer that is a powder coating film formed from a powder coating, and an outer layer that is a coating film formed on the inner layer and formed from a coating that cures faster than the powder coating. The coating film forming the outer layer is a thermosetting paint containing at least one amine compound selected from the group consisting of diethylaminopropylamine, isophoroneamine and m-xyleneamine. Is an insulating film characterized by

  ADVANTAGE OF THE INVENTION According to this invention, the uniform and thick insulating film which can be formed without producing dripping of a coating material, and its formation method can be provided.

2 is a cross-sectional view of the insulating film of the first embodiment. FIG. It is a side view of the coating film formed by the conventional powder coating method.

Embodiment 1 FIG.
Hereinafter, preferred embodiments of an insulating film and a method for forming the same according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of the insulating film of the present embodiment. In FIG. 1, the insulating film of the present embodiment is formed on an object to be coated 1, an inner layer 2 that is a powder coating film formed from a powder coating material, and a powder provided on the inner layer 2. And an outer layer 3 that is a coating film formed from a paint that cures faster than the paint.
It does not specifically limit as a powder coating material used for the inner layer 2, A well-known thing can be used in the said technical field. Here, “powder coating material” in this specification means a coating material in a powder state at room temperature (25 ° C.).

A preferable powder coating used for the inner layer 2 includes a base resin, a curing agent, and a filler.
The base resin is not particularly limited as long as it is in a solid state at room temperature (25 ° C.), and is generally an epoxy resin. Examples of the epoxy resin include, but are not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, brominated bisphenol A type epoxy resin, brominated bisphenol F type epoxy resin, brominated bisphenol AD. Bisphenol epoxy resin such as epoxy resin; alicyclic epoxy resin such as brominated alicyclic epoxy resin; phenol novolac epoxy resin, cresol novolac epoxy resin, brominated phenol novolac epoxy resin, brominated cresol novolak type A novolac type epoxy resin such as an epoxy resin may be used. These epoxy resins can be used individually or in mixture of 2 or more types.

  Since the weight average molecular weight of the base resin varies depending on the type of base resin used, it cannot be uniquely defined. The weight average molecular weight of the base resin may be in a range that becomes a solid state at room temperature (25 ° C.). Here, “weight average molecular weight” in the present specification means a value determined by gel permeation chromatography (GPC).

  It does not specifically limit as a hardening | curing agent, What is necessary is just to select suitably according to the base resin to be used. Examples of the curing agent include carboxylic acid anhydrides, amide compounds, phenol compounds, and imidazole compounds. These curing agents can be used alone or in admixture of two or more.

Examples of carboxylic anhydrides include aromatics such as phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol trimellitic anhydride, biphenyltetracarboxylic anhydride Carboxylic anhydrides; anhydrides of aliphatic carboxylic acids such as azelaic acid, sebacic acid, dodecanedioic acid; tetrahydrophthalic anhydride, hexahydrophthalic anhydride, nadic acid anhydride, chlorendic anhydride, highmic acid anhydride And alicyclic carboxylic acid anhydrides. These can be used individually or in mixture of 2 or more types.
The compounding amount of the carboxylic acid anhydride is such that the equivalent ratio of carboxyl group to a specific functional group of the base resin (for example, epoxy group of epoxy resin) is generally 0.3 or more and 1.5 or less, preferably 0.5 or more and 1 The amount is 2 or less. When the equivalent ratio is less than 0.3, the heat resistance is lowered, and when the equivalent ratio is more than 1.5, the pot life tends to be shortened.

Examples of the amide compound include dicyandiamide.
The compounding amount of the amide compound is such that the equivalent ratio of the amide group to a specific functional group (for example, epoxy group of the epoxy resin) of the base resin is generally 0.2 or more and 2.0 or less, preferably 0.3 or more and 1.5 or less. The amount is as follows. When the equivalent ratio is less than 0.2, the heat resistance is lowered, and when the equivalent ratio is greater than 2.0, the pot life tends to be shortened.

