WO2009090261A1 - High-temperature-resistant electrically insulating varnish - Google Patents

Abstract

The present invention relates to wire varnishes which can be tin-plated, comprising at least one blocked polyisocyanate adduct, at least one polyester hydroxy polyol containing imide and/or amide groups, organic solvents and optionally further auxiliaries and additives, with the resulting imide compounds having a theoretical imide content of from 8 to 40% by weight, the production of these wire varnishes and their use.

Description

 High temperature resistant electrical insulating varnish

The present application claims the priority of DE 10 2008 004 926.3. The priority document is incorporated by reference in its entirety into the present disclosure (= incorporated by reference in its entirety).

All documents cited in the present application are incorporated by reference in their entirety into the present disclosure (= incorporated by reference in their entirety).

The invention relates to a tin-plating electrical insulating lacquer, in particular wire enamel, for producing high-temperature, tin-plating coatings on wires based on polyurethanes which are modified by higher-functional isocyanates, imides and / or amide-imides.

Polyurethanes as Elektroisolierbeschichtungsmittel based on hydroxyl-containing polyesters and blocked isocyanates are known in large numbers and described for example in DE 1 957 157, DE 195 07 942 and DE 100 51 392. Such electrical insulating coating are characterized in their use as wire coating especially by their good insulating properties. Furthermore, they have the advantage that they are tin-plated. Tinnable insulated wires, when immersed in a solder bath heated to elevated temperatures, destroy the bare metal of the conductor while destroying the insulating layer, which is thus directly accessible for electrically conductive connections. It is important that the time to remove the insulating lacquer layer is as short as possible. The requirement for great thermolability under the soldering conditions is opposed by a high thermal stability, which is demanded of coated wires for use in electrical components. While the tin-pliability is due to the presence of urethane groups in the paint film, the heat resistance is significantly influenced by the choice of polyester.

From DE 24 45 302 corresponding compositions are known as impregnating varnishes. From DE 27 18 898 and EP 0 055 085 coating compositions containing polyesterimides are known which contain blocked isocyanates. However, the coating compositions described therein are not tin-plating.

The combinations of one or more hydroxyl-containing polyesters used for wire coatings based on polyurethane generally having an OH number of 200 to 900 mg KOH / g, preferably 250 to 750 mg KOH / g and one or more blocked isocyanate adducts are already known and eg in DE 28 40 352 and DE 25 45 912 described.

For the preparation of the hydroxyl-containing polyesters, the same structural components (polyol and polycarboxylic acid) and the same reaction conditions as in the preparation of the polyester or polyester imide resins can be used. That is, the preparation is carried out in a known manner by esterification of polybasic carboxylic acids with polyhydric alcohols in the presence of suitable catalysts. Instead of the free acids and their ester-forming derivatives can be used.

In DE 28 40 352 polyesterimide polyols are described which contain as imide-forming components trimellitic anhydride (TMA) and 4,4-diaminodiphenylmethane in a ratio of 2: 1, so that a linear dimidodicarboxylic arises. As further acids or their derivatives are dimethyl terephthalate and

Isophthalic acid used as alcohols include glycerol, ethylene glycol and

Propylene glycol used. The polyester imide polyols described in DE 28 40 352 contain a theoretical imide content of about 6% by weight and are branched over the glycerol.

The technical progress in electrical engineering leads to ever more powerful and smaller components. The design of modern machines is increasingly demanding smaller motors, coils, transformers, etc. These need to operate at higher temperatures than their larger equivalent. This trend has a particularly strong effect on the area of fine and ultrafine wires. Especially in this area is a rapid Verzinnbarkeit the products to connect the ends of the coated wires quickly and easily electrically conductive with other components, another requirement. The requirement for improved thermostability of solderable (solderable) enameled wires is in principle contradictory to a short tinning time, which is required for a fast processing of the wires. Prior art are polyurethane enamel wires class 180. They have softening temperatures around 260 ⁰ C, tan delta values 5 to 180 ⁰ C with tin-plating of 1 sec at 360 ° C.

A disadvantage of the previously known prior art is that a high temperature resistance, expressed by the softening temperature (> 270 ° C), a high glass transition temperature (tan-delta> 200 ° C), and a very low tinning time (<4 sec at 400 ⁰ C) could not previously be combined in a coating agent.

Object of this invention was the development of a coating agent for heat-resistant substrates, in particular for wires, which has a high

15 temperature resistance, expressed by the softening temperature (> 270 ° C) and the glass transition temperature (tan-delta> 200 ° C), and a very low tin-plating time (<4 sec at 400 ⁰ C) in itself (values according to IEC 60851-4 ). At the same time, a very low tin-plating time means that the electro-insulating lacquers can be tin-plated, which is another important aspect of the problem of the invention

20 is present invention.

