Coating for decorating colored aluminum plate and preparation method thereof

Abstract

The invention relates to a coating for a decorative colored aluminum plate, the decorative colored aluminum plate is provided with a contact surface, when the coating is arranged on the contact surface, the coating comprises a base body layer and a hole sealing layer, one side of the base body layer is connected with the contact surface, the other side of the base body layer is connected with the hole sealing layer, the porosity of the coating is a%, the thickness of the base body layer is H1 [mu] m, and the thickness of the base body layer is H1 [mu] m. The thickness of the hole sealing layer is H2 [mu] m, the contact angle between the substrate layer and the contact surface is theta degrees, and the coating meets the condition that (H1 * theta) / (H2 * a) is larger than or equal to 0.08 and smaller than or equal to 22.86; wherein the coating at least meets at least one of the following inequality relationships: 15 < = H1 < = 25; 0 < theta < = 10.5; 5 < = H2 < = 15; 0 < a < = 10; the hole sealing layer is used for filling pores and enhancing corrosion resistance, and under the condition that the inequality is met, the grade of the paint surface adhesive force test of the coating is always kept at 3B or above, so that the coating provided by the invention has excellent wear resistance and corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of decorative color aluminum plate coatings, in particular to a coating for decorative color aluminum plates and a preparation method thereof. Background Art

[0002] Colored aluminum sheet refers to a material that is processed by surface coating of aluminum sheet to form a variety of colors, thereby improving the oxidation protection performance and aesthetics of the aluminum sheet. In life, colored aluminum sheet is widely used in construction, decoration, automobiles, electrical appliances, packaging and other fields, and has become an important part of many products.

[0003] Patent publication number CN110357523B discloses a decorative board coating, which includes a base material, an inorganic iron oxide pigment, an additive, colored sand, and a mineral blend. The preparation method comprises: dividing the colored sand into two parts, dividing the base material into two parts, adding the first part of the colored sand and the first part of the base material to the mixture of the inorganic iron oxide pigment and the additive, stirring evenly to obtain a premix, adding the second part of the colored sand and the second part of the base material to the premix, and stirring evenly to obtain the decorative board coating. The patent does not take into account the influence of wear resistance and corrosion resistance. Summary of the Invention

[0004] The object of the present invention is to provide a coating having excellent wear resistance and corrosion resistance.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides a coating for a decorative colored aluminum plate, wherein the decorative colored aluminum plate has a contact surface, and the coating is provided on the contact surface; The coating comprises a base layer and a sealing layer, wherein one side of the base layer is connected to the contact surface, and the other side of the base layer is connected to the sealing layer; The porosity of the coating is a%, the thickness of the base layer is H1 μm, the thickness of the sealing layer is H2 μm, the contact angle between the base layer and the contact surface is θ°, and the coating satisfies: 0.08≤(H1×θ) / (H2×a)≤22.86; Wherein, the coating satisfies at least one of the following inequality relationships: (1) 15≤H1≤25; (2) 0<θ≤10.5; (3) 5≤H2≤15; (4) 0<a≤10.

[0006] Furthermore, the contact surface has a maximum arc M° and a minimum arc N°, and the contact surface satisfies 0≤MN≤3.5, 90<M<180, 90<N<180.

[0007] Furthermore, the contact surface includes an arcuate surface and a plurality of inner concave grooves, the inner concave grooves having a bottom wall and a surrounding wall, the surrounding wall being arranged around the circumference of the bottom wall, the bottom wall and the surrounding wall forming an accommodating space, the cross-sectional area of ​​the surrounding wall decreasing from the side of the surrounding wall away from the bottom wall to the side where the surrounding wall is connected to the bottom wall, and the side of the surrounding wall away from the bottom wall is connected to the arcuate surface; A portion of the coating fills the accommodation space, and another portion of the coating is disposed on the surface of the arc portion.

[0008] Furthermore, the accommodating space is in a truncated cone shape, the accommodating space has a circular opening, the bottom wall is a circular bottom wall, the surrounding wall is a truncated cone surrounding wall, the coating enters the accommodating space through the circular opening and fills the accommodating space, and the diameter of the circular opening is larger than the diameter of the circular bottom wall.

