DE1615830B2 - Insulated electrical conductors and processes for their manufacture - Google Patents

Description

The invention relates to insulated electrical conductors with a novel resin combination which is excellent Has thermal stability and good abrasion resistance, usually with paint films insulated electrical conductor made by passing the metallic conductor through a bath of lacquer Resin solution passes through, if necessary several times, and after each painting under the action of heat the solvents evaporate and the resin on the conductor burns and hardens.

For a long time, crosslinked terephthalic acid polyesters have been used to achieve highly heat-resistant wires used. The disadvantages of this resin insulation are, among other things, insufficient Thermal shock resistance and unsatisfactory mechanical properties, especially abrasion resistance Such wire enamel insulation is not high enough to run the wire on modern, fully automatic To be able to process winding machines. These disadvantages can, according to the proposal of the USA 30 22 200 can be partially improved by the fact that the wire provided with the basic insulating layer with an additional coating of a thermoplastic polymer with a melting point over 175 ° C, e.g. B. a high molecular weight linear terephthalic acid glycol polyester, is covered. In this case, however, the dielectric properties become especially in the heat due to the linear polyester worsened.

On the other hand, there has recently been a completely new class of materials for the electrical insulation of conductors found. These are the polyhydantoins. The production of such polyhydantoins is z. B. in DT-AS 12 30 568 described.

The polyhydantoin lacquer films show good short-term thermal overloadability and good mechanical properties Properties.

The invention was based on the object, the elasticity and especially the abrasion resistance and the thermal properties of crosslinked terephthalic acid polyesters to improve insulated electrical conductors without reducing the dielectric properties to deteriorate. This object is achieved by the invention specified in claim 1. Above all, the coatings according to the invention have improved heat shock resistance. aside from that show these coatings in comparison with the known coatings of US Pat. No. 3,022,200 increased resistance to saponifying agents, especially acidic media.

The figure shows the structure of the conductor insulation according to the invention. On an electrical conductor z. B. a wire, a base layer insulation (2) made of a cross-linked terephthalic acid polyester is first applied and cured there in the usual way. This first layer of insulation is through a second, preferably thinner, coating (3) made of polyhydantoin.

The invention further encompasses the manufacture of such insulated electrical conductors. Here, in in a manner known per se, optionally in several layers, of the base coat (2) made of the terephthalic acid polyester resin applied and cured. Then the further thinner coating (3) made of polyhydantoin is painted on in the same way by the conductors provided with the base coat (2) once or several times through a heated polyhydantoin lacquer bath is drawn and the resin layer is baked on it.

The processing conditions, in particular the baking temperature and the take-off speed can be chosen to be the same for the two finishes for the production of these layers, see above that preferably can be driven in just one operation. It must be ensured that that the wire successively passes through the two respective paint baths separately. Of course you can the wire pass through the respective enamel bath several times.

Merely for the sake of completeness, it should be pointed out here briefly that the known polyhydantoins, which are used in the context of the invention, according to the teaching of the earlier patent mentioned Implementation of aromatic di- or triamines substituted with acetic acid or acetic acid derivatives the following structural formula

AR -

R,
NH - C - COR ₂

π =

R ₂
R.

2 to 3

OH, O-alkyl, O-aryl, amino resp.

subst. Amino groups

H, alkyl radical

can be obtained with at least two NCO groups in the molecule containing isocyanate compounds at temperatures between 100 and 250 ⁰ C.

Described in the following examples

Example 1 the production of a terephthalic acid polyester lacquer which can be used for the base layer,

Example 2 the production of a polyhydantoin varnish that can be used for the top layer,

Example 3 the production of an electrical conductor with a base layer according to Example 1 and a Top layer according to example 2.

example 1

a) 193.2 parts by weight of glycerol, 193.2 parts by weight of glycol, 105 parts by weight of cresol DAB 6 and 815 parts by weight of dimethyl terephthalate and 3.57 parts by weight of cemaphthenate in 6% solution in aromatics, ζ. B. toluene, xylene or solvent naphtha, are filled in the order given in a three-necked flask equipped with a stirrer, a thermometer and a distillation head. The mixture is heated rapidly to 140 ⁰ C, and then increasing the temperature by 5 ° C per hour until it reaches 205 ⁰ C. From 190 ^° C. the reaction is carried out with the introduction of carbonic acid. During the reaction process, a distillate of about 300 parts by weight of liquid is obtained, which consists mainly of methanol. It is then cooled to 180.degree.

b) 43.6 g parts by weight of terephthalic acid are then added, the mixture is heated to 215 ° C. and is kept at this temperature for 1 hour. Then it will come back on. Cooled 180 ⁰ C and added to 43.6 parts by weight of terephthalic acid again heated to 215 ° C and held for _^3/4 hour at this temperature. During the esterification process, around 25 parts by weight of distillate are obtained, which mainly consists of water.

