DE1250036B - Stoving enamels - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C09d

German class: 22 g - 10/01

Number: 1 250 036

File number: B 78696 IV c / 22 g

, Filing date: September 28, 1964

Opened on September 14, 1967

Stoving enamels

The invention relates to stoving enamels

1. 45 to 96 parts by weight of water,

2. 4 to 55 parts by weight of ammonia and / or amine salts soluble in water or aqueous solutions of alkyd resins, which, linked like an ester,

a) 25 to 50 equivalent percent of residues of carbocyclic dibasic carboxylic acids,

b) 40 to 70 equivalent percent of residues of acyclic-aliphatic dibasic carboxylic acids,

c) 35 to 150 equivalent percent of residues of more than dihydric alcohols and optionally additionally ^c - ■ "

d) up to 20 equivalent percent of residues of monovalent carboxylic acids and / or up to 80 equivalent percent of residues of dihydric alcohols and / or up to 20 equivalent percent Residues of monohydric alcohols

included, as well

3. up to 50 parts by weight per 100 parts by weight of the salts of the alkyd resins (2) in water or aqueous solutions of soluble precondensates of aminoplasts containing N-methylol ether groups.

From stoving enamels of the type indicated, lacquers are available which, as is known, a number have valuable qualities, but also leave some wishes unfulfilled, especially with regard to theirs Adhesion strength to metals, their elasticity, their hardness and their water resistance.

It has been found that stoving enamels of the type specified improve their properties can be if they contain such salts of alkyd resins (2) in which the radicals of the carbocyclic dibasic carboxylic acids (a) to at least 50, preferably to at least 70 mol percent consist of residues of 1,2,3,6-tetrahydrophthalic acid.

Such stoving enamels can be used to obtain coatings which are distinguished in particular by improved adhesive strength on metals and improved elasticity, while at the same time being large Hardness and water resistance.

Suitable bases of the salts (2) for the invention Purpose Ammonia and the amines customary in the field, especially water-soluble, volatile amines such as methylamine, diethylamine, trimethylamine, Tri - (/ 3-hydroxyethyl) amine, N, N-dimethyl-N - (/? - hydroxypropyl) amine, Triethylamine and N, N-dimethyl-N - (; £? -Hydroxyethyl) amine. - To the salt notifier:

Aniline & Soda Factory in Baden

Aktiengesellschaft, Ludwigshafen / Rhein

Named as inventor:

Dr. Walter Lautenschlager,

Dr. Karl Engelhardt, Ludwigshafen / Rhine;

Dr. Max Wendt, Heidelberg;

Dr. Herbert Willersinn, Ludwigshafen / Rhine

A single base or a mixture of bases can be used for formation.

Particularly suitable alkyd resins of the salts (2) are those with an acid number of 25 to 90, preferably from 45 to 60. - The stoving enamels can be a single alkyd resin or a mixture of alkyd resins contain.

The following can be said in detail about the components of the alkyd resins of the salts (2):

a) According to the invention, 1,2,3,6-tetrahydrophthalic acid is used as the carbocyclic dibasic carboxylic acid; it is easily accessible, for example by diene synthesis from butadiene and maleic anhydride.

For - if necessary - additional use in addition to 1,2,3,6-tetrahydrophthalic acid suitable as further carbocyclic dibasic carboxylic acids are the relevant customary, for example phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid (1,2) and 1,2-dihydrophthalic acid and mixtures of such acids.

b) The relevant acyclic-aliphatic dibasic carboxylic acids are also suitable usual, for example succinic acid, glutaric acid, adipic acid, azelaic acid and sebacic acid, as well as mixtures of such acids.

c) As more than dihydric alcohols, the relevant customary ones are again suitable. At first These include glycerol and 1,1,1-trimethylolpropane undl ^ jl-triethylolpropane, also pentaerythritol and mixtures of such alcohols.

d) Suitable monohydric carboxylic acids, suitable dihydric alcohols and suitable monohydric Alcohols are again the usual ones to be mentioned: On the part of the monovalent carboxylic acids

709 647/551

for example benzoic acid, phenylacetic acid, a-ethylhexanecarboxylic acid, linseed oil fatty acid, ricinoleic acid, Ricinic acid, oleic acid, tall oil fatty acid and coconut fatty acid and mixtures thereof Acids. On the part of the dihydric alcohols, for example, ethanediol (1,2), propanediol (1,2), propanediol (l, 3), Butanediol- (1,4), 2,2-dimethylpropanediol- (1,3), hexadiol- (1,6), diethylene glycol and Triethylene glycol and mixtures of such alcohols. On the part of the monohydric alcohols, for example Butanol, pentanol and a-ethylhexanol and mixtures of such alcohols.

In addition to the components specified under a) to d), the alkyd resins can be used in minor amounts usual other modifying constituents contain, for example residues more than divalent Carboxylic acids such as trimellitic acid, pyromellitic acid and mixtures of such acids.

The alkyd resins can be produced by customary methods, for example by condensation of the structural components in the melt or under azeotropic conditions. It goes without saying It goes without saying that in the manufacture of the alkyd resins the acids referred to above as structural components and alcohols can be used not only as such, but also in the form of functional ones Derivatives such as anhydrides and esters.

The ammonia and / or amine salts of the alkyd resins (2) can be prepared in the customary manner can be made practically in every phase of the production of the stoving enamels, for example by Mixing the alkyd resins or the solutions or dispersions of the alkyd resins with ammonia and / or Amines or the aqueous solutions of these bases. The amount of the bases should expediently be so be chosen that in the finished stoving enamel to 1 mole of carboxyl groups of the alkyd resins 0.3 to 3, preferably 0.5 to 2 molar equivalents of the bases are omitted.

