Coating with good high temperature resistance and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a coating with good high temperature resistance and a preparation method of the coating. A resin; a functional additive; through reasonable component design, the performance defects of existing coatings are effectively overcome, and the environment-friendly high-temperature-resistant coating not only has excellent environment friendliness, but also has excellent high-temperature resistance. According to the invention, the plant fiber-nano silicon dioxide composite material is introduced, and the pretreated bamboo fiber is used as a base material, so that not only is natural skeleton support provided, but also the binding force with other components can be enhanced after surface modification; and the nano silicon dioxide improves the compactness and the mechanical property of the coating through a filling effect and an enhancing effect. The rosin modified epoxy resin is used as a film-forming substance, so that the excellent adhesive force and chemical resistance of the epoxy resin are reserved, and the compatibility with plant fibers is improved by introducing rosin.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a coating with good high-temperature resistance and a preparation method thereof. BACKGROUND

[0002] Existing coatings play an important role in the fields of construction, furniture, industrial protection, etc., and need to meet the green and environmentally friendly development trend. Compared with traditional solvent-based coatings, existing coatings usually adopt water-based systems, bio-based raw materials or low VOC (volatile organic compounds) components, which can effectively reduce the negative impact on human health and the ecological environment, and is the key direction for the sustainable development of the coating industry.

[0003] Introducing plant materials into coatings is one of the important paths for the development of existing green coatings. Plant materials are widely available, renewable, and have natural biodegradability, which can reduce the dependence on non-renewable resources such as petroleum in coating production, and significantly reduce the carbon footprint of products. In addition, some plant materials (such as cellulose, lignin, etc.) have certain mechanical properties and functionality, which can be expected to endow coatings with unique physicochemical properties and improve the ecological compatibility of coatings.

[0004] However, when plant materials are introduced into coatings in the prior art, there are still many technical problems. On the one hand, the surface of plant materials (such as natural fibers) usually contains a large number of hydrophilic groups, which have poor compatibility with the resins commonly used in coatings (especially non-polar resins), leading to the formation of interface defects in the coating, which in turn affects the adhesion of the coating to the substrate. On the other hand, the mechanical strength of plant materials is low, and they are prone to swelling in humid environments, which significantly reduces the wear resistance and water resistance of the coating, making it difficult to meet the requirements of durability in actual applications. In addition, existing coatings also have problems such as insufficient high-temperature resistance, which limits the popularization and application of coatings. SUMMARY

[0005] The purpose of the present application is to provide a coating with good high-temperature resistance.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A coating with good high-temperature resistance, consisting of the following components by weight: 30-40 parts of a plant fiber-nano-silica composite material, which is obtained by compounding nano-silica with bamboo fiber as a substrate; 20-30 parts of a resin, which is a rosin-modified epoxy resin; 8-10 parts of a functional additive, which is a mixture of hydroxyethyl cellulose, nano-zinc oxide and polyether-modified siloxane defoaming agent in a mass ratio of 4-6:1:2.

[0007] As a further technical solution, the nano-silica particles have a diameter of 60-70nm.

[0008] As a further technical solution, the bamboo fiber is prepared through a multi-stage pretreatment process: (1) Cleaning and impurity removal: After ultrasonic cleaning with deionized water, the bamboo is vacuum dried at 60℃ until the moisture content is ≤8%; The ultrasonic cleaning parameters are: 30kHz, 15min; (2) Compound enzymatic hydrolysis: Cellulase and hemicellulase were mixed at a mass ratio of 3:1 and hydrolyzed at 50℃ and pH 4.8-5.2 for 2 hours; the solid-liquid ratio of the enzymatic hydrolysis system was 1:15-20. The cellulase has an enzyme activity of 200-300 U / g; the hemicellulase has an enzyme activity of 150-200 U / g. (3) Microwave-assisted steam explosion: After pretreatment with 800W microwave for 3 minutes, the bamboo fiber with a diameter of 10-20μm was obtained by steam explosion treatment at 180℃ and 0.8MPa. (4) Low temperature bleaching: use 3wt% hydrogen peroxide to bleach at 40℃ for 30min, the whiteness is ≥85%, after filtration, washing until neutral, and drying, the result is obtained.

