A magnesium oxysulfate plate with formaldehyde purification function and a preparation method thereof

Abstract

The present application relates to the field of aluminum alloy material processing and heat treatment technology, and particularly relates to a magnesium sulfate plate with formaldehyde purification function, which is composed of a gelling base material, a formaldehyde purification composite agent, aggregate, a modifier and water; the gelling base material comprises light-burned magnesium oxide and magnesium sulfate heptahydrate; the formaldehyde purification composite agent is a compound system, comprising nano titanium dioxide and activated carbon, the nano titanium dioxide is used for catalytic degradation of formaldehyde, and the activated carbon is used for physical adsorption of formaldehyde; the aggregate comprises quartz sand. The present application builds a composite purification system, realizes the synergistic effect of adsorption and degradation through the compounding of multiple functional components, completely changes the current situation of low efficiency and poor long-acting property of the traditional single purification method, can quickly and efficiently remove formaldehyde, and can still maintain stable purification performance after long-term use, and meets the core demand of indoor environmental protection decoration for formaldehyde treatment.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy material processing and heat treatment technology, specifically to a magnesium oxysulfate board with formaldehyde purification function and its preparation method. Background Technology

[0002] Magnesium oxysulfate board, as a commonly used building material, is widely used in the field of building decoration and renovation due to its basic load-bearing capacity and fire-resistant properties. With the increasing demand for indoor environmental protection, formaldehyde pollution control has become one of the core concerns in the decoration process. However, existing magnesium oxysulfate boards generally lack formaldehyde purification-related designs, only meeting basic usage requirements and failing to adapt to the actual demands of environmentally friendly indoor decoration.

[0003] Some existing technologies attempt to add a single purifying component to wood-based panels to achieve formaldehyde purification, but these solutions have significant limitations. A single purifying component can only perform a single function in adsorption or degradation, resulting in limited purification efficiency and insufficient long-term effectiveness; its purification capacity tends to decline after prolonged use. Furthermore, the functional component has poor compatibility with the magnesium oxysulfate cementitious substrate, leading to insufficient interfacial bonding and a significant decrease in the mechanical properties of the panel after adding the purifying component, making it difficult to balance purification effectiveness with structural stability.

[0004] Furthermore, traditional magnesium oxysulfate boards generally suffer from poor water resistance, exhibiting high water absorption rates. Prolonged exposure to humid environments can lead to strength loss and shorten service life. At the production level, existing technologies have stringent requirements for raw material formulation, demanding extremely high purity and dosage precision. Even slight deviations can cause significant fluctuations in product performance. Industrial production suffers from low tolerance for error, high costs, and insufficient adaptability, making stable mass production difficult. These intertwined problems result in significant shortcomings in the overall performance and practical application value of existing magnesium oxysulfate boards, necessitating a technological solution that can balance formaldehyde purification, mechanical properties, and water resistance while being suitable for industrial production. Summary of the Invention

[0005] The primary objective of this invention is to provide a magnesium oxysulfate board with formaldehyde purification function and its preparation method.

[0006] A further objective of this invention is to provide a magnesium oxysulfate board with formaldehyde purification function, comprising a cementitious substrate, a formaldehyde purification composite agent, aggregates, a modifier, and water; the cementitious substrate includes lightly calcined magnesium oxide and magnesium sulfate heptahydrate; the formaldehyde purification composite agent is a compound system comprising nano-titanium dioxide and activated carbon, wherein the nano-titanium dioxide is used for catalytic degradation of formaldehyde, and the activated carbon is used for physical adsorption of formaldehyde; the modifier includes citric acid and polyvinyl alcohol, wherein the citric acid is used to adjust the pH of the cementitious system, and the polyvinyl alcohol is used to improve the adhesion of the slurry; the aggregate comprises quartz sand.

[0007] Preferably, the formaldehyde purification compound further includes zeolite powder, which is used to enhance the physical adsorption capacity.

[0008] Preferably, the formaldehyde purification composite agent further includes amino-modified graphene, which is used to enhance the formaldehyde adsorption capacity and the long-term catalytic degradation effect.

[0009] Preferably, the aggregate further includes vitrified microspheres, which are used to optimize the pore structure of the plate.

[0010] Preferably, the modifier further includes a silane coupling agent, which is used to improve the interfacial bonding force between the purifying agent and the cementitious substrate.

[0011] Preferably, the gelling substrate further includes anhydrous magnesium sulfate, which is used to optimize the crystal structure of the gelling product.

[0012] Preferably, it also includes auxiliary functional components, which include rice husk ash and a waterproofing agent. The rice husk ash enhances performance by reacting with magnesium ions through its active silicon components, and the waterproofing agent is used to improve water resistance stability.