[0009] Furthermore, a chamfered portion is provided on the side of the surrounding wall away from the bottom wall, the curvature of the chamfered portion is π / 4 to π / 3, one end of the chamfered portion is connected to the side of the surrounding wall away from the bottom wall, and the other end of the chamfered portion is connected to the arc portion.

[0010] Furthermore, the coating comprises the following components in parts by weight: 45-61 parts of fluororesin, 10-14 parts of blocked isocyanate, 0.5-1.5 parts of leveling agent, 0.5-1.5 parts of brightener, 0.3-0.5 parts of degassing agent, 16-36 parts of colorant, 2-4 parts of wetting agent, and 10-20 parts of sealing agent.

[0011] Furthermore, the wetting agent is a succinate block copolymer or a polyether siloxane copolymer.

[0012] Furthermore, the leveling agent is one of acrylic, silicone and fluorocarbon compounds.

[0013] Furthermore, the brightener is an acidic zinc plating brightener; the degassing agent is one of benzoin, stearic acid, and hydrogenated castor oil derivatives; and the sealing agent is one of phenol resin and epoxy resin.

[0014] In a second aspect, the present invention further provides a method for preparing a coating, comprising the following steps: S1: Weigh each raw material according to weight; S2: Add the pre-mixed fluororesin and blocked isocyanate composite slurry into the mixer, start stirring, disperse at a speed of 600-700 r / min for 10-15 minutes, increase the speed to 900-1100 r / min, add the colorant and wetting agent in sequence, and disperse for 15-25 minutes to obtain a mixed slurry; S3: Lower the rotation speed to 600-700 r / min, add the leveling agent, brightener, and degassing agent to the mixed slurry prepared in step S2 in sequence, disperse for 25-40 minutes, and mix evenly to obtain the base layer of the coating; S4: Add the sealing agent into another mixer, start stirring, and disperse it at a speed of 600-700 r / min for 10-15 minutes to obtain the sealing layer of the coating.

[0015] The beneficial effects of the present invention are as follows: when the coating is provided on the contact surface, the coating includes a base layer and a sealing layer, one side of the base layer is connected to the contact surface, and the other side of the base layer is connected to the sealing layer, the porosity of the coating is a%, the thickness of the base layer is H1 μm, the thickness of the sealing layer is H2 μm, the contact angle between the base layer and the contact surface is θ°, and the coating satisfies the following conditions: 0.08≤(H1×θ) / (H2×a)≤22.86; The coating satisfies at least one of the following inequalities: 15≤H1≤25; 0<θ≤10.5; 5≤H2≤15; 0<a≤10; the sealing layer is used to fill the pores and enhance the corrosion resistance. When the above inequalities are met, the coating of the present invention always maintains a grade of 3B or above in the paint adhesion test, which also makes the coating provided by the present invention have excellent wear resistance and corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the position of the coating and the contact surface in an embodiment of the present invention.

[0017] Figure 2 2 is a schematic top view of the contact surface of an embodiment of the present invention.

[0018] Figure 3 4 is a schematic cross-sectional view of a coating-filled inner concave hole groove according to an embodiment of the present invention.

[0019] Figure 4 2 is a schematic cross-sectional view of the inner concave hole groove according to an embodiment of the present invention.

[0020] Description of Figure Numbers: 100, coating layer; 110, base layer; 120, sealing layer; 200, contact surface; 210, contact surface 200; 220, inner concave hole groove; 221, bottom wall; 222, surrounding wall; 223, chamfered portion; 230, accommodating space. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the following further describes a coating for decorative colored aluminum plates and its preparation method in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0022] Specifically, please refer to 1-3. The present invention provides a coating for a decorative colored aluminum plate. The decorative colored aluminum plate has a contact surface 200, and the coating 100 is arranged on the contact surface 200.