Examples of phenolic compounds include bisphenol A, bisphenol F, bisphenol S, 4,4′-biphenylphenol, 2,2′-methylene-bis (4-methyl-6-tert-butylphenol), 2,2′-methylene. -Bis (4-ethyl-6-tert-butylphenol), 4,4'-butylene-bis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-) 5-tert-butylphenol), trishydroxyphenylmethane, pyrogallol, phenols having a diisopropylidene skeleton, phenols having a fluorene skeleton such as 1,1-di-4-hydroxyphenylfluorene, and polyphenol compounds such as phenolized polybutadiene , Various novolak resins and this And halides of these phenol compounds. These can be used individually or in mixture of 2 or more types. Here, examples of various novolak resins include novolak resins and xylylene skeletons made from various phenols such as phenol, cresols, ethylphenols, butylphenols, octylphenols, bisphenol A, bisphenol F, bisphenol S, and naphthols. And a phenol novolak resin containing a dicyclopentadiene skeleton, a phenol novolak resin containing a fluorene skeleton, and the like.
The compounding amount of the phenol compound is such that the equivalent ratio of hydroxyl group to a specific functional group of the base resin (for example, epoxy group of epoxy resin) is generally 0.2 or more and 2.0 or less, preferably 0.3 or more and 1.5 or less. The amount is such that When the equivalent ratio is less than 0.2, the heat resistance is lowered, and when the equivalent ratio is greater than 2.0, the pot life tends to be shortened.

Examples of imidazole compounds include 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl. 2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 2,4-diamino-6 (2′-methylimidazole (1 ′ )) Ethyl-s-triazine, 2,4-diamino-6 (2′-undecylimidazole (1 ′)) ethyl-s-triazine, 2,4-diamino-6 (2′-ethyl, 4-methyl) Imidazole (1 ′)) ethyl-s-triazine, 2,4-diamino-6 (2′-me Ruimidazole (1 ')) ethyl-s-triazine isocyanuric acid adduct, 2-methylimidazole isocyanuric acid 2: 3 adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-3,5-dihydroxy Examples include methylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, and 1-cyanoethyl-2-phenyl-3,5-dicyanoethoxymethylimidazole. These can be used individually or in mixture of 2 or more types.
The amount of the imidazole compound is generally 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, with respect to 100 parts by mass of the base resin. When the blending amount is less than 0.01 parts by mass, curing becomes insufficient, and when the blending amount is more than 10 parts by mass, the pot life tends to be shortened.

  The filler is not particularly limited, and those known in the technical field can be used. Examples of the filler include inorganic fillers such as alumina, calcium carbonate, and silica; and organic fillers such as polyamide resin. In particular, when an inorganic filler is blended, the linear expansion coefficient of the coating film becomes close to the linear expansion coefficient of the article 1 to be coated, and the adhesion between the coating film and the article 1 can be improved. Moreover, if an organic filler is mix | blended, the stress relaxation of a coating film can be improved and the adhesiveness of a coating film and the to-be-coated article 1 can be improved.

  In addition to the above components, the powder coating material may contain additional components such as a colorant, a coupling agent, a leveling agent, a lubricant, and a stress relaxation agent as necessary. These components are not particularly limited, and those known in the art can be used. Moreover, the compounding quantity of these components will not be specifically limited if it is a range which does not inhibit the effect of this invention.

  A powder coating material can be manufactured by a well-known method using said component. For example, the above components are first dry-mixed using a mixing device such as a mixer or a blender, and then melt-kneaded and cooled using a kneader or the like. Thereafter, the kneaded product is pulverized using a mechanical or airflow pulverizer and then classified using a classifier, whereby a powder coating material having a specific size can be obtained.

  The average particle diameter of the powder coating material thus produced is preferably 0.05 to 1.5 times the thickness of the powder coating film (inner layer 2) to be formed, and generally 30 μm or more. 100 μm or less. Here, the “average particle diameter” in the present specification is a value obtained by measuring the ratio of passing through the openings using several sieves having different openings, or a value measured using a laser diffraction measurement device. Means. In addition, when an average particle diameter is measured using a sieve, let the value in the case of a particle size of integrated value 50% be an average particle diameter. When the average particle diameter of the powder coating is less than 0.05 times the thickness of the powder coating film to be formed, it may take too much time to form the powder coating film. On the other hand, when the average particle diameter of the powder coating exceeds 1.5 times the thickness of the powder coating film to be formed, the powder coating may fall off from the article 1 to be coated.

The coating material used for the outer layer 3 is not particularly limited as long as it is a coating material that cures faster than the powder coating material used for the inner layer 2, and those known in the technical field can be used. Moreover, the form of the coating material used for the outer layer 3 is not particularly limited, and may be powder, liquid, or a combination thereof.
A preferable paint used for the outer layer 3 is a thermosetting paint or a photocurable paint.

