A modified interpenetrating network structure gel powder and its preparation method and application

Abstract

The present invention belongs to the technical field of honeycomb materials, and particularly relates to a modified interpenetrating network structure gel powder and its preparation method and application. First, a nanocellulose hydrogel is prepared, and then a mixed solution of nylon and modified inorganic nanoparticles is injected into the nanocellulose hydrogel solution. Under the splitting action of nanocellulose and the auxiliary action of polyvinylpyrrolidone, the mixed solution gradually precipitates to form nylon nanofibers, forming an interpenetrating network structure with nanocellulose. During the precipitation process of the nylon solution, the inorganic nanoparticles precipitate on the fiber surface with the nanofibers as carriers, which not only improves the dispersion performance of the inorganic nanoparticles, but also enhances the adhesion of the gel powder to the particles, preventing the particles from rubbing and falling off. This network structure can not only improve the anti-corrosion ability of the coating, but also effectively improve the wear resistance of the coating, and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of honeycomb materials, and particularly relates to a modified interpenetrating network structure gel powder and a preparation method and application thereof. Background Art

[0002] Polyurethane can be divided into two categories according to its dispersion medium: solvent-based polyurethane and waterborne polyurethane (WPU). Waterborne polyurethane is a polyurethane emulsion with water as the dispersion medium. Structurally, the rigid chain segments with ionic groups are hydrophilic, while the flexible chain segments play a hydrophobic role; in terms of performance, it has the excellent characteristics of polyurethane resin. In terms of its impact on the environment, waterborne polyurethane basically does not contain or only contains trace amounts of organic compounds, and has the characteristics of being green, environmentally friendly, safe and non-toxic, low manufacturing cost, and many application fields. The demand for non-toxic, non-flammable and air-pollution-free resins has promoted the rapid development of waterborne polyurethane.

[0003] The structure of waterborne polyurethane is a segmented polymer composed of soft segments and hard segments. Its performance is affected by its composition structure. The soft segments and hard segments form a unique separated microphase, which enables it to obtain many characteristics. Waterborne polyurethane has important application prospects in many industrial applications, such as coatings, adhesives, inks, glass fibers, paper pulp, synthetic leather, biomaterials, membranes and packaging films, and waterproof textiles and other fields.

[0004] The soft segment structure of waterborne polyurethane is composed of oligomeric polyols. The soft segments have a greater impact on its properties such as water resistance and mechanical strength; the hard segment structure is jointly composed of isocyanates and small molecule chain extenders. The hard segments have a greater influence on the hardness, emulsion particle size and bonding performance of the waterborne polyurethane film after film formation. The structure of waterborne polyurethane can be adjusted during production. The soft segments provide flexibility and the hard segments provide rigidity. The main factors affecting its performance are the hydrogen bonds between the hard-soft segments and the hard-hard segments. When the content of the soft segments increases, the crystallinity of the polymer increases and the tensile performance improves, but the polyols are prone to hydrolysis, which will lead to poor water resistance. If you want to improve the hardness and adhesion of waterborne polyurethane, you can appropriately increase the content of the hard segments, but if the content of the hard segments is too high, it will increase the chemical inertness of the chain segments, hinder the diffusion of the molecular chains, and lead to a decrease in adhesion.

[0005] Waterborne polyurethane coatings not only require high gloss, color retention, scratch resistance and flame retardancy, but also can protect materials from the erosion of moisture, organisms and chemical drugs, and are green, safe and pollution-free. They are commonly used in fields such as automobiles, buildings, woodware, paper, leather, fabric coatings, etc. However, waterborne polyurethane coatings use water as a carrier, and their insufficient corrosion resistance is the biggest drawback, which to a certain extent affects their application in the industrial field. In addition, there are also many problems in actual applications. For example, a large number of bubbles will be generated during the reaction with water. First, they are not easy to eliminate. Second, the bubbles may remain in the coated film, affecting the performance of the film. At the same time, due to the low solid content and weak intermolecular forces of waterborne polyurethane coatings, their mechanical properties are usually lower than those of traditional solvent-based polyurethane coatings, which has become a key bottleneck restricting their wide application.

[0006] Blending modification is to directly physically blend the prepared WPU emulsion with other types of emulsions or some nanomaterials, and make them disperse evenly through mechanical stirring or ultrasonic dispersion, so as to prepare the required functional coatings. Nanomaterials refer to materials in which at least one dimension is in the nanoscale range in three-dimensional space or materials composed of them as basic units. Adding nanoparticles to polymers is one of the important methods to improve the performance of polymer materials. At present, there are various nanomaterials used to enhance and improve waterborne polyurethane, mainly including: nanocellulose, nano metal particles, nano carbon materials, nano oxides, etc. CN118852963A discloses a heat-reflective heat-insulating coating, in which nano-titanium dioxide is evenly dispersed in the cellulose aerogel matrix and the polyurethane coating, inhibiting the agglomeration of nano-titanium dioxide, and the cellulose aerogel improves the flame retardant performance of the coating. CN117801653A discloses a high-elastic hydrophobic radiation-curable wood lacquer skin-friendly coating. Adding hyperbranched nanocellulose hydrogel realizes the skin-touch performance of the coating on the wood surface. Through the reaction between the -NH2 groups in the hyperbranched nanocellulose hydrogel and the -NCO groups of the polyurethane acrylate resin in the radiation-curable coating, the physical and mechanical properties and durability of the coating are improved. CN110105531A and CN107474680A also disclose adding gel materials to the coating to improve the corresponding performance of the coating. However, the above technologies only add modified cellulose gels. As a natural fiber material, the mechanical properties of cellulose gels are relatively low; and cellulose gels have a large specific surface area. Due to the influence of intermolecular forces and hydrogen bonds, cellulose gels are prone to aggregation, resulting in poor dispersibility and stability in polyurethane coatings. At the same time, due to the complex preparation process of cellulose gels, high cost and low yield, it is not suitable for large-scale industrialization.

