Method for preparing coating composition

Abstract

The method for preparing a coating composition according to an embodiment of the present application comprises: a step of preparing a first solution by mixing a zirconium precursor and a first polyhydric alcohol; a step of preparing a second solution by adding a binder to the first solution; and a step of preparing a third solution by adding ethanol, a polysorbate, and a second polyhydric alcohol to the second solution, wherein mathematical formula 1 is satisfied.

Description

Method for preparing a coating composition

[0001] This application claims the benefit of Korean Patent Application No. 10-2024-0005139, filed with the Korean Intellectual Property Office on January 12, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to a method for producing a coating composition.

[0003] Metal structures can be applied to a variety of fields, including lightweighting, soundproofing, thermal insulation, energy absorption, filtration, and catalysis. In some cases, passivation may be necessary. While it's generally easy to coat a passivation layer on flat substrates like glass or silicon, the highly uneven surfaces of metal structures present a challenge, making it difficult to form a uniform passivation layer on such surfaces.

[0004] In addition, zirconium dioxide has a very high melting point and a relatively low coefficient of thermal expansion, so it is highly resistant to chemical reactions and environmental degradation. Due to these characteristics, it can be applied as a passivating material in various applications to protect the material surface to prevent chemical deterioration such as corrosion and oxidation.

[0005] Therefore, in this technical field, there is a need for development of a technology for forming a passivation layer on a metal structure using zirconium dioxide.

[0006] The present application seeks to provide a method for preparing a coating composition that can be applied for various purposes.

[0007] One embodiment of this application is:

[0008] A step of preparing a first solution by mixing a zirconium precursor and a first polyhydric alcohol;

[0009] A step of preparing a second solution by adding a binder to the first solution; and

[0010] A step of preparing a third solution by adding ethanol, polysorbic acid, and a second polyhydric alcohol to the second solution,

[0011] A method for manufacturing a coating composition satisfying the following mathematical formula 1 is provided.

[0012] [Mathematical Formula 1]

[0013] (Zr molar concentration in the second solution) × (weight ratio of the second solution to the total weight of the second solution, ethanol, and polysorbic acid) < 0.11

[0014] In addition, another embodiment of the present application is

[0015] Steps to prepare the material; and

[0016] A step of coating, drying, and firing a coating composition manufactured according to the manufacturing method on the surface of the above substrate to form a zirconium dioxide coating layer on the surface of the above substrate.

[0017] A method for manufacturing a zirconium dioxide coating layer including:

[0018] According to one embodiment of the present application, a method for producing a coating composition capable of uniformly forming a zirconium dioxide coating layer on the surface of a substrate such as a metal structure and performing the role of a passivation layer can be provided.

[0019] In addition, by forming a zirconium dioxide coating film on the surface of a metal structure using a coating composition manufactured according to one embodiment of the present application, a metal structure that is applied and used in various fields such as weight reduction, sound insulation, insulation energy absorption, and filtration catalyst can be provided.

[0020] Figure 1 is a diagram showing a surface SEM image of a metal structure coated according to Example 1.

[0021] Figure 2 is a diagram showing a surface SEM image of a metal structure coated according to Example 6.

[0022] Figure 3 is a diagram showing an XRD image of a powder sample obtained by heat-treating the dried powder of the coating composition of Example 8 at 700°C for 3 hours.

[0023] Figure 4 is a diagram showing an SEM image of a powder sample obtained by heat-treating the dried powder of the coating composition of Example 8 at 700°C for 3 hours.

[0024] Figure 5 is a diagram showing a surface SEM image of a metal structure coated according to Example 8.

[0025] Figure 6 is a diagram showing a high-magnification SEM image of a passivation film coated according to Example 8.

[0026] Figure 7 is a diagram showing a surface SEM image of a metal structure coated according to Comparative Example 2.

[0027] Figure 8 is a diagram showing a surface SEM image of a metal structure coated according to Comparative Example 3.

[0028] Figure 9 is a diagram showing a surface SEM image of a metal structure coated according to Comparative Example 5.

