DE1261260B - Process for the production of storage-stable, heat-curing electrical insulating paints - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. σ .:

Number: File number: Registration date: Display day:

C09d

German class: 22h-3

1 261260
B61915IVc / 22h
March 28, 1961
15th February 1968

Very different, often contradicting requirements are placed on impregnating varnishes for electrical insulation purposes posed. The impregnating varnishes produced in a known manner are therefore each given a whole, depending on the structure certain scope. For example, you need impregnating varnishes with mainly plasticizing agents Ingredients such as oil-modified synthetic resins or polyester resins, long drying times or high baking temperatures. Impregnating varnishes with higher proportions of thermosetting phenol-formaldehyde or amine-formaldehyde resins can be cured in a relatively short time, but they can cannot be used to impregnate solvent-sensitive enameled wires, as their manufacture causes a requires a larger proportion of strong solvents, especially alcohols. In addition, such varnishes stick more or less strong formaldehyde odor, which in many cases makes processing difficult or impossible. Phenolic resin combinations also often have inadequate tracking resistance. With Lacquers made from amine-formaldehyde resins have a strong tendency to be stoved in a deep layer solvent entrapment and blistering. Paints based on urea-formaldehyde resins result Insufficient resistance, for example when exposed to moisture or constant heat.

It is also known to use masked polyisocyanates for the production of electrical insulating impregnating varnishes, their isocyanate groups at higher temperatures with elimination of a blocking agent are released and then under polyaddition with compounds containing several reactive hydrogen atoms can deliver networked products. The use of such mixtures is because of limited to a few special areas of application due to the high costs and high baking temperatures. Above all, such varnishes are bound to a solvent build-up that allows them to be soaked most magnet wire types unusable.

The invention relates to a process for the production of storage-stable, thermosetting electrical insulating impregnating paints based on compounds containing blocked isocyanate groups and reactive hydrogen atoms at the same time, as well as organic solvents, which is characterized in that produced in a manner known per se and having on average more than two reactive hydrogen atoms and with fatty acid-modified polyhydroxy compounds, wherein the fatty acid content of these compounds is 25 to 90% at a temperature up to about 12O ⁰ C, in the presence of the solvent, simultaneously with at least a process for producing storage-stable thermosetting Elektroisoliertränklacken

Applicant:

Dr. Beck & Co. G. m. B. H.,

2000 Hamburg 28, Eiselensweg

Named as inventor:

Dr. Hans-Joachim Beck,

Dr. Gerhard Neubert, 2000 Hamburg

equimolar amount of a diisocyanate and a monofunctional blocking agent are implemented, wherein the amount of blocking agent should be about 1 mole per mole of diisocyanate.

From the German Auslegeschrift 1 054 707 a method is already known, according to which polyester, Polyester amides and polyethers that have blocked isocyanate groups by reacting one linear polyesters, polyesteramides or polyethers with terminal hydroxyl groups with an excess a diisocyanate in the presence of a monofunctional blocking agent, such as. B. phenol, getting produced. However, this method uses a relatively small amount of blocking agent used, namely less than 0.5 mole per mole of diisocyanate. In contrast to the invention Lacquers, these known lacquers contain free isocyanate groups, which increases their shelf life leaves much to be desired, as they are affected by moisture, and the further disadvantage is that no solvents containing hydroxyl groups can be used.

British Patent 822 547 also describes polyesters containing blocked isocyanate groups. In their preparation, the reaction between a polyester containing hydroxyl groups and a diisocyanate after a certain reaction time, for example after 24 hours at room temperature, interrupted by a blocking agent before gelation occurs. However, this procedure requires to To achieve adequate storage stability, a large excess of blocking agent, namely from 1 to 5 times the total weight of polyester and diisocyanate. That as a solvent residual, excess blocking agent makes such reaction products for electrical insulating impregnation paints unusable.

809 508/339

3 4

The German patent also relates to the polyhydroxy compounds carried out by 895 527 on the implementation of polyfunctional den can. It was particularly surprising for him Isocyanates, in which a person skilled in the art that, according to the invention, is good in a first step part of the isocyanate groups with a blocking shelf life in addition to the complete crosslinking agent is modified, with polyhydroxy compounds, 5 ting when stoving with one in a single in particular polyesters made from polyfunctional acids. and polyfunctional alcohols. This procedure can be enough.

