JP2511190B2 - Method for manufacturing heat resistant insulated wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has a large size, such as a coil of a liquid sodium immersion type uncooled electromagnetic pump in a fast breeder reactor, and has a size of 300 mm.
The present invention relates to a method for manufacturing a heat-resistant insulated coil suitable for electric equipment that is used at a high temperature of ℃ or higher, or is repeatedly subjected to a heat cycle between a high temperature of 300 ℃ or higher and room temperature due to operation or shutdown during use. is there.

(Prior Art) Almost no heat-resistant insulated wire loop that can be used at a high temperature of 300 ° C or higher is known. Like MI cable (a product of Furukawa Electric Co., Ltd.), a heat-resistant insulating coil, in which magnesium oxide powder is filled between the conductor and the metal sheath, is known. Is required, and since the conductor space factor is low, it is not suitable for the loop of electric equipment with a large capacity.

Further, JP-B-62-1241 and JP-B-62-1242 disclose that a silicone-based resin or a silicone-based resin and a high-melting point inorganic material are used in at least a part of the inter-wire void portion of the coil and the outer surface of the coil. A heat-resistant insulating coil is described, which comprises filling and / or coating powder and then firing to form an inorganic layer.

In addition, Japanese Patent Publication No. 62-57086 and Japanese Patent Publication No. 62-57087 describe a coil formed by winding a heat-resistant insulated wire that becomes an inorganic substance on a conductor at a high temperature such as an inorganic insulating layer or abnormal conditions during use. A method of manufacturing a heat-resistant insulating coil device of a fixing method is described.

(Problems to be solved by the invention) The heat-resistant insulating wire described in the publicly known example has a powdery inorganic layer formed on the surface thereof, and thus is exposed to powdery powder after long-term use. The inorganic layer gradually powders,
It cannot be used stably for a long period of time because it falls apart and collapses. In addition, since a too thick inorganic layer cannot be formed, the dielectric breakdown voltage is low and it cannot be used in a device for high voltage. In the case of high-voltage equipment like this, mica tape or insulating tape should be heated and pressed with an inorganic polymer (polymer that can be mineralized) or an inorganic adhesive, and then baked to form completely mineralized insulation. Can be considered.

However, in this type of insulation that is entirely solidified with an adhesive, thermal stress is generated due to the difference in the coefficient of thermal expansion between the conductor and the insulating layer during start-up and stop, and if this heat cycle is repeated, insulation will be generated due to fatigue. Cracks will occur and insulation will deteriorate. In particular, such a phenomenon is likely to occur in large windings for large capacity machines and equipment used at higher temperatures, such as a liquid sodium immersion type uncooled electromagnetic pump used in the primary cooling system of a fast breeder reactor.

Therefore, a liquid sodium immersion type uncooled electromagnetic pump or the like for circulating liquid sodium in a fast breeder reactor is used.
Insulated coils used at high temperatures of 0 ° C or higher must have high heat resistance so that they can be used stably at high temperatures of 300 ° C or higher for long periods of time. And it is required to reduce the outer shape of the electromagnetic pump.
In particular, in a large-capacity machine used for a primary cooling system, a high-voltage insulating coil that does not cause insulation deterioration due to heat cycles is required.

The present invention has been made to meet such a demand, and can be stably used for a long period of time at a high temperature of 300 ° C or higher,
It is an object of the present invention to provide a method for manufacturing a heat-resistant insulating coil that can be used even at a high voltage where insulation deterioration does not occur due to a heat cycle.

[Structure of Invention]

(Means for Solving the Problems) The present invention uses an adhesive composed of an inorganic polymer or an inorganic coating material for a conductor, and winds a mica tape obtained by pasting peeled mica and an inorganic reinforcing material, at 300 ° C. or higher. Provided is a method for producing a heat-resistant insulating wire ring, which essentially requires firing an inorganic polymer or an inorganic coating at the temperature.

In the above, when the mica tape is wound, the mica tape may be wound while being coated with an inorganic polymer or an inorganic coating material and baked at a temperature of 300 ° C. or higher to solidify the mica tapes together.

