Quaternary ammonium salt-containing multifunctional coating composition as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of synthetic polymer materials, and particularly relates to a preparation method and application of a multifunctional coating composition. The coating composition comprises an epoxy quaternary ammonium salt grafted carbon nano tube A, a polysiloxane grafted carbon nano tube B and an emulsifier, and the coating composition comprises the following components in parts by mass: 2 to 4 parts of the epoxy quaternary ammonium salt grafted carbon nano tube A, 1 to 5 parts of the polysiloxane grafted multi-walled carbon nano tube B and 0.1 to 2 parts of the emulsifier. The coating composition disclosed by the invention is simple in preparation method, relatively good in stability, and relatively good in wear resistance and high temperature resistance during coating.

Description

Technical Field

[0001] This invention belongs to the field of materials technology for synthetic polymers, and particularly relates to a method for preparing and applying a multifunctional coating composition, specifically a multifunctional coating composition containing quaternary ammonium salt, polysiloxane and carbon nanotubes, and its preparation method and application. Background Technology

[0002] Nowadays, the rapid advancement of science and technology alongside modern industry has led to an increasing number of devices used in high-temperature environments, such as high-temperature furnaces, petroleum cracking towers, chimneys, aircraft engine casings, exhaust pipes, heat exchangers, and the decoration and protection of building curtain walls. If these devices are not protected and are directly exposed to high temperatures, the surface materials are easily oxidized and corroded. Once the surface materials are damaged, they need to be replaced promptly; otherwise, further damage to the internal structure of the equipment will occur.

[0003] Replacing the surface material of equipment is not only costly but also cumbersome. Therefore, pre-applying high-temperature resistant materials to the equipment surface can effectively prevent damage. Currently, it is common practice to apply one or more layers of high-temperature resistant coatings to the surface of high-temperature equipment to prevent damage to the surface material at high temperatures.

[0004] High-temperature resistant coatings are widely used in many fields such as construction, aerospace, metallurgy, and shipbuilding due to their excellent protective capabilities, low economic cost, diverse and simple construction methods (spraying, dipping, brushing, etc.), large-area construction, and easy operation. They have become one of the most important special functional materials.

[0005] The current high-temperature resistant coatings have the following drawbacks: 1. Poor chemical corrosion resistance: When exposed to chemical substances (such as acids and alkalis), the coating is prone to peeling or damage; 2. Poor abrasion resistance: At high temperatures, especially on surfaces frequently exposed to friction or wiping, the coating is easily worn or damaged; 3. Difficulty in coping with thermal expansion and contraction: When the material undergoes slight changes due to thermal expansion, the coating may crack and split; 4. Insufficient adhesion: The coating may lose good adhesion to the substrate under prolonged high-temperature conditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a multifunctional coating composition, its preparation method, and its application. The preparation method of this coating composition is simple, it has good stability, and the coating exhibits good wear resistance and high-temperature resistance.

[0007] To achieve its purpose, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a multifunctional coating composition comprising epoxy quaternary ammonium salt-grafted carbon nanotubes A, polysiloxane-grafted carbon nanotubes B, and an emulsifier.

[0009] According to an embodiment of the present invention, the coating composition comprises, by weight, 2 to 4 parts of epoxy quaternary ammonium salt-grafted carbon nanotubes A, 1 to 5 parts of polysiloxane-grafted multi-walled carbon nanotubes B, and 0.1 to 2 parts of emulsifier.

[0010] According to an embodiment of the present invention, the coating composition has a viscosity of less than 1800 centipoise at room temperature, preferably less than 1600 centipoise, for example, 1000 centipoise.

[0011] According to an embodiment of the present invention, the solid content of the coating composition is 20-50%, preferably 30-40%.

[0012] According to an embodiment of the present invention, the coating composition further includes a dispersant for forming a uniform dispersion with the epoxy quaternary ammonium salt-grafted carbon nanotubes A and the polysiloxane-grafted carbon nanotubes B.

