DE2712495A1 - PROCESS FOR THE MANUFACTURE OF HEAT-RESISTANT INSULATING COVERINGS ON ELECTRIC LADDERS - Google Patents

Description

Applicant: Dr Kurt Herberts & Co. Limited company Liability vorm. Otto Louis Herberts

D-56 Wuppertal 2, Christbusch 25

Process for the production of highly heat-resistant insulating coatings on electrical conductors.

The present invention relates to a process for the production of highly heat-resistant insulating coatings on electrical conductors by coating the conductors with catalysts and optionally containing solutions of thermosetting amide- and / or imide-modified ester resins from polyhydric alcohols, polybasic carboxylic acids with carboxyl groups bonded to aromatic rings, optionally in a mixture with aliphatic carboxylic acids, and optionally their anhydrides and / or esters, and compounds containing amino groups, and heating the coated conductors to object temperatures above 20O ⁰ C.

It is known to produce polyester resins which are suitable for painting electrical conductors if they are dissolved in organic solvents of the phenol, cresol and / or xylenol type. The electrical conductors are thus isolated in that it is coated with a solution of the above polyester resins and then at oven temperature temperatures of about 35O ⁰ C or heated above, wherein the

Cure polyester resins. The known paint solutions contain Usually the usual lacquer additives and / or curing catalysts. Lacquer solutions of polyester resins with five-membered imide rings are preferred Contained condensed (GB-PS 939 377, 1 082 181, 1 067 541, 1 067 542 and 1 127 214, BE-PS 663 429, FR-PS 1 391 834, DDR-PS 30 838, DT-OS 1 494- 4-54, 1 494 413, 1 937 310, 1 937 311, 1 966 084, 2 101 990 and 2 137 884).

The solvents of the phenol, cresol and / or type Xylenols contain phenolic hydroxyl groups. These solvents are extremely undesirable for physiological reasons, and in some countries their use is only permitted under certain precautionary measures. There is therefore a there is a strong need to avoid the use of these solvents, although they are cheap and readily available and dissolve the ester resins in question well. It is also known to use other solvents, e.g. N-methylpyrrolidone, Dimethylacetamide, dimethylformamide, dimethyl sulfoxide, N-methylcaprolactam and / or dimethyl sulfone (GB-PS 1 082 181). However, all of these solvents are also either physiologically questionable or difficult to access and thus expensive and / or they dissolve the ester resins poorly, so that only low-percentage paint solutions are obtained can. The use of these solvents therefore has none gained practical importance.

It is also known to provide insulating coatings on electrical conductors by coating the conductors with aqueous Preparing solutions, these aqueous solutions containing carboxyl groups neutralized with bases, in particular amines Ester resins contain (DT-OS 2 509 048, 2 439 385 and 2,439,386). The disadvantage of this method or this

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aqueous solutions consists in the fact that a lot of energy is required to evaporate the water during the stoving process, the furnace must be supplied with a lot of external energy, the high The surface tension of the water causes technical difficulties in painting and the acid number of the carboxyl groups Ester resins must be very high, e.g. above about 50, in order to achieve sufficient solubility in water after neutralization achieve. This in turn has the consequence that the proportion of amines used for neutralization must be high, which Brings environmental problems with it. The storage stability is unsatisfactory because of hydrolytic degradation processes.

The present invention is based on the object of a method for producing insulating coatings to be found on electrical conductors, in which solutions of amide- and / or imide-modified ester resins in organic Solvents are used, which, however, are physiologically harmless or considerably less problematic are as the above-mentioned solvents used so far.

It has now been found that, surprisingly, this task can be solved by using solvents which are extraordinary as such are poor solvents for the amide- and / or imide-modified ester resins commonly used, but that Paintable solutions with a high stoving residue can be obtained if the ester resins have a certain ratio from hydroxyl groups to carboxyl groups and have a certain acid number, and the carboxyl groups in certain Way are implemented with amines.

