A nano-passivated FW500 galvanized sheet and its production method

Abstract

The invention discloses a nano-passivated FW500 galvanized sheet and a production method thereof. The production method first uses a chromium-free passivation liquid to passivate the surface of the FW500 galvanized sheet at low temperature, and forms a colorless and transparent passivation layer; finally, a nano-passivation coating containing lamellar and granular structure nano-fillers is coated on the passivation layer by roller coating to obtain a nano-passivation coating FW500 galvanized sheet; and the finished product produced by the production method includes a FW500 galvanized sheet, a colorless and transparent passivation layer coated on the surface of the FW500 galvanized sheet, and a nano-passivation coating coated on the surface of the colorless and transparent passivation layer. The production method is simple to operate, has low production energy consumption, and the produced FW500 galvanized sheet has good corrosion resistance and good wear resistance.

Description

Technical Field

[0001] The invention relates to the technical field of galvanized sheets, and in particular to a nano-passivated FW500 galvanized sheet and a production method thereof. Background Art

[0002] Galvanized metal sheets are widely used in the fields of automobiles, building materials, home appliances, containers, etc. due to their good corrosion resistance and low price. However, galvanized metal sheets are prone to corrosion in a humid environment, forming white corrosion products on their surface or turning gray, which affects the appearance quality of the galvanized metal sheets and the corrosion resistance of the coating. In order to solve the above technical problems, most of the existing technologies use a passivation solution to passivate the galvanized sheet surface or color-coat the galvanized sheet surface, but there are still problems of poor corrosion resistance, especially poor acid and alkali resistance.

[0003] Therefore, how to provide a nano-passivated FW500 galvanized sheet and a production method thereof to solve the problems existing in the prior art is of great significance to its application. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide a nano-passivated FW500 galvanized sheet and a production method thereof, so as to solve the above-mentioned technical problems that most of the existing technologies use passivation liquid on the surface of the galvanized sheet or color coating on the surface of the galvanized sheet, but there is still the problem of poor corrosion resistance, especially poor acid and alkali resistance.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for producing a nano-passivated FW500 galvanized sheet comprises the following steps:

[0007] S1: prepare chromium-free passivation solution;

[0008] S2: preparing nano passivation coating;

[0009] S3: pre-treating the FW500 galvanized sheet;

[0010] S4: passivating the surface of the FW500 galvanized sheet obtained in step S3 using a chromium-free passivation solution to form a colorless and transparent passivation layer;

[0011] S5: coating the colorless and transparent passivation layer of the FW500 galvanized sheet with a nano passivation coating of 8-20 μm thick by roller coating, and baking at 150-250° C. until completely dry, to obtain a nano passivated FW500 galvanized sheet;

[0012] The chromium-free passivation solution in step S1 is mainly prepared from a mixture of a water-soluble resin, a water-soluble solvent, a metal phosphate, phosphoric acid and water;

[0013] The amount of metal phosphate in the chromium-free passivation solution accounts for 3-8 g / 100 ml of the total amount of the chromium-free passivation solution, and the amount of phosphoric acid accounts for 2-3 g / 100 ml of the total amount of the chromium-free passivation solution;

[0014] The nano passivation coating in step S2 is mainly prepared from water-based polyester resin, water-based amino resin, aliphatic dibasic acid ester, nano filler, color pigment, silane coupling agent, processing aid and water;

[0015] The nano filler is formed by mixing nano graphene powder and nano silicon dioxide powder in a mass ratio of 1:(4-5), and the nano filler accounts for 3-8wt.% of the total mass of the coating.

[0016] Preferably, the specific steps of step S3 include: first degreasing the galvanized sheet FW500 with alkaline solution, then washing it with clean water and drying it with hot air.

[0017] Preferably, the metal phosphate in the chromium-free passivation solution in step S2 is at least one of zinc phosphate and aluminum phosphate.

[0018] Preferably, the passivation treatment method in step S2 is to apply the chromium-free passivation solution on the surface of the galvanized sheet by roller coating and bake it at 60-80°C for 30-60s to form a colorless and transparent passivation layer, and the coating amount of the chromium-free passivation solution is 20-50g / m2.

[0019] Preferably, in step S3, the particle size of the nano-graphene powder is 80-150 nm, and the particle size of the nano-silicon dioxide powder is 50-80 nm.