c then) is cooled again from, adds C 10.5 parts by weight Zinknaphthenatlösung with a content of 8% zinc added at 200 ⁰ and cooled further to 140 ⁰ C. At 30 mm pressure, then distilled in the course of 3 hours under heating of 140 to 175 ° C, with about 80 to 90 parts by weight of distillate are obtained, which consists mainly of cresol.

d) After the vacuum distillation has ended, the temperature is increased to 225 ° C. over the course of about 3 hours while introducing carbonic acid. The reaction mixture is kept at this temperature until a sample - diluted with cresol to a solids content of 40% - a DIN-. Viscosity of 20 minutes at 20 ⁰ C and 4 mm nozzle has reached. Then rapidly added with stirring 420 parts by weight of cresol added, the solution is cooled to 140 ⁰ C. and mixed them with a mixture of 15.75 parts by weight of butyl titanate, 70 parts by weight of cresol DAB 6 and 19 parts by weight of solvent naphtha and with a resolution of 2.6 parts by weight p-Toluenesulfonic acid in 35 parts by weight of dioxyacetone alcohol and 17 parts by weight of solvent naphtha. The reaction is then allowed to take place for 10 minutes at 140 ^° C. and a further 420 parts by weight of cresol are added.

The approximately 48% solution obtained in this way is diluted to 35% with cresol, solvent naphtha or xylene.

Example 2

a) 198 parts by weight of 4,4'-diaminodiphenylmethane, 200 parts by weight of calcium carbonate and 1500 parts by weight of water are heated to 8O ⁰ C and added dropwise initially 244 parts by weight of ethyl chloroacetate at this temperature. Is maintained for 2 hours at 8O ⁰ C and then added dropwise ethyl chloroformate to have 217 parts by weight. After the evolution of carbon dioxide has ceased, the organic phase is separated from the aqueous calcium chloride solution, washed several times with hot water and taken up in approximately equal parts by weight of ethanol. Small amounts of 4,4'-bis (N-carbäthoxymethylamino) diphenylmethane precipitate here. After concentrating the ethanolic solution, the desired 4,4 '- bis - (N - carbäthoxymethyl - N - carbäthoxyaminj-diphenylmethane remains as a viscous residue, the IR spectrum of which clearly agrees with the assumed structure.

b) 51.4 parts by weight of glycine derivative obtained according to a) and 19.9 parts by weight of 4,4'-diaminodiphenylmethane were heated in a stirred flask under nitrogen first at 200 ⁰ C. Even small amounts of ethanol distill off during this process. ^{The temperature is now slowly increased to 250 °} C. in the course of 10 hours and left at this temperature until the mass can hardly be stirred. A 12% solution is produced by adding cresol / solvent naphtha in a ratio of 1: 9.

Example 3

The lacquers described in Examples 1 and 2 were successively lacquered and baked on copper wire of 1 mm 0 using a conventional process using a wire enamelling oven 2.50 m long and at an oven temperature of 480 ^{° C.}

Here, the polyester lacquer according to Example 1 alone and coated with polyhydantoin gave the following Values:

T iirV Paint according to example 1 according to example 1 covered with
Paint from example 2 Paint application 70 µ 71 μ (55/16) Surface hardness 2 to 3 H. 3 H Abrasion Load of 560 cP 68 double strokes 110 double strokes Curl shock 1 h / 200 ° C .... 7x0 OK 2x0 OK Softening temperature (according to DIN 46453) 310 ° C 340 "C

1 sheet of drawings

Claims (6)

Patent claims: 1. Electrical conductor with a base layer insulation made of a cross-linked terephthalic acid polyester, characterized by an overlying cover layer insulation made of one Polyhydantoin. 2. Electrical conductor according to claim 1, characterized in that the cover layer insulation a polyhydantoin, which has aromatic rings between the hydantoin rings. 3. Electrical conductor according to claim 2, characterized in that the top layer insulation is a has a thinner layer than the base layer insulation. 4. Process for the production of electrical conductors according to one or more of the preceding Claims, characterized in that an additional thin coating is applied to an electrical conductor coated with the polyester is applied from a polyhydantoin in a known manner and burned in there. 5. The method according to claim 4, characterized in that an additional coating of one Polyhydantoin, which has aromatic rings between the hydantoin rings, applied and burned in will. 6. The method according to any one of claims 4 and 5, characterized in that the processing conditions for applying the base layer insulation and the cover layer insulation are chosen to be the same, in particular in only one Operation is worked in such a way that the wire successively passes through two separate paint baths.