[0023] Specifically, the coating 100 includes a base layer 110 and a sealing layer 120. One side of the base layer 110 is connected to the contact surface 200, and the other side of the base layer 110 is connected to the sealing layer 120. The porosity of the coating 100 is a%, the thickness of the base layer 110 is H1 μm, the thickness of the sealing layer 120 is H2 μm, and the contact angle between the base layer 110 and the contact surface 200 is θ°. The coating 100 satisfies the following conditions: 0.08 ≤ (H1 × θ) / (H2 × a) ≤ 22.86. The coating 100 satisfies at least one of the following inequalities: (1) 15≤H1≤25; (2) 0<θ≤10.5; (3) 5≤H2≤15; (4) 0<a≤10.

[0024] It should be mentioned that there are many ways to apply the coating 100 to the contact surface 200, such as brushing, dipping, air spraying, electrostatic spraying, electrophoretic coating, powder coating, etc. There is no restriction here, as long as the coating 100 can be attached to the contact surface 200.

[0025] When the above-mentioned coating is provided on the contact surface, the coating includes a base layer and a sealing layer, one side of the base layer is connected to the contact surface, and the other side of the base layer is connected to the sealing layer. The porosity of the coating is a%, the thickness of the base layer is H1 μm, the thickness of the sealing layer is H2 μm, the contact angle between the base layer and the contact surface is θ°, and the coating satisfies: 0.08≤(H1×θ) / (H2×a)≤22.86; wherein, the coating satisfies at least one of the following inequalities: 15≤H1≤25; 0<θ≤10.5; 5≤H2≤15; 0<a≤10; the function of the sealing layer is to fill the pores and enhance the corrosion resistance. When the above inequalities are satisfied, the coating of the present invention always maintains a grade of 3B or above in the paint adhesion test, which also makes the coating provided by the present invention have excellent wear resistance and corrosion resistance.

[0026] In some embodiments, the contact surface 200 has a maximum curvature M° and a minimum curvature N°, and the contact surface 200 satisfies 0≤MN≤3.5, 90<M<180, and 90<N<180. When the decorative colored aluminum plate has the above-mentioned curvature difference, the surface contact between the external object and the colored aluminum plate can be converted into line contact without affecting the mechanical properties of the colored aluminum plate, thereby reducing friction resistance, thereby further improving the adhesion ability of the paint surface and improving the wear resistance of the coating. 90<M<180 and 90<N<180 are mainly to ensure the stability of the mechanical properties of the colored aluminum plate. The range of 0≤MN≤3.5 is determined because when MN exceeds 3.5, the aluminum plate is brittle, and exceeding this angle difference will cause damage-type deformation.

[0027] See Figure 2-3 In order to further improve the wear resistance of the coating 100, the contact surface 200 includes an arc surface 210 and a plurality of concave grooves 220. The concave groove 220 has a bottom wall 221 and a surrounding wall 222. The surrounding wall 222 is arranged around the circumference of the bottom wall 221. The bottom wall 221 and the surrounding wall 222 form a receiving space 230. From the side of the surrounding wall 222 away from the bottom wall 221 to the side where the surrounding wall 222 is connected to the bottom wall 221, the cross-sectional area of ​​the surrounding wall 222 decreases. The side of the surrounding wall 222 away from the bottom wall 221 is connected to the arc surface 210; a part of the coating 100 fills the receiving space 230, and the other part of the coating 100 is arranged on the surface of the arc surface 210. Through this arrangement, due to the distance from the side of the surrounding wall 222 away from the bottom wall 221 to the side where the surrounding wall 222 is connected to the bottom wall 221, The cross-sectional area of ​​the surrounding wall 222 tends to decrease, and the coating 100 can more easily and quickly enter and fill the accommodating space 230, and the adhesion ability of the partial coating 100 in the accommodating space 230 is stronger than that of the other partial coating 100 attached to the curved surface portion 210, because the total contact area between the partial coating 100 of the accommodating space 230 and the surrounding wall 222 and the bottom wall 221 is larger. When a scratch occurs, the partial coating 100 of the accommodating space 230 is not easily scraped off, which also avoids a large area of ​​scratches on the vehicle body, where part of the coating 100 on the curved surface portion 210 is scraped off, but part of the coating 100 in the accommodating space 230 is not affected. When performing paint adhesion testing, the partial coating 100 in the accommodating space 230 is not easily stuck away, thereby improving wear resistance.