Further, after the mica tape is wound, an inorganic insulating tape having high mechanical strength and excellent heat resistance may be wound to protect the insulating layer. When winding this inorganic insulating tape, it may be wound while applying an inorganic polymer or inorganic coating and baked at a temperature of 300 ° C. or higher to be solidified integrally with the mica layer. It is desirable not to apply an inorganic polymer or an inorganic coating because the inorganic insulating tape is easily broken by stress fatigue.

Peel mica used in the present invention is also called flake mica and mica splitting, `` a mica flakes stripped to a uniform thickness from a block or symmic mica, having 10 stacked layers having a thickness of 0.28 mm or less and having a size of 1.7. Those of cm ² or more are generally used. ” There are soft and hard depending on the difference in the raw ore, but the softer one has a higher crystallization water release temperature, and the softer one is, the better the equipment used at high temperature.

In addition, as a reinforcing material for mica tape and an inorganic insulating tape with high mechanical strength and excellent heat resistance, heat resistance such as alumina, alumina boria silica (for example, Nextel under the brand name of 3M in the US), and silica are used. Yes Use woven or non-woven fabric woven from fibers with high mechanical strength. In the case of a woven cloth, in order to improve the thermal conductivity of the insulating layer, a woven cloth having a high fiber density is preferable. Generally, for the reinforcing material of mica tape, a thin tape of about 30 to 400 μm increases the space factor of the mica layer, the dielectric breakdown voltage per unit thickness is large, and it is advantageous in the insulation design. Since an inorganic insulating tape having high mechanical strength and excellent heat resistance requires mechanical strength, a relatively thick tape of about 100 to 500 μm is suitable.

To prevent loosening of the insulating tape end, hold it down with a thread made of inorganic fiber such as alumina, alumina, boria, silica, or silica, or apply only the above-mentioned inorganic polymer or inorganic paint to the end of the insulating tape and burn at high temperature. Bond by treatment.

The term “inorganic polymer” is a general term for polymers (polymers) that become inorganic by firing at high temperature, and includes many silicones. For example, alkyl silicate type silicone AY49-208 (trade name of Toray Silicone Co.),
Inorganic filler-containing borosiloxane paint SMR-109 (trade name of Showa Densen Denki Co., Ltd.) and pressure sensitive adhesive made of methyl polysiloxane YR3286 (trade name of Toshiba Silicone Co.) are included.

Furthermore, as inorganic paint, aluminum monophosphate,
Phosphates such as silicon phosphate, colloidal silica and colloidal alumina are included.

An inorganic filler may be added to the above-mentioned inorganic polymer or inorganic coating material.

Here, as the inorganic filler, alumina (Al
₂ O ₃ ), magnesia (MgO), silica (SiO ₂ ), zirconia (ZrO ₂ ), steatite (MgSiO ₃ ), clay, kaolin, mica powder, and high melting point glass frit. The average particle size of these fillers is preferably 10 μm or less so that they can be easily mixed with the mineralized silicone and coated easily.

Incorporation of a large amount of inorganic filler into an inorganic polymer generally makes it thermally stable and cheap. However, since the filler itself does not bond by firing, it is necessary to blend an inorganic polymer to the extent that a firm bond is formed by firing.

On the other hand, it is necessary to select the blending of the inorganic filler and the inorganic polymer so as not to make it difficult to apply and not to become brittle after firing. Usually, the content of inorganic filler is 10 ~ 90
About wt% is good.

It goes without saying that all of these inorganic polymers, inorganic paints, and inorganic fillers must be insulating.

(Function) Here, the mica tape is used because the mica has high heat resistance and also has excellent dielectric breakdown voltage and withstand voltage. I used mica tape near the conductor because
This is because the life can be extended by placing a material having a higher electric field near the conductor and a higher withstand voltage.

Or to use mica, Due to its high openness, the thermal stress due to the heat cycle due to the operation / stop of the equipment is absorbed by the displacement of the mica layer. Especially for peeled mica, the size of the mica flakes is large, and each mica flakes has a tensile strength of 40-60.
Since it is as strong as kg / mm ² or more, even if thermal stress is applied to the peeled mica, the mica flakes relax the stress.

