JPH0287607A - Resin-molded coil - Google Patents

Abstract

PURPOSE:To largely enhance a thermal deformation temperature by a method wherein a polyurethane insulating film having solderability and a polyamideimide insulating film are formed one after another on a conductor, an insulating electric wire of a double structure where a ratio of a film thickness of the polyamideimide insulating film to a total film thickness is specified is wound to be a coil shape and, after that, an epoxy resin is molded. CONSTITUTION:A polyurethane insulating film having solderability is manufactured in such a way that a polyurethane insulating paint composed mainly of a stabilized polyisocyanate and a polyol is coated and baked. A polyamideimide insulating film is formed by coating and baking a polyamideimide insulating paint; the polyamideimide insulating paint is an insulating paint composed mainly of a polyamideimide resin or a polyamideimide precursor resin. When the polyamideimide resin obtained by a reaction of an aromatic tricarboxylic acid anhydride or its derivative with an aromatic diisocyanate is used, a better effect is displayed to be preferable. It is required that a film thickness of the polyamideimide insulating film occupies a ratio of 5 to 40% to a total film thickness of an insulating electric wire of a double structure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a resin-molded coil in which a coil is impregnated with resin and molded, and then heated and cured to be molded.

(Prior art) Resin molded coils are made by, for example, winding an insulated wire around a plastic bobbin to a predetermined number of turns, and then injecting resin into the coil.
Manufactured by heating and curing in a constant temperature bath, etc.

Polyurethane insulated wires, whose terminals can be peeled off by soldering, are often used as insulated wires. Furthermore, as the resin for molding, epoxy resin is often selected from the viewpoints of price and quality.

Typical resin-molded coils, such as automobile ignition coils and television flyback transformers, use thin insulated wires of several tens of microns on the secondary side, and apply high voltages of several thousand volts to the coils.

Therefore, it is essential to use a polyurethane insulated wire that can be soldered as the insulated wire, and an epoxy resin with good V- characteristics as the molding resin.

(Problems to be Solved by the Invention) As mentioned above, epoxy resin is generally used as a resin for molding a polyurethane insulated wire as a resin-molded coiled wire.

Recently, equipment has become smaller and more sophisticated, the ambient temperature in which the equipment is used has increased, and the parts used have been required to have higher heat resistance.

Epoxy resin molded coils are also being used at higher ambient temperatures.

As a result, the insulation film of the polyurethane insulated wire in the epoxy resin molded coil begins to undergo thermal deformation, and in severe cases, the conductors come into contact with each other, causing a layer short circuit.

Instead of polyurethane insulated wire, we used heat-resistant urethane insulated wire, which has improved heat resistance by introducing imide components and incyanuric ring structures into the molecule, but contrary to expectations, the heat distortion temperature did not improve significantly.

On the other hand, if polyester insulated wire or polyester imide insulated wire is used instead of polyurethane insulated wire,
Although thermal deformation of the film does not occur, the insulated wire cannot be soldered, resulting in low productivity in the manufacturing process and high production costs for epoxy resin molded coils.

For this reason, there is a demand for insulated wires that can be soldered and are less prone to thermal deformation when made into epoxy resin molded coils.

(Structure of the Invention) In the present invention, a polyurethane insulating film having brazeability and a polyamide-imide insulating film are sequentially formed on a conductor, and the ratio of the polyamide-imide insulating film thickness to the film thickness is 40%.
This is a resin molded coil characterized by having the following double structure insulated wire wound into a coil shape and then molded with epoxy resin.

In the present invention, the polyurethane 1 insulating film with brazing properties refers to polyurethane insulating coatings containing stabilized polyisocyanates and polyols as main components, and generally used as additive resins for insulating coatings such as phenolic resins, melamine resins, and polyamide resins. It includes combinations of those used.

An example of the stabilized polyisocyanate is Desmodur AP Stable manufactured by Bayer, which is a polyisocyanate obtained from 3 moles of toluene diisocyanate and 1 mole of trimethylolpropane, which is stabilized using phenols as a masking agent.

Coronate AP Stable manufactured by Nippon Polyurethane Co., Ltd., Millionate MS-50 manufactured by Nippon Polyurethane Co., Ltd., which uses diphenylmethane diisocyanate as a masking agent with xylenol compounds, and Japan Polyurethane, which uses polyisocyanate obtained from diphenylmethane diisocyanate and trimethylolpropane as a masking agent with xylenol compounds. There are Coronate 2503 and other products made by the company.

