Microcement coating and method for its preparation

Abstract

The present application relates to the paint technical field, specifically disclose a kind of micro cement paint and preparation method thereof.The micro cement paint includes following mass fraction of each raw material component: film-forming substance 31~35 parts, filler 30~35 parts, cement 43~50 parts, film-forming aid 2~4 parts, dispersant 10~15 parts, compatible agent 10~14 parts and water 40~45 parts;Film-forming substance includes fluorocarbon resin and water-based organic silicon modified acrylic resin;Filler includes chitosan modified nanocellulose and acetylated lignin.The present application uses fluorocarbon resin and water-based organic silicon modified acrylic resin as film-forming substance, uses chitosan modified nanocellulose and acetylated lignin as filler, realizes the double promotion of micro cement paint waterproof and mechanical property through the synergistic effect of each component, so that micro cement paint can still maintain low water absorption, high durability and high mechanical strength under harsh environment, provide a new way for the preparation of micro cement paint.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a microcement coating and its preparation method. Background Technology

[0002] Micro cement coatings are composed of cement, water-based resin, ultrafine mineral admixtures and functional additives. Due to their seamless integrity, minimalist texture, excellent wear resistance and strong adhesion, they are widely used in wall, floor and furniture decoration, especially suitable for minimalist interior design. They are also environmentally friendly and have low volatility, meeting the requirements of modern green building.

[0003] However, existing microcement waterproofing performance has significant shortcomings, limiting its application in humid environments. These shortcomings stem from two main factors: first, the strong hydrophilicity of cement-based materials makes them prone to forming honeycomb-like pores when dry, allowing moisture to easily penetrate through capillary action; second, the predominantly 1-2mm thin-coat application process further reduces its impermeability. Moisture penetration can lead to coating peeling and cracking, as well as dampness and mold growth on the substrate, particularly in bathrooms, kitchens, and basements. With the increasing market demand for microcement in humid environments, current technologies struggle to overcome the balancing challenge of "waterproofing, mechanical properties, and decorative effect." Improving waterproofing from the material's inherent properties without compromising its original characteristics has become a pressing issue in this field. Summary of the Invention

[0004] To address the problem of poor waterproofing performance of existing cement coatings, this invention provides a micro cement coating and its preparation method.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] The present invention provides a micro cement coating comprising the following raw material components in parts by weight: 31-35 parts of film-forming substance, 30-35 parts of filler, 43-50 parts of cement, 2-4 parts of film-forming aid, 10-15 parts of dispersant, 10-14 parts of compatibilizer and 40-45 parts of water;

[0007] The film-forming substances include fluorocarbon resin and waterborne organosilicon-modified acrylic resin.

[0008] The filler includes chitosan-modified nanocellulose and acetylated lignin.

[0009] Compared to existing technologies, the microcement coating provided by this invention utilizes fluorocarbon resin, which possesses extremely low surface energy and excellent hydrophobicity. This allows it to form a dense and weather-resistant protective film on the coating surface, effectively preventing the penetration of moisture and ions. The water-based organosilicon-modified acrylic resin contains organosilicon groups in its molecular chain, which not only provides good flexibility but also improves the compatibility between cement and film-forming substances, while enhancing the crack resistance of the coating. When fluorocarbon resin and water-based organosilicon-modified acrylic resin are used as film-forming substances in combination, the two resins work synergistically to form a continuous film structure on the coating surface that is both hydrophobic and dense, yet flexible and durable, significantly improving the waterproof performance of the coating.

[0010] Chitosan-modified nanocellulose possesses a high specific surface area and excellent mechanical strength, enabling it to construct a nanoscale reinforcing skeleton within the coating film, thereby enhancing the tensile strength of the coating. Simultaneously, after specific modification, nanocellulose can form chemical bonds with the resin in the film-forming material, further improving interfacial adhesion and thus simultaneously enhancing the waterproofness and strength of the microcement coating. Acetylated lignin exhibits good hydrophobicity, which on one hand fills the micropores within the coating, reducing the number of capillary channels; on the other hand, it forms hydrogen bonds with the polar groups of the resin in the film-forming material, improving the interfacial adhesion in the microcement coating. This results in good compatibility among the components of the microcement coating, thereby reducing the overall water absorption rate of the coating and further enhancing the waterproofing effect.

