JPH0160187B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to polyurethane insulated wires that are often used in windings for coils related to light electrical equipment, and in particular has improved heat resistance, crazing resistance, and flexibility without impairing soldering properties. This invention relates to polyurethane insulated wires. [Conventional technology] In recent years, as devices have become smaller and lighter, polyamide-imide wires, polyester-imide wires, polyimide wires, etc. have been developed as magnet wires with excellent heat resistance. Because of the difficulty in removing the insulating film, polyurethane wires having brazing properties are still currently used, especially for thin enamelled wires. In order to improve the heat resistance properties of polyurethane insulated wires, attempts have also been made to introduce imide groups into the polyol component or polyisocyanate component, but in this case, the heat deterioration resistance is good, but the heat softening resistance is poor. There is a tendency. This is because the introduction of imide groups inhibits solderability, so the crosslinking density of the film is suppressed. [Problems to be solved by the invention] Conventional polyurethane insulated wires using general polyisocyanate blocks as a crosslinking component have low thermal properties, and those that attempt to improve them have the disadvantage that other properties are significantly impaired. It was hot. In recent years, it has been desired to develop insulated wires that have heat resistance of class B and F, which is even higher than the heat resistance class E of conventional polyurethane wires, without impairing the solderability, which is a feature of polyurethane insulated wires. ing. Furthermore, polyurethane insulated wires have the disadvantage of crazing (occurrence of pinholes when elongated by 3%), and preventing this has been a technical issue. The brazing properties and heat resistance properties of polyurethane insulated wires have an antinomic relationship in that improving one will impede the other property, and if the crosslinking density is increased in order to improve the heat resistance properties, the coating There was a risk of crazing occurring due to decreased flexibility. For example, instead of a general-purpose polyester prepolymer having activated hydrogen and a low molecular weight with a hydroxyl equivalent of about 70 to 150, as a polyol component blended into the polyisocyanate block body that is the crosslinking component of conventional polyurethane insulated wires,
Molecular weight with activated hydrogen: 3000, hydroxyl equivalent: 300
Products that use a certain amount of epoxy resin are not completely crazing-free. In addition, it is also possible to use a difunctional isocyanate block, such as diphenylmethane diisocyanate stabilized with xylenoleic acid, as the polyisocyanate component, but it is impossible to completely prevent craze. It is also inferior in heat resistance. The present invention solves the problems of crazing resistance and flexibility in addition to improving the heat resistance of the coating without impairing the soldering properties of polyurethane insulated wires, which allow direct soldering without peeling off the insulation coating. It was successful in doing so. [Means for solving the problem] In the present invention, an epoxy resin having activated hydrogen, which is a new polyol component, and an ε-
The above problem was solved by using a caprolactone-modified epoxy resin obtained by reacting caprolactone. The polyisocyanate block serving as a crosslinking component needs to contain at least an isocyanate compound having an isocyanurate ring in order to impart heat resistance to the resulting polyurethane film, and a specific example is a trimer residue of toluene diisocyanate. Desmodule CT Stable (product name of Bayer AG, Germany) is a polyisocyanate block whose isocyanate groups are stabilized with phenol.
can be mentioned. In addition to this blocked polyisocyanate compound having an isocyanurate ring, in order to compensate for the brittleness of the polyurethane film, for example, 1 mol of trimethylolpropane and 3 mol of toluene diisocyanate are reacted, and the remaining isocyanate groups are stabilized with phenol. Coronate AP Stable (trade name, Nippon Polyurethane Industries, Ltd.), which is a polyisocyanate block, is used in combination as necessary. Bisphenol A-based diglycidyl ether type epoxy resins containing activated hydrogen have difficulty in film formation when the epoxy equivalent is less than 1000.
If it exceeds 4000, problems will arise with the stability of the paint, so an epoxy equivalent range of 1000 to 4000 is preferable.
Specific examples include Epicote 1007 and Epicote 1009.
(trade name of Ciel Corporation, USA), Epotote YD7019 (trade name of Toto Kasei Corporation), etc. This epoxy resin reacts with ε-caprolactone to form a caprolactone-modified epoxy resin, which is used as a polyol component. [Example] Synthesis example of caprolactone-modified epoxy resin (1) 400 g of bisphenol A diglycidyl ether type epoxy resin with an epoxy equivalent of 2000, 450 g of cyclohexanone as a solvent, and a 4-neck separable flask equipped with a stirrer and a cooling tube. The mixture was weighed out, heated to 80°C, and stirred until the epoxy resin was completely dissolved. After dissolving, add 100 g of ε-caprolactone, 12 g of lead stearate as a catalyst,
A solution uniformly dispersed in 50g of cyclohexanone was added dropwise, and after adding the entire amount, the temperature was raised to 180℃ and
The mixture was heated and stirred for hours to synthesize a caprolactone-modified epoxy resin. The end point of the reaction was confirmed by checking the presence or absence of epoxy groups in the system using the hydrochloric acid-dioxane method. (2) The amount of bisphenol A diglycidyl ether type epoxy resin with an epoxy equivalent of 2000.
A caprolactone-modified epoxy resin was synthesized by carrying out the reaction in the same manner as in Synthesis Example (1) except that the amount of ε-caprolactone used was 350 g and 150 g. (3) The amount of bisphenol A diglycidyl ether type epoxy resin with an epoxy equivalent of 2000.
A caprolactone-modified epoxy resin was synthesized by carrying out the reaction in the same manner as in Synthesis Example (1) except that the amount of ε-caprolactone used was 250 g. Preparation of polyurethane insulating paint and production of polyurethane insulated wire Coronate is a blocked polyisocyanate compound obtained by reacting 1 mole of trimethylolpropane with 3 moles of toluene diisocyanate and further stabilizing the remaining isocyanate groups with phenol.
AP stable and Desmodyur CT stable, which is a blocked polyisocyanate compound in which the remaining isocyanate groups of toluene diisocyanate trimer are stabilized with phenol, are used as crosslinking components. The obtained caprolactone-modified epoxy resin was added in the composition shown in Table 1,
A polyurethane insulation paint with a concentration of 30% was prepared by dissolving it in a mixed solvent of m-cresol and xylene. The comparative example was prepared by reacting a blocked polyisocyanate compound with a bisphenol-based diglycidyl ether type epoxy resin (unmodified) having an epoxy equivalent of 1500, or with 1 mol of trimethylolpropane and 1 mol of adipic acid. The obtained low molecular weight polyester prepolymers are shown in Table 1.
This is a polyurethane insulating paint prepared under the same conditions as above.