Although it also leads to cleavage groups, for the production of electrical insulating impregnating lacquers

the polyhydroxy compounds, it must, however, in two of the process according to the invention can even be of be carried out in separate stages. In contrast, fatty acid esters and polyesters containing hydroxyl groups is the production of the proalcohols and / or diisocyanates according to the invention with symmetrical products can be assumed due to the fatty acid modification in a molecular structure without a single stage possible. the usability of the paints for impregnation purposes

Due to the German Auslegesehriften 1 049 575 pregnant thixotropy occurs, and 1,072,387 it is also known that in the polyhydroxy compound reaction modified with fatty acid of hydroxyl-containing fatty acids, which are useful for the practice of the invention Esters with approximately equivalent amounts of Diiso process are suitable, for. B. fatty acid esters polycyanates or blocked diisocyanates of thixotropic alcohols, reaction products of epoxy reaction products arise when the contained resins with fatty acids and preferably with fat · ' Polyalcohol and / or the diisocyanate is a symmetrically acid-modified polyester.

have Irish molecular structure. Thixotropic lacquers The manufacture of fatty acid modified polyesters

However, electrical windings can be impregnated in a known manner by esterification of poly useful. alcohols with polybasic carboxylic acids and fatty

From the German patent specification 970 932, aerosols or naturally pre-hardening ones by transesterification Surface lacquers based on tall oil grease oils with a polyalcohol and acidic acids and polyalcohols known, with an esterification following 2 mol with a polyvalent the hydroxyl esters, which are less than a free hydroxyl carboxylic acid or its anhydride, group per molecule, always less than 1 mole Fatty acids are saturated or unsaturated

Diisocyanate can be used. The amount of saturated C ₈ -C ₂₂ -carboxylic acids in consideration, as they are set diisocyanate, may not be more than 3 ° z. B. from naturally occurring triglycerides such as they are used to saturate the still free hydroxyl gains, or preferably tall oil fatty acid. groups is required, otherwise gelation can also occur from drying or non-drying. In contrast to this, it is possible to start from the oils, for example from the process according to the invention a thermally linseed oil, soybean oil, castor oil or coconut oil, curable electrical insulating varnish to be produced, with the polyalcohols of which glycerol, trimethylol storage no crosslinking reactions occur and propane, pentaerythritol, dipentaerythritol called. No gelation takes place. the latter are due to the higher continuous heat

In the Belgian patent 560 481 of the resistance to invention and the excellent through-drying is also the implementation of hydroxylation properties of the paints made from them groups containing residues of higher molecular weight fat 40 are preferred. Bicic acids can also be used in smaller quantities containing ester mixtures, more than one hydric alcohols, for example glycol, are also used Isocyanate group containing higher molecular weight Re-.

action products and to the former polymerizable examples of polybasic carboxylic acids with which

monomeric, unsaturated, hydroxyl group-free versions of the fatty acid-modified polyesters are produced Bonds in the presence of polymerization catalysts are phthalic acid, maleic acid and adipinic acid described; however, after this they become acidic. Isophthalic acid and terephthalic acid processes did not know lacquers, but rather the solvent-free, due to the higher heat resistance, obtained from unsaturated polyester resins. from manufactured paints preferred. By using In addition, in this known process of dimerized and trimerized fatty acids no detachable blocking agents for the 5 "can produce particularly elastic paint films put diisocyanates to be used, as in the case of the inven- tion.

proper procedure is required. In the context of the invention, mixed

The advantage of the method according to the invention is gene of oils, eg. B. castor oil and soybean oil, mixtures once that fatty acid-modified polyhydroxy oils and fatty acids, e.g. B. castor oil and tall oil compounds for the production of one-component fatty acid, mixtures of polyalcohols, e.g. B. Ethy-polyurethane resin-Elektroisoliertränklacken used lenglycol and pentaerythritol, as well as mixtures of which can be mixed with white spirit and similar polybasic carboxylic acids, e.g. B. Isophthalic acid and mild solvents are prepared and such a multi- terephthalic acid can be used, multiple application possibilities also for solution- The oleic or fatty acid content of the for the invention