[0011] In this invention, the film-forming substance can form a continuous and dense organic phase. The filler particles further fill the micropores of the cement-based coating, ensuring sufficient filling of the internal pores. This not only reduces the number and connectivity of capillary channels in the coating but also extends the diffusion paths of moisture and ions, structurally enhancing the coating's waterproof performance. The combination of chitosan-modified nanocellulose and water-based organosilicon-modified acrylic resin, along with the compatibility of acetylated lignin with the film-forming substance, respectively improves the bonding strength between the organic phase and the inorganic cement matrix from different dimensions, reducing interface defects and ensuring the coating's structural integrity. The integrity of the structure; the nano-reinforcing network constructed by chitosan-modified nanocellulose improves the strength and wear resistance of the microcement coating, while the flexibility of the film-forming material and the compatibility of acetylated lignin reduce the brittleness of the coating, allowing the coating to remain stable under stress or temperature and humidity changes; the moisture-proof barrier constructed by fluorocarbon resin, combined with the permeation channels blocked by acetylated lignin, and the reinforcing effect of chitosan-modified nanocellulose and the flexibility of water-based organosilicon-modified acrylic resin, enable the coating to have excellent mechanical strength on the basis of low water absorption.

[0012] In this invention, fluorocarbon resin and waterborne organosilicon-modified acrylic resin are used as film-forming substances, and chitosan-modified nanocellulose and acetylated lignin are used as fillers. Through the synergistic effect of each component, the microcement coating achieves a dual improvement in waterproof performance and mechanical properties. This enables the microcement coating to maintain low water absorption, high durability and high mechanical strength even in harsh environments, providing a new approach to the preparation of microcement coatings.

[0013] Preferably, the cement is 42.5# ordinary Portland cement.

[0014] Preferably, the solid content of the fluorocarbon resin is 46-48%.

[0015] More preferably, the fluorocarbon resin is NACATE NCT-JT08 from Suqian Nakaite New Material Technology Co., Ltd.

[0016] Preferably, the viscosity of the waterborne silicone-modified acrylic resin is 3500-4000s.

[0017] A further preferred aqueous silicone-modified acrylic resin is S-611 from Wanjia Huixin Surface Materials Co., Ltd.

[0018] Preferably, the mass ratio of the fluorocarbon resin to the waterborne organosilicon-modified acrylic resin is 1:(4-6).

[0019] Preferably, the mass ratio of the chitosan-modified nanocellulose to the acetylated lignin is (2-3):1.

[0020] Through numerous experiments, the inventors discovered that by further limiting the proportions of the film-forming substances and fillers to a specific range, the waterproof and mechanical properties of microcement coatings can be further improved.

[0021] Preferably, the preparation method of the chitosan-modified nanocellulose includes the following steps:

[0022] Step 1: Disperse nanocellulose in water to obtain nanocellulose dispersion;

[0023] Step 2: Dissolve chitosan in acetic acid solution to obtain chitosan solution;

[0024] Step 3: Adjust the pH of the chitosan solution to 3-4, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, impregnate at 60-80℃, separate the solid and liquid, wash, and dry to obtain the chitosan-modified nanocellulose.

[0025] The method for preparing chitosan-modified nanocellulose provided by this invention utilizes the chemical reaction between chitosan and nanocellulose to achieve a strong bond between the two under mild conditions. This method retains the nano-reinforcing effect of nanocellulose while significantly reducing the water absorption rate of the coating through the hydrophobic modification of chitosan. At the same time, it avoids the use of toxic reagents. The process is simple and suitable for industrial production, providing a high-quality filler with both environmental friendliness and functionality for microcement coatings.

[0026] Preferably, the mass ratio of the nanocellulose to chitosan is 1:(1.4 to 1.8).

[0027] Preferably, in step 1, the diameter of the nanocellulose is 3-30 nm and the length is 50-300 nm.

[0028] More preferably, in step 1, the nanocellulose is purchased from Zhejiang Jinjiahao Green Nanomaterials Co., Ltd., and the model is CNF-B10.