[0013] A method for preparing a magnesium oxysulfate board with formaldehyde purification function includes the following steps: (1) Pre-dispersion treatment: Mix the nano titanium dioxide in the formaldehyde purification composite agent with some water, add some polyvinyl alcohol, and stir at high speed to prepare a nano titanium dioxide dispersion; mix the adsorbent components in the formaldehyde purification composite agent with some water and stir to prepare an adsorbent suspension; (2) Preparation of gelling system: Mix the components of gelling substrate, add the remaining water after dry material stirring, and stir at medium speed to form a uniform magnesium oxysulfate gelling slurry. (3) Preparation of composite slurry: Nano titanium dioxide dispersion and adsorbent suspension are added to gelling slurry in sequence, then citric acid and the remaining modifier are added, and aggregate is added after high-speed stirring. The mixture is then stirred at low speed to form a shaped slurry. (4) Molding: The molding slurry is injected into the mold, and pressure is applied and maintained after the internal air bubbles are expelled by vibration to complete the initial molding; (5) Curing: First, cure at room temperature and then demold, then cure at constant temperature, and finally cure at room temperature until the finished product is finished.

[0014] Preferably, in step (1), a silane coupling agent is added during the pre-dispersion treatment, and the adsorbent component is a mixture of activated carbon and zeolite powder to form a composite adsorbent suspension; in step (3), the aggregate is a mixture of quartz sand and vitrified microspheres.

[0015] Preferably, in step (1), nano-titanium dioxide and amino-modified graphene are mixed and then pre-dispersed. The adsorption components are a mixture of activated carbon, zeolite powder and rice husk ash, which are used to make a composite adsorption-enhanced suspension. In step (2), the cementitious substrate also includes anhydrous magnesium sulfate. In step (3), a waterproofing agent is added when preparing the composite slurry. In step (5), the constant temperature curing adopts a gradient heating method.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs a composite purification system, which achieves the synergistic effect of adsorption and degradation through the combination of multiple functional components. This completely changes the current situation of low efficiency and poor long-term effectiveness of traditional single purification methods. It can quickly and efficiently remove formaldehyde and maintain stable purification performance even after long-term use, thus meeting the core needs of indoor environmental decoration for formaldehyde treatment.

[0017] 2. This invention effectively improves the mechanical properties and water resistance of the board by optimizing the cementitious substrate ratio and adding functional modified components, thus resolving the technical contradiction between the addition of functional components and the decline in substrate performance. The board not only possesses excellent compressive and flexural strength, meeting the structural requirements of building materials, but also significantly reduces water absorption and water resistance strength loss, extending product lifespan and adapting to more application scenarios.

[0018] 3. This invention designs customized processes such as pre-dispersion of the purifying agent, segmented stirring, and gradient temperature curing to ensure uniform dispersion of each component, improve the internal density of the board, and provide a reliable guarantee for performance optimization. Simultaneously, by expanding the compatibility range of core components and process parameters, it reduces the stringent requirements for raw material selection in industrial production, improves the error tolerance and stability of the production process, effectively controls production costs, and lays the foundation for large-scale mass production.

[0019] 4. This invention does not simply add functional components or adjust process parameters, but achieves a synergistic improvement in formaldehyde purification, mechanical properties, water resistance, and industrial compatibility through the complementary functions of multiple components and precise process adaptation. The product has outstanding comprehensive competitiveness and broad application prospects. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: Preparation steps: Pre-dispersion treatment: Mix nano-titanium dioxide from the formaldehyde purification composite agent with 2 parts water, add 0.2 parts polyvinyl alcohol, and stir at 2000 r / min for 15 minutes using a high-speed mixer to prepare a uniform nano-titanium dioxide dispersion; add activated carbon to 3 parts water and stir for 5 minutes to prepare an activated carbon suspension.

[0022] Preparation of the gelling system: Lightly calcined magnesium oxide and magnesium sulfate heptahydrate were added to a mixing tank and stirred at a low speed of 500 r / min for 3 minutes to achieve uniform mixing of dry materials; then the remaining water was slowly added and stirred at a medium speed of 1000 r / min for 8 minutes to form a uniform magnesium sulfate-oxygen gelling slurry.

[0023] Preparation of composite slurry: The above-mentioned nano-titanium dioxide dispersion and activated carbon suspension are added to the gelling slurry in sequence, and citric acid and the remaining polyvinyl alcohol are added at the same time. The mixture is stirred at a high speed of 1800 r / min for 12 minutes to ensure that the components are evenly dispersed. Finally, quartz sand is added and stirred at a low speed of 600 r / min for 5 minutes to prepare the shaped slurry.

[0024] Molding: The composite slurry is injected into a mold with dimensions of 400mm×400mm×10mm, and vibrated for 2 minutes using a vibrating table with a vibration frequency of 50Hz to remove internal air bubbles. Then, a pressure of 0.3MPa is applied on a press and held for 3 minutes to complete the initial molding.

