JPS6231804B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an electrical insulating coil using prepreg mica tape impregnated with a highly concentrated resin composition that is solvent-free or has a solvent content of 3.5% by weight or less.

Technical Background of the Invention and Problems Conventionally, electrical insulating wire has been produced by impregnating mica with a varnish containing a solvent, then drying it to remove the solvent, and then wrapping the prepreg mica tape around a conductor and heating and pressurizing it. Some are made by molding. In such electric insulating wire rings, solvent remains in the pre-preg mica tape, so when the insulation structure is heated during operation after forming, the solvent in the insulating layer expands and causes voids. This causes the layers to peel off, making them susceptible to deterioration due to partial discharge, mechanical deterioration due to electromagnetic vibration or sudden short circuits, and further deterioration due to moisture absorption. In addition, an insulating layer in which a small amount of solvent remains tends to increase the dielectric loss tangent tan δ at high temperatures, which also has the disadvantage of increasing dielectric loss during operation. In order to eliminate these drawbacks, prepreg mica tape made of solvent-free resin is known, but all of these tapes use release paper (or release paper).
Because the tape itself is manufactured using prepreg mica tape impregnated with a conventional solvent-based varnish, the price of the tape itself is higher than that of prepreg mica tape impregnated with a conventional solvent-based varnish. ), which required complicated work to remove.

OBJECTS OF THE INVENTION The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide an electrically insulating wire ring that can reduce dielectric loss, is economical, and is easy to manufacture.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has an electrical insulating wire made of liquid novolac type epoxy resin 80~
100 parts by weight, 20 to 0 parts by weight of liquid bisphenol A diglycidyl ether epoxy resin, and 0 to 0 parts by weight.
A mica tape containing 40 to 50 parts by weight of an epoxy resin composition produced by heating and mixing 1.5 to 3.5 parts by weight of BF ₃ monoethylamine complex containing 3.5 parts by weight of a solvent was wound around a conductor, heated, and heated. It shall be press-formed.

Embodiments of the Invention Examples of the present invention will be described in detail below. First, to explain the method for manufacturing mica tape according to the present invention, the composition materials of the mica tape will be described first. 80 to 100 parts by weight of a liquid novolac-type epoxy resin (for example, DEN431 manufactured by Dow Chemical Company) and 20 to 100 parts by weight of liquid bisphenol A diglycidyl ether epoxy resin (for example, Epicote 828 manufactured by Schiel Chemical Co., DER331 manufactured by Dow Chemical Company, etc.).
0 parts by weight is heated to 65-70°C, weighed, and stirred. Separately, prepare 1.5 to 3.5 parts by weight of a fine BF ₃ monoethylamine complex that has been screened through a 100-mesh sieve, and either as it is or after swelling and dissolving it in 3.5 parts by weight or less of methyl ethyl ketone.
added to the epoxy resin mixture kept at 65°C;
Stir for 30 to 45 minutes to obtain an epoxy resin composition as a mica tape composition according to the present invention. In this case, the reason why the liquid epoxy resin is used is because when impregnating the mica sheet, which will be described later, with a solid resin, the resin will not soak up into the mica sheet. Furthermore, the reason for limiting the amount of bisphenol A diglycidyl ether type epoxy to 80 to 100 parts by weight of novolac type epoxy resin is that bisphenol A diglycidyl ether type epoxy is inexpensive and gives flexibility to the mica tape. Dielectric loss tangent at high temperature
This is because the tan δ is larger than that of novolac type epoxy resin. In principle, methyl ethyl ketone, which is a solvent, should not be used, and the amount used must be kept to a minimum, equal to or less than the amount of BF ₃ monoethylamine. Furthermore, when the temperature of the resin exceeds 70℃, the curing reaction of the epoxy resin rapidly progresses, causing heat generation and
The temperature of the resin must be maintained at 65°C to prevent fuming. In addition, BF ₃ monoethylamine absorbs moisture and tends to change its properties, so it is necessary to use one that does not absorb moisture. Furthermore, the epoxy resin composition used for manufacturing the electrically insulated coil of the present invention is
80 to 100 parts by weight of a liquid novolac type epoxy resin, 20 to 0 parts by weight of a liquid bisphenol A diglycidyl ether epoxy resin, and 1.5 to 3.5 parts by weight of a BF ₃ monoethylamine complex containing 0 to 3.5 parts by weight of a solvent. It is produced by heating and mixing.

Here, if the bisphenol A diglycidyl ether epoxy resin is 0 parts by weight, it becomes only a novolak type epoxy resin, which exhibits the characteristics of a novolak type epoxy resin. Although the problem of brittleness remains, mica tape can be produced even with 0 parts by weight, and wire rings with good properties can be obtained. On the other hand, 20
If it is more than part by weight, the dielectric loss tangent tan δ at high temperature is too high and the dielectric loss at operating temperature is large, so it cannot be used for type F. For these reasons, it can be said that the amount of bisphenol A diglycidyl ether epoxy resin is desirably 0 to 20 parts by weight.

