Graphene aldehyde-removing heat insulation wallpaper and wall cloth and preparation method thereof

Abstract

The present application relates to the technical field of functional decoration material, in particular to a graphene aldehyde-removing heat-insulating wallpaper and wall cloth and a preparation method thereof, and the preparation material of the graphene aldehyde-removing heat-insulating wallpaper and wall cloth comprises a base layer of raw paper and a multifunctional coating layer attached to the surface of the base layer, wherein the coating layer is composed of amino-modified graphene, nano-titanium dioxide, hollow glass microbeads and water-based polyurethane emulsion.In the present application, the three-dimensional heat-conducting adsorption network is constructed by grafting modification of graphene oxide using a silane coupling agent, which significantly improves the chemical capture efficiency and photocatalytic degradation rate of formaldehyde molecules, the hollow glass microbeads are introduced to form a dense vacuum heat-insulating barrier inside the coating layer, which effectively blocks the heat exchange path between the wall and the indoor environment, the interface compatibility between the inorganic filler and the organic resin matrix is enhanced by chemical bonding, the hidden dangers of coating cracking and falling off and secondary release of pollutants are completely eliminated, and the continuous improvement of indoor air quality and the effective reduction of building energy consumption are realized.

Description

Technical Field

[0001] This invention relates to the field of functional decorative materials technology, and in particular to a graphene-based formaldehyde-removing and heat-insulating wallpaper, wall covering, and its preparation method. Background Technology

[0002] The field of building decoration materials technology involves the research and development and manufacturing technology of interior wall coverings. Among them, traditional functional wallpaper refers to wall decoration materials prepared by physically mixing a resin coating containing activated carbon powder or ordinary heat-insulating filler onto the surface of a substrate.

[0003] In existing technologies, physical adsorption materials such as activated carbon are prone to saturation, leading to secondary release of pollutants. Ordinary heat insulation fillers have poor dispersibility, resulting in uneven distribution of thermal resistance in the coating. The resin matrix is ​​prone to residual volatile solvents during the curing process. The lack of effective chemical bonding between functional components leads to insufficient interfacial bonding strength. During long-term use, the coating is prone to cracking or powdering and peeling. It is difficult to achieve both long-lasting air purification effect and stable thermal insulation performance, resulting in a significant increase in the cost of indoor environmental treatment. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a graphene formaldehyde-removing and heat-insulating wallpaper, wall covering and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a graphene formaldehyde-removing and heat-insulating wallpaper, characterized in that the preparation materials of the graphene formaldehyde-removing and heat-insulating wallpaper include: a non-woven base paper substrate and a coating applied to the non-woven base paper substrate, the coating being composed of aminated modified graphene, nano titanium dioxide, hollow glass microspheres and water-based polyurethane emulsion.

[0006] As a further aspect of the present invention, the sheet diameter of the aminated modified graphene is 5 to 15 micrometers, and the mass percentage content of nitrogen on its surface is 8% to 12%. Nano titanium dioxide has an anatase crystal structure with an average particle size distribution between 20 and 50 nanometers, and its surface is coated with alumina or silicon dioxide. The true density of hollow glass microspheres is 0.25 to 0.60 g / cm³, and their compressive strength is greater than 15 MPa. The waterborne polyurethane emulsion is an anionic aliphatic polyurethane dispersion with a solid content of 40% to 50%. The mass ratio of aminated modified graphene to nano-titanium dioxide in the coating is 1:3 to 1:5.

[0007] A graphene-based formaldehyde-removing and heat-insulating wall covering, characterized in that the wall covering uses the aforementioned graphene-based formaldehyde-removing and heat-insulating wallpaper, and the materials used to prepare the graphene-based formaldehyde-removing and heat-insulating wall covering include: a textile fiber base layer and a coating impregnated inside the textile fiber base layer or coated on the surface of the textile fiber base layer, the coating being composed of aminated modified graphene, nano-titanium dioxide, hollow glass microspheres and water-based polyurethane emulsion.

[0008] A method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall coverings, the method being used to prepare the above-mentioned graphene formaldehyde-removing and heat-insulating wallpaper and wall coverings, comprising the following steps: S1: Adding graphene oxide dispersion and γ-aminopropyltriethoxysilane to a reaction vessel at a ratio of 1:2, stirring and reacting in an oil bath at 80°C for 6 hours, then attaching amino groups via silane coupling, followed by centrifugation and drying to prepare aminated modified graphene; S2: Aminated modified graphene, nano titanium dioxide and hollow glass microspheres are added to waterborne polyurethane emulsion and dispersed at high speed of 2000 rpm for 30 minutes to construct a formaldehyde-removing and heat-insulating slurry. S3: Use a micro-gravure coating machine to coat the formaldehyde-removing and heat-insulating slurry onto the non-woven base paper or textile fiber base, controlling the gap to 0.15mm and the speed to 20m / min, to generate a pre-made wet film. S4: The pre-made wet film is introduced into a hot air drying oven and cross-linked and cured by a gradient temperature increase of 60-120℃. After cooling and winding, the graphene formaldehyde-removing and heat-insulating wallpaper and wall covering are cut out.

[0009] As a further aspect of the present invention, the preparation process of aminated modified graphene includes: S11: adding graphene oxide powder with a sheet thickness of less than 1 nanometer to deionized water, and using an ultrasonic crusher at a frequency of 40 kHz to perform exfoliation and dispersion treatment until a uniform and precipitate-free graphene oxide dispersion is formed. S12: Add γ-aminopropyltriethoxysilane diluted with anhydrous ethanol dropwise to the graphene oxide dispersion, and simultaneously start a magnetic stirrer to continuously mix at a speed of 500 rpm. Raise the temperature of the reaction system to 80 degrees Celsius and maintain a constant temperature reaction to promote the condensation reaction between the silane hydrolysis products and the hydroxyl groups on the surface of graphene oxide to generate a reaction mixture. S13: Pump the reaction mixture into a high-speed centrifuge, set the speed to 10,000 revolutions per minute for solid-liquid separation, discard the supernatant and wash the precipitate three times with anhydrous ethanol to obtain a pure precipitate. S14: The pure precipitate was placed in a vacuum freeze dryer and sublimated at -50 degrees Celsius and a vacuum of 10 Pascals to obtain fluffy powdered aminated modified graphene.