[0009] As a further technical solution, the preparation method of the rosin-modified epoxy resin is as follows: rosin and bisphenol A type epoxy resin are mixed at a mass ratio of 1:5-6, and 1.2-1.6% of boron trifluoride diethyl ether catalyst is added. The mixture is reacted at 140-150℃ for 2.5-3 hours under nitrogen protection. After cooling to 60℃, 0.5-0.6% of epichlorohydrin is added, and the reaction is continued for 1 hour to obtain the rosin-modified epoxy resin.

[0010] As a further technical solution, the rosin is hydrogenated rosin with an acid value of 160-170 mgKOH / g, and the epoxy equivalent of the bisphenol A type epoxy resin is 180-200 g / eq. As a further technical solution, the functional additives contain: nano zinc oxide with a particle size of 20-30 nm; and hydroxyethyl cellulose with a molecular weight of 100,000-200,000.

[0011] A method for preparing a coating with good high-temperature resistance includes the following steps: (1) Preparation of plant fiber-nano silica composite material: pretreated bamboo fiber and modified nano silica were mixed at a mass ratio of 6-8:1, activated by plasma and stirred in a stirred tank for 45 min to obtain the composite material. (2) Coating preparation: add rosin modified epoxy resin and functional additives to the plant fiber-nano-silica composite material, stir for 40 min, and then defoam under a vacuum degree of -0.08 MPa for 30 min to obtain a coating.

[0012] As a further technical solution, in step (1), the plasma activation parameters are: power 65-75 W, time 16-18 min, working gas is a mixture of argon and oxygen with a volume ratio of 3:1, and vacuum degree 0.05-0.08 MPa.

[0013] As a further technical solution, in step (1), the stirring tank rotation speed is 300-500 r / min, and the temperature is 60 DEG C.

[0014] As a further technical solution, in step (2), the rosin modified epoxy resin is added in two times, 50% in the first time, and the remaining amount is added after stirring for 20 min.

[0015] Compared with the prior art, the present application has the following beneficial effects: Through reasonable component design and optimization of the preparation process, the performance defects of the existing coating are effectively solved, and the improvement effect on the high temperature resistance is remarkable.

[0016] The present application introduces a plant fiber-nano-silica composite material, and the pretreated bamboo fiber is used as a substrate, which not only provides a natural skeleton support, but also enhances the bonding force with other components after surface modification; the nano-silica improves the compactness and mechanical properties of the coating through filling effect and strengthening effect. The rosin modified epoxy resin as a film forming material not only retains the excellent adhesion and chemical resistance of the epoxy resin, but also improves the compatibility with the plant fiber and the flexibility of the coating by introducing rosin. In the functional additives, hydroxyethyl cellulose can adjust the rheological property of the coating to prevent component sedimentation; nano-zinc oxide gives the coating antibacterial property and ultraviolet shielding ability; and the polyether modified silicone defoaming agent can eliminate the bubbles generated during the preparation of the coating to ensure the smoothness of the coating surface.

[0017] The pretreated bamboo fiber and nano-silica are tightly combined through plasma activation to form a composite material which not only overcomes the defects of plant fiber such as hydrophilicity and easy swelling, but also enhances the overall structural stability by using the rigidity of nano-silica; the composite material has good interfacial compatibility with the rosin modified epoxy resin, and the two materials penetrate each other to form a continuous phase, effectively avoiding the performance decline caused by interfacial separation in traditional plant-based coatings. The functional additives form a synergistic effect with the substrate and resin through adjusting the rheological property of the system, eliminating defects, and enhancing functions, further optimizing the comprehensive performance of the coating.

[0018] The multi-stage pretreatment (cleaning and removing impurities, complex enzymolysis, microwave-assisted steam explosion, and low-temperature bleaching) of the bamboo fibers not only removes impurities, but also refines the fiber structure through enzymolysis and physical treatment, increases the specific surface area, and provides more active sites for the combination with nano-silicon dioxide; the plasma activation strengthens the interface combination between the plant fibers and the nano-silicon dioxide by introducing active groups, and forms a stable three-dimensional network structure. The rosin-modified epoxy resin adjusts the molecular polarity through chemical modification, matches the polarity of the plant fiber-nano-silicon dioxide composite material, reduces the interfacial tension, promotes the uniform dispersion of the components, and thus improves the compactness and mechanical properties of the coating. The staged addition of the resin and the vacuum debubbling process further ensure the uniformity of the internal structure of the coating and reduce the influence of defects such as pores on the performance.