The present invention accordingly provides a process for the production of highly heat-resistant insulating

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Generating coatings on electrical conductors by coating the conductors with catalysts and optionally containing leveling agent solutions of thermosetting amide- and / or imide-modified ester resins from polyhydric alcohols, polybasic carboxylic acids with carboxyl groups bonded to aromatic rings, optionally mixed with aliphatic carboxylic acids and optionally their anhydrides and / or esters, and compounds containing amino groups, and heating the coated conductor to object ^{temperatures above 200 0} C, which is characterized according to the invention that the ester resins have an acid number of Ί0 to 50 and the equivalent ratio of the hydroxyl groups to the carboxyl groups in the starting products for the preparation of the ester resins is between 1.6 and 2.5, the solution contains aliphatic amines in an amount that for each free carboxyl group of the ester resin there are 0.5 to 1.5 amino groups, and the solvents in an amount of at least about 70 wt .-% of mono- and / or dialkyl ethers, the alkyl parts each containing one to six carbon atoms, consist of mono- and / or di-alkanediols with two to four carbon atoms per alkali.

The invention also relates to a stoving enamel containing organic solvents and thermosetting amide and / or imide-modified ester resins from polyhydric alcohols, polybasic carboxylic acids with carboxyl groups attached to aromatic rings, optionally in a mixture with aliphatic carboxylic acids and optionally their anhydrides and / or esters, and compounds containing amino groups, and heating the coated conductors to object temperatures above 200 ° C, as well as catalysts and optionally customary paint additives and / or leveling agents, the is characterized in that the ester resins have an acid number of 10 to 50 and where the equivalent ratio the hydroxyl groups to the carboxyl groups in the starting materials for the production of ester resins between 1.6 and

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2.5, the solution is aliphatic amines in an amount contains that for each free carboxyl group of the ester resin there are 0.5 to 1.5 amino groups, and the solvents in an amount of at least about 70 wt .-% of mono- and / or Dialkyl ethers, the alkyl parts each from one to six Containing carbon atoms of mono- and / or dialkanediols with two to four carbon atoms per alkali. Free carboxyl groups in the above sense are those according to Termination of the condensation reaction is still unesterified.

The alkyl groups of the mono- or dialkyl ether groups mentioned can be straight-chain or branched and preferably contain one to four carbon atoms. The alk fractions of the dialkanediols each preferably contain two carbon atoms. It So the solvents used according to the invention are preferably mono- and / or dialkyl ethers of Mono- and / or diethylene glycol. Examples of such solvents used in accordance with the invention are methyl glycol (Monoethylene glycol monomethyl ether), ethyl glycol (monoethylene glycol monoethyl ether), Propyl glycol (monoethylene glycol monopropyl ether), butyl glycol (monoethylene glycol monobutyl ether), Methyl diglycol (diethylene glycol monomethyl ether), ethyl diglycol (diethylene glycol monoethyl ether), propyl diglycol (Diethylene glycol monopropyl ether), butyl diglycol (diethylene glycol monobutyl ether), Diethylene glycol dimethyl ether, butyl glycol tert-butyl ether, Methyl diglycol tert-butyl cups, Monopropylene glycol-1,3-monoethyl ether, monopropylene glycol-1,3-monobutyl ether.

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The mono- and / or dialkyl ethers of mono- and / or dialkanediols used as solvents according to the invention are per se extremely poor solvents for the ester resins used · It is surprising that one finds solutions with high storage stability, especially with regard to cloudiness, and high stoving residue when ester resins are used the ratio of the hydroxyl groups to the carboxyl groups given above and the acid number given above are used and the above-defined amounts of certain amines are added to these solutions. According to the invention The solutions used are practically harmless from a physiological point of view, at any rate considerably less hazardous than the solvents previously used in this technical field. They are easily available and therefore cheap.

As already stated above, the solvents of the solutions according to the invention consist of at least about 70% by weight, based on the total amount of solvents, from the solvents defined above. This amount is preferably around about 80% by weight, particularly preferably about 90% by weight. It it is of course possible according to the invention to use only the solvents defined above as solvents. If other solvents are used in addition, it should correspond to the task at hand the present invention are such solvents,

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which are also physiologically harmless. Examples are aliphatic alcohols with 1 to 8 carbon atoms such as ethanol, butanol, isopropanol, glycol, diacetone alcohol, esters known as paint solvents such as ethyl acetate, Butyl acetate, ethyl glycol acetate, ketones known as paint solvents such as butanone, cyclohexanone. Such are appropriate Additional solvents, which are also known as co-solvents, are used to improve the technical properties of the paint of the solutions used do not adversely affect and possibly have a beneficial effect on the paint technology Have properties such as the course. The lacquer solutions used according to the invention are resistant to contamination insensitive to small amounts of water.

The acid number of the ester resins used according to the invention is preferably at least about 5 and at most preferably about 25.