Allow medium-sensitive enameled wires. The grease 60 proper method suitable polyhydroxy compounds Polyhydroxyverbindunsäuremodifizierten forthcoming, gene is preferably ⁰ to 80 J _0, Trains t polyester prevent be about 25 in the simultaneous environmental until 90%> 45th

to accelerate the transesterification reaction

early gelation, so that the paints used in accordance with the invention for the production of the fatty acid-modified polyhydroxy coatings will have a particularly good shelf life. Only added when baking with higher and / or triethanolamine. As a metal salt, free isocyanate groups form back, especially calcium naphthenate in concentrations so that a complete crosslinking reaction of about 5 × 10 ~ ^B to 10 ~ ⁷ percent by weight calcium,

based on the oil content of the reaction mixture, linking two molecules of the polyhydroxy fatty acid

suitable. Larger amounts can react with the subsequent reaction, occurs when using a very high-

ßenden esterification with polybasic carboxylic acids molecular polyhydroxy fatty acid esters already during

a permanent cloudiness in the reaction mixture due to the production of the blocked isocyanate groups

call. The addition of triethanolamine is said to be partially crosslinking the compound containing up to 5, i. E.

V ₅ moles per mole of oil, preferably Vioo to V ₁₀ moles, of swelling. For making in the heat

wear. The reaction products, which crosslink to a greater extent in the process according to the invention, are

Compared to the usual catalysts used, advantageously of low molecular weight or low-

Chen transesterification catalysts for mixtures of viscous polyhydroxy fatty acid esters. Viscosities

oils and polyalcohols, such as. B. metal oxides, the io from about 1000 to 500,000 cP, preferably between

Advantage that they cannot be filtered out of the reac- 3000 and 100000 cP, at 20 ⁰ C have in general

tion product must be removed again. They claim proven suitable.

simultaneously accelerate the crosslinking reaction of the The blocking agent is expediently in men-

lacquers produced with it, without their storage stocks of 1 mole per mole of diisocyanate used. In the event of

This has a significant impact on the ability of the product, and it has a higher viscosity

their film properties are favorable. Reaction products. Excess blocking agent

As a diisocyanate, for example, toluene can reduce the curing rate of the

diisocyanate, hexamethylene diisocyanate or 4,4'-di- lacquers made from them and also facilitates

phenylmethane diisocyanate can be used. the emergence of a loss of diisocyanate in

Baking suitable for the method according to the invention.

monofunctional blocking agents are those that are used to obtain the electrical insulation impregnation paint

react faster with the diisocyanate than the fat-free reaction products with

acid-modified polyhydroxy compounds and the appropriate solvents. For this you can

at temperatures below 180 ^° C., preferably under inert solvents, such solvents are also used

14O ⁰ C, are split off again. Examples of this are 25 which are reactive towards isocyanate groups,

are cresols or especially phenol. such as B. Alcohols, if they are due to their volatility

The reaction of the polyhydroxy fatty acid ester does not interfere with the stoving process. An addition to the diisocyanate and the monofunctional Blök- polar solvents such as alcohols, ketones or kierungsmittel is in various ways at tem- ester has a strong, the viscosity-lowering effect, temperatures up to 12O ⁰ C executed. The paints produced according to the invention have good storage stability with individual reactants at various normal temperatures. Their sequence will be mixed together. However, pre-curing at temperatures of 12O ⁰ C and lower term crosslinking reactions largely exclude possible in a relatively short time. Compared to phenols and the reaction more controllable by formaldehyde and amine-formaldehyde resin combinations, the blocking agent is advantageous. The varnishes produced according to the invention have the essential advantage over the fatty acid-modified polyhydroxy that they are slower to react after they have been bonded. Are applied from impregnations, in deep layers and for the same reason, it is useful to cool the first reaction phase to a much lesser extent during the narrow cavities and to include at least one solvent than the known impregnation part of the varnish for producing the electrical insulating impregnation varnish 40 and therefore less tend to form bubbles, also use required solvents. For the practical application of the way one leaves the significant freshly prepared solution of a fatty acid modifying progress to a lacquer produced according to the invention with cooling to 0 to 20 ° C, the stoving process is greatly increased by using an antene polyhydroxy compound and a diisocyanate Can shorten, slowly run in a solution of the blocking agent. 45 Particular advantages also result from the fact that the reaction is then expediently carried out at an increased temperature that the solvent build-up can be set at will. Although the application can. For example, lacquers can be produced, higher temperatures result in a high reaction rate, which results in a minimum of physiological harmfulness and dizziness, but too high temperatures lead to odor nuisance and solvent sensitivity does not dissolve an undesired premature start of the lacquer wire,
wetting of the reaction products. Temperatures between The properties of the 50 and 100 ° C. produced according to the invention have generally proven to be suitable here depending on the structure. the fatty acid-modified polyhydroxy

