JPS6357886B2 - - 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 winding wires made by wrapping glass threads around a conductor to insulate them are also known as heat-resistant insulated wires, but such glass windings usually have wires between the glass threads to improve insulation and prevent fraying. It was coated with an organic insulating paint, 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 uses.
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 substances are being considered, but such inorganic wires are generally porous and have poor flexibility and insulation. The current situation is that it has not been put into practical use. On the other hand, the present inventors studied a polyborosiloxane resin that has silicon, boron, and oxygen as skeletons and can be used as an electrically insulating paint, and filed an application earlier. Although this material has the advantage of being able to be coated and baked in the same manner as ordinary enamelled wire, it has problems in the balance between flexibility and heat resistance, and has the drawbacks of poor moisture resistance. The inventors of the present invention conducted intensive studies to improve this drawback, and found that the characteristics could be greatly improved by alternately performing varnish application and baking (passing through the furnace body without applying varnish). We found that there was a significant improvement. That is, the present invention aims to improve the heat resistance of a polyborosiloxane resin coating, which is characterized in that when applying and baking a polyborosiloxane resin insulating paint directly onto a conductor or via another insulating coating, coating and baking are repeated alternately. The present invention relates to a method for manufacturing a conductive insulated wire. The polyborosiloxane resin used in the present invention is
(a) dimethyl silicone oil or methylphenyl silicone oil having a viscosity of 1.0 centistokes or more, preferably 10 centistokes or more at 25°C; and (b) a silane compound represented by SiX ₄ , SiR ₃ , or SiRR′X ₂ (in the formula R, R' are methyl group or phenyl group,
(X is a hydroxyl group or chlorine, and if X is a hydroxyl group, it also includes its dehydrated condensate) and (c) a boric acid compound such as orthoboric acid, metaboric acid, boric anhydride, boric acid methyl ester, borax, etc. It is obtained by heating at ~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. The ratio of each of the above components is 1:10 to 10:1, preferably 1:3 to 3:1 equivalent molar ratio (mol multiplied by the number of functional groups). ) is appropriate, and (a) silicone oil is
A suitable amount is 5% by weight or more based on the total amount of the silane compound (b) and the boric acid compound (c). In the production of polyborosiloxane resin, it is preferable to use a silanol compound (hydroxysilane) since the chlorine-containing silane (b) generates hydrogen chloride, which is unfavorable in terms of the working environment. Moreover, the degree of polymerization can be increased by further adding hydroquinone. The polyborosiloxane resin thus obtained is dissolved in a bakeable solvent such as cresol, N-methylpyrrolidone (NMP), tetrahydrofuran, dimethylacetamide (DMAc), etc. to make an electrical insulating paint, and Ni, Ag, etc. are plated. Coat and bake on copper wire, Ni wire, or Ag wire. In this case, under normal baking conditions, the polyborosiloxane resin is the same as the varnish state.

[Formula] This structure has good flexibility and electrical insulation, but has poor moisture resistance and heat resistance. To increase moisture resistance and heat resistance, increase the baking temperature or bake separately.

[Example 1]

432g (2 moles) of diphenyldihydroxysilane,
Put 83 g (1.3 mol) of boric acid and 256 g of 10 centistoke dimethyl silicone oil into a flask, and gradually heat and stir from room temperature to 400°C in a nitrogen atmosphere (about 6 hours), and then heat and stir at 400°C for 1 hour. A condensation polymerization reaction was carried out. During the process, 66 g of water and 70 g of unreacted low molecular weight silicone oil were removed by boiling. 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 obtain an insulating paint. Apply this paint to a 1.0mmφ nickel plate (film thickness 1.5μ).
Using a vertical baking machine with a furnace length of 7.2 m, coating and baking the copper wire were alternately repeated 8 times at a baking temperature of 450°C and a wire speed of 5 m/min to obtain an insulated wire with a film thickness of 25 μm. The breakdown voltage of this insulated wire is 5.0KV, and the passing diameter is
3d, thermal softening temperature is over 600℃, current carrying characteristics (β
value) was 45. The breakdown voltage after being left in 100% humidity for 24 hours was 2.0KV. [Examples 2 to 4] Each component in Table 1 was reacted under the same reaction conditions as in Example 1, and dissolved in cresol to obtain an insulating paint.
This paint was applied and baked 8 times alternately at 450° C. at 5 m/min to obtain an insulated wire. The properties of this product are shown in Table 1. The reference examples in the table are those in which the polyborosiloxane resin solution produced in Example 1 was coated and baked 8 times at a baking temperature of 450°C and a line speed of 5 m/min (Reference Example 1), and this was further applied 8 times. Shown is a re-baked product (Reference Example 2).

[Table] (Numbers without units in the table represent weight)
As is clear from the above examples, according to the method of the present invention, the moisture resistance was improved and an enameled wire with a well-balanced heat resistance and mechanical properties could be obtained.

Claims (1)

[Claims] 1. A polyborosiloxane resin coating characterized in that when applying and baking a polyborosiloxane resin insulating paint directly onto a conductor or via another insulating coating, coating and baking and dry baking are repeated alternately. A method for manufacturing heat-resistant insulated wire. 2. The polyborosiloxane resin insulating paint is obtained by polycondensing silicone oil, phenyl or methylsilanol, and a boric acid compound with the addition of hydroquinone if necessary, and dissolving the resultant in a stoving solvent. A method for manufacturing a heat-resistant insulated wire coated with polyborosiloxane resin.