As already stated above, the equivalent ratio should be used in the preparation of the ester resins used according to the invention the hydroxyl groups to the carboxyl groups in the starting materials are between 1.6 and 2.5. Preferred this equivalent ratio is at least about 1.8. The upper limit is preferably 2.3

As carboxyl groups that are used to calculate the equivalent ratio the hydroxyl groups are used to the carboxyl groups according to the definition above understood only those (possibly esterified, i.e. potential) carboxyl groups of the carboxylic acids which are still used for an esterification reaction with the alcohols or an amide formation with amines used for this purpose are available. The manufacture of the amide-imide-modified ester resins

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thus takes place by esterification of the polybasic carboxylic acids mentioned with polyhydric alcohols. It is there too possible, the production of preformed heterocyclic carboxylic acids, e.g. diimide dicarboxylic acids and the esterification These diimide dicarboxylic acids carry out with the alcohols in one stage in a vessel, since the amino groups with the ortho carboxyl groups or their anhydride groups E.g. trimellitic acid or its anhydride preferentially react with the formation of five-membered imide rings and therefore for the esterification with the alcohols only those carboxyl groups of the originally used carboxylic acid or whose anhydride are left over, which do not deal with amino groups react with the formation of five-membered imide rings.

Examples of carboxylic acids used in the manufacture of the ester resins can be used are terephthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, their Esters or anhydrides.

Polybasic carboxylic acids, alcohols or amino groups are also used as polyvalent compounds for polyester formation Compounds containing understood, the five-membered Imide rings included. Examples of this are polybasic carboxylic acids, which are produced by reacting, for example, trimellitic anhydride be obtained with diamines with the formation of so-called diimide dicarboxylic acids. The polyvalent carboxylic acids, which are esterified with the alcohols can therefore represent relatively complex molecules.

As amines, those with the carboxyl groups available for the esterification reaction with the formation of acid amide bonds can be implemented, as according to the prior art, aliphatic or aromatic compounds

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used. Examples are ethanolamine, ethylenediamine, Aminomethylolpropane, p-aminobenzyl alcohol, 4,4'-diaminodiphenylmethane, ether and / or sulfone.

The esterimide resins can preferably be up to 5 wt .-% Contains nitrogen bound in five-membered imide rings.

According to the invention, such compounds containing carboxylic acids, alcohols and / or amino groups are preferred Production of the ester resins used, which are at least partially polyfunctional, i.e. more than bifunctional, in order to obtain cross-linked products when stoving onto the wire. The degree of crosslinking corresponds to the usual amide- and / or imide-modified ones used in this technical field Ester resins · As in the prior art, it is preferred that the aforementioned polyfunctional Compounds containing carboxylic acids, alcohols and / or amino groups are preferably 3 or 4, particularly preferred Contains 3 carboxyl, hydroxyl and / or amino groups in the molecule.

The reaction between carboxylic acids, alcohols and compounds containing amino groups to produce the Ester resins used according to the invention are terminated when the desired acid number has been obtained. However, it is also possible to produce ester resins with an initially lower acid number, and by reacting these ester resins with polybasic carboxylic acids to produce resins with the desired acid number.

For the production of ester resins from carboxylic acids and alcohols and compounds optionally containing amino groups, customary esterification catalysts can be used.

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Examples are zinc acetate, antimony trioxide, metal amine complex catalysts, like the one in DT-AS 1 519 372 Complex compounds described, black lead, tin (II) oxalate, titanates, manganese (II) acetate, cerium (III) acetate and other.

After the esterification reaction has ended, the ester resins are brought to a temperature below the boiling point of the amines cooled, which are added to the solutions according to the present invention. Then these amines are slowly added. Primary, secondary and tertiary monoamines can be used as such aliphatic amines. Are preferred Alkanolamines, which may contain N-alkyl groups can, the alkanol or alkyl groups preferably 1 to 6, particularly preferably 1 to 4 carbon atoms in the Chain included. Examples are monoethanolamine, diethanolamine, Triethanolamine, NN-dimethylethanolamine, NN-diethylethanolamine, Propanolamine, diisopropanolamine.

The solution preferably contains the aliphatic amines in such an amount that there is one carboxyl group for each of the ester resin at least about 0.8 amino groups are omitted. The upper limit of the amines added is preferred such that there is about 1 amino group for 1 carboxyl group.