Surprisingly, the object could be achieved by using higher-functional isocyanates, with imides and / or amidimides modified Elektroisolierlackbindemittel. Despite the very good temperature resistance, the coated with this range of 25 electrical insulating wires at 400 ⁰ C were very quick solderable.

The invention relates to tin-soluble electrical insulating, in particular

Wire enamels, consisting of: A) at least one blocked polyisocyanate adduct, which retains the tinctorability of

B) at least one polyester-hydroxypolyol containing imide and / or amide groups,

C) organic solvents,

D) optionally further auxiliary substances and additives,

35 wherein the resulting imide compounds have a theoretical imide content of 8 to 40 wt .-%, preferably 10 to 25 wt .-%. Preferred subject of the present invention are tin-soluble electrical insulating, in particular wire enamels, consisting of:

A) at least one blocked polyisocyanate adduct, which allows the tin-plating of Elektroisolierlacke, wherein its proportion is 5-30 wt .-%, preferably

5 10-20 wt .-%, based on the weight of Elektroisolierlackes,

B) at least one polyester-hydroxypolyol containing imide and / or amide groups, the proportion of which is 1-20% by weight, preferably 3-10% by weight, based on the weight of the electrical insulating varnish,

C) organic solvents, the proportion of which is 50-90% by weight, preferably 70-0 85% by weight, based on the weight of the electrical insulating varnish,

D) further auxiliaries and additives, the proportion of which is 0-3% by weight, preferably 0.001-1% by weight, based on the weight of polyisocyanate adduct and polyester-hydroxypolyol, and wherein the resulting imide compounds have a theoretical imide content of 8 to 405 wt .-%, preferably 10 to 25 wt .-% have.

Which blocked Polyisocyanataddukte allow the Verzinnbarkeit the Elektroisolierlacke is readily determinable for the skilled person because of his general expertise. 0

In the context of the present invention, the theoretical imide content is calculated without consideration of the release products (H2O, CO2) formed during the formation reaction in order to obtain better comparability. The theoretical imide content thus corresponds to the percentage of the mass of imide groups 5 based on the total mass of the imide-containing compound.

For this determination in the context of the present invention, the imide group is used as OCNCO radical having a molecular weight of 70.027 g / mol.

For the preparation of the blocked polyisocyanate adduct A) to be used according to the invention, aromatic, aliphatic and cycloaliphatic are suitable

Polyisocyanates a), preferably polyisocyanates of a uniform or average average molecular weight of 140-600 with an NCO functionality of two to four. Such polyisocyanates are, for example, propylene diisocyanate,

Ethyl ethylene diisocyanate, 3,3,4-trimethylhexamethylene diisocyanate, 1, 3-5 cyclopenthyl diisocyanate, 1,4-cyclohexyl diisocyanate, 1, 2-cyclohexyl diisocyanate, 1, 3- and 1, 4-phenylene diisocyanate, 2,4- and 2,6- Diisocyanatotoluene (TDI) and mixtures of these isomers and their di- and trimers, 4,4- 2,4- and 2,2- Diisocyanatodiphenylmethane (MDI) and mixtures of these isomers or mixtures of these isomers with their higher homologs, as obtained in a known manner by phosgenation of aniline / formaldehyde condensates, 1, 5-naphthylene diisocyanate, 1, 4-butane diisocyanate, 2-methylpentane-1 , 5-diisocyanate, 1, 5-hexane diisocyanate, 1, 6-hexane diisocyanate (HDI), 1, 3- and 1, 4-cyclohexane diisocyanate and mixtures of these isomers, 2,4- and 2,6-diisocyanato-1-methylcyclohexane and Mixtures of these isomers, 3,5,5-trimethyl-3-isocyanatomethylcyclohexane isocyanate (IPDI) and dicyclohexylmethane 2,4- and 4,4-diisocyanate and mixtures of these isocyanates, 4,4'-diisocyanatodiphenyl ether and 2,3-bis-diisocyanate (8-isocyanato-octyl) -4-octyl-5-hexylcyclohexene, 1-isocyanatomethyl-5-isocyanato-1,3,3-trimethylcyclohexane, 4,4'-

Biphenylene diisocyanate, 1, 4-naphthylene diisocyanate. Preferred are as

Starting isocyanates aromatic polyisocyanates having an NCO functionality of 2

3. Very particular preference is given to 4,4- 2,4- and 2,2-

Diisocyanatodiphenylmethane (MDI) and mixtures of these isomers or mixtures of these isomers with their higher homologues, as obtained in a known manner by phosgenation of aniline / formaldehyde condensates.

