Natural environment-friendly high-hardness coating and preparation method thereof

Abstract

The invention relates to the technical field of environment-friendly coatings, in particular to a natural environment-friendly high-hardness coating and a preparation method thereof. The composition comprises the following components: a composite filler; the auxiliaries comprise a sodium polyacrylate dispersing agent, a polyether modified silicon defoaming agent and a hydroxyethyl cellulose thickening agent; an alcohol ester-12 film forming auxiliary agent; a tannic acid modified acrylate emulsion; according to the natural environment-friendly high-hardness coating provided by the invention, through the synergistic effect of all the components, multiple balance of environment friendliness, high hardness and flexibility is realized. The tannic acid modified acrylate emulsion serves as a base material of the coating, and a system is endowed with double advantages through chemical modification: tannic acid serves as a natural polyphenol compound, a benzene ring framework in a molecular structure of the tannic acid and an acrylate chain segment can form a rigid blending network, and basic hardness is provided for the coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environment-friendly coatings, in particular to a natural and environment-friendly high-hardness coating and a preparation method thereof. BACKGROUND

[0002] As an important material in the fields of construction, industry and home, the performance of coatings directly affects the service life, decorative effect and functionality of the coating. With the improvement of environmental awareness and the strictness of industry standards, the development of coatings with high hardness, environmental friendliness and good construction performance has become a key direction for the development of the industry.

[0003] Traditional coatings often face the problem of insufficient hardness, and simply increasing hardness will increase the brittleness of the coating. In addition, most traditional coatings rely on petroleum-based resins as film-forming materials, which not only have environmental problems of VOC (volatile organic compound) emission exceeding the standard, but also have difficulty in meeting the needs of high-end application scenarios in terms of mechanical properties.

[0004] In the prior art, common means to improve the hardness of coatings include adding inorganic fillers (such as titanium dioxide, calcium carbonate) or using resin systems with high crosslinking density. However, the simple addition of inorganic fillers often leads to uneven dispersion of fillers and weak interfacial bonding with the resin matrix, thereby reducing the toughness of the coating; traditional crosslinking resins can increase hardness, but usually require the addition of curing agents or high-temperature curing, which not only increases the process complexity, but also may release harmful substances.

[0005] The present application proposes a natural and environment-friendly high-hardness coating system based on tannic acid modified acrylate emulsion, which systematically solves the above technical problems through raw material modification, component ratio optimization and process innovation, aiming at the defects of insufficient hardness of coatings, difficulty in balancing environmental friendliness and mechanical properties, and poor filler synergistic effect in the prior art. SUMMARY

[0006] The purpose of the present application is to provide a natural and environment-friendly high-hardness coating and a preparation method thereof. The environment-friendly coating prepared by the present application not only has good adhesion, but also has high surface hardness.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions: The present application provides a natural and environment-friendly high-hardness coating, which comprises the following components: The composite filler accounts for 16-24% of the total mass of the coating, and is composed of modified nano-titanium dioxide and flaky mica powder in a mass ratio of 3:1; The auxiliary agent accounts for 2.5-4.5% of the total mass of the coating, and the auxiliary agent includes polyacrylic acid sodium dispersant, polyether modified silicon defoaming agent and hydroxyethyl cellulose thickening agent in a mass ratio of 2:1:1; Alcohol ester-12 film forming aid, 1.1-1.4% of the total mass of the paint; Tannic acid modified acrylate emulsion, the balance of the total mass of the paint.

[0008] Further, the preparation method of the tannic acid modified acrylate emulsion comprises: Mix butyl acrylate and methyl methacrylate with a mass ratio of 3:2, emulsify at 80℃ with 1.5% of the total mass of the acrylate monomer emulsifier OP-10 to form a pre-emulsion; React tannic acid and epichlorohydrin with a molar ratio of 1:1.8-2.0 at 80℃ with 5-6% of the mass of tannic acid sodium hydroxide as basic catalyst for 3-3.5 hours to form tannic acid glycidyl ether; Add the tannic acid glycidyl ether prepared above to the pre-emulsion, first add 0.5% of the mass of the acrylate monomer potassium persulfate initiator at 65℃ to initiate the reaction for 2 hours, then warm up to 85℃ for 2 hours, and then naturally cool to room temperature to obtain.