The thermosetting coating used for the outer layer 3 is not particularly limited as long as it contains a component that cures faster than the powder coating used for the inner layer 2.
A preferred thermosetting paint used for the outer layer 3 contains an amine compound.
It does not specifically limit as an amine compound, A well-known thing can be used in the said technical field. Examples of amine compounds include chain aliphatic amines, cycloaliphatic amines and aromatic amines. These can be used alone or in combination of two or more.

Examples of chain aliphatic amines include diethylenetriamine (DTA), triethylenetetramine (TTA), tetraethylenepentamine (TEPA), dipropylenediamine (DPDA), diethylaminopropylamine (DEAPA), AMINE 248, and the like. .
Examples of cycloaliphatic amines include N-aminoethylpiperazine (N-AEP), Temirone C-260, Araldit HY-964, Mensendiamine (MDA), Isophoronediamine (IPDA), S Cure 211, S Cure 212, Wandamine HM, 1.3 BAC and the like.
Examples of aromatic amines include m-xylenediamine (m-XDA), shoamine X, amine black, shoamine black, shoamine N, shoamine N1001, shoamine N1010, metaphenylenediamine (MPDA), diaminodiphenylmethane (DDM), diaminodiphenylsulfone (DDS) and the like.
Among the above various amine compounds, diethylaminopropylamine, isophoroneamine, and m-xyleneamine are preferable.

When the thermosetting paint is in powder form, the thermosetting paint can further include a base resin, a curing agent, and a filler. As the base resin, the curing agent, and the filler used for the powdery thermosetting paint, the same materials as those used for the powder paint used for the inner layer 2 can be used.
When the thermosetting paint is in a liquid state, the thermosetting paint can further include a base resin, a curing agent, and a filler. As the base resin used in the thermosetting paint, a base resin in a liquid state at room temperature (25 ° C.) may be used in order to make the thermosetting paint liquid.

The base resin in a liquid state at room temperature (25 ° C.) is not particularly limited, and is generally an epoxy resin. Examples of the epoxy resin include, but are not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, brominated bisphenol A type epoxy resin, brominated bisphenol F type epoxy resin, brominated bisphenol AD. Bisphenol type epoxy resin such as epoxy resin; alicyclic epoxy resin and brominated alicyclic epoxy resin; phenol novolac type epoxy resin, cresol novolac type epoxy resin, brominated phenol novolak type epoxy resin, brominated cresol novolak type epoxy resin Examples thereof include novolak type epoxy resins such as resins. These resins can be used alone or in admixture of two or more.
Since the weight average molecular weight of the base resin in a liquid state at normal temperature varies depending on the type of base resin used, it cannot be uniquely defined. Therefore, the weight average molecular weight of the base resin is not particularly limited as long as it is in a range in which it becomes a liquid state at room temperature (25 ° C.).
Moreover, as a hardening | curing agent and filler used for this liquid thermosetting coating material, the same thing as what is used with the powder coating material used for the inner layer 2 can be used.

  When using a thermosetting paint containing a base resin, a curing agent, and a filler, the compounding ratio of the amine compound is generally such that the equivalent ratio of the amine group to a specific functional group of the base resin (for example, epoxy group of the epoxy resin) The amount is from 0.2 to 2.0, preferably from 0.3 to 1.5. When the equivalent ratio is less than 0.2, the heat resistance is lowered, and when the equivalent ratio is greater than 2.0, the pot life tends to be shortened.

The thermosetting paint may contain a reactive diluent, a curing catalyst, a filler, a colorant, a coupling agent, a leveling agent, a lubricant, a stress relaxation agent, and the like as necessary in addition to the above components. it can.
A thermosetting paint can be manufactured by a well-known method using said component. For example, when preparing a powdery thermosetting paint, first, the above components are dry-mixed using a known mixing device such as a mixer or a blender, and then melt-kneaded using a kneader or the like and cooled. Thereafter, the kneaded material may be pulverized using a mechanical or airflow pulverizer. Moreover, what is necessary is just to mix the said component using well-known mixing apparatuses, such as a mixer and a blender, when preparing a liquid thermosetting coating material.

