EP0616628A1

EP0616628A1 - Wire enamels based on tris-2-hydroxyethylisocyanurate-containing polyesters and process for preparing the same

Info

Publication number: EP0616628A1
Application number: EP92924638A
Authority: EP
Inventors: Michael Schink; Gerold Schmidt; Klaus-Wilhelm Lienert; Roland Peter
Original assignee: Beck Dr and Co GmbH
Current assignee: Beck Dr and Co GmbH
Priority date: 1991-12-09
Filing date: 1992-12-01
Publication date: 1994-09-28
Also published as: TR27664A; RU94039928A; US5536791A; WO1993012188A1; JPH07504692A; DE4140472A1; BR9206901A

Abstract

Des vernis pour fils de fer contiennent: (a) 20 à 50 % en poids d'un polyester modifié par du tris-2-hydroxyéthylisocyanurate; (b) 2 à 35 % en poids d'une résine bismaléinimide; (c) 0,1 à 3 % en poids d'un catalyseur, de préférence un catalyseur au titanate; et (d) 35 à 77 % en poids d'un solvant organique, par rapport au poids total du vernis pour fils de fer, qui s'élève à 100 % en poids. L'invention concerne également des procédés de préparation de ces vernis pour fils de fer.Wire varnishes contain: (a) 20 to 50% by weight of a polyester modified with tris-2-hydroxyethylisocyanurate; (b) 2 to 35% by weight of a bismaleinimide resin; (c) 0.1 to 3% by weight of a catalyst, preferably a titanate catalyst; and (d) 35 to 77% by weight of an organic solvent, based on the total weight of the wire varnish, which amounts to 100% by weight. The invention also relates to processes for the preparation of these varnishes for wires.

Description

WIRE COATS BASED ON POLYESTERS CONTAINING TRIS-2-HYDROXYETHYLISOCYANURATE, AND METHOD FOR THE PRODUCTION THEREOF.

The present invention relates to wire enamels containing polyester based on tris-2-hydroxyethyl isocyanurate, organic solvents, catalysts,

Auxiliaries and additives. The present invention also relates to a method for producing these wire enamels.

Wire enamels based on polyester resins are known and described, for example, in US Pat. No. 3,342,780, in US Pat. No. 3,249,578 and in EP-B-144 281. As

Polyol component is used in the publications mentioned tris-2-hydroxyethyl isocyanurate. The use of tris-2-hydroxyethyl isocyanurate (THEIC) leads to particularly high softening temperatures

Wire enamel layer or at a particularly high thermal pressure (IEC 851-6). Those with wire enamels based on

Wires coated with polyester resins are characterized by the fact that the coating film has good adhesion

Owns copper wires.

The disadvantage of wire enamels based on polyester resins compared to wire enamels based on polyesterimide resins or polyamideimide resins is that the wires coated with polyester enamels have a low thermal shock. THEIC modified Polyester wire enamels are therefore used in two-layer coatings for wires as a "base coat" to which, for example, a polyamideimide wire enamel is applied.

The object underlying the present invention was to provide wire enamels which avoid the disadvantages associated with polyester wire enamels and thus improve the property profile of THEIC polyester wire enamels. These wire enamels should be stable in storage, have good adhesion to copper wires, have the highest possible heat pressure and sufficient thermal shock.

In addition, the wire enamels should have the highest possible solids content with a viscosity that is favorable for processing. The surface quality of the painted wires should be improved, especially with regard to the hardness properties. This object is achieved by wire enamels containing polyester based on tris-2-hydroxyethyl isocyanurate (THEIC), organic solvents, catalysts, auxiliaries and additives, which are characterized in that the wire enamels a) 20 to 50% by weight of THEIC Polyester, b) 2 to 35% by weight of a bismaleimide resin, c) 0.1 to 3% by weight of a catalyst, preferably a titanate catalyst, and d) 35 to 77% by weight of organic solvents, based on the total weight of the wire enamel , which is 100% by weight. It is surprising and unpredictable that the modification of THEIC polyester wire enamels with bismaleimide resins gives wire enamels which adhere very well to copper wires and which lead to coatings with excellent technological properties.

The individual components of the wire enamels according to the invention will now be explained in more detail below.