[0009] Further, the preparation method of the modified nano titanium dioxide is as follows: use 2-3% of the mass of nano titanium dioxide silane coupling agent KH-570, treat nano titanium dioxide in an ethanol-water mixed solution at 60℃ for 2 hours, then filter, wash and dry to obtain.

[0010] Further, the volume ratio of ethanol to water in the ethanol-water mixed solution is 1:1.

[0011] Further, the activation method of the sheet mica powder is as follows: plasma bombard the sheet mica powder for 15-20 minutes with a power of 100W.

[0012] Further, the treatment gas is neon.

[0013] Further, the preparation method of the composite filler is as follows: mix the modified nano titanium dioxide with the activated sheet mica powder in a mass ratio of 3:1-1.2, stir at 50℃ with a rotation speed of 500rpm for 30 minutes to embed the modified nano titanium dioxide into the micropores of the mica.

[0014] The preparation method of the natural and environmentally friendly high-hardness coating comprises the following steps: First, add the tannic acid modified acrylate emulsion into the stirring container and stir at a rotation speed of 500rpm; Then, add the composite filler dried at 60℃ for 2 hours into the stirring container in multiple equal portions; Then, add the auxiliary agent and the film forming aid in sequence and continue stirring for 20 minutes; During the stirring process, keep the temperature at 25-30℃; After the stirring is completed, the paint is filtered through a 200-mesh screen; The filtered paint is used after standing for 12 hours under sealed conditions.

[0015] Further, the order of adding the auxiliary agents is to add the sodium polyacrylate dispersant first, stir for 5 minutes, and then sequentially add the polyether modified silicon defoaming agent and the hydroxyethyl cellulose thickening agent.

[0016] Further, the stirring container is cleaned and dried before use, the cleaning uses ethanol wiping, the drying temperature is 60 DEG C, and the drying time is 1 hour.

[0017] Compared with the prior art, the beneficial effects of the present application are: 1. The natural environment-friendly high-hardness paint provided by the present application achieves multiple balances of environmental protection, high hardness and flexibility through the synergistic effect of various components. Among them, the tannic acid modified acrylate emulsion as the paint base gives the system double advantages through chemical modification. On the one hand, tannic acid as a natural polyphenolic compound, the benzene ring skeleton in its molecular structure can form a rigid blending network with the acrylate segment, providing a solid foundation for the hardness of the coating; on the other hand, the tannic acid glycidyl ether is generated, effectively blocking the flocculation activity of the phenolic hydroxyl group, solving the pH sensitivity problem of tannic acid in the water system, the modification process not only retains the natural environmental protection property of tannic acid, but also enhances the compatibility with the acrylate emulsion through chemical bonding, forming a crosslinked network that has rigidity and elasticity after solidification, laying the foundation for the performance of the coating, especially the hardness performance, from the molecular level.

[0018] 2. The composite filler compounded by the modified nano titanium dioxide and the activated flaky mica powder is the key component for improving the hardness of the paint. The nano titanium dioxide modified by the silane coupling agent KH-570 forms a hydrophobic organic layer on the surface, which is combined with the acrylate matrix through chemical bonds to avoid agglomeration, and is uniformly distributed in the coating as a nano-enhancing point to play a rigid particle reinforcing role; the flaky mica powder activated by neon plasma bombardment forms a microporous structure on the surface, providing pinning sites for the nano titanium dioxide, and the two build a three-dimensional reinforcing network through the structure design of nano particles embedded in micrometer flake layers. This double-scale structure synergizes, breaks through the limitations of traditional single filler, and the nano particles improve the micro-hardness of the coating, and the micrometer flake layer absorbs stress through interlayer sliding, so that the coating remains flexible while the hardness is improved.

[0019] 3. Synergistic effect of the introduced additive system. Sodium polyacrylate dispersant optimizes the dispersibility of composite fillers through electrostatic repulsion, avoiding agglomeration and uneven performance; polyether-modified silicone defoamer eliminates bubbles in paint preparation and improves coating density; hydroxyethyl cellulose thickener adjusts the viscosity of the system and improves application performance. The three are combined to form a stable additive synergistic system. Alcohol ester-12 film-forming aid lowers the film-forming temperature of the emulsion and promotes the fusion of tannic acid-modified acrylic emulsion particles, forming a continuous and dense paint film, further enhancing the coating hardness and weather resistance.