[0007] On the other hand, WPU is an environmentally friendly binder material with characteristics such as easy modification and no pollution, and has great application prospects in the field of tribology. However, with the increasingly harsh working conditions of mechanical systems, due to the poor wear resistance and mechanical properties of pure WPU coatings, their durability and service life are limited, and the pure WPU system coatings can no longer meet the required performance indicators. Therefore, many researchers have introduced micron or nano materials to prepare waterborne polyurethane-based composite coatings to meet the requirements of mechanical properties and tribological properties. Adding nanoparticles to polymers is one of the important methods to improve the performance of polymer materials. At present, there are various nano materials used to enhance and improve waterborne polyurethane, mainly including: nano cellulose, nano metal particles, nano carbon materials, nano oxides, etc. There has been some progress in the research of WPU in the field of tribology, but currently, the WPU coating material system is relatively small, and it is still necessary to further explore the improvement effect of other lubricating materials on the tribological properties of WPU coatings. Summary of the Invention

[0008] The purpose of the present invention is to provide a modified interpenetrating network structure gel powder and its preparation method and application. The gel powder prepared by this method not only has an interpenetrating network structure, and the introduction of nylon resin further improves the mechanical properties of cellulose gel, but also nylon resin itself contains more amide groups, greatly improving the compatibility between nano cellulose and polyurethane coatings; while the addition of inorganic nanoparticles further improves the mechanical properties of the gel material, and when used in polyurethane coatings, it improves the tribological properties of WPU coatings.

[0009] To achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0011] (1) Modify inorganic nanoparticles with an amino silane coupling agent to obtain modified inorganic nanoparticles;

[0012] (2) Place the deionized water dispersion of nano cellulose in an acidic steam bath environment for steam treatment to obtain a nano cellulose hydrogel solution;

[0013] (3) Dissolve nylon powder and polyvinylpyrrolidone in an acidic solvent to obtain a nylon solution, and then add the modified inorganic nanoparticles to the nylon solution, and obtain a nylon mixed solution after ultrasonic dispersion; the mass ratio of polyvinylpyrrolidone to nylon powder is (0.01 - 0.4):1;

[0014] (4) Under stirring conditions, injecting the nylon mixed solution into the nanocellulose hydrogel solution using a syringe with a nozzle; the nozzle is located below the liquid surface of the nanocellulose hydrogel solution; after the injection, exchanging with deionized water solvent to obtain a hydrogel with an interpenetrating network structure;

[0015] (5) The interpenetrating network structure hydrogel is freeze-dried and crushed to obtain a modified interpenetrating network structure gel powder.

[0016] Cellulose is a common high molecular polymer in nature, widely found in plants such as cotton, hemp and wood, and has the advantages of good biocompatibility, renewability, biodegradability, environmental friendliness and non-toxicity. Nanocellulose is made from cellulose, and has at least one dimensional space size of less than 100nm. Nanocellulose composite hydrogel materials not only retain the unique physical and chemical properties of cellulose, such as hydrophilicity, biocompatibility, biodegradability, high chemical activity and dimensional stability, but also have new structural characteristics given by micro-nano processing technology, such as light weight, softness, high specific surface area, high crystallinity, high strength, high modulus and mild chemical activity. Because the surface of cellulose nanofibers has abundant hydroxyl groups, cellulose exhibits high hydrophilicity, and can quickly form a uniform and stable nanocellulose suspension in the coating, which is widely used.

[0017] However, nanocellulose has low mechanical properties and has limited performance improvement on the coating. In addition, nanocellulose is prone to agglomeration due to its large specific surface area and strong hydrogen bonding, and has problems such as poor compatibility with the matrix and uneven dispersion. In the previous work (CN118895018A), the inventor first prepared graphene hydrogel and then directly added nylon / nanocellulose mixed solution. The fibrous filler in this method can only be dispersed outside the hydrogel and cannot penetrate into the gel to form an interpenetrating structure. The nylon therein only plays a role of adhesion and has limited reinforcing effect. Subsequently, the inventor prepared polyimide-nanocellulose modified interpenetrating network structure gel powder. However, polyimide has poor processability and solubility. In order to configure the polyimide solution, it is necessary to start from the monomer raw material, first prepare a polyamic acid solution, and complete imidization in the process of preparing the gel. The above method not only prolongs the process steps; more importantly, polyamic acid, as an intermediate of polyimide, is extremely unstable and cannot be stored for a long time, which greatly limits its industrial application. Nylon itself not only has excellent mechanical properties, but is also soluble in some organic solvents but insoluble in water; in particular, the nylon solution itself is relatively stable and can be stored for a long time at room temperature.

[0018] Based on the above problems, the present invention first prepares nanocellulose gel, and then prepares nylon nanofibers through a precipitation process. The precipitation method is a common process for preparing polymer nanofibers in the prior art. However, when the nylon solution is directly poured into the precipitation solution, fibers of micron or even millimeter size are obtained, and nanofibrous structures cannot be prepared.

[0019] Under stirring conditions, the present invention injects the nylon mixed solution into the nanocellulose hydrogel solution. Among them, the nanocellulose not only plays a role in forming an interpenetrating network structure; more importantly, under the state of rapid stirring, the nanocellulose fibers in the solution can play a "sickle-like" splitting role, splitting the nylon mixed solution into finer filaments, reducing the diameter of the nylon fibers. In order to further make the fiber diameter reach the nanoscale, and at the same time to enable the nylon solution to form a stable filament structure in the rapidly stirred nanocellulose hydrogel solution and promote the formation of the nanofiber structure, the present invention adds a certain amount of polyvinylpyrrolidone. On the one hand, the polyvinylpyrrolidone molecule contains a pyridine ring structure, which can form hydrogen bonds with the amide groups on the nylon, providing an adsorption force, so that the "filaments" of the organic solution of nylon can be stably dispersed in the nanocellulose hydrogel solution; on the other hand, polyvinylpyrrolidone also has a hydrophilic effect and can undergo a hydration reaction with water molecules in the nanocellulose hydrogel solution. When the nylon mixed solution is injected into the nanocellulose hydrogel solution, the adsorption force and hydration force of polyvinylpyrrolidone cause polyvinylpyrrolidone to be dispersed on the outer surface layer of the "filaments" of the nylon organic solution. Since polyvinylpyrrolidone itself has a relatively high viscosity, it can promote the stability of the "filament" structure. Under the shear force provided by stirring and the "splitting" effect of nanocellulose, the "filaments" can gradually become longer and thinner, increasing the aspect ratio of the nylon fibers and promoting the formation of the nanofiber structure. The molecular weight of polyvinylpyrrolidone is not particularly limited, and specifically, its number average molecular weight can be 8000 - 200000.