[0013] According to an embodiment of the present invention, the dispersant is, for example, at least one selected from ethanol, propanol, isopropanol, and butanol, such as isopropanol.

[0014] According to an embodiment of the present invention, the carbon nanotubes A and B are independently selected from single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

[0015] According to an embodiment of the present invention, the carbon nanotubes A and B have a length of 10–30 micrometers, an inner diameter of 5–10 nanometers, and an outer diameter of 20–30 nanometers.

[0016] According to an embodiment of the present invention, the epoxy quaternary ammonium salt-grafted carbon nanotube A has the following structure:

[0017]

[0018] R1, R2, and R3 are independently selected from C1-C10 alkyl groups, preferably from C1-C6 alkyl groups, such as methyl, ethyl, propyl, isopropyl, butyl, etc.

[0019] According to an embodiment of the present invention, the polysiloxane-grafted carbon nanotube B has the following structure:

[0020]

[0021] R4, R5, R6, and R7 are independently selected from C1-C10 alkyl groups, preferably from C1-C6 alkyl groups, such as methyl, ethyl, propyl, isopropyl, butyl, etc.

[0022] As an example, R4, R5, R6, and R7 are independently selected from methyl groups, and the polysiloxane-grafted carbon nanotube B has the following structure:

[0023]

[0024] Wherein, n = 4 to 40, preferably n = 5 to 30, and even more preferably n = 10 to 20, for example 4, 6, 8, 10, 15, 20, 25.

[0025] According to an embodiment of the present invention, the coating composition comprises epoxy quaternary ammonium salt grafted carbon nanotubes A, polysiloxane grafted carbon nanotubes B, emulsifier, and dispersant.

[0026] According to an embodiment of the present invention, the emulsifier is selected from fatty alcohol polyoxyethylene alcohol, with the structural formula RO-(CH2CH2O). x -H, x is the degree of polymerization, x = 10-200, R is a C1-C20 alkyl group, preferably a C5-C15 alkyl group, for example, a C10 alkyl group.

[0027] According to an embodiment of the present invention, the emulsifier is selected from C 10 -O-(CH2CH2O) 30 -H, C 10 -O-(CH2CH2O) 50 -H, C 10 -O-(CH2CH2O) 70 -H, C 10 -O-(CH2CH2O) 90 One or more of -H, for example, C 10 -O-(CH2CH2O) 30 -H and C 10 -O-(CH2CH2O) 90 A mixture of -H.

[0028] According to an embodiment of the present invention, the C 10 -O-(CH2CH2O) 30 -H and C 10 -O-(CH2CH2O) 90 The mass ratio of -H is (1-4):(6-11), for example, 1:1 or 1:3.

[0029] Secondly, the present invention provides a method for preparing the above-mentioned multifunctional coating composition, comprising the following steps:

[0030] A dispersion of epoxy quaternary ammonium salt-grafted carbon nanotubes A, a dispersion of polysiloxane-grafted carbon nanotubes B, and an emulsifier are mixed to obtain a multifunctional coating composition.

[0031] According to an embodiment of the present invention, in the multifunctional coating composition, the epoxy quaternary ammonium salt grafted carbon nanotube A dispersion accounts for 20-40% of the total weight, and the polysiloxane grafted carbon nanotube B dispersion accounts for 10-50% of the total weight.

[0032] According to an embodiment of the present invention, the preparation method of the epoxy quaternary ammonium salt grafted carbon nanotube A dispersion includes the following steps: dissolving the epoxy quaternary ammonium salt in a dispersant to obtain an epoxy quaternary ammonium salt solution, adding carboxylated carbon nanotube A to react, and obtaining the epoxy quaternary ammonium salt grafted carbon nanotube A dispersion.

[0033] According to an embodiment of the present invention, the dispersant and carbon nanotube A have the definitions described above.

[0034] According to an embodiment of the present invention, the mass ratio of the epoxy quaternary ammonium salt to isopropanol is (1-8):(3-9), preferably the mass ratio of the epoxy quaternary ammonium salt to isopropanol is (1-5):(3-9), for example 6:5.