[0028] As a preferred embodiment, see Figure 3The accommodating space 230 is in the shape of a truncated cone. The accommodating space 230 has a circular opening, the bottom wall 221 is a circular bottom wall, and the surrounding wall 222 is a truncated cone surrounding wall. The coating 100 enters the accommodating space 230 through the circular opening and fills the accommodating space 230. The diameter of the circular opening is larger than the diameter of the bottom wall 221. Setting the accommodating space 230 in the shape of a truncated cone not only has a simple process and low cost, but also the contact area between the circular surface and the arc surface is the largest compared to the contact area of ​​other regular shapes. The larger the contact area, the stronger the adhesion of the coating 100 in the accommodating space 230, thereby improving the wear resistance of the coating 100 on the contact surface 200.

[0029] As a preferred embodiment, see Figure 3 A chamfered portion 223 is provided on the side of the surrounding wall 222 away from the bottom wall 221, and the radian of the chamfered portion 223 is π / 4~π / 3. One end of the chamfered portion 223 is connected to the side of the surrounding wall 222 away from the bottom wall 221, and the other end of the chamfered portion 223 is connected to the curved surface portion 210. The setting of the chamfered portion 223 makes it possible for the contacted object and the chamfer to present a geometric tangent relationship when a scratch occurs, and the previous surface contact is converted into point contact. In this way, the part of the coating 100 filled in the accommodating space 230 is not easily scratched off, and the chamfered portion 223 plays an important protective role. In addition, the radian of the chamfered portion 223 is selected between π / 4~π / 3, which can reduce the impact on the overall structural strength of the vehicle body and ensure the stability of the overall structural strength of the vehicle body.

[0030] The coating 100 includes the following components in parts by weight: 45-61 parts of fluororesin, 10-14 parts of blocked isocyanate, 0.5-1.5 parts of leveling agent, 0.5-1.5 parts of brightener, 0.3-0.5 parts of degassing agent, 16-36 parts of colorant, 2-4 parts of wetting agent, and 10-20 parts of sealing agent.

[0031] In one embodiment, the wetting agent is a succinate block copolymer or a polyether siloxane copolymer. The succinate block copolymer has excellent wetting properties for various inorganic and organic pigments and fillers, and is applicable to various base materials, so that the gloss and color development of the paint film can be fully reflected. When not used in excess, it has no adverse effect on water resistance and corrosion resistance; the polyether siloxane copolymer has good compatibility and has no adverse effect on water resistance and corrosion resistance when not used in excess.

[0032] In one embodiment, the leveling agent is selected from the group consisting of acrylic, silicone, and fluorocarbon compounds. The leveling agent helps improve the dispersion of the pigment, degassing during the curing process, and enhances fluidity. This good dispersion promotes the dispersion of the pigment in the system, enhancing color uniformity and reducing processing time.

[0033] In one embodiment, the brightener is a neutral brightener, which can improve the corrosion resistance of the coating; the degassing agent is one of a derivative of benzoin, stearic acid, and hydrogenated castor oil, so that the coating can be continuously expanded and there is enough time for air to escape from the coating; the sealing agent is one of a phenol resin and an epoxy resin, so that the sealing agent has sufficient permeability and a high solid content, good corrosion resistance, can withstand certain mechanical effects, has stable performance at working temperature, and does not chemically react with the coating.

[0034] Example 1 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 45 parts of fluororesin, 10 parts of blocked isocyanate, 0.5 parts of leveling agent, 0.5 parts of brightener, 0.3 parts of degassing agent, 16 parts of colorant, 2 parts of wetting agent, and 10 parts of sealing agent.

[0035] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 5%, the thickness of the base layer 110 is 15 μm, and the thickness of the sealing layer 120 is 5 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 5°.

