# US 12,215,426 B2 · Composite coating for eliminating pollution by heavy metal chromium and VOCs from source and preparation method

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- Number: US 12,215,426 B2
- Document ID: US12215426B2
- Status: Granted
- Kind: B2
- Application number: 17/775,592
- Filed: 2020-02-24
- Published: 2022-12-22
- Granted: 2025-02-04
- Earliest claimed: 2020-01-23
- Assignees: Guangdong Provincial Academy of Building Research Group Co., Ltd
- Applicants: Guangdong Provincial Academy of Building Research Group Co., Ltd
- Inventors: Kai Zhang; Shichao Yang; Yang Ma
- Web page: https://patentgrep.com/patent/US12215426B2

## CPC

- C23C 22/34: containing fluorides or complex fluorides
- B05D 1/06: Applying particulate materials
- B05D 3/0254: {After-treatment}
- B05D 3/102: {Pretreatment of metallic substrates (C23C takes precedence)}
- B05D 7/14: to metal, e.g. car bodies (involving a chemical reaction between the metal and the coating C23)
- C09D 5/03: Powdery paints
- C09D 5/08: Anti-corrosive paints
- C09D 127/12: containing fluorine atoms
- C23C 22/78: Pretreatment of the material to be coated
- C23C 22/83: Chemical after-treatment
- B05D 2202/25: based on Al
- B05D 2506/10: Fluorinated polymers
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02)
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)

## Abstract

Disclosed is a composite coating for eliminating pollution by chromium and VOCs from a source, the coating comprising a conversion film layer and a coating surface layer. The conversion film layer is made of a surface pretreatment liquid, and the surface pretreatment liquid comprises the following components: an organic compound A having an aromatic ring and at least two phenolic hydroxyl groups in the molecule thereof, or a hydrate thereof; an ionic compound B containing zirconium and/or titanium and fluorine; a mixed solution C containing manganese fluoride; and an inorganic salt D containing potassium ions or sodium ions. The coating surface layer is an FEVE-type fluorocarbon powder coating layer. Also disclosed is a preparation method for the described composite coating.

## Claims

### Claim 1

A composite coating for eliminating pollution by chromium and VOCs from a source, comprising a conversion film layer and a coating surface layer, wherein:
the conversion film layer is made from a surface pretreatment liquid, and the surface pretreatment liquid comprises the following components:
an organic compound A having an aromatic ring and at least two phenolic hydroxyl groups in the molecule thereof or a hydrate of the organic compound A;
an ionic compound B containing an element of zirconium and/or titanium and fluorine;
a mixed solution C containing manganese fluoride; and
an inorganic salt D containing potassium ions or sodium ions,
wherein the coating surface layer is a FEVE-type fluorocarbon powder coating layer,
wherein a molecular structure of the at least two phenolic hydroxyl groups in the molecule of the organic compound A is:
wherein R2, R3, R4, R5, and R6 are selected from H or OH, and at least two of R2, R3, R4, R5, and R6 are OH, and
R1 is selected from an amide group, a carboxyl group, or an aldehyde group.

### Claim 2 (depends on 1)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 1, wherein the surface pretreatment liquid further comprises a penetrating agent E.

### Claim 3 (depends on 2)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 2, wherein the molar concentration of each component of the surface pretreatment liquid is:
0.2 mmol/L to 1.0 mmol/L of the organic compound A having an aromatic ring and at least two phenolic hydroxyl groups in the molecule thereof or the hydrate of the organic compound A;
0.1 mmol/L to 0.5 mmol/L of the ionic compound B containing an element of zirconium and/or titanium and fluorine;
0.1 mmol/L to 0.5 mmol/L of the mixed solution C containing manganese fluoride; and
0.1 mmol/L to 0.5 mmol/L of the inorganic salt D containing potassium ions or sodium ions; and
2×10−6 mmol/L to 6×10−6 mmol/L of the penetrating agent E,
wherein the concentration of the mixed solution C is calculated based on the concentration of manganese ions therein.

### Claim 4 (depends on 3)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 3, wherein the ionic compound B is selected from fluozirconic acid and/or fluozirconate or from fluotitanic acid and/or fluotitanate.

### Claim 5 (depends on 4)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 4, wherein the ionic compound B is selected from one or more of potassium fluorozirconate, sodium fluorozirconate, and ammonium fluorozirconate or from one or more of potassium fluorotitanate, sodium fluorotitanate, and ammonium fluorotitanate.

### Claim 6 (depends on 3)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 3, wherein the mixed solution C is prepared by dissolving manganese fluoride dihydrate in dilute sulfuric acid.

### Claim 7 (depends on 3)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 3, wherein the inorganic salt D is one or more of sodium sulfate, potassium sulfate, sodium fluoride, potassium fluoride, sodium hexafluoroaluminate, and potassium hexafluorochlorate.