[0020] Preferably, the coating for the nano passivation coating in step S3 mainly comprises the following components in percentage by total mass of the coating: 35-45wt.% of water-based polyester resin, 5-10wt.% of water-based amino resin, 3-8wt.% of aliphatic dibasic acid ester, 3-8wt.% of nano filler, 5-8wt.% of colored pigment, 2-3wt.% of silane coupling agent, 1-3wt.% of processing aid and balance water.

[0021] Preferably, the water-based polyester resin has a solid hydroxyl value of 50-150 mgKOH / g, a weight average molecular weight of 2000-8000, a Tg of 50-80°C, and the water-based polyester resin is at least one of an acrylic acid-modified polyester resin and an unsaturated acid anhydride-modified polyester resin; and the water-based amino resin is at least one of a melamine formaldehyde water-based resin, a methylated amino water-based resin, and a butylated amino water-based resin.

[0022] Preferably, the aliphatic dibasic acid ester is at least two of dimethyl glutarate, dimethyl succinate and dimethyl adipate.

[0023] Preferably, the processing aids include defoamers, leveling agents and wax slurry.

[0024] A nano-passivated FW500 galvanized sheet produced by any one of the production methods in claims 1 to 9, the nano-passivated FW500 galvanized sheet comprising a gold FW500 galvanized sheet, a colorless and transparent passivation layer coated on the surface of the FW500 galvanized sheet, and a nano-passivation coating coated on the surface of the colorless and transparent passivation layer.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application so that it can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings as follows.

[0027] Based on the detailed description of the specific embodiments of the present application in combination with the accompanying drawings below, those skilled in the art will become more aware of the above and other objects, advantages and features of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings without creative work. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0029] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0030] To make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all of the embodiments. In the following description, specific details such as specific configuration and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures is omitted in the embodiment.

[0031] In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0032] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" in this article describes another type of association object relationship, indicating that there can be two relationships. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0033] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusions.

[0034] See also Figure 1 The present invention provides a technical solution for a nano-passivated FW500 galvanized sheet and a production method thereof, comprising the following steps:

[0035] S1: prepare chromium-free passivation solution;

[0036] S2: preparing nano passivation coating;

[0037] S3: pre-treating the FW500 galvanized sheet;

[0038] S4: passivating the surface of the FW500 galvanized sheet obtained in step S3 using a chromium-free passivation solution to form a colorless and transparent passivation layer;

[0039] S5: coating the colorless and transparent passivation layer of the FW500 galvanized sheet with a nano passivation coating of 8-20 μm thick by roller coating, and baking at 150-250° C. until completely dry, to obtain a nano passivated FW500 galvanized sheet;

[0040] The chromium-free passivation solution in step S1 is mainly prepared from a mixture of a water-soluble resin, a water-soluble solvent, a metal phosphate, phosphoric acid and water;

[0041] The amount of metal phosphate in the chromium-free passivation solution accounts for 3-8 g / 100 ml of the total amount of the chromium-free passivation solution, and the amount of phosphoric acid accounts for 2-3 g / 100 ml of the total amount of the chromium-free passivation solution;

[0042] In step S2, the nano passivation coating is mainly prepared from water-based polyester resin, water-based amino resin, aliphatic dibasic acid ester, nano filler, color pigment, silane coupling agent, processing aid and water;

[0043] The nano filler is formed by mixing nano graphene powder and nano silicon dioxide powder in a mass ratio of 1:(4-5), and the nano filler accounts for 3-8wt.% of the total mass of the coating.

[0044] The specific steps of step S3 include: first degreasing the galvanized sheet FW500 with alkali solution, then washing it with clean water and drying it with hot air.

[0045] The metal phosphate in the chromium-free passivation solution in step S2 is at least one of zinc phosphate and aluminum phosphate.

[0046] The passivation treatment method in step S2 is to apply the chromium-free passivation liquid on the surface of the galvanized sheet by roller coating and bake it at 60-80°C for 30-60s to form a colorless and transparent passivation layer. The coating amount of the chromium-free passivation liquid is 20-50g / m2.

[0047] In step S3, the particle size of the nano-graphene powder is 80-150 nm, and the particle size of the nano-silicon dioxide powder is 50-80 nm.