The stoving enamels according to the invention contain as a further component (3) in water or Precondensates of aminoplasts which are soluble in aqueous solutions and contain N-methylol ether groups. as such are the relevant usual ones, for example etherified urea-formaldehyde condensates, Etherified melamine-formaldehyde condensates and mixtures of condensates of the type specified.

The stoving enamels can contain the relevant customary additives, eg. B. different, more Binder, minor amounts of water-soluble organic solvents, in the presence of which the Components of the stoving enamel have been produced, and / or other solvents, such as monoalkyl ethers of di- and triethylene glycol, also compounds of hexavalent chromium, such as ammonium dichromate, as well as soluble dyes, pigments, flow improvers, corrosion inhibitors, stabilizers and / or curing catalysts.

The pH of the stoving enamels should in general expediently be 5 to 10, in particular 7 to 9, be; if necessary, it can be adjusted with the usual bases or acids.

The stoving enamels can be applied to the objects to be painted using the customary methods; they are particularly suitable for painting sheet metal. It is a particular advantage of the lacquers that they can also be deposited on the metal sheets using the electrophoresis process. The stoving of the lacquers can take place at temperatures from about 100 to 250, preferably from about 120 to 190 ^° C. and, depending on the stoving temperature, in a time span from about 20 to 120, preferably from about 30 to 60 minutes.

The parts and percentages given in the examples are based on weight.

example 1

400 parts of 1,2,3,6-tetrahydrophthalic anhydride (a) and 1760 parts of 1,1,1-trimethylolpropane (c) are used heated to 160 ° C. with stirring and passing through a weak stream of stick material until the acid number of the reaction mixture has dropped to about 40. After adding a further 400 parts of 1,2,3,6-tetrahydrophthalic anhydride (a) and 1620 parts of sebacic acid (b) is heated to 190 ° C and kept at this temperature until an acid number between 50 and 55 is reached.

The still warm alkyd resin is stirred with 300 parts of N, N-dimethyl-N- (jS-hydroxyethyl) amine in 3500 parts of water, a homogeneous solution with a solids content of about 50 ° / _{0 being} formed. 14 parts of the solution of the salt of the alkyd resin thus obtained are mixed with 3 parts of the hexamethyl ether of hexamethylolmelamine, 10 parts of titanium dioxide pigment and so much water that the total solids content of the mixture is 50%. After intensive mixing the baking varnish is painted on a clean thermoforming sheet and baked for 1 hour at 15O ⁰ C. A white, glossy, scratch-resistant coating is obtained; its adhesion to the sheet metal, its nail hardness and its water resistance are very good; the elasticity according to E richse η is 3.6 mm with a thickness of the coating of 90 μ.

Example 2

A mixture of 990 parts of 1,2,3,6-tetrahydrophthalic anhydride [a], 1460 parts of adipic acid [b], 540 parts of 1,1,1-trimethylolpropane [c], 1040 parts of 2,2-dimethylpropanediol (1,3 ) [O ₁ ] and 350 parts of hexanediol (1,6) [d ₂ ^{] is kept at 160 °} C. for 1 hour and then at 190 ^° C. for 1 hour while stirring and passing nitrogen through until the reaction mixture has an acid number between 50 and 55 has.
The alkyd resin obtained in this way is processed into a stoving finish under the conditions described in Example 1. The waterproof paintwork also adheres very well to the sheet metal and has very good nail hardness; their elasticity according to Erichsen is 5.1 mm with a thickness of the coating of 63 μ.

Example 3

Using an alkyd resin of acid number 50 from 990 parts of 1,2,3,6-tetrahydrophthalic anhydride [a], 1460 parts of adipic acid [b], 670 parts of 1,1,1-trimethylolpropane [c], 305 parts of benzoic acid [dj] and 1410 parts of 2,2-dimethylpropane (l, 2) [e _2] under the conditions described in example 1 ^be: conditions an enamel prepared. It is waterproof, has very good adhesion to the sheet metal, very good nail hardness and an elasticity according to Erichsen of 6.4 mm with a thickness of the paint of 45 μ.

Example 4

Using an alkyd resin of acid number 56 from 870 parts of 1,2,3,6-tetrahydrophthalic anhydride [a], 1730 parts of sebacic acid [b], 580 parts of 1,1,1-trimethylolpropane [c], 860 parts of 2,2-dimethylpropanediol - (l, 3) Id ₁ ] and 210 parts of i-butanol [d ₂ ], a stoving finish is produced under the conditions described in Example 1; it is also waterproof, has very good adhesion to the sheet metal, very good nail hardness and an elasticity according to E richse η of 6.4 mm with a thickness of the paint of 45 μ.

Claims (3)

Claim: stoving enamels off 1. 45 to 96 parts by weight of water, 2. 4 to 55 parts by weight of ammonia and / or amine salts soluble in water or aqueous solutions of alkyd resins, which, linked like an ester, a) 25 to 50 equivalent percent of residues of carbocyclic dibasic carboxylic acids, b) 40 to 70 equivalent percent of residues of acyclic-aliphatic dibasic carboxylic acids, c) 35 to 150 equivalent percent of residues of more than dihydric alcohols and optionally Additionally d) up to 20 equivalent percent of residues of monovalent carboxylic acids and / or up to 80 equivalent percent of residues of dihydric alcohols and / or up to 20 equivalent percent on residues of monohydric alcohols included, as well 3. up to 50 parts by weight per 100 parts by weight of the salts of the alkyd resins (2) in water or aqueous solutions of soluble precondensates of N-methylol ether groups Aminoplasts, characterized in that they contain such salts of alkyd resins (2) in which the At least 50 mol percent of residues of the carbocyclic dibasic carboxylic acids (a) are residues consist of 1,2,3,6-tetrahydrophthalic acid. 709 647/551 9. 67 © Bundesdruckerei Berlin