[0020] 4. The process of plasma bombardment activation of mica powder and modification of nano-titanium dioxide with silane coupling agents enhances the bonding force between the filler and the matrix at the level of interface chemistry and microstructure. When the coating is subjected to external impact, the stress can be effectively transferred through the filler-matrix interface, avoiding damage caused by local stress concentration and ensuring the stability of the coating performance. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention belongs to the field of environmentally friendly coatings technology, specifically relating to a high-hardness natural environmentally friendly coating based on tannic acid-modified acrylic emulsion and reinforced with composite fillers.

[0023] Main raw materials

[0024] This invention provides a natural and environmentally friendly high-hardness coating, comprising the following components: a composite filler, accounting for 16-24% of the total mass of the coating, wherein the composite filler is composed of modified nano-titanium dioxide and flake mica powder in a mass ratio of 3:1; additives, accounting for 2.5-4.5% of the total mass of the coating, wherein the additives include sodium polyacrylate dispersant, polyether-modified silicone defoamer, and hydroxyethyl cellulose thickener in a mass ratio of 2:1:1; alcohol ester-12 film-forming aid, accounting for 1.1-1.4% of the total mass of the coating; and tannic acid-modified acrylate emulsion, accounting for the remainder of the total mass of the coating.

[0025] The preparation method of the tannin-modified acrylate emulsion comprises the following steps: mixing butyl acrylate and methyl methacrylate in a mass ratio of 3:2, adding an emulsifier OP-10 accounting for 1.5% of the total mass of the acrylate monomers at 80 DEG C to perform emulsification, and forming a pre-emulsion; reacting tannin and epichlorohydrin in a molar ratio of 1:1.8-2.0 at 80 DEG C with sodium hydroxide accounting for 5-6% of the mass of the tannin as an alkaline catalyst for 3-3.5 hours to generate tannin glycidyl ether; adding the prepared tannin glycidyl ether into the pre-emulsion, first adding potassium persulfate accounting for 0.5% of the mass of the acrylate monomers at 65 DEG C to initiate the reaction for 2 hours, then increasing the temperature to 85 DEG C for aging for 2 hours, and naturally cooling to room temperature to obtain the tannin-modified acrylate emulsion.

[0026] The preparation method of the modified nano-titanium dioxide comprises the following steps: using silane coupling agent KH-570 accounting for 2-3% of the mass of the nano-titanium dioxide, treating the nano-titanium dioxide in an ethanol-water mixed solution (the volume ratio of ethanol to water is 1:1) at 60 DEG C for 2 hours, then performing suction filtration, washing and drying to obtain the modified nano-titanium dioxide.

[0027] The activation method of the flaky mica powder comprises the following steps: bombarding the flaky mica powder with a plasma (the processing gas is neon) with a power of 100 W for 15-20 minutes.

[0028] The preparation method of the composite filler comprises the following steps: mixing the modified nano-titanium dioxide and the activated flaky mica powder in a mass ratio of 3:1-1.2, stirring at 50 DEG C and a rotating speed of 500 r / min for 30 minutes to embed the modified nano-titanium dioxide into the micropores of the mica.

[0029] The preparation method of the coating comprises the following steps: first adding the tannin-modified acrylate emulsion into a stirring container and stirring at a rotating speed of 500 r / min; then adding the composite filler dried at 60 DEG C for 2 hours into the stirring container in multiple equal portions; then adding additives and film-forming aids in sequence and continuously stirring for 20 minutes (the sequence of adding the additives is: first adding polyacrylic acid sodium dispersant, stirring for 5 minutes, then adding polyether-modified silicon defoaming agent and hydroxyethyl cellulose thickening agent in sequence); in the stirring process, the temperature is kept at 25-30 DEG C; after the stirring is completed, the coating is filtered through a 200-mesh screen; and the filtered coating is used after being kept in a sealed condition for 12 hours. The stirring container is cleaned and dried before use, the cleaning is performed by wiping with ethanol, the drying temperature is 60 DEG C, and the drying time is 1 hour.

