Method for coating metal surfaces of substrates, and objects coated according to said method

Abstract

A coating, a method for coating surfaces, and the coated surfaces. The method includes providing a substrate with a cleaned metal surface; contacting and coating the metal surface with an aqueous composition having a ph of from 0.5 to 7.0 and in the form of a dispersion and/or a suspension; optionally rinsing the organic coating; and drying and/or baking the organic coating, or optionally drying the organic coating and coating same with a similar or another coating composition thereto. The composition contains a complex fluoride in a quantity of 1.1 10.sup.−6 mol/l to 0.30 mol/l based on the cations. An anionic polyelectrolyte in a quantity of 0.01 to 5.0 wt % based on the total mass of the resulting mixture is added to an anionically stabilized dispersion made of film-forming polymers and/or a suspension made of film-forming inorganic particles.

Claims

1. An aqueous composition, the composition comprising: at least one anionic polyelectrolyte in a quantity of 0.01 to 5.0 wt % based on the total mass of the aqueous composition; a complex fluoride selected from the group consisting of hexa- or tetrafluorides of cations of titanium, zirconium, hafnium, silicon, aluminum, and/or boron in an amount of 1.1×10.sup.−6 mol/l to 0.30 mol/l based on the cations of the complex fluoride; a content of organic particles based on polyacrylates, polyurethanes, polyepoxides, and/or hybrids thereof; a content of at least one complexing agent selected from the group consisting of complexing agents based on maleic acid, alendronic acid, itaconic acid, citraconic acid, mesaconic acid, and anhydrides or semi-esters of these carboxylic acids; and the at least one anionic polyelectrolyte is based on gellan gum; wherein the composition is in the form of an anionically stabilized dispersion made of film-forming polymers, said dispersion comprising a solid content of 2 to 40 wt % and a mean particle size of 10 to 1,000 nm, said dispersion being stable in the pH value range of 0.5 to 7.0.

Description

EXAMPLE 1

(1) The substrate 1 was mixed with a mixture of 0.25% wt % based on the total amount of the resulting mixture with a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25% wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 2.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 55 to 65 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 2

(2) Experiment 1 was repeated with a substrate 2, and a dry film thickness of 15 to 25 μm was determined with SEM.

EXAMPLE 3

(3) Experiment 1 was repeated with a substrate 3, and a dry film thickness of 3 to 4 μm was determined with SEM.

EXAMPLE 4

(4) The substrate 1 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 4.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 63 to 67 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 5

(5) Experiment 4 was repeated with a substrate 2, and a dry film thickness of 10 to 20 μm was determined with SEM.

EXAMPLE 6

(6) Experiment 4 was repeated with a substrate 3, and a dry film thickness of 4 to 5 μm was determined with SEM.

EXAMPLE 7

(7) The substrate 1 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 6.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 70 to 85 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 8

(8) Experiment 7 was repeated with a substrate 2, and a dry film thickness of 5 to 7 μm was determined with SEM.

EXAMPLE 9

(9) Experiment 7 was repeated with a substrate 3, and a dry film thickness of 5 to 6 μm was determined with SEM.

EXAMPLE 10

(10) The substrate 2 was mixed with a mixture of 0.25% wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25% wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 8.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 5 to 10 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 11

(11) Experiment 10 was repeated with a substrate 3, and a dry film thickness of 7 to 8 μm was determined with SEM.

EXAMPLE 12

(12) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 10.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 8 to 9 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 13

(13) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 14.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 16 to 21 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 14

(14) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 24.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 20 to 22 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 15

(15) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the previously described dispersion A. 44.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 24 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 16

(16) The substrate 1 was mixed with 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the dispersion A. 1.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 52 to 55 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 17

(17) Experiment 16 was repeated with a substrate 2, and a dry film thickness of 18 to 24 μm was determined with SEM.

EXAMPLE 18

(18) Experiment 16 was repeated with a substrate 3, and a dry film thickness of 6 to 7 μm was determined with SEM.

EXAMPLE 19

(19) The substrate 1 was mixed with a mixture of 25% wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25% wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the dispersion A. 2.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 60 to 70 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 20

(20) Experiment 19 was repeated with a substrate 2, and a dry film thickness of 20 to 22 μm was determined with SEM.

EXAMPLE 21

(21) Experiment 19 was repeated with a substrate 3, and a dry film thickness of 8 to 9 μm was determined with SEM.