[0019] The improvement of the high-temperature resistance of the coating is due to the synergistic effect of multiple components: in the plant fiber-nano-silicon dioxide composite material, the pretreated bamboo fibers form a stable skeleton, the 60-70 nm nano-silicon dioxide fills the gaps between the fibers, and a dense thermal barrier is constructed to hinder heat conduction; the rosin-modified epoxy resin improves the molecular chain rigidity and crosslinking density through the covalent crosslinking of rosin and epoxy resin, and enhances the deformation resistance at high temperature; in the functional additives, hydroxyethyl cellulose optimizes the compatibility of the components, reduces interface defects, nano-zinc oxide plays an antioxidant and thermal stabilizing role, and polyether-modified silicone defoaming agent eliminates bubbles to avoid the formation of weak points due to bubble rupture at high temperature, and the three components synergistically significantly improve the high-temperature resistance of the coating.

[0020] In summary, the high-temperature resistant coating of the present application not only realizes the greenization of raw materials, but also significantly improves the adhesion, high-temperature resistance, wear resistance and water resistance of the coating through the functional complementation and synergistic effect of the components, solving the performance defects of the plant material introduced into the coating in the prior art. The coating prepared by the present application not only meets the environmental protection requirements, but also meets the durability requirements in actual application, and has a wide application prospect. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] The application provides a coating with good high-temperature resistance, which is composed of plant fiber-nano-silica composite material 30-40 parts by weight, resin 20-30 parts by weight, and functional additive 8-10 parts by weight; and the preparation method comprises the steps of plant fiber-nano-silica composite material preparation, coating blending and the like. Through specific component collocation and preparation process, the comprehensive performance of the coating is significantly improved while environmental protection is realized.

[0023] Raw material source The base material of the plant fiber-nano-silica composite material is bamboo fiber, and the bamboo is three-year-old moso bamboo which is commercially available; and the nano-silica is a commercially available product with a particle size of 60-70 nm.

[0024] The resin is a rosin modified epoxy resin, wherein the rosin is hydrogenated rosin (acid value 160-170 mgKOH / g), and the bisphenol A type epoxy resin is a commercially available product with an epoxy equivalent weight of 180-200 g / eq.

[0025] The functional additive is obtained by mixing hydroxyethyl cellulose (molecular weight 100-200 thousand), nano-zinc oxide (particle size 20-30 nm) and polyether modified siloxane defoaming agent at a mass ratio of 4-6:1:2, and each raw material is a commercially available product.

[0026] Component preparation Bamboo fiber pretreatment A multi-stage pretreatment process is adopted, and the steps are as follows: (1) cleaning and impurity removal: after the bamboo is ultrasonically cleaned (30 kHz, 15 min) with deionized water, it is vacuum dried at 60°C until the water content is ≤8%; (2) composite enzymolysis: cellulase (enzyme activity 200-300 U / g) and hemicellulase (enzyme activity 150-200 U / g) are compounded at a mass ratio of 3:1, and hydrolysis is carried out at 50°C and pH 4.8-5.2 for 2 h, and the solid-liquid ratio of the enzymolysis system is 1:15-20; (3) microwave-assisted steam explosion: after 3 min of microwave pretreatment at 800 W, steam explosion treatment is carried out at 180°C and 0.8 MPa, and bamboo fibers with a diameter of 10-20 μm are obtained; (4) low-temperature bleaching: 3wt% hydrogen peroxide is used for bleaching at 40°C for 30 min, and the whiteness is ≥85%, and after filtration, washing to neutral and drying, pretreated bamboo fiber is obtained.

[0027] Preparation of rosin modified epoxy resin Hydrogenated rosin (acid value 160-170 mgKOH / g) is mixed with bisphenol A type epoxy resin (epoxy equivalent weight 180-200 g / eq) at a mass ratio of 1:5-6, 1.2-1.6% of boron trifluoride ether catalyst based on the total mass is added, and the mixture is reacted at 140-150°C for 2.5-3h under nitrogen protection. After cooling to 60°C, 0.5-0.6% of epoxy chloropropane based on the total mass is added, and the reaction is continued for 1h to obtain a rosin-modified epoxy resin.

