DD300736A7 - Coating lacquer for electrical conductors - Google Patents

Abstract

The invention relates to a Ueberzugslack for insulated electrical conductors for producing a thermal bondable layer, are glued to the coreless, cantilever coil in itself. In order to improve the secure and permanent bonding of the windings, 0.5 to 5.0 parts by weight of high molecular weight epoxy resins having an average molecular weight of between 1000 and 4000, based on the phenoxy resin content, are added to the phenoxy resin-based paints. The layers thus produced lead to a more even bonding in a wider temperature range.

Description

Surprisingly, the addition of one or more high molecular weight epoxy resins within the specified concentration limits causes the resulting two-layered enameled wires to be more uniformly adhered over a wider temperature range. By contrast, higher concentrations of epoxy resins lead to a reduction in the caking power and a reduction in the layer elasticity. On the other hand, the addition of low molecular weight epoxy resins with molar mass below 1000 embrittlement of the adhesive layers and also a deterioration of the bonding properties.

In the thermal bonding of the two-layer enameled wires which have been produced by the novel coating of the coating varnish, uniformly good bonding forces are obtained over a wide temperature range. The baking force can be easily determined on special test specimens, so-called winding curls. To prepare the test specimens, a two-layer enameled wire with a Cu conductor diameter of 0.5 mm is wound over a 5 mm mandrel in such a way that a winding corrugation with 10 closely adjacent turns is produced. These specimens are then bonded by storage in a heating cabinet at elevated temperature within 10 minutes and then pulled apart in a tensile testing machine. The pulling resistance of the winding curl, which results from the mean value of the resistances at the moment of loosening the 5th to 7th turns, is considered to be the hardening force.

dk; Caking forces determined on the test specimens agree with the results of the winding test, eg. As to television deflection coils, well. A uniform good baking force over a wide temperature range causes a reduction in the failure rate in baked Femsehablenkspulen.

The coating lacquer according to the invention can be processed at the baking temperatures and lacquering rates customary for phenoxy resin lacquers. Adhesive enameled wires produced in this way show unaltered good enameled wire properties, such. B. layer elasticity and abrasion resistance. They can be processed excellently on modern winding machines and result in flawless baked coils.

Ausführungsbelspiele The invention will be explained in more detail in the following examples. example 1

In a mixture of 100 g of cresol and 200 g of xylene, 163 g of Epikote CL 53 L-32 (Shell Chemicals) and 0.5 g of Epikote 1006 (Shell Chemicals) were dissolved with vigorous stirring to give a clear solution. This gives a paint with a flow time of 58s and a baking residue of 11.5%. On a Drahtlackieraiilage with a furnace length of 2.5 m and catalytic exhaust gas combustion, the coating lacquer was applied by felt coating at a coating speed of 12 m / min and a baking temperature of 36O ⁰ C on a polyester imitation enameled wire (Cu conductor diameter 0.5 mm) and baked. The enameled wires obtained were tested according to the usual "static" criteria and subjected to a "dynamic" winding testing on a production winding machine for Fernsohablenkspulen. The test results are included in the table.

Example 2 In a mixture of 166 g of cresol and 532 g of xylene, 152 g of Epikote OL 53 L-32 (Shell Chemicals), 120 g of Epikote OL 55 L-32

(Shell Chemicals), 2.3 g of Epikote 1006 (Shell Chemicals) and 2.4 g of Epikote 1009 (Shell Chemicals) under intense

Stirring solved. This gives a paint with a flow time of 81 s and a baking residue of 11.9%. The paint was processed under the same conditions as described in Example 1 to a two-layered wire. The Test results are included in the table. Example 3 (comparative example) A mixture of 108 g of cresol and 216 g of xylene with vigorous stirring 176g Epikote OL 53 L-32 (Shell Chemicals)

(32% phenoxy resin solution in ethyl glycol acetate). This gives a varnish with an efflux time of 63s (TGL

RGW 1443.4 mm nozzle) and a burn-in residue of 11.6% (TGL 14303 / 02.1 h / 180 ° C). The paint was processed under the same conditions as described in Example 1 to a two-layered wire. The Test results are included in the table. table