[0036] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0037] Example 2 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 61 parts of fluororesin, 14 parts of blocked isocyanate, 1.5 parts of leveling agent, 1.5 parts of brightener, 0.5 parts of degassing agent, 36 parts of colorant, 4 parts of wetting agent, and 20 parts of sealing agent.

[0038] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 10%, the thickness of the base layer 110 is 25 μm, and the thickness of the sealing layer 120 is 15 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 10°.

[0039] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0040] Example 3 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 55 parts of fluororesin, 1.2 parts of blocked isocyanate, 1.3 parts of leveling agent, 1.3 parts of brightener, 0.5 parts of degassing agent, 25 parts of colorant, 3 parts of wetting agent, and 15 parts of sealing agent.

[0041] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 3%, the thickness of the base layer 110 is 20 μm, and the thickness of the sealing layer 120 is 10 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 10.5°.

[0042] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0043] Example 4 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 50 parts of fluororesin, 1.3 parts of blocked isocyanate, 1.2 parts of leveling agent, 1.2 parts of brightener, 0.4 parts of degassing agent, 32 parts of colorant, 3 parts of wetting agent, and 18 parts of sealing agent.

[0044] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 1%, the thickness of the base layer 110 is 25 μm, and the thickness of the sealing layer 120 is 15 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 2°.

[0045] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0046] Example 5 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 40 parts of fluororesin, 11 parts of blocked isocyanate, 0.5 parts of leveling agent, 0.5 parts of brightener, 0.3 parts of degassing agent, 16 parts of colorant, 2 parts of wetting agent, and 10 parts of sealing agent.

[0047] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 2%, the thickness of the base layer 110 is 25 μm, and the thickness of the sealing layer 120 is 5 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 10°.

[0048] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0049] Example 6 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 57 parts of fluororesin, 14 parts of blocked isocyanate, 0.6 parts of leveling agent, 0.6 parts of brightener, 0.4 parts of degassing agent, 31 parts of colorant, 2 parts of wetting agent, and 18 parts of sealing agent.

[0050] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 10%, the thickness of the base layer 110 is 15 μm, and the thickness of the sealing layer 120 is 15 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 0.8°.

[0051] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0052] Example 7 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 59 parts of fluororesin, 13 parts of blocked isocyanate, 0.7 parts of leveling agent, 0.7 parts of brightener, 0.4 parts of degassing agent, 32 parts of colorant, 3 parts of wetting agent, and 14 parts of sealing agent.

[0053] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 0.5%, the thickness of the base layer 110 is 20 μm, and the thickness of the sealing layer 120 is 7 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 4°.

[0054] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0055] Example 8 A coating for decorative colored aluminum plates, comprising the following components in parts by weight: 60 parts of fluororesin, 14 parts of blocked isocyanate, 0.8 parts of leveling agent, 0.9 parts of brightener, 0.3 parts of degassing agent, 33 parts of colorant, 2 parts of wetting agent, and 11 parts of sealing agent.

[0056] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 1%, the thickness of the base layer 110 is 15 μm, and the thickness of the sealing layer 120 is 15 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 0.9°.

[0057] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of 5 microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is 5 microns, the circular opening diameter of the accommodating space 230 is 10 microns, and the diameter depth of the accommodating space 230 is 5 microns.

[0058] Comparative Example 1 The coating formulation ratio is the same as that of the first embodiment, but the contact surface 200 is not provided with the inner concave groove 220. When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 1%, the thickness of the base layer 110 is 25 μm, and the thickness of the sealing layer 120 is 15 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 1°.

[0059] Comparative Example 2 The coating formula ratio is 44 parts of fluororesin, 9 parts of blocked isocyanate, 0.4 parts of leveling agent, 0.4 parts of brightener, 0.2 parts of degassing agent, 15 parts of colorant, 1 part of wetting agent and 9 parts of sealing agent.

[0060] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 17%, the thickness of the base layer 110 is 12 μm, and the thickness of the sealing layer 120 is 1 μm, and the contact angle between the base layer 110 and the contact surface 200 is 40°.

[0061] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of five microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is five microns, the circular opening diameter of the accommodating space 230 is ten microns, and the diameter depth of the accommodating space 230 is five microns.

