DE1669045B2 - INSULATING VARNISH FOR ELECTRIC CONDUCTORS - Google Patents

Description

solvent. Such solvents are hot-water ei se XnIoIc or xylene mixes. Lackhenzine. Isophorone. Naphtha. Toluene and benzene.

The invention also relates to the use of the insulating sheet according to the invention for the production of a heat-resistant coating on an electrical conductor, which consists of a wire enamel made from a polymeric ester of Iis (2-hydroxyethyl) isocyanate and an aromatic dicarboxylic acid or a polyester. Polyimide is provided with at least 20 " _n tris- (2-hydroxyathvll-isoeyanurat in the alcohol component of the polyester and a second lacquer layer made of polyethylene terephthalate or a linear polyester or a linear polyimide or a linear polyamide-polyamide or a linear polyamide-amide .

A Drahiemail is available at ISOC or above Resistant polyester or polyimide varnish used. The polyester used to make the enamel consists of the reaction product of a polymeric ester of terephthalic acid or isophthalic acid with Tris (2-hydroxyethyl) isocyanurate. The tris (2-hydroxyethyl isocyanurate can be up to an amount of 50 percent by weight of total polyhydric alcohol by another polyhydric alcohol such as ethylene glycol, 1,4-butanediol. 1,5-pentanediol, Butene-2-diol-1.4, butii-2-diol-1.4, 2.2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-cyclohexanedimethanol. Hydroquinone-d'tf-hydroxyethyl ether, glycerine. Trimethylolethane, 1,1,1-trimethylolpropane, pentaerythritol. Dipentaerythritol, sorbitol or mannitol can be substituted. The terephthalic acid or isophthalic acid can be up to to an amount of 50 percent by weight of the acid component by another polycarboxylic acid such as for example o-phthalic anhydride, adipic acid, sebacic acid. Hemimellitic acid. Trimellitic acid, trymic acid. Succinic acid, tetrachlorophthalic anhydride or hexachlorendomethylene tetrahydrophthalic acid be replaced.

In wire enamel, the total number of hydroxyl groups in the alcohols is generally from 1 to 1. times the total number of carboxyl groups in the acids.

The polyester can also be modified by adding an organotitanate and / or polyisocyanate. Tetraalkyl titanates such as, for example, tetraisopropyl titanate, tetrabutyl titanate, tetramethyl titanate, tetrahexyl titanate or tetrapropyl titanate can be used as the titanate. The titanate is, based on the total solids content of the wire enamels, in an amount from 0,001 to 4.0 ^0, _'0 is used.

As a polyisocyanate, for example 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate. Hexamethylene diisocyanate, blocked isocyanates such as the reaction product of 3 mol of 2,4- and 2,6-tolylene diisocyanate with trimethylolpropane. which is blocked by esterification with phenol, or the cyclic trimers of 2,4- and 2,6-tolylene diisocyanate, the three free isocyanate groups of which are blocked by esterification with m-cresol, can be used. Any of the polyisocyanates and blocked isocyanates described in U.S. Patents 2,982,754 and 3,211,585 can be used. In general, the polyisocyanates make up 1 to 40 ⁿ / _{o of} the total solids content.

The polyester wire enamel can be referenced in the US patents 3 211 585 and 3 201 276 are applied to the electrical conductor in the manner described.

and all of the tris (2-hulroxyiithyl) isocyanurate-containing terephthalates and the corresponding isophthalals described in these two patents can be used as draluemail. Instead of the polyester, a polyester polyimide can also be used for the wire inlay, in which at least 20 "" and preferably at least 50 ¹ V _{n of} the alcohol component of the polyester from tris (2-hydroxyethyl) isocyanurai and the acid component from terephthalic acid. Isophthalic acid or beiizophenonedicarboxylic acid exist. The polyimide component of the molecule usually contains benzene or naphthalene rings bonded to two carbon atoms of a heterocyclic 5- to 6-membered imide ring, one of the atoms of the imide ring being made up of nitrogen and the rest of carbon.