[0035] According to an embodiment of the present invention, the epoxy quaternary ammonium salt is dissolved in isopropanol at a temperature of 30–60°C, for example, 50°C.

[0036] According to an embodiment of the present invention, before the reaction of adding carboxylated carbon nanotube A, the following steps are further included: adding an acidic solution to the solution of the epoxy quaternary ammonium salt and adjusting the pH to 4-6, preferably the acidic solution is selected from formic acid, acetic acid, etc., for example, acetic acid.

[0037] According to an embodiment of the present invention, the epoxy quaternary ammonium salt is selected from epoxypropyl quaternary ammonium salt, which has the following structure:

[0038]

[0039] R1, R2, and R3 have the definitions described above.

[0040] As an example, the epoxy quaternary ammonium salt is selected from glycidyltrimethyl quaternary ammonium salt, which has the following structure:

[0041]

[0042] According to an embodiment of the present invention, the reaction of adding carboxylated carbon nanotubes A is carried out at a temperature of 30-80°C for a reaction time of 6-10 hours, for example, by stirring at a temperature of 50°C for 8 hours.

[0043] According to an embodiment of the present invention, the mass ratio of the epoxy quaternary ammonium salt to the carboxylated carbon nanotube A is (10-20):1, for example, 12:1.

[0044] According to an embodiment of the present invention, the preparation method of the polysiloxane-grafted carbon nanotube B dispersion includes the following steps: dissolving polyoxysilane in a dispersant to obtain a polyoxysilane solution, adding carboxylated carbon nanotube B, and obtaining a polysiloxane-grafted carbon nanotube B dispersion.

[0045] According to an embodiment of the present invention, the polyoxysilane is selected from vinyl-terminated polysiloxanes, which have the following structure:

[0046]

[0047] Among them, R4, R5, R6, and R7 have the definitions described above.

[0048] As an example, the polyoxysilane is a vinyl-terminated dimethyl polysiloxane, which has the following structure:

[0049]

[0050] According to an embodiment of the present invention, the mass ratio of the vinyl-terminated polysiloxane to the dispersant is (3-9):(4-9), preferably (3-9):(5-8), for example 1:1.

[0051] According to an embodiment of the present invention, the polyoxysilane is dissolved in a dispersant at a temperature of 30–60°C, for example, 50°C.

[0052] According to an embodiment of the present invention, before adding carboxylated carbon nanotubes B to the polyoxysilane solution, the method further includes the following step: adding sulfuric acid to the polyoxysilane solution to react and obtain an acidified polyoxysilane solution.

[0053] According to an embodiment of the present invention, the mass ratio of the polyoxysilane solution to dilute sulfuric acid is (3-6):(2-4).

[0054] According to an embodiment of the present invention, the reaction temperature of the polyoxysilane solution with dilute sulfuric acid is 100-150°C, and the reaction time is 5-10 h. Preferably, the reaction is carried out under stirring conditions.

[0055] According to an embodiment of the present invention, the concentration of the solution after the polyoxysilane solution reacts with dilute sulfuric acid is 2-30%.

[0056] According to an embodiment of the present invention, the temperature at which carboxylated carbon nanotubes B are added to an acidified polyoxysilane solution to obtain a dispersion of polysiloxane-grafted carbon nanotubes B is 100–150°C and the reaction time is 5–10 h.

[0057] According to an embodiment of the present invention, the mass ratio of the carboxylated carbon nanotube B to the acidified polyoxysilane solution is (1-9):(30-40).

[0058] According to an embodiment of the present invention, the concentration of the polysiloxane-grafted carbon nanotube B dispersion is 2-30%.

[0059] Thirdly, the present invention provides the above-mentioned multifunctional coating composition for use as a high-temperature resistant material, for example, for use in high-temperature resistant coatings.

[0060] Fourthly, the present invention provides a high-temperature resistant coating, the coating comprising the multifunctional coating composition described above.

[0061] According to an embodiment of the present invention, the coating is a water-based coating.