[0062] Comparative Example 3 The coating formula ratio is 62 parts of fluororesin, 15 parts of blocked isocyanate, 1.6 parts of leveling agent, 1.6 parts of brightener, 0.6 parts of degassing agent, 37 parts of colorant, 5 parts of wetting agent and 21 parts of sealing agent.

[0063] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 10%, the thickness of the base layer 110 is 5 μm, and the thickness of the sealing layer 120 is 20 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 1°.

[0064] In addition, the contact surface 200 is provided with a plurality of concave grooves 220 with a spacing of five microns. The accommodating space 230 of the concave grooves 220 is in a truncated cone shape. The bottom wall diameter of the concave grooves 220 is five microns, the circular opening diameter of the accommodating space 230 is ten microns, and the diameter depth of the accommodating space 230 is five microns.

[0065] Comparative Example 4 The formulation ratio of the coating 100 is the same as that of the comparative example 2, but the inner concave groove 220 is not provided on the contact surface 200 .

[0066] When the coating 100 is disposed on the contact surface 200, the porosity of the coating 100 is 10%, the thickness of the base layer 110 is 25 μm, and the thickness of the sealing layer 120 is 15 μm. μm, and the contact angle between the base layer 110 and the contact surface 200 is 10°.

[0067] The preparation process of the coating 100 obtained in the above-mentioned Examples 1 to 8 and Comparative Examples 1 to 4 includes the following steps: S1: Weigh each raw material according to weight; S2: Add the pre-mixed fluororesin and blocked isocyanate composite slurry into the mixer, start stirring, disperse at a speed of 600-700 r / min for 10-15 minutes, increase the speed to 900-1100 r / min, add the colorant and wetting agent in sequence, and disperse for 15-25 minutes to obtain a mixed slurry; S3: Lower the rotation speed to 600-700 r / min, add the leveling agent, brightener, and degassing agent to the mixed slurry prepared in step S2 in sequence, disperse for 25-40 minutes, and mix evenly to obtain the base layer of the coating; S4: Add the sealing agent into another mixer, start stirring, and disperse it at a speed of 600-700 r / min for 10-15 minutes to obtain the sealing layer of the coating.

[0068] In order to make the mixing more uniform during the mixing stage, we can adopt the following two preferred implementations: (1) In step S2, the pre-prepared fluororesin and blocked isocyanate composite slurry is added to the mixer, stirring is started, and the mixture is dispersed at a speed of 600-630 r / min for 3-5 min, at a speed of 630-670 r / min for 3-5 min, and at a speed of 670-700 r / min for 5-10 min, and then the speed is increased to 900-1100 r / min.

[0069] (2) In step S3, the rotation speed is lowered, and a leveling agent, a brightener, and a degassing agent are sequentially added to the mixed slurry obtained in step S2 at a rotation speed of 600-630 r / min, and then dispersed for 5-10 min, dispersed for 5-8 min at a rotation speed of 630-670 r / min, and dispersed for 5-7 min at a rotation speed of 670-700 r / min to obtain a mixed slurry.

[0070] The above-mentioned staged improvement of the temperature is conducive to the full mixing of the substances, the obtained mixed liquid is more uniform, and the consistency of the overall coating effect is better.

[0071] The coatings 100 of Examples 1 to 6 and Comparative Examples 1 to 4 obtained by the above preparation method were subjected to paint adhesion tests to obtain the data in the following table.

