JPS6145936B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a method of manufacturing a magnet wire having an improved double coated insulation structure. Currently, for example, polyester resins obtained by using aromatic dicarboxylic acids such as terephthalic acid as the main component of the polycarboxylic acid component and reacting polyhydric alcohols containing polyhydric alcohols of trihydric or higher hydric acid are being used. An insulated wire obtained by applying an insulating paint dissolved in a certain amount of solvent onto a conductor, heating it at a temperature of 300°C or higher, and curing it by free hydroxyl groups in the resin exhibits excellent electrical properties. Widely used as magnet wire. In order to facilitate the formation of an insulating coating on the conductor, the insulating paint used for such magnet wires is generally used by adjusting the viscosity using a relatively large amount of solvent. The solvent used for this is a mixture of phenols such as phenol, cresol, and xylenol with addition of xylene, solvent naphtha, etc. as a diluent, but these solvents are highly toxic and cannot be recovered sufficiently. Currently, some of the waste is burned and emitted. Therefore, from the viewpoint of improving the working environment and saving resources, there has been a strong desire for a method of manufacturing magnet wire without using solvents. In response to these demands, at least non-linear polyester resins that can be cured by free hydroxyl groups have been developed.
Method of coating while heating and melting at 100℃ (Tokukosho)
51-24704) is being attempted. The polyester resin used in this case must be a resin that has been condensed to such an extent that substantially no condensation reaction occurs when melted. On the other hand, if a high condensation resin is used to achieve sufficient properties, melt coating becomes difficult, and in order to alleviate this problem, it is necessary to add a small amount of solvent.
This deviates from the original purpose. Furthermore, a method of manufacturing an enameled wire type insulated wire by extrusion molding a thermoplastic resin such as polyethylene terephthalate onto a conductor (Japanese Patent Laid-Open No. 55-4875
However, since the insulated wire obtained by this method is simply a conductor coated with thermoplastic resin, the resulting insulation coating has insufficient hardness, thermal softening properties, and other thermal properties. When insulated wires are used as magnet wires, the following drawbacks have been found. In other words, since these resins are crystalline polymers, if they are stretched or bent during coil processing, microscopic cracks, or so-called crazing, will occur in the coating, reducing the electrical properties, and the coil drying process and equipment When the resin was heated to a temperature higher than its crystallization temperature, loss of flexibility due to crystallization was observed. In addition, as a test method for heat deterioration resistance of enameled wire, JIS C
3203, 3210, 3211, etc., which observes the flexibility after heating for a predetermined period of time (e.g., the windability of polyester enamelled copper wire after heating at 200°C for 6 hours), it is also possible to observe the flexibility due to crystallization of the coating resin. This results in a complete loss of flexibility. Also,
These thermoplastic resins also have a disadvantage in that they are inferior in mechanical strength, particularly in abrasion resistance as specified by JIS. The inventors conducted extensive research to obtain a polyester-insulated magnet wire that does not use solvents and does not have the above-mentioned drawbacks. As a result, the inventors conducted a thorough study to obtain a polyester-insulated magnet wire that does not use solvents and does not have the above-mentioned drawbacks. A highly gelled polyester resin is obtained by heat treatment at a temperature higher than the melting point of the resin, and an insulated wire obtained by using the resin layer as a lower layer and coating the outside with a thermoplastic polyamide resin is produced as described above. The present invention was achieved by discovering that the above drawbacks are overcome and the magnet wire has the necessary characteristics comparable to magnet wires manufactured using conventional solvent-based paints. That is, the method of the present invention uses an ester bond as a main component on a conductor, which is composed of an acid component mainly consisting of an aromatic group or a dicarboxylic acid whose part is replaced with an aliphatic group, and a diol component mainly consisting of an aliphatic diol. After melting or extrusion coating a substantially linear polyester resin, this is used in an oxygen atmosphere at a temperature higher than the melting point of the resin until the gel fraction of the polyester resin reaches 20% by weight or more. After being heated and crosslinked, a thermoplastic polyamide resin is coated on the outside by melting or extrusion so that the coating thickness is 50% or less of the total coating layer thickness. Examples of the aromatic dicarboxylic acid component of the linear polyester resin in the present invention include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, Examples include diphenyl ether dicarboxylic acid, methyl terephthalic acid, and methyl isophthalic acid, with terephthalic acid being particularly preferred. In addition, 30 mol% or less of aromatic dicarboxylic acid, which is an acid component,