[0020] WPU is a green and environmentally friendly material with broad application prospects. However, it has problems of poor mechanical properties and wear resistance, and is often modified by introducing other lubricating materials. The present invention improves the mechanical properties and tribological properties of the WPU coating by using the method of gel powder filling and inorganic nanoparticle modification. Porous gel powder with good compatibility is used as a carrier to load inorganic rigid nanoparticles. The porous gel carrier can fully infiltrate the polyurethane resin, improve the adhesion to the inorganic nanoparticles, and prevent the phenomenon of friction and shedding. On the basis of playing an enhancing role, the inorganic nanoparticles further improve the mechanical properties of the gel powder and improve the hardness and friction resistance of the coating. In particular, the inorganic nanoparticles used in the present invention are particles modified with an amino silane coupling agent. When treating the inorganic nanoparticles with an amino silane coupling agent, the silane first hydrolyzes into silanol, and then the silanol group undergoes a dehydration reaction with the hydroxyl group on the surface of the inorganic nanoparticles to form a covalent bond connection. This chemical bonding makes a firm bond between the inorganic nanoparticles and the coupling agent. On the other hand, the amino group at the other end of the amino silane coupling agent is an active polar group, which can easily form hydrogen bonds with the amide group, residual terminal amino group, and terminal carboxyl group on the nylon, further improving the interfacial bonding force between the inorganic nanoparticles and the nylon. Thus, during the precipitation process of the nylon solution, the inorganic nanoparticles precipitate on the fiber surface with the nanofibers as the carrier, not only improving the dispersion performance of the inorganic nanoparticles, but also enhancing the adhesion of the gel powder to the particles and preventing the particles from experiencing friction and shedding. In this way, as the nylon precipitates, an inorganic nanoparticle network structure with an interpenetrating network gel powder as the skeleton is gradually formed, and this network structure can effectively improve the wear resistance of the coating. When the coating surface is subjected to friction, the inorganic nanoparticles in the network structure will roll, thereby changing the sliding friction into rolling friction, and slip will also occur between the inorganic nanoparticles, which all improve the wear resistance of the coating. On the other hand, on the surface of the friction pair, the inorganic nanoparticles can act as a function similar to a "bearing". As the load increases, the local temperature on the friction surface is high, and an inorganic nanoparticle film with toughness and bending strength far exceeding that of ordinary films is formed on the surface. Due to the small particle size of the inorganic nanoparticles, under the action of high temperature and high pressure in the friction contact area, they diffuse and fuse with the matrix, further bonding the coating and the matrix tightly together, preventing both the coating from falling off and serious abrasive wear.

[0021] Nylon is soluble in acids, acetone, and some alcohol organic solvents. The reason for choosing acid as the solvent for nylon in this invention is that acidic solvents can promote the formation of the nano-cellulose gel structure. During the injection of the nylon mixed solution, the intense stirring process will inevitably cause damage to the nano-cellulose gel structure, while the subsequently injected acidic solution can repair the damaged gel structure and promote the stability of the gel structure. If organic solvents such as acetone are used, due to the addition of high-viscosity nylon, the damaged gel cannot be restored and cannot play a splitting role, affecting the formation of nylon nanofibers.

[0022] The precipitation method is a common method for preparing fibers. During the forming process of precipitated fibers, polymer droplets enter the precipitant with shear flow. Under the action of shear force, the polymer droplets are stretched and elongated. At the same time, the organic solvent in the polymer droplets and the coagulant water in the precipitant undergo a double diffusion process, gradually precipitating out polymer fibers. The inventor also used the dropping method to prepare polyimide precipitated nanofibers in previous work. However, the dropping method is applicable to polymers with better fluidity (such as polyamic acid); for nylon polymers, their acidic solutions have high viscosity and poor fluidity. Especially after adding inorganic nanoparticles, the fluidity of the nylon mixed solution is greatly reduced. When using the dropping method to prepare nylon nanofibers, it is difficult to control the droplet size, and the droplets contact the nano-cellulose gel aqueous solution at the liquid surface in a spherical structure, with a small contact area between the droplets and the precipitant; more importantly, under the gravitational action of the inorganic nanoparticles, the splitting effect of the nano-cellulose at the liquid surface is difficult to play, and nylon will precipitate during the contact process between the nylon solution and the precipitant at the liquid surface, further causing the inorganic nanoparticles to fall off and unable to adhere to the nanofibers to form an interpenetrating structure with the nano-cellulose. To increase the contact area between the nylon solution and the precipitant, this invention uses the injection method to prepare precipitated fibers. Under stirring conditions, a syringe with a nozzle is used to inject the nylon mixed solution into the nano-cellulose hydrogel solution; the nozzle is located below the liquid surface of the nano-cellulose hydrogel solution. The nylon solution added by injection can make the solution contact the precipitant in a fine filamentous structure. Compared with the droplets formed by the dropping method, its contact area with the precipitant is greatly increased, and the precipitated nylon fibers have better dispersibility. Moreover, since the nozzle is inside the nano-cellulose hydrogel solution, the splitting effect of the nano-cellulose fibers is more fully exerted, splitting the high-viscosity nylon mixed solution into finer filament bundles, further reducing the diameter of the nylon fibers. Moreover, the injection process is more conducive to dispersing the inorganic nanoparticles into the interior of the gel powder, preventing the particles from falling off the nylon fibers, and can construct a reinforcing network in three-dimensional space, thereby improving the friction resistance of the polyurethane coating.

[0023] Generally speaking, under the splitting action of nanocellulose and the assistance of polyvinylpyrrolidone, the nylon mixed solution can form fine liquid streams in the stirred nanocellulose hydrogel solution and gradually precipitate to form nylon nanofibers, thus forming an interpenetrating network structure with nanocellulose. As nylon precipitates, inorganic nanoparticles gradually disperse on the fiber surface with nylon as the carrier, which is beneficial to constructing a reinforcing network of inorganic nanoparticles in space; thus, only a small amount of inorganic nanoparticles need to be added to significantly improve the mechanical properties and friction resistance of the gel material.