  Alternatively, a liquid thermosetting paint in which an amine compound is dissolved in an organic solvent may be used. The organic solvent is not particularly limited as long as it is a highly volatile solvent, and methyl ethyl ketone, acetone, tetrahydrofuran, toluene, xylene, methyl isobutyl ketone, and the like can be used. These can be used alone or in combination of two or more. In this case, the compounding amount of the amine compound in the thermosetting coating is generally 20% by mass to 80% by mass, preferably 30% by mass to 70% by mass, and more preferably 40% by mass to 60% by mass. Moreover, this thermosetting coating material can contain a well-known additive in the range which does not inhibit the effect of this invention.

  The curing temperature of the thermosetting paint used for the outer layer 3 is preferably 10 ° C. or more, more preferably 20 ° C. or more lower than the curing temperature of the powder paint used for the inner layer 2. When the difference in the curing temperature is less than 10 degrees, dripping of the powder coating applied to form the inner layer 2 may occur during heat curing, and a uniform insulating film may not be obtained.

The photocurable coating used for the outer layer 3 is not particularly limited as long as it contains a photocurable compound. For example, any photocurable paint may be used as long as it contains a vinyl compound having one or more radical polymerizable double bonds.
The curing wavelength of the photocurable coating is not particularly limited, but is preferably 400 nm or less from the viewpoint of workability.

  Examples of vinyl compounds include esters of acrylic acid or methacrylic acid (eg, methyl acrylate, ethyl acrylate, n- or tert-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, benzyl acrylate, 2-hydroxyethyl Acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, ethylene diacrylate, neopentyl diacrylate, trimethylolpropane tris acrylate, pentaerythritol tetraacrylate, pentaerythritol tris acrylate), acrylonitrile, methacrylonitrile, acrylamide, methacrylamide N-substituted (meth) -acrylamides, vinyl esters (e.g. Vinyl acid, vinyl propionate, vinyl acrylate, vinyl succinate), vinyl ether, styrene, alkylstyrene, halogenostyrene, divinylbenzene, vinylnaphthalene, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, allyl compounds (for example, diallyl phthalate, Diallyl maleate, triallyl isocyanurate, triallyl phosphate) and the like. These can be used alone or in combination of two or more.

The photocurable coating can further contain a photopolymerization initiator, an organic solvent, and various additives (stabilizers, fillers, pigments, etc.) as necessary.
The mixing ratio of each of the above components in the photocurable coating is not particularly limited, and may be adjusted as appropriate according to the components used.
The photocurable coating can be produced by a known method using the above-described components in the same manner as in the case of the thermosetting coating.
Moreover, you may use what is marketed as a photocurable coating material.

In the insulating film of the present embodiment, a powder coating for forming the inner layer 2 is applied to the surface of the article 1 and then the coating for forming the outer layer 3 is applied to the surface and cured. Can be formed.
It does not specifically limit as a coating method, A well-known coating method can be used. For example, for powder coatings, methods such as electrostatic coating, fluid dipping, and electrostatic fluid dipping can be used. Moreover, about liquid coating materials, methods, such as brush coating, spray coating, and immersion coating, can be used.

The coating of the powder coating material for forming the inner layer 2 may be performed only once to form a single layer, but may be performed multiple times to form a multilayer. In applying the powder coating material, it is preferable to heat the object to be coated 1 from the viewpoint of melting the powder coating material and fixing it to the object to be coated 1. The heating temperature of the article 1 is not particularly limited, and may be set as appropriate according to the type of powder coating used. Generally, the said heating temperature is 100 degreeC or more and 240 degrees C or less.
The coating of the paint for forming the outer layer 3 may be performed only once to form a single layer, or may be performed multiple times to form a multilayer. Also in the case of applying this paint, it is preferable to heat the article 1 from the viewpoint of adhesion of the paint.
Other conditions (for example, the coating time) in each of the above coatings may be appropriately adjusted according to the desired film thickness, the coating apparatus to be used, and the type of paint, and are not particularly limited.

  If the yield value of the paint for forming the outer layer 3 is smaller than the stress due to gravity, the paint may sag. Therefore, from the viewpoint of suppressing the sagging of the paint, the paint for forming the outer layer 3 preferably has a yield value larger than the stress due to gravity.

  When a thermosetting paint is used as a paint for forming the outer layer 3, each paint film is sufficiently cured by performing a heat treatment after the paint is applied. The heating conditions at this time are not particularly limited, and may be set as appropriate according to the type of paint used. In general, the heating temperature is from 100 ° C. to 240 ° C., and the heating time is from 10 minutes to 3 hours.