Suitable reactants of the isocyanates a) for adduct formation are polyhydric alcohols b), preferably ethylene glycol, 1,2- and 1,3-propylene glycol, 1,2,3,1- and 1,4-butanediol, 1,5-pentanediol , Neopenthylglykol, diethylene glycol, triethylene glycol, bisphenols, and / or triols, preferably glycerol, trimethylolethane, trimethylolpropane or tris-2-hydroxyethyl isocyanurate. Preference is given to using triols, in particular trimethylolpropane and glycerol. Very particular preference is given to an adduct of 1 mol of trimethylolpropane and 3 mol of 4,4- 2,4- and 2,2-diisocyanatodiphenylmethane (MDI) and mixtures of these isomers or mixtures of these isomers with their higher homologs, as in a known manner by phosgenation of aniline / formaldehyde condensates.

Suitable blocking agents c) for the polyisocyanate adduct are aliphatic, cycloaliphatic or aromatic alcohols, e.g. Butanol, isobutanol, 2-

Ethylene hexanol, cyclohexanol, cyclopentanol, benzyl alcohol, phenols, cresols.

Further mention may be made of beta-hydroxyalkyl ethers, e.g. Methyl, ethyl, butylglycol,

Amines, e.g. Di-n-butylamine, di-n-hexylamine, oximes, e.g. methyl ethyl,

Diethylketoxime, hydroxylamines and lactams, e.g. Epsilon-caprolactam, as well as other compounds containing a hydrogen atom characterized by its reactivity

Implementation of the blocking agent with isocyanate allows. As preferred

Blocking agents are used phenols. According to the preferred preparation, the blocking agent or blocking agent mixture c) is introduced. The polyisocyanate or the polyisocyanates a) are added. The reaction mixture is stirred at a temperature of 10-180 ⁰ C, preferably 40 ° C-160 ° C until no more free isocyanate groups are present. Now the preferred triols and diols b) are added. After the condensation viscosity has been reached, it is diluted with the customary wire-enamel solvents. Among the usual wire-solvent solvents, those defined below as organic solvents C) are used.

Polyhydric alcohols d), preferably ethylene glycol, 1, 2 and 1, 3-propylene glycol, 1, 2, 1, 3 and 1, 4-butanediol, 1, 5-pentanediol are suitable for the preparation of the hydroxypolyol B) to be used according to the invention , Neopenthylglykol, diethylene glycol, triethylene glycol and / or triols, preferably glycerol, trimethylolethane, trimethylolpropane or tris-2-hydroxyethyl isocyanurate. Particularly preferred are ethylene glycol, 1, 2 and 1, 3-propylene glycol and tris-2-hydroxyethyl isocyanurate and mixtures of these alcohols.

Furthermore, for B) aromatic and aliphatic carboxylic acids and their esterified derivatives e) can be used: oxalic acid, malonic acid, succinic acid,

Glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, maleic acid,

Fumaric acid, sorbic acid, phthalic acid, isophthalic acid, terephthalic acid,

Trimesic acid, naphthalenedicarboxylic acids. The esterified derivatives are preferably methyl, ethyl, propyl, butyl, amyl, hexyl and octyl esters. It is possible to use both the half esters, the diacyl esters and the mixtures of these

Compounds as well as the corresponding acid halides. Also usable are anhydrides such as e.g. Pyromellitic dianhydride and trimellitic anhydride,

Naphthalenetetracarboxylic dianhydrides or dianhydrides of tetracarboxylic acids having two benzene nuclei in the molecule, in which the carboxyl groups are in 3,3'4- and 4'-position. Preference is given to terephthalic acid and

Trimellitic anhydride.

For the imide and amide modification of the polyester polyols B) to be used according to the invention, aromatic, aliphatic and cycloaliphatic diamines f) such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, benzidine, diaminodiphenylmethane, diaminodiphenylsulfone, sulfoxide, ethers, tioethers, phenylenediamines, tolylenediamine, dioxylylenediamine are suitable . Diamines with three benzene nuclei in the molecule, for example bis (4-aminophenoxy) -1,4-benzene, 4,4 ', - dicyclohexylmethanediamine, monoethanolamine and monopropanolamines, furthermore aminocarboxylic acids such as glycine, aminopropionic acid, aminocaproic acids or aminobenzoic acids. Preference is given to aromatic diamines such as diaminodiphenylmethane, diaminodiphenylsulfone, sulfoxide, ethers, tioethers, phenylenediamines. Polyisocyanates can also be used for amide and imidization. Here the same starting isocyanates are used as described for A).

In a preferred embodiment of the present invention, those amines and / or isocyanates which have an amine or isocyanate functionality between> 2 and 4 are used for the imidization; more preferably between 2.1 and 3, and more preferably between 2.1 and 2.6. This results in very good results. Examples of this are e.g. Mixtures of 4,4- 2,4- and 2,2-diisocyanatodiphenylmethane (MDI) and mixtures of these isomers or mixtures of these isomers with their higher homologs.