[0010] As a further aspect of the present invention, the construction process of the formaldehyde-removing heat insulation slurry includes: S21: Aminated modified graphene and nano titanium dioxide are put into a high-speed mixer and dry premixed at a speed of 500 rpm for 10 minutes to obtain mixed powder. S22: The mixed powder and hollow glass microspheres are added to the water-based polyurethane emulsion in batches, while the mixture is stirred at low speed using a dispersion disc to form a premixed liquid. S23: Transfer the premixed liquid to the dispersion vessel, turn on the high-shear disperser to disperse at 2000 rpm, and control the temperature during the dispersion process to not exceed 40 degrees Celsius to obtain the formaldehyde-removing heat insulation slurry.

[0011] As a further embodiment of the present invention, the pre-fabricated wet film generation process includes: S31: loading the non-woven base paper substrate or textile fiber substrate onto the unwinding roller, adjusting the unwinding tension to 5-10 Newtons through the tension controller, and pulling the non-woven base paper substrate or textile fiber substrate to the coating station. S32: The formaldehyde-removing and heat-insulating slurry is transported to the surface of the micro-gravure roller using a circulating pump, and the excess slurry is scraped off by a scraper to form a uniform material layer on the surface of the micro-gravure roller. S33: Drive the nonwoven base paper substrate or textile fiber substrate to make reverse contact with the micro-gravure roller, control the gap to 0.15mm, so that the uniform material layer is transferred to the surface of the nonwoven base paper substrate or textile fiber substrate to generate a pre-made wet film.

[0012] As a further aspect of the present invention, the cutting process of graphene formaldehyde-removing and heat-insulating wallpaper and wall covering includes: S41: conveying the pre-made wet film to the first temperature zone of the hot air drying box, preheating and drying at 60-80 degrees Celsius to remove free water in the coating and form a semi-dry coating. S42: The semi-dry coating is transported to the second temperature zone and dried at 80-100 degrees Celsius to allow the polyurethane particles to fuse and form a continuous film. S43: The continuous film layer is transported to the third temperature zone and cross-linked at 100-120 degrees Celsius for 3-5 minutes to obtain a cured coating; S44: The base layer with the cured coating is cooled to room temperature by a cooling roller and then wound up using a winding machine to cut graphene formaldehyde-removing and heat-insulating wallpaper and wall covering.

[0013] As a further aspect of the present invention, the purity of γ-aminopropyltriethoxysilane is greater than 98%, and it is pre-dissolved in anhydrous ethanol to prepare a silanol solution with a mass fraction of 20% to 30% before being added to the reaction vessel.

[0014] As a further aspect of the present invention, in S2, the viscosity of the formaldehyde-removing heat insulation slurry is controlled at 1000 to 3000 mPa·s, and the pH value is adjusted to 7.5 to 8.5.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, a three-dimensional thermally conductive adsorption network is constructed by grafting graphene oxide with a silane coupling agent, which significantly improves the chemical capture efficiency and photocatalytic degradation rate of formaldehyde molecules. Hollow glass microspheres are introduced into the coating to form a dense vacuum insulation barrier, effectively blocking the heat exchange path between the wall and the room. Chemical bonding is used to enhance the interfacial compatibility between inorganic fillers and organic resin matrix, completely eliminating the hidden dangers of coating cracking and peeling and secondary release of pollutants, thereby achieving continuous improvement of indoor air quality and effective reduction of building energy consumption. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the graphene-based formaldehyde-removing and heat-insulating wallpaper and wall covering of this invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the software-based technical solution is described in detail below with reference to system architecture diagrams and embodiments. It should be understood that the specific embodiments described herein are only for explaining the technical solutions of this invention and do not constitute a limitation on the scope of protection.

[0018] In the description of this invention, the system architecture relationships or data processing flows indicated by terms such as "layer," "module," "interface," "data flow," "client," and "server" are all defined based on the architecture diagram or flowchart corresponding to the embodiments. This way of describing is only used to clearly illustrate the logical relationships between the elements in the technical solution, and not to limit the physical deployment form. The term "multiple" includes two or more technical units, including but not limited to multiple data nodes, processing threads, service instances, or functional components and other scalable elements. The specific number is determined according to the actual business scenario and needs to be specifically specified.

[0019] Example 1 In this embodiment, all key process parameters involving numerical ranges are strictly set according to their minimum values ​​within the range. Specific parameters are as follows: the mass fraction of the γ-aminopropyltriethoxysilane ethanol solution is 20%; the sheet diameter of the aminated graphene is 5 micrometers, and the mass percentage content of nitrogen on its surface is 8%; the average particle size of nano-titanium dioxide is 20 nanometers; the mass ratio of aminated graphene to nano-titanium dioxide is set to 1:3; the true density of the hollow glass microspheres is 0.25 g / cm³; the solid content of the waterborne polyurethane emulsion is 40%; the viscosity of the formaldehyde-removing heat-insulating slurry is controlled at 1000 mPa·s, and the pH value is adjusted to 7.5; the unwinding tension is set to 5 Newtons; the temperature of the first preheating and drying zone is 60 degrees Celsius; the temperature of the second film-forming and drying zone is 80 degrees Celsius; the temperature of the third crosslinking reaction zone is 100 degrees Celsius, and the duration of the crosslinking reaction is 3 minutes.