[0024] This composite functional gel material not only retains the original properties of the gel material, but also combines the high strength, thermal stability of nanocellulose and nylon fibers, and the friction resistance of inorganic nanoparticles with the solution properties of the hydrogel, making up for the "soft and weak" defect in the mechanical structure of the nanocellulose gel material, and laying a foundation for the potential applications of the gel.

[0025] Furthermore, the specific preparation process of the modified inorganic nanoparticles in step (1) is as follows: disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino-silane coupling agent, and react at 40 - 60 °C for 1 - 2 h; after the reaction, filter, wash with ethanol, and dry to obtain the modified inorganic nanoparticles.

[0026] Furthermore, the amino-silane coupling agent in step (1) is at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, N-2-aminoethyl-3-aminopropyltriethoxysilane, 3-divinyltriaminepropylmethyldimethoxysilane, 3-divinyltriaminepropyltrimethoxysilane.

[0027] Furthermore, the inorganic nanoparticles in step (1) are at least one of metal nanoparticles, oxide nanoparticles, and carbon nanoparticles. Further, the inorganic nanoparticles are at least one of copper, gold, silver, platinum, silica, titanium dioxide, carbon black, and graphite. Furthermore, the average particle size of the inorganic nanoparticles is 20 - 200 nm.

[0028] Furthermore, the mass ratio of the amino-silane coupling agent to the inorganic nanoparticles in step (1) is (0.1 - 0.4):1.

[0029] Further, the natural cellulose raw material in step (2) is at least one of cotton, bamboo powder, waste paper, flax, sisal, straw, and bagasse; the treatment methods include at least one of high-pressure homogenization method, acid hydrolysis method, enzymatic hydrolysis method, and TEMPO oxidation method; the diameter of the nanocellulose is 10-100 nm, and the length is 5-20 μm. Further, the nanocellulose of the present invention is prepared by the TEMPO oxidation method. The full name of TEMPO is 2,2,6,6-tetramethylpiperidine oxide, which is an organic nitrogen oxide with weak oxidizing properties. This method has a short reaction time, is non-toxic, has a low cost, and the morphology and size of the prepared nanocellulose are relatively uniform.

[0030] Further, the acidic vapor bath in step (2) is at least one of formic acid vapor bath, acetic acid vapor bath, hydrochloric acid vapor bath, and nitric acid vapor bath; the vapor bath treatment time is 2-10 h. The vapor bath method is to place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution.

[0031] Further, the content of nanocellulose in the nanocellulose hydrogel solution in step (2) is 0.5-2 wt%; the mass ratio of nanocellulose to nylon powder in step (3) is (1-2):1; the nylon content in the nylon mixed solution is 1-5 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:(0.1-1). The surface of the inorganic nanoparticles modified by the amino silane coupling agent is rich in active functional groups such as amino groups, which can form strong hydrogen bonds with the amide groups in nylon, not only improving the loading efficiency of the inorganic nanoparticles but also improving their dispersion performance. Further, the mass ratio of nylon powder to modified inorganic nanoparticles is 1:(0.2-0.5). An appropriate amount of inorganic nanoparticles can not only improve the mechanical properties of the gel powder but also avoid the destruction of the gel structure caused by excessive inorganic fillers.

[0032] Further, the acidic solvent used to dissolve nylon is at least one of formic acid solution and sulfuric acid solution.

[0033] Further, in step (4), the nozzle of the spray head has 1-4 nozzles; the aperture of the nozzles is 0.1-1 mm; the injection rate of the nylon mixed solution is 1-3 mL / min. By injecting the nylon solution through the nozzles opened on the spray head, the injection rate can be adjusted by the number of nozzles and the aperture size of the nozzles; compared with the dropping method, the addition rate and morphology of the nylon solution are easier to control. There is no special limitation on the number and aperture of the nozzles on the spray head, and they can be adjusted according to the required injection rate. In particular, when multiple nozzles are used, the nozzles are evenly distributed on the spray head. The evenly distributed spray head is more conducive to evenly injecting the nylon solution into the nanocellulose gel solution. The nanocellulose fibers can fully play a splitting role, splitting the nylon mixed solution into finer filaments, and reducing the diameter of the nylon fibers. Further, the number of nozzles is 1, and the aperture of the nozzles is 0.3 mm. Further, a common 1 mL or 2 mL syringe on the market can be selected for injection. Further, the injection rate is 1.2-2 mL / min. By adjusting the injection rate, the nylon mixed solution can be fully dispersed into the nanocellulose hydrogel solution, and the splitting effect of the nanocellulose can be fully exerted.

[0034] Further, in step (3), the nylon is at least one of nylon 6, nylon 66, nylon 12, nylon 56, nylon 610, and nylon 1212.

[0035] Further, in step (4), the stirring rate is 600-800 rpm. An appropriate stirring rate can not only avoid the reduction of the aspect ratio of the nylon nanofibers caused by too fast stirring rate, but also prevent the defect of too thick diameter caused by too slow stirring rate.

[0036] On the other hand, the present invention also provides an application of the modified interpenetrating network structure gel powder, using the modified interpenetrating network structure gel powder in the field of polyurethane coatings.

[0037] The polyurethane coating comprises the following components in parts by weight: 100 parts of aqueous polyurethane dispersion; 0.5-5 parts of modified interpenetrating network structure gel powder.

[0038] The modified interpenetrating network structure gel powder prepared by the injection method can enable full interaction between nanocellulose and nylon nanofibers, resulting in a more regular gel structure and a higher porosity. The higher porosity is beneficial for the full infiltration of polyurethane, improving the bonding strength between the gel powder and the polyurethane coating, thereby further enhancing the mechanical properties and anti-corrosion ability of the coating. Moreover, a large number of hydroxyl groups present on the surface of nanocellulose in the gel powder will form hydrogen bonds with amino-modified inorganic nanoparticles, nylon nanofibers, and polyurethane matrix molecules, enhancing the interfacial interaction between the gel powder and the polyurethane matrix, giving full play to the properties of the gel powder, and improving the friction resistance of polyurethane. Nylon nanofibers have high mechanical properties, solving the "soft and weak" defect of nanocellulose gel materials in terms of mechanical structure. The formation of an interpenetrating structure between nanocellulose and nylon nanofibers allows the two to fully entangle, exerting a synergistic strengthening effect and improving the density and mechanical properties of the polyurethane coating.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) The modified interpenetrating network structure gel powder prepared by the injection method can enable full interaction between nanocellulose and nylon nanofibers, resulting in a more regular gel structure and a higher porosity. The higher porosity is beneficial for the full infiltration of polyurethane, improving the bonding strength between the gel powder and the polyurethane coating, thereby further enhancing the mechanical properties and anti-corrosion ability of the coating.