[0029] Hereinafter, the present specification will be described in more detail.

[0030] In this specification, when it is said that a member is located “on” another member, this includes not only cases where the member is in contact with the other member, but also cases where another member exists between the two members.

[0031] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless specifically stated otherwise.

[0032] A method for manufacturing a coating composition according to one embodiment of the present application comprises the steps of: preparing a first solution by mixing a zirconium precursor and a first polyhydric alcohol; preparing a second solution by adding a binder to the first solution; and preparing a third solution by adding ethanol, polysorbic acid, and a second polyhydric alcohol to the second solution, and satisfies the following mathematical formula 1.

[0033] [Mathematical Formula 1]

[0034] (Zr molar concentration in the second solution) × (weight ratio of the second solution to the total weight of the second solution, ethanol, and polysorbic acid) < 0.11

[0035] A method for preparing a coating composition according to one embodiment of the present application includes a step of preparing a first solution by mixing a zirconium precursor and a first polyhydric alcohol.

[0036] The above zirconium precursor is a precursor of zirconium dioxide constituting the coating layer, and the molar ratio of zirconium can be controlled by controlling the content thereof. The zirconium precursor may be zirconium propoxide, but is not limited thereto.

[0037] The first polyhydric alcohol may include at least one of 1,4-butanediol, diethylene glycol, and triethylene glycol. In addition, the first polyhydric alcohol may include 1,4-butanediol and diethylene glycol simultaneously, may include 1,4-butanediol and triethylene glycol simultaneously, and may include 1,4-butanediol, diethylene glycol, and triethylene glycol simultaneously.

[0038] The step of preparing the first solution may be performed at a temperature of 70°C to 130°C, and may be performed at a temperature of 80°C to 100°C. If the step of preparing the first solution is performed at a temperature below 70°C, the zirconium precursor may not dissolve well, which is not preferred. In addition, if the step of preparing the first solution exceeds 130°C, particle precipitation due to a hydration reaction may occur, which is not preferred.

[0039] A method for producing a coating composition according to one embodiment of the present application includes a step of producing a second solution by adding a binder to the first solution.

[0040] According to one embodiment of the present application, by adding a binder to the first solution, the adhesiveness of the coating layer manufactured can be improved, thereby preventing the detachment phenomenon of the zirconium dioxide thin film even after high-temperature heat treatment.

[0041] The above binder may include polyvinylpyrrolidone (PVP).

[0042] The content of the above binder may be 1 wt% to 5 wt% based on the total weight of 1,4-butanediol applied as the first polyhydric alcohol, but is not limited thereto.

[0043] A method for producing a coating composition according to one embodiment of the present application includes a step of producing a third solution by adding ethanol, polysorbic acid, and a second polyhydric alcohol to the second solution.

[0044] The above polysorbic acid can function as a stabilizer and dispersant, and more specifically, can suppress aggregation of Zr particles and stabilize the sol. In addition, the second polyhydric alcohol can function to precipitate particles by substituting a portion of the Zr bound to the first polyhydric alcohol, such as 1,4-butanediol, diethylene glycol, or triethylene glycol, in the first solution with hydroxyl groups.

[0045] Based on the total weight of the second solution and ethanol, the content of the second solution may be 1 wt% to 40 wt%, and preferably 5 wt% to 30 wt%. When the content of the second solution is 1 wt% to 40 wt% based on the total weight of the second solution and ethanol, a coating layer can be uniformly and reproducibly formed when the composition is coated on the surface of a substrate such as a metal structure. When the content of the second solution exceeds 40 wt% based on the total weight of the second solution and ethanol, uneven gelation may occur during the drying process, which may block open pores / cells of the metal structure, and the adhesiveness of the dried thin film may be reduced, which is not preferable.

[0046] Based on the total weight of the second solution and ethanol, the content of the polysorbic acid may be 5 wt% to 45 wt%, and may be 10 wt% to 40 wt%. If the content of the polysorbic acid exceeds 45 wt% based on the total weight of the second solution and ethanol, the viscosity of the final composition increases, which may cause defects when coating a substrate such as a metal structure, and thus is not preferable.

