JPS638566B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-resistant insulated wire, particularly a heat-resistant insulated wire that can be used at high temperatures of 300° C. or higher. Conventionally known heat-resistant enameled wires include polyimide wires, polyamide-imide wires, and polyester-imide wires, each with a wire resistance of 220 to 250.
℃, 180-220℃, and 155-180℃, and can be said to have considerable heat resistance, but since they are all composed of organic insulation films, they decompose at high temperatures of around 400℃. Therefore, its use was limited to temperatures up to 250°C. On the other hand, glass windings made by wrapping glass threads around a conductor to insulate them are also known as heat-resistant insulated wires, but such glass windings usually include glass threads and glass threads for the purpose of improving insulation and preventing fraying. An organic insulating paint was applied between them, so its heat resistance was only around 180 degrees Celsius, and it also had the disadvantage of being inferior to Space Factor. In recent years, it has been used for nuclear power generation, geothermal power generation, and other special purposes.
There is a demand for magnet wires that can be used at high temperatures of 300°C or higher, and inorganic wires coated with inorganic materials are being considered, but such inorganic wires are generally porous and have poor flexibility and insulation, making them impractical. The current situation is that it has not been standardized. On the other hand, the present inventors have studied and previously applied for a polyborosiloxane resin that has a skeleton of silicon, boron, and oxygen and can be used as an electrically insulating paint. Although it is fully satisfactory, the flexibility and electrical insulation properties are lowered, and if the firing degree is weakened, the opposite result occurs, and so far no wire has been obtained that satisfies all the properties required for an enameled wire. The present inventors have discovered that by overcoating the above-mentioned polyborosiloxane resin-coated insulated wire with an aromatic polyimide resin, it can be used even at high temperatures of 300°C or higher, while reducing flexibility and insulation properties. We have discovered that it is possible to obtain an insulated wire without any cracks. The present invention has been made based on the above findings, and relates to a heat-resistant insulated wire characterized in that a conductor is coated with a polyborosiloxane resin and further coated with an aromatic polyimide resin. The polyborosiloxane resin used in the present invention is
(a) boric acid compounds such as orthoboric acid, metaboric acid, boric anhydride, boric acid methyl ester, borax,
(b) Silane compounds represented by SiX ₄ , SiRX ₃ , SiRR'X ₂ (wherein R and R' are methyl or phenyl groups,
X is a hydroxyl group or chlorine, and in the case where It is obtained by heating the polycondensate at 50 to 800°C to carry out a polycondensation reaction. When the reaction temperature is 300°C or higher, it is preferable to carry out the reaction under an inert atmosphere, and the reaction may be carried out in two stages. When producing polyborosiloxane resins, it is preferable to use silanol compounds (hydroxysilanes) because the chlorine-containing silane (b) generates hydrogen chloride, which is unfavorable in terms of the working environment. Also, based on the total amount of boric acid compound (a) and silane compound (b),
If 5% by weight or more of silicone oil is added and the polycondensation reaction is carried out, it is desirable to use this method because a wire coating having better flexibility can be obtained. The viscosity of silicone oil at 25℃ is
Dimethylsilicon or methylphenylsilicon or mixtures thereof of 1.0 centistokes, preferably 10 centistokes or more are suitable. The aromatic polyimide resin used in the present invention is made of 3,3',4,4'-benzophenone tetracarboxylic dianhydride and a special aromatic diamine, as described in Japanese Patent Publication No. 46-17145, for example. Suitable are those obtained by heating and polycondensing in a phenolic solvent such as cresol (such as TUE5051 manufactured by Toshiba Chemical Co., Ltd.).
Others, such as Pile ML (product name manufactured by DuPont),
Obtained by addition reaction of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in a special polar solvent such as N-methylpyrrolidone (NMP) or dimethylacetamide (DMAc) at a low temperature of around 10°C. Some varnishes are made from polyamic acid resin solution, which is a precursor of polyimide, but the former is cresol-soluble because the life of the varnish is short and requires low-temperature storage, and expensive special solvents are used. The aromatic polyimide resin is more preferable. The insulated wire in the present invention is a copper wire or a Ni wire plated with Ni, Ag, etc., by dissolving the above-mentioned polyborosiloxane resin in a scorable solvent such as cresol, tetrahydrofuran, or N-methylpyrrolidone to make an electrical insulation coating. Coating and baking on Ag wire,