A useful commercial product is, for example, Desmodur < ^R > VL from Bayer AG, which has an isocyanate functionality of about 2.3 and is used in a preferred embodiment. In another preferred embodiment, further higher-functionality isocyanates can be used, for example Lupranat® ^R M10 WR from BASF.

It is also possible according to the invention to use various such higher-functionality compounds (eg Desmodur < ^R > VL and Lupranat < ^R > M10 WR) in a mixture.

Surprisingly, despite the high content of imide, the polyesterimide polyols according to the invention are soluble in high concentrations in the conventional wire-coating solvents and the polyurethanes prepared therefrom are still rapidly tin-pliable.

To prepare the polyester and modified polyester resins, the known transesterification catalysts are used. Examples are heavy metal salts, organic titanates and zirconates, cerium compounds and organic acids such as p-toluenesulfonic acid into consideration. Suitable catalysts for the preparation of the polyesters are amounts of from 0.01 to 5% by weight, based on the feed mixture, preferably from 0.3 to 3% by weight. These are preferably conventional esterification catalysts, for example heavy metal compounds, organic titanates and zirconates, cerium compounds and organic acids.

Examples of heavy metal compounds are oxides, carboxylates and alcoholates of the metals lead, zinc, tin, bismuth and antimony such as lead acetate and zinc acetate, octanoate. The titanates which can be used include, for example, tetraisopropyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraamyl titanate, tetrahexyl titanate, tetraethyl titanate, tetramethyl titanate, diisopropyldibutyl titanate or tetraphenyl titanate, tetracresyl titanate, tetrahexyl titanate or else triethanolamine titanate. Examples of usable organic acids are p-toluenesulfonic acid. Preferred catalysts are tin and zinc carboxylates as well as tin and zinc oxides and titanates.

According to a preferred manufacturing mold for component B) are the preferred polyhydric alcohols d), the preferred carboxylic acids and their esterified derivatives and anhydrides e) and the preferred esterification catalyst are submitted, and at a temperature of 100-200 ⁰ C, preferably 140-180 ⁰ C. condensed. Then, once or in portions, the imide-forming components, preferred polyamine f) with preferred anhydride e) in a ratio of 1: 3 to 3: 1, preferably 1: 0.8 to 0.8: 1 added. The temperature is gradually increased to 180 to 250 ⁰ C, preferably 190 ° C to 230 ° C and held until the condensation viscosity was reached. The usual wire-coating solvents are diluted to the desired solids content.

In another embodiment for the preparation of component B), the imide and amide-forming components are f submitted), preferred polyamine or polyisocyanate, and the preferred esterification catalyst with the usual wire enamel solvents and at 50 ° C to 200 ⁰ C, preferably at 80 ° C to 160 ° C, allow to react. Subsequently, to complete the reaction at 150 ⁰ C to 220 ° C, preferably heated to 160 ⁰ C to 200 ⁰ C and held for 1 h to 8h. Then the preferred polyhydric alcohols d) and optionally the preferred polyamines or polyisocyanates f) and optionally the preferred esterification catalysts are added and at a temperature of 160 ° C to 240 ° C, preferably 180 ° C to 220 ° C condenses. After the end of the condensation is diluted with the usual wire coating solvents to the desired solids content.

As organic solvents C) for the produced binders, the usual solvents are used, as they are usually used for Elektroisoliersysteme. These are phenols, cresols, xylenols and their technical isomer mixtures, glycol ethers, dimethyl glycol, ethyl glycol, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, phenyl glycol, glycol ether esters such as methyl glycol acetate, ethyl glycol acetate, butyl glycol aceate and methoxypropyl acetate, cyclic carbonates, e.g. Propylene carbonate, cyclic esters, gamma-butyrolactone and dimethylformamide, N, N-dimethylacetamide and N-methylpyrolidone. Furthermore, it is also possible to use aromatic and aliphatic alcohols and esters and phthalates, such as dimethyl phthalate and methyl benzoate, benzyl alcohol, n-butanol, isobutanol, if appropriate in combination with the abovementioned solvents. In addition, ketones such as cyclohexanone, isophorone.

The organic solvents may be partially replaced by cosolvents. Preferably, either pure solvent or pure solvent mixture or solvent with up to 40 wt .-%, based on the total weight, cosolvent used. Examples of suitable cosolvents are xylene, solvent naphtha, toluene, ethylbenzene, cumene, heavy benzene, various Solvesso and Shellsol types, and deasol.

In addition to the described components, the electrical insulating varnishes optionally contain customary auxiliaries and additives D) in the range from 0 to 3% by weight.

%, preferably in the range of 0.001 to 1 wt .-%, based on the weight of

Polyisocyanate adduct and polyester hydroxypolyol. As an aid to the

Elektroisolierlacke can, for example, improving the history phenol or

Melamine resins or other conventional leveling agents, e.g. based on polyacrylates and polysiloxanes are used.

