JP2544692B2 - Powder coating method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new powder coating method using a thermosetting resin powder coating material.

[0002]

2. Description of the Related Art As a coating method using a thermosetting resin such as an epoxy resin, there are a method using a liquid varnish and a method using a powder coating material. As a method of using a liquid varnish, generally, a varnish is dropped from above while rotating a preheated object to be treated (for example, a coil), and a liquid varnish is allowed to flow down on the surface of the object to be impregnated / fixed and cured. The method of letting is done. On the other hand, as a method of using the powder coating material, a fluidized dipping method, an electrostatic fluidized dipping method,
The electrostatic spraying method or a method of sprinkling powder coating material on an object to be coated is used. These methods have been adopted as impregnation / fixing methods for stator coils, rotor coils, etc. in motors and generators. By the way, in the method using the liquid varnish, the lower the viscosity of the liquid varnish is, the better the impregnation property between the coils is, but there is a problem that the varnish sags during the coating / impregnation, and the impregnation / fixing treatment is performed. In the meantime, in order to make the varnish evenly spread over the coil that is the object to be processed and to prevent varnish dripping, it is necessary to rotate the object to be treated from the varnish dropping until it gels and loses fluidity. . Therefore, there is a problem that the equipment for the painting / impregnation / fixing process becomes complicated. Furthermore, in order to secure a stable discharge amount and impregnating property, there is a problem that it is necessary to control the viscosity of the varnish, and the varnish droops downward during processing, resulting in equipment stains and waste of varnish. There is a problem that it will occur. In addition, a varnish using a solvent causes problems such as safety and environmental protection. A powder coating material is used to cover the problems of the liquid varnish, but the powder coating material has a problem that impregnation / adhesion to a minute gap is poor because the viscosity of the powder coating material is high when melted.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in coil coating, has excellent permeability into the fine gaps of the coil , and substantially causes resin to drop from the coil. The problem is to provide a coating method that does not exist.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, including crystalline thermosetting resin, a high melt flow resin powder coating and preheated co
After deposition on the lower surface of yl, the coil is turned upside down, by heating the powder coating material in this state to the curing temperature,
There is provided a powder coating method characterized by causing a curing reaction while flowing down a resin powder coating material attached to a coil in a molten state.

In the present invention, a resin powder coating material containing a crystalline thermosetting resin and having high melt fluidity is used as the powder coating material. The crystalline thermosetting resin is different from the amorphous thermosetting resin which is solid at room temperature in that it has a low viscosity when melted,
It has high melt flowability. As the crystalline thermosetting resin, various conventionally known resins are used, but a crystalline epoxy resin is preferably used. Examples of the crystalline epoxy resin include triglycidyl isocyanurate (“Epicote RXE-15”, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 103, melting point 120 ° C.), epoxypropoxydimethylbenzyl acrylamide (“Kanekaresin AXE”, Kanekabuchi). Made by Kagaku Kosei, epoxy equivalent 27
0, melting point 100 ° C.), hydroquinone diglycidyl ether (“HQDGE”, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 1
25, melting point 100 ° C.), bisphenol S diglycidyl ether (Nippon Kayaku Co., Ltd., “EBPS-200”, epoxy equivalent 200, melting point 125 ° C., tetramethylbiphenol diglycidyl ether (“YX-4000) Yuka Shell Epoxy Co., Ltd. Made, epoxy equivalent 185, melting point 105
C), tetramethylbiphenol diglycidyl ether modified product ("YL-0074C", manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 190, melting point 93C), 2,5-di-
t-Butyl hydroquinone diglycidyl ether ("D
TBHQ-EX ”, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 202, melting point 132 ° C.), terephthalic acid diglycidyl ether and the like.

The above-mentioned crystalline epoxy resin is used in combination with a curing agent, and in this case, the conventional curing agent is, for example, amine, amine adduct, polyamide,
Examples thereof include polyamide adducts, polycarboxylic acids, carboxylic acid anhydrides, polyhydric phenols, imidazole compounds, imidazoline compounds, dicyandiamide and its derivatives, boron trifluoride and its derivatives, and dihydrazide compounds. These hardeners can be crystalline and amorphous, but it is preferable to use a crystalline hardener for at least a part of them. As a typical example of the crystalline curing agent, for example, 5 (2,5-dioxotetrahydrofloryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride (“Epiclone B-4400”, large Nippon Ink Co., melting point 167 ° C), tetrahydrophthalic anhydride (THPA) (melting point 100 ° C), bisphenol A
(Melting point 157 ° C), bisphenol S (melting point 245 ° C)
Besides, organic acid hydrazides, dicyandiamide and the like can be mentioned. Further, as a typical example of the non-crystalline curing agent, for example, phenol novolac type resin (“Tamanol # 75
4 "; Tg 49 ° C, SP 100 ° C, manufactured by Arakawa Chemical Co., Ltd., o
-Cresol novolac type resin ("OCN90"; Tg
40 ° C, SP90 ° C, "OCN120" Tg70 ° C, S
P120 ° C., manufactured by Nippon Kayaku Co., Ltd., etc.

