JPS6067569A - Polyurethane insulated wire - Google Patents

Abstract

PURPOSE:To provide the titled insulated wire, having solderability and excellent crazing resistance, by coating a conductor with an insulation paint containing a blocked isocyanate containing a specific crosslinking component and a prepolymer having alcoholic OH group, at a specific ratio, and baking the paint. CONSTITUTION:An insulation paint is produced by mixing (A) a blocked isocyanate obtained by the reaction of (i) a diol having spiroacetal ring with (ii) a diisocyanate compound [e.g. the compound of formula (R1 is phenyl, methylphenyl, etc.; R2 is methylphenyl, diphenyl ether, etc.)] with (B) a prepolymer having alcoholic OH group (e.g. epoxy resin) at a ratio to give the equivalent ratio of the NCO group of the component A to the OH group of the component B of 1:0.7-1.2, and dissolving the mixture in an organic solvent. The obtained paint is applied to a conductor directly or via another insulation film, and baked to afford the objective insulated wire.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyurethane insulated wire that has brazing properties and excellent heat resistance and crazing resistance.

Polyurethane insulated wires are widely used in coil windings for light electrical applications because they have brazing properties that allow them to be soldered without peeling the insulating film coated on the conductor. In recent years, with the miniaturization and weight reduction of equipment, insulated wires have emerged that have a heat resistance of Class B, Class 7, which is even higher than Class E, which is the heat resistance classification of conventional polyurethane insulated wires, without impairing the soldering properties. desired. Furthermore, polyurethane insulated wires have drawbacks such as crazing and generation of pinholes (underwater pinholes) when stretched to 3 inches, and preventing this has also been a technical issue.

The brazing properties and heat resistance properties of polyurethane insulated wires are in a trade-off relationship, meaning that improving one will impair the other. Conventionally, using a general polyisocyanate block as a crosslinking component does not improve the properties. Therefore, in the present invention, a novel polyisocyanate block body is synthesized, and an insulating paint made by dissolving this and an oligomer or prepolymer having activated hydrogen in an organic solvent,
We succeeded in obtaining a heat-resistant polyurethane insulated wire by coating and baking it onto a conductor. On the other hand, several types of polyurethane insulated wires with improved crazing have been developed, but these generally have low thermal properties and
For example, as a polyol component to be blended into the polyisocyanate block body serving as a crosslinking component, instead of a general-purpose polyester prepolymer K having activated hydrogen and a low molecular weight with a hydroxyl equivalent of about 70 to 150, an activated phorophore is used. Products using epoxy prepolymers with a molecular weight of 1,000 and a hydroxyl equivalent of about 300 are not completely crazing-free, but do not craze when stretched in 0.2-inch saline and applied a DC 127 to a pinhole test. will occur.

In addition, measures have been taken to use positive isocyanate components 'K, difunctional isocyanate blocks such as phenylmethane diincyanate stabilized with xylenoleic acid, but it is impossible to completely prevent crazing. .

The present invention has also succeeded in solving this problem of crazing resistance.

The new incyanate cross-linking agent developed by the present inventors is a diisocyanate block compound obtained by reacting a suldiol having a spiroacetal ring with a diisocyanate compound, and having the remaining 5-diisocyanate block, specifically, has the structural formula %. Since a diol having a spiroacetal ring has a spiroacetal ring as its skeleton and alcoholic hydroxyl groups at both ends, it easily reacts with a diisocyanate compound to form a urethane bond. This reaction was carried out with an excess amount of diisocyanate, and the diisocyanate block obtained by blocking and stabilizing the remaining incyanate groups with a phenolic compound 4-
Compared to traditional diisocyanate blocks,
The molecular chain is extremely long.

Synthesis Example 1 Spiroacetal modified toluene diisocyanate block (8PG-TD enyresol crosslinking agent)
Spiroacetal glycol 91 was added to a four-piece separable flask equipped with a thermometer, stirrer, cooling tube, and separating funnel.
2% (0.3 mol), quizyrol 26 as reaction diluent
12F and 0.8y- of triethylamine as a catalyst were weighed and added, and the mixture was sufficiently stirred to be uniformly dispersed. Then, in a separatory funnel, weighed toluene diisocyanate (104)
．． 4F (0.6 mol) is added gradually dropwise to react with spiroacetal glycol. At this time, the temperature of the reaction system rises to about 70"C. Stir thoroughly during this time. When the temperature of the reaction system returns to room temperature, 64.89 m-cresol is added to block the remaining isocyanate groups. -, infrared absorption band 2 of incyanate
Continue stirring until it is confirmed that 24° crn-' is gone. At the end of the reaction, m-cresol 3481 was added so that the solid part of the reaction system was 30 cm, and 5PG-TD was added.
Unique cresol blocks body fluids.

