A method for repairing and feathering a CX heavy-duty coating

Abstract

The present application relates to heavy-duty coating damage repair technology, especially suitable for CX level electrophoresis and powder composite coating deep damage repair field on power transformer, hot dip galvanized radiator and other equipment, especially relates to a CX level heavy-duty coating damage repair and feathering polishing lap joint method, comprising the following steps: (1) feathering polishing pretreatment; (2) repair coating; The present application adopts feathering polishing and layered area lap joint structure design; CX level heavy-duty corrosion resistance can still be restored after the damage completely penetrates the zinc layer; The repair paint used has good bonding force with the powder coating; The repair thickness compensates for the loss of zinc layer, meets the long-term heavy-duty corrosion requirement; The repair position has no rust, no blister and no peeling, and the interface adhesion between the finish paint and the powder coating is greater than or equal to 18MPa.

Description

Technical Field

[0001] This invention relates to the technology for repairing damage to heavy-duty anti-corrosion coatings, and is particularly applicable to the field of deep damage repair technology for CX-grade electrophoretic and powder composite coatings on equipment such as power transformers and hot-dip galvanized radiators. Specifically, it relates to a method for repairing damage to CX-grade heavy-duty anti-corrosion coatings and a feathering grinding and overlapping method. Background Technology

[0002] Traditional repair processes have low adhesion, are prone to rust, and cannot restore the original anti-corrosion level; once the damage reaches the galvanized layer and the substrate, conventional repairs cannot meet the CX-level environmental requirements; the bonding strength between the repair paint and the powder coating is low, and it is easy to peel off. Summary of the Invention

[0003] To overcome the shortcomings and deficiencies of existing technologies, the present invention aims to provide a method for repairing and feathering / grinding overlapping of CX-grade heavy-duty anti-corrosion coatings. This method solves the problems of low adhesion, easy corrosion, and inability to restore the original anti-corrosion level in traditional repair processes; it also solves the problem that conventional repairs cannot meet CX-grade environmental requirements after the coating is damaged down to the galvanized layer and substrate; and it solves the problem of low bonding strength between the repair topcoat and powder coating, and easy delamination.

[0004] The objective of this invention is achieved through the following technical solution: a method for repairing damage and feathering / grinding overlap of a CX-grade heavy-duty anti-corrosion coating, comprising the following steps: (1) Pretreatment; Feathering grinding is performed on the damaged area of ​​the workpiece to expand the contact area of ​​the damaged area and improve the adhesion with the coating; (2) Repair the coating; a. Epoxy zinc-rich primer; spray multiple layers of epoxy zinc-rich primer, each layer being 40-60µm thick. The epoxy zinc-rich primer is sprayed within the feathering and polishing area. Each layer of epoxy zinc-rich primer is dried by baking or air drying after spraying. The baking temperature is 80℃ and the baking time is 40 min. The air drying time is greater than or equal to 12 h. b. Epoxy intermediate paint; spray multiple layers of epoxy primer, and spray the epoxy intermediate paint in the feathering and polishing area. Each layer is 50-70um thick. After each layer of epoxy intermediate paint is sprayed, it is dried by baking or air drying. The baking temperature is 80℃ and the baking time is 40min. The air drying time is greater than or equal to 12h. c. Powder-specific repair topcoat; Spray a layer of powder repair topcoat, the spraying position of the powder repair topcoat is to cross over and cover the original unsanded powder coating to achieve cross-repair, the thickness of the powder repair topcoat is 30-50um, after the powder repair topcoat is sprayed, it is dried by baking or natural drying, the baking temperature is 80℃, the baking time is 40min, and the natural drying time is greater than or equal to 12h. (3) Repair thickness test: The total dry film thickness in the repaired area is ≥300μm to be considered qualified.