[0020] Please see Figure 1 This invention provides a technical solution: a method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall coverings, comprising the following steps: S1: Preparation of aminated modified graphene. The specific process is as follows: S11: Add graphene oxide powder with a sheet thickness of less than 1 nanometer to deionized water, and use an ultrasonic crusher to perform exfoliation and dispersion treatment at a frequency of 40 kHz until a uniform and precipitate-free graphene oxide dispersion is formed; S12: Add γ-aminopropyltriethoxysilane diluted with anhydrous ethanol dropwise to the graphene oxide dispersion, and simultaneously start a magnetic stirrer to continuously mix at a speed of 500 rpm. Raise the temperature of the reaction system to 80 degrees Celsius and maintain a constant temperature reaction (reaction time 6 hours) to promote the condensation reaction between the silane hydrolysis products and the hydroxyl groups on the surface of graphene oxide to generate a reaction mixture. The purity of γ-aminopropyltriethoxysilane is greater than 98%, and it is pre-dissolved in anhydrous ethanol to prepare a silanol solution with a mass fraction of 20% to 30% before being added to the reaction vessel. S13: Pump the reaction mixture into a high-speed centrifuge, set the speed to 10,000 revolutions per minute for solid-liquid separation, discard the supernatant and wash the precipitate three times with anhydrous ethanol to obtain a pure precipitate. S14: The pure precipitate was placed in a vacuum freeze dryer and sublimated at -50 degrees Celsius and a vacuum of 10 Pascals to obtain fluffy powdered aminated modified graphene.

[0021] This step aims to construct a graphene substrate with specific functional groups. First, 500 grams of graphene oxide powder with a sheet thickness measured by atomic force microscopy (0.8 nm to 0.9 nm) was weighed and placed into an ultrasonic dispersion container containing 50 liters of deionized water. An ultrasonic breaker equipped with a titanium alloy probe was activated, with the frequency locked at 40 kHz and the power set to 1200 watts for continuous exfoliation and dispersion. During dispersion, 5 ml of the dispersion was sampled every 15 minutes, and the particle size distribution was monitored using a laser particle size analyzer until the monitoring data showed a stable D90 value within the preset range, and the dispersion appeared as a dark brown, semi-transparent substance with no visible precipitation after standing for 30 minutes. This confirmed it as a uniform graphene oxide dispersion. Meanwhile, in a separate mixing tank, 100 g of γ-aminopropyltriethoxysilane with a purity of 98.5% was weighed and slowly added to 400 g of anhydrous ethanol (corresponding to a mass fraction of 20%). The mixture was stirred with a glass rod until a colorless, transparent, homogeneous silanol solution was formed. The prepared graphene oxide dispersion was transferred to an enamel-lined reactor with a jacketed temperature control system. A magnetic stirrer was turned on and set to a speed of 500 rpm to create a stable vortex in the reactor. The silanol solution was added dropwise to the reactor at a rate of 10 mL per minute using a constant-pressure dropping funnel. After the addition was complete, circulating heat transfer oil was introduced into the reactor jacket to linearly raise the internal temperature of the reaction system to 80 degrees Celsius. This temperature was maintained constant using a PID temperature control system, with an error controlled within ±0.5 degrees Celsius. The reaction was maintained at this constant temperature for 6 hours. During this period, the intensity change of the hydroxyl peak in the reaction solution was detected every hour using an online infrared spectrometer until the reaction was completed, yielding the reaction mixture. Subsequently, a diaphragm pump was used to deliver the reaction mixture to the inlet of a high-speed tubular centrifuge. The centrifuge speed was set to 10,000 rpm, and the feed flow rate was controlled at 5 liters per hour. The supernatant after centrifugation was discharged into a waste liquid treatment tank, and the black paste-like precipitate adhering to the inner wall of the drum was collected. The precipitate was redispersed in 5 liters of anhydrous ethanol and centrifuged again. This washing operation was repeated three times to thoroughly remove unreacted silane monomers and physically adsorbed impurities, obtaining a pure precipitate. Finally, the pure precipitate was spread evenly on a stainless steel tray, with a thickness controlled to within 1 cm, and sent to a vacuum freeze dryer. The refrigeration system was started to lower the shelf temperature to -50 degrees Celsius for pre-freezing for 4 hours. Then, the vacuum pump was started to evacuate the drying chamber pressure to 10 Pascals. This vacuum level was maintained while the shelf temperature was slowly increased for sublimation drying for 24 hours, finally obtaining a fluffy powdery aminated modified graphene. Elemental analysis showed that its surface nitrogen content was 8.05%.

[0022] The aforementioned D90 refers to a particle size statistical parameter, representing the particle size value corresponding to 90% of the total particle volume or number accumulated from the smallest particle size in the particle size distribution curve. It is used to characterize the upper limit of the particle size of large particles in a particle group.

[0023] S2: Construction of formaldehyde-removing heat-insulating slurry. The specific process is as follows: S21: Aminated modified graphene and nano-titanium dioxide are put into a high-speed mixer and dry premixed at a speed of 500 rpm for 10 minutes to obtain mixed powder; In this step, the aminated modified graphene sheets have a diameter of 5 to 15 micrometers and a nitrogen content of 8% to 12% by mass on their surface; Nano titanium dioxide has an anatase crystal structure with an average particle size distribution between 20 and 50 nanometers, and its surface is coated with alumina or silicon dioxide. The mass ratio of aminated modified graphene to nano-titanium dioxide in the coating is 1:3 to 1:5; S22: The mixed powder and hollow glass microspheres are added to the water-based polyurethane emulsion in batches, while the mixture is stirred at low speed using a dispersion disc to form a premixed liquid. Among them, the true density of hollow glass microspheres is 0.25 to 0.60 grams per cubic centimeter, and their compressive strength is greater than 15 MPa; The waterborne polyurethane emulsion is an anionic aliphatic polyurethane dispersion with a solid content of 40% to 50%. S23: Transfer the premixed liquid to the dispersion vessel, turn on the high shear disperser and disperse at 2000 rpm for 30 minutes. Control the temperature during the dispersion process to not exceed 40 degrees Celsius, and control the viscosity of the formaldehyde-removing heat insulation slurry to be between 1000 and 3000 mPa·s. Adjust the pH value to 7.5 to 8.5 to obtain the formaldehyde-removing heat insulation slurry.