[0030] The coating provided by the application uses the tannin-modified acrylate emulsion to provide an environmentally-friendly base and hardness basis, and the composite filler uses a double-scale structure to synergistically improve the hardness, so that the natural environmental friendliness of the coating is ensured.

[0031] To further illustrate the present application, the following examples and comparative examples are described in detail below. Example 1

[0032] Coating components (by total mass) Tannin-modified acrylate emulsion: 62% Composite filler (modified nano-titanium dioxide and flaky mica powder mass ratio 3:1): 20% Auxiliary agent (polyacrylic acid sodium dispersant: polyether modified silicone defoamer: hydroxyethyl cellulose thickening agent is 2:1:1): 3% Alcohol ester-12 film forming agent: 1.2% Preparation of tannin-modified acrylate emulsion Mix butyl acrylate and methyl methacrylate with a mass ratio of 3:2, emulsify at 80℃ with 1.5% of the total mass of acrylate monomers of emulsifier OP-10 to form a pre-emulsion; react tannin and epichlorohydrin with a molar ratio of 1:1.8 at 80℃ with 5% of the mass of tannin sodium hydroxide as a basic catalyst for 3 hours to form tannin glycidyl ether; add tannin glycidyl ether to the pre-emulsion, first add 0.5% of the mass of acrylate monomers of potassium persulfate initiator at 65℃ to initiate the reaction for 2 hours, then warm up to 85℃ for 2 hours, and cool naturally to room temperature.

[0033] Preparation of composite filler Use 2% of the mass of nano-titanium dioxide of silane coupling agent KH-570 to treat nano-titanium dioxide in ethanol-water mixed solution (ethanol to water volume ratio 1:1) at 60℃ for 2 hours, filter, wash, and dry; bombard flaky mica powder with a power of 100W neon plasma for 15 minutes; mix modified nano-titanium dioxide and activated flaky mica powder with a mass ratio of 3:1 at 50℃ with stirring at 500 revolutions per minute for 30 minutes.

[0034] Preparation of coating Mix the components according to the preparation method described above, filter, and stand to obtain the coating. Example 2

[0035] Coating components (by total mass) Tannin-modified acrylate emulsion: 58% Composite filler (modified nano-titanium dioxide and flaky mica powder mass ratio 3:1): 22% Auxiliary agent (polyacrylic acid sodium dispersant: polyether modified silicone defoamer: hydroxyethyl cellulose thickening agent is 2:1:1): 3.5% Alcohol ester-12 film forming agent: 1.3% Preparation of tannin-modified acrylate emulsion Butyl acrylate and methyl methacrylate with a mass ratio of 3:2 were mixed, and emulsified at 80°C by adding 1.5% of emulsifier OP-10 based on the total mass of acrylate monomers to form a pre-emulsion; tannic acid and epichlorohydrin were reacted at 80°C for 3.2 hours in a molar ratio of 1:1.9 with sodium hydroxide with a mass of 5.5% of tannic acid as an alkaline catalyst to generate tannic acid glycidyl ether; the tannic acid glycidyl ether was added to the pre-emulsion, first at 65°C, 0.5% of potassium persulfate initiator based on the mass of acrylate monomers was added to initiate the reaction for 2 hours, then warmed up to 85°C for 2 hours of curing, and naturally cooled to room temperature.

[0036] Preparation of composite filler The nano-titanium dioxide was treated with 2.5% of silane coupling agent KH-570 based on the mass of nano-titanium dioxide in an ethanol-water mixed solution (volume ratio of ethanol to water 1:1) at 60°C for 2 hours, and then filtered, washed, and dried; the sheet mica powder was bombarded by neon plasma with a power of 100W for 18 minutes; the modified nano-titanium dioxide and the activated sheet mica powder were mixed in a mass ratio of 3:1 at 50°C with stirring at 500 rpm for 30 minutes.