[0072] Table 1 Porosity a (%) <![CDATA[Substrate layer thickness H1 (μm)]]> <![CDATA[Sealing layer thickness H2 (μm)]]> Contact angle θ (°) (H1×θ) / (H2×a) Is there a concave hole groove Paint adhesion (B) Example 1 5 15 5 5 3 have 5 Example 2 10 25 15 10 1.67 have 4 Example 3 3 20 10 10.5 7 have 5 Example 4 1 25 15 2 3.33 have 5 Example 5 2 25 5 10 25 have 3 Example 6 10 15 15 0.8 0.08 have 4 Example 7 0．5 20 7 4 22.86 have 3 Example 8 1 15 15 0.9 0.9 have 4 Comparative Example 1 5 15 5 5 3 none 4 Comparative Example 2 17 12 1 40 28.24 have 2 Comparative Example 3 10 5 20 1 0.025 have 1 Comparative Example 4 10 25 15 10 1.67 none 3 By analyzing the above table, we can know that: (1) When the coating 100 satisfies the following conditions: 0.08≤(H1×θ) / (H2×a)≤22.86, the paint adhesion is 3B or above; (2) When the coating 100 satisfies: 3≤(H1×θ) / (H2×a)≤7, the paint adhesion reaches the upper limit of 5B. At this time, the paint adhesion has reached the test limit; (3) When coating 100 satisfies: 0.08≤(H1×θ) / (H2×a)<3, the paint adhesion reaches 4B, which is suboptimal; (4) When coating 100 satisfies: 7<(H1×θ) / (H2×a)≤22.86, the paint adhesion reaches 3B, and the paint adhesion is basically up to standard; (5) When coating 100 satisfies: (H1×θ) / (H2×a)<0.08, the paint adhesion drops sharply to 1B; when 22.86<(H1×θ) / (H2×a), the paint adhesion is less than 3B.

[0073] (7) For the same coating formula, the paint adhesion of the coating with the inner concave groove will be improved by one level.

[0074] Based on the above analysis, when the coating is provided on the contact surface, the coating includes a base layer and a sealing layer, one side of the base layer is connected to the contact surface, and the other side of the base layer is connected to the sealing layer. The porosity of the coating is a%, the thickness of the base layer is H1 μm, the thickness of the sealing layer is H2 μm, and the contact angle between the base layer and the contact surface is θ°. The coating satisfies the following conditions: 0.08≤(H1×θ) / (H2×a)≤22.86; Among them, the coating satisfies at least one of the following inequalities: 15≤H1≤25; 0<θ≤10.5; 5≤H2≤15; 0<a≤10; the function of the sealing layer is to fill the pores and enhance the corrosion resistance. When the above inequalities are satisfied, the coating of the present invention is subjected to a paint adhesion test and the paint adhesion level is always maintained at 3B or above, which also makes the coating provided by the present invention have excellent wear resistance and corrosion resistance.

[0075] Test methods for each parameter: Porosity test: Tested in accordance with ISO14680-1:2000 standard.

[0076] Paint film thickness test: Test in accordance with GB / T 13452.2-92 standard.

[0077] Contact angle test: measured by a contact angle meter. The current mainstream algorithm is the Young-Laplace method. The Young-Laplace equation describes the relationship between the internal and external pressure difference of a closed interface and the curvature and interfacial tension of the interface. It can be used to accurately describe the outer contour of an axially symmetrical droplet, thereby calculating its contact angle.

[0078] Performance Testing Paint adhesion test: 1. First, use a utility knife or a crosshatch to scratch the paint layer in a cross-shaped pattern. Make one cut both horizontally and vertically, creating 100 small squares, each measuring 1mm x 1mm. The cuts on the crosshatch should reach the bottom layer of the paint.

[0079] 2. Use a brush to brush in diagonal directions five or six times to clean up small fragments, then stick tape on the incision and pull it apart. The adhesion of the tape is 350-400g / square meter.

[0080] 3. Finally, use a magnifying glass to observe the grid area and calculate the percentage of the peeled area at the edges of the cuts and intersections.

[0081] For the above paint adhesion test standards, please refer to the American National Standard ANSI / ASTM D3359-87 "Adhesion by Tape Test".