[0028] Preparation of plant fiber-nano silica composite material Pretreated bamboo fibers are mixed with nano silica with a particle size of 60-70 nm at a mass ratio of 6-8:1, and after plasma activation, they are stirred in a stirred tank for 45 min at a speed of 300-500 r / min and a temperature of 60°C to obtain a plant fiber-nano silica composite material. The plasma activation parameters are a power of 65-75 W, a time of 16-18 min, a mixed gas of argon and oxygen as the working gas at a volume ratio of 3:1, and a vacuum degree of 0.05-0.08 MPa.

[0029] Preparation of functional additives Hydroxyethyl cellulose, nano zinc oxide, and polyether-modified silicone defoaming agent are weighed at a mass ratio of 4-6:1:2, and mixed uniformly.

[0030] Coating preparation steps (1) Preparation of plant fiber-nano silica composite material: follow the above "Preparation of plant fiber-nano silica composite material" steps; (2) Coating preparation: add rosin-modified epoxy resin and functional additives to the plant fiber-nano silica composite material. Specifically, the rosin-modified epoxy resin is added in two portions, with 50% added first, and the remaining amount added after stirring for 20 min, with a total stirring time of 40 min. Then, the coating is degassed under a vacuum degree of -0.08 MPa for 30 min.

[0031] In the following examples, the raw materials and parameters not specifically stated are within the scope of the above "Raw materials and preparation basis". Example

[0032] (1) Preparation of plant fiber-nano silica composite material: pretreated bamboo fibers are mixed with nano silica with a particle size of 65 nm at a mass ratio of 7:1, and after plasma activation, they are stirred in a stirred tank at 400 r / min and 60°C for 45 min to obtain the composite material. The plasma activation parameters are a power of 70 W, a time of 17 min, a volume ratio of argon to oxygen of 3:1, and a vacuum degree of 0.06 MPa. (2) Functional additives: 9 parts of 150,000 molecular weight hydroxyethyl cellulose, 25 nm particle size nano zinc oxide and polyether modified siloxane defoaming agent were weighed according to the mass ratio of 5:1:2, mixed uniformly, and 9 parts were taken; (3) Coating preparation: 35 parts of plant fiber-nano silica composite material was taken, 25 parts of rosin modified epoxy resin (hydrogenated rosin and bisphenol A type epoxy resin mass ratio 1:5.5, boron trifluoride ether catalyst accounted for 1.4%, epoxy chloropropane accounted for 0.55%) was added; The rosin modified epoxy resin was added twice, the first time was 12.5 parts, after stirring for 20 min, the remaining 12.5 parts was added, then 9 parts of functional additives was added, and the total stirring time was 40 min; Finally, under the vacuum degree of-0.08 MPa, defoaming for 30 min, the coating was obtained. Example

[0033] (1) Plant fiber-nano silica composite material preparation: The pretreated bamboo fiber and the nano silica with a particle size of 60 nm were mixed according to the mass ratio of 6:1, and after plasma activation, it was stirred in a stirring kettle at 300 r / min and 60°C for 45 min to obtain the composite material; The plasma activation parameters were power 65 W, time 16 min, argon and oxygen volume ratio 3:1, and vacuum degree 0.05 MPa; (2) Functional additives: 8 parts of 100,000 molecular weight hydroxyethyl cellulose, 20 nm particle size nano zinc oxide and polyether modified siloxane defoaming agent were weighed according to the mass ratio of 4:1:2, mixed uniformly, and 8 parts were taken; (3) Coating preparation: 30 parts of plant fiber-nano silica composite material was taken, 20 parts of rosin modified epoxy resin (hydrogenated rosin and bisphenol A type epoxy resin mass ratio 1:5, boron trifluoride ether catalyst accounted for 1.2%, epoxy chloropropane accounted for 0.5%) was added; The rosin modified epoxy resin was added twice, the first time was 10 parts, after stirring for 20 min, the remaining 10 parts was added, then 8 parts of functional additives was added, and the total stirring time was 40 min; Finally, defoaming for 30 min, vacuum degree-0.08 MPa, the coating was obtained. Example