Also, even if the mica flakes are misaligned, the decrease in dielectric breakdown strength is slight.Sodium immersion type uncooled electromagnetic pump coils used in the primary cooling system of fast breeder reactors have a coil circumference Is 250 mm or more. In such a case, due to the difference in thermal expansion between the conductor and the insulating layer, a tensile strain of about 2 mm acts on the insulation at the maximum operating temperature of 600 ° C. If such an excessive strain acts locally, the laminated mica with a tensile strength of at most about 2 kg / mm ² will break the laminated mica. Dielectric breakdown voltage will decrease. If peeling mica is used, even if such an excessive strain acts, the mica flakes are displaced from each other, so that the stress is relieved and the dielectric breakdown voltage is hardly reduced.

The inorganic insulating tape, which has high mechanical strength and excellent heat resistance, is used for the reinforcing material of the mica tape or the surface protection of the mica tape for the following reason. That is, the mica tape is excellent in electrical properties but slightly inferior in mechanical strength, so an inorganic insulating tape having high mechanical strength and high heat resistance is used as a reinforcing material for mica inferior in mechanical strength, Further, by winding and pressing the mica tape from above, it is possible to prevent the mica tape from falling apart.

In addition, while applying an inorganic polymer containing an inorganic filler or an inorganic paint, winding and baking the mica tape is to form a strong insulating layer by bonding the conductor and the mica tape and the mica tapes to each other. Because you can do it.

On the other hand, the reason why the adhesive should not be applied to the inorganic insulating tape wound on the surface is that if the mica layer and the inorganic insulating tape are hardened together with the adhesive, the above-mentioned large The mechanical strength of the insulation as a whole is reduced due to the action of strain and the cutting of the inorganic insulating tape, but if no adhesive is applied, it absorbs the thermal stress caused by the heat cycle by deforming itself. Resulting in. Therefore, the insulating tape does not break. However, when the insulating tape having no adhesive is wound around the surface in this manner, the insulating tape is loosened, and thus the loosening prevention as described above is necessary.

Incidentally, in the present invention, the inorganic reinforcing material, after winding a mica tape formed by bonding with an adhesive composed of an inorganic polymer or an inorganic coating, and then baked at a temperature of 300 ℃ or more, the adhesive of the mica tape This is because the organic component is incinerated from the applied inorganic polymer or the inorganic coating material to make it completely inorganic.

(Example) Hereinafter, an example of the present invention will be described.

Example 1 In FIG. 1, a conductor 1 is a nickel-plated alumina dispersion strengthened copper 2 (trade name Glid c manufactured by Gliden Metal Co., Ltd.).
The cross section composed of opAL-15) is 2.0 mm × 4.5 mm (cross section perimeter 13
mm) rectangular wire, silica cloth with a thickness of 50 μm and a thickness of 100
A mica tape 3 consisting of a μm soft unfired laminated mica sheet and a small amount of silicone (for example, Toshiba Silicone's product name YR3286) bonded together as an adhesive was wound. After wrapping it in a pancake form to a diameter of 430 mm and a thickness of 25 mm (coil cross-section perimeter length of 250 mm), an alkyl silicate-based mineralized silicone containing an inorganic filler (trade name AY49-20 manufactured by Toray Silicone Co., Ltd.
8) or an inorganic adhesive 4 such as alumina is used for molding. Further, a 50 μm thick alumina woven cloth is lined and reinforced with 100 μm thick soft peeling mica from above, and an inorganic polymer containing the above-mentioned inorganic filler (trade name AY49-208 of Toray Silicone Co.) and inorganic filling Agent-containing borosiloxane resin coating (Showa Densen Denki's trade name SMR-1069) and silicone pressure-sensitive adhesive (Toshiba Silicone trade name YR328
6) The peeled mica tape 5 coated with and was coated with an inorganic polymer containing the above-mentioned inorganic filler (trade name AY49-208 manufactured by Toray Silicone Co., Ltd.) and wound three times in 1/2 lap winding. Wrap a mold release polytetrafluoroethylene tape (not shown) on the outside, apply an iron plate, and then wind a heat-shrinkable polyester tape (which may be in the form of a film, tube, or woven cloth). At 80 ℃ for 1 hour, 130 ℃ for 2 eyes, 150 ℃ for 2 hours, and 180 ℃ for 15 hours.
Heated and softened for a period of time. After that, the heat-shrinkable polyester tape, the iron plate, and the polytetrafluoroethylene tape for release are removed, and the wire is fired in air at 300 ° C for 8 hours and 600 ° C for 8 hours to obtain a heat-resistant insulating wire. Got