In a further preferred embodiment of the present invention, it is also possible that the inventive zinnable Elektroisolierlack still other from component A), capped isocyanates and / or isocyanurates in an amount of 25 to 35 wt .-%, based on the polyisocyanate adduct A ) contains, the electrical insulating then so from the components A), B), C), D) and E).

Example of useful compounds for this purpose are blocked Toluylenisocyanurate, such as Desmodur < ^R > CT stable.

In addition, the electrical insulating varnishes may contain crosslinking catalysts; Preferably, they contain these in amounts of 0.5 to 2.0 wt .-%, based on the weight of polyisocyanate adduct and polyester hydroxypolyol. In the case of the polyurethane based wire coating compositions, organometallic compounds have e.g. the metals potassium, magnesium, aluminum, tin, lead, zinc, iron, titanium, bismuth, antimony and zirconium and tertiary amines proven as crosslinking catalysts, usually in amounts of 0.5 to 2.0 wt .-%, based on the Weight of polyisocyanate adduct and polyester hydroxypolyol can be used.

The hyxdroxyl-containing polyesters B) and the blocked isocyanate adduct A) are used in a variant according to the invention together in an amount of from 18 to 40% by weight, preferably from 25 to 35% by weight, based on the total weight of the electrical insulating varnish. The amount of blocked isocyanate adducts is between 150 and 500 parts by weight per 100 parts by weight of hydroxyl-containing polyester, depending on the OH equivalent of the (modified) polyester and on the content of blocked NCO groups of the isocyanate adducts. The ratio of hydroxyl groups to isocyanate groups may be from 3: 1 to 1: 3, preferably 2: 1 to 1: 2. It is advantageous if there is a slight excess of hydroxyl groups, preferably a numerical excess of up to 10%, in particular up to 5%, based on the isocyanate groups.

The electrical insulating lacquers according to the invention are tin-pliable. Preferred are the

Electrical insulating coatings Wire enamels.

In the highly preferred embodiment according to the invention, the inventive tin-coatable electrical insulating lacquer consists of at least one blocked polyisocyanate adduct which satisfies the tinctorability of the

Elektroisolierlacke allows, the proportion of which is 5-30 wt .-%, preferably 10-20 wt .-%, based on the weight of Elektroisolierlackes, B) at least one polyester-hydroxypolyol containing imide and / or amide groups, the proportion of which is 1-20% by weight, preferably 3-10% by weight, based on the weight of the electrical insulating varnish,

C) organic solvents, the proportion of which is 50-90% by weight, preferably 70-5 85% by weight, based on the weight of the electrical insulating varnish,

D) further auxiliaries and additives, the proportion of which is 0-3% by weight, preferably 0.001-1% by weight, based on the weight of polyisocyanate adduct and polyester hydroxypolyol,

E) further capped isocyanates different from component A) and / or 10 isocyanurates in an amount of 25 to 35% by weight, based on the

Polyisocyanate adduct A), wherein the resulting imide compounds have a theoretical imide content of 8 to 40 wt .-%, preferably 10 to 25 wt .-% and wherein the imide and / or amide groups-containing polyester hydroxypolyol B) under 15 using amines and Isocyanates which have an amine or isocyanate functionality between> 2 and 4 is prepared.

The Elektroisolierlacke can be applied and cured by means of conventional Drahtlackiermaschinen. The required paint film thickness is through

20 at least 1 up to 10 individual orders have been set up, whereby each individual coating application is cured bubble-free before the new paint application. Conventional coating machines operate at take-off speeds of 5 m / min up to several hundred m / min, depending on the thickness of the wire to be coated. Typical oven temperatures are between 300 and 550 ^° C.

25

Preferred painting conditions:

Temperature: about 400 ⁰ C

Application system: felt

Wire diameter: 0.15 mm

30 Number of passes: 10

Increase level: 2 L

The painted wires are tested according to IEC 60851.

The invention is explained in more detail below with reference to a few examples:

Examples EXAMPLE 1 Production of a Blocked Polyisocyanate Adduct A 283 g of cresol mp (meta-para isomer mixture) and 267 g of Suprasec ^(R) X 1004 (Huntsman) are weighed into a reaction apparatus with a condensate separator with stirring and introduction of nitrogen. The mixture is heated to 30 ⁰ C, wherein an exothermic reaction begins. The mixture is then heated at 5-10 ° K / h to a reaction temperature of 160 ⁰ C. At this temperature, the batch is held until the NCO content is <1%. Then 51 g of trimethylolpropane (TMP) are added. The reaction mixture is condensed until the entire TMP has reacted away. This is followed by the addition of 190 g cresol mp and 208 g solvent naphtha ^(R) and it is stirred for 4h. The polyisocyanate adduct obtained has a viscosity of about 2000mPas (23 ° C) and a solids content of 43% (1 g / 1 h / 180 ⁰ C).