The epoxy resin powder coating material used in the present invention may contain a non-crystalline epoxy resin.
As such an amorphous epoxy resin, various conventionally known resins are used. For example, bisphenol A diglycidyl ether (“Epicoat 1001”; epoxy equivalent 475, Tg (glass transition point) 29 ° C., Durance softening point) (Hereinafter abbreviated as SP) 68 ° C., “Epicoat 100
2 "; epoxy equivalent 650, Tg 42 ° C, SP83 ° C,
"Epicoat 1004"; Epoxy equivalent 950, Tg5
3 ° C., SP98 ° C., manufactured by Yuka Shell Epoxy Co., Ltd., o-cresol novolac type epoxy resin (“Epicoat E1
80S65 "; epoxy equivalent 200, Tg 18 ° C, SP
65 ° C., “Epicoat E180S90”; epoxy equivalent 220, Tg 43 ° C., SP 90 ° C., manufactured by Yuka Shell Epoxy Co., Ltd.) and the like.

The epoxy resin powder coating used in the present invention contains, in addition to the above-mentioned epoxy resin and curing agent,
Curing accelerator, reactive solid organic matter, colorant, flame retardant,
Conventional auxiliary components such as flow regulators and fillers can be used in combination. These can be crystalline or amorphous. Examples of the curing accelerator include imidazole (“Curezol 2MZ”, melting point: 147).
C., Shikoku Kasei Co., Ltd., or modified imidazole (Curezol 2MZ-AZINE, melting point 248.degree. C., Shikoku Kasei Co., Ltd.), pre-reacted product of epoxy resin and imidazole (“Epicure P-200”, Yuka Shell Epoxy Co., Ltd.). , Tg95 ° C.), triphenylphosphine, diazabicycloundecene phenol novolac resin salt (“U-Cat831”, manufactured by San-Apro), and the like. Reactive solid organic substances are reactive with epoxy resins and exhibit various effects. Examples of such substances include, for example, improving the heat resistance of the cured product and improving the binder effect of the compounding ingredients. In addition, a bismaleimide / triazine resin (BT resin) (“BT-2170”, manufactured by Mitsubishi Gas Chemical Co., Inc., Tg 42 ° C.), a bismaleimide resin (Tg 42 ° C.), in order to improve the heat resistance of the cured product and reduce the viscosity during melting ( "MB-3000", manufactured by Mitsubishi Petrochemical Co., Ltd., melting point 156.
℃), butyral resin (“S-REC BLS”, Sekisui Chemical Co., Ltd., Tg120 for improving the adhesiveness of the cured product)
℃), in order to improve the heat resistance and flexibility of the cured product, a solid polyol such as tris (2-hydroxyethyl)
Examples thereof include isocyanurate (“THEIC”, manufactured by Shikoku Kasei Co., melting point 135 ° C.). The flow regulator is added to prevent craters from being generated in the cured product, and examples thereof include acrylic acid ester oligomers (“Nikalite XK-21”, manufactured by Nippon Carbide Co.).

The mixing ratio of the total curing agent to the total epoxy resin is 0.5 to 1.5 equivalents, preferably 0.7 to 1.
It is a ratio of 2 equivalents. The curing accelerator is all epoxy resin 1
The amount is 0.1 to 5.0 parts by weight, preferably 0.3 to 3.0 parts by weight, relative to 00 parts by weight. The mixing ratio of the reactive solid organic substance is appropriately selected as desired, but generally 10 to 50 parts by weight based on 100 parts by weight of the total epoxy resin.
It is a part by weight, preferably 20 to 40 parts by weight.

The crystalline epoxy resin powder coating material used in the present invention has been described above in detail. The coating method of the present invention is applied to a coating material coating material containing another thermosetting resin such as a crystalline bismaleimide resin, The same can be applied to a powder coating material containing a crystalline epoxy resin and a crystalline bismaleimide resin. As the crystalline bismaleimide, bismaleimide synthesized from diaminodiphenylmethane and maleic acid (MB-3000, manufactured by Mitsubishi Petrochemical Co., Ltd.,
m. p. 150 ° C.), and other examples include bismaleimide synthesized from various diamines and maleic acid.