The polyesters (component a)) modified with tris-2-hydroxyethyl isocyanurate (THEIC) are known and are described, for example, in US Pat. No. 3,342,780 and EP-B-144 281. The polyesters are prepared in a known manner by esterification of polybasic carboxylic acids with polyhydric alcohols in the presence of suitable catalysts. As an alcohol component, i.a. Tris-2-hydroxyethyl isocyanurate used.

Instead of the free acid, its ester-forming derivatives can also be used.

Alcohols suitable for the production of the polyesters are, for example, ethylene glycol, 1,2-and 1,3-propylene glycol, 1,2-butanediol, 1,3 and -1,4, 1,5-pentanediol, neopentyl glycol, diethylene glycol, triethylene glycol kol and triols, such as glycerol, trimethylolethane, trimethylolpropane and tris-2-hydroxyethyl isocyanurate. Mixtures of ethylene glycol and tris-2-hydroxyethyl isocyanurate are preferably used. The use of tris-2-hydroxyethyl isocyanurate leads to high softening temperatures of the lacquer layer. Suitable carboxylic acids are, for example, phthalic acid, isophthalic acid, terephthalic acid and their esterifiable derivatives, such as the anhydrides, if they exist, and the lower alkyl esters of the acids mentioned, such as methyl, ethyl, propyl, butyl, amyl, hexyl and octyl phthalates, terephthalates and isophthalates. Both the half esters, the dialkyl esters and mixtures of these compounds can be used. The corresponding acid halides of these compounds can also be used. The amounts of the individual components are chosen so that the polyesters have a ratio of hydroxyl to carboxyl groups from 1.1: 1 to 2.0: 1, preferably from 1.15: 1 to 1.60: 1. Catalysts suitable for the production of the polyesters, which are used in amounts of 0.01 to 5% by weight, based on the feed mixture, are conventional esterification catalysts, for example

Heavy metal salts, for example lead acetate, zinc acetate, furthermore organic titanates, for example

Tetra-n-butyl titanate, cerium compounds and organic acids, e.g. p-toluenesulfonic acid.

A polyester a) which is produced from ethylene glycol, tris-2-hydroxyethyl isocyanurate and dimethyl terephthalate and has a hydroxyl number in the range from 80 to 150 mg KOH / g is preferably used in the wire enamels according to the invention. Among those as component b) of the invention

Bismaleimide resins used in wire enamels are resins or prepolymers with bismaleimides as building blocks. The bismaleimide resins are generally obtained from the bismaleimide units and comonomers (hardeners). Mixing and heating the bismaleimides and the comonomers gives them Bismaleimide resins or prepolymers. Bismaleimide building blocks correspond to the general formula

where Y is an optionally substituted alkenyl group and X is a divalent radical having at least two carbon atoms. Monomeric bismaleimides are e.g. known from DE-A-20 40 094, DE-A-27 19 903 and DE-A-32 47 058.

Preferred bismaleimide components are 4,4'-bismaleimidodiphenylmethane, 4,4'-Bismaleinimidodiphenylether, ^3.3, -Bismaleinimidodiphenylsulfon, 1,3-bismaleimidobenzene, 2,4-Bismaleinimidotoluol, 1,6-bismaleimidohexane and 2,2,4- Trimethyl-1,6-bismaleimidohexane. In addition to bismaleimides, polymaleimides and mixtures of various bismaleimides can also be used to prepare the bismaleimide resins. The bismaleimides can also contain up to 20% of a monoimide.

Suitable comonomers are alkenyl compounds, aromatic and aliphatic polyamines, polyphenols, aminophenols, vinyl and allyl compounds. Polyamines suitable as comonomers are known, for example, from DE-A-17 70 867; 4,4'-diaminodiphenylmethane are preferred, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodicyclohexyl methane and 3,3'-diaminodiphenyl sulfone. Among the polyphenols that can be used are bisphenol A, bisphenol F or novolaks; others are listed in DE-A-24 59 925. Suitable alkenylphenols or phenol ethers are described in DE-A-26 27 045, o, o'-diallybisphenol A is preferred. Oligomeric allyl- or propenyl-terminated sulfones or allylated dicyclopentadiene polyphenols are also suitable. Aminophenols which can be used are, for example, m- or p-aminophenol. Examples of vinyl and allyl compounds are: styrene, divinylbenzene, diallyl phthalate,

Acrylates, methacrylates, diallylbenzene, alkenylphenols, alkenylphenol ethers, triallyl isocyanurate or vinyl pyrrolidone. Vinyl and allyl compounds are preferred, in particular dially ibisphenol A.