[0034] (1) Plant fiber-nano silica composite material preparation: The pretreated bamboo fiber and the nano silica with a particle size of 70 nm were mixed according to the mass ratio of 8:1, and after plasma activation, it was stirred in a stirring kettle at 500 r / min and 60°C for 45 min to obtain the composite material; The plasma activation parameters were power 75 W, time 18 min, argon and oxygen volume ratio 3:1, and vacuum degree 0.08 MPa; (2) Functional additives: 10 parts of 200,000 molecular weight hydroxyethyl cellulose, 30 nm particle size nano zinc oxide and polyether modified siloxane defoaming agent were weighed according to the mass ratio of 6:1:2, mixed uniformly, and 10 parts were taken; (3) Coating preparation: 40 parts of plant fiber-nano-silica composite material was taken, and 30 parts of rosin modified epoxy resin (hydrogenated rosin and bisphenol A type epoxy resin mass ratio 1:6, boron trifluoride ether catalyst accounted for 1.6%, epoxy chloropropane accounted for 0.6%) was added; the rosin modified epoxy resin was added twice, 15 parts was added first, stirred for 20 min, then the remaining 15 parts was added, and then 10 parts of functional additive was added, and the total stirring time was 40 min; finally, vacuum degassing was carried out for 30 min, the vacuum degree was -0.08 MPa, and the coating was obtained. Example

[0035] (1) Preparation of plant fiber-nano-silica composite material: pretreated bamboo fiber and nano-silica with a particle size of 60 nm were mixed in a mass ratio of 6:1, and after plasma activation, stirring was carried out in a stirring kettle at 300 r / min and 60°C for 45 min to obtain the composite material; the plasma activation parameters were power 65 W, time 16 min, and vacuum degree 0.05 MPa; (2) Functional additive: 10 million molecular weight hydroxyethyl cellulose, 20 nm particle size nano-zinc oxide and polyether modified silicone defoaming agent were weighed in a mass ratio of 5:1:2, mixed uniformly, and 8 parts were taken; (3) Coating preparation: 30 parts of plant fiber-nano-silica composite material was taken, and 25 parts of rosin modified epoxy resin (hydrogenated rosin and bisphenol A type epoxy resin mass ratio 1:5, catalyst accounted for 1.2%) was added; the rosin modified epoxy resin was added twice, and the total stirring time was 40 min, then degassing was carried out, vacuum degassing was carried out for 30 min, the vacuum degree was -0.08 MPa, and the coating was obtained. Example

[0036] (1) Preparation of plant fiber-nano-silica composite material: pretreated bamboo fiber and nano-silica with a particle size of 70 nm were mixed in a mass ratio of 8:1, and after plasma activation, stirring was carried out in a stirring kettle at 500 r / min and 60°C for 45 min to obtain the composite material; the plasma activation parameters were power 75 W, time 18 min, and vacuum degree 0.08 MPa; (2) Functional additive: 20 million molecular weight hydroxyethyl cellulose, 30 nm particle size nano-zinc oxide and polyether modified silicone defoaming agent were weighed in a mass ratio of 6:1:2, mixed uniformly, and 10 parts were taken; (3) Coating preparation: 40 parts of plant fiber-nano-silica composite material was taken, and 30 parts of rosin modified epoxy resin (hydrogenated rosin and bisphenol A type epoxy resin mass ratio 1:6, catalyst accounted for 1.6%) was added; the rosin modified epoxy resin was added twice, and the total stirring time was 40 min, then degassing was carried out, vacuum degassing was carried out for 30 min, the vacuum degree was -0.08 MPa, and the coating was obtained.

[0037] Comparative Example 1 The difference from Example 1 is that 35 parts of pretreated bamboo fibers (not compounded with nano-silica) are directly used instead of the plant fiber-nano-silica composite material, and the remaining raw materials and steps are the same.

[0038] Comparative Example 2 The difference from Example 1 is that the rosin-modified epoxy resin is replaced by a common bisphenol A type epoxy resin (not modified with rosin), and the remaining raw materials and steps are the same.

[0039] Test To verify the performance of the coating of the present application, water resistance, wear resistance and adhesion were tested, and the test objects were Examples 1-5 and Comparative Examples 1-2, each test was repeated 3 times, and the average value was taken.

