JPS60195168A - Manufacture of flat-type polyurethane-insulated electric wire - Google Patents

Abstract

PURPOSE:To obtain the titled electric wire having excellent solderability and high ratio of the width to the thickness, by coating a round conductor with a polyurethane insulation coating composed of a polyisocyanate block compound and an activated hydrogen-containing oligomer, baking the coating film, and rolling the coated conductor. CONSTITUTION:An insulation coating composition is prepared by (1) compounding (A) a blocked isocyanate prepared by the reaction of a diol having a spiroacetal ring with a diisocyanate compound with (B) a prepolymer having active hydrogen atom (the equivalent ratio of the isocyanate group of the component A to the hydroxyl group of the component B is 1:0.7-2.5), (2) adding (C) a polyamide resin as a flexibilizer to the above mixture, and (3) dissolving the product in (D) an organic solvent. The coating composition is applied to and baked on a round conductor, and then rolled in the form of a flat-square to obtain the objective wire. USE:The voice-coil of a speaker, the stator coil of a miniature motor for VTR, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novel rectangular polyurethane insulated wire.

Senkaku Zetsukei electric wire is used in the voice coil of speakers and the stator coil gutter of small motors for VTRs, and because it has a better space factor than round wire, it satisfies the requirements of being light, thin, short, and small.
Its uses are also increasing year by year. There are two methods for manufacturing rectangular insulated wires: one is to roll a round wire to form a rectangular conductor, and the other is to apply and bake insulating phenol to the outside of the conductor according to a conventional method, and the other is to apply and bake insulating phenol to the outside of the conductor. There is a method of rolling it to transform it into a rectangular insulated wire. However, these rectangular insulated wires manufactured by conventional methods have the following drawbacks. That is, in the former case, it is difficult to obtain a coating film with a uniform thickness, and the coating film is particularly thin at the corners, and the conductor surface at the corners is exposed, causing poor insulation. In the latter case, the ratio of the width to the thickness of the flat wire cannot be increased (approximately 1:2 to 2.5), and the thermal shock resistance of the flat wire after rolling is poor, especially for the above-mentioned applications. It was unsuitable for winding wires. As a manufacturing method for rectangular wire that improves these drawbacks, for example, the method described in Japanese Patent Publication No. 49-7428 has been proposed, but the insulating film used here is
It is limited to highly heat-resistant insulating materials such as polyamideimide, polyimide, polyhydantoin, and polyesterimide, and since none of them have solderability to the insulating film, it is difficult to solder the ends of the coil. However, the disadvantage is that the insulating film must be removed by mechanical or chemical means, and the end treatment of the coil is extremely complicated, especially for thin rectangular wires that are rolled from round wires with a conductor diameter of about 0.1 mm. However, this was a major obstacle to automating production lines.

The present invention has succeeded in obtaining a rectangular polyurethane insulated wire that improves the above-mentioned drawbacks by studying the resin composition of the insulating varnish in a method of obtaining a rectangular insulated wire by rolling an enamelled insulated wire as a leader. This will be explained in detail below.

The brazing properties and heat resistance properties of polyurethane insulated wires are in a trade-off relationship; improving one will impede the other, and the adhesion between the conductor and the insulation film depends on the heat resistance of the insulation film used. , for example, polyurethane, polyester, polyesterimide, etc., the higher the price, the higher the
Thermal shock resistance is also improved. Therefore, there is a limit to the improvement of properties when conventionally used general polyisocyanate block compounds are used as crosslinking components. Therefore, in the present invention, a novel polyisocyanate block compound is synthesized, and this is combined with an oligomer or prepolymer having activated hydrogen. A polyurethane insulating paint dissolved in an organic solvent is coated and baked on the conductor, and then rolled, resulting in solderable properties.
Moreover, it is possible to provide a rectangular polyurethane insulated wire having a large thickness-to-width ratio.

The novel isocyanate crosslinking agent developed by the present inventors is a diisocyanate block product in which a diol having a spiroacetal ring and a diisocyanate compound are reacted, and the remaining incyanate groups are blocked with a phenolic compound. , Structural formula % Formula % A diol with a spiroacetal ring has a skeleton of spiroacetal ring and alcoholic hydroxyl groups at both terminals, so it easily reacts with a diisocyanate compound to form a urethane bond. The preparation for this reaction is carried out with an excess of diisocyanate, and the remaining incyanate groups are blocked and stabilized with a phenol compound.The diisocyanate block is difunctional and has a higher molecular weight than the conventional diisocyanate block. The chain is extremely long.

Examples of the present invention are shown below.