Suitable additives are, for example

Fillers such as chalk, kaolin, quartz flour, dolomite, heavy spar, metal powder, aluminum oxide hydrate, cement,

Talc, diatomaceous earth and pigments,

Reinforcing fibers such as glass, carbon, asbestos and cellulose fibers as well as synthetic organic fibers, e.g. from polyethylene, polycarboxylic acid esters, polycarbonate or polyamides, inhibitors such as hydroquinones, quinones, nitrobenzenes, N-nitroso compounds, salts of divalent copper and quaternary ammonium salts,

Polymerization initiators, such as benzoyl peroxide,

Methyl ethyl ketone peroxide, tert-butyl peroctoate,

tert-butyl perbenzoate, cyclohexanone peroxide, acetylacetone peroxide, perketals, percarbonates, dicumyl peroxide, C-C-labile compounds and azo compounds,

Hardening accelerators, for example octoates or naphthenates of copper, lead, calcium, magnesium, cerium and in particular of manganese and cobalt; also aromatic Amines, such as dimethylaniline and diethylaniline, imidazoles, tertiary phosphines, organic acids,

- Shrinkage-reducing polymers, such as polystyrene, polymethyl methacrylate, polyvinyl acetate, polyethylene, polybutadiene and graft copolymers, copolymers and condensation polymers, such as saturated polyesters or polyester urethanes,

- elasticizing additives, e.g. rubbery

Block copolymers and modified polytetrahydrofuran, - flame retardants and plasticizers.

To prepare the bismaleimide resins b), the starting materials are mixed using customary techniques and at temperatures of i.a. 70 to 190 ° C heated, depending on the reaction time, a prepolymer is formed with an increase in viscosity. Depending on the type of comonomer and the amount of comonomer, a viscous solution or a glassy solid which is either ground or dissolved in a solvent, for example dimethylformamide or N-methylpyrrolidone, is obtained after cooling. The bismaleimide resins can also be prepared in a solvent. Suitable bismaleimide resins are described, for example, in DE-A-38 27 120, DE-A-38 35 197 and DE-A-39 24 867.

The solid, meltable bismaleinimide resins known from DE-A-39 24 867 are particularly preferably used in the wire enamels according to the invention. These are made from

A) a bismaleimide of the formula

With

X = CH ₂ , 0 or SO ₂ ,

R = C ₁ -C ₄ alkyl,

n = 0.1 or 2,

B) an aminophenol of the formula

with m = 1 or 2, in the molar ratio A): B) = 2.4: 1 to 1.4: 1, with A) and B) pre-reacting to a prepolymer, and optionally C) 0 to 2% by weight , based on A) + B), of a secondary or tertiary amine or phosphine as Ad dition catalyst,

D) 0 to 1% by weight, based on A) + B), of a polymerization inhibitor,

E) 0 to 25% by weight, based on A) + B), of a copolymerizable vinyl or allyl compound,

F) 0 to 25% by weight, based on A) + B), of an epoxy resin containing at least 2 epoxy groups and

G) 0 to 2% by weight, based on A) + B), of a peroxide initiator, 70 to 90 mol% of A) and 30 to 60 mol% of B) being present in unreacted form and the remainder remaining Prepolymer has reacted. Suitable bismaleimides A) are the bismaleimide building blocks already mentioned, 4,4'-methylene-bis- (N-phenylmaleimide) preferably being used.

Examples of suitable aminophenols B) are m-, o- and p-aminophenol, with m-aminophenol being preferred. The molar ratio A): B) is between 2.4: 1 and 1.4: 1, preferably between 2.0: 1 and 1.5: 1 and in particular between 1.8: 1 and 1.6: 1. Suitable ones Catalysts C) are secondary or tertiary amines or phosphines. Preferred amines are N, N, N ', N'-tetramethyldiaminodiphenylmethane, N, N-dimethylaniline and dimethylbenzylamine or also imidazoles, such as 1-methylimidazole. Triphenylphosphine is preferred for the phosphines. As inhibitors D) for preventing the premature radical polymerization of the double bond of the bismaleimide, customary, preferably phenolic compounds, in particular hydroquinone or 2,6-dimethylhydroquinone, are obtained in amounts of up to 1, preferably 0.1 to 0.5% by weight to the sum of A) + B).