Results of testing the thermally bondable two-layer painted wires

characteristic value Ex.1 Ex. 2 Example 3 Static test - conductor diameter (mm) 0, u 0.5 0.5 Diameter increase basecoat (μηι) 40 40 40 - diameter increase overcoat (pm) 23 21 22 - Adhesive strength during winding 0.5 mm mandrel diameter (TGL43759) I.O. I.O. I.O. - resistance to abrasion In a scraper direction (TGL 43759) (N) 13.2 12.7 12.3 - Verbackkraftnach 10 minutes storage at 170 ^° C (N) 3.2 3.3 3.0 at 200 ^° C (N) 5.6 5.3 4.4 at 22O ⁰ C (N) 5.5 5.4 4.3 be! 25O ⁰ C (N) 5.7 5.3 3.0 at 27O ⁰ C (N) 5.2 5.1 2.1 Dynamic test - winding testing on 200 FS deflection coils Failure (coils) 1 2 12

Claims (1)

Coating lacquer for insulated electrical conductors based on phenoxy resins, characterized in that the lacquer, based on the Phenoxyharzgehalt, 0.5 to 5.0 parts by mass in% of one or more Epoxidharza having average molecular weights between 1000 and 4000. Field of application of the invention The invention relates to a coating varnish for insulated electrical conductors for producing a thermally bondable outer layer. Characteristic of the known state of the art Current-carrying wire wounds in electrical and electronic products are exposed to multiple mechanical and thermal stresses as a result of the occurring electromagnetic effects and the resulting heat. It is common to glue the individual wires together to form a compact structure to protect the windings from deformation or possible mechanical damage. Usually, for this purpose, the wire windings are impregnated with coil dewaxing or with impregnating resins and then cured at elevated temperatures over a relatively long period of time. Over the past 30 years, for a special purpose, for the production of coreless, cantilevered coils, such as. As in micromotors, microphones and deflection units for television picture tubes use, enforced a highly productive technology, which consists in the processing of thermally selbstverklebenden enamel wires. These self-adhesive enamel wires generally carry two different polymer layers, of which the inner has to fulfill the task of electrical insulation and the outer layer should lead by heat to bond and thus solidify the wires with each other. The temperature required for the bonding is advantageously generated by a surge within a few seconds in the winding itself. For such applications, therefore, preferably thermoplastic materials are used. Advantageously, the thermoplastic outer layer of selbstverklebenden enameled wires is produced by painting already provided with a basic insulation copper wires with a so-called adhesive lacquer or baked enamel. Polyvinyl butyral (US Pat. No. 3,516,858), aliphatic polyamides (US Pat. No. 4,163,826) and also phenoxy resins (US Pat. No. 3,917,892) have proved to be suitable binders. For the production of self - supporting coils with complicated geometrical shapes, which require special dimensional accuracy, phenoxy resins have become popular as adhesive lacquer binders due to their high ·. Form stability and low water absorption prevailed. If enameled wires having a phenoxy resin adhesive layer are processed on particularly high-productivity winding automates into complicatedly shaped cantilevered coils such as television plasma coils, it is necessary to set the conditions of the rush current pre-treatment very accurately in order to minimize the scrap production. During the thermal bonding process, which takes place on the metallic winding form, occur within the coil, due to different levels of heat dissipation, very differing temperatures. These temperature differences, which can be up to 150 K, are often the reason for poorly glued coils. Thus, due to the high heat dissipation, often insufficient flow of the adhesive layer can take place on single-layered winding parts. On the other hand, within multi-layered winding areas, owing to the low heat dissipation, the adhesive layer can flow away more or less strongly. In both cases, poor gluing of the wires may result resulting in increased production rejects. Object of the invention It is the object of the invention to provide a coating lacquer for insulated electrical conductors, with which layers can be produced, which allow a secure bonding of the conductors over a wide temperature range. Explanation of the essence of the invention The invention has for its object by suitable additives to modify a Phenoxyharzlack so that it can be produced from outer layers on electrical conductors over a wide temperature range to a secure bonding of the individual conductors in the Stromstoßverklebung. The object is achieved according to the invention by adding 0.5 to 5.0 parts by mass in% of high molecular weight epoxy resins having average molecular weights between 1000 and 4000, based on the phenoxy resin content, as modifying agent to the phenoxy resin coating lacquer. The modification can be carried out by the addition of an epoxy resin or a mixture of several epoxy resins of different molecular weights in the molecular weight range of 1000 to 4000. As phenoxy resins, products with molecular weights of at least 20,000 can be used. Optionally, it is also possible to use several phenoxy resins with different molecular weights as main binder. Conventional mixtures based on cresol and aromatic hydrocarbons and, if appropriate, additions of diol monoethers and / or diol ether acetates can be used as the solvent. If necessary, the lacquer solutions can also be dyed by adding dyes.