[0062] Beneficial effects

[0063] 1) The emulsion prepared by the present invention using epoxy quaternary ammonium salt, polysiloxane, and carbon nanotubes has the following significant advantages: First, the quaternary ammonium salt has significant antibacterial properties, which can improve the corrosion resistance and antibacterial ability of the coating layer; Second, polysiloxane itself has a special structure, and its main chain -Si-O-Si- belongs to the "inorganic structure". The bond energy of the Si-O bond is 462.0 kJm / ol, which is much higher than the bond energy of the C-C bond (346.9 kJm / ol). Therefore, the bond polarity is large, which plays a shielding role on the attached hydrocarbon group and improves the oxidation stability. Thus, the high-temperature resistant coating in the present invention has the dual advantages of organic and inorganic materials, such as good thermal stability, low glass transition temperature, high air permeability, excellent dielectric properties, good biocompatibility, and low surface properties; Third, the addition of carbon nanotubes can improve the thermal conductivity and wear resistance of the coating, while enhancing the mechanical strength and durability of the coating.

[0064] 2) This invention uses fatty alcohols and polyoxyethylene alcohols with different degrees of polymerization to form an emulsifier in a certain volume ratio, and successfully prepares a low-viscosity, transparent emulsion containing quaternary ammonium salts, polysiloxanes and carbon nanotubes. The high-temperature resistant emulsion of this invention has good stability and will not separate or break down even after long-term storage. Attached Figure Description

[0065] Figure 1 Infrared spectrum of epoxy quaternary ammonium salt modified;

[0066] Figure 2 Infrared spectrum of polysiloxane-modified polysiloxane;

[0067] Figure 3 Infrared spectra of emulsion products containing quaternary ammonium salts, polysiloxanes, and carbon nanotubes. Detailed Implementation

[0068] The following will provide a more detailed description of the materials, preparation methods, and applications of the present invention with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0069] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0070] The epoxy quaternary ammonium salt and polysiloxane used in the following examples were purchased from Aladdin Reagents Co., Ltd. Taking epoxy quaternary ammonium salt as an example, its molecular weight M... w =151.63, the structural formula is

[0071]

[0072] Taking vinyl-terminated dimethyl polysiloxane as an example, its structural formula is:

[0073]

[0074] Where n = 4 to 40.

[0075] In the following examples, the polymer structure was characterized by infrared spectroscopy; thermal stability was determined by thermogravimetric analysis; and viscosity was determined by rotational viscometer.

[0076] Example 1

[0077] Add 12 g of epoxy quaternary ammonium salt (11.76% of the total mass) and 10 g of isopropanol to a 250 ml three-necked reaction flask equipped with a thermometer port, a sampling port, and a condenser port. Stir and heat to 50 °C. After the epoxy quaternary ammonium salt is completely dissolved, add 0.25 mL of [the solution is missing from the original text]. 3 Adjust the pH of the reaction solution to 6.0 with acetic acid at a concentration of mol / L, add 1 gram of carboxylated carbon nanotubes with a length of 10–30 μm, an inner diameter of 5–10 nm, and an outer diameter of 20–30 nm, and continue stirring at 50 °C for 8 hours to prepare an epoxy quaternary ammonium salt grafted carbon nanotube solution (solution 5).

[0078] Infrared spectrum of epoxy quaternary ammonium salt grafted carbon nanotubes ( Figure 1In the spectrum, the 1270–1010 cm⁻¹ range did not appear. -1 The absorption peak of COC with h epoxy group is observed at 1733 cm⁻¹. -1 An absorption peak for -COO- (C=O) appeared at [location missing]. A peak at 1570 cm⁻¹ was observed in the spectrum. -1 The presence of carbon nanotube absorption, including a characteristic absorption peak of -COO-C=O, indicates that the epoxy groups in the epoxy polysiloxane reacted with the carboxyl groups of the carbon nanotubes.