[0024] In this step, 200 grams of aminated modified graphene powder with a sheet diameter of 5 micrometers prepared in step S1 and 600 grams of anatase nano-titanium dioxide powder (particle size 20 nanometers) with a silica coating are accurately weighed, with the mass ratio strictly controlled at 1:3. The two powders are then fed into the mixing chamber of a high-speed mixer via a vacuum feeder. The main motor is started, and the stirring paddle speed is set to 500 rpm. The mixing process lasts for 10 minutes, using the shear force generated by the high-speed rotation to break up the agglomerates, allowing the graphene sheets and titanium dioxide particles to be uniformly interwoven at the microscale, resulting in a mixed powder. Subsequently, 10 kg of anionic aliphatic aqueous polyurethane dispersion with a solid content of 40% is prepared and placed in a stainless steel dispersion tank equipped with a dispersion disc. The disperser is turned on, and the speed is set to a low speed of 300 rpm. The mixed powder is added to the dispersion in five batches, with a 2-minute interval between each addition, ensuring the powder is completely wetted before adding the next batch. Next, 500 grams of hollow glass microspheres with a true density of 0.25 g / cm³ and a compressive strength of 16 MPa were weighed and slowly added to the dispersion tank through the side inlet. The mixture was then stirred at low speed for 15 minutes to form a well-flowing premix. The premix was piped to a high-shear dispersion vessel, and the cooling water circulation system was activated, with the cooling water temperature set to 15 degrees Celsius to counteract the heat generated during dispersion. The high-shear disperser was started, and the speed was increased to 2000 rpm for a high-speed dispersion process lasting 30 minutes. During dispersion, a temperature sensor installed at the bottom of the vessel monitored the slurry temperature in real time. The data showed that the temperature fluctuation throughout the process was between 32 and 36 degrees Celsius, not exceeding the 40-degree Celsius temperature control threshold. After dispersion, the slurry viscosity was measured using an online viscometer (based on rotational rheology), with an initial reading of 920 mPa·s. At this point, add an appropriate amount of polyurethane thickener (such as polyether polyurethane), each addition being 0.1% of the total mass. Stir well and retest until the viscosity reaches 1000 mPa·s. Then, insert the pH meter electrode, which shows an initial pH value of 6.8. Adjust the pH by adding a 5% ammonia solution dropwise while stirring, until the pH meter reading stabilizes at 7.5, thus obtaining the formaldehyde-removing and heat-insulating slurry.

[0025] Table 1. Record of Key Parameters in the Slurry Preparation Process of Example 1 ; The aforementioned anionic aliphatic waterborne polyurethane dispersion refers to a system in which a polyurethane prepolymer is emulsified and dispersed in water. The polyurethane molecular chain segments use aliphatic isocyanate as the hard segment raw material and introduce hydrophilic groups such as carboxyl or sulfonic acid groups to make them negatively charged, thereby forming a stable colloidal dispersion in water.

[0026] S3: Pre-formed wet film generation. The specific process is as follows: S31: Load the non-woven base paper substrate or textile fiber substrate onto the unwinding roller, adjust the unwinding tension to 5-10 Newtons through the tension controller, and pull the non-woven base paper substrate or textile fiber substrate to the coating station; S32: The formaldehyde-removing and heat-insulating slurry is transported to the surface of the micro-gravure roller using a circulating pump, and the excess slurry is scraped off by a scraper to form a uniform material layer on the surface of the micro-gravure roller. S33: Drive the nonwoven base paper substrate or textile fiber substrate to make reverse contact with the micro-gravure roller, control the gap to be 0.15mm, and the speed to be 20m / min, so that the uniform material layer is transferred to the surface of the nonwoven base paper substrate or textile fiber substrate to generate a pre-made wet film.

[0027] This step utilizes a precision coating unit for continuous operation. First, an 800mm diameter nonwoven base paper substrate is mounted on the unwinding air shaft, and the unwinding motor is started. A closed-loop tension control system, using a tension sensor to provide real-time feedback on the paper tape tension, adjusts the torque of the magnetic powder brake to precisely maintain the tension of the nonwoven base paper substrate at 5 Newtons. The traction roller guides the substrate smoothly into the coating head position, preventing wrinkles or breakage. The diaphragm pump of the slurry delivery system is activated, transporting the formaldehyde-removing and heat-insulating slurry obtained in step S2 from the storage tank to the trough of the coating head. A level sensor in the trough maintains a constant liquid level by controlling the pump's start and stop. The microgravure roller is partially immersed in the slurry; as the roller rotates, sufficient slurry is carried in the cells. A flexible steel doctor blade positioned above the microgravure roller contacts the roller surface at a 30-degree contact angle, scraping away excess slurry outside the cells to ensure uniform material coverage on the microgravure roller surface. The main drive motor is started, driving the microgravure roller to rotate in the opposite direction to the substrate's travel direction (reverse coating mode). The gap between the microgravure roller and the back roller is locked at 0.15 mm via a precision lead screw adjustment mechanism. The production line speed is set to 20 meters per minute. Supported by the back roller, the nonwoven base paper contacts the microgravure roller, and through reverse shearing action, the pulp within the cells is coated onto the substrate surface with a near 100% transfer rate. An online laser thickness gauge scans the wet film thickness in real time; the data shows a uniform wet film thickness distribution between 120 and 130 micrometers, generating a continuous pre-formed wet film.

[0028] The aforementioned closed-loop tension control system refers to an automated control architecture. This system uses a tension sensor to detect the actual tension value of the material during operation in real time, and feeds the signal back to the controller for comparison with the set value. After calculating the deviation through a PID algorithm, it outputs a command to adjust the output torque or speed of the actuator (such as a brake or motor) to maintain constant tension.