These amines also have an accelerating effect on the transesterification that takes place on the wire during the stoving process. this applies especially for those amines that only escape from the paint film after the solvents have evaporated.

Then it is used with the according to the invention Solvents diluted to the desired concentration. The solutions are then the usual, for the stoving

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Catalysts, leveling agents and, where appropriate, used other paint additives added. Under paint additives are in the sense of the present Invention also understood optionally blocked isocyanates. It is known in the field of manufacturing insulating Coatings on electrical conductors to use ester resins in combination with, if necessary, masked isocyanates. This modification is encompassed by the present invention. For reasons of physiological harmlessness those blocked isocyanates whose blocking agents are physiologically harmless or of little concern are preferred.

The cross-linking on the wire takes place as in the use of solvent-based paints according to the prior art at object temperatures of at least 200 ° C, ie at oven temperatures of about 300 ⁰ C, usually about 400 ⁰ C. The upper temperature limit is essentially determined by that of course a decomposition of the uniform coating on the wire can be avoided. For stoving, as is customary in the prior art, so-called stoving catalysts can be added to the solutions. Examples of these are monomeric or polymeric aryl or alkyl titanates, ortho-titanic acid ester chelate compounds and other common transesterification catalysts. These can be used by the person skilled in the art in a suitable selection and concentration (for example 0.001 to 8% by weight based on the solution). Only those stoving catalysts can be used which are homogeneously miscible in the solution used. Additives such as silicone-containing leveling agents (for example 0.001 to 5.0% by weight) are often useful, and it corresponds to the state of the art if they are added to improve the painting behavior of the stoving enamel.

As in the prior art when using solution

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medium-containing lacquer solutions, several thin layers are produced one after the other on the wire and each is baked in to finally to obtain a multi-layer coating with the best insulating and mechanical properties. The at Each individual stoving process achieved paint coatings, for example, depending on the nozzle diameter, 5 to 15 μ, maximum about 20 u with 1mm wire diameter.

The method according to the invention can be used with particular advantage on those ester resins which have a high content of tris - (2-hydroxyethyl) - isocyanurate, for example this compound is used in such an amount that it is about 30 to 50 % of that with the Starting compounds provides a total of hydroxyl groups used. The process according to the invention can also advantageously be used on those ester resins which contain a relatively high proportion of five-membered imide rings, for example in an amount such that more than 1% by weight of nitrogen in the ester resins in the form of five-membered imide rings and optionally also amide bonds are present.

example 1

248 g (4.0 mol) of ethylene glycol 392 g (1.5 mol) of tris (2-hydroxyethyl) isocyanurate 388 g (2.0 moles) of dimethyl terephthalate

are converted to 200 ⁰ C together with 1.6 g of zinc acetate in a three-necked flask equipped with stirrer, thermometer and rectification column at a temperature up. 128 g of methanol are distilled off. After cooling to approx. 150 ⁰ C are

192 g (1.0 mole) of trimellitic anhydride 99 6 (0.5 mole) of 4,4'-diaminodiphenylmethane

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admitted. By further heating to 21O ⁰ C 35 g of water are distilled off. The melt, which has been cooled to 150 ^{° C., is added again}

192 g (1.0 mole) trimellitic anhydride 99 g (0.5 mole) 4,4'-diaminodiphenylmethane

given. At 210 ° C., water is distilled off until the acid number is 19. Now, N-dimethylethanolamine is cooled to 130 ⁰ C and over 15 min. Portionwise with inagesamt 43 g N, added. (There is about 1 amino group for every free carboxyl group of the ester resin.)

500 g of the above material are dissolved in 150 g of diglycol dimethyl ether, 150 g of ethyl diglycol, 120 g of ethyl glycol, 50 g of butyl diglycol, and J> 0 g of titanium acetylacetonate (catalyst) is added. The result is a clear varnish with a stoving (1 h 180 ⁰ C) of 49% and an outlet consistency Jp = 145 lake.