[0082] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A coating for a decorative colored aluminum plate, the decorative colored aluminum plate having a contact surface (200), the coating (100) being provided on the contact surface (200), characterized in that: The coating (100) comprises a base layer (110) and a sealing layer (120), one side of the base layer (110) is connected to the contact surface (200), and the other side of the base layer (110) is connected to the sealing layer (120); The porosity of the coating (100) is a%, the thickness of the base layer (110) is H1 μm, the thickness of the sealing layer (120) is H2 μm, the contact angle between the base layer (110) and the contact surface (200) is θ°, and the coating (100) satisfies: 0.08≤(H1×θ) / (H2×a)≤22.86; Wherein, the coating (100) satisfies at least one of the following inequality relationships: （1）15≤H1≤25； (2) 0<θ≤10.5; （3）5≤H2≤15； （4）0＜a≤10。 2. The coating for decorative colored aluminum plate according to claim 1, characterized in that: The contact surface (200) has a maximum arc M° and a minimum arc N°, and the contact surface (200) satisfies 0≤MN≤3.5, 90<M<180, and 90<N<180.

3. The coating for decorative colored aluminum plate according to claim 1, characterized in that: The contact surface (200) includes a curved surface (210) and a plurality of inner concave grooves (220), wherein the inner concave grooves (220) have a bottom wall (221) and a surrounding wall (222), wherein the surrounding wall (222) is arranged around the circumference of the bottom wall (221), and the bottom wall (221) and the surrounding wall (222) form a receiving space (230), and the cross-sectional area of ​​the surrounding wall (222) decreases from the side of the surrounding wall (222) away from the bottom wall (221) to the side of the surrounding wall (222) connected to the bottom wall (221), and the side of the surrounding wall (222) away from the bottom wall (221) is connected to the curved surface (210); A portion of the coating (100) fills the accommodating space (230), and another portion of the coating (100) is disposed on the surface of the arc portion (210).

4. The coating for decorative colored aluminum plate according to claim 1, characterized in that: The accommodating space (230) is in a truncated cone shape, the accommodating space (230) has a circular opening, the bottom wall (221) is a circular bottom wall, the surrounding wall (222) is a truncated cone surrounding wall, the coating (100) enters the accommodating space through the circular opening and fills the accommodating space (230), and the diameter of the circular opening is greater than the diameter of the circular bottom wall.

5. The coating for decorative colored aluminum plate according to claim 4, characterized in that: A chamfered portion (223) is provided on the side of the surrounding wall (222) away from the bottom wall (221), and the radian of the chamfered portion (223) is π / 4 to π / 3. One end of the chamfered portion (223) is connected to the side of the surrounding wall (222) away from the bottom wall (221), and the other end of the chamfered portion (223) is connected to the arc surface portion (210).

6. The coating for decorative colored aluminum plate according to claim 1, characterized in that: The coating comprises the following components in parts by weight: 45-61 parts of fluororesin, 10-14 parts of blocked isocyanate, 0.5-1.5 parts of leveling agent, 0.5-1.5 parts of brightener, 0.3-0.5 parts of degassing agent, 16-36 parts of colorant, 2-4 parts of wetting agent, and 10-20 parts of sealing agent.

7. The coating for decorative colored aluminum plate according to claim 6, characterized in that: The wetting agent is a succinate block copolymer or a polyether siloxane copolymer.

8. The coating for decorative colored aluminum plate according to claim 6, characterized in that: The leveling agent is one of acrylic, silicone and fluorocarbon compounds.

9. The coating for decorative colored aluminum plate according to claim 6, characterized in that: The brightener is a neutral brightener; the degassing agent is one of benzoin, stearic acid, and hydrogenated castor oil derivatives; and the sealing agent is one of phenol resin and epoxy resin.

10. A method for preparing a coating according to any one of claims 1 to 9, characterized in that: S1: Weigh each raw material according to weight; S2: Add the pre-mixed fluororesin and blocked isocyanate composite slurry into the mixer, start stirring, disperse at a speed of 600-700 r / min for 10-15 minutes, increase the speed to 900-1100 r / min, add the colorant and wetting agent in sequence, and disperse for 15-25 minutes to obtain a mixed slurry; S3: Lower the rotation speed to 600-700 r / min, add the leveling agent, brightener, and degassing agent to the mixed slurry prepared in step S2 in sequence, disperse for 25-40 minutes, and mix evenly to obtain the base layer of the coating; S4: Add the sealing agent into another mixer, start stirring, and disperse it at a speed of 600-700 r / min for 10-15 minutes to obtain the sealing layer of the coating.

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