[0029] Preferably, in step 1, the concentration of the nanocellulose dispersion is 4-5 wt%.

[0030] Preferably, in step 2, the molecular weight of the chitosan is 600-800 kDa.

[0031] Preferably, in step 2, the concentration of chitosan in the chitosan solution is 1-2 wt%.

[0032] Preferably, in step 2, the concentration of the acetic acid solution is 1-3 wt%.

[0033] It should be further noted that glacial acetic acid can be used when adjusting the chitosan solution in step 3.

[0034] Preferably, in step 3, the soaking time is 1 to 1.5 hours.

[0035] Preferably, in step 3, the impregnation process also requires stirring, and the stirring speed can be 300-400 rpm.

[0036] Preferably, the method for preparing the acetylated lignin includes the following steps: mixing lignin, acetylation reagent and acetic acid evenly, and reacting at 60-65°C to obtain the acetylated lignin.

[0037] The method for preparing acetylated lignin provided by this invention avoids thermal degradation of lignin through medium-low temperature reaction, preserving its molecular chain integrity. At the same time, acetic acid is used as both a reaction medium and a solvent, reducing the use of toxic solvents. The process is simple and environmentally friendly. The esterification reaction between the acetylation reagent and the lignin hydroxyl groups is rapid and efficient, which significantly improves the hydrophobicity of acetylated lignin, enhances its compatibility with fluorocarbon resins and water-based organosilicon-modified acrylic resins, and reduces the water absorption rate of the coating. In addition, the reaction conditions provided by this invention are mild and easy to operate, making it suitable for large-scale industrial production.

[0038] Preferably, the lignin is alkali lignin.

[0039] Preferably, the lignin has a particle size of 1–5 μm.

[0040] Preferably, the reaction time is 3 to 5 hours.

[0041] Preferably, the acetylation agent is at least one of acetyl bromide or acetyl chloride.

[0042] Preferably, the mass ratio of lignin to acetylation reagent is 1:(20-25).

[0043] Preferably, the mass ratio of lignin to acetic acid is 1:(100-150).

[0044] For example, stirring is required during the reaction.

[0045] It should be further noted that after the reaction is completed, the reaction system is subjected to rotary evaporation to remove acetic acid, yielding acetylated lignin.

[0046] Preferably, the film-forming aid is at least one of dipropylene glycol methyl ether or dipropylene glycol dimethyl ether.

[0047] It should be further noted that the dispersant is not specifically limited and can be DISPERBYK-2155.

[0048] Preferably, the compatibilizer is an ethylene-methyl acrylate copolymer.

[0049] More preferably, the compatibilizer is of the following type: EMA 2116AC.

[0050] This invention provides a method for preparing the above-mentioned microcement coating, comprising the following steps:

[0051] Mix the weighed film-forming material, filler, cement, dispersant, film-forming aid and water evenly, and then add compatibilizer to obtain micro cement coating.

[0052] This invention utilizes a composite film-forming material of fluorocarbon resin and water-based organosilicon-modified acrylic resin, combined with chitosan-modified nanocellulose and acetylated lignin as fillers. This not only solves the problems of poor waterproofing and insufficient mechanical properties of existing microcement coatings, but also significantly improves the overall performance of microcement coatings through the synergistic effect of the film-forming material and the fillers, achieving a significant technological breakthrough. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] To better illustrate the present invention, further examples are provided below.

[0055] In this embodiment of the invention, the cement is 42.5# ordinary silicate cement; the fluorocarbon resin is purchased from Suqian Nakaite New Material Technology Co., Ltd., model NACATE NCT-JT08; the water-based organosilicon-modified acrylic resin is purchased from Wanjia Huixin Surface Materials Co., Ltd., model S-611; the nanocellulose is purchased from Zhejiang Jinjiahao Green Nanomaterials Co., Ltd., model CNF-B10; the dispersant is DISPERBYK-2155; and the compatibilizer is of the following type: EMA 2116AC.

[0056] Example 1

[0057] This embodiment provides a microcement coating, comprising the following raw material components in parts by weight: 31 parts film-forming substance, 35 parts filler, 45 parts cement, 2 parts dipropylene glycol methyl ether, 2 parts dispersant, 12 parts compatibilizer, and 40 parts water.