Further, an aromatic polyimide resin paint is applied and baked on top of this. Next, an example will be described. [Example 1] 432 g (2 moles) of diphenyldihydroxysilane, 83 g (1.3 moles) of boric acid, and 256 g of dimethyl silicone oil of 10 centistokes were placed in a flask and gradually heated and stirred from room temperature to 400°C in a nitrogen atmosphere. (approximately 6 hours), and was further heated and stirred at 400° C. for 1 hour to carry out the condensation reaction. 66g of water and 70g on the way
g of unreacted low molecular weight silicone oil was boiled off. The reaction product obtained was a colorless solid, and the yield was 525 g. The number average molecular weight of this reaction product was 2500, and the survival rate after firing up to 700°C was 55%. 350 g of this reaction product was dissolved in 450 g of metacresol to prepare an insulating paint.
This paint was applied to a 1.0mmφ Ni-plated (coating thickness 1.5μ) copper wire using a vertical baking machine with a furnace length of 7.2m, at a baking temperature of 450.
℃, at a wire speed of 6 m/min, and baked 5 times to obtain an insulated wire with a coating thickness of 20μ.Furthermore, aromatic polyimide resin paint TUE5051 was applied on top of this at 450℃ for 10 minutes.
By baking three times at m/min, a double-coated insulated wire with a coating thickness of 30 μm and good appearance was obtained. The test results regarding the characteristics of the obtained insulated wire were as follows. Flexibility (passing diameter) 1d Breakdown voltage (2-piece twisting method) 6.0kV Pinhole (pcs/5m) 0 Moisture resistance Good heat softening temperature (load 700g, heating method 2℃/min)
600℃ Overcurrent characteristics (β value) 35 [Example 2] TUE5051 was baked 6 times under the same baking conditions as in Example 1 to the insulated wire coated with polyborosiloxane resin obtained in Example 1 to form a 40 μ coating film. A thick insulated wire was obtained. The properties of this product were as shown in Table 1. [Examples 3 and 4] The polyborosiloxane resin insulating paint obtained in Example 1 was applied at a baking line speed of 3 m/min, and dry baking was performed alternately three times to obtain a coating film thickness of 9μ. Obtained insulated wire. On top of this, add TUE5051 at 450℃.
Baking was carried out twice at 10 m/min to obtain an insulated wire with a coating thickness of 14 μm. (Example 3) Also, 450 TUE5051
C. and 10 m/min four times to obtain an insulated wire with a coating thickness of 21 .mu.m. (Example 4) These characteristics were as shown in Table 1. [Examples 5 and 6] Pile-ML was applied to the polyborosiloxane resin-coated insulated wire obtained in Example 1 at 330°C and 3 m/min at 10 m/min.
After baking, an insulated wire with a coating thickness of 30μ was obtained. (Example 5) An insulated wire having a coating thickness of 40 μm was obtained by changing the number of times of coating and baking Pile-ML to 6 times. (Example 6) These characteristics were as shown in Table 1. [Example 7] 432 g (2 mol) of diphenyldihydroxysilane, 104 g of methyl borate, and 368 g of methylphenyl silicone oil of 100 centistokes were placed in a flask, and then a condensation polymerization reaction was carried out under the same conditions as in Example 1. Summer. The molecular weight of the reaction product obtained is
3000, and the firing survival rate up to 700°C was 60%. 350 g of this reaction product was dissolved in 450 g of cresol to prepare an insulating paint. This paint is 1.0mmφ
Ni-plated copper wire was coated with TUE5051 five times at a baking temperature of 450°C and a wire speed of 6 m/min, and then TUE5051 was coated five times in succession to obtain a double-coated insulated wire with a coating thickness of 40μ and a good appearance. Ta. The properties of this product were as shown in Table 1. The reference examples in the table are those coated with polyborosiloxane resin only and those coated with aromatic polyimide resin. Reference example 1 is the polyborosiloxane resin coated wire used in Example 1, and reference example 2 is the wire coated with polyborosiloxane resin used in Example 1. The polyborosiloxane resin coated wire used in Example 3, Reference Example 3 has a coating thickness of TUE5051 coated and baked.
30μ Polyimide Wire, Reference Example 4 shows a polyimide wire with a coating thickness of 30μ coated with Pile-ML and baked.

[Table] As is clear from the above examples, the thermal softening temperature of the insulated wire according to the present invention is much higher than that of the conventional heat-resistant enameled wire, and the mechanical properties
The electrical characteristics are comparable to conventional ones. Furthermore, since it is an enamelled wire, there is no problem of space factor as with glass winding wires, making it extremely effective.

Claims (1)

[Scope of Claims] 1. A heat-resistant insulated wire comprising a conductor coated with a polyborosiloxane resin and further coated with an aromatic polyimide resin. 2 Polyborosiloxane resin is silicone oil,
The heat-resistant insulated wire according to claim 1, which is obtained by condensation polymerization of phenyl or methylsilanol and a boric acid compound, with the addition of hydroquinone if necessary.