[0005] As an improvement to the method for repairing damage and feathering grinding of the CX-grade heavy-duty anti-corrosion coating of the present invention: the specific pretreatment steps in step (1) are as follows; a. Degreasing and cleaning: Use a degreasing agent to wipe away oil and wax from the polished area and mark the damaged boundaries; b. Remove damaged paint: Use a dry sander with a P80 or P120 to remove cracked and hollow old paint, exposing the workpiece substrate; c. Create a feather-like slope: Use a dry sander with a P180-240 grit and sand at an angle of 15°-30°, sanding from the center of the damage outwards in an arc, so that the old paint gradually becomes thinner; every time you change to a finer grit of sandpaper, the sanding area should be larger than the previous sanding area to remove sanding marks. d. Finger touch test: Touch the transition area horizontally with your finger. If there are no steps or unevenness, it is considered qualified. e. Dust and oil removal: Blow away dust from the polishing area and perform secondary oil removal.

[0006] As an improvement to the repair and feathering grinding method of the CX-grade heavy anti-corrosion coating of the present invention: in step (2), three layers of epoxy zinc-rich primer are sprayed. The epoxy zinc-rich primer is HD-159 epoxy zinc-rich primer. The ratio of epoxy zinc-rich primer to curing agent is 10:1 for epoxy zinc-rich primer and 20-30% for curing agent.

[0007] As an improvement to the repair and feathering grinding method of the CX-grade heavy anti-corrosion coating of the present invention: two layers of epoxy intermediate paint are sprayed in step (2). The epoxy intermediate paint is HD-155 epoxy intermediate paint. The ratio of epoxy intermediate paint to curing agent is 7:1 for epoxy intermediate paint and 20-30% for curing agent.

[0008] As an improvement to the method of repairing and feathering grinding of the damaged CX-grade heavy anti-corrosion coating of the present invention: the powder-specific repair topcoat in step (2) is BM-242 powder-specific repair topcoat: the ratio of powder-specific repair topcoat to curing agent is 5:1 for powder-specific repair topcoat, and the amount of diluent added is 25-35% of the powder-specific repair topcoat.

[0009] The beneficial effects of this invention are as follows: This invention adopts a feathering grinding and layered overlapping structure design; even after the damage completely penetrates the zinc layer, it can still restore the CX-level heavy corrosion protection capability; the repair paint and powder coating have a very good bonding force; the repair thickness compensates for the loss of zinc layer and meets the requirements of long-term heavy corrosion protection; the repaired area is free of rust, blistering, and peeling, and the adhesion between the topcoat and the powder coating interface is ≥18MPa. Detailed Implementation

[0010] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0011] Example 1

[0012] A method for repairing damage and feathering / grinding overlap of CX-grade heavy-duty anti-corrosion coating includes the following steps: (1) Pretreatment; Feathering grinding is performed on the damaged area of ​​the workpiece to expand the contact area of ​​the damaged area and improve the adhesion with the coating; (2) Repair the coating; a. Epoxy zinc-rich primer; spray multiple layers of epoxy zinc-rich primer, each layer 40µm thick. The epoxy zinc-rich primer is sprayed within the feathering and polishing area. Each layer of epoxy zinc-rich primer is baked or air-dried after spraying. The baking temperature is 80℃, the baking time is 40 minutes, and the air-drying time is greater than or equal to 12 hours. Three layers of epoxy zinc-rich primer are sprayed. The epoxy zinc-rich primer is HD-159 epoxy zinc-rich primer. The ratio of epoxy zinc-rich primer to hardener is 10:1, and the amount of thinner added is 20% of the epoxy zinc-rich primer. b. Epoxy intermediate coat; spray multiple layers of epoxy primer, with the epoxy intermediate coat sprayed within the feathering sanding area. Each layer is 50µm thick. After each layer of epoxy intermediate coat is sprayed, it is either baked or air-dried. The baking temperature is 80℃, the baking time is 40 minutes, and the air-drying time is greater than or equal to 12 hours. Two layers of epoxy intermediate coat are sprayed. The epoxy intermediate coat is HD-155 epoxy intermediate coat, and the ratio of epoxy intermediate coat to hardener is 7:1. The amount of thinner added is 20% of the epoxy intermediate coat. c. Powder-specific repair topcoat; Spray a layer of powder-specific repair topcoat, the spraying position of the powder-specific repair topcoat is to cross over and cover the original unsanded powder coating to achieve cross-repair, the thickness of the powder-specific repair topcoat is 30um, the powder-specific repair topcoat is dried by baking or natural drying after spraying, the baking temperature is 80℃, the baking time is 40min, and the natural drying time is greater than or equal to 12h; the powder-specific repair topcoat is BM-242 powder-specific repair topcoat: the ratio of powder-specific repair topcoat to hardener is powder-specific repair topcoat 5: hardener 1, the amount of thinner added is 25% of the powder-specific repair topcoat; (3) Repair thickness test: The total dry film thickness in the repaired area is ≥300μm to be considered qualified.