[0037] Preparation of coating According to the above preparation method, the components were mixed, filtered, and left to obtain the coating. Example 3

[0038] Coating components (based on the total mass) Tannic acid modified acrylate emulsion: 56% Composite filler (modified nano-titanium dioxide and sheet mica powder in a mass ratio of 3:1): 24% Auxiliary agent (polyacrylic acid sodium dispersant: polyether modified silicone defoaming agent: hydroxyethyl cellulose thickening agent in a ratio of 2:1:1): 4% Alcohol ester-12 film forming aid: 1.4% Preparation of tannic acid modified acrylate emulsion Butyl acrylate and methyl methacrylate with a mass ratio of 3:2 were mixed, and emulsified at 80°C by adding 1.5% of emulsifier OP-10 based on the total mass of acrylate monomers to form a pre-emulsion; tannic acid and epichlorohydrin were reacted at 80°C for 3.5 hours in a molar ratio of 1:2.0 with sodium hydroxide with a mass of 6% of tannic acid as an alkaline catalyst to generate tannic acid glycidyl ether; the tannic acid glycidyl ether was added to the pre-emulsion, first at 65°C, 0.5% of potassium persulfate initiator based on the mass of acrylate monomers was added to initiate the reaction for 2 hours, then warmed up to 85°C for 2 hours of curing, and naturally cooled to room temperature.

[0039] Preparation of composite filler The nano-titanium dioxide is treated with 3% silane coupling agent KH-570 in an ethanol-water mixture solution (volume ratio of ethanol to water is 1:1) at 60°C for 2 hours, and then filtered, washed and dried; the sheet mica powder is bombarded with neon plasma at a power of 100W for 20 minutes; the modified nano-titanium dioxide and the activated sheet mica powder are mixed at a mass ratio of 3:1, and stirred at 50°C at a speed of 500 revolutions per minute for 30 minutes.

[0040] Preparation of the coating The components are mixed according to the above preparation method, filtered, and left to stand to obtain the coating. Example 4

[0041] Coating components (based on total mass) Tannic acid modified acrylate emulsion: 60% Composite filler (mass ratio of modified nano-titanium dioxide to sheet mica powder is 3:1.1): 18% Auxiliary agent (sodium polyacrylate dispersant: polyether modified silicone defoaming agent: hydroxyethyl cellulose thickening agent is 2:1:1): 3.8% Alcohol ester-12 film forming agent: 1.2% Preparation of tannic acid modified acrylate emulsion The same as in Example 1.

[0042] Preparation of composite filler The nano-titanium dioxide is treated with 2.2% silane coupling agent KH-570 in an ethanol-water mixture solution (volume ratio of ethanol to water is 1:1) at 60°C for 2 hours, and then filtered, washed and dried; the sheet mica powder is bombarded with neon plasma at a power of 100W for 16 minutes; the modified nano-titanium dioxide and the activated sheet mica powder are mixed at a mass ratio of 3:1.1, and stirred at 50°C at a speed of 500 revolutions per minute for 30 minutes.

[0043] Preparation of the coating The components are mixed according to the above preparation method, filtered, and left to stand to obtain the coating. Example 5

[0044] Coating components (based on total mass) Tannic acid modified acrylate emulsion: 59% Composite filler (mass ratio of modified nano-titanium dioxide to sheet mica powder is 3:1.2): 19% Auxiliary agent (sodium polyacrylate dispersant: polyether modified silicone defoaming agent: hydroxyethyl cellulose thickening agent is 2:1:1): 3.6% Alcohol ester-12 film forming agent: 1.3% Preparation of tannic acid modified acrylate emulsion The same as in Example 2.

[0045] Composite filler preparation The nano-titanium dioxide was treated with 2.8% by mass of silane coupling agent KH-570 in an ethanol-water mixture solution (volume ratio of ethanol to water 1:1) at 60°C for 2 hours, and then filtered, washed, and dried. The modified nano-titanium dioxide was mixed with the activated flaky mica powder at a mass ratio of 3:1.2, and stirred at 50°C and 500 rpm for 30 minutes.

[0046] Coating preparation According to the above preparation method, the components were mixed, filtered, and left to obtain the coating.

[0047] Comparative Example 1 Coating components (by total mass) Tannic acid-modified acrylate emulsion: 62% Composite filler (mass ratio of unmodified nano-titanium dioxide to flaky mica powder 3:1): 20% Auxiliary agent (sodium polyacrylate dispersant: polyether-modified silicone defoaming agent: hydroxyethyl cellulose thickening agent at 2:1:1): 3% Alcohol ester-12 film-forming agent: 1.2% Preparation method The nano-titanium dioxide was not treated with silane coupling agent KH-570, and the other steps were the same as in Example 1.