Example 2: Preparation of a Blocked Polyisocyanate Adduct B

30 g of cresol mp, 42 g of phenol, and 211 g of xylenol DG (technical grade xylenol) are weighed into a reaction apparatus with a condensate separator with stirring and introduction of nitrogen and heated to 80.degree. Then 266 g of 4,4-MDI are added. An exothermic reaction sets in. The mixture is then heated at 5-10 ° K / h to a reaction temperature of 160 ⁰ C. At this temperature, the batch is held until the NCO content is <1% and condensed at 160 ⁰ C. Thereafter, 51 g of trimethylolpropane are added. After the TMP has reacted, add 190 g of cresol mp and 208 g of solvent naphtha ^(R) and stir for 4 h. The polyisocyanate adduct obtained has a viscosity of about 2000mPas (23 ° C) and a solids content of 43% (1 g / 1 h / 180 ° C).

Example 3: Preparation of a blocked polyisocyanate adduct C

1417 g of cresol mp, 1061 g of 4,4-MDI (4,4-diisocyanatodiphenylmethane) and 323 g of Suprasec 2085 < ^R »(polyfunctional isocyanate from Huntsman) are weighed into a reaction apparatus with a condensate separator with stirring and introduction of nitrogen. The mixture is heated to 40 ⁰ C, wherein an exothermic reaction begins. The mixture is then heated at 5-10 ° K / h to a reaction temperature of 160 ⁰ C. At this temperature, the batch is held until the NCO content is <1%. Thereafter, 203 g of trimethylolpropane are added. The reaction mixture is condensed until the entire TMP has reacted away. Then 953 g of cresol mp and 1040 g of solvent naphtha ^(R) are added and the mixture is stirred for 4 h. The resulting polyisocyanate adduct has a viscosity of 1380mPas (23 ° C) and a solids content of 42.4% (1 g / 1 h / 180 ⁰ C).

Example 4: Preparation of a Hydroxypolyol A

The following components are weighed into a reaction apparatus with a condensate separator with stirring and introduction of nitrogen: 179 g of ethylene glycol, 0.6 g of zinc octoate. Then 277 g of trimellitic anhydride and 93 g of 4,4-diaminodiphenylmethane are added in four portions and heated to 190 ⁰ C. The mixture is polycondensed at 220 ⁰ C until an acid number of <10 mg / KOH / g is reached. The mixture is then diluted with 1 13 g of cresol, 340 g of phenol and 90.91 g of solvent naphtha ^(R) . The hydroxypolyesterimide A thus prepared has a viscosity of 4700 mPas (23 ° C.) and a solids content of 44% (1 g / 1 h / 180 ° C.) and an imide content of about 12% by weight.

Example 5: Preparation of a hydroxypolyol B

The following raw materials are weighed into a reaction apparatus with a condensate separator with stirring and introduction of nitrogen: 1 162 g cresol, 90 g solvent naphtha < ^R >, 536 g Desmodur VU ^R > from Bayer AG, 768 g trimellitic anhydride, 1 g dibutyltin oxide. Then it is carefully heated to 180 ⁰ C. The foaming caused by the elimination of carbon dioxide determines the heating rate. At a temperature of 180 ⁰ C, the mixture is polycondensed 5h until no elimination of carbon dioxide is more detectable. Then, at a temperature of 180 ° C, the addition of 250 g of ethylene glycol and 0.5 g of dibutyltin oxide. It is heated to 200 ° C with 10K7h. After reaching the clear point at 200 ° C is held for 4h. The batch is taken up with 200 g of cresol and 432 g of solvent naphtha ^(R) . The Hydroxypolyesterimid B thus prepared has a viscosity of 3850mPas (23 ° C) and a solids content of 44.5% (1 g / 1 h / 180 ⁰ C) and a Imidanteil of about 18 wt .-%.

Example 6: Preparation of a hydroxypolyol C

The following raw materials are weighed into a reaction apparatus with a condensate separator with stirring and introduction of nitrogen: 1500 g of cresol, 50 g of solvent naphtha < ^R », 536 g of Desmodur VU ^R from Bayer AG, 768 g of trimellitic anhydride and 1 g of dibutyltin oxide. Then it is carefully heated to 180 ⁰ C. The foaming caused by the elimination of carbon dioxide determines the heating rate. At a temperature of 180 ⁰ C, the mixture is polycondensed for 5 h until no Cleavage of carbon dioxide is more detectable. Then, at a temperature of 150 ⁰ C, the addition of 150 g of ethylene glycol, 2g butyl titanate and 396g 4,4-diaminodiphenylmethane. It is heated to 200 ⁰ C with 10K7h. At a temperature of 200 ° C is held for 4h. The batch is taken up with 414 g of solvent naphtha < ^R ». The hydroxypolyesterimide C prepared in this way, after further dilution with 100 g of cresol and 300 g of solvent naphtha < ^{R, has} a viscosity of 1200 mPas (23 ° C.) and a solids content of 43.1% (1 g / 1 h / 180 ° C.) and an imide content of about 15 wt .-%.