  When a photocurable paint is used as a paint for forming the outer layer 3, the photocurable paint is first cured by light irradiation after the photocurable paint is applied. Then, the powder coating material for forming the inner layer 2 is fully hardened by performing heat treatment. The conditions of light irradiation and heating are not particularly limited, and may be set as appropriate according to the type of photocurable paint to be used. Generally, the wavelength of irradiation light is 400 nm or less. The heating temperature is 100 ° C. or more and 240 ° C. or less, and the heating time is 10 minutes or more and 3 hours or less.

The insulating film formed as described above is a powder coating material for forming the inner layer 2 because the coating material for forming the outer layer 3 is cured before the powder coating material for forming the inner layer 2. Is prevented by the outer layer 3 from melting and dripping, and the insulating film can be made uniform and thick.
The thickness of the insulating film to be formed is not particularly limited, but is preferably 1 mm or more, more preferably 1.2 mm or more and 5 mm or less. In addition, defects such as voids existing in the formed insulating film are generally 5 pieces / mm ² or less.

  The object 1 to be coated with the powder coating material for forming the inner layer 2 is not particularly limited, and examples thereof include metal materials such as steel materials and aluminum materials, glass, concrete, and special resins. Moreover, it does not specifically limit as a shape of the to-be-coated object 1, It can be various shapes, such as a column shape and a rectangular parallelepiped. In particular, according to this method, it is possible to form a uniform and thick insulating film without causing dripping of the paint, even on a complicated three-dimensional object 1 that is liable to dripping. When the object to be coated 1 has a complicated three-dimensional shape, the gravity applied to the paint is made uniform by rotating and reversing the object to be coated 1 during the above-described coating and heat treatment. , The effect of preventing the dripping of the paint is enhanced.

  Since the insulating film of this embodiment is uniform, thick, and excellent in insulation, it is an insulating material that insulates various members in devices such as gas-insulated switchgears, high-voltage devices, and rotating machines (small, medium, and large). Can be used as a membrane. In particular, this insulating film is optimal for forming on the surface of the stator coil of a gas insulated switchgear using sulfur hexafluoride gas (SF6) as an insulating medium.

EXAMPLES Hereinafter, although an Example demonstrates the detail of this invention, this invention is not limited by these.
Example 1
100 parts by mass of epoxy resin A (bisphenol A type epoxy resin solid at normal temperature, weight average molecular weight 1150), 30 parts by mass of epoxy resin B (cresol novolac type epoxy resin solid at normal temperature, weight average molecular weight 1400), curing agent A ( 7 parts by mass of dicyandiamide), 3 parts by mass of curing agent B (imidazole), and 15 parts by mass of filler (alumina) were dry-mixed using a mixer and then melt-kneaded using a biaxial kneader. Next, after the obtained kneaded material was cooled and solidified, it was pulverized using a pulverizer and classified using a classifier to obtain a powder coating material A having an average particle diameter of 40 μm. The powder coating A had a curing start temperature of 120 ° C.
On the other hand, a powder coating material B having an average particle size of 40 μm was obtained using the same components and methods as above except that 10 parts by mass of diethylaminopropylamine was further added. The powder coating B had a curing start temperature of 80 ° C.

Next, using the electrostatic coating method, the above-described powder coating A was applied to the surface of an object to be coated (cylindrical conductor, length 1000 mm × diameter 50 mm). At this time, the object to be coated was heated to 120 ° C., and electrostatic coating was performed at an applied voltage of 80 kV while rotating the object to be coated at a speed of 100 rpm.
Next, electrostatic coating was performed on the surface of the powder coating A coated with the powder coating B under the same conditions as described above.
Next, the coating film is heated at 100 ° C. for 15 minutes, and further heated at 180 ° C. for 30 minutes, whereby an insulating layer having an inner layer formed from the powder coating material A and an outer layer formed from the powder coating material B is obtained. A membrane was obtained.

The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Next, the cylindrical conductor on which the insulating film was formed was placed in a grounded concentric metal container, and the container was filled with SF6 gas. Thereafter, a high voltage was applied to the conductor, and the dielectric breakdown electric field on the surface of the insulating film was measured. As a result, the breakdown electric field on the surface of the insulating film was 1.7 times that of the conductor not formed with the insulating film.
After measurement of the dielectric breakdown electric field, the maximum diameter and the probability of existence of voids in the insulating film were measured using a laser microscope and an ultrasonic microscope. As a result, the maximum diameter of the void was as small as 50 μm, and the existence probability of the void was as small as 1 piece / mm ² .