[0041] (2) First, prepare a nanocellulose hydrogel to construct a gel material based on nanocellulose. Under stirring conditions, inject a nylon mixed solution into the nanocellulose hydrogel solution. Under the splitting action of nanocellulose and the auxiliary action of polyvinylpyrrolidone, the nylon mixed solution can form fine liquid streams in the stirred nanocellulose hydrogel solution and gradually precipitate to form nylon nanofibers, thus forming an interpenetrating network structure with nanocellulose.

[0042] (3) During the precipitation process of the nylon solution, inorganic nanoparticles precipitate on the fiber surface with the nanofibers as carriers, not only improving the dispersion performance of the inorganic nanoparticles but also enhancing the adhesion of the gel powder to the particles and preventing particle friction and shedding. In this way, as nylon precipitates, an inorganic nanoparticle network structure with an interpenetrating network gel powder as the backbone is gradually formed, and this network structure can effectively improve the wear resistance of the coating.

[0043] (4) Compared with synthetic fibers such as polyimide, nylon fibers have a lower cost, and the nylon solution does not need to be prepared in advance and can be used as needed, greatly reducing the production cost and process steps, and having broad market application prospects. Description of the Drawings

[0044] Figure 1The simple injection device adopted by the present invention;

[0045] Figure 2 It is the scanning electron microscope picture of the gel powder prepared in Example 10;

[0046] Figure 3 It is the scanning electron microscope picture of the gel powder prepared in Comparative Example 1. Detailed implementation manners

[0047] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application. Unless otherwise specified, the preparation raw materials and process conditions in the following examples and comparative examples are the same. Among them, the specific preparation process of nanocellulose in the following examples and comparative examples is as follows: (1) Removal of wax in bamboo powder: Add bamboo powder into a mixed solution composed of toluene and ethanol (volume ratio 3:1), mechanically stir for 24 hours, wash and dry for standby; (2) Removal of lignin in bamboo powder: Add the product of step (1) into a three-necked flask, then add 2wt% sodium chlorite solution, adjust the pH to 4, and react at 80°C for 6h, wash and dry for standby; (3) Removal of hemicellulose in bamboo powder: Add the product of step (2) into 5wt% potassium hydroxide solution, stir and react at 90°C for 3h, wash and dry to obtain bamboo powder cellulose; (4) Molding of nanocellulose: Disperse bamboo powder cellulose in a mixed solution of TEMPO, sodium bromide and distilled water, then slowly add sodium hypochlorite to the solution, stir evenly, then adjust the pH to 10 and react for 4h, centrifuge and wash to obtain TEMPO-treated cellulose; The mass ratio of bamboo powder cellulose, TEMPO, sodium bromide and sodium hypochlorite is 1:0.02:0.1:2; Place the TEMPO-treated cellulose in an ultrasonic cell disruptor for 30 min and perform freeze-drying treatment to obtain nanocellulose with a diameter of 80 nm and a length of 10 μm.

[0048] Example 1

[0049] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0050] (1) Disperse inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent, and react at 40°C for 2h; After the reaction is completed, filter, then wash with ethanol and dry to obtain modified inorganic nanoparticles; The amino silane coupling agent is γ-aminopropyltriethoxysilane; The inorganic nanoparticles are silica; The average particle size of the inorganic nanoparticles is 120 nm; The mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1;

[0051] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 4 h; the content of nanocellulose in the nanocellulose hydrogel solution is 0.5 wt%.

[0052] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and obtain a nylon mixed solution after ultrasonic dispersion; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.04:1; the mass ratio of nanocellulose to nylon powder is 1:1; the nylon content in the nylon mixed solution is 1 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.2; the nylon is nylon 66.

[0053] (4) Under stirring conditions, inject the nylon mixed solution into the nanocellulose hydrogel solution using a syringe with a nozzle; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle orifice with an orifice diameter of 0.3 mm; the injection rate of the nylon mixed solution is 1.2 mL / min; the stirring rate is 600 rpm.

[0054] (5) Freeze-dry the hydrogel with an interpenetrating network structure and crush it to obtain a modified interpenetrating network structure gel powder.

[0055] A polyurethane coating comprises the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of the modified interpenetrating network structure gel powder.

[0056] Example 2

[0057] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0058] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 60 °C for 1 h; after the reaction, filter, then wash with ethanol and dry to obtain the modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0059] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 8 h; the content of nanocellulose in the nanocellulose hydrogel solution is 2 wt%.

[0060] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% formic acid aqueous solution to obtain a nylon solution. The number average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and disperse them ultrasonically to obtain a nylon mixed solution; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.25:1; the mass ratio of nanocellulose to nylon powder is 2:1; the nylon content in the nylon mixed solution is 5 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.5; the nylon is nylon 66.

[0061] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle with a nozzle aperture of 0.3 mm; the injection rate of the nylon mixed solution is 2 mL / min; the stirring rate is 800 rpm.

[0062] (5) Freeze-dry the hydrogel with an interpenetrating network structure and pulverize it to obtain a modified interpenetrating network structure gel powder.

[0063] A polyurethane coating contains the following components in parts by weight: 100 parts of aqueous polyurethane dispersion; 3 parts of modified interpenetrating network structure gel powder.

[0064] Example 3

[0065] A preparation method of a modified interpenetrating network structure gel powder includes the following steps:

[0066] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 60 °C for 2 h; after the reaction, filter, then wash with ethanol and dry to obtain the modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0067] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 8 h; the content of nanocellulose in the nanocellulose hydrogel solution is 0.5 wt%.