[0013] Preferred steps: The specific pretreatment steps in step (1) are as follows; a. Degreasing and cleaning: Use a degreasing agent to wipe away oil and wax from the polished area and mark the damaged boundaries; b. Remove damaged paint: Use a dry sander (P80) to remove cracked and hollow old paint, exposing the workpiece substrate; c. Create a feather-like slope: Use a dry sander P180 at a 15° angle to sand, sanding from the center of the damage outwards in an arc, so that the old paint gradually becomes thinner; every time you change to a finer grit of sandpaper, the sanding area should be larger than the previous sanding area to remove sanding marks. d. Finger touch test: Touch the transition area horizontally with your finger. If there are no steps or unevenness, it is considered qualified. e. Dust and oil removal: Blow away dust from the polishing area and perform secondary oil removal.

[0014] Example 2

[0015] A method for repairing damage and feathering / grinding overlap of CX-grade heavy-duty anti-corrosion coating includes the following steps: (1) Pretreatment; Feathering grinding is performed on the damaged area of ​​the workpiece to expand the contact area of ​​the damaged area and improve the adhesion with the coating; (2) Repair the coating; a. Epoxy zinc-rich primer; spray multiple layers of epoxy zinc-rich primer, each layer being 50µm thick. The epoxy zinc-rich primer is sprayed within the feathering and polishing area. Each layer of epoxy zinc-rich primer is baked or air-dried after spraying. The baking temperature is 80℃, and the baking time is 40 minutes. The air-drying time is greater than or equal to 12 hours. Three layers of epoxy zinc-rich primer are sprayed. The epoxy zinc-rich primer is HD-159 epoxy zinc-rich primer. The ratio of epoxy zinc-rich primer to hardener is 10:1. The amount of thinner added is 25% of the epoxy zinc-rich primer. b. Epoxy intermediate coat; multiple layers of epoxy primer are sprayed, and the epoxy intermediate coat is sprayed within the feathering and polishing area. Each layer is 60µm thick. After each layer of epoxy intermediate coat is sprayed, it is either baked or air-dried. The baking temperature is 80℃ and the baking time is 40 minutes. The air-drying time is greater than or equal to 12 hours. Two layers of epoxy intermediate coat are sprayed. The epoxy intermediate coat is HD-155 epoxy intermediate coat. The ratio of epoxy intermediate coat to hardener is 7:1. The amount of thinner added is 5% of the epoxy intermediate coat. c. Powder-specific repair topcoat; spray a layer of powder-specific repair topcoat, the spraying position of the powder-specific repair topcoat is to cross over and cover the original unsanded powder coating to achieve cross-repair, the thickness of the powder-specific repair topcoat is 40um, the powder-specific repair topcoat is to be baked or air-dried after spraying, the baking temperature is 80℃, the baking time is 40min, the air-drying time is greater than or equal to 12h; the powder-specific repair topcoat is BM-242 powder-specific repair topcoat: the ratio of powder-specific repair topcoat to hardener is powder-specific repair topcoat 5: hardener 1, the amount of thinner added is 30% of the powder-specific repair topcoat; (3) Repair thickness test: The total dry film thickness in the repaired area is ≥300μm to be considered qualified.