(Example 2)
A powder coating material C having an average particle size of 40 μm was obtained in the same manner except that 10 parts by mass of isophoroneamine was blended in place of 10 parts by mass of diethylaminopropylamine in the powder coating material B. The powder coating C had a curing start temperature of 70 ° C.
Next, an insulating layer was obtained by forming the inner layer using the powder coating A and the outer layer using the powder coating C under the same conditions as in Example 1.
The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.8 times the dielectric breakdown electric field of the conductor not forming the insulating film.
Furthermore, after measuring the dielectric breakdown electric field, the maximum diameter and existence probability of voids in the insulating film were measured in the same manner as described above. As a result, the maximum diameter of voids was as small as 45 μm, and the existence probability of voids was 1 piece / mm ² . There were few.

(Example 3)
A powder coating material D having an average particle size of 40 μm was obtained in the same manner except that in the powder coating material B, 15 parts by mass of m-xyleneamine was blended in place of 10 parts by mass of diethylaminopropylamine. The powder coating D had a curing start temperature of 60 ° C.
Next, an insulating layer was obtained by forming the inner layer using the powder coating A and the outer layer using the powder coating D under the same conditions as in Example 1.
The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.7 times the dielectric breakdown electric field of the conductor not formed with the insulating film.
Further, after measuring the dielectric breakdown electric field, the maximum diameter and existence probability of voids in the insulating film were measured in the same manner as described above. As a result, the maximum diameter of voids was as small as 35 μm and the existence probability of voids was 1 piece / mm ² . There were few.

Example 4
100 parts by mass of epoxy resin C (bisphenol A type epoxy resin solid at normal temperature, weight average molecular weight 1500), 30 parts by mass of epoxy resin D (cresol novolac type epoxy resin solid at normal temperature, weight average molecular weight 1600), curing agent A ( 7 parts by mass of dicyandiamide), 3 parts by mass of curing agent B (imidazole), and 15 parts by mass of filler (alumina) were dry-mixed using a mixer and then melt-kneaded using a biaxial kneader. Next, after the obtained kneaded material was cooled and solidified, it was pulverized using a pulverizer and classified using a classifier to obtain a powder coating E having an average particle diameter of 45 μm. The powder coating E had a curing start temperature of 120 ° C.
On the other hand, 100 parts by mass of epoxy resin E (bisphenol A type epoxy resin that is liquid at normal temperature, weight average molecular weight 250), 10 parts by mass of curing agent B (imidazole), and 10 parts by mass of diethylaminopropylamine are mixed and stirred. A was obtained. The curing start temperature of this liquid paint A was 70 ° C.

Next, the above-mentioned powder coating E was applied to the surface of an object to be coated (columnar conductor, length 1000 mm × diameter 50 mm) using an electrostatic fluid immersion method. At this time, the object to be coated was heated to 120 ° C., and electrostatic coating was performed at an applied voltage of 40 kV while rotating the object to be coated at a speed of 80 rpm.
Next, the liquid coating material A was spray-coated on the surface of the coated powder coating material E.
Next, the coating film is heated at 100 ° C. for 15 minutes, and further heated at 180 ° C. for 30 minutes, whereby an insulating film having an inner layer formed from the powder coating E and an outer layer formed from the liquid coating A Got.

The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.7 times the dielectric breakdown electric field of the conductor not formed with the insulating film.
Further, after measuring the dielectric breakdown electric field, the maximum diameter and existence probability of voids in the insulating film were measured in the same manner as described above. As a result, the maximum diameter of voids was as small as 40 μm, and the existence probability of voids was 1 piece / mm ² . There were few.

(Example 5)
Liquid paint B was obtained by adding 50 parts by weight of diethylaminopropylamine to 100 parts by weight of methyl ethyl ketone (MEK) and dissolving.
Next, an insulating layer was obtained by forming the inner layer using the powder coating E and the outer layer using the liquid coating B under the same conditions as in Example 4.
The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.7 times the dielectric breakdown electric field of the conductor not formed with the insulating film.
Further, after measuring the dielectric breakdown electric field, the maximum diameter and existence probability of voids in the insulating film were measured in the same manner as described above. As a result, the maximum diameter of voids was as small as 40 μm, and the existence probability of voids was 1 piece / mm ² . There were few.

