DE1036426B - Process for the production of stoving enamels - Google Patents

Description

Process for the production of stoving enamels by mixed condensation It is known that polyvalent carbonic acid with polyhydric alcohols and amines is obtained Esteramide resins, which are used as basic materials for paints and similar uses are in demand. They are produced by heating the components together in the resin kettle to temperatures above 200 ° C. The removal of the The water of reaction causes particular difficulties.

Esteramidharze with rubber-like properties are obtained according to USA. Patent 2,281,415 by processing alkylsubstituierterGlykole. For this purpose, an amine, e.g. B. hexamethylenediamine, with an alkyl substituted dihydric alcohol, e.g. B. 2,2-dimethyl-propanediol, sebacic acid and water initially heated to 150 ° C for 4 hours, then a further 4 hours to 200 ° C and then 36 hours to 200 to 250 ° C under vacuum. The production of such Esteramidha.rze accordingly requires considerable effort. The ester amide resins obtained are soluble in organic solvents and are therefore also suitable for paint purposes.

It has now been found that excellent stoving enamels can be obtained on the basis obtained from ester amide resins by using di- or polybasic carboxylic acids or their mixtures with less than the equivalent amount of one and or or polyhydric alcohols esterified and the acidic esters with amines or amine mixtures neutralized, with the resulting spreadable mass, if necessary or, after neutralization, further diluted with diluents, especially water.

The spreadable mass does not initially contain any amide compounds. These arise only after spreading during baking. The addition of a diluent has a beneficial effect on the neutralization, but you can use the diluent also add subsequently.

The advantages of the method according to the invention over production of paints made from finished ester amide resins are obvious. A long one is omitted Heating the components to high temperatures and the laborious work below Vacuum to remove the remaining amounts of water. Rather, the condensation takes place simply by the fact that the reaction mass passed as paint and the resulting The paint film is heated, the water of reaction escaping very quickly.

Another notable advantage of the method of the invention can be seen in the fact that you do without organic solvents and instead only use water as a solvent. can. This saves the expensive ones and generally harmful and flammable organic solvents.

As polybasic carboxylic acids, saturated and unsaturated, aliphatic as well as aromatic or hydroaromatic mononuclear and also polynuclear Acids are used. Suitable acids are e.g. B. fumaric acid, maleic acid, succinic acid, Glutaric acid, adipic acid, pimelic acid, sebacic acid, phthalic acid, trimellitic acid, Trimesic acid, mellophanic acid, pentacarboxylic acid, mellitic acid etc. instead of the Acids can also be used with their anhydrides. It can still be monobasic Acids are added, e.g. B. Fatty acids of a saturated and unsaturated nature. In addition, resin acids, e.g. B. abietic acid, suitable for condensation.

Particularly suitable as the acid component is that of benzene carboxylic acids in particular existing acid mixture, which is obtained by oxidation of fuels, preferably Coal is obtained because the fuels are increased with nitric acid Pressure and treated at elevated temperature. From this raw acid: let it mix according to some not yet part of the state of the art. Procedure, before mainly by extraction and sublimation mixtures of ben, zoltri-, -tetra- and. -pentacarboxylic acid, which also contain aliphatic carboxylic acid in minor quantities.

When standing for a long time, some show combinations of esters and amines of the type according to the invention have a low tendency to settle and become cloudy. It it was found that with increasing number of components in acidic, alcoholic and basic components this tendency can be suppressed. It is based on this on the solubilizing effect of the individual components on one another. This also explains the preferred suitability of <for the oxidation of fuels acid mixtures obtained for the process of the invention.

For the esterification of the acids are the various saturated and unsaturated monofunctional and non-functional alcohols as well as with special Advantage of their mixtures can be used. Monofunctional alcohols are mainly used here the inner «, calibration. while the multifunctional alcohols form a network and thus lead to hardening.