[0068] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.25:1; the mass ratio of nanocellulose to nylon powder is 1:1; the nylon content in the nylon mixed solution is 1 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.5; the nylon is nylon 66.

[0069] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle with a nozzle aperture of 0.3 mm; the injection rate of the nylon mixed solution is 1.2 mL / min; the stirring rate is 800 rpm.

[0070] (5) Freeze-dry the hydrogel with an interpenetrating network structure and crush it to obtain a modified interpenetrating network structure gel powder.

[0071] A polyurethane coating comprises the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of a modified interpenetrating network structure gel powder.

[0072] Example 4

[0073] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0074] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 45 °C for 1.8 h; after the reaction, filter, then wash with ethanol and dry to obtain the modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0075] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 5 h; the content of nanocellulose in the nanocellulose hydrogel solution is 1 wt%.

[0076] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number-average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.15:1; the mass ratio of nanocellulose to nylon powder is 1.2:1; the nylon content in the nylon mixed solution is 2 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.3; the nylon is nylon 66.

[0077] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle orifice with an orifice diameter of 0.3 mm; the injection rate of the nylon mixed solution is 1.4 mL / min; the stirring rate is 650 rpm.

[0078] (5) Freeze-dry the hydrogel with an interpenetrating network structure and pulverize it to obtain a modified interpenetrating network structure gel powder.

[0079] A polyurethane coating contains the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of a modified interpenetrating network structure gel powder.

[0080] Example 5

[0081] A preparation method of a modified interpenetrating network structure gel powder includes the following steps:

[0082] (1) Disperse inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 55 °C for 1.3 h; after the reaction, filter, then wash with ethanol and dry to obtain modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0083] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 7 h; the content of nanocellulose in the nanocellulose hydrogel solution is 1.6 wt%.

[0084] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number-average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and obtain a nylon mixed solution after ultrasonic dispersion; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.2:1; the mass ratio of nanocellulose to nylon powder is 1.8:1; the nylon content in the nylon mixed solution is 4 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.4; the nylon is nylon 66.

[0085] (4) Under stirring conditions, inject the nylon mixed solution into the nanocellulose hydrogel solution using a syringe with a nozzle; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle opening with a nozzle aperture of 0.3 mm; the injection rate of the nylon mixed solution is 1.8 mL / min; the stirring rate is 750 rpm.

[0086] (5) Freeze-dry the hydrogel with an interpenetrating network structure and pulverize it to obtain a modified interpenetrating network structure gel powder.

[0087] A polyurethane coating, comprising the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of a modified interpenetrating network structure gel powder.

[0088] Example 6

[0089] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0090] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent, and react at 50 °C for 1.5 h; after the reaction, filter, then wash with ethanol and dry to obtain the modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0091] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 6 h; the nanocellulose content in the nanocellulose hydrogel solution is 1.2 wt%.

[0092] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution. The number-average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.4:1; the mass ratio of nanocellulose to nylon powder is 1.5:1; the nylon content in the nylon mixed solution is 3 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.3; the nylon is nylon 66.

[0093] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle orifice with an orifice diameter of 0.3 mm; the injection rate of the nylon mixed solution is 1.6 mL / min; the stirring rate is 700 rpm.

[0094] (5) Freeze-dry the hydrogel with an interpenetrating network structure and pulverize it to obtain a modified interpenetrating network structure gel powder.

[0095] A polyurethane coating contains the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of a modified interpenetrating network structure gel powder.

[0096] Example 7

[0097] A preparation method of a modified interpenetrating network structure gel powder includes the following steps:

[0098] (1) Disperse inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 50 °C for 1.5 h; after the reaction, filter, wash with ethanol, and dry to obtain modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silicon dioxide; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0099] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 6 h; the content of nanocellulose in the nanocellulose hydrogel solution is 1.2 wt%.

[0100] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number-average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and obtain a nylon mixed solution after ultrasonic dispersion; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.2:1; the mass ratio of nanocellulose to nylon powder is 1.5:1; the nylon content in the nylon mixed solution is 3 wt%; the mass ratio of nylon powder to the modified inorganic nanoparticles is 1:0.3; the nylon is nylon 66.

[0101] (4) Under stirring conditions, inject the nylon mixed solution into the nanocellulose hydrogel solution using a syringe with a nozzle; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle orifice with an orifice diameter of 0.3 mm; the injection rate of the nylon mixed solution is 3 mL / min; the stirring rate is 700 rpm.

[0102] (5) Freeze-dry the hydrogel with an interpenetrating network structure and pulverize it to obtain a modified interpenetrating network structure gel powder.

[0103] A polyurethane coating comprises the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of the modified interpenetrating network structure gel powder.

[0104] Example 8

[0105] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0106] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent, and react at 50 °C for 1.5 h; after the reaction, filter, and then wash with ethanol and dry to obtain the modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0107] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 6 h; the nanocellulose content in the nanocellulose hydrogel solution is 1.2 wt%.

[0108] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% formic acid aqueous solution to obtain a nylon solution. The number-average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.2:1; the mass ratio of nanocellulose to nylon powder is 1.5:1; the nylon content in the nylon mixed solution is 3 wt%; the mass ratio of nylon powder to the modified inorganic nanoparticles is 1:0.1; the nylon is nylon 66.

[0109] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle orifice with an orifice diameter of 0.3 mm; the injection rate of the nylon mixed solution is 1.6 mL / min; the stirring rate is 700 rpm.

[0110] (5) Freeze-dry the hydrogel with an interpenetrating network structure and pulverize it to obtain a modified interpenetrating network structure gel powder.

[0111] A polyurethane coating contains the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of the modified interpenetrating network structure gel powder.

[0112] Example 9

[0113] A preparation method of a modified interpenetrating network structure gel powder includes the following steps:

[0114] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 50 °C for 1.5 h; after the reaction, filter, then wash with ethanol and dry to obtain the modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0115] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 6 h; the nanocellulose content in the nanocellulose hydrogel solution is 1.2 wt%.

[0116] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.2:1; the mass ratio of nanocellulose to nylon powder is 1.5:1; the nylon content in the nylon mixed solution is 3 wt%; the mass ratio of nylon powder to the modified inorganic nanoparticles is 1:1; the nylon is nylon 66.