Vinyl and allyl compounds E), which are admixed in amounts of up to 25, preferably from 5 to 20,% by weight, based on the sum of A) + B), are copolymerized as comonomers in the resin matrix during the curing of the prepreg. They act as thinners to lower the resin viscosity, but above all you can, by suitable choice of the type and amount of these additives, also in the form of mixtures of several vinyl or allyl compounds, the stickiness of the

Set the prepregs precisely and lower the softening temperature of the resin to room temperature. Monomers are preferred which are two or three vinyl or

Have allyl groups. Suitable are, for example, N-vinylpyrrolidone, N-vinylcarbazole, divinylbenzene, acrylates, diallyl ethers, ethoxylated bisphenol A methacrylate, 3,3'-diallyl bisphenol A, 3,3'-dipropenyl bisphenol A, and also reaction products of a diepoxide with acrylic acid or methacrylic acid, but especially diallyl phthalate or prepolymers produced therefrom, triallyl cyanurate and triallyl isocyanurate. Conventional epoxy resins F) in amounts of up to 25% by weight, based on A) + B), can also act as reactive thinners which are incorporated into the resin matrix. As polymerization initiators G) to accelerate the curing process, 0 to 2, preferably 0.01 up to 2% by weight, based on the sum of A) + B), of conventional peroxides which decompose into free radicals at temperatures above 180 ° C. The mixture is heated to temperatures between 140 to 190 ° C., preferably to 150 to 180 °, the components melting and bismaleimide and aminophenol reacting with one another. The residence time of the reactants at these temperatures should be relatively short, preferably 1 to 10, in particular 2 to 4 minutes. be. The reaction is carried out until 70 to 90 mol% of component A and 30 to 60 mol% of component B are still present in the unreacted form in the bismaleimide resin formed. The degree of conversion can be controlled in a simple manner by means of the reaction temperature, reaction time and, if appropriate, the type and amount of the addition catalyst. The progress of the reaction can be monitored by rapid cooling and analytical determination of the unreacted starting components A) + B). High pressure liquid chromatography (HPLC) is used for the quantitative determination of A + B in the resin mixture, whereby the retention times and areas were previously calibrated with the pure substances A and B. After the reaction has ended, the melt is rapidly cooled. The resin can be granulated, flaked or pulverized.

With regard to further details on the production of the bismaleimide resins b) preferably used in the wire enamels according to the invention, reference is made to corresponding statements in DE-A-39 24 867.

Furthermore, in the wire enamels according to the invention, bismein imide resins b) which are particularly preferably used A) a bismaleimide,

B) a heterocyclic comonomer of the formula

R-Ar-O-Het-O-Ar-R with R = alkenyl or alkenyloxy group with 3-6

Carbon atoms,

Ar = phenylene, naphthylene or

with X = O, S, SO ₂ , CO, C (R ^, ) ₂ (R '= H, C ₁ -C ₆ alkyl, CF ₃ or phenyl) or a chemical bond, where Ar can optionally carry a hydroxyl group ,

Het = heterocyclic six-membered ring selected from the group

contain. Such preferred bismaleimide resins are described in DE-A-38 27 120.

Suitable comonomers B) are, for example, 2,6-bis (3-allyl-4-hydroxyphenoxy) pyridine, 2,6-bis (3-allyloxyphenoxy) pyridine, 2,6-bis (4-allyl-3- hydroxyphenoxy) pyridine, 2,6-bis [(3-allyl-4-hydroxyphenylisopropyl) phenoxy] pyridine and the corresponding pyridazine derivatives. 2,6-Bis (2-propenylphenoxy) pyridine is particularly preferably used as the heterocyclic comonomer. Suitable manufacturing processes are in the

DE-A-38 27 120.

With regard to suitable monomeric bismaleimides, reference is made to the aforementioned examples.

To prepare the bismaleimide resins, the starting materials are mixed using customary techniques and heated to temperatures between 70 and 190 ° C., with the formation of a prepolymer. Depending on the progress of the prepolymerization, a relatively low-viscosity melt or a glass-like solidified solid is obtained, which is ground or dissolved in a solvent. The resins can also be prepared in a solvent.

The mixing ratio in the reaction of the bismaleimide with the heterocyclic alkenyl compound can be chosen relatively freely, an equivalent ratio of 1 to 0.05 to 5 being preferred.