[0058] The film-forming substances include fluorocarbon resin and waterborne organosilicon-modified acrylic resin in a mass ratio of 1:4.

[0059] The filler consists of chitosan-modified nanocellulose and acetylated lignin in a mass ratio of 2:1;

[0060] The preparation method of chitosan-modified nanocellulose includes the following steps:

[0061] Step 1: Disperse 1g of nanocellulose in water to obtain a nanocellulose dispersion with a concentration of 4wt%.

[0062] Step 2: Dissolve 1.4g of chitosan with a molecular weight of 600kDa in a 3wt% acetic acid solution to obtain a chitosan solution with a chitosan concentration of 1wt%.

[0063] Step 3: Adjust the pH of the chitosan solution to 4 using glacial acetic acid, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, and soak at 60°C for 1 hour. During soaking, stir at a rate of 300 rpm, separate the solid and liquid, wash, and dry to obtain chitosan-modified nanocellulose.

[0064] The preparation method of acetylated lignin includes the following steps: 1g of alkali lignin with a particle size of 1μm, 20g of acetyl bromide and 100g of acetic acid are mixed evenly and stirred at 60℃ for 3h. After the reaction is completed, the reaction system is rotary evaporated to remove acetic acid and obtain acetylated lignin.

[0065] This embodiment also provides a method for preparing the above-mentioned microcement coating, including the following steps:

[0066] The film-forming substance, filler, cement, dispersant, dipropylene glycol methyl ether and water are weighed and mixed evenly, and then a compatibilizer is added to obtain micro cement coating.

[0067] Example 2

[0068] This embodiment provides a microcement coating, comprising the following raw material components in parts by weight: 33 parts film-forming substance, 32 parts filler, 43 parts cement, 3 parts dipropylene glycol dimethyl ether, 3 parts dispersant, 10 parts compatibilizer, and 45 parts water.

[0069] The film-forming substances include fluorocarbon resin and waterborne organosilicon-modified acrylic resin in a mass ratio of 1:5.

[0070] The filler consists of chitosan-modified nanocellulose and acetylated lignin in a mass ratio of 3:1;

[0071] The preparation method of chitosan-modified nanocellulose includes the following steps:

[0072] Step 1: Disperse 1g of nanocellulose in water to obtain a nanocellulose dispersion with a concentration of 5wt%.

[0073] Step 2: Dissolve 1.6g of chitosan with a molecular weight of 800kDa in a 2wt% acetic acid solution to obtain a chitosan solution with a chitosan concentration of 2wt%.

[0074] Step 3: Adjust the pH of the chitosan solution to 3 using glacial acetic acid, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, and soak at 80°C for 1.5 hours. During soaking, the mixture needs to be stirred at a rate of 400 rpm. After solid-liquid separation, washing and drying, chitosan-modified nanocellulose is obtained.

[0075] The preparation method of acetylated lignin includes the following steps: 1g of alkali lignin with a particle size of 3μm, 23g of acetyl chloride and 120g of acetic acid are mixed evenly and stirred at 65℃ for 5h. After the reaction is completed, the reaction system is rotary evaporated to remove acetic acid and obtain acetylated lignin.

[0076] This embodiment also provides a method for preparing the above-mentioned microcement coating, including the following steps:

[0077] The film-forming substance, filler, cement, dispersant, dipropylene glycol dimethyl ether and water are weighed and mixed evenly, and then a compatibilizer is added to obtain a micro cement coating.

[0078] Example 3

[0079] This embodiment provides a microcement coating, comprising the following raw material components in parts by weight: 35 parts film-forming substance, 30 parts filler, 50 parts cement, 4 parts dipropylene glycol dimethyl ether, 4 parts dispersant, 14 parts compatibilizer, and 42 parts water.

[0080] The film-forming substances include fluorocarbon resin and waterborne organosilicon-modified acrylic resin in a mass ratio of 1:6.

[0081] The filler consists of chitosan-modified nanocellulose and acetylated lignin in a mass ratio of 3:1;

[0082] The preparation method of chitosan-modified nanocellulose includes the following steps:

[0083] Step 1: Disperse 1g of nanocellulose in water to obtain a nanocellulose dispersion with a concentration of 5wt%.