Synthesis Example 2 Synthesis of Spiroacetal Modified Diphenylmethane Diisocyanate Block (SPG-MD Enyresol Crosslinking Agent) 9 tons of spiroacetal glycol was placed in a 4-unit parallel flask equipped with a thermometer, stirrer, cooling tube, and separating funnel.
27 (0.3 mol), Kizilol 50 as reaction diluent
6f, triethylamine 0.8 as catalyst? Weigh and add and stir thoroughly to disperse evenly. Then, in a separatory funnel, add the weighed diphenylmethane diisocyanate (15)
0F (0.6 mol) was heated to 45°C as a liquid,
This is gradually added dropwise to react with spiroacetal glycol. At this time, the temperature of the reaction system rises to 50-60°C. During this time, stir thoroughly. When the temperature of the reaction system returned to room temperature, 64.8f of m-cresol was further added to block the remaining isocyanate groups until it was confirmed that the infrared absorption band of isocyanate at 2240 crn disappeared. m-Cresol 408? is added so that the solid part of the reaction system becomes 30% at the end of one reaction with continued stirring. was added to form an 8PG-MDI-cresol block solution.

The OH component for reacting with the blocked isocyanate crosslinking agent to form a urethane bond is a prepolymer having an alcoholic hydroxyl group, preferably a molecule having activated hydrogen! An epoxy prepolymer having a molecular weight of 5.0 oo or more and a hydroxyl equivalent of about 300 is used.

Examples Using the spiroacetal-modified diisocyanate blocks obtained in Synthesis Examples 1 and 2, a prepolymer having an alcoholic hydroxyl group was blended with the prepolymer in the composition shown in the following table, and the resin concentration was 309 g in a mixed solvent of cresol and kijirole. A polyurethane insulating paint was prepared by dissolving the mixture as follows. This paint was applied to a copper wire having a conductor diameter of 0.35 Tu in a uniform thickness and baked to produce a polyurethane insulated wire according to the present invention.

Heat-resistant polyurethane insulation paint composition The properties of the obtained polyurethane insulated wire are shown in the table below.

As a comparative example, the characteristics of a conventionally known general-purpose polyurethane insulated wire that does not contain spiroacetal rings in the coating composition are shown.

A: Temperature at the point where the straight line connecting 20% and 50 inches intersects the connection of 01 B: Temperature at the time of 50 inches reduction = 2.462C Value calculated based on polyimide) Spiroacetal soil to be m1 in the present invention As mentioned above, the blocked isocyanate crosslinking agent has an extremely long molecular chain compared to conventional diisocyanate polymers, and when this is reacted with a prepolymer having an alcoholic hydroxyl group, the crosslinking interval can be made longer. is formed, and the molecular structure of the insulating film resembles that of a cylindrical molecule.

Therefore, in the polyurethane insulated wire according to the present invention, flexibility is imparted to the coating, and heat resistance is greatly improved due to the oxidation-resistant effect of the spiro ring having four oxygen atoms in the ring. That is, as is clear from the characteristic table, the residual ratio of the dielectric breakdown voltage value after heat deterioration, which indicates deterioration resistance, shows a high value of 59 to 68, and the T
The value of G-work also shows a high value of 139-149. At the same time, the problem of cooling, which was a conventional technical issue, was completely resolved.

The reason for limiting the reaction equivalent ratio of the NOO groups of the block isocyanate crosslinking agent to the OH groups of the prepolymer having alcoholic hydroxyl groups to a ratio of 1:0.7 to 1.2 is because if it deviates from this range, In either case, if the crosslinking reaction is insufficient, the insulating film becomes thermally and mechanically brittle.

Claims (1)

[Claims] The resulting block isocyanate is used as a crosslinking component by the reaction between a diol having subioacetal breakage and a diincyanate compound, and a prepolymer having an alcoholic hydroxyl group is added to this as a crosslinking component. A polyurethane insulation characterized by applying and baking an insulating paint on a conductor directly or via another insulating film, which is added at a reaction equivalent ratio of 1:17 to t2 and dissolved in an organic solvent. Electrical wire.