[0047] The second polyhydric alcohol may include ethylene glycol.

[0048] Based on the total weight of the second solution and ethanol, the content of the second polyhydric alcohol may be 0.5 wt% to 10 wt%, and may be 1 wt% to 5 wt%. If the content of the second polyhydric alcohol is less than 0.5 wt% based on the total weight of the second solution and ethanol, the hydration reaction may occur very slowly, which may increase the process time for particle formation, and thus is not preferable. In addition, if the content of the second polyhydric alcohol exceeds 10 wt% based on the total weight of the second solution and ethanol, the hydration reaction may occur rapidly, which may cause the composition to turn into a paste, making it impossible to coat the surface of a metal structure, which is not preferable.

[0049] According to an embodiment of the present application, the coating composition may have a value of the above mathematical formula 1 of less than 0.11, 0.105 or less, or 0.1 or less. According to an embodiment of the present application, by satisfying the value of the above mathematical formula 1, a coating layer, which is a uniform zirconium dioxide thin film, can be uniformly formed on the surface of a substrate such as a metal structure. When the value of the above mathematical formula 1 is 0.11 or more, the composition itself may harden or turn into a paste due to excessive hydration reaction in the process of adding the second polyhydric alcohol, which is not preferable. Therefore, in the present application, it has been found that the state of the solution before adding the second polyhydric alcohol has the greatest influence on the process of coating the metal structure, and the inventors of the present invention conducted experiments under various conditions to numerically quantify the state of the solution before adding the second polyhydric alcohol, and derived the above mathematical formula 1 as a result.

[0050] In one embodiment of the present application, since the value of the above mathematical formula 1 must be satisfied, the concentration of zirconia must not be excessively increased in order to form a thick zirconium dioxide coating film. In addition, in one embodiment of the present application, the value of the above mathematical formula 1 can be lowered due to an increase in the degree of dispersion resulting from the addition of polysorbic acid, but the amount of ethanol must also be considered simultaneously, so it is necessary to appropriately adjust the contents of polysorbic acid and ethanol to satisfy the above mathematical formula 1.

[0051] In one embodiment of the present application, the pH of the coating composition may be 6.5 to 7.5, 6.8 to 7.2, or 7. By satisfying the pH range of the coating composition, chemical changes in the metal structure can be prevented.

[0052] In one embodiment of the present application, the coating composition can be applied as a passivation layer of a metal structure, a high-refractive coating layer of a glass substrate, a heat-shielding coating layer of a gas turbine, or a bioceramic coating layer of an artificial bone, and can be more preferably applied as a passivation layer of a metal structure.

[0053] The passivation layer of the above metal structure can be applied to metal structures with severe surface irregularities, and thus can be applied as a passivation material in various application fields to protect the material surface to prevent chemical deterioration such as corrosion and oxidation.

[0054] The high refractive index coating layer of the above glass substrate can be applied to control reflection of the glass substrate to prevent glare, and thus can be applied to smart glasses, etc.

[0055] The heat shielding coating layer of the above gas turbine can be applied to gas turbines for power generation and aviation to obtain an insulating effect.

[0056] The bioceramic coating layer of the above artificial bone can further improve biocompatibility by being applied to hydroxyapatite, which is an artificial bone.

[0057] In addition, a method for manufacturing a zirconium dioxide coating layer according to an embodiment of the present application includes a step of preparing a substrate; and a step of coating, drying, and firing a coating composition manufactured according to the manufacturing method on the surface of the substrate, thereby forming a zirconium dioxide coating layer on the surface of the substrate.

[0058] As described above, the zirconium dioxide coating film may be a passivation layer of a metal structure, a high-refractive index coating layer of a glass substrate, a heat-shielding coating layer of a gas turbine, or a bioceramics coating layer of an artificial bone, and it is more preferable that it be a passivation layer of a metal structure.