Furthermore, if the solvent for the BF ₃ monoethylamine complex is 0 parts by weight, the BF ₃ monoethylamine complex can be dissolved in the resin at a high temperature, but there is a risk that heat will be generated rapidly during stirring and the resin will harden. There is a drawback that it is difficult to make mica tape. However, the effect can be exerted without loss.
When about 3.5 parts by weight of MEK is added, BF ₃ can be obtained even at room temperature.
The monoethylamine complex can be dissolved in the resin, and at this level, insulation properties can be obtained that do not adversely affect the electrical properties of the wire. For these reasons, the amount of the solvent for the BF ₃ monoethylamine complex is preferably 0 to 3.5 parts by weight.

Next, the specific manufacturing process of the mica tape according to the present invention will be explained with reference to FIG.

As shown in Figure 1, a 150g/ ^m2 laminated mica sheet 2 is superimposed on a glass cloth 1 with a thickness of 33μm,
The above-mentioned epoxy resin composition 3 adjusted to 60° C. is applied thereto via a roll 4. In this case, in order to keep the resin content in the produced mica tape constant at 40 to 50% by weight, a doctor knife 5 is provided on the surface of the roll 4 to adjust the resin amount.
A weight plate 7 is provided on the surface of the mica sheet assembly 2 with a cloth 6 in between, so that the roll 4, the glass cloth 1, and the mica sheet assembly 2 are brought into sufficient contact. Next, the surface of the assembled mica sheet 2 is heated by the heater 8 in order to help the resin composition completely permeate into the assembled mica sheet 2. Thereafter, it is passed through a dryer 9 by a bar conveyor 10 to dry it to the extent that it does not become sticky. In this way, the glass cloth reinforced prepreg mica sheet 11 can be wound up without using release paper.

The glass cloth-reinforced prepreg mica sheet 11 thus obtained is cut into tapes of a predetermined width to obtain mica tapes of 0.21 mm thickness. Wrap this mica tape around the conductor 5 times with 1/2 wrap and heat to 150℃.
After heating and press-forming for 2 hours, the wire was placed in an iron core, the wire was connected and insulated, and then cured for 15 hours at 150°C to obtain an electrically insulated wire.

According to experiments, the electric insulating wire according to the present invention thus obtained has a dielectric loss tangent tan δ of 10 to 10 at 155°C.
At 15%, the dielectric breakdown voltage was as high as 25.5 Kv/mm, and the blistering phenomenon due to heating, which is characteristic of solvent-based prepreg mica tapes, was not observed, confirming that it had the function of class F.

Next, a second embodiment of the present invention will be described with reference to FIG.

In FIG. 2, the same parts and parts as those in FIG. 1 are given the same reference numerals, and their explanations will be omitted. As shown in FIG. 2, after coating the epoxy resin composition 3 kept at 60° C. with a reverse coater 13 on a polyester film 2 with a thickness of 16 mm,
Laminated with laminated mica sheet 2 of 150 g/m ² .
Thereafter, the assembled mica sheet 2 side is heated by the heater 8, and the epoxy resin composition 3 permeates up to the surface of the assembled mica sheet 2. Thereafter, it is heated and dried through a dryer 9 by a bar conveyor 10 to eliminate stickiness. In this way, the film-reinforced prepreg mica sheet 14 can be wound up without using release paper.

The film-reinforced prepreg mica sheet 14 thus obtained is cut into tapes with a predetermined width to obtain mica tapes with a thickness of 0.21 mm. This mica tape was wound 5 times in 1/2 layers around the conductor, heated and pressed at 150°C for 2 hours, then placed in the iron core, connected and insulated, and then cured at 150°C for 15 hours to form an electrically insulated wire. get.

According to experiments, the insulated wire ring obtained in this way has a tan δ of 12.5 to 17.5% at 150℃ and a dielectric breakdown voltage.
The tape was as high as 27.5 Kv/mm, and as in the first example, the blistering phenomenon due to heating, which is characteristic of solvent-based prepreg mica tapes, was not observed, and it functioned as type F.

Effects of the Invention According to the present invention described above, it is possible to provide an electrically insulating wire ring that is inexpensive and easy to manufacture, which has a function as F type without any blistering phenomenon caused by the solvent during heating, has low dielectric loss.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the manufacturing method of the first embodiment of the electrically insulating wire according to the present invention, and FIG. 2 is a diagram for explaining the manufacturing method of the second embodiment of the electrically insulating wire according to the present invention. This is a diagram for 1... Glass cloth, 2... Laminated mica sheet, 3... Epoxy resin composition, 4... Roll,
5... Doctor knife, 6... Cloth, 7... Weight plate, 8... Heater, 9... Dryer, 10... Bar conveyor, 11... Glass cloth reinforced prepreg mica sheet, 12... Polyester film, 13...Reverse coater, 14...Glass cloth reinforced prepreg mica sheet.

Claims (1)

[Claims] 1. 1.5 to 1.5 parts by weight of BF ₃ monoethylamine complex containing 80 to 100 parts by weight of liquid novolak type epoxy resin, 20 to 0 parts by weight of liquid bisphenol A diglycidyl ether epoxy resin, and 0 to 3.5 parts by weight of solvent.
An electrically insulating coil made by winding a mica tape containing 40 to 50 parts by weight of an epoxy resin composition produced by heating and mixing 3.5 parts by weight with a conductor, heating and press-molding the tape.