Examples of polyols include phthalic anhydride, adipic acid, phthalic anhydride, terephthalic acid, and isophthalic acid.
One or more basic acids, dihydric alcohols such as ethylene glycol and propylene glycol, and glycerin,
Polyester polyols obtained from one or more trihydric alcohols such as trimethylolpropane and 2-hydroxyethyl isocyanurate can be used.

Equivalent products include Ninoboran 2006 manufactured by Nippon Polyurethane Co., Ltd., and Desjohen 8 manufactured by Sumitomo-Vinyl Co., Ltd.
There are 00 etc.

In addition, it is also possible to use ester imide in which an imide group is introduced into the molecular skeleton.

A polyamide-imide insulating film is obtained by applying and baking a polyamide-imide insulating paint. A polyamide-imide insulating paint is an insulating paint whose main component is a polyamide-imide resin or a polyamide-imide precursor resin, and some of it is made of epoxy resin, It includes combinations of resins commonly used as additives for insulating coatings, such as phenolic resins, polyisocyanates, and stabilized polyisocyanates.

A typical example of a method for producing polyamide-imide resin or its resin solution, or polyamide-imide precursor resin or its resin solution, which is the main component of polyamide-imide insulating paint, is to use at least one tricarboxylic acid anhydride acid chloride and at least one tricarboxylic acid anhydride acid chloride. Some react with diamines. Further, a part of the acid chloride of the above tricarboxylic acid anhydride is at least -m dicarboxylic acid dichloride or at least
One kind of tetracarboxylic dianhydride, or at least -m dicarboxylic dichloride may be replaced with at least one kind of tetracarboxylic dianhydride.

Further, a part of the above diamine may be replaced with at least one kind of triamine,
Alternatively, at least one type of tetramine, or at least one triamine and at least one tetramine may be replaced.

Examples of the acid chloride of tricarboxylic anhydride include 4-acid chloride of trimellitic anhydride.

Examples of dicarboxylic acid dichloride include terephthalic acid dichloride, isophthalic acid dichloride, adipic acid dichloride, and the like.

Examples of diamines include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether m-phenyl diamine, and the like. An example of triamine is
Examples include 3,4,4'-1 riaminodiphenyl ether. Examples of tetramines include 33', 4. ．． Examples include 4'-tetraaminodiphenyl ether.

Another typical manufacturing method involves reacting at least one tricarboxylic anhydride with at least one diisocyanate. Also, a part of the above tricarboxylic anhydride is replaced with at least one dicarboxylic acid, or at least one tetracarboxylic dianhydride, or at least one dicarboxylic acid and at least one tetracarboxylic dianhydride. Good too.

Further, a part of the above diisocyanate may be at least one type of 3
It may be replaced with a polyisocyanate having a polyhydric acid or higher.

Examples of tricarboxylic anhydrides include trimellitic anhydride.

Examples of dicarboxylic acids include isophthalic acid, terephthalic acid, adipic acid, and the like.

Examples of tetracarboxylic dianhydride include pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and the like. Examples of diisocyanates include diphenylmethane-4,4/-diisocyanate, diphenyl ether-4,4'-diisocyanate, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and the like.

Examples of polyisocyanates include polymethylene polyphenylene polyisocyanate.

Among them, it is preferable to use a polyamide-imide resin obtained by reacting an aromatic tricarboxylic acid anhydride or its derivative with an aromatic diincyanate because the effects of the present invention can be more effectively exhibited.

In the present invention, the thickness of the polyamide-imide insulation film must account for 5 to 40% of the thickness of the double-structured insulated wire. If it is less than 5%, the thermal deformation of the insulating film after epoxy resin molding will not improve, and if it exceeds 4096, the ends of the insulated wire cannot be exposed by soldering. Although any epoxy resin can be used for the molded coil, the following are commonly used.

An amine-curing type epoxy resin made of a combination of an epoxidized metal such as bisphenol A diglycidyl ether or bisphenol F diglycidyl ether and a polyamine compound such as triethylene triamine, inphorone diamine, phenylene diamine, diaminodiphenyl ether, or methylene dianiline, as described above. An acid anhydride-cured epoxy resin consisting of a combination of an epoxy compound and an acid anhydride f arsenic such as phthalic anhydride, trimellitic anhydride, maleic anhydride, and pyromellitic anhydride; Examples include epoxy resins containing trifluoroboric acid, polyisocyanates, and imidazoles.