[0079] In a 250ml three-necked reaction flask equipped with a thermometer port, a sampling port, and a condenser port, 12 g of polysiloxane containing Si-O-Si repeating units (11.76% of the total mass) and 10 g of isopropanol were added. The mixture was stirred and heated to 50°C. After the polysiloxane containing Si-O-Si repeating units was completely dissolved, 80 mol / L sulfuric acid was added, and the temperature was raised to 110°C. Stirring was continued for 12 hours. Then, 1 g of carboxylated carbon nanotubes with a length of 10–30 μm, an inner diameter of 5–10 nm, and an outer diameter of 20–30 nm were added. Stirring was continued for 12 hours to prepare polysiloxane-grafted multi-walled carbon nanotubes containing Si-O-Si repeating units (solution 4).

[0080] Infrared spectrum of polysiloxane-grafted multi-walled carbon nanotubes ( Figure 2 The infrared spectrum showed bands, and their assignments are as follows: (1) 802 cm⁻¹ -1 The peak appearing at 2963 cm⁻¹ is the absorption peak of the rocking vibration of CH in Si-CH₃, which is one of the characteristic peaks of polysiloxane; (2) 2963 cm⁻¹ -1 The peak appearing at 1746 cm⁻¹ is the absorption peak of the stretching vibration of CH; (3) at 1746 cm⁻¹ -1 An absorption peak for -COO- (C=O) appeared at [location missing]. Furthermore, the original 1695–1630 cm⁻¹ [value missing] was also observed. -1 The C=C absorption peak has disappeared. The presence of three characteristic absorption peaks and the disappearance of one characteristic peak in the spectrum indicate that a reaction occurred between the polysiloxane and the carboxylated carbon nanotubes.

[0081] Solution 4 and solution 5 were mixed at a mass ratio of 1:1, with each solution having a mass of 6g. The mixture was stirred and heated to 110°C, then refluxed for 12 hours to obtain solution 6.

[0082] Two fatty alcohol polyoxyethylene compounds with degrees of polymerization of 30 and 90 were mixed at a mass ratio of 1:3 to prepare an emulsifier, wherein the mass of the compound with a degree of polymerization of 30 was 2g and the mass of the compound with a degree of polymerization of 90 was 6g. The emulsifier and solution 6 were mixed at a mass ratio of 1:2 and stirred evenly to obtain the final product, a multifunctional emulsion.

[0083] The viscosity of the obtained multifunctional emulsion was 1000 mPa·s (25℃), and no stratification occurred during the emulsion preparation.

[0084] Polyester fiber strips with a length of 10 cm and a width of 2 cm were used as test objects. The bending stiffness of the uncoated strip sample (Comparative Example 1) was 414 mN (warp); 721 mN (weft), with a wrinkle recovery angle of 178.47°. The bending stiffness of the strip sample coated with 5 ml of the multifunctional emulsion prepared in this embodiment and dried (Test Example 1) was 368 mN (warp); 624 mN (weft), with a wrinkle recovery angle of 212.56°, indicating that the strip coated with the multifunctional emulsion had increased flexibility. The antibacterial rate of the strip coated with the multifunctional emulsion against Escherichia coli was 57.8%, and the antibacterial rate against Staphylococcus aureus was 46.3%. The thermal conductivity of the emulsion was 365% higher than that without carbon nanotubes.

[0085] Thermogravimetric analysis was performed on Test Example 1 and Comparative Example 1: The samples were heated from 25°C to 200°C at a rate of 10°C per minute, and the weight loss rate of the samples during the heating process was tested. The weight loss rate of Comparative Example 1 was 5.62%, and the weight loss rate of Test Example 1 was 2.38%.

[0086] Contact angle tests showed that the contact angle of PU synthetic leather with a length of 10cm and a width of 2cm and based on polyester fiber without emulsion was 107.5°, while the contact angle of PU synthetic leather after applying 5ml of the multifunctional emulsion prepared in this embodiment was 71°, indicating improved hydrophilicity.

[0087] Example 2

[0088] The method in this embodiment is basically the same as that in embodiment 1, except that the mass ratio of solution 4 to solution 5 is 2:1, wherein the mass of solution 4 is 9g and the mass of solution 5 is 4.5g.