In a parallel experiment without adding Ν, Ν-dimethylethanolamine a cloudy paint solution is obtained that cannot be processed

Example 2

496 grams (8.0 moles) of ethylene glycol, 114 grams (1.5 moles) of propylene glycol 388 g (2.0 moles) of dimethyl terephthalate

are reacted as described in Example 1 together with 1.4 g of zinc acetate. 128 g of methanol are distilled off,

After cooling to 150 ⁰ C are

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336 g (1.75 moles) of trimellitic anhydride 99 S (0.5 moles) of 4,4'-diaminodiphenylmethane

admitted. It is heated until 60 g of water are distilled off are. After cooling to 150 ° C., the melt is again added

336 grams (1.75 moles) of trimellitic anhydride, 99 grams (0.5 moles) of 4,4 ^I -diaminodiphenylmethane

given. At 220 ^° C., water is distilled off until the acid number is 25. It is then ^{cooled to 130 °} C. and a total of 65 g of N, N-dimethylethanolamine are added in portions over the course of 15 minutes. (There is about 1 amino group for every free carboxyl group.)

500 g of this material are dissolved in 150 g of diglycol dimethyl ether, 250 g of ethyl diglycol and 120 g of butyl diglycol, and 30 g of polymeric butyl titanate are added. The clear lacquer solution has a stoving residue (1 h 180 ^° C.) of 45% and

20 an outlet consistency of AK ^ ^V ■ 105 see.

In a parallel experiment without the addition of Ν, Ν-dimethylethanolamine a cloudy paint solution is obtained that cannot be processed.

Example 3

394 g (6.35 moles) ethylene glycol 4% g (1.9 mol) of tris (2-hyaroxyethyl) isocyanurate, 776 g (4.0 mol) of dimethyl terephthalate

are together with 5.0 g of monomeric butyl titanate as in

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Example 1 implemented. 250 g of methanol are distilled off. After cooling to 150 ^° C., the temperature is reduced

192 grams (1.0 mole) of trimellitic anhydride 178 grams (0.9 moles) of 4,4'-diaminodiphenyl methane

added and it is heated until 35 g of water have passed over. After cooling to 150 ^° C., the melt becomes again

192 g (1.0 mole) trimellitic anhydride 178 g (0.9 mole) ^, V-diaminodiphenylmethane

admitted. At 210 ^° C., water is distilled off until the acid number is 18. It is then cooled to 130 ° C and 73 g of diethanolamine are added to the melt (there is about 1 amino group for 1 free carboxyl group.)

500 g of this material are dissolved in 300 g of ethyl diglycol, 100 g of ethyl glycol and 120 g of butyl diglycol, and 20 g of titanium acetylacetonate are added. The clear lacquer solution has a stoving residue (1 h 180 ^° C.) of 47.5 % at a

20 Consistency of leakage from AK. “I30 see.

In a parallel experiment without diethanolamine, a cloudy paint solution is obtained that cannot be processed .

Example A-

15.95 kg (209.9 moles) propylene glycol 1.2 16.10 kg (61.7 moles) of tris (2-hydroxyethyl) isocyanurate 19.88 kg (119.8 moles) of isophthalic acid

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are reacted together with 70 g of zinc acetate in a 120 1 pilot plant reactor equipped with anchor stirrer, induction heating (temperature control) and rectification column, at a temperature up to 200 ⁰ C. 2.1 kg of water are distilled off. After cooling to 150 ⁰ C are

12.07 kg (62.9 moles) of trimellitic anhydride, 5.93 kg (29.9 moles) of 4,4'-diaminodiphenylmethane

added. By further heating to 200 ^° C., water is distilled off until the acid number is 25. It is then ^{cooled to 130 °} C. and 2.30 kg of N, N-dimethylethanolamine are slowly added. (There are about 0.9 amino groups for 1 free carboxyl group.)

8.00 kg of the above material are dissolved in 7.00 kg of ethyl diglycol, 1.00 kg of methyl diglycol and 0.50 kg of butyl diglycol, and 0.27 kg of titanium acetylacetate are added. A clear varnish with a stoving residue (1 h 180 ^° C.) of 46 % and an outflow consistency of AK ^ = 105 seconds is obtained.

One removed before the addition of Ν, Ν-dimethylethanolamine The sample is not clearly soluble in the solvents used

Examples 5 to 9

In the same way as described in Example 1, the ester resins of Examples 5 to 9 are prepared. The paints are produced according to the recipe given in Example 1.

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Example 5

238 grams (3.84 moles) of ethylene glycol

515 g (1.97 mol) of tris (2-hydroxyethyl) isocyanurate

55 grams (0.33 moles) of isophthalic acid

388 g (2.00 moles) of dimethyl terephthalate

400 g (2.01 moles) of trimellitic anhydride

198 grams (1.00 moles) of 4,4'-diaminodiphenyl methane

7 g zinc acetate

The acid number of the ester resin is 18. 40 g of Ιί, Ν-dimethylethanolamine are added so that 1 free Carboxyl group 0.88 amino groups are omitted.