Example 7: Preparation of a hydroxypolyol D

The following raw materials are weighed into a reaction apparatus with a condensate separator with stirring and introduction of nitrogen: 2500 g of cresol, 100 g of solvent naphtha ^(R) , 1536 g of trimellitic anhydride, 2 g of dibutyltin oxide. The mixture is heated to 150 ⁰ C, from 150 ° C 1072g Desmodur VU ^R foaming is> dosed wherein from a dropping funnel, determines the dispensing rate. After the addition of the polyisocyanate is heated at 10 ° K / h to 180 ⁰ C and the mixture is polycondensed for 5 h until no elimination of carbon dioxide is more detectable. At a temperature of 180 ° C, the addition of 720g 1, 2-propylene glycol and 6 g of dibutyltin oxide takes place. It is heated to 200 ⁰ C with 10K7h. At a temperature of 200 ° C is held for 4h. The batch is solubilized with 700 g cresol / solvent naphtha 2: 1. The hydroxypolyesterimide thus prepared has a viscosity of 8160 mPas (23 ° C) and a solids content of 45.57% (1 g / 1 h / 180 ⁰ C) and an imide content of about 17 wt .-%. 1500 g of the resin solution are mixed with 295 g of 4,4-diaminodiphenylmethane and with 2 g of dibutyltin oxide. The reaction mixture is slowly heated to 215 ° C and held for 4h. After cooling to 200 ° C., the batch is taken up with 433 g of cresol and 216 g of solvent naphtha < ^R ». The Hydroxypolyesterimid D thus prepared has a viscosity of 16600mPas (23 ° C) and a solids content of 41 89% (1 g / 1 h / 180 ⁰ C) and a Imidanteil of about 12 wt .-%.

EXAMPLE 8 Preparation of an Inventive Electrical Insulating Varnish The following PUR coating raw materials are weighed into a mixer: 5300 g polyisocyanate adduct B, 1900 g Desmodur® ^R stable (40% solution), 3132 g cresol, 1375 g solvent naphtha < ^R >, 1350 g xylene, 25 g dibutyltin dilaurate. The paint mixture is stirred intensively for 4 h. 4400 g of the lacquer solution are mixed intensively with 602 g of hydroxypolyol C, which was previously diluted with 150 g of cresol. With XyIoI and solvent naphtha < ^R », the PUR wire enamel is adjusted to a solids content of 24.8% (1 g / 1 h / 180 ° C). A coated with this enameled wire is at 400 ⁰ C solderable within 3 sec., The tan delta break point was 221 ⁰ C, the softening temperature is 275 ° C.

EXAMPLE 9 Preparation of an Inventive Electrical Insulating Varnish The following PU coating raw materials are weighed into a mixer: 3531 g of polyisocyanate adduct A, 131.1 g Desmodur CT stable (40% solution), 2058 g cresol, 884 g solvent naphtha < ^R >, 884 g xylene, 27 g vulcacite 576 < ^R > and 87g of a silicone-containing leveling additive. The paint mixture is stirred intensively for 4 h. 4394g of the paint solution are mixed with 604g Hydroxypolyol C that was previously diluted with 150 g of cresol, and 150 g xylene and 150 g of solvent naphtha ^(R) to a solids content of 23.85% set (1 g / 1 h / 180 ⁰ C).

A coated with this enameled wire is at 400 ⁰ C solderable within 2 sec., The tan delta break point was 211 ° C, the softening temperature is 280 ° C.

Example 10 Production of an Electrical Insulating Lacquer According to the Invention

The following PUR coating raw materials are weighed in a mixer:

3025g polyisocyanate adduct C, 925g desmodur CT stable (40% solution), 1690g cresol, 706g solvent naphtha < ^R >, 706g xylene, 20g dibutyltin dilaurate and 67g of a silicone containing flow additive. The paint mixture is stirred intensively for 4 h. 3570g of the polyisocyanate adduct C coating solution are mixed with 513g Hydroxypolyol C that cresol was previously diluted with 160 g, and 64g of xylene and 64g of solvent naphtha ^<R> to a solids content of 24.5% (1 g / 1 h / 180 ⁰ C) set. A coated with this enameled wire is at 400 ⁰ C solderable within 3 sec., The tan delta break point was 215 ° C, the softening temperature is 285 ° C.