Of course, it is also possible to add fillers, colorants, etc.

The present invention will be explained in detail in the following examples, but the present invention is not limited to these examples. The following reference examples show insulating paints used in comparative examples and examples.

Reference example 1. (Polyamide-imide insulation coating) Trimellitic anhydride 192, Ig (1.0 mol) and diphenylmethane-4,4'-diisocyanate 250.3 g (1,
0 mol) and 770 g of N-methyl-2-pyrrolidone and solvent naphtha (Maruzen Petrochemical Swazol #11
000) 330 and reacted at 80°C for 3 hours, the temperature was raised to 165°C in 6 hours, and at this temperature 2
A polyamide-imide insulating paint was obtained by a time reaction. The reduced specific viscosity of the resin was 0.54.

(Comparative Example 1) Polyurethane insulation paint (Nitto Denko Corporation Delacor) u-8
08=This polyurethane insulating paint was used in all the following examples) was coated and baked on a 0.3 nunφ copper conductor to obtain a polyurethane insulated wire with a coating thickness of 0.020 aun.

After winding the above polyurethane insulated wire in 5 layers around a 2 cm square PBT bobbin, epoxy resin (T
After injecting CG 1577A/B) and vacuum defoaming 9
It was cured at 5°C for 6 hours and at 1508C for 3 hours to obtain a coil molded with epoxy resin.

(Example 1) Polyurethane insulation paint was applied to a 0.3 mm diameter copper conductor.
After baking to a film thickness of 0.015n+m, the polyamide-imide insulation paint epithelial film thickness prepared in Reference Example 1 was 0.005n+m.
Coat and bake so that it becomes man, and the film thickness is 0.020 this time.
An insulated wire of mm was obtained.

A coil was obtained by molding epoxy resin using the above electric wire in the same manner as in Comparative Example 1.

(Example 2) An insulated wire and an epoxy mold resin were obtained in the same manner as in Example 1, except that the polyurethane insulating paint was 0.1018 mm thick and the polyamide-imide insulating paint was 0.002 mm thick.

(Comparative Example 2) An insulated wire and an epoxy mold resin were obtained in the same manner as in Example 1, except that the polyurethane insulating paint was 10,010 mm thick and the polyamide-imide insulating paint was 0.010 mm thick.

(Reference Example 1) The epoxy resin molded coils obtained in Comparative Examples 1 and 2 and Examples 1 and 2 were heat-treated under two temperature conditions: 160° C. for 1 hour and 180° C. for 1 hour.

When we cut samples heat-treated under each temperature condition and observed the state of the insulating film using a microscope, we found that 180°
There was some deformation in the insulation film of the epoxy resin molded coil of Comparative Example 1 that was heat treated at CX for 1 hour, but other 180°C
No deformation of the insulation film was observed in the epoxy resin molded coils of Examples 1 to 3 that were heat-treated for 1 hour and in all the epoxy resin molded coils that were heat-treated at 160° C. for 1 hour.

The results are summarized in Table 1.

(Reference Example 2) 410° of insulated wires obtained in Comparative Examples 1 and 2 and Example 1.2
The solderability of C was investigated. Comparative Example 1, Example 1.2
Although the insulated wire of Comparative Example 2 could be soldered, the insulated wire of Comparative Example 2 could not be soldered.

The results are summarized in Table 1.

Table 1 (Effects of the Invention) As explained above, when the insulated wire of the present invention is used, the heat resistance of the coil molded with epoxy resin can be improved compared to the conventional polyurethane insulated wire Q. It also maintains the same solderability as conventional polyurethane insulated wire.
Ideal for epoxy resin molded coils such as ignition coils and flyback transformers.

Therefore, the industrial value of the present invention is great.

Claims (2)

[Claims] (1) A double structure in which a polyurethane insulating film with brazing properties and a polyamide-imide insulating film are sequentially provided on the conductor, and the ratio of the polyamide-imide insulating film thickness to the total film thickness is 5% to 40%. A resin molded coil characterized by insulated wire wound into a coil and then molded with epoxy resin. (2) The resin molded coil according to claim 1, wherein the polyamide-imide insulating film is a compound obtained by reacting an aromatic tricarboxylic acid anhydride or a derivative thereof with an aromatic diisocyanate.