[0059] The above metal structure may be a metal foam containing NiCrAlFe, NiCrAl, SiC or α-Al2O3.

[0060] The above metal structure is a structure having various shapes, and has a small heat capacity and excellent heat transfer ability, so that it can be formed into a desired shape and used. The shape, size, etc. of the metal structure are not particularly limited, and the porosity of the metal structure can be 10% to 99%, 50% to 96%, or 85% to 96%. The pore size (cell size) of the metal structure can be 400 ㎛ to 1,500 ㎛, and 450 ㎛ to 1,400 ㎛. When the pore size of the metal structure is less than 400 ㎛, it may be difficult to coat the precursor solution, and when it exceeds 1,500 ㎛, the amount that can support the catalyst is reduced, which may be disadvantageous in the process, and thus is not preferable. The metal structure can be appropriately manufactured by a person skilled in the art using a method known in the art, taking into consideration the material, pore size, porosity, etc. of the above-mentioned metal structure.

[0061] In one embodiment of the present application, the method of coating the coating composition on the surface of the substrate may use a method known in the art, such as dip coating, wash coating, etc., but is not limited thereto.

[0062] In one embodiment of the present application, the drying may be performed at a temperature of 50°C to 250°C for 1 to 48 hours, or at a temperature of 70°C to 200°C for 5 to 36 hours, but is not limited thereto. In addition, the firing may be performed at a temperature of 400°C to 1,300°C in an air atmosphere for 1 to 30 hours, or at a temperature of 600°C to 900°C in an air atmosphere for 2 to 24 hours, but is not limited thereto. When the firing is performed at a temperature exceeding 1,300°C, the physical properties of the substrate itself may change, such as strength, length shrinkage, and pore size change, which may affect the quality of the zirconium dioxide coating film, and is therefore not preferable.

[0063] Hereinafter, examples will be provided to specifically explain the present application. However, the embodiments according to the present application may be modified in various ways, and the scope of the present application is not construed as being limited to the embodiments described below. The embodiments of the present application are provided to more fully explain the present application to those of average skill in the art.

[0064] <Example>

[0065] <Manufacturing Example 1>

[0066] Diethylene glycol (7.98 g) and zirconium propoxide (7.04 g) were added to 1,4-butanediol (25 mL) while stirring. The mixture was heated to 100°C while stirring, and maintained for 5 hours to prepare the first solution.

[0067] After that, the first solution was cooled to room temperature, and PVP (0.46 g, polyvinylpyrrolidone, M) was added as a binder. W = 40,000 g / mol) was added and mixed well until dissolved to prepare a second solution. The molar concentration of Zr in the second solution of Preparation Example 1 was 0.6 M.

[0068] <Manufacturing Example 2>

[0069] Diethylene glycol (6.37 g) and zirconium propoxide (5.62 g) were added to 1,4-butanediol (30 mL) while stirring. The mixture was heated to 80°C while stirring, and maintained for 5 hours to prepare the first solution.

[0070] After that, the first solution was cooled to room temperature, and PVP (0.55 g, polyvinylpyrrolidone, M) was added as a binder. W = 40,000 g / mol) was added and mixed well until dissolved to prepare a second solution. The molar concentration of Zr in the second solution of Preparation Example 2 was 0.4 M.

[0071] <Manufacturing Example 3>

[0072] Diethylene glycol (4.30 g) and zirconium propoxide (3.79 g) were added to 1,4-butanediol (40 mL) while stirring. The mixture was heated to 90°C while stirring, and maintained for 5 hours to prepare the first solution.

[0073] After that, the first solution was cooled to room temperature, and PVP (0.74 g, polyvinylpyrrolidone, M) was added as a binder. W = 40,000 g / mol) was added and mixed well until dissolved to prepare a second solution. The molar concentration of Zr in the second solution of Preparation Example 3 was 0.2 M.