### Claim 8 (depends on 3)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 3, wherein the penetrating agent E is diisooctyl maleate sulfonate.

### Claim 9 (depends on 3)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 3, wherein the FEVE-type fluorocarbon powder coating layer is selected from a fluorocarbon type powder coating with a FEVE resin content of 40% to 100% and with no organic solvent.

### Claim 10 (depends on 9)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 9, wherein the FEVE-type fluorocarbon powder coating layer is selected from a fluorocarbon type powder coating with a FEVE resin content of 45% to 80% and with no organic solvent.

### Claim 11 (depends on 1)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 1, wherein the organic compound A is selected from one or more of 3,4,5-trihydroxybenzamide, 3,4,5-trihydroxybenzoic acid, 3,4,5-trihydroxybenzaldehyde, and 2,4,6-trihydroxybenzoic acid.

### Claim 12 (depends on 11)

The composite coating for eliminating pollution by chromium and VOCs from a source according to claim 11, wherein the organic compound A is 3,4,5-trihydroxybenzoic acid.

### Claim 13 (depends on 1)

A preparation method of the composite coating for eliminating pollution by chromium and VOCs from the source according to claim 1, comprising:
a step (1): forming a conversion film layer on a metal surface by using a surface pretreatment liquid;
a step (2): treating the conversion film layer as a transition layer and coating a surface thereof with a FEVE-type fluorocarbon powder coating to form a coating surface layer; and
a step (3): curing the coating surface layer to form a composite coating, wherein the surface pretreatment liquid comprises the following components:
an organic compound A having an aromatic ring and at least two phenolic hydroxyl groups in the molecule thereof or a hydrate of the organic compound A;
an ionic compound B containing an element of zirconium and/or titanium and fluorine;
a mixed solution C containing manganese fluoride; and
an inorganic salt D containing potassium ions or sodium ions,
wherein a molecular structure of the at least two phenolic hydroxyl groups in the molecule of the organic compound A is:
wherein R2, R3, R4, R5, and R6 are selected from H or OH, and at least two of R2, R3, R4, R5, and R6 are OH, and
R1 is selected from an amide group, a carboxyl group, or an aldehyde group.

### Claim 14 (depends on 13)

The preparation method of the composite coating for eliminating pollution by chromium and VOCs from the source according to claim 13, further comprising:
before using the surface pretreatment liquid in the step (1), the metal surface is etched, and the etching amount is not less than 1.2 g/m2.

### Claim 15 (depends on 14)

The preparation method of the composite coating for eliminating pollution by chromium and VOCs from the source according to claim 14, wherein a manner of immersion, spraying, or coating is used in the step (1) to allow the surface pretreatment liquid covering the metal surface to form the conversion film layer.

### Claim 16 (depends on 15)

The preparation method of the composite coating for eliminating pollution by chromium and VOCs from the source according to claim 15, wherein the pH value of the surface pretreatment liquid is adjusted to 2.6 to 4.2, and
the treatment time is 2 minutes to 12 minutes when the manner of immersion is used;
the treatment time is 20 seconds to 60 seconds and the spraying pressure is less than 0.05 MPa when the manner of spraying is used;
the treatment time is 10 seconds to 20 seconds when the manner of coating is used.

### Claim 17 (depends on 16)

The preparation method of the composite coating for eliminating pollution by chromium and VOCs from the source according to claim 16, further comprising:
after the manner of immersion, spraying, or coating is performed, the conversion film layer is dried to speed up the forming of the conversion film layer, wherein the drying temperature is 80° C. to 120° C., and the drying time is 10 minutes to 20 minutes.

### Claim 18 (depends on 14)

The preparation method of the composite coating for eliminating pollution by chromium and VOCs from the source according to claim 14, wherein the FEVE-type fluorocarbon powder coating is sprayed on the surface of the conversion film layer by means of electrostatic spraying in the step (2), the thickness of spraying is 45 μm to 100 μm when the FEVE resin content of the FEVE-type fluorocarbon powder coating is 40% to 100%; and the thickness of spraying is 45 μm to 90 μm when the FEVE resin content of the FEVE-type fluorocarbon powder coating is 45% to 80%,
wherein in the process of electrostatic spraying, the electrostatic high voltage is 65 kV to 80 kV, the electrostatic current is 10 μA to 15 μA, and the atomization pressure is 0.4 MPa to 0.45 MPa.

### Claim 19 (depends on 14)

The preparation method of the composite coating for eliminating pollution by chromium and VOCs from the source according to claim 14, wherein during the curing process in the step (3), the curing temperature is 200° C. to 240° C., and the curing time is 10 minutes to 30 minutes.