[0029] S4: Cutting of graphene formaldehyde-removing and heat-insulating wallpaper and wall coverings. The specific process is as follows: S41: The pre-made wet film is transported to the first temperature zone of the hot air drying oven and preheated and dried at 60-80 degrees Celsius to remove free water from the coating and form a semi-dry coating; S42: The semi-dry coating is transported to the second temperature zone and dried at 80-100 degrees Celsius to allow the polyurethane particles to fuse and form a continuous film. S43: The continuous film layer is transported to the third temperature zone and cross-linked at 100-120 degrees Celsius for 3-5 minutes to obtain a cured coating; S44: The base layer with the cured coating is cooled to room temperature by a cooling roller and then wound up using a winding machine to cut graphene formaldehyde-removing and heat-insulating wallpaper and wall covering.

[0030] The substrate carrying the pre-formed wet film is smoothly introduced into the hot air drying chamber via a conveyor belt. The drying chamber is designed to meet the process requirements of different temperature zones, divided into three independent temperature-controlled zones. First, the substrate enters the first temperature zone (10 meters long), where the hot air nozzle temperature is set to 60 degrees Celsius and the air velocity is controlled at 15 meters per second. Under the action of low temperature and high air velocity, free water molecules on the coating surface evaporate rapidly, while preventing surface skinning due to excessive temperature, which would hinder the escape of internal moisture. After 30 seconds, the coating transitions to a semi-dry state where it no longer flows. Then, the substrate enters the second temperature zone (10 meters long), where the temperature is stepped up to 80 degrees Celsius. At this temperature, the polyurethane latex particles begin to demulsify, deform, and accumulate, further expelling water molecules from the polymer gaps, gradually densifying the coating and forming a continuous physical film. Finally, the substrate enters the third temperature zone, set at 100 degrees Celsius. To meet the requirement of a 3-minute crosslinking reaction duration in this embodiment, with a production line speed of 20 meters per minute, the effective drying path length of the third temperature zone is designed to be 60 meters. To this end, the third temperature zone employs a vertical multi-layer folding paper feeding structure. The substrate in this zone is guided by guide rollers to repeatedly move up and down, ensuring a total dwell time of 180 seconds. Under this high-temperature environment, the closed isocyanate groups are unsealed and undergo a cross-linking reaction with the amino groups on the surface of the amino graphene and the active hydrogen on the polyurethane molecular chains, forming a three-dimensional network structure and obtaining a fully cured coating. After leaving the drying oven, the wallpaper substrate with the cured coating is immediately adhered to the surface of a 600 mm diameter cooling roller. Chilled water at 5 degrees Celsius is circulated inside the cooling roller, causing the substrate temperature to drop to 25 degrees Celsius (room temperature) within 5 seconds. After the edge alignment is corrected by the web guiding system, it is wound up using a center surface winding machine. When the roll diameter reaches 500 mm, an automatic cutter laterally cuts the substrate, and the roll is unwound to obtain the finished graphene formaldehyde-removing and heat-insulating wallpaper.

[0031] Table 2 Comparison of Product Performance in Example 1 ; Example 2 In this embodiment, all key process parameters involving numerical ranges are strictly set according to their maximum values ​​within the range. Specific parameters are as follows: the mass fraction of the γ-aminopropyltriethoxysilane ethanol solution is 30%; the sheet diameter of the aminated graphene is 15 micrometers, and the mass percentage content of nitrogen on its surface is 12%; the average particle size of nano-titanium dioxide is 50 nanometers; the mass ratio of aminated graphene to nano-titanium dioxide is set to 1:5; the true density of the hollow glass microspheres is 0.60 g / cm³; the solid content of the waterborne polyurethane emulsion is 50%; the viscosity of the formaldehyde-removing heat-insulating slurry is controlled at 3000 mPa·s, and the pH value is adjusted to 8.5; the unwinding tension is set to 10 Newtons; the temperature of the first preheating and drying zone is 80 degrees Celsius; the temperature of the second film-forming and drying zone is 100 degrees Celsius; the temperature of the third crosslinking reaction zone is 120 degrees Celsius, and the duration of the crosslinking reaction is 5 minutes.

[0032] Please see Figure 1 This invention provides a technical solution: a method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall coverings, comprising the following steps: S1: Preparation of aminated modified graphene. The specific process is as follows: S11: Add graphene oxide powder with a sheet thickness of less than 1 nanometer to deionized water, and use an ultrasonic crusher to perform exfoliation and dispersion treatment at a frequency of 40 kHz until a uniform and precipitate-free graphene oxide dispersion is formed; S12: Add γ-aminopropyltriethoxysilane diluted with anhydrous ethanol dropwise to the graphene oxide dispersion, and simultaneously start a magnetic stirrer to continuously mix at a speed of 500 rpm. Raise the temperature of the reaction system to 80 degrees Celsius and maintain a constant temperature reaction (reaction time 6 hours) to promote the condensation reaction between the silane hydrolysis products and the hydroxyl groups on the surface of graphene oxide to generate a reaction mixture. The purity of γ-aminopropyltriethoxysilane is greater than 98%, and it is pre-dissolved in anhydrous ethanol to prepare a silanol solution with a mass fraction of 20% to 30% before being added to the reaction vessel. S13: Pump the reaction mixture into a high-speed centrifuge, set the speed to 10,000 revolutions per minute for solid-liquid separation, discard the supernatant and wash the precipitate three times with anhydrous ethanol to obtain a pure precipitate. S14: The pure precipitate was placed in a vacuum freeze dryer and sublimated at -50 degrees Celsius and a vacuum of 10 Pascals to obtain fluffy powdered aminated modified graphene.