[0117] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid surface of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle opening with a nozzle opening diameter of 0.3 mm; the injection rate of the nylon mixed solution is 1.6 mL / min; the stirring rate is 700 rpm.

[0118] (5) Freeze-dry the hydrogel with an interpenetrating network structure and crush it to obtain a modified interpenetrating network structure gel powder.

[0119] A polyurethane coating contains the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of the modified interpenetrating network structure gel powder.

[0120] Example 10

[0121] A preparation method of a modified interpenetrating network structure gel powder includes the following steps:

[0122] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 50 °C for 1.5 h; after the reaction, filter, then wash with ethanol and dry to obtain the modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0123] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 6 h; the content of nanocellulose in the nanocellulose hydrogel solution is 1.2 wt%.

[0124] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.2:1; the mass ratio of nanocellulose to nylon powder is 1.5:1; the nylon content in the nylon mixed solution is 3 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.3; the nylon is nylon 66.

[0125] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection is carried out using a 1 mL medical syringe, that is, the nozzle has 1 nozzle opening with a nozzle diameter of 0.3 mm; the injection rate of the nylon mixed solution is 1.6 mL / min; the stirring rate is 700 rpm.

[0126] (5) Freeze-dry the hydrogel with an interpenetrating network structure and crush it to obtain a modified interpenetrating network structure gel powder.

[0127] A polyurethane coating, comprising the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of a modified interpenetrating network structure gel powder.

[0128] Comparative Example 1

[0129] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0130] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 50 °C for 1.5 h; after the reaction, filter, and then wash with ethanol and dry to obtain modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0131] (2) Place the deionized water dispersion of nanocellulose in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 6 h; the content of nanocellulose in the nanocellulose hydrogel solution is 1.2 wt%.

[0132] (3) Dissolve nylon powder and polyvinylpyrrolidone in an 88 wt% aqueous formic acid solution to obtain a nylon solution, and the number average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles to the nylon solution and obtain a nylon mixed solution after ultrasonic dispersion; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.2:1; the mass ratio of nanocellulose to nylon powder is 1.5:1; the nylon content in the nylon mixed solution is 3 wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:0.3; the nylon is nylon 66.

[0133] (4) Under stirring conditions, drop the nylon mixed solution into the nanocellulose hydrogel solution; after the dropping is completed, perform solvent exchange with deionized water to obtain a hydrogel with an interpenetrating network structure; the dropping rate of the nylon mixed solution is 1.6 mL / min; the stirring rate is 700 rpm.

[0134] (5) Freeze-dry the hydrogel with an interpenetrating network structure and pulverize it to obtain a modified interpenetrating network structure gel powder.

[0135] A polyurethane coating, comprising the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of a modified interpenetrating network structure gel powder.

[0136] Comparative Example 2

[0137] A preparation method of a modified interpenetrating network structure gel powder, comprising the following steps:

[0138] (1) Disperse the inorganic nanoparticles in a mixed solution formed by ethanol and water, then add an amino silane coupling agent and react at 50 °C for 1.5 h; after the reaction is completed, filter, then wash with ethanol and dry to obtain modified inorganic nanoparticles; the amino silane coupling agent is γ-aminopropyltriethoxysilane; the inorganic nanoparticles are silica; the average particle size of the inorganic nanoparticles is 120 nm; the mass ratio of the amino silane coupling agent to the inorganic nanoparticles is 0.3:1.

[0139] (2) Place the deionized water dispersion of nanocellulose and polyvinylpyrrolidone in an acidic vapor bath environment for vapor treatment to obtain a nanocellulose hydrogel solution; the diameter of the nanocellulose is 80 nm and the length is 10 μm; the acidic vapor bath is a formic acid vapor bath; the vapor bath treatment time is 6 h; the content of nanocellulose in the nanocellulose hydrogel solution is 1.2 wt%.

[0140] (3) Dissolve nylon powder into an 88 wt% formic acid aqueous solution to obtain a nylon solution, where the number-average molecular weight of polyvinylpyrrolidone is 30,000; then add the modified inorganic nanoparticles into the nylon solution and obtain a nylon mixed solution after ultrasonic dispersion; the mass ratio of polyvinylpyrrolidone to nylon powder is 0.2:1; the mass ratio of nanocellulose to nylon powder is 1.5:1; the nylon content in the nylon mixed solution is 3 wt%; the mass ratio of nylon powder to the modified inorganic nanoparticles is 1:0.3; the nylon is nylon 66;

[0141] (4) Under stirring conditions, use a syringe with a nozzle to inject the nylon mixed solution into the nanocellulose hydrogel solution; the nozzle is located below the liquid level of the nanocellulose hydrogel solution; after injection, through solvent exchange with deionized water, a hydrogel with an interpenetrating network structure is obtained; the injection uses a 1 mL medical syringe, that is, the nozzle has 1 nozzle orifice with an orifice diameter of 0.3 mm; the injection rate of the nylon mixed solution is 1.6 mL / min; the stirring rate is 700 rpm;

[0142] (5) Freeze-dry the hydrogel with an interpenetrating network structure and crush it to obtain a modified interpenetrating network structure gel powder.

[0143] A polyurethane coating, comprising the following components in parts by weight: 100 parts of an aqueous polyurethane dispersion; 3 parts of the modified interpenetrating network structure gel powder.

[0144] Performance testing: Conduct hardness testing (GB / T 6739-2006), film adhesion testing (GB / T 5210-2006), salt spray resistance testing (GB / T 1771-2007), and abrasion resistance testing (GB / T 1768-2006) on the polyurethane coatings prepared in Examples 1-10 and Comparative Examples 1-2; the test results are shown in Table 1.