[0089] The multifunctional emulsion prepared in this embodiment has a viscosity of 950 mPa·s (25℃), and no stratification occurred during the emulsion preparation. Polyester fiber strips with a length of 10 cm and a width of 2 cm were used as test objects. The bending stiffness of the uncoated strip sample (Comparative Example 2) was 414 mN (warp) and 721 mN (weft), with a wrinkle recovery angle of 178.47°. The bending stiffness of the strip sample coated with 5 ml of the multifunctional emulsion prepared in this embodiment (Test Example 2) was 374 mN (warp) and 656 mN (weft), with a wrinkle recovery angle of 204.13°, indicating that the flexibility of the strip sample increased after coating with the multifunctional emulsion. Test Example 2 showed an antibacterial rate of 53.4% ​​against Escherichia coli and 41.8% against Staphylococcus aureus. The thermal conductivity of the emulsion was increased by 372% compared to the one without carbon nanotubes.

[0090] Thermogravimetric analysis was performed on Test Example 2 and Comparative Example 2: The weight loss rate of the samples was measured during the heating process from 25°C to 200°C at a rate of 10°C per minute. The weight loss rate of Comparative Example 2 was 5.44%, and the weight loss rate of Test Example 2 was 2.73%.

[0091] Contact angle tests showed that the contact angle of uncoated PU synthetic leather with a length of 10cm and a width of 2cm and based on polyester fiber was 107.5°, while the contact angle of coated PU synthetic leather was 68°, indicating improved hydrophilicity.

[0092] Example 3:

[0093] The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of solution 6 and emulsifier is 1:1, wherein the mass of solution 6 is 6g and the mass of emulsifier is 6g.

[0094] The multifunctional emulsion prepared in this embodiment has a viscosity of 1300 mPa·s (25℃), and no stratification occurred during the emulsion preparation. Polyester fiber strips with a length of 10 cm and a width of 2 cm were used as test objects. The bending stiffness of the uncoated strip sample (Comparative Example 3) was 414 mN (warp) and 721 mN (weft), with a wrinkle recovery angle of 178.47°. The bending stiffness of the strip sample coated with 5 ml of the multifunctional emulsion prepared in this embodiment (Test Example 3) was 356 mN (warp) and 642 mN (weft), with a wrinkle recovery angle of 210.33°, indicating that the flexibility of the strip sample coated with the multifunctional emulsion increased. Test Example 3 showed an antibacterial rate of 52.7% against Escherichia coli and 41.2% against Staphylococcus aureus. The thermal conductivity of the emulsion was 321% higher than that without carbon nanotubes.

[0095] Thermogravimetric analysis was performed on Test Example 3 and Comparative Example 3: the weight loss rate of the samples was tested during the process of heating from 25°C to 200°C at a rate of 10°C per minute. The weight loss rate of Comparative Example 3 was 5.98%, and the weight loss rate of Test Example 3 was 3.11%.

[0096] Contact angle tests showed that the contact angle of uncoated PU synthetic leather with a length of 10cm and a width of 2cm and based on polyester fiber was 107.5°, while the contact angle of coated PU synthetic leather was 73°, indicating improved hydrophilicity.

[0097] Example 4

[0098] The preparation method of this embodiment is basically the same as that of Example 1, except that the two fatty alcohol polyoxyethylene compounds in the emulsifier have a degree of polymerization of 30 and 90, respectively, and a mass ratio of 1:1. The fatty alcohol polyoxyethylene compound with a degree of polymerization of 30 has a mass of 5g, and the fatty alcohol polyoxyethylene compound with a degree of polymerization of 90 has a mass of 5g.