[0074] <Manufacturing Example 4>

[0075] Diethylene glycol (10.61 g) and zirconium propoxide (9.36 g) were added to 1,4-butanediol (40 mL) while stirring. The mixture was heated to 90°C while stirring and maintained for 5 hours to prepare the first solution.

[0076] After that, the first solution was cooled to room temperature, and PVP (0.74 g, polyvinylpyrrolidone, M) was added as a binder. W = 40,000 g / mol) was added and mixed well until dissolved to prepare a second solution. The molar concentration of Zr in the second solution of Preparation Example 4 was 0.5 M.

[0077] <Example 1>

[0078] The second solution of the above Preparation Example 1 was well mixed with ethanol and polysorbic acid at a constant ratio as shown in Table 1 below. Ethylene glycol was additionally added to the mixture and stirred, and a particle precipitation reaction was performed to prepare a third solution, which is a dispersion. The pH of the third solution was 7.

[0079] After immersing the metal structure (NiCrAl) in the above third solution, ultrasonic vibration was applied for several seconds to remove air bubbles within the metal structure. Thereafter, dip-coating was performed, and after the dip-coating was completed, a centrifuge was used to remove the filtrate (300 rpm, 5 minutes). Thereafter, the coated metal structure was dried in an oven at 150°C. The dried metal structure was placed in a furnace and heated at 700°C in an air atmosphere for 6 hours, thereby manufacturing a metal structure having a zirconium dioxide coating film as a passivation layer on the surface of the metal structure.

[0080] <Examples 2 to 9 and Comparative Examples 1 to 6>

[0081] As shown in Table 1 below, the same procedure as Example 1 was followed, except that the type and content of the second solution and the content of ethanol, polysorbic acid, and ethylene glycol were adjusted. In addition, in Comparative Example 5, butanol was used instead of ethanol.

[0082] In addition, the values ​​of mathematical formula 1 of the above examples and comparative examples were calculated and shown in Table 2 below.

[0083] [Table 1]

[0084]

[0085] [Table 2]

[0086]

[0087] A: Zr molar concentration (M) in the second solution

[0088] B: Weight ratio of the second solution to the total weight of the second solution, ethanol, and polysorbic acid

[0089] Figure 1 is a diagram showing a surface SEM image of a metal structure coated according to Example 1.

[0090] Figure 2 is a diagram showing a surface SEM image of a metal structure coated according to Example 6.

[0091] Figure 3 is a diagram showing an XRD image of a powder sample obtained by heat-treating the dried powder of the coating composition of Example 8 at 700°C for 3 hours.

[0092] Figure 4 is a diagram showing an SEM image of a powder sample obtained by heat-treating the dried powder of the coating composition of Example 8 at 700°C for 3 hours.

[0093] Figure 5 is a diagram showing a surface SEM image of a metal structure coated according to Example 8.

[0094] Figure 6 is a diagram showing a high-magnification SEM image of a passivation film coated according to Example 8.

[0095] Figure 7 is a diagram showing a surface SEM image of a metal structure coated according to Comparative Example 2.

[0096] Figure 8 is a diagram showing a surface SEM image of a metal structure coated according to Comparative Example 3.

[0097] Figure 9 is a diagram showing a surface SEM image of a metal structure coated according to Comparative Example 5.

[0098] As shown in the results of Figures 1, 2, and 5 below, by satisfying the value of the above mathematical formula 1, it can be confirmed that the coated zirconium dioxide film covers the surface of the metal structure well without showing defects such as cracks or pin holes. Due to the nature of the process for manufacturing the metal structure, many three-dimensional irregularities with large steps are inevitably formed, but despite the presence of these irregularities, the surface of the metal structure was coated very smoothly. In addition, the amount of coating on the surface of the metal structure may vary depending on the concentration and viscosity of the zirconia solution, coating conditions, etc., but it was confirmed that typically 1 to 3 wt% was coated. Due to this uniform coating film, the metal structure can be well chemically protected from the outside, which is similar to painting the surface of an automobile to prevent corrosion. In addition, if necessary, the thickness of the passivation film can be increased by increasing the number of coatings, thereby further enhancing the protective effect of the metal structure. In addition, when a catalyst is additionally coated on a metal structure on which a zirconium dioxide thin film is formed in this manner, the zirconium dioxide thin film acts as a barrier, thereby obtaining an effect of preventing some substances from diffusing from the metal structure to the catalyst layer.