[0016] Preferred steps: The specific pretreatment steps in step (1) are as follows; a. Degreasing and cleaning: Use a degreasing agent to wipe away oil and wax from the polished area and mark the damaged boundaries; b. Remove damaged paint: Use a dry sander (P120) to remove cracked and hollow old paint, exposing the workpiece substrate; c. Create a feathered slope: Use a dry sander P240 at a 20° angle to sand, sanding from the center of the damage outwards in an arc, so that the old paint gradually becomes thinner; every time you change to a finer grit of sandpaper, the sanding area should be larger than the previous sanding area to remove sanding marks. d. Finger touch test: Touch the transition area horizontally with your finger. If there are no steps or unevenness, it is considered qualified. e. Dust and oil removal: Blow away dust from the polishing area and perform secondary oil removal.

[0017] Example 3

[0018] A method for repairing damage and feathering / grinding overlap of CX-grade heavy-duty anti-corrosion coating includes the following steps: (1) Pretreatment; Feathering grinding is performed on the damaged area of ​​the workpiece to expand the contact area of ​​the damaged area and improve the adhesion with the coating; (2) Repair the coating; a. Epoxy zinc-rich primer; multiple layers of epoxy zinc-rich primer are sprayed, each layer being 60µm thick. The epoxy zinc-rich primer is sprayed within the feathering and polishing area. Each layer of epoxy zinc-rich primer is baked or air-dried after spraying. The baking temperature is 80℃, the baking time is 40 minutes, and the air-drying time is greater than or equal to 12 hours. Three layers of epoxy zinc-rich primer are sprayed. The epoxy zinc-rich primer is HD-159 epoxy zinc-rich primer. The ratio of epoxy zinc-rich primer to hardener is 10:1, and the amount of thinner added is 30% of the epoxy zinc-rich primer. b. Epoxy intermediate coat; multiple layers of epoxy primer are sprayed, with the epoxy intermediate coat sprayed within the feathering and sanding area. Each layer is 70µm thick. After each layer of epoxy intermediate coat is sprayed, it is either baked or air-dried. The baking temperature is 80℃, the baking time is 40 minutes, and the air-drying time is greater than or equal to 12 hours. Two layers of epoxy intermediate coat are sprayed. The epoxy intermediate coat is HD-155 epoxy intermediate coat, and the ratio of epoxy intermediate coat to hardener is 7:1. The amount of thinner added is 30% of the epoxy intermediate coat. c. Powder-specific repair topcoat; Spray a layer of powder-specific repair topcoat, the spraying position of the powder-specific repair topcoat is to cross over and cover the original unsanded powder coating to achieve cross-repair, the thickness of the powder-specific repair topcoat is 50um, the powder-specific repair topcoat is dried by baking or natural drying after spraying, the baking temperature is 80℃, the baking time is 40min, and the natural drying time is greater than or equal to 12h; the powder-specific repair topcoat is BM-242 powder-specific repair topcoat: the ratio of powder-specific repair topcoat to hardener is powder-specific repair topcoat 5: hardener 1, the amount of thinner added is 35% of the powder-specific repair topcoat; (3) Repair thickness test: The total dry film thickness in the repaired area is ≥300μm to be considered qualified.

[0019] Preferred steps: The specific pretreatment steps in step (1) are as follows; a. Degreasing and cleaning: Use a degreasing agent to wipe away oil and wax from the polished area and mark the damaged boundaries; b. Remove damaged paint: Use a dry sander (P120) to remove cracked and hollow old paint, exposing the workpiece substrate; c. Create a feather-like slope: Use a dry sander P180 at a 30° angle to sand, sanding from the center of the damage outwards in an arc, so that the old paint gradually becomes thinner; each time you change to a finer grit of sandpaper, the sanding area should be larger than the previous sanding area to remove sanding marks. d. Finger touch test: Touch the transition area horizontally with your finger. If there are no steps or unevenness, it is considered qualified. e. Dust and oil removal: Blow away dust from the polishing area and perform secondary oil removal.