[0033] This step focuses on preparing large-size modified graphene with high nitrogen content. First, 1000 grams of graphene oxide powder with a sheet thickness of less than 1 nanometer is weighed and poured into a 100-liter dispersion tank. An appropriate amount of deionized water is added to prepare a high-concentration suspension. An industrial-grade ultrasonic breaker is activated, and high-intensity exfoliation is performed at a frequency of 40 kHz. Due to the large processing volume, the ultrasonic time is extended to 1.5 times the conventional process, until sampling and testing show that the graphene oxide sheets in the dispersion are completely opened and no macroscopic particles are present. In the reagent preparation area, 300 grams of 99% pure γ-aminopropyltriethoxysilane is weighed and dissolved in 700 grams of anhydrous ethanol to prepare a 30% (w / w) high-concentration silanol solution. The graphene oxide dispersion is pumped into a 200-liter stainless steel reactor, and the anchor-type stirrer is turned on, setting the speed to 500 rpm to ensure the mixing effect of the high-viscosity system. The feed pump was turned on, and a high-concentration silanol solution was injected into the reactor at a uniform rate. Simultaneously, the steam heating valve was opened to rapidly raise the temperature inside the reactor to 80 degrees Celsius. The reaction was maintained at this temperature for 6 hours, using the high concentration of silane monomers to drive the grafting reaction in the forward direction, causing more silane molecules to condense on the graphene surface. After the reaction, the viscous reaction mixture was pumped to a high-speed disc centrifuge at 10,000 rpm for solid-liquid separation. The separated solid product was collected in a washing tank and subjected to three deep washes with ethanol, each with a stirring time of at least 30 minutes, to remove free silane oligomers. Finally, the wet material was transferred to a large freeze dryer and subjected to sublimation drying at a cold trap temperature of -50 degrees Celsius and an ultimate vacuum of 10 Pascals for 36 hours, yielding amino-modified graphene powder with extremely high bulk and a sheet size maintained at approximately 15 micrometers. The nitrogen content was measured to be 12.1%.

[0034] The aforementioned sublimation drying refers to a drying technology that freezes water-containing materials below their freezing point and heats them in a vacuum environment, causing the solid ice in the materials to directly transform into gaseous water vapor without passing through a liquid state, thereby removing moisture while maintaining the original skeletal structure and activity of the materials.

[0035] S2: Construction of formaldehyde-removing heat-insulating slurry. The specific process is as follows: S21: Aminated modified graphene and nano-titanium dioxide are put into a high-speed mixer and dry premixed at a speed of 500 rpm for 10 minutes to obtain mixed powder; In this step, the aminated modified graphene sheets have a diameter of 5 to 15 micrometers and a nitrogen content of 8% to 12% by mass on their surface; Nano titanium dioxide has an anatase crystal structure with an average particle size distribution between 20 and 50 nanometers, and its surface is coated with alumina or silicon dioxide. The mass ratio of aminated modified graphene to nano-titanium dioxide in the coating is 1:3 to 1:5; S22: The mixed powder and hollow glass microspheres are added to the water-based polyurethane emulsion in batches, while the mixture is stirred at low speed using a dispersion disc to form a premixed liquid. Among them, the true density of hollow glass microspheres is 0.25 to 0.60 grams per cubic centimeter, and their compressive strength is greater than 15 MPa; The waterborne polyurethane emulsion is an anionic aliphatic polyurethane dispersion with a solid content of 40% to 50%. S23: Transfer the premixed liquid to the dispersion vessel, turn on the high shear disperser and disperse at 2000 rpm for 30 minutes. Control the temperature during the dispersion process to not exceed 40 degrees Celsius, and control the viscosity of the formaldehyde-removing heat insulation slurry to be between 1000 and 3000 mPa·s. Adjust the pH value to 7.5 to 8.5 to obtain the formaldehyde-removing heat insulation slurry.

[0036] This step aims to construct a thick slurry with high solids content. Weigh 200g of the prepared aminated modified graphene powder and 1000g of alumina-coated anatase nano-titanium dioxide powder (50nm particle size), with a mass ratio of 1:5 to enhance the coating's hiding power and whiteness. Feed the powder into a high-speed mixer and dry mix at 500 rpm for 10 minutes, utilizing interparticle collision and friction to uniformly coat the titanium dioxide particles with graphene sheets. Measure 20kg of anionic aliphatic aqueous polyurethane dispersion with a solids content of up to 50% and add it to the dispersion tank. Due to the high viscosity of this emulsion, the motor load needs to be closely monitored after starting the dispersion tank. Add the mixed powder in batches, followed by 1000g of high-strength hollow glass microspheres with a true density of 0.60 g / cm³ and a compressive strength greater than 25 MPa. The high density of the microspheres helps disperse them in the high-viscosity system and prevents floating. A low-speed agitator was activated to assist dispersion, forming a high-solids-content premix. The premix was then transferred to a high-shear disperser and subjected to vigorous dispersion at 2000 rpm for 30 minutes. Given the significant frictional heat generation in the high-solids-content system, the cooling system was operated at full power, strictly controlling the material temperature to not exceed 40 degrees Celsius (the actual peak temperature was 38.5 degrees Celsius). After dispersion, the viscosity of the slurry was measured to be 2800 mPa·s. A thickener was then added for fine-tuning until the viscosity precisely reached 3000 mPa·s to suit thick coating processes. Finally, a 10% sodium hydroxide solution was added dropwise to slowly adjust the pH to 8.5, ensuring the slurry's storage stability under alkaline conditions, ultimately yielding a high-viscosity formaldehyde-removing and heat-insulating slurry.

[0037] Table 3 Key Parameter Recording Table for Slurry Preparation Process in Example 2 ; The aforementioned high-shear disperser refers to a mechanical device that utilizes the strong shear force, centrifugal extrusion force, and liquid friction force generated between a high-speed rotating rotor and a stator to pulverize, emulsify, homogenize, and mix materials, effectively breaking down the agglomerated structure of nanoparticles.

[0038] S3: Pre-formed wet film generation. The specific process is as follows: S31: Load the non-woven base paper substrate or textile fiber substrate onto the unwinding roller, adjust the unwinding tension to 5-10 Newtons through the tension controller, and pull the non-woven base paper substrate or textile fiber substrate to the coating station; S32: The formaldehyde-removing and heat-insulating slurry is transported to the surface of the micro-gravure roller using a circulating pump, and the excess slurry is scraped off by a scraper to form a uniform material layer on the surface of the micro-gravure roller. S33: Drive the nonwoven base paper substrate or textile fiber substrate to make reverse contact with the micro-gravure roller, control the gap to be 0.15mm, and the speed to be 20m / min, so that the uniform material layer is transferred to the surface of the nonwoven base paper substrate or textile fiber substrate to generate a pre-made wet film.