The polyester / polyimide generally consists of the following components:

1. an aromatic or aliphatic diamine, e.g. B. methylenedianiline, oxydianiline-benzidine, 3,3'-Diaminodiphenyl, p-Phenylenediamine, 1,4-Diaminonaphthaiin, \. w-nonamethylenediamine, 4,4-diaminodipheirylether, heptamethylenediamine, Diaminodiphenyl ketone, hexamethylene diamine, ethylene diamine, diaminodiphenyl sulfone or 4,4'-Dicyc! Ohexy! Methanediamine,

2. an anhydride with three to four carboxyl groups, e.g. B. trimellitic anhydride, pyromellitic dianhydride. Benzophenone-2,3-2 ', 3'-tetracarboxylic acid dianhydride, 2,3,6,7-naphthalene dianhydride or sJ '^^' - Diphenyltetracarboxylic acid dianhydride,

3. a dibasic acid, ζ Β. Terephthalic acid, Isophthalic acid or Benzrphero; .dicarboxylic acid, and

^ _n 4. Polyhydric alcohol, which ^{consists of at least 20 0 /} n of tris (2-hydroxyethyl) isocyanurate.

The polyester / polyimide contains, based on the total amount of polyester and polyimide groups, preferably 5 to 50 °, ' _o polyimide groups. The base coat can consist of all polyester / polyimides that are described in patent application P 16 45 435.6 and are applied to the electrical conductor in the manner described there. In this case can be used as modifiers for the polyester-polyimide varnish in the-USA. Patents 3,211,585 and polyisocyanates described 2,982,754 in an amount of 1 to 25 ° / ₀ and the alkyl titanates are also described therein in an amount of 1 to 10 ⁿ / ₀ can be used. The wire enamel, whether it is made of a polyester or a polyester, polyimide, generally contains, based on the total solids content, nor 1 to 5 ° / ₀ melamine formaldehyde resin or phenol

resin such as phenol formaldehyde resin, cresol formaldehyde resin or xylenol obimaldehyde resin.

A polyethylene terephthalate is preferably used as the topcoat. It is applied from a solvent in the manner described in U.S. Patent 3,201,276. The preferred solvent consists of 30 to 50 ° / ₀ of mono chloro phenol and the balance of a cresol or a mixture of cresol and phenol. Instead of

Polyethylene terephthal can also be used as a deck kick. Polyester-polyimide-amides, straight Polyimides or other linear polymers are also used. These include, for example, the im Commercially available pyromylithimide as well as other polyimides such as the reaction product of 3,3'-diaminodiphenyl and pyromellitic anhydride, the reaction product of oxydianiline and pyromellitic anhydride, the reaction product of methylene dianiline and pyromellitic anhydride and the in the USA. Patent 3,179,634 "described polyimides, the polyester-polyimide-polyamide from ethylene glycol, Terephthalic acid, methylenedianiline and pyromellitic anhydride and the like Polyesters such as polyhexamethylene glycol terephthalate and other linear polyesters can be used.

The insulation coatings of the invention can be applied directly to electrical conductors, y but they are preferably used as a protective layer over the above-described wire and topcoats. The insulating varnishes can be used for coating copper, aluminum and silver wire and for impregnating armature and field coils for motors and for power and distribution transformers of the oil or air-cooled type where a long service life at high working temperatures is required. While the insulating varnishes described in US Pat. No. 3,080,331 are only ^{stable at temperatures of up to 150 °} C., the insulating varnishes according to the invention can be used at permanent temperatures of 180 ^° C. and above.

The invention is further illustrated by the following examples. In the present description Unless otherwise stated, all information is based on weight.

40

45

example 1

In a flask were placed 762 g of soybean oil fatty acids, 945 g of tris (2-hydroxyethyl) isocyanurate and 597 g of isophthalic acid. The mixture was heated one hour at 227 ⁰ C in the course of 3.5 hours and held at 227 to 243 ° C until an acid number of 25 had. The batch was then diluted with 2000 g of xylene to a viscosity of Z 7 at 50 ° / ₀ solids content. The alkyd resin obtained had a fatty acid content of 41 ° / _0th

To 575 g of the alkyd resin were 145 g of p-tert.Butylphenolformaldehydharz given in xylene at 50 ° / ₀ solids and an additional 80 g of xylene. The insulating varnish thus obtained had at 45 ⁰ Z ₀ Feststoffgehali a viscosity of T (550 cP).

Example 2

Into a flask were placed 1344 g of soybean oil fatty acids, 885 g of tris (2-hydroxyethyl) isocyanurate and 348 g of isophthalic acid; the temperature was increased to 249 ° C. in 3.5 hours and the batch was then held at 249 to 271 ° C. for 4.5 hours until it had an acid number of 6. The batch was then diluted with 135O g of aromatic naphtha to a viscosity of Z with a solids content of 65 ° / _0.