(Example 6)
In the powder coating A, a powder coating was obtained in the same manner except that the filler (alumina) was removed and 10 parts by mass of diethylaminopropylamine was added. Liquid paint C was obtained by adding 30 parts by weight of this powder paint to 70 parts by weight of methyl ethyl ketone (MEK) and dissolving. The curing start temperature of this liquid paint C was 80 ° C.
Next, the powder coating material A was coated on the surface of an object to be coated (columnar conductor, length 1000 mm × diameter 50 mm) using a fluidized dipping method. At this time, the object to be coated was heated to 120 ° C., and coating was performed while rotating the object to be coated at a speed of 120 rpm.
Next, the liquid coating material C was spray-coated on the surface of the coated powder coating material A.
Next, the coating film is heated at 100 ° C. for 15 minutes, and further heated at 180 ° C. for 30 minutes, whereby an insulating film having an inner layer formed from the powder coating material A and an outer layer formed from the liquid coating material C Got.

The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.7 times the dielectric breakdown electric field of the conductor not formed with the insulating film.
Further, after measuring the dielectric breakdown electric field, the maximum diameter and existence probability of voids in the insulating film were measured in the same manner as described above. As a result, the maximum diameter of voids was as small as 55 μm, and the existence probability of voids was 1 piece / mm ² . There were few.

(Example 7)
As a coating material for forming the outer layer, a UV curable acrylic powder coating material (manufactured by TRIAB Corporation) was used.
First, the powder coating A was coated on the surface of an object to be coated (a cylindrical conductor, length 1000 mm × diameter 50 mm) by using an electrostatic coating method. At this time, the object to be coated was heated to 120 ° C., and electrostatic coating was performed at an applied voltage of 80 kV while rotating the object to be coated at a speed of 100 rpm.
Next, electrostatic coating was performed on the surface of the powder coating A coated with a UV curable acrylic powder coating under the same conditions as described above.
Next, it is formed from powder coating A by irradiating UV having a wavelength of 365 nm with an irradiation amount of 3000 mJ / cm ² to cure the UV curable acrylic powder coating and heating at 160 ° C. for 30 minutes. An insulating film having an inner layer and an outer layer formed from a UV curable acrylic powder coating was obtained.

The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.9 times the dielectric breakdown electric field of the conductor not forming the insulating film.
Furthermore, after measuring the dielectric breakdown electric field, the maximum diameter and existence probability of voids in the insulating film were measured in the same manner as described above. As a result, the maximum diameter of voids was as small as 50 μm, and the existence probability of voids was 1 piece / mm ² . There were few.

(Example 8)
100 parts by mass of epoxy resin F (bisphenol A type epoxy resin solid at normal temperature, weight average molecular weight 1400), 20 parts by mass of epoxy resin G (cresol novolak type epoxy resin solid at normal temperature, weight average molecular weight 1200), curing agent A ( 7 parts by mass of dicyandiamide), 3 parts by mass of curing agent B (imidazole), and 15 parts by mass of filler (calcium carbonate) were dry-mixed using a mixer and then melt-kneaded using a biaxial kneader. Next, after cooling and solidifying the obtained kneaded material, it was pulverized using a pulverizer and classified using a classifier to obtain a powder coating material F having an average particle size of 50 μm. The powder coating F had a curing start temperature of 105 ° C.
On the other hand, 100 parts by mass of epoxy resin H (bisphenol A type epoxy resin that is liquid at normal temperature, weight average molecular weight 300), 10 parts by mass of curing agent B (imidazole), and 10 parts by mass of diethylaminopropylamine are mixed and stirred. D was obtained. The curing start temperature of this liquid paint D was 70 ° C. Moreover, the yield value of the liquid coating material D was 400 Pa, and the stress applied to the liquid coating material by gravity was 360 Pa. Here, the yield value was measured using a rheometer. The stress due to gravity is a calculated value.

First, the above-mentioned powder coating F was applied to the surface of an object to be coated (columnar conductor, length 1000 mm × diameter 50 mm) by using an electrostatic fluid immersion method. At this time, the object to be coated was heated to 120 ° C., and electrostatic coating was performed at an applied voltage of 40 kV while rotating the object to be coated at a speed of 120 rpm.
Next, the liquid coating material D was spray-coated on the surface of the coated powder coating material F.
Next, the coating film is heated at 80 ° C. for 15 minutes, and further heated at 180 ° C. for 30 minutes, whereby an insulating film having an inner layer formed from the powder coating material F and an outer layer formed from the liquid coating material D Got.