Further components can be added to the bismaleimide resins described. Possible additional components are, for example, amines, preferably aromatic diamines (for example 4,4 ^, -diaminodiphenylmethane) and aminophenols, which are also an addition reaction can make double bonds with maleimide. Prepolymers, for example of a bisimide and an amine, can also be used. Other components up to a share of

50% by weight, based on the mixture, can also be used are suitable vinyl monomers, e.g. Styrene, α-methylstyrene, divinylbenzene, acrylic or methacrylic acid ester, diallyl phthalate, 3,3'-diallylbisphenol A, triallyl isocyanurate, triallyl cyanurate or vinyl pyrrolidone.

With regard to further details, reference is made to corresponding statements in DE-A-38 27 120. The bismaleimide resins known from this laid-open publication are preferably used because they have low softening temperatures and a long gelation time, which enables processing in the melt state.

In addition to the bismaleimide resins described, a large number of other BMI resins are suitable for use in the wire enamels according to the invention. The bismaleimide resins used in the wire enamels according to the invention are available, for example, under the trademark Palimid ^® S from BASF AG, for example the bismaleimide resins Palimid ^® S

410 KR, Palimid ^® S 420 KR, Palimid ^® S 430 KR, Palimid ^® S 440 KR, Palimid ^© S 450 KR and Palimid ^® S 460 KR.

Are particularly preferred Palimid ^® S 410 KR, Palimid ^® S 430 KR and Palimid ^® S 440 KR (BASF AG).

Organic solvents (component d) which are suitable for the wire enamels according to the invention and can also be used for the production of THEIC polyesters NEN, are cresolic and non-cresolic organic solvents such as cresol, phenol, glycol ethers such as methyl glycol, ethyl glycol, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol; Glycol ether esters, such as, for example, methyl glycol acetate, ethyl glycol acetate, butyl glycol acetate and 3-methoxy-n-butyl acetate; cyclic carbonates, such as propylene carbonate; cyclic esters such as γ-butyrolactone and, for example, dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone. Aromatic solvents can also be used, if appropriate in combination with the solvents mentioned. The organic solvents can be partially replaced by blending agents. Either pure solvent or pure solvent mixture or solvent with up to 40% by weight, based on the total weight of component d), of cutting agent is preferably used. Examples of suitable blending agents are xylene, solvent naphtha ^® , toluene, ethylbenzene, cumene, heavy benzene, various

Solvesso ^® and Shellsol ^® types as well as Deasof ^® . The wire enamels according to the invention contain 0.1 to 3% by weight, based on the total weight of the wire enamel, including the catalyst, of a transesterification catalyst, preferably a titanate catalyst (component c)), such as tetraalkyl titanates, for example tetraisopropyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraamyl titanate, Tetrahexyl titanate, tetraethyl titanate, tetramethyl titanate, diisopropyldibutyl titanate or aryl titanates, such as tetraphenyl titanate, tetracresyl titanate, tetraxylenyl titanate or triethanolamine titanate. Other suitable crosslinking catalysts are heavy metal salts such as lead acetate, zinc acetate, cerium compounds and organic acids such as p-toluenesulfonic acid.

The wire enamels according to the invention advantageously contain 0.2 to 5.0% by weight of a flow-promoting phenol-formaldehyde resin e), based on the total weight of the wire enamel including component e).

Suitable phenolic resins are known condensation products of phenol, substituted phenols or bisphenol A with formaldehyde. The properties of the phenolic resins depend on the type of phenol component and the aldehyde component, on the pH value set during production and on the quantitative ratio of the two reactants. According to the present invention, the phenolic resins can also be modified by incorporating other compounds in the polycondensation as well as by subsequent modification of the phenolic resin and different control of the reaction process. Of course, in addition to the condensation products with formaldehyde, those with other aldehydes can also be used.

It is furthermore advantageous that the wire enamels according to the invention contain up to 0.3% by weight of imidazole or an imidazole derivative f), based on the total weight of the wire enamels including component f). As an imidazole derivative, for example

Methylimidazole and 1,2-dimethylimidazole in question. Furthermore, it is preferred that the wire enamels contain up to 0.3% by weight of a tertiary amine g), based on the total weight of the wire enamel, including g). Suitable tertiary amines are N-methylmorpholine, N-methylpyrrolidine, N-methylpyrrole, trimethylamine, triethylamine, dimethylethanolamine, diethylmethylamine, methyldiethanolamine, ethylmethylethanolamine, Dimethylethylamine, dimethylpropylamine, dimethyl-3-hydroxy-1-propylamine, dimethylbenzylamine, dimethyl-2-hydroxy-1-propylamine, dimethyl-1-hydroxy-2-propylamine and 1,4-diazabicyclo [2.2.2. ]octane.