1500 g of p-tert-butylphenolformaldehyde resin and 342 g of aromatic naphtha were added to 15% of this alkyd resin. The insulating varnish obtained in this way had a viscosity of G at 50 ⁿ / ₀ solids.

Example 3

An insulating varnish was prepared in the same manner as in Example 1, except that an alkyd resin was made from 387 g soy fatty acids, 243 g coconut oil fatty acids, 597 g isophthalic acid and 945 g tris (2-hydroxyethyl) isocyanurate used.

Example -i

The stator of a motor was ncch with the insulating varnish. Example 1 impregnated in a dipping process. The paint was baked in an oven at 202 ° C for 1 hour to cure.

Example 5

A # 18 AWG copper wire was tied to a wire enamel and then to a Polyethylene terephthalate topcoat painted. The wire email was a mix

a) 86 parts of polyester from 4400 parts of tris (2-hydroxyethyl) isocyanurate, 481 parts of ethylene glycol and 5019 parts of dimethyl terephthalate,

b) 5 parts of cyclic trimers of 2,4- and 2,6-tolylene diisocyanate, whose three free isocyanate groups are blocked with m-cresol.

c) 5 parts of tetraisopropyl titanate and

d) 5 parts of 3440 parts of m-p-cresol formaldehyde resin m-p-CresoI and 1962 parts 37% / (, igem aqueous Formaldehyde.

The wire pre-lacquered in this way was passed twice through the insulating lacquer produced according to Example 1 drawn and hardened for 1 hour at 20? ° C after each immersion. The one with the three coatings Wire was tested by AIEE Test No. 57 (twisted in pairs) with the following results became:

TemperaUii, ° C Failure at 1000 volts after
hours 280
260
240
222 268
598
798
3557

60 If you extrapolate these values to 188 ° C, you get a time of 20,000 hours. This shows that class H can be achieved with the lacquer system consisting of the fatty acid alkyd insulating lacquer, polyethylene terephthalate top lacquer and wire enamel. The product exhibited improved bond strength and less weight loss than a conventional one with wire enamel and

Top coat provided wire, which is not yet coated with a fatty acid-modified alkyd resin varnish was.

Example 6

Example 5 was repeated with the insulating varnish according to Example 2. A class H enamelled wire was used obtain.

Example 7

When using the insulating varnish according to Example 2 on a wire provided with wire enamel and top varnish based on polyethylene terephthalate, good results were also obtained in the scorch test. In this test, the coated wire is twisted in pairs, dipped into the insulating varnish and ^{cured at 205 °} C. for 1 hour. A current of 33 A is then passed through for 4 minutes and the breakdown voltage of the system is checked. The following results, which are given in kV final voltage, were obtained in this braising test. Pre-painting according to
Example 5

Pre-painting from polyester-polyimide wire enamel with polyethylene terephthalate topcoat

Pre-painting from polyester-polyimide wire enamel

Without insulating varnish

4.98

0.77 0.75

With insulating varnish

8.6

2.38 1.16

From this it can be seen that the insulating varnish significantly improves the base coat / top coat system.

The polyester polyimide consists of trimellitic anhydride, methylenedianiline, dimethyl terephthalate, Ethylene glycol and tris (2-hydroxyethyl) isocyanura1

»O and is in the patent application P 16 45 435.6 (example 9). The mixture used in the wire enamel consisted of 210 parts of the polyester-polyimide, 8 parts of tetraisopropyl titanate, 22 parts of component b) of Example 5 and 10 parts

»5 phenol formaldehyde resin.

»9 517/30;

Claims (3)