[0048] Comparative Example 2 Coating components (by total mass) Tannic acid-modified acrylate emulsion: 62% Composite filler (mass ratio of modified nano-titanium dioxide to flaky mica powder 1:1): 20% Auxiliary agent (sodium polyacrylate dispersant: polyether-modified silicone defoaming agent: hydroxyethyl cellulose thickening agent at 2:1:1): 3% Alcohol ester-12 film-forming agent: 1.2% Preparation method The mass ratio of modified nano-titanium dioxide to flaky mica powder in the composite filler was 1:1, and the other steps were the same as in Example 1.

[0049] Comparative Example 3 Coating components (by total mass) Tannic acid-modified acrylate emulsion: 62% Composite filler (mass ratio of modified nano-titanium dioxide to unactivated flaky mica powder 3:1): 20% Auxiliary agent (sodium polyacrylate dispersant: polyether-modified silicone defoaming agent: hydroxyethyl cellulose thickening agent at 2:1:1): 3% Alcohol ester-12 film forming aid: 1.2% Preparation method The flaky mica powder was not subjected to plasma bombardment activation treatment, and the other steps were the same as in Example 1.

[0050] Test Test one: pencil hardness test Test method The paint was applied to a standard test panel, and after drying for 7 days, a pencil of different hardness (from 6H to 6B) was used to draw across the paint film at an angle of 45° with a pressure of 1 kg, and the hardest pencil grade that could scratch the paint film was recorded, and the results were as follows:

[0051] As can be seen from Table 1, the pencil hardness of Examples 1-5 all reached 2H or more, among which Example 3 reached 5H, indicating that the paint had high hardness. Comparative Example 1, which was not modified nanometer titanium dioxide, had poor interfacial adhesion with the resin matrix, resulting in a significant decrease in hardness to 2H. Comparative Example 2, in which the ratio of nanometer titanium dioxide to mica powder in the composite filler was not appropriate, had weakened synergistic effect of the double-scale structure, and the hardness decreased to 3H. Comparative Example 3, in which the flaky mica powder was not activated, lacked a microporous structure on the surface, and the modified nanometer titanium dioxide could not be embedded to form a pinning structure, and the hardness was only 2H.

[0052] Test two: pendulum damping test Test method Using a Konig pendulum, the time (in seconds) required for the pendulum to swing from 5° to 2° was measured at 25°C, and the longer the time, the higher the hardness of the paint film, and the results were as follows:

[0053] As can be seen from Table 2, the pendulum damping time of Examples 1-5 was all above 185s, and Example 3 reached 205s, indicating that the paint film had excellent hardness. Comparative Example 1, in which the nanometer titanium dioxide was not modified, had poor filler dispersion and was not tightly combined with the matrix, and the damping time was only 120s. Comparative Example 2, in which the filler ratio was unbalanced, could not form an effective support structure, and the damping time was 145s. Comparative Example 3, in which the mica powder was not activated and the modified nanometer titanium dioxide could not be embedded, lacked synergistic effect between fillers, and the damping time was 130s, all of which were significantly lower than the examples.

[0054] Test three: falling ball impact test Test method The paint is coated on a 100mm x 100mm x 0.3mm tin plate, dried for 7 days, and then a 500g steel ball is allowed to freely fall from different heights to impact the paint film surface using a falling ball impact tester, and the paint film is observed for cracking, peeling and other damage. The minimum impact height (unit: cm) that can cause damage to the paint film is recorded, and the higher the impact height, the better the balance between hardness and flexibility of the paint film. The results are as follows:

[0055] As can be seen from Table 3, the impact damage critical height of Examples 1-5 is all above 50cm, among which Example 3 reaches 60cm, indicating that the paint film can simultaneously balance hardness and flexibility when impacted. The double-scale structure of the composite filler in the present application forms a synergistic buffer system, and the grafting network of the tannin-modified acrylate emulsion enhances the matrix toughness. In Comparative Example 1, the unmodified nano-titanium dioxide has defects at the interface with the matrix, and stress concentration during impact results in a critical height of only 30cm; in Comparative Example 2, the filler ratio is unbalanced (mass ratio of modified nano-titanium dioxide to mica powder 1:1), the double-scale support structure is invalid, and the critical height drops to 35cm; in Comparative Example 3, the unactivated mica powder lacks a micropore pinning structure, the filler is loosely combined with the matrix, and the critical height is as low as 28cm, all of which are significantly lower than the level of the examples.