The conversion between the polyhydroxy fatty acid compound, the content of converted diisocyanate ester, the diisocyanate and the monofunctional 55 and the degree of crosslinking. The cured lacquer blocking agent must have good to excellent creepage conditions under practically anhydrous films and, _{if carried out in inert solvents, must be of the T 4} to T _{5 level} according to DIN 53480. Appropriate inert solvents are suitable for this.

especially aliphatic, cycloaliphatic and aromatic paints produced according to the invention can

table hydrocarbons; However, additional paint raw materials can also be added through

Ketones, esters or chlorinated hydrocarbons use their properties in one direction or another

be det. to be changed. An example of this are phenol

Heat-crosslinking reaction formaldehyde, urea-formaldehyde, melamine molded products are obtained, if you have more than 1 mol of diisocyanate per aldehyde resins, oil-modified alkyd resins or eth-MoI Fatty acid-modified polyhydroxy compound called one-65 oxylin resins. It is also possible by adding. The degree of crosslinking is determined by the relative rate of paint additives, for example siccatives, Excess amount of diisocyanate given. Because that will improve the film properties or the paints too A certain amount of diisocyanate is pigmented or colored.

I 261 260

example 1

637 parts by weight of soybean oil, 277 parts by weight of castor oil and 245 parts by weight of pentaerythritol are under Addition of 2 parts by weight of triethanolamine for 2 hours at 250 ° C and then transesterified at 190 to 230 ° C with 116 parts by weight of isophthalic acid to an acid number of about 0.5 and a viscosity of 6000 cP esterified.

8th
Example 4

820 parts by weight of coconut oil and 408 parts by weight of pentaerythritol are added with 0.5 weight-5 share calcium naphthenate transesterified at 250 ° C for 3 hours. After adding 62 parts by weight of ethylene glycol and 296 parts by weight of phthalic anhydride, the reaction mixture is esterified at 170 to 220 ° C, to an acid number of about 3 and a viscous

In the 50% solution of the condensation product io did of about 5000OcP is reached. in white spirit solvent naphtha (1: 1) at 20 ° C in the prepared fresh at 20 ° C / 50 ° ₀ solution

a 50 ° / oig ^e solution of 400 parts by weight of tolylene the condensation product with 556 parts by weight of diisocyanate in white spirit solvent naphtha (1: 1) overall tolylene diisocyanate in solvent naphtha will be slow and immediately thereafter a 50 ° / _o by weight solution of a 50 ° / _o ige solution of 300 parts by weight of phenol 227 parts by weight of cresol DAB IV M in solvent 15 in solvent naphtha was added. Then the

Solution at 7O ⁰ C heated until no free isocyanate groups and no free phenol can be detected. A varnish is obtained which, at stoving temperatures above 110 ° C., is relatively light and hard

naphtha was added dropwise within 1 hour. The reaction is completed by heating at 80 ° C. for 8 hours Out at the end, with an increase in viscosity occurs.

The varnish solution, which is stable at room temperature, produces tough, elastic, Well-drying coatings in a deep layer. It contains no free isocyanate groups and none unbound cresol more and can be mixed with other resins, e.g. B. phenol-formaldehyde resins, and any Solvents, e.g. B. butanol, are mixed.

Example 2

Film results.

Example 5

267 parts by weight of linseed oil and 184 parts by weight of glycerin are transesterified at 250 ° C. for 7 hours. After adding 163 parts by weight of phthalic anhydride, the reaction mixture is heated to 180.degree. To 220.degree esterified until it has an acid number of 2 and a viscosity of 100,000 cP.

In the 70 ° / ige mixture freshly prepared at 20 ° C. 637 parts by weight of soybean oil, 277 parts by weight of castor oil 30 of the condensation product with 195 parts by weight and 272 parts by weight of pentaerythritol are gradually added to toluylene diisocyanate in solvent naphtha with 8 parts by weight of triethanolamine for 2 hours
transesterified at 250 ⁰ C and after addition of 133 parts by weight of isophthalic acid at 190 to 23O ⁰ C up to
an acid number of 2 and a viscosity of

esterified by I and a viscosity of 12,000 cP.

In the freshly prepared at 20 ⁰ C 50% ig ^e mixture of the condensation product with 487 parts by weight of tolylene diisocyanate in mineral spirits is added in mineral spirits, a 50% solution of 244 parts by weight of phenol. The reaction mixture is then heated to 100 ° C. for 2 hours.