Example 6

326 grams (5.26 moles) of ethylene glycol

922 ε (3.53 mol) tris (2-hydroxyethyl) isocyanurate

607 g (3.13 moles) of dimethyl terephthalate

787 grams (4.10 moles) of trimellitic anhydride

396 grams (2.00 moles) of 4,4'-diaminodiphenyl methane 18 g zinc acetate

The acid number of the ester resin is 23 · It is 95 g N, N-dimethylethanolamine added, so that on 1 free Carboxyl group 0.96 amino groups are omitted.

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Example 7

286 grams (4.61 moles) of ethylene glycol

731 g (2.80 mol) of tris (2-hydroxyethyl) isocyanurate

166 g (1.00 mole) isophthalic acid

24-3 g (1.25 moles) of dimethyl terephthalate

595 g (3t10 moles) of trimellitic anhydride

297 S (1.50 moles) 4,4'-diaminodiphenyl methane

7 g zinc acetate

4 g of antimony oxide

The acid number of the ester resins is 20. 70 g of Ν, Ν-dimethylethanolamine are added so that 1 free Carboxyl group 1.05 amino groups are omitted.

Example 8

620 grams (10.00 moles) of ethylene glycol

104 g (1.00 mole) neopentyl glycol

1566 g (6.00 mol) of tris (2-hydroxyethyl) isocyanurate

415 S (2.50 moles) isophthalic acid

970 g (5.00 moles) of dimethyl terephthalate

960 grams (5.00 moles) of trimellitic anhydride

495 grams (2.50 moles) of 4,4'-diaminodiphenyl methane 20 g zinc acetate

The acid number of the ester resins is. 19 · There are 151 β N, N-Diä "Chy] ethanolamine added so that on 1 free Carboxyl group 0.84 amino groups are omitted.

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Example 9

495 6 (7.98 moles) ethylene glycol

1466 g (5.62 mol) of tris (2-hydroxyethyl) isocyanurate

427 grams (2.57 moles) of isophthalic acid

582 g (3 x 00 moles) of dimethyl terephthalate

1152 grams (6.00 moles) of trimellitic acid aihydride

634 grams (3-20 moles) of 4,4'-diaminodiphenyl methane 25 g zinc acetate

5 g cerium III acetate

The acid number of the ester resin "is 25. It is 160 g N, N-dimethylethanolamine was added, so that there were 0.92 amino groups for 1 free carboxyl group.

The lacquer solutions are in a horizontal wire lacquering oven about 3 m long and a temperature of 550 C. applied by means of nozzles in 8 layers on a copper wire of 0.5 now 0 and cured. The painting speed in Examples 1 to 9 is 38 to 40 m / min.

The test procedures were carried out as follows:

1. Winding strength with pre-stretching: A wire section is Pre-stretched to the specified percentage and wrapped around its own mandrel, the diameter of which is equal to the diameter of the tested wire. Then the insulated conductor is examined for cracks in the lacquer layer. If no cracks are found, the tested wire is OK (OK). The pre-elongation at which the wire is still is specified is ok. The test conditions are described in detail in DIN 46453, Section 5.1.2 - Sheet 1.

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2. Heat shock test 30 min at 160 ° C.: The wire is wound into a curl over a mandrel with the diameter of the wire, then ^{stored in the oven at 160 °} C. for 30 min and assessed as under item 1. The test procedure is described in detail in DIN 46453 sheet 1, section 5-2.1.

The experiment ^{is carried out at 180 °} C. or 200 ^° C. in a similar manner, but the oven is kept at 180 ^° C. or 200 ^° C.

3. Softening point in ⁰ C according to DIN 46453 sheet 1, section 5.22: The softening point is the temperature at which two wires under tension and increasing temperature load, which overlap in a cross shape and are loaded with standard weights, get short-circuited.

4. Eiribrennrückstand: 1 g coating solution is baked in a cover with a 50 mm 0 for 1 hour at 180 ⁰ C. The remaining residue is given in percent.

? 0

5. Outflow consistency AKf: The outflow consistency is the

understood according to DIN 53211 (April 1974) at 20 ⁰ C determined time in seconds which the paint solution needs to run out of the DIN cup 4.