[0040] Water resistance test Test method: The coating was applied to a tinplate panel (coating thickness 50 μm), dried at room temperature for 72 h, then immersed in distilled water (25°C), and observed for 240 h to see if the coating had blistering, peeling or discoloration, and the time of the first defect was recorded; if there was no defect for 240 h, it was recorded as 240 h+, and the results were as follows:

[0041] As can be seen from Table 1, Examples 1, 3 and 5 have the best water resistance (no defects for 240 h), and Examples 2 and 4 are slightly weaker but still better than the comparative examples. Comparative Example 1 lacks nano-silica, the bamboo fibers have insufficient bonding force with the resin, and water molecules easily penetrate, resulting in premature failure of the coating; Comparative Example 2 uses a common epoxy resin, which has poor compatibility with the plant fibers and weak interfacial bonding, and has even poorer water resistance. The synergistic effect of the plant fiber-nano-silica composite material and the rosin-modified epoxy resin in the present application significantly improves the water resistance.

[0042] Wear resistance test Test method: A Taber abrasion tester (load 500 g, abrasive wheel CS-10) was used to test the number of revolutions of the coating (thickness 50 μm) until the substrate was exposed, and the higher the number of revolutions, the better the wear resistance, and the results were as follows:

[0043] As can be seen from Table 2, the wear resistance of the examples is significantly better than that of the comparative examples, and the number of revolutions of Examples 3 and 5 exceeds 4000. Comparative Example 1 lacks nano-silica, the fibers have poor dispersibility, and the coating structure is loose, resulting in poor wear resistance; Comparative Example 2 has a weak interfacial bonding between the common epoxy resin and the fibers, and is prone to peeling under stress, resulting in even poorer wear resistance. The reinforcing effect of nano-silica and the compatibility of rosin-modified epoxy resin are the key to improving wear resistance.

[0044] Adhesion test Test method: adopt grid method (ISO 2409), use grid knife to draw 10x10 1mm square on the coating (thickness 50μm), stick 3M tape and tear it off quickly, observe the residual coating in the square, rate (0 level is the best, 5 level is the worst), the results are as follows:

[0045] As can be seen from Table 3, the adhesion of Examples 1, 3 and 5 reaches 0 level (best), Examples 2 and 4 are 1 level, which are better than Comparative Examples. Comparative Example 1 has no nano-silica, and there are gaps between the fiber and the resin interface, so the adhesion is reduced; Comparative Example 2 has a large difference in polarity between the ordinary epoxy resin and the plant fiber, and the interface is weakly combined, so the adhesion is the worst. The surface modification of the plant fiber-nano-silica composite material and the polarity adjustment of the rosin modified epoxy resin in the application significantly improve the adhesion of the coating to the substrate.

[0046] High temperature resistance test Test method: test plate preparation: the coating was evenly coated on a 100mmx50mmx0.3mm tin plate (sanding treatment, roughness Ra3.2μm), and the coating thickness (dry film) was controlled to be 50μm, and dried at room temperature and 50% humidity for 72h. Test process: place the test plate in a high temperature oven, and keep it at 200℃, 250℃, 300℃ and 350℃ for 24h respectively, and observe whether the coating cracks, peels off or discolors after cooling to room temperature, and at the same time, measure the weight loss rate of the coating (weight loss rate=(mass before heating-mass after heating) / mass before heatingx100%), and the highest temperature with no cracking, peeling and weight loss rate≤10% is the temperature limit, and the results are as follows:

[0047] As can be seen from Table 4, the coating prepared by the application has excellent high temperature resistance. Comparative Example 1 has no nano-silica, and the coating density is significantly reduced, so the high temperature resistance is reduced; Comparative Example 2 has a large difference in polarity between the ordinary epoxy resin and the plant fiber, and the interface is weakly combined, so the high temperature resistance is reduced.

[0048] In summary, through the design of plant fiber-nano-silica composite material, the selection and specific preparation process of rosin modified epoxy resin, the coating has excellent water resistance, wear resistance and adhesion, and solves the problem of insufficient performance of traditional plant-based coatings.