In addition, the wire enamels can also contain customary auxiliaries and additives in customary amounts, preferably up to 1% by weight, based on the total weight of components a) and b). As auxiliaries for the wire enamels, for example, flow-improving melamine resins or leveling agents based on polyacrylates can be used.

Wire enamels according to the invention, which a) 28 to 47% by weight of THEIC polyester, b) 4 to 10% by weight of a bismaleimide resin, c) 0.3 to 1.5% by weight lead to coatings with particularly good properties. a titanate catalyst, d) 40 to 67% by weight of organic solvents, e) 0.4 to 4.0% by weight of a phenol-formaldehyde resin, f) 0.01 to 0.2% by weight of imidazole and / or an imidazole derivative and g) 0.01 to 0.2% by weight of a tertiary amine, based on the total weight of the wire enamel, which is 100% by weight.

The present invention also relates to a method for the production of the wire enamels described above, which is characterized in that the polyester component a), the bismaleimide resin b), the catalyst c), organic solvent d), if appropriate the phenolic resin component e), if appropriate the imidazole or the imidazole derivative f) , if necessary the tertiary amine g) and further auxiliaries and additives by mixing and if necessary

Dispersing can be processed into a wire coating composition.

Preferred is a process for the preparation of the wire enamels according to the invention, which is characterized in that the THEIC-modified polyester a) is dissolved in organic solvent, the bismaleimide resin b) is added to the polyester resin solution either as a solid or in organic solution, and components c) , if applicable d), if applicable e), if applicable f) and if applicable g) and further auxiliaries and additives. Possibly. is then adjusted to the desired viscosity with additional solvent.

Modifications to this manufacturing process are also possible. For example, the THEIC polyester a) can be dissolved together with the bismaleimide resin.

The wire enamels are applied and hardened using conventional wire enamelling machines. The required lacquer film thickness is built up by at least 1 to 10 individual orders, whereby each individual lacquer application is cured without bubbles before the new lacquer application.Usual lacquering machines operate at take-off speeds of 5 to 180 m / min, depending on the binder base of the wire enamel and the thickness of the wire to be coated. Typical oven temperatures are between 300 and 550 ° C. Such Wire coating machines are known and therefore do not need to be explained in more detail here.

The wire enamels according to the invention are surprisingly stable in storage, even though they contain components as diverse as THEIC polyesters, bismaleimide resins, titanates and possibly phenolic resins. The wire enamel coatings obtained from the lacquers according to the invention after lacquering and baking have very good adhesion to copper wires, although - as will be shown below - bismaleimide resins alone, i.e. without the polyester component a), lead to non-stick coatings. Surprisingly, it was found that the wire coatings resulting from the lacquers according to the invention have an extraordinarily good property profile. For example, the wires coated with the lacquers according to the invention have excellent results in terms of thermal shock.

The invention is explained in more detail below on the basis of exemplary embodiments.

A) Production of a THEIC polyester resin

A polyester resin having a hydroxyl number of 90 to 140 mgKOH / g is prepared from 125.84 g of ethylene glycol, 294.92 g of tris-2-hydroxyethyl isocyanurate, 578.57 g of dimethyl terephthalate and 0.68 g of butyl titanate by heating to 200 ° C. This THEIC-modified polyester resin is used in the following working examples.

B) Production of a THEIC polyester lacquer

With stirring, 355.60 g of the under A) put THEIC-modified polyester in

264.80 g cresol dissolved at 150 ° C. After cooling to room temperature, 15.00 g of butyl titanate, 54.30 g of solvent naphtha and 42.62 g of a commercially available phenolic resin are added and the mixture is diluted with 214.4 g of cresol and 53.54 g of solvent naphtha.

Viscosity (23 ° C): 540 mPas

Solid (1 g, 1 h, 180 ° C): 39.8%.