[0048] The coating for the nano passivation coating in step S3 mainly includes the following components in percentage by total mass of the coating: 35-45wt.% of water-based polyester resin, 5-10wt.% of water-based amino resin, 3-8wt.% of aliphatic dibasic acid ester, 3-8wt.% of nano filler, 5-8wt.% of colored pigment, 2-3wt.% of silane coupling agent, 1-3wt.% of processing aid and balance water.

[0049] The waterborne polyester resin has a solid hydroxyl value of 50-150 mgKOH / g, a weight average molecular weight of 2000-8000, and a Tg of 50-80°C, and the waterborne polyester resin is at least one of an acrylic acid-modified polyester resin and an unsaturated acid anhydride-modified polyester resin; and the waterborne amino resin is at least one of a melamine formaldehyde waterborne resin, a methyl etherified amino waterborne resin, and a butyl etherified amino waterborne resin.

[0050] The aliphatic dibasic acid ester is at least two of dimethyl glutarate, dimethyl succinate and dimethyl adipate.

[0051] Processing aids include defoamers, leveling agents and wax slurries.

[0052] A nano-passivated FW500 galvanized sheet, which is produced by any one of the production methods in claims 1 to 9, and comprises a gold FW500 galvanized sheet, a colorless and transparent passivation layer coated on the surface of the FW500 galvanized sheet, and a nano-passivation coating coated on the surface of the colorless and transparent passivation layer.

[0053] The following is a specific description with reference to the embodiments:

[0054] First select the appropriate ratio of chromium-free passivation solution:

[0055] Proportion 1: 35 wt.% of water-soluble resin, 30 wt.% of water-soluble solvent, 3 wt.% of metal phosphate, 2 wt.% of phosphoric acid and 30 wt.% of water;

[0056] Proportion 2: 30 wt.% of water-soluble resin, 30 wt.% of water-soluble solvent, 8 wt.% of metal phosphate, 2 wt.% of phosphoric acid and 30 wt.% of water;

[0057] Proportion 3: 40 wt.% of water-soluble resin, 20 wt.% of water-soluble solvent, 3 wt.% of metal phosphate, 2 wt.% of phosphoric acid and 30 wt.% of water;

[0058] Proportion 4: 42 wt.% of water-soluble resin, 25 wt.% of water-soluble solvent, 5 wt.% of metal phosphate, 3 wt.% of phosphoric acid and 25 wt.% of water;

[0059] Then the formed colorless and transparent passivation layer was tested, among which the color and appearance, adhesion (cross-hatch method, grade), gloss (60°), T-bend (T), cupping (mm), MEK wiping resistance, impact strength (J), pencil hardness, and salt spray resistance (96h) of ratio 1 were the best.

[0060] Then choose the best nano-passivation coating ratio:

[0061] Coating Example 1: 35 wt.% of waterborne polyester resin, 5 wt.% of waterborne amino resin, 3 wt.% of aliphatic dibasic acid ester, 3 wt.% of nanofiller, 5 wt.% of color pigment, 2 wt.% of silane coupling agent, 1 wt.% of processing aid and 46 wt.% of water;

[0062] Coating Example 2: 40 wt.% of waterborne polyester resin, 8 wt.% of waterborne amino resin, 5 wt.% of aliphatic dibasic acid ester, 5 wt.% of nanofiller, 5 wt.% of color pigment, 3 wt.% of silane coupling agent, 2 wt.% of processing aid and 32 wt.% of water;

[0063] Coating Example 3: 45wt.% of waterborne polyester resin, 10wt.% of waterborne amino resin, 8wt.% of aliphatic dibasic acid ester, 8wt.% of nanofiller, 8wt.% of color pigment, 3wt.% of silane coupling agent, 3wt.% of processing aid and 15wt.% of water;

[0064] Coating Example 4: 35 wt.% of water-based polyester resin, 8 wt.% of water-based amino resin, 5 wt.% of aliphatic dibasic acid ester, 5 wt.% of nanofiller, 6 wt.% of colored pigment, 3 wt.% of silane coupling agent, 3 wt.% of processing aid and 35 wt.% of water.

[0065] After comprehensive experiments, coating example 2 has the best effect.