[0056] In the description of the present specification, the description of the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0057] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the present specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A natural, environmentally friendly, high hardness coating, characterized in that, The coating comprises the following components: Composite filler, 16-24% of the total mass of the coating, the composite filler is compounded by modified nano titanium dioxide and flaky mica powder in a mass ratio of 3:1; Auxiliary agent, 2.5-4.5% of the total mass of the coating, the auxiliary agent includes polyacrylic acid sodium dispersant, polyether modified silicone defoaming agent and hydroxyethyl cellulose thickening agent in a mass ratio of 2:1:1; Alcohol ester-12 film forming agent, 1.1-1.4% of the total mass of the coating; Tannic acid modified acrylic emulsion, the rest of the total mass of the coating.

2. The natural, environmentally friendly, high hardness coating of claim 1, wherein, The preparation method of the tannic acid modified acrylic emulsion comprises: Mixing butyl acrylate and methyl methacrylate in a mass ratio of 3:2, adding 1.5% of the total mass of the acrylic monomer emulsifier OP-10 at 80℃ for emulsification to form a pre-emulsion; Reacting tannic acid with epichlorohydrin in a molar ratio of 1:1.8-2.0 at 80℃ with 5-6% of the mass of tannic acid sodium hydroxide as alkaline catalyst for 3-3.5 hours to generate tannic acid glycidyl ether; Adding the prepared tannic acid glycidyl ether into the pre-emulsion, first adding 0.5% of the mass of the acrylic monomer potassium persulfate initiator at 65℃ to initiate the reaction for 2 hours, then heating to 85℃ for 2 hours, and naturally cooling to room temperature to obtain.

3. The natural, environmentally friendly, high hardness coating of claim 1, wherein, The preparation method of the modified nano titanium dioxide is: using 2-3% of the mass of nano titanium dioxide silane coupling agent KH-570, treating nano titanium dioxide in an ethanol-water mixed solution at 60℃ for 2 hours, then filtering, washing and drying to obtain.

4. The natural, environmentally friendly, high hardness coating of claim 3, wherein, The volume ratio of ethanol to water in the ethanol-water mixed solution is 1:

1.

5. The natural, environmentally friendly, high hardness coating of claim 3, wherein, The activation method of the flaky mica powder is: plasma bombarding the flaky mica powder for 15-20 minutes at a power of 100W.

6. The natural, environmentally friendly, high hardness coating of claim 5, wherein, The treatment gas is neon.

7. The natural, environmentally friendly, high hardness coating of claim 5, wherein, The preparation method of the composite filler is: mixing the modified nano titanium dioxide with the activated flaky mica powder in a mass ratio of 3:1-1.2, stirring at 50℃ and a speed of 500 revolutions per minute for 30 minutes to embed the modified nano titanium dioxide into the micropores of the mica.

8. A process for the preparation of a natural, environmentally friendly, high hardness coating as claimed in any one of claims 1 to 7, characterized in that, The method comprises the following steps: First, add the tannic acid modified acrylic emulsion into the stirring container and stir at a speed of 500 revolutions per minute; Then, add the composite filler dried at 60℃ for 2 hours into the stirring container in multiple equal portions; Then, add the auxiliary agent and the film forming agent in sequence and continue stirring for 20 minutes; During the stirring process, keep the temperature at 25-30℃; After the stirring is completed, filter the coating through a 200 mesh screen; The filtered coating is used after being placed under sealed conditions for 12 hours.

9. The method of claim 8, wherein the natural, environmentally friendly, high hardness coating is prepared by, The order of adding the auxiliary agent is: first add the polyacrylic acid sodium dispersant, stir for 5 minutes, then add the polyether modified silicone defoaming agent and the hydroxyethyl cellulose thickening agent in sequence.

10. The method of claim 8, wherein the natural, environmentally friendly, high hardness coating is prepared by, The stirring container is cleaned and dried before use, the cleaning uses ethanol wiping, the drying temperature is 60℃, and the drying time is 1 hour.

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