C) Preparation of a bismaleimide resin varnish

253.33 g of cresol are added to 366.12 g of a bismaleimide resin based on monomeric bismaleimides and aminophenols and the mixture is stirred at room temperature until the bismaleimide resin has completely dissolved. After adding 0.62 g

1,2-dimethylimidazole, 126.78 g of solvent naphtha and 253.15 g of cresol, the lacquer is stirred for 6 hours and then filtered.

Viscosity (23 ° C): 546 mPas

Solids (1 g, 1 h, 180 ° C): 37.6%

Example 1:

37.04 g of a bismaleimide resin based on monomeric bismaleimides and aminophenols and 0.04 g of 1,2-dimethylimidazole are added to 925.89 g of the THEIC-modified polyester resin lacquer produced under B) at room temperature with stirring. After adding 27.77 g of cresol and 9.26 g of solvent naphtha, the lacquer is stirred for 6 hours and then filtered.

Viscosity (23 ° C): 640 mPas Solids (1 g, 1 h, 180 ° C): 40.6%

EXAMPLE 2 71.42 g of a bismaleimide resin based on monomeric bismaleimides and aminophenols and 0.07 g of 1,2-dimethylimidazole are added to 892.79 g of the THEIC-modified polyester resin lacquer produced under B) at room temperature with stirring. After adding 26.79 g of cresol and 8.93 g of solvent naphtha, the lacquer is stirred for 6 hours and then filtered.

Viscosity (23 ° C): 815 mPas

Solid (1 g, 1 h, 180 ° C): 41.1%

Example 3:

There are 81.80 g of a bismaleimide resin based on monomeric bismaleimides and aminophenols in

75.00 g of cresol and 24.99 g of solvent naphtha dissolved. The

The viscosity of this solution is 630 mPas at 23 ° C.

The solution is added with stirring at room temperature

Given 818.05 g of the THEIC-modified polyester lacquer produced under B). After adding 0.16 g

1,2-dimethylimidazole, the lacquer is stirred for 2 hours and then filtered.

Viscosity (23 ° C): 540 mPas

Solid (1 g, 1 h, 180 ° C): 39.6%

Example 4:

At 75 ° C., 97.61 g of a bismaleimide resin based on monomeric bismaleimides and aminophenols are dissolved in 23.76 g cresol with stirring. The viscosity this solution is 35 Pas at 23 ° C. After cooling to 50 ° C., 813.38 g of the polyester lacquer produced under B), 0.12 g 1,2-dimethylimidazole, 48.86 g cresol and 16.29 g solvent naphtha are added, the lacquer is stirred for 2 hours and then filtered .

Viscosity (23 ° C): 695 mPas

Solids (1 g, 1 h, 180 ° C): 41.2% Example 5:

139.35 g of a bismaleimide resin based on monomeric bismaleimides and aminophenols are dissolved in 33.93 g cresol at 75 ° C. with stirring; After cooling to 50 ° C, 696.77 g of the THEIC-modified polyester lacquer produced under B), 0.14 g of 1,2-dimethylimidazole, 97.37 g of cresol and 32.44 g of solvent naphtha are added. The resulting varnish is stirred for 2 hours and then filtered.

Viscosity (23 ° C): 650 mPas

Solid (1 g, 1 h, 180 ° C): 40.5%

The lacquers produced under B) and C) and in Examples 1 to 5 are lacquered on a standard wire lacquering machine.

Painting conditions: oven KLH, Aumann

Length: 4 m

Temperature: 500 ° C

Application system: pump + felt

Wire diameter: 0.71 mm

Take-off speed: 28 m / min

Number of swings: 8 Increase degree: 2 L

The coated wires are tested according to IEC 851. The results are summarized in the following table:

The wire painted with a THEIC polyester varnish (comparative example B) is characterized by very good adhesion when winding 1 x d with a pre-stretch of 25%. The disadvantage is a relatively weak thermal shock 1 x d of 155 ° C.

The bismaleimide resin varnish described under C) has no liability on copper wires.

The wire enamels according to the invention produced in Examples 1-5 have good adhesion to the copper wire which corresponds to the standard. The surface quality of the coated wires and the hardness of the coating film are in some cases above the level compared to conventional wires coated with THEIC polyesters.

The wire enamels according to the invention are characterized in particular by the fact that they are coated with them

Wires have a thermal pressure of 430 - 450 ° C and a thermal shock, 1 x d to 220ºC. The tan S steep rise is between 136ºC and 146ºC.