In the above manufacturing process, pressurization during heat curing is performed by heat shrinkage of the heat-shrinkable polyester tape, and further, organic components contained in the insulating layer are scattered and burned off to be inorganicized by heating and baking at high temperature. (Ceramicization), and a completely inorganic insulating layer was formed. Furthermore, as an inorganic insulating tape with no adhesive, a thickness of 300
The insulating tape 6 made of alumina fiber woven cloth having no μm adhesive was wound once by 1/2 lap winding. Then, in order to prevent the end of the insulating tape from loosening, a thread made of alumina fiber was wound while being pressed from the winding end of the insulating tape to form an insulating layer.

Example 2 After the peeling mica tape 5 was wound according to Example 1 described above, an insulating tape made of alumina fiber woven cloth having a thickness of 300 μm was used as an inorganic insulating tape having no adhesive thereon. 6 was wound once in 1/2 lap winding. After that, in order to prevent the end of the insulating tape from loosening, a thread made of alumina fiber was wound while being pressed from the winding end of the insulating tape to form an insulating layer. As in Example 1 described above, a polytetrafluoroethylene tape (not shown) for release was wound around the insulating layer thus formed, and an iron plate was applied thereto, and then a heat-shrinkable polyester tape (film shape) was used. , Tube-shaped or woven cloth may be used, and this is heated at 80 ℃ for 1 hour, 130 ℃
2 hours, 150 ° C. for 2 hours, and 180 ° C. for 15 hours to cure. After that, the heat-shrinkable polyester tape, the iron plate, and the polytetrafluoroethylene tape for mold release were removed, and the wire was heated at 300 ° C. for 8 hours at 600 ° C.
And baked for 8 hours to obtain a heat-resistant insulating wire ring.

Comparative Example 1 As shown in FIG. 2, the peeling mica tape 5 of Example 1 described above has a thickness of 100 μm instead of the soft peeling mica layer.
An assembled mica tape 7 prepared by laminating the soft assembled mica of No. 1 with the same adhesive was prepared, and while applying the adhesive, it was wound three times by 1/2 lap winding. After curing and firing in the same manner as in Example 1, the inorganic insulating tape 6 was wound to form an insulating layer.

Comparative Example 2 As shown in FIG. 3, after winding an assembled mica tape 7 made of soft assembled mica according to Comparative Example 1 described above, the above-mentioned adhesive-free inorganic insulating tape was replaced with the above Inorganized polymer containing inorganic filler (Toray Silicone Co., Ltd. product name AY49-208) and inorganic filler-containing borosiloxane resin coating (Showa Densen Denki Co. product name
SMR-109) is applied and dried, and the prepreg-shaped inorganic insulating tape 8 is coated with an inorganic polymer containing an inorganic filler (trade name AY49-208 manufactured by Toray Silicone Co., Ltd.). It was wound once by 1/2 lap winding to form an insulating layer. Curing and firing were carried out in the same manner as in Example 1 to obtain a heat resistant insulating coil.