Preferably, aliphatic dicarboxylic acids such as succinic acid, adipic acid, and sebacic acid may be contained in a proportion of 20 mol% or less. Examples of aliphatic diols constituting the straight complex polyester resin include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexanediol, and decanediol, with ethylene glycol and tetramethylene glycol being particularly preferred. Further, a portion of the aliphatic diol may be oxy(alkylene) glycol, such as polyethylene glycol or polytetramethylene glycol. Typical polyester resins obtained from these components include polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene naphthalate resin, and the like. On the other hand, the thermoplastic polyamide resin used for the upper layer coating includes aliphatic, alicyclic, or aliphatic and aromatic copolymer polyamide resins, and 6,6-nylon is generally used. In the present invention, the gel fraction of polyester resin refers to the polyamide layer removed from an insulated wire using hydrochloric acid, formic acid, etc., then the polyester resin film is removed and heated at 90°C using m-cresol. It is the ratio of undissolved residue to the weight of the sample resin coating when it is dissolved, and if this undissolved residue is less than 20%, the characteristics of the double-coated insulated wire of the present invention as a magnet wire cannot be obtained. It becomes difficult. Furthermore, if the polyamide coating thickness is 50% or more of the total coating layer thickness, heat resistance will deteriorate, which is undesirable. Furthermore, the effect of coating the upper layer with polyamide is that mechanical properties, particularly abrasion resistance and surface slipperiness, are improved. Next, examples of the present invention will be shown. Example 1 Polyethylene terephthalate resin (trade name Tetron TR4550BH manufactured by Teijin Ltd., hereinafter referred to as PET, melting point 250-260°C) was extruded onto a copper wire having a diameter of 0.85 mm using an extruder to a thickness of 27 μm. The extrusion conditions are 260-280-300℃ from the inlet to the exit of the extruder, and 300℃ at the head.
°C, linear velocity 100 m/min. The extrusion-coated wire was immediately passed through a heating furnace (furnace length: 5 m, furnace temperature: 400°C) 5 times to heat crosslinking. CM3001 (melting point 255℃) was extruded to a thickness of 11μ. Extrusion conditions are 250−270− from inlet to outlet.
290℃, head part 290℃. In order to examine the gel fraction of the polyester coating layer, the gel fraction of the lower layer resin was measured using the method described above using the insulated wire thus obtained, and it was found to be 93%. Example 2 PET was produced using the same extrusion conditions as in Example 1.
After extruding to a thickness of 25 μm, it was passed through a heating furnace twice to heat crosslink, and then 6.6-nylon was extruded on top of this to a thickness of 10 μm using another extruder under the same conditions. Note that the gel fraction of the polyester resin in the lower layer was 35%. Reference example 1 PET was produced under the same extrusion conditions using the equipment of Example 1.
After extruding to a thickness of 25μ, 6.6-nylon was added to 10% of this in another extruder under the same conditions without passing it through a heating furnace.
It was extruded to a thickness of μ. Note that the gel fraction of the lower layer polyester resin was 0%. Reference example 2 PET was produced under the same extrusion conditions using the equipment of Example 1.
After extruding it to a thickness of 17μ, it was passed through a heating furnace three times to heat crosslinking, and then 6.6-nylon was extruded on top of this to a thickness of 20μ using another extruder under the same conditions. Note that the gel fraction of the lower layer polyester resin was 52%. Comparative Example 1 PET was heated to 33μ using the same conditions as in Example 1.
An insulated wire was obtained by extruding it thickly. Comparative Example 2 After extruding PET to a thickness of 33 μm under the same conditions as Comparative Example 1, it was heat-treated by passing it through a heating furnace with a furnace length of 5 m and a furnace temperature of 400° C. five times. Examples 1-2, Reference Examples 1-2, and Comparative Example 1
- Characteristics of each insulated wire obtained in 2.
Table 1 shows the results measured according to JIS C 3210.

【table】

[Table] As is clear from the above examples, the insulated wire obtained by the method of the present invention maintains various excellent properties, and its practical value is extremely large.

Claims (1)

[Claims] 1 Substantially straight chain whose main component is an ester bond consisting of an acid component mainly consisting of dicarboxylic acid with aromatics or part of them replaced with aliphatic on the conductor, and a diol component mainly consisting of aliphatic diol. After melting or extruding polyester resin,
This is heated in an oxygen atmosphere at a temperature higher than the melting point of the resin used until the gel fraction of the polyester resin becomes 20% by weight or higher to crosslink it, and then a thermoplastic polyamide resin is coated on the outside to the full thickness. 50 thick
% or more.