[0039] This step primarily focuses on the coating process of the textile fiber base layer (wallcovering). Heavy-duty textile fiber base layer rolls are hoisted onto the unwinding rack. Due to the thickness and weight of the wallcovering substrate, the tension controller is set to an unwinding tension of 10 Newtons to ensure a smooth and unslack fabric surface. After being guided by the alignment rollers, the substrate enters the coating station. The coating system's feed pump pumps a high-viscosity (3000 mPa·s) formaldehyde-removing and heat-insulating slurry into the microgravure roller trough. For the high-viscosity slurry, a microgravure roller with a deeper cell depth is selected to increase the material carrying capacity. The doctor blade pressure is correspondingly increased to ensure the high-viscosity slurry is smoothed. The drive motor rotates the microgravure roller in the opposite direction, maintaining a gap of 0.15 mm between it and the substrate. The production line speed is set to 20 meters per minute. Under the combined effect of high tension and high viscosity, the slurry is forcefully transferred to the rough surface of the textile fibers and partially penetrates into the fiber gaps, forming a pre-formed wet film with stronger adhesion. The online testing system showed that due to the high solid content and high viscosity of the slurry, the thickness of the wet film reached about 150 micrometers, and the surface smoothness was good with no missed coating.

[0040] The aforementioned micro-gravure roller refers to a coating roller with tiny cells of specific patterns and depths engraved on its surface. It is usually small in diameter and transfers the liquid in the cells to the substrate by reverse contact. It is suitable for thin-layer, uniform and precise coating operations.

[0041] S4: Cutting of graphene formaldehyde-removing and heat-insulating wallpaper and wall coverings. The specific process is as follows: S41: The pre-made wet film is transported to the first temperature zone of the hot air drying oven and preheated and dried at 60-80 degrees Celsius to remove free water from the coating and form a semi-dry coating; S42: The semi-dry coating is transported to the second temperature zone and dried at 80-100 degrees Celsius to allow the polyurethane particles to fuse and form a continuous film. S43: The continuous film layer is transported to the third temperature zone and cross-linked at 100-120 degrees Celsius for 3-5 minutes to obtain a cured coating; S44: The base layer with the cured coating is cooled to room temperature by a cooling roller and then wound up using a winding machine to cut graphene formaldehyde-removing and heat-insulating wallpaper and wall covering.

[0042] The pre-formed wet film enters the drying and curing system along with the substrate. The first temperature zone is set at 80 degrees Celsius, which is the upper limit of preheating and drying. Due to the relatively low water content (high solids content) in the slurry, the higher initial temperature accelerates surface drying and prevents slurry sagging. The substrate runs in this temperature zone for 30 seconds, and the surface quickly sets. It then enters the second temperature zone, where the temperature is raised to 100 degrees Celsius. At this high temperature, the polyurethane particles undergo deep fusion, high-boiling-point additives begin to volatilize, and the internal structure of the coating becomes denser. Subsequently, it enters the third temperature zone, set at 120 degrees Celsius, which is the intensification stage of the crosslinking reaction. To meet the 5-minute crosslinking time set in this embodiment, based on a linear velocity of 20 meters per minute, the physical path length of the third temperature zone needs to reach 100 meters. Therefore, this temperature zone uses a large, multi-layered, loop-shaped paper feeding structure in an ultra-long oven, where the substrate travels a long distance through multiple sets of guide rollers. Under the long baking time of 120 degrees Celsius for 5 minutes, the crosslinking agent in the coating reacts completely, the crosslinking density reaches its maximum value, and the coating acquires extremely high mechanical strength and water resistance. After curing, the wallpaper substrate is at a high temperature. It is then cooled in stages by two series of cooling rollers: the first stage lowers the temperature to 60 degrees Celsius, and the second stage lowers it to room temperature. Finally, it is wound at high tension by a winding machine and cut to obtain the finished graphene formaldehyde-removing and heat-insulating wallpaper.

[0043] Table 4 Comparison of Product Performance in Example 2 ; The aforementioned crosslinking reaction refers to the chemical process by which linear or branched polymer chains form chemical bonds (such as covalent bonds) through chemical bonding, connecting the molecular chains into a three-dimensional network or three-dimensional structure. This process can significantly improve the heat resistance, solvent resistance, and mechanical strength of materials.

[0044] The above embodiments illustrate preferred embodiments of the present invention. Any equivalent adjustments to the technical solution based on software engineering methods are within the scope of protection, including but not limited to: implementing algorithm logic using different programming languages, refactoring functional modules into services, adjusting data interaction protocols, and optimizing resource scheduling strategies. Any implementation scheme derived from reasonable modifications to the data processing flow, service call chain, or system architecture layer without departing from the core technology of the present invention should be considered within the protection scope defined by the technical solution of the present invention.

Claims

1. A graphene-based formaldehyde-removing and heat-insulating wallpaper, characterized in that, The materials used in preparing the graphene-based formaldehyde-removing and heat-insulating wallpaper include: The nonwoven base paper substrate and the coating applied to the nonwoven base paper substrate, wherein the coating is composed of aminated modified graphene, nano-titanium dioxide, hollow glass microspheres and waterborne polyurethane emulsion.

2. The graphene formaldehyde-removing and heat-insulating wallpaper according to claim 1, characterized in that, The aminated modified graphene has a sheet diameter of 5 to 15 micrometers and a nitrogen content of 8% to 12% by mass on its surface; The nano-titanium dioxide has an anatase crystal structure with an average particle size distribution between 20 and 50 nanometers, and its surface is coated with alumina or silicon dioxide. The true density of the hollow glass microspheres is 0.25 to 0.60 g / cm³, and their compressive strength is greater than 15 MPa. The aqueous polyurethane emulsion is an anionic aliphatic polyurethane dispersion with a solid content of 40% to 50%. The mass ratio of the aminated modified graphene to the nano-titanium dioxide in the coating is 1:3 to 1:

5.