[0099] The multifunctional emulsion prepared in this embodiment has a viscosity of 1200 mPa·s (25℃), and no stratification occurred during the emulsion preparation. Polyester fiber strips with a length of 10 cm and a width of 2 cm were used as test objects. The bending stiffness of the uncoated strip sample (Comparative Example 4) was 414 mN (warp) and 721 mN (weft), with a wrinkle recovery angle of 178.47°. The bending stiffness of the strip sample coated with 5 ml of the multifunctional emulsion prepared in this embodiment (Test Example 4) was 377 mN (warp) and 668 mN (weft), with a wrinkle recovery angle of 207.29°, indicating that the flexibility of the strip sample coated with the multifunctional emulsion increased. Test Example 4 showed an antibacterial rate of 61.1% against Escherichia coli and 49.4% against Staphylococcus aureus. The thermal conductivity of the emulsion was 312% higher than that without carbon nanotubes.

[0100] Thermogravimetric analysis was performed on Test Example 4 and Comparative Example 4. The weight loss rate of the samples was measured during the heating process from 25°C to 200°C at a rate of 10°C per minute. The weight loss rate of Comparative Example 4 was 6.32%, and the weight loss rate of Test Example 4 was 3.32%.

[0101] Contact angle tests showed that the contact angle of PU synthetic leather with a length of 10cm and a width of 2cm and based on polyester fiber without emulsion was 107.5°, while the contact angle of PU synthetic leather after emulsion application was 79°, indicating improved hydrophilicity.

[0102] Example 5

[0103] The preparation method in this embodiment is basically the same as that in Example 1, except that the temperature for preparing solution 5 is increased to 60°C and the temperature for preparing solution 6 is increased to 150°C.

[0104] The resulting emulsion had a viscosity of 800 mPa·s (25℃) and did not exhibit stratification. Polyester fiber strips with a length of 10 cm and a width of 2 cm were used as test subjects. The fabric strip sample without the emulsion (Comparative Example 5) had a bending stiffness of 414 mN (warp) and 721 mN (weft), with a wrinkle recovery angle of 178.47°. The fabric strip sample coated with 5 ml of the multifunctional emulsion prepared in this example (Test Example 5) had a bending stiffness of 379 mN (warp) and 653 mN (weft), with a wrinkle recovery angle of 214.74°, indicating that the fabric strip sample coated with the multifunctional emulsion showed increased flexibility. Test Example 5 showed an antibacterial rate of 56.1% against Escherichia coli and 44.22% against Staphylococcus aureus. The thermal conductivity of the emulsion was 374% higher than that without carbon nanotubes.

[0105] Thermogravimetric analysis was performed on Test Example 5 and Comparative Example 5. The weight loss rate of the samples was measured during the heating process from 25°C to 200°C at a rate of 10°C per minute. The weight loss rate of Comparative Example 5 was 6.84%, and the weight loss rate of Test Example 5 was 3.51%.

[0106] Contact angle tests showed that the contact angle of PU synthetic leather with a length of 10cm and a width of 2cm and based on polyester fiber without emulsion was 107.5°, while the contact angle of PU synthetic leather after emulsion application was 76°, indicating improved hydrophilicity.

[0107] The specific embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above exemplary embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A multifunctional coating composition, characterized in that, The coating composition comprises epoxy quaternary ammonium salt-grafted carbon nanotubes A, polysiloxane-grafted carbon nanotubes B, and an emulsifier. Preferably, by weight, the coating composition comprises 2 to 4 parts of epoxy quaternary ammonium salt-grafted carbon nanotubes A, 1 to 5 parts of polysiloxane-grafted multi-walled carbon nanotubes B, and 0.1 to 2 parts of emulsifier.

2. The multifunctional coating composition according to claim 1, characterized in that, The epoxy quaternary ammonium salt-grafted carbon nanotube A has the following structure: R1, R2, and R3 are independently selected from C1-C10 alkyl groups. Preferably, the polysiloxane-grafted carbon nanotube B has the following structure: R4, R5, R6, and R7 are independently selected from C1-C10 alkyl groups. Preferably, R4, R5, R6, and R7 are independently selected from methyl groups, and the polysiloxane-grafted carbon nanotube B has the following structure: Where n = 4 to 40.