Claims

1. Wire enamel containing polyester based on

Tris-2-hydroxyethyl isocyanurate, organic solvents, catalysts, auxiliaries and additives, characterized in that the wire enamel a) 20 to 50% by weight of THEIC polyester, b) 2 to 35% by weight of a bismaleimide resin, c) 0 , 1 to 3% by weight of a catalyst, preferably a titanate catalyst, and d) 35 to 77% by weight of organic solvents, based on the total weight of the wire enamel, which is 100% by weight.

2. Wire enamel according to claim 1, characterized in that the wire enamel contains 0.2 to 5.0 wt .-% of a phenolic resin e), based on the total weight of the wire enamel, which is 100 wt .-%.

3. Wire enamel according to claim 1 or 2, characterized in that the wire enamel contains up to 0.3 wt .-% imidazole or an imidazole derivative f), based on the total weight of the wire enamel, which is 100 wt .-% .

4. wire enamel according to claim 1, 2 or 3, characterized in that the wire enamel up to 0.3 wt .-% of a tertiary amine g), based on the total weight of the Wire enamel, which is 100 wt .-%, contains.

5. Wire enamel according to claim 1 to 4, characterized in that the wire enamel a) 28 to 47 wt .-% of THEIC polyester, b) 4 to 10 wt .-% of a bismaleimide resin, c) 0.3 to 1.5 % By weight of a titanate catalyst, d) 40 to 67% by weight of organic solvents, e) 0.4 to 4.0% by weight of a phenol-formaldehyde resin, f) 0.01 to 0.2% by weight. % Imidazole and / or an imidazole derivative and g) 0.01 to 0.2% by weight of a tertiary amine, based on the total weight of the wire enamel, which is 100% by weight.

6. Wire enamel according to claim 1 to 5, characterized in that the polyester a) is produced from ethylene glycol, tris-2-hydroxyethyl isocyanurate and dimethyl terephthalate and has a hydroxyl number in the range from 80 to 150 mg KOH / g.

7. wire enamel according to claim 1 to 6, characterized in that the bismaleimide resin b) is produced from A) a bismaleimide of the formula

With

X = CH ₂ , 0 or SO ₂ ,

R = C ₁ ^" - C ₄ alkyl,

n = 0, 1 or 2,

B) an aminophenol of the formula

with m = 1 or 2, in the molar ratio A): B) = 2.4: 1 to 1.4: 1, where A) and B) pre-react to a prepolymer, and if appropriate C) 0 to 2% by weight, based on A) + B), of a secondary or tertiary amine or phosphine as addition catalyst,

D) 0 to 1% by weight, based on A) + B), of a polymerization inhibitor,

G) 0 to 2% by weight, based on A) + B), of a peroxide initiator, 70 to 90 mol% of A) and 30 to 60 mol% of B) being present in unreacted form and the remainder remaining Prepolymer has reacted.

8. wire enamel according to claim 1 to 6, characterized in that the bismaleimide resin b)

A) a bismaleimide,

B) a heterocyclic comonomer of the formula R-Ar-0-Het-0-Ar-R

with R = alkenyl or alkenyloxy group with 3-6

Carbon atoms, Ar = phenylene, naphthylene or

with X = O, S, SO ₂ , CO, C (R ') ₂ (R' = H, C ₁ -C ₆ alkyl, CF ₃ or phenyl) or a chemical bond, where Ar can optionally carry a hydroxyl group ,

Het heterocyclic six-membered ring selected from the group

contains.

9. wire enamel according to claim 8, characterized in that the comonomer B) is 2,6-bis (2-propenylphenoxy) pyridine.

10. The method for producing the wire enamel according to one or more of claims 1 to 9, characterized in that the THEIC-modified polyester (a), the bismaleimide resin b), the catalyst component c), organic solvent (d), optionally the Phenolic resin component e), optionally the imidazole component f), optionally the tertiary amine g) and further auxiliaries and additives can be processed to a wire coating composition by mixing and optionally dispersing.

11. A process for producing the wire enamel according to claim 10, characterized in that the polyester a) is dissolved in organic solvent, the bismaleimide resin b) is added as a solid or in organic solution to the polyester resin solution and components c), optionally d), optionally e), optionally f), optionally g) and further auxiliaries and additives are added.