[Table] The paint prepared as described above was applied to a copper wire having a conductor diameter of 0.35 mm in a uniform thickness and baked to produce a polyurethane insulated wire according to the present invention. Its characteristics are shown in Table 2.

【table】

[Effect]

The polyurethane insulated wire according to the present invention has good heat resistance properties due to the isocyanurate ring of the blocked polyisocyanate compound as a crosslinking component of the polyurethane film, and also has an ester group introduced from the polyol component generated by the reaction between ε-caprolactone and an epoxy group. As a result, heat resistance is further improved. Furthermore, even if a block polyisocyanate compound having an isocyanurate ring is used as a crosslinking component, if the polyol component to be blended with it is the conventional low molecular weight polyester prepolymer or unmodified epoxy resin shown in the comparative example, the resulting polyurethane The film is hard and lacks flexibility and crazing resistance, but the caprolactone-modified epoxy resin used as the polyol component in the present invention has a longer molecular chain than the conventional ones, so it can suppress the rigidity of the film. This gives the film good flexibility and crazing resistance. Furthermore, the polyurethane insulated wire of the present invention not only improves the thermal properties of the coating as described above, but also has excellent soldering properties due to the presence of urethane bonds. In the present invention, the reaction equivalent ratio of the OH group of the caprolactone-modified epoxy resin as a polyol component and the NCO group of the blocked polyisocyanate compound is limited to 1:0.7 to 2.0. This is because the film becomes brittle and there are problems with film formation. [Effects of the Invention] As is clear from the characteristics shown in Table 2, the polyurethane insulated wire of the present invention has a thermal softening temperature of about
It exhibited high heat resistance properties of 290°C, which cannot be obtained with known polyurethane insulated wires, and also achieved properties comparable to conventional ones in terms of solderability. Moreover, by using a specific polyol component, it was possible to impart good flexibility and crazing resistance to the film.

Claims (1)

[Claims] 1 A caprolactone-modified epoxy resin obtained by synthesis of bisphenol A-based diglycidyl ether type epoxy resin having an activated hydrogen having an epoxy equivalent of 1000 to 4000 and ε-caprolactone is used as a polyol component, and this has at least an isocyanurate ring. A blocked isocyanate compound containing an isocyanate compound is combined with the OH group of the above polyol component and the NCO of the blocked isocyanate compound.
Add at a reaction equivalent ratio of 1:0.7 to 2.0 with the group,
A polyurethane insulated wire characterized in that an insulating paint dissolved in an organic solvent is applied and baked onto a conductor directly or via another insulating film.