Example 1 1: Preparation of an Electrical Insulating Lacquer According to the Invention The following PU coating raw materials are weighed into a mixer:

3025g polyisocyanate C, 925g Desmodur CT stable (40% solution), 1690g cresol, 706g solvent naphtha ^<R> 706g xylene, 1054,0g dimethyl phthalate, 26g Vulcacit 576 ^®, 2g dibutyltindilaurate and 67 g of a silicone-containing flow control additive. The paint mixture is stirred intensively for 4 h. 3570 g of polyisocyanate adduct C enamel solution, 533 g of hydroxypolyol D, which was previously diluted with 160 g of cresol, mixed and adjusted with 64 g XyIoI and 64 g solvent naphtha < ^R > to a solids content of 24.5% (1 g / 1 h / 180 ° C). A coated with this enameled wire is at 400 ⁰ C solderable within 1 sec., The tan delta break point was 220 ⁰ C, the softening temperature is 280 ° C.

EXAMPLE 12 Production of an Electrical Insulating Varnish as Comparative Example The following PU coating raw materials are weighed into a mixer: 3531 g of polyisocyanate adduct A, 131. 1 g Desmodur CT stable (40% solution), 2058 g cresol, 884 g solvent naphtha < ^R >, 884 g xylene, 27 g vulcacite 576 < ^R > and 87g of a silicone-containing leveling additive. The paint mixture is stirred intensively for 4 h. 4394g of the polyisocyanate adduct A resist solution are mixed with 604g Hydroxypolyol A, that had previously been diluted with 150 g of cresol, and ^<R> to a solids content of 23.94% adjusted with 150g of xylene and 150g of solvent naphtha (1 g / 1 h / 180 ⁰ C) , A coated with this enameled wire is at 400 ⁰ C solderable within 1 sec., The tan delta break point was 185 ° C, the softening temperature is 255 ° C.

Claims

Claims: 1. Tinnable Elektroisolierlack, consisting of A) at least one blocked polyisocyanate adduct, the Tinnability of Elektroisolierlacke allows B) at least one polyester-hydroxypolyol containing imide and / or amide groups, C) organic solvents, D) other auxiliaries and additives, and wherein the resulting imide compounds have a theoretical imide content of 8 to 40 wt .-%, preferably 10 to 25 wt .-%. 2. Tinnable Elektroisolierlack, consisting of A) at least one blocked polyisocyanate adduct, the Tinnability of Elektroisolierlacke allows B) at least one polyester-hydroxypolyol containing imide and / or amide groups, C) organic solvents, D) other auxiliaries and additives, E) further capped isocyanates and / or isocyanurates other than component A) in an amount of 25 to 35% by weight, based on the polyisocyanate adduct A), the resulting imide compounds having a theoretical imide content of 8 to 40% by weight, preferably 10 to 25 wt .-% have. 3. Elektroisolierlack according to claim 1 or 2, characterized in that A) the proportion of A) is 5-30 wt .-%, preferably 10-20 wt .-%, based on the weight of Elektroisolierlackes, B) the proportion of B) 1-20 wt .-% is, preferably 3 -10 wt .-%, based on the weight of Elektroisolierlackes, C) the proportion of C) is 50-90% by weight, preferably 70-85% by weight, based on the weight of the electrical insulating varnish, D) the proportion of D) is 0-3 wt .-%, preferably 0.001-1 wt .-%, based on the weight of polyisocyanate adduct and polyester hydroxypolyol. 4. Elektroisolierlack according to any one of claims 1 to 3, characterized in that the imide and / or amide-containing polyester hydroxypolyol B) using amines and / or isocyanates having an amine or isocyanate functionality between> 2 and 4 is produced. 5. Elektroisolierlack according to any one of claims 1 to 4, characterized in that it has a softening temperature of at least 270 ⁰ C, preferably of 275 ° C, in particular of at least 280 ⁰ C after painting and baking. 6. Elektroisolierlack according to any one of claims 1 to 5, characterized in that it has a tan delta of at least 200 ⁰ C after painting and baking. 7. Elektroisolierlack according to any one of claims 1 to 6, characterized in that it has a tin-plating time of at most 4 seconds at 400 ⁰ C after painting and baking. 8. A process for the preparation of Elektroisolierlacke according to any one of claims 1 to 7, characterized in that the components A), B), C), D) and optionally E) are mixed together. 9. Use of the electrical insulating varnish according to one of claims 1 to 7 in the coating of motors, coils, transformers, fine and superfine wires and for heat-resistant substrates, in particular for wires. 10. Use of the Elektroisolierlacke according to one of claims 1 to 7 in painting machines under conditions of Withdrawal speeds of 5 m / min up to several hundred m / min, - oven temperatures between 300 and 550 ° C 1 to 20 passes.