It goes without saying that monofunctional alcohols are used alone no networking at all. In this case, according to the invention, this is only achieved by adding a multifunctional amine and heating brought about.

Suitable polyhydric alcohols are, for. B. ethylene glycol, di-, tri- and tetraethylene glycol, propyl glycol, butylene glycol, pinacon, glycerine, trimethylol propane, Pentaerythritol, also those of aromatic and hydroaromatic character, e.g. B. Phtlialylalkohole etc. As monohydric alcohols are the known saturated and unsaturated normal and branched chain alcohols of any chain length usable.

Tcilester can also be made from polyhydric alcohols with still free Use hydroxyl groups, #vie z. B.'mono- and diglycerides of saturated or unsaturated fatty acids.

Mono- or polybasic amines and also aminocarboxylic acids can be used as amines use, such as B. aminocaprolactam. It can be both aliphatic and aromatic Amines are used. Suitable amines are e.g. B. ethylenediamine, propylenediamine, Amylenediamine, hexamethylenediamine, also butylamine, amylamine, octylamine, duodecylamine, Aniline, p-phenylenediamine. The monobasic amines produce an internal one when heated Plasticization, <lie polybasic lead to crosslinking. It is not necessary, add exactly equivalent amounts of amines, sometimes a small excess of amines for further processing, e.g. B. with varnishes for the course of the spread, cheaper.

It has already been mentioned that one is involved in the preparation of the starting mixtures such alcohols can be used as alcoholic components, those with a fatty acid are partially esterified. It is also possible to use neutralization products from fatty acids and add amines. These dissolve homogeneously in the one produced according to the method Geinisch on.

The acidic esters are produced in a manner known per se, however, care must be taken that no products which are too viscous are obtained. The acidic esters thus obtained are mixed with amines, which are either solid or liquid or mixed in as a solution. Salt formation occurs, which is reflected in the occurrence of heat and water formation. The. Further processing of the so produced Mixing to the finished resin happens after application on all kinds of surfaces and baking the paint films. The mixtures must always be heated to higher levels Temperatures, preferably above 180 ° C., with the release of the water and further condensation hardened. The resins sometimes darken when heated noticeable. This can be reduced by baking in a nitrogen atmosphere or avoided.

As already mentioned, the ratio of alcohol to amine can be changed vary within wide limits. The most favorable ratio depends on nature the acid mixtures used and the alcohols used for esterification. It is also not absolutely necessary, exactly equivalent to the remaining acid number Use amounts of amines. Rather, one kaiiii only a part of the rest Neutralize carboxyl groups and esterify the rest with any alcohol that is still present.

The addition of the amine bases to the acidic ester leads to salt formation and causes a certain hydrophilicity of the entire system, i. i.e., the mixture is Miscible with certain amounts of water. In this way, you can make spreadable masses obtain. In cases where water alone is insufficient as a solvent, are you still water-soluble diluents, such as. B. ethanol, propanol, acetone, Diacetone alcohol, too.

Sometimes it is also useful to maintain the state of solution to adjust the resin solution slightly alkaline, which can be achieved by a small excess to amine via the chemical equivalence point or by an additional base, such as z. B. ammonia, can achieve. It is even possible. the Ainine partially replace with ammonia. When stoving the salt mixtures or their aqueous Solutions, the amnion salts initially present in the paint film are converted into stable nitrogen compounds above.

In any case, it is up to you to choose the proportions so that spreadable masses arise whose consistency by adding water and or or organic solvents or the required by increasing the temperature Processing conditions can be adapted.

Example 1 100 parts of pyroinellitic anhydride are in 825 parts Acetone dissolved and with 28.5 parts of ethylene glycol at the boiling point of acetone so far esterified as possible. The acetone is evaporated and the remaining acidic Ester with 46 parts of water, 26 parts of hexamethylenediamine, 16.8 parts of butylamine and 3.9 parts of ammonia (25% aqueous solution) are added with stirring. It educates an aqueous spreadable mass, which is applied to a rusted iron sheet will. The mixture is heated for 1 hour at 220 ° C and a slightly darkened, shiny, hard and elastic filni. If you work in a nitrogen atmosphere, so the film remains practically colorless.