The paint, which is further diluted with solvent naphtha, for example, is free from phenol and isocyanate groups and hardens at 120 ° C and produces extremely tough, hard and solvent-resistant coatings.

Example 3

637 parts by weight of soybean oil, 277 parts by weight of castor oil and 218 parts by weight of pentaerythritol are ^{transesterified with the addition of 2 g of triethanolamine and 0.05 g of calcium naphthenate for 2 hours at 25O 0} C and after the addition of 560 parts by weight of a mixture of 75% dimeric, 22% trimeric and 3% monomeric C ₁₈ fatty acids esterified at 190 to 230 ° C until the condensation product has an acid number of 1 and a viscosity of 7500 cP.

The freshly blended at 20 ⁰ C 50% solution lent a 70% strength solution of ^e 105 parts by weight of phenol in the solvent naphtha was added. The reaction mixture is then ^{heated to 90 °} C. and kept at this temperature until free isocyanate groups can no longer be detected. Additional solvent, for example solvent naphtha, is added to lower the viscosity.

The paint cured at 12O ⁰ C and results in a tough and hard film.

Example 6

In a freshly prepared at 20 ° C 50% mixture of a condensation product with an acid number of 5 and a viscosity of 20,000 cP, made from 840 parts by weight of tall oil fatty acid, 134 parts by weight of trimethylolpropane, 245 parts by weight of pentaerythritol and 193 parts by weight of isophthalic acid, with 313 parts by weight toluene diisocyanate in white spirit solvent naphtha (1: 1) is slowly added a 50% strength solution ^e of 169 parts by weight of phenol in white spirit solvent naphtha: added (1: 1). The reaction mixture is then ^{heated to 70 °} C. and kept at this temperature for 8 hours.

To obtain a varnish, the above 110 ⁰ C cures to a tough, elastic film and shows deep layers, even at baking temperatures of 180 ° C, no solvent inclusions and no blistering. This varnish is extremely suitable

Example 7

of the condensation product with 313 parts by weight 60 for soaking windings of electrical equipment and toluylene diisocyanate in white spirit — solvent naphtha machines. (1: 1) is slowly ig ^e solution of 169 parts by weight of phenol in the solvent naphtha was added 50%. At-

In a 50% mixture freshly made at 20 ° C of a condensation product with an acid number of 2 and a viscosity of 5000 cP from 1008 parts by weight of peanut oil fatty acid, 272 parts by weight of pentaerythritol and 100 parts by weight of Iso

closing the reaction mixture is kept for several hours at 8O ⁰ C.

The varnish, which is free of phenol and isocyanate groups, is particularly elastic when stoved above 110 ° C Movies.

phthalic acid, with 348 parts by weight of tolylene diisocyanate in white spirit, a 50% solution of 216 parts by weight of cresol DAB IV M in white spirit is slowly added. Then the reaction mixture is heated to 8O ⁰ C and kept at this temperature until no free isocyanate groups are no longer detectable. This lacquer hardens at temperatures above 110 ^° C.

Claims (2)

Patent claims: 1. Process for the production of storage-stable, thermosetting electrical insulating impregnating varnishes based on simultaneously blocked isocyanate groups and reactive hydrogen atoms containing compounds and organic solvents, characterized in that that produced in a manner known per se, on average more than two reactive Polyhydroxy compounds containing hydrogen atoms and modified with fatty acids, the fatty acid content of these compounds being from 25 to 90% at a temperature up to about 10 120 ^° C., in the presence of the solvent, can be reacted simultaneously with at least an equimolar amount of a diisocyanate and a monofunctional blocking agent, the amount of the blocking agent being about 1 mol per mol of diisocyanate. 2. The method according to claim 1, characterized in that the fatty acid-modified polyhydroxy compounds polyesters modified with fatty acids can be used. Considered publications:
German patents No. 946 173, 970 932,
527; German Auslegeschriften Nos. 1054 707, 1049 575, 072 387, 1 058 666, 1 073 135;
Belgian Patent No. 560,481;
British Patent No. 822,547;
U.S. Patent Nos. 2,884,390, 2,870,102;
ao Wagner - Sarx, Lackkunstharze, 1950, pp. 74/75; Angewandte Chemie, 1947, pp. 263-265;
Bayer Kunststoffe, 1955, p. 33. S09 508/339 2.68 © Bundesdruckerei Berlin