[0049] In the description of the specification, reference to "one embodiment", "an example", "a specific example" or the like means that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. The appearances of the phrases "in one embodiment", "an example", "a specific example" or the like in various places in the specification are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0050] The preferred embodiments of the application disclosed above are only to help explain the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the contents of the specification. The specification selects and specifically describes these embodiments in order to better explain the principles and practical application 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 coating with good high-temperature resistance, characterized in that, It consists of the following components in parts by weight: 30-40 parts of plant fiber-nano silica composite material, wherein the composite material is obtained by combining bamboo fiber as the base material with nano silica; 20-30 parts of resin, wherein the resin is rosin-modified epoxy resin; The functional additives, 8-10 parts in total, are a mixture of hydroxyethyl cellulose, nano zinc oxide and polyether-modified siloxane defoamer in a mass ratio of 4-6:1:

2.

2. The coating with good high-temperature resistance according to claim 1, characterized in that, The nano-silica particles have a diameter of 60-70 nm.

3. The coating with good high-temperature resistance according to claim 1, characterized in that, The bamboo fiber is prepared through a multi-stage pretreatment process: (1) Cleaning and impurity removal: After ultrasonic cleaning with deionized water, the bamboo is vacuum dried at 60℃ until the moisture content is ≤8%; The ultrasonic cleaning parameters are: 30kHz, 15min; (2) Compound enzymatic hydrolysis: Cellulase and hemicellulase were mixed at a mass ratio of 3:1 and hydrolyzed at 50℃ and pH 4.8-5.2 for 2 hours; the solid-liquid ratio of the enzymatic hydrolysis system was 1:15-20. The cellulase has an enzyme activity of 200-300 U / g; the hemicellulase has an enzyme activity of 150-200 U / g. (3) Microwave-assisted steam explosion: After pretreatment with 800W microwave for 3 minutes, the bamboo fiber with a diameter of 10-20μm was obtained by steam explosion treatment at 180℃ and 0.8MPa. (4) Low temperature bleaching: use 3wt% hydrogen peroxide to bleach at 40℃ for 30min, the whiteness is ≥85%, after filtration, washing until neutral, and drying, the result is obtained.

4. The coating with good high-temperature resistance according to claim 1, characterized in that, The preparation method of the rosin-modified epoxy resin is as follows: rosin and bisphenol A type epoxy resin are mixed at a mass ratio of 1:5-6, and boron trifluoride diethyl ether catalyst accounting for 1.2-1.6% of the total mass is added. The mixture is reacted at 140-150℃ for 2.5-3 hours under nitrogen protection. After cooling to 60℃, epichlorohydrin accounting for 0.5-0.6% of the total mass is added, and the reaction is continued for 1 hour to obtain the rosin-modified epoxy resin.

5. The coating with good high-temperature resistance according to claim 4, characterized in that, The rosin is hydrogenated rosin with an acid value of 160-170 mgKOH / g, and the epoxy equivalent of the bisphenol A epoxy resin is 180-200 g / eq.

6. The coating with good high-temperature resistance according to claim 1, characterized in that, The functional additives include: nano zinc oxide with a particle size of 20-30 nm; and hydroxyethyl cellulose with a molecular weight of 100,000-200,000.

7. The method for preparing a coating with good high-temperature resistance according to claim 1, characterized in that, Includes the following steps: (1) Preparation of plant fiber-nano silica composite material: pretreated bamboo fiber and modified nano silica were mixed at a mass ratio of 6-8:1, activated by plasma and stirred in a stirred tank for 45 min to obtain the composite material. (2) Coating preparation: Add rosin-modified epoxy resin and functional additives to the plant fiber-nano silica composite material, stir for 40 min, and then degas for 30 min under vacuum of -0.08 MPa to obtain the coating.

8. The preparation method according to claim 7, characterized in that, In step (1), the parameters for plasma activation are: power 65-75W, time 16-18min, working gas is a mixture of argon and oxygen with a volume ratio of 3:1, and vacuum degree 0.05-0.08MPa.

9. The preparation method according to claim 7, characterized in that, In step (1), the stirring tank speed is 300-500 r / min and the temperature is 60℃.

10. The preparation method according to claim 7, characterized in that, In step (2), the rosin-modified epoxy resin is added in two parts. The first part is 50%, and the remaining amount is added after stirring for 20 minutes.

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