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Tabel ' 1 5 "Insulated wires t 3 ; r gave the following values: 5 6th 7th 8th ; 9 clear 2 clear 4th clear clear clear of course clear ! The examination of: OK clear OK clear OK OK OK OK OK Paint according to the example 30% OK 20% OK 60
20% 70
25% 65
25-30% 65
25% 60
20-25% 03 CD Appearance of
Paint solutions OK
OK
OK 60
20% OK
OK
not ok 25% OK
OK
not ok OK
OK
OK OK
OK
OK OK
OK
not ok OK
OK
OK φ ***
3 -Γ »
3 ^
s °
-: cn
^ CO Lacquer surface 373 ⁰ C OK
OK
not ok 342 ⁰ C OK
OK
not ok 36O ⁰ C 373 ° C 378 ⁰ C 368 ° C 372 ° < Lacquer finish in u in
DIN 46 453
Winding strength
to get through
knife of wire
after pre-stretching 305 ⁰ G 325 ° C Thermal shock test
30 min 160 C
30 min 180 ^° C
30 min at 200 ^° C Softening point
DIN 46 453 sheet 1
Section 5.22 OK = OK
not ok = not ok

NJ -F-

Claims (10)

Claims 1. Process for the production of highly heat-resistant insulating Coatings on electrical conductors by coating the conductors with catalysts and optionally Leveling agent-containing solutions of thermosetting amide- and / or imide-modified ester resins from polyhydric alcohols, polybasic carboxylic acids with carboxyl groups attached to aromatic rings, optionally in a mixture with aliphatic carboxylic acids and optionally their anhydrides and / or esters, and amino group-containing compounds, and heating the coated conductors to object temperatures 200 C, characterized in that the ester resins have an acid number of 10 to 50 and wherein the equivalent ratio of the hydroxyl groups to the carboxyl groups in the starting materials for Production of ester resins is between 1.6 and 2.5, the solution contains aliphatic amines in an amount that there are 0.5 to 1.5 amino groups for each free carboxyl group of the ester resin, and the solvents in an amount of at least about 70 wt .-% of mono- and / or dialkyl ethers, the alkyl parts each being a contain up to six carbon atoms, from mono- and / or Dialkanediols with two to four carbon atoms per alkali exist. 2. The method according to claim 1, characterized in that the equivalent ratio of the hydroxyl groups to the Carboxyl groups is at least about 1.8. 709840/0853 ORIGINAL INSPECTED 3. The method according to claims 1 or 2, characterized in that the equivalent ratio of the hydroxyl groups to the Carboxyl groups is at most about 2.3. 4-. Method according to one of Claims 1 to 3 »characterized in that that the ester resins have an acid number of at least about 15. 5. The method according to any one of claims 1 to 4, characterized in that that the ester resins have an acid number of at most about 25. 6. The method according to any one of claims 1 to 5, characterized in that that the solution contains aliphatic amines in an amount that for each carboxyl group of the ester resin at least about 0.8 amino groups are omitted. 7. The method according to any one of claims 1 to 6, characterized in that that the solution contains aliphatic amines in an amount that for each carboxyl group of the ester resin at most about one amino group is omitted. 8. The method according to any one of claims 1 to 7 »characterized in that that the solution contains aliphatic monoamines. 9. Method according to one of Claims 1 to 8, characterized in that that the solution is alkanolamines, the N-alkyl groups may contain, contains. 10. Stoving enamel containing organic solvents and thermosetting amide and / or imide modified ester resins from polyhydric alcohols, polybasic carboxylic acids with carboxyl groups attached to aromatic rings, 709840/0853 2712A95 optionally in a mixture with aliphatic carboxylic acids and optionally their anhydrides and / or esters, and amino group-containing compounds and heating the coated conductors to object temperatures above 200 C, as well as catalysts and, if necessary, customary paint additives and / or leveling agents, characterized in that the ester resins have an acid number of 10 to 50 and where the equivalent ratio of the hydroxyl groups to the carboxyl groups in the starting materials for production of the ester resins is between 1.6 and 2.5, the solution contains aliphatic amines in an amount that for each free carboxyl group of the ester resin there are 0.5 to 1.5 amino groups, and the solvents in an amount of at least about 70 wt .-% of mono- and / or dialkyl ethers, the alkyl moieties each being a contain up to six carbon atoms, of mono- and / or dialkanediols with two to four carbon atoms per Alcohol content exist. 709840/0853