Example 1I From a crude carboxylic acid mixture obtained by oxidation of Bituminous coal obtained with nitric acid of density 1.2 in the presence of air under pressure is made by boiling several times with acetone and concentrating the solutions Extract made from 100 parts of dissolved carboxylic acid mixture with an acid number of 412 and 200 "file acetone. 31.0 parts of ß-ethylhexanol are added to the extract and 11.2 parts of butanedioal 1,3 are added and the mixture is stirred and distilled off of the acetone gradually heated up to 150 ° C. It will be at this temperature for so long held until no further esterification takes place. Then lets man cool to 100 ° C. and stir 11.6 parts of hexamethylenediamine into the acidic ester and 3.6 parts of Butyla.min in the form of a 70% aqueous solution. Warming occurs a. The mixture is stirred with 30 parts of N @ 'water and placed on an iron plate elapsed. It is baked for 45 minutes at 200 ° C and a shiny, flexible, hard, well-adhering paint film. Example III 1? In a crude carboxylic acid mixture, obtained by the oxidation of coal with nitric acid is in an subjected to a known manner of a thermal aftertreatment with sulfuric acid and then extracted. The one obtainable after distilling off the solvent yellow acid mixture has an acid number of 700.

100 parts of this acid mixture are filed in 400 "ß-ethylhexanol dissolved and esterified by heating to boiling temperature until half the carboxyl groups have reacted. That is the case in about 3/3 of an hour. The solution the acid ester is freed from excess ß-ethylhexanol in vacuo. That The resulting mixture is mixed with 35 parts of hexamethylenediamine, which is 70% aqueous Solution is present, stirred. Warming occurs. Stir in the 100 ° C warm mixture a neutralization product of 5.5 parts of linseed oil fatty acid mixture and 2.40 parts Hexamethylenediamine. Adding 30 parts of water gives a spreadable one A mass that is applied to an iron sheet and baked at 200 ° C. for 1 hour. It the result is a hard, shiny, elastic film with good adhesive strength. example IV A raw carboxylic acid mixture obtained by oxidizing coal with nitric acid the density 1.2 was obtained at 160 ° C under pressure in the presence of 02 is used for the purpose Removal of certain high molecular weight fractions and mineral components with dioxane extracted. 400 parts of this extract, consisting of 300 parts of dioxane, 100 parts Carboxylic acid mixture with an acid number of 450, with 22.5 parts of butanediol 1.3 mixed and heated to 100 ° C for 5 hours. The dioxane is evaporated and the remaining mixture with 9 parts of hexamethylenediamine, 12 parts of isoamylamine and 15 parts of 1 n-N H3 water are added, with heating occurring. The mixture will Spread on an iron sheet and baked for 1 hour at 220 ° C. It arises a glossy, flexible, hard, well-adhering paint film.

Claims (4)

PATENT APPLICATION: 1. Stoving enamels, consisting of neutralization products of acidic esters, which are formed by the reaction of di- or polybasic carboxylic acids or their mixtures with less than the equivalent amount of one and or or Polyhydric alcohols are made with amines or amine mixtures, the Neutralization products, possibly already during their formation, with diluents, preferably water, are diluted. 2. Stoving enamels according to claim 1, characterized in that that water is used as a diluent in the presence or absence of ammonia is. 3. stoving enamels according to claim 1 and 2, characterized in that the acid one obtained from the oxidation of coals or other fuels with nitric acid Carboxylic acid mixture is used. 4. Stoving enamels according to Claims 1 to 3, characterized in that neutralization products of fatty acids and amines or other plasticizers are added to the ester amine mixture. Contemplated publications: USA. Patent No. 2,281,415..