EXAMPLE 22

(22) The substrate 1 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the dispersion A. 4.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 67 to 73 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 23

(23) Experiment 22 was repeated with a substrate 2, and a dry film thickness of 6 to 11 μm was determined with SEM.

EXAMPLE 24

(24) Experiment 22 was repeated with a substrate 3, and a dry film thickness of 8 to 10 μm was determined with SEM.

EXAMPLE 25

(25) The substrate 1 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the dispersion A. 6.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 70 to 90 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 26

(26) Experiment 25 was repeated with a substrate 2, and a dry film thickness of 6 to 12 μm was determined with SEM.

EXAMPLE 27

(27) Experiment 25 was repeated with a substrate 3, and a dry film thickness of 7 to 9 μm was determined with SEM.

EXAMPLE 28

(28) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the above dispersion A. 8.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 8 to 11 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 29

(29) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the dispersion A. 10.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 8 to 12 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 30

(30) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the dispersion A. 14.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 9 to 11 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 31

(31) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the above dispersion A. 24.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 12 to 17 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 32

(32) The substrate 3 was mixed with a mixture of 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 52%, a degree of epoxidation of 0%, and a galacturonic acid content of 87%, and 0.25 wt %, based on the total amount of the resulting mixture, of a pectin having a molecular weight of about 70,000 g/mol, a degree of amidation of 0%, a degree of esterification of 10%, a degree of epoxidation of 0%, and a galacturonic acid content of 85%, with 99.5 wt % of the above dispersion A. 44.0 g/L of 20% hexafluorotitanic acid was added to the mixture. A dry film thickness of 16 to 24 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 33

(33) The substrate 1 was mixed with a mixture of 0.5 wt %, based on the total amount of the resulting mixture, of a chitosan having a degree of diacetylation between 65% and 85% dissolved in 1% acetic acid, and with 99.5 wt % of the dispersion A. 2.8 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 4 to 6 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 34

(34) The substrate 1 was mixed with a mixture of 0.5% wt %, based on the total amount of the resulting mixture, of a chitosan having a degree of diacetylation between 75% and 85% dissolved in 1% acetic acid, and with 99.5 wt % of the dispersion B. 2.4 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 45 to 50 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 35

(35) Experiment 35 was repeated with a substrate 3, and a dry film thickness of 3 to 4 μm was determined with SEM.

EXAMPLE 33

(36) The substrate 1 was mixed with a mixture of 0.5 wt %, based on the total amount of the resulting mixture, of a gellan gum having a molecular weight of about 70,000 g/mol and a low acyl content with 99.5 wt % of the above dispersion A. 2.0 g/L of 20% hexafluorozirconic acid was added to the mixture. A dry film thickness of 5 to 6 μm was measured, as determined with an eddy current meter and SEM.

EXAMPLE 34

(37) Experiment 33 was repeated with a substrate 2, and a dry film thickness of 7 to 8 μm was determined with SEM.

EXAMPLE 35

(38) Experiment 33 was repeated with a substrate 3, and a dry film thickness of 7 to 8 μm was determined with SEM.

COMPARATIVE EXAMPLE 1

(39) The substrate 1 was coated with the dispersion A. A dry film thickness was not determined by SEM.

COMPARATIVE EXAMPLE 2

(40) The substrate 2 was coated with the dispersion A. A dry film thickness was not determined by SEM.

COMPARATIVE EXAMPLE 3

(41) The substrate 3 was coated with the dispersion A. A dry film thickness was not determined by SEM.

COMPARATIVE EXAMPLE 4

(42) The coating of the substrate 1 with the polyelectrolytes referred to in the description of the invention, without mixture with the dispersion A, resulted in a dry film thickness of 300 to 500 nm.

COMPARATIVE EXAMPLE 5

(43) The coating of the substrate 2 with the polyelectrolytes referred to in the description of the invention, without mixture with the dispersion A, resulted in a dry film thickness of 300 to 500 nm.

COMPARATIVE EXAMPLE 6

(44) The coating of the substrate 3 with the polyelectrolytes referred to in the description of the invention, without mixture with the dispersion A, resulted in a dry film thickness of 300 to 500 nm.

(45) The microscope images consistently show a homogeneous layer formation, indicating a reliable, self-regulating, and readily controllable coating method.