The thermosetting resin powder coating used in the present invention is
Any material containing a crystalline thermosetting resin and having a high melt fluidity may be used, and in general, a melt viscosity of 1000 cp or less, preferably 500 cp or less is used.

In order to carry out the powder coating method of the present invention, first, the lower part of the preheated coil is dipped in a stationary layer or a fluidized bed of thermosetting resin powder coating, and this powder coating is applied to the coil coating. It is attached to the lower surface of the processed material. The coil preheat temperature is
It is usually the melting temperature of the powder coating. For the preheating of the coil , an appropriate heating method is adopted depending on the coil of the object to be treated, and for example, electric heating or hot air stove heating can be used. The amount of powder coating adhered can be adjusted by the preheating temperature of the coil, the time for immersing the coil in the powder coating, and the ratio of immersing the coil in the powder coating. The ratio of immersing the coil in the powder coating is 20 to 20% of the total volume of the coil.
It is 80 vol%, preferably 30 to 60 vol%.
Adhesion amount of the powder coating to the coil covers the entire surface of the coil, is 1.5 times the required coating weight to fill the fine voids of the coil to the required deposition amount. In addition,
This required adhesion amount can be easily known by a simple preliminary experiment.

Next, the coil having the powder coating adhered to the lower portion as described above is turned upside down, and the powder coating adhered in this state is heated to its curing temperature. The heating of the adhered powder coating material to the curing temperature can be performed not only by placing the coil in a heating furnace and by the amount of heat from the heating furnace, but also by the amount of heat possessed by the coil itself. By this heating, the melt of the powder coating material located on the upper part of the coil flows down the coil surface, and also penetrates into the fine voids of the coil and flows down, and at the same time, a hardening reaction occurs and the hardening gradually occurs. Go. In this way, the surface of the coil while being coated with the melt of the powder coating, the microvoids of the coil filled coil is formed in the melt of the powder coating. In this way, the powder coating material melt adhered to the coil is finally cured into an insoluble and infusible cured product. When curing a powder coating, if the curing temperature is too high, the melt viscosity of the powder coating will be low, but the gelation will be faster, so the viscosity increase due to gelation of the melt will be faster, and conversely, the curing temperature will be higher. If it is too low, the melt viscosity of the powder coating material will be high, but the viscosity increase due to gelation of the melt will be slow. Therefore, the curing temperature is appropriately determined according to the specific component composition of the powder coating material and the gelling property. Generally, 200
The gelation time (JISC2104) of 5 seconds or more, preferably 10 to 30 seconds at a temperature of 1000 ° C. and a melt viscosity of 1000 cp
Hereafter, it is preferable to adopt a curing temperature that preferably indicates 500 cp or less. The optimum curing temperature can be easily known by preliminary experiments.

Examples of the coil of the object to be treated used in the present invention include a stator coil (stator coil) in a motor or a generator . According to the invention, these carp
On the surface of the Le can be formed a cured coating film of a thermosetting resin, also can be filled with the cured product of the thermosetting resin in the micropores of the coil.

[0015]

According to the powder coating method of the present invention, the cured product of the thermosetting resin can be easily attached to the surface of the coil and the fine voids . Unlike the conventional powder coating method, the method of the present invention uses a powder coating material having a low viscosity at the time of melting, but even if the coil of the object to be processed is not rotated, the coating material sags. Since it does not fall off, it is remarkably excellent in coating workability and economy. Further, the method of the present invention, compared with the method using a liquid varnish, because the paint melt does not sag, the paint is significantly saved, and the workability is also significantly improved. Is. The method of the present invention is a method of fixing a coil.
It is extremely advantageously applied as a law. Coating of the coil of the present invention
By the mounting method , the coating material is uniformly adhered to the outer surface of the coil and the fine voids between the coils, and the coil can be firmly fixed.

[0016]

Next, the present invention will be described in more detail with reference to examples.