The heat-resistant insulating wire loops obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were heat-cycled 1000 times between room temperature and 650 ° C. to form an insulating mica tape forming the insulating layer of Comparative Examples 1 and 2. The mica of No. 7 was cracked and cut.
On the other hand, in the case of the peeled mica for forming the insulating layer of Examples 1 and 2, no crack was found in the peeled mica tape 7. The residual dielectric breakdown voltage (percentage of the dielectric breakdown voltage after heat cycle deterioration with respect to the initial value of the dielectric breakdown voltage) after 1000 heat cycles was determined in Example 1.
95%, 90% in Example 2, 60% in Comparative Example 1, 55 in Comparative Example 2
%, The residual insulation breakdown voltage of the insulated wire of the present invention was high.
As described above, the heat cycle test showed that the deterioration of the comparative example was larger than that of the example because the perimeter of the conductor cross section was 25
This is because the tensile strain acting on the insulating layer was so large that it was as large as 0 mm, and the laminated mica of the comparative example could not withstand. In each of the examples and the comparative examples, the mica laminated was used for the conductor of the rectangular wire forming the conductor, but no crack was found at all. In this case, the conductor perimeter is 13
Since it is as small as mm, tensile strain is hardly applied to the insulating layer. Since the peeled mica of the present embodiment has a large piece of phosphorus, even if a large tensile strain is exerted, the pieces of phosphorus are overlapped with each other and shift into a depression, so that the dielectric breakdown voltage hardly decreases.

A crack was generated in the alumina woven tape on the insulating surface of Comparative Example 2 early in the heat cycle, and the alumina fiber was cut. This is because the inorganic polymer applied to the alumina woven fabric becomes brittle when fired, and the strength of the fiber is reduced. In the case of the woven alumina tape having an insulating surface of Examples 1 and 2 and Comparative Example 1 having no adhesive, heat cycle
No cracks were found even after 1000 times.
However, as shown in Table 1 as the relative value of the tensile strength of the alumina tape portion of the insulating surface before the heat cycle test cut out from the insulating wire loop as a relative value to the tensile strength before taping, alumina tapes other than Example 1 were Low tensile strength.
This is because when the inorganic polymer in the mica tape layer is sintered, the volatile component adheres to the alumina fibers and sinters, which reduces the strength of the fibers. Therefore, it is desirable that the alumina tape on the insulating surface be wound after sintering the inorganic polymer in the mica tape layer.

[Effects of the Invention] As described above, according to the present invention, peeling is performed by applying an inorganic reinforcing material with an adhesive made of an inorganic polymer or an inorganic coating while applying a mineralized silicone or an inorganic coating to a conductor. After winding the mica tape and baking it at a temperature of 300 ° C or higher to make it inorganic, and to form a peeling mica tape with excellent electrical properties and heat resistance on the inner layer that is in contact with the conductor, the mechanical strength is Since it is wound with an inorganic insulating tape that is large and has excellent heat resistance and does not have an adhesive, a heat-resistant insulated wire ring that is electrically and mechanically excellent can be obtained. In addition, this heat-resistant insulating coil does not deteriorate in performance even when used continuously at high temperatures, and does not crack in the insulating layer even if the heat cycle that accompanies the operation / stop of equipment is repeated. , Insulation performance hardly deteriorates. Therefore, it is possible to provide a manufacturing method suitable for a heat-resistant insulating coil used at a high temperature of 300 ° C. or higher, such as an electromagnetic pump for circulating liquid sodium in a primary cooling system of a fast breeder reactor.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the heat-resistant insulating coil according to the present invention, and FIGS. 2 and 3 are cross-sectional views of a heat-resistant insulating coil showing a comparative example with the embodiment of the present invention. is there. 1 ... Conductor 2 ... Nickel-plated alumina dispersion strengthened copper 3 ... Assembled mica tape 4 ... Mineralized silicone or inorganic adhesive 5 ... Peel off mica tape 6 ... Inorganic insulating tape without adhesive 7: Integrated mica tape 8: Prepreg-shaped inorganic insulating tape

Claims (3)

(57) [Claims] 1. A mica tape obtained by bonding a peeling mica and an inorganic reinforcing material to each other by using an adhesive made of an inorganic polymer or an inorganic coating on a conductor and winding the same at 300 ° C.
A method for producing a heat-resistant insulating coil, which comprises firing an inorganic polymer or an inorganic coating material at the above temperature. 2. The method for producing a heat-resistant insulated wire according to claim 1, wherein an inorganic polymer or an inorganic coating is applied when the mica tape is wound. 3. A heat-resistant insulating coil according to claim 2, characterized in that, after winding the mica tape, an inorganic insulating tape having high mechanical strength and excellent heat resistance is wound. Manufacturing method.