3. The multifunctional coating composition according to claim 1, characterized in that, The emulsifier is selected from fatty alcohol polyoxyethylene alcohol, with the structural formula RO-(CH2CH2O). x -H, x is the degree of polymerization, x = 10-200, and R is a C1-C20 alkyl group. Preferably, the emulsifier is selected from C 10 -O-(CH2CH2O) 30 -H, C 10 -O-(CH2CH2O) 50 -H, C 10 -O-(CH2CH2O) 70 -H, C 10 -O-(CH2CH2O) 90 One or more of -H.

4. The multifunctional coating composition according to any one of claims 1-3, characterized in that, The solid content of the coating composition is 20-50%, and the viscosity of the coating composition at room temperature is less than 1800 centipoise. Preferably, the coating composition further includes a dispersant, wherein the dispersant is at least one selected from ethanol, propanol, isopropanol, and butanol.

5. A method for preparing a multifunctional coating composition according to any one of claims 1-4, comprising the following steps: A dispersion of epoxy quaternary ammonium salt-grafted carbon nanotubes A, a dispersion of polysiloxane-grafted carbon nanotubes B, and an emulsifier were mixed to obtain a multifunctional coating composition. Preferably, in the multifunctional coating composition, the epoxy quaternary ammonium salt-grafted carbon nanotube A dispersion accounts for 20-40% of the total weight, and the polysiloxane-grafted carbon nanotube B dispersion accounts for 10-50% of the total weight.

6. The preparation method according to claim 5, characterized in that, The preparation method of the epoxy quaternary ammonium salt grafted carbon nanotube A dispersion includes the following steps: dissolving the epoxy quaternary ammonium salt in a dispersant to obtain an epoxy quaternary ammonium salt solution, adding carboxylated carbon nanotube A to react, and obtaining the epoxy quaternary ammonium salt grafted carbon nanotube A dispersion. Preferably, when the dispersant is isopropanol, the mass ratio of the epoxy quaternary ammonium salt to isopropanol is (1-8):(3-9). Preferably, before adding carboxylated carbon nanotubes A, the reaction further includes the following step: adding an acidic solution to the solution of the epoxy quaternary ammonium salt to adjust the pH to 4-6.

7. The preparation method according to claim 6, characterized in that, The epoxy quaternary ammonium salt is selected from epoxypropyl quaternary ammonium salt, and has the following structure: Preferably, the mass ratio of the epoxy quaternary ammonium salt to the carboxylated carbon nanotube A is (10-20):

1.

8. The preparation method according to claim 6 or 7, characterized in that, The preparation method of the polysiloxane-grafted carbon nanotube dispersion B includes the following steps: dissolving polyoxysilane in a dispersant to obtain a polyoxysilane solution, adding carboxylated carbon nanotubes B, and obtaining the polysiloxane-grafted carbon nanotube dispersion B. Preferably, the polyoxysilane is selected from vinyl-terminated polysiloxanes, which have the following structure: Preferably, the mass ratio of the vinyl-terminated polysiloxane to the dispersant is (3-9):(4-9). Preferably, before adding carboxylated carbon nanotubes B to the polyoxysilane solution, the method further includes the following step: adding sulfuric acid to the polyoxysilane solution to react and obtain an acidified polyoxysilane solution.

9. The preparation method according to claim 8, characterized in that, The mass ratio of the polyoxysilane solution to dilute sulfuric acid is (3-6):(2-4). Preferably, the reaction temperature of the polyoxysilane solution with sulfuric acid is 100-150°C, and the reaction time is 5-10 hours. Preferably, the temperature at which carboxylated carbon nanotubes B are added to the acidified polyoxysilane solution to obtain a dispersion of polysiloxane-grafted carbon nanotubes B is 100–150°C, and the reaction time is 5–10 h.

10. A high-temperature resistant coating, the coating comprising the multifunctional coating composition according to any one of claims 1-4 or the multifunctional coating composition prepared by the method according to any one of claims 5-9. Preferably, the coating is a water-based coating.

Images