The obtained insulating film did not sag paint when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was within 20%, and it was confirmed that the insulating film had high uniformity.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.8 times the dielectric breakdown electric field of the conductor not forming the insulating film.
Further, after measuring the dielectric breakdown electric field, the maximum diameter and existence probability of voids in the insulating film were measured in the same manner as described above. As a result, the maximum diameter of voids was as small as 40 μm, and the existence probability of voids was 1 piece / mm ² . There were few.

(Comparative Example 1)
First, the powder coating A was coated on the surface of an object to be coated (a cylindrical conductor, length 1000 mm × diameter 50 mm) by using an electrostatic coating method. At this time, the object to be coated was heated to 120 ° C., and electrostatic coating was performed at an applied voltage of 80 kV while rotating the object to be coated at a speed of 100 rpm.
Next, electrostatic coating was again performed on the surface of the powder coating A coated with the powder coating A under the same conditions as described above. Here, the yield value of the powder coating material A was 400 Pa, and the stress applied to the powder coating material by gravity was 450 Pa.
Next, the coating film is heated at 100 ° C. for 15 minutes, and further heated at 180 ° C. for 30 minutes, whereby an insulating layer having an inner layer formed from the powder coating material A and an outer layer formed from the powder coating material A is obtained. A membrane was obtained.

In the obtained insulating film, dripping of the paint occurred when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was as high as 240%, and the uniformity of the insulating film was lowered.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.1 times the dielectric breakdown electric field of the conductor not forming the insulating film.

(Comparative Example 2)
A powder coating G was obtained in the same manner except that the curing agent A (dicyandiamide) was removed from the powder coating A. The curing start temperature of this powder coating G was 160 ° C.
Next, the above-described powder coating G was applied to the surface of an object to be coated (columnar conductor, length 1000 mm × diameter 50 mm) using an electrostatic fluid immersion method. At this time, the object to be coated was heated to 120 ° C., and electrostatic coating was performed at an applied voltage of 40 kV while rotating the object to be coated at a speed of 80 rpm.
Next, the coating film was heated at 180 ° C. for 30 minutes to obtain an insulating film formed from the powder paint G.

In the obtained insulating film, dripping of the paint occurred when heated. Further, regarding the film thickness of the insulating film, the difference between the average film thickness measured at 10 cm square and the maximum or minimum film thickness was as high as 240%, and the uniformity of the insulating film was lowered.
Further, as a result of measuring the dielectric breakdown electric field on the surface of the insulating film in the same manner as described above, the dielectric breakdown electric field on the surface of the insulating film was 1.1 times the dielectric breakdown electric field of the conductor not forming the insulating film.

  As can be seen from the above results, according to the present invention, after the powder coating is applied, the surface is coated with a coating that hardens faster than the powder coating and cured, so that no dripping of the coating occurs. A uniform and thick insulating film that can be formed and a method for forming the same can be provided.

  1 Object to be painted, 2 inner layer, 3 outer layer.

Claims (8)

An insulating film having an inner layer, which is a powder coating film formed from a powder coating material, and an outer layer, which is a coating film formed on the inner layer and formed from a coating material that cures faster than the powder coating material , ,
An insulating film , wherein the coating material forming the outer layer is a photocurable coating material containing a vinyl compound . An insulating film having an inner layer, which is a powder coating film formed from a powder coating material, and an outer layer, which is a coating film formed on the inner layer and formed from a coating material that cures faster than the powder coating material, ,
The insulating film, wherein the paint forming the outer layer is a thermosetting paint containing at least one amine compound selected from the group consisting of diethylaminopropylamine, isophoroneamine and m-xyleneamine. The powder coating composition forming the inner layer, an epoxy resin, an insulating film according to claim 1 or 2, characterized in that it comprises a curing agent and a filler. The insulating film according to claim 3 , wherein the curing agent is at least one selected from the group consisting of a carboxylic acid anhydride, an amide compound, a phenol compound, and an imidazole compound. The paint, insulating film according to claim 3 or 4, further comprising the same curing agent as the curing agent contained in the powder coating composition forming the inner layer that forms the outer layer. The paint, insulating film according to any one of claims 1 to 5, characterized in that it has a yield value is greater than the stress due to gravity, to form the outer layer. Stator coil and having an insulating film according to the surface in any one of claims 1-6. A gas insulated switchgear comprising the stator coil according to claim 7 .

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