3. A graphene-based formaldehyde-removing and heat-insulating wall covering, characterized in that, The wall covering uses the graphene formaldehyde-removing and heat-insulating wallpaper as described in claims 1-2, and the materials used to prepare the graphene formaldehyde-removing and heat-insulating wall covering include: The textile fiber base layer and the coating impregnated inside the textile fiber base layer or coated on the surface of the textile fiber base layer, the coating being composed of aminated modified graphene, nano-titanium dioxide, hollow glass microspheres and waterborne polyurethane emulsion.

4. A method for preparing graphene-based formaldehyde-removing and heat-insulating wallpaper or wall covering, characterized in that, The method is used to prepare the graphene formaldehyde-removing and heat-insulating wallpaper and wall covering according to any one of claims 1-3, and includes the following steps: S1: The graphene oxide dispersion and γ-aminopropyltriethoxysilane were added to the reactor at a ratio of 1:2 and stirred in an oil bath at 80°C for 6 hours. The amino groups were then coupled with silane, and the mixture was centrifuged and dried to prepare amino-modified graphene. S2: The aminated modified graphene, the nano titanium dioxide and the hollow glass microspheres are added to the aqueous polyurethane emulsion and dispersed at high speed of 2000 rpm for 30 minutes to construct a formaldehyde-removing and heat-insulating slurry. S3: The formaldehyde-removing and heat-insulating slurry is coated onto the non-woven base paper substrate or the textile fiber substrate using a micro-gravure coating machine, with a gap of 0.15mm and a speed of 20m / min, to generate a pre-made wet film. S4: The pre-made wet film is introduced into a hot air drying oven and cross-linked and cured by a gradient temperature increase of 60-120℃. After cooling and winding, the graphene formaldehyde-removing and heat-insulating wallpaper and wall covering are cut out.

5. The method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall covering according to claim 4, characterized in that, The preparation process of the aminated modified graphene includes: S11: Add graphene oxide powder with a sheet thickness of less than 1 nanometer to deionized water, and use an ultrasonic crusher to perform peeling and dispersion treatment at a frequency of 40 kHz until a uniform graphene oxide dispersion without precipitation is formed. S12: Add the γ-aminopropyltriethoxysilane diluted with anhydrous ethanol dropwise to the graphene oxide dispersion, and simultaneously start the magnetic stirrer to continuously mix at a speed of 500 rpm. Raise the temperature of the reaction system to 80 degrees Celsius and maintain a constant temperature reaction to promote the condensation reaction between the silane hydrolysis products and the hydroxyl groups on the surface of graphene oxide to generate a reaction mixture. S13: Pump the reaction mixture into a high-speed centrifuge, set the speed to 10,000 revolutions per minute for solid-liquid separation, discard the supernatant and wash the precipitate three times with anhydrous ethanol to obtain a pure precipitate. S14: The purified precipitate is placed in a vacuum freeze dryer and sublimated at -50 degrees Celsius and a vacuum of 10 Pascals to obtain the aminated modified graphene in the form of a fluffy powder.

6. The method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall covering according to claim 4, characterized in that, The construction process of the formaldehyde-removing heat insulation slurry includes: S21: The aminated modified graphene and the nano titanium dioxide are put into a high-speed mixer and dry premixed at a speed of 500 rpm for 10 minutes to obtain a mixed powder. S22: The mixed powder and the hollow glass microspheres are added to the aqueous polyurethane emulsion in batches, while the dispersion disc is used to stir at low speed to form a premixed liquid. S23: Transfer the premixed liquid to a dispersion vessel, turn on the high-shear disperser to perform high-speed dispersion at 2000 rpm, and control the temperature during the dispersion process to not exceed 40 degrees Celsius to obtain the formaldehyde-removing heat insulation slurry.

7. The method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall covering according to claim 4, characterized in that, The process of generating the pre-fabricated wet film includes: S31: Load the nonwoven base paper substrate or the textile fiber substrate onto the unwinding roller, adjust the unwinding tension to 5-10 Newtons through the tension controller, and pull the nonwoven base paper substrate or the textile fiber substrate to the coating station; S32: The formaldehyde-removing and heat-insulating slurry is transported to the surface of the micro-gravure roller using a circulating pump, and excess slurry is scraped off by a scraper to form a uniform material layer on the surface of the micro-gravure roller. S33: Drive the nonwoven base paper substrate or the textile fiber substrate to make reverse contact with the microgravure roller, control the gap to be 0.15mm, so that the uniform material layer is transferred to the surface of the nonwoven base paper substrate or the textile fiber substrate to generate the pre-made wet film.

8. The method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall covering according to claim 4, characterized in that, The process of cutting the graphene-based formaldehyde-removing and heat-insulating wallpaper and wall covering includes: S41: The pre-made wet film is conveyed to the first temperature zone of the hot air drying oven and preheated and dried at 60-80 degrees Celsius to remove free water from the coating and form a semi-dry coating. S42: The semi-dry coating is transported to the second temperature zone and dried at 80-100 degrees Celsius to fuse the polyurethane particles and form a continuous film layer. S43: The continuous film layer is transported to the third temperature zone and crosslinked at 100-120 degrees Celsius for 3-5 minutes to obtain a cured coating. S44: The base layer with the cured coating is cooled to room temperature by a cooling roller and wound up using a winding machine to cut the graphene formaldehyde-removing and heat-insulating wallpaper and wall covering.

9. The method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall covering according to claim 4, characterized in that, The γ-aminopropyltriethoxysilane has a purity greater than 98%, and is pre-dissolved in anhydrous ethanol to prepare a silanol solution with a mass fraction of 20% to 30% before being added to the reaction vessel.

10. The method for preparing graphene formaldehyde-removing and heat-insulating wallpaper and wall covering according to claim 4, characterized in that, In S2, the viscosity of the formaldehyde-removing heat-insulating slurry is controlled between 1000 and 3000 mPa·s, and the pH value is adjusted to 7.5 to 8.5.

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