[0066] The above description is only the preferred embodiment of the present invention, which does not limit the protection scope of the present invention. For those skilled in the art, the present invention can be modified and varied in various ways. Within the spirit and principle of the present invention, any change, modification, replacement, integration and parameter change of these embodiments by conventional substitution or capable of achieving the same function without departing from the principle and spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for producing nano-passivated FW500 galvanized sheet, characterized in that: The following steps are involved: S1: prepare chromium-free passivation solution; S2: preparing nano passivation coating; S3: pre-treating the FW500 galvanized sheet; S4: passivating the surface of the FW500 galvanized sheet obtained in step S3 using a chromium-free passivation solution to form a colorless and transparent passivation layer; S5: coating the colorless and transparent passivation layer of the FW500 galvanized sheet with a nano passivation coating of 8-20 μm thick by roller coating, and baking at 150-250° C. until completely dry, to obtain a nano passivated FW500 galvanized sheet; The chromium-free passivation solution in step S1 is mainly prepared from a mixture of a water-soluble resin, a water-soluble solvent, a metal phosphate, phosphoric acid and water; The amount of the metal phosphate in the chromium-free passivation solution accounts for 3-8 g / 100 ml of the total amount of the chromium-free passivation solution, and the amount of the phosphoric acid accounts for 2-3 g / 100 ml of the total amount of the chromium-free passivation solution; The nano passivation coating in step S2 is mainly prepared from water-based polyester resin, water-based amino resin, aliphatic dibasic acid ester, nano filler, color pigment, silane coupling agent, processing aid and water; The nano filler is formed by mixing nano graphene powder and nano silicon dioxide powder in a mass ratio of 1:(4-5), and the nano filler accounts for 3-8wt.% of the total mass of the coating.

2. The method for producing a nano-passivated FW500 galvanized sheet according to claim 1, characterized in that: The specific steps of step S3 include: first degreasing the galvanized sheet FW500 with alkaline solution, then washing with clean water and drying with hot air.

3. The method for producing a nano-passivated FW500 galvanized sheet as claimed in claim 2, characterized in that: The metal phosphate in the chromium-free passivation solution in step S2 is at least one of zinc phosphate and aluminum phosphate.

4. The method for producing a nano-passivated FW500 galvanized sheet according to claim 1, characterized in that: The passivation treatment method in step S2 is to apply the chromium-free passivation solution on the surface of the galvanized sheet by roller coating and bake it at 60-80°C for 30-60s to form a colorless and transparent passivation layer. The coating amount of the chromium-free passivation solution is 20-50g / m2.

5. The method for producing a nano-passivated FW500 galvanized sheet according to claim 1, characterized in that: In the step S3, the particle size of the nano-graphene powder is 80-150 nm, and the particle size of the nano-silicon dioxide powder is 50-80 nm.

6. The method for producing a nano-passivated FW500 galvanized sheet according to claim 1, characterized in that: The coating for the nano passivation coating in step S3 mainly comprises the following components in percentage by total mass of the coating: 35-45wt.% of water-based polyester resin, 5-10wt.% of water-based amino resin, 3-8wt.% of aliphatic dibasic acid ester, 3-8wt.% of nano filler, 5-8wt.% of colored pigment, 2-3wt.% of silane coupling agent, 1-3wt.% of processing aid and balance water.

7. The method for producing a nano-passivated FW500 galvanized sheet according to claim 1, characterized in that: The water-based polyester resin has a solid hydroxyl value of 50-150 mgKOH / g, a weight average molecular weight of 2000-8000, and a Tg of 50-80°C, and the water-based polyester resin is at least one of an acrylic acid-modified polyester resin and an unsaturated acid anhydride-modified polyester resin; and the water-based amino resin is at least one of a melamine formaldehyde water-based resin, a methyl etherified amino water-based resin, and a butyl etherified amino water-based resin.

8. The method for producing a nano-passivated FW500 galvanized sheet according to claim 1, characterized in that: The aliphatic dibasic acid ester is at least two of dimethyl glutarate, dimethyl succinate and dimethyl adipate.

9. The method for producing a nano-passivated FW500 galvanized sheet according to claim 1, characterized in that: The processing aids include defoamers, leveling agents and wax slurries.

10. A nano-passivated FW500 galvanized sheet, characterized in that: The nano-passivated FW500 galvanized sheet produced by any one of the production methods of claim 1 to claim 9 comprises a gold FW500 galvanized sheet, a colorless and transparent passivation layer coated on the surface of the FW500 galvanized sheet, and a nano-passivation coating coated on the surface of the colorless and transparent passivation layer.

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