[0084] Step 2: Dissolve 1.8g of chitosan with a molecular weight of 700kDa in a 1wt% acetic acid solution to obtain a chitosan solution with a chitosan concentration of 2wt%.

[0085] Step 3: Adjust the pH of the chitosan solution to 3 using glacial acetic acid, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, and soak at 70°C for 1.5 hours. During soaking, the mixture needs to be stirred at a rate of 350 rpm. After solid-liquid separation, washing and drying, chitosan-modified nanocellulose is obtained.

[0086] The preparation method of acetylated lignin includes the following steps: 1g of alkali lignin with a particle size of 3μm, 25g of acetyl chloride and 150g of acetic acid are mixed evenly and stirred at 62℃ for 4h. After the reaction is completed, the reaction system is rotary evaporated to remove acetic acid and obtain acetylated lignin.

[0087] This embodiment also provides a method for preparing the above-mentioned microcement coating, including the following steps:

[0088] The film-forming substance, filler, cement, dispersant, dipropylene glycol dimethyl ether and water are weighed and mixed evenly, and then a compatibilizer is added to obtain a micro cement coating.

[0089] Comparative Example 1

[0090] This comparative example provides a microcement coating, which differs from Example 1 in that: the fluorocarbon resin is replaced with an equal amount of water-based organosilicon-modified acrylic resin.

[0091] Specifically, the raw material components include the following parts by weight: 31 parts of water-based silicone-modified acrylic resin, 35 parts of filler, 45 parts of cement, 2 parts of dipropylene glycol methyl ether, 2 parts of dispersant, 12 parts of compatibilizer, and 40 parts of water.

[0092] The filler includes chitosan-modified nanocellulose and acetylated lignin in a mass ratio of 2:1.

[0093] The preparation method of chitosan-modified nanocellulose includes the following steps:

[0094] Step 1: Disperse 1g of nanocellulose in water to obtain a nanocellulose dispersion with a concentration of 4wt%.

[0095] Step 2: Dissolve 1.4g of chitosan with a molecular weight of 600kDa in a 3wt% acetic acid solution to obtain a chitosan solution with a chitosan concentration of 1wt%.

[0096] Step 3: Adjust the pH of the chitosan solution to 4 using glacial acetic acid, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, and soak at 60°C for 1 hour. During soaking, stir at a rate of 300 rpm, separate the solid and liquid, wash, and dry to obtain chitosan-modified nanocellulose.

[0097] The preparation method of acetylated lignin includes the following steps: 1g of alkali lignin with a particle size of 1μm, 20g of acetyl bromide and 100g of acetic acid are mixed evenly and stirred at 60℃ for 3h. After the reaction is completed, the reaction system is rotary evaporated to remove acetic acid and obtain acetylated lignin.

[0098] This comparative example also provides a method for preparing the above-mentioned microcement coating, including the following steps:

[0099] The water-based organosilicon-modified acrylic resin, filler, cement, dispersant, dipropylene glycol methyl ether and water are weighed and mixed evenly, and then a compatibilizer is added to obtain micro cement coating.

[0100] Comparative Example 2

[0101] This comparative example provides a microcement coating, which differs from Example 1 in that: the water-based organosilicon-modified acrylic resin is replaced with an equal amount of fluorocarbon resin.

[0102] Specifically, the raw material components include the following parts by weight: 31 parts fluorocarbon resin, 35 parts filler, 45 parts cement, 2 parts dipropylene glycol methyl ether, 2 parts dispersant, 12 parts compatibilizer, and 40 parts water.

[0103] The filler consists of chitosan-modified nanocellulose and acetylated lignin in a mass ratio of 2:1;

[0104] The preparation method of chitosan-modified nanocellulose includes the following steps:

[0105] Step 1: Disperse 1g of nanocellulose in water to obtain a nanocellulose dispersion with a concentration of 4wt%.

[0106] Step 2: Dissolve 1.4g of chitosan with a molecular weight of 600kDa in a 3wt% acetic acid solution to obtain a chitosan solution with a chitosan concentration of 1wt%.