gives excellent mechanical strength with thermal resistance. Claims: The subject of the invention is therefore an insulating varnish for bare or already coated electrical conductors 5 based on phenol-formaldehyde resins and 1. Insulating varnish for bare or already coated polyesters made from terephthalic acid. Ethylene glycol and electrical conductors based on phenol tris (2-hydroxyethyl) isocyanurate. dissolved in common formaldehyde resins and polyesters made from terephthalic lacquer solvents, which is characterized by acid. Athylglyco! and Tns- (2-hydro. \ yäthyl) -iso- that it acts as a binder with an unsaturated higher eyanurate. dissolved in conventional paint solvents, io fatty acids modified tris (2-hydroxyethyl) iso, characterized in that it is a cyanurate isophthalate and or terephthalate, and in the case of the binder a higher fatty acid containing up to 50 percent by weight of tris (2-hydroxyethyl ) Acids modified tris (2-hydroxyethyl) isocyanurate by another polyvalent alkocyanurate isophthalate and or terephthalate. in hol can be replaced with a fatty acid content of which up to 50 percent by weight of the tris (2-hy- 15 20 to 65 ° ' _o and based on the total amount of hydroxyethyl) isocyanurate by another more alkyd resin and phenol-formaldehyde resin, 80 to 15 percent alcohol can be replaced, with an oil-soluble phenol-formaldehyde fatty acid content of 20 to 65 ⁰ Z ₀ and. based on resin. The total amount of alkyd resin and phenol is preferably contained in the insulating varnish in the alkyd resin formaldehyde resin, 80 to 15 weight percent of a 20 unsaturated higher fatty acid fatty acids semi-oil soluble Contains phenol-formaldehyde resin. drying oils, preferably in an amount of 2. Insulating varnish according to claim 1, characterized in that it is 30 to 55 percent by weight, based on the alkyd resin, that it is in the alkyd resin as unsaturated. B. at a higher fatty acids semi-drying oils, fatty acid content of 55 ° / _0, can be used instead of the Isophthalvorzugsweise in an amount of 30 to 55 weight acid 25 the otherwise less preferred Terephthalprozent, based on the alkyd resin contains. acid can be used. 3. Insulating varnish according to claim 2, characterized in that the tris (2-hydroxyäthyI) isocyanurate can as drawn, that the fatty acids of semi-drying oils says partly through another polyvalent alcohol-soy fatty acids and that the phenols in the phenol hol, z. B. glycerol or pentaerythritol, are replaced, formaldehyde resin in the o- or p-position is alkyl 3 ", however, when replacing part of the tris (2-hydroxy-substituted Phenols or bis (p-hydroxyphenyl) - ethyl) isocyanurate by another polyvalent one are propane. Alcohol somewhat adversely affects the improved heat resistance of the laquer according to the invention. Soybean oil, 35 cottonseed oil, corn oil, whale oil, safflower oil or Sunflower oil fatty acids or the somewhat less preferred linseed oil, tung oil, oiticica oil or perilla oil fatty acids be used. Some of the drying or semi-drying fatty acids can also through The invention relates to modified alkyd resins, non-drying fatty acids such as coconut oil, olive oil, ! Retaining insulating varnish for electrical conductors for connection. Replaced peanut oil or rapeseed oil sulfide manoeuvrable as heat-resistant coatings on one with. Wire enameled electrical conductor. If part of the tris (2-hydroxyethyl) isocyanurate From the USA.-Patent 3,080,331 are insulating is replaced by glycerin, this does not need as Jacket made of oil-modified glyceryl isophthalate and 45 such to be added, but can: / in the form an oil-soluble phenol-formaldehyde resin is known. an oil such as soybean oil. Corn oil, linseed oil Although such lacquers are well used or the like for many purposes. In this case it brings bar, they cannot be used where naturally the oil is also part of the fatty acid products required which component in the AIEE test or the entire fatty acid component No. 57 are resistant at 180 ° C (products of the class 50 with a. fication H). From the Belgian patent specification 628 506 As already mentioned above, the inven- are already insulating varnishes with a content of polyisocyanate insulating varnishes in addition to the one with a higher cyanate and or alkyl titanate-modified polymers ren fatty acid-modified tris (2-hydroxyethyl) isoatis Tris (2-hydroxyethyl) isocyanates, which may contain cyanurate polyester or an oil-soluble phenol form Part can be replaced by polyols, and 55 aldehyde resin. For the production of this phenol iso- or terephthalic acid, the phenols that may be preferred for formaldehyde resins are in o- or Can also be partly replaced by other acids, be p-position alkyl-substituted phenols, 2,2-bis- (p-hycane. These lacquers are used as wire enamel on a droxyphcnyl) -propane and 4,4-bis- (p-hydroxyphenyl) -electric Conductors are applied and have excellent propane. Excellent thermal properties, but not for all demands ^. As examples of suitable phenols for the production of sufficient mechanical properties. The resin can be p-tert-butylphenol, p-tert-amyl invention is based on the object of a new phenol, p-tert-octylphenol, p-penylphenol, o-tert.Bu insulating varnish with a content of oil-modified tylphenol and to propose the alkyd resin in US Pat. No. 1,800,296, which is one of the thermally described phenols. It can withstand all long-term stresses of 180 ° C and can be used as Iso- ⁶ S in US Pat.
wire enamel and a Polyäthylenterephthalatdeck- The insulating varnishes according to the invention contain in addition lacquered electrical conductor this one outstanding resin components the common lacquer