[0099] After the coating process, a metal structure as a support layer exists. To facilitate crystalline phase analysis, the coating solution was dried separately and then heat-treated at 700°C to obtain a powder, which was then measured using XRD. As shown in the results in Fig. 3 below, it can be confirmed that the crystal structure of zirconium dioxide is a mixture of monoclinic and tetragonal systems. When the amount was calculated through Rietveld quantitative analysis, it was confirmed that the tetragonal system was approximately 85.5% and the orthorhombic system was approximately 14.5%.

[0100] In addition, as shown in the results of Fig. 4 below, the crystal grain size of zirconium dioxide was confirmed to be approximately 15 nm to 30 nm. The results of observing the zirconium dioxide passivation film coated on the metal structure with a high magnification SEM are shown in Fig. 6, and it can be confirmed that the crystal grain structure is similar to that of Fig. 4.

[0101] However, in the case of Comparative Examples 1, 4 and 6, since the value of the mathematical expression 1 was 0.11 or higher, gelation of the coating solution occurred severely over time, making the subsequent deep coating process impossible.

[0102] In addition, in the case of Comparative Examples 2 to 4, where polysorbic acid was not added, the uniformity of the coating film was very poor, as shown in Figures 7 and 8 below, and it could be confirmed that only a portion was coated, like an island, exposing the surface of the metal structure.

[0103] In addition, in the case of Comparative Example 5 where butanol was used instead of ethanol in the preparation of the third solution, a uniform coating film could not be formed due to a decrease in the dispersibility of the solution and an increase in surface energy, as shown in Figure 9 below.

Claims

1. A step of preparing a first solution by mixing a zirconium precursor and a first polyhydric alcohol; A step of preparing a second solution by adding a binder to the first solution; and A step of preparing a third solution by adding ethanol, polysorbic acid and a second polyhydric alcohol to the second solution, A method for manufacturing a coating composition satisfying the following mathematical formula 1: [Mathematical Formula 1] (Zr molar concentration in the second solution) × (Weight ratio of the second solution to the total weight of the second solution, ethanol, and polysorbic acid) < 0.11 2. A method for producing a coating composition according to claim 1, wherein the zirconium precursor is zirconium propoxide.

3. A method for producing a coating composition according to claim 1, wherein the first polyhydric alcohol comprises at least one of 1,4-butanediol, diethylene glycol, and triethylene glycol.

4. A method for producing a coating composition according to claim 1, wherein the step of preparing the first solution is performed at a temperature of 70°C to 130°C.

5. A method for producing a coating composition according to claim 1, wherein the binder comprises polyvinylpyrrolidone (PVP).

6. A method for producing a coating composition according to claim 1, wherein the second polyhydric alcohol contains ethylene glycol.

7. A method for producing a coating composition according to claim 1, wherein the pH of the coating composition is 6.5 to 7.

5.

8. A method for producing a coating composition according to claim 1, wherein the coating composition is applied as a passivation layer of a metal structure, a high refractive index coating layer of a glass substrate, a heat-shielding coating layer of a gas turbine, or a bioceramic coating layer of an artificial bone.

9. Step of preparing the equipment; and A step of coating, drying and firing a coating composition manufactured according to any one of claims 1 to 7 on the surface of the substrate to form a zirconium dioxide coating layer on the surface of the substrate. A method for manufacturing a zirconium dioxide coating layer comprising:

10. A method for manufacturing a zirconium dioxide coating layer according to claim 9, wherein the zirconium dioxide coating layer is a passivation layer of a metal structure, a high refractive index coating layer of a glass substrate, a heat shielding coating layer of a gas turbine, or a bioceramic coating layer of an artificial bone.

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