[0107] Step 3: Adjust the pH of the chitosan solution to 4 using glacial acetic acid, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, and soak at 60°C for 1 hour. During soaking, stir at a rate of 300 rpm, separate the solid and liquid, wash, and dry to obtain chitosan-modified nanocellulose.

[0108] The preparation method of acetylated lignin includes the following steps: 1g of alkali lignin with a particle size of 1μm, 20g of acetyl bromide and 100g of acetic acid are mixed evenly and stirred at 60℃ for 3h. After the reaction is completed, the reaction system is rotary evaporated to remove acetic acid and obtain acetylated lignin.

[0109] This comparative example also provides a method for preparing the above-mentioned microcement coating, including the following steps:

[0110] The weighed fluorocarbon resin, filler, cement, dispersant, dipropylene glycol methyl ether and water are mixed evenly, and then a compatibilizer is added to obtain micro cement coating.

[0111] Comparative Example 3

[0112] This comparative example provides a microcement coating, which differs from Example 1 in that: chitosan-modified nanocellulose is replaced with an equal amount of polylysine-modified nanocellulose, wherein the polylysine is purchased from Hangzhou Qianying Biotechnology Co., Ltd., model number 30100;

[0113] Specifically, the raw material components include the following parts by weight: 31 parts film-forming substance, 35 parts filler, 45 parts cement, 2 parts dipropylene glycol methyl ether, 2 parts dispersant, 12 parts compatibilizer, and 40 parts water.

[0114] The film-forming substances include fluorocarbon resin and waterborne organosilicon-modified acrylic resin in a mass ratio of 1:4.

[0115] The filler consists of polylysine-modified nanocellulose and acetylated lignin in a mass ratio of 2:1;

[0116] The preparation method of polylysine-modified nanocellulose includes the following steps:

[0117] Step 1: Disperse 1g of nanocellulose in water to obtain a nanocellulose dispersion with a concentration of 4wt%.

[0118] Step 2: Dissolve 1.4g of polylysine in a 3wt% acetic acid solution to obtain a polylysine solution with a polylysine concentration of 1wt%.

[0119] Step 3: Adjust the pH of the polylysine solution to 4 using glacial acetic acid, add the adjusted polylysine solution dropwise to the nanocellulose dispersion, and impregnate at 60°C for 1 hour. During impregnation, stir at a rate of 300 rpm, separate the solid and liquid, wash, and dry to obtain polylysine-modified nanocellulose.

[0120] The preparation method of acetylated lignin includes the following steps: 1g of alkali lignin with a particle size of 1μm, 20g of acetyl bromide and 100g of acetic acid are mixed evenly and stirred at 60℃ for 3h. After the reaction is completed, the reaction system is rotary evaporated to remove acetic acid and obtain acetylated lignin.

[0121] This comparative example also provides a method for preparing the above-mentioned microcement coating, including the following steps:

[0122] The film-forming substance, filler, cement, dispersant, dipropylene glycol methyl ether and water are weighed and mixed evenly, and then a compatibilizer is added to obtain micro cement coating.

[0123] Comparative Example 4

[0124] This comparative example provides a microcement coating, which differs from Example 1 in that: acetylated lignin is replaced with an equal amount of benzoyl-modified lignin;

[0125] Specifically, the raw material components include the following parts by weight: 31 parts film-forming substance, 35 parts filler, 45 parts cement, 2 parts dipropylene glycol methyl ether, 2 parts dispersant, 12 parts compatibilizer, and 40 parts water.

[0126] The film-forming substances include fluorocarbon resin and waterborne organosilicon-modified acrylic resin in a mass ratio of 1:4.

[0127] The filler consists of chitosan-modified nanocellulose and benzoyl-modified lignin in a mass ratio of 2:1;

[0128] The preparation method of chitosan-modified nanocellulose includes the following steps:

[0129] Step 1: Disperse 1g of nanocellulose in water to obtain a nanocellulose dispersion with a concentration of 4wt%.

[0130] Step 2: Dissolve 1.4g of chitosan with a molecular weight of 600kDa in a 3wt% acetic acid solution to obtain a chitosan solution with a chitosan concentration of 1wt%.