[0145]

[0146] Figure 2-3 Scanning electron microscope pictures of the gel powders prepared in Example 10 and Comparative Example 1 respectively. Combining the data in Table 1, from Figure 2It can be seen that the precipitated nylon nanofibers and nanocellulose form an interpenetrating network structure, and the inorganic nanoparticles are uniformly dispersed on the fiber surface. This shows that under the tearing action of nanocellulose and the auxiliary action of polyvinylpyrrolidone, the nylon mixed solution can form fine liquid streams in the stirred nanocellulose hydrogel solution and gradually precipitate to form nylon nanofibers, thus forming an interpenetrating network structure with nanocellulose. As nylon precipitates, the inorganic nanoparticles gradually disperse onto the fiber surface with nylon as the carrier, which is beneficial to constructing a reinforcing network of inorganic nanoparticles in space; thus, only a small amount of inorganic nanoparticles need to be added to significantly improve the mechanical properties and friction resistance of the gel material. Comparative Example 1 shows that when preparing nylon nanofibers by the dropping method, it is difficult to control the droplet size, and the droplets contact the nanocellulose gel aqueous solution at the liquid surface in a spherical structure, with a small contact area between the droplets and the precipitation solution; more importantly, under the gravitational action of the inorganic nanoparticles, it is difficult for the tearing action of nanocellulose at the liquid surface to play, and nylon will precipitate during the contact process between the nylon solution and the precipitation solution liquid surface, further causing the detachment of the inorganic nanoparticles and being unable to adhere to the nanofibers to form an interpenetrating structure with nanocellulose. From Figure 3 It can also be seen that nylon does not form a fibrous structure but instead adheres to the surface of nanocellulose in a lamellar shape, and the modified inorganic nanoparticles are scattered on the nylon lamellae. The porosity of this gel structure is relatively low, seriously affecting the infiltration efficiency of polyurethane. Since the inorganic nanoparticles are wrapped by nylon, it is difficult for them to play the roles of lubrication and wear resistance. Comparative Example 2 shows that polyvinylpyrrolidone needs to be added to the nylon solution in advance. If it is added to the nanocellulose aqueous dispersion in advance, due to the abundant hydroxyl groups on the surface of nanocellulose, strong hydrogen bonds will be formed with polyvinylpyrrolidone and it will not be able to adhere to the subsequently dropped nylon surface, and cannot stably disperse the "filament bundle" of the nylon solution in the nanocellulose hydrogel solution, affecting the formation of polymer nanofibers.

[0147] The above are only the preferred embodiments of the present invention and do not impose any other form of limitation on the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope claimed by the present invention.

Claims

1. A method for preparing a modified interpenetrating network structure gel powder, characterized in that: The following steps are involved: (1) Using an aminosilane coupling agent to modify inorganic nanoparticles to prepare modified inorganic nanoparticles; (2) placing the deionized water dispersion of nanocellulose in an acidic steam bath environment for steam treatment to obtain a nanocellulose hydrogel solution; (3) dissolving nylon powder and polyvinyl pyrrolidone in an acidic solvent to obtain a nylon solution, then adding the modified inorganic nanoparticles into the nylon solution, and obtaining a nylon mixed solution after ultrasonic dispersion; The mass ratio of polyvinyl pyrrolidone to nylon powder is (0.01-0.4):1; the mass ratio of nanocellulose to nylon powder is (1-2):1; the nylon content in the nylon mixed solution is 1-5wt%; the mass ratio of nylon powder to modified inorganic nanoparticles is 1:(0.1-1); (4) Under stirring conditions, injecting the nylon mixed solution into the nanocellulose hydrogel solution using a syringe with a nozzle; the nozzle is located below the liquid surface of the nanocellulose hydrogel solution; after the injection, exchanging with deionized water solvent to obtain a hydrogel with an interpenetrating network structure; (5) The interpenetrating network structure hydrogel is freeze-dried and crushed to obtain a modified interpenetrating network structure gel powder.

2. The method for preparing a modified interpenetrating network structure gel powder according to claim 1, characterized in that: The specific preparation process of the modified inorganic nanoparticles in step (1) is as follows: dispersing the inorganic nanoparticles in a mixed solution formed by ethanol and water, then adding an aminosilane coupling agent, and reacting at 40-60° C. for 1-2 hours; filtering after the reaction, washing with ethanol, and drying to obtain the modified inorganic nanoparticles.

3. The method for preparing a modified interpenetrating network structure gel powder according to claim 1, characterized in that: In step (1), the aminosilane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, N-2-aminoethyl-3-aminopropyltriethoxysilane, 3-diethylenetriaminopropylmethyldimethoxysilane and 3-diethylenetriaminopropyltrimethoxysilane.

4. The method for preparing a modified interpenetrating network structure gel powder according to claim 1, characterized in that: In step (1), the inorganic nanoparticles are at least one of metal nanoparticles, oxide nanoparticles, and carbon nanoparticles; and the average particle size of the inorganic nanoparticles is 20-200 nm.

5. The method for preparing a modified interpenetrating network structure gel powder according to claim 1, characterized in that: In step (1), the mass ratio of the aminosilane coupling agent to the inorganic nanoparticles is (0.1-0.4):

1.

6. The method for preparing a modified interpenetrating network structure gel powder according to claim 1, characterized in that: The nanocellulose in step (2) has a diameter of 10-100 nm and a length of 5-20 μm; the acidic vapor bath is at least one of a formic acid vapor bath, an acetic acid vapor bath, a hydrochloric acid vapor bath, and a nitric acid vapor bath; the vapor bath treatment time is 4-8 hours; the nanocellulose content in the nanocellulose hydrogel solution in step (2) is 0.5-2 wt%; and the acidic solvent in step (3) is at least one of a formic acid solution and a sulfuric acid solution.

7. The method for preparing a modified interpenetrating network structure gel powder according to claim 1, characterized in that: In step (4), the nozzle has 1-4 nozzles; the nozzle aperture is 0.1-1 mm; the nylon mixed solution injection rate is 1-3 mL / min; the nylon in step (3) is at least one of nylon 6, nylon 66, nylon 12, nylon 56, nylon 610, and nylon 1212; and the stirring rate in step (4) is 600-800 rpm.

8. A modified interpenetrating network structure gel powder, characterized in that: The modified interpenetrating network structure gel powder is prepared by the preparation method of any one of claims 1 to 7.

9. An application of a modified interpenetrating network structure gel powder as claimed in claim 8, characterized in that: The modified interpenetrating network structure gel powder is used in the field of polyurethane coatings.

10. A polyurethane coating, characterized in that: The invention comprises the following components in parts by weight: 100 parts of aqueous polyurethane dispersion; and 0.5-5 parts of the modified interpenetrating network structure gel powder according to claim 8.

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