[0020] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for repairing damage and feathering / grinding overlap of a CX-grade heavy-duty anti-corrosion coating, characterized in that: Includes the following steps: (1) Pretreatment; Feathering grinding is performed on the damaged area of ​​the workpiece to expand the contact area of ​​the damaged area and improve the adhesion with the coating; (2) Repair the coating; a. Epoxy zinc-rich primer; spray multiple layers of epoxy zinc-rich primer, each layer being 40-60µm thick. The epoxy zinc-rich primer is sprayed within the feathering and polishing area. Each layer of epoxy zinc-rich primer is dried by baking or air drying after spraying. The baking temperature is 80℃ and the baking time is 40 min. The air drying time is greater than or equal to 12 h. b. Epoxy intermediate coat; Spray multiple layers of epoxy primer, and spray the epoxy intermediate paint in the feathering and sanding area. Each layer is 50-70um thick. After each layer of epoxy intermediate paint is sprayed, it is dried by baking or air drying. The baking temperature is 80℃ and the baking time is 40min. The air drying time is greater than or equal to 12h. c. Powder-specific repair topcoat; Spray a layer of powder repair topcoat, the spraying position of the powder repair topcoat is to cross over and cover the original unsanded powder coating to achieve cross-repair, the thickness of the powder repair topcoat is 30-50um, after the powder repair topcoat is sprayed, it is dried by baking or natural drying, the baking temperature is 80℃, the baking time is 40min, and the natural drying time is greater than or equal to 12h. (3) Repair thickness test: The total dry film thickness in the repaired area is ≥300μm to be considered qualified.

2. The method for repairing damage and feathering grinding of a CX-grade heavy-duty anti-corrosion coating according to claim 1, characterized in that: The specific preprocessing steps in step (1) are as follows; a. Degreasing and cleaning: Use a degreasing agent to wipe away oil and wax from the polished area and mark the damaged boundaries; b. Remove damaged paint: Use a dry sander with a P80 or P120 to remove cracked and hollow old paint, exposing the workpiece substrate; c. Create a feather-like slope: Use a dry sander with a P180-240 grit and sand at an angle of 15°-30°, sanding from the center of the damage outwards in an arc, so that the old paint gradually becomes thinner; every time you change to a finer grit of sandpaper, the sanding area should be larger than the previous sanding area to remove sanding marks. d. Finger touch test: Touch the transition area horizontally with your finger. If there are no steps or unevenness, it is considered qualified. e. Dust and oil removal: Blow away dust from the polishing area and perform secondary oil removal.

3. The method for repairing damage and feathering grinding of a CX-grade heavy-duty anti-corrosion coating according to claim 1, characterized in that: In step (2), three layers of epoxy zinc-rich primer are sprayed. The epoxy zinc-rich primer is HD-159 epoxy zinc-rich primer. The ratio of epoxy zinc-rich primer to curing agent is 10:

1. The amount of diluent added is 20-30% of the epoxy zinc-rich primer.

4. The method for repairing damage and feathering grinding overlap of a CX-grade heavy-duty anti-corrosion coating according to claim 1, characterized in that: In step (2), two layers of epoxy intermediate paint are sprayed. The epoxy intermediate paint is HD-155 epoxy intermediate paint. The ratio of epoxy intermediate paint to curing agent is 7:

1. The amount of thinner added is 20-30% of the epoxy intermediate paint.

5. The method for repairing damage and feathering grinding of a CX-grade heavy-duty anti-corrosion coating according to claim 1, characterized in that: The powder-specific repair topcoat in step (2) is BM-242 powder-specific repair topcoat: the ratio of powder-specific repair topcoat to hardener is 5 parts powder-specific repair topcoat to 1 part hardener, and the amount of thinner added is 25-35% of the powder-specific repair topcoat.