Synthesis Example Synthesis temperature Wl of spiroacetal modified diphenylmethane diisocyanate block crosslinking agent, spiroacetal glycol 91.2i (0.3 mol), Kijirol 3o 6 as a reactive diluent! i', Weigh and add 0.8 g of triethylamine as medium M, and stir thoroughly to uniformly disperse it. Then, in a separatory funnel, heat to 45°C.
Scale ht Cida diphenylmethane diisocyanate 150
1i' (0.6 mol) was gradually added dropwise to react with spiroacetal glycol. At this time, the temperature of the reaction system rises to about 50-60°C. During this time, stir thoroughly. When the temperature of the reaction system returns to room temperature, further nl-
Add 64.8 fF of cresol and continue stirring until it is confirmed that the infrared absorption band 2240cn1 of incyanate disappears. When the reaction was completed, m-cresol 408z was added so that the solid content of the reaction system was 60 cm to obtain a solution of spiroacetal-modified diphenylmethane diisocyanate cresol block compound.

Using the solution 5oofI- of the spiroacetal-modified diisocyanate compound obtained in the synthesis example, an epoxy prepolymer 94f/- of molecules i1 so o o having an alcoholic hydroxyl group was weighed and added thereto, and further a flexibility imparting component was added. As polyamide resin 244? and dissolved these in a mixed solvent of cresol and Kijiroru to a resin concentration of 15%.
The coating thickness is 1 on an annealed copper wire with a conductor diameter of 0.270JEl'l.
Furnace temperature to be 0.0-10.5μ! A polyurethane insulated wire was produced by baking at 180'c and a wire speed of 50 m/+nin.

Next, this was rolled in a four-axis rolling mill with a roll diameter of 25 fins to obtain a rectangular polyurethane insulated wire according to the present invention.

In addition, as a specific example of the polyamide resin added as a flexibility imparting component, Ultramid 1C (Germany 1BA
(SF company product name), Amiran CM-4000 (Toshisha company product name), Bratabond M1276 (Nippon Rilzan company product name), Diamide I, -1801 Diamide N-1901
(Daicel product name) etc.

The properties of the rectangular polyurethane insulated wires of the examples are shown in the table below.The comparative example is a cross-linked wire made by reacting a general-purpose polyisocyanate compound, such as toluene diisocyanate and trimethylolpropane, and blocking the remaining isocyanate groups with phenol. A conventionally known polyurethane paint containing an epoxy prepolymer with a molecular weight of 1II-3000 as a polyol component was applied and baked onto the light guide, and then rolled. Characteristics of rectangular polyurethane insulated wire.

Since the rectangular polyurethane insulated wire obtained by the manufacturing method of the present invention uses a block isocyanate compound having a bulky spiroacetal ring with a long molecular chain as a crosslinking component of the polyurethane film, the distance between crosslinks becomes long. Furthermore, the addition of the polyamide resin improves the removability of the film, resulting in a structure in which the film deforms relatively easily in response to external stress. Therefore, the adhesion between the conductor and the insulating film is good, the film can sufficiently follow the deformation of the conductor, and the stress strain in the film is small. If this were the case, countless cracks would occur in the coating, making it impossible to put it to practical use. However, in the present invention, as seen in the results of the Examples, the properties of the coating can be maintained even in ultra-thin rectangular wires. Furthermore, since the film has a three-dimensional network structure formed by urethane bonding, it is possible to increase the solder resistance by 4" and improve the working efficiency of the coil end portion.

The JJI ratio for the reaction between the isocyanate of the block isocyanate crosslinking agent and the water r49 group of the prepolymer that cures the activated hydrogen atoms was limited to a ratio of 1:0.7 to 2.5 because it was outside this range. In all cases, rack 41-6
This is because the reaction becomes insufficient and the insulating film becomes thermally and mechanically brittle.

As explained above, it is significant that a rectangular polyurethane wire having solderability and a large thickness-to-width ratio can be obtained by the present invention, and the present invention will greatly contribute to industry.

Applicant Tokyo Special Electric Wire Co., Ltd. '· ··to.

Claims (1)

[Claims] Block incyanate obtained by the reaction between a diol having a spiroacetal ring and a diisocyanate compound is used as a crosslinking component, and a prepolymer having an activated hydrogen atom is added to this as a crosslinking component. to the hydroxyl group at a reaction equivalent ratio of 1:0.7 to 2.5, further add polyamide resin as a flexibility imparting component, and dissolve these in an organic solvent to obtain an insulating paint. A method for manufacturing a rectangular polyurethane insulated wire, which comprises applying and baking the wire and then rolling it into a rectangular shape.