[0131] Step 3: Adjust the pH of the chitosan solution to 4 using glacial acetic acid, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, and soak at 60°C for 1 hour. During soaking, stir at a rate of 300 rpm, separate the solid and liquid, wash, and dry to obtain chitosan-modified nanocellulose.

[0132] The preparation method of benzoyl-modified lignin includes the following steps: 1g of alkali lignin with a particle size of 1μm, 20g of benzoyl bromide and 100g of acetic acid are mixed evenly and stirred at 60℃ for 3h. After the reaction is completed, the reaction system is rotary evaporated to remove acetic acid and obtain benzoyl-modified lignin.

[0133] This comparative example also provides a method for preparing the above-mentioned microcement coating, including the following steps:

[0134] The film-forming substance, filler, cement, dispersant, dipropylene glycol methyl ether and water are weighed and mixed evenly, and then a compatibilizer is added to obtain micro cement coating.

[0135] The microcement coatings prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were tested, and the specific test indicators and methods are as follows:

[0136] Tensile strength, elongation at break, and impermeability were tested according to GB / T 23445-2009 "Polymer Cement Waterproof Coatings";

[0137] Water absorption rate was tested according to JG / T 375-2012;

[0138] The specific test results are shown in Table 1:

[0139] Table 1. Experimental Results

[0140]

[0141]

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microcement coating, characterized in that, The raw material components include the following parts by weight: 31-35 parts film-forming substance, 30-35 parts filler, 43-50 parts cement, 2-4 parts film-forming aid, 2-4 parts dispersant, 10-14 parts compatibilizer and 40-45 parts water; The film-forming substances include fluorocarbon resin and waterborne organosilicon-modified acrylic resin. The filler includes chitosan-modified nanocellulose and acetylated lignin.

2. The microcement coating as described in claim 1, characterized in that, The solid content of the fluorocarbon resin is 46-48%.

3. The microcement coating as described in claim 1 or 2, characterized in that, The mass ratio of the fluorocarbon resin to the waterborne organosilicon-modified acrylic resin is 1:(4~6).

4. The microcement coating as described in claim 1 or 2, characterized in that, The mass ratio of chitosan-modified nanocellulose to acetylated lignin is (2~3):

1.

5. The microcement coating as described in claim 1, characterized in that, The preparation method of the chitosan-modified nanocellulose includes the following steps: Step 1: Disperse nanocellulose in water to obtain nanocellulose dispersion; Step 2: Dissolve chitosan in acetic acid solution to obtain chitosan solution; Step 3: Adjust the pH of the chitosan solution to 3-4, add the adjusted chitosan solution dropwise to the nanocellulose dispersion, impregnate at 60-80℃, separate the solid and liquid, wash, and dry to obtain the chitosan-modified nanocellulose.

6. The microcement coating as described in claim 5, characterized in that, The mass ratio of nanocellulose to chitosan is 1:(1.4~1.8). In step 1, the diameter of the nanocellulose is 3~30nm and the length is 50~300nm; In step 1, the concentration of the nanocellulose dispersion is 4-5 wt%.

7. The microcement coating as described in claim 5, characterized in that, In step 2, the concentration of chitosan in the chitosan solution is 1-2 wt%. In step 2, the concentration of the acetic acid solution is 1-3 wt%. In step 3, the soaking time is 1 to 1.5 hours.

8. The microcement coating as described in claim 1, characterized in that, The preparation method of the acetylated lignin includes the following steps: mixing lignin, acetylation reagent and acetic acid evenly, and reacting at 60~65℃ to obtain the acetylated lignin.

9. The microcement coating as described in claim 8, characterized in that, The lignin has a particle size of 1~5μm; The mass ratio of lignin to acetylation reagent is 1:(20~25); The mass ratio of lignin to acetic acid is 1:(100~150). The reaction time is 3-5 hours.

10. A method for preparing the microcement coating according to any one of claims 1 to 9, characterized in that, Includes the following steps: Mix the weighed film-forming material, filler, cement, dispersant, film-forming aid and water evenly, and then add compatibilizer to obtain micro cement coating.

Images