[0025] Curing: First, cure at room temperature (25℃) and relative humidity (60%) for 24 hours, then demold; then transfer to a constant temperature curing chamber and cure at 50℃ and relative humidity (50%) for 48 hours, and finally cure at room temperature for 72 hours to obtain the basic formaldehyde-purifying magnesium oxide board.

[0026] This embodiment, as a basic optimization scheme, addresses the core shortcomings of the closest existing technology by, for the first time, combining nano-titanium dioxide and activated carbon to form a basic formaldehyde purification composite system. Nano-titanium dioxide achieves photocatalytic degradation of formaldehyde, while activated carbon achieves physical adsorption. The synergistic effect of the two achieves an integrated adsorption and degradation effect, overcoming the technical limitation of existing magnesium oxysulfate boards that only possess basic load-bearing and fire-resistant properties. Simultaneously, citric acid is used to adjust the pH value of the gelling system, and polyvinyl alcohol is used to improve the slurry's adhesion, ensuring that the board retains its basic mechanical properties after the addition of the purification components, laying a solid foundation for subsequent performance optimization.

[0027] The technical solution of this embodiment has clear application value: existing ordinary magnesium oxysulfate boards do not involve any formaldehyde purification design, and existing boards with only added purification agents only use a single component for purification, resulting in limited purification effects. This embodiment, through the design of a composite purification system, adds formaldehyde purification function without sacrificing basic performance, solving the technical problem of how to introduce purification function into magnesium oxysulfate boards without damaging the mechanical properties of the substrate. The combination of these technical means forms a synergistic effect of adsorption and degradation, possessing good application prospects; at the same time, this solution meets the urgent need for environmentally friendly indoor decoration and has significant application advantages compared to existing technologies.

[0028] Example 2: Preparation steps: Pre-dispersion treatment: Mix nano-titanium dioxide with 2.5 parts water, add 0.3 parts polyvinyl alcohol and 0.1 parts silane coupling agent KH-550, and stir at high speed of 2200 r / min for 20 minutes. The dispersion effect is optimized by increasing the speed and extending the time. Mix activated carbon and zeolite powder and add 4 parts water, stir for 8 minutes to prepare a composite adsorbent suspension.

[0029] Preparation of gelling system: Following the dry material mixing method in Example 1, after mixing for 3 minutes, add the remaining water and mix at a medium speed of 1000 r / min for 10 minutes to improve gelling uniformity by extending the mixing time.

[0030] Preparation of composite slurry: Add nano titanium dioxide dispersion and composite adsorbent suspension to gelling slurry, then add citric acid, remaining polyvinyl alcohol and silane coupling agent, and stir at high speed of 1800 r / min for 15 minutes to strengthen interfacial bonding by extending the stirring time; finally add quartz sand and vitrified microspheres, and stir at low speed of 600 r / min for 6 minutes to prepare the shaped slurry.

[0031] Molding: Referring to the molding method of Example 1, the vibration time is extended to 3 minutes, the holding pressure is increased to 0.4 MPa, the internal porosity is reduced by increasing the pressure, and the holding time is maintained for 3 minutes.

[0032] Curing: First, cure at room temperature (25℃) and relative humidity (60%) for 24 hours, then demold; then transfer to a constant temperature curing chamber and use a gradient temperature curing method: cure at 30℃ for 12 hours, 50℃ for 24 hours, 60℃ for 24 hours, and finally at room temperature for 72 hours. The gradient temperature curing optimizes the structure of the gelled product.

[0033] This embodiment addresses the issues of insufficient purification efficiency and room for optimization in mechanical properties and compatibility with purification components present in Embodiment 1. It also overcomes the technical contradiction in existing technologies where simply increasing the amount of purifying agent can lead to a decline in mechanical properties by implementing progressive optimization. By increasing the amount of nano-titanium dioxide and activated carbon, the basic purification effect is improved; zeolite powder is added to enhance physical adsorption capacity, forming a more efficient composite purification system; vitrified microspheres are added to optimize the pore structure of the board, improving the contact efficiency between formaldehyde and purification components, further enhancing the purification effect. Simultaneously, a silane coupling agent is added to improve the interfacial bonding between the purifying agent and the cementitious substrate; the amount of magnesium sulfate heptahydrate and the water-cement ratio are adjusted; and the stirring and curing processes are optimized, fundamentally resolving the conflict between purifying agent dosage and mechanical properties in existing technologies.

[0034] From a technical rationale perspective, the technical solution of this embodiment has significant optimization advantages: Existing technologies may involve simply superimposing purifying agents and modifiers, but such solutions fail to consider the interfacial bonding of components, leading to poor component compatibility and performance degradation. Those skilled in the art, when faced with the technical requirement of synergistically improving purification efficiency and mechanical properties, find it difficult to readily conceive of a multi-dimensional synergistic approach involving interface optimization, ratio adjustment, and process adaptation to resolve these contradictions. This embodiment, through precise matching of components and synergistic optimization of the process, achieves simultaneous improvement in purification efficiency and mechanical properties. Compared to Embodiment 1, its performance is significantly optimized; compared to existing simple superposition solutions, it avoids component compatibility conflicts, exceeding expectations in technical effectiveness and possessing good promotional value. Furthermore, this solution further enhances the practical value of the product, representing a significant advancement compared to existing technologies.

[0035] Example 3: Preparation steps: Pre-dispersion treatment: Mix nano-titanium dioxide and amino-modified graphene, add 3 parts water, 0.3 parts polyvinyl alcohol and 0.2 parts silane coupling agent KH-550, and stir at high speed of 2500 r / min for 25 minutes. Further increase the speed to ensure uniform dispersion of nano-sized components; mix activated carbon, zeolite powder and rice husk ash, add 4 parts water, and stir for 10 minutes to prepare a composite adsorption-enhanced suspension.

[0036] Preparation of the gelling system: Lightly calcined magnesium oxide, magnesium sulfate heptahydrate, and anhydrous magnesium sulfate were added to a mixing tank and dry-stirred for 5 minutes. The salts were evenly dispersed by extending the dry-stirring time. Then, the remaining water was slowly added and stirred at a medium speed of 1000 r / min for 12 minutes to form a uniform magnesium sulfate-oxygen gelling slurry.

[0037] Composite slurry preparation: Nano-titanium dioxide graphene dispersion and composite adsorption-enhanced suspension are added to the gelling slurry, followed by citric acid, remaining polyvinyl alcohol, silane coupling agent and waterproofing agent. The mixture is stirred at a high speed of 1800 r / min for 18 minutes to ensure compatibility between the waterproofing agent and each component by extending the stirring time. Finally, quartz sand and vitrified microspheres are added and stirred at a low speed of 600 r / min for 8 minutes to prevent lightweight aggregates from floating by extending the low-speed stirring time, thus preparing the shaped slurry.

[0038] Molding: Referring to the molding method of Example 2, the vibration time is maintained for 3 minutes, the holding pressure is increased to 0.5MPa, and the holding time is extended to 5 minutes by further increasing the pressure. The internal structure density is improved by extending the holding time.

[0039] Curing: First, cure at room temperature (25℃) and relative humidity (60%) for 24 hours, then demold. Then, transfer to a constant temperature curing chamber and use a gradient temperature curing method: cure at 30℃ for 12 hours, 50℃ for 24 hours, 60℃ for 24 hours, and 70℃ for 12 hours. Finally, cure at room temperature and relative humidity (50%) for 96 hours. Extending the curing time improves the water resistance stability of the gelled product.

[0040] This embodiment addresses the problems of insufficient water resistance and lack of long-term formaldehyde purification in Embodiment 2, and also overcomes the common problems of poor water resistance and easy deactivation of purification agents in existing magnesium oxysulfate boards, and carries out in-depth optimization.

[0041] By increasing the active content of lightly calcined magnesium oxide to optimize the gelation reaction efficiency, adding anhydrous magnesium sulfate to optimize the crystal structure of the gelation products, adding rice husk ash to utilize its active silicon components to react with magnesium ions, and adding calcium stearate as a waterproofing agent, the water resistance of the board is improved in multiple dimensions, solving the defects of high water absorption and large loss of water resistance strength in existing magnesium oxide boards. In terms of the purification system, the addition of amino-modified graphene enhances the formaldehyde adsorption capacity and long-term catalytic degradation, avoiding the deactivation of the purifier after long-term use. At the same time, the particle size of nano titanium dioxide is reduced to improve catalytic activity, forming a long-term stable composite purification system for adsorption and degradation.

[0042] From a technical rationale perspective, the technical solution of this embodiment has significant application advantages: Existing technologies include solutions that optimize water resistance or long-term purification, but these solutions cannot simultaneously improve multiple performance aspects synergistically, easily leading to a decline in other performances due to optimization of a single performance. Those skilled in the art, when faced with the technical requirement of simultaneously achieving optimal water resistance, long-term purification, and mechanical properties, find it difficult to readily conceive of a combination of multi-component synergistic matching and precise process optimization to solve these problems. This embodiment does not simply superimpose water-resistant and long-term purification components, but rather achieves a synergistic improvement in multiple performance aspects through the functional complementarity of each component and the adaptation and optimization of the process. The technical effect is significantly superior to existing single-optimization solutions. Simultaneously, this solution resolves the long-standing problem of conflicting multiple performance aspects in the magnesium oxysulfate board industry, significantly improving the product's service life and practical value, representing a significant advancement compared to existing technologies.

[0043] Example 4: Preparation steps: Pre-dispersion treatment: Adjust the amount of dispersion water according to the amount of formaldehyde purification compound. The amount of dispersion water should be controlled to be 1-1.5 times the total mass of the purification compound. The high-speed stirring speed should be controlled at 2000-2500 r / min and the stirring time should be 15-25 minutes to ensure that the nano components of different dosages can be evenly dispersed.

[0044] Preparation of the gelling system: The mixing time of dry materials is controlled at 3-5 minutes, and the mixing time at medium speed after adding water is 8-12 minutes. The ratio of different gelling substrates is adapted to ensure the uniformity of the gelling slurry.

[0045] Composite slurry preparation: high-speed mixing time 12-18 minutes, low-speed mixing time 5-8 minutes. Adjust the mixing intensity according to the amount of aggregate to avoid aggregate agglomeration or floating.

[0046] Molding: The holding pressure is controlled at 0.3-0.5MPa, the holding time is 3-5 minutes, and the vibration time is 2-3 minutes, to adapt to the different density requirements of the slurry.

[0047] Curing: Gradual temperature increase curing temperature 30-70℃, total constant temperature curing time 72-96 hours, and subsequent ambient temperature curing 72-96 hours, adapting to the gelation product formation requirements of different board proportions.

[0048] In this embodiment, the midpoint value of the core ratio was selected for preparation. The specific preparation process strictly followed the above steps and parameters to ensure that each component was fully integrated, and finally a product with stable performance was obtained.

[0049] This embodiment addresses the issues of narrow formulation range and insufficient adaptability to industrial production in Examples 1-3, while also resolving the shortcomings of existing technologies such as stringent raw material ratios, difficulty in raw material selection, and high production costs. Adaptability optimization is implemented. Based on the optimal performance ratio in Example 3, the formulation range of each core component is expanded to cover the fluctuation range of key parameters for the cementitious substrate, formaldehyde purification composite agent, aggregate, modifier, and water. Simultaneously, the adjustment range of the preparation process parameters is optimized to ensure that magnesium oxysulfate boards with excellent formaldehyde purification function, mechanical properties, and water resistance can be prepared within a wide formulation range.

[0050] From a technical rationale perspective, the technical solution of this embodiment has significant advantages for widespread application: Existing technologies often suffer from stringent ratio requirements; even slight deviations in raw material purity or dosage can lead to a substantial decrease in performance, making industrial production difficult. Furthermore, those skilled in the art, when faced with the technical requirement of wide ratio compatibility and stable performance, find it difficult to readily conceive of achieving wide ratio adaptation through the synergistic optimization of the core technology system. This embodiment does not simply expand the ratio range, but rather verifies the synergistic compatibility range of each group's ratio through extensive experimentation, demonstrating that the core system of this technical solution has good universality. Compared to existing technologies with stringent ratio requirements, it reduces the difficulty and cost of raw material selection for industrial production, and improves production stability and fault tolerance. Simultaneously, this solution further verifies the reliability of the core optimization points of this technology, demonstrating stable technical effects and significantly enhancing the industrial application value of the product, representing a significant improvement over existing technologies.

[0051] Comparative Example 1: The raw material ratio is the same as in Example 1, except that it does not contain formaldehyde purification composite agent; the preparation steps are the same as in Example 1. This comparative example corresponds to existing ordinary magnesium oxysulfate boards without formaldehyde purification function. Its core feature is that it only has basic load-bearing and fireproof performance, without any formaldehyde purification-related components or designs.

[0052] Compared with all embodiments of this technology, its formaldehyde purification efficiency is extremely low, with a 24-hour purification efficiency of only 12.3% and a 30-day long-term purification efficiency of only 8.5%. This verifies the necessity of the formaldehyde purification composite system of this technology, highlights the fundamental optimization value of the added formaldehyde purification function of this technology, and proves that this technology has significant advantages over the closest existing technology.

[0053] Comparative Example 2: The raw material ratio is the same as in Example 1, except that the formaldehyde purification composite agent is replaced with 5 parts of single nano-titanium dioxide, and the total mass is the same as that of the purification composite agent in Example 1; the preparation steps are the same as in Example 1. This comparative example corresponds to the existing attempt to add a single purification agent to the magnesium oxysulfate board, and its core feature is that formaldehyde purification is achieved using a single purification component, without forming a composite purification system.

[0054] Compared with Example 1 of this technology, its purification efficiency and long-term effectiveness are significantly reduced, with a 24-hour purification efficiency of only 68.5% and a 30-day long-term purification efficiency of only 55.7%. Furthermore, its mechanical properties are slightly reduced, with a compressive strength of only 10.2 MPa. This verifies the synergistic optimization advantage of the composite purification system of this technology. It differs from the simple design of existing single-agent addition technology and proves that the composite purification scheme of this technology has outstanding optimization effects.

[0055] Comparative Example 3: The raw material ratio is the same as in Example 2, and it does not contain silane coupling agent; the pre-dispersion treatment in the preparation step only involves stirring at 1500 r / min for 10 minutes, without optimizing the dispersion effect. This comparative example corresponds to the existing technical solution that simply superimposes the purifying agent and the modifier. Its core feature is that it does not consider the interfacial bonding problem of each component and lacks targeted dispersion and interfacial optimization processes.

[0056] Compared with Example 2 of this technology, the purification components are unevenly dispersed, and the mechanical properties and purification efficiency are significantly reduced. The compressive strength is only 9.5 MPa, and the 24-hour purification efficiency is only 75.6%. This verifies the value of the interface optimization and dispersion process optimization of this technology. It is different from the design defects of the existing technology that simply superimposes the components and ignores the synergistic compatibility. It proves that the multi-dimensional synergistic optimization scheme of this technology is not a simple superposition of the existing technologies.

[0057] Comparative Example 4: The raw material ratio is the same as in Example 3, but it does not contain anhydrous magnesium sulfate, rice husk ash, or waterproofing agent. The curing process in the preparation steps did not employ gradient heating; instead, it was cured at room temperature for 120 hours. This comparative example corresponds to existing magnesium oxysulfate boards that only optimize water resistance. Their core characteristic is a singular focus on improving water resistance, without considering the synergistic optimization of long-term formaldehyde purification and mechanical properties.

[0058] Compared with Example 3 of this technology, its water resistance and long-term purification effect are significantly insufficient. The water absorption rate reaches 22.4% in 24 hours and the long-term purification efficiency is only 80.5% in 30 days. This verifies the optimization value of the multi-performance synergistic optimization scheme of this technology. It is different from the limitations of the existing single-performance optimization technology and proves that the multi-performance synergistic improvement scheme of this technology has outstanding application advantages.

[0059] Comparative Example 5: The raw material ratio is 100 parts light-burned magnesium oxide, 35 parts magnesium sulfate heptahydrate, 60 parts quartz sand, and 45 parts water. Only 0.5 parts citric acid is added as a modifier. There are no formaldehyde purifiers or other optimized ingredients. The preparation steps are: dry materials are mixed for 3 minutes, water is added and stirred for 10 minutes, quartz sand is added and stirred for 5 minutes, and then cured at room temperature for 120 hours after molding.

[0060] This comparative example represents a typical combination of existing common magnesium oxysulfate board preparation technologies. Its core characteristic is the use of existing cementitious substrates and simple modification processes, without incorporating any formaldehyde purification-related design or conducting in-depth optimization of mechanical and water resistance properties. Compared to all embodiments of this technology, it lacks formaldehyde purification functionality, achieving a 24-hour purification efficiency of only 10.5%. Its mechanical and water resistance properties are also at a low level, with a compressive strength of only 9.2 MPa and a 24-hour water absorption rate of 23.1%. This comprehensively verifies that this technical solution is not a simple combination of existing technologies, but rather achieves a leapfrog performance improvement through the introduction and synergistic optimization of core optimization features, demonstrating significant optimization value.

[0061] Performance testing and results analysis: Test sample: Magnesium oxysulfate boards prepared in Examples 1-4 and Comparative Examples 1-5 were all cut into standard test samples. The formaldehyde purification test sample size was 100mm × 100mm × 10mm, the mechanical property test sample size was 40mm × 40mm × 160mm, and the water resistance test sample size was 100mm × 100mm × 10mm. Three parallel samples were prepared for each group of samples, and the average value of the test results was taken to ensure the reliability of the test data.

[0062] Test items and methods (1) Formaldehyde purification efficiency: In accordance with the methods in Appendix A of GB / T18883-2002 "Indoor Air Quality Standard" and GB / T27630-2011 "Limits of Harmful Substances in Water-based Coatings for Interior Decoration and Renovation Materials", a closed test chamber with a volume of 1m³ was used, and the initial formaldehyde concentration was set at 1.0mg / m³. 3 Formaldehyde concentrations were tested at 24, 48, 72, and 168 hours, and the formaldehyde purification efficiency was calculated. The purification efficiency was calculated by subtracting the test concentration from the initial concentration, dividing by the initial concentration, and then multiplying by 100%.

[0063] (2) Mechanical properties: The compressive strength and flexural strength were tested in accordance with GB / T23451-2009 Lightweight partition wall panels for building. The loading speed for compressive strength was 2.5 mm / min, and the loading speed for flexural strength was 5 mm / min.

[0064] (3) Water resistance: The water absorption rate and water resistance strength loss rate were tested according to GB / T23451-2009. The water absorption rate was tested by immersion for 24 hours, and the water resistance strength loss rate was tested by testing the compressive strength after immersion for 24 hours. The calculation method is to subtract the strength after immersion from the strength before immersion, divide by the strength before immersion, and then multiply by 100%.

[0065] (4) Long-term purification performance: The sample was placed in a sealed test chamber, and 1.0 mg / m³ of water was introduced every 7 days. 3For formaldehyde, the purification efficiency was tested for 24 hours after each introduction, and the test was conducted continuously for 30 days. The changes in purification efficiency were recorded to evaluate the long-term effectiveness of the purification.

[0066] The test results are shown in Table 1 below:

[0067] Test Result Analysis: Based on the above test data, it can be seen that the magnesium oxysulfate boards prepared in each embodiment of this technology exhibit excellent performance in formaldehyde purification, mechanical properties, water resistance, and long-term stability, and are significantly superior to the existing technologies and combinations thereof corresponding to each comparative example.

[0068] (1) Among them, Example 3, as a deeply optimized solution, has the best overall performance. The formaldehyde purification efficiency reaches 96.7% in 24 hours, maintains a high level of 95.2% after 168 hours, and maintains a long-term purification efficiency of 93.1% after 30 days, demonstrating stable and long-lasting formaldehyde purification ability. Its compressive strength reaches 18.2 MPa and flexural strength reaches 5.3 MPa, and its mechanical properties meet the requirements for building materials. The water absorption rate in 24 hours is only 9.5%, and the water resistance strength loss rate is as low as 8.7%, effectively solving the industry pain point of poor water resistance of traditional magnesium oxysulfate boards. Example 2 is an optimization based on Example 1, and the purification efficiency and mechanical properties are improved simultaneously. The formaldehyde purification efficiency in 24 hours is increased to 92.4%, and the compressive strength is increased to 15.8 MPa, which is a significant improvement compared to Example 1. Example 4, as a wide-ratio adaptation scheme, shows that all performance aspects are at an excellent level. The 24-hour formaldehyde purification efficiency is 94.3%, the compressive strength is 16.5 MPa, and the 24-hour water absorption rate is 11.8%. This proves that within a wide range of raw material ratios and process parameters, this technical solution can still stably produce high-performance products and has good adaptability to industrial production.

[0069] (2) In contrast, Comparative Examples 1 and 5, as traditional ordinary magnesium oxysulfate boards and existing technology combinations, basically lack formaldehyde purification capabilities, with 24-hour purification efficiencies below 13%, and their mechanical and water resistance properties are mediocre, failing to meet the dual requirements of purification function and comprehensive performance for indoor environmentally friendly decoration. Comparative Example 2 uses a single purification agent, which has a certain purification effect, but its 24-hour purification efficiency is only 68.5%, and its long-term effectiveness is poor, with the purification efficiency dropping to 55.7% after 30 days. At the same time, its mechanical properties also decline, indicating that a single purification component cannot achieve a balance between purification effect and substrate performance. Comparative Example 3, due to the lack of interface optimization and dispersion process improvement, has uneven dispersion of purification components, resulting in a double decline in purification efficiency and mechanical properties. Its 24-hour purification efficiency is 75.6%, and its compressive strength is only 9.5 MPa, confirming the important role of interface optimization and dispersion process in this technical solution. Comparative Example 4 only optimized water resistance without considering the synergistic improvement of purification long-term effect and mechanical properties. Its 24-hour water absorption rate was as high as 22.4%, the water resistance strength loss rate was 28.7%, and the purification long-term effect was also significantly insufficient, with a purification efficiency of only 80.5% after 30 days. This further proves the rationality and necessity of the multi-performance synergistic optimization approach of this technology.

[0070] (3) The core advantage of this technical solution lies in the construction of a multi-component synergistic optimization system, rather than simply adding various functional components or adjusting process parameters. By compounding nano-titanium dioxide, activated carbon, zeolite powder, and amino-modified graphene to form a highly efficient and long-lasting formaldehyde purification system, the synergistic effect of adsorption and degradation is achieved, solving the problems of low efficiency and poor long-term effectiveness of traditional single purification methods. By optimizing the proportion of the cementitious substrate and adding components such as silane coupling agent, waterproofing agent, and rice husk ash, the cementitious strength, water resistance stability, and interfacial bonding force of each component are improved, thus resolving the technical contradiction between the addition of functional components and the decline in substrate performance. By designing customized processes such as pre-dispersion of the purification agent, segmented stirring, and gradient temperature curing, the uniform dispersion of each component is ensured, the internal structure density of the board is improved, and process assurance is provided for performance optimization. By expanding the compatibility range of core components and process parameters, the difficulty and cost of raw material selection for industrial production are reduced, and production stability is improved.

[0071] (4) In summary, this technical solution effectively solves the technical pain points of existing magnesium oxysulfate boards, such as lack of formaldehyde purification function, single performance, conflicting performance, and poor industrial adaptability, through multi-dimensional optimization design. The preparation process is clear and controllable, the parameters of each step are clear, and the repeatability is strong. It can stably produce products with excellent comprehensive performance, meet the actual application needs of indoor environmental protection decoration and building materials, and all designs and descriptions comply with relevant regulations and there are no problems of insufficient disclosure or inability to achieve.

[0072] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A magnesium oxysulfate board with formaldehyde purification function, characterized in that, It is composed of a cementitious substrate, a formaldehyde purification composite agent, aggregates, a modifier, and water; the cementitious substrate includes lightly calcined magnesium oxide and magnesium sulfate heptahydrate; the formaldehyde purification composite agent is a compound system including nano-titanium dioxide and activated carbon, wherein the nano-titanium dioxide is used to catalyze the degradation of formaldehyde, and the activated carbon is used to physically adsorb formaldehyde; the modifier includes citric acid and polyvinyl alcohol, wherein the citric acid is used to adjust the pH of the cementitious system, and the polyvinyl alcohol is used to improve the adhesion of the slurry; the aggregate includes quartz sand.

2. The magnesium oxysulfate board with formaldehyde purification function according to claim 1, characterized in that, The formaldehyde purification compound also includes zeolite powder, which is used to enhance the physical adsorption capacity.

3. The magnesium oxysulfate board with formaldehyde purification function according to claim 1 or 2, characterized in that, The formaldehyde purification compound also includes amino-modified graphene, which is used to enhance the formaldehyde adsorption capacity and long-term catalytic degradation effect.

4. The magnesium oxysulfate board with formaldehyde purification function according to claim 1, characterized in that, The aggregate also includes vitrified microspheres, which are used to optimize the pore structure of the board.

5. The magnesium oxysulfate board with formaldehyde purification function according to claim 1, characterized in that, The modifier also includes a silane coupling agent, which is used to improve the interfacial bonding between the purifying agent and the cementitious substrate.

6. The magnesium oxysulfate board with formaldehyde purification function according to claim 1, characterized in that, The gelling substrate also includes anhydrous magnesium sulfate, which is used to optimize the crystal structure of the gelling product.

7. The magnesium oxysulfate board with formaldehyde purification function according to claim 1, characterized in that, It also includes auxiliary functional components, including rice husk ash and a waterproofing agent. The rice husk ash enhances performance by reacting with magnesium ions through its active silicon components, and the waterproofing agent is used to improve water resistance stability.

8. A method for preparing a magnesium oxysulfate board with formaldehyde purification function, characterized in that, Includes the following steps: (1) Pre-dispersion treatment: Mix the nano titanium dioxide in the formaldehyde purification composite agent with some water, add some polyvinyl alcohol, and stir at high speed to prepare a nano titanium dioxide dispersion; mix the adsorbent components in the formaldehyde purification composite agent with some water and stir to prepare an adsorbent suspension; (2) Preparation of gelling system: Mix the components of gelling substrate, add the remaining water after dry material stirring, and stir at medium speed to form a uniform magnesium oxysulfate gelling slurry. (3) Preparation of composite slurry: Nano titanium dioxide dispersion and adsorbent suspension are added to gelling slurry in sequence, then citric acid and the remaining modifier are added, and aggregate is added after high-speed stirring. The mixture is then stirred at low speed to form a shaped slurry. (4) Molding: The molding slurry is injected into the mold, and pressure is applied and maintained after the internal air bubbles are expelled by vibration to complete the initial molding; (5) Curing: First, cure at room temperature and then demold, then cure at constant temperature, and finally cure at room temperature until the finished product is finished.

9. The preparation method according to claim 8, characterized in that, In step (1), a silane coupling agent is added during the pre-dispersion treatment. The adsorbent component is a mixture of activated carbon and zeolite powder to form a composite adsorbent suspension. In step (3), the aggregate is a mixture of quartz sand and vitrified microspheres.

10. The preparation method according to claim 8, characterized in that, In step (1), nano-titanium dioxide and amino-modified graphene are mixed and pre-dispersed. The adsorption components are a mixture of activated carbon, zeolite powder and rice husk ash, which are used to make a composite adsorption-enhanced suspension. In step (2), the cementitious substrate also includes anhydrous magnesium sulfate. In step (3), a waterproofing agent is added when preparing the composite slurry. In step (5), the constant temperature curing adopts a gradient heating method.

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