Examples 1 to 3 Twenty copper wires having a diameter of 1.2 mm and a length of 50 mm are bundled into one rod-shaped object to be treated, and a copper wire having a diameter of 0.3 mm is wound around two places around the copper wire. A simulated coil with the whole fixed was used. In this simulated coil, one of the copper wires at the center was made 100 mm in length and projected from the end of the copper wire bundle to be used as an operating member. On the other hand, N in Table 1
o. A powder coating having the composition (parts by weight) shown in No. 1 has a diameter of 25
100m height in a cylindrical container of 0mm and height 100mm
It filled up to m and formed the powder coating material layer. Next, preheat the copper wire bundle in a hot air heating furnace, hold the copper wire protruding from the end of the copper wire bundle in a hand with heat-resistant gloves, and in the powder coating layer, from the tip of the copper wire bundle to the copper wire bundle. After immersing the part up to ⅓ of the length (17 mm from the tip) for a certain period of time shown in Table 2, immediately turn it upside down and heat the copper wire protruding from the copper wire bundle by placing it in a hole on the support base. It was placed in a furnace and heated at the curing temperature shown in Table 2 for 30 minutes. For each coated coil obtained in this way, while measuring the coating adhesion amount,
The adhesion of the copper wires to each other and the dripping of the molten coating upon curing were examined. As a result, it was confirmed that the paint permeated and adhered to the fine voids formed between the copper wires of the copper wires to firmly fix the copper wires to each other. In addition, when it was examined whether or not the coating melt dripped on the support after curing, it was confirmed that the melt did not droop.

Comparative Examples 1-2 No. 1 in Table 1 An experiment was conducted in the same manner as in Example 1 except that the epoxy resin powder coating shown in 2 was used.
Inadequate penetration of the paint into the gap between the copper wires and the resin has not reached the opposite side of the powder layer, and when the copper wire bundle is strongly compressed by hand, movement of the copper wire is recognized. Was given.

The contents of the components indicated by the symbols in Table 1 are as follows. YX-4000: Tetramethyl biphenol diglycidyl ether, epoxy equivalent 185, melting point 105 ° C, made by Yuka Shell Epoxy E-1004: Bisphenol A diglycidyl ether, epoxy equivalent 950, softening point 98 ° C, made by Yuka Shell Epoxy Co. B-4400: 2 (2,5-dioxotetrahydrofloryl) -3-cyclohexene-1,2-dicarboxylic acid anhydride, melting point 167 ° C., OCN-120: o-cresol novolac resin manufactured by Dainippon Ink and Chemicals, softened Point 120 ° C., Nippon Kayaku Co., Ltd. 2MZ-P: 2-methylimidazole, Shikoku Chemicals P-200: Preliminary reaction product of epoxy resin and imidazole, Yuka Shell Epoxy Co., Ltd.

[0020]

[Table 1]

[0021]

[Table 2] Contrabass Rheomat 115 / CP400 system, cone no. Measured at 8

Example 4 As an object to be treated, an AI having a diameter of 2.3 mm and a length of 40 mm was used.
A simulation in which six W copper wires are bundled, two copper wires having a length of 80 mm are pierced one by one from both ends of the bundle to the center, and a 0.3 mm copper wire is wound around the copper wire and the whole is fixed. A coil was used. This copper wire bundle is preheated to a predetermined temperature and has one of the copper wires projecting from the center of both ends of the bundle, and from the tip of the copper wire bundle to 1/4 of the length of the copper wire bundle (10 m from the tip
After the parts up to m) were immersed in the powder layer, they were immediately inverted upside down, grabbed by double-clicking, and cured in a curing furnace. During the curing, the powder adhered to the upper part of the simulated coil was melted and flowed through the gap between the copper wires, the entire copper wire bundle was covered with the cured resin, and no resin dripping was observed.

Comparative Example 3 In Example 4, No. 1 in Table 1 was used. As a result of performing the same experiment except that the powder of No. 2 was used, the resin adhering to the upper part of the copper wire bundle did not flow down the copper wire bundle after melting, but remained on the upper part of the copper wire bundle, and was impregnated into the powder layer. The 80 mm copper wire protruding from the center of the end portion on the non-existing side was easily removed. The results of Example 4 and Comparative Example 3 shown above are shown in Table 3.

[0024]

[Table 3]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuji Kitagawa 4-11-2 Ginza, Chuo-ku, Tokyo Somer Co., Ltd. (56) References Japanese Patent Publication No. 3-73447 (JP, B2)

Claims (2)

(57) [Claims] 1. A resin powder coating containing a crystalline thermosetting resin and having a high melt fluidity is applied to the lower surface of a preheated coil , and then the coil is turned upside down. A powder coating method, wherein the coating material is heated to its curing temperature, and a curing reaction is performed while the resin powder coating material attached to the coil is flowed in a molten state. 2. The melting viscosity of the powder coating material is 1000 cp.
The method of claim 1, wherein: